JP2004338487A - Suspension device for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance ground contact performance (riding comfort) in an electric vehicle for making a motor as a power source. <P>SOLUTION: This device 10 is provided with the motor 12, first supporting means 22 and 24, etc. for supporting wheels driving by making the motor 12 as the power source on a vehicle body, a second supporting means 30 for elastically supporting the motor 12 on the vehicle body, and a power transmission mechanism 14 for connecting the motor 12 and the wheels to be relatively displaced and transmitting power generated by the motor 12 to the wheels. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a suspension device for an electric vehicle that uses a motor as a power source.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a suspension device for a wheel-in-motor type vehicle including a motor for driving each driving wheel in a wheel of the driving wheel is known (for example, see Patent Document 1). According to this conventional suspension device, by arranging the motor in the wheel, the space in the wheel can be effectively used as a space for mounting the motor, and the power is transmitted by connecting the motor and the axle. Weight of the mechanism to be performed can be achieved.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-16040
[Problems to be solved by the invention]
However, in the above-mentioned conventional suspension, when the motor is built in the wheel, the motor and the driving wheel are directly connected, so that the unsprung weight is reduced by the amount of the motor (and the additional components related thereto). It becomes heavy, and there is a problem that a fall of a grounding property (road surface followability) and a reduction of ride comfort accompanying it are caused.
[0005]
Therefore, an object of the present invention is to improve the contact property (ride comfort) in an electric vehicle using a motor as a power source.
[0006]
[Means for Solving the Problems]
The object is to provide a motor as described in claim 1;
First supporting means for supporting wheels driven by the motor as a power source with respect to a vehicle body;
Second support means for elastically supporting the motor with respect to the vehicle body;
And a power transmission mechanism that connects the motor and the wheels so as to be relatively displaceable and that transmits power generated by the motor to the wheels.
[0007]
In the present invention, the motor is not rigidly supported on the wheels or rigidly supported on the vehicle body, but is elastically supported on the vehicle body by the second support means. Therefore, according to the present invention, the wheel and the motor are independently supported by the first and second support means with respect to the vehicle body, so that the unsprung weight is reduced and the grounding property (riding) is improved. Comfort).
[0008]
In the case where the second support means supports the motor with respect to the vehicle body via a spring element and a damping element as described in claim 2, the wheel has characteristics suitable for each of the wheel and the motor. And a motor. That is, the characteristics (spring / damping characteristics) of the first and second support means can be separately adjusted and optimized.
[0009]
The damping element of the first supporting means and the damping element of the second supporting means may be hydraulically controlled so that the wheel and the motor move in opposite phases. In the case of a configuration in which the wheels and the motor are interconnected by a passage, the wheels and the motor are forcibly displaced in the up and down directions (opposite phases) when the wheels move up and down, so that a vibration damping effect can be obtained. In addition, the fluid (gas, oil, etc.) sealed in the hydraulic cylinder constituting each damping element flows through the hydraulic pressure passage.
[0010]
Further, when the damping elements of the second support means relating to each of the left and right wheels are interconnected by a hydraulic passage, the up and down movement of the motor can be in the same phase or in the opposite phase. Can be limited to For example, when the vertical movement of the motor is limited to the case of the same phase in the left and right, the vertical movement of the motor is allowed only during the unsprung vibration of the left and right in phase, so that the sprung movement in the roll direction by the reaction force of the motor is suppressed. can do.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 is a front view schematically showing a first embodiment of a suspension system for an electric vehicle according to the present invention. The electric vehicle suspension device 10 of the present embodiment includes a motor 12 for driving wheels. The motor 12 is provided for each drive wheel. Each drive wheel is provided with a not-shown braking mechanism (such as a caliper), and each steered wheel is provided with a not-shown steering mechanism (such as a tie rod). It should be noted that the configuration of the present embodiment does not substantially differ for each drive wheel, and therefore only one drive wheel will be described below. However, the configuration of the present embodiment may be applied only to the front wheel side or only to the rear wheel side.
[0013]
The rotating shaft of the motor 12 is connected to driving wheels via a drive shaft (including a constant velocity joint) 14 that passes through a knuckle (steering knuckle) 20. The drive shaft 14 is rotatably supported inside the knuckle 20 via a bearing 16. The lower end of a suspension 22 (comprising a coil spring and a shock absorber) whose upper end is connected to the vehicle body is connected to the knuckle 20. The other end of the lower arm 24 whose one end is rotatably supported by the vehicle body is connected to the knuckle 20 via a ball joint. With such a configuration, the drive wheels are supported movably mainly in the vertical direction with respect to the vehicle body, and the positions in the vertical direction are held by the suspension 22.
[0014]
FIG. 2 is a diagram showing the support structure of the motor 12 when viewed in the direction X of FIG. As shown in FIG. 1, the motor 12 of this embodiment is supported by a suspension 30 (in the embodiment shown in FIG. 1, a shock absorber having a built-in coil spring) so as to be mainly displaceable in the vertical direction with respect to the vehicle body. ing. At this time, as shown in FIG. 2, the motor 12 preferably has two suspensions 30 (typically having the same spring and damping characteristics so as to restrict the displacement when receiving the rotational reaction force. Are supported in parallel by the two suspensions 30). In this case, the motor 12 is respectively connected to the two suspensions 30 at two connection points 40 set at a predetermined interval along the outer periphery (peripheral surface of the motor housing). The motor 12 is suspended so as to be as close as possible to the drive wheels in order to shorten (and reduce the weight of) the power transmission mechanism (such as a constant velocity joint).
[0015]
With such a configuration, the motor 12 is supported by the suspension 30 so as to be able to move mainly in the vertical direction with respect to the vehicle body, and the position in the vertical direction is maintained, similarly to the drive wheels. Therefore, the center of gravity of the motor 12 and the wheel shaft can be moved vertically independently of each other. In this connection, a power transmission mechanism (constant velocity joint) for connecting the output shaft of the motor 12 and the wheel shaft is capable of absorbing and absorbing such a relative displacement between the motor 12 and the wheel shaft. Twelve rotational forces can be transmitted to the wheel shaft.
[0016]
In the present invention, the motor 12 and the driving wheels are elastically supported so as to be vertically displaceable independently of the vehicle body, and the driving force of the motor 12 can be transmitted to the wheel shaft. The method is not particularly limited to the above-described connection method between the motor 12 and the drive wheels and the suspension method of the drive wheels. For example, the present invention is applicable to a structure other than the above-described strut type suspension structure (for example, a double wishbone type suspension structure), and the motor 12 and the driving wheels are connected via a flexible coupling. They may be connected.
[0017]
FIG. 3 shows a spring-mass model (A) of the electric vehicle suspension device 10 of the present embodiment. FIG. 3 shows a spring-mass model (B) of a suspension device 10 for an electric vehicle in which a motor 12 is rigidly fixed to a vehicle body as a comparative example 1, and a motor 12 having a driving wheel as a comparative example 2. Also, a spring-mass model (C) of the electric vehicle suspension device 10 directly connected to FIG. FIG. 4 shows a characteristic curve (relationship between frequency and vertical acceleration) in each spring-mass model of FIG. 3 under the same condition (each mass, spring constant, etc.).
[0018]
In this embodiment, as is apparent from the above description and FIG. 3A, the motor 12 is coupled to the vehicle body independently of the drive wheels, so that the unsprung weight is the same as the configuration in FIG. 3B. Thus, the motor 12 (and parts related thereto) is smaller than the configuration of FIG. Therefore, according to the present embodiment, as shown by the solid line in FIG. 4, the grounding property (road surface following property) at the time of unsprung resonance is significantly larger than the configuration (dashed characteristic curve) of FIG. To improve. Further, in this embodiment, since the motor 12 is coupled to the vehicle body by a spring and a damper, the grounding property at the time of sprung resonance is lower than that of the configuration of FIG. Somewhat improved.
[0019]
As described above, according to the present embodiment, the motor 12 is eliminated from the unsprung components, so that the unsprung weight is reduced and the grounding property is improved. Further, since the motor 12 and the driving wheels are independently suspended from the vehicle body, it is possible to realize suspension characteristics suitable for each of the motor 12 and the driving wheels. In addition, since the motor 12 is coupled to the vehicle body by a spring and a damper, transmission of vibration of the motor 12 (for example, vibration due to rotation or vertical vibration when traveling on a rough road) can be prevented. Become.
[0020]
Next, a suspension apparatus 10 for an electric vehicle according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a front view schematically showing the electric vehicle suspension device 10 of the present embodiment. Also in the electric vehicle suspension system 10 of the present embodiment, since the configuration for each drive wheel is the same, only one drive wheel will be described below. However, the configuration of the present embodiment may be applied to only the front wheels or only the rear wheels of the drive wheels.
[0021]
This embodiment is different from the above-described embodiment in that, as shown in FIG. 5, a predetermined hydraulic chamber 22a (two hydraulic chambers partitioned by pistons in a hydraulic cylinder) of an absorber of a drive wheel suspension 22 is provided. Of the suspension 30 for the motor 12 and a predetermined hydraulic chamber 30a of the absorber of the suspension 30 for the motor 12 only in that they are communicated with each other through a hydraulic passage (for example, a pipe) 32. At this time, the hydraulic chambers 22a and 30a are connected by a hydraulic passage 32 so as to be displaced (expanded and contracted) in opposite phases. Therefore, for example, when the driving wheel bounces, the fluid in the driving wheel-side hydraulic chamber 22a is discharged into the hydraulic chamber 30a on the motor 12 side through the hydraulic pressure passage 32, and the motor 12 is moved downward (hydraulic pressure). (The direction in which the volume of the chamber 30a increases). As described above, according to the present embodiment, the motor 12 and the driving wheels are forcibly displaced in opposite phases, so that a vibration damping effect can be obtained.
[0022]
In this embodiment, when the absorbers of the two suspensions 30 are provided for the respective drive wheels as described above, between the two hydraulic chambers of each absorber and the hydraulic chamber 22a on the drive wheel side. May be independently connected by two hydraulic passages 32, or a predetermined hydraulic chamber of the absorber of the two suspensions 30 may be connected by another hydraulic passage so that they are forced to be in phase. The hydraulic chamber of the absorber of one suspension 30 may be communicated with the hydraulic chamber 22a on the driving wheel side by one hydraulic passage 32 as described above. The configuration of the present embodiment is naturally applicable to all types of shock absorbers, whether hydraulic or pneumatic, or single or double cylinder type.
[0023]
Next, an electric vehicle suspension system 10 according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a front view schematically showing the electric vehicle suspension apparatus 10 of the present embodiment. Since the structure of the suspension device 10 for an electric vehicle of the present embodiment is the same on the front wheel side and the rear wheel side, only the front wheel side will be described below. However, the configuration of the present embodiment may be applied only to the front wheel side or only to the rear wheel side.
[0024]
In the present embodiment, as shown in FIG. 6, predetermined hydraulic chambers 30aL and 30aR of the absorbers of the left and right wheel suspensions 30L and 30R are communicated with the first embodiment by a hydraulic passage 34. Only the point is different. At this time, the hydraulic chambers 30aL and 30aR are connected by a hydraulic passage 34 so as to be displaced (expanded and contracted) in the same phase. Therefore, for example, when the motor 12L on the left wheel side is displaced upward (in the direction in which the volume of the hydraulic pressure chamber 30aL is reduced), the fluid in the hydraulic pressure chamber 30aL of the left suspension 30L passes through the hydraulic pressure passage 34 and flows on the right side. The fluid is discharged into the hydraulic chamber 30aR of the suspension 30R, and the right wheel side motor 12R is urged upward (in a direction in which the volume of the hydraulic chamber 30aR increases). As described above, according to the present embodiment, the vertical movement of the left and right motors 12L and R is limited to the case where the left and right are in phase. become. This effectively suppresses the sprung being urged in the roll direction by the reaction force of the motors 12L and 12R.
[0025]
In this embodiment, similarly to the above-described second embodiment, when the absorbers of the two suspensions 30 are provided for each drive wheel as described above, similarly, two sets of left and right absorbers are provided. The hydraulic chambers may be independently connected by two hydraulic passages 32, or the hydraulic chambers of the two suspensions 30 on each side may be connected by separate hydraulic passages, and they may be forcibly connected. The hydraulic chambers of the left and right suspensions 30 may be communicated with each other by the single hydraulic passage 32 as described above.
[0026]
Although the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the above-described embodiment, and various modifications and substitutions can be made to the above-described embodiment without departing from the scope of the present invention. Can be added.
[0027]
For example, in the above-described first embodiment, the suspension 22 for the driving wheels and / or the suspension 30 for the motor 12 may be configured by a leaf spring instead of a coil spring and a hydraulic absorber.
[0028]
In the third embodiment described above, the hydraulic chambers 30aL and 30aR of the left and right wheel suspensions 30L and 30R may be connected by the hydraulic passage 34 so that they are displaced (expanded or contracted) not in phase but in opposite phases. Good.
[0029]
【The invention's effect】
Since the present invention is as described above, the following effects can be obtained. ADVANTAGE OF THE INVENTION According to this invention, in an electric vehicle which uses a motor as a power source, the grounding property (ride comfort) can be improved.
[Brief description of the drawings]
FIG. 1 is a front view schematically showing a first embodiment of a suspension system for an electric vehicle according to the present invention.
FIG. 2 is a diagram showing a support structure of a motor 12 when viewed in a direction X of FIG.
FIG. 3 is a diagram showing a spring-mass model of the suspension apparatus for an electric vehicle 10 of the present embodiment together with a comparative example.
FIG. 4 is a diagram showing performance curves in the configuration of each spring-mass model of FIG. 3;
FIG. 5 is a front view schematically showing a second embodiment of the suspension system for an electric vehicle according to the present invention.
FIG. 6 is a front view schematically showing a suspension apparatus for an electric vehicle according to a third embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 10 Suspension device for electric vehicle 12 Motor 14 Drive shaft 16 Bearing 20 Knuckle 22 Suspension 30 Suspension

Claims (4)

Motor and
First supporting means for supporting wheels driven by the motor as a power source with respect to a vehicle body;
Second support means for elastically supporting the motor with respect to the vehicle body;
A power transmission mechanism that connects the motor and the wheel so as to be relatively displaceable and that transmits power generated by the motor to the wheel. The suspension device for an electric vehicle according to claim 1, wherein the second support means supports the motor with respect to a vehicle body via a spring element and a damping element. The damping element of the first support means and the damping element of the second support means are interconnected by hydraulic passages such that the wheels and the motor move in opposite phases. 3. The suspension device for an electric vehicle according to 1 or 2. The suspension device for an electric vehicle according to claim 1, wherein the damping elements of the second support means for each of the left and right wheels are interconnected by a hydraulic passage.

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