Shock absorber

Abstract

This shock absorber (D) is provided with: a cylinder (1); the piston rod (2) can be inserted into the air cylinder (1) in an axial moving manner; a piston (3) which is connected to the piston rod (2), is inserted into the cylinder (1) so as to be axially movable, and divides the inside of the cylinder (1) into an extension-side chamber (R1) and a compression-side chamber (R2); an auxiliary cylinder (4) housed in a compression-side chamber (R2) in the cylinder (1); and a partition wall (5) that divides the interior of the auxiliary cylinder (4) into a hydraulic lock chamber (L) and a compensation chamber (R) on the piston-opposite side of the hydraulic lock chamber (L). The compensation chamber (R) has a gas chamber (G) and a liquid chamber (A) communicating with the compression-side chamber (R2), and when the piston rod (2) moves in a contraction direction in which the compression-side chamber (R2) is compressed with respect to the cylinder (1), and the tip of the piston rod (2) or a connecting member is inserted into the hydraulic lock chamber (L), the hydraulic lock chamber (L) suppresses the movement of the piston rod (2) in the contraction direction by the internal pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to a damper. BACKGROUND

[0002] For example, as disclosed in JP 2020-008150 A, a damper is provided with: a cylinder; a piston rod movably inserted into the cylinder; a piston coupled to the piston rod and movably inserted into the cylinder, and dividing the cylinder into an extension-side chamber filled with hydraulic oil and a compression-side chamber; a piston rod movably inserted into the cylinder and coupled to the piston; and a free piston axially movably inserted into the cylinder and forming a gas chamber facing the compression-side chamber in the cylinder; which is interposed between a vehicle body and a rear wheel of a suspension straddle vehicle, and generates a damping force that suppresses vibration of the vehicle body at the time of extension and contraction. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] Patent Document 1: JP 2020-008150 A SUMMARY PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the conventional damper, when a contraction operation in which the piston moves in a direction in which the compression-side chamber is compressed with respect to the cylinder is performed, a compression-side vane valve provided at the compression-side port of the piston is opened, and hydraulic oil flows from the compression-side chamber to the extension-side chamber, so that a pressure difference is generated between the compression-side chamber and the extension-side chamber, and a compression-side damping force that suppresses the contraction operation can be generated.

[0005] In such a conventional damper, the compression-side damping force can be generated and the vibration of the vehicle body can be suppressed, but when it is necessary to travel on a rough road in a region where road maintenance is not perfect or the like, a larger compression-side damping force than before is sometimes required to be generated to the damper when the damper is contracted to the vicinity of the stroke end.

[0006] In order to meet such a demand, it is sufficient to increase the pressure of the compression-side chamber at the time of the contraction operation of the damper, but in the structure of the conventional damper, the gas chamber is opposed to the compression-side chamber via the free piston, and it is not possible to increase the pressure of the compression-side chamber to be higher than the pressure of the gas chamber, so that it is limited to attempt to increase the compression-side damping force.

[0007] To address this, an object of the present application is to provide a damper that can generate a larger damping force in the vicinity of the stroke end. MEANS FOR SOLVING PROBLEMS

[0008] In order to solve the aforementioned problems, the buffer of the present invention comprises: a cylinder; a piston rod axially movably inserted into the cylinder; a piston connected to the piston rod and axially movably inserted into the cylinder, and dividing the cylinder into an extension side chamber and a compression side chamber; an auxiliary cylinder accommodated in the compression side chamber in the cylinder; and a partition wall dividing the auxiliary cylinder into a hydraulic lock chamber and a compensation chamber on the opposite side of the piston of the hydraulic lock chamber; the compensation chamber has a gas chamber and a liquid chamber connected to the compression side chamber, and when the piston rod moves relative to the cylinder in a contraction direction to compress the compression side chamber and the front end of the piston rod or a connecting component connected to the piston rod is inserted into the hydraulic lock chamber, the hydraulic lock chamber suppresses the movement of the piston rod in the contraction direction by the internal pressure.

[0009] In the shock absorber constructed in this manner, when a contraction action occurs, the piston moves in the contraction direction and the piston rod enters the hydraulic lock chamber, the resistance that suppresses the movement of the piston rod can be added to the damping force during the contraction action by the pressure in the hydraulic lock chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a cross-sectional view of a buffer in one embodiment. Figure 2 This is a cross-sectional view of a shock absorber according to a first modified example of one embodiment. Implementation Method

[0011] The present invention will be described based on the embodiments shown in the drawings. Figure 1 As shown, a shock absorber D in one embodiment includes: a cylinder 1; a piston rod 2 axially movably inserted into the cylinder 1; a piston 3 connected to the piston rod 2 and axially movably inserted into the cylinder 1, dividing the interior of the cylinder 1 into an expansion-side chamber R1 and a compression-side chamber R2; an auxiliary cylinder 4 housed in the compression-side chamber R2 of the cylinder 1; and a partition wall 5 dividing the interior of the auxiliary cylinder 4 into a hydraulic lock chamber L and a compensation chamber R on the opposite side of the piston from the hydraulic lock chamber L. Although not shown, the shock absorber D is installed between the vehicle body and the rear wheel of a straddle-type vehicle with a suspension, such as a motorcycle, to generate a damping force during extension and contraction, thereby suppressing vehicle body vibration. The shock absorber D can also be used in vehicles other than straddle-type vehicles, and in non-vehicle equipment, buildings, and the like.

[0012] Hereinafter, each part of the shock absorber D will be described. The cylinder 1 is cylindrical and its upper end opening is mounted on Figure 1 The cover 10 at the upper end is closed. The cover 10 has a bracket 10a that closes the upper end opening of the cylinder 1 and can be connected to the body of the suspension straddle type vehicle. Figure 1 The inner circumference of the middle and lower end is fitted with a ring-shaped guide 11 which is inserted through the piston rod 2. Figure 1The open end of the middle and lower end is equipped with an annular protrusion stopper 12. The guide 11 is limited from the inside of the cylinder 1 to the outside by a retaining ring 13 installed on the inner periphery of the cylinder 1. Figure 1 Moves downward and is pushed by the pressure of the liquid in cylinder 1 Figure 1 The guide member 11 is pushed downward in the middle and positioned in contact with the retaining ring 13. Furthermore, a cylindrical bushing 14 is mounted on the inner periphery of the guide member 11 so as to be in sliding contact with the outer periphery of the piston rod 2, and a sealing ring 15 is mounted on the inner periphery of the guide member 11 so as to be in sliding contact with the outer periphery of the piston rod 2 and seal the outer periphery of the piston rod 2. Furthermore, a sealing ring 16 is mounted on the outer periphery of the guide member 11 so as to be in close contact with the inner periphery of the cylinder 1 and seal the space between the cylinder 1 and the guide member 11.

[0013] In addition, in cylinder 1 Figure 1 The outer periphery of the middle upper part is screwed and fixed with an annular upper spring bracket 7. When the cylinder 1 is rotated, the upper spring bracket 7 can be axially moved relative to the cylinder 1. Figure 1 Displacement in the upper and lower directions.

[0014] The piston rod 2 is inserted into the cylinder 1 in an axially movable manner through the inner periphery of the protruding stopper 12 and the guide 11, and the front end is connected to the piston 3 inserted into the cylinder 1 in an axially movable manner. The piston rod 2 has a small diameter portion 2a provided at the front end. Figure 1 The piston 3 is installed on the outer periphery of the middle upper end; the threaded portion 2b is provided on the outer periphery of the upper end of the small diameter portion 2a; and the step portion 2c is formed between the small diameter portion 2a and the lower portion of the small diameter portion 2a. Figure 1 A bracket 17 is installed at the middle lower end to connect the piston rod 2 to the swing arm supporting the rear wheel of the suspension straddle type vehicle (not shown). A collision buffer rubber 18 is fitted on the outer periphery of the lower end of the piston rod 2 and is placed on the bracket 17. The collision buffer rubber 18 is connected to the piston rod 2. Figure 1 The bump stoppers 12 at the middle and lower ends face each other in the axial direction. When the buffer D travels toward the contraction side near the end of the stroke, it abuts against the bump stoppers 12 and is compressed, exerting an elastic force to suppress the buffer D from traveling in the further contraction direction, thereby alleviating the impact of the buffer D when it is most contracted.

[0015] Bracket 17 includes a lower spring bracket 17a on its outer periphery. A suspension spring 8, a coil spring, is interposed between lower spring bracket 17a and upper spring bracket 7 mounted on the outer periphery of cylinder 1. Suspension spring 8 applies force in a direction that axially separates cylinder 1 and piston rod 2, that is, in a direction that extends shock absorber D. This spring force interposes shock absorber D between the vehicle body and the rear wheel of the suspension straddle-type vehicle, elastically supporting the vehicle body. Furthermore, since the axial position of upper spring bracket 7 relative to cylinder 1 can be changed, the initial load applied to suspension spring 8 can be varied, thereby adjusting the vehicle height of the suspension straddle-type vehicle.

[0016] The compression-side vane valve 20, the piston 3, and the extension-side vane valve 21 are sequentially assembled to the small-diameter portion 2a of the piston rod 2. The compression-side vane valve 20, the piston 3, and the extension-side vane valve 21 are sandwiched by the threaded portion 2b of the small-diameter portion 2a of the piston rod 2 and the stepped portion 2c of the piston rod 2, and are fixed to the small-diameter portion 2a of the piston rod 2.

[0017] The piston 3 has a piston ring 3a on the outer periphery thereof, which is in sliding contact with the inner periphery of the cylinder 1, and divides the inside of the cylinder 1 into the extension-side chamber Rl and the compression-side chamber R2, which are filled with a liquid. In addition, the piston 3 has the extension-side port 3b and the compression-side port 3c, which communicate the extension-side chamber Rl and the compression-side chamber R2. Furthermore, the liquid filled in the extension-side chamber Rl and the compression-side chamber R2 is, for example, hydraulic oil, but a liquid other than hydraulic oil can also be used.

[0018] The compression-side vane valve 20 is a laminated vane valve formed by laminating a plurality of annular plates, and is fixed to the inner periphery of the piston rod 2, and is laminated to the lower end of the piston 3, allowing the outer peripheral side to bend. Figure 1 The compression-side vane valve 20 closes the compression-side port 3c when it is laminated to the piston 3, and opens the compression-side port 3c when it is bent by the pressure of the compression-side chamber R2 acting through the compression-side port 3c.

[0019] On the other hand, the extension-side vane valve 21 is a laminated vane valve formed by laminating a plurality of annular plates, and is fixed to the inner periphery of the piston rod 2, and is laminated to the upper end of the piston 3, allowing the outer peripheral side to bend. Figure 1 The extension-side vane valve 21 closes the extension-side port 3b when it is laminated to the piston 3, and opens the extension-side port 3b when it is bent by the pressure of the extension-side chamber Rl acting through the extension-side port 3b.

[0020] Further, the closure body 6 is screw-fitted to the threaded portion 2b of the small-diameter portion 2a of the piston rod 2, and is more toward the upper side than the piston nut 22. Figure 1 In this way, the closure body 6 is attached to the front end of the piston rod 2 as a linking member. In the present embodiment, the closure body 6 is a hexagonal nut shape that can be gripped by a wrench or the like not shown, has a threaded portion 6a screw-fitted to the threaded portion 2b on the inner periphery, and has a circular annular flat surface 6b on the upper end of the extension-side end. Figure 1 In addition, a stopper 23 that abuts against the lower end of the closure body 6 is attached to the outer periphery of the threaded portion 2b of the piston rod 2 and the extension-side opposite side of the closure body 6. Figure 1 The stopper 23 is a clasp that is fitted in an unmarked groove provided on the outer periphery of the small-diameter portion 2a of the piston rod 2, and abuts against the lower end of the closure body 6 to restrict the movement of the closure body 6 toward the lower side opposite to the extension-side of the piston rod 2. Figure 1 The stopper 23 is a clasp that is fitted in an unmarked groove provided on the outer periphery of the small-diameter portion 2a of the piston rod 2, and abuts against the lower end of the closure body 6 to restrict the movement of the closure body 6 toward the lower side opposite to the extension-side of the piston rod 2.

[0021] Further, the tip end of the small diameter portion 2a of the piston rod 2 is cylindrical, and a flange portion 2d and a stopper 23 formed by press working the tip end sandwich the closure body 6, which is fixed to the piston rod 2.

[0022] The auxiliary cylinder 4 is cylindrical, is fitted to the outer periphery of the annular protrusion 10b provided at the middle lower end of the cap 10, and is fixed to the cap 10 by welding, and the cylinder 1 is housed in the compression side chamber R2. In this way, the upper end of the auxiliary cylinder 4 is closed by the cap 10, and further, the outer diameter of the auxiliary cylinder 4 is smaller than the inner diameter of the cylinder 1, and an annular gap S is formed between the auxiliary cylinder 4 and the cylinder 1. Figure 1

[0023] Further, a disc-shaped partition wall 5 is fitted to the inner periphery of the auxiliary cylinder 4, and the inside of the auxiliary cylinder 4 is divided by the partition wall 5 into the hydraulic lock chamber L and a compensation chamber R on the opposite side of the hydraulic lock chamber L with respect to the piston. In the present embodiment, the auxiliary cylinder 4 is formed by two cylinders 4a, 4b which are axially overlapped, and by making the inner diameters of the mutually facing open ends of the cylinders 4a, 4b such that the partition wall 5 can be fitted, fitting the open ends of the cylinders 4a, 4b to the partition wall 5, axially overlapping the cylinders 4a, 4b, and welding the outer peripheries of the end portions of the cylinders 4a, 4b and the partition wall 5, the partition wall 5 is integrated with the auxiliary cylinder 4. By integrating the partition wall 5 with the auxiliary cylinder 4 in this way, the hydraulic lock chamber L and the compensation chamber R can be divided liquid-tightly without providing a sealing member. Further, the method of processing the partition wall 5 in the auxiliary cylinder 4 is one example, and the partition wall 5 can be fixed to the auxiliary cylinder 4 by a method of fitting the partition wall 5 to the inner periphery of the auxiliary cylinder 4 by a pair of clamps fitted to the inner periphery of the auxiliary cylinder 4, and the like. In this case, the hydraulic lock chamber L and the compensation chamber R can be sealed by providing a sealing ring which is in close contact with the inner periphery of the auxiliary cylinder 4 to the outer periphery of the partition wall 5.

[0024] Further, in the inner periphery of the auxiliary cylinder 4 and in the compensation chamber R, a free piston 30 which is in sliding contact with the inner periphery of the auxiliary cylinder 4 and which is axially movable and which divides the compensation chamber R into a gas chamber G and a liquid chamber A is fitted. The free piston 30 has a sealing ring 30a in sliding contact with the inner periphery of the auxiliary cylinder 4 in the outer periphery, and seals between the gas chamber G and the liquid chamber A. Compressed gas is filled in the gas chamber G, and the same liquid as that filled in the extension side chamber Rl and the compression side chamber R2 is filled in the liquid chamber A. Further, in the shock absorber D of the present embodiment, the compensation chamber R is divided into the gas chamber G and the liquid chamber A by the free piston 30, but an elastic partition wall such as an air bag, a diaphragm, a bellows, or the like which can change the volume distribution of the gas chamber G and the liquid chamber A can be used.

[0025] ​Further, the assist cylinder 4 has a throttle hole 4c that communicates the compression-side chamber R2 and the liquid chamber A through a wall portion of the assist cylinder 4. The throttle hole 4c exerts a resistance to the flow of the liquid between the compression-side chamber R2 and the liquid chamber A of the compensation chamber R. In addition, in the present embodiment, the cross-sectional area of the annular gap S between the assist cylinder 4 and the cylinder 1 is made larger than the opening area of the throttle hole 4c, and the resistance exerted by the annular gap S to the flow of the liquid through the annular gap S is not greater than the resistance exerted by the throttle hole 4c to the flow of the liquid through the throttle hole 4c. In the present embodiment, the throttle hole 4c exerts a resistance to the flow of the liquid between the compression-side chamber R2 and the liquid chamber A of the compensation chamber R, but the flow path area of the annular gap S can be reduced, and a resistance can be exerted to the flow of the liquid between the compression-side chamber R2 and the liquid chamber A of the compensation chamber R through the annular gap S, and the annular gap S can be used as a restriction flow path. In this case, instead of the throttle hole 4c, a hole that exerts almost no resistance to the flow of the liquid can be provided in the assist cylinder 4, and the liquid chamber A can be made to communicate with the compression-side chamber R2 via the annular gap S.

[0026] In addition, the lock piece 31 is movably inserted into the hydraulic lock chamber L in the assist cylinder 4 in the axial direction, and a spring 32 is interposed between the lock piece 31 and the partition wall 5. The lock piece 31 has a circular ring-shaped head portion 31a having a hole 31b at the center, and a cylindrical portion 31c rising from the outer periphery of the head portion 31a toward the upper side in the axial direction and facing the inner periphery of the assist cylinder 4. Figure 1 The lock piece 31 is positioned at a position abutting against the snap ring 33 in a state in which the lock piece 31 is spaced apart from the closure body 6 of the piston rod 2 by the spring 32.

[0027] The snap ring 33 that prevents the lock piece 31 from falling out of the hydraulic lock chamber L is attached to the inner periphery of the assist cylinder 4 near the lower end in the axial direction. Figure 1 The lock piece 31 is positioned at a position abutting against the snap ring 33 in a state in which the lock piece 31 is spaced apart from the closure body 6 of the piston rod 2 by the spring 32.

[0028] The outer diameter of the cylindrical portion 31c of the lock piece 31 is slightly smaller than the inner diameter of the portion of the assist cylinder 4 that forms the hydraulic lock chamber L, and the liquid can pass through the gap between the outer periphery of the lock piece 31 and the inner periphery of the assist cylinder 4 while being resisted.

[0029] Further, the inner diameter of the hole 31b in the head 31a is smaller than the outer diameter of the annular flat surface 6b of the closure body 6, and is set to a diameter that can allow the flange portion 2d of the front end portion of the piston rod 2 to be inserted therethrough. Therefore, in a state in which the closure body 6 and the lock tab 31 are not in abutment, the hydraulic lock chamber L and the compression-side chamber R2 communicate via the hole 31b of the lock tab 31 and the gap between the outer periphery of the lock tab 31 and the inner periphery of the auxiliary cylinder 4, but when the piston rod 2 moves upward in the cylinder 1 and the head 31a abuts against the flat surface 6b of the closure body 6, the hole 31b of the lock tab 31 is closed by the flat surface 6b of the closure body 6 and the piston rod 2, and the inside of the hydraulic lock chamber L and the compression-side chamber R2 communicate only via the narrow gap between the outer periphery of the lock tab 31 and the inner periphery of the auxiliary cylinder 4. Figure 1

[0030] The damper D is configured in the above-described manner, and the operation of the damper D will be described below. First, the operation when the damper D is in the extension operation will be described. When the piston rod 2 moves downward in the cylinder 1 and the damper D is in the extension operation, the liquid in the extension-side chamber Rl that is reduced by the piston 3 moves to the compression-side chamber R2 that is expanded by the push-out of the extension-side vane valve 21 through the extension-side port 3b. Since the extension-side vane valve 21 exerts resistance to the flow of this liquid, the pressure in the extension-side chamber Rl rises, and a pressure difference is generated between the pressure in the extension-side chamber Rl and the pressure in the compression-side chamber R2, and the damper D generates the extension-side damping force that hinders the extension operation. When the damper D is in the extension operation, the piston rod 2 is withdrawn from the cylinder 1, and therefore the volume of liquid that is withdrawn from the cylinder 1 is insufficient in the compression-side chamber R2, but the liquid in the insufficient portion is displaced in the direction in which the gas chamber G of the free piston 30 is expanded in the auxiliary cylinder 4, and is supplied from the liquid chamber A to the compression-side chamber R2. Figure 1 Conversely, the operation when the damper D is in the contraction operation will be described. When the piston rod 2 moves upward in the cylinder 1 and the damper D is in the contraction operation, the liquid in the compression-side chamber R2 that is expanded by the push-out of the extension-side vane valve 21 through the extension-side port 3b moves to the extension-side chamber Rl that is reduced by the piston 3. Since the extension-side vane valve 21 exerts resistance to the flow of this liquid, the pressure in the compression-side chamber R2 rises, and a pressure difference is generated between the pressure in the compression-side chamber R2 and the pressure in the extension-side chamber Rl, and the damper D generates the contraction-side damping force that hinders the contraction operation. When the damper D is in the contraction operation, the piston rod 2 is inserted into the cylinder 1, and therefore the volume of liquid that is inserted into the cylinder 1 is insufficient in the compression-side chamber R2, but the liquid in the insufficient portion is displaced in the direction in which the gas chamber G of the free piston 30 is reduced in the auxiliary cylinder 4, and is supplied from the liquid chamber A to the compression-side chamber R2.

[0031] Figure 1 ​​When the damper D contracts due to upward movement, the liquid in the compression-side chamber R2, which has been contracted by the piston 3, moves through the compression-side port 3c to the expansion-side chamber R1, which has expanded by pushing open the compression-side leaf valve 20. The compression-side leaf valve 20 resists this flow of liquid, causing the pressure in the compression-side chamber R2 to rise. This creates a pressure difference between the pressure in the compression-side chamber R2 and the pressure in the expansion-side chamber R1, causing the damper D to generate a compression-side damping force that hinders contraction. During the contraction of the damper D, the piston rod 2 intrudes into the cylinder 1, creating an excess volume of liquid in the compression-side chamber R2. This excess liquid flows through the orifice 4c into the liquid chamber A of the compensation chamber R, causing the free piston 30 to displace within the auxiliary cylinder 4 in a direction that contracts the gas chamber G. In addition, the compensation chamber R connects the compression side chamber R2 with the liquid chamber A via the throttle hole 4c, and the pressure in the compression side chamber R2 can exceed the pressure in the liquid chamber A and rise. Therefore, the buffer D can generate a larger compression side damping force than the previous single-rod type buffer.

[0032] When the buffer D is in contraction, the piston rod 2 moves relative to the cylinder 1. Figure 1 When the piston rod 2 moves upward, the closing body 6 attached to the front end of the piston rod 2 will soon come into contact with the head 31a of the locking plate 31 in the hydraulic lock chamber L. When the flat surface 6b of the closing body 6 comes into contact with the locking plate 31, the hole 31b of the locking plate 31 is closed by the closing body 6 and the piston rod 2, and the communication between the hydraulic lock chamber L and the compression side chamber R2 through the hole 31b is cut off. Figure 1 When the locking plate 31 is moved upward in the middle to contract the buffer D, the locking plate 31 is pushed by the closing body 6 and moves in the direction of compressing the hydraulic lock chamber L. The closing body 6, which serves as a connecting component, is inserted into the hydraulic lock chamber L. When the closing body 6 is in contact with the head 31a of the locking plate 31, the hydraulic lock chamber L and the compression side chamber R2 are connected only through the gap between the locking plate 31 and the auxiliary cylinder 4. Therefore, the piston rod 2 moves in the contraction direction relative to the cylinder 1, and the piston rod 2 penetrates into the hydraulic lock chamber L. When the locking plate 31 pushed by the closing body 6 contracts the hydraulic lock chamber L, the liquid in the hydraulic lock chamber L encounters resistance in the gap and moves toward the compression side chamber R2. Therefore, the pressure in the hydraulic lock chamber L rises above the compression side chamber R2, and the piston rod 2 and the locking plate 31 are pushed upward by the pressure in the hydraulic lock chamber L. Figure 1 Push from the lower middle.

[0033] Thus, when the damper D is displaced to the vicinity of the stroke end on the contraction side, the closing body 6 abuts against the lock piece 31 to raise the pressure in the hydraulic lock chamber L, and the hydraulic lock function is exerted, so the damper D adds the resistance generated by the rise in the pressure in the hydraulic lock chamber L to the damping force generated by the contraction-side vane valve 20, and a greater damping force on the contraction side can be generated.

[0034] When the damper D is displaced to the vicinity of the stroke end on the contraction side, the damper D is displaced to the vicinity of the stroke end on the contraction side, the closing body 6 abuts against the lock piece 31 to raise the pressure in the hydraulic lock chamber L, and the hydraulic lock function is exerted, so the damper D adds the resistance generated by the rise in the pressure in the hydraulic lock chamber L to the damping force generated by the contraction-side vane valve 20, and a greater damping force on the contraction side can be generated.

[0035] In the damper D of the present embodiment configured in this way, when the contraction operation is performed and the piston 3 is displaced in the contraction direction and the piston rod 2 intrudes into the hydraulic lock chamber L, the resistance to the displacement of the piston rod 2 by the pressure in the hydraulic lock chamber L can be added to the damping force at the time of the contraction operation. Therefore, according to the damper D of the present embodiment, a greater damping force than that of the conventional damper can be generated when the contraction is performed to the vicinity of the stroke end. Moreover, if the damper D configured in this way is used as mounted between the vehicle body and the wheel of a suspension straddle-type vehicle, the so-called bottoming out of the suspension straddle-type vehicle when running on a rough road can be suppressed.

[0036] In the damper D of the present embodiment configured in this way, when the contraction operation is performed and the piston 3 is displaced in the contraction direction and the piston rod 2 intrudes into the hydraulic lock chamber L, the resistance to the displacement of the piston rod 2 by the pressure in the hydraulic lock chamber L can be added to the damping force at the time of the contraction operation. Therefore, according to the damper D of the present embodiment, a greater damping force than that of the conventional damper can be generated when the contraction is performed to the vicinity of the stroke end. Moreover, if the damper D configured in this way is used as mounted between the vehicle body and the wheel of a suspension straddle-type vehicle, the so-called bottoming out of the suspension straddle-type vehicle when running on a rough road can be suppressed.

[0037] In addition, the damper D of the present embodiment can generate a greater damping force when the contraction is performed to the vicinity of the stroke end, so even if the impact-absorbing rubber 18 does not generate a greater elastic force, the impact at the time of the greatest contraction can be mitigated, and the impact-absorbing rubber 18 can be downsized and lightened. In addition, the damper D of the present embodiment can generate a greater damping force when the contraction is performed to the vicinity of the stroke end, so as the suspension spring 8 is continuously compressed, the spring constant does not need to be changed to compensate for the insufficient damping force, so the structure of the suspension spring 8 becomes simple, and the productivity is improved.

[0038] Further, in the damper D of the present embodiment, a lock piece 31 having a hole 31b is inserted into a hydraulic lock chamber L in the auxiliary cylinder 4 in an axially movable manner, a spring 32 is interposed between the lock piece 31 and the partition wall 5 to apply a force to the lock piece 31 toward the piston side, and a closure body 6 is provided at the front end of the piston rod 2 to close the hole 31b when the lock piece 31 abuts against the closure body 6. The closure body 6 serves as a linking member.

[0039] According to the damper D configured in this manner, the piston rod 2 approaches the auxiliary cylinder 4, the hole 31b of the lock piece 31 of the hydraulic lock chamber L is closed by the closure body 6 provided at the piston rod 2 side, and the hydraulic lock chamber L can be compressed by the piston rod 2, the closure body 6, and the lock piece 31. Therefore, even if there is an offset between the piston rod 2 and the axis of the auxiliary cylinder 4, the hydraulic lock chamber L can be compressed to increase the pressure in the hydraulic lock chamber L, and a desired large damping force on the compression side can be obtained near the end of the stroke.

[0040] Further, if there is no problem of the offset between the piston rod 2 and the axis of the auxiliary cylinder 4, the lock piece 31, the spring 32, and the clasp 33 housed in the auxiliary cylinder 4 can be omitted, and a circular ring-shaped lock piece can be provided at the outer periphery of the piston rod 2 as a linking member. When the piston rod 2 invades into the auxiliary cylinder 4 together with the lock piece, the hydraulic lock chamber L is compressed by the lock piece provided at the piston rod 2 to increase the internal pressure, and the movement of the piston rod 2 in the contraction direction is suppressed.

[0041] Further, in the damper D of the present embodiment, the closure body 6 is provided as a linking member linked to the piston rod 2, and the hydraulic lock chamber L is inserted into the hydraulic lock chamber L by the closure body 6 to suppress the movement of the piston rod 2 in the contraction direction, but the linking member can be omitted, and the front end of the piston rod 2 can be inserted into the hydraulic lock chamber L to suppress the movement of the piston rod 2 in the contraction direction by the hydraulic lock chamber L. In this case, for example, when the front end surface of the piston rod 2 abuts against the lock piece 31, the hole 31b can be closed at the front end surface. In addition, in the case where the linking member is not provided and the lock piece 31, the spring 32, and the clasp 33 are omitted, the inner diameter of the cylinder 4a of the auxiliary cylinder 4 forming the hydraulic lock chamber L can be slightly larger than the outer diameter of the front end of the piston rod 2, and when the front end of the piston rod 2 is inserted into the hydraulic lock chamber L, the pressure in the hydraulic lock chamber L increases to suppress the movement of the piston rod 2 in the contraction direction. In this way, the damper D can generate the hydraulic lock function by installing some linking member at the front end of the piston rod 2 and inserting the linking member into the hydraulic lock chamber L, or can generate the hydraulic lock function by inserting the front end of the piston rod 2 itself into the hydraulic lock chamber L.

[0042] Further, in the damper D of the present embodiment, when the hydraulic lock chamber L is compressed, the liquid from the hydraulic lock chamber L toward the compression-side chamber R2 passes through the gap between the lock piece 31 and the auxiliary cylinder 4, and the flow of the liquid is resisted in the gap to raise the pressure in the hydraulic lock chamber L, but the lock piece 31 can be in sliding contact with the inner periphery of the auxiliary cylinder 4, and instead of the gap, a passage functioning as a throttle hole or choke ring is formed in the lock piece 31 or the closure body 6 or between the lock piece and the closure body 6 or on the piston rod 2, and the pressure in the hydraulic lock chamber L is raised by causing the liquid to pass through the passage. Further, a throttle hole or choke ring that communicates the hydraulic lock chamber L and the compression-side chamber R2 can be provided in the auxiliary cylinder 4. Further, the closure body 6 is hexagonal, but when abutting against the lock piece 31, the hole 31b of the lock piece 31 is closed, and when the piston rod 2 intrudes into the hydraulic lock chamber L, as long as the hydraulic lock chamber L can be compressed together with the lock piece 31, the shape and structure can be appropriately designed and changed. Further, even in the case where a groove is provided in one or both of the abutting surfaces of the closure body 6 and the lock piece 31 and the groove functions as a throttle hole or choke ring for raising the pressure in the hydraulic lock chamber L, in the state where the closure body 6 and the lock piece 31 abut against each other, the hole 31b is not completely closed, but as long as the function of the hydraulic lock chamber L can be achieved, such a case is also included in the concept that the hole 31b is closed by the closure body 6.

[0043] Further, the lock piece 31 can be made of metal, but if made of resin, the noise when abutting against the closure body 6 can be reduced, and the inner peripheral surface of the auxiliary cylinder 4 can be prevented from being damaged when moving in the auxiliary cylinder 4.

[0044] Further, in the damper D of the present embodiment, the auxiliary cylinder 4 has a throttle hole 4c that communicates the compression-side chamber R2 and the liquid chamber A in the lateral direction, and thus when the damper D is contracted, the pressure in the compression-side chamber R2 can be made higher than the pressure in the compensation chamber R, and thus the damping force on the compression side when the damper D is contracted can be increased. Therefore, if the damper D configured in this way is used between the vehicle body and the wheel of a suspension straddle-type vehicle, the bottoming can be further suppressed when the suspension straddle-type vehicle is driven on a rough road.

[0045] Further, in the damper D of the present embodiment, the closure body 6 is attached to the outer periphery of the front end of the piston rod 2, and the piston 3 has an extension-side port 3b and a compression-side port 3c, which are annular, attached to the outer periphery of the piston rod 2 and the opposite side of the closure body 6 from the assist cylinder, and which communicate with the extension-side chamber Rl and the compression-side chamber R2, and the damper D is provided with: a compression-side spool valve 20, which is annular, fixed to the outer periphery of the piston rod 2 at the inner periphery and overlaps the extension-side chamber side end of the piston 3 to open and close the compression-side port 3c; an extension-side spool valve 21, which is annular, fixed to the outer periphery of the piston rod 2 at the inner periphery and overlaps the compression-side chamber side end of the piston 3 to open and close the extension-side port 3b; and a stopper 23, attached to the outer periphery of the piston rod 2 to abut against the opposite side of the closure body 6 from the assist cylinder. In the damper D configured in this way, when the damper D is in the contraction operation near the end of the stroke, the closure body 6 provided to the piston rod 2 abuts against the lock piece 31 to compress the hydraulic lock chamber L together with the lock piece 31, and the pressure in the hydraulic lock chamber L rises. The pressure in the hydraulic lock chamber L urges the closure body 6 toward the piston 3 side relative to the piston rod 2, but the closure body 6 is restricted from moving toward the piston 3 side by the stopper 23 attached to the piston rod 2, and therefore the axial load that the closure body 6 receives due to the pressure of the hydraulic lock chamber L does not act on the compression-side spool valve 20, the piston 3, and the extension-side spool valve 21. Therefore, according to the damper D of the present embodiment configured in this way, even if the closure body 6 is provided to the piston rod 2, since the axial load that the closure body 6 receives due to the pressure of the hydraulic lock chamber L does not act on the compression-side spool valve 20, the piston 3, and the extension-side spool valve 21, the deterioration of the compression-side spool valve 20, the piston 3, and the extension-side spool valve 21 can be prevented, and the damping forces of the extension side and the compression side can be generated as designed.

[0046] Further, the upper and lower arrangement of the gas chamber G and the liquid chamber A in the compensation chamber R can also be reversed Figure 1the opposite is shown. In addition, in the damper D of the present embodiment, the auxiliary cylinder 4 is provided with the throttle hole 4c that communicates the liquid chamber A and the compression-side chamber R2, and assists the pressure rise in the compression-side chamber R2 at the time of the contraction operation, but it is also possible to communicate the liquid chamber A and the compression-side chamber R2 with a hole that cannot function as a throttle hole, and to provide a restriction flow path that applies resistance to the flow of the liquid in the gap between the cylinder 1 and the auxiliary cylinder 4, and to assist the pressure rise in the compression-side chamber R2 at the time of the contraction operation. However, when the pressure rise in the compression-side chamber R2 at the time of the contraction operation is assisted by the throttle hole 4c that easily manages the area, the advantage of easily adjusting the pressure in the compression-side chamber R2 and the pressure in the liquid chamber A can be enjoyed. In addition, the diameter of the hydraulic lock chamber L side of the auxiliary cylinder 4 and the diameter of the compensation chamber R side are equal, but they can be different. Furthermore, in the damper D of the present embodiment, since the auxiliary cylinder 4 is held by the cover 10, the components assembled to the auxiliary cylinder 4 can be assembled to the cover 10 together with the auxiliary cylinder 4 to form an auxiliary cylinder assembly, and the assembly of the damper D becomes easy. However, the structure in which the auxiliary cylinder 4 is housed in the cylinder 1 and is fixed is not limited to Figure 2 As shown, design changes can be appropriately made.

[0047] For example, as in the damper D1 of the first modification example of the embodiment shown in Figure 2 The auxiliary cylinder 4 can be formed of a first cylinder 41 and a second cylinder 42 that are bottomed cylinders, the first cylinder 41 is a bottomed cylinder that forms the hydraulic lock chamber L with the bottom portion 41a as a partition wall, and the second cylinder 42 is fitted to the outer periphery of the bottom portion side end of the first cylinder 41 and forms the compensation chamber R by being held to the first cylinder 41 by press bonding from the outer periphery side.

[0048] The first cylinder 41 has a bottom portion 41a that is a disc, and a cylinder portion 41b that is smaller in outer diameter than the bottom portion 41a and hangs from the bottom portion 41a toward the piston side, which is housed in the cylinder 1 and in the compression-side chamber R2, and which forms the hydraulic lock chamber L inside. The lock piece 31 is inserted into the first cylinder 41 so as to be axially movable, and a spring 32 that is a conical coil spring is interposed between the lock piece 31 and the bottom portion 41a. In addition, the Figure 2 The lower end is bent inward in the inner periphery, a bent portion 41c is formed at the lower end of the cylinder portion 41b, and the lock piece 31 is prevented from falling out of the hydraulic lock chamber L by the bent portion 41c. The lock piece 31 is positioned at a position that abuts against the bent portion 41c by the spring 32 in a state in which the lock piece 31 is separated from the closure body 6 of the piston rod 2.

[0049] The second cylinder 42 is a cylindrical shape, is fitted to the outer periphery of the annular protrusion 10b of the lower end of the cover 10, is fixed to the cover 10 by welding, is housed in the cylinder 1 in the compression-side chamber R2, and forms the compensation chamber R inside. In addition, the Figure 2 The second cylinder 42 is a cylindrical shape, is fitted to the outer periphery of the annular protrusion 10b of the lower end of the cover 10, is fixed to the cover 10 by welding, is housed in the cylinder 1 in the compression-side chamber R2, and forms the compensation chamber R inside. In addition, the​ The inner diameter of the lower end of the second cylinder 42 is larger than that of the upper end, and a step portion 42a is provided on the inner periphery and a throttle hole 42b, which is a radial through-wall portion, is provided on the opposite side of the step portion 42a. The inner diameter of the lower end of the second cylinder 42 is set to a diameter into which the bottom portion 41a of the first cylinder 41 can be inserted. The axial length of the portion 42c, which is the portion of the second cylinder 42 having a large inner diameter, is longer than the axial length of the bottom portion 41a of the first cylinder 41.

[0050] To join the first cylinder 41 and the second cylinder 42 configured in this manner, the bottom portion side end of the first cylinder 41 is inserted into the inside of the lower end of the second cylinder 42, and the bottom portion 41a of the first cylinder 41 is brought into abutment with the step portion 42a of the second cylinder 42. In this state, the portion 42c of the second cylinder 42, which is the portion of the lower end having a large inner diameter, is plastically deformed by being crimped from the outer periphery side as a crimping portion to hold the bottom portion 41a, and further the second cylinder 42 and the first cylinder 41 are joined. In this way, when the auxiliary cylinder 4 is formed using the first cylinder 41, which is a bottomed cylinder that forms the hydraulic lock chamber L, and the second cylinder 42, which is fitted to the outer periphery of the bottom portion side end of the first cylinder 41 and holds the first cylinder 41 by being crimped from the outer periphery side to form the compensation chamber R, since deformation due to welding does not occur in the first cylinder 41 and the second cylinder 42, it is not necessary to perform post-processing on the inner peripheral surface of the first cylinder 41 and the second cylinder 42, and thus the auxiliary cylinder 4 can be manufactured economically and easily, and since the hydraulic lock chamber L is formed using the first cylinder 41, which is a bottomed cylinder, when the hydraulic lock function is exerted, there is no concern that liquid will leak from the inside of the hydraulic lock chamber L into the compression side chamber R2 via a portion other than between the cylinder portion 41b and the lock piece 31, and thus the hydraulic lock function can be stably exerted.

[0051] In addition, even if liquid in the compensation chamber R leaks from the portion 42d, which is the lower end of the first cylinder 41 and the second cylinder 42 that becomes a crimping portion, to the compression side chamber R2, since the joint portion of the first cylinder 41 and the second cylinder 42 faces only the liquid chamber A, the liquid chamber A and the compression side chamber R2 are in a state of being in communication at all times, and thus no problem occurs, and since the hydraulic lock chamber L is formed inside the first cylinder 41, which is a bottomed cylinder, no influence on the hydraulic lock chamber L occurs.

[0052] In addition, the holding of the first cylinder 41 by the second cylinder 42 can be performed by fitting, as long as the holding state can be maintained by fitting the second cylinder 42 to the outer periphery of the first cylinder 41.

[0053] Furthermore, the first cylinder that forms the hydraulic lock chamber L can be provided in a cylindrical shape, and the second cylinder that is joined to the cap 10 to form the compensation chamber R can be provided in a bottomed cylindrical shape, and the first cylinder and the second cylinder can be joined to form the auxiliary cylinder 4 by fitting the first cylinder to the outer periphery of the bottom portion side end of the second cylinder, crimping the first cylinder from the outer periphery side toward the bottom portion of the second cylinder, and crimping.

[0054] The above describes the preferred embodiments of the present application, but modifications, variations, and changes can be made without departing from the scope of the application. Explanation of symbols

[0055] 1 cylinder 2 piston rod 3 piston 3b elongation-side port 3c compression-side port 4 auxiliary cylinder 4c orifice 5 partition wall 6 closure body (link member) 20 compression-side vane valve 21 elongation-side vane valve 23 stopper 31 lock plate 31b hole 32 spring 41 first cylinder 41a bottom 42 second cylinder A liquid chamber D buffer G gas chamber L hydraulic lock chamber R compensation chamber R1 elongation-side chamber R2 compression-side chamber S annular gap

Claims

1. A buffer comprising: cylinder; a piston rod, axially movably inserted into the cylinder; a piston connected to the piston rod and inserted into the cylinder so as to be axially movable, and dividing the interior of the cylinder into an expansion-side chamber and a compression-side chamber; An auxiliary cylinder housed in the compression-side chamber within the cylinder; and a partition wall dividing the auxiliary cylinder into a hydraulic lock chamber and a compensation chamber on the opposite side of the piston of the hydraulic lock chamber; The compensation chamber comprises a gas chamber and a liquid chamber communicating with the compression side chamber. When the piston rod moves relative to the cylinder in a contraction direction to compress the compression side chamber, and the front end of the piston rod or a connecting component connected to the piston rod is inserted into the hydraulic lock chamber, the hydraulic lock chamber suppresses the movement of the piston rod in the contraction direction by internal pressure.

2. The buffer according to claim 1, comprising: a locking plate having a hole and axially movably inserted into the auxiliary cylinder and the hydraulic locking chamber; a spring interposed between the locking plate and the partition wall to bias the locking plate toward the piston; and a closing body provided at the front end of the piston rod to close the hole when in contact with the locking plate; The connecting component is the closing body.

3. The buffer according to claim 1, wherein The auxiliary cylinder has a throttle hole on the side thereof for connecting the compression side chamber and the liquid chamber. The buffer according to claim 1 , wherein: An annular gap between the cylinder and the auxiliary cylinder forms a restriction flow path, and the restriction flow path applies resistance to the flow of liquid back and forth between the compression side chamber and the compensation chamber.

5. The buffer according to claim 1, wherein The auxiliary cylinder includes: a first bottomed cylinder having a bottomed cylinder with the bottom serving as the partition wall to form a hydraulic lock chamber; and a second cylinder fitted with the outer periphery of the bottom side end of the first cylinder and holding the first cylinder to form a compensation chamber. The buffer according to claim 2 , wherein: The closing body is mounted on the outer periphery of the front end of the piston rod. The piston has an extension side port and a compression side port, and the extension side port and the compression side port are annular and installed on the outer periphery of the piston rod and on the side of the closing body opposite to the auxiliary cylinder, and communicate with the extension side chamber and the compression side chamber. The buffer has: a compression-side leaf valve having an annular shape, the inner periphery of which is fixed to the outer periphery of the piston rod and overlaps with the extension-side chamber side end of the piston to open and close the compression-side port; an expansion-side leaf valve having an annular shape, the inner periphery of which is fixed to the outer periphery of the piston rod and overlaps with the compression-side chamber side end of the piston to open and close the expansion-side port; and A stopper is mounted on the outer periphery of the piston rod and abuts against the side of the sealing body opposite to the auxiliary cylinder.

7. The buffer according to claim 2, wherein The spring is a conical coil spring.

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