JP2001341513A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control an attitude by the expansion/contraction operation of a shock absorber at a low pressure and to maintain the controlled attitude even after the elimination of driving force. SOLUTION: A spring seat 5 for seating the lower end of a suspension spring 2 wound around a shock absorber 1 is slidably fitted to an unsprung member 6 fixedly provided at the outer periphery of a shock absorber body 3, and supported to a lower end flange part 6b (a body 3) of the unsprung member 6 through a first coil spring 7 and a first expansion/contraction liquid chamber 8 in a direction opposed to the spring force of the suspension spring 2. The interior of the body 3 and the chamber 8 are communicated through a hole 52, and the interior of the body 3 is communicated with a second expansion/ contraction liquid chamber 26 of an oil pressure generating mechanism 21 through a hollow hole 4b of a piston rod 4. A second coil spring 31 is stretched in the chamber 26. When an external screw member 28 is rotated by a motor 27, the chamber 26 is expanded/contracted through an internal screw member 29 to change the volume of the chamber 8 in an opposite phase, and a body attitude can be controlled by the height change of a car through the displacement of the spring seat 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension apparatus for suspending wheels of a vehicle on a vehicle body, and more particularly to a suspension apparatus capable of controlling the attitude of the vehicle body during acceleration / deceleration or turning. is there.

[0002]

2. Description of the Related Art As a suspension device capable of controlling the posture of a vehicle body, a conventional suspension device is disclosed, for example, in Japanese Utility Model Laid-Open No. 5-320015.
The following are described in Japanese Unexamined Patent Publication (Kokai) No. H10-260926.
That is, a wheel is attached to the tubular body of the shock absorber, and a piston rod of the shock absorber that is detachably protruded from the upper end of the tubular body is attached to the vehicle body, and is passed through the tubular body of the shock absorber to generate a hydraulic pressure generating mechanism. Is provided.

The hydraulic pressure generating mechanism is constituted by a piston / cylinder device, and the static pressure in the cylindrical body of the shock absorber is changed by flowing liquid into and out of the cylindrical body of the shock absorber by the relative stroke of the cylinder and the piston. Thus, the reaction force of the piston rod of the shock absorber can be controlled to control the posture of the vehicle body.

[0004]

By the way, in the conventional suspension apparatus described above, when the stroke of the piston / cylinder apparatus is generated, the rotational force of the motor is converted into a linear force by a rack-and-pinion mechanism. Since the stroke is made relatively to the cylinder, the following problem arises. That is, since the rack and pinion mechanism that converts the rotational force of the motor into a linear force is a reversible mechanism, the internal pressure corresponding to the wheel load that is constantly generated in the piston / cylinder device is reversely input to the motor. When the rotational force of the motor is no longer generated, the extension force generated in the piston / cylinder device due to the internal pressure cannot be received by the motor, and the controlled vehicle body posture cannot be maintained.

Therefore, in the conventional suspension device, the piston / cylinder device is extended by the internal pressure so that the motor is not driven in reverse by the internal pressure corresponding to the wheel load constantly generated in the piston / cylinder device. The motor had to be constantly energized except during attitude control so that a rotational force consistent with the force was constantly generated. Therefore, the conventional suspension device requires the driving force of the motor even during the posture control, and the motor must generate the rotational force to support all of the wheel loads, so that the energy loss is prevented from being increased. Did not.

Further, in the conventional suspension device, all the wheel loads must be supported by the internal pressure of the piston / cylinder device, and the diameter of the piston / cylinder device cannot be so large due to its installation space. However, the internal pressure of the piston / cylinder device cannot be considerably increased. For this reason, there is a risk that the conventional suspension device may leak liquid, and if the sealing accuracy is increased in order to prevent the liquid leakage, the friction of the seal portion is increased and the smooth operation is impaired. I am concerned.

In view of the latter problem, the first aspect of the present invention is capable of reducing the generated internal pressure by eliminating the need for the hydraulic pressure generating mechanism to support all the wheel loads as in the prior art. It is an object of the present invention to prevent the problem of liquid leakage and the latter problem of increased friction of the seal portion from occurring, and to reduce the driving force of the hydraulic pressure generating mechanism.

[0008] A second aspect of the present invention is to realize a unique configuration for the first aspect in a compact manner.

A third aspect of the present invention is directed to a compact configuration according to the second aspect of the present invention, in which the risk of liquid leakage is further reduced.

A fourth aspect of the present invention is directed to a configuration of the second or third aspect of the present invention in which the risk of liquid leakage is further reduced.

According to a fifth aspect of the present invention, in consideration of the former problem, it is possible to maintain a control attitude even when an actuator for driving a hydraulic pressure generating mechanism is inactive while attitude control is not being performed. Accordingly, an object of the present invention is to solve the former problem that the energy loss becomes large.

A sixth object of the present invention is to provide a hydraulic pressure generating mechanism having a simple configuration and a configuration in which there is no fear of liquid leakage.

A seventh object of the present invention is to further reduce the driving force of the hydraulic pressure generating mechanism.

An eighth aspect of the present invention is directed to a compact configuration for reducing the driving force of the hydraulic pressure generating mechanism as in the seventh aspect.

According to a ninth aspect of the present invention, since the hydraulic pressure generating mechanism is normally mounted on the vehicle body side, the hydraulic pressure generating mechanism can be connected to a piston rod having a better vibration environment than the wheel side. It is an object of the present invention to improve durability at a connection portion of a mechanism and to enable a hydraulic pressure generating mechanism to be installed in a good environment such as an engine room.

[0016]

SUMMARY OF THE INVENTION For the above purpose, the first
The suspension device according to the present invention is a suspension device in which a coil type suspension spring is fitted to a shock absorber and mounted between a cylindrical body and a piston rod of the shock absorber. Is fitted to the outer periphery of the cylindrical body so as to be axially displaceable, and the spring seat is moved in a direction opposite to the spring force of the suspension spring via the first elastic means and the first expansion / contraction liquid chamber. The spring seat is displaced in the axial direction of the tubular body by the inflow and outflow of the liquid into and from the first expansion / contraction liquid chamber, and the relative stroke position between the tubular body and the piston rod of the shock absorber is changed. It is characterized by being made possible.

In the suspension device according to the second invention, in the first invention, the first expansion / contraction liquid chamber is an annular chamber surrounding the cylindrical main body, and the first elastic means is housed in the annular chamber. It is characterized by comprising a coil spring.

The suspension device according to a third invention is the suspension device according to the second invention, wherein an outer peripheral wall of the annular chamber is constituted by a bellows, and one end of the bellows is attached to the spring seat and the other end is attached to the outer periphery of the cylindrical main body. It is characterized by being connected under liquid-tight sealing.

A suspension device according to a fourth invention is the suspension device according to the second invention or the third invention, wherein an inner peripheral wall of the annular chamber is constituted by a cylindrical diaphragm, one end of the cylindrical diaphragm is connected to the spring seat, and the other end is connected to the spring seat. It is characterized by being connected to the outer periphery of the cylindrical body under liquid-tight sealing.

A suspension device according to a fifth aspect of the present invention is the suspension device according to any one of the first to fourth aspects, further comprising a second expanding / contracting liquid chamber for flowing liquid into and out of the first expanding / contracting liquid chamber. The second expansion / contraction liquid chamber is configured to be expanded / contracted by an irreversible screw mechanism.

The suspension device according to a sixth aspect of the present invention is the suspension device according to the fifth aspect, wherein the second expansion / contraction liquid chamber is provided with inner and outer bellows,
A second expanding / contracting liquid chamber is formed by forming an annular chamber defined by end covers respectively closing both ends of the annular space between the inner and outer bellows, and moving the end covers closer to and away from each other by the irreversible screw mechanism. Are configured to expand and contract.

A suspension device according to a seventh aspect of the present invention is the suspension device according to the fifth or sixth aspect, further comprising a second elastic means for urging the second expansion / contraction liquid chamber in a contraction direction.

The suspension device according to an eighth aspect of the present invention is the suspension device according to the seventh aspect, wherein the second elastic means is constituted by a coil spring disposed in the second expansion / contraction liquid chamber.

A suspension device according to a ninth aspect of the present invention is the suspension device according to any one of the fifth to eighth aspects, wherein the second expansion / contraction liquid chamber communicates with the inside of the cylindrical main body through the hollow hole of the piston rod. The inside of the cylindrical main body is communicated with the first expansion / contraction liquid chamber.

[0025]

The suspension device has a cushioning function by means of a coil suspension spring mounted between the cylindrical body of the shock absorber and the piston rod. By the way, in the first invention, when the relative stroke position between the cylindrical body of the shock absorber and the piston rod can be changed for the purpose of controlling the posture of the vehicle body, the end of the suspension spring close to the cylindrical body is used. The seating spring seat is fitted to the outer periphery of the cylindrical body so as to be axially displaceable, and the first elastic means and the first elastic means are arranged in a direction facing the spring force of the suspension spring.
The spring seat is supported on the cylindrical body via the expansion / contraction liquid chamber, and the spring seat is displaced in the axial direction of the cylindrical body by the inflow / outflow of the liquid into / from the first expansion / contraction liquid chamber, thereby causing the relative movement between the cylindrical body and the piston rod. Because the stroke position can be changed, the first
The hydraulic pressure generating mechanism for allowing the liquid to flow into and out of the expansion / contraction liquid chamber to allow the relative stroke position between the cylindrical body and the piston rod to be changed is no longer necessary to support all the wheel loads as in the related art. The supporting load is reduced by the elastic force of one elastic means. For this reason, in the first invention, it is possible to reduce the internal pressure generated by the hydraulic pressure generating mechanism, and to solve the problem of liquid leakage and the problem of increased friction of the seal portion which have occurred in the conventional device as described above. it can. Moreover, in the first invention, since the internal pressure generated by the hydraulic pressure generating mechanism is low, the driving force of the hydraulic pressure generating mechanism may be small, and the energy consumption for the driving force may be reduced.

In the second invention, the first expansion / contraction liquid chamber is an annular chamber surrounding the cylindrical body, and the first elastic means is constituted by a coil spring housed in the annular chamber. The operation and effect of the first invention can be realized with a compact configuration, and the first invention can be easily adopted even for a suspension device whose installation space is particularly limited.

In the third aspect, the outer peripheral wall of the annular chamber is formed of a bellows, and one end of the bellows is connected to the spring seat and the other end is connected to the outer periphery of the cylindrical body under liquid-tight sealing. The compact structure according to the second aspect of the present invention can be configured to further reduce the risk of liquid leakage.

In the fourth invention, the inner peripheral wall of the annular chamber is formed of a cylindrical diaphragm, and one end of the cylindrical diaphragm is liquid-tightly sealed to the spring seat and the other end is sealed to the outer periphery of the cylindrical body. Because of the connection below, the configuration of the second invention or the third invention can be made such that the fear of liquid leakage is further reduced.

In the fifth invention, a second expanding / contracting liquid chamber for inflow / outflow of liquid to / from the first expanding / contracting liquid chamber is provided.
Since the expansion and contraction of the expansion / contraction liquid chamber is configured to be caused by the irreversible screw mechanism, the actuator for driving the second expansion / contraction liquid chamber, which constitutes the hydraulic pressure generation mechanism, is deactivated while the attitude control is not being performed. Therefore, it is possible to maintain the vehicle body control attitude, so that it is not necessary to keep the actuator in the operating state at all times, so that the energy consumption can be reduced, and the above-mentioned problem of the conventional device in which the energy loss increases can be solved.

In the sixth invention, the second expansion / contraction liquid chamber is an annular chamber defined by inner and outer bellows and end covers respectively closing both ends of an annular space between the inner and outer bellows, and these end covers are formed. Since the second expanding / contracting liquid chamber is configured to expand / contract by being moved closer to or away from each other by the irreversible screw mechanism, it is possible to simplify the hydraulic pressure generating mechanism and reduce the risk of liquid leakage. it can.

In the seventh aspect, since the second elastic means for urging the second expanding / contracting liquid chamber in the contracting direction is provided, the driving force of the hydraulic pressure generating mechanism is further reduced by the elastic force of the second elastic means. Can be.

In the eighth invention, since the second elastic means is constituted by a coil spring disposed in the second expansion / contraction liquid chamber, a structure for reducing the driving force of the hydraulic pressure generating mechanism as in the seventh invention is provided. It can be compact.

In the ninth aspect, the second expansion / contraction liquid chamber communicates with the inside of the cylindrical main body through the hollow hole of the piston rod,
Further, since the inside of the cylindrical main body is communicated with the first expansion / contraction liquid chamber,
Since the hydraulic pressure generating mechanism constituted by the second expansion / contraction liquid chamber is normally mounted on the vehicle body side, it can be connected to a piston rod having a better vibration environment than the wheel side, and the durability at the connection part of the hydraulic pressure generating mechanism Can be improved, and the hydraulic pressure generating mechanism can be installed in a good environment place such as an engine room.

[0034]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a suspension device according to an embodiment of the present invention, wherein 1 is a shock absorber, and 2 is a suspension spring. The shock absorber 1 mainly includes a cylindrical main body 3 and a piston rod 4. The upper end of the piston rod 4 protruding from the cylindrical main body 3 is mounted on a vehicle body (not shown), and the lower end of the cylindrical main body 3 is mounted with wheels (not shown). And a well-known one for practical use.

The suspension spring 2 is a coil type suspension spring arranged so as to surround the shock absorber 1, the upper end of which is seated on the vehicle body, that is, the upper end of the piston rod 4, and the lower end of which is a spring seat 5.
To sit on. Here, the cylindrical portion 6a of the unsprung member 6 is fitted and fixed to the outer periphery of the tubular main body 3, and the spring seat 5 is fitted to the outer periphery of the cylindrical portion 6a so as to be slidable in the axial direction.

The spring seat 5 is moved in a direction opposite to the spring force of the suspension spring 2 via a first coil spring 7 as a first elastic means and a first expansion / contraction liquid chamber 8 to a lower end flange portion 6b of the unsprung member 6. Therefore, it is supported by the cylindrical main body 3. The first coil spring 7 has an upper end seated on the spring seat 5 via the insert 9, a lower end seated on the lower end flange portion 6 b of the unsprung member 6 via the insert 10, and suspends the spring seat 5 by a compression reaction force. It is intended to support the spring 2 in a direction opposite to the spring force.

The first expanding / contracting liquid chamber 8 is an annular chamber surrounding the cylindrical portion 6a of the unsprung member 6, that is, the cylindrical body 3 of the shock absorber 1, and the first coil spring 7 is concentrically provided in the annular chamber. To store. In order to make the first expansion / contraction liquid chamber 8 an annular chamber as described above, its outer peripheral wall is made of a metal bellows 1.
1 and the inner peripheral wall is formed by a cylindrical diaphragm 12. Insert both ends of metal bellows 11
10, and both ends of the cylindrical diaphragm 12 are connected to the spring seat 5 and the lower end flange portion 6b of the unsprung member 6 by liquid-tight sealing, whereby the first expansion / contraction liquid chamber 8 is formed. Spring seat 5 via internal liquid
In the direction opposite to the spring force of the suspension spring 2.

On the outer periphery of the metal bellows 11, a cylindrical protector 13 sandwiched between the lower end flange portion 6b of the unsprung member 6 and the insert 10 is arranged so as to surround the metal bellows 11 with a predetermined gap. Stepping stones and the like do not collide with and damage the metal bellows 11. Further, in order to prevent dust or the like from entering the sliding portion between the cylindrical portion 6a of the spring seat 5 and the unsprung member 6, the sliding portion is connected to the dust boot 14
Cover with.

According to the above configuration, the liquid flows into and out of the first expanding / contracting liquid chamber 8 to move the spring seat 5 into the cylindrical main body 3.
, The relative stroke position between the cylindrical body 3 of the shock absorber 1 and the piston rod 4 is changed, and the posture of the vehicle body can be changed. For this purpose, the hydraulic pressure generating mechanism 21 has the following configuration.

That is, the inner and outer metal bellows 22, 23,
A second expanding / contracting liquid chamber 26 is provided which is annularly defined by end covers 24 and 25 which respectively close both ends of the annular space between the inner and outer metal bellows. A motor 27 as an actuator is attached to one end cover 24, and a male screw member 28 driven to rotate by the motor is attached to the inner metal bellows 2.
2, a female screw member 29 screwed to the projecting end of the male screw member 28 is fixed to the other end cover 25, and a detent member extending from the one end cover 24. Stop rotation at 30. Therefore, when the male screw member 28 is driven to rotate by the motor 27, the other end cover 25
Can be separated from or approached to one end cover 24 via the female screw member 29, and the second expanding / contracting liquid chamber 26 can be expanded / contracted.

The male screw member 28 and the female screw member 29
Can cause the female screw member 29 to stroke in the axial direction of the motor in response to the rotation of the male screw member 28 driven by the motor 27. On the contrary, when the thrust is input to the female screw member 29, the rotation of the male screw member 28 is caused. Irreversible screw mechanism.

Further, the second ring-shaped second member is formed as described above.
A second coil spring 31 as a second elastic means is disposed concentrically in the expansion / contraction liquid chamber 26.
Is installed between the end covers 24 and 25 in an extended state,
The end covers 24 and 25 are urged in a direction approaching each other, that is, a direction in which the second expansion / contraction liquid chamber 26 is contracted. The first expansion / contraction liquid chamber 8 and the second expansion / contraction liquid chamber 26 are communicated with each other by the elastic pipe 32, and the elastic pipe 32 close to the first expansion / contraction liquid chamber 8 is provided.
One end of the unsprung member 6 is opened to the first expansion / contraction liquid chamber 8.
The elastic tube 3 connected to the lower end flange portion 6b and the communication hole 33 formed in the insert 10 and close to the second expanding / contracting liquid chamber 26
The other end of the end cover 24 is opened to the second expansion / contraction liquid chamber 26.
Is connected to the communication hole 34 formed in the hole.

The operation of the suspension device according to the above embodiment will be described below. Cylindrical body 3 due to wheel springing
During the relative stroke of the piston rod 4 and the suspension rod 2, the suspension spring 2 performs a predetermined damping function, and the shock absorber 1 performs a well-known vibration damping function. In controlling the vehicle body attitude, the male screw member 28 is rotated by driving the motor 27. At this time, the female screw member 29 is changed according to the driving direction of the motor 27 (the rotation direction of the male screw member 28).
Is stroked in a direction to separate or approach the end cover 25 from the end cover 24. An amount of hydraulic oil corresponding to the change in the volume of the second expanding / contracting liquid chamber 26 enters and exits the first expanding / contracting liquid chamber 8 via the elastic tube 32 and the volume of the first expanding / contracting liquid chamber 8 in the opposite phase. This causes a change, whereby the spring seat 5 is displaced in a direction to approach or move away from the lower end flange portion 6b of the unsprung member 6. The relative stroke position of the cylindrical body 3 and the piston rod 4 changes so that the shock absorber 1 contracts or expands due to the displacement of the spring seat 5, and the vehicle body posture can be controlled by changing the vehicle height of the corresponding vehicle body part.

At the time of such vehicle body attitude control, the first and second
Static pressure in expansion and contraction liquid chambers 8 and 26, and motor 2
The driving force of No. 7 will be described below with reference to FIG. 2 which shows the suspension device of FIG. 1 as a schematic diagram. At this time, the motor 27 is driven so as to generate the driving force Fa shown in FIG. 2, and the driving force Fa and the tension spring reaction force of the second coil spring 31 are described. With F ₂ , the end cover 25 is brought closer to the end cover 24. As a result, the volume of the second expansion / contraction liquid chamber 26 is reduced, and the amount of hydraulic oil corresponding to the reduced volume is P ₁ × S
₂ (P ₁ is the static internal pressure of the second expanding and contracting liquid chamber 26, S ₂ is the pressure receiving area of the second expanding and contracting liquid chamber 26) and is pushed into the first expanding and contracting liquid chamber 8 through the elastic pipe 32. Causes its volume to increase. The increase in the volume of the first expansion / contraction liquid chamber 8 is such that the spring seat 5 resists the wheel load W in cooperation with the compression spring reaction force F ₁ of the first coil spring 7, and P ₁ × S ₁ (P ₁ is The static internal pressure of the first expansion / contraction liquid chamber 8, S _1, is displaced in a direction away from the lower end flange 6 b of the unsprung member 6 by the oil pressure F ₀ of the pressure receiving area of the first expansion / contraction liquid chamber 8. The relative stroke position of the cylindrical body 3 and the piston rod 4 is changed so that the shock absorber 1 is extended by the displacement of the spring seat 5, and the vehicle body posture can be controlled by increasing the vehicle height of the corresponding vehicle body part.

Here, the static internal pressure P ₁ generated in the first expansion / contraction liquid chamber 8 and the second expansion / contraction liquid chamber 26 will be described with reference to FIG.
As is clear from FIG.
To support the _first expansion / contraction liquid chamber 8 and the second expansion / contraction liquid chamber 8 by the compression spring reaction force F _1. Contraction chamber 26
, The static internal pressure P ₁ becomes lower. As a result, the first expansion / contraction liquid chamber 8
In addition, the occurrence of problems relating to liquid leakage from the second expanding / contracting liquid chamber 26 and the problem of increasing the friction of the seal portion can be reduced, and the hydraulic pressure F ₀ required at the time of controlling the vehicle body attitude also decreases. As a result, the driving force Fa of the motor 27 can be reduced.

The wheel load W are those as shown by A in FIG operating point for those shown by W ₀ in FIG. 3, the above-mentioned facts, the case of vehicle body attitude control in this operation point A If the first coil spring 7 does not exist, the first expanding and contracting liquid chamber 8 and the second expanding and contracting liquid chamber 26
_Since it is necessary to support all ₀ , the motor 27
After having supported the wheel load W ₀ by a large driving force Fa _O relative to the, it is necessary to perform posture control to correct the inclination at the time of vehicle braking and driving or when turning, wheels as in this embodiment First coil spring 7 supporting load W ₀
Is provided, the origin is raised by the compression spring reaction force F ₁ of the first coil spring 7, which is equivalent to rising from the origin 1 to the origin 2 in FIG. 3, and the driving force of the motor 27 can be reduced accordingly. it can be (Fa _O -F _1).

It should be noted, by increasing the compression spring reaction force F ₁ of the first coil spring 7 as the origin 2 matches the operating point A, but it can minimize the driving force of the motor 27 is ideal Since it is necessary to constantly apply a positive pressure to the hydraulic pressure as long as the displacement force of the spring seat 5 is generated using the hydraulic pressure, there is a limit to reducing the driving force of the motor 27 using only the first coil spring 7. is there. Therefore, in the present embodiment, as described above, the second coil spring 31 that urges the end covers 24 and 25 of the second expansion / contraction liquid chamber 26 in a direction approaching each other is provided.

The second coil spring 31 is used to reduce the volume of the second expanding / contracting liquid chamber 26 by bringing the end cover 25 close to the end cover 24 with the driving force Fa of the motor 27 during the posture control by increasing the vehicle height. The hydraulic pressure P ₁ × S ₂ (see FIG. 2) is shared by F ₂ , and the driving force Fa of the motor 27 can be made smaller than the hydraulic pressure (P ₁ × S ₂ ) by F ₂ . It is added that about 3, the origin becomes equivalent to the further pulling of the amount corresponding to the spring reaction force F ₂ of the second coil spring 31 raising from the origin 2, correspondingly, the motor 27
The driving force is further reduced _{F 3 (= Fa O -F 1} -F
₂ ) Can be.

In this embodiment, as shown in FIG. 1, the first expanding / contracting liquid chamber 8 is an annular chamber for enclosing the cylindrical body 3 of the shock absorber 1, and the first coil spring is provided in the annular chamber. 7 can be realized with a compact configuration, and the present embodiment can be easily applied to a suspension device whose installation space is limited. it can.

The outer peripheral wall of the first expanding / contracting liquid chamber 8 having an annular shape as described above is constituted by a bellows 11, the upper end of the bellows being the insert 9 on the spring seat 5 side, and the lower end being the cylindrical body 3. Since it is connected to the insert 10 near the lower end flange 6b of the unsprung member 6 fixed to the outer periphery under liquid-tight sealing, the fear of liquid leakage can be further reduced.

Further, the inner peripheral wall of the first expanding / contracting liquid chamber 8 having an annular shape as described above is constituted by a cylindrical diaphragm 12, the upper end of the cylindrical diaphragm being the spring seat 5, and the lower end being the cylindrical body 3. Since they are connected to the outer periphery under liquid-tight sealing, there is no need to worry about liquid leakage relating to the sliding portion of the spring seat 5.

In addition, the expansion and contraction of the second expansion / contraction liquid chamber 26 constituting the hydraulic pressure generating mechanism 21 for flowing the liquid into and out of the first expansion / contraction liquid chamber 8 is constituted by a male screw member 28 and a female screw member 29. Since the motor 27 for driving the hydraulic pressure generating mechanism 21 is not operated while the posture control is not being performed, the vehicle body control posture can be maintained. It is no longer necessary to keep the device in an operating state at all times, so that the energy consumption can be reduced, and the above-mentioned problem of the conventional device in which the energy loss increases can be solved.

Further, the second expansion / contraction liquid chamber 26 is connected to the inner and outer bellows 2.
2 and 23, and end covers 24 and 25 for closing both ends of the annular space between the inner and outer bellows, respectively, and these end covers 24 and 25 are brought closer to each other by the irreversible screw mechanism. Since the second expanding / contracting liquid chamber 26 is expanded / contracted by causing the hydraulic pressure generating mechanism 21 to expand / contract, the hydraulic pressure generating mechanism 21 can have a simple configuration and can be configured to have no fear of liquid leakage. Also, the second coil spring 2
6 is arranged in the second expanding / contracting liquid chamber 26 which is annular as described above, so that the hydraulic pressure generating mechanism 21 can be downsized.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the inner cylindrical portion 5a of the spring seat 5 is provided.
The O-ring 41 is provided on the sliding portion between the unsprung member 6 and the cylindrical portion 6a.
, The inner peripheral portion of the first expanding / contracting liquid chamber 8 formed in a ring shape is sealed, and the sealing relating to the outer peripheral portion of the first expanding / contracting liquid chamber 8 is provided integrally with the spring seat 5. The outer peripheral surface of the outer cylinder portion 5b and the inner peripheral surface of the cylinder member 42 attached to the lower end flange portion 6b of the unsprung member 6 are slidably fitted to each other, and the O-ring 43 is fitted to the fitting portion. It is performed by intervening.
Then, the fitting portion is covered with a dust boot 44 so that dust and the like do not enter the sliding fitting portion between the outer peripheral surface of the spring seat outer cylindrical portion 5b and the inner peripheral surface of the cylinder member 42.

In this embodiment, the first expansion / contraction liquid chamber 8
Although the sealing at the inner and outer peripheral portions of can not be expected to be perfect in sealing as in the case of using the diaphragm 12 and the metal bellows 11 as in the above-described embodiment,
The inclination of the spring seat 5 due to the offset of the springs 2 and 7 is prevented not only by the fitting portion between the inner cylindrical portion 5a of the spring seat 5 and the cylindrical portion 6a of the unsprung member 6, but also by the outer cylinder of the spring seat 5. Part 5b and cylinder member 4
2 can also be prevented.

FIG. 5 shows still another embodiment of the present invention. In this embodiment, the first expansion / contraction liquid chamber 8 and the second
The expansion / contraction liquid chambers 26 are communicated with each other as follows. First, the shock absorber 1 will be described in detail. The tubular main body 3 is constituted by integrally and integrally connecting an inner cylinder 3a and an outer cylinder 3b, and defines a reservoir chamber 3c between the inner and outer cylinders 3a and 3b. The reservoir chamber 3c communicates with the lower end of the inner cylinder 3a through a well-known vibration damping bottom valve 51 at the lower end of the inner cylinder 3a, and also communicates with the first expansion / contraction liquid chamber 8 through a communication hole 52 also near the lower end. The working fluid is sealed in the entire inner cylinder 3a and the lower part of the reservoir chamber 3c, and gas is sealed in the upper part of the reservoir chamber 3c. The piston 4a at the inner end of the piston rod 4 is slidably fitted into the inner cylinder 3a, but a gap between the piston 4a and the inner cylinder 3a is large enough to allow the replacement flow of the hydraulic fluid before and after the piston 4a. To have.

In the shock absorber 1 described above, a wheel (not shown) is attached to the lower end of the cylindrical main body 3 and the upper end of the piston rod 4 is attached to the vehicle body 53 and housed in a wheel house 54 for practical use. The hydraulic pressure generating mechanism 21
3 in the engine room 55 adjacent to the wheel house 54 with the second expansion / contraction liquid chamber 2 of the hydraulic pressure generating mechanism 21 interposed therebetween.
An elastic tube 32 extending from 6 is connected to a distal end opening of a hollow hole 4b formed in the center of the piston rod 4 so as to open to the inner cylinder 3a.

As described above, the second expansion / contraction liquid chamber 26 is communicated with the inside of the cylindrical body 3 (the inner cylinder 3a) through the hollow hole 4b of the piston rod 4, and the second main body 3 (the inner cylinder 3a) is opened. When the reservoir chamber 3c communicated with the inside is communicated with the first expansion / contraction liquid chamber 8 through the communication hole 52, the first expansion / contraction liquid chamber 8 and the second expansion / contraction liquid chamber 2
The space between 6 is the hollow hole 4b of the piston rod 4 and the cylindrical body 3
The hydraulic pressure generating mechanism 21 can be connected to the piston rod 4 which has a better vibration environment than the wheel side because the hydraulic pressure generating mechanism 21 is normally mounted on the vehicle body side. Can be improved in durability, and the hydraulic pressure generating mechanism 21 can be installed in a good environment location such as in the engine room 55.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a main part of a suspension device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram schematically showing the suspension device for explaining operation.

FIG. 3 is a diagram showing a relationship between a wheel load and an actuator driving force of the suspension device.

FIG. 4 is a longitudinal sectional side view of a lower portion of a shock absorber showing a suspension device according to another embodiment of the present invention.

FIG. 5 is a vertical sectional side view showing a suspension device according to still another embodiment of the present invention attached to a vehicle body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shock absorber 2 Suspension spring 3 Cylindrical body 3a Inner cylinder 3b Outer cylinder 3c Reservoir chamber 4 Piston rod 4a Piston 4b Hollow hole 5 Spring seat 5a Same inner cylinder part 5b Same outer cylinder part 6 Unsprung member 6a Same cylindrical part 6b Same as above Lower flange 7 First coil spring (first elastic means) 8 First expansion / contraction liquid chamber 9 Insert 10 Insert 11 Metal bellows 12 Diaphragm 13 Protector 14 Dust boot 21 Hydraulic pressure generating mechanism 22 Inner metal bellows 23 Outer metal bellows 24 End cover 25 End cover 26 Second expansion / contraction liquid chamber 27 Motor (actuator) 28 Male screw member 29 Female screw member 30 Detent member 31 Second coil spring (second elastic means) 32 Elastic tube 33 Communication hole 34 Communication hole 41 O-ring 42 Cylinder Member 43 O-ring 44 Dust boot 51 Vibration damping bottom valve 52 Communication hole 53 Body 54 Wheel house 55 D Jinrumu

Claims (9)

[Claims] 1. A suspension device in which a coil type suspension spring is fitted to a shock absorber and mounted between a cylindrical body of the shock absorber and a piston rod, wherein an end of the suspension spring close to the cylindrical body is provided. A spring seat to be seated is fitted on the outer periphery of the cylindrical body so as to be axially displaceable, and the spring seat is moved in a direction opposite to the spring force of the suspension spring via the first elastic means and the first expansion / contraction liquid chamber. The spring seat is displaced in the axial direction of the tubular body by the inflow and outflow of the liquid into and from the first expansion / contraction liquid chamber, whereby the relative stroke position between the tubular body of the shock absorber and the piston rod can be changed. A suspension device characterized in that: 2. The device according to claim 1, wherein the first expansion / contraction liquid chamber is an annular chamber surrounding the tubular main body, and the first elastic means is a coil spring housed in the annular chamber. A suspension device characterized by the following. 3. The bellows according to claim 2, wherein one end of the bellows is connected to the spring seat, and the other end of the bellows is connected to the outer periphery of the cylindrical body under liquid-tight sealing. A suspension device characterized by: 4. The cylindrical chamber according to claim 2, wherein an inner peripheral wall of the annular chamber is formed of a cylindrical diaphragm, and one end of the cylindrical diaphragm is provided on the spring seat, and the other end is provided on an outer periphery of the cylindrical body. A suspension device connected under liquid-tight sealing. 5. The second expansion / contraction liquid chamber according to claim 1, further comprising a second expansion / contraction liquid chamber for inflow / outflow of liquid to / from the first expansion / contraction liquid chamber. A suspension device characterized in that expansion and contraction are caused by an irreversible screw mechanism. 6. The second expansion / contraction liquid chamber according to claim 5, wherein the second expansion / contraction liquid chamber is an annular chamber defined by inner and outer bellows and end covers respectively closing both ends of an annular space between the inner and outer bellows. A second expansion / contraction liquid chamber configured to expand / contract by moving the second expansion / contraction liquid chamber closer to or away from each other by the irreversible screw mechanism. 7. The suspension device according to claim 5, further comprising a second elastic means for urging the second expansion / contraction liquid chamber in a contraction direction. 8. The suspension device according to claim 7, wherein the second elastic means is constituted by a coil spring disposed in the second expansion / contraction liquid chamber. 9. The cylindrical body according to claim 5, wherein the second expansion / contraction liquid chamber communicates with the inside of the cylindrical body through a hollow hole of the piston rod. A suspension device, wherein the suspension device communicates with the first expansion / contraction liquid chamber.