JP2021154990A - Suspension structure for in-wheel motor drive device - Google Patents

Abstract

To provide a structure which prevents interference between an in-wheel motor drive device and a damper without reducing a lever ratio that is defined by a suspension member and the damper.SOLUTION: A suspension device 40 for an in-wheel motor drive device comprises: a lower arm 48 which extends in a vehicle width direction, of which a vehicle width direction outer end 48p is connected to a lower part of an in-wheel motor drive device 10 and a vehicle width direction inner end 48q is so connected to a sub frame 30 as to be capable of oscillating in a vertical direction; a damper 43 which is located above the lower arm 48 and is telescopically movable in the vertical direction, and of which an upper end is connected to a vehicle body side member; a shaft part 46 which extends downward from a lower end 43c of the damper 43 and bends to a vehicle width direction outer side at a midship thereof, and of which a lower end 46d is so connected to a vehicle width direction outer area of the lower arm 48 as to be relatively rotatable; and a spring 44 which energizes upper and lower ends of the damper 43 in a direction of separating from each other.SELECTED DRAWING: Figure 1

Description

The present invention relates to a suspension device for connecting an in-wheel motor drive device to a vehicle body of an electric vehicle.

Conventionally, a structure described in Japanese Patent Application Laid-Open No. 2004-090822 (Patent Document 1) is known as a suspension device for connecting an in-wheel motor to a vehicle body of an electric vehicle such as an electric vehicle or a hybrid vehicle.

In the structure described in Pat. The lower end is connected to the lower arm.

Japanese Unexamined Patent Publication No. 2004-090822

However, the present inventor has found that the conventional suspension structure has some points to be further improved. FIG. 3 is a front view showing the inverse proportion, and shows a state seen in the front-rear direction of the vehicle. FIG. 4 is a side view showing the inverse proportion, and shows a state seen from the inside in the vehicle width direction. Since the motor portion 121 of the in-wheel motor 110 is arranged in a narrow space between the rim portion Wr of the road wheel W and the axis O of the wheel, the radial dimension Dm of the motor portion 121 is small, and the in-wheel motor 110 Insufficient output.

Therefore, in order to increase the motor output, it is necessary to increase the dimensions of the motor unit 121 in the radial direction and the axial direction. In the conventional structure, when the axial dimension Lm of the motor becomes large, the motor portion 121 interferes with the shock absorber 141 at the time of steering or the like. Therefore, as shown in the reference example shown in FIG. 5, it is necessary to move the arrangement of the shock absorber 141 inward in the vehicle width direction. Note that FIG. 5 is a front view showing a reference example, and shows a state seen from the front-rear direction of the vehicle. The shock absorber 141 is composed of a damper 143, a shaft portion 146, and a coil spring 144.

Briefly explaining the inverse proportion of FIGS. 3 to 5 and the reference example, the damper 143 extends straight in the vertical direction. A shaft portion 146 extends from the lower end 143c of the damper 143. The shaft portion 146 further extends straight from the damper 143. The lower end 146d of the shaft portion 146 is connected to an intermediate portion of the lower arm 148 extending in the vehicle width direction via a pivot axis (also referred to as a connection point Pb, Pc). The damper 143, the coil spring 144, and the shaft portion 146 are represented by a common center line Xc.

As shown in FIG. 3, the distance Ln is represented from the connection point Pb of the unmoved shaft portion 146 and the lower arm 148 to the axis Xb which is the swing center of the lower arm 148. The center line Xc passes through the connection point Pb.

FIG. 5 represents the distance Lr from the connection point Pc of the moved shaft portion 146 and the lower arm 148 to the swing axis Xb of the lower arm 148 (Ln> Lr). The center line Xc passes through the connection point Pc.

When the shock absorber 141 is moved inward in the vehicle width direction in comparison with FIGS. 3 and 5, the coil spring 144 integrally attached to the damper 143 of the shock absorber 141 also moves inward in the vehicle width direction. The lever ratio (Lr / Ls) represented by the ratio of the distance Lr from the lower arm swing axis Xb to the shock absorber connection point Pc with respect to the lower arm effective length Ls becomes smaller (Ln / Ls> Lr / Ls).

When the lever ratio becomes small, the load applied to the vehicle body side attachment point 148q provided at the inner end of the lower arm 148 in the vehicle width direction increases. Then, in order to increase the durability of the bush 151 at the vehicle body side mounting point 148q, it is necessary to set the rigidity of the bush 151 high. However, in the case of the suspension device connected to the in-wheel motor 110, since the vibration during driving the in-wheel motor is large, it is desirable to set the rigidity of the bush 151 to be low to improve the vibration isolation effect. Therefore, it is desired to avoid increasing the rigidity of the bush 151 to deteriorate the sound vibration performance.

An object of the present invention is to provide a structure in which the in-wheel motor drive device and the damper do not interfere with each other without reducing the lever ratio defined by the suspension member and the damper when increasing the output of the in-wheel motor drive device. be.

For this purpose, the suspension structure for an in-wheel motor drive according to the present invention extends in the vehicle width direction, the outer end in the vehicle width direction is connected to the lower part of the in-wheel motor drive, and the inner end in the vehicle width direction becomes a vehicle body side member. A suspension member that is swingably connected in the vertical direction, a damper that is arranged above the suspension member and can be expanded and contracted in the vertical direction, and whose upper end is connected to a member on the vehicle body side, and a damper that is downward from the lower end of the damper. A shaft portion that extends and bends outward in the vehicle width direction in the middle, and the lower end of which is rotatably connected to the outer region of the suspension member in the vehicle width direction, and a spring that urges the upper and lower ends of the damper to separate from each other. To be equipped with.

According to the present invention, the lever portion defined by the suspension member and the damper is ensured to have the same size as the conventional one by the shaft portion whose upper end is arranged inside in the vehicle width direction with respect to the lower end. Therefore, it is possible to avoid applying an excessive load to the inner end of the suspension member in the vehicle width direction and reduce the elastic modulus of the elastic bush that connects the inner end of the suspension member in the vehicle width direction and the vehicle body side member. .. Then, it is possible to suppress the vibration of the in-wheel motor drive device from being transmitted to the vehicle body side member. The suspension member may be a swinging member and is not particularly limited. The suspension member is, for example, a suspension arm that swings up and down, or a link member that is an element of a link structure. The upper end of the shaft portion extends linearly in line with the center line of the damper. The bending shape in the middle of the shaft portion is not particularly limited. The shaft portion may be integrally formed at the lower end of the damper and may be recognized as a part of the damper. Alternatively, the shaft portion may be a member separate from the damper and may be attached and fixed to the lower end of the damper. The shaft portion may be a single member or an assembly. For example, the shaft portion may be formed of separate members with the bent portion of the shaft portion as a boundary, and they may be connected and fixed to form the shaft portion. In this case, the shaft portion may further include a connecting member that reinforces the connecting portion where stress is likely to be concentrated.

The arrangement and structure of the spring are not particularly limited, but as one aspect of the present invention, the spring is a coil spring, which extends spirally so as to surround the damper and is provided on the upper end side and the lower end side of the damper, respectively. It is reduced between the pair of coil spring seats. In another aspect, the coil springs are placed elsewhere. In another aspect, the spring is an air spring.

As a preferable aspect of the present invention, the center line of the coil spring is arranged outside the center line of the damper in the vehicle width direction.

As a more preferable aspect of the present invention, the center line of the coil spring is inclined so as to move downward from the center line of the damper toward the outside in the vehicle width direction.

As one aspect of the present invention, the lower end of the coil spring is arranged above the motor portion of the in-wheel motor drive device or at the same height as the upper portion of the motor portion. According to this aspect, the interference between the motor portion and the coil spring can be avoided, and the diameter dimension and the axial dimension of the motor portion can be made larger than before. As one aspect of the present invention, the central axis of the motor portion of the in-wheel motor drive device is arranged so as to be displaced in the front-rear direction of the vehicle from the damper. According to this aspect, the interference between the motor portion and the coil spring can be avoided, and the diameter dimension and the axial dimension of the motor portion can be made larger than before.

As one aspect of the present invention, the in-wheel motor drive device drives the steering wheels. As another aspect of the present invention, the in-wheel motor drive device is arranged in the inner space region of the non-steering wheel to drive the non-steering wheel.

Thus, according to the present invention, the output of the in-wheel motor drive device is increased. Moreover, since the lever ratio defined by the suspension member and the damper does not become small, the suspension member can be connected to the vehicle body side member via a soft bush, and the vibration of the in-wheel motor drive device can be transmitted to the vehicle body side member. It is suppressed.

It is a front view which shows one Embodiment of this invention. It is a side view which shows the embodiment. It is a front view which shows the inverse proportion. It is a side view which shows the inverse proportion of FIG. It is a front view which shows the reference example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing an embodiment of the present invention, and shows a state viewed in the front-rear direction of the vehicle. FIG. 2 is a side view showing the same embodiment, and shows a state seen from the inside in the vehicle width direction. The present embodiment includes a wheel, an in-wheel motor drive device 10, a subframe 30, and a suspension device 40. The wheel is composed of a road wheel W and a tire T. The tire T fits on the outer circumference of the road wheel W. The road wheel W and the brake rotor BD are coaxially coupled to a wheel hub (not shown) of the in-wheel motor drive device 10. The axis O, which is the center line of the wheel hub, represents an axle.

The in-wheel motor drive device 10 includes a wheel hub bearing portion 11 that rotatably supports the wheel hub, a motor portion 12, and a deceleration portion 13 that decelerates the rotation of the motor portion 12 and transmits the rotation to the wheel hub bearing portion 11. It has a carrier 15. The axis O passing through the center of the wheel hub bearing portion 11 represents an axle. Regarding the position in the axis O direction, the wheel hub bearing portion 11 is arranged on one side in the axis O direction, the motor portion 12 is arranged on the other side in the axis O direction, and the deceleration portion 13 is arranged in the center in the axis O direction. Further, the motor unit 12 is offset from the axis O. The motor unit 12 of the present embodiment is arranged so as to be displaced from the axis O toward the front of the vehicle. The axis M of the motor unit 12 extends parallel to the axis O.

In the in-wheel motor drive device 10, one side in the axis O direction is outside the vehicle width direction (also referred to as the outboard side), and the other side in the axis O direction is inside the vehicle width direction (also referred to as the inboard side) in the vehicle width direction of the electric vehicle. It is placed on each side. Each in-wheel motor drive device 10 is connected to the subframe 30 by the suspension device 40.

The in-wheel motor drive device 10 is housed in the inner space of the road wheel W. The inner space region is partitioned by the inner peripheral surface of the rim portion Wr of the road wheel W and the inner surface surface of the spoke portions Ws in the axis O direction. However, a part of the motor unit 12 may protrude inward in the vehicle width direction from the inner space region.

The carrier 15 extends in the vertical direction, the central region is attached and fixed to the surface of the in-wheel motor drive device 10, and the upper and lower ends project from the deceleration portion 13 of the in-wheel motor drive device 10, respectively. As shown in FIG. 1, the upper and lower ends of the carrier 15 project outward from the central region in the vehicle width direction, respectively. As a result, the upper and lower ends of the carrier 15 are accommodated in the inner space region of the road wheel W.

An arm portion 16 is formed in the central region of the carrier 15. The arm portion 16 projects in the direction opposite to that of the motor portion 12, that is, toward the rear of the vehicle. The arm portion 16 is connected to the tie rod 18 of the steering device via a ball joint 17. The tie rod 18 extends in the vehicle width direction and pushes and pulls the arm portion 16 inward or outward in the vehicle width direction. As a result, the in-wheel motor drive device 10 is steered.

The brake caliper BC is arranged above the arm portion 16. The brake caliper BC is attached to the upper part of the in-wheel motor drive device 10 behind the axis O and brakes the brake rotor BD.

The suspension device 40 is a double wishbone suspension device and includes a shock absorber 41, an upper arm 47, and a lower arm 48. The shock absorber 41 is a suspension member that extends in the vertical direction so as to be expandable and contractible, and the lower end region of the shock absorber 41 is bent and formed. The bent and extended region is referred to as a shaft portion 46. The upper end of the shock absorber 41 is connected to the vehicle body of an electric vehicle (not shown) to support the vehicle body.

The shock absorber 41 includes a nested linear damper 43 and a coil spring 44 that spirally extends so as to surround the damper 43. An upper coil spring seat 42b is attached to the upper end of the damper 43, and a lower coil spring seat 42c is attached to the lower portion of the damper 43. The damper 43 occupies the upper end to the lower end of the shock absorber 41, and the lower end 43c of the damper 43 is coupled to the upper end of the shaft portion 46.

As shown in FIG. 1, a region of the damper 43 that protrudes downward from the lower coil spring seat 42c is referred to as a lower end region of the damper 43. The lower end region of the damper 43 is arranged adjacent to the inner side of the motor portion 12 in the vehicle width direction. The lower end region of the damper 43 is arranged at the same height as the motor unit 12. The shaft portion 46 bends and extends so as to avoid the motor portion 12, and the upper end of the shaft portion 46, that is, the lower end 43c of the damper 43, is arranged inside the motor portion 12 in the vehicle width direction, but the shaft portion 46 The lower end 46d of the motor unit 12 is arranged outside the vehicle width direction inner end surface 12f of the motor unit 12. The shaft portion 46 of the present embodiment is formed by bending at the center. As a result, the lower end portion of the shaft portion 46 is bent and extended so that the upper end portion is in an inclined posture and the upper end portion is in a nearly vertical posture. As a modification (not shown), the shaft portion 46 may be bent and formed in a gentle curved shape.

The coil spring 44 is shortened between a pair of upper and lower coil spring seats 42b and a lower coil spring seat 42c. The center of the upper coil spring seat 42b substantially coincides with the center line Xf of the damper 43, but the center of the lower coil spring seat 42c is arranged so as to be offset outward in the vehicle width direction from the center line Xf. Further, the lower coil spring seat 42c is arranged at substantially the same height as the upper portion of the motor portion 12 or at a position higher than the motor portion 12. A member on the vehicle body side, for example, a subframe 30, is referred to as a member on the vehicle body side in view of the member to be described (for example, the suspension device 40).

As shown in FIG. 1, the center line Xf of the damper 43 is reduced in inclination angle by the shaft portion 46 that bends and extends so that the lower end portion is in an inclined posture and the upper end portion is in a posture close to vertical, and the posture is close to vertical. Be made. On the other hand, the center line Xe of the coil spring 44 is in an inclined posture. Specifically, the center line Xe passes through the center of the pair of upper and lower coil spring seats described above, and as it goes downward, it separates from the center line Xf outward in the vehicle width direction. The center lines Xe and Xf intersect at the upper end of the shock absorber 41.

The shaft portion 46 bends and extends in the vertical direction, the lower end 46d is rotatably connected to the outer region of the lower arm 48 in the vehicle width direction via a pivot axis (hereinafter referred to as a connection point Pb), and the upper end is connected to the lower end 46c. Is also arranged inside in the vehicle width direction and is coupled with the lower end 43c of the damper 43. In this connection, the two members of the damper 43 and the shaft portion 46 are fixed to each other. Alternatively, the shaft portion 46 may be integrally formed at the lower end of the damper 43, and the shaft portion 46 may be regarded as a part of the damper 43. The center line Xe passes through the connection point Pb or in the vicinity of the connection point Pb. On the other hand, the center line Xf is separated from the connection point Pb inward in the vehicle width direction.

The lower arm 48 is a suspension member extending in the vehicle width direction, and is arranged below the axis O. The lower arm 48 is a triangular arm or an A-type arm, and has one outer end 48p in the vehicle width direction and two inner ends 48q and 48r in the vehicle width direction. The inner ends 48q and 48r in the vehicle width direction are separated in the vehicle front-rear direction. The outer end 48p of the lower arm 48 in the vehicle width direction is connected to the lower end of the carrier 15 via a ball joint 49. In FIG. 1, the inner end 48q in the vehicle width direction is shown, but the inner end 48r in the vehicle width direction is omitted.

The socket portion of the ball joint 49 is provided on the carrier 15 of the in-wheel motor drive device 10, and the stud portion extending from the ball portion accommodated in the socket portion is bolted to the outer end 48p in the vehicle width direction. The protruding direction of the stud portion is a direction away from the in-wheel motor drive device 10 (downward). The ball center of the ball joint 49 is arranged above the outer end 48p in the vehicle width direction (the side closer to the in-wheel motor drive device 10).

The inner ends 48q and 48r of the lower arm 48 in the vehicle width direction are rotatably connected to the subframe 30 via cylindrical elastic bushes 51 and 52, respectively. Thus, the lower arm 48 can swing in the vertical direction with the outer end 48p in the vehicle width direction as the free end and the inner ends 48q and 48r in the vehicle width direction as the base ends. The center line of the cylindrical elastic bush 51 forms the swing center of the lower arm 48, and is therefore referred to as the swing axis Xb. The swing axis Xb extends in the front-rear direction of the vehicle and passes through an elastic bush 52 provided at the inner end 48r in the vehicle width direction. The center line of the cylindrical elastic bush 52 extends in the vertical direction in the present embodiment, but may extend in the front-rear direction of the vehicle as a modification (not shown).

The upper arm 47 is a suspension member extending in the vehicle width direction, and is arranged above the axis O. The upper arm 47 is a V-shaped arm that branches from the outside in the vehicle width direction to the inside, and has one vehicle width direction outer end 47p and two vehicle width direction inner ends 47q and 47r. The outer end 47p of the upper arm 47 in the vehicle width direction is connected to the upper end of the carrier 15 via a ball joint 50. A shock absorber 41 is passed between the arms of the upper arm 47 that branches to the front and the rear of the vehicle, respectively.

The socket portion of the ball joint 50 is provided at the outer end 47p in the vehicle width direction. The stud portion protrudes from the ball portion housed in the socket portion. This protruding direction is a direction (downward) toward the in-wheel motor drive device 10. The stud portion of the ball joint 50 is fastened and fixed to the upper end of the carrier 15 with bolts. The ball center of the ball joint 50 is arranged below the outer end 47p in the vehicle width direction (the side closer to the in-wheel motor drive device 10).

The inner ends 47q and 47r of the upper arm 47 in the vehicle width direction are rotatably connected to a member on the vehicle body side (not shown) via cylindrical elastic bushes 53 and 54, respectively. The upper arm 47 can swing in the vertical direction with the outer end 47p in the vehicle width direction as the free end and the inner ends 47q and 47r in the vehicle width direction as the base ends. Since the center lines of the cylindrical elastic bushes 53 and 54 coincide with each other and form the swing center of the upper arm 47, they are referred to as swing axis Xd. The swing axis Xd extends in the front-rear direction of the vehicle.

By the way, in the present embodiment shown in FIG. 1, the outer end 48p in the vehicle width direction of the lower arm 48 extending in the vehicle width direction is connected to the lower portion of the in-wheel motor drive device 10, and the inner end 48q in the vehicle width direction is vertically connected to the subframe 30. It is connected so that it can swing. The shaft portion 46 is bent and extended in the vertical direction, the lower end is rotatably connected to the outer region of the lower arm 48 in the vehicle width direction at the connection point Pb, and the upper end is arranged inside the vehicle width direction with respect to the lower end. Therefore, the same lever ratio (Ln / Ls) as the inverse proportion shown in FIG. 3 can be secured. Therefore, the load acting on the elastic bushes 51 and 52 in the vertical direction becomes the same as the conventional one, and the elastic modulus of the elastic bushes 51 and 52 is reduced to suppress the vibration transmitted from the in-wheel motor drive device 10 to the subframe 30. can do.

Further, the damper 43 of the present embodiment can be expanded and contracted in the vertical direction, the lower end thereof is connected to the upper end of the shaft portion 46, and the upper end is connected to a vehicle body side member (not shown). The coil spring 44 urges the upper and lower ends of the damper 43 in a direction that separates them from each other. The damper 43 is arranged inside the motor portion 12 in the vehicle width direction by the shaft portion 46 that bends and extends in this way. Therefore, the diameter dimension Dl and the axial dimension Ll of the motor unit are made larger than the relative proportional radial dimension Dm and the axial dimension Lm shown in FIG. 3 (Ll> Lm, Dl> Dm) to increase the output of the motor unit 12. Can be planned.

Further, as shown in FIGS. 1 and 2, since the lower end of the coil spring 44 of the present embodiment is arranged at the same height as the upper portion of the motor portion 12, the diameter dimension Dl and the axial dimension Ll of the motor portion can be set. , Can be larger than the inverse proportion shown in FIG.

Further, in the present embodiment, since the axis M passing through the center of the motor portion 12 is arranged so as to be displaced in the vehicle front-rear direction from the damper 43, the diameter dimension Dl and the axial dimension Ll of the motor portion are shown in FIG. It can be larger than inverse proportion.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and modifications can be made to the illustrated embodiment within the same range as the present invention or within the same range. The coil spring 44 extends in the vertical direction and surrounds the damper 43, but the arrangement and structure of the spring of the suspension device 40 are not limited to this embodiment. The spring need only be urged in the direction of separating the upper and lower ends of the damper. As a spring of a modified example (not shown), an air spring may be adopted instead of the coil spring 44.

The present invention is advantageously utilized in electric vehicles and hybrid vehicles.

10 in-wheel motor drive, 11 wheel hub bearings,
12 Motor part, 12f Inner end face in vehicle width direction, 13 Deceleration part,
15 carriers, 17, 49, 50, 53 ball joints,
30 subframes, 40 suspension devices,
41 shock absorber, 42b upper coil spring seat,
42c lower coil spring seat, 43 damper,
44 coil spring (spring), 46 shaft part,
47 upper arm, 48 lower arm (suspension member),
51, 52, 53, 54 Elastic bush, Dl motor diameter dimension,
Ls lower arm effective length, Pb connection point, W road wheel,
Xd upper arm swing axis, Xb lower arm swing axis,
Xe coil spring centerline, Xf damper centerline.

Claims (7)

A suspension member that extends in the vehicle width direction, the outer end in the vehicle width direction is connected to the lower part of the in-wheel motor drive device, and the inner end in the vehicle width direction is connected to the vehicle body side member so as to be swingable in the vertical direction.
A damper that is arranged above the suspension member and can be expanded and contracted in the vertical direction, and the upper end is connected to the vehicle body side member.
A shaft portion that extends downward from the lower end of the damper, bends outward in the vehicle width direction in the middle, and the lower end is rotatably connected to the outer region of the suspension member in the vehicle width direction.
A suspension structure for an in-wheel motor drive that includes a spring that urges the upper and lower ends of the damper in a direction that separates them from each other. 15. The suspension structure for the in-wheel motor drive described. The suspension structure for an in-wheel motor drive according to claim 2, wherein the center line of the coil spring is arranged outside the center line of the damper in the vehicle width direction. The suspension structure for an in-wheel motor drive according to claim 3, wherein the center line of the coil spring is inclined so as to move downward from the center line of the damper toward the outside in the vehicle width direction. The in-wheel motor drive according to any one of claims 2 to 4, wherein the lower end of the coil spring is arranged above the motor portion of the in-wheel motor drive device or at the same height as the upper portion of the motor portion. Suspension structure for equipment. The suspension structure for an in-wheel motor drive according to any one of claims 1 to 5, wherein the central axis of the motor portion of the in-wheel motor drive is arranged so as to be displaced in the vehicle front-rear direction from the damper. The suspension structure for an in-wheel motor drive device according to any one of claims 1 to 6, wherein the in-wheel motor drive device drives a steering wheel.

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