JP2883997B2 - Hydraulic shock absorber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic shock absorber provided in a vehicle such as an automobile.

(Prior Art) In recent years, there has been a demand for a hydraulic shock absorber having a high degree of freedom in setting damping force so that an optimum damping force can be generated according to the running characteristics of a vehicle and the like in order to improve maneuverability and ride comfort. ing.

There is a hydraulic shock absorber conventionally proposed in JP-A-61-10135 to meet the demand. This hydraulic shock absorber has a structure as shown in FIGS. 3 and 4, and will be described briefly.

A valve seat 3 is attached to a lower end of a piston 2 slidably fitted to the cylinder 1, and a main valve 4 and a sub-valve 5 are arranged in contact with both end surfaces of the valve seat 3. An annular concave portion is formed on both end surfaces of the valve seat 3, and this concave portion and each valve 4,
The oil chambers 6 and 7 are constituted by 5 and 5, respectively. The oil chamber 6 on the main valve 4 side is an oil passage formed along the piston rod 9 in the upper oil chamber 8 in the cylinder 1 defined by the piston 2.
It is communicated through ten. The oil passage 10 is constituted by a concave portion 11 formed on the inner periphery of the valve seat 3 and the sub-valve 5 as shown in FIG. The upper oil chamber 8 and the lower oil chamber 12 in the cylinder 1 are communicated with each other by a first orifice 13 formed in the middle of the oil passage 10, and respective oil chambers 6, 7 formed in the valve seat 3. Are communicated via a second orifice 14. The piston 2, the valve seat 3, the main valve 4 and the sub-valve 5 are fixed to the end of the piston rod 9 by tightening a nut 15.

According to this configuration, when the moving speed of the piston 2 is low, when the oil liquid flows from the upper oil chamber 8 to the lower oil chamber 12 through the first orifice 13 provided in the middle of the oil passage 10, A characteristic damping force is generated. Further, as the speed of the piston 2 increases, the oil liquid is introduced from the oil passage 10 into the oil chamber 6 on the main valve 4 side and the oil chamber 7 on the sub-valve 5 side, the hydraulic pressure rises, and the sub-valve 5 opens, and the second The orifice 14 generates a damping force having orifice characteristics. Then, when the speed of the piston 2 further increases, the main valve 4 opens, and a damping force having valve characteristics is generated. The degree of freedom in setting the damping force characteristics generated in this manner can be increased, and the maneuverability, ride comfort, and the like can be improved.

(Problems to be Solved by the Invention) However, the above-mentioned conventional hydraulic shock absorber has the following problems.

The oil passage 10 includes a plurality of recesses 11 formed in each of the valve seat 3 and the sub-valve 5.
In order to ensure a sufficient flow passage area of the valve 10, the concave portion 11 of the valve seat 3 and the concave portion (not shown) of the sub-valve 5 must be aligned during assembly. Therefore, there is a problem that it is very difficult to make a judgment and the workability is deteriorated.

The recess 11 is formed adjacent to a hole through which the piston rod 9 penetrates, and the central portion of the valve seat 3 has a small receiving area of a portion receiving the tightening force by the nut 15 by the recess 11, The rigidity must be reduced accordingly.
Therefore, when a relatively brittle material such as sintered metal is used for the valve seat 3, a nut is attached to the piston rod 9.
There is a problem in that there is a risk of being damaged when the 15 is tightened.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydraulic shock absorber having a high degree of freedom in setting a damping force, and having a good assembling property and a high rigidity. To provide equipment.

(Means for Solving the Problems) A hydraulic shock absorber according to the present invention has an annular groove formed on an end face of a piston fixed to a piston rod and slidably fitted to a cylinder to partition the cylinder into two chambers. A communication hole that communicates the two chambers with the histone is formed in the groove so as to be open, and a sub-valve is interposed on an end surface of the piston where the groove is formed, and a valve body is brought into contact with the valve body. An annular groove is formed corresponding to the groove of the piston, and an opening hole is formed in the sub-valve to communicate between the groove of the piston and the groove of the valve body, and is opposite to the sub-valve side of the valve body. A first pressurizing chamber which communicates with the valve body through a first passage hole in the groove of the valve body and applies hydraulic pressure to the main valve; The auxiliary chamber communicates with the pressurizing chamber through a second passage hole. A second pressurizing chamber for applying hydraulic pressure to the valve is provided, and an annular groove formed in the valve body and first and second passage holes are formed in a radial direction from a through hole of a piston rod formed in the valve body. It is arranged at a position remote from the outside.

(Operation) According to the above configuration, an annular groove is formed in the valve body corresponding to the annular groove in which the communication hole of the piston opens,
Since the opening hole was formed in the sub valve in each groove,
The communication hole of the piston and the pressurizing chamber of the valve body can be communicated without assembling the piston and the valve body around the axis center at a fixed position, thereby facilitating the assembly.

Further, since the annular groove and the first passage hole of the valve body are not provided adjacent to the through hole of the piston rod as in the conventional oil passage and are arranged at a position radially outward from the through hole, A large receiving area of the valve body can be secured by that much, and the surface pressure applied to this portion when fixing the piston body to the piston rod with a nut or caulking is reduced, so that damage to the valve body can be prevented.

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a main part of the hydraulic shock absorber of the present embodiment,
FIG. 2 is a diagram showing damping force characteristics of the hydraulic shock absorber shown in FIG.

In this embodiment, the present invention is applied to a double cylinder type hydraulic shock absorber. A piston 18 fixed to one end of a piston rod 17 is slidably fitted to a cylinder (inner cylinder) 16 via a piston ring 19. The inside of the cylinder 16 is partitioned by the piston 18 into two chambers, an upper chamber 20 and a lower chamber 21. An annular groove 22 is formed in the lower end surface of the piston 18, and an extension communication hole 23 extending in parallel with the axis of the piston 18 and communicating with the upper chamber 20 is opened in the groove 22.
An annular groove 24 is also formed on the upper end surface of the piston 18, and a compression-side communication hole 25 that extends in parallel with the axis of the piston 18 and communicates the upper chamber 20 and the lower chamber 21 is formed in the groove 24. doing. The contraction-side communication hole 25 is closed by a check valve mechanism 26 disposed on the upper end surface of the piston 18, and the check chamber 26 is moved from the lower chamber 21 through the contraction-side communication hole 25 by the check valve mechanism 26.
The flow of oil liquid to 20 is allowed and the flow of oil liquid in the opposite direction is regulated.

A valve body 28 is in contact with the lower end surface of the piston 18 with a sub-valve 27 as a disk valve interposed therebetween.
An annular groove 29 is formed on the upper end surface of the sub-valve 27 so as to correspond to the annular groove 22 formed on the lower end surface of the piston 18. The sub-valve 27 is provided with a plurality of openings 30 at predetermined intervals for communicating between the inside of the groove 22 of the piston 18 and the inside of the groove 29 of the valve body 28. An annular groove 31 is also formed on the lower end surface of the valve body 28, and a groove provided in the groove 31 and the upper end surface is formed in the valve body 28.
A first passage hole 32 communicating with the inside of the valve body 29 is formed to extend in parallel with the axis of the valve body 28.

A main valve 33 in which a plurality of disc valves are stacked is in contact with the lower end surface of the valve body 28 so as to close the groove 31. The first pressure chamber is formed by the main valve 33 and the groove 31.
34 are configured. The lower chamber 21 and the first chamber 21 are provided on the outer peripheral side of the disc valve on the side that contacts the valve body 28 of the main valve 33.
The orifice 35 is formed of a notch for communicating with the inside of the pressurizing chamber 34 with a small flow passage area.

An annular groove 36 is also formed radially outside the groove 29 on the upper end surface of the valve body 28, and this groove 36
Is blocked by The inside of the groove 36 and the first pressure chamber 34
Is a second passage hole 37 extending in parallel with the axis of the valve body 28.
Communication. The sub-valve 27 and the groove 36 constitute a second pressurizing chamber 38.

As described above, the annular groove 22 and the extension side communication hole 23 formed in the piston 18 are arranged at positions radially outwardly away from the through hole 18a of the piston rod 17 formed in the piston 18. Further, the annular groove 29 and the first and second passage holes 32 and 37 formed in the valve body 28 are also located at positions radially outward from the through holes 28a of the piston rod 17 formed in the valve body 28. Are located.

The piston 18, the auxiliary valve 27, the valve body
28, main valve 33, etc.
Are fixed together by tightening.

In these configurations, the damping force is generated during the extension stroke of the hydraulic shock absorber, but the damping force during the contraction stroke is arranged on the bottom side (not shown) and the cylinder 16 and the outer cylinder
It is generated by a contraction-side damping force generation mechanism (not shown) that controls the flow of the oil liquid into the reservoir chamber 41 between the pressure chamber 40 and the reservoir 40.

An operation of generating a damping force of the hydraulic shock absorber having the above configuration will be described.

First, when the moving speed of the piston 18 is slow in the extension stroke, the oil liquid on the upper chamber 20 side is filled with the extension side communication hole 23, the opening hole 30,
It flows into the first pressurizing chamber 34 through the first passage hole 32, and further flows into the lower chamber 21 through the orifice 35 formed in the main valve 33. At this time, the damping force of the orifice characteristic is reduced by the orifice 35. (Characteristics shown by the line A in FIG. 2).

Next, when the speed of the piston 18 increases, the second passage hole
The oil liquid flows from the first pressurizing chamber 34 to the second pressurizing chamber 38 through 37, and the pressure in the second pressurizing chamber 38 is increased to open the sub-valve 27, thereby reducing the damping force of the valve characteristics. Generated (second
(Characteristic indicated by line B in the figure).

When the speed of the piston 18 further increases, the first pressurizing chamber 34
The main valve 33 opens to generate a damping force of valve characteristics (characteristics of line C in FIG. 2).

Here, the auxiliary valve 27 has a single disk valve configuration, and the main valve 33 has a plurality of disk valves. Therefore, the valve opening pressure of the auxiliary valve 27 is smaller than that of the main valve 33. . Further, the pressure receiving area in which the main valve 33 receives the pressure from the first pressurizing chamber 34 and the sub valve 27 is the second pressurizing chamber 38
Because it is larger than the pressure receiving area that receives pressure from
The gradient of the valve characteristic of 33 is smaller than the gradient of the valve characteristic of the sub-valve 27. Note that these damping force characteristics can be freely set by appropriately selecting the number of disk valves and the pressure receiving area.

 The operation of the hydraulic shock absorber will be described.

An annular groove 29 corresponding to the annular groove 22 in which the extension side communication hole 23 of the piston 18 opens is formed in the valve body 28, and an opening hole 30 is formed in the sub-valve 27 so as to be located in each groove 22, 29. Therefore, the extension side communication hole 23 and the first and second pressurizing chambers 34 and 38 are surely communicated simply by assembling the piston 18 and the valve body 28 without fixing the position around the axis center thereof. . Therefore, there is no need to accurately position the sub-valve 27 and the valve body 28 in the rotational direction as in the related art, and assembly becomes very easy.

Further, since the extension-side communication hole 23 and the first passage hole 32 are not provided close to the piston rod 17 and are arranged at a position radially outward from the piston rod 17, the receiving area of the valve body 28 is accordingly reduced. It can be secured large. Therefore, when the nut 39 is tightened and fixed to the piston rod 17, the surface pressure of the portion where the valve body 28 receives the tightening force is reduced, and even if the piston 18 and the valve body 28 are formed of sintered metal, breakage or the like occurs. Can be prevented.

In the present embodiment, the present invention is applied so as to generate damping force during the extension stroke.However, the present invention is applied so as to generate damping force during the contraction stroke or during both the extension stroke and the contraction stroke. You may.

In the present embodiment, the present invention is applied to the sub-cylinder type hydraulic shock absorber. However, the present invention can be applied to any type of hydraulic shock absorber as long as the piston slides in the cylinder.

(Effects of the Invention) As described in detail above, the present invention provides an annular groove formed in the valve body and communicating with the pressurizing chamber corresponding to an annular groove formed in the piston and opening the communication hole, Since the opening hole that connects each groove to the sub-valve is formed, the communication hole and the pressurizing chamber are surely communicated simply by assembling without fixing the position around the axis of the piston and the valve body. There is no need to position the valve and the valve body in the rotational direction, and assembly becomes very easy. Therefore, productivity can be improved and product cost can be reduced.

Further, the annular groove and the first and second passage holes of the valve body are not provided adjacent to the through-holes of the piston rod, and are arranged at positions radially outwardly from the piston rod. Since a large bearing area can be ensured, the surface pressure applied to the contact surface with the valve body due to a nut or caulking during assembly is reduced, and damage to the valve body can be prevented. Therefore, the occurrence of defective products can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an essential part showing an embodiment of a hydraulic shock absorber according to the present invention, FIG. 2 is a diagram showing damping force characteristics of the hydraulic shock absorber shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 17 Piston rod, 18 Piston 20 Upper chamber, 21 Lower chamber 22, 29 Annular groove, 27 Secondary valve 28 Valve body, 28a Through hole 30 Open Hole 32 First passage hole 33 Main valve 34 First pressurized chamber 37 Second passage hole 38 Second pressurized chamber

Claims (1)

(57) [Claims] An annular groove is formed in an end face of a piston fixed to a piston rod and slidably fitted to a cylinder to partition the cylinder into two chambers, and communicates the two chambers with the piston. A communication hole is provided in the groove so as to be opened, an auxiliary valve is interposed on the end face of the piston where the groove is formed, and a valve body is brought into contact with the piston, and an annular groove is formed in the valve body corresponding to the groove of the piston. In addition, an opening hole is formed in the sub-valve to communicate the inside of the piston groove and the inside of the valve body groove, and the main valve is disposed on the side of the valve body opposite to the side of the sub-valve. A first pressurizing chamber for communicating with the inside of the groove of the valve body through a first passage hole and applying hydraulic pressure to the main valve;
A second pressurizing chamber for communicating hydraulic pressure to the auxiliary valve through a passage hole of the valve body, and an annular groove formed in the valve body and first and second passage holes are formed in the valve body. A hydraulic shock absorber characterized by being disposed at a position radially outwardly away from a through hole of a piston rod to be formed.