JP2002206584A - Valve structure in hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of an abnormal noise caused by discontinuity of a damping force, by smoothly opening each valve in an hydraulic shock absorber without delay, while maintaining a withstand pressure strength of each valve. SOLUTION: In this hydraulic shock absorber, on a base end side rear surface of a check valve CV and an elongation side damping valve PV arranged on a piston 5 partitioning an inside of a cylinder 21 into an upper chamber A and a lower chamber B, a ring seat with an outer edge as a supporting portion for deflection of each valve is placed to support each valve, thereby controlling the elongation side damping force when the piston rod elongates, while on a base end side rear surface of a suction valve DV and a pressing side damping valve BV arranged on a valve case 15 partitioning the inside of the cylinder into the lower chamber and a bottom chamber C, a ring seat with an outer edge as a supporting portion for deflection of each valve is placed to support each valve, thereby controlling a pressing side damping force when the piston rod lowers. In either the check valve arranged on the piston and the ring seat 107 arranged on the base end side rear surface of the elongation side damping valve, or the suction valve arranged on the valve case and the ring seat 117 arranged on the base end side rear surface of the pressing side damping valve, or all of them, the distances in a radial direction from centers of inside diameters to the outer edges are smoothly changed to vary the deflection rigidity in a peripheral direction of each valve, thereby sequentially opening the valve from a small deflection rigidity portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As this type of hydraulic shock absorber, for example, the one shown in FIG. 4 is known. First, an outline of the structure will be described with reference to the drawings. When the hydraulic shock absorber is mounted on the vehicle, the vertical relationship is the same as that of FIG.

A hydraulic shock absorber mounted between a vehicle body and a wheel via a coupling member is provided with a piston rod 1 mounted on the vehicle body side, a piston 5 and a piston valve for controlling the extension-side damping force, which are slidably mounted. And a cylinder 21 having a base valve for controlling a compression-side damping force at a lower end thereof is accommodated in an outer cylinder 22 attached to the wheel side, and a seal 24 and a rod guide 23 for shutting off outside air.
After the packing case 25 accommodating the above is inserted from above the outer cylinder 22, the upper end of the outer cylinder 22 is hermetically sealed by welding all around. Then, the cylinder 21 and the outer cylinder 22
A tank chamber D is formed therebetween.

When the piston rod 1 rises in the cylinder 21 filled with hydraulic oil, the hydraulic oil in the closed upper chamber A is supplied to the lower chamber via a piston valve attached to the lower end of the piston rod 1. B, and the passage resistance at this time becomes the extension-side damping force. Hydraulic oil corresponding to the piston rod withdrawal volume that is insufficient due to the rise of the piston rod 1 is replenished from the bottom chamber C connected to the tank chamber D via a base valve attached to the lower end of the cylinder 21.

Next, a piston valve for controlling the extension-side damping force 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, where a check valve C comprising a leaf valve 3 and a notched leaf valve 4 is provided.
The valve stopper 2, which regulates the maximum deflection of the V, the ring seat 7, the outer peripheral edge of which serves as a support point for the deflection of the check valve CV, the leaf valve 3, the hydraulic valve is superimposed on the lower side of the leaf valve 3 and the hydraulic fluid is provided on the outer peripheral side Notch leaf valve 4 provided with notch 4A, and piston 5 whose upper surface faces notch leaf valve 4
Are sequentially inserted.

A piston 5 having a cylinder 21 partitioned into an upper chamber A and a lower chamber B and having a guide 5S wound around the outer periphery thereof has a through hole 3A for the leaf valve 3 and a through hole for the notched leaf valve 4 on the upper surface side. An annular upper opening window 5D communicating with the upper chamber A via the upper peripheral chamber 4B and an annular outer opening window 5E communicating with the lower chamber B via the outer peripheral port 5A are provided. An annular lower opening window 5C communicating with the upper opening window 5D via 5B is provided.

Subsequently, the extension damping valve PV comprising a leaf valve 6 opposed to the lower opening window 5C, the ring seat 7 having an outer peripheral edge serving as a support point for the bending of the extension damping valve PV, and the extension damping valve PV. The valve stopper 8 for restricting the maximum deflection is sequentially assembled, and finally, the piston nut 9 is screwed into the threaded portion of the spigot portion 1A and fastened by a tightening tool, thereby forming a piston valve.

In a so-called elongation step in which the piston rod 1 rises in the cylinder 21 filled with hydraulic oil, in a so-called low-speed range where the piston speed is small and the pressure difference between the lower opening window 5C of the piston 5 and the lower chamber B is small. , Extension damping valve P
V covers the lower opening window 5C. Therefore, upper chamber A
Pressure oil passes through the notch 4A of the notch leaf valve 4,
The fluid flows out into the lower chamber B through the outer opening window 5E and the outer peripheral port 5A of the piston 5, and at this time, the extension resistance in the low speed range proportional to the square of the piston speed is generated by the passage resistance.

[0009] As the piston speed increases, the flow rate through the notch 4A of the notch leaf valve 4 increases, the pressure difference before and after the notch increases, and communication with the upper chamber A via the inner peripheral port 5B. Lower opening window 5C of the moving piston 5
The pressure difference between the pressure and the lower chamber B also increases.

As the piston speed approaches the medium speed range, the extension damping valve PV disposed opposite the lower opening window 5C.
Of the lower opening window 5C is pushed open from the outer sheet portion of the lower opening window 5C, overcoming the combined flexural rigidity, and the hydraulic oil flows out to the lower chamber B, and the passage resistance at this time and the passage resistance of the inner peripheral port 5B. With this, the extension side damping force is generated in the middle speed range and thereafter.
By appropriately selecting the flexural rigidity of the extension-side damping valve PV composed of the leaf valve 6 and the passage area of the inner peripheral port 5B,
The required damping force characteristics can be obtained.

Next, a base valve for controlling the compression side damping force will be described. First, on the shaft 11A of the guide 11,
A ring seat 17 whose outer peripheral edge is a supporting point of the deflection of the suction valve DV composed of the leaf valve 13 and the cut-out leaf valve 14, the leaf valve 13, and a lower side of the leaf valve 13 that are superimposed on the lower side of the leaf valve 13 so that a hydraulic oil passage is formed. Notch leaf valve 14 having a notch 14A,
Are sequentially fitted.

A lower chamber B fitted to the lower end of the cylinder 21
A ring-shaped upper opening window 15D communicating with the lower chamber B through a through-hole 13A of the leaf valve 13 and a through-hole 14B of the notched leaf valve 14 is provided on the upper surface side of the valve case 15 that separates the bottom chamber C from the bottom case C. And an annular outer opening window 15E communicating with the bottom chamber C through an outer peripheral port 15A, and an upper opening window 1 through an inner peripheral port 15B on the lower surface side.
An annular lower opening window 15C communicating with 5D is provided.

Subsequently, on the shaft portion 11A of the guide 11, a compression damping valve BV composed of a leaf valve 16 facing the lower opening window 15C of the valve case 15, and further, the outer peripheral edge supports the bending of the compression damping valve BV. The base ring is formed by sequentially assembling a ring seat 17 serving as a point and a valve stopper 18 for regulating the maximum deflection of the compression-side damping valve BV, and finally crimping the lower end of the shaft 11A of the guide 11 with a tool.

In a so-called contraction step in which the piston rod 1 descends in the cylinder 21 filled with hydraulic oil, in a so-called low-speed region where the piston speed is small and the pressure difference between the lower opening window 15C of the valve case 15 and the bottom chamber C is small. , The compression side damping valve BV covers the lower opening window 15C. For this reason, the pressure oil in the lower chamber B excluding the amount replenished to the upper chamber A whose volume increases via the piston 5 is supplied to the notch 14A of the notch leaf valve 14 and the outer opening window 1 of the valve case 15.
5E, opened to the bottom chamber C via the outer peripheral port 15A,
Due to the passage resistance at this time, a pressure-side base damping force in a low-speed range that is approximately proportional to the square of the piston speed is generated.

Here, the pressure oil in the lower chamber B, which is replenished through the piston 5 to the upper chamber A whose volume is increased, has a low piston speed and a pressure difference between the outer opening window 5E of the piston 5 and the upper chamber A. In a small so-called low speed range, the leaf valve 3
The check valve CV including the notched leaf valve 4 covers the outer opening window 5E. For this reason, the pressure oil in the lower chamber B passes through the outer peripheral port 5A of the piston 5, flows out to the upper chamber A through the notch 4A of the notch leaf valve 4, and the piston speed becomes approximately 2 due to the passage resistance at this time. Generates a pressure-side back-side damping force in the low-speed range that is proportional to the power. The compression-side damping force obtained by adding the compression-side back surface damping force to the compression-side base damping force is a compression-side damping force in a low-speed range.

As the piston speed increases, the flow rate passing through the notch 14A increases, the pressure difference between before and after the notch increases, and the through hole 13A of the leaf valve 13 and the notch leaf communicating with the through hole 13A. Opening 1 of valve 14
4B, the valve case 15 communicating with the lower chamber B via the upper opening window 15D of the valve case 15 and the inner peripheral port 15B.
The pressure difference between the lower opening window 15C and the bottom chamber C also increases.

For this reason, as the piston speed approaches the middle speed range, the outer peripheral side of the compression side damping valve BV composed of the leaf valve 16 disposed opposite to the lower opening window 15C has its combined flexural rigidity. It overcomes and is pushed open from the outer seat portion of the lower opening window 15C, and the hydraulic oil flows out to the bottom chamber C, and the passage resistance at this time and the passage resistance of the inner peripheral port 15B cause the compression-side base damping force after the middle speed range. Occurs. By appropriately selecting the bending rigidity of the compression side damping valve BV including the leaf valve 16 and the passage area of the inner peripheral port 15B,
The required damping force characteristics can be obtained.

Here, the upper chamber A whose volume is increased passes through the outer peripheral port 5A of the piston 5 and overcomes the combined flexural rigidity of the check valve CV composed of the leaf valve 3 and the notched leaf valve 4, The check valve CV is pushed open from the outer seat portion 5F of the outer opening window 5E, hydraulic fluid is replenished from the lower chamber B, and the passage resistance at this time generates a pressure-side rear damping force in the middle speed region and thereafter. The compression-side damping force obtained by adding the compression-side rear damping force to the compression-side base damping force is the compression-side damping force in the middle speed range and thereafter.

Conversely, when the piston rod 1 rises, the hydraulic oil in the bottom chamber C passes through the outer peripheral port 15A of the valve case 15, and the deflection of the suction valve DV composed of the leaf valve 13 and the notched leaf valve 14 is caused. Overcoming rigidity,
The suction valve DV is connected to the outer seat portion 15F of the outer opening window 15E.
The lower portion B is replenished with hydraulic oil corresponding to the retreated volume of the piston rod 1.

[0020]

When the hydraulic shock absorber switches from the extension stroke to the contraction stroke, the pressure in the lower chamber B increases due to the compression damping force.
And the suction valve DV closes promptly due to the differential pressure between the lower chamber B and the bottom chamber C where the pressure increases. On the other hand, when switching from the contraction stroke to the extension stroke, the pressure in the upper chamber A increases rapidly due to the extension damping force.
The check valve CV closes promptly due to the pressure difference between the upper chamber A and the lower chamber B. However, the pressure in the bottom chamber C is the same as the pressure of the gas sealed in the tank chamber D (standard type: 1 bar, low-pressure gas type: 3 bar), and the differential pressure between the bottom chamber C and the lower chamber B is the same as the pressure of the sealed gas. Since the pressure cannot be exceeded, it is difficult to smoothly open the suction valve DV with this small differential pressure without delay.

For this reason, when switching from the contraction stroke to the extension stroke, insufficiency of suction into the lower chamber B occurs in a low piston speed range, and the pressure in the lower chamber B temporarily decreases. Since the suction force to the lower chamber B due to the pressure drop of the lower chamber B is added to the original expansion damping force generated on the valve side, as shown by the L section in FIG. The rising gradient of the damping force becomes steep, causing discontinuity of the damping force.

As a method of smoothly opening the suction valve DV, it is conceivable to reduce its bending rigidity or to increase the pressure receiving area of the outer opening window 15E.
Since the suction valve DV needs to withstand the pressure in the lower chamber B corresponding to the compression-side damping force during the contraction stroke, there is a limit in reducing the flexural rigidity while maintaining the pressure resistance. On the other hand, there is a space limitation in increasing the pressure receiving area of the outer opening window 15E.

The valve opening pressure of the suction valve DV is determined by the bending rigidity of the suction valve itself and the annular outer peripheral sheet portion 15F and the intermediate seat portion 15G forming the upper opening window 15E.
It is known that it is determined by the attraction force of the contact surface between the strip seat portion and the suction valve DV. Since the pressure difference between the bottom chamber C and the lower chamber B cannot exceed the gas pressure of the gas sealed in the tank chamber D, the pressure difference between the bottom chamber C and the lower chamber B must be reduced to the opening pressure of the suction valve DV which must be operated with a small pressure difference. The influence of the occupying power is large.

Here, the suction valve DV is fixed on the inner peripheral side and opens gradually from the outer peripheral side.
The magnitude of the attraction force occupying the valve opening pressure of V is first in the outer peripheral sheet portion 15F and then in the intermediate seat portion 15G. The present invention has been made in view of the above circumstances, and a purpose thereof is to open the suction valve DV on the base valve side smoothly and smoothly without delay while maintaining the pressure resistance, and to reduce the damping force. An object of the present invention is to provide a hydraulic shock absorber that can suppress generation of abnormal noise caused by discontinuity.

[0025]

Means for Solving the Problems The invention according to the first and second embodiments is described as follows. "The inside of a cylinder is divided into an upper chamber and a lower chamber via a piston fastened to a piston rod, The lower chamber and the bottom chamber communicating with the tank chamber are partitioned through the provided valve case, and the outer peripheral edge of the check valve and the extension-side damping valve disposed on the piston on the rear side of the base end side of the deflection of each valve is provided. A ring seat serving as a support point is provided to carry each valve and control the extension damping force when the piston rod is extended, while the base rear side of the suction valve and the compression damping valve arranged in the valve case. An annular seat whose outer peripheral edge serves as a support point for the bending of each valve is provided on each of the valves, and the hydraulic shock absorber controls each valve and controls the compression-side damping force when the piston rod descends.

In order to solve the problem, a means adopted by the invention according to the first embodiment is that “a check valve disposed on the piston or a suction valve disposed on a valve case is disposed on a back surface on each base end side. Either or both of the ring seats are smoothly changed in the radial direction from the axis of the inner diameter to the outer peripheral edge to change the bending rigidity in the circumferential direction of each of the valves, and sequentially from the portion having the smaller bending rigidity. That the valve is opened. "

Next, a means adopted by the invention according to the second embodiment is that "the expansion damping valve disposed on the piston or the compression damping valve disposed on the valve case is disposed on the back surface on the base end side of each valve. Either or both of the ring seats are smoothly changed in the radial direction from the axis of the inner diameter to the outer peripheral edge to change the circumferential flexural rigidity of each of the valves, and sequentially from the portion having the smaller flexural rigidity. That the valve is opened. "
The outer peripheral edge of the ring seat may be any of a circle eccentric to the inner diameter, a substantially elliptical shape or a substantially polygonal shape concentric with the inner diameter.

Next, the invention according to the third embodiment is as follows.
`` The interior of the cylinder is divided into an upper chamber and a lower chamber through a piston fastened to a piston rod, and a lower chamber and a bottom chamber communicating with the tank chamber are divided through a valve case provided at the lower part of the cylinder. A low-speed damping valve is opposed to each lower opening window of a piston or a valve case communicated with the upper chamber or the lower chamber, and an outer peripheral edge of the low-speed damping valve is bent at a rear end side of the low-speed damping valve. An auxiliary leaf valve is provided while providing a gap corresponding to the thickness of the ring seat on the back side of the ring seat, and in the low piston speed range, the other oil chamber is The pressure oil guided to each lower opening window flows out to one oil chamber while bending only the low speed range damping valve with the outer peripheral edge of the ring seat as a support point, and when the piston speed is above the middle speed range, the low speed range damping The valve and auxiliary leaf valve overlap and flex while reducing the extension side It assumes hydraulic shock absorber "to control the force or compression side damping force.

Means adopted by the invention according to the third embodiment is that the ring seats disposed on the rear surface on the base end side of the leaf valve are provided so that the radial distance from the axis of the inner diameter to the outer peripheral edge is smooth. To change the bending stiffness of the leaf valve so that the valve is sequentially opened from a portion having a small bending stiffness. " The outer peripheral edge of the ring seat may be any of a circle eccentric to the inner diameter, a substantially elliptical shape or a substantially polygonal shape concentric with the inner diameter.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic shock absorber according to the present invention has the same basic structure as the prior art shown in FIG.
Are movably inserted into the cylinder 21 via the piston 5 mounted on the lower end thereof, and define an upper chamber A and a lower chamber B. Further, a valve case 15 is fitted to the lower end of the cylinder 21 to similarly define a bottom chamber C communicating with the lower chamber B and the tank chamber D.

The first embodiment of the present invention relates to a structure for reducing the attraction force of the check valve CV or the suction valve DV. The effect of reducing the suction force between each valve and the seat portion is particularly remarkable in the suction valve DV on the base valve side, but the same effect is also obtained in the check valve CV on the piston valve side. Since the check valve CV and the expansion damping valve PV on the piston valve side and the suction valve DV and the compression damping valve BV on the base valve side according to the present invention are similar to each other in the degree to which the inside diameters of the components are different, the following effects are obtained. The contents of the present invention will be described together in the form of the piston valve side (base valve side).

First, a first embodiment of the present invention will be described with reference to a sectional view of a main part shown in FIG. 1 and a drawing of related parts shown in FIG. In a first example of the present embodiment, the same leaf valve 3 (13) and notched leaf valve 4 (1) as the conventional one shown in FIG.
4) the check valve CV (suction valve DV)
The outer peripheral edge 107A (117A) of the ring seat 107 (117), which is superimposed on the rear surface on the base end side of the check valve CV (suction valve DV) and serves as a flexure support member, has an inner diameter 107B as shown in FIG. (117B) is decentered by W. As a result, the radial distance from the axis Z of the inner diameter 107B (117B) to the outer peripheral edge 107A (117A) can be smoothly changed.

Next, a second embodiment in which the outer periphery of the ring seat is made elliptical as shown in FIG. 2 (D) will be described. In the present embodiment, the ring seat 207 (217) which is superimposed on the rear surface on the base end side of the check valve CV (suction valve DV) and serves as a bending support member.
The outer peripheral edge 207A (217A) of the
7B) and an inner diameter 207B (21
The radial distance from the axis Z of 7B) to the outer peripheral edge 207A (217A) is smoothly changed. The outer peripheral edge of the ring seat only needs to smoothly change the distance in the radial direction.

Next, a description will be given of a third embodiment in which the outer peripheral edge of the ring seat is formed in a substantially triangular shape (diaper shape) as shown in FIG. 2 (E). In this embodiment, the check valve CV (suction valve D
The outer peripheral edge 307A (317A) of the ring seat 307 (317) which is superimposed on the rear surface on the base end side of V) and serves as a flexure support member is substantially triangular (conical) concentric with the inner diameter 307B (317B), and the inner diameter 307B The radial distance from the axis Z of (317B) to the outer peripheral edge is smoothly changed. The outer peripheral edge of the ring seat may have a substantially polygonal shape (4, 5, 6,...) Since the distance in the radial direction only needs to change smoothly.

In any of the embodiments, the check valve CV
A ring seat 107 serving as a support member for bending the (suction valve DV),
Outer edge 1 of 207, 307 (117, 217, 317)
07A, 207A, 307A (117A, 217A, 3
17A) changes continuously from the X portion where the distance from the center Z is the shortest to the Y portion where the distance from the center Z is the longest.

In the outer peripheral edge of the ring seat, the farther from the center Z, the farther the support point of the check valve CV (suction valve DV) becomes, the more the check point CV supported by the outer peripheral edge of the ring seat. The bending rigidity of the (suction valve DV) increases continuously from the X side to the Y side. For this reason, in the low-speed range of the piston speed, first, each valve opens from the X side where the flexural rigidity is small, and gradually and smoothly toward the Y side where the flexural rigidity is large as the differential pressure increases with the increase of the piston speed. To open.

The suction force of the check valve CV (suction valve DV) to the seat portion on the piston back (back of the valve case) side is:
Since opening the valve gradually is smaller than opening it all at once,
Since the differential pressure when the valve is opened from the X side is small, it is possible to improve insufficient suction from the bottom chamber C to the lower chamber B via the suction valve DV particularly when switching from the compression side to the expansion side. As a result, the discontinuity of the damping force due to the insufficient suction as shown at L in FIG. 5 (B) is smoothly improved as shown in FIG. 5 (A), and the noise caused by the discontinuity of the damping force is reduced. Can be suppressed.

As described above, the present invention is applied to the check valve C on the upper surface side of the piston.
V (the suction valve DV on the upper side of the valve case) has been described, but the leaf valve 6 disposed opposite the lower opening window 5C (15C) on the lower side of the piston (valve case) is described. Extension side damping valve PV consisting of (16)
The second embodiment applied to the (pressure-side damping valve BV) can be carried out in the same manner as the rear side. In this embodiment, similarly to each of the above-described embodiments, the ring seat 7 (17) having the conventional structure, which is disposed on the rear surface on the base end side of the leaf valve 6 (leaf valve 16), is replaced with the ring according to the present invention. Seat 1
07, 207, 307 (117, 217, 317).

Also in this case, each ring seat 107, 207, 30
7 (117, 217, 317), the longer the distance from the center Z, the more the support point of the extension-side damping valve PV (compression-side damping valve BV) becomes outside, so that each ring seat 107, 207, 30
7 (117, 217, 317), the flexural stiffness of the extension-side damping valve PV (compression-side damping valve BV) supported on the base-side rear surface continuously increases from the X side to the Y side. Therefore, in the low-speed range of the piston speed, the valve is first opened from the X side where the flexural rigidity is small, and is gradually and smoothly opened toward the Y side where the flexural rigidity is large in accordance with the increase in the differential pressure accompanying the increase in the piston speed. .

Next, each of the ring seats 107, 207, 30
7 (117, 217, 317) will be described for a third embodiment in which the damping force in the entire speed range from a very low speed range to a high speed range of the piston speed is controlled by a leaf valve, as shown in FIG. Piston 5 according to the present embodiment
The expansion side low-side damping valve LPV on the side and the compression side low-side damping valve LBV on the valve case 15 side have similar functions and effects to the extent that the inside diameters of the components are different. (Case side).

This valve structure is disclosed in Japanese Utility Model Laid-Open Publication No. 60-101242, which is exemplified by using the right half sectional view of FIG. 3, and has a lower opening window on the lower surface side of the piston 5 (valve case 15). At 5C (15C), leaf valve 6 (1
6), the expansion-side low-speed damping valve LPV (compression-side low-speed damping valve LBV) faces each other, and each low-speed damping valve LPV (LB
A ring seat 7 whose inner and outer diameters are concentric and whose outer peripheral edge is a support point of the bending of each low-speed range damping valve LPV (LBV) is provided on the rear surface on the base end side of V)
(17) {Indicated in parentheses in the right half cross-sectional view of FIG. 3), the auxiliary leaf valve 106 (116) is disposed on the rear surface on the base end side of the ring seat 7 (17). I have.

The auxiliary leaf valve 106 (116)
Exemplifies a case in which the inner and outer diameters are the same as the extension-side low-speed range damping valve LPV (compression-side low-speed range damping valve LBV) composed of the leaf valve 6 (16).
Is not necessarily the same as the outer diameter of the leaf valve 6 (16), and the bending rigidity can be adjusted by reducing the outer diameter or by gradually reducing the outer diameter.

In the range from the very low speed to the low speed of the piston speed, the pressure oil guided from the upper chamber A (lower chamber B) to the lower opening window 5C (15C) is applied to the expansion side low speed area formed by the leaf valve 6 (16). It overcomes the flexural rigidity of the damping valve LPV (pressure-side low-speed damping valve LBV), pushes its outer peripheral side through the lower opening window 5C (15C) and flows out to the lower chamber B (bottom chamber C), and the passage resistance at that time As a result, a damping force in a very low to low speed range is generated. By appropriately selecting the combination of the plate thickness and the number of leaf valves 6 (16), the flexural rigidity can be changed, and the damping force in the low to low speed range can be controlled.

As the piston speed increases, the flexing of the extension-side low-speed damping valve LPV (compression-side low-speed damping valve LBV) increases, so that the outer peripheral side of each low-speed damping valve LPV (LBV) is an auxiliary leaf valve 106 (116). After that, each low-speed range damping valve LPV (LBV) bends by overcoming the combined bending stiffness of both while pushing down the auxiliary leaf valve 106 (116).

Therefore, the damping force can be controlled by the flexural rigidity of only the low speed range damping valve LPV (LBV) in the range of very low to low speed of the piston speed. Range damping valve LPV (LB
The damping force can be controlled by the combined flexural rigidity of V) and the auxiliary leaf valve 106 (116).

The piston 5 (valve case 15)
The lower opening window 5C (15C) is provided with an extension-side low-speed damping valve L.
Since the PV (pressure-side low-speed range damping valve LBV) is opposed, an adsorbing force acts on the contact portion between the two via an oil film. In the range of very low to low speeds of the piston speed, the differential pressure across the extension-side low-speed damping valve LPV (compression-side low-speed damping valve LBV) is small, so that the effect of the attraction force on the damping force in the very low to low speed range is large.

Therefore, in the third embodiment of the present invention, as shown in FIG. 3, the ring seat 7 (17) is replaced with the ring seats 107, 207, 307 (117, 21) described in the first embodiment.
7,317), and the outer periphery 107
A, 207A, 307A (117A, 217A, 317)
A) is changed continuously from the X portion where the distance from the center Z is the shortest to the Y portion where the distance from the center Z is the longest.

As the distance from the center Z increases, the outer peripheral edge of the ring seat extends toward the extension side low speed range damping valve LPV (the compression side low speed range damping valve LV).
Since the support point of BV) is on the outside, the flexural rigidity of the extension-side low-speed damping valve LPV (compression-side low-speed damping valve LBV) whose rear surface on the base end is supported by the outer peripheral edge of the ring seat changes from the X side to the Y side. It grows continuously toward. For this reason, the piston speed is very low
In the low speed range, first, each valve opens from the X side where the flexural rigidity is small, and as the differential pressure increases with the increase in piston speed,
The valve is gradually and smoothly opened toward the Y side where the flexural rigidity is large.

The extension-side low-speed damping valve LPV for the lower opening window 5C (15C) of the piston 5 (valve case 15)
Since the suction force of the (pressure side low speed range damping valve LBV) is smaller when the valve is gradually opened than when it is opened all at once, the differential pressure at the time of opening the valve from the X side becomes smaller. The damping force can be raised smoothly. As a result,
The discontinuity of the damping force as shown at L in FIG.
As shown in (A), the smoothness is improved, and it is possible to suppress the occurrence of noise that is caused by the discontinuity of the damping force.

According to the present invention, the ring seats 107, 207, 307 (117, 217,
317) of the outer periphery 107A, 207A, 307A (11
7A, 217A, 317A)
(Suction valve DV) or extension side damping valve PV (compression side damping valve B)
V) or the extension side low speed range damping valve LPV (compression side low speed range damping valve L
The bending rigidity of BV) increases continuously from the X side whose outer peripheral edge is closer to the axis of the inner diameter to the Y side farther from the axis.

For this reason, in the low-speed range of the piston speed, the valve is first opened from the X side where the flexural rigidity is small, and gradually and smoothly toward the Y side where the flexural rigidity is large as the differential pressure increases as the piston speed increases. Since the valves are opened, the attraction force between each valve and the seat portion can be reduced. As a result, FIG.
As shown in (A), the discontinuity of the damping force is almost eliminated, and the generation of abnormal noise due to the discontinuity of the damping force can be suppressed.

[0052]

As described above in detail, according to the present invention, the check valve (suction valve) or the expansion-side damping valve (compression-side damping valve) or the expansion-side low-speed damping valve (supported by the outer peripheral edge of the ring seat) is provided. The flexural rigidity of the compression-side low-speed damping valve) increases continuously from the portion where the outer peripheral edge is closer to the inner diameter axis to the farther from the axis. For this reason, in the low-speed range of the piston speed, the valve is first opened from the one with the smaller flexural rigidity, and the valve is gradually and smoothly opened toward the larger flexural rigidity according to the increase in the differential pressure with the increase in the piston speed. The attraction force between each valve and the seat can be reduced. As a result, the discontinuity of the damping force is almost eliminated, and generation of abnormal noise due to the discontinuity of the damping force can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a hydraulic shock absorber according to first and second embodiments of the present invention.

FIG. 2A is a plan view of a ring seat according to a first example of each embodiment. (B) It is a top view of the leaf valve concerning 1st Embodiment. (C) It is a top view of the leaf valve concerning a 2nd, 3rd embodiment. (D) It is a top view of the ring seat concerning the 2nd example of each embodiment. (E) It is a top view of the ring seat concerning the 3rd example of each embodiment.

FIG. 3 is a sectional view of a main part of a hydraulic shock absorber according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a hydraulic shock absorber according to the related art.

FIG. 5A is an example of a damping force characteristic of the hydraulic shock absorber according to the present invention. (B) An example of a damping force characteristic of a hydraulic shock absorber according to the related art.

[Explanation of symbols]

A upper chamber B lower chamber C bottom chamber D tank chamber BV compression side damping valve CV check valve DV suction valve PV expansion side damping valve LPV expansion side low speed area damping valve LBV pressure side low speed area damping valve 1 piston rod 5 piston 5C lower opening Window (piston side) 15 Valve case 15C Lower opening window (valve case side) 21 Cylinder 106 Auxiliary leaf valve (extended side) 107, 207, 307 Ring seat 107B, 207B, 307B Inner diameter of the ring seat 107A, 207A, 307A Peripheral edge of the ring seat 116 Auxiliary leaf valve (pressure side) 117, 217, 317 Ring seat (first, second and third embodiments on the valve case side) 117B, 217B, 317B Inner diameter of the ring seat 117A, 217A, 317A Peripheral edge of the ring seat

Claims (6)

[Claims] 1. A bottom chamber which is divided into an upper chamber and a lower chamber via a piston fastened to a piston rod, and which communicates with the lower chamber and the tank chamber via a valve case provided at a lower part of the cylinder. And a ring seat whose outer peripheral edge serves as a support point for bending of each valve is disposed on the base rear side of the check valve and the extension-side damping valve disposed on the piston, and carries each valve. While controlling the extension-side damping force when the piston rod is extended, a ring seat whose outer peripheral edge serves as a support point for bending of each valve is provided on the base-side rear surface of the suction valve and the compression-side damping valve arranged in the valve case. In a hydraulic shock absorber arranged to carry each valve and control a compression side damping force when the piston rod descends, each base end of a check valve arranged in the piston or a suction valve arranged in a valve case Either one or both of the ring seats arranged on the side back, The radial rigidity in the circumferential direction of each valve is changed by smoothly changing the radial distance from the axis of the inner diameter to the outer peripheral edge, and the valve is sequentially opened from a portion having a small flexural rigidity. Hydraulic shock absorber valve structure. 2. A bottom chamber which divides the inside of a cylinder into an upper chamber and a lower chamber via a piston fastened to a piston rod, and which communicates with the lower chamber and the tank chamber via a valve case provided at a lower part of the cylinder. And a ring seat whose outer peripheral edge serves as a support point for bending of each valve is disposed on the base rear side of the check valve and the extension-side damping valve disposed on the piston, and carries each valve. While controlling the extension-side damping force when the piston rod is extended, a ring seat whose outer peripheral edge serves as a support point for bending of each valve is provided on the base-side rear surface of the suction valve and the compression-side damping valve arranged in the valve case. In a hydraulic shock absorber arranged to carry each valve and control a compression damping force when the piston rod descends, each of a compression damping valve arranged in the piston or a compression damping valve arranged in a valve case is provided. One or both of the ring seats located on the rear side On the other hand, the radial distance from the axis of the inner diameter to the outer peripheral edge is smoothly changed to change the flexural rigidity in the circumferential direction of each of the valves, and the valves are sequentially opened from a portion having a small flexural rigidity. A valve structure for a hydraulic shock absorber, characterized in that: 3. A bottom chamber which is divided into an upper chamber and a lower chamber via a piston fastened to a piston rod, and which communicates with the lower chamber and the tank chamber via a valve case provided at a lower part of the cylinder. And a low-speed damping valve is opposed to each lower opening window of a piston or a valve case communicated with the upper chamber or the lower chamber. A ring seat that serves as a support point for the deflection of the damping valve is interposed, and an auxiliary leaf valve is arranged on the back side of the ring seat while providing a gap corresponding to the thickness of the ring seat. The pressure oil guided from the oil chamber to each lower opening window flows out to one oil chamber while flexing only the low speed range damping valve with the outer peripheral edge of the ring seat as a supporting point, and at a piston speed above the middle speed range, If the low-speed damping valve and the auxiliary leaf valve overlap, In the hydraulic shock absorber that controls the extension damping force or the compression damping force, a ring seat disposed on each base side rear surface of the low-speed range damping valve is provided with a radial distance from the axis of the inner diameter to the outer peripheral edge. A valve structure for a hydraulic shock absorber, wherein the bending rigidity of the low-speed damping valve is changed by changing smoothly, and the valve is sequentially opened from a portion having a small bending rigidity. 4. The valve structure for a hydraulic shock absorber according to claim 1, wherein an outer peripheral edge of said ring seat is a circular shape eccentric with respect to an inner diameter. 5. The valve structure for a hydraulic shock absorber according to claim 1, wherein an outer peripheral edge of said ring seat is substantially elliptical. 6. The valve structure for a hydraulic shock absorber according to claim 1, wherein an outer peripheral edge of said ring seat is substantially polygonal.