Buffer and buffer assembly method

Abstract

The shock absorber comprises a cylinder; a rod movably inserted into the cylinder; a piston inserted into the cylinder and dividing the cylinder into an expansion-side chamber and a compression-side chamber; and an annular sealing member mounted on the outer circumference of the piston and in sliding contact with the inner circumference of the cylinder. The piston comprises a first piston segment that is axially split and a second piston segment that axially opposes the first piston segment. The sealing member is accommodated in an annular recess provided on the outer circumference of the first piston segment on the side of the split surface. In the shock absorber assembly method, the sealing member is preliminarily accommodated in the annular recess, and then the first and second piston segments are overlapped.

Description

Technical Field

[0001] The present invention relates to a buffer and a method for assembling the buffer. Background Art

[0002] The buffer, for example, comprises: a cylinder; a piston rod that can be movably inserted into the cylinder; a piston that is connected to the piston rod while being slidably inserted into the cylinder; an extension side chamber and a compression side chamber that are filled with hydraulic oil while dividing the cylinder by the piston; an outer tube that covers the outer periphery of the cylinder and forms a reservoir for storing hydraulic oil between the cylinders; a damping channel that only allows hydraulic oil to flow from the extension side chamber to the reservoir and applies resistance to the flow of the hydraulic oil passing through; a rectifying channel that is provided on the piston and only allows hydraulic oil to flow from the compression side chamber to the extension side chamber; and a suction channel that only allows hydraulic oil to flow from the reservoir to the compression side chamber.

[0003] The shock absorber constructed in this way is set as a single-phase shock absorber in which the hydraulic oil flows through the reservoir, the compression side chamber, the extension side chamber in sequence and reaches the reservoir during the extension and contraction movement. The shock absorber applies resistance to the flow of hydraulic oil discharged from the cylinder to the reservoir through the damping channel, and generates a damping force that hinders extension and contraction.

[0004] The pressure in the expansion-side chamber and the pressure in the compression-side chamber, defined by the piston, act on the piston to generate a damping force that hinders its movement. However, if the shock absorber is configured as a single-phase shock absorber, a pressure difference between the expansion-side chamber and the compression-side chamber is required to generate the damping force during contraction. If the shock absorber is configured as a bidirectional shock absorber, a pressure difference between the expansion-side chamber and the compression-side chamber is required to generate the damping force during both contraction and extension movements, or during extension.

[0005] Therefore, when hydraulic oil flows between the cylinder and the piston outside the port provided on the piston, the difference between the pressure of the expansion-side chamber and the pressure of the compression-side chamber does not conform to the designed value, and the shock absorber cannot generate the damping force as expected.

[0006] Therefore, as disclosed in JP2015-224780A, the shock absorber includes a sealing member formed into an annular shape from a synthetic resin or the like. This sealing member is mounted in an annular groove on the outer periphery of the piston while in sliding contact with the inner periphery of the cylinder. This sealing member seals the space between the cylinder and the piston, preventing hydraulic oil from flowing between the two areas beyond the port provided on the piston. Summary of the Invention

[0007] For example, if a railway vehicle or structure is used as the vibration reduction target, the buffer is set between the body of the railway vehicle and the trolley, or between the bodies of adjacent railway vehicles, between the elastically supported structure and the foundation, or between the columns and beams of the structure, and is used to attenuate the vibration of the vibration reduction target.

[0008] As previously mentioned, when the shock absorber is used to dampen heavy objects such as railway vehicles or structures, it is necessary to generate a high damping force to suppress the vibrations of the object. Increasing the shock absorber's damping force to meet this requirement requires increasing the pressure difference between the expansion-side chamber and the compression-side chamber. Therefore, the seal member located on the outer periphery of the piston must be strong enough to withstand this high pressure. However, increasing the strength of the seal member results in a high elastic modulus and difficulty in stretching.

[0009] To install the sealing member in the annular groove on the piston's outer circumference, the sealing member's diameter is expanded to allow the piston to be inserted into the sealing member. The sealing member is then moved along the piston's outer circumference to a position facing the annular groove. The sealing member then contracts in diameter due to its own restoring force and is accommodated in the piston's annular groove.

[0010] When this method of attaching the sealing member to the piston is employed, as previously described, increasing the strength of the sealing member, which makes it difficult to extend, makes it difficult to insert the piston into the sealing member. Furthermore, when maintaining the buffer, the sealing member must be removed from the piston, but this difficulty is compounded by the difficulty of extending the sealing member. In other words, increasing the strength of the sealing member makes it difficult to attach or detach the sealing member to the piston, and the buffer's assembly and disassembly performance deteriorates.

[0011] Furthermore, when an attempt is made to forcibly fit the sealing member into the annular groove of the piston, the sealing member may be damaged and the sealing performance may also be deteriorated.

[0012] Therefore, an object of the present invention is to provide a shock absorber and a shock absorber assembling method that allow a sealing member to be easily attached to or detached from a piston even if the strength of the sealing member is increased.

[0013] In order to solve the above-mentioned problem, the buffer of the present invention comprises: a cylinder; a rod which can be movably inserted into the cylinder; a piston which is inserted into the cylinder and divides the cylinder into an extension side chamber and a compression side chamber; and an annular sealing component which is mounted on the outer periphery of the piston and is in sliding contact with the inner periphery of the cylinder; the piston comprises a first piston split body and a second piston split body opposite to the first piston split body; one or both of the first piston split body and the second piston split body have an annular recess which is formed on the outer periphery of the split surface side where the first piston split body and the second piston split body face each other; the sealing component is accommodated in the annular recess. 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 a piston portion of a shock absorber in one embodiment.

[0016] Figure 3 This is a plan view of a second piston split body of a shock absorber in one embodiment.

[0017] Figure 4 This is an enlarged cross-sectional view of a piston portion of a shock absorber in a first modified example of an embodiment.

[0018] Figure 5 This is an enlarged cross-sectional view of a piston portion of a shock absorber in a second modified example of one embodiment. DETAILED DESCRIPTION

[0019] 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 rod 2 movably inserted into the cylinder 1; a piston 3 inserted into the cylinder 1 to divide the interior of the cylinder 1 into an expansion-side chamber R1 and a compression-side chamber R2; and a sealing member 4 attached to the outer periphery of the piston 3 and in sliding contact with the inner periphery of the cylinder 1. Furthermore, this shock absorber D is used, for example, by being installed between a vehicle body and a bogie in a railway vehicle (not shown) to suppress vibrations of the vehicle body and the bogie.

[0020] Next, each part of the buffer D will be described in detail. Figure 1 As shown, in cylinder 1 Figure 1 The left end of the cylinder is fitted with an annular rod guide 10. Figure 1 The right end is closed by the valve housing 11. In addition, the cylinder 1 is accommodated together with the valve housing 11. Figure 1 The right end is sealed by a bottom cover 13 in the outer tube 12. A reservoir R is formed between the cylinder 1 and the outer tube 12. The reservoir R is annular and stores fluids such as hydraulic oil together with gas.

[0021] Outer cylinder 12 Figure 1 The opening at the center left end is closed by a rod guide 10 mounted on an outer tube 12. Furthermore, the cylinder 1 and valve housing 11 are held by the rod guide 10 and the bottom cover 13 fixed to the outer tube 12, and are accommodated in the outer tube 12 and fixed relative to the outer tube 12.

[0022] The rod 2 is inserted into the cylinder 1 so as to be slidable through the rod guide 10 and is guided in the axial direction by the rod guide 10. The rod 2 includes a piston mounting portion 2a provided at a position as Figure 1 The front end of the middle right end has a small outer diameter and a piston 3 is mounted on the outer periphery; the threaded portion 2b is provided on the outer periphery of the front end of the piston mounting portion 2a; the first step portion 2c (refer to Figure 2 ), which connects the piston mounting portion 2a and the piston mounting portion 2a Figure 1 The left terminal; and the second step portion 2d (refer to Figure 2 ) and the third step portion 2e (refer to Figure 2 ), which is provided closer to the first step portion 2c Figure 1 Thus, in the shock absorber D of this embodiment, the rod 2 has a shape in which the outer diameter is divided into three small diameter stages at the front end side.

[0023] The annular piston 3 is mounted on the piston mounting portion 2a of the rod 2 and is movably inserted into the cylinder 1. It divides the interior of the cylinder 1 into an expansion-side chamber R1 and a compression-side chamber R2, which are filled with a fluid such as hydraulic oil. Furthermore, the fluid may be a liquid other than hydraulic oil, such as water or an aqueous solution. Furthermore, a gas may be used as the fluid in place of a liquid.

[0024] In this embodiment, the piston 3 is configured to include an axially divided first piston segment 31 and a second piston segment 32. The first piston segment 31 and the second piston segment 32 are both annular and are axially overlapped to form a single body to form the piston 3.

[0025] The first piston segment 31 includes an annular recess 31a formed in a circular ring shape and circumferentially formed on the first piston segment 31. Figure 2 The outer periphery of the dividing surface A1 side on the right end side is connected to the second piston split body 32. Figure 2 The dividing surface A2 side end is opposite to the left end; the annular groove 31b is formed circumferentially as Figure 2 an annular valve seat 31c, which protrudes in the axial direction from the reverse dividing surface B1 side end and surrounds the groove 31b; and a plurality of first ports 31d, which open on the dividing surface A1 and communicate with the groove 31b.

[0026] like Figure 2 and Figure 3 As shown, the second piston segment 32 comprises: an annular groove 32a, which is annular and formed on the outer periphery along the circumferential direction; an opening groove 32b, which is formed on the outer periphery along the circumferential direction through the annular groove. Figure 2The first piston segment 31 and the second piston segment 32 have the same outer diameter and an inner diameter that allows them to be mounted on the outer periphery of the piston mounting portion 2a of the rod 2. Furthermore, when the centers of the first and second piston segments 31 and 32 are aligned and the first piston segment 31 is axially superimposed on the second piston segment 32, the first ports 31d of the first piston segment 31 and the opening grooves 32b of the second piston segment 32 are arranged so as to face each other.

[0027] The first and second piston split bodies 31 and 32, constructed in this manner, are used with their split surfaces A1 and A2 facing each other and overlapping axially. After the piston mounting portion 2a of the rod 2 is inserted into the inner circumference of the first piston split body 31, the second piston split body 32 is screwed onto the threaded portion 2b formed on the outer circumference of the piston mounting portion 2a of the rod 2. The first piston split body 31 is thus clamped and secured to the rod 2 by the first step 2c of the rod 2 and the second piston split body 32. Furthermore, a piston nut 15 is screwed onto the front end of the threaded portion 2b, closer to the front end of the second piston split body 32. Thus, when the piston nut 15 is screwed onto the threaded portion 2b of the rod 2, the second piston split body 32 and the piston nut 15 form a double nut, preventing the second piston split body 32 from loosening and the piston 3 from falling off the rod 2. Alternatively, the piston 3 may be fixed to the rod 2 using only the piston nut 15, without providing a threaded groove on the inner circumference of the second piston split body 32. The first piston split body 31 and the second piston split body 32 fixed to the rod 2 in this manner are integrally held on the outer circumference of the piston mounting portion 2a of the rod 2 and cooperate with each other to function as the piston 3.

[0028] Furthermore, when the first piston segment 31 and the second piston segment 32 overlap, the first port 31d and the opening groove 32b face each other, and the first port 31d and the second port 32c communicate with each other, forming a passage 3a for connecting the expansion-side chamber R1 and the compression-side chamber R2. Furthermore, the number of first ports 31d and second ports 32c provided can be arbitrarily set.

[0029] Furthermore, when the first piston split body 31 and the second piston split body 32 overlap, the annular recess 31 a provided on the outer periphery of the first piston split body 31 faces the dividing surface A2 of the second piston split body 32 and forms an annular groove for surrounding the outer periphery of the piston 3 .

[0030] The annular groove formed by the annular recess 31a houses a sealing member 4 that is annular and seals the space between the cylinder 1 and the piston 3. The sealing member 4 comprises a seal ring 4a that is in sliding contact with the inner circumference of the cylinder 1 and an O-ring 4b disposed on the inner circumference of the seal ring 4a.

[0031] The seal ring 4a is made of synthetic resin and is in sliding contact with the inner circumferential surface of the cylinder 1. It has self-lubricating properties, preventing the flow of hydraulic oil between it and the cylinder 1 while not hindering the smooth movement of the piston 3. Furthermore, the O-ring 4b is in close contact with the inner circumferential surface of the seal ring 4a and the bottom surface of the annular recess 31a of the piston 3, sealing the gap between the seal ring 4a and the piston 3 to prevent the flow of hydraulic oil into the annular recess 31a. Thus, in the shock absorber D of this embodiment, the seal member 4 is composed of the seal ring 4a and the O-ring 4b, but it can also be composed of a single component.

[0032] In order to install the sealing component 4 on the outer periphery of the piston 3, before the first piston split body 31 and the second piston split body 32 are overlapped and integrated, the sealing component 4 can be accommodated in the annular recess 31a from the side of the split surface A1 of the first piston split body 31. Specifically, when assembling the first piston split body 31, the second piston split body 32 and the sealing component 4, the assembly can be carried out through the following steps. First, the first piston split body 31 is fitted into the outer periphery of the piston mounting portion 2a of the rod 2 and abutted against the first step portion (step portion) 2c. Next, the sealing component 4 is accommodated in the annular recess 31a of the first piston split body 31. After the step of accommodating the sealing member 4, the following steps are performed: the second piston split body 32 is fitted into the outer periphery 2a of the piston mounting portion, the first piston split body 31 and the second piston split body 32 are screwed onto the threaded portion 2b of the piston mounting portion 2a in an overlapping state, and then the first piston split body 31 and the second piston split body 32 are fixed to the piston rod 2. After performing these series of steps, the first piston split body 31, the second piston split body 32, and the sealing member 4 are assembled while being fixed to the rod 2.

[0033] In addition, since the dividing surface A1 side of the first piston segment 31 of the annular recess 31a is open, in the above-mentioned accommodation process, there is no need to enlarge the diameter of the sealing component 4 when installing the sealing component 4 into the annular recess 31a, and the sealing component 4 can be installed in the annular recess 31a without applying any load to the sealing component 4.

[0034] In this manner, after the sealing member 4 is assembled to the first piston divided body 31 , the first piston divided body 31 and the second piston divided body 32 are overlapped to form the piston 3 .

[0035] Furthermore, an annular piston ring 5 is mounted in an annular groove 32 a provided on the outer periphery of the second piston segment 32 , the annular piston ring 5 being in sliding contact with the inner periphery of the cylinder 1 and guiding the axial movement of the piston 3 .

[0036] As previously described, the piston 3 constructed in this manner is mounted on the outer periphery of the piston mounting portion 2a of the rod 2. Specifically, the coil spring 16, the annular valve body 17 formed of an annular plate, and the piston 3 are assembled in this order at the distal end of the rod 2. As previously described, the piston 3 is fixed to the outer periphery of the piston mounting portion 2a of the rod 2, with the first and second piston split bodies 31 and 32 in close contact with each other at their split surfaces A1 and A2.

[0037] In addition, the annular valve body 17 is annular, with an outer diameter larger than the annular valve seat 31c of the first piston segment 31, and is axially movable and embedded in the outer periphery between the first step 2c and the second step 2d of the rod 2. Moreover, the annular valve body 17 can move away from or toward the piston 3 in the axial direction. When it is in contact with the piston 3 and seated on the annular valve seat 31c, it closes the channel 3a, and when it is away from the piston 3, it opens the channel 3a. When the annular valve body 17 is in contact with the second step 2d, it moves further toward the piston 3. Figure 1 Movement to the center left is restricted, and the maximum lift away from the piston 3 is set by the location of the second step 2d. A coil spring 16 is installed between the third step 2e and the annular valve body 17 to urge the annular valve body 17 to contact the piston 3.

[0038] Therefore, in the buffer D of this embodiment, the piston 3, the coil spring 16 and the annular valve body 17 constitute a check valve. When the annular valve body 17 moves away from the annular valve seat 31c to open the channel 3a, only the hydraulic oil is allowed to flow from the compression side chamber R2 to the extension side chamber R1. When the hydraulic oil flows from the extension side chamber R1 to the compression side chamber R2, the annular valve body 17 is seated on the annular valve seat 31c to close the channel 3a.

[0039] Next, the rod guide 10 is provided with a discharge passage 10a for communicating between the expansion-side chamber R1 and the reservoir R. A damping valve 10b is provided in the discharge passage 10a. This damping valve allows only the flow of hydraulic oil from the expansion-side chamber R1 to the reservoir R, and applies resistance to the flow of the hydraulic oil passing therethrough while preventing reverse flow. The discharge passage 10a is configured as a one-way passage that allows only the flow of hydraulic oil from the expansion-side chamber R1 to the reservoir R.

[0040] Furthermore, the valve housing 11 is provided with a suction passage 11a for communicating the reservoir R with the compression-side chamber R2. A check valve 11b is provided on the suction passage 11a, which allows hydraulic oil to flow from the reservoir R to the compression-side chamber R2 and prevents reverse flow. The suction passage 11a is configured as a one-way passage that allows hydraulic oil to flow from the reservoir R to the compression-side chamber R2.

[0041] The buffer D is constructed in the above manner, and the operation of the buffer D will be described below. First, the rod 2 is moved relative to the cylinder 1. Figure 1 The following describes the action when the piston 3 moves to the left and the buffer D extends. When the buffer D extends, the piston 3 moves relative to the cylinder 1. Figure 1 As the center moves to the left, the expansion-side chamber R1 is compressed and the compression-side chamber R2 is expanded.

[0042] In this situation, the annular valve body 17 seats on the annular valve seat 31c, sealing the passage 3a provided in the piston 3. Therefore, the hydraulic oil in the expansion-side chamber R1 flows through the damping valve 10b of the discharge passage 10a and is discharged into the reservoir R. Because the damping valve 10b resists the movement of this hydraulic oil, the pressure in the expansion-side chamber R1 rises and becomes higher than the pressure in the reservoir R. Furthermore, the volume of the compression-side chamber R2 expands due to the movement of the piston 3, resulting in a shortage of hydraulic oil. However, this shortage is replenished by the opening of the check valve 11b, allowing the hydraulic oil to be supplied from the reservoir R via the suction passage 11a to the compression-side chamber R2. Consequently, the pressure in the compression-side chamber R2 becomes approximately equal to the pressure in the reservoir R.

[0043] When the damper D extends in this manner, the pressure in the expansion-side chamber R1, acting on the side of the expansion-side chamber R1 of the piston 3, becomes higher than the pressure in the compression-side chamber R2, acting on the side of the compression-side chamber R2 of the piston 3. Consequently, the damper D generates an extension-side damping force that hinders the extension. Furthermore, hydraulic oil from the reservoir R is supplied to the compression-side chamber R2, representing the volume of the rod 2 that has withdrawn from the cylinder 1, to compensate for the volume of the rod 2 that has withdrawn from the cylinder 1.

[0044] Next, the rod 2 is rotated relative to the cylinder 1. Figure 1 The following describes the action when the piston 3 moves to the right and the buffer D contracts. When the buffer D contracts, the piston 3 moves relative to the cylinder 1. Figure 1 The movement to the middle right compresses the compression-side chamber R2 and expands the expansion-side chamber R1.

[0045] In this situation, the annular valve body 17 is moved away from the annular valve seat 31c, opening the passage 3a provided in the piston 3. Simultaneously, the check valve 11b is closed, blocking the suction passage 11a. As a result, the hydraulic oil in the compression-side chamber R2 flows through the passage 3a to the expansion-side chamber R1. Furthermore, when the shock absorber D contracts, the rod 2 intrudes into the cylinder 1, resulting in an excess of hydraulic oil in the cylinder 1 corresponding to the volume of the rod 2 intruding into the cylinder 1. This excess hydraulic oil in the cylinder 1 flows through the damping valve 10b in the discharge passage 10a and is discharged to the reservoir R. Because the damping valve 10b resists this movement of hydraulic oil, the pressure in the expansion-side chamber R1 rises and becomes higher than the pressure in the reservoir R. Furthermore, since the compression-side chamber R2 is connected to the expansion-side chamber R1 via the passage 3a, the pressure in the compression-side chamber R2 is approximately equal to the pressure in the expansion-side chamber R1.

[0046] When the damper D contracts in this manner, the pressure in the expansion-side chamber R1 acting on the side of the expansion-side chamber R1 of the piston 3 and the pressure in the compression-side chamber R2 acting on the side of the compression-side chamber R2 of the piston 3 are approximately equal. However, because the pressure-receiving area of ​​the compression-side chamber R2 is larger than the pressure-receiving area of ​​the expansion-side chamber R1 of the piston 3, the damper D generates a compression-side damping force that hinders contraction. Furthermore, the hydraulic oil that has intruded the rod 2 into the cylinder 1 is discharged from the cylinder 1 into the reservoir R, compensating for the volume of the rod 2 that has intruded into the cylinder 1. In this way, the damper D generates a damping force during its expansion and contraction, attenuating the vibration of the target object.

[0047] Moreover, the buffer D of this embodiment includes: a cylinder 1; a rod 2, which can be movably inserted into the cylinder 1; a piston 3, which is inserted into the cylinder 1 and divides the cylinder 1 into an extension side chamber R1 and a compression side chamber R2; and an annular sealing component 4, which is mounted on the outer periphery of the piston 3 and is in sliding contact with the inner periphery of the cylinder 1; the piston 3 includes a first piston split body 31 and a second piston split body 32 opposite to the first piston split body 31; the first piston split body 31 has an annular recess 31a, which is formed on the outer periphery of the dividing surface A1 side where the first piston split body 31 and the second piston split body 32 are opposite; the sealing component 4 is accommodated in the annular recess 31a.

[0048] In the shock absorber D constructed in this manner, the sealing member 4 can be accommodated within the annular recess 31a before the first and second piston segments 31 and 32 are superimposed, even without increasing its diameter. When the first and second piston segments 31 and 32 are superimposed, the dividing surface A2 of the second piston segment 32 faces the annular recess 31a, forming an annular groove on the outer circumference of the piston 3. Therefore, even if the sealing member 4 housed within the annular recess 31a moves axially relative to the piston 3, it is axially clamped by the first and second piston segments 31 and 32, preventing it from moving and preventing it from falling out of the annular recess 31a.

[0049] Furthermore, in the shock absorber D of this embodiment, when the sealing member 4 is mounted on the piston 3, the sealing member 4 is first housed in the annular recess 31a of the first piston segment 31 without applying any load, and then the sealing member 4 can be mounted on the piston 3 simply by overlapping the first piston segment 31 and the second piston segment 32. Furthermore, in the shock absorber D of this embodiment, when the sealing member 4 is removed from the piston 3, the sealing member 4 is simply removed from the annular recess 31a of the first piston segment 31 after separating the first piston segment 31 and the second piston segment 32.

[0050] Therefore, according to the shock absorber D of this embodiment, the sealing member 4 can be easily attached to the outer circumference of the piston 3 without applying an unreasonable force that would cause the sealing member 4 to expand in diameter. Consequently, as the pressure within the cylinder 1 increases, which is used to generate a large damping force in the shock absorber D, the strength of the sealing member 4 increases. As a result, even if it is difficult to increase the diameter of the sealing member 4, there is no need to increase the diameter of the sealing member 4 when attaching the sealing member 4 to the piston 3. Therefore, the sealing member 4 can be easily attached to or removed from the piston 3. Therefore, according to the shock absorber D of this embodiment, even if the strength of the sealing member 4 is increased, the sealing member 4 can be easily attached to or removed from the piston 3.

[0051] In the shock absorber D of this embodiment, an annular recess 31a for accommodating the sealing member 4 is provided on the outer periphery of the first piston segment 31 on the side of the segmentation surface A1. Figure 4As in the shock absorber of the first modified example shown in FIG. 1 , the annular recess 31a of the first piston segment 31 can be eliminated, and an annular recess 32d for accommodating the sealing member 4 can be provided on the outer circumference of the second piston segment 32 on the side of the dividing plane A2. This allows the sealing member 4 to be assembled onto the second piston segment 32 without increasing its diameter before superimposing the first and second piston segments 31 and 32. Therefore, even with an increased strength of the sealing member 4, the sealing member 4 can be easily attached to and removed from the piston 3.

[0052] Furthermore, if Figure 5 As in the second modified example shown in the dashpot, annular recesses 31e and 32e may be provided on both the outer periphery of the first piston segment 31 on the side of the dividing plane A1 and the outer periphery of the second piston segment 32 on the side of the dividing plane A2, facing each other in the axial direction. When the first and second piston segments 31 and 32 are superimposed, these annular recesses 31e and 32e form an annular groove on the outer periphery of the piston 3 for accommodating the sealing member 4. In this manner, the sealing member 4 can be assembled on the outer periphery of the piston 3 without increasing its diameter when the first and second piston segments 31 and 32 are superimposed. Therefore, even if the sealing member 4 is made stronger, it can be easily attached to and removed from the piston 3.

[0053] Furthermore, in the shock absorber D of this embodiment, the first piston segment 31 includes a first port 31d that communicates from the inverted split surface B1 side to the split surface A1 side, and the second piston segment 32 includes a second port 32c that communicates from the inverted split surface B2 side to the split surface A2 side. The split surface A2 side of the second piston segment 32 includes an annular opening groove 32b that connects both the first port 31d and the second port 32c, formed circumferentially. With this structure, the shock absorber D allows communication between the first port 31d and the second port 32c via the opening groove 32b even when the first and second piston segments 31 and 32 are stacked, even if they are not aligned circumferentially. This facilitates assembly of the shock absorber D even when the piston 3 includes the passage 3a. Alternatively, the opening groove may be provided on the split surface A1 of the first piston segment 31, rather than on the second piston segment 32.

[0054] When the first piston split body 31 and the second piston split body 31 are overlapped and combined in the axial direction, as long as they can function as the piston 3 and the dividing surfaces A1 and A2 sides of the annular recesses 31a, 31e, 32d, and 32e are open in the axial direction, the shape can be changed arbitrarily, and the dividing surfaces A1 and A2 can also have concave and convex parts.

[0055] In this embodiment, the shock absorber D is a one-way, single-phase shock absorber in which hydraulic oil flows sequentially through the reservoir R, the compression-side chamber R2, and the extension-side chamber R1 during telescopic operation before returning to the reservoir R. However, a bidirectional shock absorber can also be used in which hydraulic oil moves back and forth between the extension-side chamber R1 and the compression-side chamber R2 during telescopic operation. Furthermore, the discharge passage 10a, damping valve 10b, and suction passage 11a can be located at locations other than those shown. Furthermore, the shock absorber D is not limited to railway vehicles or structures and can also be used for saddle-type vehicles, automobiles, and other machinery.

[0056] In addition, the assembly method of the buffer D of the present embodiment is a method of assembling the buffer D, which includes: a cylinder 1; a rod 2, which is movably inserted into the cylinder 1; an annular piston 3, which is inserted into the cylinder 1 and divides the cylinder 1 into an extension side chamber R1 and a compression side chamber R2; and an annular sealing component 4, which is mounted on the outer periphery of the piston 3 and is in sliding contact with the inner periphery of the cylinder 1; the rod 2 has a piston mounting portion 2a with a small diameter at the front end and the piston 3 mounted on the outer periphery, and a first step portion (step portion) 2c connected to the terminal end of the piston mounting portion 2a; the piston 3 has a first piston split body 31 and a second piston split body 32 axially opposite to the first piston split body 31; one or both of the first piston split body 31 and the second piston split body 32 have An annular recess 31a (31e, 32d, 32e) is formed on the outer periphery of the dividing surfaces A1 and A2 of the first piston split body 31 and the second piston split body 32; the assembly method includes the following steps: a step of fitting the first piston split body 31 to the outer periphery of the piston mounting portion 2a so that the first piston split body 31 abuts against the first step (step) 2c; a step of accommodating the sealing component 4 in the annular recess 31a (31e, 32d, 32e) of the first piston split body 31 or the second piston split body 32; and a step of fitting the second piston split body 32 to the outer periphery of the piston mounting portion 2a after the accommodating step, and fixing the first piston split body 31 and the second piston split body 32 to the piston mounting portion 2a in an overlapping state. In the assembly method of the buffer D constructed in this manner, when the sealing component 4 is installed on the piston 3, the sealing component 4 is pre-accommodated in the annular recess 31a (31e, 32d, 32e) of the first piston split body 31 or the second piston split body 32 without applying any load. The sealing component 4 can be installed on the piston 3 simply by overlapping the first piston split body 31 and the second piston split body 32, so the assembly of the buffer D also becomes easy.

[0057] 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.

[0058] This application claims priority based on Japanese Patent Application No. 2020-115278 filed with the Japan Patent Office on July 3, 2020, the entire contents of which are incorporated herein by reference.

Claims

1. A buffer, It has: cylinder; a rod member, which is movably inserted into the cylinder; a piston inserted into the cylinder and dividing the cylinder into an extension-side chamber and a compression-side chamber; and an annular sealing member mounted on the outer periphery of the piston and in sliding contact with the inner periphery of the cylinder; The piston includes a first piston split body and a second piston split body opposite to the first piston split body; One or both of the first piston split body and the second piston split body has an annular recessed portion formed on an outer periphery of a facing split surface side of the first piston split body and the second piston split body. The first piston split body has a first port communicating from the reverse split surface side to the split surface side, The second piston split body has a second port communicating from the reverse split surface side to the split surface side. An annular opening groove communicating with both the first port and the second port formed in the circumferential direction is provided on the dividing surface side of one of the first piston split body and the second piston split body. The sealing member is accommodated in the annular recess.

2. A method for assembling a buffer, The shock absorber comprises: a cylinder; a rod movably inserted into the cylinder; an annular piston inserted into the cylinder and dividing the cylinder into an expansion-side chamber and a compression-side chamber; and an annular sealing member mounted on the outer periphery of the piston and in sliding contact with the inner periphery of the cylinder. in, The rod has a piston mounting portion with a small diameter at the front end and the piston mounted on the outer periphery, and a step portion connected to the terminal end of the piston mounting portion. The piston includes an annular first piston segment and an annular second piston segment facing the first piston segment. One or both of the first piston split body and the second piston split body has an annular recessed portion formed on an outer periphery of a facing split surface side of the first piston split body and the second piston split body. The first piston split body has a first port communicating from the reverse split surface side to the split surface side, The second piston split body has a second port communicating from the reverse split surface side to the split surface side. One of the first piston split body and the second piston split body has an annular opening groove, and the opening groove communicates with both the first port and the second port formed on the split surface side in the circumferential direction. The assembly method of the buffer comprises the following steps: The step of fitting the first piston split body to the outer periphery of the piston mounting portion so that the first piston split body abuts against the step portion; a step of accommodating the sealing member in the annular recess of the first piston segment or the second piston segment; and, after the accommodating step, fitting the second piston split body to the outer periphery of the piston mounting portion, and fixing the first piston split body and the second piston split body to the piston mounting portion in an overlapping state.

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