JP2002168281A - Damping force adjustable hydraulic shock absorber - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a damping force adjusting type hydraulic shock absorber, a backflow of an oil liquid is prevented to constantly generate a stable damping force. SOLUTION: Disk valves 24 on the extension side and the contraction side,
The back pressure chambers 30, 44 are formed at the back of 38. Proportional solenoid 53
By adjusting the control pressures of the extension side and contraction side pressure control valves 35, 49, the flow of the oil liquid between the oil passages 33, 34 and between the oil passages 47, 48 is controlled, so that the piston speed damping force in the low speed range is controlled. , The internal pressures of the back pressure chambers 30, 44 are changed to adjust the valve opening characteristics of the disc valves 24, 38, thereby adjusting the damping force in the high piston speed range. The check valves 32, 46 prevent the backflow of the oil liquid from the back pressure chambers 30, 34 to the upstream side thereof, so that a stable damping force can always be generated.

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] In general, a damping force adjusting type hydraulic shock absorber slidably fits a piston having a piston rod connected to a cylinder filled with an oil liquid so as to divide the cylinder into two chambers.
The piston section is provided with a main oil passage and a bypass passage communicating the two chambers in the cylinder, the main oil passage is provided with a damping force generating mechanism comprising an orifice and a disc valve, and the bypass passage is provided with a damping device for adjusting the passage area. It has a configuration in which a force adjusting valve is provided.

[0004] The bypass passage is opened by the damping force adjusting valve to reduce the flow resistance of the oil liquid between the two chambers in the cylinder to reduce the damping force, and the bypass passage is closed to reduce the flow between the two chambers. The damping force is increased by increasing the resistance. Thus, the damping force characteristic can be appropriately adjusted by opening and closing the damping force adjusting valve.

However, when the damping force is adjusted by the passage area of the bypass passage as described above, the damping force depends on the restriction of the orifice of the oil passage in a low-speed range of the piston speed. It can be changed, but in the middle and high speed range of piston speed,
Damping force is generated by the main oil passage damping force mechanism (disk valve, etc.)
, The damping force characteristic cannot be changed significantly.

Accordingly, the present applicant has disclosed, for example,
No. 141, a back pressure chamber (pressure chamber) is formed at the back of a disk valve, which is a damping force generating mechanism of the main passage, provided with a main passage and a sub passage through which an oil liquid flows by movement of a piston in a cylinder. In the passage, a fixed orifice and a sub passage area adjusting section (variable orifice) are provided, and a damping force for adjusting the damping force by adjusting the pressure of the back pressure chamber between the fixed orifice of the sub passage and the sub passage area adjusting section. An adjustable hydraulic shock absorber has been proposed.

According to this damping force adjusting type hydraulic shock absorber, the flow of the oil liquid in the sub passage is controlled by the sub passage area adjusting section to directly adjust the damping force, and is generated by the sub passage area adjusting section. By changing the pressure introduced into the back pressure chamber by the flow resistance, the valve opening pressure of the disc valve can be adjusted. Thereby, in addition to the damping force characteristics by the sub passage area adjusting section, the valve opening characteristics of the disc valve can be simultaneously adjusted, and the adjustment range of the damping force can be widened.

[0008]

However, the damping force-adjustable hydraulic shock absorber in which a back pressure chamber is provided at the back of the conventional disk valve has the following problems. JP-A-10-
In the structure disclosed in Japanese Patent No. 73141, since the structure allows a flow in the opposite direction to the normal flow (normal flow) of the oil liquid from the back pressure chamber provided in the sub-passage, it is damped by the reverse flow of the oil liquid. The force tends to be unstable.

The present invention has been made in view of the above point, and a damping force-adjustable hydraulic shock absorber capable of reliably preventing a backflow of an oil liquid from a pressure chamber and obtaining a stable damping force. The purpose is to provide.

[0010]

In order to solve the above-mentioned problems, the present invention provides a cylinder filled with an oil liquid, a piston slidably fitted in the cylinder, and one end of the piston. A piston rod, the other end of which is extended outside the cylinder, a main passage and a sub-passage through which the oil liquid flows by movement of the piston in the cylinder,
A pilot-type damping valve provided in the main passage; and a fixed orifice and a sub-passage area adjusting portion provided in the sub-passage, wherein a portion between the fixed orifice of the sub-passage and the sub-passage area adjusting portion is provided. A damping force-adjustable hydraulic shock absorber in which a pressure in a pressure chamber is set as a pilot pressure of the pilot-type damping valve, wherein a check valve that allows only the flow to the pressure chamber is provided upstream of the pressure chamber. It is characterized by. With such a configuration, the damping force is directly adjusted by controlling the flow of the oil liquid in the sub passage by the sub passage area adjusting section, and the pressure of the pressure chamber is changed by the flow resistance of the sub passage area adjusting section. Adjust the valve opening characteristics of the pilot damping valve. At this time, the check valve provided on the upstream side of the pressure chamber reliably prevents the backflow of the oil liquid from the pressure chamber.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIGS. 1 and 2, the damping force-adjustable hydraulic shock absorber 1 of the present embodiment has a double cylinder structure in which an outer cylinder 3 is provided outside a cylinder 2, and the cylinder 2 and the outer cylinder 3 Is formed between them.
A piston 5 is slidably fitted in the cylinder 2, and the piston 5 causes the inside of the cylinder 2 to be in a cylinder upper chamber.
2a and a cylinder lower chamber 2b. A substantially cylindrical piston bolt 6 is inserted through the piston 5 and fixed by a nut 7. A solenoid case 9 attached to one end of a piston rod 8 is screwed to the base end of the piston bolt 6, and the other end of the piston rod 8 passes through the cylinder upper chamber 2a, and is connected to the cylinder 2 and the outer cylinder 3. It is inserted through a rod guide 10 and an oil seal 11 mounted on the upper end, and extends outside the cylinder 2. Cylinder 2
A base valve 12 that partitions the lower cylinder chamber 2b and the reservoir 4 is provided at the lower end of the base valve.

The piston 5 has a divided structure in which piston members 5A and 5B are fitted. One piston member 5A has an extension-side oil passage 13 for communicating between the cylinder upper and lower chambers 2a and 2b. 14 (main passage) and an extension-side damping force generating mechanism 15 are provided, and the other piston member 5B has cylinder upper and lower chambers 2a,
The compression-side oil passages 16 and 17 (main passages) and the compression-side damping force generating mechanism 18 for communicating between the two 2b are provided.

The base valve 12 allows oil passages 19 and 20 for communication between the cylinder lower chamber 2b and the reservoir 4, and allows only the flow of oil from the reservoir 4 side of the oil passage 19 to the cylinder lower chamber 2b. A check valve 21 and a disk valve 22 that opens when the pressure of the oil liquid on the cylinder lower chamber 2b side reaches a predetermined pressure and allows the oil liquid to flow to the reservoir 4 side through the oil passage 20 are provided. ing. And an oil liquid is sealed in the cylinder 2,
The reservoir 4 is filled with an oil liquid and a gas having a predetermined pressure.

As shown in FIG. 3, the extension-side damping force generating mechanism 19 includes a seat portion formed in a cylindrical portion of the piston member 5A.
A disc valve 24 (pilot type damping valve) is seated on 23, an inner peripheral portion of a seal ring 26 is superimposed thereon via a seat ring 25, and an outer peripheral portion of the seal ring 26 is attached to a seat portion 27 of the piston member 5A. Further, on the seal ring 26, a notched disk 100 in which a fixed orifice 101 is cut out at a plurality of positions in the circumferential direction, and a ring-shaped leaf spring 28 are laminated, and the leaf spring 28 By spring force,
Disc valve 24 and seal ring 26 are seated 23, 27
Pressed against. In the cylindrical part of the piston member 5A,
An annular fixing member 29 is fitted to form a back pressure chamber 30 (pressure chamber) behind the disc valve 24, and the internal pressure of the back pressure chamber 30 urges the disc valve 24 in the valve closing direction as pilot pressure. It has become.

The back pressure chamber 30 is communicated with the extension side oil passage 13 through oil passages 31 provided at a plurality of positions in the circumferential direction of the disk valve 24 and substantially not giving resistance to the flow of the oil liquid. On the upstream side of the fixed orifice 101, there is provided a check valve 32 that allows only the flow of the oil liquid from the extension-side oil passage 13 to the back-pressure chamber 30 side. The check valve 32 is formed of a ring-shaped valve body that comes into contact with the seat ring 25, and the inner peripheral portion thereof is clamped together with the leaf spring 28 by a fixing member 29.

The back pressure chamber 30 is connected to an extension-side pressure control valve 35 (sub-passage area) provided inside the piston bolt 6 by oil passages 33 and 34 (sub-passage) provided on the side wall of the piston bolt 6. The fixing member 29 communicates with the opposite side of the fixing member 29, and further communicates with the cylinder lower chamber 2b via a check valve 36 attached to the fixing member 29. The check valve 36
Allows only the flow of the oil liquid from the oil passage 34 side to the cylinder lower chamber 2b side.

As shown in FIG. 4, the compression-side damping force generating mechanism 18 includes a seat portion formed in a cylindrical portion of the piston member 5B.
A disc valve 38 (pilot type damping valve) is seated on 37, and an inner peripheral portion of the seal ring 40 is overlapped thereon via a seat ring 39, and an outer peripheral portion of the seal ring 40 is attached to a seat portion 41 of the piston member 5A. Further, on the seal ring 40, a notched disk 102 in which a fixed orifice 103 is cut out at a plurality of positions in the circumferential direction, and a ring-shaped leaf spring 42 are laminated, and the leaf spring 42 By spring force,
Disc valve 38 and seal ring 40 are seated 37, 41
Pressed against. In the cylindrical part of the piston member 5A,
An annular fixing member 43 is fitted, and a back pressure chamber 44 (pressure chamber) is formed at the back of the disc valve 38, and the internal pressure of the back pressure chamber 44 applies the pilot pressure to the disc valve 38 in the valve closing direction. It is going to take off.

The back pressure chamber 44 is communicated with the compression side oil passage 16 via oil passages 45 provided at a plurality of positions in the circumferential direction of the disk valve 38 and substantially giving no resistance to the flow of the oil liquid. On the upstream side of the fixed orifice 103, a check valve 46 that allows only the flow of the oil liquid from the contraction side oil passage 16 side to the back pressure chamber 44 side is provided. The check valve 46 is formed of a ring-shaped valve body that comes into contact with the seat ring 39, and the inner peripheral portion thereof is clamped together with the leaf spring 42 by a fixing member 43.

The back pressure chamber 44 is provided with oil passages 47 and 48 (sub passages) provided on the side wall of the piston bolt 6, and a compression side pressure control valve 49 (sub passage area) provided inside the piston bolt 6. The fixing member 43 communicates with the opposite side of the fixing member 43, and further communicates with the cylinder upper chamber 2a via a check valve 50 attached to the fixing member 43. The check valve 50
Allows only the flow of the oil liquid from the oil passage 48 side to the cylinder upper chamber 2a side.

The extension-side and contraction-side pressure control valves 35, 49 are provided for movement resistance (return spring) caused by the pressure of the oil flowing through the sub passages of the valve bodies 51, 52 slidably fitted in the piston bolts 6. Five
4, 55) to adjust the valve opening pressure of the valve bodies 51, 52, i.e., the area of the sub-passage. Thus, the valve opening pressure of the valve bodies 51 and 52, and thus the pressure of the back pressure chamber, can be adjusted in accordance with the current supplied to the proportional solenoid 53.

Next, the operation of the embodiment constructed as described above will be described. During the extension stroke of the piston rod 8, the movement of the piston 5 pressurizes the oil liquid on the cylinder upper chamber 2a side, and before the disc valve 24 of the extension-side damping force generating mechanism 15 opens (piston speed low speed range). The lower side of the cylinder passes through the extension side oil passage 13, the oil passage 31, the check valve 32, the fixed orifice 101, the back pressure chamber 30, the oil passage 33, the extension side pressure control valve 35, the oil passage 34, and the check valve 36. It flows to the room 2b side. When the pressure on the cylinder upper chamber 2a side reaches the valve opening pressure of the disc valve 24 (high piston speed range), the disc valve 24 opens, and the oil liquid flows directly from the extension side oil passage 13 to the extension side oil passage. It flows through 14 to the cylinder lower chamber 2b. At this time, the piston rod
The amount of oil that has exited the cylinder 2 from the cylinder 2 opens the check valve 21 of the oil passage 19 of the base valve 12 from the reservoir 4 to the lower chamber of the cylinder.
Flow to 2b.

Then, by adjusting the valve opening pressure of the valve body 51 of the extension side pressure control valve 35 by the current supplied to the proportional solenoid 53, the extension side damping force can be directly controlled. At this time, the internal pressure (pilot pressure) of the upstream back pressure chamber 30 changes due to the flow resistance of the extension side pressure control valve 35, and the valve opening pressure of the disc valve 24 is adjusted. And the high-speed damping force can be adjusted simultaneously.

Also, during the contraction stroke of the piston rod 8, the movement of the piston 5 pressurizes the oil liquid in the cylinder lower chamber 2b side, so that the disk valve 38 of the contraction-side damping force generating mechanism 18 is opened before the piston valve is opened. (Low-speed range), the contraction-side oil passage 16, the oil passage 45, the fixed orifice 103, the check valve 46, the back pressure chamber 44, the oil passage 47, the contraction-side pressure control valve 49, the oil passage 48, and the check valve 50 Through the cylinder upper chamber 2a. When the pressure on the cylinder lower chamber 2b side reaches the valve opening pressure of the disc valve 38 (high piston speed range), the disc valve 38 opens, and the oil liquid flows directly from the contraction side oil passage 16 to the contraction side oil passage. It flows through 17 to the cylinder upper chamber 2a. At this time, the piston rod
The oil liquid that has entered the cylinder 2 flows into the reservoir 4 from the cylinder lower chamber 2b by opening the disk valve 22 of the oil passage 20 of the base valve 12.

By adjusting the valve-opening pressure of the valve body 52 of the compression-side pressure control valve 49 by the current supplied to the proportional solenoid 53, the compression-side damping force can be directly controlled. At this time, the internal pressure (pilot pressure) of the back pressure chamber 44 on the upstream side changes due to the flow resistance of the compression side pressure control valve 49, and the valve opening pressure of the disc valve 38 is adjusted. And the high-speed damping force can be adjusted simultaneously.

Here, at the time of shifting from the extension stroke to the contraction stroke, the check valve 32 prevents the pressure in the back pressure chamber 30 which was in a pressurized state during the extension stroke from escaping to the reduced cylinder upper chamber 2a.
Can reliably prevent the pressure in the back pressure chamber 30 from being maintained at the pressure at the time of the previous extension stroke when shifting to the next extension stroke, and can reliably generate a desired damping force. Therefore, a stable damping force can be obtained.

During the extension stroke, the pressurized oil liquid in the cylinder upper chamber 2a acts in the direction of lifting the seal ring 40 of the compression-side damping force generating mechanism 18 through the compression-side oil passage 17. In this case, since the pressure in the back pressure chamber 44 is maintained by the check valve 46, the lift of the seal ring 40 is suppressed, and the oil liquid short-circuits from the contraction side oil passage 17 to the cylinder lower chamber 2b side. And a stable damping force can be obtained.

Further, even in the transition from the contraction stroke to the extension stroke, the check valve 46 ensures that the pressure in the back pressure chamber 44 that has been in the pressurized state escapes to the reduced cylinder lower chamber 2b. To prevent the back pressure chamber from moving to the next contraction stroke.
The pressure in 44 can be maintained at the pressure at the time of the previous contraction stroke, and a desired damping force can be reliably generated, so that a stable damping force can be obtained.

Further, during the contraction stroke, the pressurized oil liquid in the cylinder lower chamber 2b side acts through the extension side oil passage 14 to lift the seal ring 26 of the extension side damping force generating mechanism 15. In this case, since the pressure in the back pressure chamber 30 is maintained by the check valve 32, the lift of the seal ring 26 is suppressed, and the oil liquid short-circuits from the extension oil passage 14 to the cylinder upper chamber 2a. And a stable damping force can be obtained.

In the above-described contraction stroke, the pressurized oil liquid in the cylinder lower chamber 2b passes through the expansion-side oil passage 14 and lifts the seal ring 26 of the expansion-side damping force generating mechanism 15 to lift the back pressure chamber. Even when the oil flows into the cylinder 30, the oil passage 31 is securely closed by the check valve 32, so that the oil liquid does not short-circuit from the back pressure chamber 30 to the cylinder upper chamber 2a side, and a stable damping force is generated. be able to.

In this manner, the check valves 32 and 46
By preventing the flow of the oil liquid from the back pressure chambers 30 and 44 to the upstream side thereof, it is possible to reliably prevent the backflow of the oil liquid,
A stable damping force characteristic can always be obtained.

In the above embodiment, the piston is provided with the main passage, the sub passage, the pilot damping valve, the fixed orifice, the check valve, the pressure chamber, and the sub passage area adjusting portion. Not limited to this, these elements may be provided on a bypass passage that bypasses the upper and lower chambers of the piston outside the cylinder.

[0032]

As described above in detail, according to the damping force adjusting type hydraulic shock absorber of the present invention, since the check valve for preventing the flow of the oil liquid from the pressure chamber to the upstream side thereof is provided, The backflow of the liquid can be reliably prevented, and a stable damping force can always be generated.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a main part of the damping force adjustable hydraulic shock absorber of FIG.

FIG. 3 is an enlarged view of an extension side damping force generating mechanism of the damping force adjusting type hydraulic shock absorber of FIG. 1;

FIG. 4 is an enlarged view of a contraction-side damping force generating mechanism of the damping force adjusting hydraulic shock absorber of FIG. 1;

[Explanation of symbols]

 1 Hydraulic shock absorber with damping force adjustment 2 Cylinder 5 Piston 8 Piston rod 13, 14 Extension oil path (main passage) 17, 18 Retraction oil path (main passage) 24, 38 Disc valve (pilot type damping valve) 101, 103 Fixed Orifice 30,44 Back pressure chamber (pressure chamber) 32,46 Check valve 33,34,47,48 Oil passage (sub-passage) 35 Expansion side pressure control valve (sub-passage area adjustment section) 49 Retraction side pressure control valve ( (Auxiliary passage area adjustment unit)

Claims (1)

[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 and a sub-passage through which oil fluid flows by movement of a piston in the cylinder, a pilot damping valve provided in the main passage, and a fixed orifice and sub-passage area adjustment provided in the sub-passage A damping force-adjustable hydraulic shock absorber comprising a pressure of a pressure chamber between the fixed orifice of the sub-passage and the sub-passage area adjusting portion as a pilot pressure of the pilot-type damping valve. A damping force-adjustable hydraulic shock absorber, wherein a check valve is provided upstream of the pressure chamber to allow only the flow to the pressure chamber.