JP2007100726A - Hydraulic draft gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the subassembly of a valve member, a main valve and the other annular member which form a back-pressure chamber in a hydraulic draft having the back-pressure chamber to control the damping force. <P>SOLUTION: A piston 3 with a piston rod 4 connected thereto is fitted into a cylinder 2. Main disc valves 14, 28 control the oil liquid flow of expansion and contraction side oil passages 6, 7 to generate the damping force, and the back-pressure chambers 19, 33 control the valve opening pressure of main disc valves 14, 28. A guide 38 is projected toward a support 25 of the valve member 24. A shim disc 31 and the main disc valve 28 are fitted into the guide 38, and an elastic seal member 32 is fitted into the valve member 24 to hold them in the valve member 24. Unless the piston rod 4 is inserted, the guide 38 certainly positions the main disc valve 28 and the shim disc 31. <P>COPYRIGHT: (C)2007,JPO&INPIT

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 back pressure 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 shown in Patent Document 1, a back pressure chamber is provided on the back side of the disc valve, a part of the oil is introduced into the back pressure chamber, and the pressure in the back pressure chamber is closed with respect to the disc valve. A hydraulic shock absorber has been proposed in which the opening degree of the disc valve is controlled by acting in the direction to increase the degree of freedom in setting the damping force characteristic.
JP 2003-278819 A

  The hydraulic shock absorber described in Patent Document 1 is a piston rod on a ring member including a disk valve, a valve member for forming a back pressure chamber, a spacer, a shim or the like for setting a set load (initial deflection) on the disk valve. Is inserted and fitted, and these are assembled together. For this reason, these annular members cannot be sub-assembled in advance because their center positions cannot be aligned when the piston rod is inserted. In particular, when sub-assembly of an annular member such as a valve member for forming a back pressure chamber, a disk valve, and shims and spacers interposed between them, positioning of the annular member is difficult, It is a problem.

  The present invention has been made in view of the above points, and a valve member for forming a back pressure chamber, a disk valve, and an annular member interposed therebetween can be easily sub-assembled. An object is to provide a hydraulic shock absorber.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a cylinder in which oil is sealed, a piston slidably fitted in the cylinder, and one end connected to the piston and the other end. Has a piston rod extended to the outside of the cylinder, a main valve that generates a damping force by controlling the flow of oil produced by sliding of the piston, and a pressure acting in the valve closing direction of the main valve A hydraulic shock absorber comprising a back pressure chamber, wherein a part of the flow of the oil liquid is introduced into the back pressure chamber and the opening of the main valve is controlled by the pressure of the back pressure chamber;
The main valve is clamped between a valve member forming the back pressure chamber and the piston, and an annular member is interposed between the main valve and the valve member, the main valve, the piston, The valve member and the annular member are integrally assembled with the piston rod inserted therethrough, and a support portion is formed on the valve member to abut against and clamp the annular member. Further, a cylindrical guide portion that is fitted to the inner periphery of the annular member and the main valve is projected.
According to a second aspect of the present invention, in the hydraulic shock absorber according to the first aspect, an annular elastic seal member is fixed to the outer peripheral portion of the main valve on the back side, and the elastic seal member is the valve. The back pressure chamber is formed by fitting with a member.

According to the hydraulic shock absorber of the first aspect of the present invention, the annular member and the main valve are fitted to the guide portion of the valve member, so that they can be positioned reliably and can be easily sub-assembled. it can.
According to the hydraulic shock absorber according to the invention of claim 2, by fitting the annular member and the main valve to the guide portion of the valve member and fitting the elastic seal member to the valve member, the elastic force of the elastic member The annular member and the main valve can be held on the valve member.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, a hydraulic shock absorber 1 according to this embodiment is a cylindrical hydraulic shock absorber that is mounted on a suspension device of a vehicle such as an automobile, and includes a cylinder 2 (one of side walls) in which oil is sealed. The piston 3 is slidably fitted in the inside of the cylinder 2, and the inside of the cylinder 2 is defined by the piston 3 as two chambers, a cylinder upper chamber 2 </ b> A and a cylinder lower chamber 2 </ b> B. 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 end portions of the cylinder 2 and the outer cylinder and an oil seal. (Not shown) is inserted 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. A support portion 11 extending to the vicinity of the opening end is formed at the inner central portion of the bottom portion of the valve member 10. The valve member 10 has a piston rod 4 inserted through a support portion 11 and is fixed together with a piston 3 and the like by a nut 5. On the end surface of the piston 3 on the cylinder lower chamber 2 </ b> B side, an annular clamp portion 12 and a seat portion 13 protrude from the inner peripheral side and the outer peripheral side, respectively, and an extension side is provided between the clamp portion 12 and the seat portion 13. An oil passage 6 is opened. The sheet portion 13 has a protruding height larger than that of the clamp portion 12. An annular main disk valve 14 (main valve), a notch disk 15, a plain disk 16, and a shim disk 17 (annular member) are clamped between the clamp part 12 and the support part 11 of the valve member 10.
The shim disc 17 acts as a fulcrum when the main disc valve 14 is opened, and the characteristics of the main disc valve 14 can be changed by arbitrarily setting the outer diameter thereof. Further, when the shim disk 17 is not inserted, the fulcrum of the main valve 14 is the valve member 10 made of sintered metal, so that the accuracy is low and soft in the sintering, which causes variations in damping force. By inserting the disc 17, such a problem can be solved.

  The main disc valve 14 is a disk-shaped member having flexibility, and the outer peripheral portion is seated on the seat portion 13. An annular elastic seal member 18 is fixed to the outer peripheral portion on the back side of the surface of the main disk valve 14 seated on the seat portion 13, and the elastic seal member 18 is slidable within the cylindrical portion of the valve member 10. It is liquid-tightly fitted. As a result, a back pressure chamber 19 is formed inside the valve member 10, and the internal pressure of the back pressure chamber 19 acts on the main disc valve 14 in the valve closing direction. An orifice 20 that allows the back pressure chamber 19 to communicate with the extension-side oil passage 6 is formed by an opening formed in the main disk valve 14 and a notch formed in the notch disk 15.

  An oil passage 21 that connects the back pressure chamber 19 to the cylinder lower chamber 2B is provided at the bottom of the valve member 10. The oil passage 21 is provided with a normally closed disk valve 22 (relief valve) for relieving the oil in the back pressure chamber 19 that has reached a predetermined pressure to the cylinder lower chamber 2B. In addition, a downstream orifice 23 (notch) is provided on the outer peripheral portion of the disk bubble 22 to always connect the back pressure chamber 19 to the cylinder lower chamber 2B.

Next, the contraction side damping force generation mechanism 9 will be described.
A substantially bottomed cylindrical valve member 24 is attached to the end of the piston 3 on the cylinder upper chamber 2A side. A support portion 25 extending to the vicinity of the opening end is formed at the inner central portion of the bottom portion of the valve member 24. The valve member 24 is fixed together with the piston 3 and the like by a nut 5 with the piston rod 4 inserted through the support portion 25. On the end surface of the piston 3 on the cylinder upper chamber 2 </ b> A side, an annular clamp portion 26 and a seat portion 27 protrude from the inner peripheral side and the outer peripheral side, respectively, and a contraction side is provided between the clamp portion 26 and the seat portion 27. An oil passage 7 is opened. The seat portion 27 has a protruding height larger than that of the clamp portion 26. An annular main disc valve 28 (main valve), a notch disc 29, a plain disc 30, and a shim disc 31 (annular member) are clamped between the clamp portion 26 and the support portion 25 of the valve member 24.

  The main disk valve 28 is a disk-shaped member having flexibility, and an outer peripheral portion is seated on the seat portion 27. An annular elastic seal member 32 is fixed to the outer peripheral portion on the back side of the surface of the main disk valve 28 seated on the seat portion 27, and the elastic seal member 32 is slidable within the cylindrical portion of the valve member 24. It is liquid-tightly fitted. As a result, a back pressure chamber 33 is formed inside the valve member 24, and the internal pressure of the back pressure chamber 33 acts on the main disc valve 28 in the valve closing direction. An orifice 34 that allows the back pressure chamber 33 to communicate with the contraction-side oil passage 7 is formed by an opening formed in the main disk valve 28 and a notch formed in the notch disk 29.

  An oil passage 35 that communicates the back pressure chamber 33 with the cylinder upper chamber 2 </ b> A is provided at the bottom of the valve member 24. The oil passage 35 is provided with a normally closed disk valve 36 (relief valve) for relieving the oil in the back pressure chamber 33 that has reached a predetermined pressure to the cylinder upper chamber 2A. Further, a downstream orifice 37 (notch) is provided on the outer peripheral portion of the disk bubble 36 so that the back pressure chamber 33 always communicates with the cylinder upper chamber 2A.

  Next, referring to FIG. 2, a structure for positioning the main disk valves 14 and 28 and the shim disks 17 and 31 with respect to the support parts 11 and 25 of the valve members 10 and 24, which is the main part of the present invention. explain. Since the extension side damping force generation mechanism 8 and the contraction side damping force generation mechanism 9 have substantially the same structure as described above, only the compression side damping force generation mechanism 9 will be described.

  As shown in FIG. 2, a cylindrical guide portion 38 through which the piston rod 4 is inserted protrudes from the distal end portion of the support portion 25 of the valve member 24. The protrusion height h of the guide portion 38 is larger than the plate thickness t1 of the shim disc 31 and smaller than the sum of the plate thickness t1 and the plate thickness t2 of the main disc valve 28 (t1 <h <t1 + t2). The shim disk 31, the main disk valve 28, the notch disk 29, and the plain disk 30 can be sandwiched between the distal end portion of the support portion 25 and the clamp portion 26 of the piston 3. Further, the outer diameter D of the guide portion 38 is smaller than the inner diameter d1 of the shim disc 31 and the inner diameter d2 of the main disc valve 28 (D <d1, D <d2), and the shim disc 31 is placed on the outer periphery of the guide portion 38. The main disc valve 28 can be fitted.

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 side 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, a damping force is generated by flowing the oil through the orifice 20, the back pressure chamber 19 and the orifice 23, and when the main disc valve 14 is opened, the opening is changed according to the opening degree. Damping force is generated. At this time, the oil liquid is introduced into the back pressure chamber 19 through the orifice 20 to increase the internal pressure of the back pressure chamber 19 and adjust the valve opening pressure of the main disc valve 14. When the pressure in the back pressure chamber 19 reaches a predetermined pressure, the disc valve 20 is opened, and the pressure in the back pressure chamber 19 is relieved to the cylinder lower chamber 2B side. Prevent excessive rise.

  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, damping force is generated when oil flows through the orifice 34, the back pressure chamber 33, and the orifice 37, and when the main disk valve 28 is opened, according to the opening degree. Damping force is generated. At this time, the oil liquid is introduced into the back pressure chamber 33 through the orifice 34, whereby the internal pressure of the back pressure chamber 33 rises and the valve opening pressure of the main disk valve 28 is adjusted. When the pressure in the back pressure chamber 33 reaches a predetermined pressure, the disc valve 36 is opened, and the pressure in the back pressure chamber 33 is relieved to the cylinder upper chamber 2A side, thereby reducing the valve opening pressure of the main disc valve 28. Prevent excessive rise.

  When the compression-side damping force generating mechanism 9 is assembled to the piston rod 4, the shim disk 31 and the main disk valve 28 are fitted into the guide part 38 protruding from the support part 25 of the valve member 24, and the main disk valve 28 By fitting the elastic seal member 32 into the cylindrical portion of the valve member 24, the main disk valve 28 and the shim disk 31 can be held on the valve member 24 by the elastic force of the elastic seal member 32, and these can be easily sub-assembled. Can be assembled. At this time, the shim disc 31 and the main disc valve 28 can be reliably positioned by the guide portion 38 even when the piston rod 4 is not inserted.

In the above embodiment, the case where there is one shim disk 31 has been described. However, the present invention is not limited to this, and even when there are a plurality of shim disks 31, the protrusion height of the guide portion 38 is appropriately set. By setting, it can be similarly applied. Further, the guide portion 38 may be chamfered at the tip portion or may be formed in a tapered shape with a small diameter in consideration of the assembling property of the shim disc 31 and the main disc valve 28.
Further, by increasing the outer diameter of the shim disk 31 and closing the orifice 34, the shim disk 31 can be operated as a check valve for introducing back pressure.
The present invention can also be applied to a reduction force adjustment type hydraulic shock absorber as disclosed in Patent Document 1 described above.
Furthermore, the damping force generation mechanism of the present invention is applicable not only to the piston part but also to the bottom or the like.

It is a longitudinal section showing the important section of the hydraulic shock absorber concerning one embodiment of the present invention. It is a figure which expands and shows the principal part of the compression side damping force generation mechanism of the hydraulic shock absorber shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic buffer, 2 Cylinder, 3 Piston, 4 Piston rod, 24 Valve member, 25 Support part, 28 Main disk valve (main valve), 31 Shim disk (annular member), 32 Elastic seal member, 33 Back pressure chamber, 38 Guide section

Claims (2)

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 back pressure chamber that applies pressure in a valve closing direction of the main valve, and a part of the flow of the oil liquid is In the hydraulic shock absorber introduced into the back pressure chamber and controlling the opening of the main valve by the pressure of the back pressure chamber,
The main valve is clamped between a valve member forming the back pressure chamber and the piston, and an annular member is interposed between the main valve and the valve member, the main valve, the piston, The valve member and the annular member are integrally assembled with the piston rod inserted therethrough, and a support portion is formed on the valve member to abut against and clamp the annular member. Further, a cylindrical buffer portion that is fitted to the inner periphery of the annular member and the main valve protrudes. An annular elastic seal member is fixed to an outer peripheral portion on the back side of the main valve, and the elastic seal member is fitted to the valve member to form the back pressure chamber. The hydraulic shock absorber according to 1.

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