JPH04370430A - Damping force regulator for hydraulic damper - Google Patents

Abstract

PURPOSE:To stably and rapidly switch damping valves in changing over damping force, and shorten a basic length as a whole. CONSTITUTION:Two oil chambers A, B partitioned by a piston 30 are communicated with each other via a port disposed in the piston and damping valves 5, 6 provided at outlet ends of the port. A pilot passage bypassing the damping valves is formed inside the piston and a piston rod. First sub valves 7, 8 and second sub valves 96, 104 for applying a back pressure to the damping valves are provided inside the pilot passage. The back surfaces of the damping valves are supported by elastic seals 51, 61.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is a damping hydraulic shock absorber that adjusts the main damping force generated by a leaf valve as a damping valve by changing the amount of peripheral deflection of the leaf valve as a damping valve using a piezoelectric element. This invention relates to improvements in force adjustment devices.

0002

[Prior Art] As a conventional damping force adjustment device for a hydraulic shock absorber, the amount of deflection of the peripheral end of a leaf valve, which is a damping valve, is adjusted by applying voltage to a piezoelectric element, thereby changing the main damping force generated by the leaf valve. A method to do this is proposed in, for example, Japanese Patent Laid-Open No. 13041/1983.

This proposal has the disadvantage that the adjustment range 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, which is an electrostrictive member, and the piezoelectric element expands, the expansion force directly controls the amount of deflection of the peripheral end of a leaf valve, which is a damping valve for generating damping force. This adjusts the damping force generated by the leaf valve.

Therefore, with this prior art, it is not possible to change the amount of deflection of the peripheral end of the leaf valve beyond the amount of expansion of the piezoelectric element, and when a large amount of change in deflection is required at the peripheral end of the leaf valve, The number of piezoelectric elements installed in series must be significantly increased, and in this case, there is a disadvantage that the axial length of the entire damping force adjustment device increases significantly.

[0006] Therefore, the present applicant increased the amount of deflection of the peripheral end of the leaf valve, which is the damping valve, compared to the amount of expansion of the piezoelectric element, which is the electrostrictive member, to increase the adjustment range of the generated damping force. We have developed various damping force adjustment devices that are optimal for use in hydraulic shock absorbers (patent application No.
No. 214628).

[0007]

[Problems to be Solved by the Invention] However, the leaf valve, which is a damping valve of a hydraulic shock absorber equipped with the above-mentioned damping force adjustment device, has a metal long slidable valve support member on the back surface of its outer peripheral end, and this valve support member. Since the damping valve is supported by a coil spring that biases the damping valve in the closing direction, stable and high-speed switching of the damping valve may be hindered due to inertia and poor sliding between the valve support member and the coil spring when switching the damping force.

Furthermore, since a long member is used as the support member, there is a problem that the basic length of the hydraulic shock absorber itself in the axial direction becomes long.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a damping force adjusting device for a hydraulic shock absorber that can switch the damping valve quickly and stably when changing the damping force, and can shorten the overall basic length.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention has a structure in which a piston rod is movably inserted into a cylinder via a piston body, and the piston body has two oil chambers in the cylinder. The two oil chambers communicate with each other through the expansion side port and compression side port provided on the piston body, and the expansion side damping valve and the compression side damping valve provided at the outlet end of each port. is a hydraulic shock absorber that is provided in the piston rod and communicates with each other through the expansion side and compression side pilot passages that bypass the expansion side damping valve and the compression side damping valve. An elastic seal, such as a rubber O-ring, is interposed on the back surface to support each rebound damping valve and the compression damping valve, and an elastic seal such as a rubber O-ring is provided in each of the pilot passages to apply back pressure to the back surface of each rebound damping valve and compression damping valve. A first extension sub-valve and a first compression sub-valve to be supplied; a piezoelectric element that is provided in the piston rod and adjusts the amount of deflection of the first extension sub-valve and the first compression sub-valve by its own reverse piezoelectric action; The second expansion side is disposed on the exit side of the pilot passage and sets the damping force characteristics according to the speed of the piston rod.
It is characterized by providing a sub-valve and a second pressure-side sub-valve.

[0011]

[Operation] When the piston rod slides within the cylinder, the hydraulic oil from the so-called upstream oil chamber reaches the back side of each leaf valve that generates the main damping force via each first sub-valve, and This also extends to the pressure receiving surface side of each leaf valve, and by bending the peripheral end of each leaf valve and allowing the hydraulic oil to pass through, a predetermined damping force is generated on each side.

At this time, when a predetermined voltage is applied to the piezoelectric element, the amount of deflection of the peripheral end of each first sub-valve is adjusted according to the magnitude of the applied voltage, and the back of each leaf valve is adjusted. The respective pressures are adjusted, the amount of peripheral end deflection of each leaf valve is adjusted, and each damping force generated in each leaf valve is adjusted.

As a result, the damping force generated by each of the leaf valves can be changed within a range greater than the amount of expansion of the piezoelectric element.

Furthermore, when the application of voltage to the piezoelectric element is removed, the amount of deflection of the circumferential end of each first sub-valve returns to its old state;
As a result, the hydraulic pressure acting on the back surface of each leaf valve is also restored to its old state, and the damping force generated by each leaf valve is returned to the initially set magnitude.

On the other hand, each second sub-valve has a P-Q characteristic of 3.
Because it is a square-square characteristic, the back pressure mentioned above is relatively high in the low speed range of the piston rod to obtain a sufficient reduction range, and in the medium and high speed range, the back pressure is not excessively increased and oil suction is prevented. prevent. Furthermore, since elastic seals support each damping valve, the back pressure led to each rebound damping valve and compression damping valve is sealed, and there is no influence of inertia or poor sliding, which improves the switching performance of the damping valve. There are no negative effects,
Can be switched stably and quickly.

[0016]

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

FIG. 1 is a cross-sectional view of the main parts of a damping force adjusting device according to an 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 installed. It has a piston part 3 forming a section.

A piezoelectric element 4, which is an electrostrictive member, is disposed in a through hole 2a formed in the axial center of the hollow piston rod 2.

A lead wire (not shown) is connected to the piezoelectric element 4, and the end of the lead wire projects outward from the 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 forces on the expansion side and compression side, respectively.

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

The piston rod 2 has a tip spigot member 20 connected to its tip 2b, and the piston portion 3 is interposed on the outer periphery of the tip spigot member 20.

The piston part 3 has a piston body 30 that slides within the cylinder 1, and a compression side leaf valve 5, which is a compression side damping valve, and a compression side leaf valve, which is a compression side damping valve, which are arranged to sandwich the piston body 30. It has a valve 6.

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

Each of the leaf valves 5 and 6 is 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, and when each outer peripheral end is bent, a main body of a predetermined size Generates both rebound and compression damping forces.

That is, each of the leaf valves 5 and 6 has a nut-shaped spacer 50 and a nut-shaped spacer 50 disposed such that the inner peripheral end thereof faces the upper and lower inner end surfaces of the piston body 30, and the upper and lower end surfaces of the piston body 30. It is held between the step part 30g of the tip spigot member. Further, the back surface of each leaf valve 5, 6 is supported by elastic seals 51, 61 made of rubber O-rings or the like. Each elastic seal 51, 61 is connected to the housing 5
The leaf valves 5 and 6 are supported by the end faces of the leaf valves 5 and 6, and are bent by compressing the elastic seals 51 and 61. A hydraulic chamber 53 is provided on the back of each leaf valve 5, 6.
, 63 are formed, and these elastic seals 51, 6
1 and housings 54 and 64, respectively.

The hydraulic chambers 53 and 63 are connected to the pilot passage inside the tip spigot member 20 through the communication hole 50a formed in the spacer 50 and the communication holes 21b and 21c of the tip spigot member 20, respectively. It's communicating.

[0028] The tip pilot member 20 has a rod side oil chamber A.
A growth-side pilot passage and a compression-side pilot passage are provided which communicate the piston-side oil chamber B with the piston-side oil chamber B and bypass each growth-side damping valve and the compression-side damping valve, respectively. Inside each pilot passage, a first sub-valve 7 on the expansion side and a first sub-valve 8 on the compression side are provided on the back surface of each leaf valve 5, 6, that is, the first sub-valve 7 on the compression side, which supplies hydraulic pressure to each hydraulic chamber 53, 63.

That is, the tip spigot member 20 is integrally provided and consists of a rod portion 21 and a connecting portion 22 at the upper end.

Further, each of the first sub-valves 7 and 8 is provided in a cylindrical inner space 21a formed inside the rod portion 21.
It will be equipped with.

Each of the first sub-valves 7 and 8 has its circumferential end deflection amount changed by the expansion force generated in the piezoelectric element 4, and in this embodiment, each of the first sub-valves 7 and 8 is an annular leaf valve. It is configured to allow the flow of hydraulic oil through each of the first sub-valves 7 and 8 when the outer peripheral end is bent.

That is, the first expansion-side sub-valve 7 has the front end annular seat portion of the valve seat 71 in contact with its back surface.

The valve seat 71 is fitted into the inner cavity 21a.

[0034] The annular seat portion is brought into contact with the inner peripheral end of the back surface of the first sub-valve 7 on the expansion side.

Further, the first sub-valve 7 on the expansion side has an inner fixed portion and an outer seat portion of the lower portion of the valve spool 72 in contact with the upper pressure receiving surface thereof.

This valve spool 72 has an inner space 21a.
It is fitted so as to be slidable in the vertical direction, and has an annular groove between the inner peripheral side fixing part and the outer peripheral side seat part.

A port 72d passing through the thick upper part of the valve spool 72 is opened in the annular groove.

Therefore, the first extension sub-valve 7 in this embodiment has its inner peripheral end side sandwiched between the inner peripheral side fixed part of the valve spool 72 and the annular seat part of the valve seat 71. The outer peripheral end will be fixed in a flexible manner.

Therefore, when the hydraulic pressure from the growth side pilot passage acts on the outer peripheral end of the growth side first sub-valve 7, this bends downward in the figure, and at this time, a predetermined flow rate of hydraulic oil is ensured. be done.

However, since the inner peripheral end side of the growth side first sub-valve 7 is sandwiched between the innermost inner peripheral side fixing part and the annular seat part slightly closer to the outer periphery, the growth side first sub-valve 7 When the inner peripheral end of the expansion side sub-valve 7 is actively pressed against the inner peripheral fixed part using the annular seat part as a fulcrum, the outer peripheral end of the expansion side sub-valve 7 is pressed against the outer peripheral side seat part of the valve spool 72 by a so-called lever movement, and the expansion side The amount of deflection of the outer peripheral end of the first sub-valve 7 is changed, and the flow rate of the hydraulic oil is changed to decrease through the outer peripheral end of the growth-side first sub-valve 7.

On the other hand, the lower end annular seat portion of the valve seat 81 is brought into contact with the back surface of the first pressure side sub-valve 8 .

The valve seat 81 is housed in the inner cavity 21a so that it can move up and down, that is, in the axial direction of the rod surface 21.

The valve seat 81 has a port 81b formed in its thick part.
This allows communication between the pressure side leaf valve 6 side and the outside of the valve seat 81.

The annular seat portion is brought into contact with the inner circumferential end of the back surface of the first sub-valve 8 on the pressure side.

Further, in the pressure side first sub-valve 8, the inner peripheral side fixing part and the outer peripheral side seat part of the upper end of the valve spool 72 are brought into contact with the lower pressure receiving surface.

The valve spool 72 has an annular groove between the inner peripheral side fixing part and the outer peripheral side seat part,
A port 82d is opened in the annular groove and passes through the thick lower part of the valve spool 72.

Therefore, the pressure-side first sub-valve 8 in this embodiment has its inner peripheral end side sandwiched between the inner peripheral side fixed part of the valve spool 72 and the annular seat part of the valve seat 81, and its outer peripheral end side The ends will be flexibly anchored.

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

The inner circumferential end of the first pressure side sub-valve 8 is sandwiched between the innermost fixed part on the inner circumferential side and the annular seat part slightly closer to the outer circumference. When the end is actively pressed against the inner fixed part using the annular seat part as a fulcrum, the outer peripheral end of the pressure side sub-valve 8 becomes pressed against the outer peripheral side seat part of the valve spool 72 by a so-called lever movement, and the pressure side first The amount of deflection of the outer peripheral end of the sub-valve 8 is changed.

Therefore, 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 through the communication hole 21b formed in the rod portion 21 and the communication hole 50a formed in the spacer 50, respectively. respectively through the hydraulic chamber 5
3, and similarly flows into the hydraulic chamber 6 through the communication hole 21c.
3.

Further, on the upstream side of each of the first sub-valves 7 and 8, there is an expansion side port 3 which is opened in the piston body 30.
Hydraulic oil flows in through Oa and pressure side port 30b, respectively.

That is, the piston main body 30 has an extension side sub-port 30c, which is an extension pilot passage, opened from the inner peripheral surface near the lower end of the piston main body 30 to the lower end surface, and extends from the inner peripheral surface near the upper end of the piston main body 30. A pressure side sub-port 30d serving as a pressure side pilot passage is opened from the piston body 30 to the upper end surface of the piston body 30.

[0054] Each sub-port 30c, 30d is
The inner circumferential surface of the piston body 30 communicates with communication holes 21d and 21e opened in the adjacent rod portion 21, and communicates with the inner cavity 21a of the rod portion 21 and each port 72d through these communication holes 21d and 21e. , 82d, respectively.

Further, each of the sub-ports 30c and 30d communicates with each of the ports 30a and 30b through annular grooves formed in the upper and lower end surfaces of the piston body 30, respectively.

Further, a steel ball 43 is disposed between the valve seat 81 and the piezoelectric element 4, and under the alignment structure using the steel ball 43, when a predetermined voltage is applied to the piezoelectric element 4, the piezoelectric The expansion force generated by the element 4 acts on the member.

The housing 54 is screwed onto the spacer 50 and forms a port 90 that communicates the hydraulic chamber 53 and the piston-side oil chamber B in the axial direction, and a second expansion-side sub-valve is provided at the outlet end of the port 90 so as to be openable and closable. It is located in

Similarly, the upper housing 64 also has a hydraulic chamber 6.
3 to the rod side oil chamber A, and a pressure side second sub-valve 104 is provided at the outlet end of this port 91 so as to be openable and closable.

In the hydraulic shock absorber according to this embodiment formed as described above, each port 3 of the piston body 30
When 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 flowing through each first sub-valve 7 and 8 through each sub-port 30c and 30d.
This will extend to the pressure-receiving surface side of the

Further, the hydraulic oil via the first sub-valves 7 and 8 on each side flows into the hydraulic chambers 53 and 63 formed on the back side of each leaf valve 5 and 6, and therefore, each leaf valve This will suppress the amount of deflection of the outer peripheral ends of Nos. 5 and 6.

The amount of deflection of the outer peripheral end of each first sub-valve 7, 8 is controlled by a predetermined voltage applied to the piezoelectric element 4. When the amount of deflection of the outer peripheral end of the first sub-valve 7, 8 on each side is changed in the direction of decreasing, the hydraulic pressure that was previously supplied to the back surface of each leaf valve 5, 6 will be reduced, and therefore , the amount of deflection of the outer peripheral end of each leaf valve 5, 6 increases, and the damping force generated in each leaf valve 5, 6 is adjusted to decrease. Each leaf valve 5, 6, which is a damping valve that generates a predetermined damping force during the expansion and contraction operation of the hydraulic shock absorber, has its inner peripheral end deflection amount changed when the voltage application to the piezoelectric element 4 is reduced, and the generated damping is reduced. The force will be adjusted to a higher tendency.

In this case, when a voltage is applied to the piezoelectric element 4, the expansion force generated in the piezoelectric element 4 can be controlled by changing the amount of deflection of the outer peripheral end of each first sub-valve 7, 8. The flow rate of the hydraulic oil passing through the outer circumferential ends of the leaf valves 5, 8 is restricted, thereby changing the flow rate of the hydraulic oil flowing into the back side of each leaf valve 5, 6, and reducing the main This will change the damping force.

As a result, it is possible to make the amount of change in deflection of the outer peripheral end of each leaf valve 5, 6 extremely large compared to the amount of expansion of the piezoelectric element 4.
Each damping force generated by the piezoelectric element 6 can be adjusted within a wide range compared to the amount of expansion of the piezoelectric element 4.

[0064] Furthermore, the pilot flow 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, after pushing these apart and passing through. , hydraulic chamber 53,
63 and applies back pressure to each leaf valve 5, 6 via this hydraulic chamber 53, 63, the oil flows through ports 90, 9.
1, the second expansion-side sub-valve 96 and the second compression-side sub-valve 104 are pushed open, and the oil flows out into the piston-side oil chamber B and the rod-side oil chamber A, respectively.

At this time, the back pressure applied to each leaf valve 5, 6 depends on the characteristics of each second sub-valve 96, 104,
That is, since the P-Q characteristic is a 2/3 characteristic, it becomes relatively high in the low speed range of the piston rod 2, but does not become very high in the medium and high speed range.

Therefore, when the piston rod 2 operates at a low speed, a sufficient damping width is ensured, and when the piston rod 2 operates at a medium or high speed, the hard damping force does not increase significantly, which may cause poor oil suction on the compression side. No worries.

Furthermore, since each of the first sub-valves 7 and 8 is supported by a single integrally formed spool, the movement of the piezoelectric element 4 can be controlled with high sensitivity. It is possible to simplify the configuration and reduce costs.

[0068]

As described above, according to the present invention, a first growth-side sub-valve and a first compression-side sub-valve are provided in the pilot passage, and a second growth-side sub-valve and a compression-side sub-valve are further provided on the outlet side of the pilot passage. Since it is configured to set the damping force characteristics according to the speed of the piston rod,
Compared to the expansion amount of the piezoelectric element, it is possible to make the amount of change in the circumferential deflection of each side leaf valve extremely large. Therefore, the damping force on each side generated by each side leaf valve can be reduced by the expansion amount of the piezoelectric element. It has the advantage of being able to be adjusted over a wide range compared to .

In addition, sufficient reduction adjustment is ensured even in the low speed range of the piston rod, and in the medium and high speed range, the hard damping force is not so high as to cause poor oil suction, especially on the compression side, and the structure is simplified. The effect of being able to achieve this goal is obtained.

Furthermore, since the back of the damping valve is supported by an elastic seal, there is no need to worry about inertia or poor sliding, and since the oil pressure on the back of the damping valve is sealed, the damping valve is stable and highly efficient. Switching becomes possible.

Furthermore, since the elastic seal is thin, the installation space is shortened, and the basic length of the hydraulic shock absorber can be shortened.

[Brief explanation of the drawing]

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

[Explanation of symbols]

1 Cylinder 2 Piston rod 4 Piezoelectric element 5 Leaf valve as a damping valve on the expansion side 6 Leaf valve as a damping valve on the compression side 7 First sub-valve on the expansion side 8 First sub-valve on the compression side 51 Elastic seal 61 Elastic seal 96 Second sub-valve on the expansion side 104 Second compression side Sub valve A Rod side oil chamber B Piston side oil chamber

Claims (1)

[Claims] Claim 1: A piston rod is movably inserted into the cylinder via a piston body, the piston body defines two oil chambers in the cylinder, and the two oil chambers are connected to an expansion side port provided in the piston body. The compression side port communicates with the rebound damping valve and the compression damping valve provided at the outlet end of each port, and two oil chambers are provided in the piston rod to communicate with the rebound damping valve and the compression damping valve. in a hydraulic shock absorber that communicates with the expansion side and compression side pilot passages bypassing the expansion side damping valve and the compression side damping valve, and supporting each expansion side damping valve and the compression side damping valve by being interposed on the back surface of each of the expansion side damping valve and the compression side damping valve. an elastic seal, a first expansion-side sub-valve and a first compression-side sub-valve provided in each of the pilot passages to supply back pressure to the rear surfaces of each of the expansion-side valves and compression-side valves; A piezoelectric element that adjusts the amount of deflection of the first expansion-side sub-valve and the first compression-side sub-valve by reverse piezoelectric action, and a piezoelectric element disposed on the exit side of each pilot passage to set damping force characteristics according to the speed of the piston rod. The second sub-valve on the rebound side and the second sub-valve on the compression side
A damping force adjustment device for a hydraulic shock absorber, characterized in that it is provided with a sub-valve.