Wheels for use with a transport vehicle equipped with differential steering, and a transport vehicle equipped with differential steering

Abstract

A wheel is described, comprising a hub portion configured to rotate about an axis, and a ground contact area surrounding the hub portion, the ground contact area being formed from several segments, each of which is configured to typically take a fixed position and move to one side of its fixed position relative to the hub, along a path of travel substantially lateral to the circumference of the hub portion, by a limited distance from its fixed position, the wheel further includes means for returning each of the segments to its fixed position, the internal area of ​​each segment being positioned to support the hub, lifted off the ground surface, and moving by sliding against the outside of the hub portion.

Description

Technical Field

[0001] The present invention relates to a wheel that is particularly suitable for use in a carrier or vehicle with a differential steering configuration. Embodiments of the present invention find particular use in the use of electric wheelchairs and other carriers that can also be used in places where pedestrian traffic exists, such as in public spaces, on sidewalks, and inside buildings.

Background Art

[0002] Differential steering is a means of maneuvering a land vehicle by applying more driving torque to one vehicle than the other. Advantages of differential steering include mechanical simplicity and the ability to create a more robust vehicle. Differential steering is the primary means of maneuvering tracked vehicles such as tanks and bulldozers and is also commonly used in certain wheeled vehicles known as skid-steer vehicles.

[0003] In skid-steer wheeled vehicles, the wheels are typically fixed in their orientation and always aligned with the forward direction of travel of the vehicle. When turning, by applying more torque to some wheels than others, one or more of the plurality of wheels "skid" across the surface on which the vehicle travels.

[0004] The skidding of the wheels (or tracks) optimizes the use of these types of vehicles on soft ground, such as traveling on soil, sand, or other soft ground. When used on a hard surface, the wheels or tracks can experience a high wear rate. Additionally, the road surface on which the vehicle or carrier travels can be damaged by the wheels or tracks. Further, skidding is an inefficient way to turn and results in energy loss.

[0005] Attempts are being made to address the aforementioned problems of lateral slippage by using so-called "omnidirectional" wheels, such as omniwheels or Mecanum wheels. These wheels have lateral rollers mounted around their outer edge. However, such a configuration can make it difficult to control a vehicle on an inclined surface, as the vehicle may slide uncontrollably laterally down the slope. Furthermore, the load-bearing capacity of these types of wheels is limited by the strength of the lateral roller axles. Therefore, to support heavy loads, very large wheels must be used to accommodate rollers and axles of sufficient strength, which in some applications necessitates the use of impracticalally large wheels.

[0006] There is still a need to provide improvements to the differential steering configuration of vehicles and transport vehicles. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] PCT Application / Australian Patent Application Publication No. 2018 / 051065 Specification [Overview of the Initiative]

[0008] In a first aspect, the present invention provides a wheel comprising a hub portion configured to rotate about an axis, and a ground contact region surrounding the hub portion, the ground contact region being formed of several segments, each of which is configured to typically take a fixed position and move to one side of its fixed position relative to the hub, along a path of travel substantially lateral to the circumference of the hub portion, by a limited distance from its fixed position, the wheel further includes means for returning each of the segments to its fixed position, the internal region of each segment being positioned to support the hub, lifted off the ground surface, and moving by sliding against the outside of the hub portion.

[0009] Each segment may be arranged to move by rotating around the region of the hub.

[0010] Each segment may be positioned to move laterally relative to the hub.

[0011] The path of each segment may be limited by the area of ​​each segment that is in contact with the hub.

[0012] The inside of each segment may coincide with the outside of the hub.

[0013] The hub portion may include a series of projections that alternate with the segments, which guide the lateral movement of the segments and support the segments in the circumferential direction of the hub portion during braking and acceleration.

[0014] The means for returning each segment to its designated position may take the form of a biasing mechanism.

[0015] The biasing method can be magnetic.

[0016] Each segment may include at least one region of the elastic material, and the biasing means functions by the elastic deformation of the elastic material.

[0017] The segment can be snap-fitted to the hub.

[0018] The segment may engage with a guide as a means of returning the segment to its designated position.

[0019] The guide may be located inside the cowl that partially encloses the wheel.

[0020] In a second aspect, the present invention provides a transport vehicle including ground-contacting wheels, at least one of which conforms to the first aspect of the present invention.

[0021] Herein, embodiments of the present invention will be described only as examples with reference to the accompanying drawings. [Brief explanation of the drawing]

[0022] [Figure 1] It is a perspective view of the wheel. [Figure 2] It is a side view of the wheel of FIG. 1. [Figure 3] It is a front view of the wheel of FIG. 1. [Figure 4] It is a vertical cross-sectional view passing through the figure of FIG. 3. [Figure 5] It is a side view of the hub portion of the wheel of FIG. 1. [Figure 6] It is a front view of the hub portion of FIG. 5. [Figure 7] It is a cross-sectional view passing through line A-A of FIG. 5. [Figure 8] It is a cross-sectional view passing through line B-B of FIG. 5. [Figure 9] It is a bottom perspective view of the electric wheelchair. [Figure 10] It is a schematic diagram showing that the differential steering is used to cause the left turn of the wheelchair of FIG. 9. [Figure 11] It is a cross-sectional view similar to FIG. 4 during a left turn. [Figure 12] It is a cross-sectional view similar to FIG. 4 during a right turn. [Figure 13] It is a cross-sectional view of another embodiment of the wheel during a right turn. [Figure 14] It is a cross-sectional view of another embodiment of the wheel. [Figure 15] It is a cross-sectional view of another embodiment of the wheel. [Figure 16] It is a side view of another embodiment of the wheel. [Figure 17] It is a cross-sectional view along line A of FIG. 16. [Figure 18] It is a bottom perspective view of the cowl of the wheel of FIG. 16. [Figure 19] It is a side cross-sectional view passing through the cowl of FIG. 18. [Figure 20] It is a perspective view of another embodiment of the wheel. [Figure 21] It is a side view of the wheel of FIG. 20. [Figure 22]This is a cross-sectional view along line A in Figure 21. [Figure 23] Figure 20 is a perspective view of the wheel hub. [Figure 24] This is an upper perspective view of one of the segments from the wheel in Figure 20. [Figure 25] This is an alternative perspective view of the segment in Figure 24. [Figure 26] Figure 20 shows alternative versions of segments that can be used with the wheel. [Modes for carrying out the invention]

[0023] Referring to Figures 1 to 4, the wheel 10 shows a hub portion including a stainless steel hub member 20. When in use, the hub member 20 is attached to the shaft 100 (see Figure 4) using a keyed opening 21 and is positioned to rotate on the shaft about the central axis.

[0024] The ground contact area, formed from several segments 30, surrounds the hub member 20. The segments, as indicated by the ground A, are in contact with and support the ground during use.

[0025] As best seen in Figure 4, each segment is formed from a nylon circlip body 32. The area of ​​the rubber tread 34 is bonded to the outside of the circlip 32, and the magnet 36 is embedded inside the circlip. The circlip 32 snaps into place around the hub member 20.

[0026] The outer region 23 of the hub member 20 is torus-shaped overall. The inner surface of each segment 30 coincides with the outer surface of the hub member 22. The magnets 26 fit into the hub member 20 and are covered by a protective sheath 28. The magnets 26 are oriented in each of the segments 30 to attract the corresponding magnets 36. That is, in a pair of magnets, the north pole of one magnet points towards the south pole of the other magnet.

[0027] Each of the segments 30 moves freely by rotating relative to the hub member 20 for a limited distance substantially lateral to the circumference of the hub, along a curved path of travel around the hub. As shown in Figure 4, the attractive forces of magnets 26 and 36 bias each segment to a central fixed position. As will be described later, if the biasing force of magnets 26 and 36 is overcome, each segment can rotate to one side of its fixed position during use.

[0028] The hub member 20 includes several protrusions in the form of paddles 40, which are arranged alternately with the segments 30 and contact and support the segments 30 when in use during braking and acceleration.

[0029] Referring to Figures 5 to 8, the hub member 20 is shown in a separated state. The hub member 20 is integrally formed by casting from austenitic stainless steel. An opening 29 is provided in the hub member for receiving the magnet 26 and the sheath 28. The paddle 40 is integrally formed with the hub member. A transverse channel 41 is formed between the paddles to support the segment and guide its movement.

[0030] Here, the operation of the wheel 10 is described with reference to an example of an electric wheelchair using the wheel 10. This example refers to an electric wheelchair described and shown in the applicant's previously filed international patent application, PCT application / Australian Patent Application Publication No. 2018 / 051065, the entire contents of which are incorporated herein by reference.

[0031] Referring to Figure 9, an electric wheelchair 50 is shown, and wheels A, B, C, and D are of the type of wheel 10 described above. Wheels A, B, C, and D are mounted on the wheelchair 50, and as a result, their wheels are aligned to face the normal forward direction during travel.

[0032] Referring to Figure 10, wheelchair 50 is steered using a differential steering configuration. The figure shows the wheelchair performing a left turn. To achieve the left turn, wheels A and C are driven with higher torque than wheels B and D. The torque applied to each wheel is represented by the length of the arrow associated with each wheel. By applying greater torque to wheels A and C, the wheelchair is driven in the direction indicated by the dotted arrow to achieve a left turn.

[0033] Referring to Figure 11, during the turn, the lateral force between the road and the wheel overcomes the bias force of the magnets 26, 36, and the segment of the wheel 30 slides laterally while in contact with the ground as it rotates away from its fixed position. In Figure 11, the segment 30 currently in contact with the ground rotates to the limit of its arc-shaped path, and the end 39 of the segment 30 abuts against the hub member 20.

[0034] As the wheel continues to rotate, the next segment makes contact with the ground. It can then slide laterally to adapt to the vehicle's turn and avoid any rubbing or skidding of the wheel across the ground. When a segment that was in contact with the ground loses contact with the ground due to the continued rotation of the wheel, the magnetic bias mechanism pulls the segment back into place (indicated by segment 30a), thus preparing the segment for continued rotation of the wheel when it touches the ground. As each segment rotates due to the wheel, it oscillates sequentially like a wave.

[0035] Figure 12 shows the corresponding wheel 10 during a right turn. The segment rotates in the opposite direction.

[0036] During some turns, the segment does not rotate throughout the entire arc-shaped path of its range of motion or movement. The degree of rotation of the segment depends on the degree of the tightness of the turn being performed, as well as the vehicle's current speed and acceleration / deceleration, and the direction and degree of any inclination of the ground on which the vehicle is traveling.

[0037] This configuration provides stability to the segment by using a "sandwich" effect that prevents the segment from accidentally flying out between the paddles. The segment is partially alternating with the paddles in the hub, partially protruding so that the hub is separated from the ground, and then sandwiched between the hub and the ground at the moment the paddle pushes the segment to generate propulsion.

[0038] Its configuration does not involve the use of axles and rollers around the periphery, as seen in omniwheels. This configuration allows the segment to transfer weight directly to the ground, thereby avoiding any type of axle and roller failure that can occur in omniwheels.

[0039] The configuration described above allows the wheels to maintain good "contact patch" with the ground while the vehicle is turning. As a result, there is less friction between the wheels and the ground compared to conventional wheels, which further reduces the risk of damage to the ground the vehicle is traveling on. Furthermore, when the vehicle is oriented laterally against an inclined slope, it cannot turn laterally by an uncontrollable distance.

[0040] Referring to Figure 13, the improved version of wheel 10' is shown in a right-hand turn. This wheel differs from wheel 10 in that pairs of magnets 26a, 26b, 36a, and 36b are provided on the hub and segment, respectively. Again, the pairs of magnets are oriented to attract each other (with their north poles facing each other's south poles), but in this embodiment, magnet 36b is oriented with the opposite polarity to magnet 36a. Therefore, for example, if magnet 36a has a north pole facing inward on the hub and magnet 26a, then magnet 36b will be oriented with its south pole facing inward. Thus, as the segment moves away from its fixed position, the attractive force between the pairs of magnets increases due to the repulsive force. At the bottom of the wheel in Figure 13, magnet 36a is attracted to magnet 26a, and magnet 36b is attracted to magnet 26b. Similarly, magnet 36b is repelled by magnet 26a, and magnet 26a increases the magnetic force that biases the segment to its fixed position.

[0041] Referring to Figure 14, another embodiment of the wheel 110 is shown. This embodiment differs from the embodiments described above, namely that the segment may include at least one region of the elastic material, and the biasing means functions by the elastic deformation of the elastic material.

[0042] The wheel 110 includes a hub member 120. This hub member differs from those described above, namely that the recesses around the hub member do not house magnets. The rigid nylon segments are replaced by segments 130, which are formed entirely from a resilient rubber material. Each segment 130 is attached to the hub 120 by an internally located clamping member 129, which is secured in place by a hexagonal head screw 128 that tightens and fixes the end of the associated segment 130 in place.

[0043] The hub 120 has a smooth outer surface and may be formed from, for example, polished stainless steel. A slippery coating such as grease or Teflon® is applied to the inner surface of each segment 130.

[0044] Referring to the lower part of the wheel 130, the lateral force between the ground and the segment 130 during turning causes elastic deformation of the segment, thereby causing the segment to slide around the hub 120 during the period when the segment is in contact with the ground. The area within the area of ​​arrow E is stretched to the side of the wheel, and the area within the area of ​​arrow F is compressed. The deformation of the segment adapts to the relative motion between the wheel and the ground, which would otherwise result in the wheel slipping.

[0045] As the wheel rotates further and the segment lifts off the ground and no longer makes contact, the compressed and stretched regions return to their original shapes, and the forces on the segment on one side of the wheel become balanced. In this way, the segment is biased to a central resting position and can move away from that position on the wheel to one side.

[0046] Otherwise, wheel 110 operates identically to wheel 10 and uses support paddles in the same manner as wheel 10. However, these are not shown in Figure 14.

[0047] Referring to Figure 15, another embodiment of the wheel 210 is shown. The wheel 210 differs from the wheel 110 in that the segment 130 is attached to the hub of the wheel via a snap-fit ​​insert member 229. The insert member 229 is positioned to snap-fit ​​around the tapered region 221 of the hub member 220. The segment 130 slides around the outer surface of the insert member 229. In Figure 15, the contour of the paddle 240, shown by a dotted line, is visible, guiding the lateral movement of the segment and supporting the segment during use, during braking and acceleration.

[0048] Referring to Figures 16 to 19, another embodiment of the wheel 310 is shown. This embodiment differs from the wheel 10 in that the magnetic means for returning the segment to its fixed position is replaced by a guide structure provided inside the cowl 320, and the cowl 320 engages with projections 322 provided on the segment 330 to return the segment to its fixed position.

[0049] As best seen in Figures 18 and 19, the cowl 320 includes an internal guide structure 326 and an external guide structure 324, which take the form of raised surface regions on the inside of the cowl. At the same time, the guide structures 326 and 324 define a recessed region 328 located between the guide structures.

[0050] As the wheel rotates, each segment 330, when in contact with the ground, is displaced to one side of its fixed position, depending on whether the vehicle is currently performing a left or right turn, and can adapt to lateral movement between the wheel and the ground. However, as the wheel continues to rotate, the spring does not immediately return to its fixed position when the segment leaves the ground. Instead, the segment is guided by the guide structures 324,326 as they rotate inside the cowl, and the guide structures 324,326 engage with projections 322 on the segment to return it to its fixed position. When the segment has rotated 180 degrees, its projection is located in region A shown in Figure 19, and at that point, the segment is returned to its fixed position.

[0051] Referring to Figures 20 to 25, another embodiment of the wheel 410 is shown including a series of segments 430 that snap into a hub 420. In this embodiment, the bias of the segment to its fixed position is provided by the segment itself, which is formed from an elastic material, causing the segment to spring back to its fixed position after it has lifted off the ground and is no longer in contact with it.

[0052] Referring to Figure 22, the segment 430 includes a molded body 431 formed from an elastic spring material such as a nylon or low-friction TPU composition. Each segment 430 further includes a ground contact area 436, which is overmolded onto the body 431 and formed from a relatively soft material such as polyurethane to provide high friction and grip to the ground.

[0053] The body 431 includes two deformable arms 438, each having a spherical end region 432, which snaps into a groove 422 provided on one side of the hub 420 to hold the segment 430 on the hub 420. Each body 431 of the segment 430 includes a molded rib 434, which serves two purposes: to add rigidity to the ground contact area of ​​the segment, and to be located in an associated transverse channel 441 formed between the paddle regions 440 of the hub, allowing it to slide from side to side within the transverse channel 441 (see Figure 23). The hub 420 is formed from a material such as nylon or acetal to provide a low-friction sliding contact surface between the outside of the hub 420 and the inside of the segment 430. Such a configuration does not require any lubricant.

[0054] As shown in the lower part of Figure 22, as the wheel 410 rotates, the outer region of the hub 420 rests on the inner surface of the ground contact region of each segment, supporting the hub 420 while lifted off the ground surface. The segment 430 is capable of sliding from side to side relative to the hub 420 when in contact with the ground, adapting to the lateral movement between the hub 420 and the ground during left or right turning. The arm 438 remains elastically deformed during the movement of the segment. As the wheel 410 continues to rotate and the segment 430 is lifted off the ground and no longer in contact, the segment springs back to its original shape and, consequently, returns to its original central position.

[0055] Referring to Figure 26, an improved version of segment 430a that can be used with wheel 410 is shown. In this version, the body 431a is improved to provide a stopping area 435 at either end of the rib 434a. The stopping area abuts against the hub, limits the degree of lateral movement of the segment, and prevents damage to the arm 438.

[0056] Although the embodiments described above are based on electric wheelchairs, the wheels according to the present invention can be used in other types of vehicles or transport vehicles such as electric scooters and electric trolleys, and in various types of mobile robots such as surveillance robots, delivery robots, toy robots, cleaning robots, and household assistance robots.

[0057] Embodiments of the present invention are suitable for use in vehicles that utilize skid steering and, consequently, rocker bogies, which may be difficult to steer.

[0058] In the embodiments described above, a wheel mounted on a drive shaft was described, but the present invention can also be applied to a so-called hub motor, in which the drive motor is integrated into the wheel.

[0059] In conjunction with the application of the present invention, the hub itself may be designed to have features that dampen vibrations and absorb shocks.

[0060] Any reference to prior art contained herein shall not be construed as common general knowledge unless otherwise indicated.

[0061] Finally, it should be acknowledged that various modifications or additions may be made to the parts described herein without departing from the spirit or scope of the present invention.

Claims

1. It is a wheel, A hub portion configured to rotate around an axis, The hub portion includes a ground contact area, The ground contact area is formed from several segments, Each of the segments is configured to normally take a fixed position and move to one side of the fixed position relative to the hub, along a path substantially lateral to the circumference of the hub, so as to move a limited distance away from the fixed position. The wheel further includes means for returning each segment to its designated position, A wheel in which the internal region of each segment is positioned away from the ground surface to support the hub and moves by sliding against the outside of the hub portion.

2. The wheel according to claim 1, wherein each segment is arranged to move by rotating around the area of ​​the hub portion.

3. The wheel according to claim 1 or 2, wherein each segment is arranged to move laterally with respect to the hub portion.

4. The wheel according to any one of claims 1 to 3, wherein the travel path of each segment is limited by the region of each segment that contacts the hub portion.

5. The wheel according to any one of claims 1 to 4, wherein the inside of each segment coincides with the outside of the hub portion.

6. The wheel according to any one of claims 1 to 5, wherein the hub portion includes a series of protrusions arranged alternately with the segments, the protrusions guide the lateral movement of the segments, and support the segments in the circumferential direction of the hub portion during braking and acceleration.

7. The wheel according to any one of claims 1 to 6, wherein the means for returning each of the segments to its designated position is in the form of a biasing means.

8. The wheel according to claim 7, wherein the biasing means is magnetic.

9. The wheel according to claim 7, wherein each segment includes at least one region of the elastic material, and the bias means functions by the elastic deformation of the elastic material.

10. The wheel according to any one of claims 1 to 9, wherein the segment snaps into the hub portion.

11. The wheel according to any one of claims 1 to 10, wherein the segment engages with a guide as a means of returning the segment to its fixed position.

12. The wheel according to claim 11, wherein the guide is provided inside a cowl that partially surrounds the wheel.

13. A transport vehicle including ground-contacting wheels, wherein at least one of the wheels is a wheel according to any one of claims 1 to 12.

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