JPH1163077A - Valve structure of hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve structure of a shock absorber capable of highly setting attenuation force in a high piston speed area to improve a bad road running properties so that the attenuation force in a middle speed does not rise so as not to impair comfort when a joint of the road is passed. SOLUTION: In this buffer, a first passage form a top chamber A to an opening window 107D of a piston lower face via an inner circumference port 107A of a piston 107 is additionally provided with a second passage detoured through a horizontal hole 101B opening on the lower end outer face of a piston rod 101 and a hollow hole 101C of the piston rod 101. On the other hand, on the outer face of the horizontal hole 101B of the second passage, a shutter 124 biased by a support spring 125 downwardly supported by a stopper 126 and sandwiched via a rebound spring 123 for upwardly supporting a compression load of the rebound cushion 121 is engaged and inserted vertically movable. Thereby, the second passage is opened and closed in response to the compression load of the rebound cushion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a valve structure for generating a damping force of a hydraulic shock absorber for suppressing vibration of a vehicle body such as a suspension system of an automobile.

[0002]

2. Description of the Related Art As this type of hydraulic shock absorber, for example, one disclosed in Japanese Utility Model Laid-Open Publication No. 1-111840 shown in FIG. 3 (FIG. 3 corresponds to FIG. 2 of the publication) has been developed.
First, an outline of the structure will be described with reference to the drawings. The hydraulic shock absorber mounted between the vehicle body and the wheels via a coupling member,
A piston valve PV is assembled to the piston rod 1 and slidably accommodated therein, and a cylinder 2 having a base valve BV mounted at the lower end is accommodated in the outer cylinder 3, and a seal 16 and a rod guide 17 for shutting off outside air are formed. After inserting the accommodated packing case 18 from above the outer cylinder 3, the outer cylinder 3
Is formed by hermetically sealing the upper end portion by welding all around.
A tank chamber C is formed between the cylinder 2 and the outer cylinder 3.

[0003] When the piston rod 1 rises in the cylinder 2 filled with hydraulic oil, the hydraulic oil in the closed upper chamber A flows out to the lower chamber B via the piston valve PV. The passage resistance becomes the extension-side damping force. Hydraulic oil corresponding to the piston rod retreating volume that is insufficient due to the rise of the piston rod 1 is sucked from the tank chamber C via a base valve BV disposed at the lower end of the cylinder 2.

Next, the piston portion of the hydraulic shock absorber will be described. At the lower end of the piston rod 1, a spigot portion 1A having a smaller diameter than the upper portion is provided, in which a valve retainer 4, a non-return spring 5, a non-return valve 6, a piston ring 14 and a piston 7 fitted with a piston band 15, a main body. The leaf valve 8, sub-leaf valve 9, and Kanza 10 are sequentially inserted. Finally spring 13
The piston valve 11 is configured by screwing the piston nut 11 into which the spring seat 12 urged in the above is loosely inserted so as to be vertically movable and tightening it with a specified torque.

A piston 7 which divides the interior of the cylinder 2 into an upper chamber A and a lower chamber B has an inner peripheral port 7A and an outer peripheral port 7A.
B is formed. An annular opening window 7C is formed at the lower end of the inner peripheral port 7A.
The main leaf valve 8 provided with the communication window 8A and the sub-leaf valve 9 laminated so as to cover the communication window 8A face each other, and the inner peripheral side is fixed by the piston nut 11 via the Kanza 10. In a so-called low speed to low speed range in which the piston speed is small and the pressure difference between the opening window 7C on the lower surface of the piston and the lower chamber B is small, the outer periphery of the main leaf valve 8 urged by the spring 13 via the spring seat 12 is It is closed.

The pressure in the opening window 7C at the lower part of the piston is guided to the upper surface of the sub-leaf valve 9 through the communication window 8A of the main leaf valve 8, so that the outer diameter of the sub-leaf valve 9 reduces the outer diameter of the Kansa 10. Pushed open as a support point,
The spring seat 12 is opened to the lower chamber B through the bypass port 12A.
Generates low-speed damping force. In the low speed range, the communication window 8
Since the flow rate of the hydraulic oil passing through A is small, the pressure difference before and after the communication window 8A is small. However, when the sub-leaf valve 9 downstream of the communication window is pushed open, even if the flow rate is small, the bending rigidity is satisfied. As a result, a damping force having a linear rise at the piston speed can be obtained.

As the piston speed increases, the communication window 8A
And the pressure difference around the communication window 8A also increases. As the piston speed approaches the middle speed range, the pressure difference between the opening window 7C at the lower part of the piston and the lower chamber B increases, so that the outer periphery of the main leaf valve 8 urged by the spring 13 becomes the outer peripheral seat surface of the lower surface of the piston. The hydraulic oil is pushed open from 7D and flows out into the lower chamber B in parallel with the sub-leaf valve 9, and a damping force in the middle speed range and thereafter is generated by the passage resistance at this time.

That is, although the upstream main leaf valve 8 and the downstream sub leaf valve 9 are structurally stacked in series, the piston speed increases and the main leaf valve 8
The pressure difference before and after the communication window 8A provided in the
When the pressure exceeds a set pressure determined by the urging force of the main leaf valve 8 and the bending rigidity of the main leaf valve 8 itself, the main leaf valve 8 itself is pushed open from the outer peripheral side seat surface 7D on the lower surface of the piston in parallel with the communication window 8A which is already open, Since both act as a common damping force generating valve, the pressure difference before and after the communication window 8A does not increase any more, and even if the piston speed further increases, the flow rate flowing through the sub-leaf valve 9 becomes substantially constant. .

As a result, the rise of the damping force can be linearly increased from a very low speed range to a low speed range, so that the damping force is generated firmly even in a low piston speed range such as when rolling, thereby suppressing the body shake. While you can
If the increase in damping force for piston speeds above the medium speed range is set to a small value, the damping force is suppressed in situations where piston speeds in the medium speed range occur frequently, such as when passing through seams of concrete paved roads. Therefore, the input from the road surface to the vehicle body is suppressed, and it is possible to achieve both steering stability and riding comfort.

The above description relates to the extension side in which the piston rod 1 rises in the cylinder 2 filled with hydraulic oil. Conversely, in the so-called compression stroke in which the piston rod 1 descends, the outer peripheral port 7B of the piston 7 The hydraulic oil corresponding to the piston rod entry volume of the lower chamber B excluding the amount to be replenished to the upper chamber A, which becomes a negative pressure by pushing open the non-return valve 6 urged by the non-return spring 5, , Flows out into the tank chamber C via the base valve BV mounted on the lower end of the cylinder 2, and the passage resistance at this time becomes the compression-side damping force.

[0011]

In Japanese Utility Model Laid-Open Publication No. 1-111840 described in the prior art, the stroke of the suspension is finite. When traveling on a rough road such as a road, the frequency of the piston rods being fully extended increases, so-called poor road traveling performance is deteriorated. Conversely, in order to increase the damping force in the high piston speed range in order to improve the ability to travel on rough roads, it is necessary to set the inner peripheral port 7A to a small area, so it has a structural fate. There is a problem that the riding comfort is deteriorated when passing through a seam of a road, for example, when the damping force of the area is increased due to the damping force.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to set a high damping force in a high piston speed range in order to improve running performance on a rough road. An object of the present invention is to provide a valve structure of a shock absorber in which a damping force in a middle speed range is not increased so as not to deteriorate riding comfort when passing through a seam of a road.

[0013]

In order to solve the above-mentioned problems, a means adopted by the present invention is that a piston rod is provided in a first passage from an upper chamber to an opening window on a lower surface of a piston through an inner peripheral port of the piston. A second passage which is detoured through a lateral hole opened on the outer surface of the lower end of the second passage and a hollow hole of the piston rod is provided, and the outer surface of the lateral hole of the second passage is biased from below by a support spring supported by a stopper. At the same time, the second passage is moved in response to the compression load of the rebound cushion by vertically inserting a shutter sandwiched from above through a rebound spring that supports the compression load of the rebound cushion. Opening and closing ".

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a valve structure of a hydraulic shock absorber according to the present invention will be described with reference to FIG. Since the entire structure of the shock absorber is the same as that of the related art, FIG. 1 shows only a piston portion different from that of the related art.
A valve stopper 103, a leaf spring 104, a Kansa 1
05, non-return valve 106, piston band 120
Are assembled in the order of a molded piston 107, a main leaf valve 108, a sub-leaf valve 109, and a support 110, and are fastened by a piston nut 111 into which a spring seat 113 is loosely inserted vertically. A main valve spring 112 is seated on a lower end flange portion of the piston nut 111, and an upper end of the main valve spring 112 urges a main leaf valve 108 via a spring seat 113.

The piston 107 partitions the interior of the cylinder 102 into an upper chamber A and a lower chamber B, and has a lower opening window 107D,
A rear opening window 107E opposite to the non-return valve 106 is provided on the back side, and an annular groove 1 is provided at a central portion on the inner diameter side of the piston 107.
07F is provided. The rear opening window 107E opens to the lower chamber B via the outer peripheral port 107B, and the upper chamber A opens to the lower opening window 107D via the inner peripheral port 107A as a first passage. A main leaf valve 10 is provided substantially at the center of the inner and outer seat surfaces of the lower opening window 107D so as to withstand a back pressure corresponding to a compression-side damping force.
Auxiliary projections for supporting the inner surface 8 from the inside are distributed at several places on the circumference.

The lower part of the piston rod 101 has a hollow hole 1
01C is drilled and the lower end opening is sealed by fixing the plug 114 by caulking or the like, while the upper part of the hollow hole 101C is formed on the outer surface of the lower end of the piston rod 101 via the horizontal hole 101B. It is open.
A support spring 125 whose base end is supported by a stopper 126 is disposed in the vicinity of the lateral hole 101B. At the upper end of the support spring 125, a shutter 124 in which a bush is pressed into the inner diameter side is provided at the lower end of the piston rod 101. It is fitted on the outer surface so as to be movable up and down.

Above the shutter 124, a rebound spring 123 is provided.
A slider 122 is fitted to the upper end of the rebound cushion 121 and the rebound cushion 121
Is movable up and down together with the slider 122 on the outer surface of the piston rod. The annular groove 107F communicating with the bottom opening window 107D via the subport 107C is
1D, the hollow hole 101C, and the horizontal hole 101B communicate with the upper chamber A to form a second passage from the upper chamber A to the lower opening 107D.

Next, the operation in the extension stroke will be described. When the piston speed is in the low speed range, the hydraulic oil in the upper chamber A passes through the inner peripheral port 107A to the lower opening window 107D, the horizontal hole 101B, the hollow hole 101C, the horizontal hole 101D, the annular groove 107F, and the sub port. It is divided into a second passage that passes through 107C and reaches the lower opening window 107D and merges with the lower opening window 107D. The hydraulic oil that has joined the lower opening window pushes the sub-leaf valve 109 open through the communication window 108A of the main leaf valve 108, and flows to the lower chamber B through the communication window 113A of the spring seat 113.
Due to the pressure loss when passing through the sub-leaf valve 109, it is possible to generate a linear rising low-speed damping force as shown in part A of FIG.

When the piston speed is in the middle speed range and the pressure in the lower opening window 107D is increased, the outer peripheral portion of the main leaf valve 108 urged by the main valve spring 112 is pushed open, and the lower chamber B is also opened. Hydraulic oil flows through Since this is a flow parallel to the flow passing through the sub-leaf valve 109, the second passage is open, and compared with the damping force indicated by the dotted line in FIG. 2 when the second passage is not present. As shown by the solid line, the rate of increase of the extension-side damping force with respect to the piston speed is suppressed to a small value, thereby realizing a characteristic that the riding comfort is not degraded at the joint running on the road (part B in FIG. 2).

Next, a description will be given of a state where the temperature of the hydraulic shock absorber rises as a result of traveling on a rough road or the like, the internal pressure rises, and the piston rod 101 shifts above the normal operation range. In this state, the rebound cushion 121 comes into contact with a rod guide (not shown) and the slider 122
While pressing the rebound spring 123 and the support spring 125 through the shutter, the shutter 124 sandwiched between the two springs is pushed down, and in response to the compression load applied to the rebound cushion 121, the horizontal hole 101B
To control the communication area. When the rebound load increases, the lower end of the shutter 124 finally hits the stopper 126 and stops, and the horizontal hole 101B is closed.
Only 3 will bend.

In this state, since the horizontal hole 101B is closed, the second hole 101B passing through the hollow hole 101C of the piston rod is closed.
The passage is shut off, and the passage from the upper chamber A to the lower opening window 107D is only the inner peripheral port 107A. However, since the pressure loss of the inner peripheral port 107A is small in a low speed range, the damping force characteristic at that time is different from the normal position. It is almost the same as the part A in FIG. When the piston speed increases and the state changes from the medium speed range to the high speed range, the pressure loss at the inner peripheral port 107A increases, and the characteristic as shown in FIG. .

That is, the temperature inside the hydraulic shock absorber rises due to rough road running or the like, and the internal pressure rises.
Is higher than the normal operating range, the passage is restricted to the first passage, and the pressure loss increases, so that the damping force in the high-speed region can be increased, so that the running performance on rough roads is improved. It can be done. Hydraulic oil corresponding to the piston rod 101 withdrawing is sucked into the lower chamber B from a reservoir (not shown) through the base valve.

In the so-called compression stroke in which the piston rod 101 descends, the upper chamber A through which the non-return valve 106 urged by the non-return spring 104 is pushed open through the outer peripheral port 107B of the piston to produce a negative pressure.
Hydraulic oil corresponding to the piston rod entering volume of the lower chamber B excluding the amount to be replenished to the lower chamber B flows out to the tank chamber via a base valve (not shown). Become.

[0024]

As described in detail above, in the present invention,
When the piston speed is lower than the middle speed range, the hydraulic oil in the upper chamber A passes through the inner peripheral port 107A of the piston and the lower opening window 10A.
7D, a horizontal hole 101B, and a hollow hole 101
C, lateral hole 101D, annular groove 107F, subport 107
C and the second passage leading to the bottom opening window 107D, merges into the bottom opening window, passes through the communication window 108A of the main leaf valve 108, pushes the sub-leaf valve 109 open, and opens the communication window 113A of the spring seat 113. Then, it flows to the lower chamber B. A pressure loss when passing through the sub-leaf valve can generate a linear rising damping force in a low-speed range, so that the body such as a roll can be prevented from swinging. When the piston speed is in the middle speed range and the pressure in the lower opening window increases, the main valve spring 11
The outer peripheral portion of the main leaf valve urged by 2 is pushed open and hydraulic oil flows into the lower chamber. Since this is a flow parallel to the flow passing through the sub-leaf valve facing the communication window of the main leaf valve, the increase in the damping force in the middle speed range with respect to the piston speed is suppressed relatively small, such as during seam running on a road. Deterioration of riding comfort can be prevented.

When the temperature of the hydraulic shock absorber rises due to rough road running or the like, the internal pressure rises, and the piston rod 101 shifts above the normal operation range, the rebound cushion 121 comes into contact with the rod guide, and the slider 122 While pressing the rebound spring 123 and the support spring 125 through the shutter, the shutter 124 sandwiched between the two springs is pushed down, and the communication area of the lateral hole 101B is controlled in response to the rebound load applied to the rebound cushion. When the rebound load increases, the second passage is finally shut off and the lower opening window 1 extends from the upper chamber A.
The passage leading to 07D is only the inner peripheral port 107A. Therefore, when the piston speed changes from the middle speed range to the high speed range, the pressure loss at the inner peripheral port 107A increases, and the rate of increase of the damping force with respect to the piston speed can be increased. That is, it is possible to increase the damping force in the high speed range of the piston speed when traveling on a rough road, etc., while maintaining the characteristic that the riding comfort is not deteriorated when traveling on a seam of a pavement road, etc. It is possible to improve the running performance of the car.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piston portion of a hydraulic shock absorber according to the present invention.

FIG. 2 is a damping force characteristic of the hydraulic shock absorber according to the present invention.

FIG. 3 is a longitudinal sectional view of a hydraulic shock absorber according to the related art.

[Explanation of symbols]

Reference Signs List A Upper chamber B Lower chamber 101 Piston rod 101B Lateral hole opened in lower end outer surface of piston rod 101C Hollow hole of piston rod 102 Cylinder 107 Piston 107A Inner peripheral port of piston (first passage) 107D Opening window on lower surface of piston 121 Rebound cushion 123 Rebound spring 124 Shutter 125 Support spring 126 Stopper 101B-101C-101D-107F-107C
2nd passage

Claims (1)

[Claims] 1. A hydraulic shock absorber having a piston valve assembled to a lower end of a piston rod and partitioning the inside of a cylinder into an upper chamber and a lower chamber, and slidably guided in the cylinder to generate an extension-side damping force. A first passage extending from the upper chamber through the inner peripheral port of the piston to the opening window on the lower surface of the piston, a second hole diverted through a lateral hole opened on the outer surface of the lower end of the piston rod and a hollow hole of the piston rod.
While a passage is provided, on the outer surface of the side hole of the second passage,
The rebound cushion is urged from below by a support spring supported by a stopper, and from above is inserted vertically by a shutter that is sandwiched via a rebound spring that supports the compression load of the rebound cushion. Wherein the second passage is opened and closed in response to a compression load of the hydraulic shock absorber.