JP4356016B2 - Hydraulic shock absorber - Google Patents

Description

  The present invention relates to a hydraulic shock absorber mounted on a suspension device of a vehicle such as an automobile, and more particularly to a hydraulic shock absorber having a pilot chamber for controlling a valve opening pressure of a main valve that generates a damping force.

  In general, a cylindrical hydraulic shock absorber mounted on a suspension device of a vehicle such as an automobile is slidably fitted with a piston connected to a piston rod in a cylinder in which oil is sealed, and a piston portion Is provided with a damping force generating mechanism including an oil liquid passage, an orifice, a disk valve, and the like. Thereby, the flow of the oil liquid generated in the oil liquid oil passage by the sliding of the piston in the cylinder accompanying the stroke of the piston rod is controlled by the orifice and the disk valve to generate the damping force. In the low speed region of the piston speed, an orifice characteristic damping force is generated by the orifice, and in the high piston speed region, the disk valve is bent and opened to generate the valve characteristic damping force. ing.

  However, in the conventional hydraulic shock absorber, the damping force in the low speed region of the piston speed depends on the flow area of the orifice, and the damping force in the high speed region depends on the valve opening pressure set in advance. Therefore, if the damping force characteristics are set with a low degree of freedom and a small damping force is obtained in the low speed region of the piston speed, the damping force in the high speed region is insufficient, and a large damping force is obtained in the high speed region. Then, there is a problem that the damping force in the low speed region becomes excessive.

Therefore, for example, as disclosed in Patent Document 1, a pilot chamber is provided on the back side of the disk valve, a part of the oil is introduced into the pilot chamber, and the pressure in the pilot chamber acts on the disk valve in the valve closing direction. Thus, there has been proposed a hydraulic shock absorber that increases the degree of freedom in setting the damping force characteristic by controlling the valve opening pressure of the disk valve.
JP 2003-278819 A

  In the hydraulic shock absorber described in Patent Document 1, the pilot chamber is sealed by directly contacting an elastic seal member fixed to the pilot chamber side on the back side of the disk valve. In addition, it is conceivable to seal the pilot chamber by liquid-tightly slidingly fitting a seal member fixed to the disk valve side to the pilot chamber side. Since it is large and tends to become unstable, the opening / closing pressure and lift amount of the disk valve are unstable, and it is difficult to obtain a stable damping force.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a hydraulic shock absorber capable of ensuring the sealing performance of the pilot chamber and obtaining a stable damping force.

In order to solve the above-described problems, the present invention provides a cylinder in which oil is sealed, a piston slidably fitted in the cylinder, one end connected to the piston, and the other end of the cylinder. A piston rod extended to the outside, a main valve that generates a damping force by controlling the flow of oil produced by sliding of the piston, and a pilot chamber that applies pressure in the valve closing direction of the main valve. A hydraulic shock absorber for introducing a part of the flow of the oil liquid into the pilot chamber and controlling the opening of the main valve by the pressure of the pilot chamber;
An annular seal member is fixedly provided on the outer peripheral portion of the back side of the main valve, and the seal member is slidably and liquid-tightly fitted into a cylindrical pilot case to form the pilot chamber, The valve is a valve that is clamped on the inner peripheral side and opened on the outer peripheral side, and the outer peripheral portion of the seal member forms a tapered lip portion having a large diameter from the main valve side toward the pilot case side. To do.

According to the hydraulic shock absorber according to the present invention, the flow of the oil liquid caused by the stroke of the piston rod is controlled by the main valve to generate a damping force, and the opening of the main valve is controlled by the pressure in the pilot chamber, thereby damping. The degree of freedom in setting the force characteristics can be increased. The seal member having a tapered lip portion fixed to the outer peripheral portion on the back side of the main valve can secure the sealing performance of the pilot chamber and can reduce the sliding resistance of the seal member to obtain a stable damping force. .

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 3, the hydraulic shock absorber 1 according to the present embodiment has a double cylinder structure in which an outer cylinder 3 is provided on the outer periphery of a cylinder 2 in which oil is sealed. 3, an annular oil passage 4 is formed. A gas chamber unit 5 is connected to the lower end of the cylinder 2, and the oil liquid in the cylinder 2 is constantly pressurized by the high pressure gas sealed in the gas chamber 6 via the free piston 7. . A damping force generating mechanism 8 is attached to a side portion of a hydraulic shock absorber main body including the cylinder 2, the outer cylinder 3, and the gas chamber unit 5.

  A piston 9 is slidably fitted in the cylinder 2, and the inside of the cylinder 2 is defined by the piston 9 as two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. One end of a piston rod 10 is connected to the piston 9 by a nut 11, and the other end of the piston rod 10 is connected to a rod guide 12 and an oil seal 13 mounted on the upper ends of the cylinder 2 and the outer cylinder 3. It is inserted and extended to the outside of the cylinder 2.

  The piston 9 is provided with an extension side oil passage 14 and a contraction side oil passage 15 that communicate between the cylinder upper and lower chambers 2A, 2B. The extension side oil passage 14 is provided with a normally closed relief valve 16 (disc valve) that opens when the pressure in the cylinder upper chamber 2A reaches a predetermined pressure and relieves the pressure to the cylinder lower chamber 2B. The contraction-side oil passage 15 is provided with a normally closed relief valve 17 (disc valve) that opens when the pressure in the cylinder lower chamber 2A reaches a predetermined pressure and relieves the pressure to the cylinder upper chamber 2A. It has been.

  In the damping force generating mechanism 8, a valve member 19 is fitted and fixed in a bottomed cylindrical case 18, and the inside of the case 18 is defined by the valve member 19 into two chambers, an upper chamber 18A and a lower chamber 18B. ing. The upper chamber 18A communicates with the cylinder upper chamber 2A via an oil passage 20 provided on the side wall of the case 18, the annular oil passage 4, and an oil passage 21 provided on the upper end side wall of the cylinder 2. The lower chamber 18B is communicated with the cylinder lower chamber 2B via an oil passage 22 provided on the side wall of the case 18. The valve member 19 is provided with an extension side oil passage 23 and a contraction side oil passage 24 for communicating the upper chamber 18A and the lower chamber 18B. The extension side oil passage 23 includes an extension side damping force generation mechanism. 25 is provided, and a compression side damping force generation mechanism 26 is provided in the compression side oil passage 24.

Since the expansion side damping force generation mechanism 25 and the compression side damping force generation mechanism 26 have the same structure, the expansion side damping force generation mechanism 25 will be described below with reference to FIG. Detailed description of the generating mechanism 26 is omitted.
As shown in FIG. 1, the extension-side damping force generation mechanism 25 receives a pressure of the oil liquid from the extension-side oil passage 23 to open and generate a damping force, and a main valve 27 (disc valve). And a pilot chamber 28 for operating the pressure in the valve closing direction of the main valve 27. The pilot chamber 28 communicates with the upstream side oil passage 23 via the orifice oil passage 29 and the port 31, and the notch 30 a of the spool valve 30 (flow control valve) is connected to the ports 31 and 32. The pilot chamber 28 is communicated with the lower chamber 18 </ b> B on the downstream side through the check valve 33.

  Then, by moving the spool valve 30 by the solenoid actuator 34 (see FIG. 3) and changing the flow passage area between the ports 31 and 32, the flow passage area between the upper and lower chambers 18A and 18B is directly adjusted. Thus, the pressure in the pilot chamber 28 is adjusted to control the valve opening pressure of the main valve 27.

  The contraction-side damping force generation mechanism 26, like the above-described extension-side damping force generation mechanism 25, changes the flow passage area between the ports 35 and 36 by changing the notch 30a of the spool valve 30, thereby providing the upper and lower chambers 18A, In addition to directly adjusting the flow path area between 18B, the pressure of the pilot chamber 37 is adjusted by this, and the valve opening pressure of the main valve 38 that opens under the pressure of the contraction side oil passage 24 is controlled. ing.

Next, the seal structure of the pilot chamber 28 will be described with reference to FIGS.
As shown in FIG. 1, the pilot chamber 28 includes a substantially bottomed cylindrical pilot case 39 disposed adjacent to the valve member 19, and a flexible seal disk 40 stacked on the back side of the main valve 27. Is formed by. An annular seal member 41 is fixed to the outer peripheral portion on the back side of the seal disk 40. The seal disc 40 is slidably and fluid-tightly fitted to the inner peripheral surface of the cylindrical portion 39A of the pilot case 39. The seal disc 40 has an inner peripheral portion at the bottom of the pilot case 39. Between the inner cylindrical portion 39B protruding in the center and the valve member 19, it is clamped together with the main valve 27, and the outer peripheral side can be moved together with the seal member 41 by bending, thereby sealing the pilot chamber 28.

  The seal member 41 can be made of rubber having viscoelasticity such as fluoro rubber, synthetic resin, or the like, and is fixed to the seal disk 40 by adhesion or baking. As shown in FIGS. 2 and 4, a tapered lip portion 42 is formed on the outer peripheral portion of the seal member 41, and a plurality of annular protrusions 43 are parallel to the lip portion 42 along the circumferential direction. Is formed. In the example shown in FIGS. 2 and 4, the annular protrusions 43 have a circular cross section with a radius R, are arranged at four intervals L (equal intervals), and protrude by a height H. A reverse tapered surface 44 is formed at one end of the seal member 41 in consideration of the ease of assembly with the pilot case 39. In the present embodiment, as an example, the diameter d = 23.2 mm of the end on the small diameter side of the lip portion 42 and the diameter D = 24.7 mm of the end on the large diameter side (the tip of the annular protrusion 43) are 24.7 mm. The cross-sectional radius R is 0.2 mm, the height H is 0.07 mm, and the interval L is 0.4 mm.

Next, the operation of the present embodiment configured as described above will be described.
During the extension stroke of the piston rod 10, as the piston 9 in the cylinder 2 slides, the oil liquid on the cylinder upper chamber 2 </ b> A side passes through the oil passage 21, the annular oil passage 4, and the oil passage 20, and the damping force generation mechanism 8. Flows to the upper chamber 18A, flows from the upper chamber 18A to the lower chamber 18B through the extension side oil passage 23, etc., and further flows from the lower chamber 18A to the cylinder lower chamber 2B through the oil passage 22 to generate the extension side damping force. A damping force is generated by the mechanism 25. At this time, the high-pressure gas in the gas chamber 6 is expanded by the amount that the piston rod 10 has left the cylinder 2 to compensate for the volume change in the cylinder 2.

  In the extension side damping force generation mechanism 25, in the low speed region of the piston speed, a damping force having an orifice characteristic is generated by the flow path area between the ports 31, 32 adjusted by the orifice oil passage 29 and the spool valve 30, and the piston When the speed increases, the main valve 27 is opened and a damping force having a valve characteristic is generated. Then, the solenoid valve 34 is moved by the solenoid actuator 34 and the flow path area between the ports 31 and 32 is adjusted, thereby adjusting the orifice characteristic and adjusting the pressure in the pilot chamber 28 to adjust the valve characteristic. Can do. When the pressure in the cylinder upper chamber 2A reaches a predetermined pressure, the relief valve 16 of the piston 9 opens, and the pressure in the cylinder upper chamber 2A is relieved to the cylinder lower chamber 2B to prevent an excessive increase in damping force. To do.

  During the contraction stroke of the piston rod 10, as the piston 9 in the cylinder 2 slides, the oil liquid on the cylinder lower chamber 2 </ b> B side flows through the oil passage 22 to the lower chamber 18 </ b> B of the damping force generation mechanism 8. From the upper chamber 18A to the upper chamber 18A through the compression side oil passage 24 and the like, and further flows from the upper chamber 18A through the oil passage 20, the annular oil passage 4 and the oil passage 21 to the cylinder upper chamber 2A to generate a compression side damping force. A damping force is generated by the mechanism 26. At this time, the high pressure gas in the gas chamber 6 is compressed as much as the piston rod 10 enters the cylinder 2 to compensate for the volume change in the cylinder 2.

  In the compression-side damping force generating mechanism 26, in the low piston speed range, the orifice characteristic damping force is reduced by the orifice oil passage (not shown) and the flow passage area between the ports 35 and 36 adjusted by the spool valve 30. When this occurs and the piston speed increases, the main valve 38 opens and a damping characteristic of the valve characteristic is generated. Then, the solenoid valve 34 is moved by the solenoid actuator 34 and the flow path area between the ports 35 and 36 is adjusted to adjust the orifice characteristic and the pressure in the pilot chamber 37 to adjust the valve characteristic. Can do. When the pressure in the cylinder lower chamber 2B reaches a predetermined pressure, the relief valve 17 of the piston 9 opens, and the pressure in the cylinder lower chamber 2B is relieved to the cylinder upper chamber 2A to prevent an excessive increase in damping force. To do.

  The seal member 41 that seals the pilot chamber 28 can form a multistage seal with the inner peripheral surface of the cylindrical portion 39A of the pilot case 39 by forming a plurality of annular protrusions 43 on the lip portion 42 thereof. It is possible to securely seal between them, and to reduce and stabilize the sliding resistance between them. As a result, leakage of the pilot chamber 28 can be prevented, the main valve 27 can be opened smoothly, and a stable damping force can be obtained. Further, when the seal disk 40 is assembled to the pilot case 39, the sliding resistance is reduced by the reverse tapered surface 44, so that the assembling workability is improved and the seal member 41 is hardly damaged and the manufacturing quality is improved. be able to.

  Next, a modification of the seal member 41 of the above embodiment will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the same part with respect to the sealing member 41 shown in FIG. 2, and only a different part is demonstrated in detail.

  In the first modification shown in FIG. 5, a plurality of annular grooves 45 are formed in the lip portion 42 of the seal member 41 instead of the annular protrusions 43. Thereby, a multistage seal can be formed between the pilot case 39 and the cylindrical portion 39A, and the same operations and effects as those in FIG. 2 can be achieved.

  In the second modification shown in FIG. 6, the lip portion 42 of the seal member 41 has a two-stage structure of a first lip portion 46 and a second lip portion 47, and the first lip portion 46 and the second lip portion 47. An annular protrusion 43 is formed on both of them. In the third modified example shown in FIG. 7, the lip portion 42 of the seal member 41 has a two-stage structure of a first lip portion 46 and a second lip portion 47 as in the second modified example. The annular protrusion 43 having a circular cross-sectional shape is formed only on the first lip portion 46. As described above, a plurality of lip portions can be formed on the lip portion 42, and the annular protrusions 43 can be formed on all or a part of these lip portions. Further, in the second and third modifications, an annular groove 45 may be formed instead of the annular protrusion 43.

  In the above embodiment, the damping force generating mechanism is described on the side of the hydraulic shock absorber body. However, the present invention is not limited to this, and the damping force generating mechanism is disposed on the piston portion. It can be similarly applied to.

It is a longitudinal cross-sectional view which expands and shows the expansion side damping force generation mechanism of the hydraulic shock absorber which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the seal disc and seal member which seal the pilot chamber of the damping force generation mechanism shown in FIG. It is a longitudinal cross-sectional view of the whole hydraulic shock absorber which has the elongation side damping force generation mechanism shown in FIG. It is a figure which expands and shows the outer peripheral part of the sealing member shown in FIG. It is a longitudinal cross-sectional view which shows the 1st modification of a sealing member. It is a longitudinal cross-sectional view which shows the 2nd modification of a sealing member. It is a longitudinal cross-sectional view which shows the 3rd modification of a sealing member.

Explanation of symbols

1 Hydraulic shock absorber, 2 cylinder, 9 piston, 10 piston rod, 27, 38 main valve, 28, 37 pilot chamber, 41 sealing member, 43 annular protrusion, 45 annular groove

Claims (3)

A cylinder filled with oil, a piston slidably fitted in the cylinder, a piston rod having one end connected to the piston and the other end extending outside the cylinder, A main valve that generates a damping force by controlling a flow of oil liquid generated by sliding; and a pilot chamber that applies pressure in a valve closing direction of the main valve, and a part of the flow of oil liquid is the pilot In a hydraulic shock absorber that is introduced into a chamber and controls the opening of the main valve by the pressure of the pilot chamber,
An annular seal member is fixedly provided on the outer peripheral portion of the back side of the main valve, and the seal member is slidably and liquid-tightly fitted into a cylindrical pilot case to form the pilot chamber, The valve is a valve that is clamped on the inner peripheral side and opened on the outer peripheral side, and the outer peripheral portion of the seal member forms a tapered lip portion having a large diameter from the main valve side toward the pilot case side. Hydraulic shock absorber. The hydraulic shock absorber according to claim 1, wherein a plurality of annular protrusions or annular grooves are formed in the lip portion. 3. The hydraulic shock absorber according to claim 1, wherein a reverse tapered surface is formed at an end of the lip portion on the large diameter side. 4.

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