JPH1191331A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a car height without using a driving source such as a motor and to change a spring constant. SOLUTION: A piston rod 16 of a shock absorber 12 is provided with a through passage 16a. The through passage 16a is communicated with a shock absorber lower chamber 14b. Further a piston part 36a of an upper spring sheet 36 is slidably mounted in a cylinder member 24, to form a liquid chamber 24b. A first electromagnetic valve 40 selectively permits the flow of the oil from the through passage 16a to the accumulator chamber 52a of an accumulator 52, or an oil chamber 24b, and a second electromagnetic valve 42 selectively permits the flow of the fluid from the accumulator chamber 52a or the oil chamber 24b to the through passage 16a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device, and more particularly to a suspension device suitable for realizing a vehicle height and a spring constant according to demand.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No.
As disclosed in No. 6, a suspension device using a fluid pressure cylinder is known. The fluid pressure cylinder includes a cylinder filled with fluid, a piston slidably disposed in the cylinder, and a piston rod connected to the piston and having a fluid passage communicating with the inside of the cylinder. . In the above-mentioned conventional device, the fluid pressure cylinder forms a shock absorber of a suspension device by connecting the cylinder to the wheel side and connecting the piston rod to the vehicle body frame side. Fluid is supplied to or discharged from the fluid pressure cylinder through the fluid passage, so that the relative position between the piston and the cylinder changes, that is, the fluid pressure cylinder expands and contracts. Changes.

[0003] The conventional suspension device described above also
It has a reservoir tank for storing a fluid, and a pressure chamber communicating with both the fluid pressure cylinder and the reservoir tank. In a passage connecting the fluid pressure cylinder and the pressure chamber, a first shut-off valve for switching between opening and closing is provided. Further, a second shutoff valve for switching between opening and closing is provided in a passage connecting the reservoir tank and the pressure chamber. The pressure chamber is provided with a displacement member that is displaced in accordance with a change in the internal pressure. The displacement member constitutes a pump mechanism for pumping fluid from the reservoir tank to the fluid pressure cylinder in accordance with the displacement.

When the vehicle travels, the hydraulic cylinder expands and contracts to absorb the traveling vibration of the vehicle, and accordingly, the internal pressure of the hydraulic cylinder repeatedly increases and decreases. Therefore, when the first shutoff valve is opened, the increase or decrease in the internal pressure of the fluid pressure cylinder is guided to the pressure chamber, and the displacement member reciprocates.
In this case, when the second shut-off valve is closed, the pump mechanism supplies the fluid from the reservoir tank to the hydraulic cylinder, and the hydraulic cylinder expands, so that the vehicle height increases. On the other hand, when both the first shutoff valve and the second shutoff valve are opened, the fluid pressure cylinder communicates with the reservoir tank via the pressure chamber. Therefore, when the fluid is discharged from the fluid pressure cylinder to the reservoir, the fluid pressure cylinder contracts, and the vehicle height decreases.

As described above, the above-mentioned conventional suspension device can operate a pump mechanism for pumping a fluid to a fluid pressure pump by utilizing a pressure change caused by running vibration of a vehicle. That is, according to the conventional suspension device, the vehicle height can be adjusted without using a driving device such as a motor by switching between opening and closing the first and second shutoff valves.

[0006]

By the way, in a vehicle suspension system, a coil spring is provided in parallel with a shock absorber, and the coil spring absorbs vertical vibration of wheels. When the spring constant of the coil spring increases, the running stability of the vehicle improves,
When the spring constant decreases, the riding comfort of the vehicle improves. Therefore, in order to ensure both excellent running stability and good riding comfort, it is desirable that the spring constant of the suspension device can be made variable according to the running state of the vehicle. However, in the conventional suspension device described above, no consideration is given to changing the spring constant.

[0007] The present invention has been made in view of the above points, and a suspension device capable of adjusting a vehicle height without using a driving device such as a motor and changing a spring constant. The purpose is to provide.

[0008]

The above object is achieved by the present invention.
As described in the above, a shock absorber including a fluid-filled absorber cylinder, a piston rod that is inserted into and retractable from the absorber cylinder, and a shock absorber that is provided in parallel with the shock absorber, and is provided in accordance with the expansion and contraction of the shock absorber. An accumulator for compensating for a volume change in the absorber cylinder due to the advance and retreat of the piston rod by flowing the fluid between the coil spring that expands and contracts and the absorber cylinder, a cylinder, and a slide in the cylinder. Movably provided,
A piston that expands and contracts the coil spring in accordance with the displacement; and a liquid chamber defined by the cylinder and the piston. The liquid chamber and the absorber cylinder transfer the fluid in accordance with the advance and retreat of the piston rod. And a first switching means for selectively permitting a one-way fluid flow from the absorber cylinder to either the accumulator or the liquid chamber by displacing the piston. And a second switching means for selectively permitting a one-way fluid flow from one of the liquid chamber and the accumulator to the absorber cylinder. .

In the present invention, the first switching means selectively allows a one-way fluid flow from the absorber cylinder to either the accumulator or the liquid chamber. The second switching means selectively allows the flow of the fluid in one direction from one of the liquid chamber and the accumulator to the absorber cylinder. When the flow of the fluid from the absorber cylinder to the accumulator is permitted by the first switching means and the flow of the fluid from the accumulator to the absorber cylinder is permitted by the second switching means, the piston rod moves forward and backward. The change in volume in the absorber cylinder is compensated by the transfer of fluid between the absorber cylinder and the accumulator. In this case, no displacement occurs in the piston of the cylinder mechanism, so that the coil spring expands and contracts by the same amount as the expansion and contraction of the shock absorber.

On the other hand, the flow of the fluid from the absorber cylinder to the liquid chamber is allowed by the first switching means, and
In a state where the flow of the fluid from the liquid chamber toward the absorber cylinder is allowed by the second switching means, the volume change in the absorber cylinder due to the advance and retreat of the piston rod causes the fluid to flow between the absorber cylinder and the liquid chamber of the cylinder mechanism. Is compensated by being exchanged between them. In this case, the piston of the cylinder mechanism is displaced in accordance with the transfer of the fluid. The piston displaces the coil spring according to the displacement. Therefore, expansion and contraction of both the expansion and contraction corresponding to the amount of expansion and contraction of the shock absorber and the expansion and contraction corresponding to the amount of displacement of the piston of the cylinder mechanism occur in the coil spring. For this reason, the elastic force generated by the coil spring for a given stroke of the shock absorber changes, and the spring constant of the suspension device changes.

[0011] Further, the flow of the fluid from the absorber cylinder to the liquid chamber is permitted by the first switching means, and
In a state in which the flow of the fluid from the accumulator to the absorber cylinder is permitted by the second switching means, the decrease in the volume in the absorber cylinder due to the inward movement of the piston rod is compensated by the fluid flowing from the absorber cylinder into the liquid chamber. The increase in the volume in the absorber cylinder due to the retreating movement of the piston rod is compensated by the fluid flowing from the accumulator into the absorber cylinder. In such a situation, when the piston rod repeatedly moves forward and backward with the vertical vibration of the vehicle, the amount of fluid in the liquid chamber increases, and the piston of the cylinder mechanism is displaced in a direction corresponding to the increase in the capacity of the liquid chamber. In this case, the vehicle height rises or falls according to the displacement direction of the piston.

On the other hand, in a state where the flow of the fluid from the absorber cylinder to the accumulator is permitted by the first switching means and the flow of the fluid from the liquid chamber to the absorber cylinder is permitted by the second switching means, The decrease in the volume in the absorber cylinder due to the rod entering movement is compensated by the fluid flowing into the accumulator from the absorber cylinder. Is compensated by flowing into Under such circumstances, when the piston rod repeatedly moves forward and backward with the vertical vibration of the vehicle, the amount of fluid in the liquid chamber decreases, and the piston of the cylinder mechanism is displaced in a direction corresponding to the decrease in the capacity of the liquid chamber. In this case, the vehicle height rises or falls according to the displacement direction of the piston.

[0013]

FIG. 1 shows a system configuration diagram of one wheel of a suspension device 10 according to an embodiment of the present invention. The suspension device 10 of the present embodiment includes a shock absorber 12. The shock absorber 12 includes an absorber cylinder 14 and a piston rod 16. The piston rod 16 is connected to the absorber cylinder 14
Is penetrated through the rod guide 15 provided at the upper end portion of the absorber cylinder 14 so as to be able to advance and retreat. A piston 18 is fixed to an end of the piston rod 16 on the side accommodated in the absorber cylinder 14. The piston 18 is provided in a liquid-tight and slidable manner with respect to the inner peripheral surface of the absorber cylinder 14. The interior space of the absorber cylinder 14 is partitioned by a piston 18 into an upper absorber chamber 14a above the piston 18 and a lower absorber lower chamber 14b below. Piston 1
8 is provided with a damping valve 18a. When the piston 18 slides in the absorber cylinder 14, the damping valve 18a allows oil to flow between the upper absorber chamber 14a and the lower absorber chamber 14b, and the flow resistance reduces the sliding speed of the piston 18. It is configured to generate a damping force of an appropriate magnitude. That is, in the present embodiment, the shock absorber 12 is a monotube type shock absorber composed of a single cylinder.

A lower spring seat 20 is fixed to the outer peripheral surface of the absorber cylinder 14. The lower end of the absorber cylinder 14 is connected to a trailing arm 21 which is supported to be able to swing up and down with respect to the vehicle body. Further, a wheel 22 is rotatably supported by the trailing arm 21. The piston rod 16 has a through passage 16a penetrating in the axial direction. The flow path 23 is connected to the upper end of the through passage 16a. A cylinder member 24 is fixed to the outer peripheral surface of the upper end of the piston rod 16. The cylinder member 24 is fitted to a mount rubber 26, and the mount rubber 26 is fixed to the body frame 32 by a bracket 28 and a bolt 30.

The cylinder member 24 has an annular cylinder space 24a having an open lower end surface. A flow path 34 is connected to the upper end surface of the cylinder space 24a. Also,
The piston portion 36a of the upper spring seat 36 is disposed inside the cylinder space 24a so as to be liquid-tight and slidable. The piston part 36a is an annular part formed on the upper part of the upper spring seat 36. A liquid chamber 24b is defined between the upper bottom surface of the cylinder space 24a and the upper end surface of the piston portion 36a. Therefore, the flow path 34
Communicates with the liquid chamber 24b. A coil spring 38 is arranged between the lower spring seat 20 and the upper spring seat 36 so as to surround the shock absorber 12.

The suspension device of this embodiment is
A first solenoid valve 40 and a second solenoid valve 42 are provided. First
The solenoid valve 40 and the second solenoid valve 42 have four ports 40a to 40d and 42a to 42d, respectively.
The first solenoid valve 40 and the second solenoid valve 42 are not energized to their respective solenoids (hereinafter referred to as non-energized states).
Then, the ports 40a, 42a and the ports 40c, 42c are electrically connected, and the ports 40b, 42b and
d, 42d. On the other hand, when the solenoids of the first solenoid valve 40 and the second solenoid valve 42 are energized (hereinafter referred to as energized states), the ports 40a,
2a and the ports 40c, 42c,
The ports 40b and 42b are electrically connected to the ports 40d and 42d.

The ports 40a and 40b of the first solenoid valve 40
Communicates with the flow path 23 via a common first check valve 44. The first check valve 44 is connected to the first solenoid valve 4 from the flow path 23 side.
It is configured to allow only the flow of the fluid toward the zero side. The ports 42a and 42 of the second solenoid valve 42
b communicates with the flow path 23 via a common second check valve 46. The second check valve 46 is configured to allow only the flow of the fluid from the second solenoid valve 42 side to the flow path 23 side.

The port 40c of the first solenoid valve 40 and the port 42c of the second solenoid valve 42 both communicate with the flow path 34. The port 40 d of the first solenoid valve 40 and the port 42 d of the second solenoid valve 42 both communicate with the accumulator 52. The accumulator 52 is provided with a free piston 54 which is disposed in a liquid-tight and slidable manner therein. The internal space of the accumulator 52 is separated from the free piston 54 by a free piston 54 as shown in FIG.
It is partitioned into an accumulator chamber 52a on the middle left and an air chamber 52b on the right in FIG. The ports 40 d and 42 d of the first solenoid valve 40 and the second solenoid valve 42 are connected to the accumulator chamber 5.
2a side.

The above-described absorber upper chamber 14a, absorber lower chamber 14b, through passage 16a, flow paths 23 and 34,
The liquid chamber 24b and the accumulator chamber 52a are filled with oil. The air chamber 52b is filled with an inert gas such as nitrogen gas. The above-described first solenoid valve 40 and second solenoid valve 42 are controlled by an electronic control unit (hereinafter, referred to as ECU) 56. ECU
A command device 58 and a vehicle height sensor 60 are connected to 56. The command device 58 is a device that outputs a signal that is selected by the driver or set according to the running state of the vehicle, according to the vehicle height and the spring constant. The vehicle height sensor 60 is a sensor that detects the vehicle height based on the relative displacement between the absorber cylinder 14 of the shock absorber 12 and the body frame 32.

Next, the operation of the suspension device of this embodiment will be described. First, an operation in a case where both the first solenoid valve 40 and the second solenoid valve 42 are energized (hereinafter, referred to as a first state) will be described. In the first state, the flow of oil from the flow path 23 to the accumulator chamber 52a via the first check valve 44 and the ports 40b and 40d of the first solenoid valve 40 is allowed, and the accumulator chamber 52a Through the ports 42 d and 42 b of the second solenoid valve 42 and the second check valve 46
Oil flow toward 3 is allowed.

In this state, when the piston rod 16 retreats from the absorber cylinder 14 (that is, when the suspension device 10 rebounds), an increase in the volume inside the absorber cylinder 14 due to the retraction movement of the piston rod 16 causes a change in the reservoir chamber. The oil in 52a is supplied to the second solenoid valve 42, the second check valve 46, the flow path 23, and the through passage 1.
It is compensated by flowing into the lower absorber chamber 14b via 6a. In this case, as the oil amount in the reservoir chamber 52a decreases, the free piston 50 moves toward the reservoir chamber 52a. The increase in the volume of the lower absorber chamber 14b due to the retreating movement of the piston rod 16 and the reduction in the volume of the upper absorber chamber 14a are caused by the upper absorber 14
The oil in a is compensated by flowing into the lower absorber chamber 14b via the damping valve 18a. In this case, due to the viscous resistance when the oil flows through the damping valve 18a, a damping force against the retreating movement of the piston rod 16 is generated.

On the other hand, when the piston rod 16 moves into the absorber cylinder 14 (ie, when the suspension device 10 bounces), the piston rod 1
The oil inside the absorber lower chamber 14b is reduced by the through passage 16a, the flow path 23, the first check valve 44, and the first solenoid valve 4 due to the decrease in the volume inside the absorber cylinder 14 due to the approach movement of the cylinder 6.
It is compensated by flowing into the reservoir chamber 52a via 0. In this case, the free piston 50 moves toward the air chamber 52b as the amount of oil in the reservoir chamber 52a increases. Further, the volume of the lower absorber chamber 14b decreases due to the approach movement of the piston rod 16, and the upper absorber chamber 1
The increase in the volume of 4a is compensated by the oil in the lower absorber chamber 14b flowing into the upper absorber chamber 14a via the damping valve 18a. In this case, due to the viscous resistance when the oil flows through the damping valve 18a, a damping force against the inward movement of the piston rod 16 is generated.

As described above, in the first state, as the piston rod 16 advances and retreats, the absorber lower chamber 14
Oil is exchanged between b and the accumulator chamber 52a, and the amount of oil in the liquid chamber 24b of the cylinder member 24 does not change. Therefore, the upper spring seat 36
No displacement occurs in the coil spring 38, and the amount of advance and retreat of the piston rod 16, ie, the shock absorber 1
The expansion and contraction deformation of the magnitude equal to the expansion and contraction amount of 2 occurs.

That is, in the energized state, since the coil spring 38 undergoes expansion and contraction equal to the expansion and contraction amount x of the shock absorber 12, the expansion and contraction amount E ₁ of the coil spring 38 becomes E ₁ = x (1). Here, E ₁ and x represent the contraction direction as positive.

On the other hand, the first solenoid valve 40 and the second solenoid valve 42
Are in a non-energized state (hereinafter, referred to as a second state), the flow path 34 passes through the first check valve 44 and the ports 40 a and 40 c of the first solenoid valve 40. The oil flow from the flow path 34 to the flow path 23 via the ports 42c and 42a of the second solenoid valve 42 and the second check valve 46 is permitted.

When the piston rod 16 retreats from the absorber cylinder 14 in such a state, the volume increase in the absorber cylinder 14 due to the retreat movement is caused by the liquid chamber 24.
b in the flow path 34, the second solenoid valve 42, and the second
It is compensated by flowing into the lower absorber chamber 14b via the check valve 46, the flow path 23, and the through passage 16a. In this case, the piston portion 36a of the upper spring seat 36 is displaced upward in accordance with the decrease in the amount of oil in the liquid chamber 24b. Therefore, in the coil spring 38, in addition to the extension deformation caused by the retreating movement of the piston rod 16, the extension deformation caused by the upward displacement of the upper spring seat 36 occurs.

On the other hand, when the piston rod 18 moves into the absorber cylinder 14, the decrease in the volume in the absorber cylinder 14 caused by the movement of the piston rod 18 is caused by the lower absorber 1
The oil in 4b is compensated by flowing into the liquid chamber 24b via the through passage 16a, the flow path 23, the first check valve 44, the first solenoid valve 40, and the flow path 34. in this case,
The piston portion 36a of the upper spring seat 36 moves downward in accordance with an increase in the amount of oil in the liquid chamber 24b.
Therefore, in the coil spring 38, in addition to the contraction deformation caused by the inward movement of the piston rod 16, the contraction deformation caused by the downward movement of the upper spring seat 36 occurs.

That is, the downward displacement amount y of the upper spring seat 36 in the second state is as follows, where S _{1 is} the sectional area of the piston rod 18 and S ₂ is the sectional area of the cylinder space 24 a of the cylinder member 24. (S ₁ / S ₂ ) · x (2) In the second state, the coil spring 38
The expansion and contraction of the shock absorber 12 equal to the expansion and contraction amount x and the expansion and contraction of the upper spring seat 36 equal to the displacement amount y occur. Therefore, the expansion / contraction amount E ₂ of the coil spring 38 is expressed as follows: E ₂ = x + y = (1 + S ₁ / S ₂ ) · x (3)

From the above equations (1) and (3), in the second state
E of the coil spring 24 _TwoIs in the first state
(1 + S)₁/ S_Two) Double the size
You can see that. The amount of expansion and contraction of the coil spring 24 increases
Then, the coil spring 24 emits in proportion to it.
The elastic force also increases. Therefore, the suspension of the present embodiment
According to the device, switching between the first state and the second state
As a result, a certain stroke is
The magnitude of the spring force acting on the vehicle body when it occurs,
In addition, the spring constant of the suspension device is set to 1: (1 + S₁/
S_Two). And Siri
Sectional area S of the solder space 24a_TwoOf the piston rod 18
Area S₁, The change in the spring constant
The ratio can be set large.

Next, when the first solenoid valve 40 is de-energized and the second solenoid valve 42 is energized (hereinafter, referred to as a third state), the flow path 23 Ports 40a and 40 of the first check valve 44 and the first solenoid valve 40
c, the flow of oil toward the flow path 34 is permitted, and the second solenoid valve 4
The flow of oil toward the flow path 23 via the second ports 42d and 42b and the second check valve 46 is allowed.

Therefore, when the piston rod 16 moves into the absorber cylinder 14 in the third state, the volume reduction in the absorber cylinder 14 is caused by the oil in the absorber lower chamber 14b passing through the through passage 16a, the flow path 23,
The compensation is made by flowing into the liquid chamber 24b via the first check valve 44, the first solenoid valve 40, and the flow path 34. When the piston rod 16 retreats from the absorber cylinder 14, the volume in the absorber cylinder 14 increases due to the oil in the accumulator chamber 52a flowing through the second solenoid valve 42, the second check valve 46, the flow path 23, and the Passage 16a
Is compensated by flowing into the lower absorber chamber 14b via

Under these circumstances, when the piston rod 16 repeats the forward and backward movements in response to the running vibration of the vehicle, the oil in the accumulator chamber 52a flows into the lower absorber chamber 14b during the backward movement, and the lower absorber 1 during the approach movement.
The oil in 4b flows into the oil chamber 24b. That is, as the piston rod 16 advances and retreats, the oil in the accumulator chamber 52a repeatedly flows into the oil chamber 24b, so that the amount of oil in the oil chamber 24b increases. Oil chamber 24b
When the amount of oil in the inside increases, the piston portion 36a of the upper spring seat 36 is displaced downward in proportion thereto,
The body frame 32 is lifted by a height corresponding to the displacement of the piston portion 36a. in this way,
According to the present embodiment, by realizing the third state when the vehicle travels, it is possible to increase the vehicle height using the traveling vibration of the vehicle.

On the other hand, the first solenoid valve 40 is turned on,
When the second solenoid valve 42 is in a non-energized state (hereinafter, referred to as a fourth state), the first flow from the flow path 23 is stopped.
Check valve 44 and ports 40b, 40d of first solenoid valve 40
Is allowed to flow toward the accumulator chamber 52a through the flow path 34, and the oil flowing from the flow path 34 toward the flow path 23 through the ports 42c and 42a of the second solenoid valve 42 and the second check valve 46. Flow is allowed.

Therefore, when the piston rod 16 moves into the absorber cylinder 14 in the fourth state, the volume in the absorber cylinder 14 decreases due to the oil in the absorber lower chamber 14b passing through the through passage 16a, the flow path 23,
The compensation is made by flowing into the accumulator chamber 52a via the first check valve 44 and the first solenoid valve 40. When the piston rod 16 retreats from the absorber cylinder 14, the volume in the absorber cylinder 14 increases due to the oil in the liquid chamber 24 b flowing through the flow path 34 and the second solenoid valve 4.
2. It is compensated by flowing into the lower absorber chamber 14b via the second check valve 46, the flow path 23, and the through passage 16a.

In such a situation, when the piston rod 16 repeats the forward and backward movements in accordance with the running vibration of the vehicle, the oil in the oil chamber 24b flows into the lower absorber chamber 14b at the time of the backward movement, and the absorber lower chamber 14b at the time of the approach movement. The oil inside flows into the accumulator chamber 52a. That is, as the piston rod 16 moves forward and backward, the oil in the oil chamber 24b repeatedly flows out to the accumulator accumulator chamber 52a, so that the amount of oil in the oil chamber 24b decreases. When the amount of oil in the oil chamber 24b decreases, the piston portion 36a of the upper spring seat 36 is displaced upward in proportion thereto, and the height of the body frame 32 is reduced by an amount corresponding to the displacement amount of the piston portion 36a. Becomes
As described above, according to the present embodiment, by realizing the fourth state when the vehicle travels, the vehicle height can be reduced by using the traveling vibration of the vehicle. That is, according to the suspension device 10 of the present embodiment, in the third or fourth state, the vehicle height can be raised or lowered using the vibration energy of the vehicle.

FIG. 2 shows the first solenoid valve 40 and the second
The table summarizes the relationship between the energized / deenergized state of the solenoid valve 42 and the operation of the suspension device. As described above, in the present embodiment, the first solenoid valve 40 and the second solenoid valve 42
By forming the first state in which both are energized, a low spring constant can be realized, and the second state in which both the first solenoid valve 40 and the second solenoid valve 42 are in the non-energized state. By forming the state described above, a high spring constant can be realized. Therefore, by forming the first state under the condition where the high spring constant is commanded by the command device 58 and the second state under the condition where the low spring constant is commanded, the spring corresponding to the command is formed. Constants can be realized. That is, according to the present embodiment, by realizing an appropriate spring constant according to the driver's request or the running condition of the vehicle, it is possible to achieve both good riding comfort of the vehicle and excellent steering stability. .

Further, in this embodiment, the first solenoid valve 4
0 is a non-energized state and the third solenoid valve 42 is an energized state.
The vehicle height can be increased by forming the state described above, the first solenoid valve 40 is energized, and the second solenoid valve 42
The vehicle height can be reduced by forming a fourth state in which the vehicle is not energized. On the other hand, in the first state, oil is not transferred to and from the liquid chamber 24b. In the second state, oil is supplied to the liquid chamber 24b and the lower absorber chamber 14b in accordance with the reciprocation of the piston rod 16.
Is bidirectionally transmitted and received between the liquid chamber 24b and the average oil amount in the liquid chamber 24b does not change. That is, the vehicle height does not change in the first and second states. Therefore, when the vehicle height detected by the vehicle height sensor 60 is lower than the command value output from the command device 58, the vehicle height is raised by forming the third state, and the vehicle height is higher than the command value. In such a case, the vehicle height is reduced by forming the fourth state,
Further, when the vehicle height is equal to the required value, the first state or the second state is formed in accordance with the height of the commanded spring constant, so that the driver's request or the traveling state of the vehicle is established. Vehicle height can be realized according to the vehicle height.

FIG. 3 is a block diagram of the ECU 56 for realizing the above functions.
5 is a flowchart of an example of a routine executed by the user. The routine shown in FIG. 3 is a regular interruption routine executed at predetermined time intervals. When the routine shown in FIG. 3 is started, first, at step 100, the command value H ₀ of the vehicle height H output from the command device 58 is read, and then, at step 102, the average vehicle height H _SM over a predetermined period is read. Is read. The average vehicle height H _SM is a value obtained by averaging the output signal of the vehicle height sensor 60 over a predetermined period. When the processing of step 102 is completed,
Step 104 is executed.

In step 104, it is determined whether or not the average vehicle height H _SM is equal to or less than a value obtained by subtracting a predetermined value α from the command value H ₀ . As a result, if H _SM ≦ H ₀ −α, it is determined that the average vehicle height H _SM is lower than the command value H ₀ . In this case, next, in step 106, a process of setting the first solenoid valve 40 to the non-energized state and the second solenoid valve 42 to the energized state is executed, and then the current routine is ended. On the other hand, if it is determined in step 104 that H _SM > H ₀ -α, the process of step 108 is executed.

In step 108, the average vehicle height H_SMIs a directive
Value H₀Is greater than or equal to a predetermined value α
It is. As a result, H_SM≧ H₀If + α, average car
High H _SMIs the command value H₀Is judged to be high. This place
Then, in step 110, the first solenoid valve 40 is passed.
The process of setting the second solenoid valve 42 to the non-energized state is executed.
After this, the current routine ends. On the other hand,
In step 108, H _SM, H₀-If α, command
Average vehicle height H_SMIt is determined that
Then, the process of step 112 is executed.

In step 112, it is determined whether a lower spring constant than the command device 58 has been commanded. As a result, if a low spring constant is commanded, then at step 114, the first solenoid valve 40 and the second solenoid valve 4
After the processing for turning on both the power supply terminals 2 is performed, the current routine is terminated. On the other hand, in step 112,
If the low spring constant has not been commanded (that is, a high spring constant has been commanded), then, in step 116, a process of turning off both the first solenoid valve 40 and the second solenoid valve 42 is performed. After this, the current routine ends.

As described above, according to the suspension device 10 of this embodiment, both the vehicle height and the spring constant of the suspension device can be changed. Therefore, according to the suspension device 10, it is possible to realize an appropriate vehicle height and spring constant according to the driver's request or the running state of the vehicle. In this embodiment, the adjustment of the vehicle height is performed using the energy of the vertical vibration of the vehicle, and no drive source such as a motor is used. Therefore, according to the suspension device of the present embodiment, the advantage that the cost is lower than that of a system that adjusts the vehicle height using a motor or the like can be obtained.

In the above embodiment, the piston portion 36a of the upper spring seat 36 corresponds to the piston of the cylinder mechanism described in the claims, the cylinder member 24 corresponds to the cylinder of the cylinder mechanism described in the claims, and the liquid chamber 24b corresponds to the cylinder of the cylinder mechanism described in the claims. The first solenoid valve 4 is provided in the liquid chamber of the cylinder mechanism described in the claims.
The zero and first check valves 44 correspond to first switching means described in claims, and the second solenoid valve 42 and the second check valve 46 correspond to second switching means described in claims. I have.

[0044]

As described above, according to the present invention, the vehicle height can be changed without providing a driving source such as a motor, and the spring constant of the suspension device can be changed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a suspension device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between energized / deenergized states of a first electromagnetic valve and a second electromagnetic valve and an operation state of a suspension device.

FIG. 3 is a flowchart of a routine executed by an ECU in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Suspension device 12 Shock absorber 24 Cylinder member 24b Liquid chamber 36 Upper spring seat 36a Piston part 38 Coil spring 40 First solenoid valve 42 Second solenoid valve 44 First check valve 46 Second check valve 52 Accumulator

Claims (1)

[Claims] 1. A shock absorber having a fluid-filled absorber cylinder, a piston rod inserted into and retractable from the absorber cylinder, and a shock absorber provided in parallel with the shock absorber and adapted to expand and contract the shock absorber. A coil spring that expands and contracts; an accumulator that circulates the fluid between the absorber cylinder to compensate for a change in volume in the absorber cylinder caused by the reciprocation of the piston rod; a cylinder; Movably provided, comprising a piston that expands and contracts the coil spring in accordance with the displacement thereof, and a liquid chamber defined by the cylinder and the piston, wherein the fluid is moved in accordance with the reciprocation of the piston rod. By flowing between the liquid chamber and the absorber cylinder, A cylinder mechanism for displacing the piston; first switching means for selectively allowing a one-way fluid flow from the absorber cylinder to one of the accumulator and the liquid chamber; and the liquid chamber or the accumulator. And a second switching means for selectively allowing one-way fluid flow from any one of the above to the absorber cylinder.