Shock absorber

Abstract

The shock absorber (D) is a shock absorber (D) which is used in a vertically placed manner and is provided with a cylinder body (1), a piston rod (2) which is inserted into the cylinder body (1) in a freely movable manner, and a piston (3) which is inserted into the cylinder body (1) and divides the interior of the cylinder body (1) into an extension-side chamber (R1) and a compression-side chamber (R2), and is further configured to be provided with a stopper (S) which is immovable with respect to the cylinder body (1) in the axial direction of the cylinder body (1) and a restriction member (20). And a restricting member which is provided on the piston rod (2), faces the stopper (S) in the axial direction of the cylinder (1), and is capable of restricting the movement of the piston (3) in the extension direction with respect to the cylinder (1) when the restricting member is in contact with the stopper (S).

Description

[Technical field]

[0001] The present invention relates to a buffer. [Technical Background]

[0002] As shown in Japanese patent JP2015-224780A, the buffer includes a cylinder body, a piston rod freely movably inserted into the cylinder body, a piston freely slidably inserted into the cylinder body and connected to the piston rod, an extension side chamber and a compression side chamber filled with hydraulic oil divided by the piston in the cylinder body, and an outer tube covering the outer periphery of the cylinder body and forming a liquid storage chamber for storing hydraulic oil between the outer tube and the cylinder body. The buffer is used to suppress the vibration of the shock-absorbing object.

[0003] This type of shock absorber is used in conjunction with the object whose vibrations need to be suppressed. When in use, it is longitudinally sandwiched between the bogie and wheels of a railway vehicle, in parallel with an axle spring. The shock absorber also includes an annular cover member fixed to the end of the cylinder and with a piston rod inserted through its inner circumference. Because the piston rod is supported by the cover member, it can smoothly extend and retract.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] [Patent Document 1] JP2015-224780A [Summary of the invention]

[0007] [Problems to be Solved by the Invention]

[0008] In most cases, buffers are used in parallel with axle springs to suppress vibrations. If they are clamped between the bogie and wheels of a railway vehicle, the railway vehicle body needs to be removed from the bogie during maintenance. At this time, the axle springs that elastically support the body extend, and the buffer is fully stretched to its maximum length. The piston or the valve assembled on the piston may collide with the cover component.

[0009] When the cover member collides with the piston in this manner, the piston is subjected to a load, and components such as the piston or the valve may be deformed. Alternatively, the piston rod may be subjected to excessive load between the nut connecting the piston to the piston rod and the threaded portion of the piston rod, causing fatigue.

[0010] Therefore, an object of the present invention is to provide a shock absorber capable of suppressing deformation or fatigue even when stretched to its maximum extent.

[0011] [Solutions to Solve the Problem]

[0012] In order to solve the above problems, the buffer of the present invention comprises a cylinder body, a piston rod which can be freely movably inserted into the cylinder body, and a piston which is inserted into the cylinder body and divides the interior of the cylinder body into an extension side chamber and a compression side chamber. It also comprises a stopper which is immovable relative to the cylinder body in the axial direction of the cylinder body and a limiting component. The limiting component is arranged on the piston rod and is opposite to the stopper in the axial direction of the cylinder body, and when it abuts against the stopper, it can limit the movement of the piston in the extension direction relative to the cylinder body.

[0013] According to the buffer constructed in this way, when it is stretched to its longest, the limiting component installed on the piston rod abuts against the block that is immovable relative to the cylinder body and limits its elongation. Therefore, the load in the elongation direction is borne by the limiting component and the block, thereby preventing excessive load from acting on the threaded connection part of the piston or the piston rod. [Brief Description of the Drawings]

[0014] Figure 1 This is a longitudinal cross-sectional view of a buffer in one embodiment.

[0015] Figure 2 This is an enlarged cross-sectional view of the upper end portion of the cylinder of the shock absorber according to one embodiment.

[0016] Figure 3 This is an enlarged cross-sectional view of an upper end portion of a cylinder of a shock absorber in a modified example of one embodiment. [Specific implementation method]

[0017] The present invention will be described below 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 movably inserted into the cylinder 1, a piston 3 inserted into the cylinder 1 and dividing the interior of the cylinder 1 into an expansion chamber R1 and a compression chamber R2, a stopper S immovable relative to the cylinder 1 in the axial direction of the cylinder 1, and a C-ring 20 serving as a limiting member. The C-ring is provided on the piston rod 2 and faces the stopper S in the axial direction of the cylinder 1. When the C-ring abuts the stopper S, the movement of the piston 3 in the expansion direction relative to the cylinder 1 is limited. The shock absorber D is, for example, mounted in parallel with an axle spring, sandwiched between a bogie (not shown) and an axlebox supporting an axle with wheels mounted on its outer circumference on a railway vehicle. It is used as an axle damper placed longitudinally to suppress vertical relative vibration between the bogie and the wheels.

[0018] Next, each part of the buffer D is described in detail. Figure 1 As shown, the cylinder 1 Figure 1 The upper end of the cylinder body is fitted with an annular cover member 10, which is installed on the upper end of the cylinder body 1, closing the side end of the extension side chamber of the cylinder body 1 and supporting the piston rod 2. Figure 1The lower end shown in FIG is closed by the valve housing 11. In addition, the cylinder 1 and the valve housing 11 are housed in an outer tube 12. Figure 1 The lower end of the cylinder 1 is closed by a bottom cover 13. An annular liquid storage chamber R is formed between the cylinder body 1 and the outer tube 12 and stores liquids such as hydraulic oil and gas.

[0019] Outer cylinder 12 Figure 1 The upper end opening of the outer tube is closed by the cover member 10 mounted on the outer tube 12. In addition, the upper end inner periphery of the outer tube 12 is threadedly connected to the cover member 10. Figure 1 In this way, if the nut 19 is threadedly coupled to the outer tube 12, the cover member 10, the cylinder 1 and the valve housing 11 are clamped by the nut 19 and the bottom cover 13, accommodated in the outer tube 12 and fixed relative to the outer tube 12.

[0020] The piston rod 2 can be freely slidably inserted into the cover member 10 and inserted into the cylinder body 1, and is guided by the cover member 10 to move in the axial direction. The cover member 10 thus constructed can close the upper end of the cylinder body 1 and can also serve as a guide to guide the movement of the piston rod 2 in the axial direction. The piston rod 2 has: a small diameter portion 2a, an outer diameter front end (i.e. Figure 1 The lower end of the small diameter portion 2a is small in diameter and a piston 3 is mounted on the outer periphery thereof; a threaded portion 2b is provided on the outer periphery of the front end of the small diameter portion 2a; a step portion 2c is formed at the junction of the small diameter portion 2a and the large diameter portion 2e, and the large diameter portion is at the junction of the small diameter portion 2a. Figure 1 annular groove 2d, which is formed circumferentially in the small diameter portion 2a Figure 1 A C-ring 20 with a circular cross section is attached to the annular groove 2d of the piston rod 2, slightly away from the smaller diameter portion 2a. Furthermore, a C-ring 20 with a circular cross section is attached to the annular groove 2d of the piston rod 2, acting as a restricting member. The C-ring 20 is an annular member with a single opening. By expanding the diameter using this opening, it can be easily installed in the annular groove 2d of the piston rod 2. This C-ring 20 with a single opening also falls within the annular range.

[0021] The annular piston 3 is mounted on the small-diameter portion 2a of the piston rod 2 and is movably inserted into the cylinder body 1. Its outer periphery is in sliding contact with the inner periphery of the cylinder body 1, dividing the interior of the cylinder body 1 into an expansion-side chamber R1 and a compression-side chamber R2, both of which are filled with a liquid such as hydraulic oil. The liquid may be other liquids besides hydraulic oil, such as water or an aqueous solution. Furthermore, a gas may be used in place of the liquid.

[0022] More specifically, the piston 3 comprises: a main body 3a which is annular and fits into the outer periphery of the small diameter portion 2a of the piston rod 2 and has a port 3b for communicating the expansion side chamber R1 with the compression side chamber R2; a cylindrical portion 3c which extends from the main body 3a to the outside of the small diameter portion 2a of the piston rod 2; Figure 1 The lower end of the outer circumference Figure 1 sealing ring 3d, which is mounted on the outer periphery of the cylindrical portion 3c, and in sliding contact with the inner periphery of the cylinder 1.

[0023] The piston 3 is fixed to the piston rod 2 by being clamped by the piston nut 15 which is threadedly coupled to the threaded portion 2b at the front end of the piston rod 2 and the step portion 2c of the piston rod 2. Figure 1 An annular collar 17 having an L-shaped cross section is sandwiched between the upper portion of the piston rod 2 and the step portion 2c. A check valve 18 for opening or closing the port 3b is installed on the outer periphery of the collar 17 and is composed of a plurality of stacked annular plates with different diameters.

[0024] The check valve 18 is stacked on the piston 3 Figure 1 The upper end side of the closed port 3b Figure 1 Specifically, when the piston 3 moves relative to the cylinder 1, the upper end of the piston 3b can be opened or closed. Figure 1 When the check valve 18 moves downward in the direction of contraction, that is, when the check valve 18 moves downward in the direction of contraction, the pressure of the compression chamber R2 acting through the port 3b is pressed against the check valve 18 and the check valve 18 bends, thereby opening the port 3b and allowing the liquid to flow from the compression chamber R2 to the extension chamber R1. Figure 1 When the check valve 18 moves upward in the expansion direction, that is, in the expansion direction, the check valve 18 is subjected to the pressure from the expansion-side chamber R1 and closes the port 3b, thereby preventing the liquid from flowing from the expansion-side chamber R1 to the compression-side chamber R2 through the port 3b. In this way, the port 3b provided with the check valve 18 functions as a rectifying passage P1, which allows the liquid to flow from the compression-side chamber R2 to the expansion-side chamber R1 and prevents the liquid from flowing from the expansion-side chamber R1 to the compression-side chamber R2.

[0025] Next, the cover member 10 is annular and has a Figure 1 The annular recess 10a at the lower end of the annular recess 10a, the annular sealing member 10b mounted on the inner periphery of the annular recess 10a, the cylindrical sleeve 10c mounted on the inner periphery of the sealing member 10b, the cover member 10 Figure 1 The cover member 10 is fixed to the outer tube 12 together with the cylinder body 1 by being clamped by the nut 19 and the bottom cover 13. Therefore, it is immovable in the axial direction relative to the cylinder body 1 and can function as a stopper. In addition, the inner periphery of the cover member 10 is axially opposite to the C-ring 20 used as a limiting member installed on the outer periphery of the piston rod 2. When the cover member 10 and the C-ring 20 are in contact, the piston 3 can be limited in the extension direction relative to the cylinder body 1, that is, in the direction of extension. Figure 2 Move above in.

[0026] The piston rod 2 is inserted into the inner periphery of the cover member 10 and is in sliding contact with the inner periphery of the sealing member 10b and the inner periphery of the sleeve 10c. The sealing member 10b is in sliding contact with the outer periphery of the piston rod 2 and seals the outer periphery of the piston rod 2. The sleeve 10c is in sliding contact with the outer periphery of the piston rod 2 and guides the movement of the piston rod 2 in the axial direction, that is, in the vertical direction relative to the cylinder body 1. Figure 1 A sealing ring 10f is installed on the outer periphery of the upper end of the cover 10 so as to be in close contact with the inner periphery of the outer tube 12, thereby sealing the cover 10 and the outer tube 12. Figure 1 An annular sealing member 19a is provided on the inner periphery of the upper nut 19 in the middle, in sliding contact with the outer periphery of the piston rod 2. The sealing members 10b, 19a, and the sealing ring 10f seal the interior of the buffer D, thereby preventing leakage of liquid and gas from the buffer D.

[0027] The annular recess 10a opens at the lower end of the inner periphery of the cover member 10 and forms an annular gap with the piston rod 2. Figure 2 The upper end, i.e. the top 10a1, is a curved surface. Figure 2 The inner diameter decreases as it moves upward. Furthermore, the diameter φA of the annular recess 10a is larger than the sum of the bottom diameter φB of the annular groove 2d of the piston rod 2 and twice the diameter φD of the C-ring 20, but smaller than the sum of twice the cross-sectional diameter φD of the C-ring 20 and the outer diameter φC of the large-diameter portion 2e of the piston rod 2, to allow the C-ring 20 to fit into the annular recess 10a while being attached to the outer circumference of the piston rod 2.

[0028] When the buffer D is extended, and the piston 3 moves relative to the cylinder 1 in the extension direction, that is, Figure 2 When the piston 3 moves upward in the cylinder 1, the C-ring 20 enters the annular recess 10a of the cover member 10. Furthermore, if the buffer D continues to extend, the C-ring 20 contacts the top 10a1 of the annular recess 10a, and the upward movement of the piston 3 relative to the cylinder 1 is restricted. Since the top 10a1 of the annular recess 10a is a curved surface, when it contacts the C-ring 20, the piston 3 is restricted from contacting the C-ring 20. Figure 1The upper outer periphery of the C-ring 20 is in surface contact, and when the top 10a1 contacts the C-ring 20, the top 10a1 only contacts the upper end of the C-ring 20, and there is no excessive load on the part of the C-ring 20. Therefore, the aging of the C-ring 20 can be suppressed. Moreover, when the top 10a1 and the C-ring 20 contact each other, the component force acts from the top 10a1 in the direction of reducing the diameter of the C-ring 20. Therefore, when a collision occurs between the top 10a1 and the C-ring 20, the C-ring 20 does not expand in diameter, and thus the movement of the buffer D in the extension direction can be stably restricted. In this way, the stopper S has the top 10a1 axially opposite to the C-ring 20 as the limiting component and the annular recess 10a that allows the C-ring 20 to enter, which is closer to the sleeve 10c in the cover component 10. Figure 1 Below and with cylinder 1 Figure 1 The portion that engages with the upper end of the stopper S is formed by a portion including an annular recess 10a formed around the axis of the piston rod 2 on the end side facing the expansion-side chamber R1. As described above, in this embodiment, the stopper S is integral with the cover member 10 and forms a part of the cover member 10, and the annular recess 10a is also provided around the axis of the piston rod 2 on the end side facing the expansion-side chamber R1.

[0029] In addition, since the radius of the annular recess 10a is smaller than the value obtained by adding the diameter of the cross section of the C-ring 20 and the radius of the outer diameter of the piston rod 2, even if the diameter of the C-ring 20 entering the annular recess 10a is expanded, it will be restricted by the inner wall of the annular recess 10a of the cover member 10, which can prevent the inner diameter of the C-ring 20 from being larger than the outer diameter of the piston rod 2. Therefore, the C-ring 20 will not fall off from the annular groove 2d.

[0030] Furthermore, a pipeline 21 housed in the liquid storage chamber R is embedded in the vertical hole 10d of the cover member 10. The pipeline 21 is fixed in place in the vertical hole 10d of the cover member 10 by press-fitting, welding, or gluing, and its lower end is sufficiently long to ensure that it is always disposed below the liquid level in the liquid storage chamber R.

[0031] The channel 10e is connected to the extension side chamber R1 through the annular recess 10a, and is connected to the liquid storage chamber R through the interior of the pipeline 21, forming a damping channel DP together with the pipeline 21. Specifically, Figure 2 As shown, the passage 10e includes a hole 10e1 extending from the annular recess 10a, a valve hole 10e2 accommodating the damping valve V through the hole 10e1, and a hole 10e3 connecting the valve hole 10e2 with the interior of the pipeline 21 fitted in the vertical hole 10d.

[0032] The damping valve V includes an annular valve seat 30 disposed in the valve hole 10e2, which can be Figure 2The valve body 31 is housed in the valve hole 10e2, movably disposed therein and seated on the annular valve seat 30. The valve body 31 is also seated therein, and a spring 32 biases the valve body 31 toward the annular valve seat 30. The damping valve V opens and resists the flow of liquid from the expansion-side chamber R1 through the damping passage DP to the liquid reservoir R. However, the damping passage DP is closed to liquid flowing from the liquid reservoir R to the expansion-side chamber R1. Thus, the damping passage DP is configured as a one-way passage that allows only liquid flow from the expansion-side chamber R1 to the liquid reservoir R via the damping valve V.

[0033] Next, the valve housing 11 is provided with a suction passage P2 that connects the reservoir R and the compression-side chamber R2. The suction passage P2 is provided with a suction check valve 22 that allows hydraulic oil to flow only from the reservoir R to the compression-side chamber R2 and prevents reverse flow. The suction passage P2 is configured as a one-way passage that allows hydraulic oil to flow only from the reservoir R to the compression-side chamber R2.

[0034] The operation of the buffer D will be described below. The buffer D constructed as described above is placed longitudinally and clamped between the bogie and the wheel of the railway vehicle. When the buffer D is clamped between the bogie and the wheel for use, the buffer D bears the weight of the railway vehicle body and the bogie together with the parallel axle spring. Even if it travels to the maximum extension side, the stopper S installed on the piston rod 2 will not come into contact with the C-shaped ring 20 used as a limiting component. In this way, the buffer D is usually clamped between the bogie and the wheel for use. In this case, as long as the piston 3 travels within the stroke range, that is, the normal stroke range E relative to the cylinder body 1, the stopper will not come into contact with the limiting component to limit the extension of the buffer D. In addition, in Figure 1 In the figure, the normal stroke range E represents the range from the upper limit that the upper end of the piston 3 can reach when the piston 3 is displaced relative to the cylinder 1 in a direction compressing the expansion-side chamber R1 to the lower limit that the lower end of the piston 3 can reach when the piston 3 is displaced relative to the cylinder 1 in a direction compressing the compression-side chamber R2 under normal use. Even when the piston 3 moves relative to the cylinder 1 within the normal stroke range E, the piston 3 does not contact the cover member 10 including the stopper S and the valve housing 11, and the C-ring 20 does not contact the stopper S.

[0035] First, the operation of the shock absorber D when the piston 3 is traveling relative to the cylinder 1 within the normal travel range E will be described. Figure 1 When the buffer D extends, the piston 3 moves upward relative to the cylinder 1. Figure 1 As the cylinder moves upward, the expansion-side chamber R1 is compressed and the compression-side chamber R2 is expanded.

[0036] In this situation, since the check valve 18 closes port 3b, shutting off the rectifying passage P1, the liquid in the expansion-side chamber R1 flows through the damping valve V of the damping passage DP and is discharged into the reservoir R. Because the damping valve V resists this flow of liquid, the pressure in the expansion-side chamber R1 rises to a level higher than that in the reservoir R. Furthermore, the volume of the compression-side chamber R2 expands due to the movement of the piston 3, creating a shortage of hydraulic oil. This shortage is then supplied from the reservoir R to the compression-side chamber R2 through the suction passage P2 due to the opening of the suction check valve 22. Consequently, the pressure in the compression-side chamber R2 becomes approximately equal to that in the reservoir R.

[0037] As a result, when the damper D extends, the pressure in the expansion-side chamber R1 acting on the side of the piston 3 in the expansion-side chamber R1 becomes higher than the pressure in the compression-side chamber R2 acting on the side of the piston 3 in the compression-side chamber R2. This generates an extension-side damping force that hinders its extension. Furthermore, hydraulic oil equivalent to the volume of the piston rod 2 withdrawn from the cylinder 1 is supplied from the reservoir R to the compression-side chamber R2 to compensate for the volume of the piston rod 2 withdrawn from the cylinder 1. Furthermore, the fluid flowing from the expansion-side chamber R1 through the damping passage DP is discharged into the liquid in the reservoir R through the line 21 and does not come into contact with the gas in the reservoir R, thereby preventing the entrapment of gas in the liquid in the reservoir R. When the buffer D extends, the liquid moves from the liquid storage chamber R to the cylinder 1 through the suction channel P2. Since it is possible to prevent gas from being drawn into the liquid in the liquid storage chamber R, it is possible to prevent gas from entering the cylinder 1, thereby causing the damping force generated by the buffer D to become unstable.

[0038] Next, when the piston rod 2 is relative to the cylinder 1 Figure 1 The operation when the buffer D moves downward and the buffer D contracts will be described. When the buffer D contracts, the piston 3 moves relative to the cylinder 1. Figure 1 As the chamber moves downward in the center, the compression-side chamber R2 is compressed and the expansion-side chamber R1 is expanded.

[0039] At this time, since the check valve 18 is opened and the port 3b is opened to connect the extension side chamber R1 and the compression side chamber R2 through the rectification channel P1, and the suction check valve 22 is closed to cut off the suction channel P2, the liquid in the compression side chamber R2 moves toward the extension side chamber R1 through the rectification channel P1.

[0040] Furthermore, when the shock absorber D contracts, the piston rod 2 enters the cylinder 1, creating an excess of liquid within the cylinder 1 equal to the volume of the piston rod 2 entering the cylinder 1. This excess liquid within the cylinder 1 flows through the damping valve V in the damping passage DP and is discharged into the reservoir R. Because the damping valve V resists the flow of hydraulic oil, the pressure within the expansion-side chamber R1 rises to a level higher than that within the reservoir R. Furthermore, because the compression-side chamber R2 is connected to the expansion-side chamber R1 via the rectifying passage P1, the pressure within the compression-side chamber R2 is substantially equal to that within the expansion-side chamber R1.

[0041] As a result, when the shock absorber D contracts, the pressure in the expansion-side chamber R1 acting on the side of the piston 3 increases by approximately the same amount as the pressure in the compression-side chamber R2 acting on the side of the piston 3. However, because the area receiving the pressure in the expansion-side chamber R1 of the piston 3 is smaller than the area receiving the pressure in the compression-side chamber R2, the shock absorber D generates a compression-side damping force that hinders its contraction. Furthermore, a volume of liquid equivalent to the volume of the piston rod 2 entering the cylinder 1 is discharged from the cylinder 1 into the reservoir R, compensating for the volume of the piston rod 2 entering the cylinder 1. This generates a damping force during the shock absorber D's expansion and contraction, thereby suppressing vibrations of the object being damped.

[0042] Thus, the damper D is a single-flow type damper, that is, no matter whether it is performing an extension action or a contraction action, the liquid will flow through the damping valve V of the damping channel DP and generate a damping force.

[0043] Next, if the car body of the railway vehicle is removed from the bogie for maintenance, the axle spring supporting the car body is extended. Therefore, the buffer D is stretched to its maximum length, and the piston 3 moves toward the extension side relative to the cylinder 1 and exceeds the normal stroke range E. The C-ring 20 used as a limiting member mounted on the outer periphery of the piston rod 2 enters the annular recess 10a of the stopper S provided on the cover member 10 and abuts against the top 10a1, thereby limiting the movement of the piston 3 toward the extension side relative to the cylinder 1.

[0044] In this way, the C-ring 20 installed on the outer periphery of the piston rod 2 abuts against the top 10a1 of the annular recess 10a of the stopper S, thereby limiting the extension of the buffer D. Therefore, the stopper S will not collide with the piston 3 or the check valve 18, and can prevent excessive shear load from acting on the joint between the piston nut 15 and the threaded portion 2b.

[0045] Therefore, in the shock absorber D of the present embodiment, deformation of components such as the piston 3 and the check valve 18 and fatigue of the piston rod 2 due to an excessive load can be prevented.

[0046] As described above, the buffer D of this embodiment is a buffer D having a cylinder body 1, a piston rod 2 which can be freely movably inserted into the cylinder body 1, and a piston 3 which is inserted into the cylinder body 1 and divides the interior of the cylinder body 1 into an extension side chamber R1 and a compression side chamber R2. The buffer D also has a stopper S which is immovable relative to the cylinder body 1 in the axial direction of the cylinder body 1 and a C-ring (limiting component) 20. The C-ring is arranged on the piston rod 2 and is opposite to the stopper S in the axial direction of the cylinder body 1. When the C-ring abuts against the stopper S, it can limit the movement of the piston 3 in the extension direction relative to the cylinder body 1.

[0047] With the shock absorber D thus constructed, when the shock absorber is stretched to its maximum length during bogie maintenance, for example, the C-ring (limiting member) 20 attached to the piston rod 2 abuts against the stopper S, which is immovable relative to the cylinder 1, limiting its extension. Consequently, the load in the direction of extension is borne by the C-ring (limiting member) 20 and the stopper S, preventing excessive loads from acting on the stopper S and piston 3, the check valve 18 assembled on the piston 3, or the threaded connection between the piston nut 15 and the piston rod 2. Therefore, the shock absorber D of this embodiment can suppress deformation and fatigue even when stretched to its maximum length.

[0048] Alternatively, the stopper S may be immovably held relative to the cylinder body 1, and a restricting member may be provided relative to the piston rod 2 so that, when the shock absorber D is stretched to its maximum length, it abuts the stopper S before the piston 3 or the check valve 18 interferes with the cover member 10. Therefore, in the shock absorber D of this embodiment, the stopper S is the cover member 10, and the restricting member is the C-ring 20. However, as long as the stopper S is directly or indirectly attached to the cylinder body 1 and immovably held relative to the cylinder body 1, the stopper S may be a member separate from the cover member 10, and the restricting member may be provided on the piston rod 2, as long as no load is applied to the piston 3 when it abuts the stopper S. The restricting member may also be formed of a member other than the C-ring 20.

[0049] Therefore, the stopper S can also be a pin or a C-ring immovably mounted on the cylinder body 1, and the limiting component can be designed into any shape and structure, as long as it corresponds to the shape or structure of the stopper S and can limit the extension of the buffer D when it abuts against the stopper S.

[0050] Furthermore, in the shock absorber D of this embodiment, the C-ring (restriction member) 20 abuts against the stopper S when the piston 3 moves relative to the cylinder 1 in the extension direction beyond the normal stroke range E. With the shock absorber D thus configured, the C-ring (restriction member) 20 does not interfere with the stopper S when the piston 3 moves relative to the cylinder 1 within the normal stroke range E. Therefore, even when the shock absorber D is used between a bogie and a wheel of a railway vehicle, the C-ring (restriction member) 20 does not collide with the stopper S, thereby preventing a reduction in the ride comfort of the railway vehicle.

[0051] Furthermore, in the buffer D of this embodiment, the C-ring (limiting component) 20 is annular and is installed on the outer periphery of the piston rod 2, and the stopper S is annular. There is an annular recess 10a for inserting the C-ring (limiting component) 20 around the axis of the piston rod 2 on the end side facing the extension side chamber R1, which is arranged on the cover component 10. The cover component can close the side end of the extension side chamber of the cylinder body 1 and axially support the piston rod 2. When the C-ring (limiting component) 20 abuts against the top 10a1 of the annular recess 10a of the stopper S, the movement of the piston 3 in the extension direction relative to the cylinder body 1 is restricted.

[0052] According to the shock absorber D constructed in this manner, since the stopper S serves as the cover member 10 required for the shock absorber D, and the C-ring (limiting member) 20 is attached to the outer circumference of the piston rod 2, the only additional component required in the shock absorber D is the C-ring (limiting member) 20. This is low-cost and easy to attach to the piston rod 2, minimizing the increase in cost. Furthermore, according to the shock absorber D of this embodiment, the extension of the shock absorber D is limited by providing the annular recess 10a and allowing the top portion 10a1 to abut against the C-ring (limiting member) 20. Therefore, even if the C-ring (limiting member) 20 is attached to the piston rod 2, the annular recess 10a is provided on the cover member 10 side for the C-ring (limiting member) 20 to enter. This allows the stroke length of the shock absorber D to be maintained, compared to a case where the C-ring (limiting member) 20 abuts against the end of the cover member 10 to limit the extension of the shock absorber D without providing the annular recess 10a. Therefore, according to the buffer D of this embodiment, not only can deformation or fatigue be suppressed even when stretched to its maximum length, but the only component that needs to be added to the buffer D is the C-ring (limiting member) 20, which is low in cost and easy to install on the piston rod 2, thereby suppressing cost increases. In addition, since the annular recess 10a is provided for the C-ring (limiting member) 20 to enter, it is easier to ensure the stroke length than in a case where the annular recess 10a is not provided and the C-ring (limiting member) 20 is abutted against the end of the cover member 10 to limit the extension of the buffer D.

[0053] In addition, in the above case, the C-ring (limiting member) 20 contacts the top 10a1 of the annular recess 10a of the stopper S, thereby limiting the movement of the piston 3 relative to the cylinder 1 in the extension direction. However, the deeper the annular recess 10a is, the deeper the annular recess 10a is. Figure 2 Above the annular recess 10a, the inner diameter of the annular recess 10a gradually becomes smaller, and the inner peripheral surface of the annular recess 10a becomes a tapered surface with a tapered front end. In this case, the movement of the piston 3 relative to the cylinder body 1 in the extension direction can also be limited by the C-ring (limiting component) 20 abutting against the inner peripheral surface of the annular recess 10a.

[0054] Furthermore, in the buffer D of this embodiment, the limiting component is a C-ring 20 with a circular cross-section, which is engaged with an annular groove 2d circumferentially arranged on the outer periphery of the piston rod 2. The diameter of the annular recess 10a on the stopper S is smaller than the value obtained by adding twice the length of the diameter of the cross-section of the C-ring 20 and the diameter of the outer diameter of the piston rod 2, and the top 10a1 has a curved surface that is in surface contact with the C-ring 20.

[0055] According to the shock absorber D constructed in this manner, since the top portion 10a1 has a curved surface that comes into surface contact with the C-ring 20, when the top portion 10a1 and the C-ring 20 come into contact, the top portion 10a1 only abuts the upper end of the C-ring 20, and an excessive load is not applied to a portion of the C-ring 20. Therefore, deterioration of the C-ring 20 can be suppressed. Moreover, even if the C-ring 20 enters the annular recess 10a and abuts the top portion 10a1, the C-ring 20 is subjected to a load pushed toward the piston 3 relative to the piston rod 2, causing it to expand in diameter and almost fall out of the annular groove 2d. However, when the top portion 10a1 and the C-ring 20 come into contact, a force in a direction of reducing the diameter acts on the C-ring 20, so that the C-ring does not expand in diameter but is restrained by the inner wall of the annular recess 10a of the cover member 10, thereby preventing the inner diameter of the C-ring 20 from becoming larger than the outer diameter of the piston rod 2. Therefore, the C-ring 20 is prevented from falling out of the annular groove 2d.

[0056] Furthermore, the buffer D of this embodiment includes: an outer tube 12, which covers the cylinder body 1 and forms an annular liquid storage chamber R between the outer tube 1 and the cylinder body 1 for storing liquid; a damping channel DP, which is arranged on the cover part 10 and connects the extension side chamber R1 and the liquid storage chamber R through the annular recess 10a; a damping valve V, which is arranged on the damping channel DP and only allows liquid to flow from the extension side chamber R1 to the liquid storage chamber R, and applies resistance to the flow of the liquid; a suction channel P2, which connects the liquid storage chamber R and the compression side chamber R2 and only allows liquid to flow from the liquid storage chamber R to the compression side chamber R2; a rectifying channel P1, which connects the compression side chamber R2 and the extension side chamber R1 and only allows liquid to flow from the compression side chamber R2 to the extension side chamber R1. The buffer D constructed in this manner includes a damping passage DP that connects the annular recess 10a provided on the stopper S with the fluid storage chamber R, and a damping valve V on the damping passage DP. By utilizing the structure of a single-flow buffer in which the damping passage DP is provided on the cover member 10 and the annular recess 10a is originally provided on the inner periphery, the elongation of the buffer D can be limited by merely providing a C-ring 20 on the outer periphery of the piston rod 2. Therefore, the elongation of the buffer D can be limited by making minimal design changes to the buffer D of the existing structure.

[0057] Furthermore, if an expansion-side damping passage for applying resistance to the liquid flowing from the expansion-side chamber R1 to the compression-side chamber R2 is provided on the piston 3 of the damper D, and a compression-side damping passage for applying resistance to the liquid flowing from the compression-side chamber R2 to the liquid storage chamber R is provided on the valve housing 11, it is not necessary to use a double-flow type damper in which the expansion-side chamber R1 and the liquid storage chamber R are connected by the damping passage DP through the annular recess 10a, or even if a single-flow type is used but the damping passage DP is not required to be connected to the annular recess 10a, as in the example Figure 3 As shown, the buffer D can also be provided with a pressure chamber PR formed in the annular recess 10a of the stopper S by a limiting component 40 installed on the outer periphery of the piston rod 2, and a limiting flow passage P3 that is connected to the pressure chamber PR and the extension side chamber R1 and applies resistance to the flow of the fluid flowing from the pressure chamber PR to the extension side chamber, so that the pressure in the pressure chamber PR increases, and the piston 3 is reduced relative to the cylinder 1 by the action of the pressure. Figure 3 The speed at which the upper side, i.e. the extension side, moves.

[0058] Specifically, the restriction member 40 is configured so that its outer circumferential surface faces the inner circumferential surface of the annular recess 10a of the stopper S with an extremely small gap. When the liquid enters the annular recess 10a, it resists the flow of the liquid as it passes through the gap between the outer circumferential surface of the restriction member 40 and the inner circumferential surface of the annular recess 10a. With the damper D thus configured, when the restriction member 40 enters the annular recess 10a, the restriction member 40 forms a pressure chamber PR within the annular recess 10a, separated from the expansion-side chamber R1. This pressure chamber PR communicates with the expansion-side chamber R1 via a restriction flow path P3 formed by the narrow gap between the outer circumferential surface of the restriction member 40 and the inner circumferential surface of the annular recess 10a. Since the restriction flow path P3 exerts resistance on the liquid flowing from the pressure chamber PR to the expansion side chamber R1, it is difficult for the liquid to move from the annular recess 10a to the expansion side chamber R1, causing the pressure in the annular recess 10a to rise. In this state, if the shock absorber D continues to extend, the pressure in the annular recess 10a increases, and this pressure exerts pressure on the restriction member 40. Figure 3 The downward force in the cylinder 1 is counteracted, and the hydraulic lock is activated, exerting resistance to prevent the piston 3 from moving upward relative to the cylinder 1, thereby suppressing its extension. Therefore, the shock absorber D constructed in this manner can reduce the extension speed when extending to its maximum length, thereby preventing the cover member (stopper) 10 from violently colliding with the limiting member 40 and reducing the impact force generated when the cover member (stopper) 10 and the limiting member 40 collide. When the limiting component 40 enters the annular recess 10a, the limiting flow channel P3 connects the pressure chamber PR divided in the annular recess 10a with the extension side chamber R1. In addition to being formed by the gap between the outer peripheral surface of the limiting component 40 and the inner peripheral surface of the annular recess 10a, it can also be formed by a groove or a hole of the limiting component 40 formed axially along the outer periphery of the limiting component 40 or the inner periphery of the annular recess 10a, or even a channel that opens on the end face of the extension side chamber R1 facing the guide 10 and communicates with the annular recess 10a.

[0059] Furthermore, in this embodiment, the case where the buffer D is interposed between the bogie and wheels of a railway vehicle is described as an example. However, the buffer D can also be used for other purposes other than railway vehicles in which it is placed longitudinally.

[0060] While the preferred embodiments of the present invention have been described in detail above, modifications, variations, and alterations may be made without departing from the scope of the claims.

[0061] Explanation of symbols

[0062] 1 cylinder

[0063] 2 piston rod

[0064] 3 pistons

[0065] 10 Cover assembly

[0066] 10a annular recess

[0067] 10a1 top

[0068] 12 outer cylinder

[0069] 20 C-ring (limiting part)

[0070] 30 Restricted parts

[0071] D-buffer

[0072] DP damping channel

[0073] E Normal travel range

[0074] P1 rectifier channel

[0075] P2 suction channel

[0076] P3 restricted flow channel

[0077] PR pressure chamber

[0078] R reservoir

[0079] R1 elongated side chamber

[0080] R2 compression side chamber

[0081] S stop

Claims

1. A buffer, It has a cylinder, a piston rod movably inserted into the cylinder, and a piston inserted into the cylinder to divide the interior of the cylinder into an extension side chamber and a compression side chamber. A stopper is also provided which is immovable relative to the cylinder in the axial direction of the cylinder. and a limiting component, which is provided on the piston rod and is opposite to the stopper in the axial direction of the cylinder body, and can limit the movement of the piston relative to the cylinder body in the extension direction when the limiting component abuts against the stopper.

2. The buffer according to claim 1, wherein When the piston moves in the extension direction relative to the cylinder beyond a normal stroke range, the limiting member abuts against the stopper.

3. The buffer according to claim 1, wherein The limiting member is annular and mounted on the outer periphery of the piston rod. The stopper is annular and has an annular recess around the axis of the piston rod facing the end side of the extension side chamber, allowing the restriction member to be inserted. The stopper is provided on an annular cover member that can close the extension side chamber side end of the cylinder body and axially support the piston rod. When the restricting member contacts the inner peripheral surface or the top portion of the annular recess on the stopper, movement of the piston relative to the cylinder in the extension direction is restricted. The buffer according to claim 3 , wherein: The limiting member is a C-shaped ring with a circular cross section, and the C-shaped ring is engaged with an annular groove provided circumferentially on the outer periphery of the piston rod. The diameter of the annular recess on the stopper is smaller than the sum of twice the cross-sectional diameter of the C-shaped ring and the outer diameter of the piston rod. The top portion includes a curved surface that makes surface contact with the C-shaped ring.

5. The buffer according to claim 3, The buffer has: an outer cylinder covering the cylinder body and forming an annular liquid storage chamber for storing liquid between the outer cylinder and the cylinder body; a damping channel provided on the cover member and connecting the extension side chamber and the liquid storage chamber via the annular recess; a damping valve disposed on the damping passage and configured to only allow liquid to flow from the extension side chamber to the liquid storage chamber and to apply resistance to the flow of the liquid; a suction passage connecting the liquid storage chamber and the compression-side chamber and allowing only liquid to flow from the liquid storage chamber to the compression-side chamber; A rectifying passage connects the compression-side chamber and the extension-side chamber and only allows liquid to flow from the compression-side chamber to the extension-side chamber.

6. The buffer according to claim 3, The buffer has: a pressure chamber formed in the annular recess by the restriction member entering the annular recess; A restriction flow passage communicates with the pressure chamber and the extension-side chamber and applies resistance to the flow of fluid from the pressure chamber to the extension-side chamber.

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