JP6972896B2 - Vehicle undercarriage of electric vehicle - Google Patents

Description

The present invention relates to a vehicle undercarriage structure of an electric vehicle.

Generally, a suspension structure is provided in the lower part of the vehicle. Of the plurality of types of suspension structures, for example, an axle suspension type suspension structure is often used for, for example, a four-wheel drive off-road vehicle. A four-wheel drive vehicle generally has a power transmission path for transmitting power generated by an engine mounted on the front portion of a vehicle body to rear wheels (rear wheels).

Even when the four-wheel drive vehicle as described above is configured as an electric vehicle, a power transmission path for transmitting the power generated by a power unit such as a drive motor to the rear wheels is required. Generally, a propeller shaft or a differential gear is provided in the power transmission path.

Further, a steering mechanism for steering the wheels is arranged in the lower part of the vehicle. As the steering mechanism, a ball nut type steering mechanism and a rack and pinion type steering mechanism are known. For example, Patent Document 1 discloses a structure in which a rack and pinion type steering mechanism is arranged so as to be adjacent to an axle suspension type suspension mechanism.

Jitsukaisho 55-153275 Gazette

In a four-wheel drive vehicle as described above, it is required to set a high ground height to improve running performance, and to simplify the structure and reduce the weight. Therefore, the steering mechanism is required to have a simple structure and high rigidity. In this case, since the ball nut type steering mechanism has low rigidity, it may be easily affected by disturbance when traveling on unpaved roads. On the other hand, the rack and pinion type steering mechanism has a relatively simple structure and high rigidity.

However, if a rack and pinion type steering mechanism is used, it may interfere with the propeller shaft and differential gear described above.

The present invention has been made to solve the above problems, and an object of the present invention is to set a high ground height of the vehicle body to improve running performance, and to simplify the structure and reduce the weight of the electric vehicle. Is to provide the vehicle undercarriage of.

In order to achieve the above object, the vehicle lower structure of the electric vehicle according to the present invention includes an axle to which wheels arranged on the left and right sides of the vehicle can be connected, a wheel driving motor for driving the wheels, and the axle and the wheels. It includes an axle housing that houses a drive motor and a steering mechanism that steers the wheels. In the vehicle lower structure of the electric vehicle, the axle is arranged on the vehicle width direction side portion in the axle housing, and the wheel drive motor is arranged on the vehicle width direction center portion in the axle housing. The rack pinion gearbox constituting a part of the steering mechanism is housed in the axle housing, the rack pinion gearbox is arranged in the vehicle width direction center portion, and the vehicle width direction center portion in the axle housing. Is provided with a motor frame that surrounds the wheel drive motor and fixes the wheel drive motor in a top view, and the motor frame is provided with a fixing portion to which the rack pinion gearbox is attached. Has been done.

According to the present invention, the ground height of the vehicle body can be set high to improve the running performance, and the structure can be simplified and reduced in weight.

It is a bottom view which looked at the vehicle lower structure of the electric vehicle which concerns on this invention from the lower side of the vehicle. It is an enlarged bottom view which shows the rear axle housing and the like on the rear side of the vehicle of FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 2 is a perspective view of the rear axle housing of FIG. 2 as viewed from the rear of the vehicle. FIG. 2 is a rear view of the rear axle housing and the like as viewed from the rear of the vehicle. It is a perspective view which shows the wheel drive motor and the like housed in the axle housing of FIG. It is a bottom view which shows the modification of FIG.

Hereinafter, the vehicle lower structure of the electric vehicle according to the present invention will be described with reference to the drawings (FIGS. 1 to 7). The vehicle 1 in the present embodiment is a four-wheel drive electric vehicle having an axle suspension structure, and a wheel drive motor is connected to each wheel via an axle or the like. Further, the axle and the wheel drive motor are housed inside the axle housing. Further, the steering mechanism of the present embodiment is a rack and pinion type steering mechanism, and includes a rack and pinion gearbox. The rack and pinion gearbox is housed inside the axle housing. Hereinafter, the vehicle lower structure of the present embodiment will be described.

As shown in FIGS. 1 and 2, the rear portion of the vehicle lower structure of the present embodiment includes rear axles 12a and 12b, rear wheel drive motors 22a and 22b, rear suspension 27, and rear rack and pinion gearboxes 24a and 24b. I have. Further, the rear portion of the vehicle lower structure includes a rear axle housing 14 and the like. The rear axle housing 14 houses the rear wheel drive motors 22a and 22b and the rear rack and pinion gearboxes 24a and 24b.

Further, the front portion of the vehicle lower structure includes a front axle, a front wheel drive motor, a front suspension, and a front rack and pinion gearbox, as in the rear portion. Further, the front portion of the vehicle lower structure includes a front axle housing 13 and the like. The front axle housing 13 houses a front wheel drive motor and a front rack and pinion gearbox. In the present embodiment, the structure of the rear part of the vehicle and the structure of the front part of the vehicle have the same structure. Therefore, the structure of the rear part of the vehicle will be described in detail below.

The rear axles 12a and 12b, the rear wheel drive motors 22a and 22b, and the rear rack and pinion gears 24a and 24b in the present embodiment are individually arranged on the left and right sides, respectively. That is, the rear axles 12a and 12b have a left rear axle 12a and a right rear axle 12b, and the rear wheel drive motors 22a and 22b have a left rear wheel drive motor 22a and a right rear wheel drive motor 22b. The rear rack and pinion gearboxes 24a and 24b have a left rear rack and pinion gearbox 24a and a right rear rack and pinion gearbox 24b.

Similarly for the front part, the front axle has a left front axle and a right front axle (both not shown), and the front wheel drive motor includes a left front wheel drive motor and a right front wheel drive motor (both not shown). The front rack and pinion gearbox has a left front rack and pinion gearbox and a right front rack and pinion gearbox (both not shown). The left and right in the description of the present embodiment correspond to the left and right when the vehicle 1 is seated in the driver's seat (not shown).

The left rear axle 12a and the right rear axle 12b are members that extend horizontally in the vehicle width direction, and are formed of, for example, a metal material. As shown in FIG. 2, the left rear wheel 4a is attached to the left end of the left rear axle 12a via a knuckle 9 or the like, and the right end is connected to the left rear wheel drive motor 22a. Similarly, the right rear wheel 4b is attached to the right end of the right rear axle 12b via a knuckle 9 or the like, and the left end is connected to the right rear wheel drive motor 22b. The left front axle and the right front axle are also configured in the same manner as the left rear axle 12a and the right rear axle 12b.

As shown in FIGS. 1 and 2, the rear axle housing 14 of the present embodiment is a member extending in the vehicle width direction as a whole, and is a rear housing central portion 14A arranged in the vehicle width direction central portion and a rear housing. It has rear housing side portions 14B arranged on both sides of the central portion 14A in the vehicle width direction. The rear housing central portion 14A bulges in the vehicle front-rear direction and the vehicle vertical direction with respect to the rear housing side portion 14B, and has a left rear wheel drive motor 22a, a right rear wheel drive motor 22b, and a left rear rack inside. It houses the pinion gearbox 24a and the right rear rack pinion gearbox 24b.

Further, the front axle housing 13 is configured in the same manner as the rear axle housing 14, and has a front housing central portion 13A and a front housing side portion 13B. Similar to the rear housing central portion 14A, the front housing central portion 13A houses a left front wheel drive motor, a right front wheel drive motor, a left front rack and pinion gearbox, and a right front rack and pinion gearbox.

By mounting a drive mechanism (rear wheel and front wheel drive motors) and a steering mechanism (front and rear rack and pinion gearboxes) on the front and rear axle housings 13 and 14, suspension strokes that are less restricted in connecting the vehicle body and axles. Can be taken large.

Further, by mounting the front wheel drive motor and the rear wheel drive motors 22a and 22b on the front and rear axle housings 13 and 14, the transmission mechanism of the drive with the vehicle body can be omitted, and the drive wheel of the axle suspension type suspension. However, it is possible to secure a space for mounting a rack and pinion type steering gearbox (front and rear rack and pinion gearboxes). According to this configuration, since there is no propeller shaft or the like and there is no structure that cushions the left and right rear rack and pinion gearboxes 24a and 24b, the ground height can be increased, the running performance is improved, and the structure is simplified. It is possible to reduce the weight and weight.

Further, with the above configuration, the driving force and the driving direction of the left and right wheels can be operated separately in the rear portion and the front portion of the vehicle 1, and it becomes possible to carry out traveling control with a higher degree of freedom.

Here, the front and rear axle housings 13 and 14 will be described. The rear housing side portion 14B of the rear axle housing 14 is a tubular member extending outward in the vehicle width direction from both sides of the rear housing central portion 14A, and houses the left rear axle 12a and the right rear axle 12b inside. .. The left and right rear axles 12a and 12b project from the outside of the rear housing side portion 14B in the vehicle width direction toward the rear wheels 4a and 4b. Bearings 5 are provided on both outer sides of the rear housing side portion 14B in the vehicle width direction, and the left and right rear axles 12a and 12b are rotatably supported by the rear housing side portions 14B by the bearings 5. The front housing side portion 13B of the front axle housing 13 is similarly configured.

Further, as shown in FIGS. 4 and 5, the outer portion of the rear housing side portion 14B in the vehicle width direction is inclined so as to be located below the vehicle central portion 14A of the rear housing. That is, the lower surface of the rear housing central portion 14A of the rear axle housing 14 is arranged above the center of the left and right rear wheels 4a and 4b. The front housing side portion 13B is also configured in the same manner as the rear housing side portion 14B, and the lower surface of the front housing central portion 13A is arranged above the center of the left and right front wheels 3a and 3b. The front and rear axle housings 13 and 14 have a V shape in front view of the front of the vehicle and front view of the rear of the vehicle. With this configuration, a large clearance with the ground can be obtained and the running performance is improved.

Further, as shown in FIGS. 1, 4 and 5, mounting portions 6a and 7a of the link arm 6 and the lateral rod 7 are provided on the front and rear housing side portions 13B and 14B. The link arm 6 is arranged along the vehicle front-rear direction, and the lateral rod 7 is arranged along the vehicle left-right direction. The attachment portion 6a of the link arm 6 is provided at the lower part of a pair of left and right arm brackets 7b extending in the vertical direction of the vehicle, and one end of the link arm 6 is attached to the front and rear housing side portions via the arm bracket 7b. There is. Therefore, the arm bracket 7b is arranged along the vertical direction of the vehicle, and the upper and lower intermediate portions are joined to the rear surface of the front housing side portion 13B and the front surface of the rear housing side portion 14B, respectively. The other end of the link arm 6 is attached to the lower part of the vehicle body.

Further, one mounting portion of the lateral rod 7 is provided on the upper portion of the arm bracket 7b, and one end of the lateral rod 7 is mounted on the rear housing side portion 14B via the arm bracket 7b. Further, the other mounting portion of the lateral rod 7 is provided on the lower surface of the vehicle body, and the other end of the lateral rod 7 is attached to the lower surface of the vehicle body via the support bracket 7c.

Here, the suspension structures of the left rear axle 12a and the right rear axle 12b will be described. The left rear axle 12a and the right rear axle 12b are suspended by the rear suspension 27. In the structure of the rear suspension 27 of the present embodiment, the rear suspension 27 is configured on the upper part of the vehicle at the joint between the knuckle 9 and the left and right rear axles 12a and 12b, as shown in FIGS. 4 and 5. The strut 28 is rotatably held.

The basic design of the rear suspension 27 is a 5-link type rigid axle, which has a structure that does not cause an alignment change during a stroke in addition to the rough road running performance peculiar to the rigid suspension. Therefore, by holding the strut 28 rotatably on the upper part of the vehicle at the joint between the knuckle 9 and the rear axle, it is configured to positively utilize the alignment change by using the rack and pinion gear coaxial with the axle. There is. The front suspension is also configured in the same manner as the rear suspension 27.

Further, as shown in FIG. 4, the knuckle 9 of the present embodiment is provided with a reduction hub 9b. By providing the reduction hub 9b, it is possible to arrange the mounting portions of the front and rear axles at positions higher than the centers of the front wheels and the rear wheels, and the vehicle height can be set higher.

The left and right rear wheel drive motors 22a and 22b and the left and right front wheel drive motors are electric motors, and are powered and driven by a battery (not shown). In the wheel drive motor in the present embodiment, one wheel drive motor is connected to each wheel. That is, the left rear wheel drive motor 22a is connected to the left rear wheel 4a, and the right rear wheel drive motor 22b is connected to the right rear wheel 4b. Similarly, the left front wheel drive motor is connected to the left front wheel 3a, and the right front wheel drive motor is connected to the right front wheel 3b.

Further, the left rear wheel drive motor 22a and the right rear wheel drive motor 22b are housed inside the rear housing central portion 14A of the rear axle housing 14 in a state of being adjacent to the left and right along the vehicle width direction. There is. The left front wheel drive motor and the right front wheel drive motor are also housed inside the front housing central portion 13A of the front axle housing 13 in a state of being adjacent to the left and right along the vehicle width direction.

As shown in FIGS. 2 and 6, inside the rear housing central portion 14A, the left and right rear wheels surround the left rear wheel drive motor 22a and the right rear wheel drive motor 22b that are arranged side by side in a top view. A motor frame 21 for fixing the drive motors 22a and 22b is provided. In this example, it is substantially rectangular in top view. As shown in FIG. 3, the rear wheel drive motors 22a and 22b are fastened to the motor frame 21 by bolts or the like at the front and rear fastening portions 33 of the outer case. The upper and lower fastening portions 31 of the outer case are fastened to the ceiling and the bottom surface of the rear housing central portion 14A. In FIG. 3, the fastening portions 31 and 33 show only the fastening positions, and the detailed structure is not shown.

Further, a gap is provided between the left and right rear wheel drive motors 22a and 22b and the motor frame 21 and the inner wall of the rear axle housing 14. For example, the front wall of the motor frame 21 and the inner wall of the rear housing central portion 14A are arranged at intervals in the front-rear direction of the vehicle. Further, as shown in FIG. 3, the motor frame 21 is provided with a fixing portion 21a to which the left and right rear rack and pinion gearboxes 24a and 24b are attached. The upper and lower portions of the rear rack and pinion gearboxes 24a and 24b are fixed to the fixing portion 21a of the motor frame 21. Similarly, the motor frame 21 is provided inside the central portion 13A of the front housing.

By providing the motor frame 21, the rigidity of the fixed structure of the wheel drive motor can be easily improved. Further, by directly fixing the left and right rear rack and pinion gearboxes 24a and 24b to the front side of the motor frame 21 of the rear housing central portion 14A, the left and right rear rack and pinion gearboxes 24a and 24b can be moved in the vehicle front-rear direction. In front view, the rear axle housing 14 is arranged so as to overlap with the rear axle housing 14 and is located on the upper side of the vehicle with respect to the lower surface of the motor frame 21, so that space can be saved and clearance with obstacles can be easily secured.

In the motor frame 21, an auxiliary frame (not shown) extending in the front-rear direction of the vehicle is arranged between the lower surfaces of the left and right rear wheel drive motors 22a and 22b and the inner bottom surface of the rear housing central portion 14A. ing. By providing the auxiliary frame, the rigidity and strength of the motor frame 21 can be improved, and further, it is possible to prevent and protect the drive motor and the steering mechanism from direct contact with the ground or obstacles. Become. The front motor frame 21 is similarly configured, and the same effect can be obtained.

The fixing portion 21a of the motor frame 21 arranged inside the rear axle housing 14 is provided at the front portion of the motor frame 21, and the left and right rear rack and pinion gearboxes 24a and 24b are the left and right rear wheel drive motors 22a. It is arranged on the front side of 22b. Similarly, the fixed portion of the motor frame arranged inside the front axle housing 13 is provided at the rear of the motor frame, and the left and right front rack and pinion gearboxes are arranged on the rear side of the left and right front wheel drive motors. There is. That is, the front and rear rack and pinion gearboxes are arranged inside the wheelbase between the front and rear axles in the front-rear direction of the vehicle.

Further, the fixing portion 21a of the motor frame 21 arranged inside the rear axle housing 14 extends from the front portion of the motor frame 21 to the lower side of the vehicle of the left and right rear rack and pinion gearboxes 24a and 24b, and the lower end of the fixing portion 21a. Is located above the vehicle above the lower end of the motor frame 21. With this configuration, the fixed portion 21a is placed so that the motor frame 21 and the rear axles 4a and 4b overlap with each other when the vehicle is viewed from the front and rear, and the steering mechanism is arranged. It becomes easier to protect the motors 22a and 22b and the left and right rear rack and pinion gearboxes 24a and 24b. The same applies to the motor frame inside the front axle housing 13.

The steering mechanism for steering the left rear wheel 4a and the right rear wheel 4b includes the left rear rack and pinion gearbox 24a and the right rear rack and pinion gearbox 24b described above. The left rear rack and pinion gearbox 24a and the right rear rack and pinion gearbox 24b are connected to the left and right rear wheels 4a and 4b via a tie rod 26 extending along the vehicle width direction.

In this example, the left and right rear rack and pinion gears overlap the left and right rear axles 12a and 12b that connect the left and right rear wheel drive motors 22a and 22b and the left and right rear wheels 4a and 4b when viewed from the front in the front-rear direction of the vehicle. A tie rod 26 connecting the boxes 24a and 24b and the left and right knuckle arms 8 is arranged. Further, at the central portion 14A of the rear housing, the vehicle has a vehicle vertical position (height) at the end of the motor shaft (not shown) and the ends of the rear rack and pinion gearboxes 24a and 24b (joints of the tie rods 26). The positions in the vertical direction are arranged to be the same. The steering mechanism for steering the left front wheel 3a and the right front wheel 3b is also configured in the same manner as the steering mechanism for steering the left rear wheel 4a and the right rear wheel 4b.

With the rack and pinion type steering configuration in this way, the rack and pinion gearboxes 24a and 24b and the knuckle 9 are connected by the tie rod 26, so even if the rear axle housing 14 is formed in a chevron shape (H-shape). , Steering accuracy can be ensured. Further, by arranging the tie rod 26 at a height overlapping the axle and the axle housings 13 and 14, the tie rod 26 can be easily protected and the decrease in operation efficiency can be suppressed.

Further, as shown in FIG. 2, a steering drive motor 25 is provided in each of the left rear rack and pinion gearbox 24a and the right rear rack and pinion gearbox 24b. The steering drive motor 25 is similarly provided in each of the left front rack and pinion gearbox and the right front rack and pinion gearbox. As shown in FIG. 3, the steering drive motor 25 is fixed to the rear rack pinion gearboxes 24a and 24b.

The steering drive motor 25 is configured to be driven by an electric signal. That is, the steering mechanism employs a so-called steer-by-wire technique that does not have a steering shaft connected to a steering wheel arranged in the vehicle interior. The steering drive motor 25 is attached to, for example, a pinion gear shaft of a rack and pinion gear, and the shaft is rotated by an electric signal sent from the vehicle interior to steer the wheels.

With this configuration, different steering operations can be performed on the left and right rear wheels 4a and 4b, with a higher degree of freedom, less restrictions on the suspension stroke, and more accurate vehicle maneuvering. It will be possible.

Further, in the present embodiment, the left and right front wheel drive motors and the left and right front rack pinion gearboxes arranged in the front axle housing 13, and the left and right rear wheel drive motors 22a arranged in the rear axle housing 14 The 22b and the left and right rear rack pinion gearboxes 24a and 24b are arranged symmetrically in the front-rear direction of the vehicle. That is, these are arranged line-symmetrically with respect to the vehicle width direction line at the center of the wheelbase in the front-rear direction of the vehicle. As a result, the steering angles, driving force, and driving direction of the front, rear, left, and right wheels (four wheels) can be operated respectively, and the movement of the vehicle 1 with a greater degree of freedom can be realized. Furthermore, productivity and maintainability can be improved by standardizing parts.

Further, the left and right rear rack and pinion gearboxes 24a and 24b and the left and right rear wheel drive motors 22a and 22b are arranged symmetrically. The left and right front rack and pinion gearboxes and the left and right front wheel drive motors are also arranged in the same way.

The description of the present embodiment is an example for explaining the present invention, and does not limit the invention described in the claims. Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

For example, in the above embodiment, the four-wheel drive vehicle is described, but the present invention is not limited to this, and a two-wheel drive vehicle may be used.

Further, as shown in FIG. 7, one rear rack and pinion gearbox 24 may be configured to steer the left and right rear wheels 4a and 4b. In this case, one steering drive motor 25 may be attached to the rear rack and pinion gearbox 24. Further, in the above embodiment, drive motors are provided on the left and right wheels, respectively, but the present invention is not limited to this. The left and right wheels may be driven by a common drive motor.

1 Vehicle 3a Left front wheel 3b Right front wheel 4a Left rear wheel 4b Right rear wheel 6 Link arm 6a Link arm mounting part 7 Lateral rod 7a Lateral rod mounting part 8 Knuckle arm 9 Knuckle 12a Left rear axle 12b Right rear axle 13 Front axle housing 13A Front housing center 13B Front axle side 14 Rear axle housing 14A Rear housing center 14B Rear housing side 21 Motor frame 21a Fixed 22a Left rear wheel drive motor 22b Right rear wheel drive motor 24a Left rear rack and pinion gear Box 24b Right rear rack and pinion gearbox 25 Steering drive motor 26 Tie rod 27 Rear suspension 28 Struts 31, 33 Fasteners

Claims (7)

An axle to which wheels arranged on the left and right sides of the vehicle can be connected, a wheel drive motor for driving the wheels, an axle housing for accommodating the axle and the wheel drive motor, and a steering mechanism for steering the wheels. In the vehicle undercarriage of an electric vehicle equipped with
The axle is arranged in the vehicle width direction side portion in the axle housing, and the wheel drive motor is arranged in the vehicle width direction central portion in the axle housing.
The rack and pinion gearbox constituting a part of the steering mechanism is housed in the axle housing, and the rack and pinion gearbox is arranged in the central portion in the vehicle width direction .
A motor frame is provided at the center of the axle housing in the vehicle width direction so as to surround the wheel drive motor in a top view and fix the wheel drive motor.
The vehicle lower structure of an electric vehicle, characterized in that the motor frame is provided with a fixing portion to which the rack and pinion gearbox is attached. The lower portion of an electric vehicle according to claim 1 , wherein the motor frame has an auxiliary frame arranged between a lower surface of the wheel drive motor and a lower surface in the axle housing. structure. The axle housing is arranged at the front of the vehicle and the rear of the vehicle.
The fixing portion of the motor frame in the axle housing disposed at the front of the vehicle is disposed at the rear of the motor frame.
The vehicle for an electric vehicle according to claim 1 or 2 , wherein the fixing portion of the motor frame in the axle housing arranged at the rear portion of the vehicle is arranged at the front portion of the motor frame. Substructure. The vehicle for an electric vehicle according to any one of claims 1 to 3 , wherein the lower surface of the central portion of the axle housing in the vehicle width direction is arranged above the center of the wheel. Substructure. The steering mechanism has a left rack and pinion gearbox that steers the wheels on the left side in the vehicle width direction, and a right rack and pinion gearbox that steers the wheels on the right side in the vehicle width direction.
A steering drive motor is provided in each of the left rack and pinion gearbox and the right rack and pinion gearbox.
The lower part of the electric vehicle according to any one of claims 1 to 4 , wherein the steering drive motor is configured to be driven by an electric signal transmitted from the vehicle interior. structure. The electric vehicle according to any one of claims 1 to 5 , wherein the wheel driving motor is provided on each of the left wheel on the left side in the vehicle width direction and the right wheel on the right side in the vehicle width direction. Vehicle undercarriage. The wheel drive motor and rack and pinion gearbox arranged in the axle housing corresponding to the front wheels on the front side of the vehicle, and the wheel drive arranged in the axle housing corresponding to the rear wheels on the rear side of the vehicle. The vehicle lower structure according to any one of claims 1 to 6 , wherein the motor and the rack and pinion gearbox are arranged symmetrically in the front-rear direction.

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