FIELD OF INVENTION

This invention relates to a wheel frame component. More particularly, this invention relates to a wheel frame component forming part of a multiple directional wheel BACKGROUND ART

The following references to and descriptions o f prior proposals or products are not intended to be, and are not to he construed as, statements or admissions of common general knowledge in the art In particular, the following prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the

identification of pertinent prior art proposals is but one part.

Wheel frames for multiple directional wheels or omni-wheels generally include a hub having a main axis about which the multiple directional wheel is adapted to rotate; a hub rim radially surrounding the hub; a first plurality of peripheral roller supporting amis radially extending from the hub rim in a first plane, and a second plurality of peripheral roller supporting arms, each member arm of the second plurality of peripheral roller supporting arms having a radially inner base and being

circumferentially offset with respect to diagonally adjacent members of the first plurality of peripheral roller supporting arms. The diagonally adjacent rollers overlap so that an operable portion of at least one of the rollers is in use in ground contact to enable the wheel to move in both a forward direction normal to the main axis by the rotation of the wheel as a whole about the main axis, and in a lateral direction having a vector component parallel to the main axis by the rotation of the at least one round contacting roller. The cost of manufacture of prior art multiple directional wheel frames is high both in terms of time and materials. Inadequate ride quality is another factor in which prior attempts do not excel. Ride quality is directly related to roller pass^-off length. Also, prior art attempts suffer from poor roller axle housing fit and impact resistance. These result in substantial wear and deterioration of the wheel and its performance: loosening axel mounts and impact damage discourage use of multiple applications where there is a low tolerance to mechanical failure or deterioration in performance. Furthermore, prior attempts tend to use metal components, such as axels, in engagement with moving components made of softer or weaker materials, thereby increasing cost and the likelihood of mechanical failure or accelerated wear and tear. It would be advantageous to provide a wheel frame that ameliorates one or more of the aforementioned disadvantages of the prior art or to at least provide a useful alternative thereto.

STATEMENT OF INVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the invention there is provided: a component for a wheel frame for a multiple directional wheel, the wheel frame component comprising: a hub having a main axis aboufwhich the multiple directional wheel is adapted to rotate; a hub rim radially surrounding the hub; a first plurality of peripheral roller supporting arms radially extending from the hub rim and lying in a first plane, a second plurality of peripheral roller supporting arms, each member arm of the second plurality of peripheral roller supporting arms having a radially inner base and being circumferentially offset with respect to diagonally adjacent members of the first plurality of peripheral roller supporting arms, wherein/characterised in that: the wheel frame component comprises a plurality of beams corresponding to the number of member arms of the second plurality of peripheral roller supporting arms, each respective beam extending from the hub rim to a corresponding inner base of a member arm of the second plurality of peripheral roller supporting arms; and the second plurality of peripheral roller supporting arms lie in a second plane normal to the main axis, spaced from, and parallel to, the first plane.

In another aspect, the invention provides:

A multiple directional wheel including a wheel frame comprising identical component parts, wherein each of the wheel frame components comprise:

a hub having a main axis about which the multiple directional wheel is adapted to rotate;

a hub rim radially surrounding the hub; a first plurality of peripheral roller supporting arms radially extending from the hub rim and lying in a first plane; and a second plurality of peripheral roller supporting arms, each member ami of the second plurality of peripheral roller supporting arms having a radially inner base and being circumferentially offset with respect to diagonally adjacent members of the first plurality of peripheral roller supporting arms, wherein/characterised in that: each of the wheel frame components further comprise a plurality of beams

corresponding to the number of member arms of the second plurality of peripheral roller supporting arms, each respective beam extending from the hub rim to a corresponding inner base of a member arm of the second plurality of peripheral roller supporting arms, and a plurality of spigots extending from each corresponding one the beams or the inner bases;

the second plurality of peripheral roller supporting arms lie in a second plane normal to the main axis, spaced from, and parallel to, the first plane; and

each of the spigots is received in a recess formed in a facing surface of a

complementary one of the wheel frame components to join the wheel frame

components to form the wheel frame.

The wheel can be used for both driven and free rolling conveyor transfer systems, inspection tables, ball transfer stations, as a robotic wheels or other wheel applications, particularly where caster wheels are employed. The wheel frame components may be identical or different, but are preferably identical to reduce manufacturing costs. The wheel frame, once assembled, may comprise two or more wheel frame components. The wheel frame is preferably formed from identical half wheel frame components. The wheel frame components may be formed by moulding, casting, 3-D printing, laser cutting, such as by using a CNC machine, and other forms of manufacture of 3-D objects known to the person skilled in the art.

Preferably the wheel frame is formed from polymeric material, such as acetal, reinforced polypropylene and other suitable polymer materials. The wheel frame may also be formed from metallic materials, such as various grades of steel, depending on corrosion and strength resistance properties required of the wheel. In a preferred embodiment, the wheel is made from lighter polymeric materials.

Preferably, the frame is moulded from ABS or acetal. By providing a standard cylindrical hub bore adapted to receive a variety of alternative hub bore inserts, the wheel may be suited to many different applications. For example, the various hub inserts may define a bore varying between 4.8mm, 6mm and 8mm in diameter. The hub insert may define a polygonal or cross-shaped axial bore. The hub insert is preferably in the form of a bushing. The hub insert may comprise a pair of opposable bushings, each engageable with the hub or each other, to form spaced axial bore openings.

The first component has a frame which includes the rim forming a circular ring from which radially extend the first support arms and cantilevered beams extend parallel axially from the rim to support the second support arms, also extending radially but axially offset from the ring and extending radially from the remote end of each beam, the first supporting arms circumferentially offset from the second supporting arms, a spigot extending from a base of each second supporting arm, and a recess formed in the base of each first supporting arm to receiving an opposed spigot of a like and mating second component.

The rollers may be unitarily or integrally formed as a single piece comprising a solid body. Each roller may have a pair of end protruding axial stubs that respectively engage spaced opposing support heads. The rollers so formed may be made from substantially rigid polymer, such as Nylon or polyurethane, the latter being suitable where high cut and tear resistance is desirable or such may be required for industrial applications. Alternatively, where a soft roller material is required for greater traction or quieter ride properties, the rollers may be overmolded as described in the Applicant's published patent application No. WO2011047443, the entire contents of which are herein incorporated. Overmolding of the rollers may be performed over axles of a harder and more rigid material suitable for forming a structural component, such as acetal. In any case, although forming the wheel from one or more metal components is within the scope of the invention, where the rollers and frame are made from polymeric materials, then preferably the components such as axels constituting or being engaged to relatively moving parts are made from materials other than metals to minimise relative abrasion and early onset of wear and tear related performance failures.

The wheel hub may be circular and adapted to receive and/or engage an axel, journal, bearings and/or drive shaft. In this connection, the spigots extending in an axially parallel direction from one wheel frame component may extend into and through the corresponding recesses of a second wheel frame component. The recesses may be keyed using a keyway spline. The recesses may be polygonal in section and adapted to receive a spigot in a press or interference fit.

The recesses may be cavities recessed into the second wheel frame component structure. Alternatively, the recesses may be bores or apertures that extend fully through the second wheel frame component. The spigots may extend through the bore or aperture and protrude proud on the other side of the second wheel frame component.

A drive means may be mounted to the wheel. The wheel may include a drive engagement device to operatively connect the rotation of the wheel about the main axis to the drive means. The protruding spigots may then be used to mount the drive means.

The drive means may be in the form of a sprocket having corresponding recesses to receive the protruding spigots. The drive means may include a gear assembly to enable the relative rotation ratios of the wheel compared to a drive shaft to be changed as required. The drive means may include a drive motor operably connected to the drive means. The drive means may include an internal plate adapted to face and abut the adjacent wheel frame component.

The drive means may engage the wheel by being keyed to operatively engage profiled or keyway defining bores. Alternatively, the drive means may include hub engaging tines. The hub engaging tines may be deflectable. The tines may be engageable in a corresponding recess or recesses formed in close association to the hub. The hub engaging tines may be arranged in a circle whereby to be inserted into the circular hub of the adjacent wheel frame component. The tines may be equally spaced. There may be two or more tines constituting the hub engagement device. The tines may each have a curved shape. The tines engaging a particular hub may form a set of tines that collectively are in the shape of a broken circle with arc gaps that define the sides of the tines. The curved tines are preferably adapted to engage complementary recesses formed in the hub rim outer face. The spigots preferably only partially extend from the first wheel frame component into the drive means. The spigots preferably do not extend fully through from the first wheel frame component to the drive means.

The rollers comprise tyres formed in a truncated fusiform or barrel shape. Each roller comprises an axel. The axel is preferably coaxial with respect to the roller. The axel preferably extends through an axial bore in the roller. The axel preferably extends beyond either end of the roller. Each roller axel can preferably engage a head of a peripheral roller supporting arm. The head is preferably located at a radially outward periphery or rim of the wheel.

Each roller axel may have a roller bushing. The roller bushing may be discretely formed. Alternatively, the roller bushing may be in the form of a wider cylindrical bushing. The axel may be either unitarily or integrally moulded with the wider cylindrical bushing. The wider cylindrical bushing may be enveloped or sleeved by the outer roller tyre. The roller tyre may be moulded or otherwise applied about the wider cylindrical bushing. The wider cylindrical bushing may be separately applied to the roller axel. Preferably, to minimise costs, the roller axel and the roller bushing are a unitary piece moulded as a single component for each roller. The roller axel and bushing may therefore be made of a strong and relatively inflexible material, such as reinforced or hardened polymeric material. Advantageously, a single piece molded roller core incorporating the axle pins/heads may be used. Alternatively, the roller may comprise a full solid piece roller. In another alternative, a roller undersized in diameter may be used which can be overmolded with selected materials adapted for improved wear and tear resistance, non-marking or improved traction, etc., or other desirable roller ground-engaging properties.

Each of the peripheral roller supporting arms may extend radially outwardly. The peripheral roller supporting arms may terminate at a radial extent close to the radial periphery of the wheel. The radial periphery corresponding to the outer extent of the wheel may be defined by the rollers when the wheel is viewed in side profile.

Each head, when viewed from a side in the line of the main axis, may comprise a substantially triangular body comprising recesses on either of its isosceles angled sides to receive roller axel pins extending from the rollers. Each head may be completed upon assembly of the component parts of the wheel frame. The head may include an outer peripheral engagement means to further secure the engagement of the component wheel frame parts.

The peripheral roller supporting arms may include a radial shaft extending from the hub rim to the head and may comprise a wide base adjacent the hub rim that tapers towards the head.

During assembly, the rollers may be press fitted into their respective opposed and spaced support head mounts so adjacent radial heads assist in retaining the roller during assembly.

The radial heads preferably include modified structural features to ensure a tighter fit with minimal opportunity for gaps between respective opposed engaged surfaces.

Advantageously, each opposed part adapted to form each head comprises a substantially planar surface interrupted by a marginally raised region proximal to the outer periphery. One or both facing surfaces may be so raised, so that the radially inward region of the opposed faces is adapted to flex and urge the opposed parts into flush engagement. The outer periphery of each pair of support heads may have complementary male and female fitting features, including a flange on one and a corresponding recess on the other.

The shaft may include an inner facing recess to receive an axially aligned spigot. The inner facing recess may be polygonal in shape. Preferably, the inner facing recess is hexagonal in shape. Preferably, the spigots are round in section. The diameter of the spigots is progressively stepped or tapered intermediate their respective lengths.

Accordingly, the round shaped spigot in section may be inserted into the hexagonal inner recess for a tight interference fit. The spigot may have a base with a wider diameter than a terminal or free end of the spigot. The base of the spigot may provide an interference fit in the inner facing recess. The narrower or smaller dimensioned terminal end of the spigot, which may have a smaller diameter, may extend partially or fully through the opposed wheel frame component. The spigot may extend fully through and out the other side for engagement with the drive means in some

embodiments of the invention.

Advantageously, the spigots are preferably short stubs of a constant cross section or constantly graded cross-section. The spigots may therefore not include a stepped shaft profile. Preferably, the entire length of the spigot provides an engagement surface in the corresponding receiving bore of the recess for a non-releasable friction fit. Preferably, the recess is a blind hole to minimise fatigue and mechanical failure risks in small frame components and for aesthetic reasons. However, in large wheel frames where the recess is formed in a greater body of material, through holes may be desirable for the recesses as described above.

The spigots therefore may provide complimentary fastening devices in the form of axial bolts or studs that mechanically join to complimentary recesses in an interference fit. Preferably the fastening devices extend parallel to the main axis. Each fastening device may extend substantially parallel to a corresponding beam. One or more of the fastening devices may extend substantially coaxially relative to a corresponding beam.

Each beam is preferably cantilevered and extending in parallel axial alignment, that is substantially parallel to the main axis from the hub rim. The beam may be polygonal in section. The beam is preferably trapezoidal in section. Still more preferably, the beam may be isosceles trapezoidal in section., in which a large elongate, substantially rectangular and parallel face corresponds to the outer perimeter of the hub rim. A small parallel face may correspond to the inner periphery of the hub rim.

Accordingly, the linear structure of the hub rim, the beam and the spigot in series is very strong. In its preferred form, it provides a strong and rigid inner structure of the hub rim of the wheel frame. When the wheel is coupled to the drive means, the drive means is preferably engaged through the strongest part of the wheel frame for the most efficient and effective transfer of power to the wheel. The beam is sufficiently long to extend axially parallel radially inwardly relative to a corresponding roller. The length of each beam allows space for a member of the second plurality of peripheral roller supporting arms to extend radially outwardly within the wheel's and the assembled wheel frame's side profile. Each member of the second plurality of peripheral roller supporting arms comprises a radial shaft with a wide base at the inner base tapering radially outwardly to a peripheral roller supporting head. The head preferably face in the same direction as the offset and diagonally adjacent heads of the first plurality of peripheral roller supporting arms.

Accordingly, by providing a pair of like wheel frame components facing each other and registered so that their respective spigots are received by their corresponding opposed inner recesses, the wheel frame components may be mechanically brought together in an interference fit and engaged to form a unitary wheel frame. Optionally, the wheel frame, hub or central bore interface can have further mounted to it a drive means. The interference fit may be mechanically sufficient to robustly join the pair of components or further reinforcement in the form of adhesive or welding, or a combination of both, may be desirable. Welding may be in the form of ultra-sonic welding. Preferably, respective engagement of the pair of components is achieved with only interference fit and no further adherence means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Figure 1 is perspective exploded view of a wheel according to a first

embodiment of the invention;

Figure 2 is a perspective exploded view of a wheel frame according to a second embodiment of the invention;

Figure 3 is a perspective view of the second embodiment shown from a different angle; Figure 4 is a perspective view of an assembled wheel according to either the first or second embodiment shown in Figures 1 or 2;

Figure 5 is a side view of the wheel according to a third embodiment;

Figure 6 is an end view of the wheel according to the third embodiment together with a bushing;

Figure 7 is an exploded perspective view of the wheel shown in Fig. 6;

Figures 8a-d are perspective views of alternative bushings for fitment to the third embodiment;

Figure 9 is a schematic side view of a solid moulded roller; and

Figure 10 is a schematic side sectional view of a support post of a wheel made according to the third embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

Referring to Fig. 1, there is shown a multiple directional wheel 10 including a wheel frame 20 comprising identical component parts 21i-ii. Each of the wheel frame components 21 i-ii comprise: a hub 30 having a main axis 1 about which the multiple directional wheel 10 is adapted to rotate; a hub rim 31 radially surrounding the hub 30; a first plurality (four shown) of peripheral roller supporting arms ("first arms") 22 radially extending from the hub rim 31 and aligned in a first plane; and a second plurality of peripheral roller supporting arms ("second arms") 23, each member arm of the second plurality of peripheral roller supporting arms having a radially inner base 24 and being circumferentially offset with respect to diagonally adjacent members of the first plurality of peripheral roller supporting arms 22. Each of the wheel frame components 21 i-ii further comprise a plurality of beams 25 corresponding to the number of member arms of the second plurality of peripheral roller supporting arms 23, each respective beam 25 extending from the hub rim 31 to a corresponding inner base 26 of a member arm of the second plurality of peripheral roller supporting arms 23, and a plurality of spigots 40 extending from each corresponding one the beams 25 or the inner bases 26. The second plurality of peripheral roller supporting arms 23 lie in a second plane normal to the main axis 1, spaced from, and parallel to, the first plane; and each of the spigots 40 from one of the wheel frame components 2 li-ii is received in a recess 27 formed in a facing surface 35 of a complementary one of the wheel frame components 2 li-ii to join the wheel frame components 2 li-ii to form the wheel frame 20.

The hub rim 31 defines a circular hub 30. The frame 20 of the eight-roller wheels 10- 10c is star-shaped and has concave curved walls 32 extending between and forming part of the first arms 22. The star-shape facilitates the provision of a wide base 28 first arm 22 tapering through its shaft 29 to first roller axle mounting heads 12.

Each of the beams 25 is a thick structure substantially consistent in thickness

throughout its length from the hub rim 31 to its corresponding inner base 26, although the skilled person may appreciate that some variation may achieve optimisation of strength whilst minimising materials. The beam 25 is substantially linear and aligned parallel to the main axis 1. Aligned in series and substantially linearly aligned are the hub rim 31, the extending beam 25 end-on-end, the inner base 26 of a transversely extending second arm 23 and an elongate spigot 40. The beam is cantilevered from the hub rim 31 and this structure allows for the minimisation of materials, whilst permitting easy assembly of the wheel 10 by allowing the rollers to be first inserted and then secured and trapped once assembled. The assembled wheel 10 provides an extremely robust and rigid hub rim 31 and inner base 26 structure by maintaining consistently the thickness of the hub rim 31 and cantilevered beam 25 through a linear direction parallel to the main axis 1.

The spigot 40 is stepped, having variable diameter between a wider spigot base 41 and a thinner protruding terminal end 42. The spigot base 41 is adapted to be received in an strong mechanical interference and non-releasable fit in a corresponding recess 27, so that the terminal end 42 extends proud beyond the other side of the complementary other wheel frame component 21ii through hole 33 that is continuous with the recess 27. The proud terminal end 42 of the spigot 40 may be used to engage a drive device such as a set of gears, a drive motor or a sprocket 50 as shown in Fig. 1 by inserting the spigot end 42 into one of a plurality of through-apertures 51 formed in a body 52 of the sprocket 50.

The respective roller axle supporting head parts 12 comprise substantially isosceles triangular bodies with axle pins 61 of rollers 60 being received in shallow, half- spherical axle pin recesses 63. Only upon the assembly of the two half components 21i- ii is each head 12 completed and the roller axle pins 61 secured and trapped in their respective completed recesses 63. The head parts 12 comprise peripheral

complementary engagement portions in the form of a male tongue or flange 14 formed in the facing head 13 of the first component 21i and curved to follow the contour of the outer wheel rim and a complementarily curved female groove 16 formed in the head 12 of the second component 21ii.

With reference to Figs. 2 - 4, in describing the various components in the second embodiment, like features will be referenced with the same reference number, a variation of the embodiment shown in Fig. 1 is provided in which a wheel 10b is substantially similar to the wheel 10, but has a different hub 30b shape and spigot 40b shapes. The spigots 40b are not stepped but terminate with a thick base portion 41a (corresponding to portion 41 of the spigot 40 shown in Fig. 1) and extend from a first wheel frame component 22b only to the extent that they end flush with an outer wall 34 of a second wheel frame component 23b. Similarly, complementary spigots 41b extending from wheel frame component 22b extend through recesses 27b in wheel frame component 23b and end flush with an outer wall 35b of wheel frame component 23b. The hub rims 3 lb of the wheel frame components 22b-23b comprise wedged cut out recesses 37b that are adapted to form the cooperating recess for complementary- shaped tines or fingers 53b provided in the unitary moulding of a second form of sprocket 50b adapted to engage directly with the hub rim 3 lb, so that the spigots 40b,41b are not required to attach the sprocket 50b. The tines 53b are arranged in a circular pattern and are equi-spaced to be inserted and to be received in a mechanical interference fit in the corresponding wedge shaped recesses 37b so that the sprocket 50a or other suitable drive means may be engaged or mounted to the wheel 10a for rotation therewith as shown in Fig. 4.

Additional embodiments shown with reference to Figs. 5 - 8d will now be described wherein similar corresponding features are identified by like reference numbers.

A wheel 10c in assembled form will be described with reference to Figs, 5 - 10 in which the recesses 27c receiving spigots 40c are blind recesses shown in broken lines to indicate that they are hidden from external view and sealed at one end to preserve the strength and integrity of the frame 20c structure surrounding the recess 27c.

The spigots 40c are of constant cross-section and are not stepped whereby to maximise the engagement surface and friction fit with the wall of the recess 27c.

The respective components 21 i-ii face each other at opposing surfaces 35c-36c when engaged to one another as shown in Fig. 10. The faces 35c-36c are raised at the radially outer region 37c-38c of the head 12c radially inwardly adjacent the pin recesses 63c whereby to create a shallow radially inward cavity 39c between opposed surfaces 35c- 36c, This gap 39c facilitates greater adherence of the respective components 21 i-ii to each other, permitting flexing about the raised surfaces and into the cavity 39c.

The peripheral rim of the first component 21i has a male flange 14c that cooperates with a female recess or ledge 16c to facilitate engagement of the respective components 21 i-ii.

The rollers 60c are solid unitary structures formed from a single moulding and made from an homogenised material, such as polyurethane and other polymeric materials which have a high cut, tear and sheer strength. Softer materials offering greater traction and able to be overmoulded onto a roller bush axle substrate may be suitable in certain applications. As shown in Fig. 9, the rollers 60c may be unitarily or integrally formed from a single piece including a solid, barrel-shaped body 65c and a pair of spaced, coaxial, end pins 61c adapted to be received in the cup-shaped recesses 63c formed by the components 21 i-ii.

As shown in Figs. 7 - 8, the shape of the axle bore 30,30c can be modified by substituting any on a range of different bushings 70a-d, each having tines 53c whereby to engage with reciprocal recesses 37c to connect to the rim 31c. The bushings 70a-b have varying bores in the range of 4.8mm - 8.0mm, although other sizes will be considered to fall within the scope of the invention, thereby being able to be flexibly adapted to fit larger or smaller axles, bearings and journals. The axles extending through the main bore 30,30c may be keyed to ensure that the frame 20c rotates with the main axle. Bushing 70c has a star-shaped bore profile 73c, whereas the bore of bushing 70d has a four-leaf clover keyed shape 74c.

Throughout the specification and claims the word "comprise" and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word "comprise" and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

In the present specification, terms such as "apparatus", "means", "device" and

"member" may refer to singular or plural items and are terms intended to refer to a set of properties, functions or characteristics performed by one or more items or

components having one or more parts. It is envisaged that where an "apparatus", "means", "device" or "member" or similar term is described as being a unitary object, then a functionally equivalent object having multiple components is considered to fall within the scope of the term, and similarly, where an "apparatus", "assembly",

"means", "device" or "member" is described as having multiple components, a functionally equivalent but unitary object is also considered to fall within the scope of the term, unless the contrary is expressly stated or the context requires otherwise.

Orientational terms used in the specification and claims such as vertical, horizontal, top, bottom, upper and lower are to be interpreted as relational and are based on the premise that the component, item, article, apparatus, device or instrument will usually be considered in a particular orientation, typically with the wheel shown upright and the main axis aligned horizontally.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the invention.