JP2008128479A - Bound stopper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bound stopper advantageously enhanced in durability to repeated load. <P>SOLUTION: A recessed groove 32 having a rectangular sectional shape is formed in the outer circumferential surface of an axially intermediate part of a stopper body 12 which is inserted onto and disposed on a piston rod 46 of a shock absorber 44, and a rigid constraint ring 14 having a rectangular axial sectional shape is fitted into the recessed groove 14. A currant part 32 extending in the circumferential direction is provided at a bottom corner part of the recessed groove 18 located on the side closer to a cylinder 50 of the shock absorber 44 to form a free surface composed of the inner surface of the currant part 32 which is non-contact with the inner circumferential angle part of the constraint ring 14 located in a position corresponding to the bottom corner part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bound stopper, and more particularly, to an improved structure of a bound stopper that is arranged on a piston rod of a shock absorber so as to elastically limit an operating stroke of the shock absorber.

  Conventionally, a shock absorber constituting a vehicle suspension has been provided with a cylindrical bounce stopper formed by an elastic body such as rubber or urethane foam, which is externally attached to a piston rod. The shock absorber is actuated by compressing and deforming the bound stopper in the axial direction between the shock absorber cylinder and the vehicle body side or wheel side member to which the shock absorber piston rod is attached. The stroke is elastically limited.

  In addition, as a kind of such a bound stopper, it has a cylindrical stopper body formed of an elastic body, which is disposed on the piston rod of the shock absorber, and an outer peripheral surface of an intermediate portion in the axial direction of the stopper body. In addition, a structure in which an annular concave groove extending in the circumferential direction is formed and a rigid constraining ring is inserted into the concave groove is generally known (for example, see Patent Document 1 below). .

  According to the bound stopper having such a structure, when a relatively small load is input, a soft spring characteristic is obtained based on elastic deformation of a portion of the stopper body located on the cylinder side with respect to the portion where the restraining ring is mounted. On the other hand, when a large load is input, deformation of the stopper main body in the radial direction at the mounting portion of the restraining ring is restricted, while the main portion of the stopper main body is opposite to the mounting side of the restraining ring. A relatively hard spring characteristic can be obtained by compressing and deforming the portion located in the non-linear spring characteristic that can achieve both good riding comfort and steering stability of the vehicle, It can be used advantageously. Moreover, since the deformation of the stopper body in the radially outward direction is restricted by the restraining ring, not only interference with other members such as a dust cover located around the stopper body is prevented in advance. Excessive deformation in the axial direction of the stopper body is also prevented, so that the operating stroke of the shock absorber can be more reliably and advantageously limited.

  However, in such a conventional bound stopper, both the restraining ring and the groove have a rectangular cross-sectional shape, and the restraining ring has its inner peripheral surface and both end surfaces in the axial direction connected to the bottom surface of the groove. Since the stopper body is compressed and deformed by a load input, it is in contact with the inner peripheral corner (edge) of the restraining ring. Then, the bottom corners of the concave grooves of the stopper main body that are in contact therewith are strongly pressed, which may cause cracks or damage to the bottom corners.

  Under such circumstances, Patent Document 2 below discloses that the bottom corner of the concave groove having a rectangular cross section is obtained by cutting off at least one of the two inner peripheral corners of the restraining ring having a rectangular cross sectional shape. A bound stopper in which a space is formed between the two parts has been proposed. According to the bound stopper having such a structure, when a load is input, the stopper main body is compressed and deformed so as to fill a space formed between the restraining ring and the concave groove. It is avoided that the bottom corner is in press contact with the inner peripheral corner of the restraining ring, or the pressing force during such pressing contact is advantageously alleviated, and the bottom corner of the concave groove of the stopper body It is intended to prevent cracks and damage from occurring.

  However, when the present inventors conducted a repeated load test in which a constant load was repeatedly applied to the bound stopper having such a structure, among the bottom corners of the concave groove of the stopper body, in particular, shock It has been found that the durability against repeated load at the bottom corner positioned on the cylinder side of the absorber is inferior to other portions of the stopper body.

  Such a partial decrease in durability of the stopper body is considered to be due to the following reason. That is, as shown in FIG. 6, the stopper main body 102 of the bound stopper 100 is extrapolated to the piston rod 106 of the shock absorber 104, and the bound stopper 100 is attached to the shock absorber 104 under the state where the bound stopper 100 is assembled to the shock absorber 104. When the load is input and the stopper main body 102 is compressed and deformed, the two bottom corners 112a and 112b of the concave groove 108 of the stopper main body 102 into which the restraining ring 107 is inserted are placed on the cylinder 110 side of the shock absorber 104. With respect to the bottom corner 112a to be positioned, as shown by an arrow: A, a tensile force to one side in the axial direction opposite to the cylinder 110 side, and a radially outward direction as shown by an arrow: A. Tensile force is applied simultaneously, and at this time, stress concentrates on the bottom corner 112a. Large distortion occurs. Such stress concentration and generation of large strain at the bottom corner 112a are repeatedly caused each time a load is input, so that the load on the bottom corner 112a of the recess 108 in the stopper body 12 can be reduced. It is presumed that the durability will be lower than other parts.

Japanese Utility Model Publication No. 61-203807 JP 2005-282735 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is a rectangular cross-section formed on the outer peripheral surface of a cylindrical stopper body made of an elastic body. In the bound stopper in which a constraining ring having a rectangular cross section is inserted into the concave groove, durability of a repeated load can be improved more advantageously.

  In the present invention, in order to solve such a problem, the gist of the present invention is to have a cylindrical stopper body formed of an elastic body that is externally arranged on the piston rod of the shock absorber. An annular concave groove extending in the circumferential direction with a rectangular cross-sectional shape is formed on the outer peripheral surface of the axially middle portion of the stopper body, while a rigid restraining ring having a rectangular cross-sectional shape in the axial direction The shock absorber is inserted into the groove, and the inner peripheral surface of the constraining ring and both end surfaces in the axial direction are arranged so as to contact the bottom surface and both side surfaces of the groove, respectively. In the bound stopper configured to be elastically limited, a corner portion extending in a circumferential direction is provided at a bottom corner portion of the concave groove located on the cylinder side of the shock absorber, and the bottom corner portion Is the inner peripheral side corner portion of the constraining ring corresponding position and non-contact, in bound stopper, characterized in that the formation of the free surface consisting of the inner surface of the hollow portion.

  According to one of the preferred embodiments of the bound stopper according to the present invention, the straight portion is formed so as to be recessed inward in the radial direction.

  Further, according to one of the other preferable aspects of the bound stopper according to the present invention, the straight portion has a groove that is located on the cylinder side of the shock absorber with respect to the bottom corner of the groove. It is formed to extend continuously around the circumference.

  Furthermore, according to one of the desirable aspects of the bound stopper according to the present invention, the bottom surface of the straight portion has a U-shaped curved surface configuration.

  Still further, according to one of the other preferred embodiments of the bound stopper according to the present invention, the straight portion is communicated with at least one of the restraining ring and the stopper main body, and the straight portion An air passage that allows air to enter and exit between the inside and the outside of the housing is provided.

  In other words, the bound stopper according to the present invention has a structure in which a rigid restraining ring is inserted in the concave groove of the stopper main body, so that a soft spring characteristic is exhibited when a small load is input. On the other hand, a sufficiently hard spring characteristic can be exhibited when a large load is input.

  In such a bound stopper, in particular, the bottom corner of the concave groove of the stopper body has a free surface on the inner surface at the bottom corner positioned on the cylinder side when assembled to the shock absorber. Is provided. Therefore, the inner peripheral side corners of the constraining ring, which are positioned corresponding to the bottom corners of the concave grooves, are simply cut off, and so on, so that the gap between the bottom corners of the concave grooves and the inner peripheral side corners of the constraining rings Compared to the case where only a space is formed, the free length of the bottom corner that is elastically deformed at the time of load input, in particular, one axial direction opposite to the cylinder side due to compressive deformation of the stopper body due to load input The free length of the bottom corner on the cylinder side that is elastically deformed when a lateral pulling force and a radially outward pulling force are applied can be effectively increased. As a result, the stress concentration at the bottom corner on the cylinder side and the occurrence of a large strain at the time of load input can be advantageously suppressed, and the stress concentration at the bottom corner and the occurrence of a large strain can be suppressed. Each time is entered, it is not repeatedly triggered.

  Therefore, in the bound stopper according to the present invention as described above, a non-linear spring characteristic that can achieve both good riding comfort and steering stability of the vehicle is advantageously ensured, and durability against repeated loads is ensured. In the bottom corner of the concave groove in the stopper body, it is possible to advantageously eliminate the local lowering at the bottom corner positioned on the cylinder side in the assembled state to the shock absorber. The durability against repeated loads can be increased very advantageously.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 shows a bound stopper 10 according to the present invention in a longitudinal section. As is clear from this figure, the bound stopper 10 includes a stopper main body 12 having a substantially stepped cylindrical shape and a restraining ring 14 that is externally inserted into the stopper main body 12. Hereinafter, for convenience, the upper side and the lower side in FIG. 1 will be referred to as the upper side and the lower side of the bound stopper 10.

  More specifically, the stopper main body 12 is made of an elastic body. As the elastic body for providing the stopper main body 12, known elastic bodies such as various rubbers and urethanes are used. In the present embodiment, foamed urethane rubber is used, so that the stopper main body 12 is soft. Spring characteristics are exhibited.

  Further, the stopper body 12 as a whole has a stepped cylindrical shape whose outer diameter increases stepwise toward the upper part, and the inner hole is an insertion hole 16 extending in the axial direction with a constant diameter. Yes. And while the upper side part of such a stopper main body 12 is made into the upper cylindrical part 20 which exhibits a thick cylindrical shape, the lower side part is made into the lower cylindrical part 22 which exhibits a thin cylindrical shape, The intermediate portion is an intermediate cylindrical portion 24 having a cylindrical shape of medium thickness.

  Moreover, in the lower cylindrical part 22 of the stopper main body 12, the lower part from the axial direction intermediate part of an outer peripheral surface is made into the taper surface which becomes small diameter gradually as it goes below, Furthermore, the axis | shaft of an inner peripheral surface A circumferential groove 26 having a substantially V-shaped cross section is provided in the middle portion in the direction. As a result, the lower cylindrical portion 22 of the lower cylindrical portion 22 is a tapered cylindrical portion 28 in which both the thickness and the outer diameter gradually decrease toward the lower end.

  Further, in the lower part of the outer peripheral surface of the intermediate cylindrical portion 24 in the stopper main body 12, as shown in the enlarged partial views of FIGS. 1 and 2, a concave groove 18 having a substantially rectangular cross-sectional shape is provided. It is formed with an annular shape extending continuously in the circumferential direction. Further, in the concave groove 18, the upper bottom corner portion 30 a located on the upper side of the intermediate cylindrical portion 24 among the bottom corner portions 30 a and 30 b located on both sides in the width direction (vertical direction) is angular. It is formed as an R surface that draws a gentle curved surface with no part.

  Here, in particular, the straight portion 32 is formed with respect to the lower bottom corner portion 30b of the concave groove 18 located on the lower side of the intermediate cylindrical portion 24. The straight portion 32 has a concave groove shape continuously extending in the circumferential direction over the entire circumference of the intermediate cylindrical portion 24. Further, it is recessed inward in the radial direction of the intermediate cylindrical portion 24 of the stopper body 12, and is opened outward in the radial direction at the bottom of the concave groove 18. In the tick portion 32, the bottom surface 34 made of a curved surface having a semicircular or substantially U-shaped cross section, the upper side surface 36 made of a gentle convex curved surface, and the lower side of the groove 18. It has the lower side surface 38 which consists of a flat surface extended horizontally following the located side surface.

  On the other hand, the constraining ring 14 that is externally inserted into the stopper body 12 is formed using a material having rigidity such as metal or resin. The axial cross section has a substantially rectangular shape, and the inner diameter and thickness thereof are dimensions corresponding to the inner diameter and width of the concave groove 18, and the outer diameter is more predetermined than the outer diameter of the concave groove 18. Only the size of is increased. Further, in the restraining ring 14, the angular portions of the four corner portions 40 a to 40 d are cut off, and each of the corner portions 40 forms a gentle curved surface, particularly the upper side of the concave groove 18. R surfaces corresponding to the R surfaces of the corners 30a are formed.

  Such a restraining ring 14 is inserted into the concave groove 18 of the stopper main body 12 so as to be extrapolated to the intermediate cylindrical portion 24 of the stopper main body 12. In such a state, both the axial end surfaces and the inner peripheral surface of the restraining ring 14 are brought into contact with or in contact with the two side surfaces and the bottom surface of the concave groove 18 to be locked. Yes. As a result, the restraining ring 14 can be prevented from easily detaching from the intermediate cylindrical portion 24 of the stopper main body 12 and can be freely expanded outward in the radial direction accompanying the compression deformation of the intermediate cylindrical portion 24. The structure is such that the deformation is regulated.

  In addition, here, among the four corners 40a to 40d that are the R surfaces of the restraining ring 14, the upper inner peripheral corner 40a located at the upper portion on the inner peripheral side and the corresponding R surface are used. The upper bottom corner portion 30a of the groove 18 is brought into contact with each other. On the other hand, the lower inner peripheral corner portion 40b located at the lower portion on the inner peripheral side is not in contact with the lower bottom corner portion 30b of the concave groove 18 by the straight portion 32 provided there.

  Thus, in the present embodiment, the bottom surface 34 and the upper and lower side surfaces 36, 38 of the straight portion 32 are free surfaces that are not in contact with the lower inner peripheral corner portion 40b of the restraining ring 14. Yes. As a result, the bottom bottom corner 30b of the bottom groove 30b that is elastically deformed along with the compressive deformation of the stopper main body 12 by load input under the assembled condition of the bound stopper 10 to the shock absorber 44 as will be described later. The free length is long enough. Further, between the lower bottom corner portion 30b of the concave groove 18 and the lower inner peripheral corner portion 40b of the restraining ring 14, the inner surface of the straight portion 32 and the R surface of the lower inner peripheral corner portion 40b. A cavity 42 enclosed and closed from the outside is formed so as to continuously extend in the circumferential direction.

  Thus, in the bound stopper 10 having such a structure, for example, as shown in FIG. 3, the stopper main body 12 is arranged on the piston rod 46 of the shock absorber 44 in the insertion hole 16. ing. Further, under such an arrangement state, the stopper main body 12 is press-fitted in the upper cylindrical portion 20 inside a mounting plate 49 having a U-shaped cross section provided in the suspension insulator 48 that supports the piston rod 46 on the vehicle body side in a vibration-proof manner. Thus, the suspension insulator 48 is attached. Thus, the bound stopper 10 is disposed between the cylinder 50 of the shock absorber 44 and the suspension insulator 48 so as to be movable up and down integrally with the piston rod 46.

  Thus, in the bound stopper 10, as shown in FIG. 4, the suspension insulator 48 and the absorber plate 52 on the upper surface of the cylinder 50, when the shock absorber 44 is contracted by a load input (when the piston rod 46 is retracted). Are elastically deformed in the axial direction between them, and the operating stroke of the shock absorber 44 is elastically limited. When a small load is input (when the operating stroke of the shock absorber 44 is small), the thinner tapered cylindrical portion 28 composed of the lower portion of the thin lower cylindrical portion 22 in the stopper body 12 is mainly sheared. As the load gradually increases (the operation stroke of the shock absorber 44 gradually increases), the entire lower cylindrical portion 22 is crushed in the axial direction and compressed and deformed, and the intermediate cylindrical portion 24 is deformed. The upper cylindrical portion 20 is also compressed and deformed. At this time, the deformation of the intermediate cylindrical portion 24 in the radially outward direction is restricted by the restraining ring 14.

  Thereby, in the bound stopper 10 of the present embodiment, a soft spring characteristic is exhibited at the time of inputting a small load, and a spring characteristic that becomes sharply harder as the input load increases is more effectively exhibited. As a result, non-linear spring characteristics are exhibited as a whole bound stopper 10, and good vehicle riding comfort and steering stability can be achieved at a high level.

  Here, as shown in FIG. 4, when a heavy load is input, the lower cylindrical portion 22 and the intermediate cylindrical portion 24 of the stopper main body 12 are straight portions provided in the lower bottom corner portion 30 b of the groove 18. 32 is compressed and deformed so as to fill a void 42 surrounded by the inner surface of 32 and the R surface of the lower inner peripheral corner 40b of the constraining ring 14, and thereby the lower bottom corner 30b of the groove 18 is formed. However, the pressing force at the time can be effectively relieved even if it is prevented from being brought into press contact with the lower inner peripheral corner portion 40b of the restraining ring 14, or even if it is brought into press contact. It has become.

  Moreover, in the present embodiment, in particular, the inner surface (bottom surface 34 and both side surfaces 36, 38) of the straight portion 32 is a free surface, and the lower bottom corner of the groove 18 in which the straight portion 32 is formed. The free length of the part 30b is made sufficiently long. Therefore, the lower cylindrical portion 22 that gives the lower side surface 38 of the lower bottom corner portion 30b due to the compressive deformation of the lower cylindrical portion 22 and the intermediate cylindrical portion 24 of the stopper main body 12 due to load input is radially outward. When an upward tensile force is applied to the intermediate cylindrical portion 24 portion that provides the upper side surface 36 and the bottom surface 34 of the lower bottom corner portion 30b, In the bottom corner 30b, it is possible to effectively suppress the stress concentration and the great distortion. Therefore, every time a load is input, stress concentration and generation of large strain at the lower bottom corner 30b are not repeatedly caused.

  Therefore, in the bound stopper 10 according to the present embodiment as described above, the possibility that a crack or the like is generated in the lower bottom corner 30b of the concave groove 18 in the stopper body 12 due to repeated input of a large load is effectively eliminated. As a result, the durability against repeated loads can be increased very advantageously.

  In the bound stopper 10, the upper bottom corner portion 30 a of the groove 18 and the upper inner peripheral corner portion 40 a of the constraining ring 14 are brought into contact with each other on the R surfaces that are gentle curved surfaces corresponding to each other. When the intermediate cylindrical portion 24 is compressed and deformed by load input, the upper bottom corner portion 30a of the concave groove 18 is pressed against the upper inner peripheral corner portion 40a of the restraining ring 14, and the upper bottom corner portion 30a is pressed against the upper bottom corner portion 30a. The occurrence of cracks and damage can also be effectively eliminated or suppressed. This also makes it possible to improve the durability against repeated loads even more effectively.

  Further, in the present embodiment, the straight portion 32 is formed so as to be recessed radially inward and open radially outward at the bottom of the groove 18. Unlike the case where the lower side surface of the groove 18 is formed so as to open upward, a portion that gives the side surface of the straight portion 32 when the stopper body 12 is manufactured by a general-purpose technique such as injection molding. Such an undercut can be advantageously avoided and the manufacture is facilitated. In addition, when the stopper main body 12 is formed of a foamable elastic body, a molding defect may occur due to the confinement of excess air bubbles in the portion to which the side surface of the straight portion 32 is provided at the time of manufacture. This can also be prevented beforehand.

  Furthermore, in the bound stopper 10, the straight portion 32 is formed with a groove shape extending continuously in the circumferential direction over the entire circumference of the lower bottom corner portion 30 b of the groove 18. Therefore, the occurrence of cracks and the like in the lower bottom corner 30b can be reliably suppressed over the entire circumference, and thereby the durability against the input load as described above is uniform in the circumferential direction of the bound stopper 10. And it can be exhibited stably.

  In the present embodiment, the bottom surface 34 of the straight portion 32 is formed of a curved surface having a semicircular or U-shaped cross section, and thus is formed on the inner surface including the bottom surface 34 of the straight portion 32. The length of the free surface, that is, the free length of the lower bottom corner portion 30b of the groove 18 can be made even more advantageously longer, whereby the lower bottom corner portion 30b and thus the entire bound stopper 10 can be made. The durability against the input load can be improved more effectively.

  Further, in the bound stopper 10, the circumferential space 42 formed between the lower inner peripheral corner 40 b of the restraining ring 14 and the lower bottom corner 30 b of the groove 18 is closed from the outside. Therefore, the foreign matter from the outside is advantageously prevented from entering the space 42, and the function of the stopper body 10 as the accommodating space of the compression deformed portion is advantageously maintained. obtain. In particular, the bound stopper 10 is always near the tire since it is used by being externally attached to the piston rod 46 of the shock absorber 44. Therefore, foreign matters such as mud and dust from the ground are easily attached, and This is because, when the space is filled by the adhesion, the characteristics cannot be effectively exhibited.

  As mentioned above, although one typical embodiment of the present invention has been described in detail, it is merely an example, and the present invention is interpreted in a limited manner by a specific description in such an embodiment. It should be understood that this is not the case.

  For example, the straight portion 32 is provided intermittently in the circumferential direction or only in a part of the circumferential direction without being continuous over the entire circumference of the lower bottom corner portion 30b of the groove 18. May be.

  Further, the shape of the straight portion 32 is not limited to the shape in which the bottom surface 34 is an arc shape or a U-shaped curved surface, and for example, a shape having a V-shaped or polygonal cross section. There is no problem even if it is done.

  Furthermore, in the above-described embodiment, the tick portion 32 is provided so as to be recessed inward in the radial direction and open at the bottom surface of the groove 18. However, the tick portion 32 is depressed downward, It can also be formed so as to open upward on the lower side surface of the groove 18 or open across the lower side surface and the bottom surface of the groove 18.

  In the above embodiment, the void 42 formed inside the straight portion 32 is formed as a space closed from the outside. For example, as shown in FIG. A groove portion extending in the radial direction is provided at one or a plurality of locations on the circumference of the end face so as to communicate the space 42 to the outside, and in this space 42 (inside the straight portion 32) It is also possible to form an air passage 54 that allows air to enter and exit from the outside. According to such a structure, when the stopper body 12 is compressed and deformed so as to fill the space 42 by load input, the air in the space 42 is smoothly discharged to the outside through the air passage 54. As a result, it is possible to effectively prevent abnormal noise from being generated when air is discharged from the space 42.

  Furthermore, in the said embodiment, although the four corner | angular parts 40a-d of the constraining ring 14 were made into the R surface which consists of gentle curved surfaces, these each corner | angular part 40 is made into the flat cut surface (C surface). Even if it has an angular shape with no R or C surface, there is no problem.

  Furthermore, the specific shape of the stopper main body 12 is not particularly limited to the illustrated one, and for example, only the lower cylindrical portion 22 or the entire stopper main body 12 is formed in a bellows shape, or such Of course, a straight cylindrical body having no bellows-like portion is also possible.

  In addition, although not listed one by one, the present invention can be implemented in a mode with various changes, modifications, improvements, and the like based on the knowledge of those skilled in the art. It goes without saying that any one of them falls within the scope of the present invention without departing from the spirit of the invention.

It is a longitudinal section explanatory view showing one embodiment of the bound stopper which has the structure according to the present invention. It is the elements on larger scale in FIG. It is a longitudinal cross-sectional explanatory drawing which shows an example of the state which assembled | attached the bound stopper shown by FIG. 1 to the shock absorber. It is a longitudinal cross-sectional explanatory drawing which shows the compressed state of the bound stopper shown by FIG. It is a figure corresponding to FIG. 2 which shows another embodiment of the bound stopper which has a structure according to this invention. It is a fragmentary longitudinal cross-section explanatory drawing which shows the conventional bound stopper in the state assembled | attached to the shock absorber and compressed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Anti-vibration device 12 Stopper main body 14 Restraint ring 18 Concave groove 30 Bottom corner part 32 Straight part 40 Corner part 42 Space

Claims (5)

A cylindrical stopper body formed of an elastic body, which is placed on the piston rod of the shock absorber, has an annular shape extending in the circumferential direction with a rectangular cross-sectional shape on the outer peripheral surface of the axially intermediate portion of the stopper body And a rigid constraining ring having a rectangular cross section in the axial direction is fitted into the concave groove, and the inner peripheral surface of the constraining ring and both end surfaces in the axial direction are In the bound stopper which is arranged so as to be in contact with the bottom surface and both side surfaces of the groove, respectively, and is configured to elastically limit the operation stroke of the shock absorber.
A corner portion extending in the circumferential direction is provided at the bottom corner portion of the concave groove located on the cylinder side of the shock absorber so as not to be in contact with the inner peripheral corner portion of the restraining ring positioned corresponding to the bottom corner portion. In addition, a bounce stopper characterized in that a free surface comprising the inner surface of the straight portion is formed.   The bound stopper according to claim 1, wherein the straight portion is formed to be recessed inward in the radial direction.   The said straight part is formed so that it may extend so that it may continue to the perimeter of this concave groove with respect to the bottom corner part of the said concave groove located in the cylinder side of the said shock absorber. The bound stopper described.   The bound stopper according to any one of claims 1 to 3, wherein a bottom surface of the straight portion has a U-shaped curved surface form. At least one of the restraining ring and the stopper main body is provided with an air passage that allows the straight portion to communicate with the outside so that air can enter and exit between the inside and the outside of the straight portion. The bound stopper according to any one of claims 1 to 4.

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