JPH0454340A - Hydraulic shock absorber of variable damping force - Google Patents

Abstract

PURPOSE:To obtain a damping force generating system capable of varying the damping force characteristic continuously, shortening the operation time and responding quickly by varying the set load of a disc valve mechanism by means of applying voltage on a piezoelectric particle thereby causing it to expand and contract. CONSTITUTION:For instance, in a case of the contracting side of a piston rod 3, if it is left in a shortened condition without applying voltage on a piezoelectric actuator 11, a valve body 9 impinging on a valve seat 8 flags by virtue of a spring 12 and moves along the piston rod 3 toward a piston 2 side causing the set load of a disc valve mechanism 10 to become heavier and the valve opening pressure bigger. On the other hand, if voltage is applied to the piezoelectric actuator 11 and expanded, the valve body 9 resisting against the spring 12 moves toward the end of the piston rod 3 causing the set load of the disc valve mechanism 10 to become smaller and valve opening pressure smaller. Thus the damping force characteristic can be varied by variation of the valve opening pressure and, because expansion and contraction of the piezoelectric actuators 11 and 18 is in proportion to the voltage applied, the damping force characteristic can be established freely.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable damping force hydraulic shock absorber used in a suspension system for a vehicle such as an automobile.

(Prior Art) For example, in automobiles, the damping force characteristics of hydraulic shock absorbers installed in suspension systems are used to provide ride comfort or handling stability according to the specifications of the automobile, such as a sports type or a luxury car. Set. However, even for the same vehicle, the desired damping force characteristics differ depending on conditions such as the loaded weight, the road surface, and the speed at which the vehicle is traveling. Therefore, some vehicles are equipped with variable damping force hydraulic shock absorbers that can adjust damping force characteristics depending on the situation.

Conventionally, variable damping force hydraulic shock absorbers have multiple oil passages equipped with a damping force generation mechanism on a piston slidably fitted into a cylinder filled with oil, and an oil passage selected by an external actuator. Some are equipped with a switching valve that opens and closes automatically. With this configuration, several types of damping force characteristics are obtained by selecting the oil passage through which the oil flows as the piston slides, using the switching valve.

(Problems to be Solved by the Invention) However, the conventional variable damping force type hydraulic shock absorber has the following problems.

Since oil passages equipped with damping force generating mechanisms of respective characteristics are required depending on the number of desired damping force characteristics, the structure becomes complicated when there are many damping force characteristics to be obtained.

In addition, it is necessary to provide an actuator externally, and since it takes time for the actuator to operate when operating the switching valve, there is a problem that a response delay occurs when controlling the damping force characteristics in real time according to the driving situation.

The present invention has been made in view of the above points, and provides a variable damping force hydraulic shock absorber equipped with a damping force generation mechanism that can continuously change damping force characteristics and has a short operating time and quick response. The purpose is to

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention controls the flow of oil that occurs in a communication passage that communicates two partitioned chambers by sliding a piston in a cylinder. A variable damping force hydraulic shock absorber that generates a damping force is provided with a disc valve mechanism that opens and closes the communication passage, and the relative position in the axial direction between the support part of the valve body of the disc valve mechanism and the valve seat is adjusted by expansion and contraction. The present invention is characterized in that a piezoelectric element to be moved is provided, and the set load of the disc valve mechanism is changed by applying a voltage to the piezoelectric element to cause it to expand and contract.

(Function) With this configuration, by changing the applied voltage to expand and contract the piezoelectric element, it is possible to change the set load of the disc valve mechanism and change the valve opening pressure.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 shows the main parts of the variable damping force type hydraulic shock absorber of this embodiment.

In FIG. 1, a piston 2 that partitions the inside of the cylinder 1 into two chambers, an upper chamber 1a and a lower chamber 1b, is slidably fitted into a cylinder 1 filled with oil. The base end of a piston rod 3 is inserted into the piston 2 and fixed with a nut 5 through a sleeve 4, so that the piston 2 moves in the oil as the piston rod 3 expands and contracts. . A contraction side passage 6 and an expansion side passage 7 are bored in the piston 2 as communication passages that communicate the upper chamber 1a and the lower chamber lb. A disk consisting of an annular valve seat 8 formed on the piston 2 so as to close the contraction side passage 7 on the end face of the upper chamber 1a of the piston 2, and an annular flexible valve body 9 fitted onto the piston rod 3. A valve mechanism 10 is provided. The valve body 9 is held between a cylindrical piezoelectric actuator 11 provided on the piston 2 side and a spring 12 provided on the distal end side of the piston rod 3 via a retainer 13 and a retainer 14 .

Similarly, an extension passageway 6 is formed on the end surface of the piston 2 on the lower chamber 1b side.
A disc valve mechanism 17 consisting of a valve seat 15 and a flexible valve body 16 is provided so as to close the valve seat 15, and the valve body 16 is connected to a cylindrical piezoelectric actuator I8 provided on the piston 2 side and the base of the piston rod 3. Spring 19 provided on the end side
They are sandwiched between the retainers 20 and 21. The disc valve mechanism 10 is opened when the valve body 9 is bent by the pressure of the oil in the contraction side passage 7 when the piston rod 3 is shortened, and the disc valve mechanism 17 is opened when the piston rod 3 is extended. The valve body 16 is bent by the pressure of the oil in the side passage 6, thereby opening the valve.

Further, the piston 2 is provided with an orifice passage (not shown) that constantly communicates the upper chamber 1a and the lower chamber 1b with a small passage area. Support part of valve body 9 (piezoelectric actuator 1
1 and spring 12 via retainer 13 and retainer 14) and the supporting portion of valve body 16 (portion sandwiched between piezoelectric actuator 18 and barb 19 via retainer 20 and retainer 21) are piezoelectric. By moving along the piston rod 3 due to the expansion and contraction of the actuator 11.18 and the elastic force of the spring 12j9, the support portion of the valve body 9 and the valve seat 8 and the support portion of the valve body 16 and the valve seat work 5 are moved.
It is designed to move the relative position in the axial direction. By changing the deflection of the valve bodies 9, 16 due to contact with the valve seat 8.15, the disc valve mechanism 10.1
7 set load can be changed. The piezoelectric actuator 11.18 is formed into a cylindrical shape by stacking annular thin plates of piezoelectric material, and expands and contracts in the axial direction in response to an applied voltage. The piston rod 3 is provided with an axial hole 22 having an opening facing the piezoelectric actuator 11.18, and a conducting wire 23 and a wire connecting the piezoelectric actuator 11 and a voltage control device (not shown) are formed in the hole 22. A conductive wire 24 is inserted through which connects the piezoelectric actuator 18 and a voltage control device (not shown). In the figure, 25 is a sealing member.

The operation of this embodiment configured as above will be explained next.

When the piston speed due to the expansion and contraction of the piston rod 3 is small, the disc valve mechanisms IO and J7 are in a closed state, and the oil flows through the orifice passage (not shown) provided in the piston 2, so that the speed shown in FIG. It generates damping forces indicated by medium A (extension side) and a (contraction side).

When the piston speed due to the expansion and contraction of the piston rod 3 reaches a predetermined speed, when the piston rod 3 is shortened, the valve body 9 is bent by the pressure of the oil in the contraction side passage 7, and the disc valve mechanism IO is opened and the contraction side passage is closed. By flowing the oil through 7, a damping force having the orifice characteristics shown in FIG. 4 is generated. Further, when the piston rod 3 is extended, the valve body 16 is bent by the pressure of the oil in the extension passage 6, and the disc valve mechanism 17 is opened, allowing the oil to flow through the extension passage 6, as indicated by B in FIG. Generates damping force.

Here, since the pressure at which the disc valve mechanisms 10 and 17 open is proportional to the set load of the disc valve mechanisms IO and 17, the piezoelectric actuators 11 and 18
can be changed by moving the supporting parts of the valve bodies 9 and 16 along the piston rod 3 by applying a voltage with a voltage control device to expand and contract them.

Hereinafter, the contraction side of the piston rod 3 will be explained as an example.

When the piezoelectric actuator 11 is in the shortened state without applying a voltage, the valve body 9 in contact with the valve seat 8 is bent by the spring 12 and moved along the piston rod 3 toward the piston 2, as shown in FIG. It is in a moving state. Then, as the set load of the disc valve mechanism 10 increases (the valve opening pressure of the disc valve mechanism 10 increases), damping force characteristics as shown in FIG. 4 (B on the extension side) are obtained.

By applying a voltage to the piezoelectric actuator 11 and causing it to expand, the valve body 9 moves along the piston rod 3 toward the tip end of the piston rod against the elastic force of the spring 12.

Then, the set load of the disc valve mechanism 10 becomes smaller, the valve opening pressure of the disc valve mechanism 10 becomes smaller, and the damping force characteristics as shown in FIG. 4 (B on the extension side) are obtained.

Furthermore, by increasing the applied voltage, the piezoelectric actuator 11
The disk valve mechanism I is extended as shown in Fig. 3.
If O is always kept open, b3 in Fig. 4 (B on the extension side)
The damping force characteristics shown in 3) are obtained. The bending point in FIG. 4 indicates the opening of the disc valve mechanism IO.

In this way, by changing the voltage applied to the piezoelectric actuators 11 and 18, the disc valve mechanisms 10 and 1
By changing the valve opening pressure 7, the damping force characteristics can be changed as shown in FIG. Furthermore, since the expansion and contraction of the piezoelectric actuators 11 and 18 is proportional to the applied voltage, the damping force characteristics can be freely set between B1 and B (b) in FIG. The damping force characteristics on the compression side and the expansion side are determined by the piezoelectric actuator 11.
and I8, so the damping force characteristics on the compression side and the expansion side can be controlled independently. Furthermore, the response speed of the piezoelectric actuator's expansion and contraction due to the application of voltage is as fast as several meters per second, so it is possible to control the damping force retention in real time according to the driving situation.

In addition, in the embodiment shown in FIG.
Disc valve mechanism 10.1 by moving the
For example, as shown in FIG. 5, annular valve seats 26 and 27 are provided separately from the piston 2, and the gap between the valve seats 26 and 27 and the piston 2 is piezoelectric actuators 28 and 29 interposed in
Also by expanding and contracting the disc valve mechanism 10.
17 set loads can be changed. In FIG. 5, members corresponding to those in FIG. 1 are given the same numbers.

In addition, in this example, the case where the present invention is applied to a damping force generation mechanism provided in a piston has been explained.
The present invention is not limited to this, but can also be applied, for example, to a damping force generation mechanism of a base valve provided at the bottom of a cylinder.

(Effects of the Invention) As described in detail above, the present invention generates a damping force by controlling the flow of oil generated in a communication passage that communicates two partitioned chambers by sliding a piston in a cylinder. A variable damping force type hydraulic shock absorber is provided with a disc valve mechanism that opens and closes the communication passage, and a piezoelectric element that moves the relative position in the axial direction of the support part of the valve body of the disc valve mechanism and the valve seat by expansion and contraction, By applying a voltage to the piezoelectric element and causing it to expand and contract, the set load of the disc valve mechanism can be changed. As a result, the damping force characteristics can be changed by changing the voltage applied to the piezoelectric element and changing the valve opening pressure of the disc valve mechanism.

Further, since the expansion and contraction of the piezoelectric element is proportional to the applied voltage, the damping force characteristics can be changed continuously. Furthermore, since the response speed of the piezoelectric actuator's expansion and contraction due to the application of voltage is as fast as several meters per second, it is possible to control the damping force characteristics in real time according to the driving conditions, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the main parts of an integrated embodiment of the present invention, and FIG. 2 is an enlarged view of the main parts of the apparatus shown in FIG. , Fig. 3 is an enlarged view of the main parts of the device shown in Fig. 1 with the valve body of the disc valve mechanism moved to the tip side of the piston rod, and Fig. 4 shows the damping force characteristics of the device shown in Fig. 1. FIG. 5 is a vertical cross-sectional view of a main part of another embodiment of the present invention. l...-Cylinder 1a...Upper chamber 1b...Lower chamber 2...Piston 6...Elongation side passage 7...Compression side passage 8.15...-Valve seat 9.16... Valve body special 10.17 26.27 28.29 - Disc valve mechanism... Piezoelectric actuator (piezoelectric element)... Valve seat... Piezoelectric actuator (piezoelectric element) Engraving of drawings of patent applicant Tokiko Co., Ltd. (No change in content) Figure B Figure 4 Figure Procedure Amendment (Method) % Formula % Title of Invention: Variable damping force hydraulic shock absorber 3. Person making an amendment Related to the case Patent applicant name Tokico Co., Ltd. 5 Ochanomizu Square Building B, 1-6 Kanda Surugadai, Chiyoda-ku, Tokyo. Date of amendment order: September 10, 1990 (Shipping date: September 25, 1990)

Claims (1)

[Claims] (1) In a hydraulic shock absorber that generates damping force by controlling the flow of oil generated in a communication path that communicates two compartmented chambers by sliding a piston in a cylinder, a disk that opens and closes the communication path. A valve mechanism is provided, and a piezoelectric element is provided that moves the relative position in the axial direction between the support part of the valve body of the disk valve mechanism and the valve seat by expansion and contraction, and the disk is moved by applying a voltage to the piezoelectric element to cause it to expand and contract. A variable damping force hydraulic shock absorber characterized by changing the set load of the valve mechanism.