Field of the invention

The invention relates to the field of electrical feeding of vehicles, and in particular electrical feeding of underground vehicles.

Background

Concerns about the environmental impact of combustion of fossil fuels have led to an increased interest in electric vehicles, which have several potential benefits

compared to vehicles with conventional internal combustion engines, including: a significant reduction of urban air pollution, as they do not emit harmful tailpipe pollutants from the on-board source of power at the point of operation; reduced greenhouse gas emissions from the on-board source of power, depending on the fuel and technology used for electricity generation and/or charging the batteries and reduced dependency on fossil fuels with increasingly variable supply and fluctuating prices.

One disadvantage to be overcome is the limited range of existing electric vehicles due to limitations in battery capacity. This is a particularly significant disadvantage for heavy vehicles such as long haulage trucks as well as construction and mining vehicles.

WO 2010/140964 proposes a solution to this problem by feeding electric vehicles while driving. It discloses a system for electric propulsion of a vehicle along a road comprising electric conductors in the shape of conducting rails that may be put under voltage and located in longitudinal tracks or channels in the road. The vehicle is equipped with a current collector which during contact with the conducting rail allows for transfer of electric current between the conducting rail and the vehicle.

Although the solution according to WO 2010/140964 works well in many applications, it may not be suitable for very dusty or dirty environments such as mines. Since the conducting rail or track is located in the road, the excessive amount of dirt, sand and stones present in a mine may accumulate in the track and greatly impair electric contact therein, and possible leading to the current collector getting stuck in the tracks or channels.

Summary

An object of the present invention is to provide a system, a method and use for electrical feeding of a vehicle which is suitable for use in an underground

environment such as a mine. Another object is to provide such a system, method and use with high safety.

These and other objects are achieved by the present invention by means of a system, a method and use for electrical feeding of a vehicle according to the independent claims. Preferred embodiments are defined in the dependent claims.

According to a first aspect of the invention, there is provided a system for electrical feeding of a vehicle. The system comprises at least one suspended rail element and at least one contact device. The rail element has at least one elongated groove or channel extending along a length of the rail element, wherein electric conductors to be put under voltage are arranged therein. The at least one contact device is directly or indirectly connectable to the vehicle, wherein the contact device is displaceable relative said vehicle and is configured to mechanically and electrically connect with the rail element, for example from beneath, in order to transmit electric current from said electric conductor to the vehicle.

In other words, the system comprises at least one suspended rail element, e.g. rail element(s) which is/are suspended or is adapted to be suspended from for example a ceiling, wall or one or more stands, posts or the like. The rail element has at least one elongated groove or channel extending along a length of the rail element. In embodiments, the elongated groove or channel extends along the whole or essentially the whole length of the rail element. Electric conductors to be put under voltage are arranged in the at least one groove or channel. For example, a system comprising a plurality of grooves or channels may have one, two or a plurality of electric conductors in each groove or channel, and a system comprising one groove or channel may have two or a plurality of electrical conductors therein. The electric conductors may be arranged at a bottom portion or surface, or on vertical or side wall(s) or portion(s), of the at least one groove or channel. The at least one contact device is directly or indirectly connectable to the vehicle, e.g. it comprises or is attached to connecting means, such as a connecting arm, which is directly connected to the vehicle. The at least one contact device is configured to mechanically and electrically connect with the rail element. For example, the contact device may be configured to allow at least a portion thereof to abut with at least the electric conductors to achieve a sliding electrical contact when to vehicle moves in order to transmit electric current from said electric conductor to the vehicle, either directly to at least one electric motor which is arranged to propel the vehicle or indirectly, i.e. to for example a battery or super capacitor arrangement. The at least one contact device may be configured to connect with the rail element from beneath, i.e. connect with the rail element which is located above the contact device.

The invention is based on the insight that a suspended rail element, and the groove or channel therein, is less exposed to dirt when it is suspended. The invention is furthermore based on the insight that suspended rail elements having elongated groove(s) or channel(s) in which electrical conductors are arranged offers substantial safety improvements over known technologies, such as suspended lines used with trolley buses.

It is understood that suspended rail element refers to a rail element which is hung from, or attached to, for example a ceiling, wall, or one or more stands or posts or the like such that the rail element is at a distance or separated from the road. It is further understood that the directions given throughout this text refer to an application where the vehicle is located with its wheels on a road, and the rail element is suspended above the vehicle and/or above the road. It is also understood that rail element refers to an elongated element having a substantially greater length than width.

According to an embodiment, the at least one elongated groove or channel may be downwardly facing when the at least one rail element is suspended, i.e. the at least one elongated groove or channel is arranged facing in a direction having its greatest direction component along the plump line. In embodiments, the contact device is displaceable upwards, downwards and laterally. This is advantageous since it allows the contact device to connect to the rail element regardless of their initial relative position.

In embodiments, the contact device further comprises guiding means arranged to guide the contact device in a direction towards the rail element. The guiding means may comprise a guiding element provided with a recess, or with a U-shaped portion, having a width corresponding to that of said rail element. The guiding element may be described as being elongated or laterally extending or as having a laterally extending body. The recess or U-shaped portion may be provided at any suitable position of the guiding element as seen in the lateral direction, but preferably at, or essentially at the middle of the guiding element or its body. Such a guiding element is operated by forcing it towards said rail element, for example upwards, until it contacts the rail element, and thereafter the guiding element is displaced in a lateral direction thereof, e.g. in a perpendicular or substantially perpendicular direction relative the rail element(s), until the rail element and the recess or U-shaped portion having a width corresponding to that of said rail element slide into, or engage with, each other.

In embodiments, the at least one rail element is provided with one or more additional electric conductors at opposite sides of said at least one groove or channel, through which conductors a current is adapted to pass for generating a magnetic field.

Alternatively, the magnetic field may be generated by at least one permanent magnet arranged at opposite sides of the at least one groove or channel. The guiding means may be provided with at least one coil adapted to sense the magnetic field and a variation thereof, and the guiding means may further be provided with, or be configured to co-operate with, control means, such as an electronic control unit (ECU), which is configured to control actuating means, such as electric motors, arranged to displace said contact device in response to said sensed magnetic field.

In embodiments, the rail element is provided with at least one electrically conducting ground conductor provided on, or forming at least a portion of, an outer surface of the rail element, the ground conductor being connected or connectable to ground potential. The ground conductor may be arranged to envelope said rail element (apart from said at least one elongated groove) to provide a ground shield around said rail element. The contact device may comprise at least one ground collector, for example a sliding current collector, configured to be brought in electrical and mechanical contact with said ground conductor.

In embodiments, the rail element is provided with three electric conductors, each being connected to a phase of a three phase AC supply. In other embodiments, the rail element is provided with two electric conductors being connected to a DC supply.

In embodiments, regardless if an AC or DC supply is used, the rail element may be provided with at least one additional electric conductor being a ground conductor arranged in at least one of the elongated groove(s) or channel(s), which ground conductor is connected or connectable to ground potential.

In embodiments, the rail element comprises of a plurality of consecutively arranged rail element sections, wherein end portions of adjacent rail element sections are electrically and mechanically releasably connected together. This is advantageous since the rail element may be conveniently mounted or suspended by suspending or mounting one rail element section at a time, and may also be conveniently

dismounted when the system is to be used in for example another mine tunnel. The rail element and rail element sections may be attached to the ceiling using for example expander bolts in drilled holes in the ceiling.

According to a second aspect of the invention, there is provided a method for electrical feeding of a vehicle having at least one electric motor arranged to propel the vehicle. The method comprises:

- suspending at least one a rail element from a ceiling, wall or one or more

stands, posts or the like, the rail element having at least one elongated groove or channel extending along a length of said rail element, wherein at least one electric conductor is arranged therein;

- connecting at least one contact device to the vehicle, the contact device being displaceable relative said vehicle;

- displacing the contact device in a direction towards said rail element, for

example from beneath, such that said contact device connects mechanically and electrically with said rail element; and - supplying electric current to the at least one electric conductor whereby the electric current is transmitted to the vehicle via said contact device.

In embodiments of the method according to the second aspect of the invention, the step of suspending comprises suspending the at least one rail element in a direction such that the elongated groove is downwardly facing.

In embodiments of the method according to the second aspect of the invention, the step of displacing comprises displacing the contact device in a direction towards the rail element and at least partially into the at least one groove, for example from beneath, such that the contact device connects electrically with the at least one electric conductor. In other words, the contact device is displaced towards the rail element, and at least a portion thereof is displaced into the at least one groove. The at least a portion of the contact device preferably comprises at least one current collector which thereby connects electrically with the at least one electric conductor.

In embodiments of the method, where the rail element is provided with at least one electrically conducting ground conductor provided on, or forming at least a portion of, an outer surface of the rail element, and where the contact device comprise at least one ground collector, for example a sliding current collector, the step of displacing further comprises displacing the contact device in a direction towards the rail element such that the ground collector connects electrically with the at least one ground conductor.

In embodiments of the method according to the second aspect of the invention, where the contact device comprises a guiding element provided with a recess, or with a U-shaped portion, having a width corresponding to that of the rail element, the step of displacing comprises displacing the contact device towards the rail element until the guiding element contacts the rail element, and thereafter displacing the guiding element in a lateral direction thereof until the rail element slides into the recess or U- shaped portion. In other words, the contact device is displaced towards the rail element, typically upwards, until the guiding element contacts the rail element.

Thereafter, the guiding element is displaced sideways or laterally, while the contact device including the guiding element is still being forced towards the rail element, until the rail element slides into the recess or U-shaped portion, i.e. the recess or U- shaped portion engages with the rail element.

In embodiments of the method according to the second aspect of the invention, the step of suspending comprises suspending a plurality of rail element sections consecutively in a row, such that the rail element sections forms the rail element, wherein an end portion of one of the rail element sections is electrically and mechanically attached to an end portion of an adjacent rail element section.

According to a third aspect of the invention, there is provided use of at least one suspended rail element for electrical feeding of a vehicle, wherein the rail element is suspended from a ceiling, wall or one or more stands or posts, the rail element having at least one elongated groove or channel extending along a length of the rail element, wherein at least one electric conductor is arranged therein.

In embodiments of the use according to the third aspect of the invention, at least one contact device is used to transmit electric current from the electric conductor to the vehicle, wherein the contact device is directly or indirectly connected to the vehicle, and wherein said contact device is displaceable and is configured to mechanically and electrically connect with said rail element, for example from beneath. The at least one contact device may also be used to connect the vehicle to ground potential, where the contact device comprises at least one ground collector, for example a sliding current collector, which is brought in electrical and mechanical contact with at least one ground conductor of the rail element, the at least ground conductor being provided on, or forming at least a portion of, an outer surface of the rail element. Alternatively, the at least one ground conductor may be arranged in at least one of the elongated groove(s) or channel(s).

The features of the embodiments described above are combinable in any way to form embodiments having combinations of these features. Further, all features and advantages of embodiments described in connection with the system according to the first aspect of the invention may be applied in corresponding embodiments of the method according to the second aspect of the invention, and also in corresponding embodiments of the use according to the third aspect of the invention, and vice versa.

Brief description of the drawings

These and other aspects of the present invention will now be described in more detail with reference to the appended drawings, which show presently preferred

embodiments of the invention, wherein:

fig. 1 shows a schematic illustration of an embodiment of a system according to the first aspect of the invention, where the system arranged in a mine tunnel;

fig. 2 shows a schematic illustration of another embodiment of a system according to the first aspect of the invention;

fig. 3 shows a schematic illustration of yet another embodiment of a system according to the first aspect of the invention, which system comprises a ground conductor; and

fig. 4 shows a schematic illustration of a further embodiment of a system according to the first aspect of the invention, wherein the contact device of the system comprises a guiding element.

Detailed description

Figure 1 shows a schematic illustration of an embodiment of a system 1 according to the first aspect of the invention, where the system is arranged in a mine tunnel. A vehicle 2 is arranged in the mine tunnel. A rail element 3 is suspended from the ceiling of the mine tunnel. The rail element extends along the mine tunnel, i.e. in the depth direction thereof, i.e. along the travel path or direction of the vehicle. The rail element has two elongated grooves or channels 4a-b extending along the length of the rail element (in the depth direction in the figure). One electric conductor (not shown in figure) put under voltage is arranged in each groove or channel. The elongated grooves or channels 4a-b are downwardly facing, i.e. facing towards the vehicle 2 and towards the road on which the vehicle is standing on.

The system also comprises a contact device 6 which is connected to a roof portion the vehicle 2 using a connecting arm 12. The contact device is displaceable upwards, downwards and laterally to mechanically and electrically connect with the rail element from beneath, in order to transmit electric current from said electric conductor to the vehicle, either directly to at least one electric motor which is arranged to propel the vehicle or indirectly, i.e. to for example a battery or super capacitor arrangement. The contact device is displaced using the connecting arm 12 which is pivotably attached to the vehicle (backwards, forwards and sideways as seen in the figure). This is advantageous since it allows the contact device to connect, or maintain a connection, to the rail element even if the vehicle moves in the lateral direction and if the height of the tunnel varies. The contact device connects with the rail element by being displaced upwards such that each of two vertically upwards extending portions of the contact device 6 enters a corresponding groove or channel 4a-b. Each vertically upwards extending portion of the contact device comprises a current collector portion configured to connect electrically with the electric conductor in the groove or channel.

Figure 2 shows a schematic illustration of another embodiment of a system according to the first aspect of the invention.

A rail element 13 is suspended from a ceiling or stand (illustrated by the horizontal line in the figure). The rail element has three elongated grooves or channels 14a-c extending along the length of the rail element (in the depth direction in the figure). Electric conductors 15a-c are arranged said grooves or channels, one at a bottom portion of each groove or channel 14a-c. In other embodiments, the electric conductors may be arranged on for example side walls or portions of the at least one groove or channel. The elongated grooves or channels 14a-c are downwardly facing.

The system also comprises a contact device 16 which is connectable to a roof portion a vehicle 2 using for example a connecting arm corresponding to that shown in figure 1 . The contact device is displaceable upwards, downwards and laterally to

mechanically and electrically connect with the rail element from beneath, in order to transmit electric current from said electric conductor to the vehicle, either directly to at least one electric motor which is arranged to propel the vehicle or indirectly, i.e. to for example a battery or super capacitor arrangement. The contact device connects with the rail element by being displaced upwards such that each of three vertically upwards extending portions of the contact device 6 enters a corresponding groove or channel 14a-c. Each vertically upwards extending portion of the contact device comprises a current collector 1 1 a-c configured to connect electrically with the electric conductor in the grooves or channels. In the figure, the current collectors are in direct contact with corresponding electric conductors 15a-c. As the vehicle moves, the current collectors slides along the electric conductors in the grooves or channels, remaining in contact with the electric conductors.

Figure 2 also illustrates how the grooves or channels 14a-c are limited and separated by four parallel side walls 13a-d and a top wall 13e and have essentially U-shaped cross-sections. The grooves or channels are thus adapted to support current- feedable and energizable electric conductors 15a-c arranged in the innermost portions of the grooves or channels and being in abutment with the top wall 13e. The rail element also comprises an outer cover 13f that surrounds the side walls 13a, 13f and the top wall 13e. The outer cover is adapted to form a strong shell that prevents, among other things, the rail element from being deformed.

Figure 3 shows a schematic illustration of yet another embodiment of a system according to the first aspect of the invention, which system comprises a ground conductor. The embodiment in figure 3 corresponds to the embodiment shown in figure 2, but differs in that the rail element 23 is provided with an electrically conducting ground conductor 29 provided around an outer surface of the rail element to envelope said rail element (apart from the elongated grooves or channels 24a-c), the ground conductor being connected to ground potential. The ground conductor thereby provides a ground shield around said rail element. A further difference from the embodiment in figure 2 is that the contact device 26 comprises two ground collectors 210a-b, being sliding current collectors, configured to be brought in electrical and mechanical contact with corresponding and downwardly directed portions of the ground conductor 29. The contact device connects with the ground conductor by being displaced upwards such that the two vertically upwards extending ground collectors 210a-b abut with the ground conductor, e.g. downwardly facing portions thereof, to achieve electrical and mechanical contact therewith.

Figure 4 shows a schematic illustration of a further embodiment of a system according to the first aspect of the invention, which system comprises a guiding element. The embodiment in figure 3 corresponds to the embodiment shown in figure 2, but differs in that the contact device 36 is provided with a guiding element 37 which is connected to a connecting arm 312. The guiding element has a laterally extending bar-shaped body having a U-shaped portion 38 in the middle thereof. The U-shaped portion has a width corresponding to that of the rail element 33. The guiding element is provided to guide the contact device by displacing or moving the contact device towards the rail element 33 until the guiding element contacts the rail element, and thereafter displacing the guiding element in a lateral or sideways direction thereof until the rail element slides into the U-shaped portion 38. In the figure, the contact device is located below the rail element 33, but is not centred there below. Thus, when the contact device including the guiding element is displaced upwards using the connecting arm 312, the rail element 33 will not fit into the U- shaped portion. Consequently, the contact device is moved laterally or sideways relative the rail element, while simultaneously being forced upwards, until the contact device and rail element slide into each other, thereby causing the current collectors 31 1 a-c to enter corresponding grooves or channels 34a-c of the rail element, to make contact with the electric conductors therein.

The description above and the appended drawings are to be considered as non- limiting examples of the invention. The person skilled in the art realizes that several changes and modifications may be made within the scope of the invention. For example, the number of grooves or channels may be changed, and the dimensions and proportions thereof may also be changed. Further, the groove(s) or channel(s) do not necessarily have to be facing straight downwardly, i.e. along the plump line, but may be facing in practically any other direction. The scope of protection is determined by the appended patent claims.