JP4405657B2 - Hydraulic shock absorber valve structure - Google Patents

Description

[Industrial application fields]
The present invention relates to a hydraulic shock absorber that suppresses vibrations of a vehicle body such as an automobile suspension, and more particularly to a valve structure of a hydraulic shock absorber that can reduce variation in damping force.
[0001]
[Prior art]
As this type of hydraulic shock absorber, for example, those shown in FIGS. 3 and 4 are known. First, an outline of the structure will be described with reference to the drawings. Since the vertical relationship is the same as that in FIG. 3 when attached to the vehicle, the position or part of the member will be described below in the vertical relationship of FIG.
[0002]
A hydraulic shock absorber attached between a vehicle body and a wheel via a coupling member is assembled with a piston rod 1 attached to the vehicle body side and a piston valve for controlling an extension-side damping force and is slidably accommodated. At the same time, a cylinder 21 fitted with a base valve for controlling the compression damping force at the lower end is accommodated in an outer cylinder 22 attached to the wheel side, and a packing case 25 accommodating a seal 24 and a rod guide 23 for blocking outside air is removed. After the upper part of the cylinder 22 is inserted, the upper end part of the outer cylinder 22 is sealed by all-around welding or the like. A tank chamber D is formed between the cylinder 21 and the outer cylinder 22.
[0003]
When the piston rod 1 ascends in the cylinder 21 filled with hydraulic oil, the hydraulic oil in the sealed upper chamber A flows out to the lower chamber B through the piston valve, and the passage resistance at this time is increased on the extended side. Damping force. The hydraulic oil corresponding to the piston rod withdrawal volume that is insufficient due to the rise of the piston rod 1 is replenished from the bottom chamber C connected to the tank chamber D via a base valve disposed at the lower end of the cylinder 21.
[0004]
Next, a piston valve for controlling the extension side damping force will be described.
[0005]
An inlay portion 1A having a smaller diameter than the upper portion is provided at the lower end portion of the piston rod 1, and a valve stopper 2 for regulating the maximum deflection of the check valve CV including the leaf valve 3 and the notched leaf valve 4 is provided on the outer end thereof. A notch leaf valve 4 with a notch 4A provided on the outer periphery of the ring valve 7, the leaf valve 3, and the leaf valve 3 that are superimposed on the lower side of the check valve CV is supported. The pistons 5 facing each other are sequentially inserted.
[0006]
An extension port 5A that communicates the upper chamber A and the annular lower opening window 5C is perforated in the piston 5 that divides the inside of the cylinder 21 into an upper chamber A and a lower chamber B and is wound with a guide 5S. In addition, a pressure side port 5B that communicates the lower chamber B with the annular upper opening window 5D is perforated. The expansion side damping valve PV made up of the leaf valve 6 faces the lower opening window 5C. Subsequently, the ring seat 7 whose outer end is the support diameter of the extension side damping valve PV and the valve stopper 8 that regulates the maximum deflection of the extension side damping valve PV are sequentially assembled, and finally the piston nut 9 is attached to the inlay portion 1A. A piston valve is configured by screwing onto a threaded portion and fastening with a tightening tool.
[0007]
In a so-called extension process in which the piston rod 1 ascends in the cylinder 21 filled with hydraulic oil, the extension side damping is performed in a so-called low speed region where the piston speed is small and the pressure difference between the lower opening window 5C of the piston and the lower chamber B is small. The valve PV covers the lower opening window 5C. For this reason, the pressure oil in the upper chamber A passes through the notch 4A of the notch leaf valve 4 and flows out to the lower chamber B through the upper opening window 5D and the pressure side port 5B of the piston. A low-speed extension side damping force proportional to the square of the speed is generated.
[0008]
As the piston speed increases, the flow rate passing through the notch 4A of the notch leaf valve 4 increases, the pressure difference before and after the notch increases, and the piston communicating with the upper chamber A via the expansion side port 5A. The pressure difference between the lower opening window 5C and the lower chamber B is also increased.
[0009]
As the piston speed approaches the middle speed range, the outer peripheral side of the expansion side damping valve PV disposed facing the lower opening window 5C overcomes the combined bending rigidity, and the outside of the lower opening window 5C. The hydraulic fluid is pushed open from the seat portion 5F and flows out into the lower chamber B, and the extension side damping force after the middle speed region is generated by the passage resistance at this time and the passage resistance of the extension side port 5A. The required damping force characteristic can be obtained by appropriately selecting the bending rigidity of the expansion side damping valve PV comprising the leaf valve 6 and the passage area of the expansion side port 5A.
[0010]
Next, a base valve for controlling the compression side damping force will be described. First, a valve stopper 12 for restricting the maximum deflection of the suction valve DV comprising the leaf valve 13 and the notch leaf valve 14 is provided on the shaft portion 11A of the guide 11, and the ring seat 17 whose outer end is a support diameter for the deflection of the suction valve DV. , A leaf valve 13, a notched leaf valve 14 that is superimposed on the lower side of the leaf valve 13 and provided with a notch 14 </ b> A on the outer periphery, and a valve case 15 that has an upper surface facing the notched leaf valve 14 are sequentially inserted.
[0011]
An inner peripheral port 15B that connects the lower chamber B and the annular lower opening window 15C is drilled in the valve case 15 that is fitted to the lower end of the cylinder 21 and divides the lower chamber B and the bottom chamber C. In addition, an outer peripheral port 15A communicating the bottom chamber C and the annular outer opening window 15K is perforated.
[0012]
Subsequently, on the shaft 11A of the guide 11, the pressure side damping valve BV including the leaf valve 16 facing the outer opening window 15K of the valve case, and the ring seat whose outer end serves as a support diameter for the bending of the pressure side damping valve BV. 17. A valve stopper 18 for restricting the maximum deflection of the compression side damping valve BV is sequentially assembled, and finally, a base valve is configured by caulking the lower end portion of the shaft portion 11A of the guide with a tool.
[0013]
In a so-called contraction process in which the piston rod 1 descends in the cylinder 21 filled with hydraulic oil, in the so-called low speed region where the piston speed is small and the pressure difference between the lower opening window 15C of the valve case and the bottom chamber C is small, the compression side damping. The valve BV covers the lower opening window 15C. For this reason, the pressure oil in the lower chamber B, excluding the amount replenished in the upper chamber A whose volume is increased via the piston, is removed through the notch 14A of the notch leaf valve, the outer opening window 15K, and the outer peripheral port 15A. The chamber C is opened, and a pressure-side base damping force in a low speed region proportional to the square of the piston speed is generated by the passage resistance at this time.
[0014]
Here, the pressure oil in the lower chamber B that is replenished to the upper chamber A whose volume is increased via the piston is in a so-called low speed region where the piston speed is small and the pressure difference between the outer opening window 15K of the piston and the upper chamber A is small. The check valve CV comprising the leaf valve 3 and the notched leaf valve 4 covers the upper opening window 5D. For this reason, the pressure oil in the lower chamber B passes through the pressure side port 5B of the piston 5 and flows out into the upper chamber A through the notch 4A of the notch leaf valve 4, and the passage resistance at this time causes the piston speed to be almost 2%. It generates a compression side backside damping force in the low speed range proportional to the power. A pressure side damping force in a low speed region is obtained by adding the compression side back damping force to the compression side base damping force.
[0015]
As the piston speed increases, the flow rate passing through the notch 14A increases, the pressure difference before and after the notch increases, and the through hole 13A of the leaf valve 13 and the notch leaf valve 14 communicating with the through hole 13A. The pressure difference between the bottom chamber C and the lower opening window 15C of the valve case communicating with the lower chamber B via the opening 14B, the upper opening window 15D of the valve case, and the inner peripheral port 15B also increases.
[0016]
For this reason, as the piston speed approaches the middle speed range, the outer peripheral side of the compression side damping valve BV composed of the leaf valve 16 disposed facing the lower opening window 15C overcomes the combined bending rigidity. The hydraulic oil is pushed open from the outer sheet portion 15F of the side opening window 15C and flows out into the bottom chamber C, and a pressure-side base damping force after the middle speed region is generated by the passage resistance and the passage resistance of the inner peripheral port 15B. To do.
[0017]
Here, in the upper chamber A whose volume is increased, it passes through the pressure side port 5B of the piston 5 and overcomes the combined bending rigidity of the check valve CV composed of the leaf valve 3 and the notched leaf valve 4, and the outer peripheral side thereof is overcome. The hydraulic oil is pushed up and replenished from the lower chamber B, and a pressure side rear damping force after the middle speed region is generated by the passage resistance at this time. The pressure side rear damping force added to the pressure side base damping force becomes the pressure side damping force after the medium speed range.
[0018]
On the contrary, when the piston rod 1 moves up, it passes from the bottom chamber C through the outer peripheral port 15A of the valve case, overcomes the bending rigidity of the suction valve DV comprising the leaf valve 13 and the notch leaf valve 14, , And the lower chamber B is replenished with hydraulic oil corresponding to the withdrawal volume of the piston rod 1.
[0019]
[Problems to be solved by the invention]
Since the shape of the upper and lower valve support structures in the piston 5 and the valve case according to the prior art is similar, the problem to be solved will be described by taking the valve support structure on the lower chamber B side of the piston valve as an example. To do. As shown in FIGS. 3 and 4, the lower opening window 5C formed on the lower surface of the piston 5 has a cylindrical central boss portion 5E and an annular outer sheet slightly higher (for example, 5 μ) than the boss portion 5E. It is an annular groove surrounded by the portion 5F.
[0020]
On the other hand, the valve stopper 8 which is attached to the lower side of the ring seat 7 which serves as a bending support portion of the expansion side damping valve PV and regulates the bending of the expansion side damping valve PV is a ring seat which functions as a bending support member. In order to securely hold the outer end of 7 from the lower side, the upper surface is a tapered surface whose gradient rises upward from the base end side toward the outer end side. If the outer diameter of the ring seat 7 is made larger than the outer diameter of the boss portion 5E in order to set a high damping force in accordance with the requirements of the vehicle, the outer end of the ring seat 7 is pushed by the taper surface of the valve stopper 8 and the piston It is pushed down to the 5th side.
[0021]
Since the piston 5 is provided with a level difference in which the annular seat portion 5F is slightly higher than the boss portion 5E in order to stabilize the damping force, the extension side damping held between the boss portion 5E and the valve stopper 8 is provided. In addition to the initial deflection due to the step between the seat portion 5F and the boss portion 5E, the initial deflection of the valve PV is increased by the amount that the valve stopper 8 is pushed down to the piston 5 side. The increase in the initial deflection varies depending on the appearance of the tapered surface, and the valve opening pressure changes accordingly. Therefore, the variation in the damping force increases accordingly.
[0022]
The present invention has been made in view of the above circumstances, and the object of the present invention is a hydraulic pressure in which variation in damping force does not increase even if the outer diameter of the ring seat is larger than the outer diameter of the boss portion. Is to provide a shock absorber.
[0023]
[Means for solving problems]
In the present invention, two oil chambers are defined in a cylinder via a partition member made of a piston or a valve case, and the two oil chambers are formed on a port formed in the partition member and an outlet end of the port or an inlet and an outlet end of the port. Communicating through the opening windows formed on both sides, the opening window is regulated by a base end side boss portion and an outer annular seat portion, and a leaf valve for opening and closing the opening window is provided between the boss portion and the seat portion. The leaf valve's base end-side back is supported via a ring seat, and the ring seat is supported by a valve stopper having a tapered surface whose gradient rises from the base end side toward the outer end side. Assuming a hydraulic shock absorber. The leaf valve constitutes an extension side damping valve and a check valve on the piston side, or a pressure side damping valve and a suction valve on the valve case side.
[0024]
In order to solve the problem, the means adopted by the present invention is that a plurality of protrusions are provided along the circumferential direction on the outer peripheral side of the boss part, which are connected to the end face of the boss part and protrude outward from the outer end of the ring seat. That is. It is desirable that the protrusions have the same protrusion height in the radial direction and are equally divided in the circumferential direction.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
The hydraulic shock absorber according to the present invention has the same basic structure as the prior art of FIG. 3, and the piston rod 1 is movably inserted into the cylinder 21 via the piston 105 attached to the lower end portion thereof, The upper chamber A and the lower chamber B are partitioned. A valve case 115 is fitted to the lower end portion of the cylinder 21, and similarly defines the lower chamber B and the bottom chamber C.
[0026]
The lower opening window 105C and the upper opening window 105D of the piston 105 corresponding to the ring seat 107 on the piston valve side are vertically symmetrical, and the lower opening window 115C and the upper side of the valve case 115 corresponding to the ring seat 117 on the base valve side. Since the opening window 115D is substantially vertically symmetric, the following description will be made by taking the lower opening window as an example in the order of the piston and the valve case.
[0027]
3, the piston 105 divides the upper chamber A and the lower chamber B, and the upper chamber A and the lower chamber B communicate with each other via an extension side port 105A and a pressure side port 105B formed in the piston 105. ing. The lower opening window 105C formed at the outlet end of the extension side port 105A is opened and closed by the extension side damping valve PV, and the upper opening window 105D formed at the outlet end of the compression side port 105B is opened and closed by the check valve CV.
[0028]
The upper side of the expansion side damping valve PV that contacts the lower opening window 105C is supported by an outer annular sheet portion 105F that regulates the lower opening window 105C and a central boss portion 105E. 107 is supported. The ring seat 107 is supported by a valve stopper 108 fastened by a piston nut 9, and the upper surface of the valve stopper 108 is formed as a tapered surface with a gradient rising from the base end side toward the outer end side.
[0029]
The embodiment of the present invention shown in FIG. 1 will be described first from the valve support structure on the expansion-side damping valve PV side for the piston valve. As shown in FIG. 1, the piston valve according to the present invention is a gently tapered surface having an outer height (for example, 5 μ) in which the upper surface of the valve stopper 108 is inclined toward the piston 105 from the base end side to the outer end side, and The outer end of the ring seat 107 is larger than the outer end of the boss portion 105E, and a damping force higher than usual can be set.
[0030]
In general, as a method for preventing the outer end of the ring seat 107 from affecting the initial deflection of the expansion side damping valve PV, it is considered that the outer diameter of the boss portion 105E of the piston 105 is made larger than the outer diameter of the ring seat 107. It is done. However, according to this method, since the opening area of the annular lower opening window 105C is reduced, the degree of freedom in setting the damping force is lowered.
[0031]
Therefore, the present invention has been developed as another method for achieving the above object without greatly reducing the opening area of the lower opening window 105C. That is, on the outer peripheral side of the lower boss portion 105E, a plurality of protrusions 105J continuous to the end face of the lower boss portion 105E are provided to protrude outward along the circumferential direction. Is supported by the lower boss 105E and the projection 105J. The proximal side rear surface of the extension side damping valve PV is supported by a ring seat 107.
[0032]
For this reason, the protrusion 105J slightly reduces the opening area of the lower opening window 105C, but can increase the opening area as compared with the case where the entire outer diameter of the lower boss portion 105E is increased. The projecting height of the plurality of protrusions 105 </ b> J may be such that each vertex of the protrusion 105 </ b> J protrudes outward from the outer end of the ring seat 107. The protrusions 105J may be at least two support portions, but in order to uniformly prevent the bending of the ring seat 107, which is a support member for bending the expansion side damping valve PV, to prevent fluctuations in the damping force, It is desirable that there are three or more.
[0033]
As long as the above conditions are satisfied, the protruding heights of the plurality of protrusions 105J may be slightly uneven. However, the protrusions 105J have the same protruding height and are equally divided in the circumferential direction. It is more preferable to provide them. This is because, when the center of the circumscribed circle connecting the vertices of the protrusion 105J is the same as the axial center of the lower boss portion 105E and is equally divided in the circumferential direction, the extension contacted with the lower opening window 105C is made. This is because the initial deflection of the side damping valve PV becomes uniform. The extension side port 105A is drilled at a position where it does not interfere with the protrusion 105J.
[0034]
According to the above configuration, even if the outer peripheral side of the ring seat 107 is likely to be pushed down to the piston 5 side by the upper surface taper of the valve stopper 108, the circumferential protrusion 105J prevents this, so the expansion side damping valve PV Therefore, it is possible to prevent an increase in variation in damping force. Although the case where the protrusion 105J is provided on the lower boss portion 105E side has been described, it can be provided on the upper boss portion 105G side in the same manner.
[0035]
In this case, the valve support structure of the check valve CV that contacts the upper opening window 105D is substantially the same as the valve support structure of the extension-side damping valve PV, and thus detailed description thereof is omitted. However, since the pressure side damping force generated on the check valve CV side is smaller than the pressure side base damping force generated on the pressure side damping valve BV side, the protrusions 105J are not necessarily provided on both sides. You may provide only in the part 105E side.
[0036]
Next, a case where the above invention is applied to the base valve side will be described. The upper side of the pressure side damping valve BV that contacts the lower opening window 1 15C is supported by an outer annular seat portion 1 15F that regulates the lower opening window 1 15C and a central boss portion 1 15E, and the rear surface side of the base end portion is the annular seat 1 17 It is supported by. The annular seat 1 17 is supported by a valve stopper 1 18, and the upper surface of the valve stopper 1 18 is formed as a tapered surface whose gradient rises from the base end side toward the outer end side.
[0037]
On the outer peripheral side of the lower boss portion 115E of the valve case 115, at least two protrusions 115J connected to the end surface of the lower boss portion 115E are desirably divided into the circumferential direction and projected outward. Set up. In this case, as in the piston valve side, even if the outer peripheral side of the ring seat 117 is likely to be pushed down to the valve case 115 side by the taper of the upper surface of the valve stopper 118, the circumferential projection 115J of the valve case 115 Therefore, the initial deflection of the compression side damping valve BV formed of the leaf valve 16 is not increased, so that an increase in variation in damping force can be prevented in advance.
[0038]
Although the case where the protrusion 115J is provided on the lower opening window 115C side is described, the protrusion 115J can be provided on the upper opening window 1 15D side in the same manner. Since the valve support structure of the suction valve DV that contacts the upper opening window 1 15D is substantially the same as the valve support structure of the compression side damping valve BV, detailed description thereof is omitted. However, the suction valve DV is originally set to have a small bending rigidity in order to improve the suction performance, and the influence of the initial deflection of the suction valve DV due to the bending of the ring seat 117 is small. Therefore, the protrusions 115J are necessarily provided on both sides. However, it may be provided only on the lower boss portion 115E side.
[0039]
Further, the piston 105 and the valve case 115 according to the present invention have the outer ends of the ring seats corresponding to the lower boss portion 105E and the upper boss portion 105G of the piston, the lower boss portion 115E and the upper boss portion 115G of the valve case, Each can be used as it is even when it has the same diameter or smaller diameter than the outer end of each boss. Furthermore, the present invention may be applied to either the piston valve side or the base valve side, or may be applied to both.
[0040]
【The invention's effect】
As described above in detail, according to the present invention, the protrusions that are connected to the end surface of the boss portion that supports the leaf valve and project outward from the outer end of the ring seat that supports the leaf valve from the back surface are provided in the circumferential direction, etc. It is possible to prevent the degree of freedom in setting the damping force from being lowered, and even if the outer peripheral side of the ring seat is likely to be pushed down to the partition wall member side by the tapered surface of the valve stopper, Since the circumferential protrusion prevents this, the initial deflection of the leaf valve is not increased, so that an increase in variation in damping force can be prevented in advance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a hydraulic shock absorber according to the present invention.
FIG. 2 is a bottom view of a piston according to the present invention.
FIG. 3 is a longitudinal sectional view of a hydraulic shock absorber according to the prior art.
FIG. 4 is a bottom view of a piston according to the prior art.
[Explanation of symbols]
A Upper chamber B Lower chamber BV Pressure side damping valve CV Check valve DV Suction valve PV Extension side damping valve 6, 16 Leaf valve (piston side, valve case side)
21 Cylinder 105 Piston 105C, 105D Opening window (lower and upper side of piston)
105E, 105G Boss (lower and upper side of piston)
105F, 115F annular seat (piston side, valve case side)
105J, 115J Protrusion (piston side, valve case side)
107,117 Ring seat (piston side, valve case side)
115 Valve case 115C, 115D Opening window (lower side, upper side of valve case)
115E, 115G Boss (lower side and upper side of valve case)

Claims (3)

Two oil chambers are defined in the cylinder via a partition member made of a piston or a valve case, and the two oil chambers are formed in the port formed in the partition member and both the port outlet end or the port inlet and outlet ends. The opening window communicates via an opening window, and the opening window is regulated by a proximal end boss portion and an outer annular seat portion, and a leaf valve for opening and closing the opening window is freely opened and closed between the boss portion and the seat portion. In contact, the rear end of the leaf valve is supported by a ring seat, and the ring seat is supported by a valve stopper having a tapered surface with a gradient rising from the base end toward the outer end. The valve of the hydraulic shock absorber, characterized in that a plurality of protrusions protruding in the circumferential direction are provided on the outer peripheral side of the boss portion, which are connected to the end face of the boss portion and protrude outward from the outer end of the ring seat. Construction. 2. The valve structure of a hydraulic shock absorber according to claim 1, wherein the leaf valve constitutes an extension side damping valve and a check valve on a piston side, or a pressure side damping valve and a suction valve on a valve case side. 2. The valve structure for a hydraulic shock absorber according to claim 1, wherein the protrusions are provided with the same height in the radial direction and equally divided in the circumferential direction.

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