Vehicle wheel assembly structure

Abstract

This disclosure provides a wheel assembly structure for a vehicle. The wheel assembly structure may include: a wheel on which a vehicle tire is mounted; a rotor housing connected to and rotating with the wheel; a stator housing fixed to the vehicle and configured to rotate the rotor housing by applying an electric current; a hub extending from the center of the wheel toward the inside of the vehicle; a vehicle connection portion connected to the stator housing and extending toward the inside of the vehicle; and a shock absorber mounted on the vehicle connection portion and configured to mitigate impacts between the stator housing and the wheel.

Description

[0001] Cross-citation of related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0169660, filed with the Korean Intellectual Property Office on November 25, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a wheel assembly structure for a vehicle, and more specifically, to a wheel assembly structure having an in-wheel motor and including shock absorbers for reducing vehicle load. Background Technology

[0004] An in-wheel drive system is installed on each wheel of a vehicle. This system is installed in electric vehicles (such as hybrid vehicles, fuel cell vehicles, and electric vehicles) and instead of using a large single motor, it installs a small, independent motor on each wheel to generate power to drive each wheel.

[0005] An in-wheel drive system provides an independent motor for each wheel (hereinafter referred to as an in-wheel motor), which simplifies the drive system and increases interior space compared to vehicles equipped with large drive motors. Furthermore, the in-wheel drive system directly controls the rotation of the wheels, thus eliminating the need for complex power transmission devices such as differentials.

[0006] High efficiency and high performance are achieved by eliminating powertrain components. Specifically, by mounting in-wheel motors (e.g., directly) on each wheel, power waste is reduced and sufficient driving force is ensured. Fuel efficiency is improved by maximizing the power allocated to each in-wheel motor during driving and recovering braking energy generated by regenerative braking during braking.

[0007] However, in in-wheel drive systems, the in-wheel motor is integrated with the wheel, which can increase the vehicle's unsprung mass and vibration and noise (NVH), and there is a risk of damage to the in-wheel motor due to impacts to the underside of the vehicle. Furthermore, designing the wheel assembly structure can be challenging to ensure the durability of the in-wheel motor and the durability of the high-voltage cables moving during wheel rotation.

[0008] An in-wheel drive system incorporates a shock absorber between the wheel and the stator housing to mitigate impacts between the stator housing and the wheel. Shock absorber brackets (e.g., steering knuckles) are used to hold the shock absorber attached to the vehicle's wheel hub. If the shock absorber cannot maintain sufficient strength to withstand forward, rearward, left-right loads transmitted through the vehicle's tires, wheels, hubs, and steering knuckles, the load-bearing components may be damaged. Summary of the Invention

[0009] This disclosure provides a wheel assembly structure for a vehicle that, by employing a shock absorber structure consisting of a large tube and a double-layer cylinder, can reduce the impact transmitted from the lower body of the vehicle to the in-wheel motor and improve the strength and durability against lateral forces.

[0010] This disclosure provides a wheel assembly structure for a vehicle. The wheel assembly structure may include: a wheel on which a vehicle tire is mounted; a rotor housing connected to and rotating with the wheel; a stator housing fixed to the vehicle and configured to rotate by applying an electric current; a hub extending from the center of the wheel toward the inside of the vehicle; a vehicle connection portion connected to the stator housing and extending toward the inside of the vehicle; and a shock absorber mounted on the vehicle connection portion to mitigate impact between the stator housing and the wheel.

[0011] A permanent magnet can be provided on the inner surface of the rotor housing facing the axis of rotation of the rotor housing, and a coil can be provided on the outer surface of the stator housing facing the permanent magnet, so that the rotor housing can be operated to rotate by the electromagnetic force generated by applying electricity to the coil.

[0012] The shock absorber is surrounded by a spring that is designed to support the upper surface of the vehicle connection, support the vehicle load and stator housing, and reduce impact.

[0013] The shock absorber can be connected to the wheel hub via a wheel hub connecting member, and the wheel hub and the wheel hub connecting member can be rotatably connected via a wheel hub bearing.

[0014] The hub connecting component can be fixedly connected to the outer periphery of the center part of the cylinder block.

[0015] The vehicle connection can be attached to the stator housing in a shape that surrounds the shock absorber.

[0016] The shock absorber may include: a tube, a first end of which is connected to the upper part of the vehicle connection, and a second end of which extends toward the lower part of the vehicle connection; a piston disposed on the outer periphery of the second end of the tube; a cylinder having an open first end and a closed and sealed second end, and configured to reciprocate along the vertical direction of the vehicle connection while the outer periphery of the piston contacts the inner surface of the cylinder; and a cylinder cover configured to close and seal the first end of the cylinder.

[0017] The second end of the tube can pass through the second end of the cylinder to connect to the lower part of the vehicle connection.

[0018] A buffer stop is provided between the lower surface of the upper part of the vehicle connection and the first end of the cylinder. The buffer stop contacts the vehicle connection and is installed around the tube so that it deforms when it contacts the first end of the cylinder, thereby being compressed.

[0019] A first outer cylinder body may be provided between the buffer stop and the first end of the cylinder body, the first outer cylinder body being through which a tube passes and configured to surround the outside of the first end of the cylinder body.

[0020] A first sliding member may be provided between the outer side of the first end of the cylinder and the inner side of the first outer cylinder. The first sliding member is configured to allow the cylinder to slide on the inner side of the first outer cylinder.

[0021] A second outer cylinder may be provided between the second end of the cylinder and the lower part of the vehicle connection, the second outer cylinder surrounding the outer side of the second end of the cylinder.

[0022] A second sliding member may be provided between the outer side of the second end of the cylinder and the inner side of the second outer cylinder, which allows the cylinder to slide on the inner side of the second outer cylinder.

[0023] The hub connecting component can be positioned between the first outer cylinder block and the second outer cylinder block.

[0024] According to an exemplary embodiment, in a wheel assembly structure equipped with an in-wheel motor including a stator and a rotor, by employing a shock absorber structure consisting of a large tube and a double-layer cylinder, the impact transmitted from the vehicle's underbody to the in-wheel motor can be reduced, thereby improving the durability of the high-voltage cable connected to the in-wheel motor.

[0025] In addition, by increasing the strength of the shock absorber itself, the strength and durability of the shock absorber in resisting lateral forces applied to the vehicle can be improved.

[0026] Furthermore, by placing the buffer stop on the outside of the double-layer cylinder block, the design freedom of the buffer stop can be increased. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view showing the wheel assembly structure of a vehicle according to an embodiment, as viewed from the front of the vehicle.

[0028] Figure 2 This is a cross-sectional view showing an example of a shock absorber in a vehicle wheel assembly structure according to an embodiment.

[0029] Figure 3 This is a cross-sectional view showing another example of a shock absorber in a vehicle wheel assembly structure according to an embodiment.

[0030] Figure 4A , Figure 4B and Figure 4C It shows according to Figure 3 A cross-sectional view of the operation process of another example of the shock absorber of the vehicle wheel assembly structure shown in the embodiment. Detailed Implementation

[0031] In the following description, this disclosure will be given more fully with reference to the accompanying drawings, in which embodiments of the disclosure are illustrated. Various modifications may be made to the described embodiments without departing from the spirit or scope of this disclosure.

[0032] In the various exemplary embodiments, the same reference numerals are used for elements having the same configuration and can be described representatively in the first exemplary embodiment, while in other exemplary embodiments, elements different from those in the first exemplary embodiment can be described.

[0033] The accompanying drawings are schematic and not to scale. For clarity, the relative dimensions and ratios of some parts in the drawings are shown as enlarged or reduced in size, and the dimensions are exemplary and not limiting. Furthermore, similar structures, elements, or components shown in two or more drawings may use the same reference numerals to denote similar features. When an element such as a layer, film, region, or substrate is referred to as being "on" another element, it may be (e.g., directly) on the other element, or there may be an intermediate element present.

[0034] Various modifications to the accompanying drawings are expected. Therefore, the embodiments described herein are not limited to the shape of the illustrated components (e.g., regions), but may include, for example, changes in shape during manufacturing.

[0035] In the following, a wheel assembly structure of a vehicle according to an exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0036] Figure 1 This is a cross-sectional view showing the wheel assembly structure of a vehicle according to an embodiment, as viewed from the front of the vehicle.

[0037] A wheel assembly structure for a vehicle according to an exemplary embodiment may include: a wheel 20 on which a tire 10 of the vehicle is mounted; a rotor housing 40 connected to the wheel 20 and configured to rotate with the wheel 20; and a stator housing 30 fixed to the vehicle and configured to rotate the rotor housing 40 by applying an electric current.

[0038] The stator housing 30 and rotor housing 40 can be disposed inside the rotor 43 to form an in-wheel motor. The in-wheel motors 31 and 41 can be electric vehicle drive systems that drive the wheels by (e.g., directly) mounting the motors on each wheel. Unlike drive methods using internal combustion engines and transmissions, this allows for efficient energy transfer because the wheels and motors are directly connected.

[0039] Wheel 20 may (e.g., primarily) be made of metal and rotate about a central axis. Wheel 20 serves to support tire 10, reduce impacts received from the road, and support the weight of the vehicle.

[0040] Tire 10 surrounds the outside of wheel 20 and is (e.g., primarily) made of rubber and steel wire. Tire 10 controls the direction and speed of the vehicle by utilizing friction with the road surface. Tire 10 absorbs impacts from the road surface to provide a comfortable driving environment and improve vehicle safety.

[0041] Rotor 43 can be connected to the interior of wheel 20 and can rotate with wheel 20. Rotor 43 (e.g., a portion) can be configured to rotate when receiving electricity from in-wheel motors 31 and 41. Rotor 43 can be used to transmit engine torque to the wheel. The rotation of rotor 43 primarily converts power into mechanical energy.

[0042] The stator 29 can be fixed to the vehicle and can rotate the rotor 43 by applying an electric current. The stator 29 is the fixed part of the in-wheel motors 31 and 41 and (e.g., primarily) can be made of coils 35 or magnets 42. When electrical energy passes through the stator 29, a magnetic field can be generated, which can cause the rotor 43 to rotate.

[0043] A bearing may be provided between the rotor 43 and the stator 29. The bearing allows the shaft to move between the rotor 43 and the stator 29 and supports the smooth rotation of the internal components.

[0044] A damping device 70 can be inserted between the upper surface of the rotor housing 40 and the lower surface of the wheel 20. The damping device 70 can be made of an elastic polymer material. Alternatively, the damping device 70 can be an air spring. Due to the damping device 70, the wheel 20 and the in-wheel motors 31 and 41 can move vertically relative to each other, which can protect the in-wheel motors 31 and 41 from impacts from below and can reduce vibration.

[0045] Furthermore, the damping device 70 can be disposed on the outer side of the in-wheel motors 31 and 41, that is, on the outer periphery of the stator housing 30. Additionally, the damping device 70 can be disposed on the circumference of the central axis of the rotor housing 40.

[0046] Additionally, for example, the wheel assembly structure of a vehicle according to an exemplary embodiment can be applied to a custom-built vehicle (PBV). This wheel assembly structure can be modularized and applied to the lower body of the PBV body (e.g., a skateboard chassis).

[0047] Meanwhile, the wheel assembly structure of the vehicle according to the exemplary embodiment may include: a wheel hub 25 extending from the center of the wheel 20 toward the inside of the vehicle; a vehicle connection portion or vehicle connector 33 connected to the stator housing 30 and extending toward the inside of the vehicle; and a shock absorber 62 mounted on the vehicle connection portion 33 and configured to reduce the impact between the stator housing 30 and the wheel 20.

[0048] The wheel hub 25 can protrude from the center portion of the wheel 20 toward the inside of the vehicle, and a wheel hub connecting member or wheel hub connector 80 can be engaged (e.g., configured) to the protrusion. A first end of the wheel hub connecting member 80 can (e.g., connected) to the protrusion surrounding the wheel hub 25 and can (e.g., connected) to (e.g., relatively) rotate via a wheel hub bearing 27. A second end of the wheel hub connecting member 80 can be connected to a shock absorber 62.

[0049] The vehicle connection portion 33 can be connected to the inside of the stator housing 30 and can protrude toward the inside of the vehicle. Furthermore, the shock absorber 62 can be mounted in the vehicle connection portion 33. The vehicle connection portion 33 can (e.g., in shape) be connected to the stator housing 30 in a manner surrounding the shock absorber 62.

[0050] The shock absorber 62 can be installed inside the vehicle connection part 33 and can be connected to the wheel hub connection member 80. A spring 64 can be provided around the shock absorber 62. The spring is configured to support the upper surface of the vehicle connection part 33, support the load of the vehicle and the stator housing 30, and reduce impact.

[0051] Shock absorber 62 is an example of a suspension and can be installed inside the vehicle connection 33 to absorb impacts from the road surface, thereby improving ride comfort and reducing damage to the vehicle.

[0052] The upper end of the shock absorber 62 can be supported on the upper vehicle connection portion 33 by a buffer stop 66. The buffer stop 66 can prevent the shock absorber 62 from (e.g., directly) contacting and colliding with the vehicle connection portion 33. The buffer stop 66 can be made of an elastic polymer material.

[0053] Figure 2 This is a cross-sectional view showing an example of a shock absorber in a vehicle wheel assembly structure according to an embodiment.

[0054] refer to Figure 2 The shock absorber 100 can be composed of a tube 110, a piston 120, a cylinder 130, and a cylinder cover 135. In this embodiment, as shown in the figure, the spring installed around the shock absorber 100 can be omitted.

[0055] The first end of the tube 110 can be fixed to the upper part of the vehicle connection 33, and the second end of the tube can extend toward the lower part of the vehicle connection 33. A buffer stop 166, which is mounted around the tube 110 and deforms to be compressed when in contact with the first end of the cylinder block 130, can be provided on the lower surface of the upper part of the vehicle connection 33 and the outer periphery of the first end of the tube 110.

[0056] The piston 120 may be disposed on the outer periphery of the second end of the tube 110 and may (e.g., in close contact) with the inner wall of the cylinder 130.

[0057] The cylinder body 130 may have a first end (e.g., open) and a second end (e.g., closed and sealed). When the outer periphery of the piston 120 contacts the inner surface of the cylinder body 130, the cylinder body 130 may reciprocate in the vertical direction of the vehicle connection portion 33. That is, when the tube 110 and the piston 120 are fixed, the cylinder body 130 may move along the vertical direction of the vehicle connection portion 33 while in contact with the outer periphery of the piston 120.

[0058] The second end of the tube 110 can extend into the cylinder 130 by passing through the piston 120. Furthermore, the second end of the tube 110 can pass through the second end of the cylinder 130 to connect to the lower part of the vehicle connection portion 33. The second end of the cylinder 130 (through which the second end of the tube 110 passes) can be slidably moved along the length of the tube 110, while simultaneously closing and sealing the interior of the cylinder 130.

[0059] The cylinder cover 135 can be configured to close and seal the opening at the first end of the cylinder 130. A tube 110 can pass through the center of the cylinder cover 135, and the center of the cylinder cover 135 (the position through which the tube 110 passes) can slide along the length of the tube 110.

[0060] The shock absorber 100 can be connected to the hub 25 via a hub connecting member 80. The hub connecting member 80 can be (e.g., fixedly) connected to the lower outer periphery of the shock absorber 100. The hub 25 and the hub connecting member 80 can be rotatably connected via a hub bearing 27. Therefore, even if the hub 25 rotates, the hub connecting member 80 and the shock absorber 100 will not rotate.

[0061] Figure 3 This is a cross-sectional view showing another example of a shock absorber in a vehicle wheel assembly structure according to an embodiment.

[0062] refer to Figure 3 A first outer cylinder body 140 may be provided between the first end of the cylinder body 130 and the buffer stop 166 of the shock absorber 200. The first outer cylinder body 140 may surround the outside of the first end of the cylinder body 130, and the tube 110 may pass through the center of the upper surface.

[0063] Furthermore, the first sliding member 145 is configured such that the cylinder body 130 can contact (e.g., tightly) the inner side of the first outer cylinder body 140 and slide slidably. The first sliding member 145 may be disposed between the outer side of the first end of the cylinder body 130 and the inner side of the first outer cylinder body 140. The first sliding member 145 may be disposed on the outer periphery of the first end of the cylinder body 130 or on the inner periphery of the first outer cylinder body 140, and multiple first sliding members 145 may be provided.

[0064] A second outer cylinder 150 may be provided between the second end of the cylinder 130 and the lower part of the vehicle connection portion 33, the second outer cylinder 150 surrounding the outer side of the second end of the cylinder 130. The second outer cylinder 150 may contact the lower part of the vehicle connection portion 33 and be supported by the lower part of the vehicle connection portion.

[0065] Furthermore, a second sliding member 155 may be provided between the outer side of the second end of the cylinder body 130 and the inner side of the second outer cylinder body 150, configured to allow the cylinder body 130 to slide slidably on the inner side of the second outer cylinder body 150. The second sliding member 155 may be provided on the outer periphery of the second end of the cylinder body 130 or on the inner periphery of the second outer cylinder body 150, and multiple second sliding members 155 may be provided.

[0066] Meanwhile, the hub connecting member 180 can be (e.g., fixedly) connected to the outer periphery of the cylinder block 130 between the first outer cylinder block 140 and the second outer cylinder block 150. The hub 25 and the hub connecting member 180 can be rotatably connected via the hub bearing 27. Therefore, even if the hub 25 rotates, the hub connecting member 180 and the cylinder block 130 can remain stationary.

[0067] The first and second ends of the cylinder 130 can be positioned such that the outer side of the first end of the cylinder 130 is surrounded by the first outer cylinder 140 and the outer side of the second end of the cylinder 130 is surrounded by the second outer cylinder 150, such that the vertical movement range of the cylinder 130, the hub 25 and the hub connecting member 180 can be limited by the first outer cylinder 140 and the second outer cylinder 150 (e.g., the interval between the first outer cylinder 140 and the second outer cylinder 150).

[0068] Meanwhile, the second outer cylinder 150 can (e.g., in one state) be fixed to the lower inner surface of the vehicle connection 33, and when the piston 120 moves upward and (e.g., by contact) pushes the upper inner surface of the first outer cylinder 140 upward, the first outer cylinder 140 can (e.g., rise to) compress the buffer stop 166.

[0069] Figure 4A , Figure 4B and Figure 4C It shows according to Figure 3A cross-sectional view of the operation process of another example of the shock absorber of the vehicle wheel assembly structure shown in the embodiment.

[0070] refer to Figure 4A , Figure 4B and Figure 4C With the shock absorber 200's buffer stop 166 uncompressed, the bottom of the second end of the cylinder block 130 can contact the inner bottom surface of the second outer cylinder 150. Furthermore, the hub connecting member 180 is positioned near the second outer cylinder block 150, and the piston 120 is positioned near the first end of the cylinder block 130 (in...). Figure 4A (As shown in the image).

[0071] When an impact is applied to a vehicle from the road surface, while the tube 110 and piston 120 are fixed, the cylinder 130 and the first outer cylinder 140 move upward due to inertia (e.g., torque). The bottom of the second end of the cylinder 130 can be separated from the inner bottom surface of the second outer cylinder 150, and the first end of the cylinder 130 can contact the upper inner surface of the first outer cylinder 140. The second end and the first end of the cylinder 130 can be slidably moved toward the upper part of the second outer cylinder 150 and the upper part of the first outer cylinder 140, respectively, via the second sliding member 155 and the first sliding member 145. At this time, the buffer stop 166 located between the lower surface of the vehicle connection portion 33 and the upper outer surface of the first outer cylinder 140 begins to be compressed. Figure 4B (as shown in the image).

[0072] The upward movement range of the cylinder block 130 and the hub connecting member 180 can be limited by the arrangement of the first outer cylinder block 140. When the cylinder block 130 moves upward (e.g., to its maximum extent), the buffer stop 166 can be compressed (e.g., fully or to its maximum extent). At this time, the length of the second outer cylinder 150 can be formed to have a length such that the second end of the cylinder block 130 does not separate from the second outer cylinder block 150. Figure 4C (as shown in the image).

[0073] When an impact is applied to a vehicle from the road surface, such as Figure 4A , Figure 4B and Figure 4C As shown, the cylinder block 130 can reciprocate between the first outer cylinder block 140 and the second outer cylinder block 150, and the cylinder block 130 can move upward while contacting the upper inner surface of the first outer cylinder block 140, so that the buffer stop 166 can be compressed and decompressed through the reciprocating movement. Through this process, the impact on the lower body of the vehicle can be reduced, and by adopting a double-layer cylinder block structure of cylinder block 130, first outer cylinder block 140 and second outer cylinder block 150, the impact along the lateral direction of the vehicle can also be reduced.

[0074] Therefore, according to an exemplary embodiment, in a wheel assembly structure provided with an in-wheel motor including a stator and a rotor, by employing a shock absorber structure consisting of a large tube and a double-layer cylinder, the impact transmitted from the underbody of the vehicle to the in-wheel motor can be reduced, thereby improving the durability of the high-voltage cable connected to the in-wheel motor.

[0075] In addition, by increasing the strength of the shock absorber itself, the strength and durability of the shock absorber in resisting lateral forces applied to the vehicle can be improved.

[0076] Furthermore, by placing the buffer stop on the outside of the double-layer cylinder block, the design freedom of the buffer stop can be increased.

[0077] Although this disclosure has been described in conjunction with exemplary embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. Rather, this disclosure is intended to cover various modifications and (e.g., substantially) equivalent arrangements.

Claims

1. A wheel assembly structure for a vehicle, comprising: Wheels, on which the vehicle's tires are mounted; A rotor housing connected to the wheel, the rotor housing being configured to rotate together with the wheel; A stator housing, connected to the vehicle, the stator housing being configured to rotate the rotor housing by applying an electric current; as well as The wheel hub extends from the center of the wheel toward the inside of the vehicle; A vehicle connection portion is attached to the stator housing and extends toward the inside of the vehicle; as well as A shock absorber is mounted on the vehicle connection and is configured to reduce the impact between the stator housing and the wheel.

2. The wheel assembly structure according to claim 1, wherein, A permanent magnet facing the rotation axis of the rotor housing is provided on the inner surface of the rotor housing.

3. The wheel assembly structure according to claim 2, wherein, A coil is disposed on the outer surface of the stator housing at a position facing the permanent magnet.

4. The wheel assembly structure according to claim 3, wherein, The rotor housing rotates by electromagnetic force generated by applying electricity to the coil.

5. The wheel assembly structure according to claim 1, wherein, A spring is configured to support the upper surface of the vehicle connection, support the load of the vehicle and the stator housing, and reduce impact.

6. The wheel assembly structure according to claim 5, wherein, The spring is disposed around the periphery of the shock absorber.

7. The wheel assembly structure according to claim 1, wherein: The shock absorber is connected to the wheel hub via a hub connection component.

8. The wheel assembly structure according to claim 7, wherein, The hub and the hub connecting member are rotatably connected by a hub bearing.

9. The wheel assembly structure according to claim 7, wherein, The hub connecting component is connected to the lower outer periphery of the shock absorber.

10. The wheel assembly structure according to claim 1, wherein, The vehicle connection is attached to the stator housing in the form of surrounding the shock absorber.

11. The wheel assembly structure according to claim 10, wherein, The shock absorber includes: The tube has a first end connected to the upper part of the vehicle connection portion, and a second end extending toward the lower part of the vehicle connection portion; A piston is disposed on the outer periphery of the second end of the tube; A cylinder body having an open first end and a closed and sealed second end, wherein the cylinder body is configured to reciprocate along the vertical direction of the vehicle connection while the outer periphery of the piston contacts the inner surface of the cylinder body; and The cylinder cover is configured to close and seal the first end of the cylinder.

12. The wheel assembly structure according to claim 11, wherein, The second end of the tube passes through the second end of the cylinder to connect to the lower part of the vehicle connection.

13. The wheel assembly structure according to claim 11, wherein, A buffer stop contacts the vehicle connection and is installed around the tube.

14. The wheel assembly structure according to claim 13, wherein, The buffer stop is disposed between the lower surface of the upper part of the vehicle connection and the first end of the cylinder.

15. The wheel assembly structure according to claim 14, wherein, The buffer stop is configured to be compressed when it contacts the first end of the cylinder.

16. The wheel assembly structure according to claim 13, wherein, A first outer cylinder is provided between the buffer stop and the first end of the cylinder body, the first outer cylinder being passed through the tube and configured to surround the outside of the first end of the cylinder body.

17. The wheel assembly structure according to claim 16, wherein, A first sliding member is provided between the outer side of the first end of the cylinder and the inner side of the first outer cylinder. The first sliding member is configured to allow the cylinder to slide on the inner side of the first outer cylinder.

18. The wheel assembly structure according to claim 17, wherein, A second outer cylinder is provided between the second end of the cylinder and the lower part of the vehicle connection portion, and the second outer cylinder surrounds the outer side of the second end of the cylinder.

19. The wheel assembly structure according to claim 18, wherein, A second sliding member is provided between the outer side of the second end of the cylinder and the inner side of the second outer cylinder. The second sliding member is configured to allow the cylinder to slide on the inner side of the second outer cylinder.

20. The wheel assembly structure according to claim 18, wherein, The shock absorber is connected to the wheel hub via a wheel hub connecting member, and the wheel hub connecting member is disposed between the first outer cylinder and the second outer cylinder.

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