JPH0828619A - Hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To suppress an excessive increase in attenuation force in the area where piston speed is remarkably large in a hydraulic buffer. CONSTITUTION:A piston 3 is fitted in a cylinder 2. Upper and lower chambers 2a, 2b in respect to a cylinder are communicated with each other through extention side passages 15, 18, an extention side chamber 13, contraction side passages 16, 19, and a contraction side chamber 14. An orifice 21 and disc valves 22, 23 are arranged in the extention side passage 15 and the contraction side passage 19. The upper and lower chambers 2a, 2b in respect to the cylinder are communicated with each other through bypass passages 17, 20, and a circular valve chamber 12. A disc valve 24 is fitted in the valve chamber 12. An outer peripheral part of one end abuts against an outer valve seat 25 of the valve chamber 12, while an inner peripheral part of the other end abuts against an inner valve seat 26. Normally, Attenuation force is generated by the orifice 21 and the disc valves 22, 23. In the area where piston speed is remarkably large, the disc valve 24 is flexed, the outer periphery or the inner peiphery is separated from the outer or inner valve seat 25, 26. The bypass passages 17, 20 are communicated with each other for suppressing excessive increase of attenuation force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile.

[0002]

2. Description of the Related Art Generally, a hydraulic shock absorber mounted in a suspension system of a vehicle such as an automobile has a piston in which a piston rod is connected slidably fitted in a cylinder in which an oil liquid is sealed, and is defined by the piston. The two chambers in the selected cylinder are communicated with each other by an oil liquid passage, and a damping force generating mechanism including an orifice and a disk valve arranged in parallel with the oil liquid passage is provided.

Then, the flow of the oil liquid generated in the oil liquid passage due to the sliding of the piston in the cylinder accompanying the expansion and contraction of the piston rod is controlled by the orifice and the disc valve to generate the damping force. At this time, in a region where the piston speed is low, the damping force has a damping force characteristic (orifice characteristic) in which the damping force increases in a quadratic curve as the piston speed increases due to the restriction of the orifice. Further, in a region where the piston speed is high, the disc valve is opened and the flow passage area of the oil liquid is expanded, so that the damping force linearly increases with the increase of the piston speed (valve characteristic).

As described above, by changing the damping force characteristic according to the piston speed, it is possible to suppress an excessive increase in the damping force with respect to a large input of the piston speed caused by passing through a protrusion or a depression on the road surface. It is designed to improve driving stability and riding comfort.

Further, by combining a damping force adjusting hydraulic shock absorber capable of appropriately adjusting the damping force characteristic by providing a damping force adjusting valve for adjusting the flow passage area of the oil liquid, an actuator and a controller, road surface conditions and running There is a suspension control device that improves riding comfort and steering stability by automatically switching the damping force in real time according to the situation.

[0006]

However, in the conventional hydraulic shock absorber provided with the orifice and the disc valve, the damping force is determined by the passage area where the oil liquid passage is fixed after the disc valve is fully opened. Therefore, when the piston speed becomes higher, the increasing tendency of the damping force becomes larger, and a larger damping force than necessary is generated to deteriorate the riding comfort.

Further, since the suspension control device as described above requires expensive damping force adjusting hydraulic shock absorbers, actuators, controllers and various sensors,
There is a problem that the cost becomes very high.

The present invention has been made in view of the above points, and provides a hydraulic shock absorber having a simple structure and effectively suppressing an excessive increase in damping force in a region where the piston speed is very high. The purpose is to provide.

[0009]

In order to solve the above-mentioned problems, the present invention defines a cylinder in which an oil liquid is enclosed and a cylinder slidably fitted in the cylinder so that the inside of the cylinder is divided into two chambers. A piston that is formed, a piston rod that has one end connected to the piston and the other end that extends to the outside of the cylinder, and a main oil liquid passage that connects the two chambers in the cylinder.
In a hydraulic shock absorber comprising a damping force generation mechanism that controls the flow of oil liquid in the main oil liquid passage to generate a damping force,
The piston is provided with an annular valve chamber and a bypass passage that connects the two chambers in the cylinder via the valve chamber, and an outer valve seat extending in the circumferential direction is provided on the outer peripheral wall of the valve chamber so as to project. An inner valve seat that extends along the circumferential direction is provided on the inner peripheral wall in a protruding manner.
Further, an annular disc valve was fitted in the valve chamber so that the outer peripheral portion of one end surface of the disc valve abuts the outer valve seat and the inner peripheral portion of the other end surface abuts the inner valve seat. It is characterized by

[0010]

With this structure, the damping force generating mechanism controls the flow of the oil liquid generated in the main oil liquid passage due to the sliding of the piston in the cylinder accompanying the expansion and contraction of the piston rod to generate the damping force. Let Then, when the piston speed becomes extremely high and the pressure in one of the two chambers in the cylinder reaches a predetermined pressure, the disc valve bends and its inner or outer peripheral portion separates from the inner or outer valve seat. The two chambers in the cylinder are communicated with each other via the bypass passage to suppress an excessive increase in damping force. Further, since the disc valve is opened by bending in both directions, one disc valve can open and close the bypass passage during the extension stroke and the contraction side stroke.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. 1 and 2, the left side of the drawing shows the state of the piston rod during the expansion stroke, and the right side thereof shows the state of the contraction stroke.

As shown in FIG. 1, a hydraulic shock absorber 1 according to this embodiment has a piston 3 in a cylinder 2 in which an oil liquid is sealed.
Is slidably fitted, and the interior of the cylinder 2 is defined by the piston 3 into a cylinder upper chamber 2a and a cylinder lower chamber 2b. The piston 3 has a piston rod 4
Is connected to one end of the piston rod, and the other end of the piston rod is
It is inserted into a rod guide and an oil seal (not shown) attached to the end of the cylinder 2 and extends to the outside of the cylinder 2.

An outer cylinder 5 is provided on the outer circumference of the cylinder 2.
A reservoir chamber 6 is formed between the cylinder 2 and the outer cylinder 5, and the cylinder lower chamber 2b and the reservoir chamber 6 are appropriately distributed through a base valve (not shown) provided at the bottom of the cylinder 2. It is communicated with resistance. The reservoir chamber 6 is filled with oil liquid and gas, and the volume change in the cylinder 2 due to the intrusion and retreat of the piston rod 4 is compensated by the compression and expansion of the gas.

The piston 3 comprises a bottomed cylindrical piston member 7 slidably fitted in the cylinder 2, and a bottomed cylindrical valve member 8 fitted in the piston member 7. The small diameter portion 4a on one end side of the piston rod 4 is penetrated through these, and a nut 9 is screwed to the tip portion thereof, so that they are integrally connected to the piston rod 4. The tip of the small-diameter tubular portion 10 of the valve member 8 abuts the bottom of the piston member 7, and the large-diameter bottom 11 is fitted to the side wall of the piston member 7. An annular valve chamber 12 is formed between the annular valve chamber 12 and the annular portion 10. Also,
The inner side of the tubular portion 10 is formed by a partition wall (not shown) and the small diameter portion 4a of the piston rod 4 so that the expansion side chamber 13 and the compression side chamber 14
It is divided into 2 rooms.

At the bottom of the piston member 7, there is a cylinder lower chamber.
An extension-side main passage 15 that communicates 2b with the extension-side chamber 13, a compression-side passage 16 that communicates with the compression-side chamber 14, and a bypass passage 17 that communicates with the valve chamber 12. In addition, at the bottom of the valve member 8, an extension side passage 18 that communicates the cylinder upper chamber 2a with the extension side chamber 13 and a compression side passage that communicates with the compression side chamber 14.
A bypass passage 20 communicating with the valve chamber 12 is provided.

Then, the extension side passages 15 and 18 and the extension side chamber
An extension-side main oil liquid passage that connects the cylinder upper chamber 2a and the cylinder lower chamber 2b is formed by 13, and the contraction-side passage
The contraction-side main oil liquid passages that connect the cylinder upper chamber 2a and the cylinder lower chamber 2b are formed by the contraction side chambers 16 and 19. Further, the cylinder upper and lower chambers 2a and 2b are communicated with each other through the valve chambers 12 by the bypass passages 17 and 20.

At the end of the bottom of the piston member 7 on the cylinder lower chamber 2b side, an orifice for narrowing the passage area of the extension passage 15 is formed.
And a disc valve 22 that opens by receiving the pressure of the oil liquid on the extension side chamber 13 side, that is, the cylinder upper chamber 2a side, and controls the flow of the oil liquid in the extension side passage 15 to generate a damping force. A force generating mechanism is provided. Further, the end of the bottom of the valve member 8 on the cylinder upper chamber 2a side is opened by receiving pressure on the compression side chamber 14 side, that is, the cylinder lower chamber 2b side to open the compression side passage 19 to the cylinder upper chamber 2a. A damping force generation mechanism including a disc valve 23 that allows the flow of the oil liquid, controls the flow of the oil liquid to generate a damping force, and blocks the flow of the oil liquid in the opposite direction is provided.

An annular disc valve 24 is assembled in the valve chamber 12 to shut off the communication between the bypass passages 17 and 20. On the inner peripheral surface of the side wall of the piston member 7, that is, the outer peripheral wall of the valve chamber 12, an annular outer valve seat 25 extending in the circumferential direction is provided in a protruding manner. Also, the tubular portion of the valve member 8
On the outer peripheral surface of 10, that is, the inner peripheral wall of the valve chamber 12, the outer valve seat 25
An inner valve seat 26, which extends in the circumferential direction so as to face the above, is provided in a protruding manner. The disc valve 24 has its outer peripheral portion on one end surface abutting on the outer valve seat 25 of the piston member 7, and the inner peripheral portion on the other end surface abutting on the inner valve seat 26 of the valve member 8 and is held between them. There is. In this case, the disk valve 24 is pressed by the outer valve seat 25 and the inner valve seat 26, and is supported in a state where the inner and outer peripheral portions are bent in the axial direction, and the initial load corresponding to the predetermined valve opening pressure is applied. Is set.

When the pressure on the cylinder upper chamber 2a side reaches a predetermined pressure, the disc valve 24 bends on the inner peripheral side and separates from the inner valve seat 26 to allow communication between the bypass passages 17 and 20, and When the pressure on the lower cylinder chamber 2b side reaches a predetermined pressure, the outer peripheral side bends and separates from the outer valve seat 25 to bypass the bypass passage.
It connects 17 and 20. The opening pressure of the disc valve 24 is the disc valve in the main oil passage.
It is set higher than 22 and 23.

The operation of the present embodiment configured as above will be described below.

As shown in FIG. 1, during the expansion stroke of the piston rod 4, the oil liquid on the cylinder upper chamber 2a side is expanded side passage 1
8, flow to the cylinder lower chamber 2b side through the extension side chamber 13 and the extension side passage 15. At this time, in the region where the piston speed is low, the damping force of the orifice characteristic is generated by the restriction of the orifice 21, and in the region where the piston speed is high, the pressure on the cylinder upper chamber 2a side rises to open the disc valve 22 to open the valve. A characteristic damping force is generated.

During the compression stroke, in the region where the piston speed is low, the oil liquid on the cylinder lower chamber 2b side flows through the orifice 21 to the cylinder upper chamber 2a side through the extension side passage 15, the extension side chamber 13 and the extension side passage 18 and extends. As in the case of the stroke, the restriction of the orifice 21 produces a damping force of the orifice characteristic. In the region where the piston speed is high, the pressure in the cylinder lower chamber 2b rises to open the disc valve 23,
A damping force having a valve characteristic is generated by flowing to the cylinder upper chamber 2a side through the compression side passage 16, the compression side chamber 14 and the compression side passage 19.

When the piston speed further increases, as shown in FIG. 2, the pressure on the cylinder upper chamber 2a side rises during the extension stroke, and this pressure causes the inner peripheral side of the disc valve 24 to bend and the inner valve Open from the seat 26,
The bypass passages 17 and 20 are communicated with each other via the valve chamber 12. As a result, the oil liquid on the cylinder upper chamber 2a side flows to the cylinder lower chamber 2b side through the bypass passage 20, the valve chamber 12 and the bypass passage 17 in addition to the main oil liquid passage on the extension side. The rise can be suppressed.

During the compression stroke, the pressure on the cylinder lower chamber 2b side rises, and this pressure causes the outer peripheral side of the disk valve 24 to bend and separate from the outer valve seat 25 to open the valve chamber 12
The bypass passages 17 and 20 are communicated with each other via. As a result, the oil liquid on the cylinder lower chamber 2b side is added to the bypass passage 17, the valve chamber 12 and the bypass passage 20 in addition to the main oil liquid passage on the contraction side.
Since it flows through the cylinder to the cylinder lower chamber 2b side, it is possible to suppress an excessive increase in the damping force.

Thus, even in a region where the piston speed is very high, it is possible to suppress an excessive increase in damping force and improve the riding comfort of the vehicle.

The hydraulic shock absorber 1 bends the inner peripheral side or the outer peripheral side of the disc valve 24 to establish communication between the bypass passages 17 and 20 so that the bypass passage is extended and contracted.
Since 17 and 20 are also used, the desired effect can be achieved with a simple structure.

Further, the disc valve 24 is assembled by inserting the disc valve 24 into the piston member 7 and then the outer valve seat 25.
This can be easily done by fitting the valve member 8 into the piston member 7 and pressing the inner valve seat 26 against the disc valve 24 after it has been placed on top.

Further, the valve opening pressure of the disc valve 24 is set by appropriately shifting the formation positions of the outer and inner valve seats 25 and 26 of the piston member 7 and the valve member 8 in the axial direction, or by setting the tubular portion 10 of the cylindrical portion 10. This can be easily adjusted by adjusting the initial deflection amount of the disc valve 24 by appropriately changing the length. Further, the spring constant of the disk valve 24 can be changed by appropriately changing the protrusion amounts of the outer and inner valve seats 25 and 26 in the radial direction or by appropriately changing the radius of the tubular portion 10.

In the present embodiment, the inner peripheral side of the disc valve 24 is bent by the pressure of the oil liquid on the cylinder upper chamber 2a side to be separated from the inner valve seat 26, and the oil on the cylinder lower chamber 2b side is separated. Although the outer peripheral side of the disc valve 24 is bent by the pressure of the liquid and is separated from the outer valve seat 25, the bypass passages 17 and 20 are communicated with each other.
And the inner valve seat 26 in the axial direction are reversed and the cylinder upper chamber
The pressure on the side 2a deflects the outer peripheral side of the disc valve 24 to separate it from the outer valve seat 25, and the pressure on the lower cylinder chamber 2b side deflects the inner peripheral side of the disc valve 24 from the inner valve seat 26. You may make it sit down.

[0030]

As described above in detail, in the hydraulic shock absorber of the present invention, the piston speed is increased because the piston is provided with the annular valve chamber and the bypass passage and the disc valve is provided in the valve chamber. When the pressure in either one of the two chambers reaches a predetermined pressure, the disc valve bends and its inner peripheral portion or outer peripheral portion separates from the inner valve seat or the outer valve seat, and the inside of the cylinder passes through the bypass passage. The two chambers are communicated with each other to prevent an excessive increase in damping force. Further, since the disc valve is opened by bending in both directions, one disc valve can open and close the bypass passage during the extension stroke and the contraction side stroke. As a result, it is possible to suppress the excessive increase of the damping force in the region where the piston speed is very high, and it is possible to improve the riding comfort of the vehicle. Moreover, since the expansion passage and the contraction side also serve as bypass passages, the desired effect can be achieved with a simple structure.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of essential parts showing a normal operating state of a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part showing an operating state when the piston speed is very high in the device of FIG.

[Explanation of symbols]

 1 Hydraulic shock absorber 2 Cylinder 2a Cylinder upper chamber 2b Cylinder lower chamber 3 Piston 4 Piston rod 15,18 Expansion side passage (main oil liquid passage) 16,19 Compression side passage (main oil liquid passage) 17,20 Bypass passage 21 Orifice (Damping force generating mechanism) 22,23 Disc valve (Damping force generating mechanism) 24 Disc valve 25 Outer valve seat 26 Inner valve seat

Claims (1)

[Claims] 1. A cylinder in which an oil liquid is sealed, a piston slidably fitted in the cylinder to define two chambers in the cylinder, one end of which is connected to the piston and the other end of which is the cylinder. A piston rod extended to the outside of
A hydraulic shock absorber, comprising: a main oil liquid passage that connects two chambers in the cylinder; and a damping force generation mechanism that controls a flow of the oil liquid in the main oil liquid passage to generate a damping force. An annular valve chamber and a bypass passage communicating the two chambers in the cylinder via the valve chamber, and an outer valve seat extending in the circumferential direction on the outer peripheral wall of the valve chamber in a protruding manner.
An inner valve seat extending in the circumferential direction is provided on the inner peripheral wall in a protruding manner, and an annular disc valve is fitted in the valve chamber so that the outer peripheral portion of one end surface of the disc valve abuts on the outer valve seat. A hydraulic shock absorber, wherein an inner peripheral portion of the other end surface is brought into contact with the inner valve seat.