JP5322678B2 - shock absorber - Google Patents

Description

  The present invention relates to a shock absorber that buffers a load using a viscous fluid, and more particularly, to a shock absorber having a novel throttle adjustment mechanism that can accurately and smoothly realize a throttle adjustment of a viscous fluid flow rate according to a load. .

  2. Description of the Related Art Conventionally, there is known a shock absorber that is applied to a stopper of an object such as a conveyor line, a robot arm, or a cylinder to buffer an impact at the time of collision of these objects.

  As this type of shock absorber, the applicant of the present application has a cylinder in which a viscous fluid is sealed, a piston provided in the cylinder, an outer diameter smaller than the outer diameter of the piston, and a predetermined range in the axial direction. A plate that is supported only movably, a groove formed between the plate and the piston, and a reflux hole that penetrates between both end surfaces of the piston and communicates with the groove. When the viscous fluid passes through the reflux hole via the groove, a technique is proposed in which the flow rate of the viscous fluid passing through the reflux hole is reduced by the groove (Patent Document 1).

  However, when a mechanism for adjusting the flow rate of the viscous fluid passing through the reflux hole according to the movement position of the plate in the axial direction as in the prior art according to Patent Document 1, for example, between the shaft and the plate is used. If any foreign matter is caught in the plate, there is a possibility that the viscous fluid flow rate cannot be adjusted due to the malfunction of the plate.

JP 2006-118651 A

  In the prior art which concerns on patent document 1, there existed a possibility of causing the situation which cannot restrict | squeeze and adjust a viscous fluid flow volume.

An object of the present invention is to provide a shock absorber having a novel throttle adjustment mechanism capable of accurately and smoothly realizing a throttle adjustment of a viscous fluid flow rate according to a load. A cylinder having a shape, a substantially cylindrical piston that is slidably provided in the cylinder and that transmits a force from a load, and a load side and an anti-load side of the cylinder sandwiching the piston, respectively. A valve having a load-side fluid chamber and an anti-load-side fluid chamber, a base portion fixed to the anti-load side of the piston, and an annular flap portion integrally provided around the base portion, The piston is provided with a reflux hole that passes through the piston and communicates the load-side fluid chamber and the anti-load-side fluid chamber, and an annular valve in which the flap portion faces the anti-load side of the piston. And the flap portion bends according to the pressure difference between the fluid chambers, and the gap between the flap portion and the valve receiving portion is displaced, so that the flow rate of the viscous fluid flowing through the return hole is reduced. A shock absorber to be adjusted , wherein the valve is formed such that the thickness of the base is thicker than the thickness of the flap, and the thickness of the flap is gradually reduced from the base toward the outer periphery. The main feature is that it is formed .

  According to the shock absorber according to the present invention, the flap portion bends according to the pressure difference between the fluid chambers of the load side fluid chamber and the anti-load side fluid chamber, and the gap between the flap portion and the valve receiving portion is displaced. As a result, the flow rate of the viscous fluid flowing through the reflux hole is throttled and adjusted, so that the throttle adjustment of the viscous fluid flow rate according to the load can be realized accurately and smoothly.

It is sectional drawing which shows the whole structure of the shock absorber which concerns on Example 1 (Example 1). It is a principal part enlarged view of the shock absorber which concerns on Example 1 (Example 1). (Example 1) which shows the process at the time of attaching a valve to a piston. Fig. 4 (1) is an explanatory diagram of a valve throttle adjusting mechanism derived from the behavior of viscous fluid when the piston is retracted (lowered) to the anti-load side, and Fig. 4 (2) is an illustration of the piston on the load side. (Embodiment 1) It is explanatory drawing of the throttle adjustment mechanism of the valve originating in the behavior of a viscous fluid at the time of extension movement (rise). It is a principal part enlarged view of the shock absorber which concerns on Example 2 (Example 2). It is a principal part enlarged view of the shock absorber which concerns on Example 3 (Example 3). It is a principal part enlarged view of the shock absorber which concerns on Example 4 (Example 4).

  The flap part bends according to the pressure difference between the fluid chambers of the load-side fluid chamber and the anti-load-side fluid chamber for the purpose of accurately and smoothly realizing the throttle adjustment of the viscous fluid flow rate according to the load. This is realized by a novel throttle adjustment mechanism that adjusts the flow rate of the viscous fluid flowing through the reflux hole by changing the gap between the flap part and the valve receiving part.

A shock absorber according to Embodiment 1 of the present invention will be described with reference to the drawings.
[Overall Configuration of Shock Absorber According to Embodiment 1]
FIG. 1 is a cross-sectional view showing the overall configuration of the shock absorber according to the first embodiment, FIG. 2 is an enlarged view of a main part of the shock absorber according to the first embodiment, and FIG. 3 shows a process for attaching a valve to the piston. It is explanatory drawing.

  As shown in FIGS. 1 and 2, the shock absorber 11 according to the present embodiment is provided with a cylinder 13 in which a viscous fluid is sealed, and is slidably provided in the cylinder 13, and a force from a load (not shown). Is connected to a shock absorbing object (not shown) as a load, and the other end of the cylinder 13 penetrating the load side member is connected to the piston 15. The flow rate of the viscous fluid is throttled and adjusted by bending the metal piston rod 17 that transmits the force from the load to the piston 15, and the base 15 a fixed to the piston 15 and the load. And a valve 19 having a flap portion 15b.

  The cylinder 13 made of metal (or made of resin is acceptable) is formed in a substantially cylindrical shape having one end opened and the other end closed by a bottom wall 13a.

  In the cylinder 13, a substantially cylindrical first fluid chamber 13 b is provided on the load side, and a substantially cylindrical second fluid chamber 13 c is provided on the non-load side. The inner diameter of the second fluid chamber 13c is made smaller than the inner diameter of the first fluid chamber 13b, and a stepped receiving portion 21 extending in the circumferential direction is formed at the boundary between the two fluid chambers 13b and 13c. .

  In the first fluid chamber 13b, a metal rod guide 23 extending over substantially the entire length in the longitudinal direction of the fluid chamber 13b is provided so as to be held in close contact with the cylindrical piston rod 17.

  A flange portion 25 that extends in the circumferential direction and has an outer diameter slightly smaller than the inner diameter of the first fluid chamber 13b is integrally formed on the non-load side of the rod guide 23. The rod guide 23 is fixed in the first fluid chamber 13b in a state where the flange portion 25 is abutted against the receiving portion 21.

  The intermediate portion of the rod guide 23 in the extending direction has a thin outer peripheral edge, thereby forming a liquid storage chamber 27 partitioned by the inner wall of the first fluid chamber 13b and the outer wall of the rod guide 23. Has been. The liquid storage chamber 27 has a small gap formed between the flange portion 25 and the inner wall of the first fluid chamber 13b when the piston rod 17 advances in the load buffering direction and enters the second fluid chamber 13c. On the other hand, the viscous fluid overflowed by the amount of intrusion of the piston rod 17 is received from the second fluid chamber 13c. On the contrary, the piston rod 17 moves backward with respect to the load buffering direction and the second fluid chamber 13c. When retracted from the inside, the viscous fluid reduced by the retracted amount of the piston rod 17 is returned to the second fluid chamber 13c via the gap.

  A circumferential groove 29 is formed on the load side of the rod guide 23. An O-ring 31 made of an elastic material such as silicon rubber is fitted into the circumferential groove 29. Due to the liquid tightness that occurs when the O-ring 31 comes into contact with the inner wall of the first fluid chamber 13b, the viscous fluid that has traveled from the liquid storage chamber 27 through the inner wall of the first fluid chamber 13b is leaked to the outside. Can be prevented.

  A substantially cylindrical recess 33 is integrally formed at the load side end of the rod guide 23. A substantially annular seal member 35 is attached to the recess 33 so as to be in close contact with the piston rod 17. And, in order to isolate this hollow portion 33 from the outside, an opening end of the cylinder 13, and at the load side end of the piston rod 17, a through hole 37 a for insertion of the piston rod 17 is opened at the center thereof. A lid 37 is provided. Viscous fluid that has been transmitted from the second fluid chamber 13c through the gap formed between the surface of the piston rod 17 and the inner wall of the rod guide 23 due to liquid tightness caused by the sealing member 35 coming into close contact with the piston rod 17. Leakage to the outside can be prevented.

  As the viscous fluid filled in the cylinder 13, an incompressible viscous fluid such as silicone oil can be preferably used. The buffer characteristics can be finely adjusted by changing the viscosity of the oil used.

  For example, the resin piston 15 is slightly smaller than the inner diameter of the second fluid chamber 13 c, and a minute clearance is formed between the inner wall of the cylinder 13.

  As shown in FIG. 2, the piston 15 passes through the piston 15 and corresponds to a third fluid chamber (load-side fluid chamber) 13 d and a second fluid chamber 13 c (the “anti-load-side fluid chamber” of the present invention). Are provided with a plurality of columnar reflux holes 15a communicating with each other. The diameters of the reflux holes 15a are set to appropriate values based on the fluid resistance at the time of advancement and retraction of the piston 15, and cause a predetermined passage resistance to the viscous fluid.

  As shown in FIG. 3, a substantially cylindrical protruding portion 15 b to which the base portion 19 a of the valve 19 is fixed is integrally formed on the anti-load side of the piston 15. An annular groove 15c into which the fitting through hole 19c provided in the base portion 19a of the valve 19 is fitted is formed in the protruding portion 15b. The width of the annular groove 15c (dimension in the vertical direction in FIG. 3) is such that the fitting through hole 19c provided in the base portion 19a of the valve 19 is fitted and fitted, and the valve 19 is moved up and down. The width of the base portion 19a of the valve 19 is made slightly larger in consideration of the fact that it can move together as a unit. A chamfering process 15d is applied to a corner portion in the circumferential direction at the distal end portion of the projecting portion 15b in order to facilitate mounting of the valve 19 to the projecting portion 15b.

  Further, on the anti-load side of the piston 15, a valve receiving portion 15 e that protrudes in an annular shape is provided at a position where the flap portion 19 b of the valve 19 faces in a state where the valve 19 is fixed to the piston 15.

  On the load side of the piston 15, a fitting hole 15 f is provided in which the opposite end of the piston rod 17 is fitted and fixed.

  The valve 19 is made of a flexible elastic material such as rubber. The valve 19 is integrally formed around the base 19a and the base 19a, and is a substantially conical flap that bends according to the pressure difference between the fluid chambers 13d and 13c. Part 19b. The base 19a is provided with the above-described fitting through hole 19c. The flap portion 19b is configured to incline from the base portion 19a toward the anti-load side direction. The thickness of the flap portion 19b is formed so as to gradually decrease from the base portion 19a toward the outer peripheral edge. In the shock absorber 11 according to the first embodiment, as shown in FIG. 2, the gap between the flap portion 19b and the valve receiving portion 15e is opened under no load condition. Further, in the loaded state, the gap is displaced from the initial open position to the closed position according to the magnitude of the load.

Accordingly, when the piston 15 moves back and forth, the flap portion 19b bends according to the pressure difference between the fluid chambers 13d and 13c, and the gap between the flap portion 19b and the valve receiving portion 15e is displaced, so that it flows through the reflux hole 15a. It operates so that the flow rate of the viscous fluid to be throttled is adjusted.
[Operation of Shock Absorber According to Example 1]
Next, the operation of the shock absorber according to the first embodiment will be described with reference to FIGS. 4 (1) and (2).

  Fig. 4 (1) is an explanatory diagram of a valve throttle adjusting mechanism derived from the behavior of viscous fluid when the piston is retracted (lowered) to the anti-load side, and Fig. 4 (2) is an illustration of the piston on the load side. It is explanatory drawing of the throttle adjustment mechanism of the valve originating in the behavior of a viscous fluid at the time of extension movement (rise).

  Prior to the description of the operation of the shock absorber according to the first embodiment, the piston 15 is moved under the assumption that the gap between the flap portion 19b and the valve receiving portion 15e is maintained as it is and the reflux hole 15a is open. Reference is made to the point that the pressure difference of the viscous fluid between the sandwiched load-side and anti-load-side fluid chambers 13d and 13c correlates with the moving speed (load magnitude) of the piston rod 17. If the piston rod 17 moves at a high speed toward the anti-load side, the viscous fluid flowing through the reflux hole 15a in the piston 15 behaves so as to increase the flow speed. Then, although the viscous fluid tries to move from the anti-load side fluid chamber 13c to the load side, the narrow flow path of the reflux hole 15a becomes rate limiting, and the pressure of the anti-load side fluid chamber 13c increases. Therefore, it can be said that the above-described correlation is established under the predetermined assumption described above.

  As shown in FIG. 4 (1), when the piston rod 17 is retracted (lowered) to the anti-load side and is pushed into the cylinder 13, the piston 15 is linked to the anti-load side of the cylinder 13. Retreats (lowers). At this time, when the retracting movement speed of the piston rod 17 (correlating with the pressure difference of the viscous fluid between the fluid chambers 13b and 13c) is less than a set load that can deflect the flap portion 19b of the valve 19 to the load side. Since the gap between the flap portion 19b and the valve receiving portion 15e is maintained as it is, the piston 15 retreats (lowers) with the reflux hole 15a opened. In this case, the third fluid is moved between the piston 15 and the flange portion 25 of the rod guide 23 by the viscous fluid (see the dotted arrow in FIG. 4A) that has moved from the anti-load side fluid chamber 13c to the load side. A fluid chamber (load-side fluid chamber) 13d is formed. At this time, the shock absorber 11 buffers the load at the first buffer speed.

  On the other hand, when the retraction movement speed of the piston rod 17 exceeds a set load that can deflect the flap portion 19b of the valve 19 to the load side, the flap portion 19b of the valve 19 moves to the load side according to the magnitude of the load. Bend. As described above, the gap between the flap portion 19b and the valve receiving portion 15e is displaced, so that the flow rate of the viscous fluid flowing through the reflux hole 15a is throttled and adjusted. Thereby, the retreat movement speed of the piston 15 is decelerated to the second buffer speed lower than the first buffer speed, and the shock absorber 1 buffers the load at the second buffer speed.

  Further, when the retracting movement speed of the piston rod 17 greatly exceeds the set load that can deflect the flap portion 19b of the valve 19 to the load side, the flap portion 19b of the valve 19 is moved to the second fluid chamber (the anti-load side fluid). The chamber) is deformed all at once by the pressure received from the viscous fluid of 13c and reaches the seat 15e. In this way, when the flap portion 19b of the valve 19 is seated in close contact with the valve receiving portion 15e, the flow of the viscous fluid in the plurality of reflux holes 15a is completely stopped. Thereby, the retreat movement speed of the piston 15 is reduced to the maximum, and the shock absorber 11 buffers the load at a third buffer speed lower than the second buffer speed.

On the other hand, as shown in FIG. 4 (2), when the piston rod 17 extends (up) toward the load side and extends outward from the cylinder 13, the piston 15 moves to the cylinder 13 in conjunction therewith. The extension moves to the load side (rises). At this time, the viscous fluid pressure in the second fluid chamber (anti-load side fluid chamber) 13c becomes relatively smaller than the viscous fluid pressure in the third fluid chamber (load side fluid chamber) 13d. The viscous fluid flows toward the anti-load side fluid chamber 13c through the reflux hole 15a (see the solid line arrow in FIG. 4 (2)). Then, the flow of the viscous fluid acts on the flap portion 19b of the valve 19, and the gap between the flap portion 19b and the valve receiving portion 15e is maintained as it is or expanded. As a result, the viscous fluid in the third fluid chamber (load-side fluid chamber) 13d smoothly returns to the second fluid chamber 13c via the reflux hole 15a, so that the piston 15 returns to the original position before load buffering. Return. In the process of returning, the shock absorber 11 buffers the load at the fourth buffering speed.
[Effect of Example 1]
The shock absorber 11 according to the first embodiment passes through the return hole depending on the moving position of the plate in the direction in view of the possibility that the viscous fluid flow rate may not be throttled and adjusted in the related art according to Patent Document 1. Instead of the mechanism according to Patent Document 1 that restricts and adjusts the flow rate of the viscous fluid, the base portion 19a of the valve 19 is fixed to the piston 15, and the flap portion 19b supported by the base portion 19a includes the load side fluid chamber 13d and The flow rate of the viscous fluid flowing through the reflux hole 15a is throttled and adjusted by bending according to the pressure difference between the two fluid chambers of the anti-load side fluid chamber 13c and the gap between the flap portion 19b and the valve receiving portion 15e being displaced. The mechanism was adopted.

  Therefore, according to the shock absorber 11 according to the first embodiment, the adjustment of the viscous fluid flow rate according to the load can be realized accurately and smoothly.

  In addition, the viscous fluid flow rate adjusting mechanism does not employ a configuration that depends on the movement of the plate in the axial direction, and therefore has high reliability without malfunction due to foreign matter.

  Furthermore, if the flexible characteristic in the flap part 19b of the valve 19 is appropriately adjusted, the responsiveness can be enhanced.

  In addition, by reducing the clearance between the cylinder 13 and the piston 15 to the limit, the backlash of the piston 15 can be suppressed, so that durability is improved.

  FIG. 5 is an enlarged view of a main part of the shock absorber according to the second embodiment.

  The difference between the shock absorber according to the first embodiment described above and the shock absorber according to the second embodiment is as follows.

  That is, in the valve 19 configured to include the base portion 19a and the flap portion 19b according to the first embodiment, the flap portion 19b is configured to be inclined toward the anti-load side direction from the base portion 19a. Whereas the thickness is formed so as to gradually decrease from the base portion 19a toward the outer peripheral edge, in the valve 41 configured to include the base portion 41a and the flap portion 41b according to the second embodiment, The flap portion 41b is common in that it is configured to be inclined from the base portion 41a toward the anti-load side direction, but its thickness is gradually reduced continuously from the base portion 41a toward the outer peripheral edge. It is formed and is different from the first embodiment in terms of the flexible characteristics of the flap portion 41b.

  Note that the gap between the flap portion 41b and the valve receiving portion 15e is the same as that in the first embodiment in that the gap is opened under no load.

  According to the shock absorber according to the second embodiment, the adjustment of the viscous fluid flow rate according to the load according to the flexibility characteristic of the flap portion 41b of the valve 41 can be realized accurately and smoothly.

  FIG. 6 is an enlarged view of a main part of the shock absorber according to the third embodiment.

  Differences between the shock absorber according to the first embodiment described above and the shock absorber according to the third embodiment are as follows.

  That is, in the shock absorber 11 according to the first embodiment, the gap between the flap portion 19b and the valve receiving portion 15e is opened under no load condition, whereas in the shock absorber according to the third embodiment, the flap portion 51b. The gap between the valve receiver 15e and the valve receiving portion 15e is closed under a no-load condition, and is different from the first embodiment in the mounting state of the valve 51 for controlling the behavior of the viscous fluid.

  Next, the operation of the shock absorber according to the third embodiment will be described.

  When the piston rod 17 is retracted (lowered) to the anti-load side and pushed into the cylinder 13, the piston 15 is retracted (lowered) to the anti-load side of the cylinder 13 in conjunction therewith. At this time, the flap portion 19b of the valve 19 is seated in close contact with the valve receiving portion 15e, and the flow of the viscous fluid in the plurality of reflux holes 15a is completely stopped. As a result, the retreat movement speed of the piston 15 is reduced to the maximum, and the shock absorber according to the third embodiment buffers the load at the maximum buffer speed.

  On the other hand, when the piston rod 17 extends (rises) to the load side and extends outward from the cylinder 13, the piston 15 extends and moves (rises) to the load side of the cylinder 13 in conjunction therewith. . At this time, since the viscous fluid pressure in the second fluid chamber (anti-load side fluid chamber) 13c is relatively small with respect to the viscous fluid pressure in the third fluid chamber (load side fluid chamber), the refrigerant returns from the load side fluid chamber. A viscous fluid flows toward the anti-load side fluid chamber 13c via the hole 15a. Then, the flow of the viscous fluid acts on the flap portion 51b of the valve 51, and the gap between the flap portion 51b and the valve receiving portion 15e is expanded (the valve 51 is displaced from the closed position to the open position). . As a result, the viscous fluid in the third fluid chamber (load-side fluid chamber) smoothly returns to the second fluid chamber 13c via the reflux hole 15a, so that the piston 15 returns to the original position before load buffering. To do. In the process of this return, the shock absorber 11 buffers the load at a buffering speed according to the flexible characteristic or the like by the throttle adjusting function of the viscous fluid flow rate according to the load according to the flexible characteristic of the flap portion 51b of the valve 51.

  According to the shock absorber according to the third embodiment, the adjustment of the viscous fluid flow rate according to the load according to the flexibility characteristic of the flap portion 51b of the valve 51 can be realized accurately and smoothly.

  FIG. 7 is an enlarged view of a main part of the shock absorber according to the fourth embodiment.

  Differences between the shock absorber according to the first embodiment described above and the shock absorber according to the fourth embodiment are as follows.

  That is, in the shock absorber according to the first embodiment, the valve receiving portion 15e that protrudes in an annular shape is provided at the position opposite to the flap portion 19b of the valve 19 on the anti-load side of the piston 15. In the shock absorber according to the present invention, an annular flat valve receiving portion 61 is provided at a position opposite to the flap portion 19b of the valve 19 on the side opposite to the load on the piston 15, whereby the flap portion 19b and the valve receiving portion 61 are provided. This is different from the first embodiment in that the gap between the first and second embodiments is widened.

  Note that the gap between the flap portion 19b and the valve receiving portion 61 is the same as that of the first embodiment in that the gap portion is opened under a no-load state.

According to the shock absorber according to the fourth embodiment, the adjustment allowance for the viscous fluid flow rate is expanded, so that the range of the buffer capacity for the load can be expanded, and the response capability to the load can be increased.
[Others]
The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist of the invention read from the claims and the entire specification or the technical idea, and the shock absorber accompanying such a change. Is also included in the scope of the technical scope of the present invention.

  That is, for example, in the embodiment of the present invention, the return hole 15a has an orifice function, and the shock absorber 11 is caused to cooperate with the third fluid chamber (load-side fluid chamber) 13d and the return hole (orifice) 15a. However, in the case of adopting a configuration in which the third fluid chamber 13d alone obtains the buffer function, the diameter of the reflux hole 15a may be made sufficiently large.

  In the embodiment of the present invention, the piston rod 17 moves back and forth in accordance with the movement of the object to be controlled without having a return means such as a spring for returning the piston rod 17 retracted in the cylinder 13 to its original state. However, the present invention is not limited to this example, and a return means such as a spring is provided in the cylinder 13, and the piston rod 17 retracted in the cylinder 13 is restored by the action of the return means. You may employ | adopt the structure returned to this state.

  As an example of the configuration of the flap portion 19b of the valve 19, an example is formed in which the base portion 19a is inclined toward the anti-load side direction, and the thickness thereof is gradually reduced from the base portion 19a toward the outer peripheral edge. As described above, the present invention is not limited to this example. The thickness of the flap portion 19b is changed from the base portion 19a toward the outer peripheral edge by changing the strength of each cross section with respect to the flexure, and the degree of flexure is stepwise in each cross section. It is also possible to adopt a configuration in which the load buffering capacity is changed in multiple stages by changing to.

11 Shock absorber 13 Cylinder 13a Bottom wall 13b First fluid chamber 13c Second fluid chamber (anti-load side fluid chamber)
13d Third fluid chamber (load side fluid chamber)
15 piston 15a reflux hole 15b protrusion 15c annular groove 15d chamfered corner 15e valve receiving part 15f fitting hole 17 piston rod 19 valve (Example 1)
19a Base portion 19b Flap portion 19c Fitting through hole 21 Receiving portion 23 Rod guide 25 Flange portion 27 Liquid storage chamber 29 Circulating groove 31 O-ring 33 Recessed portion 35 Seal member 37 Cover body 41 Valve (Example 2)
41a Base 41b Flap part 51 Valve (Example 3)
51a Base 51b Flap part 61 Valve receiving part (Example 4)

Claims (5)

A substantially cylindrical cylinder sealed with a viscous fluid;
A substantially cylindrical piston which is slidably provided in the cylinder and transmits a force from a load;
A load-side fluid chamber and an anti-load-side fluid chamber formed respectively on the load side and the anti-load side of the cylinder across the piston;
A valve having a base portion fixed to the anti-load side of the piston and an annular flap portion integrally provided around the base portion;
The piston is provided with a reflux hole that penetrates the piston and communicates the load-side fluid chamber and the anti-load-side fluid chamber,
An annular valve receiving portion facing the flap portion is provided on the anti-load side of the piston,
A shock absorber in which the flap portion is bent in accordance with a pressure difference between the fluid chambers, and a gap between the flap portion and the valve receiving portion is displaced, so that a flow rate of the viscous fluid flowing through the reflux hole is throttled and adjusted. Because
The valve is formed so that the thickness of the base portion is thicker than the thickness of the flap portion, and the thickness of the flap portion gradually decreases from the base portion toward the outer peripheral edge,
Shock absorber characterized by that. The shock absorber according to claim 1,
Provided on the anti-load side of the piston is a substantially cylindrical protrusion to which the base of the valve is fixed;
A fitting through hole is provided in the base of the valve,
An annular groove in which the fitting through hole fits is provided in the protruding portion,
The valve is adapted for fitting the base portion into the annular groove of the protrusion so that the valve moves integrally with the piston by fitting the through hole for fitting into the annular groove from the tip of the protrusion . Fitted through holes and fixed ,
Shock absorber characterized by that. The shock absorber according to claim 1 or 2,
A plurality of the reflux holes are provided in the piston.
Shock absorber characterized by that. The shock absorber according to any one of claims 1 to 3,
The gap between the flap portion and the valve receiving portion is opened under no load condition,
Shock absorber characterized by that. The shock absorber according to any one of claims 1 to 3,
The gap between the flap part and the valve receiving part is closed under no load condition,
Shock absorber characterized by that.