JP2989315B2 - Damping force adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force adjusting device which adjusts a main damping force generated by a leaf valve as a damping valve by changing the peripheral bending amount of the leaf valve using a piezoelectric element. Regarding improvement.

[0002]

2. Description of the Related Art As a conventional damping force adjusting device for a hydraulic shock absorber, a main damping force generated by the leaf valve is changed by adjusting a bending amount of a peripheral end of a leaf valve which is a damping valve by applying a voltage to a piezoelectric element. Such an arrangement is proposed in, for example, Japanese Patent Application Laid-Open No. Sho 61-13041.

In this proposal, there is a disadvantage that the adjustment width of the damping force cannot be made larger than the amount of deformation of the piezoelectric element.

That is, in this proposal, when a voltage is applied to a piezoelectric element serving as an electrostrictive member, when the piezoelectric element expands, the amount of expansion of the peripheral end of a leaf valve serving as a damping force valve for generating a damping force is increased by the expansion force. The damping force generated by the leaf valve is directly adjusted by the direct adjustment.

Therefore, according to this prior art, it is impossible to change the peripheral end bending amount of the leaf valve beyond the expansion amount of the piezoelectric element. The amount of serially arranged elements must be greatly increased, and in this case, there is a disadvantage that the axial length of the entire damping force adjusting device is greatly increased.

On the other hand, an expansion-side leaf valve as an expansion-side damping valve and a compression-side leaf valve as a compression-side attenuation valve are respectively disposed on the end surface of a piston body that slides in a cylinder, and the back surface of each of the piston bodies. The sub-valve is provided with a back pressure acting on the orifice via a sub-valve, and each of these sub-valves is disposed in a front spigot member connected to the front end of the piston rod, while hydraulic pressure is applied to the back of each leaf valve. Supply and change the amount of bending of each peripheral end by the expansion force generated in the piezoelectric element,
A configuration in which the supply hydraulic pressure to the rear surface is changed has been proposed by the present applicant.

[0007]

In the case of the prior art, since the orifice is used as the fixed throttle of the pilot portion, the piston speed is relatively low (when the amount of oil flowing through the pilot portion is relatively small). ), The effect of this throttle is moderate and the damping force of the hardware is not so high (back pressure of each leaf valve does not become very high), but as the piston speed increases, the pilot flow rate also increases, and this throttle And the damping force of the hardware increases accordingly (the back pressure of each leaf valve increases greatly).

[0008] Therefore, the oil in the piston-side oil chamber cannot be sufficiently supplied to the piston-rod-side oil chamber particularly at the time of the pressure side, which causes a so-called poor oil suction.

On the other hand, in order to prevent this, if the diameter of the orifice is increased to reduce the throttling effect, it is no longer possible to secure the width of deceleration in the low speed range of the piston.

That is, there is a problem that the damping force of the hardware does not increase.

Further, the number of parts of the pilot system increases,
There were problems such as disadvantages in terms of assemblability and cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to increase the amount of deflection at the peripheral end of a leaf valve as a damping valve as compared with the expansion of a piezoelectric element as an electrostrictive member. In this way, the range of adjustment of the generated damping force is increased, so that it is optimized for use in hydraulic shock absorbers, and optimal damping force characteristics corresponding to the speed of the piston rod are obtained, resulting in insufficient oil suction. And to propose a damping force adjusting device capable of further simplifying the configuration.

[0013]

In order to achieve the above object, the present invention provides a piston rod inserted into a cylinder, a piston body attached to the histone rod and sliding in the cylinder. A rear-side damping valve and a compression-side damping valve disposed on each end surface of the piston rod; and a rear-side of the rear-side damping valve and the compression-side damping valve disposed in a tip spigot member attached to a distal end of the piston rod. An expansion-side first sub-valve and a compression-side first sub-valve comprising a leaf valve for supplying pressure, and the expansion-side first sub-valve and the compression-side first sub-valve provided in the piston rod via a valve spool by its own reverse piezoelectric action. A piezoelectric element that adjusts the amount of deflection of the periphery of the valve, and a hydraulic pressure that is outside the front spigot member and communicates with the back pressure passage of each of the damping valves A second expansion sub-valve and a second compression sub-valve comprising a leaf valve arranged between the piston-side oil chamber and the rod-side oil chamber, respectively, for setting a damping force characteristic according to the speed of the piston rod. It is characterized by having.

The expansion-side first sub-valve and the compression-side first sub-valve may be urged in the opening direction by a backup spring provided on the back surface.

[0015]

When the piston rod slides in the cylinder, the hydraulic oil from the so-called upstream oil chamber reaches the rear side of each leaf valve that generates a main damping force via each first sub-valve. This extends to the pressure receiving surface side of each of the leaf valves, and the hydraulic oil passes while bending the peripheral end of each of the leaf valves, thereby generating a predetermined damping force on each of the respective sides.

At this time, when a predetermined voltage is applied to the piezoelectric element, the amount of bending of each peripheral end of each sub-valve is adjusted according to the magnitude of the applied voltage, and the back pressure at each leaf valve is reduced. The respective adjustments are made to adjust the amount of deflection at the peripheral end of each leaf valve, and each damping force generated at each leaf valve is adjusted.

As a result, the damping force generated in each of the leaf valves can be changed within a width equal to or larger than the expansion amount of the piezoelectric element.

When the application of the voltage to the piezoelectric element is released, the bending amount of the peripheral end of each of the first sub-valves returns to the old state,
Thereby, the hydraulic pressure acting on the back surface of each leaf valve also returns to the old state, and the generated damping force at each leaf valve is returned to the initially set magnitude.

On the other hand, each second sub-valve has a PQ characteristic of 3
Because of the square power characteristic, the above back pressure is relatively high in the low speed range of the piston rod to obtain a sufficient range of deceleration, and in the middle and high speed range, the suction of oil is performed without excessive back pressure passage. Prevent defects.

However, if the damping width is set to a value larger than the above, the balance between the piezoelectric element generation force and the resulting decrease in the damping force is lost, and discontinuity occurs between the voltage and the damping force. By providing a back-up spring on the back side in the direction in which it opens, the damping force can always be changed continuously.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a main part showing a damping force adjusting device according to one embodiment of the present invention. Reference numeral 1 denotes a cylinder, in which a rod-side oil chamber A and a piston-side oil chamber B are provided. It has a piston portion 3 that forms a compartment.

A piezoelectric element 4 serving as an electrostrictive member is disposed in a through hole 2a formed in the shaft core of the hollow piston rod 2.

Although not shown, a lead wire is connected to the piezoelectric element 4, and an end of the lead wire projects outside from a rear end, which is the upper end of the piston rod 2.

The piezoelectric element 4 expands when a predetermined voltage is applied thereto, and the expansion force changes and adjusts the main damping force on the expansion side and the compression side, respectively.

The expansion force acts so that only the tip of the piezoelectric element 4 moves downward.

The piston rod 2 is provided with a front spigot member 20 connected to the front end 2b, and the piston 3 is interposed on the outer periphery of the front spigot member 20.

The piston portion 3 has a piston body 30 that slides in the cylinder 1, and an extension-side leaf valve 5 as an extension-side damping valve and a compression-side leaf as a compression-side damping valve disposed so as to sandwich the piston body 30. And a valve 6.

The extension side leaf valve 5 is disposed so as to close the lower end opening of the extension side port 30a opened in the piston body 30, and the compression side leaf valve 6 is opened in the piston body 30. The pressure side port 30b is disposed so as to close the upper end opening.

Each of the leaf valves 5 and 6 is formed of an annular leaf valve, and is fixed in such a manner that the inner peripheral end is fixed and the outer peripheral end is free. Generates the damping force on the extension side and the compression side.

That is, each of the leaf valves 5 and 6 has upper and lower end surfaces on the inner peripheral side of the piston body 30, a spacer 50 and a front spigot member disposed so as to face the upper and lower end surfaces. The upper and lower end surfaces on the outer peripheral side of the piston body 30 and the valve stoppers 51 and 61 disposed opposite to the upper and lower end surfaces are adjacent to the outer peripheral end thereof. I have.

The valve stoppers 51 and 61 are biased by biasing springs 52 and 62, respectively, to move the outer peripheral ends of the leaf valves 5 and 6 to the upper and lower end surfaces (piston seat surfaces) on the outer peripheral side of the piston body 30. The magnitude of the main damping force generated by each leaf valve 5, 6 is set by selecting the pressing, the urging force, and the bending rigidity of each leaf valve 5, 6.

In this embodiment, the hydraulic chambers 53, 6 are provided on the back side of the leaf valves 5, 6, respectively.
3 are formed, and are defined by spacers 50, valve stoppers 51 and 61, and housings 54 and 64 for accommodating the valve stoppers 51 and 61.

The hydraulic chambers 53 and 63 communicate with the inside of the front spigot member 20 via the communication holes 50a formed in the spacers 50 and 60 and the communication holes 21b and 21c of the front spigot member 20, respectively. doing.

The front spigot member 20 has a rear-side first sub-valve 7 and a pressure-side first sub-valve 7 for supplying hydraulic pressure to the back surfaces of the leaf valves 5 and 6, that is, the back pressure passages 5 a and 6 a and the hydraulic chambers 53 and 63. It has one sub-valve 8.

That is, the front spigot member 20 is integrally connected and comprises a rod portion 21 and a connecting portion 22 on the upper end side.

Each of the first sub-valves 7 and 8 has a cylindrical inner space 21a formed inside the rod 21.
Garbage.

Each of the first sub-valves 7 and 8 has its peripheral end bending amount changed by expansion force generated in the piezoelectric element 4. In this embodiment, each of the first sub-valves 7 and 8 comprises an annular leaf valve. When the outer peripheral end is bent, it is set so as to allow the flow of the hydraulic oil through the first sub-valves 7 and 8.

That is, the extension-side first sub-valve 7 has an annular seat portion 71a of the valve seat 71 in contact with the back surface thereof.

The valve seat 71 is fitted in the inner space 21a.

The annular seat portion 71a is in contact with the rear side of the extension-side first sub-valve 7 near the inner peripheral end.

Further, the expansion-side first sub-valve 7 has an inner peripheral side fixed portion 72a and an outer peripheral side seat portion 72b below the valve spool 72 in contact with a pressure receiving surface which is an upper surface.

The valve spool 72 is provided in the inner space 21a.
Is slidably fitted in the up and down direction, and the inner peripheral side fixed portion 72a
An annular groove 72c is provided between the outer peripheral side seat portion 72b and the outer peripheral side seat portion 72b.

Further, the valve spool 7 is provided in the annular groove 72c.
A port 72d that penetrates the thick portion at the upper part of 2 is opened.

Therefore, the extension-side first sub-valve 7 in this embodiment has an inner peripheral end on the inner peripheral side fixed portion 72a of the valve spool 72 and an annular seat portion 71 of the valve seat 71.
a and the outer peripheral end thereof is fixed so as to be flexible.

Accordingly, when the hydraulic pressure acts on the outer peripheral end of the extension-side first sub-valve 7, it is deflected downward in the figure, and at this time, a predetermined flow rate of the hydraulic oil is secured.

However, since the inner peripheral end side of the expansion-side first sub-valve 7 is sandwiched between the innermost inner-peripheral-side fixed portion 72a and the annular seat portion 71a slightly closer to the outer periphery, the expansion-side first sub-valve 7 is held. When the inner peripheral end of the sub-valve 7 is positively pressed against the inner peripheral fixing portion 72a with the annular seat portion 71a as a fulcrum, the outer peripheral end of the expansion-side sub-valve 7 is in a so-called lever motion, and is moved to the outer peripheral seat portion 72b of the valve spool 72. When pressed, the amount of deflection of the outer peripheral end of the extension-side first sub-valve 7 is changed, and the flow rate of hydraulic oil is changed to decrease via the outer peripheral end of the extension-side first sub-valve 7.

On the other hand, the pressure-side first sub-valve 8 has an annular seat portion 81a of a valve seat 81 also serving as a valve spool in contact with a back surface as an upper surface.

The valve seat 81 is vertically movable in the inner space 21a, that is, is accommodated in the axial direction of the rod surface 21.

The valve seat 81 has a notch 81b formed in a thick portion thereof.
This allows communication between the pressure side leaf valve 6 side and the outside of the valve seat 81.

The annular seat portion 81a is in contact with the rear side of the pressure-side first sub-valve 8 near the inner peripheral end.

The pressure-side first sub-valve 8 has an inner peripheral side fixed portion 82 at the upper end of the valve spool 72 on the pressure-receiving surface, which is the lower surface.
a and the outer peripheral side sheet portion 82b are in contact with each other.

The valve spool 72 has an annular groove 82c between the inner peripheral fixing portion 82a and the outer peripheral seat portion 82b, and the valve spool 7 is provided in the annular groove 82c.
A port 82d penetrating the thick portion at the lower part of the second port 2 is opened.

For this reason, the pressure side first sub-valve 8 in this embodiment has an inner peripheral end side having an inner peripheral side fixed portion 82a of the valve spool 72 and an annular seat portion 8 of the valve seat 81.
1a, and the outer peripheral end thereof is flexibly fixed.

Therefore, when hydraulic pressure acts on the outer peripheral end of the pressure side first sub-valve 8, it bends upward, and at this time, a predetermined flow rate of hydraulic oil is secured.

The inner peripheral end of the compression-side first sub-valve 8 is sandwiched between the innermost inner-peripheral-side fixed portion 82a and the annular seat portion 81a slightly closer to the outer periphery. When the inner peripheral end is positively pressed against the inner peripheral side fixed portion 82a with the annular seat portion 81a as a fulcrum, the outer peripheral end of the pressure side sub-valve 8 is pressed against the outer peripheral side seat portion 82b of the valve spool 82 by a so-called lever motion. That is, the amount of deflection of the outer peripheral end of the compression-side first sub-valve 8 is changed.

Accordingly, the flow rate of the hydraulic oil through the outer peripheral end of the pressure side sub-valve 8 is adjusted to decrease.

By the way, the hydraulic oil flowing out to the downstream side through each of the first sub-valves 7 and 8 flows into the communication hole 21b formed in the rod portion 21 and the communication hole 50a formed in the spacer 50, respectively. The fluid flows into the hydraulic chambers 53 and 63 through the communication holes 21c, respectively.

Further, on the upstream side of each of the first sub-valves 7 and 8, an extension side port
Hydraulic oil flows through the pressure port 0a and the pressure side port 30b, respectively.

More specifically, the piston body 30 is provided with an extension side subport 30c extending from the inner peripheral surface near the lower end of the piston main body 30 to the lower end surface thereof, and from the inner peripheral surface near the upper end of the piston main body 30 to the piston main body 30. A pressure-side subport 30d is opened to the upper end surface of the pressure-sensitive sub-port.

The subports 30e and 30f are
The inner peripheral surface of the piston body 30 communicates with communication holes 21d and 21e formed in the adjacent rod portion 21 and also communicates with the inner space 21a of the rod portion 21 through these communication holes 21d and 21e. I have.

The sub-ports 30c and 30d communicate with the ports 30a and 30b by annular grooves 30e and 30f formed in the upper and lower end surfaces of the piston body 30, respectively.

A steel ball 43 is provided between the valve seat 81 and the block 42 locked at the end of the piezoelectric element 4.
The expansion force generated by the piezoelectric element 4 acts on the above-described member when a predetermined voltage is applied to the piezoelectric element 4 under the alignment structure of the steel balls 43.

On the other hand, a fastening member 92 having a cylindrical portion 91 is screwed into the outer periphery of the lower end of the rod portion 21, and a support ring 93 is mounted on the flange portion 92a of the fastening member 92. .

The support ring 93 comprises a support piece 93a directly supported by the flange 92a and an upstanding piece 93b rising from the periphery thereof. The support piece 93a communicates with the piston side oil chamber B. A communication hole 94 is provided.

Reference numeral 95 denotes a spacer mounted near the inner peripheral end of the bearing piece 93a. The extension second sub-valve 9 is mounted on the spacer 95.
6 is placed on the inner peripheral end.

Reference numeral 97a denotes an inner peripheral side seat formed at the lower end of the housing 54, which holds the inner peripheral end of the second sub-valve 96 between the spacer 95 and the inner peripheral side.

Reference numeral 97b denotes an outer peripheral side seat portion 97b which is in contact with the upper surface on the outer peripheral end side of the extension side second sub-valve 96.

Reference numeral 97c denotes a communication hole provided between each of the seat portions 97a and 97b. Reference numeral 98 denotes a spring seat of the urging spring 52 installed on the inner peripheral seat portion 97a of the housing 54. Is provided with a cutout 98a communicating with the hydraulic chamber 53, the communication hole 97c, and the communication hole 94.

Further, on the outer periphery of the upper part of the rod portion 21,
A support ring 101 is attached so as to cover the housing 64 from outside.

The support ring 101 comprises a support piece 101a supported on the step of the rod 21 and an upstanding piece 101b rising from the periphery thereof.
A is provided with a communication hole 102 that communicates with the rod-side oil chamber A.

Reference numeral 103 denotes a spacer provided on the lower surface of the inner peripheral end of the support piece 101a. On the spacer 103, the inner peripheral end of the pressure-side second sub-valve 104 is provided.

Reference numeral 105a denotes an inner peripheral seat formed at the upper end of the housing 64, which holds the inner peripheral end of the pressure-side second sub-valve 104 between the inner seat and the spacer 103.

Reference numeral 105b denotes an outer peripheral side seat portion which is in contact with the lower surface of the outer peripheral end of the pressure side second sub-valve 104.

Reference numeral 105c denotes each of the sheet portions 105a, 1
The communication holes 106 provided between the housings 64b
The spring seat of the urging spring 62 provided on the lower surface of the inner peripheral side seat portion 105a of the
3. Notch 1 communicating with communication hole 105c and communication hole 102
06a is provided.

In the hydraulic shock absorber according to this embodiment formed as described above, each port 3 of the piston body 30
When the hydraulic oil passes through 0a and 30b, the hydraulic oil flows into the pressure receiving surface side of each leaf valve 5 and 6, while reaching the back side of each sub valve 7 and 8 via each sub port 30c and 30d. Will be.

The hydraulic oil flowing through the first sub-valves 7, 8 on each side flows into hydraulic chambers 53, 63 formed on the back side of the leaf valves 5, 6. The bending amount of the outer peripheral ends of the fifth and sixth parts is suppressed.

The bending amount of the outer peripheral end of each of the first sub-valves 7 and 8 is controlled by a predetermined voltage applied to the piezoelectric element 4. In this embodiment, the voltage is applied to the piezoelectric element 4 by applying a voltage. When the amount of bending at the outer peripheral end of each of the first sub-valves 7 and 8 is changed, the amount of oil that has been supplied to the back surface of each of the leaf valves 5 and 6, that is, the hydraulic pressure, decreases.
Therefore, the amount of deflection of the outer peripheral end of each of the leaf valves 5, 6 increases, and the damping force generated in each of the leaf valves 5, 6 is adjusted to decrease.

When the voltage is applied to the piezoelectric element 4, the amount of deflection of the inner peripheral end of each of the leaf valves 5 and 6, which generate a predetermined damping force when the hydraulic shock absorber expands and contracts, is changed. The generated damping force is adjusted to a high tendency.

In this case, when a voltage is applied to the piezoelectric element 4, the expansion force generated in the piezoelectric element 4 is temporarily reduced to the first level.
The amount of deflection of the outer peripheral ends of the sub-valves 7 and 8 is changed to restrict the flow rate of hydraulic oil passing through the outer peripheral ends of the first sub-valves 7 and 8 on each side. By changing the flow rate of the oil, the main damping forces generated in the leaf valves 5 and 6 are changed.

As a result, the amount of deflection of the outer peripheral end of each of the leaf valves 5 and 6 can be made extremely large as compared with the amount of expansion of the piezoelectric element 4. The force can be adjusted in a wide range as compared with the amount of expansion of the piezoelectric element 4.

Further, the flow of the pilot when the piston rod 2 moves to the extension side and the compression side, that is, the oil flowing to the extension side first sub-valve 7 and the compression side first sub-valve 8 pushes and opens these, and then passes through. The oil that wraps around the back of each of the leaf valves 5 and 6 and gives back pressure thereto is communicated with the communication hole 21b of the rod portion 21, the hydraulic chamber 53, the cutout 98a of the spring seat 98, and the communication hole 97c of the housing 54.
Pushes and opens the extension-side second sub-valve 96, and pushes and opens the compression-side second sub-valve 104 through the communication hole 21c of the rod portion, the hydraulic chamber 63, the cutout portion 106a of the spring seat 106, and the communication hole 105c of the housing 64. As a result, they flow out to the piston-side oil chamber B and the rod-side oil chamber A, respectively.

The back pressure applied to each of the leaf valves 5 and 6 at this time depends on the characteristics of each of the second sub-valves 96 and 104,
That is, the PQ characteristic is relatively high in the low speed range of the piston rod 2 and not so high in the middle and high speed range because of the ２ power characteristic.

Therefore, when the piston rod 2 operates at a low speed, a sufficient step-down width is ensured. When the piston rod 2 operates at a medium speed, the damping force of the hardware is not significantly increased, and there is no fear of causing poor oil suction. Absent.

The first sub-valves 7, 8 are provided so as to be supported by a single spool formed integrally, so that the movement of the piezoelectric element 4 can be controlled with high sensitivity. To simplify the configuration and reduce the cost.

FIG. 2 shows another embodiment of the present invention. In this embodiment, backup back slings 90 and 90a made of a disc spring, a coil spring and the like are provided on the back of the extension-side first sub-valve 7 and the back of the compression-side first sub-valve 8. Arranged on the extension side first
The sub-valve 7 and the pressure-side first sub-valve 8 are urged in the opening direction.

The other structure, operation and effect are the same as those of the embodiment of FIG. 1, and the details are omitted by attaching the same reference numerals.

In the embodiment of FIG. 2, when a voltage is applied to the piezoelectric element 4, each sub-valve 7 or 8 is pushed by the valve spool 72 in the closing direction as in the embodiment of FIG. 1, but is opened by the backup springs 90 and 90a. Is prevented from suddenly changing from a certain opening position to the fully closed state.

For this reason, the damping force can be continuously changed even when a large damping force adjustment width is set by the applied voltage.

[0090]

As described above, according to the present invention, the piston rod inserted into the cylinder and the piston body attached to the piston rod and slid in the cylinder are disposed on each end face. It comprises a rebound damping valve and a compression damping valve, and a leaf valve arranged in a tip spigot member attached to the tip of the piston rod to supply back pressure to the back of the rebound damping valve and the compression damping valve. A piezoelectric element provided in the piston rod for adjusting the peripheral deflection of the expansion-side first sub-valve and the compression-side first sub-valve via a valve spool by its own reverse piezoelectric action. A hydraulic chamber that is provided outside the tip spigot member and communicates with a back pressure passage of each of the damping valves; Between the oil chamber and the rod side oil chamber,
Since the expansion-side second sub-valve and the compression-side second sub-valve each composed of a leaf valve are connected to each other to set a damping force characteristic according to the speed of the piston rod,
It becomes possible to greatly increase the amount of deflection at the peripheral end of each side leaf valve as compared with the amount of expansion of the piezoelectric element. There is an advantage that adjustment can be made in a wider range as compared with the above. Further, in the present invention, each of the first and second sub-valves is constituted by a leaf valve, and the hydraulic fluid generated by the pilot flow pushes and opens each of the first sub-valves, then flows around the back of each of the damping valves, and then each of the second sub-valves. At the same time, the back pressure applied to each damping valve is two thirds that the PQ characteristic of each second sub-valve is the characteristic of the leaf valve.
Due to the power characteristic, it is relatively high in the low-speed range of the piston and not so high in the medium-high speed range. Therefore, a sufficient damping force adjustment width is ensured even in the low-speed range of the piston, and the damping force of the hardware is not so high in the middle and high-speed range, so that insufficient suction of oil does not occur.

[0091]

Further, since the backup spring is disposed on the back side of the extension side and the compression side first sub-valve, the damping force continuously changes with respect to the voltage applied to the piezoelectric element even if the damping force change width is increased. be able to.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing a hydraulic shock absorber according to one embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating a hydraulic shock absorber according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston rod 4 Piezoelectric element 5 Extension side damping valve 5a, 6a Back pressure passage 6 Compression side damping valve 7 Extension side first sub-valve 8 Compression side first sub-valve 90, 90a Backup spring 96 Extension side second sub-valve 104 Compression side second sub-valve A Oil chamber on rod side B Oil chamber on piston side

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16F 9/00-9/58 B60G 17/08

Claims (2)

(57) [Claims] 1. A piston rod inserted into a cylinder, an extension damping valve and a compression damping valve mounted on each end face of a piston body attached to the piston rod and sliding in the cylinder, An extension first sub-valve and a compression side first sub-valve disposed in a tip spigot member attached to the tip of the piston rod and configured to supply back pressure to the back of the extension-side damping valve and the compression-side damping valve. And a piezoelectric element provided in the piston rod for adjusting the amount of bending around the expansion-side first sub-valve and the compression-side first sub-valve via a valve spool by its own reverse piezoelectric action. Between the hydraulic chamber communicating with the back pressure passage of each of the damping valves and the piston-side oil chamber and the rod-side oil chamber. And a damping force adjusting device including a leaf-side second sub-valve and a pressure-side second sub-valve, each of which is a leaf valve for setting a damping force characteristic according to a speed of a piston rod. 2. A back-up spring is disposed on the back side of the extension-side first sub-valve and the compression-side first sub-valve to extend the extension-side first sub-valve.
2. The damping force adjusting device according to claim 1, wherein the sub-valve and the pressure-side first sub-valve are biased in directions in which they are opened.