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Abstract

A shock absorber includes: an extension body having a cylinder and a rod member movably inserted into the cylinder in an axial direction; a partition member partitioning an extension-side chamber and a compression-side chamber in the extension body while having a passage for communicating the extension-side chamber and the compression-side chamber; and a valve for opening and closing the passage; an annular inner peripheral valve seat and an annular outer peripheral valve are formed on the partition member, and the valve is seated from an end portion facing the valve in an axial direction; and an annular intermediate valve seat is formed in the axial direction from an end portion facing the valve; the passage and the intermediate valve seat are formed between the inner peripheral valve seat and the outer peripheral valve seat.

Description

TECHNICAL FIELD

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

[0002] For example, as disclosed in JP 2015-224780 A, a damper is provided with: a cylinder; a piston rod which is movably inserted into the cylinder; a piston which is connected to the piston rod while being slidably inserted into the cylinder; an extension-side chamber and a compression-side chamber which divide the inside of the cylinder by the piston while being filled with hydraulic oil; an outer tube which covers the outer periphery of the cylinder and forms a reservoir for storing hydraulic oil between the cylinder; a damping passage which is provided with a damping valve for allowing hydraulic oil to flow only from the extension-side chamber to the reservoir while applying resistance to the flow of the hydraulic oil; a rectification passage which is provided on the piston and allows hydraulic oil to flow only from the compression-side chamber to the extension-side chamber; and a suction passage which allows hydraulic oil to flow only from the reservoir to the compression-side chamber.

[0003] The damper configured in this way is provided with valves which function as check valves on the rectification passage and the suction passage, and by these valves, it is set to be of a single-phase type in which hydraulic oil reaches the reservoir in the order of the reservoir, the compression-side chamber, and the extension-side chamber at the time of extension and contraction. Also, the damper applies resistance to the flow of hydraulic oil which is discharged from the inside of the cylinder to the reservoir through the damping passage at the time of extension and contraction, and generates a damping force which hinders extension and contraction.

[0004] Further, the valves provided on the piston are ring-shaped, and are urged from the back side toward the piston by a spring, and are seated or unseated on a ring-shaped outer peripheral valve seat for surrounding the outlet end of the rectification passage and a ring-shaped inner peripheral valve seat provided on the inner peripheral side of the outlet end, and open the rectification passage when the entire body is distanced from the piston due to pressure from the compression-side chamber. SUMMARY

[0005] For example, with a railway vehicle or a structure as a vibration-damping object, a damper is provided between a vehicle body and a bogie of a railway vehicle or between vehicle bodies of adjacent railway vehicles, between a structure which is elastically supported and a foundation, or between column beams of a structure, and the like, and is used for the purpose of attenuating the vibration of the vibration-damping object.

[0006] As described above, when the vibration-damping object of the damper is a heavy object such as a railway vehicle or a structure, in order to suppress the vibration of the vibration-damping object, it is necessary for the damper to generate a large damping force. In order to increase the damping force of the damper to meet such a demand, it is sufficient to increase the difference between the pressure of the extension-side chamber and the pressure of the compression-side chamber.

[0007] However, when the pressure of the extension-side chamber is greater than the pressure of the compression-side chamber, the above-mentioned valve is pressed toward the piston by the pressure of the extension-side chamber on the back surface, and is seated on the inner peripheral valve seat and the outer peripheral valve seat while the intermediate portion is bent toward the piston side, so that when the difference between the pressure of the extension-side chamber and the pressure of the compression-side chamber is increased, a large bending and plastic deformation can occur, and the passage can not be cut off. Therefore, in the conventional damper, there is a problem that it is difficult to generate a high damping force due to high pressure in the cylinder.

[0008] Therefore, an object of the present application is to provide a damper capable of withstanding high pressure in a cylinder and generating a high damping force.

[0009] To solve the problem, the damper of the present application includes: an extension body having a cylinder and a rod member movably inserted into the cylinder in an axial direction; a partition member partitioning two fluid chambers in the extension body while having a passage for communicating the fluid chambers; and a valve ring-shaped and axially movable away from or close to the partition member and for opening and closing the passage; the partition member has: an annular inner peripheral valve seat protruding in the axial direction from an end portion facing the valve and seating the inner peripheral surface side of the valve; an annular outer peripheral valve seat protruding in the axial direction from an end portion facing the valve and seating the outer peripheral surface side of the valve; and an intermediate valve seat protruding in the axial direction from an end portion facing the valve; the passage and the intermediate valve seat are formed between the inner peripheral valve seat and the outer peripheral valve seat. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 FIG. 1 is a longitudinal sectional view of a damper in an embodiment.

[0011] Figure 2 FIG. 2 is an enlarged sectional view of a piston portion of the damper in the embodiment.

[0012] Figure 3 FIG. 3 is a partial enlarged sectional view of a piston of the damper in the embodiment.

[0013] Figure 4 FIG. 4 is a plan view of the piston of the damper in the embodiment.

[0014] Figure 5 FIG. 5 is a plan view of the piston of the damper in a first modification of the embodiment. DETAILED DESCRIPTION

[0015] Hereinafter, the present application will be described based on the embodiment shown in the drawings. As shown in FIG. 1, a damper 1 according to the present application includes a cylinder 2, a rod member 3 movably inserted into the cylinder 2 in an axial direction, a piston 4 movably inserted into the cylinder 2 in the axial direction, and a valve 5. Figure 1As shown, the damper D in one embodiment includes: a telescopic body E including a cylinder 1 and a rod member 2 that is movably inserted into the cylinder 1 in the axial direction; a piston 3 as a partition member that partitions an extension-side chamber Rl and a compression-side chamber R2 as two fluid chambers in the telescopic body E while having a passage 3a for communicating the extension-side chamber Rl and the compression-side chamber R2; and a valve V that is annular and can be moved away from or close to the piston 3 in the axial direction and is used to open and close the passage 3a. Also, in the damper D, for example, use is made between a vehicle body and a bogie mounted in a railway vehicle not shown to suppress vibration of the vehicle body and the bogie.

[0016] Next, each part of the damper D will be described in detail. In the damper D of the present embodiment, as shown in Figure 1 , the telescopic body E includes: the cylinder 1; an outer tube 12 provided on the outer periphery of the cylinder 1; and the rod member 2 that is movably inserted into the cylinder 1.

[0017] In the left end of the cylinder 1, an annular rod guide 10 is fitted, and in the right end of the cylinder 1, a valve housing 11 is closed. Further, the cylinder 1 is housed in the outer tube 12 with the valve housing 11, and the right end of the outer tube 12 is closed by a bottom cover 13. A reservoir R is formed between the cylinder 1 and the outer tube 12, and is annular and stores fluid such as hydraulic oil together with gas. Figure 1 Figure 1 Figure 1

[0018] The opening portion of the left end of the outer tube 12 is closed by the rod guide 10 mounted on the outer tube 12. Also, the cylinder 1 and the valve housing 11 are sandwiched by the rod guide 10 and the bottom cover 13 fixed to the outer tube 12 and are housed in the outer tube 12 and fixed to the outer tube 12. Figure 1 The rod member 2 is slidably inserted into the rod guide 10 and into the cylinder 1 and guided by the rod guide 10 to move in the axial direction. The telescopic body E is provided in this way with the cylinder 1 and the rod member 2 that is movable in the axial direction with respect to the cylinder 1 and is telescoped by moving in the axial direction with respect to the cylinder 1 by the rod member 2.

[0019] Further, as shown in

[0020] , the rod member 2 includes: a small-diameter portion 2a provided at the front end as the right end and having a small outer diameter and the piston 3 mounted on the outer periphery as a partition member; a threaded portion 2b provided on the front end outer periphery of the small-diameter portion 2a; a first step portion 2c formed at the boundary between the small-diameter portion 2a and a position more to the left than the small-diameter portion 2a; and a second step portion 2d and a third step portion 2e provided more to the left than the first step portion 2c. Figure 2 Figure 2 Figure 2 Figure 2 ​​​​​​The rod member 2 is in the shape of a small-diameter portion divided into three stages in the outer diameter on the front end side in the buffer D of the present embodiment.

[0021] The piston 3 is ring-shaped, is mounted on the small-diameter portion 2a of the rod member 2, and is movably inserted into the cylinder 1, thereby dividing the inside of the cylinder 1 into an extension-side chamber R1 filled with a fluid such as hydraulic oil and a compression-side chamber R2. In addition, the fluid can be a liquid such as water, aqueous solution, or the like in addition to hydraulic oil. Furthermore, the fluid can be a gas instead of a liquid.

[0022] In the present embodiment, as shown in Figure 2 , the piston 3 is configured to include a first piston divided body 31 and a second piston divided body 32 divided in the axial direction. Both the first piston divided body 31 and the second piston divided body 32 are ring-shaped, are integrated after being overlapped in the axial direction, and form the piston 3.

[0023] The first piston divided body 31 is formed of cast iron such as gray cast iron, ductile cast iron, malleable cast iron, alloy cast iron, white cast iron, or the like. 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 has a feature of excellent wear resistance. The first piston divided body 31 includes a ring-shaped recessed portion 31a that is circular ring-shaped, is formed on the outer periphery on the divided surface Al side of the right end side, and is opposed to the divided surface A2 side of the left end of the second piston divided body 32; a plurality of first ports 31b that are opened in the axial direction from the divided surface Al to the reverse divided surface Bl; a ring-shaped inner peripheral valve seat 31c that protrudes in the axial direction from the reverse divided surface Bl side end and seats the inner peripheral side surface of the valve V; a ring-shaped outer peripheral valve seat 31d that protrudes in the axial direction from the reverse divided surface Bl side end and seats the outer peripheral side surface of the valve V; and an intermediate valve seat 31e that is formed between the inner peripheral valve seat 31c and the outer peripheral valve seat 31d and protrudes in the axial direction from the reverse divided surface Bl side end. Figure 1 Figure 1 The first piston divided body 31 is formed of cast iron such as gray cast iron, ductile cast iron, malleable cast iron, alloy cast iron, white cast iron, or the like. 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 has a feature of excellent wear resistance. The first piston divided body 31 includes a ring-shaped recessed portion 31a that is circular ring-shaped, is formed on the outer periphery on the divided surface Al side of the right end side, and is opposed to the divided surface A2 side of the left end of the second piston divided body 32; a plurality of first ports 31b that are opened in the axial direction from the divided surface Al to the reverse divided surface Bl; a ring-shaped inner peripheral valve seat 31c that protrudes in the axial direction from the reverse divided surface Bl side end and seats the inner peripheral side surface of the valve V; a ring-shaped outer peripheral valve seat 31d that protrudes in the axial direction from the reverse divided surface Bl side end and seats the outer peripheral side surface of the valve V; and an intermediate valve seat 31e that is formed between the inner peripheral valve seat 31c and the outer peripheral valve seat 31d and protrudes in the axial direction from the reverse divided surface Bl side end.

[0024] As shown in Figure 3 , the end surface W of the intermediate valve seat 31e is lower than the imaginary plane Z that is a plane including the end surface X of the inner peripheral valve seat 31c and the end surface Y of the outer peripheral valve seat 31d. That is, in the axial direction of the first piston divided body 31, the intermediate valve seat 31e protrudes from the reverse divided surface Bl side end at a lower height than the imaginary plane Z including both the end surface X of the inner peripheral valve seat 31c and the end surface Y of the outer peripheral valve seat 31d.

[0025] In addition, as shown in Figure 4 ​As shown, a first port 31b of the first piston divider 31 is formed on the intermediate valve seat 31e. That is, the intermediate valve seat 31e is disposed between the first ports 31b and 31b. Therefore, the intermediate valve seat 31e has multiple arc-shaped portions that divide the annulus through the first port 31b, and is formed between the inner peripheral valve seat 31c and the outer peripheral valve seat 31d. As will be described later, the first port 31b forms a channel 3a. Therefore, the intermediate valve seat 31e is disposed between the channels 3a.

[0026] The second piston segment 32 is formed of carbon steel containing 0.02 to 2.14% carbon. Carbon steel has high strength, and the second piston segment 32 has higher strength than the first piston segment 31. Furthermore, the second piston segment 32 includes: a first sealing groove 32a, which is annular and formed circumferentially on its outer periphery; and an annular groove 32b, which is formed circumferentially on its outer periphery. Figure 1 On the left-hand dividing surface A2 side end; and a plurality of second ports 32c, which open axially from the reverse dividing surface B2 and communicate with the annular groove 32b; having a threaded groove (not shown) on the inner circumference and engaging with the threaded portion 2b of the rod 2.

[0027] The first piston divider 31 and the second piston divider 32 have the same outer diameter and an inner diameter that can be mounted on the outer periphery of the small-diameter portion 2a of the rod 2. Moreover, when the centers of the first piston divider 31 and the second piston divider 32 are aligned and the first piston divider 31 is overlapped axially on the second piston divider 32, the first ports 31b of the first piston divider 31 and the annular grooves 32b of the second piston divider 32 are arranged opposite to each other.

[0028] The first and second piston segments 31 and 32 thus configured are used with the division surfaces Al and A2 facing each other and overlapping in the axial direction. Further, after the small-diameter portion 2a of the rod member 2 is inserted into the inner periphery of the first piston segment 31, the second piston segment 32 is screwed onto the threaded portion 2b formed on the outer periphery of the small-diameter portion 2a of the rod member 2. Thus, the first piston segment 31 is sandwiched by the first step portion 2c of the rod member 2 and the second piston segment 32 and is fixed to the rod member 2. Further, the piston nut 15 is screwed onto the threaded portion 2b at a position further toward the front end than the second piston segment 32. In this way, when the piston nut 15 is screwed onto the threaded portion 2b of the rod member 2, the second piston segment 32 and the piston nut 15 constitute a double nut, preventing loosening of the second piston segment 32 and preventing the piston 3 from coming off the rod member 2. Alternatively, the piston 3 can be fixed to the rod member 2 by the piston nut 15 alone without providing a threaded groove on the inner periphery of the second piston segment 32. The first and second piston segments 31 and 32 thus fixed to the rod member 2 are integrally held on the outer periphery of the small-diameter portion 2a of the rod member 2 and cooperate with each other to function as the piston 3.

[0029] Further, when the first and second piston segments 31 and 32 are overlapped, the first port 31b and the annular groove 32b face each other, the first port 31b and the second port 32c communicate with each other, and the passage 3a for communicating the extension-side chamber Rl and the compression-side chamber R2 is formed.

[0030] Further, when the first and second piston segments 31 and 32 are overlapped, the annular recess 31a provided on the outer periphery of the first piston segment 31 faces the division surface A2 of the second piston segment 32, and the annular second seal groove surrounding the outer periphery of the piston 3 is formed.

[0031] In the second seal groove formed by the annular recess 31a, the seal member 4 in the form of a circular ring for sealing between the cylinder 1 and the piston 3 is accommodated. The seal member 4 is configured to have a seal ring 4a 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 4a.

[0032] 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 hydraulic oil from flowing between the seal ring 4a and the cylinder 1 while not hindering smooth movement of the piston 3 when moving. 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 closes the space between the seal ring 4a and the piston 3 to prevent hydraulic oil from flowing into the annular recess 31a. In this way, in the damper D of the present embodiment, the seal member 4 is configured by the seal ring 4a and the O-ring 4b, but can be configured by a single member.

[0033] In order to mount the seal member 4 on the outer periphery of the piston 3, it is sufficient to house the seal member 4 in the annular recessed portion 31a from the split surface Al side of the first piston split body 31 before the first piston split body 31 and the second piston split body 32 are overlapped to be integrated. Since the split surface Al side of the first piston split body 31 of the annular recessed portion 31a is open, when the seal member 4 is mounted on the annular recessed portion 31a, it is not necessary to enlarge the diameter of the seal member 4, and the seal member 4 can be mounted in the annular recessed portion 31a without applying any load to the seal member 4.

[0034] Thus, after the seal member 4 is assembled in the first piston split body 31, if the first piston split body 31 is overlapped with the second piston split body 32, the piston 3 can be formed.

[0035] Further, in the first seal groove 32a provided on the outer periphery of the second piston split body 32, an annular piston ring 5 for sliding contact with the inner periphery of the cylinder 1 and guiding the axial movement of the piston 3 is mounted.

[0036] As described above, the piston 3 configured in this manner is mounted on the outer periphery of the small diameter portion 2a of the rod member 2. Specifically, the helical spring 16, the annular valve V, and the piston 3 are assembled in this order on the front end of the rod member 2. As described above, in the state where the first piston split body 31 and the second piston split body 32 make the split surfaces Al, A2 therebetween abut each other, the piston 3 is fixed to the outer periphery of the small diameter portion 2a of the rod member 2. In the piston 3 as a partition member, the inner peripheral valve seat 31c, the outer peripheral valve seat 31d, and the intermediate valve seat 31e are provided on the end portion facing the valve V. Figure 1 The valve V is laminated on the upper end of the piston 3, that is, on the side of the elongated chamber. As described above, the inner peripheral valve seat 31c, the outer peripheral valve seat 31d, and the intermediate valve seat 31e are provided on the end portion of the piston 3 facing the valve V. Therefore, the inner peripheral valve seat 31c, the outer peripheral valve seat 31d, and the intermediate valve seat 31e are all provided protruding toward the valve V side from the end portion of the piston 3 as a partition member facing the valve V. Further, in the shock absorber D of the present embodiment, the reverse split surface Bl of the first piston split body 31 of the piston 3 is the end portion facing the valve V.

[0037] The valve V is formed of a spring steel such as high carbon steel, alloy steel, stainless steel, etc. The spring steel has excellent characteristics of elastic limit and fatigue limit. The valve V is ring-shaped, opposes the inner peripheral valve seat 31c and the outer peripheral valve seat 31d of the first piston divided body 31 in the axial direction, and is fitted on the outer periphery between the first step portion 2c and the second step portion 2d of the rod member 2 in the axial direction. That is, the valve V has an outer diameter larger than that of the outer peripheral valve seat 31d, has an inner diameter smaller than that of the inner peripheral valve seat 31c, and is seated on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d in a state of abutting against the piston 3. In this way, when the valve V is in the state of abutting against the piston 3, the inner peripheral surface side of the valve V is seated on the inner peripheral valve seat 31c, and the outer peripheral surface side of the valve V is seated on the outer peripheral valve seat 31d.

[0038] More specifically, the valve V in the damper D of the present embodiment has an inner diameter of about 20 mm and an outer diameter of about 40 mm, is a ring-shaped plate having a plate thickness of about 1.2 mm to 2.0 mm, and has a very high bending stiffness. Therefore, a very large force is required to bend the intermediate portion in a state of supporting the inner side and the outer side of the valve V.

[0039] Further, the valve V can move away from or approach the piston 3 in the axial direction, closes the passage 3a in a state of being seated on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d of the first piston divided body 31 of the piston 3, and opens the passage 3a when the entire body is moved away from the piston 3. When the valve V abuts against the second step portion 2d, its movement to the left is limited, and the maximum lift amount from the piston 3 is set according to the setting position of the second step portion 2d. The coil spring 16 is installed between the third step portion 2e and the valve V, and applies a force to the valve V to abut against the piston 3. Figure 1

[0040] Therefore, in the damper D of the present embodiment, the valve V is applied with a force from the piston opposite side as the back surface side by the coil spring 16. Further, when the pressure of the extension side chamber R1 is higher than that of the compression side chamber R2, the valve V is seated on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d of the piston 3 and cuts off the passage 3a. On the other hand, when the pressure of the compression side chamber R2 is higher than that of the extension side chamber R1, and the force of the compression side chamber R2 acting on the piston 3 side as the front surface side through the passage 3a exceeds the force of the coil spring 16, the valve V moves away from the piston 3 and opens the passage 3a. In this way, in the damper D of the present embodiment, the valve V allows the hydraulic oil to flow only from the compression side chamber R2 to the extension side chamber R1 in the passage 3a, and seats the valve V on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d to constitute a check valve for closing the passage 3a when the hydraulic oil flows from the extension side chamber R1 to the compression side chamber R2.

[0041] ​Even if the pressure of the extension-side chamber R1 acting on the back side of the valve V is higher than the pressure of the compression-side chamber R2 acting on the front side, the intermediate portion does not bend much when the differential pressure between them is small, but the intermediate portion bends when the pressure in the cylinder 1 is increased to obtain a large damping force, and the pressure of the extension-side chamber R1 acting on the valve V becomes high.

[0042] When the valve V receives high pressure from the extension-side chamber R1 in this way to bend the intermediate portion, the intermediate portion comes into abutment with the intermediate valve seat 31e and supports the front side of the valve V, and prevents the valve V from further bending. When the force that bends the intermediate portion of the valve V is increased, the amount of bending increases, and then the valve V yields and plastically deforms. The intermediate valve seat 31e comes into abutment with the intermediate portion of the valve V before the amount of bending of the valve V reaches the amount of bending at which plastic deformation occurs, and prevents the valve V from plastically deforming.

[0043] When the intermediate valve seat 31e is provided in this way between the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, the intermediate valve seat 31e is able to support the intermediate portion of the valve V, and thus is able to prevent the valve V from plastically deforming after a large deformation.

[0044] Further, in the damper D of the present embodiment, the intermediate valve seat 31e protrudes from the end face of the piston 3 as a partition member with a protrusion height that is lower than the protrusion heights of both the inner peripheral valve seat 31c and the outer peripheral valve seat 31d. Specifically, the end face W of the intermediate valve seat 31e is located at a position lower than an imaginary plane Z that includes the end face X of the inner peripheral valve seat 31c and the end face Y of the outer peripheral valve seat 31d. Therefore, in the damper D of the present embodiment, in a state in which the valve V is overlapped with the piston 3 and seated in the inner peripheral valve seat 31c and the outer peripheral valve seat 31d in a no-load state in which no force is applied to the valve V, the intermediate portions of the inner side and the outer side of the valve V do not come into abutment with the intermediate valve seat 31e.

[0045] Further, the end surface W of the intermediate valve seat 31e is arranged at a position capable of restricting the amount of bending of the intermediate portion of the valve V, so that the bending of the intermediate portion of the valve V is limited to the range of elastic deformation with respect to the imaginary plane Z. In a state where the valve V is supported by the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, the intermediate portion not supported bends toward the piston 3 side and plastically deforms beyond the range of elastic deformation by an amount of bending which differs depending on the inner and outer diameters of the valve V and the plate thickness and material, but if the distance between the end surface W of the intermediate valve seat 31e and the imaginary plane Z is shorter than the amount of bending Lmax at which the valve V plastically deforms just beyond the range of elastic deformation, the valve V is prevented from plastically deforming. The amount of bending at which the valve V plastically deforms differs depending on the inner and outer diameters of the valve V and the plate thickness and material, so the position of the intermediate valve seat 31e is determined so that the distance Ll between the end surface W of the intermediate valve seat 31e and the imaginary plane Z satisfies 0 < Ll < Lmax. The amount of bending at which the valve V plastically deforms differs depending on the inner and outer diameters of the valve V and the plate thickness and material, so the position of the end surface W of the intermediate valve seat 31e is determined by finding the amount of bending Lmax according to the specifications of the valve V. Further, the end surface W of the intermediate valve seat 31e can be in contact with the side opposite to the piston as long as it does not exceed the imaginary plane Z, and in this case, the valve V is in abutment with the intermediate valve seat 31e in a state where it is seated on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, so the intermediate portion of the valve V can be supported to restrict bending in this case as well.

[0046] Next, the rod guide 10 is provided with a discharge passage 10a for communicating the extension-side chamber Rl and the reservoir R. A damping valve 10b is provided on the discharge passage 10a, which allows hydraulic oil to flow only from the extension-side chamber Rl to the reservoir R and applies resistance to the flow of hydraulic oil while preventing reverse flow. The discharge passage 10a is set as a one-way passage which allows hydraulic oil to flow only from the extension-side chamber Rl to the reservoir R.

[0047] 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 is provided on the suction passage 11a, which allows hydraulic oil to flow only from the reservoir R to the compression-side chamber R2 and prevents reverse flow. The suction passage 11a is set as a one-way passage which allows hydraulic oil to flow only from the reservoir R to the compression-side chamber R2.

[0048] The damper D is constructed in the above-described manner, and the operation of the damper D will be described below. First, the operation when the rod 2 moves to the left relative to the cylinder 1 and the damper D performs an extension operation will be described. Figure 1 The operation when the damper D performs an extension operation will be described. When the damper D performs an extension operation, the piston 3 moves relative to the cylinder 1Figure 1 The middle leftward movement of the piston 3 causes the extension-side chamber Rl to be compressed and the compression-side chamber R2 to be enlarged.

[0049] In this case, since the passage 3a provided in the piston 3 is closed by the valve V seated on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, the hydraulic oil in the extension-side chamber Rl flows toward the reservoir R after passing through the damping valve 10b of the discharge passage 10a. Since the movement of such hydraulic oil is resisted by the damping valve 10b, the pressure in the extension-side chamber Rl rises and becomes higher than the pressure in the reservoir R. Further, the compression-side chamber R2 is caused to have an insufficient amount of hydraulic oil due to the volume enlargement of the piston 3, but the insufficient amount of hydraulic oil is supplied from the reservoir R to the compression-side chamber R2 through the opening of the suction check valve 11b via the suction passage 11a. Therefore, the pressure in the compression-side chamber R2 becomes substantially equal to the pressure in the reservoir R.

[0050] When the shock absorber D performs the extension operation in this manner, the pressure of the extension-side chamber Rl acting on the extension-side chamber Rl side surface of the piston 3 becomes higher than the pressure in the compression-side chamber R2 acting on the compression-side chamber R2 side surface of the piston 3, and the extension-side damping force that hinders the extension operation is generated in the shock absorber D. Further, the hydraulic oil of the volume portion in which the rod member 2 is withdrawn from the cylinder 1 is supplied from the reservoir R to the compression-side chamber R2 to compensate for the volume in which the rod member 2 is withdrawn from the cylinder 1.

[0051] Next, the operation when the rod member 2 moves toward the middle right with respect to the cylinder 1 and the shock absorber D performs the contraction operation will be described. Figure 1 When the shock absorber D performs the contraction operation, the piston 3 moves toward the middle right with respect to the cylinder 1, and thus the extension-side chamber Rl is enlarged while the compression-side chamber R2 is compressed. Figure 1

[0052] In this case, the entire valve V moves away from the piston 3 and away from the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, and thus the passage 3a provided in the piston 3 is opened while the suction check valve 11b is closed and the suction passage 11a is cut off, and therefore the hydraulic oil in the compression-side chamber R2 moves toward the extension-side chamber Rl through the passage 3a. Further, when the shock absorber D performs the contraction operation, the rod member 2 intrudes into the cylinder 1, and thus the hydraulic oil of the volume portion in which the rod member 2 intrudes into the cylinder 1 is excessive in the cylinder 1. This excessive hydraulic oil in the cylinder 1 is discharged toward the reservoir R after passing through the damping valve 10b of the discharge passage 10a. Since the movement of such hydraulic oil is resisted by the damping valve 10b, the pressure in the extension-side chamber Rl 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 Rl through the passage 3a, the pressure in the compression-side chamber R2 becomes substantially equal to the pressure in the extension-side chamber Rl. ​

[0053] When the damper D performs the contraction operation in this way, the pressure of the extension-side chamber Rl acting on the side surface of the piston 3 on the extension-side chamber Rl side is approximately equal to the pressure in the compression-side chamber R2 acting on the side surface of the piston 3 on the compression-side chamber R2 side, but since the pressure receiving area that receives the pressure in the compression-side chamber R2 is larger than the pressure receiving area that receives the pressure in the extension-side chamber Rl of the piston 3, the damper D generates a compression-side damping force that hinders the contraction operation. In addition, the hydraulic oil in the volume portion in which the rod member 2 intrudes into the cylinder 1 is discharged from the cylinder 1 to the reservoir R, and the volume in which the rod member 2 intrudes into the cylinder 1 is compensated. In this way, the damper D generates a damping force when it performs the extension and contraction operation, and attenuates the vibration of the vibration object.

[0054] In the damper D of the present embodiment, there are provided: an extension and contraction body E having a cylinder 1 and a rod member 2 that is movably inserted into the cylinder 1 in the axial direction; a piston (partition member) 3 that partitions an extension-side chamber (fluid chamber) Rl and a compression-side chamber (fluid chamber) R2 in the extension and contraction body E while having a passage 3a for communicating the extension-side chamber (fluid chamber) Rl and the compression-side chamber (fluid chamber) R2 on the same circumference; and a valve V that is annular and can be moved away from or close to the piston (partition member) 3 in the axial direction and is used to open and close the passage 3a; and the piston (partition member) 3 has an intermediate valve seat 31e when the valve V is off the seat or seated between the inner peripheral valve seat 31c and the outer peripheral valve seat 31d. When the damper D performs the extension operation, when the intermediate portion is bent in a state in which the larger pressure of the extension-side chamber Rl acts on the back surface side of the valve V and the inner and outer peripheries of the valve V are supported by the inner peripheral valve seat 31c and the outer peripheral valve seat 31d before the valve V is plastically deformed, the intermediate valve seat 31e abuts against the front surface side of the intermediate portion and limits further bending of the valve V. Therefore, the valve V does not plastically deform, and when the pressure of the extension-side chamber Rl decreases, it returns to the flat original annular plate shape by the restoring force, so that the valve V can be seated on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d and cut off the passage 3a when the damper D performs the extension operation. Thus, the valve V no longer maintains the state of opening the passage 3a, and the damper D can exert the damping force as designed.

[0055] Therefore, when the damper D performs the extension and contraction operation, even if the pressure in the cylinder 1 is higher than before and a larger axial force acts on the valve V, the valve V can be prevented from plastically deforming, so that the damper D according to the present embodiment can withstand the high pressure in the cylinder 1 and generate a high damping force.

[0056] Further, the damper D of the present embodiment is configured such that the protruding height of the intermediate valve seat 31e is lower than the protruding heights of the inner peripheral valve seat 31c and the outer peripheral valve seat 31d. According to the damper D configured in this way, since the protruding height of the intermediate valve seat 31e is lower than the protruding heights of the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, even if the bending stiffness of the valve V is increased, the intermediate valve seat 31e does not interfere with the seating of the valve V on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d. Therefore, according to the damper D configured in this way, the intermediate valve seat 31e does not interfere with the seating of the valve V on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, so it is possible to prevent the valve V from being plastically deformed, and it is possible to ensure that the valve V smoothly cuts off the passage 3a, and it is possible to increase the bending stiffness of the valve V, so it is possible to generate a higher damping force. In addition, in order to make the intermediate valve seat 31e not interfere with the seating of the valve V on the inner peripheral valve seat 31c and the outer peripheral valve seat 31d, the protruding height of the intermediate valve seat 31e can also be the same as the protruding heights of the inner peripheral valve seat 31c and the outer peripheral valve seat 31d. That is, the end surface W of the intermediate valve seat 31e can also be disposed at a position where it meets an imaginary plane Z that includes the end surface X of the inner peripheral valve seat 31c and the end surface Y of the outer peripheral valve seat 31d.

[0057] Further, since the intermediate valve seat 31e only needs to be able to prevent the valve V from being plastically deformed, the intermediate portion between the opposing portions of the inner peripheral valve seat 31c and the outer peripheral valve seat 31d of the valve V can also be distanced in the circumferential direction and partially supported.

[0058] In addition, the intermediate valve seat 31e of the damper D of the present embodiment is formed with the passage 3a, so the intermediate valve seat 31e is provided on the entire circumference of the piston 3 except for the openings of the passages 3a. In this way, when the intermediate valve seat 31e is provided between the passages 3a, the intermediate valve seat 31e supports the intermediate portion of the valve V uniformly in the circumferential direction, so it is possible to uniformly suppress the bending of the intermediate portion of the valve V in the circumferential direction, and it is possible to suppress the fatigue of the valve V.

[0059] Further, when the damper D is extended, the valve V cuts off the passages 3a in the piston 3, and when the damper D is contracted, the valve V is distanced from the piston 3 and opens the passages 3a. In this way, when the damper D repeatedly extends and contracts, the valve V repeatedly collides with the first piston segment 31. What is required of the first piston segment 31 that comes into contact with the valve V is wear resistance, and materials that are excellent in wear resistance are sometimes poor in strength, and when the entire piston is formed of a material that is excellent in wear resistance, in order to make the damper generate a high damping force, when the pressure in the cylinder 1 is increased during extension and contraction of the damper and used, the strength of the piston sometimes becomes insufficient.

[0060] However, in the damper D of the present embodiment, the piston 3 is provided with the first piston divided body 31 and the second piston divided body 32 which are divided in the axial direction, the first piston divided body 31 and the second piston divided body 32 which collide with the valve V are formed of different materials, and the strength of the second piston divided body 32 is higher than that of the first piston divided body 31. Therefore, when the damper D performs the extension and contraction operation, even if the pressure in the cylinder 1 is higher than before and a larger axial force is applied to the piston 3, since the second piston divided body 32 which has high strength supports the first piston divided body 31 which has poor strength in the axial direction, the first piston divided body 31 can be prevented from being deformed. Further, since the deformation of the first piston divided body 31 which has poor strength can be supported by the second piston divided body 32 which has better strength, even if the flow passage area of the passage 3a is increased for use in a high-speed extension and contraction use of the damper D, the first piston divided body 31 can be prevented from being deformed. Therefore, according to the damper D of the present embodiment, the pressure in the cylinder 1 can be further increased, and a higher damping force can be generated.

[0061] Further, in the damper D of the present embodiment, the second piston divided body 32 is screwed with the threaded portion 2b of the rod member 2, and the first stepped portion 2c of the second piston divided body 32 and the rod member 2 sandwich the first piston divided body 31, so that the force applied to the piston 3 by the pressure in the cylinder 1 is transmitted via the second piston divided body 32 which has high strength, and thus an excessive shearing force can be prevented from being applied to the inner peripheral portion of the first piston divided body 31. Therefore, according to the damper D configured in this way, the first piston divided body 31 which has poor strength can be further protected.

[0062] Further, in the damper D of the present embodiment, since the valve V is formed of a material which has higher strength than the first piston divided body 31, the valve V can also be prevented from being deformed under high pressure in the cylinder 1.

[0063] In addition, the first piston divided body 31 can be formed of cast iron, and the valve V can be formed of spring steel. Since cast iron has excellent wear resistance, it can also withstand wear caused by repeated collisions of the valve V, and thus is optimal as a material for the first piston divided body 31. Since spring steel has excellent elastic limit and fatigue limit, it is optimal as a material for the valve V which repeatedly collides with the piston 3 while receiving a higher pressure from the back surface side which is the opposite side of the piston from the extension side chamber R1. As described above, according to the damper D in which the first piston divided body 31 is formed of cast iron and the valve V is formed of spring steel, degradation caused by wear of the first piston divided body 31 can be reduced, and degradation such as deformation and fatigue of the valve V can be reduced.

[0064] Further, in the damper D of the present embodiment, the first piston segment 31 is provided with a first port 31b that communicates from the reverse division surface Bl side to the division surface Al side, and the second piston segment 32 is provided with a second port 32c that communicates from the reverse division surface B2 side to the division surface A2 side, and the second piston segment 32 is provided with an annular groove 32b on the division surface A2 side for communicating with both the first port 31b and the second port 32c formed in the circumferential direction. According to the damper D configured in this way, when the first piston segment 31 and the second piston segment 32 are overlapped, even if they are not aligned in the circumferential direction, the first port 31b and the second port 32c can communicate through the annular groove 32b, and therefore, when the passage 3a is provided in the piston 3, the assembly of the damper D also becomes easy. The annular groove can also be provided on the division surface Al of the first piston segment 31, rather than on the second piston segment 32.

[0065] Further, the damper D of the present embodiment is provided with a reservoir R for storing hydraulic oil (fluid), a discharge passage 10a that communicates the elongation-side chamber Rl and the reservoir R, a damping valve 10b provided on the discharge passage 10a that allows the flow of hydraulic oil (fluid) only from the elongation-side chamber Rl to the reservoir R while applying resistance to the flow of hydraulic oil (fluid), a suction passage 11a that communicates the reservoir R and the compression-side chamber R2, and a suction check valve 11b provided on the suction passage 11a that allows the flow of hydraulic oil (fluid) only from the reservoir R to the compression-side chamber R2, and the valve V is a check valve that allows the flow of hydraulic oil (fluid) only from the compression-side chamber R2 to the elongation-side chamber Rl in the passage 3a. The damper D configured in this way is set as a single-phase damper in which hydraulic oil (fluid) sequentially passes through the reservoir R, the compression-side chamber R2, and the elongation-side chamber Rl and then unidirectionally returns to the reservoir R when a telescopic operation is performed. In the single-phase damper D set in this way, the entire amount of hydraulic oil (fluid) that moves from the reduced compression-side chamber R2 at the time of contraction moves to the elongation-side chamber Rl via the passage 3a. Therefore, the amount of hydraulic oil (fluid) that flows through the passage 3a in the damper D set as a single-phase damper is larger than the amount of hydraulic oil (fluid) that flows through the passage provided in the piston of a damper set as a bi-directional damper in which hydraulic oil (fluid) reciprocates between the elongation-side chamber and the compression-side chamber without passing through the reservoir at the time of telescoping. In this way, in the damper D set as a single-phase damper, the requirement for the large size of the flow passage area of the passage 3a provided in the piston 3 is high.

[0066] Therefore, the structure provided with the first piston segment 31 that allows the valve V to be seated or unseated from the piston 3, and the second piston segment 32 that has high strength is most suitable for a single-phase damper D that has to allow more hydraulic oil (fluid) to flow due to high pressure in the cylinder 1, and therefore, the practicality of the single-phase damper D can be improved.

[0067] Further, the piston 3 has a first piston divided body 31 divided in the axial direction and a second piston divided body 32 opposed to the first piston divided body 31 in the axial direction, and the seal member 4 is housed in an annular recessed portion 31a provided on the outer circumference of the first piston divided body 31 on the divided surface Al side.

[0068] In the damper D configured in this way, the seal member 4 can be housed in the annular recessed portion 31a even without expanding the diameter of the seal member 4 before the first piston divided body 31 and the second piston divided body 32 are overlapped, and when the first piston divided body 31 and the second piston divided body 32 are overlapped, the divided surface A2 of the second piston divided body 32 is opposed to the annular recessed portion 31a and a second seal groove is formed on the outer circumference of the piston 3. Thus, even if the seal member 4 housed in the annular recessed portion 31a moves in the axial direction with respect to the piston 3, the seal member 4 is clamped by the first piston divided body 31 and the second piston divided body 32 in the axial direction so as not to move, and does not come out of the annular recessed portion 31a.

[0069] Further, in the damper D of the present embodiment, in the case of mounting the seal member 4 on the piston 3, the seal member 4 is housed in the annular recessed portion 31a of the first piston divided body 31 in advance without applying any load, and then the seal member 4 can be mounted on the piston 3 simply by overlapping the first piston divided body 31 and the second piston divided body 32. Further, in the damper D of the present embodiment, in the case of removing the seal member 4 from the piston 3, the seal member 4 is simply detached from the annular recessed portion 31a of the first piston divided body 31 after the first piston divided body 31 and the second piston divided body 32 are separated.

[0070] Therefore, according to the damper D of the present embodiment, the seal member 4 can be easily mounted on the outer circumference of the piston 3 without applying an unreasonable force to expand the diameter of the seal member 4. Therefore, as the pressure in the cylinder 1 for making the damper D generate a larger damping force increases, the strength of the seal member 4 is improved, and as a result thereof, even if it is difficult to expand the diameter of the seal member 4, it is not necessary to expand the diameter of the seal member 4 when mounting the seal member 4 on the piston 3, and thus the seal member 4 can be easily mounted or detached on the piston 3. Therefore, according to the damper D of the present embodiment, even if the high strength of the seal member 4 is achieved, the seal member 4 can be easily mounted or detached on the piston 3.

[0071] Further, in the damper D of the present embodiment, the annular recess 31a for accommodating the seal member 4 is provided on the outer periphery of the 1st piston segment 31 on the segment surface Al side, but the annular recess 31a of the 1st piston segment 31 can be omitted and an annular recess for accommodating the seal member 4 can be provided on the outer periphery of the 2nd piston segment 32 on the segment surface A2 side. In this way, even if the operation of enlarging the diameter of the seal member 4 is not performed before the 1st piston segment 31 and the 2nd piston segment 32 are overlapped, the seal member 4 can be assembled on the 2nd piston segment 32, and therefore, even if the high strength of the seal member 4 is achieved, the seal member 4 can be easily mounted on or detached from the piston 3.

[0072] Further, the annular recesses can be provided on both the outer periphery of the 1st piston segment 31 on the segment surface Al side and the outer periphery of the 2nd piston segment 32 on the segment surface A2 side, and when the 1st piston segment 31 and the 2nd piston segment 32 are overlapped, one 2nd seal groove for accommodating the seal member 4 can be formed on the outer periphery of the piston 3 by the annular recesses. In this way, even if the operation of enlarging the diameter of the seal member 4 is not performed when the 1st piston segment 31 and the 2nd piston segment 32 are overlapped, the seal member 4 can be assembled on the outer periphery of the piston 3, and therefore, even if the high strength of the seal member 4 is achieved, the seal member 4 can be easily mounted on or detached from the piston 3.

[0073] Further, the 1st piston segment 31 and the 2nd piston segment 32 can be arbitrarily changed in shape when they are combined in the axial direction and function as the piston 3, and can have projections and depressions on the segment surfaces Al, A2.

[0074] Further, as described above, in the present embodiment, the piston 3 is composed of the 1st piston segment 31 and the 2nd piston segment 32, and therefore, the high pressure in the cylinder 1 can be further achieved, but the piston 3 can be composed of a single member which cannot be separated, rather than being composed of a plurality of segments. Further, the piston 3 can be composed of three or more piston segments including the 1st piston segment 31 and the 2nd piston segment 32.

[0075] Further, as described above, in order to suppress the fatigue of the valve V, the entire circumference of the intermediate portion of the valve V can be as widely as possible supported by the intermediate valve seat 31e. Therefore, as shown in the damper piston 41 of the 1st modified example of the embodiment, while the circular ring-shaped intermediate valve seat 41c is provided between the inner peripheral valve seat 41a and the outer peripheral valve seat 41b, the passages 41d, 41e are provided between the inner peripheral valve seat 41a and the intermediate valve seat 41c and between the outer peripheral valve seat 41b and the intermediate valve seat 41c, the flow path area is ensured and the wide support on the entire circumference of the intermediate portion of the valve V is achieved. Figure 5 Further, as described above, in order to suppress the fatigue of the valve V, the entire circumference of the intermediate portion of the valve V can be as widely as possible supported by the intermediate valve seat 31e. Therefore, as shown in the damper piston 41 of the 1st modified example of the embodiment, while the circular ring-shaped intermediate valve seat 41c is provided between the inner peripheral valve seat 41a and the outer peripheral valve seat 41b, the passages 41d, 41e are provided between the inner peripheral valve seat 41a and the intermediate valve seat 41c and between the outer peripheral valve seat 41b and the intermediate valve seat 41c, the flow path area is ensured and the wide support on the entire circumference of the intermediate portion of the valve V is achieved.

[0076] According to the damper configured in this way, since the entire circumference of the intermediate portion of the valve V can be supported seamlessly, fatigue caused by bending of the valve V can be further suppressed, and the passages 41d, 41e are provided between the inner peripheral valve seat 41a and the intermediate valve seat 41c and between the outer peripheral valve seat 41b and the intermediate valve seat 41c, so the flow path area can be ensured, and there is no problem in use in a use in which the damper D is stretched and contracted at high speed.

[0077] In addition, in the damper D of the foregoing embodiment, the partition member is the piston 3, but the valve housing 11 can be used as the partition member instead of the piston 3, and the valve housing 11 can have the inner peripheral valve seat, the outer peripheral valve seat, and the intermediate valve seat, or the piston 3 and the valve housing 11 can both be used as the partition member, and the inner peripheral valve seat, the outer peripheral valve seat, and the intermediate valve seat can be provided on them. In this case, the compression-side chamber R2 and the reservoir R are fluid chambers.

[0078] In addition, the damper D is a single-phase damper, but can be a bidirectional damper in which hydraulic oil reciprocates in the extension-side chamber R1 and the compression-side chamber R2 at the time of stretching and contracting. Further, as for the discharge passage 10a, the damping valve 10b, and the suction passage 11a, the positions at which they are provided can be positions other than the illustrated positions. Further, the vibration-damping object of the damper D is not limited to a railway vehicle and a structure, but can be a saddle-type vehicle, an automobile, another machine, or the like.

[0079] The preferred embodiments of the present application have been described in detail above, but modifications, alterations, and changes can be made without departing from the scope of the claims.

[0080] This application claims priority based on Japanese Patent Application No. 2020-115279 filed on July 3, 2020 with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

Claims

1. A damper, provided with: a telescopic body provided with a cylinder and a rod member movably inserted in the cylinder in an axial direction; a partition member partitioning two fluid chambers in the telescopic body while having passages for communicating the fluid chambers; and a valve ring-shaped and axially away from or close to the partition member and for opening and closing the passages; the partition member has: an annular inner peripheral valve seat protruding in the axial direction from an end facing the valve and seating an inner peripheral surface side of the valve; an annular outer peripheral valve seat protruding in the axial direction from an end facing the valve and seating an outer peripheral surface side of the valve; and an intermediate valve seat protruding in the axial direction from an end facing the valve; a plurality of the passages are provided on the partition member along the same circumference, the passages and the intermediate valve seat are formed between the inner peripheral valve seat and the outer peripheral valve seat, the intermediate valve seat is provided on the entire circumference of the partition member except for the openings of the passages while the openings of the passages and the intermediate valve seat are arranged on the same circumference.

2. The damper according to claim 1, wherein the protrusion height of the intermediate valve seat is equal to or smaller than the protrusion heights of the inner peripheral valve seat and the outer peripheral valve seat.

3. The damper according to claim 1, wherein the intermediate valve seat is provided between the passages.

4. The damper according to claim 1, wherein the intermediate valve seat is annularly formed in the circumferential direction between the inner peripheral valve seat and the outer peripheral valve seat of the partition member, a plurality of the passages are respectively provided between the inner peripheral valve seat and the intermediate valve seat and between the intermediate valve seat and the outer peripheral valve seat.

5. The damper according to any one of claims 1 to 4, wherein the partition member is a piston partitioning the cylinder into an elongation side chamber and a compression side chamber as fluid chambers while being movably inserted in the cylinder, the passages communicate the elongation side chamber and the compression side chamber and are provided with: a reservoir for storing a fluid; a discharge passage for communicating the elongation side chamber and the reservoir; a damping valve provided on the discharge passage and applying a resistance to the flow of the fluid while allowing only the flow of the fluid from the elongation side chamber to the reservoir; a suction passage for communicating the reservoir and the compression side chamber; and a suction check valve provided on the suction passage and allowing only the flow of the fluid from the reservoir to the compression side chamber; the valve is a check valve allowing only the flow of the fluid from the compression side chamber to the elongation side chamber in the passage.

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