FIELD OF INVENTION The invention relates to a slot racing system, and track pieces and slot cars used within such a slot racing system. Slot racing (also commonly termed “slot car racing” or “slotcar racing”) is a popular hobby or pastime which involves driving vehicles around a track comprising slots or grooves to guide these vehicles. The invention provides a slot racing system which has low manufacture costs, is suitable for use in a wide variety of environments and is very reliable.

BACKGROUND TO INVENTION

Conventionally, slot car racing involves driving miniature slot cars - usually in the form of model cars, trucks or other automobiles - along a track with slots or grooves in its upper surface. Slot cars commonly include a guide blade which extends beneath the slot car and can be inserted into a slot in the track. As the slot car is driven along the track it will travel along the slot in which the guide blade is received, the lateral movement of the slot car being restricted by the passage of the guide blade through the slot.

In traditional slot racing systems a slot car is driven by an electric motor. These electric motors drive wheels of the slot car and are powered by an external power source (e.g. mains electricity or other domestic power).

Electricity from the external power source is conducted along the track to a car travelling thereon by a pair of conductive rails positioned on the upper surface of the track such that they extend parallel to the slot and on either side of the slot. Together the conductive rails and the external power source form a circuit which may be closed by a slot car mounted in the slot. Electricity conducted along the conductive rails is conducted to the electric motor (so as to drive the slot car) by a pair of conducting brushes or braids provided on the underside of the slot car either side of the guide blade. Each conducting brush contacts a respective conductive rail so as to close the circuit formed by the rails.

The speed of a slot car may be controlled by the operation of a controller placed in this circuit. The controller is used to vary the amount of electrical power which flows along the conductive rails in the track. Hence, the power input to the electric motor of a slot car in a slot, and the speed of this slot car, is varied. Therefore, in conventional systems, conductive rails are required to supply power to a slot car and to control the speed of the slot car.

Careful control of the speed of a slot car by a user is required to race successfully. At high speeds a slot car will experience high centrifugal force in corners, causing the guide blade of the slot car to lift out of the slot in a track and the slot car to crash. This control requires a high level of skill. The “grip” a slot car has to the track (i.e. the force required to lift the guide blade out of the slot and for the slot car to become detached from the track) is in some cases controlled by providing a magnet in the underside of a slot car which is attracted to the material of the conductive rails.

A plurality of slot cars may be raced against each other by providing a plurality of slots, each slot being provided with its own conducting rails and a respective controller. Thus each slot car is raced in a respective slot and on a respective electrical circuit. It will be appreciated that in traditional analogue systems if two slot cars are placed in the same slot they will each receive the same electricity from the rails on either side of the slot and will travel at corresponding speeds and at a constant separation around a track (assuming the slot cars are otherwise identical).

Slot racing is a fast, exciting hobby or toy. Nevertheless existing slot racing systems have a number of drawbacks. Critically, the system itself is complex and expensive to manufacture. Producing a track with a slot and conductive rails positioned on either side of the slot is expensive, requiring high tolerances and significant labour.

Moreover, a step down transformer is necessary to convert mains or domestic electricity to safe voltages for transmission along the rails on the upper surface of the track. Such transformers are relatively expensive and contribute to a significant portion of the overall unit cost of a slot racing system. In addition, different transformers may be provided in different territories which may have different forms of mains or domestic power.

Slot racing systems can also be unreliable. This is especially true where a track is formed from a series of modular or connectable track pieces. In these examples electrical power must be reliably transmitted from one track piece to the next. However, ensuring electricity is effectively transmitted between track pieces can be difficult. To ensure effective transmission modular track pieces are traditionally constructed from hard, rigid plastics with solid metal rails so as to avoid deformation of the track pieces and to ensure an accurate connection between track pieces. However, the electrical and physical connections between these rigid track pieces are fragile and prone to damage (e.g. if accidentally stepped on). Furthermore, conductive brushes on the underside of conventional slot card degrade with use and must be replaced periodically.

In addition, conventional slot racing sets are limited in where they may be used and stored. Given the need to transmit of electrical power along the conductive rails, existing slot racing systems are unsuitable for use outdoors. Moreover, track pieces tend to warp over time since the different materials used for the conductive rails and the body track pieces have different coefficients of thermal expansion.

There is a desire to provide an improved slot racing system which overcomes at least some the disadvantages identified above. SUMMARY OF INVENTION

In place of the conventional slot racing systems described above, the inventors have recognised that by mounting a power source onboard a slot racer and by controlling each slot racer wirelessly there is no longer a requirement to provide conductive rails at the sides of the slot in the track. Moreover, by removing conductive rails the inventors have developed more flexible slot racing system that offers increased variety to users. According to a first aspect of the invention there is provided a slot racing system comprising: a slot racer comprising a power module configured to receive an onboard power source, a guide blade and a communication module configured to wirelessly communicate with an external controller; and, a track piece comprising at least one slot configured to receive the guide blade.

Thus the construction of the track pieces and the slot racer is dramatically simplified. This system avoids the need for conductive rails which extend along the slot racing track. Equally, there is no requirement for a slot car to comprise brushes or for wiring and a transformer to connect the mains or domestic supply to the track pieces. Consequently, the system is simplified, the material and labour associated with manufacturing the system are reduced and the system is more reliable. In addition, the system is made more portable and may be used in a wider variety of environments since it does not require rails to conduct electricity during use.

In the following description, each track piece will generally be described as having first and second opposing surfaces, being the major surfaces of the track piece, in at least one of which the slots are located. As such, these major surfaces form “racing surfaces” across which one or more slot cars may be raced. Each track piece will also generally be described as having first and second ends, being the sides of the track piece between which the slots extend in the surfaces, the first and second ends of a plurality of track pieces being configured to connect together to form a track. Finally, the track piece will generally be described as comprising edges, being the sides of the track piece that extend between the first and second ends and run generally parallel to the slots.

Slot racers are commonly referred to in the art as “slot cars”, and these terms are used interchangeably herein. Slot cars (i.e. slot racers) suitable for use in the invention may take the form of a conventional car, truck, van, train, boat or other vehicle. However, this is not essential and a slot racer may take other forms such as a character or person. Hence, the terms “slot racer” and “slot car” will be understood as devices with substantially any shape or form that comprise or receive a guide blade such that they may be driven around a track with a slot.

Preferably a slot car for use in the invention is a miniature or scale model of an existing or fictional vehicle. The slot car may be from 2 to 25 cm long, and preferably from 5 to 21 cm long. For instance, based on the sizes of conventional full scale cars: a 1/24 scale slot car may be from 17 to 21 cm long (and from 7 and 9 cm wide); a 1/32 scale slot car may be from 12 and 16 cm long (and from 6 and 7 cm wide); a 1/43 scale slot car may be from 7 and 12 cm long; finally a 1/64 or 1/78 scale slot car may be from 5 to 7 cm long.

A slot car may comprise a car body (used interchangeably herein with the term “racer body”) which forms a bulk or major portion of the slot car. The power module, onboard power source, communication module and any electric motor may be position within or on such a car body (i.e. racer body). The guide blade and axles of the slot car may project from the car body, such that the guide blade may enter a slot in a track and so that wheels may be mounted to the axles.

In some embodiments the car body may comprise an internal chassis and a separate body shell. The power module, onboard power source, communication module and other components may be provided on or within the chassis, whilst the guide blade may be mounted to the chassis. The body shell may be a cover or casing which is configured to attach to the chassis (e.g. for aesthetic purposes). For instance, the body shell may imitate a real or fictional vehicle. Moreover, the system may comprise a plurality of body shells, and the chassis may be configured to interchangeably connect to each of the body shells. As such the user may change the appearance of the slot car (e.g. from a car to a truck) without needing to replace the chassis. The body shells may preferably be interchanged by hand or alternatively with the use of a tool such as a screwdriver. However, alternatively, the car body may be a single unit, the outside of which takes the desired appearance (i.e. the car body may not comprise a separate chassis and body shell).

By an “onboard power source” it is understood that the power source is carried by the slot car (i.e. the slot racer) as it moves, e.g. as it travels or is driven along the track. This power source provides power to drive the slot car. For instance, the power source may provide power to a motor (e.g. electrical power to an electrical motor) that drives wheels of the slot car. The onboard power source may also provide power to the communication system.

In preferred configurations the onboard power source comprises an electric battery. Electrical batteries provide a convenient and reusable power source which can be fed to an electric motor. The electric battery may be rechargeable. For instance, the electrical battery may be recharged via a USB charging port (or an alternative connection) comprised within the slot car. Alternatively or additionally, the electric battery (or another power source) may be detachable from the power module such that it may be easily and quickly replaced. Suitable electrical batteries include commercially available standard batteries (e.g. an AA or AAA cell) which may be replaced or recharged when their power is depleted. Alternatively, other batteries may be used such as a single cell lithium battery or lithium ion battery.

Racing using the system discussed above is also more flexible. A slot car with an onboard power source may be driven in either direction along a track piece or around a track. This is different from traditional analogue slot racing systems where a slot car will only travel in a single direction along a track since the conductive rails in a track which have a pre-determined polarisation. In use the guide blade of the slot car may extend from the slot car into a slot of the track piece. The slot may be from 2 to 6 mm in width, preferably 3 to 5 mm in width and more preferably between 3.5 and 4.5 mm in width. The slot may be at least 8 mm in depth, preferably at least 10 mm in depth, more preferably at least 12 mm in depth, more preferably still at least 14 mm in depth. Such dimensions are well suited for use with slot cars at 1/24, 1/32 and 1/43 scale. The guide blade may have a smaller width than the slot such that the guide blade may be received in and freely move along the slot. Preferably the guide blade may rotate relative to the remaining components of the slot car (e.g. relative to a car body of the slot car), but this is not essential.

An external controller is preferably provided separate from the slot car. The external controller may be a purpose built controller such as a hand throttle (e.g. a wireless hand throttle). Alternatively, the external controller may be a smartphone, mobile telephone, a tablet, a personal computer or other general purpose user device. In particularly preferred embodiments such user devices may run an app which communicates wirelessly with the slot car.

The communication module and an external controller may be configured to communicate via electromagnetic waves (e.g. using radio waves, or an optical system). For instance, the communication module may be configured to wirelessly communicate via Bluetooth (RTM), Wi-Fi or any other suitable communication method.

In preferred configurations, the system is configured such that the track piece will not conduct power (e.g. electrical power) to the slot car. Since the slot car carries its own onboard power source an external power source is not required, and the track piece is preferably not configured to connect to an external power source. For instance, the track piece and/or the slot car may comprise an electrically insulating material, such that electrical power is not conducted from the track piece to the slot car. Equally, the slot car may not require or comprise electrically conductive brushes or braids found in conventional slot cars. By avoiding equipment necessary to conduct power from the track piece to the slot car the system may be made less complex and more reliable as discussed above.

In preferred configurations the track piece does not comprise conductive rails. Indeed, the track may be unpowered and/or may not be configured to connect to an external power source such as mains or domestic power supplies, and/or an electrical battery. Thus the cost and complexity of a track piece is reduced. However, in alternative configurations a track piece may comprise one or more slots with corresponding conductive rails. This may allow the track piece to be used with both slot cars with onboard power sources in accordance with the present invention and traditional slot cars which require conductive rails for power and control.

In preferred configurations the track piece comprises a material with a Shore D Hardness of less than 75, preferably less than 60, more preferably 45 or less. In further examples the Shore D Hardness may be less than 30 and/or greater than 10. The Shore D Hardness test provides a manner of determining the harness of relatively soft materials. Testing procedures to determine the Shore D Hardness of a material are laid down in technical standards ASTM D2240- 15e1 (ASTM International, ‘ASTM Volume 09.01 Rubber, Natural and Synthetic — General Test Methods; Carbon Black’, 2019, ISBN 978-1-6822-1561-6) and ISO 868:2003 (ISO, 7 SO 868:2003’, March 2003), the disclosures of which are incorporated by reference in their entirety.

These soft materials provide improved control of slot cars racing using the system. A soft material offers increased “grip” for slot cars in comparison to tracks formed of rigid materials (such as ABS, HIPS, wood and medium or high density fibreboards). In other words, guide blades are better retained in a slot and the slot cars are less likely to detach or decouple from a track piece when using a softer material than a hard material. Thus using a soft material may provide comparable effects to providing a magnet within the slot cars of traditional slot racing systems. In preferred examples the track piece comprises a polymer such as high impact polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), ethylene vinyl acetate (EVA) or rubber, or cork.

Elastomeric polymers such as ethylene vinyl acetate (EVA) and rubber, and cork are well suited for use in track pieces. These materials can be easily worked and formed, and are relatively soft (such that the guide blade of a slot car is well retained in a slot and the slot car is less likely to detach or decouple from the track piece in use). In addition, rubber, cork and many elastomeric polymers including EVA are electrical insulators. Hence, these materials will not transmit electrical power to a slot car on their own.

Alternatively, one or more track pieces may be formed of rigid materials. These may be quicker and cheaper to manufacture, and may be simpler to connect to one another during set up of a slot racing track. For instance, track pieces may be rapidly and cheaply manufactured by injection moulding using ABS, HIPS, PVC or another rigid polymer.

Preferably the slot car comprises a plurality of axles, and wherein the distance between the at least one slot and an edge of the track piece in a direction perpendicular to the slot is equal to or greater than the distance between the guide blade and an axle of the slot car furthest from the guide blade, and preferably at least 1.1 times the distance between the guide blade and an axle of the slot car furthest from the guide blade, more preferably at least 1.2 times the distance between the guide blade and an axle of the slot car furthest from the guide blade. For instance, the distance between the slot and the edge of the track piece on either side of the slot (and preferably on both sides of the slot) may be at least the length of the slot car, and preferably at least 1.2 times the length of the slot car.

A track piece of these widths is particularly useful in combination with slot cars in which the guide blade is configured to rotate relative to a car body of the slot car by large angles (e.g. at least 180 degrees, or at least 360 degrees such that the car body of the slot may rotate completely around the guide blade). Such slot cars may be used to imitate so-called drift racing cars. A large track border - i.e. a large distance between a slot and an edge of the track piece - will support the wheels of the slot car and avoid the slot car from falling from the track piece, regardless of the angle between the slot car and the slot in which the guide blade is received.

Thus the track piece is preferably sufficiently wide that the wheels of the slot car will not fall off the edge or side of the track piece when it is orientated perpendicular to the slot. This is of particularly beneficial when the slot is curved, since a slot car with a rotatable guide blade will tend to swing out from a curved slot (i.e. “oversteer”) under a centrifugal force when cornering.

Alternatively, or additionally, the system may comprise one or more border pieces, each of which is configured to be attached to or positioned adjacent to the track piece such that the racing surface across which a slot car travels is extended laterally. Thus the border pieces form a “skirt” that extends around the outside of the track pieces. Additionally, or alternatively, the system may comprise one or more barriers configured to extend upwards from the edge of a track piece so as to prevent a slot car from leaving the racing surface. Preferably, the track piece comprises one or more connectors at at least one edge, to which the barriers or border pieces may be connected. For instance, a track piece may be provided with a groove at at least one edge to which barriers and/or border pieces may be attached or clipped. The track piece may be provided with these connectors at an edge of the track even if the border or barrier pieces are sold separately as way to upgrade the user’s track. The barriers and/or border piece may be configured to detachably couple to the track piece. For instance, the track piece may comprise a groove at its edge to which the barrier or border piece may be attached or clipped. In further examples the border portions and/or barriers may be formed integrally with the track piece. Preferably the track piece comprises one or more slots in a first surface and one or more slots in an opposed second surface. Thus the track piece is reversible and a slot car may be raced on each surface. In effect, the track piece is made double-sided having two opposed “racing surfaces”. Slot racing systems comprising such track pieces can offer greater variety and a more challenging experience to users.

Preferably the first and second surfaces are different. In preferred configurations the first surface has a different texture, roughness, surface finish, surface coating and/or markings than the second surface. Additionally, or alternatively the first and second surfaces may vary by any other property. Thus the performance of the slot cars on each surface of the double-sided track may be different and/or the appearance of the track piece from each side may be different. Again variations between the racing surfaces of the track pieces (i.e. the surfaces over which the slot cars race) increases the variety provided by the slot racing system.

Preferably the track piece is of a cellular structure. Having a plurality of cells - i.e. voids or cavities - formed therein. Walls may extend between and separate the cells, forming the structure of the track piece. The use of such a cellular structure reduces the amount of material required to form a track piece whilst maintaining sufficient strength.

In particularly preferred examples at least one surface of the track piece comprises an open cell structure. The open cell structure may comprise a plurality of open cells or cavities which extend into the track piece from the respective surface. Each cell is open since it is accessible from the exterior of the track piece and is not closed by any material. The cells may be of consistent size and shape. The cells may be arranged in a regular and/or tessellating array. However, these features is not essential and in other examples the open cells may be irregular in size, shape or positioning. In preferred examples the open cell structure may comprise a plurality of hexagonal cells in a honeycomb structure. This provides high strength and minimises material usage. However, in further examples arrays of triangular, circular, or square cells, or cells of other shapes may be used.

It will be appreciated that forming one racing surface (or the majority of said surface) of the track piece as an open cell structure whilst the opposing racing surface is continuous (or substantially continuous across a majority of the opposing surface) provides different textures on each side of the track piece. Consequently, the performance of slot cars on each side of the track will be different - thereby affecting the racing experience using each side of the track piece and increasing variety for users. Preferably at least 50% of the first surface of the track piece comprises an open cell structure, more preferably at least 60%, more preferably still at least 80%. Whereas, preferably at least 50% of the second surface of the track piece is continuous and/or substantially planar, more preferably at least 60%, more preferably still 80%.

Alternatively, each of the first and second surfaces may comprise different open cell structures. For instance, the first surface may comprise a hexagonal (i.e. honeycomb) cell structure, whereas the second surface may comprise a square open cell structure.

During use, the array of cavities or recesses within an open cell structure may be filled with sand, dirt, ice or other materials to further affect the texture and performance of the track piece. For instance the cells may be filled with water and placed in a freezer before use to form an “ice track”. Whereas sand may be introduced into the open cell structure to imitate rally racing or other forms of motorsport.

In alternative examples, a track piece may comprise a closed cell structure in which cells are formed within the track piece only, and are not open to the outside of the track piece. Thus, unlike in the open cell structures discussed above, the cells forming the closed cell structure do not extend to an outer face of the track piece (e.g. the first or second surfaces) and are not fluidly connected to the exterior of the track piece. As discussed above, this may achieve a reduction in material requirements for the track piece, but may not affect the texture of the racing surfaces of the track piece.

Preferably the one or more slots in the first surface follow different paths than the one or more slots in the second surface. Such a double-sided track piece again offers different experiences when racing on each side of the track piece. For instance the same track piece can provide different layouts for racing by using its opposing (i.e. its reverse) side.

In particularly preferred examples at least one of the slots in the first surface is not parallel to at least one of the slots in the second surface. For example, the slots in the first surface may be straight, whereas one or more slots in the second surface may be curved (e.g. to provide a chicane). Additionally or alternatively, the one or more slots in the first surface may be laterally offset from the one or more slots in the second surface.

In further preferred embodiments the number of slots in the first surface of the track piece may be different from the number of slots in the second surface. For instance the first surface of the track piece may comprise two slots, whereas the second surface of the track piece may comprise three or four slots. Therefore different numbers of participants may compete on each side.

Equally, the dimensions of the one or more slots in the first surface may be different from the dimensions of the one or more slots in the second surface. Additionally or alternatively, where multiple slots are provided in each surface, the lateral distance or spacing between the slots in the first surface may be different from the lateral distance or spacing between the slots in the second surface. As such, the opposing sides of the track piece may be suitable for use with slot cars of different sizes. For instance, the slots in the first surface of the track may be suitable for slot cars at 1/24 and/or 1/32 scale whereas the slots in the opposing second surface may be suitable for slot cars at 1/43, 1/64 and/or 1/78 scale. Alternatively, changing the spacing between slots may be used to deliberately bring slot cars racing on adjacent slots into contact to provide increased excitement.

The differences in both the surface properties of either side of the track piece and the arrangement or layout of slots in each surface of the track piece can increase the variety of tracks that can be created using each track piece.

In preferred embodiments, the thickness of the track piece less than 3 times the average slot depth, preferably less than 2.5 times the average slot depth, more preferably less than 2 times the average slot depth. Having a low thickness reduces the material required to produce a track piece. However, sufficient thickness is necessary to ensure enough structural strength.

Where the thickness of the track piece is equal to the slot depth (such that the track piece is one times the slot depth), a slot will extend through the track piece from a first surface to an opposed second surface. As such the track piece may comprise one or more slots formed continuously between the opposed first and second surfaces of the track piece. As such, a slot extending through the track piece may divide the track piece into separate parts. These separate parts may be connected by a further connecting component (e.g. adhesive tape). Alternatively, if the depth of the slot or the thickness of the track piece varies, the slot may only extend completely through the track piece in a specific location(s) along the length of the slot.

Similarly, where the thickness of the track piece is between 1 and 2 times the average slot depth, a slot formed in the first surface and a slot formed in the second surface of the track piece will intersect and form a continuous slot through the track piece in regions where the slots are not offset laterally (i.e. where the slots in the opposed surfaces are overlapped or coincident).

As discussed above, the one or more slots in the first surface may be laterally offset from the one or more slots in the second surface. Thus the slots in each surface may be offset or separated in a direction which is substantially perpendicular to the direction in which the slots extend into the track piece. As such, the overall thickness of the track piece may be reduced without resulting in a hole or aperture extending through the track piece (i.e. an aperture extending continuously from the first surface of the track piece to the second surface of the track piece formed by overlapped or superimposed slots). Therefore, the material required for the track piece can be reduced without impacting the strength or performance of the track piece. Having said this in further examples, slots in the opposed sides of a track piece that has a thickness less than or equal to two times the average slot depth may cross in places without impacting the structural integrity of a track piece so long as the slots are not coincident or superimposed over a relatively long distance.

In preferred configurations the system may comprise a plurality of track pieces, preferably interconnecting track pieces. Each of these track pieces may comprise any of the preferable features discussed above.

Preferably the plurality of track pieces may be connected such that the one or more slots extend continuously between adjacent track pieces (i.e. from one track piece to the next). Therefore, a slot car may be raced across the surface of both track pieces. In preferred examples, a plurality of track pieces may form a modular race track which may be assembled or connected together in a variety of layouts. However, this is not essential and the track pieces may only be connected in a single layout. Equally in some embodiments a single track piece may form a race track on its own.

For example, the system may comprise a plurality of straight track pieces which extend in a single direction, and a plurality of curved track pieces which may be interconnected to form a wide variety of layouts. The length of the track pieces in a given system may be varied to provide increased flexibility (e.g. straight track pieces of different lengths may be provided and/or curves of different radiuses or arc lengths may be provided). Alternatively, the system may be provided with a plurality of track pieces of a constant length and curves of a fixed arc length (e.g. 45, 60 or 90 degree curves) so as to simplify construction of different continuous track layouts (where the final track piece meets the starting track piece). In particular, it is particularly easy to create a wide variety of interesting tracks when using a system that comprises straight track pieces and 60 degree curves only.

Preferably the system may comprise a plurality of interconnecting track pieces, wherein a first track piece of the plurality of track pieces may be connected to a second track piece in a first arrangement where a first surface of the first track piece meets the first surface of the second track piece and in a second arrangement in which the first surface of the first track piece meets a second surface of the second track piece. Therefore, the second track piece is reversible in relation to the first track piece and may be raced on either side.

In preferred configurations the system comprises a plurality of interconnecting track pieces, wherein each track piece of the plurality of track pieces comprises one or more slots in its respective first surface and one or more slots in its respective opposed second surface; wherein a first track piece and a second track piece of the plurality of track pieces comprise connection portions, the connection portions being configured such that the first track piece may be connected to a second track piece in at least four different arrangements, wherein: in a first arrangement the first surface of the first track piece meets the first surface of the second track piece, and a first end of the first track piece is connected to a first end of the second track piece; in a second arrangement the first surface of the first track piece meets the first surface of the second track piece, and the first end of the first track piece is connected to a second end of the second track piece; in a third arrangement the first surface of the first track piece meets the second surface of the second track piece, and the first end of the first track piece is connected to the first end of the second track piece; and in a fourth arrangement the first surface of the first track piece meets the second surface of the second track piece, and the first end of the first track piece is connected to the second end of the second track piece; and wherein the slots of the first track piece and the second track piece are configured such that in each of said arrangements the slots in the respective coplanar surfaces are continuous.

Therefore, a second track piece may be attached to a first track piece in four different arrangements in which slots extend continuously between the surfaces of the first and second track pieces. Hence slot cars can be driven from one track piece to the next regardless of the orientation of the two track pieces relative to one another. In preferred configurations the (racing) surfaces of the first and second track pieces which meet may be coplanar or substantially coplanar (especially when the track pieces are laid out on a flat surface). This is particularly valuable where the opposing surfaces of one or more of the track pieces have different properties and/or the slots in each surface follow different paths. Different textures, roughnesses surface finishes, surface coatings, markings and/or slot layouts may be interchanged by varying the manner in which the track pieces connect.

Equally the layout of a track may be varied by changing the manner in which track pieces connect. As with the previous example, the second track piece may be flipped over or reversed relative to the first track piece (e.g. to reveal a racing surface with different surface properties or a different layout of slots) without preventing a slot car from travelling along a slot and without creating a break or discontinuity in the combined race track. In addition, the second track piece may be rotated in the plane of the second track piece to (for instance) convert a left handed corner to a right handed corner. As such, the second track piece is not chiral and may be raced in left-handed and right-handed arrangements on either surface.

In more detail, it will be seen that the difference between the first and the second arrangements is that the second track piece is rotated about a first axis normal to the plane in which the track piece extends. For instance if the second track piece is a straight track piece it may be rotated by 180 degrees relative to the first track piece between the first and second arrangements. Whereas a second track piece with a 90 degree bend may be rotated by 90 degrees, and a second track piece with a 45 degree bend may be rotated by 45 degrees relative to the first track piece between the two arrangements. Equally a second track piece with a 60 degree bend may be rotated by 60 degrees relative to the first track piece. The first and third arrangements differ in that the track piece is rotated by 180 degrees about a second axis parallel to a direction in which the track piece extends. Finally, the difference between the first and fourth arrangements is a combination of the differences between the first and second arrangements and the first and third arrangements. In other words, the second track piece is rotated about both the first and the second axis between the first and fourth arrangements.

Preferably, the connection portions and slots of the first and second track pieces are configured such that the second track piece may be connected to the first track piece in four corresponding arrangements. Indeed, in particularly preferred embodiments the connection portions and slots of each of the plurality of track pieces are configured such that any first track piece of the plurality of track pieces may be connected to any second track piece of the plurality of track pieces in the four arrangements discussed above.

These embodiments discussed above simplify the construction of a race track and may provide increased variety in the race track (e.g. if the first and second surfaces of the second track piece or the slots in these surfaces are different).

In preferred examples each track piece of the plurality of track pieces may comprise connection portions at each of its respective ends. As mentioned above, these connection portions may allow the track pieces to be connected together. For instance, each track piece may comprise one or more male connection portions and one or more one female connection portions. The male connection portions of a first track piece (e.g. any first track piece) may be configured to be received in the female connection portion of a second track piece (e.g. any second track piece). Additionally, the male connection portions of the second track piece may be configured to be received in the female connection portion of the first track piece. As such, all track pieces preferably comprise the same or similar connection portions at each of their ends. Preferably the connection portions are formed integrally with the track piece - i.e. the connection portions and track piece are connected or formed continuously such that the connection portions may not be detached or separated from the track piece.

By “male” and “female” it will be understood that each male connection portion may couple or attach to a female connection portion of another track piece and not with another male connector and vice versa. In other words, connection portions of dissimilar gender may be coupled together, but connection portions of similar gender may not. However, in particularly preferred embodiments there are provided track pieces that each comprise male and female connection portions, the connection portions configured such that male connection portions may be received within female connection portions of further track pieces.

Preferably the female connection portions of each track piece are configured to correspond to a male connection portion of said track piece, being of corresponding size and shape to the male connection portion, such that the female connection portions of each track piece may receive the male connection portion of further track pieces with the same connection portions (and vice versa). One or more male connection portions and one or more female connection portions may be provided at each end of the track pieces. Preferably the number of male connection portions and the number of female connection portions at each end of the track pieces correspond.

At each end of a track piece, the connection portions and the slots may be rotationally symmetric about an axis parallel to the direction in which said track piece extends local to the respective end of the track piece (e.g. normal to the respective end faces of said track piece). Preferably the connection portions and slots are rotationally symmetric about a centreline of the track piece. Preferably the connection portions and slots at each end of the track piece have rotational symmetry of order 2. Preferably the same or corresponding connection portions are provided at each end of the track piece. These features enable track pieces formed with such connection portions and slots to be arranged in the four different arrangements discussed above and for slot racers to be raced across multiple track pieces regardless of which arrangement the track pieces are placed in.

Preferably each track piece comprises at least two male connection portions and at least two female connection portions at each end. The male and female connection portions on each end are preferably arranged in pairs exhibiting rotational symmetry about an axis parallel to the direction in which said track piece extends local to the respective end of the track piece. For example, on each end of the track piece a first male-female connection portion pair may be provided towards an outside edge of the track piece and a second male-female connection portion pair provided towards an inside edge of the track piece, the second male-female connection portion pair on the first end being flipped relative to the first male-female connection portion pair on the first end. Additionally, the first male-female connection portion pair on the first end is flipped relative to the first male-female connection portion pair on the second end and the second male-female connection portion pair on the first end is flipped relative to the second male-female connection portion pair on the second end. Providing even numbers of male and female connection portions at each end of the track piece allows the connection portions to be arranged with rotational symmetry of order 2 about an axis parallel to the direction in which the track piece extends. For instance, each track piece may be provided at each end with 2, 4, 6, 8 or any other even number of male and female connection portions. This may allow each track piece to be connected to an adjacent track piece in four different orientations (arrangements).

Preferably each male connection portion projects or extends from an end surface of the track piece along a direction parallel to the direction in which the track piece extends at the end at which the male connection is formed (e.g. normal to an end surface of the track piece). Equally, each female connection portion preferably comprises a recess or cavity that extends into the track piece from the end surface of the track piece along a direction parallel to the direction in which the track piece extends.

Additionally, each of said male connection portions preferably comprises one or more projections that extends from the male connection portion along a direction that is perpendicular to the direction in which the track piece extends at the end in question. The female connection portion preferably comprises corresponding receiving cavities each of which is configured to receive a respective projection from the male connection portions. The female connection portions preferably extend along a direction that is perpendicular to the direction in which the track piece extends. Such projections and cavities formed on the male and female connection portions may be configured to interlock in use, creating a strong attachment between connected track pieces restricting unwanted movement between track pieces. These interlocking projection and cavities are particularly valuable where the track pieces are formed of rigid materials such as ABS or PVC.

Preferably the male and female connection portions are tapered or dovetailed. In such embodiments the width of the male connection portion increases continuously or discontinuously along a direction from the free end of the male connection portion to the end of the male portion attached to the respective track piece, whereas the width of the female connection portion increases continuously or discontinuously as distance from the surface in which the female portion is formed increased.

Nevertheless, embodiments which comprise male and female connection portions may also be formed of soft and/or elastic track piece materials (such as EVA, rubber and cork, as discussed above). In these examples the male and female connection portions may be easily attached and detached easily by hand, but will still provide a strong connection between track pieces.

Preferably each track piece comprises one or more male connection portions and a corresponding number of female connection portions at each end. Increasing the number of connection portions may improve the attachment between connected track pieces through increased friction or mechanical interference which can restrict undesirable movement between track pieces during use. For instance, each track piece may comprise two or more male connection portions and two or more female connection portions.

Despite the discussion above, track pieces which form continuous slots when connected in different arrangements (i.e. orientations) are not essential. In further embodiments the connection portions and/or slots may be configured such that the track pieces may be combined or attached in a single arrangement or in only two arrangements. For instance, in some configurations, it may not be possible to connect a right-handed corner track piece in a manner such that it forms a left-handed corner and vice-versa.

In preferred configurations the onboard power source comprises an electric battery. The electric battery may be rechargeable or replaceable. For instance, the electrical battery may be recharged via a USB charging port (or an alternative connection). Alternatively, the electrical battery may be a commercially available standard battery (e.g. an AA or AAA cell, or a lithium or lithium ion battery) which may be replaced or recharged when its power is depleted. Electrical batteries provide a convenient and reusable power source which can be fed to an electric motor. However, in alternative examples any other suitable power source may be used. The slot car may comprise any suitable motor or other drive component. For instance the slot car may comprise an F130 or N30 motor, available from a variety of miniature toy manufacturers.

In preferred embodiments the slot car comprises at least one tyre formed of natural rubber, synthetic rubber, silicone or a sponge polymer. Preferably all tyres of the slot car are formed of natural or synthetic rubber, silicone or a sponge polymer. These materials provide good adhesion or grip between the slot car and a track piece. However, in alternative embodiments other materials may be used for tyres. Preferably the tyres are selectively detachable from wheel hubs on which they are mounted (e.g. such that they may be removed and replaced as necessary). In addition, preferably the wheel hubs are quick- release wheel hubs, such that they are selectively detachable and may be easily attached and removed from the axles of the slot car manually and without the need of any tool (however, this is not essential).

Preferably the slot car comprises a car body, wherein the guide blade is selectively detachable from the car body. By selectively detachable it will be understood that the guide blade may be detached and reattached to the car body manually and without the use of a tool. For instance, the guide blade may be attached to the car body by a clip or other fastener which may be operated by hand. Selectively detachable guide blades may quickly and easily interchanged (e.g. to fit alternative tracks and/or slots, or to replace worn guide blades) or removed entirely (e.g. such that the slot car may be used for racing in a straight line similar to drag racing for conventional automobiles).

Preferably, the slot car comprises a car body, and the guide blade is configured to rotate relative to the car body. For example the guide blade may freely rotate relative to the car body about an axis that is perpendicular to the direction in which the car body extends (i.e. perpendicular to the surface on which the car body may race across). Thus the car body of the slot car will swing out under centrifugal force as the slot car turns around a corner at high speed, similar to oversteer on a traditional vehicle. This increases excitement when racing the slot car and increases the skill required to race slot cars.

In alternative embodiments the guide blade may be detachably coupled to the car body using fixings (e.g. screws) such that a tool is required to remove the guide blade. Equally, the guide blade may be permanently coupled to the car body - e.g. using adhesive or by forming the guide blade and car body as a single component.

In preferred examples the slot car comprises a car body, and the guide blade is changeable between two modes, wherein: in a first mode the guide blade is configured to rotate relative to the car body over a range of at least 180 degrees, and preferably at least 360 degrees; and in a second mode the guide blade is configured to rotate relative to the car body between limits that are separated by a maximum of 180 degrees, preferably by a maximum of 150 degrees, more preferably by a maximum of 120 degrees, more preferably still by a maximum of 90 degrees.

In the first mode the car body of the slot car may rotate relative to the guide blade within a relatively large angle range and preferably may rotate entirely around the guide blade. This may allow the slot car to imitate so-called “drift cars”, such that it will exhibit large amounts of oversteer with the rear of the slot car swinging out under centrifugal force when cornering. Equally, the ability to rotate the car body completely around the guide blade may allow the slot car to be raced in either direction along the same slot.

In contrast, when the slot car is in the second mode the car body may rotate within an angle range that smaller than the range in the first mode. As such, the ability for the car body of the slot car to swing away from a slot during racing is restricted.

The handling of a slot car in the two different modes will be very different. As such slot cars using a guide blade which may be set in different modes with different limits to its rotation relative to the car body offers an increased variety of racing experiences.

The guide blade may be changed between the two modes mechanically (e.g. using a lock, latch or other component which restricts the movement of the guide blade) or electronically using a switch mounted on the slot car. In a particularly preferred embodiment the guide blade may be detachably mounted on the car body at two separate mounting locations, such that: when mounted to the car body in a first location the guide blade may be capable of rotating in a relatively large angle range (e.g. over at least 180 degrees); and, when mounted or attached to the car body in a second location where the guide blade is capable of rotating in a relatively small angle range (e.g. less than 150 degrees). Preferably the guide blade comprises two opposed longitudinal faces, wherein at least one of the longitudinal faces comprises a surface relief or texture configured to contact an internal surface of the slot and restrict movement of the slot car normal to the track piece when the guide blade is received in the slot. Thus the slot car is better retained in the slot, and is less likely to be detached (e.g. when cornering). Therefore the difficulty of racing using the system may be controlled and the enjoyment of racing increased.

This increase in “grip” between the slot car and the track piece (i.e. the force required to lift the guide blade from the slot so as to separate the slot car from the track piece) is achieved without the need for the metal rails and magnets used in conventional systems.

For instance, the longitudinal surfaces may comprise longitudinal fins or other projections which extend or protrude from the respective longitudinal surfaces. If the slot car is lifted from or tilted within the slot (e.g. under centrifugal force when cornering) the protrusions will contact a side of the slot and mechanically interfere or restrict the movement of the car.

Preferably wherein the guide blade extends at least 8 mm from a car body of the slot car, preferably at least 9 mm, more preferably at least 10 mm, more preferably still at least 12 mm. Increasing the length of the guide blade further increases the forces required to lift the guide blade from the slot during racing and makes it more difficult for the slot car to be separated from the track piece (i.e. the grip between the slot car and the track is increased). Therefore, the difficulty of racing using the system may be controlled by varying the length of the guide blade so as to maximise enjoyment of the system. The lengths of 9mm, 10mm and 12mm discussed above may be suited for slot cars at (for instance) 1/24, 1/32 and 1/43 scale. However, in further embodiments guide blades of alternative sizes may be used. In preferred embodiments, the slot car comprises a car body, and the clearance height between the car body and a surface on which the slot car stands decreases in a longitudinal direction from a leading edge and/or a trailing edge of the car body towards the centre of the car body. For instance, the leading edge of the underside of the car body may be rounded, chamfered or tapered. Additionally or alternatively, the trailing edge of the underside of the car body may be rounded, chamfered or tapered. For instance, the leading edge and/or a trailing edge of the chassis of a car body may be rounded, chamfered or tapered. Thus if the slot car reaches a protrusion or raised section in the track, as may occur at the boundary between adjacent track pieces if the surfaces of the track pieces are not accurately aligned, the slot car may traverse the protrusion without crashing or becoming detached from the track even if the protrusion is greater in height than the minimum clearance distance between the car body and the track surface (i.e. the surface on which the slot car stands). Therefore, such slot cars are suitable for use with a wider variety of tracks, including tracks formed on uneven surfaces (e.g. outdoors) and the system is suitable for use in a wider variety of environments. In contrast a slot car with a flat or planar underside of constant clearance height is more likely to crash (i.e. detach from its slot) if the slot car encounters a protrusion which is greater than its clearance distance.

In preferred examples the slot car comprises a drive motor, a driven axle to which the drive motor is connected and a freely-rotating axle; wherein the distance between the centre of mass of the slot car and the driven axle is less than the distance between the centre of mass of the slot car and the freely- rotating axle; wherein preferably the distance between the centre of mass of the slot car and the driven axle is less than two-thirds the distance between the centre of mass of the slot car and the freely-rotating axle, more preferably less than half of the distance; more preferably still less than a third of the distance.

By arranging the centre of mass of the slot car close to or over the driven axle the force applied to the wheels attached to the driven axles and the contact between these driven wheels and the surface of the track piece is increased. This reduces the chance these driven wheels slip or lose traction on the surface of the track piece, and provides greater control to a driver and increases the enjoyment of the slot racing system. The position of the centre of mass may be controlled by (for instance) varying the position of an electric motor, electric battery or other components within a car body of the slot car.

For instance, in preferred embodiments the electric motor may be positioned substantially in line with (e.g. over) the driven axle, or on an opposing side of the driven axle to the freely-rotating axle. Equally, the electric battery may be provided between the driven axle and the freely-rotating axle, in line with (e.g. over) the driven axle, or on an opposing side of the driven axle to the freely- rotating axle.

The electric motor, electric battery and/or other components may also be provided close to a base or underside of the car body to lower the centre of gravity of the slot car as a whole. This reduces the chance that the slot car will overturn (e.g. when cornering).

In preferred examples the slot car is waterproof and/or weatherproof. As such, a car body of the slot car is sealed such that liquids such as water cannot enter the car body. This increases the range of environments the slot racing system can be used. In particular, the combination of unpowered track piece(s) which do not conduct electrical power, and slot cars that are waterproof and/or weatherproof means that all electrical components in the system are protected from their environment. Therefore, the system is well suited for use outdoors as well as indoors. For instance, the car body may be manufactured to the IP54 standard as defined in European standard EN 60529 and international I EC standard 60529 (I EC 60529, Edition 2.2, 2013), such that the car body is protected from at least limited dust ingress and protected from water spray from any direction.

In further embodiments the slot car may comprise a car body configured to connect to parts of interlocking studded brick systems (e.g. Lego (RTM), or MegaBlox (RTM)) or another construction system. For instance a surface of the car body may be provided with studs configured to connect to blocks of a construction system. In further embodiments the system may comprise adhesive stickers suitable for application to the slot car and/or track piece. Therefore a user may personalise or modify the appearance of the slot car.

In further embodiments the slot car may comprise selectively detachable wheel hubs and/or tyres. For instance, the slot car may be provided with quick-release wheels which may be selectively detached and attached manually and without the need for any tools. As such, the wheel hubs and/or tyres may be switched or replaced to modify the performance of the slot car (e.g. to suit specific racing conditions) or for aesthetic reasons. Additionally or alternatively, the slot car may be configured such that the distance between its axles may be varied. For instance the position of one or more axles of the slot car may be changed (i.e. said axle(s) may be arranged at a plurality of positions along the length of the car body of the slot car). Again these changes may be performed to modify the performance of the slot car or for aesthetic reasons.

In preferred embodiments the system comprises: a plurality of slot cars, each comprising an onboard power source, a guide blade and a communication module configured to wirelessly communicate with an external controller; a track piece comprising a plurality of slots each configured to receive the guide blade of a respective one of the plurality of slot cars.

Thus the slot cars may be raced against each other along their corresponding slots. Each of the plurality of track pieces may comprise any of the preferable or optional features of track pieces discussed above. Similarly, each of the plurality of slot cars may comprise any of the preferable or optional features of slot cars discussed above.

In some examples, each slot car may each be controlled by a respective external controller. However, alternatively multiple slot cars may be controlled by a single external controller - e.g. multiple users may share a single tablet or mobile computer. The slot cars may be controlled by a mixture of purpose built controllers (e.g. a wireless hand throttles) and general purpose user devices (e.g. smartphone, mobile telephone, tablets or computers). In other words at least one slot car of the plurality of slot cars may be controlled by a wireless hand throttle or other purpose built controller, and at least one slot car of the plurality of slot cars may be controlled by a smartphone, mobile telephone, tablet, personal computer or other general purpose user device.

In further embodiments, the system may comprise a different number of slot cars than slots. For instance, in some embodiments the system may comprise a greater number of slot cars than slots, wherein multiple slot cars may be raced along the same slot sequentially, such that a single slot is configured to receive the guide blade of multiple slot cars simultaneously. In these examples, the slot cars may be controlled and raced independently despite running along the same slot because each slot car comprises a separate onboard power source and a separate communication module. For instance the claimed system may be used to provide a “chase” between multiple cars on the same slot.

Racing in this manner - where the system is configured such that a plurality of identical slot cars may be controlled to travel at different speeds along a single slot - is unachievable using traditional analogue slot racing systems that utilise conductive rails, because in conventional systems each slot car in a given slot will receive the same power from the conductive rails and travel at similar speeds along the slot (assuming the slot cars are substantially identical).

According to a further aspect of the invention, there is provided a track piece comprising at least one slot configured to receive the guide blade, the track piece being suitable for use in any of the slot racing systems according to the first aspect of the invention and discussed above. The track piece may comprise any of the preferable or optional features of track pieces discussed above with reference to the first aspect of the invention and offer corresponding benefits. According to further aspects of the invention there is also provided slot racing track systems comprising a plurality of track pieces as discussed with reference to the previous aspects of the invention. Such slot racing track systems may in some cases be sold separately from the slot racers (i.e. slot cars) that will be raced on the tracks formed using these systems.

According to a further aspect of the invention, there is provided a slot car comprising an onboard power source, a guide blade and a communication module configured to wirelessly communicate with an external controller, the slot car being suitable for use in any of the slot racing systems according to the first aspect of the invention and discussed above. The slot car may comprise any of the preferable or optional features of slot cars discussed above with reference to the first aspect of the invention.

It will be appreciated that slot cars in accordance with the invention which comprise an onboard power source (e.g. batteries carried on or in the slot car) may still be raced on the tracks of conventional slot racing systems assuming that the guide blades of the slot cars in accordance with the invention can be received in the slots in the track of the conventional system. However, unlike conventional slot cars, the slot cars according to the invention will not draw power from the track. In other words, slot cars according to the invention will not receive electrical power from conductive rails on either side of a slot.

BRIEF SUMMARY OF DRAWINGS

Figures 1a and 1b show a slot racing system according to the invention schematically from the side and front respectively.

Figure 2a shows a straight track piece according to the invention in a perspective view; Figures 2b and 2c show the opposing sides of a track piece in plan view. Figure 3a shows a curved track piece according to the invention in a perspective view; Figures 3b and 3c show the opposing sides of the track piece in plan view. Figures 4a and 4b show cross sections of respective track pieces according to the invention.

Figure 5a shows a plan view of a slot car according to the invention from above; Figure 5b shows a reverse plan view of the underside of the slot car.

Figure 6a and 6b show a guide blade component in perspective and elevation views respectively.

Figure 7 shows a cross section through a portion of the slot car exhibited in Figures 5a and 5b.

Figures 8 to 11 show perspective views of four alternative embodiments of connection portions of track pieces for slot racing according to the invention.

Figures 12a and 12b show opposing sides of a curved track piece in accordance with the invention in plan view; Figure 12c shows a perspective view of this track piece.

Figure 13 shows invention in perspective view a slot racing track system in accordance with the invention.

Figure 14 shows in perspective view a further slot racing track system in accordance with the invention.

DETAILED DESCRIPTION

Figure 1a and 1b show schematically a slot racing system according to the invention. The system comprises a slot car 10 (i.e. a slot racer) and a track piece 20, the slot car 10 being positioned on a surface 21 of the track piece 20. As shown, the slot car 10 has the form of a miniature or scale version of a full size car. The slot car 10 comprises a car body 11. Within the car body 11 (i.e. the racer body) are provided an onboard power source 12 (e.g. an internal battery), a communication module 14 (e.g. a Bluetooth (RTM) module) and a motor 15 (e.g. an electric motor). The onboard power source 12 supplies power to the communication module 14 and motor 15, and is received in a power module (e.g. a battery may be received or retained in a battery compartment). These internal features that are positioned within the car body 11 are shown using dashed lines in Figure 1a.

The slot car 10 further comprises a guide blade which extends (or projects) from the underside 11a of the car body 11. This guide blade 13 is received within and extends into a slot 22 in the surface 21 of the track piece 22 as is seen in the front view of Figure 1b and shown by the dashed lines of Figure 1a. As the slot car 10 travels along the surface 21 of the track piece 20 along the slot 22 (in the x-direction, as shown), its lateral position (i.e. its position perpendicular to the slot 22 in the y-direction) will be restricted by the slot 22.

The slot car 10 further comprises wheels 16. The front wheels 16a of the slot car 10 (i.e. the wheels 16 furthest forward in the x-direction) are free to rotate on freely-rotating axle 17a. The rear wheels 16b are mounted on a driven axle 17b. The driven axle 17b and the driven rear wheels 16b rotate under a driving force from the motor 15, such that the slot car 10 may travel or move along a surface on which it is placed (e.g. the surface 21 of the track piece 20).

The speed at which the slot car 10 travels may be controlled by a user. To achieve this, the user may use an external controller (not shown) that is separate (i.e. not physically connected to) the slot car 10 and track piece 20 in wireless communication with the communication module 14. The external controller may transmit a signal to the communication module 14 from the user. Having received this signal, the communication module 14 may instruct the power source 12 to vary the power supplied to the motor 15 so as to change the output speed of the motor 15 and the driven rear wheels 16b. Alternatively, communication module 14 may instruct the motor 15 to vary its output speed directly.

As the power to drive the slot car 10 is supplied by an onboard power source 12 carried by the slot car 10 there is no requirement for the track piece 20 to transmit power to the slot car 10 or to comprise conductive rails.

A minimum clearance height C exists between the underside 11 a of the car body 11 and the surface 21 of the track piece 20, defined by the distance the wheels 16 extend past the underside 11a of the car body. The clearance height between the underside 11a of the car body 11 and the surface 21 of the track piece 20 increases towards the front and rear of the car body (i.e. towards the leading and trailing edges of the car body). The leading edge 11b of the car body 11 is rounded, having a radiused or curved shape. Whereas the trailing edge 11c of the car body 11 is tapered or angled. In each case, the clearance height between the car body 11 and the surface 21 on which the slot car 11 stands decreases along a direction from the ends of the slot car 10 towards the centre of the slot car 10 (i.e. in the x-direction in which the slot car 10 extends). Therefore, the slot car 10 can safely ride over bumps or discontinuities in a track. In further embodiments the car body 11 may be tapered or rounded at each end.

In Figures 1a and 1b the car body 11 is shown schematically using a single outline. However, in many preferred embodiments the car body 11 may comprise a chassis (which contains or carries the power module and onboard power source 12, the communication module 14 and the electric motor 15) and a separate body shell which may attach or clip over the chassis. In such embodiments the chassis may be configured to connect to one or more body shells which have different appearances (e.g. different shapes and/or markings). Thus the appearance of the car body 11 and the slot car 10 as a whole may be quickly and easily changed by the user (e.g. by hand or using a screwdriver). Such a chassis is preferably waterproof and/or weatherproof (e.g. being of a unitary or sealed construction). Moreover, the leading edge and/or trailing edge of the chassis may be rounded, bevelled or tapered as discussed above in reference to car body 11. Further discussion of the chassis and body shell of a slot car are discussed below with reference to the specific example of Figures 5a and 5b.

Having said this, in alternative embodiments the car body 11 may be a single self-contained unit (i.e. it may not comprise a chassis and body shell which are manually detachable). In which case, the car body 11 itself may be sealed such that it is waterproof and/or weatherproof.

Two exemplary track pieces 30, 40 are shown in Figures 2 and 3. Figures 2a, 2b and 2c show a straight first track piece 30 (where the start and end of the track piece are not offset laterally or rotated relative to each other), whereas Figures 3a, 3b and 3c show a curved second track piece 40 having a 45-degree curve. In the figures, corresponding features in each track piece 30, 40 are indicated using similar reference signs which are incremented by 10 between the figures.

Each of the track pieces 30, 40 is double-sided, having a first set of slots 32a, 42a formed in a first surface 31a, 41a and a second set of slots 32b, 42b formed in an opposed second surface 31b, 41b. Therefore, slots cars may be raced on either side of the track pieces 30, 40. Specifically, each surface 31a, 31b, 41a, 41b has two slots 32a, 32b, 42a, 42b (but this is not essential).

In each track piece 30, 40, the slots 32a, 42a formed in the first surface 31a, 41a of the track piece 30, 40 have a different layout than the slots 32b, 42b formed in the respective second surface 31b, 41b. In other words, the first slots 32a, 42a follow different paths in comparison to the second slots 32b, 42b.

For instance, it will be seen from Figure 2b that the slots 32a in the first side 31a of the straight track piece 30 are straight, running parallel to the direction in which the track piece 30 extends (the x-direction) along their entire length. Whereas, Figure 2c shows that the separation between the slots 32a in the second surface 31b is increased at the middle of the track piece 30. Similarly, Figure 3b shows the first set of slots 42a in the curved track piece 40, that each have a constant radius and extend parallel to the direction in which the track piece 40 extends. In contrast the second set of slots 42 shown in Figure 3c bow outwards before having a sharper curve (i.e. a curve with a shorter radius) at the middle of the track piece 40 in the x-direction.

Therefore each side of the track pieces 30, 40 offers a different layout and an alternative racing experience since the slots formed in the opposed sides are not parallel and follow different paths.

In further embodiments the properties of the first and second surfaces 31a, 31b of the straight track piece 30 and/or the properties of the first and second surfaces 41a, 41b of the curved track piece 40 may be different, such that the experience of racing on each side of a track piece 30, 40 is further distinguished. For instance the texture, roughness, surface finish, surface coating and/or markings of the opposed surfaces of the respective track pieces 30, 40 may be varied. Equally, in further examples surface properties may be varied between the two track pieces 30, 40, such that the surfaces 31a, 31b of the straight track piece 30 have a different texture, roughness, surface finish, surface coating, markings or other properties than the surfaces 41a, 41b of the curved track piece 40.

The track pieces 30, 40 are modular and may be connected together to form a larger track. Indeed, the track pieces 30, 40 each comprise respective connection portions 35, 36, 45, 46 which allow them to be assembled in a variety of arrangements (i.e. orientations).

Specifically it will be appreciated that either end 34a, 34b of the straight track piece 30 may be connected to either end 44a, 44b of the curved track piece 40 (i.e. the track pieces 30, 40 may be connected in either order). Furthermore, the track pieces 30, 40 may be connected such that their first surfaces 31a, 41b and second surfaces 31b, 41b are coplanar, or such that the first surface 31a of the straight track piece 31a is coplanar with the second surface 41a of the curved track piece 40 (and vice versa). In addition, the curved track piece 40 may be arranged to provide either a left-hand curve or a right-hand curve relative to the straight track piece 30 regardless of which surface 41a, 41b of the curved track piece 40 is coplanar with the first surface 31a of the straight track piece 30.

Equally, multiple straight track pieces 30 may be connected to form a longer portion of straight track, or multiple curved track pieces 40 may be connected to form a longer corner and/or a double curve or ‘S’ shape.

The connection portions 35, 36, 45, 46 provided to the track pieces 30, 40 include male connection portions 35, 45 and corresponding female connection portions 36, 46 in which the male connection portions 35, 45 may be received. Each male connection portion 35, 45 has the same dimensions, and each female connection portion 36, 46 has the same dimensions. As such, any male connection portion 35, 45 may be received in any female connection portion 36, 46.

At each end 34a, 34b, 44a, 44b of the track pieces 30, 40 there are provided two male connection portions 35, 45 and two female connection portions 36, 46. The connection portions 35, 36, 45, 46 are arranged with second order rotational symmetry about the axis in which the track piece 30, 40 extend at the respective end 34a, 34b, 44a, 44b (e.g. about an axis in the x-direction for each end 34a, 34b of the straight track piece 30).

As shown in Figures 2 and 3, the male connection portions 35, 45 and female connection portions 36, 46 are dovetailed. In other words a distal end (i.e. the free end) of each male connection portion 35, 45 is of greater width than a proximal end of each male connection portion 35, 45 (at which the male connection portion 35, 45 is connected to its respective track piece 30, 40), whilst similarly an opening or entrance of each female connection portion 36, 46 is narrower than an internal or interior part of each female connection portion 36, 46. Thus the male and female connection portions 35, 36, 45, 46 may be interlocked. More specifically, it will be seen that the male and female connection portions 35, 36, 45, 46 are tapered (as opposed to being curved, or increasing in width discontinuously along their lengths, which may be used in alternative track pieces).

The dovetailed connection portions 35, 36, 45, 46 provide a strong join or connection between adjacent track pieces as male and female connection portions 35, 36, 45, 46 cannot be easily separated by forces in the plane of the track piece. However, they are not essential and in further examples connection portions with alternative configurations and arrangements may be used.

The slots 32a, 32b, 42a, 42b in each track piece 30, 40 have consistent positioning at each end 34a, 34b, 44, 44b of the track pieces 30, 40, having second order rotational symmetry about the axis in which the track pieces 30, 40 extend at each respective end 34a, 34b, 44a, 44b. As such, it will be seen that the slots 32a, 32b, 42a, 42b in the track pieces 30, 40 will extend continuously regardless of the arrangement in which the track pieces 30, 40 (or multiple track pieces 30, 40) are combined.

In the examples shown in Figures 2 and 3, the thickness of the track pieces 30, 40 (i.e. the distance between the respective opposed surfaces 31a & 31b, 41a & 41b) is twice the slot depth. As such, where the slots 32a, 42a in the first surface 31a, 41a of each track piece 30, 40 are superimposed or overlap the slots 32b, 42b in the second surface 31b, 41b, the slots 32a & 32b, 42a & 42b will extend continuously between the opposed surfaces 31a & 31b, 41a & 41b. As such, apertures 33, 43 extend through the track pieces 30, 40 at each end 34a, 34b, 44a, 44b of the track pieces 30, 40.

However, in some cases continuous apertures formed by coincident or overlapping slots formed in the opposed surfaces of a track piece are undesirable. For instance, these apertures that extend through a track piece may reduce the strength of the track piece. Figures 4a and 4b show in cross section two embodiments of track pieces 50, 60 which avoid slots extending through a track piece.

Figure 4a shows a track piece 50 having a first surface 51a and an opposed second surface 51b. A first slot 52a extends into the first surface 51a, whereas a second slot 52b extends into the second surface 51b. As shown, the slots 52a, 52b are aligned, extending in a single plane parallel to the thickness of the track piece (the z-direction) and the direction in which the track piece extends (the x- direction). However, the thickness of the track piece 50 is greater than twice the depth of the slots 52a, 52b (i.e. the depth of the slot in the z-direction as shown). As such, track material will exist between the slots 52a, 52b regardless of their position in the respective surface 51a, 51b of the track piece 50.

In contrast, Figure 4b shows a track piece 60 which is between 1 and 2 times the average thickness of the slots 62a, 62b formed into its first and second surfaces 61a, 61b. To avoid a slot or cavity extending continuously between the first and second surfaces 61a, 61b of the track piece 60 (i.e. through the track piece 60) the slots 62a, 62b are laterally offset. Specifically, the slots 62a, 62b are offset or separated in the y-direction (that is the direction perpendicular to the direction in which the slots extend into the track piece 60 (the z-direction) and perpendicular to the direction in which the slots extend along the track piece 60 (the x-direction)). Thus the thickness of the track piece 60 can be reduced without a cavity or aperture extending through the track piece 60.

A slot car 100 (i.e. a slot racer) with further preferable features will now be discussed in relation to Figures 5 to 7. In this example the car body of the slot car 100 comprises a chassis 110 which is shown from above and below in Figures 5a and 5b respectively. The chassis 110 comprises a communication module, a power module configured to receive an onboard power source (specifically a battery compartment configured to receive batteries) and an electric motor in a similar manner to the slot car 10 shown in Figure 1 a and 1 b. The slot car 100 may comprise a selectively detachable guide blade component 130, as shown in Figures 6a and 6b, which may be attached to the chassis 110. The chassis 110 of Figures 5a and 5b is shown with the guide blade component 130 detached or separated.

The chassis 110 comprises an underside 110a (seen in Figure 5b) and an opposed upper side 110b (see Figure 5a), the underside 110a of the chassis 110 configured to face towards a track on which the slot car 100 is racing. The upper side 110b of the chassis 110 is provided with a plurality of construction block studs 112 (i.e. cylindrical protrusions extending from the upper side 110b of the chassis). These construction block studs 112 may be configured for use with conventional construction sets - e.g. such that the user may modify the appearance of the slot car 110 by connecting or clipping building blocks to the surface of the car. Equally the chassis 110 may connected to purpose built body shells with connections that match the arrangement of construction block studs 112 on the chassis 110. In other words the car body of the slot car 100 may comprise a chassis 110 and a separate body shell which clips over the chassis 110 using construction block studs 112. However, this is not essential and it will be appreciated that the slot car 100 may be driven or raced without either a body shell or any construction blocks mounted using the construction block studs 112.

The slot car 100 comprises a pair of driven wheels 160 mounted on a driven axle (not shown). The driven wheels 160 are driven by gear assembly 165. The slot car 100 further comprises a pair of freely rotating wheels 170. The freely rotating wheels 160 are mounted on respective freely rotating axles (not shown) of a freely rotating wheel assembly 175. The position of the freely rotating wheel assembly 175 may be varied along the length of the slot car 100 (i.e. in the x direction) by connecting the assembly 175 to different construction block studs 112. As such the wheel base - the distance between the wheels 160, 170 - of the slot car 100 may be changed (e.g. such that the scale slot car 100 may imitate a wider range of full-scale automobiles). The underside 110a of the chassis 110 is provided with a battery compartment door 114 which allows the user to access the battery compartment - e.g. to replace or recharge electrical batteries stored within the car body.

The slot car 100 is shown in Figures 5a and 5b without a guide blade. The slot car 100 may be selectively attached to the guide blade component 130 shown in Figures 6a and 6b.

The guide blade component 130 comprises a guide blade plate 134. From a first side 134a of the guide blade plate 134 extends a guide blade 132 configured to project from the chassis 110 of the slot car 100 (i.e. from the car body of a slot car) and be received in a slot of a track or track piece during use. The guide blade 132 is substantially planar, and extends in a longitudinal direction across the first side of the guide blade plate 134a From a second side 134b of the guide blade plate 134 extends a split cylinder 136 and a pair of rotation pins 135 on opposing sides of the split cylinder 136.

As shown in Figure 5b, the chassis 110 is configured to receive the split cylinder 136 and rotation pins 135 in two different locations. The guide blade component 130 (and hence the guide blade 132 projecting from the slot car 100) may freely rotate in different ranges when the guide blade component 130 installed or mounted in the different locations. Therefore, the guide blade 132 may be switched between different modes by changing its mounting location.

The first location in which the guide blade component 130 may be mounted comprises a first split cylinder receiving hole 140 and two rotation slots 145 formed into the underside 110a of the chassis 110. A cross section of the underside 110a of the chassis 110b along line A-A showing these features is provided in Figure 7.

The split cylinder 136 may be inserted into the split cylinder receiving hole 140 such that each of the rotation pins 135 is received in a respective rotation slot 145. Specifically, the split cylinder 136 may be formed of a material that can elastically deform, such that the split cylinder 136 may be inserted into the split cylinder receiving hole 140 by pressing the split cylinder 136 into the split cylinder receiving hole 140 such that its two parts are deflected towards one another. In this deformed state, the split cylinder 136 may be pushed through the split cylinder receiving hole 140 until the distal end 136a of the split cylinder 136 - which is of increased diameter in comparison to the remainder of the split cylinder 140 and the split cylinder receiving hole 140 - reaches groove 140a. At this point the compressed parts will be released such that the split cylinder 136 can return to its original shape.

The seating of the distal end 136a of the split cylinder 136 in groove 140a restricts movement of the guide blade component 130 parallel to the longitudinal axis of the split cylinder receiving hole 140 unless the two parts of the spilt cylinder 136 are pressed together. Therefore, the guide blade component 130 may be securely mounted to the chassis 110 whilst still being capable of freely rotating about the central axis of the split cylinder receiving hole 140. Equally, the guide blade component 136 may be easily attached to and detached from the chassis 110 by hand (i.e. manually) and without the need for any tools.

As will be seen from Figure 5b, the rotation slots 145 in the underside 110a of the chassis 110 at the first location are arcuate. Each rotation slot 145 extends about an angle of approximately 90 degrees in a circumferential direction about the centreline of the first split cylinder receiving hole 140. When the guide blade component 130 is attached to the chassis 110 in the first location (i.e. when the split cylinder 136 is received in the first split cylinder receiving hole 140) the rotation pins 135 may move freely in their respective rotation slot 145. As such, the ends of the rotation slots (which prevent further rotation of the rotation pins 135) define limits to the rotation of the guide blade component 130 and the guide blade 132. Therefore, when the guide blade component is attached to the chassis 110 in the first location the guide blade 132 may rotate between limits that are approximately 90 degrees apart. The guide blade component 130 may also be attached to the chassis 110 in a second location. The second location comprises a second split cylinder receiving hole 150 configured to receive the split cylinder 136. This second split cylinder receiving hole 150 has a similar structure to the first split cylinder receiving hole 140 shown in Figure 7. However, unlike the first location, the second location comprises a single circular rotation slot 155 that is arranged concentrically around second split cylinder receiving hole 150 and is configured to receive both rotation pins 135. As such, there is no limit to the rotation of the rotation pins 135 within the rotation slot 155. Therefore, the guide blade component 130 and the guide blade 132 may rotate continuously about the centreline of the second split cylinder receiving hole 150.

Therefore, the guide blade 132 is changeable between two modes - i.e. when it is attached to the chassis 110 in two different locations - such that in each mode or position it can rotate relative to the chassis 110 about different angle ranges. The guide blade 132 can be switched between these two modes (or removed from the car body entirely) manually by pulling the guide blade component 130 away from the chassis 110 and out of the first location and pushing the guide blade back into the chassis 110 at the second location, and vice versa.

It will be appreciated that the guide blade component 130 and the chassis 110 may be modified without affecting the performance of the guide blade 132 or the slot car 110. For instance, the number, size and positions of the rotation pins 135 and rotation slots 145 may be varied. In further embodiments a slot car 100 may have a different number of locations in which a guide blade component 130 may be mounted on the chassis 110. Equally, a skilled person will understand that a wide variety of alternative mechanisms for switching the guide blade 132 between different rotation modes are possible. Moreover, it will be appreciated that the guide blade 132 of Figures 6a and 6b may be used with a wide variety of slot cars or slot racers with appropriate fixing locations, including those with car bodies do not comprise a separate chassis and body shell. The guide blade component 130 shown in Figure 6 comprises a number of further preferable features of guide blades.

For instance, the guide blade 132 comprises two opposed longitudinal surfaces 132a, 132b. When the guide blade 132 is received in a slot, these longitudinal surfaces 132a, 132b will be arranged parallel to the sides of the slot. As such, as a slot car travels along this slot the sides of the slot will contact the longitudinal surfaces 132a, 132b so as to restrict the movement of the guide blade 132 laterally (i.e. perpendicular to the direction in which the slot extends into the track piece) and turn the attached slot car.

Each of the longitudinal surfaces 132a, 132b comprises a surface relief which restricts movement of the slot car normal to the slot (i.e. normal to the surface of the track piece in which the slot is formed). Specifically, each of the longitudinal surfaces 132a, 132b comprises three longitudinal fins 133 extending parallel to an axis in which the guide blade 132 extends (and parallel to the direction in which the guide blade 132 will travel along a slot). These longitudinal fins 133 will act to prevent the guide blade 132 (and an attached slot car) from lifting out of a slot or rotating relative to the slot in which the guide blade 132 is received. If a slot car lifts or rotates whilst the guide blade 132 is in a slot the longitudinal fins will contact or interfere with the sides of the slot and act to prevent further movement. Thus the longitudinal fins 133 will restrict movement of the slot car normal to the surface of a track piece (i.e. normal to the direction in which the slot extends into a track piece). The fins 133 may also provide a texture or surface relief which makes it easier for a user to grip the guide blade 132 when removing or inserting it into the car body of a slot car.

It will be appreciated that longitudinal surfaces may also be provided with alternative surface reliefs which achieve substantially the same purpose. For instance, the longitudinal surfaces may have alternative numbers of longitudinal fins and/or may be provided with protrusions in alternative patterns such as a “polka dot” pattern. Equally, the longitudinal fins 133 of Figures 6a and 6b are semi-circular in cross section, but this is not essential. For instance the longitudinal fins may have a triangular or rectangular cross section.

The guide blade 132 shown in Figures 6a and 6b also has a rounded leading edge 132c and a rounded trailing edge 132d. As such, a slot car to which the guide blade 132 is attached may ride over a discontinuity or bump in the base of a slot in which the guide blade is received without crashing. In further embodiments the leading edge and/or trailing edge of a guide blade may be tapered or may have an alternative configuration in which the length of the guide blade in the direction along which the guide blade projects from the slot car increases from its leading edge and/or trailing edge to the centre of the guide blade.

The guide blade 132 of Figures 6a and 6b is symmetric across a plane perpendicular to the opposed longitudinal surfaces 132a, 132b on the sides of the guide blade 132. Thus the guide blade 132 is suited for travelling in either direction relative to the longitudinal surfaces 132a, 132b of the guide blade 132. For instance, the guide blade 132 will have similar properties regardless of whether a slot car is driven in a forward direction or a reverse direction, and regardless of whether the body of a slot car is rotated by 180 degrees relative to the guide blade component 130.

It will be appreciated that these preferable features of the guide blade 132 shown in Figures 6a and 6b may be implemented separately from the remaining features of the guide blade component 130 shown in these figures. The preferable features of the guide blade 132 discussed above are not inextricably linked to the arrangement of a split cylinder 136 and rotation pins 135, or the concept of a guide blade component 130 which may be placed in alternative modes of rotation relative to a slot car.

Similarly, it will be appreciated that any of the features discussed above with reference to the slot car 10 of Figures 1a and 1b may be combined or incorporated into the slot car 100 and guide blade component 130 described in relation to Figures 5 to 7 (and vice versa). Equally the system as a whole and the specific slot racers and track pieces discussed in this detailed description may be adapted as appropriate to incorporate any of the optional or preferable features discussed in the summary of invention above.

Further track pieces and track systems for slot racing will now be discussed with reference to Figures 8 to 14. Figures 8 to 11 show four alternative sets of connection portions suitable for use with any of the track pieces discussed above, Figures 12a to 12 c shows a further curved track piece with different textures and slot arrangements on each side, whilst Figures 13 and 14 show track systems for slot racing that comprise barriers and border portions arranged at the sides of track pieces.

An end of four straight track pieces 210, 220, 230, 240 is shown in each of Figures 8 to 11. The reference signs of corresponding features shared by these track pieces 210, 220, 230, 240 are incremented by 10 between these figures.

As shown, each track piece 210, 220, 230, 240 comprises two slots 212, 222, 232, 242 formed in its first surface 211a, 221a, 231a, 241a. These slots 212, 222, 232, 242 are configured to receive guide blades of slot cars, such that slot cars may be raced on the first surfaces 211a, 221a, 231a, 241a. Each track piece may comprise further slots formed into its opposing second surface (not shown) such that slot cars may be raced on either surface of the track pieces 210, 220, 230, 240. The opposing racing surfaces of each track piece 210, 220, 230, 240 may comprise different layouts or arrangements of slots, and/or different surface properties (e.g. different textures, roughness, coatings, finishing, and/or markings).

The four track pieces 210, 220, 230, 240 shown in Figure 8 to 11 include different connection portions 215 & 216, 225 & 226, 235 & 236, 245 & 246. These connection portions 215 & 216, 225 & 226, 235 & 236, 245 & 246 are formed integrally with the track pieces 210, 220, 230, 240, such that the connection portions 215 & 216, 225 & 226, 235 & 236, 245 & 246 are attached to the main body of the track pieces 210, 220, 230, 240 and cannot be separated or removed from the track pieces 210, 220, 230, 240.

As will be seen the connection portions 215 & 216, 225 & 226, 235 & 236, 245 & 246 of each track piece 210, 220, 230, 240 are rotationally symmetric about the centreline of the track piece 210, 220, 230, 240 local to the end of the track piece - i.e. the longitudinal axis along which the track piece extends - marked by line Ai in Figure 8. Specifically, the connection portion arrangements have rotational symmetry of order two. Thus two track pieces which are provided at each end with a set of connection portions 215 & 216, 225 & 226, 235 & 236, 245 & 246 as shown in these figures may be securely coupled together in four different arrangements to create a substantially continuous or coplanar racing surface across the two track pieces. Equally the slots in each of the track pieces 210, 220, 230, 240 are rotationally symmetric about the same line at the end of the track piece with rotational symmetry of order 2. Hence, slot racing cars may be raced across two connected track pieces, regardless of which arrangement in which the pieces are connected via the connection portions 215 & 216, 225 & 226, 235 & 236, 245 & 246.

Figure 8 shows an end of a track piece 210 with jigsaw style connection portions 215, 216. As mentioned, the connection portions 215, 216 are rotationally symmetric about the central longitudinal axis Ai of the track piece 210 such that the track piece 210 may be connected to a further track pieces with corresponding connection portions in four different arrangements.

Two male connection portions 215 (i.e. protrusions) extend from the end surface 214a of the track piece 210 along the longitudinal axis Ai of the track piece 210 - i.e. perpendicular to the end surface 214a of the track piece 210. Two corresponding female connection portions 216 (i.e. recesses) are formed into the track piece 210, extending into the track piece from the end surface 214a. The female connection portions 216 are sized and shaped to correspond to the male connection portions 215, such that a further track piece with similar connection portions may be coupled to the track piece 210 shown in Figure 8 by bringing the track pieces together, and inserting the male connection portions 215 of each track piece into the female connection portions 216 of the adjacent track piece.

Each male connection portion 215 comprises projections 215a that extend from the connection in a direction perpendicular to the longitudinal axis Ai of the track piece, and parallel to the track. Corresponding receiving cavities 216a are provided to the female connection portions 216. These receiving cavities 216a are continuous with the body of the female connection portions 216 and extend into the track piece 210 in a direction perpendicular to the longitudinal axis Ai of the track piece 210, and are arranged to receive and accommodate the corresponding projections 215a of a further track piece (not shown). Specifically, each male connection portions 215 comprises four projections 215a whilst each female connection portion 216 comprises four corresponding recesses 216a.

When two or more track pieces with these connection portions 215, 216 are connected as discussed above connected in this manner, the projections 215a of each male connection portion 215 will be received in the receiving cavities 216b of the respective female connection portion 216. Thus the projections 215a and recesses 216a of the male and female connection portions 215, 216 are configured to interlock with the recesses and projections of a corresponding track piece. This provides a particularly secure connection between track pieces, restricting or preventing relative movement during use.

Further examples of connection portions with projections and recesses extending from the respective male and female connection portions are shown in Figures 9 and 10. The male connection portions 225, 235 extend from the end surface 224a, 234a of the track pieces 220, 230, whereas the female connection portions 226, 236 extend into the track pieces 220, 230 and are configured to receive the male connection portions of a further track piece with corresponding connection portions.

In each case male connection portions 225, 235 comprise projections 225a, 235a which extend perpendicular to the longitudinal axis of the respective track piece 220, 230 - i.e. perpendicular to the direction in which the male connection portions 225, 235 extend from the end surface 224a, 234a of the track piece 220, 230. The female connection portions 226, 236 each comprise corresponding receiving cavities configured to receive the projections 225a, 235a of a further track piece with corresponding connection portions. This is similar to the example shown in Figure 8. These receiving cavities extend into the respective track piece 220, 230 in a direction perpendicular to the longitudinal axis of the respective track piece 220, 230. This interlocking structure operates in a similar manner to the example shown in Figure 8.

However, unlike the projections 215a and receiving cavities 216a shown in Figure 8 which extend parallel to the racing surfaces of the track piece 210 (i.e. parallel to the first surface 211a shown in Figure 8) the interlocking projections 225a, 235a and receiving cavities 226b, 236b of the track pieces 220, 230 of Figures 9 and 10 extend perpendicular to the racing surfaces of the track pieces 220, 230. This can further prevent or resist undesirable separation of the connected track pieces caused by rotation of the track pieces relative to one another.

The track piece 220 of Figure 9 comprises dovetailed connection portions 225, 226, wherein the connection portions 225, 226 are wider at their distal end than at their base where they meet the end surface 224a of the track piece 220. Thus further improves connection between track pieces with these connection portions 225, 226. As shown the track piece 220 comprises two male connection portions 225 and two female connection portions arranged in rotational symmetry of order 2 around the longitudinal axis of the track piece (i.e. the direction in which the track piece extends). Each male connection portion 225 comprises four projections 235a that are configured to be received by four receiving cavities 226b of a female connection portion of a further track piece with similar connection portions.

The track piece 230 of Figure 10 comprises four male connection portions 235, and four corresponding female connection portions 236 at each end. Increasing the number of connection portions in this manner helps restrict movement or separation of the track pieces during use. As shown, the receiving cavity 236a of each female connection portion 236 extends through the track piece 230, such that a through hole is formed between the female connection portion 236 and the respective racing surface of the track piece 230. This simplifies manufacture of the track piece 230 and the female connection portion 236.

The track piece 230 shown in Figure 10 further comprises a region of hexagonal open cells 238 adjacent to each male connection portion 235 the track piece 230 comprises. These regions of open cell structures will be discussed further below with reference to Figure 12 which shows a curved track piece utilising the same arrangement of connection portions as shown in Figure 10.

Figure 11 shows a further track piece 240 with male and female connection portions 245, 246. These male and female connection portions 245, 246 again extend respectively from and into the end surface 244a of the track piece 240 parallel to the direction in which the track piece 240 extends. The connection portions 245, 246 are arranged with order 2 rotational symmetry on the end surface 244a such that the track piece 240 may be coupled or connected to a further track piece with corresponding connection portions in four different arrangements such that the racing surfaces of the track pieces extend continuously between the track pieces. As with each of the examples shown in Figures 8 to 10, the slots are also rotationally symmetric with order two at the end of the track piece 240 shown in Figure 11 , such that a slot racer may be raced across the surface of track pieces connected in any of these four arrangement.

The male connection portions 245 are studs that correspond in size and arrangement with recesses that form the female connection portion 246. These studs and recesses are cylindrical, although this is not essential. Close tolerances between the size and shape of the male and female connection portions 245, 246 and the relatively large number of connection portions 225, 226 on each track piece provides a particularly strong connection between connected track portions.

Each of the track pieces 210, 220, 230, 240 shown in Figures 8 to 11 further comprises reinforcement ribs 217, 227, 237, 247 provided at the base of the slots 212, 222, 232, 242 adjacent to the racing surfaces of the track piece 210, 220, 230, 240. This strengthens the track pieces around 210, 220, 230, 240 their slots 212, 222, 232, 242. However such reinforcement is not essential.

Figures 12a, 12b and 12c show a curved track piece 250 that extends through a 90 degree bend. The track piece 250 comprises two racing surfaces - a first surface 251a shown in Figure 12a and an opposing second surface 251b shown in Figure 12b and 12c.

The track piece 250 comprises connection portions 255, 256 that correspond to the connection portions 235, 236 discussed with reference to Figure 10 above. As such, each end of the track piece 250 comprises four male connection portions 255 and four female connection portions 256 of corresponding size and shape. The male connection portions 255 extend from the end surface 254 of the track portion 250 in a direction parallel to the direction in which the track piece 250 extends local to the end in question, whereas the corresponding female connection portions 256 extend into the track piece 250 along a similar direction. Each male connection portion 255 is provided with a projection 255a which corresponds in size, location and shape to a receiving cavity 256b extending from the female connection portion 256.

Slots 252a, 252b are formed into each of the first and second surfaces 251a, 251b of the track piece 250. The slots 252a, 252b on the first and second surfaces 251a, 251b are collocated (i.e. overlie one another) at each end of the track piece 250, but have different arrangements and follow different paths between the two ends of the track piece 250. The two slots 252a in the first surface 251a are parallel and follow the path along which the track piece 250 extends. Whereas the two slots 252b in the second surface 251b cross, such that a slot car racing in an inside slot will be transfer to an outer slot as it passes across the second surface 251b (and vice versa). Thus racing on each side of the track piece 250 provides a different experience to users.

The first and second surfaces 251a, 251b also have different textures. Thus the variety in the experience of racing using the track piece 250 is further increased. Specifically, the majority of the first surface 251a is flat or planar, whereas the majority of the second surface 251b comprises an open cell structure. This open cell structure is particularly beneficial since it improves variety whilst reducing the material required for track pieces, retaining strength and simplifying manufacture using techniques such as injection moulding. The cells 258 forming the open cell structure are cavities or recesses that extend into the second surface 251 b of the track piece 250. The cells 258 are hexagonal and formed in a regular honeycomb arrangement which provides high strength and minimise material requirements. However, in further embodiments other cell shapes (e.g. triangular, square, circular) may alternatively be used. The open cell structure extends across over 80% of the second surface 251b.

The first surface 251a does comprise smaller regions of open cell structures adjacent the respective male connection portions 255. These regions correspond to the underlying positions of the female connection portions 256 and avoid large solid regions of material within the track piece 250, thereby reducing weight and simplifying tooling when manufacturing the track piece 250 using injection moulding. Similarly, the second surface 251b comprises small planar regions which overly and correspond to the female connection portions 256. These planar regions define the surface of the recess forming the female connection portions 256. Equally, planar regions are formed across the second surface 251b in regions overlying the slots 251a formed in the first surface 251a of the track piece 250. These planar regions define the base of the slots 251a in the first surface 251a.

During use, the cells 258 of the open cell structure of the second surface 251b may be filled with sand, ice or other materials so as to provide further variety in the slot racing experience. This may be used to provide a slot racing track that imitates forms of motorsport such as rally racing.

The track piece 250 further comprises a groove 259 on either side of the track piece 250 by which detachable barriers or borders may be connected to the track piece (e.g. by a clip fitting). Examples of track systems comprising detachable barriers and border portions are shown in Figures 13 and 14.

Figure 13 shows a track system 300 comprising curved track piece 250 of Figure 22 to which barriers 260 have been attached using clips 261 which enter the grooves 259 on either side of the track piece 250. The barriers 260 extend parallel to the track piece and stand upwards from the racing surface of the track piece across which slot cars travel.

Figure 14 shows a track system 400 comprising a straight track piece 270 which comprises similar connection portions as the track pieces of Figures 10, 12 and 13. The straight track piece 270 comprises grooves as discussed in relation to the track piece 250 of Figures 12 and 13. Flat border portions 280 are attached (clipped) to either side of the track piece 270 and extend continuously in a lateral from the racing surface of the track piece, whilst barriers 290 are attached to the outer sides of the border portions 280 by clips 291 and stand upwards from the respective border piece 280 to which they are attached.

Such border portions 280 and barriers 260, 290 can help prevent slot cars from separating from the track during use, as may occur if the wheels of a slot car leave the edge of a track piece. Providing detachable barriers and border portions as shown in Figures 13 and 14 can provide increased flexibility and variety for users since the barriers and border portions can be attached and detached as desired. However, in further examples one or more of the barriers and/or border portions may be provided integrally with a track piece.