JP2002013579A - Damping force regulation type hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damping force regulation type hydraulic shock absorber in which a stable orifice characteristic can be obtained and a setting range of damping force can be set wider, even if valve opening pressure of a damping valve is made small. SOLUTION: A main disc 22 having an oil path 22a is seated on a valve seat 21. On an oil path 13 side at the extension side of the main disc 22 (upstream side), a notched disc 200 having a plurality of notches 200a circumferentially which communicate with the oil path 22a of the main disc 22 and a blocking disc 300 having the same diameter as the notched disc 200 are laminated in this order. Since the fluid flow pressure of oil flow makes each disc firmly adhere and acts on the main disc in the direction which opens the valve, area of the fixed orifice can be maintained constant and a stable orifice characteristic can be obtained, and further since the valve opening force of the main disc is not being raised, the setting range of damping force can be set wider.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile is provided with a damping force that can be appropriately adjusted in order to improve riding comfort and steering stability in accordance with road surface conditions, running conditions, and the like. There is a damping force adjustable hydraulic shock absorber.

[0003] For example, as described in Japanese Patent Application Laid-Open No. H11-94004, in this damping force adjustable hydraulic shock absorber, a damping valve (pilot type damping valve) provided in a main passage is provided.
A pilot chamber (pressure chamber) is provided downstream of the pilot chamber, oil fluid is guided from the upstream side of the main passage into the pilot chamber, and a variable orifice (regulating valve) provided downstream of the pilot chamber is opened and closed to open and close the pilot chamber. To adjust.

In this damping force adjusting type hydraulic shock absorber,
An oil passage for guiding the oil liquid to the pilot chamber is provided in the damping valve,
On the downstream side (pilot chamber side), a valve spring having a fixed orifice (notch) is formed, and further downstream of the valve spring, a plurality of disks that close the notch of the valve spring in the axial direction are damped. The valves are stacked with an initial load applied so as to urge the valves in the valve closing direction. Thus, the pilot chamber provided downstream of the damping valve is connected to the cylinder chamber upstream of the damping valve via a notch (fixed orifice) of the valve spring.

By opening and closing the variable orifice, the communication passage area between the two chambers in the cylinder is adjusted, and the pressure in the pilot chamber is changed by the pressure loss generated in the variable orifice to reduce the valve opening pressure of the disk valve. Can be changed. In this way, the orifice characteristics (the damping force is approximately proportional to the square of the piston speed) and the valve characteristics (the damping force is approximately proportional to the piston speed) can be adjusted.

[0006]

By the way, the recent trend of the damping force-adjustable hydraulic shock absorber has been to improve the driving stability on rough roads and to improve the riding comfort on undulating roads. It is desired to widen the setting range of the attenuation characteristic so that the attenuation characteristic can be obtained accordingly.

However, according to the conventional damping force adjusting type hydraulic shock absorber as described above, a valve spring provided with a notch constituting a fixed orifice is provided on the downstream side of the damping valve, and the notch of the valve spring is arranged in the axial direction. A plurality of discs to be closed are stacked in this order, and a predetermined initial load is applied to the valve spring and the disc so as to urge the damping valve in the valve closing direction. Therefore, it was difficult to obtain valve characteristics in a low piston speed range.

Therefore, the setting range of the attenuation characteristic is restricted, and the above-mentioned demands cannot be sufficiently satisfied.

Therefore, in order to solve the above problem, it is necessary to reduce the initial load of the valve spring and the disc for urging the damping valve in the valve closing direction to be sufficiently small so as to reduce the valve opening pressure of the damping valve. However, in this case, the valve spring and the disk are separated from each other due to the flow pressure of the oil liquid, and there is a problem that stable orifice characteristics cannot be obtained.

The present invention has been made in view of the above points, and provides a stable orifice characteristic even when the valve opening pressure of the damping valve is reduced, thereby providing a wider damping force setting range. An object of the present invention is to provide an adjustable hydraulic shock absorber.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a cylinder filled with an oil liquid, a piston slidably fitted in the cylinder,
A piston rod having one end connected to the piston and the other end extending to the outside of the cylinder, a main passage through which oil fluid flows by sliding of the piston rod, and a damping valve provided in the main passage. A fixed orifice provided in the damping valve, a sub-passage that branches off from the main passage via the fixed orifice, and is provided in the sub-passage through which the oil liquid flows by sliding of the piston rod. A damping force-adjustable hydraulic shock absorber comprising an adjusting valve that can be adjusted from the outside, and adjusting a damping force of the damping valve by changing a pressure between the fixed orifice and the adjusting valve,
The damping valve includes: a main disk provided with an oil hole; a notch disk provided at an upstream side of the main disk and provided with at least one notch communicating with the oil hole and extending in a radial direction; A closed orifice is provided on the upstream side of the disc, comprising a closed disc that closes a position facing the oil hole of the notch, and an oil passage formed by the main disc, the closed disc, and the notch constitutes a fixed orifice. I do.

As described above, since the notched disk and the closed disk are stacked in this order on the upstream side, not on the downstream side of the main disk, the flowing pressure of the oil liquid causes the disks to come into close contact with each other and opens the main disk in the direction in which the main disk is opened. Therefore, the area of the fixed orifice can be kept constant without increasing the valve opening pressure of the main disk.

According to a second aspect of the present invention, in the first aspect of the present invention, an initial load is applied to the closed disk so as to bias the closed disk toward the main disk.

With this configuration, the main disk, the notched disk, and the closed disk are applied to each disk by the flow pressure of the oil liquid, and the initial load is also applied to each disk, so that the minute amount of the oil liquid is reduced. The area of the fixed orifice can be kept constant even during flow (the piston speed is extremely low).

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In FIG. 2, only the main passage A and the sub-passage B on the extension side are indicated by arrows, and in FIG. 3, only the extension-side pilot damping valve portion is enlarged.

The damping force-adjustable hydraulic shock absorber 1 of the present invention has a double cylinder structure in which an outer cylinder (not shown) is provided outside the cylinder 2, and a reservoir is provided between the cylinder 2 and the outer cylinder. (Not shown) are formed. A piston 3 is slidably fitted in the cylinder 2, and the piston 3 divides the inside of the cylinder 2 into an upper cylinder chamber 2 a and a lower cylinder chamber 2.
b and two rooms. A substantially cylindrical piston bolt 4 is inserted into the piston 3 and fixed by a nut 5. A solenoid case 7 fixed to one end of a piston rod 6 is screwed into a large diameter portion 4a formed at the base end of the piston bolt 4, and the other end of the piston rod 6 is connected to the cylinder upper chamber 2a. As shown in the figure, the cylinder 2 is inserted through a rod guide and an oil seal (both not shown) mounted on the upper ends of the cylinder 2 and the outer cylinder, and extends outside the cylinder 2. At the lower end of the cylinder 2, a base valve (not shown) for dividing the cylinder lower chamber 2b and the reservoir is provided.

The piston 3 includes cylinder upper and lower chambers 2a, 2a
An extension-side oil passage 13 and a contraction-side oil passage 14 for communicating between b are provided. Between the piston 3 and the nut 5, an extension-side damping force generating mechanism 15 that controls the flow of the oil liquid in the extension-side oil passage 13 is provided. Between the piston 3 and the large-diameter portion 4a of the piston bolt 4, a contraction-side oil passage 14 is provided.
A contraction side damping force generation mechanism 16 for controlling the flow of the oil liquid is provided. The base valve is provided with an oil passage (not shown) for communicating the cylinder lower chamber 2b with the reservoir.
A check valve (not shown) that allows only the flow of the oil liquid from the reservoir side to the cylinder lower chamber 2b side is provided in this oil path, and when the pressure of the oil liquid in the cylinder lower chamber 2b reaches a predetermined pressure. A disc valve (not shown) is provided to open the valve and allow the oil liquid to flow to the reservoir side. An oil liquid is sealed in the cylinder 2, and an oil liquid and a gas of a predetermined pressure are sealed in the reservoir.

Next, the extension side damping force generating mechanism 15 will be described. On the end face of the piston 3 on the cylinder lower chamber 2b side,
An annular valve seat 21 is protruded, and an oil passage 22 is provided in the valve seat 21.
The main disk 22 provided with a (oil hole) is seated.

On the extension side oil passage 13 side (upstream side) of the main disk 22, a plurality of notches 200a communicating with the oil passage 22a of the main disk 22 and extending radially and having an open outer periphery are provided at a plurality of positions in the circumferential direction (FIG. The notch disks 200 provided are stacked at eight positions. The notch disks 200 have the same diameter as the notch disks 200 on the extension side oil passage 13 side.
A closing disk 300 that closes the axial position of the oil passage 22a that faces the oil passage 22a is stacked.

The main disk 22, the notch disk 200 and the closing disk 300 constitute an extension-side pilot damping valve (damping valve).

Here, the total area of the fixed orifice 27 (radial cross section of the notch 200a) communicating the upstream side (extension-side oil passage 13) of the main disk 22 and a back pressure chamber 22A described later is the total area of the notch disk 200. It is determined by the thickness, the circumferential length of the radial cross section of the notch 200a, and the number of the notches 200a, and the total area of the fixed orifices 27 corresponds to the total area of the fixed orifices described in the related art.

An annular fixing member 23 is attached to the piston bolt 4 between the piston 3 and the nut 5.
A movable ring 24 is slidably fitted on the outer periphery of the fixed member 23. The movable ring 24 is brought into contact with the main disk 22 by a disk-shaped leaf spring 26 clamped between the fixed member 23 and the nut 5 to reduce the internal pressure between the main disk 22 and the fixed member 23. A back pressure chamber 22A that acts in the valve closing direction of the main disk 22 is formed.

The back pressure chamber 22A is communicated with the extension side oil passage 13 by a fixed orifice 27 formed by a notch 200a of the notch disk 200. The back pressure chamber 22A is
The oil passages 28 and 29 provided on the side wall of the piston bolt 4 communicate with the opposite side of the fixing member 23 via the extension-side pressure control valve 30 provided inside the piston bolt 4, and are provided on the leaf spring 26. Oil passage 32 and leaf spring 26
Is communicated with the cylinder lower chamber 2b via a check valve 31 laminated on the cylinder.

The compression side damping force generating mechanism 16 will be described. An annular valve seat 33 protrudes from an end surface of the piston 3 on the side of the cylinder upper chamber 2a, and an oil passage 34a (oil hole) is formed in the valve seat 33.
The main disk 34 provided with is seated.

On the contraction side oil passage 14 side (upstream side) of the main disk 34, a plurality of notches 201a communicating with the oil passage 34a of the main disk 34 and extending radially and having an open outer periphery are provided at a plurality of positions in the circumferential direction (FIG. The notch disk 201 provided is stacked at eight positions. The notch disk 201 further has a notch 201a having the same diameter as the notch disk on the contraction side oil passage 14 side of the notch disk 201.
A blocking disk 301 that closes an axial position facing the oil passage 34a is laminated.

The main disk 34, the notch disk 201 and the closing disk 301 constitute a contraction-side pilot damping valve (damping valve).

Here, the total area of the fixed orifice 40 (radial cross section of the notch 201a) communicating the upstream side (the contraction side oil passage 14) of the main disk 34 and the back pressure chamber 39 described later is the extension side pilot type. Like the damping valve, the thickness is determined by the thickness of the notch disk 201, the circumferential length of the radial cross section of the notch 201a, and the number of the notches 201a.

An annular fixing member 35 is attached to the piston bolt 4 between the large diameter portion 4a and the piston 3, and a movable ring 36 is slidably fitted around the outer periphery of the fixing member 35. I have. The movable ring 36 is brought into contact with the main disk 34 by a disk-shaped leaf spring 38 clamped between the fixed member 35 and the large-diameter portion 4a, and is disposed between the main disk 34 and the fixed member 35. A back pressure chamber 39 for applying the internal pressure in the valve closing direction of the main disk 34 is formed.

The back pressure chamber 39 is connected to the contraction side oil passage 14 by a fixed orifice 40 formed by a notch 201a of the notch disk 201. In addition, the back pressure chamber 39 is provided on the opposite side of the fixing member 35 by oil passages 41 and 42 provided on the side wall of the piston bolt 4 via a compression side pressure control valve 43 provided inside the piston bolt 4. Communicated,
An oil passage 45 provided in the leaf spring 38 and a check valve 44 laminated on the leaf spring 38 communicate with the cylinder upper chamber 2a.

Here, on the extension side and the contraction side, the height t1 of the valve seats 21 and 33 is set to notch discs 200 and 20.
1 and the thickness t3 of the closing disks 300 and 301.
Are set (lower) than the sum of (t1 <(t2 +
t3)), the notched disks 200 and 201 and the closed disks 300 and 301 have the main disks 22 and 3 respectively.
An initial load is applied so as to urge No. 4 in the valve opening direction.

The movable ring 2 of the leaf springs 26, 38
The force (F1) for urging the main disks 22 and 34 in the valve closing direction via the cutout disks 200 and 201
And the main disk 22 of the closed disks 300 and 301,
The force (F2) is set to be larger than the force (F2) for urging the valve 34 in the valve opening direction (F1> F2).

The expansion and contraction side pressure control valves 30, 43
(Adjustment valve) will be described. In the piston bolt 4, small-diameter bores 46 are formed in the center of the oil passages 28 and 41, and large-diameter bores 47 and 48 are formed on both sides of the small-diameter bores 46. The annular valve seats 49 and 50 are formed by steps between the first and second large bores 47 and 48. A cylindrical slider 51 is slidably fitted in the small-diameter bore 46 of the piston bolt 4, and an oil passage is provided between the small-diameter portion formed at both ends of the slider 51 and the small-diameter bore 46. 28, 4
Annular valve chambers 52 and 53 communicating with 1 are formed.
Valve seats 49, 50 are provided at both ends of the slider 51, respectively.
The sub-valve members 54 and 55 which take off and seat on the
It is press-fitted and installed.

A proportional solenoid 58 is provided in the solenoid case 7, and a plunger 59 has an operating rod 60.
Is press-fitted and fixed. The coil 73 is provided with a lead wire 74 connected thereto, and the lead wire 74 is connected to the piston rod 6.
And extends to the outside through a hollow portion of the camera and is connected to a controller (not shown).

The distal end of the operating rod 60 is
Is in contact with a sub-valve member 55 attached to one end of the valve. The large-diameter bore 47 of the piston bolt 4 is screwed with an adjustment plug 61 and a lock nut 62 for closing the distal end thereof, and a sub-valve member 54 attached to the other end of the slider 51 and the adjustment plug 61. Between them, a compression spring 63 acting against the suction force of the plunger 59 is interposed.

The sub-valve members 54 and 55 include a slider 5
The oil chambers 65 and 66 formed on both sides of 1 are communicated with each other,
Oil passages 67 and 68 for balancing the pressures acting on both ends of the slider 51 are provided.

The small diameter bores 46 in the oil chambers 52, 53 of the piston bolt 4 are provided with steps 69, 70 at positions in the oil chambers 52, 53, respectively. Pressure receiving areas of the sub-valve members 54 and 55 (pressure receiving areas of the slider 51 generating thrust in the valve opening direction) than pressure receiving areas of the steps 71 and 72 (pressure receiving areas of the slider 51 generating thrust in the valve closing direction). Is larger.

When the coil 73 is not energized, the slider 5
1 is that the auxiliary valve member 54 is seated on the valve seat 49 and the auxiliary valve member 55 is held at a position separated from the valve seat 50 by the compression spring 63. The solenoid 58 causes the plunger 59 to move downward in the drawing against the compression spring 63 by an attraction force corresponding to the magnitude of the energizing current, and causes the sub-valve member 54 to open in the valve opening direction and the sub-valve member 55 to close in the valve closing direction. Is selectively energized.

The initial load of the compression spring 63 is set as follows.
The adjustment can be performed by the adjustment plug 61 and the lock nut 62.

Next, the operation of the present embodiment configured as described above will be described.

During the extension stroke of the piston rod 6, the oil liquid in the cylinder upper chamber 2a is pressurized with the movement of the piston 3, and the main disk 22 of the extension-side damping force generating mechanism 15 is pressed.
Before the valve is opened (low-speed range of piston speed), the expansion-side oil passage 13 branches off from the main passage A via the fixed orifice 27, and the back pressure chamber 22A, the oil passage 28, the expansion-side pressure control valve 30, the oil The fluid flows toward the cylinder lower chamber 2b through a sub-passage B including the passage 29, the oil passage 32, and the check valve 31. When the pressure on the cylinder upper chamber 2a side reaches the valve opening pressure of the main disk 22 (high piston speed range), the main disk 22 is opened, and the oil liquid flows from the elongate oil passage 13 through the main passage A to the lower cylinder. Flows directly into chamber 2b. In addition, the amount of oil that the piston rod 6 has withdrawn from the cylinder 2 opens the check valve of the oil passage of the base valve from the reservoir, and the cylinder lower chamber 2
Flow to b.

Thus, before the main disk 22 is opened (low piston speed range), the fixed orifice 2
7 and the extension-side pressure control valve 30 generate a damping force. At this time, due to the flow pressure of the oil liquid from the extension side oil passage 13 and the initial load of the notch disk 200 and the closing disk 300 on the main disk 22 side, the main disk 2
2. The notched disk 200 and the closed disk 300 are in close contact with each other, and a stable orifice characteristic can be obtained.

In the extension side pressure control valve 30, the pressure receiving area of the sub-valve member 54 is larger than the pressure receiving area of the step portion 71 of the slider 51 in the oil chamber 52. As a result, a thrust is generated in the slider 51 in the valve opening direction of the sub-valve member 54. On the other hand, the slider 51 is urged in the valve closing direction of the sub-valve member 54 by the compression spring 63, but the valve-opening pressure of the sub-valve member 54 can be adjusted according to the current supplied to the coil 73.
Thus, the damping force before the main disk 22 is opened (low piston speed range) can be directly controlled regardless of the piston speed.

By adjusting the valve opening pressure of the sub-valve member 54, the upstream back pressure chamber 2 is adjusted in accordance with the pressure.
Since the pressure of 2A is adjusted and the pressure of the back pressure chamber 22A acts as a pilot pressure of the main disk 22 in the valve closing direction, the valve opening pressure of the sub-valve member 54 and the valve opening pressure of the main disk 22 are similarly reduced. The damping force in the high piston speed range can be adjusted at the same time.

During the compression stroke of the piston rod 6, the check valve of the base valve is closed with the movement of the piston 3, and the hydraulic fluid in the cylinder lower chamber 2b is pressurized. Before the main disk 34 is opened (low-speed range of piston speed), the main disc 34 branches off from the main passage via the fixed orifice 40 from the contraction-side oil passage 14 to form the back pressure chamber 39, the oil passage 41, and the contraction-side pressure control valve. 43, oilway 4
2. It flows toward the cylinder upper chamber 2a through a sub-passage including the oil passage 45 and the check valve 44. And the cylinder lower chamber 2
When the pressure on the b side reaches the valve opening pressure of the main disk 34 (high piston speed range), the main disk 34 opens, and the oil liquid contracts from the contraction-side oil passage 14 through the main passage to the cylinder upper chamber 2a.
Flows directly to In addition, the oil liquid that the piston rod 6 has entered into the cylinder 2 flows from the cylinder lower chamber 2b to the reservoir by opening the disk valve in the oil passage of the base valve.

Thus, before the main disc 34 is opened (low piston speed range), the fixed orifice 4
A damping force is generated by the zero and the contraction side pressure control valve 43. At this time, due to the flow pressure of the oil liquid from the contraction side oil passage 14 and the initial load of the notch disk 201 and the closing disk 301 on the main disk 34 side, the main disk 3
4. The notched disk 201 and the closed disk 301 are in close contact with each other, and a stable orifice characteristic is obtained.

In the compression side pressure control valve 43, in the oil chamber 53, the pressure receiving area of the auxiliary valve member 55 is larger than the pressure receiving area of the stepped portion 72 of the slider 51. , A thrust in the valve opening direction of the sub-valve member 55 is generated. On the other hand, by urging the slider 51 in the valve closing direction of the sub-valve member 55 by the proportional solenoid 58 and adjusting the valve-opening pressure of the sub-valve member 55 in accordance with the current supplied to the coil 73, the main It is possible to directly control the damping force before the disk 34 is opened (low piston speed range) regardless of the piston speed.

By adjusting the valve opening pressure of the auxiliary valve member 55, the upstream back pressure chamber 3 is adjusted in accordance with the pressure.
9 is adjusted, and the pressure in the back pressure chamber 39 acts as a pilot pressure of the main disk 34 in the valve closing direction.
Can be similarly adjusted, and the damping force in the high piston speed range can be adjusted at the same time.

As described above, the notch disks 200 and 201 and the closing disks 300 and 301 are stacked on the upstream side of the main disks 22 and 34, so that a stable orifice characteristic can be obtained even at a low piston speed range, An appropriate damping force according to the characteristics can be obtained, and the setting range of the damping characteristics can be widened.

Even if the initial load of the closed disk is reduced to such a degree that it touches the notched disk, the disks adhere to each other due to the flow pressure of the oil liquid, so that the orifice characteristics are stable even in the extremely low piston speed range. Is obtained, and the setting range of the damping force becomes wider.

The height t1 of the valve seats 21 and 33 is determined by the thickness t2 of the notched disks 200 and 201 and the height t1 of the closed disk 30.
Since the thickness (t1 <(t2 + t3)) is set to be smaller (lower) than the sum of the thicknesses t3 of 0 and 301, the notch disk 20
Initial loads are applied to the main disks 22, 34 and the closing disks 300, 301 in such a manner as to urge the main disks 22, 34 in the valve opening direction, and the disks can be brought into close contact with each other to obtain a stable orifice characteristic. it can.

Further, since the outer peripheral sides of the main disks 22, 34 are warped toward the valve seats 21, 33, the main disk 2
The seating points of the valve seats 2 and 34 with respect to the valve seats 21 and 33 are the outer peripheral edges (line contact) of the valve seats 21 and 33, and the main disk 2
2, 34 valve opening pressure can be stabilized.

Further, since the disks having low rigidity (thin thickness) are laminated, the rigidity of the entire disk can be reduced, the inclination of the valve characteristics can be made gentle, and the pilot type damping valve itself can be formed by the friction effect between the plates. In addition, in the above embodiment, the notched disks 200 and 201 on the extension side and the contraction side can be absorbed.
However, the notch disk is not limited to this.In order to obtain a desired orifice characteristic on the extension side and the contraction side, a notch disk with a suitably changed number of notches is used if the extension side and the contraction side are different. You may use it.

Further, in the above embodiment, the notch of the notch disk is shown to extend in the radial direction and open at the outer periphery. However, the present invention is not limited to this, and as shown in FIG. 5, the notch communicates with the oil hole of the main disk. In addition, a notched disk having a notch whose outer periphery extending in the radial direction is not open may be used. In this case, the diameter of the closing disc is set so that a fixed orifice is formed in the radial cross section of the notch.

Further, in the above embodiment, the oil chamber 5
The damping force is controlled by the balance between the thrust generated in the slider 51 due to the pressure receiving area difference between the stepped portions 71 and 72 of the slider 51 and the sub-valve members 54 and 55 in the slider 51 and the thrust of the proportional solenoid 58. By reducing the pressure receiving area difference, the load on the proportional solenoid 58 can be reduced, and the size and weight can be reduced.

The slider 51 is provided with a proportional solenoid 5
8 through the coil 73, the auxiliary valve member 5
A position to open both valves 4 and 55 (soft on both the extension side and the contraction side), and a position to close one of them and open the other (soft on the extension side and hard on the contraction side, or hard on the extension side and soft on the contraction side) ), It is possible to obtain an extension-side compression-side inversion characteristic suitable for semi-active suspension control based on the so-called skyhook theory.

Further, in the above-described embodiment, the damping force adjusting type hydraulic shock absorber in which the pilot type damping valve and the like are built in the piston and the piston rod portion is shown. However, the present invention is not limited to this. Can be communicated with a bypass passage outside the cylinder, and the present invention can also be applied to a damping force-adjustable hydraulic shock absorber of a type in which a pilot damping valve or the like is provided in the bypass passage.

[0057]

As described in detail above, according to the damping force adjusting type hydraulic shock absorber of the first aspect, the damping valve is provided on the main disk provided with the oil hole and on the upstream side of the main disk, A notch disk provided with at least one notch communicating with the oil hole and extending in the radial direction; and a closing disk provided on the upstream side of the notch disk and closing an axial position facing the oil hole of the notch. The fixed orifice is composed of the disc, the closed disc, and the oil passage formed by the notch, so that the fluid pressure of the oil liquid makes each disc adhere to each other, and the area of the fixed orifice can be kept constant, and stable orifice characteristics Can be obtained.

Further, the notched disk and the closed disk are
Since the notch disk and the closed disk do not act to close the main disk because they are provided on the upstream side of the main disk, the valve opening pressure of the main disk is not increased,
As a result, the setting range of the attenuation characteristic can be expanded.

According to the damping force adjusting hydraulic shock absorber of the second aspect, in the first aspect of the invention, the initial load is applied to the closing disk so as to urge the main disk side, so that the closed disk is caused by the flow of the oil liquid. In addition to the force to bring the disks into close contact, the initial load also brings the disks into close contact, so that the area of the fixed orifice is kept constant even during the minute flow of the oil liquid (at extremely low piston speeds) to ensure stable operation. By obtaining the orifice characteristics, the setting range of the attenuation characteristics can be further expanded.

[Brief description of the drawings]

FIG. 1 is an enlarged longitudinal sectional view showing a damping force adjusting type hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view showing a piston portion in FIG.

FIG. 3 is an enlarged longitudinal sectional view showing a main part of the present invention.

FIG. 4 is a plan view showing each disk of the present invention.

FIG. 5 is an enlarged sectional view showing a modified example of each disk of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic shock absorber with damping force adjustment 2 Cylinder 3 Piston 6 Piston rod 22, 34 Main disk (damping valve) 22a, 34a Oil passage 22A, 39 Back pressure chamber (pilot chamber) 27, 40 Fixed orifice 30, 43 Pressure control valve (Regulatory valve) 200, 201 Notch disc (damping valve) 200a, 201a Notch 300, 301 Closing disc (damping valve) A main passage B sub passage

Claims (2)

[Claims] 1. A cylinder filled with an oil liquid, a piston slidably fitted in the cylinder, and a piston having one end connected to the piston and the other end extending outside the cylinder. A rod, a main passage through which the oil liquid flows by sliding of the piston rod, a damping valve provided in the main passage, a fixed orifice provided in the damping valve, and a fixed orifice provided from the main passage through the fixed orifice. A sub-passage through which the oil liquid flows by sliding of the piston rod, and an externally-adjustable adjustment valve provided in the sub-passage, wherein the fixed orifice and the adjustment valve A damping force adjusting hydraulic shock absorber for adjusting the damping force of the damping valve by changing a pressure between the main disc and an upstream side of the main disc provided with an oil hole. Provided and before A notch disk provided with at least one notch communicating with the oil hole and extending in the radial direction, and a closing disk provided upstream of the notch disk and closing a position of the notch facing the oil hole, A damping force-adjustable hydraulic shock absorber, wherein a fixed orifice is constituted by an oil passage formed by the main disk, the closing disk, and the notch. 2. The damping force-adjustable hydraulic shock absorber according to claim 1, wherein an initial load is applied to the closing disk so as to urge the main disk toward the main disk.