JP2002286077A - Valve device for hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To depress low the attenuation force at the initial rising time of the stroke of a hydraulic buffer and secure a high attenuation force after elapse of the initial rising time. SOLUTION: In a valve device 50 of a hydraulic buffer 10 provided with a disc valve 82 on the partition wall member 62 separating two oil chambers 31B, 52, a circular valve seat 65 is set slidably on the partition wall member 62. The valve seat 65 is moved axially by the hydraulic pressure of one oil chamber 31B to lift the disc valve 82.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a valve device for a hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a valve device of a hydraulic shock absorber,
As described in Japanese Utility Model Publication No. 59-22357, an annular partition member for partitioning two oil chambers is provided at one stroke of the hydraulic shock absorber.
A flow path is provided that flows from one oil chamber on the side where hydraulic oil contracts to the other oil chamber on the opposite side, and the flow path is opened at the opening of this flow path when the one oil chamber is contracted to open the one flow path. And a fixed disk valve for generating a damping force for the hydraulic oil flowing from the oil chamber to the other oil chamber. In the prior art,
A preset load is applied to the disc valve in order to obtain high damping force characteristics in the middle and high speed range of the hydraulic shock absorber stroke.
The damping force characteristic of the hydraulic shock absorber at this time is as shown by a two-dot chain line in FIG.

[0003]

However, in a hydraulic shock absorber in which a preset load is applied to a disk valve, the disk valve does not open until the oil pressure in the one oil chamber reaches the preset load, and the damping force of the hydraulic shock absorber is reduced. Is increased in the low speed range at the beginning of the stroke as shown by the two-dot chain line in FIG. 4, and the vibration absorption is deteriorated at the beginning of the stroke.

On the other hand, when a disk valve having a low spring constant is used in order to improve the vibration absorption at the initial stage of the hydraulic shock absorber, the damping force in the middle and high speed range of the stroke is insufficient.

[0005] It is an object of the present invention to suppress the damping force at the beginning of the stroke of the hydraulic shock absorber at a low level and to secure a high damping force after the elapse of the early stage of the stroke.

[0006]

According to a first aspect of the present invention, an annular partition member for partitioning two oil chambers is provided from one oil chamber on the side on which hydraulic oil contracts during one stroke of the hydraulic shock absorber. One flow path that flows to the other oil chamber on the opposite side is provided, and the one flow path is opened at the opening of the one flow path when the one oil chamber is contracted to open the one flow path from the other oil chamber to the other oil chamber. In a valve device of a hydraulic shock absorber provided with one of an outer peripheral edge and an inner peripheral edge of a disk valve that generates a damping force for hydraulic oil flowing into an oil chamber, an outer peripheral portion and an inner peripheral portion of the partition member are provided. An annular valve seat is slidably provided on the other side of the portion, and the valve seat moves in the axial direction by receiving the oil pressure of the one oil chamber,
The other side of the outer peripheral portion and the inner peripheral portion of the disc valve is lifted.

According to a second aspect of the present invention, in the first aspect of the present invention, the one oil on the side where the hydraulic oil expands from the other oil chamber during the other stroke of the hydraulic shock absorber is provided in the partition member. The other flow path returning to the chamber is provided, and at the opening of the other flow path, when the one oil chamber is expanded, the other flow path is opened, and the hydraulic oil flows from the other oil chamber to the one oil chamber. The check valve receives the oil pressure in the one oil chamber during the one stroke, and slides the valve seat in the axial direction.

[0008]

According to the first aspect of the present invention, the following operations are provided. In the low-speed range at the beginning of one stroke of the hydraulic shock absorber, when the oil pressure in one oil chamber first opens the disc valve to generate damping force, damping is not performed by applying a preset load to the disc valve. The power can be kept low.

As soon as the disc valve is opened by the rise of one stroke of the hydraulic shock absorber, the valve seat moves so as to fill the opening gap of the disc valve. That is, as a result of the valve seat operating so as to narrow the valve opening gap of the disc valve, the operating oil is throttled at this gap and a high damping force is generated. Therefore, even if the preset load is not applied to the disc valve, the opening gap of the disc valve is reduced in proportion to the flow rate of the stroke of the hydraulic shock absorber,
High damping force is secured in the middle and high speed range.

According to the second aspect of the present invention, the following effects are obtained. In one stroke of the hydraulic shock absorber, the check valve receives the oil pressure in one oil chamber, lifts up, and slides the valve seat in the axial direction. As a result, the valve seat moves to fill the opening gap of the disc valve described above. The operation can be surely executed.

[0011]

FIG. 1 is a sectional view showing a hydraulic shock absorber.
2 is a sectional view showing a base valve device, FIG. 3 is an enlarged view of a main part of FIG. 2, FIG. 4 is a diagram showing damping force characteristics of a hydraulic shock absorber,
5 is a schematic diagram showing the operation of the base valve device, FIG. 6 is a schematic diagram showing a first partition member, FIG. 7 is a schematic diagram showing a second partition member, FIG. 8 is a schematic diagram showing a valve seat, and FIG. It is a schematic diagram which shows a 3rd partition member.

As shown in FIG. 1, a hydraulic shock absorber 10 has a hollow piston rod 12 inserted into a cylinder 11, and a suspension spring 1 provided outside the cylinder 11 and the piston rod 12.
3 are interposed.

The cylinder 11 has a vehicle body-side mounting portion 14,
The piston rod 12 includes a wheel-side mounting portion 15. A spring support adjusting ring 16 and a spring support 17 are screwed around the outer periphery of the cylinder 11, and the spring support 1 is mounted on the piston rod 12.
8 is fixed, a suspension spring 13 is interposed between the spring support 17 and the spring support 18, and the spring support adjustment ring 1
The set length of the suspension spring 13 can be adjusted by the screwing of the spring support 6 and the spring receiver 17. The elastic force of the suspension spring 13 absorbs the impact force that the vehicle receives from the road surface.

The cylinder 11 has a rod guide 21 through which the piston rod 12 passes. Rod guide 21
Is inserted into the cylinder 11 in a liquid-tight manner via the O-ring 22, and the piston rod 12 is slidable in a liquid-tight manner on the inner diameter portion provided with the oil seal 23, the bush 24, and the dust seal 25.

The cylinder 11 is provided on the compression side damper 26 outside the rod guide 21, and a damper stopper 27 provided on the piston rod 12 abuts on the compression side damper 26 to regulate the maximum compression stroke. Further, the cylinder 11 includes a rebound rubber 28 on an inner end surface of the rod guide 21, and the rebound stopper 2 included in the piston rod 12.
9 is abutted against the rebound rubber 28 to regulate the extension stroke.

The hydraulic shock absorber 10 has a piston valve device (extension-side damping force generator) 30 and a base valve device (compression-side damping force generator) 50. Hydraulic shock absorber 1
0 is the piston valve device 30 and the base valve device 50
Causes the expansion and contraction vibration of the cylinder 11 and the piston rod 12 due to the absorption of the impact force by the suspension spring 13.

(Piston Valve Apparatus 30) (FIG. 1) The hydraulic shock absorber 10 has an oil chamber 31 formed in the cylinder 11 and is provided at the tip of a piston rod 12 slidably inserted into the cylinder 11. The oil chamber 31 is moved by the piston 32 into the rod-side oil chamber 3 that houses the piston rod 12.
1A and a piston-side oil chamber 31B (one oil chamber) not accommodating the piston rod 12, and a piston 32 is provided with a piston valve device 30.

The piston valve device 30 is provided with an extension flow path 33 and a compression flow path 34 as communication paths between the rod-side oil chamber 31A and the piston-side oil chamber 31B in the piston 32. Each of the paths 34 is provided with an extension-side disc valve 33A and a compression-side disc valve 34A. In the piston valve device 30, the expansion-side damping force based on the bending deformation of the expansion-side disk valve 33A is applied to the compression-side disk valve 34A.
Is set so as to be larger than the compression side damping force based on the bending deformation of.

In the piston valve device 30, a damping force adjusting rod 42 operated by a slider device 41 is passed through a hollow portion of the piston rod 12 so as to be able to advance and retreat. The opening area of the bypass passage 44 between the rod-side oil chamber 31A and the piston-side oil chamber 31B provided in the pipe 12 can be adjusted.

Therefore, during the compression stroke of the hydraulic shock absorber 10, the oil in the piston-side oil chamber 31A passes through the pressure-side flow path 34, opens the pressure-side disc valve 34A, and is guided to the rod-side oil chamber 31A.

During the extension stroke of the hydraulic shock absorber 10,
When the relative speed between the cylinder 11 and the piston rod 12 is low, the oil in the rod-side oil chamber 31A flows to the piston-side oil chamber 31B through the bypass flow path 44 having the needle valve 43, and the throttle resistance by the needle valve 43 during this time. This causes a damping force on the extension side. This damping force is adjusted by rotating the slider device 41.

When the relative speed between the cylinder 11 and the piston rod 12 is medium or high during the extension stroke of the hydraulic shock absorber 10, oil in the rod-side oil chamber 31A passes through the extension-side flow path 33 and the extension-side disc valve 33A. Is bent and guided to the piston-side oil chamber 31B to generate an extension-side damping force.

(Base Valve Device 50) (FIGS. 1 to 9) The hydraulic shock absorber 10 has a sub-tank 51 integrally connected to the cylinder 11 and an oil sump chamber 52 (FIG. 1) communicating with the piston side oil chamber 31B of the cylinder 11. The other oil chamber) is provided in the sub-tank 51, and the base valve device 50 is provided in the communication path 70 provided in the partition wall member 60 that partitions the piston-side oil chamber 31 </ b> B and the oil reservoir 52.
Is provided. The partition member 60 includes a first partition member 61, a second partition member 62, and a third partition member 63.
Numeral 0 includes a low-speed channel 71, a medium-speed channel 72, a high-speed channel 73, and an extension-side channel 74. The sub tank 51 is provided with a diaphragm (or a free piston) that separates an oil reservoir 52 and a pressurized gas chamber.

As shown in FIG. 2, the base valve device 50 includes a piston side oil chamber 31B of the sub tank 51 and an oil reservoir 5
The throttle member 53 is pressed into the communication area of the
The valve housing 55 and the third partition member 63 are held in the sub-tank 51 by plug bolts 54 screwed to the first and second partition members 61 and 62 between the throttle member 53 and the third partition member 63. Hold.

The partition member 60 (61, 62, 63) includes a low-speed flow path 71 provided with a throttle valve 81, a medium-speed flow path 72 provided with a pressure-side sub-disc valve 82 (one flow path), and a pressure-side main High-speed flow path 73 with disk valve 83 and expansion-side flow path 74 with expansion-side check valve 84 (the other flow path)
And the low-speed flow path 71, the medium-speed flow path 72, the high-speed flow path 73, and the extension-side flow path 74 are respectively branched directly from the piston-side oil chamber 31B side and arranged in parallel with each other.

More specifically, the first partition member 61 has a hollow center rod 91 forming a low-speed flow path 71 at the center. The second partition wall member 62 is disposed around the center rod 91 and forms a plurality of medium-speed flow paths 72 and an extension-side flow path 74. The third partition member 63 is axially separated from the second partition member 62 to form a plurality of high-speed flow paths 73.

More specifically, as shown in FIG. 6, the first partition member 61 has an intermediate portion of the center rod 91 screwed into a center hole 61B of the annular body 61A, and is provided at a plurality of circumferential positions of the annular body 61A. An L-shaped fitting leg 61D including a communication hole 61C communicating with the middle-speed flow path 72, the high-speed flow path 73, and the extension-side flow path 74, and extending radially from a plurality of circumferential positions on the outer periphery of the annular body 61A.
Is held on an inner peripheral portion of a skirt portion 63B described later of the third partition member 63. The first partition member 61 is adjacent to the leg 61D.
The space between them is defined as a communication portion 61E that communicates with the medium-speed channel 72, the high-speed channel 73, and the extension-side channel 74. Also, the first partition member 61
Is located on the inner end face surrounded by the leg 61D of the annular body 61A,
A spring holding portion 61F for the extension side check valve 84 is provided.

An adjusting lever 92 is fitted to the plug bolt 54 screwed to the sub tank 51 so as to be rotatable in a liquid-tight manner.
3 is rotatably inserted in a liquid-tight manner.
3 is provided with the above-described throttle valve 81 (needle valve) that can be engaged in the rotational direction and relatively moved in the axial direction at the distal end of the nut 3, and a nut 94 caulked and fixed to the distal end side of the adjust lever 92.
The external thread of the throttle valve 81 is screwed. The adjusting rod 93 is provided with a spacer and a ball 96 by a set spring 95. By rotating the adjusting rod 93, the ball 96 is sequentially engaged with the engaging concave portions 92A at a plurality of circumferential positions of the adjusting lever 92. Thereby, the throttle valve 81 is moved forward and backward with respect to the low-speed flow path 71 of the center rod 91, and the opening area of the low-speed flow path 71 can be adjusted.

As shown in FIG. 7, the second partition member 62 forms medium-speed flow paths 72 at a plurality of circumferential positions of an annular body 62A (having an outer peripheral thick ring portion 62B and an inner peripheral thin ring portion 62C). The extension side flow path 74 can be formed by the center hole. The outer peripheral thick ring portion 62B of the second partition member 62 is fitted to the inner peripheral holding portion 61G of the leg portion 61D of the first partition member 61 together with the pressure side sub-disc valve 82 and the shim 82A for closing the medium speed flow path 72. The annular body 6 of the first partition member 61
In a state in which a flow path 70A is formed between the first partition 1A and the annular body 61A so as to be separated from the annular body 61A in the axial direction, the third partition 63 is held by an annular body 63A described later. The compression-side sub-disc valve 82 constitutes an inner peripheral bending valve whose outer peripheral edge is held by the annular body 63A of the third partition member 63,
As a result, the spring constant is increased, the damping force in the medium speed range is increased, and a feeling of waist (resistance) can be secured.

The second partition member 62 has an outer peripheral thick ring portion 62.
The locking surface 62E for the valve seat 65, which will be described later, of the inner peripheral thin ring portion 62C is set at a low step relative to the valve fixing surface 62D in contact with the pressure side sub-disc valve 82 of B. The opposite end face of the portion 62C to the pressure side disc valve 82 is flush.

That is, the second partition member 62 includes two oil chambers, the piston side oil chamber 31B (one oil chamber) and the oil reservoir 5
2 (the other oil chamber) is formed into an annular shape, and the hydraulic shock absorber 1
During a compression stroke of 0 (one stroke), a medium-speed flow path 72 (one flow path) that flows from the oil chamber 31B on the side where the hydraulic oil contracts to the oil storage chamber 52 on the opposite side is provided. The second partition member 62 has a damping force on the outer peripheral portion surrounding the opening of the middle-speed flow path 72 when the piston-side oil chamber 31B opens and contracts, and the hydraulic oil flows from the oil chamber 31B to the oil reservoir 52. Is fixed at the outer peripheral edge of the pressure-side sub-disk valve 82 that generates the pressure.

Further, as shown in FIGS. 2 and 3, an annular valve seat 65 is attached to the second partition member 62 as an accessory. As shown in FIG. 8, the valve seat 65 includes an annular body 65A (the valve seat surface 65B and the engaging surface 65B) slidably fitted to the inner peripheral portion of the inner peripheral thin annular portion 62C of the second partition member 62.
C and a pressing surface 65D). Before the start of the compression stroke of the hydraulic shock absorber 10, the piston side oil chamber 31B
In the state where the hydraulic pressure does not act on the expansion-side check valve 84, as shown in FIG. 5A, the valve seat 65 has the valve seat surface 65B provided on the inner peripheral portion of the compression-side sub-disc valve 82 without a gap or a minute gap (valve). (Seat surface 65B is set slightly lower than valve fixing surface 62D of second partition member 62.)
, The engaging surface 65C is opposed to the engaging surface 62E of the inner peripheral thin ring portion 62C of the second partition member 62, and is opposite to the valve seat surface 65B. Of the extension side check valve 84 to be described later.
B is set so as to be able to contact with no gap or with no load via a small gap, and as a result, the preset load is not applied to the pressure side sub-disc valve 82. Then, when the extension side check valve 84 receives the oil pressure of the piston side oil chamber 31B during the compression stroke of the hydraulic shock absorber 10, as shown in FIG.
4B pushes the pushing surface 65D of the valve seat 65 to move the valve seat 65 to the inner peripheral thin annular portion 62C of the second partition member 62.
Axially along the inner periphery of the valve seat 65
Sets the valve seat surface 65B to the pressure side sub-disc valve 82.
To lift the inner peripheral portion of the pressure side sub-disc valve 82 to start bending deformation of the pressure side sub-disk valve 82. Then, the cylinder 11 of the hydraulic shock absorber 10
As the relative speed of the piston rod 12 and the piston oil 12 increases, and the flow rate of the hydraulic oil from the piston side oil chamber 31B to the oil reservoir 52 increases, as shown in FIG. , Pressure side sub-disc valve 82
Is separated from the valve seat surface 65B of the valve seat 65 to form a valve opening gap proportional to the flow rate.

As shown in FIG. 9, the third partition member 63 forms high-speed flow paths 73 at a plurality of positions in the circumferential direction of the annular body 63A, and includes a skirt 63B extending cylindrically from the outer periphery of the annular body 63A and a sub-tank 51. And the leg portion 61D of the first partition member 61 is attached to the inner peripheral portion of the skirt portion 63B.
Is held. The third partition member 63 has a low-speed flow path 71 of the center rod 91, a medium-speed flow path 72 of the second partition member 62, and an extension-side flow path 74 by an inner cylindrical portion 63 </ b> C extending cylindrically from the inner periphery of the annular body 63 </ b> A. (The flow path 7 of the valve spring 55)
A flow path 70B that communicates with the oil reservoir 52 (via OC) is formed. The third partition member 63 has a pressure-side main disk valve 83 for closing the high-speed flow path 73 and a shim 83A thereof mounted on the outer periphery of the inner cylindrical portion 63C. The compression side main disk valve 83 is provided with a valve stopper 8 screwed to the inner cylindrical portion 63C.
3B constitutes an outer peripheral flexure valve whose inner peripheral end is held, lowers the spring constant, ensures blowing at high speeds, and instantaneously reduces the compression side damping force when passing over a road surface with a large gap. It can be reduced.

An adjust guide 97 is screwed into the screw portion of the above-described adjust lever 92 rotatably fitted to the plug bolt 54 screwed into the sub tank 51.
The adjusting guide 97 is connected to a parallel pin 98 slidably engaged with a guide groove provided in the plug bolt 54, and the adjusting guide 97 supports the initial load setting spring 100 for the compression-side main disc valve 83 on the back side. The spring force of the spring 100 can be applied to the compression-side main disc valve 83 via the spring seat 99. By rotating the adjustment lever 92, the adjustment guide 97 is moved in the axial direction,
As a result, the valve opening load of the compression side main disk valve 83 can be adjusted.

The extension side check valve 84 is connected to the center rod 9.
A guide portion 84A slidingly contacting the outer circumference of the first partition member 6;
And a valve portion 84B which comes into contact with and separates from the opening of the second extension side flow path 74.

That is, the hydraulic shock absorber 1 is attached to the second partition member 62.
At the time of the extension stroke of 0, an extension-side flow path 74 is provided to return to the piston-side oil chamber 31B on the side where the hydraulic oil expands from the oil reservoir chamber 52, and the piston-side oil chamber 31B is enlarged at the opening of the extension-side flow path 74. An extension-side check valve 84 is provided, which is sometimes separated from the opening of the extension-side flow path 74, opens the extension-side flow path 74, and returns hydraulic oil from the oil reservoir 52 to the oil chamber 31B. At this time, the extension-side check valve 84 can be biased in the closing direction of the extension-side flow path 74 by a spring 101 supported on the back surface of the spring holding portion 61F of the first partition wall member 61, and the opening of the extension-side flow path 74 is opened. The extension-side check valve 84 apart from the portion can be urged in the closing direction of the extension-side flow path 74 that is in contact with the opening of the extension-side flow path 74. However, the spring 101 is not pre-compressed in the free state before the rise of the extension side stroke of the hydraulic shock absorber 10 and the valve portion 84B of the extension side check valve 84 is attached to the pressing surface 65D of the valve seat 65 as described above. The abutment is performed with no load, and as a result, the preset load is not applied to the compression side sub-disc valve 82.

Therefore, during the compression stroke of the hydraulic shock absorber 10, oil corresponding to the volume of the piston rod 12 that has entered the cylinder 11 is transferred from the piston side oil chamber 31B to the communication path 70.
(71, 72, 73) and is discharged to the oil reservoir 52B.

At this time, when the relative speed between the cylinder 11 and the piston rod 12 is low, the compression side damping force is obtained by the throttle resistance of the throttle valve 81 provided in the low speed flow passage 71. This damping force is adjusted by adjusting the position of the throttle valve 81 by the adjuster rod 93.

The cylinder 11 and the piston rod 12
When the relative speed becomes medium speed, the compression side sub-disc valve 82 provided in the medium speed flow path 72 bends to obtain a compression side damping force.

The cylinder 11 and the piston rod 12
When the relative speed becomes high, the compression side main disc valve 83 provided in the high speed flow path 73 is bent and deformed, so that the compression side damping force is obtained. This damping force is applied to the adjustment lever 92.
The initial load setting spring 100 is adjusted by adjusting the initial load.

During the extension stroke of the hydraulic shock absorber 10, oil corresponding to the retraction volume of the piston rod 12 retreating from the cylinder 11 flows from the oil reservoir 52 to the extension side flow path 74 and the extension side check valve 8.
4 and is returned to the piston side oil chamber 31B.

However, in the base valve device 50 of the hydraulic shock absorber 10, the valve seat 65 is attached to the second partition member 62 provided with the pressure-side sub-disc valve 82. The obtained pressure-side damping force characteristic is as shown by the solid line in FIG. That is, according to the present embodiment, the following operations are provided.

When the hydraulic pressure in the piston-side oil chamber 31B first opens the compression-side sub-disc valve 82 to generate a damping force in the low-speed range at the early stage of the rise of the compression stroke of the hydraulic shock absorber 10, the compression-side sub-disc valve 82 is preset. By not applying a load, the damping force can be kept low.

As soon as the compression side sub-disc valve 82 is opened by the rise of the compression stroke of the hydraulic shock absorber 10, the valve seat 65 is moved so as to fill the opening gap of the compression side sub-disc valve 82. That is, as a result of the valve seat 65 operating so as to narrow the valve opening gap of the pressure side sub-disc valve 82, the hydraulic oil is throttled in this gap and a high damping force is generated. Therefore, the compression side sub-disc valve 82
Hydraulic shock absorber 1 without applying a preset load to
0 in proportion to the flow rate in the zero stroke.
The valve opening gap is narrowed, and high damping force is secured in the middle and high speed range.

In the compression stroke of the hydraulic shock absorber 10, the expansion-side check valve 84 receives the oil pressure in the piston-side oil chamber 31B, lifts up, and slides the valve seat 65 in the axial direction. The movement operation for filling the valve opening gap of the compression side sub-disc valve 82 can be surely executed.

In this embodiment, the following operation is also provided. The low-speed flow path 71, the medium-speed flow path 72, the high-speed flow path 73, and the extension-side flow path 74 are parallel to each other, and are each directly branched from the piston-side oil chamber 31B. Therefore, the flow area of the medium-speed flow path 72 having the pressure side sub-disc valve 82 is increased,
Since the flow path length can be shortened and a sufficient flow rate of hydraulic oil can be secured, a stable pressure-side damping force can be generated in a medium speed range (low speed range to high speed range excluding the extremely low speed range). Waist feeling (resistance) in the medium speed range
To obtain steering stability.

The pipe resistance of the medium speed flow path 72 can be reduced.
When the compression stroke and the expansion stroke are frequently switched, the followability of the compression-side sub-disc valve 82 is improved,
Eliminates response delay and prevents pressure-side damping force from falling off.

When passing on a road surface having a large gap,
In a high-speed range in which the piston 32 moves at a high speed, a shock can be absorbed by a high blowing effect of the compression-side main disc valve 83, and a soft ride can be obtained.

The small-diameter low-speed flow path 7 is
1 and a medium-speed flow path 72, a high-speed flow path 73, and a growth-side flow path 74 are formed in parallel with each other in an annular space having a large area around the center rod 91. Therefore, the flow area of the medium-speed flow path 72 can be reliably increased.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design may be changed without departing from the scope of the present invention. The present invention is also included in the present invention. For example, in a valve device of the present invention, in a piston valve device in which a disc valve is provided in a piston (partition member) that partitions a rod-side oil chamber and a piston-side oil chamber inside a cylinder, an annular valve seat is provided in the piston. Alternatively, the disc seat may be lifted by sliding the valve seat in the axial direction by the oil pressure of one oil chamber.

[0051]

As described above, according to the present invention, the damping force at the beginning of the stroke of the hydraulic shock absorber can be kept low, and a high damping force can be secured after the elapse of the beginning of the stroke.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a hydraulic shock absorber.

FIG. 2 is a sectional view showing a base valve device.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a diagram showing a damping force characteristic of the hydraulic shock absorber.

FIG. 5 is a schematic view showing the operation of the base valve device.

FIG. 6 is a schematic view showing a first partition member.

FIG. 7 is a schematic view showing a second partition member.

FIG. 8 is a schematic view showing a valve seat.

FIG. 9 is a schematic view showing a third partition member.

[Explanation of symbols]

 Reference Signs List 10 hydraulic shock absorber 31B piston-side oil chamber (one oil chamber) 50 base valve device (valve device) 52 oil reservoir (other oil chamber) 65 valve seat 72 medium-speed flow path (one flow path) 74 extension side Flow path (the other flow path) 82 Pressure side sub-disc valve (disk valve) 84 Extension side check valve (check valve)

Claims (2)

[Claims] An annular partition member for partitioning two oil chambers is provided with one hydraulic chamber that flows from one oil chamber on the contracting side to the other oil chamber on the opposite side during one stroke of the hydraulic shock absorber. A flow path is provided, and at the opening of the one flow path, when the one oil chamber is contracted, the one flow path is opened to attenuate hydraulic fluid flowing from the one oil chamber to the other oil chamber. In the valve device of the hydraulic shock absorber provided with one of the outer peripheral edge and the inner peripheral edge of the disk valve generating a fixed, an annular valve seat is provided on the other side of the outer peripheral portion and the inner peripheral portion of the partition member. The valve seat is slidably provided, and receives the oil pressure of the one oil chamber, moves in the axial direction, and lifts the other side of the outer peripheral portion and the inner peripheral portion of the disc valve. Vessel valve device. 2. The other partition passage member is provided with another flow path for returning to the one oil chamber on the side where the operating oil expands from the other oil chamber during the other stroke of the hydraulic shock absorber. A check valve is provided at the opening of the flow path to open the other flow path when the one oil chamber is expanded and return hydraulic oil from the other oil chamber to the one oil chamber, The valve device for a hydraulic shock absorber according to claim 1, wherein the valve seat is slid in the axial direction by receiving the oil pressure in the one oil chamber during the stroke.