JP2007126018A - Suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suspension device capable of controlling the vehicle posture with a relatively small force. <P>SOLUTION: The spring constant (the spring efficiency) of a suspension spring 6 in the vertical direction of a vehicle is variable. Thus, the posture of a vehicle can be controlled by reducing the spring efficiency (the spring constant in the vertical direction of the vehicle at the wheel position) at an arbitrary wheel position, increasing the set-in amount (the deflection) caused by the self weight or the inertia force, and inclining the vehicle in the wheel direction. Further, the spring efficiency is changed by moving a vehicle body side end of the suspension spring 6 in the direction orthogonal to the axial direction of the suspension spring 6 to support the sprung weight of the vehicle. Thus, in comparison with, for example, a suspension device for changing the vehicle posture by compressing the suspension spring 6 in the axial direction, the vehicle height at an arbitrary wheel position can be easily controlled, and the vehicle posture can be controlled with a small force. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a suspension device that controls a vehicle attitude.

Conventionally, as this kind of technology, the vehicle posture is lowered by pulling up the suspension device with a member having a spring function from the vehicle body side (a member whose spring constant is one digit smaller than the suspension spring of the suspension device) to lower the vehicle height. Some control (for example, refer to Patent Document 1).
JP 2004-268902 A

However, in the above prior art, the suspension is pulled up by a member whose spring constant is an order of magnitude smaller than that of the suspension spring. For example, in order to make the wheel stroke zero when turning the vehicle, the suspension device is 30 mm. In the case of raising the degree, the member had to be raised (taken up) by about 300 mm. Therefore, in order to obtain sufficient control performance, it is necessary to provide a high-power and high-speed winding device, resulting in a problem that the weight and size increase.
An object of the present invention is to provide a suspension device that can control the vehicle posture with a relatively small force.

  In order to solve the above-described problems, the suspension of the present invention is a suspension device that controls the vehicle posture, and the spring efficiency of each spring element that supports the vehicle weight (at the wheel position with respect to the inherent spring constant of the spring element). It is characterized by comprising a spring efficiency control means for controlling the vehicle posture by controlling the apparent spring constant ratio in the vertical direction of the vehicle.

Therefore, according to the suspension device of the present invention, the apparent spring constant at an arbitrary wheel position is reduced, the amount of subsidence due to its own weight or inertia force is increased at the wheel position, and the vehicle is tilted in the direction of the wheel. And the vehicle attitude can be controlled.
Further, by moving one end of the spring element in a direction orthogonal to the axial direction of the spring element and changing the spring efficiency by tilting the spring element, for example, a compressive force that compresses the spring element is generated to change the vehicle posture. The vehicle posture can be controlled with a relatively small force as compared with the changing one.

Embodiments of the suspension device of the present invention will be described below with reference to the drawings.
<Configuration of suspension device>
FIG. 1 is a schematic configuration diagram showing a double wishbone type suspension apparatus according to an embodiment of the suspension apparatus of the present invention. As shown in FIG. 1, the suspension device is disposed between a vehicle body 1 and a wheel 2 and includes an axle 3, a lower arm 4, an upper arm 5, a suspension spring 6, and a variable efficiency mechanism 7 (that is, In addition to the component groups 2 to 6 of the normal suspension device, the variable efficiency mechanism 7 is included.

The variable efficiency mechanism 7 is provided on the vehicle body side, and the end of the suspension spring 6 on the vehicle body side is attached.
FIG. 2 is an enlarged view of a main part showing the variable efficiency mechanism 7 in an enlarged manner. As shown in FIG. 2, the variable efficiency mechanism 7 includes a power source 8, a rotary linear converter 9, and a linear motion mechanism 10.
The power source 8 includes a motor 8a that generates a rotational torque in response to a command input from a spring efficiency control controller (not shown) for controlling the spring efficiency of each suspension spring 6, and a rotational torque generated by the motor 8a. And a speed reducer 8b that transmits the signal to the rotating linear converter 9.

The rotational linear converter 9 converts the rotational torque amplified by the speed reducer 8b into a linear propulsive force that linearly moves a slider 10a (described later) of the linear motion mechanism 10, and adds the linear torque to the slider 10a.
The linear motion mechanism 10 includes a slider 10a to which one end of the vehicle body side of the suspension spring 6 is attached at one end and the driving force of the rotary linear converter 9 is added to the other end. And a guide 10b that regulates in a direction perpendicular to the vehicle (vehicle width direction in rear view).

  And if the generation | occurrence | production command of rotational torque is output from the spring efficiency control controller, the efficiency variable mechanism 7 will generate rotational torque with the motor 8a according to the instruction | command, Amplify the rotational torque with the reduction gear 8b, The amplified rotational torque is converted into the propulsive force of the slider 10a by the rotary linear converter 9 and applied to the slider 10a, and the slider 10a is moved in the direction perpendicular to the axial direction of the suspension spring 6 by the propulsive force. The vehicle body side end of the spring 6 is moved. Then, the inclination degree of the suspension spring 6 with respect to the vehicle vertical direction changes, and the apparent spring constant (spring efficiency) in the vehicle vertical direction at the wheel position changes. That is, when the inclination degree of the suspension spring 6 increases, the spring efficiency decreases, and when the inclination degree of the suspension spring 6 decreases, the spring efficiency increases.

Thus, in the suspension device of the present embodiment, the spring efficiency of the suspension spring 6 can be changed. Therefore, the spring efficiency at any wheel position (spring constant in the vehicle vertical direction at the wheel position) is reduced, the amount of subsidence (deflection amount) due to its own weight or inertial force is increased, and the vehicle is moved in the direction of the wheel. By tilting, the vehicle attitude can be controlled.
Further, the spring efficiency is changed by moving the vehicle body side end of the suspension spring 6 in a direction orthogonal to the axial direction of the suspension spring 6 that supports the sprung weight of the vehicle. Therefore, for example, the vehicle height at an arbitrary wheel position can be easily controlled and the vehicle posture can be controlled with a small force, compared to a vehicle posture changing by generating a compressive force that compresses the suspension spring 6 in the axial direction. be able to.

<Results of suspension device operation verification>
Next, the results of the operation verification of the suspension device of the present embodiment will be described with reference to the drawings.
In this operation verification, the suspension spring 6 for controlling the spring efficiency and the method for controlling the spring efficiency of the suspension spring 5 are changed for each suspension, and each suspension device (comparative example, Examples 1 and 2) is set to 0 to 1G. While turning (in each turn in increments of 0.025G), the wheel stroke amount sti on the turning inner wheel side, the wheel stroke amount sto on the turning outer wheel side, the fluctuation amount ΔH of the center of gravity height, the lever ratio γi on the turning inner wheel side, the turning outer wheel side The lever ratio γo and the roll angle rollangle were measured.

  In this operation verification, a device that changes the spring efficiency by changing the lever ratio was used. In addition, as a comparative example, a suspension device that does not change the spring efficiency of any suspension spring 6 was used. Further, as Example 1, a suspension device that changes only the spring efficiency of the suspension spring 6 on the turning inner ring side was used. Furthermore, as Example 2, a suspension device that changes the spring efficiency of the suspension spring 6 on the turning inner ring side and the spring efficiency of the suspension spring 6 on the turning outer ring side was used.

As shown in FIG. 3, the sprung weight W is 800 kgf, the tread Tr is 1.5 m, the center of gravity height H is 0.5 m, the inherent spring constant k of the suspension spring 6 is 2 kgf / mm, The variable β used for calculating the proload (β × (W / 2)) of the spring 5 was set to 0.5 [−].
FIG. 4 is a graph showing the measurement results of the comparative example. As shown in FIG. 4, in the comparative example, as the turning G increases, the wheel stroke amount sti on the turning inner wheel side increases in the positive direction (the direction in which the stroke extends), and the wheel stroke amount sto on the turning outer wheel side decreases in the negative direction. By increasing in the (shrinking direction), the roll angle rollangle of the vehicle body 1 is increased.

FIG. 5 shows a case where the spring efficiency of the suspension spring 6 on the turning inner ring side is changed in accordance with the first embodiment, that is, the following equation (1) for not changing the deflection amount (wheel stroke amount) on the turning inner ring side ( It is a graph which shows the measurement result of the case where the lever ratio γi on the turning inner wheel side decreases as the vehicle acceleration / deceleration α (turning G) increases. As shown in FIG. 5, in Example 1, as the turning G increases, the wheel stroke amount sto on the turning outer wheel side increases in the negative direction, but the lever ratio γi on the turning inner wheel side decreases, and the turning inner wheel side increases. The spring efficiency is reduced, the lift (rebound amount) on the inner turning wheel side can be reduced, and the wheel stroke amount sti on the inner turning wheel side becomes 0, so the wheel stroke amount sti on the inner turning wheel side increases in the positive direction. Compared to the comparative example, the roll angle rollangle can be halved. Further, the amount of change ΔH in the center of gravity height is reduced and the center of gravity height H is lower than in the comparative example.
γ _i = (− β + (β ² +4 (1-β) (1- (H / Tr) α)) ^1/2 ) / (2 (1-β)) (1)

  Furthermore, FIG. 6 shows the second embodiment, that is, the turning inner ring side and the turning outer ring side according to the above formula (1) and the following formula (2) for preventing the deflection amount on the turning inner ring side and the deflection amount on the turning outer ring side. When the spring efficiency of the suspension spring 6 is changed (when the vehicle acceleration / deceleration α (turning G) increases, the lever ratio γi on the turning inner wheel side decreases and the lever ratio γo on the turning outer wheel increases) It is a graph which shows the measurement result. As shown in FIG. 6, in Example 2, as the turning G increases, the lever ratio γo on the turning outer wheel side increases, the spring efficiency on the turning outer wheel side increases, and the sinking (bound amount) on the turning outer wheel side increases. Since the wheel stroke amount sto on the turning outer wheel side becomes 0, the roll stroke rollangle can be reduced compared with the comparative example in which the wheel stroke amount on the turning outer wheel side increases in the negative direction. .

Even when the turn G is increased, the wheel stroke amounts sti and sto on the turning inner wheel side and the turning outer wheel side are both 0, so the roll angle rollangle is also 0. Further, for example, in the case of 0.5G turning, the inner wheel side lever ratio γi is 0.88 and the outer wheel side lever ratio γo is 1.11, which can be realized by an efficiency conversion of about 10% of the spring efficiency. Recognize.
γ _o = (− β + (β ² +4 (1-β) (1+ (H / Tr) α)) ^1/2 ) / (2 (1-β)) (2)

<Calculation method of the formulas (1) and (2)>
Next, a description will be given of a calculation method of the above formulas (1) and (2) in order not to change the deflection amount on the turning inner wheel side and the deflection amount on the turning outer wheel side.
First, as shown in FIG. 3, the deflection amount Δz _i on the inner turning wheel side and the deflection amount Δz _o on the outer turning wheel side are expressed by the following equation (3).
Δz _i = W / (2γ _i ² k) × (1−αH / Tr−γ _i β)
Δz _o = W / (2γ _o ² k) × (1 + αH / Tr−γ _o β) (3)
Where αW is the inertial force due to turning. From this equation (3), as the lever ratio .gamma.i, is γo decreases, the amount of deflection Delta] z _i, Delta] z _o is increased, it can be seen that the vehicle height H is reduced.

Further, when the deflection amounts Δz _i and Δz _o on the turning inner wheel side and the turning outer wheel side are not changed during turning, the deflection amounts Δz _i and Δz _o are the same as when α = 0, γ _i , and γ _o = 1. Since it becomes equal to the amount of deflection, the following equation (4) (the above equations (1) and (2)) is derived from the above equation (3).
γ _i = (− β + (β ² +4 (1-β) (1- (H / Tr) α)) ^1/2 ) / (2 (1-β))
γ _o = (− β + (β ² +4 (1-β) (1+ (H / Tr) α)) ^1/2 ) / (2 (1-β)) (4)
The suspension device of the present invention is not limited to the contents of the above embodiment, and can be appropriately changed without departing from the gist of the present invention.

For example, an example of application to a double wishbone type suspension has been shown, but the present invention is not limited to this. For example, as shown in FIG. 7, the present invention may be applied to a push rod type suspension device. Specifically, one end of the push rod 11 is attached to the lower arm 4 and the other end is attached to the suspension spring 6 via the rocker 12, and the vehicle body side end of the suspension spring 6 is provided on the vehicle body side. You may make it attach to.
Moreover, although the example which attaches the variable efficiency mechanism 7 to a vehicle body side avoiding the part which moves with the vertical motion of the wheel 2 was shown, it is not restricted to this. For example, as long as the durability and layout of the mechanism due to the vertical movement of the wheel 2 can be ensured, it may be provided other than on the vehicle body side.

  Furthermore, although the example which uses the motor 8a as a power source for changing spring efficiency was shown, it is not restricted to this. For example, as shown in FIG. 8, the hydraulic pressure of the hydraulic power steering 13 may be used. Specifically, as the slider 10a, a vehicle body side end of the suspension spring 6 is attached to one end and a piston 14 is provided to the other end, and a spring 15 for applying a preload toward the other end is disposed on the one end side. ing. Further, the guide 10b is formed of a cylinder 16 in which the moving direction of the slider 10a extends in a direction perpendicular to the axial direction of the suspension spring 5 and the inside is partitioned by the piston 14, and the cylinder 16 partitioned by the piston 14 is formed. Of these spaces, the space 17 in the direction in which the spring 15 applies preload is communicated with the hydraulic chambers 13L and 13R of the hydraulic power steering 13 (the hydraulic chamber 13L on the left side in the vehicle width direction of the hydraulic power steering 13 is on the left side in the vehicle width direction). The hydraulic chamber 13R on the right side in the vehicle width direction communicates with the space 17 of the efficiency variable mechanism 7 on the right side in the vehicle width direction.

  When the steering handle (not shown) is steered, the hydraulic pressure in the hydraulic chamber on the steering direction side increases, and the hydraulic pressure in the opposite hydraulic chamber decreases, the hydraulic pressure in the space 17 of the efficiency variable mechanism 7 on the steering direction side increases. Then, the hydraulic pressure in the space 17 of the opposite efficiency variable mechanism 7 decreases. Then, a propulsive force toward the one end side of the slider 10a is applied to the piston 14 of the efficiency variable mechanism 7 on the steering direction side, and a propulsive force toward the other end side is applied to the piston 14 of the opposite efficiency variable mechanism 7. Added. Therefore, the spring efficiency is reduced when the slider 10a is moved by the driving force toward the one end side, and the spring efficiency is increased when the slider 10a is moved by the driving force toward the other end side. Vehicle posture control according to the turning state of the vehicle can be realized without adding a special power source only for vehicle posture control.

It is a schematic block diagram which shows one Embodiment of the suspension apparatus of this invention. It is a principal part enlarged view which expands and shows the efficiency variable mechanism of FIG. It is explanatory drawing for demonstrating the specification used for operation | movement verification. It is a graph for demonstrating operation | movement of a comparative example. 6 is a graph for explaining the operation of the first embodiment. 6 is a graph for explaining the operation of the second embodiment. It is explanatory drawing for demonstrating the modification of this invention. It is explanatory drawing for demonstrating the modification of this invention.

Explanation of symbols

1 is a suspension device, 2 is a wheel, 3 is an axle, 4 is a lower arm, 4 is an upper arm, 6 is a suspension spring, 7 is a variable efficiency mechanism, 8 is a power source, 8a is a motor, 8b is a rotating linear converter 9 10 is a linear motion mechanism, 10a is a slider, 10b is a guide, 11 is a push rod, 1 is a rocker, 13 is hydraulic power steering, 14 is a piston, 15 is a spring, 16 is a cylinder, and 17 is a space.

Claims (6)

A suspension device for controlling a vehicle attitude,
A suspension apparatus comprising spring efficiency control means for controlling a vehicle posture by controlling spring efficiency of each spring element supporting a vehicle weight.   The suspension device according to claim 1, wherein the spring efficiency control means reduces the spring efficiency of the spring element on the turning inner ring side when the vehicle is turning.   The suspension device according to claim 1 or 2, wherein the spring efficiency control means increases the spring efficiency of the spring element on the side of the turning outer wheel when the vehicle is turning.   4. The spring efficiency control unit controls the spring efficiency by moving one end of the spring element in a direction perpendicular to the axial direction of the spring element. 5. The suspension device described in 1.   The suspension apparatus according to any one of claims 1 to 3, wherein the spring efficiency control means controls the spring efficiency using a hydraulic pressure of hydraulic power steering. The spring efficiency control means is provided corresponding to each spring element, and includes left and right cylinders communicating with the left and right hydraulic chambers of the hydraulic power steering,
The cylinder reduces the spring efficiency of the corresponding spring element using the hydraulic pressure when the hydraulic pressure of the communicated hydraulic chamber is large, and the spring of the corresponding spring element when the hydraulic pressure of the communicated hydraulic chamber is small 6. The suspension device according to claim 5, wherein the efficiency is increased by using the hydraulic pressure.

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