JP2013155840A - Hydraulic shock absorber, and shock absorbing material - Google Patents

Abstract

An object of the present invention is to provide a hydraulic shock absorber that reduces impact generated when a restricting member that restricts a moving range of a piston rod protruding from a cylinder and an inner end of the cylinder abut against each other and has improved durability. And
A hydraulic shock absorber according to the present invention includes an inner cylinder, a piston, a piston rod, a rebound seat that restricts a movement range of the piston rod, and a ring provided around the piston rod. And a rebound rubber 50 that prevents the rebound sheet 70 and the inner end of the inner cylinder 12 from contacting each other. The rebound rubber 50 has a groove on the outer periphery extending in a direction intersecting with the axial direction of the inner cylinder 12, and the most protruding portion in the axial direction of the inner cylinder 12 is annular, and the inner diameter of this portion is the groove. It is larger than the diameter of the bottom.
[Selection] Figure 1

Description

  The present invention relates to a hydraulic shock absorber and a shock absorber.

A hydraulic shock absorber using a damping force generation device for suspension devices of vehicles such as automobiles, in order to appropriately reduce vibration transmitted from the road surface to the vehicle body during traveling and improve riding comfort and steering stability It has.
For example, the hydraulic shock absorber described in Patent Document 1 is configured as follows. That is, it constitutes a piston sliding chamber filled with oil in the tube, and in this piston sliding chamber, a piston that slides in the bound direction and vice versa against the oil resistance is arranged, The rod that supports the piston is provided with a rebound stopper that moves together in the piston sliding chamber and that abuts against the rod guide at a limit position in the rebound direction of the piston. The rebound stopper is provided in two stages in the piston sliding direction, and a resin ring having higher rigidity than the rebound stopper is interposed between the rebound stopper and the rebound stopper.

JP 11-325159 A

To absorb more shock when the rebound seat hits one end of the cylinder when the piston rod protrudes from the cylinder, change the material of the rebound rubber or combine multiple different materials. Is also possible. However, since the rebound rubber is provided in the oil that can be hot, the selection of the material is greatly restricted. Further, when a plurality of members are combined, the number of parts is increased and the assembly becomes complicated.
It is an object of the present invention to provide a hydraulic shock absorber that reduces the impact that occurs when a restricting member that restricts the range of movement of a piston rod protruding from a cylinder and the inner end of the cylinder abut against each other and that has improved durability. Objective.

For this purpose, the present invention includes a cylinder that contains oil therein, a piston body that divides the inside of the cylinder into two oil chambers, and is slidably disposed within the cylinder, and the piston A piston rod that is fixed to the main body and moves together with the piston main body, passes through one end of the cylinder and protrudes out of the cylinder, a limiting member that restricts a moving range of the piston rod, and provided around the piston rod An annular member, provided between the restriction member and the inner end of the cylinder, and when the piston rod moves in a direction protruding from the cylinder, the restriction member and the inner end of the cylinder A contact prevention member that prevents the contact of the cylinder, and the contact prevention member exists on the outer periphery over a direction intersecting the axial direction of the cylinder. A portion that protrudes most in the axial direction of the cylinder at the end in the axial direction of the cylinder is annular, and the inner diameter of the portion is larger than the diameter of the bottom of the groove It is a hydraulic shock absorber.
Here, it is preferable that the end portion of the contact preventing member has an inclined surface from the portion that protrudes most in the axial direction of the cylinder toward the inner peripheral side.
Further, the portion that protrudes most in the axial direction of the cylinder may form an end face having a predetermined width.
Moreover, the said contact prevention member is good to have the said groove | channel in the symmetrical position on the basis of the center in the axial direction of the said cylinder, and to have the said site | part of the same structure in the said edge part of both sides.
The contact prevention member has a plurality of the grooves on the outer periphery, and the diameter of the portion that protrudes most in the axial direction of the cylinder at the end is at least the annular end of the plurality of grooves. It is good to be larger than the diameter of the bottom in the nearest groove.

  From another point of view, the present invention is an annular member provided around the piston rod in the cylinder of the hydraulic shock absorber, and includes a limiting member that limits the movement range of the piston rod, and an inner end of the cylinder. Is an impact absorbing material that prevents the restriction member and the inner end of the cylinder from coming into contact with each other when the piston rod moves in a direction protruding from the cylinder. A portion that protrudes in the axial direction of the cylinder at the end in the axial direction of the cylinder is annular, and the inner diameter of the portion is the bottom of the groove in the groove. The shock absorber is characterized by being larger than the diameter.

  According to the present invention, there is provided a hydraulic shock absorber that reduces the impact that occurs when the limiting member that limits the movement range of the piston rod protruding from the cylinder and the inner end of the cylinder abut against each other and that has improved durability. be able to.

It is a figure which shows schematic structure of the hydraulic shock absorber which concerns on this Embodiment. It is a figure which shows the flow of the oil at the time of the compression stroke of a hydraulic shock absorber. It is a figure which shows the flow of the oil at the time of the expansion stroke of a hydraulic shock absorber. It is a figure which shows the cross section of a rebound rubber. It is the figure which showed the state in which a rebound rubber receives compressive force. It is the figure which showed the rebound rubber of the comparative example. It is a figure explaining the relationship between the deformation | transformation amount when a rebound rubber of this Embodiment receives a compressive load, and a load with a comparative example. It is a figure explaining a rebound rubber modification.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
<Hydraulic shock absorber 100>
FIG. 1 is a diagram showing a schematic configuration of a hydraulic shock absorber 100 according to the present embodiment. The hydraulic shock absorber 100 according to the present embodiment is a double cylinder type hydraulic shock absorber that constitutes a part of a strut type suspension.
As shown in FIG. 1, the hydraulic shock absorber 100 includes a thin cylindrical outer cylinder 11, a thin cylindrical inner cylinder (an example of a cylinder) 12 accommodated in the outer cylinder 11, and a cylindrical outer cylinder 11. A cylinder 10 having a bottom lid 13 that closes one end of the cylinder in the center line direction (vertical direction in FIG. 1) is provided. Hereinafter, the center line direction of the outer cylinder 11 is simply referred to as “center line direction”.

The hydraulic shock absorber 100 includes a piston (piston body) 41 that is inserted into the inner cylinder 12 so as to be movable in the center line direction, and is disposed along the center line direction and one end in the center line direction ( The piston rod 22 that supports the piston 41 at the lower end in FIG. 1 and the rod guide 25 that is disposed inside the outer cylinder 11 and guides the piston rod 22 are provided. The piston 41 is in contact with the inner periphery of the inner cylinder 12, and a space in which the liquid (oil in the present embodiment) in the inner cylinder 12 is sealed is located closer to one end side in the center line direction than the piston 41. The first oil chamber Y1 and the second oil chamber Y2 on the other end side in the center line direction from the piston 41 are divided.
Further, in the hydraulic shock absorber 100 according to the present embodiment, the reservoir chamber R is formed by the outer periphery of the inner cylinder 12 and the inner periphery of the outer cylinder 11. The interior of the reservoir chamber R is divided into an oil chamber filled with oil and a gas chamber filled with air, inert gas, and the like. As shown in FIG. 1, the first valve device 30 separates the first oil chamber Y1 and the reservoir chamber R by a valve body 31 described later.
The hydraulic shock absorber 100 includes an oil seal 27 that is provided on the side opposite to the piston 41 with respect to the rod guide 25 and prevents leakage of liquid in the cylinder 10 and entry of foreign matter into the cylinder 10.

The hydraulic shock absorber 100 includes a first valve device 30 disposed at one end of the inner cylinder 12 in the center line direction and a second valve disposed at one end of the piston rod 22 in the center line direction. Device 40.
The first valve device 30 includes a valve body 31 that is a cylindrical member having a first oil passage 311 and a second oil passage 312 formed in the center line direction. The first valve device 30 includes a first valve 32 that closes one end of the first oil passage 311 formed in the valve body 31 in the center line direction, and a second oil passage 312 formed in the valve body 31. And a second valve 33 that closes the other end portion in the center line direction.
The second valve device 40 includes the piston 41 described above. Here, the piston 41 has a first oil passage 411 and a second oil passage 412 formed in the center line direction. The second valve device 40 includes a first valve 42 that closes one end of the first oil passage 411 formed in the piston 41 in the center line direction, and a center in the second oil passage 412 formed in the piston 41. And a second valve 43 that closes the other end in the linear direction.

  The hydraulic shock absorber 100 includes a bracket 53 for connection to a wheel knuckle (not shown) to which the hydraulic shock absorber 100 is attached, and the other end portion in the center line direction of the piston rod 22 (the upper end portion in FIG. 1). And an upper spring seat (not shown) that supports the spring (not shown) together with the upper spring seat.

Next, the operation of the hydraulic shock absorber 100 configured as described above will be described.
First, the operation of the hydraulic shock absorber 100 during the compression stroke will be described.
FIG. 2 is a diagram illustrating the flow of oil during the compression stroke of the hydraulic shock absorber 100.
When the piston rod 22 moves to one end side in the center line direction (downward in FIG. 2) with respect to the cylinder 10 as indicated by a white arrow, the pressure in the first oil chamber Y1 is moved by the movement of the piston 41. Rise. Then, the oil in the first oil chamber Y1 opens the second valve 43 that closes the second oil passage 412 of the second valve device 40, and flows into the second oil chamber Y2 above the second valve device 40 ( (See arrow A). The oil flow from the first oil chamber Y1 to the second oil chamber Y2 is throttled by the second valve 43 and the second oil passage 412 to obtain a damping force during the compression stroke of the hydraulic shock absorber 100.
The oil in the first oil chamber Y1 opens the first valve 32 that closes the first oil passage 311 and flows into the reservoir chamber R formed between the inner cylinder 12 and the outer cylinder 11 (see arrow B). ). The oil flow from the first oil chamber Y1 to the reservoir chamber R is throttled by the first valve 32 and the first oil passage 311 to obtain a damping force during the compression stroke of the hydraulic shock absorber 100.

Next, the behavior of the hydraulic shock absorber 100 during the extension stroke will be described.
FIG. 3 is a diagram illustrating the flow of oil during the extension stroke of the hydraulic shock absorber 100.
When the piston rod 22 moves to the other end side in the center line direction (upward in FIG. 3) with respect to the cylinder 10 as indicated by the white arrow, the oil corresponding to the volume is insufficient in the first oil chamber Y1. As a result, negative pressure is obtained. As a result, the oil in the second oil chamber Y2 opens the first valve 42 that closes the first oil passage 411 of the second valve device 40, and flows into the first oil chamber Y1 (see arrow C). The oil flow from the second oil chamber Y2 to the first oil chamber Y1 is throttled by the first valve 42 and the first oil passage 411 of the second valve device 40, and the damping force during the expansion stroke of the hydraulic shock absorber 100 Get.
Further, when the piston rod 22 moves to the other end side in the center line direction with respect to the cylinder 10 (upward in FIG. 3), the oil in the reservoir chamber R becomes the second of the valve body 31 of the first valve device 30. The second valve 33 that closes the oil passage 312 is opened and flows into the first oil chamber Y1 (see arrow D). The oil flow from the reservoir chamber R to the first oil chamber Y1 is throttled by the second valve 33 and the second oil passage 312 of the first valve device 30 to obtain a damping force during the extension stroke of the hydraulic shock absorber 100. .
The hydraulic shock absorber 100 configured as described above absorbs an impact force when the vehicle to which the hydraulic shock absorber 100 is attached travels.

<Rebound rubber 50>
Although not described above, as shown in FIG. 1, the hydraulic shock absorber 100 is a cylindrical member provided on the outer periphery of the piston rod 22, and together with the piston rod 22 inside the inner cylinder 12 filled with oil. A moving rebound rubber 50 is provided. The hydraulic shock absorber 100 is a cylindrical member fixed to the outer periphery of the piston rod 22 by welding, caulking, or the like, and includes a rebound sheet (restricting member) 70 that restricts a range in which the piston rod 22 moves. The rebound rubber 50 is disposed between the rod guide 25 and the rebound sheet 70 in the center line direction. In the illustrated example, the rebound rubber 50 is provided in contact with the rebound seat 70.
Further, the rebound rubber 50 is elastically deformed by being sandwiched between the rebound seat 70 and the rod guide 25 for guiding the piston rod 22 at the maximum stroke of the piston rod 22 in the expansion stroke of the hydraulic shock absorber 100. That is, the rebound rubber 50 prevents the rebound sheet 70 and the rod guide 25 from directly colliding with each other, thereby reducing (absorbing) the impact.

Next, the rebound rubber 50 will be described in detail.
FIG. 4 is a view showing a cross section of the rebound rubber 50. More specifically, FIG. 4 (a) is an enlarged view of the rebound rubber 50 shown in FIG. 1, and FIG. 4 (b) is an enlarged view of the circle in FIG. 4 (a). (C) is the figure seen from the arrow IVc direction in Fig.4 (a), FIG.4 (d) is the figure which showed the state which the rebound rubber 50 receives a load and elastically deforms.

  As shown to Fig.4 (a), the rebound rubber 50 which is an example of a contact prevention member and an impact-absorbing material is provided with the annular groove (groove) 501 in an outer peripheral surface. As shown in FIG. 4B, the annular groove 501 is inclined so that the width decreases from the edge 501a to the bottom 501b. A plurality of the annular grooves 501 are provided at predetermined intervals in the center line direction (axial direction). In the illustrated example, the groove depths of the plurality of annular grooves 501 are the same, but may be different for each annular groove 501.

  Further, the end portions 510 and 520 in the axial direction of the rebound rubber 50 are annular. As shown in FIG. 4B, the annular end portion 510 has an end surface (most protruding portion) 502 that is a portion that protrudes most in the axial direction from the end portion 510. Further, in the illustrated example, the inner diameter side of the end portion 510 of the rebound rubber 50 is chamfered by an inclined surface 503.

Now, the bottom portion 501b (refer to reference numeral S1) in the annular groove 501 is located on the inner peripheral side of the inner peripheral portion 502a (refer to reference numeral S1) where the end surface 502 is the innermost peripheral side and the inclined surface 503 starts.
More specifically, as shown in FIG. 4C, the radius R1 of the bottom portion 501b is smaller than the radius R2 of the inner peripheral portion 502a. Further, the inclined surface 503 is formed at a position where the inclined surface 503 and the annular groove 501 overlap (see the colored portion in FIG. 4C).

  Furthermore, in the axial direction of the rebound rubber 50, the distance from the end face 502 to the groove edge 501a closest to the end face 502 (see S3) is the strength and shape (outer diameter, inner diameter, or end face of the material of the rebound rubber 50. ) And the like. More specifically, this distance (see S <b> 3) can be determined according to the load that deforms the ends 510 and 520 in the axial direction of the rebound rubber 50.

  In addition, although mentioned later for details, as shown to (d-1)-(d-3) of FIG.4 (d), the rebound rubber 50 is loaded by being pinched | interposed by the rod guide 25 and the rebound sheet | seat 70. FIG. When received, in the axial direction of the rebound rubber 50, it is deformed in order from the ends 510 and 520 toward the center. And as shown in FIG.4 (d-1), when the rebound rubber 50 receives a load by being pinched | interposed by the rod guide 25 and the rebound sheet | seat 70, the annular groove 501 nearest to the end surface 502 will collapse. Transforms into

The rebound rubber 50 is made of a material having oil resistance and heat resistance, and is made of, for example, nylon, polyurethane, rubber, polyimide synthetic fiber, or the like.
In the illustrated example, the annular groove 501 has a U-shaped cross section, but may have a trapezoidal shape, a V shape, a semicircular shape, or the like.
Furthermore, in the present embodiment, the arrangement of the end surface 502 of the rebound rubber 50 and the annular grooves 501 does not change even when the upper and lower sides in FIG. Therefore, the rebound rubber 50 is not disposed in the wrong orientation (reverse assembly or incorrect assembly) with respect to the piston rod 22 at the time of manufacturing the hydraulic shock absorber 100 or maintenance work.

  Here, for example, in the rebound rubber 50 having an outer diameter of 23 mm, an inner diameter of 18 mm, and an axial length of 30 mm, when the groove depth from the outer peripheral surface is 1.5 mm (radius R1 is 10 mm), The radius R2 is 10.5 mm. As a result, as shown in FIG. 4C, when the rebound rubber 50 is viewed in the axial direction from the end portion 510 side, the circular groove 501 and the inclined surface 503 are circular in which the radial width is 0.5 mm. It overlaps in the annular region (see the colored part in FIG. 4C).

  More specifically, when the annular groove 501 having a groove width of 2 mm in the axial direction is formed, the distance from the end surface 502 to the nearest annular groove 501 (see S3) is 5 mm. The distance between the centers of the annular grooves 501 is 6 mm.

<Action>
Next, the operation of the rebound rubber 50 configured as described above will be described.
First, as shown in FIG. 1, the rebound rubber 50 is elastically deformed by receiving a load by being sandwiched between the rod guide 25 and the rebound seat 70 during the maximum stroke of the piston rod 22 in the expansion stroke of the hydraulic shock absorber 100.
The rebound rubber 50 reduces the amount of change (acceleration) in the moving speed of the piston rod 22 by elastic deformation, and absorbs the impact during the maximum stroke of the piston rod 22.

  In addition, the rebound rubber 50 suppresses noise generated with this impact (at the time of the maximum stroke). More specifically, the rebound rubber 50 suppresses so-called rebound touch that is initial contact at the time of rebound and abnormal noise due to so-called rebound shock that is an impact when a rebound load is input.

Here, a state where the rebound rubber 50 receives a compressive force will be described with reference to FIG. FIG. 5 is a view showing a state where the rebound rubber 50 receives a compressive force.
First, as shown in FIG. 5A, the rebound rubber 50 starts to be pressed by the rod guide 25 and the rebound sheet 70, and receives a compressive force Fa that is an initial load from the rod guide 25. At this time, there is an annular groove 501 in the direction in which the initial load is applied from the end surface 502 that receives the compressive force Fa (the downward direction in FIG. 5). In other words, there is a region where there is no member of the rebound rubber 50 in the direction in which the initial load is applied from the portion that receives the initial load.

  Since there is a region where there is no member of the rebound rubber 50, the member in the direction of receiving the initial load from the portion receiving the initial load cannot be supported by the stress against compression. From this, when the rebound rubber 50 is pressed, the end portions 510 and 520 are easily bent. In other words, the elastic stress of the rebound rubber 50 when the rebound rubber 50 receives an impact is reduced as compared with the case where there is no region where the rebound rubber 50 member is not present (when the members of the rebound rubber 50 are continuous). It becomes the state.

Here, as a comparative example, as shown in FIG. 5C, the diameter of the inner peripheral portion 502a (see symbol S2) of the annular end surface 502 is the diameter of the bottom portion 501b (see symbol S1) in the annular groove 501. Consider a smaller case.
In this case, there is a continuous portion S4 in which the members of the rebound rubber 50 are continuous in the direction in which the initial load is applied from the end face 502 that receives the initial load. And this continuous part S4 supports an initial load with the stress with respect to the compression to the continuous part S4.

  Therefore, in the example shown in FIG. 5C, stress for the deflection of the end portions 510 and 520 and stress for compression of the continuous portion S4 are generated with respect to the compression force Fb that is the initial load. As a result, as compared with the embodiment shown in FIG. 5A, the rebound rubber 50 imparts a greater resistance force to the piston rod 22 at the moment of impact.

Here, the operation of the rebound rubber 50 will be further described with reference to FIGS. 4, 6, and 7.
FIG. 6 is a view showing the rebound rubbers 200, 230, and 260 of the comparative example. FIG. 7 is a diagram illustrating the relationship between the amount of deformation and the load when the rebound rubber 50 according to the present embodiment receives a compressive load, together with a comparative example.

  Unlike the present embodiment, the rebound rubber 200 which is a comparative example shown in FIG. 6A has a protrusion 201 protruding in the axial direction from the annular end portions 210 and 220 in the axial direction. The protrusion 201 is not formed in a continuous annular shape around the shaft but protrudes partially.

  The rebound rubber 230 which is a comparative example shown in FIG. 6B has a larger volume than the rebound rubber 200 shown in FIG. A plurality of annular grooves 231 are provided on the outer peripheral surface of the rebound rubber 230, and the outer peripheral surface has a so-called bellows shape. The rebound rubber 230 is different from the present embodiment in that the inner diameter of the end surface is smaller than the diameter of the bottom of the annular groove 231. Further, unlike the rebound rubber 200 shown in FIG. 6A, the rebound rubber 230 does not have protrusions protruding in the axial direction at the annular end portions 240 and 250 in the axial direction.

  The rebound rubber 260 which is a comparative example shown in FIG. 6C has a larger volume than the rebound rubber 200 shown in FIG. Unlike the present embodiment, the rebound rubber 260 has a protrusion 261 that protrudes in the axial direction from the annular end portions 270 and 280 in the axial direction. The protrusion 261 is not formed in an annular shape that continues around the shaft, but protrudes partially. In addition, the outer peripheral surface of the rebound rubber 260 does not have an annular groove.

  FIG. 7A is a diagram showing the entire relationship between the deformation amount and the load, and FIG. 7B is an enlarged view of the ellipse in FIG. In FIGS. 7A and 7B, the horizontal axis indicates the amount of deformation, and the vertical axis indicates the load. Further, the solid line in FIGS. 7A and 7B shows the rebound rubber 50 of the present embodiment, the broken line shows the rebound rubber 200 (shape a) shown in FIG. 6A, and the two-dot chain line shows the figure. The rebound rubber 230 (shape b) shown in FIG. 6 (b) is shown, and the one-dot chain line shows the rebound rubber 260 (shape c) shown in FIG. 6 (c).

  The rebound rubber 50 according to the present embodiment applies a small resistance force to the piston rod 22 at the moment of receiving an impact, and suppresses a large change in the moving speed of the piston rod 22. In other words, when the rebound rubber 50 receives a load and starts to deform, the initial impact that is an impact applied to the rod guide 25 and the rebound sheet 70 is reduced (relaxed).

  Further, in the rebound rubber 50 of the present embodiment, as the load increases, the deformation amount of the rebound rubber 50 with respect to the load decreases (see FIG. 7A). This prevents the rebound sheet 70 and the rod guide 25 from directly colliding even when the rebound rubber 50 receives a large load.

  Further, in the rebound rubber 50, the annular groove 501 is crushed as the load increases (see FIG. 4D-2), and the deformation amount of the rebound rubber 50 with respect to the load is further reduced. In addition, the rebound rubber 50 imparts a greater resistance force to the piston rod 22 when the annular groove 501 is crushed, and decelerates the piston rod 22. In addition, after the annular groove 501 is completely crushed (see FIG. 4D-3), the deformation amount of the rebound rubber 50 with respect to the load becomes approximately the same as that of the rebound rubber 50 without the annular groove 501.

Next, the rebound rubber 50 of this embodiment will be described in comparison with the rebound rubbers 200, 230, and 260 shown in FIGS.
In the rebound rubber 200 shown in FIG. 6A, stress is concentrated on the protrusion 201, although the area around the protrusion 201 is reduced due to the deformation of the protrusion 201 when an initial load is applied. Therefore, the protrusion 201 is easily damaged.

  On the other hand, in the rebound rubber 50 of the present embodiment, the axial end surface 502, which is a portion that receives the initial load, is annular, and stress is suppressed from being concentrated on a part of the annular shape. Furthermore, since the inclined surface 503 is formed on the inner diameter side of the end portion 510 of the rebound rubber 50, the concentration of stress on the inner diameter side is also suppressed. Therefore, the rebound rubber 50 of the present embodiment has higher durability than the rebound rubber 200 shown in FIG.

Moreover, since the rebound rubber 50 of this Embodiment has a larger volume than the rebound rubber 200 shown to Fig.6 (a), it can relieve a shock, even when there exists a big impact (input) (FIG. 7). (See (a)). That is, the rebound rubber 50 can absorb larger energy.
Note that the rebound rubber 50 of the present embodiment is easier to create a prototype by cutting compared to the rebound rubber 200 shown in FIG. 6A, and the process of determining specifications while creating a prototype is short-term. Can be

Compared with the rebound rubber 230 shown in FIG. 6B, the rebound rubber 50 according to the present embodiment can reduce the initial area by bending the end portions 510 and 520 when receiving the initial load. (Refer FIG.7 (b)).
Further, the rebound rubber 50 according to the present embodiment can receive the initial load in a distributed manner because the end face 502 in the axial direction is annular, as compared with the rebound rubber 260 shown in FIG. Is expensive.

<Modification>
Next, a modified example of the rebound rubber 50 will be described.
FIG. 8 is a view for explaining a modified example of the rebound rubber 50.

In the above description, it has been described that the inner diameter sides of the end portions 510 and 520 in the axial direction of the rebound rubber 50 are chamfered by the inclined surface 503.
However, if the inner diameter of the portion that protrudes most in the axial direction from the annular end portions 510 and 520 is larger than the diameter of the bottom portion 501b in the annular groove 501 (see S1 in FIG. 4B), the end The shape on the inner diameter side of the portion 51 is not limited. For example, as shown to Fig.8 (a), the structure by which the level | step difference 505 is formed in the internal diameter side of the edge part 510 in the axial direction of the rebound rubber 50 may be sufficient.

  Further, if the inner diameter of the portion that protrudes most in the axial direction from the annular end portion 510 is larger than the diameter of the bottom portion 501b (see reference numeral S1) in the annular groove 501, the outer diameter side than the most protruding portion. The shape is not limited. For example, as shown in FIG. 8B, the outer diameter side of the end portion 510 in the axial direction of the rebound rubber 50 may be chamfered by a surface 507.

  Further, if the inner diameter of the portion that protrudes most in the axial direction from the annular end portion 510 is larger than the diameter of the bottom portion 501b (see reference numeral S1) in the annular groove 501, this protruding portion is the end face 502. There is no need. For example, as shown in FIG. 8C, the protruding portion may be a top portion 513 of a portion protruding in the axial direction from the annular end portion 510.

  Furthermore, the portion most protruding in the axial direction from the annular end portion 510 is not limited to being formed by immersing the other portion of the annular end portion 510. For example, as shown in FIG. 8D, a configuration may be adopted in which an annular member 515 formed as a separate member is fixed to the annular end portion 510.

DESCRIPTION OF SYMBOLS 10 ... Cylinder, 11 ... Outer cylinder, 12 ... Inner cylinder, 22 ... Piston rod, 25 ... Rod guide, 50 ... Rebound rubber, 70 ... Rebound seat, 100 ... Hydraulic shock absorber, 501 ... Annular groove, 502 ... End face, 503 ... Inclined surface, 510, 520 ... End

Claims (6)

A cylinder for containing oil inside,
A piston body that divides the inside of the cylinder into two oil chambers and is slidably arranged inside the cylinder;
A piston rod fixed to the piston body and moving with the piston body, penetrating one end of the cylinder and projecting out of the cylinder;
A limiting member for limiting the moving range of the piston rod;
An annular member provided around the piston rod, provided between the restriction member and the inner end of the cylinder, and when the piston rod moves in a direction protruding from the cylinder, A contact preventing member for preventing the inner end of the cylinder from contacting,
The contact prevention member has a groove on the outer periphery over a direction intersecting with the axial direction of the cylinder, and a portion that protrudes most in the axial direction of the cylinder at the end in the axial direction of the cylinder is annular, and A hydraulic shock absorber characterized in that the inner diameter of the part is larger than the diameter of the bottom of the groove.   2. The hydraulic shock absorber according to claim 1, wherein the end portion of the contact prevention member has an inclined surface toward an inner peripheral side from the portion that protrudes most in an axial direction of the cylinder.   The hydraulic shock absorber according to claim 1 or 2, wherein the portion that protrudes most in the axial direction of the cylinder forms an end face having a predetermined width.   4. The contact prevention member according to claim 1, wherein the contact prevention member has the groove at a symmetrical position with respect to a center in the axial direction of the cylinder, and has the same portion at the end portions on both sides. The hydraulic shock absorber according to any one of claims.   The contact preventing member has a plurality of the grooves on the outer periphery, and the diameter of the portion that protrudes most in the axial direction of the cylinder at the end is at least closest to the annular end of the plurality of grooves. The hydraulic shock absorber according to any one of claims 1 to 4, wherein the hydraulic shock absorber is larger than a diameter of the bottom portion in the groove. An annular member provided around the piston rod in the cylinder of the hydraulic shock absorber, provided between a limiting member that restricts the movement range of the piston rod and the inner end of the cylinder, and the piston rod is An impact absorbing material that prevents the restriction member and the inner end of the cylinder from coming into contact when moving in a direction protruding from the cylinder,
The outer periphery has a groove that extends in a direction that intersects with the axial direction of the cylinder, the portion that protrudes most in the axial direction of the cylinder at the end in the axial direction of the cylinder is annular, and the inner diameter of the portion is A shock absorber characterized by being larger than the diameter of the bottom of the groove.

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