CN113883208A - Buffer device - Google Patents

Abstract

The buffer is provided with: a cylinder; a rod member movably inserted into the cylinder; a piston inserted into the cylinder, and having a passage for communicating the expansion-side chamber and the compression-side chamber while dividing the interior of the cylinder into the expansion-side chamber and the compression-side chamber; and a valve for opening and closing the passage; the piston has a1 st piston segment that is axially segmented and that unseats or seats the valve body of the valve, and a2 nd piston segment that axially faces the 1 st piston segment, and the 2 nd piston segment is formed of a material having a higher strength than the 1 st piston segment.

Description

Buffer device

Technical Field

The present invention relates to a buffer.

Background

For example, as disclosed in JP2015-224780a, a buffer includes: a cylinder; a piston rod movably inserted into the cylinder; a piston which is slidably inserted into the cylinder and is connected to the piston rod; an extension side chamber and a compression side chamber which are filled with hydraulic oil while dividing the inside of the cylinder by a piston; an outer cylinder that covers an outer periphery of the cylinders and forms a reservoir for storing hydraulic oil between the cylinders; a damping passage that allows only hydraulic oil to flow from the elongated side chamber to the reservoir and that applies resistance to the flow of hydraulic oil therethrough; a flow regulating passage provided on the piston and allowing only hydraulic oil to flow from the compression-side chamber to the extension-side chamber; and a suction passage that allows only hydraulic oil to flow from the reservoir to the compression-side chamber.

The shock absorber configured as described above is provided with check valves in the rectifying passage and the suction passage, and the check valves are set to a single-phase type in which the hydraulic oil flows through the reservoir, the compression-side chamber, and the extension-side chamber in this order and reaches the reservoir during the expansion and contraction operation. In addition, the shock absorber generates a damping force that resists expansion and contraction by applying resistance to the flow of hydraulic oil discharged from the cylinder to the reservoir through the damping passage during expansion and contraction operations.

The check valve provided to the piston includes: an annular valve body unseated or seated on a valve seat surrounding an outlet end of the rectifying passage of the piston; and a spring that urges the annular valve body toward the piston, and opens the rectifying passage when the entire annular valve body receives pressure from the compression-side chamber and is away from the piston.

The annular valve body in the check valve is formed of hardened high-carbon steel or the like having excellent elastic limit and fatigue resistance limit because the annular valve body repeatedly moves away from and contacts the piston due to expansion and contraction of the shock absorber. On the other hand, from the viewpoint of formability and wear resistance, the piston that repeatedly collides with the annular valve body is formed of cast iron having a carbon content of 2.14% to 6.67%.

When the piston is formed of cast iron in this manner, even if the piston repeatedly collides with the annular valve body, the piston is less worn, and the shock absorber can be retained and functions for a long period of time.

Summary of The Invention

For example, a railway vehicle or a structure is used as a vibration damping object, and a damper is provided between a vehicle body of the railway vehicle and a bogie or between vehicle bodies of adjacent railway vehicles, between an elastically supported structure and a foundation, or between column beams of the structure, and the like, and is used for the purpose of damping vibration of the vibration damping object.

As described above, when the object to be damped of the shock absorber is a heavy object such as a railway vehicle or a structure, the shock absorber needs to generate a large damping force in order to suppress the vibration of the object to be damped. In order to satisfy such a demand, the damping force of the shock absorber may be increased by increasing the difference between the pressure in the expansion-side chamber and the pressure in the compression-side chamber.

As described above, the piston is made of cast iron, and although cast iron has excellent wear resistance, it has low strength and may not be able to withstand the action of high pressure. Further, in the case where the shock absorber expands and contracts at a high speed, it is desirable to allow more hydraulic oil to pass through the passage provided in the piston, but as described above, since the piston is formed of cast iron, when the passage sectional area is increased, the strength is reduced, and it is also difficult to secure a larger passage sectional area. Therefore, the conventional shock absorber has a problem that it is difficult to generate a high damping force due to a high pressure in the cylinder.

Accordingly, an object of the present invention is to provide a shock absorber capable of generating a high damping force while withstanding a high pressure in a cylinder.

In order to solve the above problem, a damper according to the present invention includes: a cylinder; a rod member movably inserted into the cylinder; a piston inserted into the cylinder, and having a passage for communicating the expansion-side chamber and the compression-side chamber while dividing the interior of the cylinder into the expansion-side chamber and the compression-side chamber; and a valve for opening and closing the passage; the piston has a1 st piston segment divided in the axial direction and separating or seating a valve body of the valve, and a2 nd piston segment divided in the axial direction and facing the 1 st piston segment, and the 2 nd piston segment is formed of a material having a higher strength than the 1 st piston segment.

Drawings

FIG. 1 is a longitudinal cross-sectional view of a bumper in one embodiment.

FIG. 2 is an enlarged cross-sectional view of a piston portion of a damper in one embodiment.

Fig. 3 is a plan view of a2 nd piston split body of the shock absorber according to the embodiment.

Detailed Description

The present invention will be described based on embodiments shown in the drawings. As shown in fig. 1, a buffer D according to an embodiment includes: a cylinder 1; a rod member 2 inserted into the cylinder 1 to be movable; a piston 3 inserted into the cylinder 1, having a passage 3a for communicating the extension side chamber R1 and the compression side chamber R2 while dividing the interior of the cylinder 1 into the extension side chamber R1 and the compression side chamber R2; and a valve V for opening and closing the passage 3 a. In the case of the shock absorber D, for example, it is used between a vehicle body and a bogie in a railway vehicle, not shown, to suppress vibration of the vehicle body and the bogie.

Next, each part of the buffer D will be described in detail. As shown in fig. 1, an annular rod guide 10 is fitted to the left end of the cylinder 1 in fig. 1, and the right end of the cylinder 1 in fig. 1 is closed by a valve housing 11. Further, the cylinder 1 is accommodated together with the valve housing 11 in an outer cylinder 12 whose right end is closed by a bottom cover 13 in fig. 1. A reservoir R, which is annular and stores fluid such as hydraulic oil together with gas, is formed between the cylinder 1 and the outer cylinder 12.

The opening portion of the outer cylinder 12 at the left end in fig. 1 is closed by a rod guide 10 mounted on the outer cylinder 12. Further, the cylinder 1 and the valve housing 11 are sandwiched by the rod guide 10 and the bottom cover 13 fixed to the outer cylinder 12 and are accommodated in the outer cylinder 12 and fixed with respect to the outer cylinder 12.

The rod 2 is slidably inserted into the rod guide 10 and inserted into the cylinder 1, and is guided by the rod guide 10 to move in the axial direction. The rod member 2 includes: a small diameter portion 2a provided at a front end which is a right end in fig. 1, having a small outer diameter, and having a piston 3 attached to an outer periphery thereof; a threaded portion 2b provided on the outer periphery of the tip of the small-diameter portion 2 a; a1 st stepped portion 2c (see fig. 2) formed at a boundary between the small diameter portion 2a and a position on the left side in fig. 1 with respect to the small diameter portion 2 a; and a2 nd step part 2d (see fig. 2) and a 3 rd step part 2e (see fig. 2) provided on the left side in fig. 1 of the 1 st step part 2 c. As described above, in the shock absorber D of the present embodiment, the rod 2 has a small diameter whose outer diameter is divided into 3 steps on the distal end side.

The piston 3 is annularly attached to the small diameter portion 2a of the rod 2, is movably inserted into the cylinder 1, and divides the cylinder 1 into an extension side chamber R1 and a compression side chamber R2 filled with a fluid such as hydraulic oil. In addition to hydraulic oil, for example, water, aqueous solution, or other liquid may be used as the fluid. In addition, a gas may be used as the fluid instead of the liquid.

In the present embodiment, the piston 3 is configured to include the 1 st piston segment 31 and the 2 nd piston segment 32 that are axially divided. The 1 st piston split body 31 and the 2 nd piston split body 32 are both annular and are stacked in the axial direction to form a piston 3 integrally.

The 1 st piston split body 31 is made of cast iron such as gray cast iron, nodular cast iron, malleable cast iron, alloy cast iron, and white cast iron. Cast iron is a ternary alloy of iron containing carbon in the range of 2.14 to 6.67%, silicon in the range of about 1 to 3%, and is characterized by excellent wear resistance. The 1 st piston split body 31 includes: an annular recessed portion 31a formed in an annular shape on an outer periphery on the side of a split surface a1 which is a right end side in fig. 2 in the circumferential direction and opposed to a split surface a2 side end which is a left end side in fig. 2 of the 2 nd piston split body 32; an annular groove 31B formed circumferentially on the end on the side of the reverse split surface B1, which is the left end in fig. 2; an annular valve seat 31c projecting in the axial direction from the side end of the reverse dividing surface B1 and surrounding the groove 31B; and a plurality of 1 st ports 31d that open on the dividing surface a1 and communicate with the groove 31 b.

The 2 nd piston divided body 32 is formed using carbon steel containing carbon in a range of 0.02 to 2.14% as a material. The carbon steel has high strength, and the 2 nd split piston body 32 has higher strength than the 1 st split piston body 31. As shown in fig. 2 and 3, the 2 nd piston split body 32 includes: an annular groove 32a which is annular and formed on the outer periphery in the circumferential direction; an open groove 32b formed on the side end of the dividing plane a2 as the left end in fig. 2 in the circumferential direction through an annular groove; and a plurality of 2 nd ports 32c opened on the reverse split surface B2 and communicating with the open grooves 32B; a screw groove, not shown, is formed on the inner periphery and is screwed with the screw portion 2b of the rod 2.

The 1 st piston segment 31 and the 2 nd piston segment 32 have the same outer diameter and have inner diameters that can be attached to the outer periphery of the small diameter portion 2a of the rod 2. When the 1 st split piston body 31 and the 2 nd split piston body 32 are axially overlapped with each other with the centers of the 1 st split piston body 31 and the 2 nd split piston body 32 aligned, the 1 st port 31d of the 1 st split piston body 31 and the open groove 32b of the 2 nd split piston body 32 are arranged to face each other.

The 1 st and 2 nd piston split bodies 31, 32 configured in this way are used after the split surfaces a1, a2 are opposed to each other and overlapped in the axial direction. After the small diameter portion 2a of the rod 2 is inserted into the inner periphery of the 1 st piston segment 31, the 2 nd piston segment 32 is screwed into the screw portion 2b formed on the outer periphery of the small diameter portion 2a of the rod 2. Then, the 1 st piston divided body 31 is sandwiched between the 1 st step portion 2c of the rod 2 and the 2 nd piston divided body 32 and fixed to the rod 2. Further, a piston nut 15 is screwed to the 2 nd split piston body 32 on the front end side of the threaded portion 2 b. When the piston nut 15 is screwed into the threaded portion 2b of the rod 2 in this way, the 2 nd split piston body 32 and the piston nut 15 form a double nut, which prevents the 2 nd split piston body 32 from loosening and prevents the piston 3 from coming off the rod 2. Further, the piston 3 may be fixed to the rod 2 only by the piston nut 15 without providing a screw groove on the inner periphery of the 2 nd piston split body 32. The 1 st piston segment 31 and the 2 nd piston segment 32 fixed to the rod 2 in this manner are integrally held on the outer periphery of the small diameter portion 2a of the rod 2, and cooperate with each other to function as the piston 3.

Further, when the 1 st and 2 nd piston divided bodies 31, 32 overlap, the 1 st port 31d and the open groove 32b oppose each other, the 1 st port 31d and the 2 nd port 32c communicate with each other, and a passage 3a for communicating the extension side chamber R1 and the compression side chamber R2 is formed. In addition, the number of the 1 st port 31d and the 2 nd port 32c can be arbitrarily set.

Further, when the 1 st piston divided body 31 and the 2 nd piston divided body 32 are overlapped, the annular concave portion 31a provided on the outer periphery of the 1 st piston divided body 31 is opposed to the divided surface a2 of the 2 nd piston divided body 32, and an annular groove for surrounding the outer periphery of the piston 3 is formed.

A sealing member 4 having an annular shape and sealing a space between the cylinder 1 and the piston 3 is accommodated in the annular groove formed by the annular recess 31 a. The seal member 4 is configured to include a seal ring 4a that is in sliding contact with the inner peripheral surface of the cylinder 1, and an O-ring 4b disposed on the inner peripheral side of the seal ring 4 a.

The seal ring 4a is made of synthetic resin and is in sliding contact with the inner peripheral surface of the cylinder 1, and has self-lubricating properties to prevent the hydraulic oil from flowing between itself and the cylinder 1 while not hindering smooth movement of the piston 3. Further, the O-ring 4b is in close contact with the inner peripheral surface of the seal ring 4a and the bottom surface of the annular recess 31a of the piston 3, and seals between the seal ring 4a and the piston 3 to prevent the hydraulic oil from flowing through the inside of the annular recess 31 a. As described above, in the shock absorber D of the present embodiment, the seal member 4 is constituted by the seal ring 4a and the O-ring 4b, but may be constituted by a single member.

In order to attach the seal member 4 to the outer periphery of the piston 3, the seal member 4 may be accommodated in the annular recess 31a from the split surface a1 side of the 1 st split piston body 31 before the 1 st split piston body 31 and the 2 nd split piston body 32 are integrally overlapped. Since the 1 st piston segment 31 of the annular recessed portion 31a is open on the side of the split surface a1, the seal member 4 can be attached to the annular recessed portion 31a without applying any load to the seal member 4, without enlarging the diameter of the seal member 4 when attaching the seal member 4 to the annular recessed portion 31 a.

In this way, after the sealing member 4 is assembled to the 1 st split piston body 31, the piston 3 can be formed if the 1 st split piston body 31 and the 2 nd split piston body 32 are overlapped.

Further, a ring-shaped piston ring 5 for guiding the axial movement of the piston 3 by sliding contact with the inner circumference of the cylinder 1 is mounted in a ring-shaped groove 32a provided on the outer circumference of the 2 nd piston divided body 32.

As described above, the piston 3 configured in this way is mounted on the outer periphery of the small diameter portion 2a of the rod member 2. Specifically, a coil spring 16, an annular valve body 17 formed of an annular plate and serving as a valve body, and the piston 3 are assembled in this order at the tip of the rod 2. As described above, the piston 3 is fixed to the outer periphery of the small diameter portion 2a of the rod member 2 in a state where the 1 st piston split body 31 and the 2 nd piston split body 32 are in close contact with each other at the split surfaces a1, a 2.

The annular valve body 17 is formed of spring steel such as high-carbon steel, alloy steel, or stainless steel. Spring steel is characterized by excellent elastic limit and fatigue resistance limit. The annular valve body 17 is annular, has an outer diameter larger than the annular valve seat 31c of the 1 st piston segment 31, and is fitted to the outer periphery of the rod 2 between the 1 st step portion 2c and the 2 nd step portion 2d so as to be movable in the axial direction. The annular valve body 17 may be axially moved away from or close to the piston 3, close the passage 3a in a state of abutting against the piston 3 and seating on the annular valve seat 31c, and open the passage 3a when moved away from the piston 3. When the annular valve body 17 abuts on the 2 nd step portion 2d, further movement thereof to the left in fig. 1 is restricted, and the maximum lift amount distant from the piston 3 is set in accordance with the installation position of the 2 nd step portion 2 d. The coil spring 16 is attached between the 3 rd step portion 2e and the annular valve body 17, and urges the annular valve body 17 into contact with the piston 3.

Therefore, in the shock absorber D of the present embodiment, the annular valve body 17, which is a valve body unseated or seated on the annular valve seat 31c of the 1 st piston divided body 31, and the coil spring 16 constitute a valve V for opening and closing the passage 3 a. In the shock absorber D of the present embodiment, the valve V opens the passage 3a by moving the annular valve body 17 away from the annular valve seat 31c, thereby allowing the hydraulic oil to flow only from the compression-side chamber R2 to the extension-side chamber R1, and 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 constitute a check valve for closing the passage 3 a.

Next, the rod guide 10 is provided with a discharge passage 10a for communicating the extension-side chamber R1 and the reservoir R. A damping valve 10b that allows only the hydraulic oil to flow from the extension-side chamber R1 to the reservoir R and that blocks the flow of the hydraulic oil therethrough in the reverse direction while applying resistance to the flow thereof is provided on the discharge passage 10 a; the discharge passage 10a is set as a passage that allows only one-way passage of the hydraulic oil from the extension-side chamber R1 to the reservoir R.

Further, the valve housing 11 is provided with a suction passage 11a for communicating the reservoir R and the compression-side chamber R2. A suction check valve 11b that allows only the hydraulic oil to flow from the reservoir R to the compression-side chamber R2 and prevents the hydraulic oil from flowing in the reverse direction is provided on the suction passage 11 a; the suction passage 11a is set as a passage that allows only one-way passage of the hydraulic oil from the reservoir R to the compression-side chamber R2.

The buffer D is configured as described above, and the operation of the buffer D will be described below. First, the operation when the rod 2 moves leftward in fig. 1 with respect to the cylinder 1 and the shock absorber D extends will be described. When the shock absorber D extends, the piston 3 moves leftward in fig. 1 with respect to the cylinder 1, and therefore the extension side chamber R1 is compressed and the compression side chamber R2 is expanded.

In this case, since the annular valve body 17 is seated on the annular valve seat 31c to close the passage 3a provided in the piston 3, the hydraulic oil in the extension-side chamber R1 flows through the orifice valve 10b of the discharge passage 10a and is discharged to the reservoir R. Since resistance is applied to such movement of the hydraulic oil by the damping valve 10b, the pressure in the extension side chamber R1 rises and becomes higher than the pressure in the reservoir R. Further, the compression-side chamber R2 has an enlarged volume due to the movement of the piston 3, and the hydraulic oil is insufficient, but the insufficient hydraulic oil is supplied from the reservoir R to the compression-side chamber R2 via the suction passage 11a by opening the suction check valve 11 b. Therefore, the pressure in the compression-side chamber R2 is substantially equal to the pressure in the reservoir R.

When the shock absorber D performs the extension operation in this way, the pressure acting on the extension side chamber R1 on the side of the extension side chamber R1 of the piston 3 is higher than the pressure acting on the compression side chamber R2 on the side of the compression side chamber R2 of the piston 3, and the shock absorber D generates an extension side damping force that interferes with the extension operation. Further, the volume portion of the hydraulic oil that the rod 2 withdraws from the cylinder 1 is supplied from the reservoir R to the compression-side chamber R2 to compensate for the volume of the rod 2 withdrawing from the cylinder 1.

Next, the operation when the rod 2 moves in the right direction in fig. 1 with respect to the cylinder 1 and the shock absorber D contracts will be described. When the shock absorber D contracts, the piston 3 moves rightward in fig. 1 with respect to the cylinder 1, and therefore compresses the compression-side chamber R2 and expands the expansion-side chamber R1.

In this case, while the passage 3a provided in the piston 3 is opened by moving the annular valve body 17 away from the annular valve seat 31c, the suction check valve 11b is closed and the suction passage 11a is shut off, and therefore, the hydraulic oil in the compression-side chamber R2 moves to the extension-side chamber R1 through the passage 3 a. Further, when the shock absorber D performs the contraction operation, the rod 2 enters the cylinder 1, and therefore, the hydraulic oil in the volume portion of the cylinder 1 where the rod 2 enters the cylinder 1 becomes excessive. The surplus hydraulic oil in the cylinder 1 is discharged to the reservoir R through the damping valve 10b of the discharge passage 10 a. Since resistance is applied to such movement of the hydraulic oil by the damping valve 10b, the pressure in the extension side chamber R1 rises and becomes higher than the pressure in the reservoir R. Further, since the compression side chamber R2 is in a state of being communicated with the extension side chamber R1 through the passage 3a, the pressure in the compression side chamber R2 is substantially equal to the pressure in the extension side chamber R1.

When the shock absorber D performs the contraction operation in this way, the pressure acting on the extension side chamber R1 on the side of the extension side chamber R1 of the piston 3 is substantially equal to the pressure acting in the compression side chamber R2 on the side of the compression side chamber R2 of the piston 3, but the pressure receiving area receiving the pressure in the compression side chamber R2 is larger than the pressure receiving area receiving the pressure in the extension side chamber R1 of the piston 3, and therefore the shock absorber D generates the compression side damping force that hinders the contraction operation. In addition, the volume of hydraulic oil that the rod 2 intrudes into the cylinder 1 is drained from the cylinder 1 to the reservoir R, compensating for the volume of the rod 2 that intrudes into the cylinder 1. In this way, the shock absorber D generates a damping force when performing the expansion and contraction operation, and damps vibration to be damped.

Further, when the shock absorber D is expanded, the annular valve body 17 in the valve V abuts against the annular valve seat 31c provided on the 1 st piston divided body 31 in the piston 3 and closes the passage 3a, and when the shock absorber D is contracted, the annular valve body 17 in the valve V is separated from the piston 3 and opens the passage 3 a. As the shock absorber D repeats expansion and contraction in this way, the annular valve body 17 repeatedly collides with the 1 st split piston body 31. The first piston segment 31 abutting against the annular valve body 17 is required to have wear resistance, but a material having excellent wear resistance may be poor in strength, and when the entire piston is formed of a material having excellent wear resistance as in a conventional shock absorber, the strength of the piston may be insufficient when the piston is used after the pressure in the cylinder 1 is increased during expansion and contraction of the shock absorber to generate a high damping force.

However, in the shock absorber D of the present embodiment, the piston 3 includes the 1 st piston segment 31 and the 2 nd piston segment 32 which are axially divided, the 1 st piston segment 31 and the 2 nd piston segment 32 which collide with the annular valve body 17 are formed of different materials, and the strength of the 2 nd piston segment 32 is higher than that of the 1 st piston segment 31. Therefore, even if the pressure in the cylinder 1 is higher than the conventional one and a large axial force is applied to the piston 3 during the expansion and contraction operation of the shock absorber D, the 2 nd split piston body 32 having high strength supports the 1 st split piston body 31 having low strength in the axial direction, and therefore, the 1 st split piston body 31 can be prevented from being deformed. Further, since the 1 st split piston body 31 having a low strength can be supported by the 2 nd split piston body 32 having a high strength, even if the flow passage area of the passage 3a is increased for use in high-speed expansion and contraction of the shock absorber D, the 1 st split piston body 31 can be prevented from being deformed.

As described above, the buffer D of the present embodiment includes: a cylinder 1; a rod member 2 inserted into the cylinder 1 to be movable; a piston 3 inserted into the cylinder 1, having a passage 3a for communicating the extension side chamber R1 and the compression side chamber R2 while dividing the interior of the cylinder 1 into the extension side chamber R1 and the compression side chamber R2; and a valve V for opening and closing the passage 3 a; the piston 3 includes a1 st piston segment 31 that is axially divided and separates or seats the annular valve body (valve body) 17 of the valve V, and a2 nd piston segment 32 that axially faces the 1 st piston segment 31, and the 2 nd piston segment 32 is formed of a material having higher strength than the 1 st piston segment 31.

As described above, in the shock absorber D configured in this way, even if the pressure in the cylinder 1 is increased, the deformation of the 1 st split piston body 31, which is inferior in strength, can be supported by the 2 nd split piston body 32, which is superior in strength, and the flow passage area of the passage 3a can be increased. Therefore, according to the shock absorber D of the present embodiment, it is possible to generate a high damping force while withstanding a high pressure in the cylinder 1.

In the shock absorber D of the present embodiment, the 2 nd piston split body 32 is screwed into the threaded portion 2b of the rod 2, and the 1 st piston split body 31 is sandwiched between the 2 nd piston split body 32 and the 1 st stepped portion 2c of the rod 2, so that the force acting on the piston 3 by the pressure in the cylinder 1 is transmitted through the 2 nd piston split body 32 having high strength, and thus it is possible to prevent an excessive shearing force from acting on the inner peripheral portion of the 1 st piston split body 31. Therefore, according to the shock absorber D configured in this way, the 1 st split piston body 31 which is inferior in strength can be further protected.

The structure of the valve V is not limited to the above-described structure, and may be a leaf valve or a poppet valve. The piston 3 may be constituted by 3 or more piston split bodies including the 1 st piston split body 31 and the 2 nd piston split body 32, since the 1 st piston split body 31 is axially split and the valve V is unseated or seated, and the 2 nd piston split body 32 axially faces the 1 st piston split body 31.

In the shock absorber D of the present embodiment, the annular valve body (valve body) 17 in the valve V is formed of a material having a higher strength than the 1 st piston split body 31, and therefore the annular valve body (valve body) 17 can be prevented from being deformed under a high pressure in the cylinder 1.

The 1 st piston split body 31 may be made of cast iron, and the annular valve body (valve body) 17 in the valve V may be made of spring steel. Since cast iron has excellent wear resistance, it can also withstand wear due to repeated impacts with the annular valve body (valve body) 17, and therefore is suitable as the material of the 1 st piston segment 31, and since spring steel has excellent elastic limit and fatigue resistance limit, it is suitable as the material of the annular valve body (valve body) 17 that repeatedly collides with the piston 3 while receiving high pressure from the back side, which is the opposite side of the piston, from the extension-side chamber R1. As described above, according to the shock absorber D in which the 1 st piston split body 31 is formed of cast iron and the annular valve body (valve body) 17 of the valve V is formed of spring steel, it is possible to reduce deterioration due to wear of the 1 st piston split body 31 and deterioration such as deformation and fatigue of the annular valve body (valve body) 17.

Further, in the shock absorber D of the present embodiment, the 1 st piston divided body 31 includes the 1 st port 31D communicating from the reverse divided surface B1 side to the divided surface a1 side, the 2 nd piston divided body 32 includes the 2 nd port 32c communicating from the reverse divided surface B2 side to the divided surface a2 side, and the 2 nd piston divided body 32 includes the annular open groove 32B communicating with both the 1 st port 31D and the 2 nd port 32c formed in the circumferential direction on the divided surface a2 side. According to the shock absorber D configured in this way, when the 1 st piston divided body 31 and the 2 nd piston divided body 32 are overlapped, even if they are not aligned in the circumferential direction, the 1 st port 31D and the 2 nd port 32c can communicate through the open groove 32b, and therefore, in the case where the piston 3 is provided with the passage 3a, the assembly of the shock absorber D becomes easy. The opening groove may be provided on the dividing surface a1 of the 1 st piston divided body 31 instead of the 2 nd piston divided body 32.

Further, the buffer D of the present embodiment includes: a reservoir R for storing hydraulic oil (fluid); a discharge channel 10a communicating the extension-side chamber R1 and the reservoir R; a damping valve 10b that is provided on the discharge passage 10a and that applies resistance to the flow of hydraulic oil (fluid) while allowing only the hydraulic oil (fluid) to flow from the extension-side chamber R1 to the reservoir R; a suction channel 11a communicating the reservoir R and the compression-side chamber R2; and a suction check valve 11b that is provided on the suction passage 11a and allows only hydraulic oil (fluid) to flow from the reservoir R to the compression-side chamber R2; the valve V is a check valve that allows only hydraulic oil (fluid) to flow in the passage 3a from the compression-side chamber R2 to the extension-side chamber R1. The shock absorber D configured in this manner is a single-phase shock absorber in which, when the telescopic operation is performed, the hydraulic oil (fluid) flows through the reservoir R, the compression-side chamber R2, and the extension-side chamber R1 in this order, and then flows back to the reservoir R in one direction. In the single-phase shock absorber D, the entire amount of the hydraulic oil (fluid) that moves from the compression-side chamber R2 that contracts during contraction moves to the extension-side chamber R1 through the passage 3 a. Therefore, the amount of hydraulic oil (fluid amount) flowing through the passage 3a in the shock absorber D set to the single-phase type is larger than the amount of hydraulic oil (fluid amount) flowing through the passage provided in the piston of the shock absorber, and the shock absorber is set to the double-direction type shock absorber in which hydraulic oil (fluid) reciprocates in the expansion-side chamber and the compression-side chamber without passing through the reservoir during expansion and contraction. In this way, in the damper D set to the single-phase type, there is a high demand for an increase in the flow passage area of the passage 3a provided in the piston 3.

Therefore, the structure including the 1 st piston segment 31 for unseating or seating the valve V on the piston 3 and the 2 nd piston segment 32 having high strength is most suitable for the single-phase shock absorber D which has to allow more hydraulic oil (fluid) to flow due to high pressure in the cylinder 1, and the practicality of the single-phase shock absorber D can be improved.

The piston 3 includes a1 st piston segment 31 divided in the axial direction and a2 nd piston segment 32 facing the 1 st piston segment 31 in the axial direction, and the seal member 4 is accommodated in an annular recess 31a provided on the outer periphery of the 1 st piston segment 31 on the dividing surface a1 side.

In the shock absorber D configured as described above, the diameter of the seal member 4 can be accommodated in the annular recess 31a without enlarging the diameter before the 1 st piston divided body 31 and the 2 nd piston divided body 32 are overlapped, and when the 1 st piston divided body 31 and the 2 nd piston divided body 32 are overlapped, the divided surface a2 of the 2 nd piston divided body 32 faces the annular recess 31a, and an annular groove is formed in the outer periphery of the piston 3. Thus, even if the seal member 4 accommodated in the annular recess 31a moves in the axial direction with respect to the piston 3, the 1 st split piston body 31 and the 2 nd split piston body 32 are sandwiched in the axial direction so as not to move, and do not come out of the annular recess 31 a.

In the shock absorber D of the present embodiment, when the seal member 4 is attached to the piston 3, the seal member 4 is accommodated in the annular concave portion 31a of the 1 st piston split body 31 without applying any load, and then the 1 st piston split body 31 and the 2 nd piston split body 32 are merely overlapped with each other, whereby the seal member 4 can be attached to the piston 3. In the shock absorber D of the present embodiment, when the seal member 4 is removed from the piston 3, the 1 st piston divided body 31 and the 2 nd piston divided body 32 are separated, and then the seal member 4 is easily removed from the annular concave portion 31a of the 1 st piston divided body 31.

Therefore, according to the shock absorber D of the present embodiment, the seal member 4 can be easily attached to the outer periphery of the piston 3 without applying an excessive biasing force for expanding the diameter of the seal member 4. Therefore, as the pressure in the cylinder 1 for generating a large damping force of the shock absorber D increases, the strength of the seal member 4 increases, and as a result, even if it is difficult to enlarge the diameter of the seal member 4, it is not necessary to enlarge the diameter of the seal member 4 when the seal member 4 is attached to the piston 3, and therefore, the seal member 4 can be easily attached to and detached from the piston 3. Therefore, according to the shock absorber D of the present embodiment, even if the seal member 4 is strengthened, the seal member 4 can be easily attached to or detached from the piston 3.

In the shock absorber D of the present embodiment, the annular recessed portion 31a for accommodating the seal member 4 is provided on the outer periphery of the 1 st piston segment 31 on the dividing surface a1 side, but the annular recessed portion 31a of the 1 st piston segment 31 may be eliminated and the annular recessed portion for accommodating the seal member 4 may be provided on the outer periphery of the 2 nd piston segment 32 on the dividing surface a2 side. In this way, even if the operation of enlarging the diameter of the seal member 4 is not performed before the 1 st piston divided body 31 and the 2 nd piston divided body 32 are superposed, the piston divided bodies can be assembled to the 2 nd piston divided body 32, and therefore, even if the seal member 4 is strengthened, the seal member 4 can be easily attached to or detached from the piston 3.

Further, annular concave portions that face each other in the axial direction may be provided on both the outer periphery of the 1 st piston divided body 31 on the dividing surface a1 side and the outer periphery of the 2 nd piston divided body 32 on the dividing surface a2 side, and when the 1 st piston divided body 31 and the 2 nd piston divided body 32 are overlapped, one annular groove for accommodating the seal member 4 may be formed on the outer periphery of the piston 3 by these annular concave portions. In this way, even if the diameter of the seal member 4 is not enlarged when the 1 st and 2 nd piston divided bodies 31, 32 are superposed, the piston divided bodies can be assembled to the outer periphery of the piston 3, and therefore, even if the seal member 4 is strengthened, the seal member 4 can be easily attached to or detached from the piston 3.

When the 1 st piston divided body 31 and the 2 nd piston divided body 32 are overlapped and combined in the axial direction, the shape may be arbitrarily changed as long as they can function as the piston 3, and the divided surfaces a1 and a2 may have irregularities.

The shock absorber D is a single-phase shock absorber, but may be a bidirectional shock absorber in which the hydraulic oil reciprocates between the expansion side chamber R1 and the compression side chamber R2 during the expansion and contraction operation. In the case of the two-way shock absorber, since the valves V are disposed on both sides of the 1 st piston split body, both sides in the axial direction of the 1 st piston split body may be sandwiched by the 2 nd piston split body formed of a material having a higher strength than the 1 st piston split body. The discharge passage 10a, the damping valve 10b, and the suction passage 11a may be provided at positions other than those shown in the drawings. The target of vibration reduction of the shock absorber D is not limited to the railway vehicle and the structure, and may be a saddle-ride type vehicle, an automobile, other machinery, or the like.

While the preferred embodiments of the present invention have been illustrated and described in detail, modifications, variations and changes may be made without departing from the scope of the claims.

This application claims priority based on Japanese patent application No. 2020-115277, filed on the filing date 7/3 of 2020 to the office, the entire content of which is incorporated herein by reference.

Claims (5)

1. A kind of buffer is disclosed, which comprises a buffer body,

it is provided with:

a cylinder;

a rod member movably inserted into the cylinder;

a piston inserted into the cylinder, and having a passage for communicating the extension-side chamber and the compression-side chamber while dividing the inside of the cylinder into the extension-side chamber and the compression-side chamber;

and a valve for opening and closing the passage;

the piston has a1 st piston segment body that is axially divided and that causes a valve body of the valve to unseat or seat, and a2 nd piston segment body that is axially divided and that axially faces the 1 st piston segment body,

the 2 nd piston split body is formed of a material having higher strength than the 1 st piston split body.

2. The buffer of claim 1, wherein the buffer is a single buffer,

wherein,

the valve body is formed of a material having higher strength than the 1 st piston split body.

3. The buffer of claim 2, wherein the buffer is a single buffer,

wherein,

the 1 st piston split body is formed of cast iron,

the valve body is formed of spring steel.

4. The buffer of claim 1, wherein the buffer is a single buffer,

wherein,

the 1 st piston split body has a1 st port communicating from the reverse split surface side to the split surface side,

the 2 nd piston split body has a2 nd port communicating from the reverse split surface side to the split surface side,

and has an annular open groove communicating with both the 1 st port and the 2 nd port formed on a split surface side of one of the 1 st piston split body and the 2 nd piston split body in a circumferential direction.

5. The buffer according to any one of claims 1 to 4,

the disclosed device is characterized by being provided with:

a reservoir for storing a fluid;

a discharge channel for communicating the elongated side chamber and the reservoir;

a damping valve provided on the discharge channel, which applies resistance to the flow of the fluid while allowing only the fluid to flow from the elongated side chamber to the reservoir;

a suction channel for communicating the reservoir and the compression-side chamber;

and a suction check valve that is provided on the suction channel and allows only the fluid to flow from the reservoir to the compression-side chamber;

the valve is a check valve that allows only the fluid to flow in the passage from the compression-side chamber to the extension-side chamber.

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