IN-WHEELSUSPENSION

FIELD OF THE INVENTION

[0001] The invention relates to an in-wheel suspension where main portions of suspension components are arranged in a wheel.

BACKGROUND OF THE INVENTION

[0002] Such an in-wheel suspension is described, for example, in Japanese Patent Application Publication No. JP-A- 10-338009. The in-wheel suspension described in this publication includes a hub that supports a wheel. The wheel mainly includes a disc and a rim. The rim has a reference width and a reference diameter. The in-wheel suspension includes a wheel carrier that defines the rotational axis of the hub, and a guide member that guides the movement of the wheel carrier with respect to a support member in the axial direction. The support member includes fitting means for fitting the support member to a chassis of a vehicle. The wheel carrier is fitted to the guide member by a long-and-thin single bar, and slides according to the guidance by the guide member. The wheel carrier is prevented from rotating on the sliding axis. The wheel carrier is fitted to the both ends of the bar. The in-wheel suspension includes means for supporting a load of the vehicle transmitted to the wheel carrier by the support member. The wheel carrier, the bar, and the guide member are housed in the wheel along the diameter defined by the reference diameter. The wheel carrier, the bar, and the guide member are housed in a limited space having a shape of a cylinder where one of the surfaces of the cylinder, which extend in the axial direction of the wheel carrier, bar, and the guide member, is defined by the disc of the wheel and the other surface is defined by a virtual surface contacting the rim.

[0003] In an in-wheel suspension where a sliding mechanism is used, a spring element and an attenuation element need to be operated in accordance with sliding of the sliding mechanism. Therefore, the spring element and the attenuation element need to

be positioned near the sliding mechanism, as described above. This reduces flexibility in arrangement of the sliding mechanism and the spring element/attenuation element in a limited space in the wheel. It is, therefore, difficult to efficiently arrange the components in the limited space in the wheel.

DISCLOSURE OF THE INVENTION

[0004] An object of the invention is to provide an in-wheel suspension where a sliding mechanism and a spring element/attenuation element can be arranged with greater flexibility. [0005] A first aspect of the invention relates to an in-wheel suspension including two sliding shaft members that are fixed to a carrier which rotatably supports a tire/wheel assembly, and that are arranged in a wheel so as to extend in the vertical/substantially vertical direction; two sliding members that slide with respect to the respective sliding shaft members; a coupling member that couples at least one of the sliding members with a vehicle body; a link device that enables the two sliding members to slide in accordance with each other; and a spring element and an attenuation element that operate in accordance with sliding of the sliding members.

[0006] One of the two sliding shaft members may be arranged on the front side of a wheel center. The other of the two sliding shaft member may be arranged on the rear side of the wheel center.

[0007] The spring element may be arranged between one of the two sliding members and the sliding shaft member corresponding to the one of the two sliding members.

[0008] In the in-wheel suspension according to the first aspect, each of the two sliding shaft members may constitute a piston rod, and each of the two sliding members may constitute a hydraulic cylinder which has a hydraulic chamber filled with fluid. The hydraulic chamber is partitioned into an upper hydraulic chamber and a lower hydraulic chamber by a piston portion of the sliding shaft member. Also, the link device may include a first link passage and a second link passage. The first link passage connects the upper hydraulic chamber of one of the sliding members to the lower

hydraulic chamber of the other sliding member. The second link passage connects the lower hydraulic chamber of the one of the sliding members to the upper hydraulic chamber of the other sliding member.

[0009] The attenuation element may be a fluid resistance element that is arranged at at least one of the first link passage and the second link passage.

[0010] The spring element may be arranged between one of the two sliding members and the sliding shaft member corresponding to the one of the two sliding members. Also, a pressure receiving area of the hydraulic cylinder to which the spring element is provided may be greater than a pressure receiving area of the other hydraulic cylinder. [0011] The two hydraulic cylinders may have different pressure receiving areas.

One of the two sliding members may be coupled with the vehicle body by the coupling member. A second coupling member that pivotably couples the other sliding member with the vehicle body may be provided.

[0012] The link device may include a belt that connects the two sliding members to each other; and multiple pulleys over which the belt is looped, and which enable the two sliding members to slide in phase using the belt.

[0013] The attenuation element may be a device that is provided at at least one of the multiple pulleys and that attenuates a rotary input.

[0014] The invention provides the in-wheel suspension where the sliding mechanism and the spring element/attenuation element can be arranged with greater flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The foregoing and further objects, features and advantages of the invention will become apparent from the following description of an example embodiment with reference to the accompanying drawings, wherein the same or corresponding portions are denoted by the same reference numerals and wherein:

FIG. 1 illustrates the view of a tire/wheel assembly when viewed from the inside of a vehicle, showing the structure of a main portion of an in-wheel suspension according to an embodiment of the invention;

FIG. 2 illustrates the cross-sectional view taken along line I-I in FIG. 1; FIG. 3 illustrates the schematic view of main components of the in-wheel suspension when viewed from the top of the vehicle; and

FIG. 4 illustrates the schematic view of a link device according to a modified example of the embodiment.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENT [0016] Hereafter, an example embodiment of the invention will be described in detail with reference to accompanying drawings. [0017] FIG. 1 illustrates the structure of a main portion of an in-wheel suspension according to the embodiment of the invention. FIG. 1 is the view of a tire/wheel assembly when viewed from the inside of a vehicle. The left side of FIG. 1 is the front of the vehicle. In FIG. 1, some components (a hydraulic cylinder, a piston rod, etc.) are shown in section for convenience of explanation. In the description below, the in-wheel suspension according to the embodiment is applied to a rear wheel. However, the in-wheel suspension according to the embodiment may be applied to a front wheel.

[0018] A tire/wheel assembly 10 includes a tire 12 and a wheel 14. As described below in detail, main portions of suspension components are arranged in a space defined by the inner peripheral surface of the rim of the wheel 14. The term "in the wheel" corresponds to the term "in the substantially cylindrical space defined by the inner peripheral surface of the rim of the wheel 14". However, the description that a component is arranged in the wheel does not always mean that the entirety of the component is arranged in the wheel. The description includes the structure where the component partially protrudes from the wheel. [0019] A carrier 70 is arranged in the wheel. The carrier 70 rotatably supports the tire/wheel assembly 10 via an axle bearing 70a. A drive shaft (not shown) may be coupled with the axle bearing 70a at a position on the tire/wheel assembly 10 side.

[0020] The carrier 70 according to the embodiment has two arm portions (carrier arms) 72a, 72b, one of which extends upward from a position near the wheel center

toward the rear of the vehicle, and the other of which extends downward from a position near the wheel center toward the rear of the vehicle. In addition, the carrier 70 has two arm portions (carrier arms) 74a, 74b, one of which extends upward from a position near the wheel center toward the front of the vehicle, and the other of which extends downward from a position near the wheel center toward the front of the vehicle.

[0021] The upper end and the lower end of a first piston rod 40 are fixed to the ends of the two arm portions 74a, 74b that extend toward the front of the vehicle, respectively. Namely, the first piston rod 40 is arranged on the front side of the wheel center. The first piston rod 40 is arranged in the vertical/substantially vertical direction in the wheel. [0022] The upper end and the lower end of a second piston rod 42 are fixed to the ends of the two arm portions 72a, 72b that extend toward the rear of the vehicle, respectively. Namely, the second piston rod 42 is arranged on the rear side of the wheel center. The second piston rod 42 is arranged in the vertical/substantially vertical direction in the wheel. [0023] A brake caliper 20 is fixed to the carrier 70 at the junction of the two arm portions 72a, 72b. The brake caliper 20 is arranged on the rear side of the second piston rod 42. The brake caliper 20 and a brake rotor 22, which is arranged outboard of the carrier 70, constitute a brake device for restricting rotation of the tire/wheel assembly 10.

[0024] The first piston rod 40 is provided with a first hydraulic cylinder 50. The first hydraulic cylinder 50 has a hydraulic chamber filled with fluid (e.g. oil). The hydraulic chamber has a circular cross section that is constant in the axial direction of the first piston rod 40. The hydraulic chamber is partitioned into an upper portion and a lower portion by a piston portion 40a of the first piston rod 40. Namely, the first hydraulic cylinder 50 has an upper hydraulic chamber 50a and a lower hydraulic chamber 50b that are separated by the piston portion 40a. The piston portion 40a does not have a valve, an orifice, or the like. The fluid flow between the upper hydraulic chamber 50a and the lower hydraulic chamber 50b is prevented substantially completely by the piston portion 40a. The first piston rod 40 may be connected to the first hydraulic cylinder 50 so as to be slidable in the axial direction (vertical/substantially vertical direction) with

respect to the first hydraulic cylinder 50 and rotatable on its axis with liquid-tightness maintained by a seal, a bearing or the like, as in the case of a piston rod of a commonly used shock absorber.

[0025] Two fluid passages 40c, 4Od are formed in the first piston rod 40. FIG. 2 illustrates the cross-sectional view taken along line I-I in FIG. 1. The first piston rod 40 is a rod-like member having a circular cross section that is constant in the axial direction. At least the portion of the first piston rod 40, which slides with respect to the first hydraulic cylinder 50, has the constant cross section. The fluid passages 40c, 4Od are formed in the first piston rod 40. The upper fluid passage 40c has an opening portion near the upper end of the first piston rod 40. The upper fluid passage 40c extends in the axial direction from the upper portion of the first piston rod 40 to a position near the piston portion 40a. The upper fluid passage 40c opens into the upper hydraulic chamber 50a. Similarly, the lower fluid passage 4Od has an opening portion near the lower end of the first piston rod 40. The lower fluid passage 4Od extends in the axial direction from the lower portion of the first piston rod 40 to a position near the piston portion 40a. The lower fluid passage 4Od opens into the lower hydraulic chamber 50b.

[0026] Similarly, the second piston rod 42 is provided with a second hydraulic cylinder 52. The second hydraulic cylinder 52 has a hydraulic chamber filled with fluid. The hydraulic chamber has a circular cross section that is constant in the axial direction of the second piston rod 42. The hydraulic chamber is partitioned into an upper portion and a lower portion by a piston portion 42a of the second piston rod 42. Namely, the second hydraulic cylinder 52 has an upper hydraulic chamber 52a and a lower hydraulic chamber 52b that are separated by the piston portion 42a. The piston portion 42a does not have a valve, an orifice, or the like. The fluid flow between the upper hydraulic chamber 52a and the lower hydraulic chamber 52b is prevented substantially completely by the piston portion 42a. The second piston rod 42 may be connected to the second hydraulic cylinder 52 so as to be slidable in the axial direction (vertical/substantially vertical direction) with respect to the second hydraulic cylinder 52 and rotatable on its axis with liquid-tightness maintained by a seal, a bearing or the like, as in the case of a

piston rod of a commonly used shock absorber.

[0027] Two fluid passages 42c, 42d are formed in the second piston rod 42. The second piston rod 42 is a rod-like member having a circular cross section that is constant in the axial direction. At least the portion of the second piston rod 42, which slides with respect to the second hydraulic cylinder 52, has the constant cross section. The fluid passages 42c, 42d are formed in the second piston rod 42. The upper fluid passage 42c has an opening portion near the upper end of the second piston rod 42. The upper fluid passage 42c extends in the axial direction from the upper portion of the second piston rod 42 to a position near the piston portion 42a. The upper fluid passage 42c opens into the upper hydraulic chamber 52a. Similarly, the lower fluid passage 42d has an opening portion near the lower end of the second piston rod 42. The lower fluid passage 42d extends in the axial direction from the lower portion of the second piston rod 42 to a position near the piston portion 42a. The lower fluid passage 42d opens into the lower hydraulic chamber 52b. [0028] The upper fluid passage 40c, a first link passage 60, and the lower fluid passage 42d connect the upper hydraulic chamber 50a of the first hydraulic cylinder 50 to the lower hydraulic chamber 52b of the second hydraulic cylinder 52. The first link passage 60 is formed of a pipe. The first link passage 60 is connected to the opening portion of the fluid passage 40c, which is positioned near the upper end of the first piston rod 40. The first link passage 60 is also connected to the opening portion of the fluid passage 42d, which is positioned near the lower end of the second piston rod 42.

[0029] Similarly, the lower fluid passage 4Od, a second link passage 62, and the upper fluid passage 42c connect the lower hydraulic chamber 50b of the first hydraulic cylinder 50 to the upper hydraulic chamber 52a of the second hydraulic cylinder 52. The second link passage 62 is formed of a pipe. The second link passage 62 is connected to the opening portion of the fluid passage 4Od, which is positioned near the lower end of the first piston rod 40. The second link passage 62 is also connected to the opening portion of the fluid passage 42c, which is positioned near the upper end of the second piston rod 42.

[0030] FIG. 3 illustrates the schematic view of main components of the in-wheel suspension when viewed from the top of the vehicle. As schematically shown in FIG. 3, the second hydraulic cylinder 52 is coupled with a vehicle body (for example, a suspension member) via an arm 90. The arm 90 extends from the vehicle body into the wheel, and is coupled with the second hydraulic cylinder 52 in the wheel. High strength/rigidity is provided to a portion at which the second hydraulic cylinder 52 and the arm 90 are coupled with each other (and the second hydraulic cylinder itself) by, for example, a stiffener. The arm 90 is strongly coupled with the vehicle body. However, as schematically shown in FIG. 3, the arm 90 may be coupled with the vehicle body via, for example, a bushing, as long as the second hydraulic cylinder 52 can rotate on the second piston rod 42 as necessary.

[0031] A certain degree of freedom in the vertical/substantially vertical movement of the first hydraulic cylinder 50 with respect to the carrier 70 is restrained by a link. In this case, the first hydraulic cylinder 50 may be coupled with the carrier 70 via the link. Alternatively, as schematically shown in FIG. 3, the first hydraulic cylinder 50 may be coupled with the vehicle body via a link 92. In this case, the link 92 may be pivotably coupled with the carrier 70 and/or the vehicle body and the first hydraulic cylinder 50 via a ball joint or a bushing (pin connection).

[0032] When the link 92 is coupled with the vehicle body, the link 92 extends from the vehicle body into the wheel, and is coupled with the first hydraulic cylinder 50 in the wheel. With this structure, rotation of the second hydraulic cylinder 52 on the second piston rod 42 is restrained by the link 92. Accordingly, means for restraining the degree of freedom in rotation of the second hydraulic cylinder 52 on the second piston rod 42 is no longer needed (for example, the second piston rod 42 need not be formed to have a rectangular cross section). When the tire/wheel assembly 10 is a steering wheel, the link 92 can also serve as a tie-rod by being connected to a steering mechanism.

[0033] Meanwhile, when the link 92 is coupled with the carrier 70 and the tire/wheel assembly 10 is a steering wheel, rotation of the second hydraulic cylinder 52 on the second piston rod 42 can be controlled by coupling the tie-rod with the first hydraulic

cylinder 50. When the tire/wheel assembly 10 is not a steering wheel, rotation of the second hydraulic cylinder 52 on the second piston rod 42 may be restrained, for example, by forming the second piston rod 42 to have a rectangular cross section.

[0034] Thus, the tire/wheel assembly 10 is restrained with a certain degree of freedom in the vertical/substantially vertical movement with respect to the arm 90 (actually, with respect to the vehicle body). Namely, the suspension is restrained with a certain degree of freedom of in the vertical/substantially vertical movement.

[0035] Next, the operation when the tire/wheel assembly 10 jounces/rebounds will be described. When the tire/wheel assembly 10 jounces, the second piston rod 42 moves upward with respect to the arm 90 (the second hydraulic cylinder 52), and the upper hydraulic chamber 52a of the second hydraulic cylinder 52 is compressed. Thus, the fluid in the upper hydraulic chamber 52a of the second hydraulic cylinder 52 is sent, under pressure, through the fluid passage 42c, the second link passage 62 and the fluid passage 4Od, and discharged into the lower hydraulic chamber 50b of the first hydraulic cylinder 50. At this time, the lower hydraulic chamber 50b is pressurized and expanded, and the upper hydraulic chamber 50a of the first hydraulic cylinder 50 is compressed. When the upper hydraulic chamber 50a is compressed, the fluid in the upper hydraulic chamber 50a is sent, under pressure, through the fluid passage 40c, the first link passage 60 and the fluid passage 42d, and discharged into the lower hydraulic chamber 52b of the second hydraulic cylinder 52. When the compressed fluid is discharged into the lower hydraulic chamber 52b, the lower hydraulic chamber 52b of the second hydraulic cylinder 52 is pressurized and expanded. As a result, the first piston rod 40 and the second piston rod 42 move upward, in phase, with respect to the first hydraulic cylinder 50 and the second hydraulic cylinder 52, respectively. [0036] When the tire/wheel assembly 10 rebounds, the second piston rod 42 moves downward with respect to the arm 90 (the second hydraulic cylinder 52), and the lower hydraulic chamber 52b of the second hydraulic cylinder 52 is compressed. Thus, the fluid in the lower hydraulic chamber 52b of the second hydraulic cylinder 52 is sent, under pressure, through the fluid passage 42d, the first link passage 60 and the fluid

passage 40c, and discharged into the upper hydraulic chamber 50a of the first hydraulic cylinder 50. At this time, the upper hydraulic chamber 50a is pressurized and expanded, and the lower hydraulic chamber 50b of the first hydraulic cylinder 50 is compressed. When the lower hydraulic chamber 50b is compressed, the fluid in the lower hydraulic chamber 50b is sent, under pressure, through the fluid passage 4Od, the second link passage 62, and the fluid passage 42c, and discharged into the upper hydraulic chamber 52a of the second hydraulic cylinder 52. When the compressed fluid is discharged into the upper hydraulic chamber 52a, the upper hydraulic chamber 52a of the second hydraulic cylinder 52 is pressurized and expanded. As a result, the first piston rod 40 and the second piston rod 42 move downward, in phase, with respect to the first hydraulic cylinder 50 and the second hydraulic cylinder 52, respectively.

[0037] Thus, in the embodiment, when the tire/wheel assembly 10 jounces/rebounds, the first hydraulic cylinder 50 moves (slides) in the vertical/substantially vertical direction with respect to the first piston rod 40 in accordance with the vertical/substantially vertical movement (sliding) of the second piston rod 42 with respect to the arm 90 (the second hydraulic cylinder 52). Thus, a certain degree of freedom in the vertical/substantially vertical movement of the suspension is ensured. Hereafter, the thus produced vertical/substantially vertical movement (sliding) of the first hydraulic cylinder 50 (the second hydraulic cylinder 52) with respect to the first piston rod 40 (the second piston rod 42) will be sometimes referred to as "sliding of the first hydraulic cylinder 50 (the second hydraulic cylinder 52)".

[0038] Referring again to FIG. 1, a spring element 80 and an attenuation element 82, which slide in accordance with sliding of the first hydraulic cylinder 50 and the second hydraulic cylinder 52, are arranged in the wheel. [0039] In FIG. 1, the spring element 80 is a spring (a coil spring), and arranged between a lower spring seat 80a and an upper spring seat 80b so as to surround the first hydraulic cylinder 50. Thie lower spring seat 80a is fixed at a position near the lower end of the first piston rod 40. The upper spring seat 80b is fixed to the upper portion of the first hydraulic cylinder 50. The spring element 80 extends and contracts in the

vertical/substantially vertical direction coaxially with the first piston rod 40. A rebound stopper 8Od and a bound stopper 80c, which restrict extension and contraction of the spring element 80 (the sliding stroke of the first hydraulic cylinder 50), are provided at the upper end and the lower end of the first piston rod 40, respectively. In FIG. 1, the spring element 80 is arranged in the direction opposite to the direction in which a spring element is usually arranged. However, the upper spring seat 80b may be fixed to the upper end of the first piston rod 40, the lower spring seat 80a may be fixed to the lower end of the first hydraulic cylinder 50, and the spring element 80 may be arranged between the upper spring seat 80b and the lower spring seat 80a. The rebound stopper may be arranged in the first hydraulic cylinder 50. Also, a rebound spring and the like may be optionally provided.

[0040] In FIG. 1, the attenuation element 82 is a damper unit that is provided to the second link passage 62. The attenuation element 82 imposes resistance to the fluid that is sent through the second link passage 62 under pressure, thereby supplying attenuation force to sliding of the first hydraulic cylinder 50 and the second hydraulic cylinder 52. The attenuation element 82 may be an orifice similar to those formed in commonly used shock absorbers. The attenuation element 82 may be formed, for example, of a linear control valve, and the flow volume of the fluid passing through the orifice may be changed by changing the area of the orifice, thereby changing the attenuation force in a stepwise manner or linearly.

[0041] Accordingly, as shown in FIG. 1, when the tire/wheel assembly 10 moves in the vertical/substantially vertical direction (when the tire/wheel assembly 10 jounces/rebounds), the first hydraulic cylinder 50 slides with respect to the first piston rod 40 in accordance with sliding of the second hydraulic cylinder 52 with respect to the second piston rod 42. In accordance with such a sliding motion, the spring element 80 extends and contracts. As a result, a shock that is caused when the tire/wheel assembly 10 moves in the vertical/substantially vertical direction is reduced. Also, the fluid, which is sent under pressure in the above-mentioned manner, passes through the attenuation element 82 in accordance with the sliding of the first hydraulic cylinder 50

and the second hydraulic cylinder 52, whereby the shock that is caused when the tire/wheel assembly 10 moves in the vertical/substantially vertical direction is attenuated.

[0042] According to the embodiment described above, two sets of sliding mechanisms (one set of sliding mechanism is formed of a combination of the hydraulic cylinder and the piston rod) are provided, and the two sliding mechanism are operated in accordance with each other. As a result, flexibility in arrangement of the spring element

80 and the attenuation element 82 improves. In the embodiment, the spring element 80 is arranged on the first hydraulic cylinder 50 side. However, the spring element 80 may be arranged on the second hydraulic cylinder 52 side, although there is a constraint on its arrangement due to the presence of the brake caliper 20. Also, the attenuation element 82 may be arranged at any position of the first link passage 60 and the second link passage 62. Thus, the main portions of the suspension components can be efficiently arranged in the wheel.

[0043] According to the embodiment, flexibility of the arrangement of the sliding mechanisms improves. Because the two sets of sliding mechanisms are operated in accordance with each other via a hydraulic circuit, the two sliding mechanisms can be arranged independently of each other. Accordingly, additional space near the wheel center can be obtained by arranging one of the two sliding mechanisms on the front side of the wheel center, and the other sliding mechanism on the rear side of the wheel center. For example, the drive shaft can be passed through the space near the wheel center, when one of the two sliding mechanisms is arranged on the front side of the wheel center, and the other sliding mechanism is arranged on the rear side of the wheel center, and the first link passage 60 and the second link passage 62 are routed so as not to pass the wheel center, as shown in FIG. 1. [0044] When the pressure-receiving area (the cross sectional area of the hydraulic chamber cut in the direction perpendicular to the axial direction of the piston rod) of the first hydraulic cylinder 50 is equal to that of the second hydraulic cylinder 52, the first hydraulic cylinder 50 and the second hydraulic cylinder 52 slide by the same stroke. Namely, the sliding strokes of the two sets of sliding mechanism are equal to each other.

[0045] Meanwhile, when the pressure receiving area differs between the first hydraulic cylinder 50 and the second hydraulic cylinder 52, the sliding stroke also differs between the first hydraulic cylinder 50 and the second hydraulic cylinder 52. For example, as shown in FIG. 1, when the pressure receiving area of the first hydraulic cylinder 50 is greater than that of the second hydraulic cylinder 52, the sliding stroke of the first hydraulic cylinder 50 is less than that of the second hydraulic cylinder 52.

[0046] Accordingly, when the pressure receiving area of the first hydraulic cylinder 50 is greater than that of the second hydraulic cylinder 52, the spring element 80 is arranged on the side of the sliding mechanism having a greater pressure receiving area (on the side of the combination of the first hydraulic cylinder 50 and the first piston 40), as shown in FIG. 1. As a result, the stroke of the spring element 80 can be reduced. Also, it becomes easier to arrange the rebound stopper 8Od and the bound stopper 80c at the upper end and the lower end of the first piston 40.

[0047] In addition, when the pressure receiving area differs between the first hydraulic cylinder 50 and the second hydraulic cylinder 52, if the first hydraulic cylinder 50 is coupled with the vehicle body via the link 92 as shown in FIG. 3, the link 92 moves in the vertical/substantially vertical direction based on the difference in the sliding stroke between the first hydraulic cylinder 50 and the second hydraulic cylinder 52 when the tire/wheel assembly 10 moves in the vertical/substantially vertical direction. Accordingly, the toe-angle of the tire/wheel assembly 10 can be adjusted when the tire/wheel assembly 10 moves in the vertical/substantially vertical direction (when the tire/wheel assembly 10 jounces/rebounds), by appropriately making an adjustment such that the link 92 moves along an appropriate path, namely, the coupling point, at which the link 92 is coupled with the first hydraulic cylinder 50, moves along the appropriate path (when only one link 92 is provided, the link 92 moves using the coupling point, at which the link 92 is coupled with the vehicle body, as the supporting point, and an adjustment is made such that the end of the link 92 moves along an appropriate arc). For example, when only one link 92 is horizontally provided, the coupling point, at which the link 92 is coupled with the first hydraulic cylinder 50, moves toward the inside of the vehicle as the

tire/wheel assembly 10 moves in the vertical/substantially vertical direction. As a result, the orientation of the tire/wheel assembly 10 can be changed such that the toe-in-angle increases.

[0048] The first piston rod 40 and the second piston rod 42 in the embodiment correspond to "sliding shaft members" according to the invention, and the first hydraulic cylinder 50 and the second hydraulic cylinder 52 in the embodiment correspond to the "sliding members" according to the invention.

[0049] The embodiment of the invention that has been disclosed in the specification is to be considered in all respects as illustrative and not restrictive. All changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

[0050] For example, in the embodiment described above, the first hydraulic cylinder 50 and the second hydraulic cylinder 52 are enabled to slide in accordance with each other by a link device such as the hydraulic circuit. However, as schematically shown in FIG. 4, the first hydraulic cylinder 50 and the second hydraulic cylinder 52 may be enabled to slide in accordance with each other by a mechanical transmission mechanism such as a belt. In a modified example shown in FIG. 4, the first hydraulic cylinder 50 and the second hydraulic cylinder 52 are connected to each other by a belt 100 via pulleys 102 such that the first hydraulic cylinder 50 and the second hydraulic cylinder 52 move in phase. The belt 100 is looped over the pulleys 102 such that a portion of the belt 100 between two pulleys 102 crosses another portion of the belt 100 between other two pulleys 102. In this case as well, one of the two sliding mechanisms is arranged on the front side of the wheel center, and the other sliding mechanism is arranged on the rear side of the wheel center. Also, the belt 100 is arranged so as not pass the wheel center, as shown in FIG. 4. As a result, the drive shaft can be passed through the space near the center wheel. Also, an attenuation element can be realized by applying a rotary electromagnetic absorber 104, which attenuates a rotary input, to one of the pulleys 102 (the upper pulley 102 at a position closer to the rear of the vehicle, in the example shown in FIG. 4) that rotate in accordance with the movement of the belt 100. The absorber

104 includes a rotating shaft that meshes with the pulley 102. The absorber 104 attenuates the rotational force transferred to the rotating shaft via rotation of the pulley 102. Namely, when the rotating shaft (pulley 102) rotates, a magnetic field that acts to suppress rotation of the rotating shaft is formed by a magnet housed in the absorber body. Thus, the rotational force transferred to the rotating shaft via the rotation of the pulley 102 is attenuated.

[0051] In the embodiment, the ends of the arm portions 72a, 72b, 74a, and 74b of the carrier 70 are arranged inboard of the carrier 70, whereby the first piston rod 40 and the second piston rod 42 (and the first hydraulic cylinder 50 and the second hydraulic cylinder 52, and the spring element 80) can be arranged in the wheel. However, if the distance between the end of each arm portion and the carrier 70 is insufficient, these components may partially protrude from the wheel in the vehicle-width direction.

[0052] In the tire/wheel assembly 10 according to the embodiment, the brake caliper 20 is arranged at a position close to the rear of the vehicle, and the spring element 80 is arranged at a position close to the front of the vehicle. However, the brake caliper 20 may be arranged at a position close to the front of the vehicle, and the spring element 80 may be arranged at a position close to the rear of the vehicle. Also, when the tire/wheel assembly 10 is not a driving wheel, two sliding mechanisms may be arranged in parallel near the center of the tire/wheel assembly 10.