Omnidirectional wheel

Abstract

An omnidirectional wheel (100) includes a central hub (150) from which a plurality of radially extending spokes (110) extend, each spoke (110) terminating in an outer radial head (112), each pair of adjacent radial heads radially spaced from the central hub (150) having a roller axis extending therebetween for supporting a roller (104) adapted to rotate about an axis (105), the axis (105) is perpendicular to a virtual radial line (124) extending from the main rotational axis (108) of the wheel (104), where the outer periphery of the central hub (150) includes a cylindrical outer wall (156) supporting each radial head, a pair of radially outwardly extending spoke arms (146) defining a triangular, diamond or arrow-shaped hollow portion (142) therebetween, the pair of outwardly extending spoke arms (146) converging to converge, thereby forming a spoke neck (134) supporting a respective radial head (112).

Description

Technical Field

[0001] The utility model relates to the technical field of omnidirectional wheels, and particularly relates to an omnidirectional wheel. Background Art

[0002] Omnidirectional wheels have become important components in various fields including material transportation, packaging parcel transportation, and the use of multi-directional wheels in robots. The materials used to manufacture the frames of such omnidirectional wheels (such as metals and plastics) are very expensive. Preferred characteristics are a combination of lightweight, elastic or rigid, and sturdy. Minimizing the materials used and the number of individual components when manufacturing the wheels is advantageous.

[0003] Omnidirectional wheels can be easily driven by power to provide precise mobility for robots. They can also be inverted, i.e., positioned to run under the contact surface rather than on top of it, for example, for multi-directional conveying and sorting in a conveyor feed table application. Conveying and sorting applications require high load-carrying capacity, while in robots, a lighter wheel frame is an advantage.

[0004] The omnidirectional wheel frames of the prior art are usually either sturdy, thick, and heavy, or fragile and not suitable for heavy loads. A single-rim fragile frame can include assembled components connected by metal fasteners. Since the metal fasteners abut against the softer plastic frame, this may create an unfavorable hardness difference. Summary of the Utility Model

[0005] An omnidirectional wheel generally includes a double rim or double frame to form a wheel unit. The applicant's omnidirectional wheel includes two wheel frames or bodies, each wheel frame or body having a rim, such that each assembled omnidirectional wheel generally has two rims. Each wheel frame supports a plurality of rollers. In the present utility model, each of the applicant's wheel frames supports 8 or 9 rollers, such that the assembled double-rim omnidirectional wheel has 16 or 18 peripheral rollers.

[0006] Objective

[0007] An objective of the present utility model is to solve one or more drawbacks of the prior art or at least provide a useful alternative.

[0008] The present utility model provides an omnidirectional wheel, which includes a wheel frame that supports a total of 8 or 9 peripheral rollers and a corresponding number of radially extending spokes. Each spoke includes a pair of radially extending curved spoke arms. The spoke arms converge radially outward to support a radial head. The radial head is adapted to support one end of a roller shaft that extends between an adjacent pair of radial heads on the same wheel frame. Each spoke arm has a geometric relationship with another spoke arm of the wheel frame, forming a multi-point star shape. This star shape repeats and overlaps throughout the wheel frame structure.

[0009] The star shape is preferably defined by a plurality of pairs of inline spoke arms that together have a geometric connection across the wheel rim. A pair of inline spoke arms is shaped to conform to a contour path that follows a symmetric curve between the plurality of pairs of inline spoke arms. The contour path has an average radius within 20% of 2R or R, preferably within 10% of R, where R is the radius of the omnidirectional wheel from the main central axis of rotation of the omnidirectional wheel to the outermost rim of the omnidirectional wheel corresponding to the ground contact surface of one of the rollers on the wheel carriage.

[0010] On the other hand, the omnidirectional wheel includes a wheel carriage that supports a total of 8 or 9 peripheral rollers and a corresponding number of radially extending spokes. Each spoke includes a pair of radially extending curved spoke arms that converge radially outward to support a radial head. The radial head is adapted to support one end of a roller shaft that extends between adjacent pairs of radial heads on the same wheel carriage. Each spoke arm has a geometric relationship with another spoke arm of the wheel carriage to form a pair of inline spoke arms having a geometric connection across the wheel carriage. The pair of inline spoke arms is shaped to conform to a contour path that follows a symmetric curve between the pair of inline spoke arms. The contour path has an average radius within 20% of 2R or R, preferably within 10% of R, where R is the radius of the omnidirectional wheel from the main central axis of rotation of the omnidirectional wheel to the outermost rim of the omnidirectional wheel corresponding to the ground contact surface of one of the rollers on the wheel carriage.

[0011] Wheel carriage

[0012] The omnidirectional wheel may include only one wheel carriage, for example, for transportation and sorting applications. The wheel carriage may be one of a plurality of wheel carriages for the assembly of the omnidirectional wheel. Generally, an omnidirectional wheel for a ground engagement application includes two wheel carriages having a corresponding pair of rims.

[0013] The omnidirectional wheel frame design involves competing space constraints. The space between the peripheral rollers must be maximized to ensure good overlap of diagonally adjacent rollers by minimizing the circumferential width of the spokes. However, the outer radial heads of the spokes that support the rollers cannot be too thin, otherwise their structure will be compromised. In addition, although the omnidirectional wheel frame must be strong, it is also preferably as lightweight as possible. Even more preferably, for each roller seat ring, the frame is integrally formed as one piece.

[0014] Roller

[0015] Each pair of adjacent heads has a roller shaft extending therebetween for supporting a peripheral roller to rotate about a roller axis perpendicular to the main axis.

[0016] Roller bushing

[0017] The roller preferably includes a bushing. The roller includes a sleeve material, such as a synthetic flexible rubber compound. The sleeve material can be overmolded onto the bushing to form the roller on the wheel carrier. Preferably, the bushing is in the form of a helical bushing as described by the applicant in WO2014089642.

[0018] Radial head

[0019] The radial head has a substantially trapezoidal or triangular head. The spoke has a double triangular structure, and the approach angle of the spoke arm at the spoke neck balances the triangular form of the radial head having an hourglass or "8-form" shape. The load applied to the radial head can be effectively dispersed to the spoke arms through the neck, enabling the wheel carrier to use a minimum amount of material.

[0020] Radial arm / spoke

[0021] Preferably, each spoke has a unique direct spatial and structural relationship through the central hub to two other spokes. The spoke arm of one spoke preferably follows a straight or curved line along the spaced-apart spoke arms of another spoke through the central hub to the wheel carrier. The straight or curved line can be a contour path.

[0022] The radial spokes extend from the central hub and are joined to the hub to form a central star-shaped frame with a recognizable number of overlapping star shapes. In the central star-shaped frame, each individual spoke defines a hollow triangular, diamond, or arrow shape.

[0023] Hub / hole

[0024] The bearing seat can be combined with an interchangeable inner hole. The inner hole can be a polygonal key inner hole, such as a hexagonal inner hole. The inner angles of the hole are preferably undercut so that the polygonal shape can be slightly deformed to hold the insert by friction fit or interference fit. The undercut can be an internal fillet that prevents splitting but allows bending, thus facilitating the accommodation of the polygonal-shaped insert.

[0025] Twin-rim wheel

[0026] The wheel may include a pair of omnidirectional wheel rims, each rim including a wheel carrier having a hub and 8 or 9 rollers. To engage a pair of wheel rims, the wheel carriers of one or both omnidirectional wheel rims may include a combination of protrusions and complementary recesses. The paired rims may be connected by an engagement involving an interference fit. The interference fit may involve inserting a pin of one shape (e.g., cylindrical) into a hole of a different geometry (e.g., hexagonal). The interference fit preferably includes a round pin inserted into a hexagonal hole, which may be described as a "Mattellock". Although it is anticipated that the inner wall of the hexagonal hole may be slightly deformed, it is believed that the pin deforms from its circular cross-section to exert a large surface pressure on the plane of the hexagon, rather than the hexagon deforming, as it is desired that the hexagon remains unchanged to accommodate the pin. The pin may have a diameter slightly larger than the maximum width of the hexagonal hole, e.g., about 0.05 mm - 0.3 mm larger. The arrangement may include an array of pins on the inner surface of the wheel body (central hub) of the first rim. Advantageously, circumferentially offset from the pin array may be a corresponding and complementary array of hexagonal recesses. The offset arrangement of the pin and recess arrays on the same inner hub surface allows two identical halves to be combined to form a double-rim symmetric wheel body. Additionally, providing convex engagement members and concave engagement members on the two identical halves provides a firm, two-sided symmetric engagement. Description of the Drawings

[0027] The present utility model can be better understood through the following non-limiting description of the preferred embodiments, wherein:

[0028] Figure 1a is a right perspective view of a double-rim omnidirectional wheel according to a first embodiment having 8 rollers;

[0029] Figure 1b is according to Figure 1a a left perspective view of the double-rim omnidirectional wheel according to the first embodiment shown;

[0030] Figure 1c is a front view of the omnidirectional wheel according to the first embodiment;

[0031] Figure 1d is a right view of the omnidirectional wheel according to the first embodiment;

[0032] Figure 1e is a top view of the omnidirectional wheel according to the first embodiment; Figure 2a is a front view of the omnidirectional wheel according to a second embodiment having 9 rollers;

[0033] Figure 2b is a rear view of the omnidirectional wheel according to the second embodiment having 9 rollers;

[0034] Figure 3is a rear perspective view of a single wheel carrier, which is one of two wheel carriers forming part of an omnidirectional wheel according to the second embodiment;

[0035] Figure 4 is a rear view of the central hub of an omnidirectional wheel according to the second embodiment;

[0036] Figure 5a is according to the second embodiment Figure 3 front view of the single-rim omnidirectional wheel shown;

[0037] Figure 5b is Figure 5a an enlarged view of part A in;

[0038] Figure 6a is Figure 5a front view of the single-rim omnidirectional wheel shown;

[0039] Figure 6b is Figure 6a an enlarged view of part B in;

[0040] Figure 7 is also the front view of a single-rim omnidirectional wheel according to the second embodiment shown in Figure 5a but rotated 30°;

[0041] Figure 8a is a cross-sectional view along the Dt-Dt section of Figure 7 ;

[0042] Figure 8b is Figure 8a an enlarged view of part E in;

[0043] Figure 9 is a side view of a roller forming part of the first or second embodiment and having 13 annular ribs;

[0044] Figure 10 is a side view of a roller forming part of the first or second embodiment and having 9 annular ribs;

[0045] Figure 11a -c is a side-by-side comparison of perspective views of actual images of prior art omnidirectional wheels and omnidirectional wheels of the first and second embodiments standing parallel to each other;

[0046] Figure 12a - Figure 12c are respectively the front view, rear view and perspective view of a single-rim wheel carrier which is one of two wheel carriers forming part of an omnidirectional wheel with a wheel diameter of 127 mm according to the first embodiment;

[0047] Figure 13a - Figure 13cThe front view, rear view and perspective view of a single - rim wheel carrier which is one of the two wheel carriers forming part of an omnidirectional wheel with a wheel diameter of 150 mm according to the second embodiment; and

[0048] Figure 14a - Figure 14b The front view and perspective view of a single - rim wheel carrier which is one of the two wheel carriers forming part of an omnidirectional wheel with a wheel diameter of 127 mm according to the first embodiment. Detailed implementation manners

[0049] Preferred features of the present utility model will now be described with particular reference to the accompanying drawings.

[0050] Definitions, meanings, limitations and explanations

[0051] Omnidirectional wheel

[0052] The accompanying drawings show an omnidirectional wheel 100, each of whose wheel carriers 140 or wheel seat rings has 8 rollers 104. The accompanying drawings also show an omnidirectional wheel 200 according to the second embodiment, each of whose wheel carriers 140 has 9 rollers 104. When describing the omnidirectional wheels 100, 200 with reference to the accompanying drawings, the same features are given the same reference numerals. The wheel carrier 140 of each omnidirectional wheel 100, 200 includes a central hub 150, from which a plurality of radially extending spokes 110 extend, each spoke 110 terminating at an outer radial head 112. Each pair of adjacent radial heads radially spaced from the central hub 150 has a roller shaft in the form of a solid cylindrical rod extending therebetween for supporting the roller 104, and the roller 104 is adapted to rotate about an axis 105 which is perpendicular to a radial line 124 extending from the main axis of rotation 108 of the wheel 104. Wherein, the outer periphery of the central hub 150 includes a plurality of solid triangular bases 147 radially aligned with the corresponding rollers 104. Each pair of adjacent triangular bases 147, together with a pair of radially outwardly extending spoke arms 146, define a triangular, rhombic or arrow - shaped hollow portion 142 therebetween, and a pair of outwardly extending spoke arms 146 converge and intersect to form a spoke neck portion 134 for supporting a corresponding radial head 112.

[0053] Figure 1a - Figure 3 An omnidirectional wheel 100 according to the first embodiment of the present invention is shown. The omnidirectional wheel has a pair of parallel - plane, coaxially - aligned and adjacent roller seats 101, 102. Each roller 104a of the first seat 101 is offset from each diagonally - adjacent roller 104b in the second seat 102. The offset arrangement of the rollers 104a of the first seat 101 is complementary to the positioning of the rollers 104b of the second seat, so that in Figure 2aIn the side view shown in -b, a continuous, substantially circular peripheral surface 106 is presented. The continuous peripheral surface 106 enables the wheel 100 to provide a smooth and non-bumpy ride when rotating about the main axis 108. Each roller 104 is mounted on a roller shaft that is supported between a pair of adjacent radial heads located at the ends of the radially outwardly extending spokes 110. The radial heads 112 are slightly radially recessed so that the roller 104 (rather than the radial head 112) contacts the external surface (such as the ground).

[0054] Roller

[0055] The omnidirectional wheel may include two or more seats for the rollers 104, and each seat 101, 102 forms a rim.

[0056] The roller 104 has a truncated spindle shape, a solid torpedo shape, or a cigar shape. The outer surface 114 of the roller 104 is slightly convexly curved to correspond to the approximate overall radius R of the omnidirectional wheel 100. The roller 104 has a consistent length to correspond to a common (within the applicant's product range) bushing 120, although their diameters and the radius of curvature of their outer surfaces 114 may vary according to the size of the omnidirectional wheel. Internally, within its own omnidirectional wheel product range, the applicant has standardized the length of its rollers 104 to a length of approximately 28.5 mm. According to the main radius R of the omnidirectional wheel 100, the curve of the outer surface 114 of the roller 104 can vary to correspond to radii of 45 mm, 63.5 mm, 75 mm, and 90 mm, corresponding to omnidirectional wheels 100 with diameters of 90 mm, 127 mm, 150 mm, and 180 mm, respectively. However, the constant length of the roller 104 allows the applicant to use the same bushing 120 within the scope of future omnidirectional wheels 100.

[0057] The preferred roller surface has as Figure 9 - 10The ribbed profile 116 shown. Regardless of the diameter of the roller 104, the pattern of the ribs 116a can be consistent across a range of wheels 100. The number of radial ribs 116a is an odd number, 9, 11, or 13, where correspondingly, on either side of the 5th, 6th, or 7th center rib 116b, 116bi, there is an equal even number of ribs 116a, 116ai that extend to either end of the roller 104 on either side of the center rib 116b, 116bi. Due to the gaps, clearances, or grooves 118, 118i between the outermost ribs 116c, 116ci and the penultimate outermost ribs 116d, 116di allowing significant clearance for the outermost ribs 116c, 116ci, the outermost ribs 116c, 116ci have a high ability to flex and elastically deform at each end. This enables smooth and bump-free transfer from one roller 104a to its diagonally adjacent roller 104b. Additionally, overall, the elastic deformation ability of the ribbed profile 116 and the individual ribs 116a - d improves the smoothness of the travel of the omnidirectional wheel 100.

[0058] On either side of the wide center rib 116b of the rollers 104, 104i are shallow grooves 118, 118i. The grooves 118, 118i gradually deepen towards the penultimate ribs 116d, 116di and the outermost ribs 116c, 116ci.

[0059] Spiral roller bushing

[0060] Special attention Figure 2b - Figure 3 , reference Figure 4 - 9 and specifically reference Figure 9 describes the omnidirectional wheel seat ring 201, noting that the discussion pertains to all embodiments of the present invention described in this specification. The bushing 120 is in the form of the spiral bushing 10 described by the applicant in PCT Application No. 2014089642, the entire content of which is incorporated herein by reference. The spiral bushing 120 is advantageously overmolded with the roller sleeve material 117 that forms the ribs 116a, and the ribs 116a are molded onto the bushing 120 to form the roller 104. This requires more than the minimum area 122 of the roller sleeve material 117 that consists of the corresponding ends of the bushing 120 to be able to close the sleeve molding tool (not shown). If the minimum area 122 is too small, it may be difficult to stop the flash of the sleeve material 117. The flash can be removed, but additional steps may be required and / or additional manufacturing time may be needed. If the minimum area 122 is too large, the roller length 117a or its diameter needs to be reduced, which adversely affects the smoothness of the transition from the roller 104a to its diagonally adjacent roller 104b, which impairs the ride quality. Refer to Figure 2b, in roller 104 with a roller sleeve length of 25 - 30 mm, preferably 28 - 29 mm, and most preferably 28.5 mm, the minimum area 122 can vary between 1.5 - 2 mm, preferably 1.8 - 1.9 mm, and most preferably, the minimum area 122 is approximately 1.85 mm, regardless of the number of ribs 116a.

[0061] Wheel carrier

[0062] The wheel carrier 140 can be made of a strong moldable or castable material, such as titanium or other expensive lightweight metals and their alloys, and preferably a strong plastic, such as acetal.

[0063] The wheel carrier 140 for each omnidirectional wheel race includes a radial head 112. Extending between adjacent radial heads 112c of the wheel carrier 140 of a single race is the roller shaft 480. The radial head 112 and the roller shaft 480 (both in the same plane of the wheel frame 140) are combined by a continuous one-piece molding connection to form a continuous polygonal ring structure. As can be seen in Figure 12a -c, the roller shaft 480, the spokes 110, and the central hub 150 are all formed by the same single material mold. This forms an extremely strong wheel carrier 140 structure including the roller shaft 480. The spokes 110 (including the spoke arms 146, the spoke necks 134, and the radial heads 112) are formed from a continuous material without separate parts, joints, or fastening connections to the central core or central hub 150 of the wheel carrier 140. The central core mainly includes the central hub 150.

[0064] The multi-axis ring (a combination of the outer peripheral part of the wheel carrier 140, including the radial head 112 and the roller shaft 480) acts in tension with the spokes 110 and the central core 150 to support the radial head 112 and hold it firmly in place relative to the core 150 against forces that would deform the wheel carrier 140. In use, when a compressive force F is applied to the ground contact roller 104 and the roller shaft 480 on which it is mounted, the force F is radially dispersed inward through the radial head 112 integrally formed with the load-bearing roller shaft 480. The force F is further dispersed through the roller shaft 480 integrally formed with the radial heads 112 on both sides of the bearing shaft 480, and thereafter dispersed to the entire wheel carrier 140 including the spokes 110 and other roller shafts 480.

[0065] The force F is further dispersed through the spokes 110, each of which has a unique spatial and structural relationship through the central hub 150 to at least one other spoke 110.

[0066] Radial head

[0067] The radial head has a head 132 that is substantially trapezoidal or triangular. The spoke 110 has a double triangular structure (radial head 132, spoke arm, and base triangle 142), where the approach angle of the spoke arm 146 at the spoke neck 134 balances the triangular form of the radial head 132 having an hourglass or "figure 8" shape. The load applied to the radial head 132 can be effectively dispersed through the neck 134 to the spoke arm 146, enabling the formation of the wheel carrier 140 using a minimum amount of material.

[0068] The wheel carrier 140 for each omnidirectional wheel race 201, 202 includes a radial head 132, a roller shaft extending between each pair of adjacent radial heads 132, a spoke neck 134, a spoke arm 146, and a central hub 150, all of which are formed from the same unitary single mold of material.

[0069] Impact on the radial head 112 may occur during use. This can damage or collapse the end material of the bushing 120, which increases friction and limits the rotation of the roller 104. The overall form of the wheel carrier 140, including an internal circular central hub 150 and an external integral continuous roller shaft ring, provides a high-strength wheel carrier 140 resistant to deformation caused by radially inward impact forces, with the central hub 150 and the radial head 132 radially bridged by corresponding overlapping and mutually reinforcing pairs of inline spoke arms 146.

[0070] The radial head 112 includes a generally triangular head 132 that is continuous and adjacent to a narrow neck 134 and a central hub 150 that is radially located in the middle of the length of the spoke 110. The head has a radially outermost end wall 136 that has a curve with a radius approximately corresponding to or equal to the radius R of the omnidirectional wheel 100. The head 132 has side walls 138 that extend at an angle θ relative to a virtual radial line extending from the main axis 108, with the angle θ ranging from 17° - 23°, preferably approximately 20°. This positions the side walls 138 at an angle perpendicular to the axis of rotation 105 of the opposing roller 104 (which is coaxial with the corresponding roller shaft) and adjacent and parallel to the plane 124 in which the end edge of the bushing end 120 lies. The corner 133 transition between the outer wall 136 and the side walls 138 is rounded. This provides room for the edge of the bushing end 120 to distort without applying pressure to the material through adjacency. This is counterintuitive because the load applied radially inward through the head 132 is expected to distort the end ribs 116c - d of the roller 104 away from the head 132. However, this geometric and structural relationship between the head 132 and the bushing 120 reduces the stress and load on the edge of the bushing end 120.

[0071] Radial arm / spoke

[0072] The radial spokes 110 extend from and are joined to a central hub 150 to form a central star frame (see Figure 2a 、 6a and 10, which outline the 3- and 4-point star shapes formed by the hub 150 and the multiple sets of spokes 110). The star shape is a plurality of overlapping star shapes that are recognizable.

[0073] The central star frame includes 3- or 4-point sub-units for the respective 9 and 8 roller seats of the omnidirectional wheels (omnidirectional wheels 100, 400), where the diagonally adjacent overlapping rollers 104 include multiples of 9 and 8 rollers 104. The spoke arms 146 of each pair of spoke arms 110 belong to a spoke 110 that is adapted to elastically bend inwardly towards the other spoke arm 146 of the pair of spoke arms 146.

[0074] The paired spoke arms 146 belonging to the spoke 110 can be curved and in the form of inwardly arched walls 148, each spoke arm 146 extending radially outward from the triangular base they form to a neck. The arched walls, together with the central star frame including the central hub 150 and the triangular base, resist compression radially against the centripetal load applied to the omnidirectional wheel 100.

[0075] The radial spokes 110 extend from the central hub 150 and are joined to the hub 150 to form a central star frame 140, where each individual spoke 110 defines a hollow triangular, diamond, or arrow shape 142. The hollow shape 142 is shallowly defined in the facia by an innermost crescent-shaped wall 143 having a vertex 143a closest to the main axis 108 and a pair of obtuse-angled (about 110° - 140°, preferably about 120° - 130°, and most preferably about 125°) diverging walls 144 extending outward from the vertex 143a. However, the structural base of the diverging walls 144 is located at the outer cylindrical wall 156 (or 256 in the second embodiment).

[0076] The hollow shape 142 is bilaterally symmetric, and the diverging walls 144 are each transitioned by an interior angle 143b, and a pair of converging walls 145 extend outward from the interior angle 143b to meet at the interior angle 143c of the outer acute angle. The acute angle is preferably between 38° - 50°, preferably between 40° - 45°, and most preferably about 43°. The converging walls 145 form the inner sides of a pair of converging arms 146 that meet at the neck 134. The converging arms 145 are concavely curved such that when they meet at the neck 134, they bend towards each other.

[0077] The wheel frame 140 is star-shaped and is combined with the frame of the generally circular central hub 150. It is extremely light and strong, providing flexibility because the converging arms 146 bend elastically inward, while the peripheral roller collar and the radial head 132 structure stabilize each spoke 146 and increase the rigidity of the overall wheel frame 140. The converging arms 146 bend against their bases 147. The adjacent converging arms 146 of adjacent radial spokes 110 meet at the triangular base 147, which extends outward from the circular hub 150 to support each hollow shape 142. The innermost vertex 143a is preferably positioned radially adjacent to the periphery of the central hub 150. Thus, the bent converging arm 146 includes an inwardly arched wall 148, which extends from the radially outer intersection point 146b of the converging arm 146 to the inner end 146a of the arm 146 base. The arched wall 148, together with the star-shaped central frame 140 including the central hub 150, provides a very strong and light structure, which radially resists compression from the centripetal load applied to the omnidirectional wheel 100. Specifically, each spoke 110 has a three-leaf relationship with two other spokes to form a three-point star shape. The profile L of the first spoke arm 146c of the first spoke 110a at its inner end is consistent with the nearest spoke arm 146b of the second spoke 110b that is set at 120° relative to the first spoke 110a. This is a structural aspect that provides strength to the entire wheel frame 140, where each individual thin spoke arm 146 directly resists the centripetal force applied through the inline spoke 110b. The thin spoke arm 146 has a thickness in a plane that is substantially parallel to the plane of the omnidirectional wheel 100 at the midpoint of the arm 146, and this thickness is in the range of 3-10% of the radius R of the omnidirectional wheel, preferably in the range of 4-7%, and most preferably about 5%. In this way, each spoke arm 146c has a corresponding opposite spoke arm 146d, which is adapted to resist the compressive force applied through it, and the respective bases 146a of each inline spoke arm 146c, 146d are circumferentially offset from each other by about 75°-85°, preferably 80°.

[0078] The radius r of the outer wall of the spoke arm 146 extending between its inner end 146a and its outer radial length 146b at the confluence with its paired spoke arm 146 is in the range of + / - 10% of the radius R of the omnidirectional wheel 100 intercepted from the main axis 108 to the outer periphery 106. Preferably, the radius R of the omnidirectional wheel 100 is substantially equal to the outer wall radius r of the spoke arm 146.

[0079] Each converging arm 146 extends from or near the radially outer vertex 149 of each triangular base 147. Two converging arms 146 extend from each triangular base 147 and extend outward in a curve that is close to a pure radial line until the converging arm 146 reaches the arrow neck 134, and then the continuous wall of the spoke 110 continues the curve as it transitions to the radial head 112 and the diverging curve of its triangular head 132.

[0080] Contour path

[0081] In Figure 6a it, an omnidirectional wheel carrier 140 of a seat ring 201 having nine rollers 104 is shown highlighting a repeating and overlapping triangular three-point star structure in the carrier 140. Each first spoke arm 146a in the side profile has a geometric relationship with a different second spoke arm 146b belonging to a different radial spoke 110b such that the first spoke arm 146a and the second spoke arm 146b are along a common contour path, which common contour path follows a curve L9 without inflection points, and the curve L9 extends through and between the first spoke arm 146a and the second spoke arm 146b. The average radius of the contour path is within 10% of the radius 2R (intercepted from the main axis X to the outer peripheral surface 106 of the omnidirectional wheel 100). The second spoke arm 146b belongs to a radial spoke 110b that is not adjacent or opposite to the radial spoke 110a of the first spoke arm 146a.

[0082] The radius r of the curve L9 (or L1, L2, L3) of the triangular star structure is the same as or close to twice the radius R of the omnidirectional wheel 200. The curves L1 - L3 form a triangular star shape, as Figure 2a shown, which is a repeating and overlapping pattern around the carrier 240.

[0083] Figure 1c An omnidirectional wheel 100 according to a first embodiment is shown, which includes a pair of rims 101, 102, each rim including eight rollers 104. The rollers 104 are supported by radial spokes 410 arranged in an overlapping four-point star shape defined by four curves L8.

[0084] Figure 14a A single omnidirectional wheel carrier 440 according to a first embodiment is shown, wherein the carrier 440 is adapted to form part of an assembled double-rim omnidirectional wheel 100, and each carrier 440 is adapted to support eight rollers. The carrier 440 has eight radial spokes 410 arranged in an overlapping four-point star shape (also see Figure 12a , which shows a curved dashed line following the contour of the curve L8).

[0085] Each first spoke arm 446a in the side profile has a geometric relationship with a different second spoke arm 446b belonging to a different radial spoke 410b such that the first spoke arm 446a and the second spoke arm 446b are placed along a common contour path that follows a curve L8 without inflection points, and the curve L8 extends through and between the first spoke arm 446a and the second spoke arm 446b. The average radius of the contour path is within 10% of the radius R of the omnidirectional wheel 400 (intercepted from the main axis to the peripheral surface 406 of the omnidirectional wheel 400). The second spoke arm 446b belongs to a radial spoke 410b that is not adjacent or opposite to the radial spoke 410a of the first spoke arm 446a.

[0086] Figure 11a - Figure 11c A side-by-side comparison of a prior art omnidirectional wheel manufactured by the applicant with the omnidirectional wheels 100, 400 according to the first and second embodiments is shown. The difference in the geometry of the triangular heads 112, 412 is that, compared to the prior art example, the head is flatter and the head side walls facing the ends of each bushing 120, 420 and from which the roller shafts extend are less inclined to the radial lines extending from the main axis X. In combination with the double triangular, hourglass, dumbbell or "figure 8" structure of each spoke 110, 410 and its slender narrow neck 134, 434. The narrowness of the side profiles of the necks 134, 434 and the spoke arms 146, 446 does not present a weakness in the frames 140, 440. The necks 134, 434 and the spoke arms 146, 446 extend from one side of the omnidirectional wheels 100, 400 to the other side, making full use of the entire width of the central hubs 150, 450, since the width of the wheel carriers 140, 440 tapers radially outwards along the profiles F1, F2. The narrowest width of the wheel carriers 140, 440 corresponds to the width of the neck-radial head transition. The width of the spokes 110, 410 radially outwards from the central hubs 150, 450 in a plane parallel to the main axis X is never greater than any part of the spokes 110, 410 radially inwards.

[0087] Refer to Figure 12a - Figure 12c , Figure 13a - Figure 13c , a comparison of the omnidirectional wheel carrier 440 including 8 roller shafts 480 with the carrier of the 9-roller shaft version of the omnidirectional wheel 200 is shown. The roller shafts 480 are integrally formed as part of the wheel carrier 440 with the central hub 450 and the radial spokes 410 including the radial heads 432 in a single mold.

[0088] Figure 14a A hollow triangular structure 490 formed at the base of the spoke 410 by a pair of radial arms 446i-ii belonging to the spoke 410 is shown. The continuous curve L8 along the shared contour of the inline spoke arms 446a-b is at Figure 12b and14a is shown. Refer to Figure 2b and Figure 13a - Figure 13b , the geometry of the nine-roller carrier 240 is shown as having a structure strengthened by a symmetric array of repeating and overlapping triangular star structures defined by curves L1 - L3 that follow the curved profile of each spoke arm 146b to another spoke arm 146d of a spoke 110b that is not adjacent to the first spoke 110a. This repeating triangular pattern provides an extremely robust carrier 240 body.

[0089] Non - adjacent spoke arms in the nine - roller carrier 240 that are separated by only one intermediate spoke 110 also have a strong geometric relationship through curve L8i, as Figure 13a shown. However, unlike the 4 - point star shape of the eight - roller carrier 440 or the 3 - point star shape of the nine - roller carrier 240, the L8i curve does not form part of a symmetric multi - point star - shaped structure.

[0090] Hub / Bore

[0091] The central hub 150 includes a bearing seat 160 which, in the second embodiment described with reference to Figure 4 - Figure 9 , is combined with a hexagonal inner bore 162. The hexagonal inner bore 162 can be replaced by other polygonal shapes (such as a pentagon or a square keyhole). The corners 164 of the bore 162 are undercut to maintain a friction fit for an insert (not shown), which is enhanced by the slight deformation of the polygonal shape 162 allowed by the undercut 164. The undercut 164 is an internally rounded corner that prevents cracking but allows bending, whereby the bore 162 can be slightly deformed to accommodate a slightly over - sized polygonal insert.

[0092] As Figure 6b shown, the hub bore is fixed in the cylindrical bearing seat 160. During manufacture, different configurations or keyed inner bores can be inserted into the bore seat 160 to accommodate different applications.

[0093] Dual - Rim Wheel

[0094] Figure 3 , Figure 4 and Figure 7 - Figure 8bDevice 270a for connecting a pair of wheel seats 201, 202 is shown. Features similar to those of the first embodiment share similar numbers, where the representation with a hundred is replaced by the representation with a two-hundred (e.g., 100 is represented by 200). The pair of seats 201, 202 are connected by an interference fit, which is characterized by inserting a pin of one shape into a hole with a different geometry. In the example shown, this joint 270 includes a round pin 272 inserted into a hexagonal hole 274. The inner wall of the hexagonal hole 274 abuts against the cylindrical pin 272, and the cylindrical pin 272 is slightly distorted to provide resistance and an interference fit. The hexagonal hole 274 houses the pin 272. The pin 272 has a diameter slightly larger than the maximum width of the hexagonal hole 274. Device 270 includes a pin array 272a on the inner surface 271 of the wheel body of the first seat 201. Advantageously, circumferentially offset relative to the pin array 272a is a corresponding and complementary array of hexagonal recesses 274a. The offset arrangement of the arrays 272a, 274a on the same surface 271 allows for the combination of two identical halves 201, 202 to form a double-seat symmetric wheel body 200.

[0095] The central hub 150 defines a circular seat 160, which provides flexibility in the hole 162, and the hole 162 can be deployed according to the dimensions and shaft key or journal requirements for a particular application. For example, for a conveying application, the driven robot wheel 200 compared to the freely rotatable wheel 100.

[0096] Tensile distribution of force

[0097] In Figure 7 - Figure 8a it is shown the structural relationship between the diameter D of the roller 104 and the depth d of the spoke 110 at its respective base 147 in a direction parallel to the axis 108 of the hole 162. The diameter D is equal to or close (within 10%) to the depth d. After a short shoulder at the base 147, the outer surface 275 of the spoke 110 inclines inward as it extends radially outward at an angle μ relative to the inner wall 276 of the spoke 110, where μ is less than 20°, more preferably between 14 - 18°, and most preferably 16°. At the transition between the spoke arm 146 and the neck 134, there is a bend away from the inner wall 276 at an angle β, where β is the same as or close to (within 20%) the angle μ, more specifically less than 25°, more preferably between 18 - 20°, and most preferably 19°. The outer surface 275 and the inner surface 276 of the neck 134 extend in directions approaching each other (within 5°) until the radial head 112.

[0098] As Figure 8aAs shown, the angle β corresponds to the angle at which the radial head 112 extends forward (away from the complementary rim 202 that forms part of the assembled dual-rim omnidirectional wheel 200). The bend defined by the angle β is located at the neck 134 of the spoke 110. The angle β is an obtuse angle formed with the inclination angle F2 of the front surface or outer surface 275, since the front surface 275 and the rear surface 276 extend substantially parallel to each other. This spatial relationship and positioning of the spoke 110 recessed from the outer surface of the central hub 150 and the radial head 112 extending away from its complementary mating rim 201 in the assembled omnidirectional wheel 200 protects the spoke from impact damage and optimizes the space between diagonally adjacent rollers 104a, b to reduce the risk of rolling interference with each other.

[0099] The meanings of descriptive, precise or absolute terms such as "bent", "orthogonal", "parallel", "horizontal", "vertical" or "perfect" include the qualifying words "substantially or nearly" preceding them, unless the context or a contrary meaning is clearly indicated.

[0100] Qualifying relative terms such as "relative", "sufficient", "close", "almost" or "substantially" may be used to indicate an absolute value change between 0° and 10° or between 0% and 10% relative to an absolute value. For example, "close to horizontal" may represent any direction between 0° and 10° relative to the horizontal line.

[0101] In this specification, the term "integral" means formed in one piece in a single process. Specifically, the term "formed integrally" means formed in one piece without attaching separately formed component parts after molding. That is, "formed integrally" and the similar term "formed as a whole" mean formed in a single forming process and do not include attaching component parts after formation by fastening means or other means of fixing substances or methods.

[0102] Directional terms used in the specification and claims, such as vertical, horizontal, top, bottom, upper and lower, should be interpreted as relative and based on the premise that the component, article, item, device, equipment or instrument is generally considered to be in a specific orientation, i.e., in the current context, the main axis is horizontal.

Claims

1. An omnidirectional wheel, comprising a wheel carrier that supports a total of eight or nine peripheral rollers and a corresponding number of radially extending spokes, characterized in that, Each spoke includes a pair of radially extending curved spoke arms that converge radially outwardly to support a radial head, the radial head being adapted to support one end of a roller shaft that extends between adjacent pairs of radial heads on the same wheel carriage. Each spoke arm has a geometric relationship with another spoke arm of the wheel carriage to form a multi-point star shape that repeats and overlaps across the entire wheel carriage structure.

2. The omnidirectional wheel according to claim 1, wherein the star shape is defined by a plurality of inline pairs of spoke arms that have a geometric connection across the wheel carriage, the inline pairs of spoke arms being designed to conform to a contour path (L8, L9) that follows a symmetric curve between the inline pairs of spoke arms, the contour path (L8, L9) having an average radius within 20% of 2R or R, where R is the radius of the omnidirectional wheel from the main central axis of rotation (108, X) of the omnidirectional wheel to the outermost rim (116) of the omnidirectional wheel corresponding to the ground contact surface (106) of one of the rollers (104) on the wheel carriage.

3. The omnidirectional wheel according to claim 1, wherein each said spoke (110) includes a pair of outwardly extending spoke arms that are wider spaced and converge at the central hub to meet at a spoke neck (134).

4. The omnidirectional wheel according to claim 1, wherein each roller (104) has a sleeve overmolded onto a bushing mounted on the roller shaft of the wheel carriage, and the side walls of the radial heads (112, 412) facing the ends of each bushing (120, 420) are inclined relative to a radial line extending from the main axis X to provide a double triangular structure for each spoke, with the spoke neck located in the middle of the double triangular structure.

5. The omnidirectional wheel according to claim 4, wherein the spoke neck and the spoke arms extend from one side of the omnidirectional wheel to the other side, corresponding to the entire width of the central hub (150, 450) and tapering radially outwardly such that the narrowest width of the wheel carriage corresponds to the width of the spoke neck (134)-radial head (112) transition portion.

6. The omnidirectional wheel according to claim 5, wherein the width of the spoke (110) radially outward from the central hub (150) in a plane parallel to the main axis (X) is never greater than any part of the spoke (110) radially inward thereof.

7. An omnidirectional wheel, comprising a wheel carrier that supports a total of eight or nine peripheral rollers (104) and a corresponding number of radially extending spokes (110), characterized in that, Each spoke (110) includes a pair of radially extending curved spoke arms that converge outwardly to meet at a spoke neck (134) that supports a radial head (112), the radial head (112) being adapted to support one end of a roller shaft (480) that extends between adjacent pairs of radial heads (112) on the wheel carriage, each roller shaft having a roller (104) mounted thereto, each spoke arm having a geometric relationship with another spoke arm of the wheel carriage to form a pair of inline spoke arms having a geometric connection across the wheel carriage, the pair of inline spoke arms being designed to conform to a profile path that follows a symmetric curve between the pair of inline spoke arms, the profile path having an average radius within 10% of 2R or R, where R is the radius of the omnidirectional wheel from the main axis (X) of the omnidirectional wheel to the contact surface (106) of the roller (104).

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