JP4453000B2 - Hydraulic shock absorber - Google Patents

Description

  The present invention relates to a hydraulic shock absorber attached to a suspension device of a vehicle such as an automobile, and more particularly to a hydraulic shock absorber having a high degree of freedom in setting damping force characteristics and excellent in response.

  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 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, a damping force is generated by the orifice, and in the high speed region of the piston speed, the disk valve is bent and opened to prevent an excessive increase in the damping force. .

  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 shown in Patent Document 1, a back pressure chamber is provided on the back side of the disk valve, and a part of the oil is introduced into the back pressure chamber via the sub disk valve, so that the internal pressure of the back pressure chamber is reduced. By acting on the disk valve in the valve closing direction, the internal pressure of the back pressure chamber is adjusted by the sub disk valve, and the valve opening pressure of the disk valve is controlled to increase the degree of freedom in setting the damping force characteristics. A hydraulic shock absorber has been proposed.
JP-A-2-278026

  However, the one described in Patent Document 1 has the following problems. The passage for introducing the oil into the back pressure chamber has a long passage length due to the arrangement of the sub-disc valve, which increases the flow resistance, and the response to the increase in the internal pressure of the back pressure chamber. As a result, it is difficult to quickly obtain an appropriate 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 having a high degree of freedom in setting damping force characteristics and excellent in responsiveness.

In order to solve the above-mentioned problems, the invention according to claim 1 includes a cylinder in which oil is sealed, a piston slidably fitted in the cylinder, and one end connected to the piston. A piston rod whose end extends to the outside of the cylinder, a main disk valve that generates a damping force by controlling the flow of oil produced by sliding of the piston, and an internal pressure in the valve closing direction of the main disk valve A hydraulic buffer that controls a valve opening of the main disk valve by introducing a part of the oil into the back pressure chamber.
A pilot oil passage for introducing oil into the back pressure chamber is drilled in the main disc valve, and a sub valve for directly opening and closing the pilot oil passage is provided on the back side of the main disc valve ,
When the piston speed is low, the main disk valve and the sub-valve open the main disk valve with the pilot oil passage closed by the sub-valve, and the sub-valve increases as the piston speed increases. It is the structure which introduce | transduces an oil liquid into the said back pressure chamber through the said opening pilot oil path .
A hydraulic shock absorber according to a second aspect of the present invention is characterized in that, in the configuration of the first aspect, the main disc valve and the sub valve are valves that open and close without causing the valve body to bend.
The hydraulic shock absorber according to a third aspect of the present invention is the hydraulic shock absorber according to the first or second aspect, wherein the main disc valve and the sub valve are separated from each other by a seat portion provided so as to protrude from either one of them. The pilot oil passage is opened and closed by being seated.

According to the hydraulic shock absorber of the first aspect of the invention, when the sub valve in the low piston speed region is closed, no oil is introduced into the back pressure chamber and the internal pressure of the back pressure chamber does not increase. When the sub-valve is opened due to an increase in piston speed due to lower valve opening pressure, oil is introduced into the back pressure chamber through the pilot passage, and the internal pressure in the back pressure chamber rises. As the valve opening pressure rises, the damping force increases. By drilling a pilot passage in the main disc valve and providing a sub-valve that directly opens and closes the pilot passage on the back side of the main disc valve, the passage length of the pilot passage communicating with the back pressure chamber can be sufficiently shortened, Responsiveness of the increase in the internal pressure of the back pressure chamber can be enhanced.
According to the hydraulic shock absorber according to the second aspect of the present invention, the damping force can be generated without depending on the deflection of the valve body of the main disc valve and the sub-valve. Therefore, the damping force is increased by the increase of the deflection of the valve body. An excessive rise can be prevented.
According to the hydraulic shock absorber pertaining to the third aspect of the invention, the sticking between the main disc valve and the sub valve can be prevented by the protruding seat portion, and the sub valve can be smoothly opened.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, a hydraulic shock absorber 1 according to the present embodiment is a cylindrical hydraulic shock absorber mounted on a suspension device of a vehicle such as an automobile, and includes a cylinder 2 ( The piston 3 is slidably fitted in a part of the side wall (illustrated in a part of the side wall), and the cylinder 3 is defined by the piston 3 as two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. One end of a piston rod 4 is connected to the piston 3 by a nut 5, and the other end side of the piston rod 4 is a rod guide (not shown) attached to the upper ends of the cylinder 2 and the outer cylinder 3 and oil. It is inserted through a seal (not shown) and extended to the outside. The cylinder lower chamber 2B is connected to a reservoir (not shown) via a base valve (not shown) having an appropriate flow resistance, and oil and gas are sealed in the reservoir.

  The piston 3 is provided with an expansion side oil passage 6 and a contraction side oil passage 7 for communicating between the cylinder upper and lower chambers 2A, 2B. The end of the piston 3 on the cylinder lower chamber 2B side is provided with an extension-side damping force generation mechanism 8 that generates a damping force by controlling the flow of the oil liquid in the extension-side oil passage 6, and on the cylinder upper chamber 2A side. A compression-side damping force generation mechanism 9 that generates a damping force by controlling the fluid flow of the compression-side oil passage 7 is provided at the end.

The extension side damping force generation mechanism 8 will be described.
A substantially bottomed cylindrical valve member 10 is attached to the end of the piston 3 on the cylinder lower chamber 2B side. The valve member 10 has a cylindrical guide portion 11 erected on the inner side of the bottom portion thereof in contact with the piston 3. The piston rod 4 is inserted into the guide portion 11 and is fixed to the piston 3 by a nut 5. Yes. On the end surface of the piston 3 on the cylinder lower chamber 2B side, annular seat portions 12 and 13 are projected on the inner peripheral side and the outer peripheral side, respectively, and the extension-side oil passage 6 is opened between the seat portions 12 and 13. Has been. A main disc valve 14 is seated on the seat portions 12 and 13.

  The inner periphery of the main disc valve 14 is guided by the guide portion 11 of the valve member 10 so as to be movable in the axial direction, and can be seated on and off the seat portions 12 and 13 without causing bending. Further, a substantially cylindrical sealing member 15 is baked on the outer peripheral portion on the back surface side of the main disk valve 14, and the sealing member 15 comes into air-tight sliding contact with the inner peripheral surface of the cylindrical portion of the valve member 10. A back pressure chamber 16 is formed inside 10 so that the internal pressure of the back pressure chamber 16 acts in the valve closing direction of the main disk valve 14. The seal member 15 may be provided with a core material (not shown) integrated with the main disk valve 14 to ensure the necessary rigidity. When the main disk valve 14 is lifted from the seat portions 12 and 13 under the pressure of the extension side oil passage 6, the extension side oil passage 6 communicates directly with the cylinder lower chamber 2B.

  The main disk valve 14 is provided with a pilot passage 17 that allows the extension side oil passage 6 and the back pressure chamber 16 to communicate with each other. On the back side of the main disc valve 14, a sub disc valve 18 (sub valve) for directly opening and closing the pilot passage 17 is overlaid. The sub-disc valve 18 is guided by the guide portion 11 of the valve member 10 so as to be movable along the axial direction, and the sub-disc valve 18 is seated on the rear surface of the main disc valve 14 without bending, thereby being pilot-passaged. 17 is opened and closed. A substantially cylindrical sealing member 19 is baked on the inner peripheral portion on the back side of the sub-disc valve 18, and the sealing member 19 seals the back pressure chamber 16 in airtight contact with the cylindrical portion 11. . The sealing member 19 may be provided with a core material (not shown) integral with the sub disk valve 14 to ensure the necessary rigidity. The main disc valve 14 and the sub disc valve 18 are respectively urged to the valve closing position by coil springs 20 and 21 provided in the back pressure chamber 16, and the initial valve opening pressure of the sub disc valve 18 is the main disc. It is set higher than the initial valve opening pressure of the valve 14.

  An oil passage 22 is provided at the bottom of the valve member 10 to allow the back pressure chamber 18 to communicate with the cylinder lower chamber 2B. In the oil passage 22, oil in the back pressure chamber 16 that has reached a predetermined pressure is supplied to the cylinder lower chamber. A normally closed disk valve 23 (relief valve) that relieves to 2B is provided, and an orifice 24 (notch) that always connects the back pressure chamber 16 to the cylinder lower chamber 2B is provided on the outer periphery of the disk bubble 23. .

Next, the contraction side damping force generation mechanism 9 will be described.
Similar to the extension side damping force generation mechanism 8, the valve member 25 is attached to the end of the piston 3 on the cylinder upper chamber 2 </ b> A side, and the guide portion 26 of the valve member 25 is in contact with the piston 3. A contraction-side oil passage 7 is opened between the seat portions 27 and 28 protruding from the end portion of the piston 3 on the cylinder upper chamber 2A side. A main disc valve 29 guided by the guide portion 26 is seated on the seat portions 27, 28, and the seal member 30 baked on the main disc valve 29 slides on the inner peripheral surface of the cylindrical portion of the valve member 25 in an airtight manner. In contact therewith, a back pressure chamber 31 is formed on the back side of the main disc valve 29 inside the valve member 25.

  The main disc valve 29 is provided with a pilot passage 32 that allows the contraction-side oil passage 7 and the back pressure chamber 31 to communicate with each other, and a sub disc valve 33 (directly opening and closing the pilot passage 32 on the back side of the main disc valve 29). Subvalves) are stacked. A seal member 34 baked on the sub disk valve 33 is in sliding contact with the guide portion 26 to seal the back pressure chamber 31. The main disc valve 29 and the sub disc valve 33 are urged to the valve closing positions by the coil springs 35 and 36 provided in the back pressure chamber 31, respectively. It is set higher than the initial valve opening pressure of the valve 29.

  An oil passage 37 that allows the back pressure chamber 31 to communicate with the cylinder upper chamber 2A is provided at the bottom of the valve member 26. The oil passage 37 allows the oil in the back pressure chamber 31 that has reached a predetermined pressure to flow into the cylinder upper chamber. A normally closed disk valve 38 (relief valve) that relieves to 2A is provided, and an orifice 39 (notch) that always connects the back pressure chamber 31 to the cylinder upper chamber 2A is provided on the outer periphery of the disk bubble 38. .

Next, the operation of the present embodiment configured as described above will be described.
During the extension stroke of the piston rod 4, as the piston 3 slides in the cylinder 2, the oil in the cylinder upper chamber 2 </ b> A flows to the cylinder lower chamber 2 </ b> B through the extension side oil passage 6 of the piston 3, and the extension side A damping force is generated by the damping force generation mechanism 8. At this time, the oil liquid corresponding to the withdrawal of the piston rod 4 from the cylinder 2 flows from the reservoir to the cylinder lower chamber 2B through the base valve, and the gas in the reservoir 4 expands to compensate for the volume change in the cylinder 2. To do.

  In the extension side damping force generation mechanism 8, the main disc valve 14 is opened by receiving the pressure of the oil in the extension side oil passage 6, and a damping force is generated according to the opening degree. At this time, since the pilot passage 17 is closed by the sub disk valve 18 in the low speed region of the piston speed, the internal pressure of the back pressure chamber 16 does not increase, so that the valve opening pressure of the main disk valve 14 becomes low and small. Damping force is generated. Thereby, by setting the spring force of the coil spring 20 sufficiently small, the initial valve opening pressure of the main disk valve 14 can be reduced, and in the extremely low speed region of the piston speed (the initial stroke region of the piston rod 4), A sufficiently small damping force can be generated.

  When the piston speed increases and the pressure on the extension side oil passage 6 increases, the sub-disc valve 18 opens, and the pressure on the extension side oil passage 6 side is introduced into the back pressure chamber 16 through the pilot passage 17 so that the back pressure is increased. The internal pressure of the chamber 16 increases. As a result, as the piston speed increases, the valve opening pressure of the main disk valve 14 increases and the damping force increases. When the pressure in the back pressure chamber 16 reaches a predetermined pressure, the disc valve 23 opens to relieve the pressure in the back pressure chamber 16 to the cylinder lower chamber 2B side, that is, the valve opening pressure of the main disc valve 14, that is, Prevent excessive increase in damping force on the stretch side.

  During the contraction stroke of the piston rod 4 described later, the pressure on the cylinder lower chamber 2B side is introduced into the back pressure chamber 16 via the orifice 24, and the main disk valve 14 and the sub disk valve 18 are closed by the pressure. Maintained.

  During the contraction stroke of the piston rod 4, as the piston 3 slides in the cylinder 2, the oil in the cylinder lower chamber 2 </ b> B flows into the cylinder upper chamber 2 </ b> A through the contraction-side oil passage 7 of the piston 3. A damping force is generated by the generation mechanism 9, and at this time, the oil liquid that has entered the cylinder 2 through the piston rod 4 flows into the reservoir via the base valve, and compresses the gas in the reservoir 2. Compensates for volume changes.

  In the compression side damping force generation mechanism 9, as in the case of the expansion side damping force generation mechanism 8, the main disc valve 29 opens upon receiving the pressure of the oil in the compression side oil passage 7, and according to the opening degree. To generate damping force. At this time, since the pilot passage 32 is closed by the sub-disc valve 33 in the low speed region of the piston speed, the internal pressure of the back pressure chamber 31 does not rise, so the valve opening pressure of the main disc valve 29 becomes low and small. Damping force is generated. Thereby, by setting the spring force of the coil spring 35 sufficiently small, the initial valve opening pressure of the main disk valve 29 can be reduced, and in the extremely low speed range of the piston speed (the initial stroke range of the piston rod 4), A sufficiently small damping force can be generated.

  When the piston speed increases and the pressure on the contraction side oil passage 7 increases, the sub-disc valve 33 opens, and the pressure on the contraction side oil passage 7 side is introduced into the back pressure chamber 31 through the pilot passage 32, and the back pressure is increased. The internal pressure of the chamber 31 increases. As a result, as the piston speed increases, the valve opening pressure of the main disk valve 29 increases and the damping force increases. When the pressure in the back pressure chamber 31 reaches a predetermined pressure, the disc valve 38 opens to relieve the pressure in the back pressure chamber 31 to the cylinder upper chamber 2A side, that is, the valve opening pressure of the main disc valve 29, that is, Prevent excessive increase in damping force on the stretch side.

  During the extension stroke of the piston rod 4, the pressure on the cylinder upper chamber 2A side is introduced into the back pressure chamber 30 via the orifice 39, and the main disc valve 29 is maintained in the closed state by the pressure.

  Accordingly, by appropriately setting the characteristics of the main disc valves 14 and 29, the pilot passages 17 and 32, the sub disc valves 18 and 33, the back pressure chambers 16 and 31, and the disc valves 23 and 38, each piston speed range is set. Therefore, an appropriate damping force can be generated and ideal damping force characteristics can be obtained.

  The pilot passages 17 and 32 are formed in the main disc valves 14 and 29, and the pilot passages 17 and 32 are directly opened and closed by the sub disc valves 18 and 33 that are directly overlapped with the main disc valves 14 and 29. The passage lengths of the pilot passages 17 and 32 communicating with the chambers 16 and 31 can be sufficiently shortened, and the response of the increase in the internal pressure of the back pressure chambers 16 and 31 can be improved, and an appropriate damping force can be obtained quickly. it can. Further, compared with the conventional example described in Patent Document 1, the structure is simple, the number of parts is small, and the manufacturing cost is not required.

  Next, second to fourth embodiments of the present invention will be described with reference to FIGS. In addition, with respect to the said 1st Embodiment, the same code | symbol is attached | subjected to the same part, and only a different part is illustrated and demonstrated in detail. Further, since the extension side damping force generation mechanism 8 and the contraction side damping force generation mechanism 9 have substantially the same structure, only the extension side damping force generation mechanism 8 will be described.

  In the second embodiment of the present invention, as shown in FIG. 3, a seat portion 18 </ b> A that projects from and closes to the main disc valve 14 to open and close the pilot passage 17 protrudes from the sub disc valve 18. Thereby, the sub disk valve 18 and the main disk valve 14 can be prevented from sticking, and the sub disk valve 18 can be opened smoothly. Further, the pressure receiving area of the sub disk valve 18 can be adjusted by the shape and arrangement of the seat portion 18A. Note that the seal member 19 of the sub disk valve 18 is omitted.

  In the third embodiment of the present invention, as shown in FIG. 4, a ring-shaped retainer 40 is interposed between the guide portion 11 of the valve member 10 and the seat portion 13 of the piston 3. The circumference is guided by the retainer 40. The sub disk valve 18 has an inner peripheral portion clamped by a retainer 40, and a seat portion 18 A protruding from the outer peripheral part contacts the main disk valve 14, and a set load is applied to the main disk valve 14 by its spring force. Further, the main disc valve 14 is pressed in the valve closing direction. Thereby, the coil springs 20 and 21 of the first embodiment can be omitted, and the sub-disk valve 18 is prevented from sticking to the main disk valve 14 by the seat portion 18A. The valve can be opened smoothly.

  In the third embodiment, the seat portion 18A is formed by protruding the sub disk valve 18; however, instead of this, the main disk valve 14 may be protruded to form a seat portion. An effect | action and an effect can be show | played.

  In the fourth embodiment of the present invention, as shown in FIG. 5, a cylindrical portion 41 is extended from the outer peripheral portion of the piston 3, and the disc-shaped valve member 10 is attached to the cylindrical portion 41. The seal member 15 of the main disk valve 14 is slidably contacted with the cylindrical portion 41, and the seal member 19 of the sub disk valve 18 is directly slidably contacted with the piston rod 4 to seal the back pressure chamber 16. The cylindrical portion 41 is provided with an oil passage 42 for communicating the extension side oil passage 6 with the cylinder lower chamber 2B. The coil spring 21 is used as the main disk valve 14 and the sub disk valve 18, and the coil spring 20 is omitted. With this configuration, the guide portion 11 of the valve member 10 can be omitted, and the pressure receiving areas of the main disk valve 14 and the back pressure chamber 16 can be increased.

It is a longitudinal cross-sectional view of the principal part of the hydraulic shock absorber according to the first embodiment of the present invention. It is a figure which expands and shows the elongation side damping force generation mechanism of the apparatus of FIG. It is a longitudinal cross-sectional view which expands and shows the expansion | extension side damping force generation mechanism of the hydraulic buffer which concerns on 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the expansion | extension side damping force generation mechanism of the hydraulic buffer which concerns on 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the expansion | extension side damping force generation mechanism of the hydraulic buffer which concerns on 4th Embodiment of this invention.

Explanation of symbols

1 Hydraulic shock absorber, 2 cylinders, 3 pistons, 4 piston rods, 14 main disc valve, 17 pilot passage, 18 sub disc valve (sub valve), 18A seat part

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 disc valve that generates a damping force by controlling a flow of oil liquid generated by sliding; and a back pressure chamber that applies an internal pressure in a valve closing direction of the main disc valve; In the hydraulic shock absorber introduced into the pressure chamber and controlling the opening of the main disk valve,
A pilot oil passage for introducing oil into the back pressure chamber is drilled in the main disc valve, and a sub valve for directly opening and closing the pilot oil passage is provided on the back side of the main disc valve ,
When the piston speed is low, the main disk valve and the sub-valve open the main disk valve with the pilot oil passage closed by the sub-valve, and the sub-valve increases as the piston speed increases. The hydraulic shock absorber is characterized in that the hydraulic fluid is introduced into the back pressure chamber through the open pilot oil passage . 2. The hydraulic shock absorber according to claim 1, wherein the main disk valve and the sub valve are valves that open and close without causing bending of the valve body. 3. The pilot oil passage according to claim 1, wherein the main disc valve and the sub-valve open and close the pilot oil passage by seating a seat portion provided on either one of the main disc valve and the sub-valve. The hydraulic shock absorber described.

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