damper

Abstract

To provide a damper capable of sufficiently generating damping force even when contraction operation is performed at very low speed.SOLUTION: A damper D of the present invention includes a cylinder 1, a rod 2 which is inserted into the cylinder 1, a piston 3 which partitions an inside of the cylinder 1 into an extension-side chamber R1 and a pressure-side chamber R2, a first cylinder 5 which forms an extension-side passage EP between the cylinder 1 and the first cylinder 5, a second cylinder 6 which forms a pressure-side passage CP between the cylinder 1 and the second cylinder 6, an outer cylinder 4 which forms a tank T for storing liquid between the first cylinder 5 and the second cylinder 6, an extension-side suction passage ES which allows only the flow of the liquid going toward the extension-side chamber R1 from the tank T, a pressure-side suction passage CS which allows only the flow of the liquid going toward the pressure-side chamber R2 from the tank T, an extension-side damping valve EV which imparts resistance to the flow of the liquid going toward the tank T from the extension-side chamber R1 through the extension-side passage EP, and a pressure side damping valve CV which imparts resistance to the flow of the liquid going toward the tank T from the pressure-side chamber R2 through the pressure-side passage CP.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a damper.

Background Art

[0002] Conventionally, this type of damper is used for an installation target to suppress vibrations of the installation target. As a damper, for example, a damper interposed between a car body and a bogie to suppress vibrations in the left - right direction with respect to the traveling direction of the car body of a railway vehicle is known.

[0003] Such a damper includes, for example, a cylinder, an outer cylinder that covers the cylinder and forms a tank between the outer cylinder and the cylinder, a piston that is slidably inserted into the cylinder and divides the inside of the cylinder into a rod - side chamber and a piston - side chamber, a rod that is inserted into the cylinder and connected to the piston, a rod guide that closes one end of the cylinder and one end of the outer tube and through which the rod is inserted on the inner circumference, a bottom cap that closes the other end of the cylinder and the other end of the outer tube, and a valve unit having a passage that is held by the bottom cap and communicates the rod - side chamber and the tank, and a variable relief valve provided in the middle of the passage (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional damper, in order to suppress the lateral vibration of a railway vehicle, when the opening pressure of a variable relief valve is fixed, if the stroke speeds are the same, the damping forces on both the extension and contraction sides are set to be equal. Therefore, in a conventional damper, if the stroke amounts are the same whether extending or contracting, the cross-sectional area of the rod is made half of the cross-sectional area of the piston so that the amount of hydraulic oil discharged from the cylinder to the tank and passing through the variable relief valve is equal.

[0006] Further, in a conventional damper, since the structure is such that when the rod enters the cylinder during the contraction operation, the entire cylinder is pressurized to generate a damping force that hinders the contraction operation, the entire amount of hydraulic oil in the cylinder is compressed during the contraction operation.

[0007] The conventional damper configured in this way can generate a damping force without problems when the stroke speed is relatively high even during the contraction operation. However, since gas is dissolved in the hydraulic oil filled in the damper and the hydraulic oil appears to have elasticity, the damping force may be insufficient when the stroke is at an extremely low speed during the contraction operation.

[0008] To avoid such a phenomenon, it is conceivable to increase the inner diameter of the cylinder and the pressure receiving area of the piston. However, since there are restrictions on the space where the damper is installed, the outer diameter of the damper often cannot be increased. Also, as described above, in a conventional damper, if the inner diameter of the cylinder is increased, the outer diameter of the rod also has to be increased, making it difficult to increase the damping force during the contraction operation at an extremely low speed.

[0009] Therefore, an object of the present invention is to provide a damper that can generate a sufficient damping force even during the contraction operation at an extremely low speed.

Means for Solving the Problems

[0010] To achieve the above object, the damper of the present invention includes a cylinder, a rod inserted axially movably into the cylinder, a piston inserted movably into the cylinder and connected to the rod to partition the inside of the cylinder into an extension chamber and a compression chamber, a first cylinder disposed on the outer peripheral side of the cylinder and forming an extension passage communicating with the extension chamber between the first cylinder and the cylinder, a second cylinder disposed on the outer peripheral side of the cylinder and forming a compression passage communicating with the compression chamber between the second cylinder and the cylinder, an outer cylinder disposed on the outer peripheral sides of the first cylinder and the second cylinder and forming a tank for storing a liquid between the first cylinder and the second cylinder, an extension suction passage allowing only the flow of the liquid from the tank toward the extension chamber, a compression suction passage allowing only the flow of the liquid from the tank toward the compression chamber, an extension damping valve providing resistance to the flow of the liquid from the extension chamber toward the tank through the extension passage, and a compression damping valve providing resistance to the flow of the liquid from the compression chamber toward the tank through the compression passage.

[0011] According to the damper configured as described above, during the extension operation, the extension damping valve provides resistance to the flow of the liquid from the extension chamber toward the tank, compressing only the liquid in the extension chamber to generate an extension damping force, so that the liquid column compression rigidity can be increased. Further, in the damper of the present embodiment, during the extension operation, the extension damping valve provides resistance to the flow of the liquid from the extension chamber toward the tank, compressing only the liquid in the extension chamber to generate an extension damping force, and during the contraction operation, the compression damping valve provides resistance to the flow of the liquid from the compression chamber toward the tank, compressing only the liquid in the compression chamber to generate a compression damping force. Therefore, since the outer diameter of the rod and the inner diameter of the cylinder are not restricted as in the conventional damper, the outer diameter of the rod can be reduced and the inner diameter of the cylinder can be increased as long as there are no strength problems.

[0012] As described above, according to the damper of the present invention, the liquid column compression rigidity during the extension operation can be increased and the outer diameter of the rod can be reduced, so that a damping force can be generated without shortage even when the extension operation is performed at an extremely low speed. Further, according to the damper of the present invention, the extension-side passage and the compression-side passage are respectively formed by a first cylinder and a second cylinder arranged on the outer periphery of the cylinder, and can rotate relative to each other in the circumferential direction before being fixed. Therefore, even if the installation positions of the extension-side damping valve and the compression-side damping valve with respect to the outer cylinder are changed according to the equipment on which the damper is installed, the outlet of the extension-side passage and the extension-side damping valve can be arranged in close proximity, and the outlet of the compression-side passage and the compression-side damping valve can be arranged in close proximity. The installation position of the extension-side damping valve and the compression-side damping valve on the outer cylinder can be easily changed according to the equipment, and the damper is not enlarged, so the mountability and practicality of the equipment can be improved.

[0013] Further, the cylinder in the damper may include an extension-side recess provided on the outer periphery and forming an extension-side passage between the first cylinder, a compression-side recess provided on the outer periphery and forming a compression-side passage between the second cylinder, and a convex portion protruding radially outward from between the extension-side recess and the compression-side recess and partitioning the extension-side recess and the compression-side recess.

[0014] According to the damper configured as described above, if the extension-side recess and the compression-side recess are provided by processing the outer periphery of the cylinder, the extension-side passage between the cylinder and the first cylinder and the compression-side passage between the cylinder and the second cylinder can be formed. Therefore, compared with the case where recesses are formed on the inner circumferences of the first cylinder and the second cylinder to form the extension-side passage and the compression-side passage, the processing is easy and the processing cost can be reduced.

[0015] Furthermore, the damper has a first hole and a second hole in the outer cylinder that communicate the inside and outside, the first cylinder has a first boss portion facing the first hole and having an inner circumference communicating with the extension passage, the second cylinder has a second boss portion facing the second hole and having an inner circumference communicating with the compression passage, the extension damping valve installed outside the outer cylinder through an extension pipe inserted into the first hole and the first boss portion communicates with the extension passage, and the extension damping valve communicates with the tank through the outside of the extension pipe within the first hole. The compression damping valve installed outside the outer cylinder through a compression pipe inserted into the second hole and the second boss portion communicates with the compression passage, and the compression damping valve may communicate with the tank through the outside of the compression pipe within the second hole.

[0016] According to the damper configured in this way, the extension pipe and the compression pipe that reduce the volume in the tank become shorter, and the first hole and the second hole can be used as passages for returning the liquid that has passed through the extension damping valve and the compression damping valve to the tank. Furthermore, since the first cylinder includes the first boss portion and the second cylinder includes the second boss portion, and it is not necessary to increase the thickness of the first cylinder and the second cylinder for attaching the extension pipe and the compression pipe, the volume in the tank can be ensured without significantly increasing the diameter of the outer cylinder. Also, according to the damper configured in this way, since the first cylinder includes the first boss portion and the second cylinder includes the second boss portion, the attachment of the extension pipe and the compression pipe becomes easier, and the assembly work of the damper becomes easier.

[0017] Further, the damper may include permanent magnets that are attached to a plane for circumferential alignment on the outer circumferences of the end portions where the first cylinder and the second cylinder face each other and abut against each other. According to the damper configured in this way, since the permanent magnets are installed on the planes provided on the outer circumferences of the first cylinder and the second cylinder, contaminants such as cutting chips generated when processing the components constituting the damper in the liquid in the tank can be captured by the permanent magnets, the liquid can be purified, and the biting of contaminants by the extension-side damping valve, the compression-side damping valve, the extension-side suction check valve, and the compression-side suction check valve can be suppressed. Further, since the permanent magnets are attached to the plane that serves as a mark for circumferential alignment between the first cylinder and the second cylinder, there is no concern about the permanent magnets falling off from the first cylinder and the second cylinder, and since the operator visually recognizes the position of the plane when attaching the permanent magnets, the first cylinder and the second cylinder can be accurately arranged at appropriate positions without error.

Advantages of the Invention

[0018] According to the damper of the present invention, even when the damper contracts at an extremely low speed, a sufficient damping force can be generated.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIG. 1, the damper D in the present embodiment includes a cylinder 1, a rod 2 that is inserted into the cylinder 1 so as to be axially movable, a piston 3 that is movably inserted into the cylinder 1 and is connected to the rod 2 to partition the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, a first cylinder 5 that is disposed on the outer peripheral side of the cylinder 1 and forms an extension passage EP that communicates with the extension chamber R1 between the first cylinder 5 and the cylinder 1, a second cylinder 6 that is disposed on the outer peripheral side of the cylinder 1 and forms a compression passage CP that communicates with the compression chamber R2 between the second cylinder 6 and the cylinder 1, an outer cylinder 4 that is disposed on the outer peripheral sides of the first cylinder 5 and the second cylinder 6 and forms a tank T that stores liquid between the first cylinder 5 and the second cylinder 6, an extension suction passage ES that allows only the flow of liquid from the tank T toward the extension chamber R1, a compression suction passage CS that allows only the flow of liquid from the tank T toward the compression chamber R2, an extension damping valve EV that provides resistance to the flow of liquid from the extension chamber R1 toward the tank T via the extension passage EP, and a compression damping valve CV that provides resistance to the flow of liquid from the compression chamber R2 toward the tank T via the compression passage CP. Although not shown in detail, the damper D of the present embodiment is interposed between the car body and the bogie of a railway vehicle, and suppresses vibrations in the horizontal lateral direction with respect to the traveling direction of the vehicle of the car body by the damping force exerted during expansion and contraction. Note that the damper D may be used with an installation target other than railway vehicles.

[0021] In the description of the damper D of the present invention, the vertical direction in FIG. 1 is taken as the vertical direction of the damper D, the horizontal direction in FIG. 1 is taken as the horizontal direction of the damper D, and the direction penetrating the paper surface in FIG. 1 is taken as the lateral direction of the damper D.

[0022] Hereinafter, each part will be described in detail. As shown in FIG. 1, the cylinder 1 is cylindrical, and has an annular head-side flange 1a that protrudes radially outward from the outer periphery of the left end in FIG. 1, an annular bottom-side flange 1b that protrudes radially outward from the outer periphery of the right end in FIG. 1, an annular convex portion 1c that protrudes radially outward from the outer periphery between the head-side flange 1a and the bottom-side flange 1b, an extension-side recess 1d formed in an annular recess between the outer periphery of the head-side flange 1a and the convex portion 1c, a compression-side recess 1e formed in an annular recess between the outer periphery of the bottom-side flange 1b and the convex portion 1c, a through hole 1f provided near the head-side flange 1a and communicating with the extension-side recess 1d inside the cylinder 1, a through hole 1g provided near the bottom-side flange 1b and communicating with the compression-side recess 1e inside the cylinder 1, and two annular grooves 1h, 1i formed along the circumferential direction on the outer periphery of the convex portion 1c. The cylinder 1 is manufactured, for example, by subjecting a thick-walled pipe material as a base material to machining such as cutting or grinding to form the extension-side recess 1d, the compression-side recess 1e, and the annular grooves 1h, 1i on the outer periphery of the pipe material. In this way, when the extension-side recess 1d, the compression-side recess 1e, and the annular grooves 1h, 1i are formed on the outer periphery of the pipe material, the head-side flange 1a, the bottom-side flange 1b, and the convex portion 1c can be formed on the outer periphery of the cylinder 1.

[0023] Sealing rings 20 and 21 are respectively accommodated in the annular grooves 1h and 1i formed in the convex portion 1c of the cylinder 1. Further, the right end of the cylinder 1 in FIG. 1 is closed by a valve case 9 fitted to the inner periphery of the right end. An annular rod guide 10 is attached to the left end of the cylinder 1 in FIG. 1.

[0024] On the outer periphery of the cylinder 1, as shown in FIGS. 1 and 3, a first cylinder 5 and a second cylinder 6 are fitted. The first cylinder 5 has its inner periphery fitted to the outer periphery of the head-side flange 1a of the cylinder 1 and the outer periphery of the convex portion 1c. The right end of the first cylinder 5 in FIG. 1 is disposed at the axial center of the convex portion 1c in the cylinder 1, and the left end of the first cylinder 5 in FIG. 1 is disposed to the left beyond the left end of the cylinder 1 in FIG. 1. The inner periphery of the first cylinder 5 faces the outer periphery of the head-side flange 1a of the cylinder 1 and also faces the seal ring 20 housed in the annular groove 1h of the convex portion 1c, covering the entire extension-side recess 1d on the outer periphery of the cylinder 1. Therefore, when the cylinder 1 is fitted into the first cylinder 5, an extension-side passage EP formed by the extension-side recess 1d is formed between the first cylinder 5 and the cylinder 1. The extension-side passage EP communicates with the extension-side chamber R1 inside the cylinder 1 through the through-hole 1f provided in the cylinder 1.

[0025] Furthermore, as shown in FIGS. 2 and 3, the first cylinder 5 includes an annular first boss portion 5a attached to the outer periphery by welding. Inside the first boss portion 5a, it communicates with the inner peripheral side of the first cylinder 5 through a hole 5c that penetrates the wall of the first cylinder 5, and a continuous hole that penetrates the first cylinder 5 in the radial direction is formed by the first boss portion 5a and the hole 5c. Therefore, the inside of the first boss portion 5a communicates with the extension-side passage EP between the first cylinder 5 and the cylinder 1. Note that the inner diameter of the first boss portion 5a is larger than the inner diameter of the hole 5c, and the continuous hole formed by the first boss portion 5a and the hole 5c has a step in the middle. Also, on the outer periphery of the right end of the first cylinder 5 in FIG. 1, as shown in FIG. 2, a flat surface 5b is provided in a part of the circumferential direction. In the damper D of the present embodiment, the first cylinder 5 is provided on the outer peripheral side of the cylinder 1 in this way, and the extension-side passage EP is provided between the cylinder 1 and the first cylinder 5. If the first cylinder 5 is not provided, it is necessary to provide the first boss portion at a position facing the through-hole 1f provided outside the operating range of the piston 3 of the cylinder 1, so the installation position of the first boss portion is restricted. However, by providing the first cylinder 5, the first boss portion 5a can be installed within the range of the first cylinder 5 without being restricted by the position of the through-hole 1f, so the degree of freedom in the installation position of the first boss portion 5a is improved.

[0026] Further, the second cylinder 6 has an outer diameter equal to the outer diameter of the first cylinder 5, and its inner circumference is fitted to the outer circumference of the bottom-side flange 1b of the cylinder 1 and the outer circumference of the convex portion 1c. The left end of the second cylinder 6 in FIG. 1 is disposed at the axial center of the convex portion 1c in the cylinder 1, and the right end of the second cylinder 6 in FIG. 1 is disposed to the right beyond the right end of the cylinder 1 in FIG. 1. The inner circumference of the second cylinder 6 faces the outer circumference of the bottom-side flange 1b of the cylinder 1 and faces the seal ring 21 accommodated in the annular groove 1i of the convex portion 1c, covering the entire pressure-side recess 1e on the outer circumference of the cylinder 1. Therefore, when the cylinder 1 is fitted into the second cylinder 6, a pressure-side passage CP formed by the pressure-side recess 1e is formed between the second cylinder 6 and the cylinder 1. The pressure-side passage CP communicates with the pressure-side chamber R2 in the cylinder 1 through the through-hole 1g provided in the cylinder 1. Thus, when the cylinder 1 is inserted into the inner circumferential sides of the first cylinder 5 and the second cylinder 6, the extension-side recess 1d provided on the outer circumference of the cylinder 1 and forming an extension-side passage EP between the first cylinder 5, the pressure-side recess 1e provided on the outer circumference of the cylinder 1 and forming a pressure-side passage CP between the second cylinder 6, and the convex portion 1c of the cylinder 1 partition the extension-side recess 1d and the pressure-side recess 1e. In this embodiment, two annular grooves 1h and 1i are provided on the outer circumference of one convex portion 1c to accommodate the seal ring 20 in close contact with the first cylinder 5 in the annular groove 1h and the seal ring 21 in close contact with the second cylinder 6 in the annular groove 1i to seal between the extension-side passage EP and the pressure-side passage CP. However, one annular groove may be provided for the convex portion 1c to accommodate one seal ring that is in close contact with both the inner circumference of the first cylinder 5 and the inner circumference of the second cylinder 6 in the annular groove to seal between the extension-side passage EP and the pressure-side passage CP. Although the extension-side passage EP and the pressure-side passage CP are partitioned by the convex portion 1c in this way, since the extension-side passage EP and the pressure-side passage CP are sealed by the seal rings 20 and 21, the outer circumference of the convex portion 1c does not have to contact the inner circumference of the first cylinder 5 and the outer circumference of the second cylinder 6.

[0027] Furthermore, as shown in FIGS. 2 and 3, the second cylinder 6 is provided with an annular second boss portion 6a attached to the outer periphery by welding. Inside the second boss portion 6a, it communicates with the inner peripheral side of the second cylinder 6 through a hole 6c penetrating the wall of the second cylinder 6, and a continuous hole penetrating the second cylinder 6 in the radial direction is formed by the second boss portion 6a and the hole 6c. Therefore, the inside of the second boss portion 6a communicates with the pressure side passage CP between the second cylinder 6 and the cylinder 1. Note that the inner diameter of the second boss portion 6a is larger than the inner diameter of the hole 6c, and the continuous hole formed by the second boss portion 6a and the hole 6c has a step in the middle. Also, as shown in FIG. 2, a flat surface 6b is provided on a part of the outer periphery at the right end of the second cylinder 6 in FIG. 1 in the circumferential direction. In the damper D of the present embodiment, the second cylinder 6 is provided on the outer peripheral side of the cylinder 1 in this way, and the pressure side passage CP is provided between the cylinder 1 and the second cylinder 6. When the second cylinder 6 is not provided, since it is necessary to provide the second boss portion at a position facing the through hole 1g provided outside the operating range of the piston 3 of the cylinder 1, the installation position of the second boss portion is restricted. However, by providing the second cylinder 6, the second boss portion 6a can be installed within the range of the second cylinder 6 without being restricted by the position of the through hole 1g, so the degree of freedom in the installation position of the second boss portion 6a is improved.

[0028] When the first cylinder 5 and the second cylinder 6 configured as described above are fitted on the outer periphery of the cylinder 1, the end portions 5d and 6d facing each other are abutted against each other. Then, with the flat surfaces 5b and 6b formed on the outer peripheries of the end portions 5d and 6d of the first cylinder 5 and the second cylinder 6 as marks, when the first cylinder 5 and the second cylinder 6 are rotated and arranged so that the flat surfaces 5b and 6b are at the same position in the circumferential direction, the relative circumferential arrangement of the first boss portion 5a and the second boss portion 6a of the first cylinder 5 and the second cylinder 6 becomes the designed arrangement.

[0029] Further, when the end portions 5d and 6d of the first cylinder 5 and the second cylinder 6 are abutted against each other and the planes 5b and 6b are opposed to each other, a flush plane is formed by the planes 5b and 6b. And a permanent magnet 40 is attached to the flush plane formed by the planes 5b and 6b. When the first cylinder 5 and the second cylinder 6 are made of a soft magnetic material, the permanent magnet 40 can be attached to the first cylinder 5 and the second cylinder 6 by its own attracting force. When the first cylinder 5 and the second cylinder 6 are made of a non-magnetic material, the permanent magnet 40 may be attached to the first cylinder 5 and the second cylinder 6 by adhesion. Since the marks for circumferential alignment between the first cylinder 5 and the second cylinder 6 are the planes 5b and 6b in this way, when the first cylinder 5 and the second cylinder 6 are abutted against each other to align the circumferential positions, a flush plane for installing the permanent magnet 40 is formed by the planes 5b and 6b. Therefore, the permanent magnet 40 can be easily attached and the dropout of the permanent magnet 40 can be prevented. Further, the above-described planes 5b and 6b are arranged below the tank T when the damper D is installed horizontally, and the permanent magnet 40 is also arranged below the tank T. Therefore, since the permanent magnet 40 is in the liquid and is arranged below the tank T where contaminants accumulate during the assembly of the damper D, it becomes easier to catch the contaminants.

[0030] The outer cylinder 4 is arranged on the outer peripheral sides of the first cylinder 5 and the second cylinder 6, covers the first cylinder 5 and the second cylinder 6, and houses the inner cylinder 1, the first cylinder 5, and the second cylinder 6 inward. Further, the outer cylinder 4 forms a tank T for storing a liquid in the annular gap between the first cylinder 5 and the second cylinder 6. Note that the tank T is filled with a gas in addition to the liquid. Note that the liquid is, for example, hydraulic oil, but may be a liquid other than hydraulic oil, and the gas is, for example, an inert gas such as nitrogen, but may be air in addition to the inert gas.

[0031] As shown in Fig. 3, the outer cylinder 4 is provided with a first hole 4a that radially faces the first boss portion 5a of the first cylinder 5 and a second hole 4b that radially faces the second boss portion 6a of the second cylinder 6. Further, a first pedestal 23 and a second pedestal 24 are attached to the outer periphery of the outer cylinder 4. Since the extension-side damping valve EV is disposed radially outside the first hole 4a in the outer cylinder 4 and the compression-side damping valve CV is disposed radially outside the second hole 4b, the first hole 4a and the second hole 4b are arranged at positions sufficiently separated from each other in the circumferential direction or the axial direction of the outer cylinder 4 so that the extension-side damping valve EV and the compression-side damping valve CV do not interfere with each other.

[0032] The first boss portion 5a of the first cylinder 5 described above is disposed at a position that radially faces the first hole 4a of the outer cylinder 4, and the second boss portion 6a of the second cylinder 6 is disposed at a position that radially faces the second hole 4b of the outer cylinder 4. Therefore, the planes 5b and 6b, which serve as marks for the relative positions of the first cylinder 5 and the second cylinder 6, are provided on the first cylinder 5 and the second cylinder 6 so that the first boss portion 5a and the second boss portion 6a can face the corresponding first hole 4a and second hole 4b according to the installation positions of the first hole 4a and the second hole 4b of the outer cylinder 4. Thus, when the circumferential relative position of the first cylinder 5 and the second cylinder 6 is positioned by aligning the planes 5b and 6b with each other in the circumferential direction and the outer cylinder 4 is disposed at an appropriate position in the circumferential direction with respect to the first cylinder 5 and the second cylinder 6, the first boss portion 5a and the second boss portion 6a face the corresponding first hole 4a and second hole 4b.

[0033] As shown in Fig. 3, the first pedestal 23 is a seat for attaching the extension-side damping valve EV to the damper D. The inner surface facing the outer periphery of the outer cylinder 4 is curved along the outer periphery of the outer cylinder 4 and the inner surface is in contact with the outer periphery of the outer cylinder 4. The end surface on the side opposite to the outer cylinder is rectangular and forms a flat valve mounting surface 23a. Further, the first pedestal 23 is provided with a hole 23b that penetrates through the center along the radial direction of the outer cylinder 4 and communicates with the first hole 4a, and screw holes (not shown) provided at the four corners on the side opposite to the outer cylinder. The first pedestal 23 configured in this way is fixed to the outer periphery of the outer cylinder 4 by welding.

[0034] As shown in Fig. 3, the second pedestal 24 is a pedestal for attaching the pressure-side damping valve CV to the damper D. The inner surface facing the outer periphery of the outer cylinder 4 is curved along the outer periphery of the outer cylinder 4 and is in contact with the outer periphery of the outer cylinder 4. The end surface on the side opposite to the outer cylinder is rectangular and is a flat valve mounting surface 24a. Further, the second pedestal 24 includes a hole 24b that penetrates through the center along the radial direction of the outer cylinder 4 and communicates with the second hole 4b, and screw holes (not shown) provided at the four corners on the side opposite to the outer cylinder. The second pedestal 24 configured in this way is fixed to the outer periphery of the outer cylinder 4 by welding.

[0035] A rod guide 10 is fitted to the inner circumferences at the left end in Fig. 1 of the cylinder 1, the first cylinder 5, and the outer cylinder 4. The rod guide 10 is annular, supports the rod 2 that is inserted through the inner circumference and is axially movable inside the cylinder 1, and guides the axial movement of the rod 2 with respect to the cylinder 1. Further, a disk-shaped valve case 9 is fitted to the right ends in Fig. 1 of the cylinder 1 and the second cylinder 6, and is closed by the valve case 9. Furthermore, a bottom cap 16 is attached to the right end in Fig. 1 of the outer cylinder 4, and is closed by the bottom cap 16.

[0036] The left end of the rod 2 in Fig. 1 protrudes outside the cylinder 1, and the right end in Fig. 1 is connected to a piston 3 that is axially movably inserted inside the cylinder 1. Further, a bracket 2a that enables attachment to an attachment portion provided on a bogie in a railway vehicle (not shown) is provided at the left end of the rod 2 in Fig. 1. The rod 2 is axially movably inserted inside the cylinder 1 in the left-right direction in Fig. 1 and can be displaced axially with respect to the cylinder 1 together with the piston 3. Further, the piston 3 divides the inside of the cylinder 1 into an extension chamber R1 filled with liquid and a pressure chamber R2, and when moving axially inside the cylinder 1 together with the rod 2, the extension chamber R1 and the pressure chamber R2 expand and contract.

[0037] The valve case 9 is disc-shaped and has a small-diameter portion 9a that fits inside the cylinder 1 provided at the left end in FIG. 1, a large-diameter portion 9b that is connected to the right in FIG. 1 from the small-diameter portion 9a and fits inside the second cylinder 6, a flange 9c provided on the outer circumference of the large-diameter portion 9b that abuts against the right end in FIG. 1 of the second cylinder 6, a recess 9d that opens from the left end in FIG. 1 of the small-diameter portion 9a, and a plurality of ports 9e that open from the right end in FIG. 1 of the large-diameter portion 9b and communicate with the recess 9d. The ports 9e are arranged in a plurality along the circumference along the circumferential direction of the recess 9d.

[0038] Also, inside the recess 9d of the valve case 9, there is an annular valve body 15a that opens and closes the left end in FIG. 1 which is the outlet end of the port 9e, an annular retaining ring 15b attached to the side portion on the opening side of the recess 9d of the valve case 9, and a compression-side check valve 15 provided with a coil spring 15c interposed between the valve body 15a and the retaining ring 15b to bias the valve body 15a toward the bottom side of the recess 9d is accommodated.

[0039] The bottom cap 16 is attached to the right end in FIG. 1 of the outer cylinder 4 by welding, closes the right end in FIG. 1 of the outer cylinder 4, and has a recess 16a that fits into the right end in FIG. 1 of the large-diameter portion 9b of the valve case 9 and a passage 16b that connects the recess 16a to the tank T. In addition, a bracket 16c is provided at the right end in FIG. 1 to enable attachment to an attachment portion provided on the vehicle body of a railway vehicle (not shown). Therefore, the damper D can be interposed between the bogie and the vehicle body of a railway vehicle (not shown) via the bracket 2a of the rod 2 and the bracket 16c of the bottom cap 16.

[0040] The inlet end of the port 9e in the valve case 9 communicates with the tank T through the recess 16a and the passage 16b, and the outlet end of the port 9e communicates with the compression-side chamber R2. Therefore, the compression-side suction passage CS is formed by the port 9e, the recess 16a, and the passage 16b.

[0041] The pressure-side check valve 15 allows the valve body 15a to compress the coil spring 15c and move leftward in Fig. 1 within the recess 9d to open the valve for the flow of liquid passing through the port 9e from the tank T toward the pressure-side chamber R2. Thus, the port 9e is opened to allow the flow of liquid moving from the tank T toward the pressure-side chamber R2. Conversely, for the flow of liquid from the pressure-side chamber R2 toward the tank T, the pressure-side check valve 15 closes the valve by pressing the valve body 15a against the bottom of the recess 9d by the pressure in the pressure-side chamber R2 and the biasing force of the coil spring 15c to block the port 9e, thereby preventing the flow of liquid moving from the pressure-side chamber R2 toward the tank T. Since the pressure-side check valve 15 opens the ports 9e arranged side by side on the same circumference, even if the flow rate of liquid from the tank T toward the pressure-side chamber R2 is large, it can allow the movement of liquid from the tank T to the pressure-side chamber R2 without much resistance. In this way, the pressure-side check valve 15 is installed in the pressure-side suction passage CS and is set as a one-way passage that allows only the flow of liquid from the tank T toward the pressure-side chamber R2 in the pressure-side suction passage CS and blocks the reverse flow.

[0042] Next, the rod guide 10 is annular. As shown in FIGS. 1 and 3, it has an outer cylinder fitting portion 10a that fits onto the inner circumference of the outer cylinder 4, a collar fitting portion 10b that is continuous to the right of the outer cylinder fitting portion 10a in FIG. 1 and has a smaller outer diameter than the outer cylinder fitting portion 10a with an annular collar 14 fitted onto its outer circumference, a first cylinder fitting portion 10c that is continuous to the right of the collar fitting portion 10b in FIG. 1 and has a smaller outer diameter than the collar fitting portion 10b with the first cylinder 5 fitted onto its outer circumference, a cylinder fitting portion 10d that is continuous to the right of the first cylinder fitting portion 10c in FIG. 1 and has a smaller outer diameter than the first cylinder fitting portion 10c with the cylinder 1 fitted onto its outer circumference, an annular valve mounting portion 10e that protrudes from the inner circumference at the right end of the cylinder fitting portion 10d in FIG. 1, eight ports 10f that open at the right end of the cylinder fitting portion 10d in FIG. 1 and communicate with the outer circumference of the collar fitting portion 10b through an opening from the outer circumference of the valve mounting portion 10e, and a return passage 10g that opens from the right end of the outer cylinder fitting portion 10a in FIG. 1 and communicates with the left end. The eight ports 10f open at equal intervals on the same circumference surrounding the rod 2 at the right end of the cylinder fitting portion 10d in FIG. 1 and extend radially to open at equal intervals at the bottom of an annular groove 10b1 provided along the circumferential direction on the outer circumference of the collar fitting portion 10b. Since the annular groove 10b1 is provided on the entire outer circumference of the collar fitting portion 10b, it communicates with all of the eight ports 10f.

[0043] Also, on the inner circumference of the rod guide 10, a cylindrical bush 11 is mounted that slidably contacts the outer circumference of the rod 2 to guide the axial movement of the rod 2 and ensure smooth movement of the rod 2, and a seal ring 12 that closely adheres to the outer circumference of the rod 2 is mounted.

[0044] The collar 14 is annular, has an outer diameter smaller than the inner diameter of the outer cylinder 4, a notch 14a provided on a part of its outer circumference, a plurality of passages 14b that open from the end face of the notch 14a and communicate with the inner circumference, and a pin insertion groove 14c provided at a position on the outer circumference opposite to the notch 14a in the circumferential direction, and is fitted onto the outer circumference of the collar fitting portion 10b of the rod guide 10.

[0045] When Color 14 is press-fitted onto the outer periphery of the color fitting portion 10b of the rod guide 10, it can be fixed to the outer periphery of the color fitting portion 10b, and each passage 14b of Color 14 faces the annular groove 10b1 respectively. All of the passages 14b and all of the ports 10f communicate with each other through the annular groove 10b1. Note that in the damper D of the present embodiment, the rod guide 10 is provided with an annular groove 10b1 that forms an annular passage for communicating the port 10f and the passage 14b on the outer periphery of the color fitting portion 10b. However, an annular groove for forming an annular passage for communicating the port 10f and the passage 14b may be provided on the inner periphery of Color 14 instead of the outer periphery of the color fitting portion 10b.

[0046] Then, the rod guide 10 with Color 14 fitted on its outer periphery fits the cylinder fitting portion 10d into the cylinder 1, the first cylinder fitting portion 10c into the first cylinder 5, and the outer cylinder fitting portion 10a into the outer cylinder 4. When this is done, the left end of the cylinder 1 in FIG. 1 abuts against the right end of the first cylinder fitting portion 10c in FIG. 1, and the left end of the first cylinder 5 in FIG. 1 abuts against the right end of the color fitting portion 10b in FIG. 1. Also, the outer diameter of the color fitting portion 10b is smaller than the outer diameter of the first cylinder 5, the axial lengths of Color 14 and the color fitting portion 10b are equal, and when the first cylinder fitting portion 10c of the rod guide 10 is fitted into the first cylinder 5, the outer peripheral side of the left end of the first cylinder 5 in FIG. 1 abuts against Color 14, and Color 14 is fixed to the color fitting portion 10b.

[0047] Also, when the rod guide 10 is fitted to the left end in FIG. 1 of the cylinder 1, the first cylinder 5, and the outer cylinder 4, the passage 14b opening into the notch 14a of Color 14 communicates with the tank T. Therefore, the inlet end of the port 10f in the rod guide 10 communicates with the tank T through the passage 14b, and the outlet end of the port 10f communicates with the extending chamber R1 inside the cylinder 1. In this way, the extending suction passage ES is formed by the port 10f, the annular groove 10b1, and the passage 14b.

[0048] Note that the passage 14b opens into a notch 14a provided on the outer periphery of the collar 14, and the cross-sectional area of the gap between the notch 14a and the outer cylinder 4 is made larger than the total cross-sectional area of all the passages 14b and the total cross-sectional area of all the ports 10f. By providing the notch 14a in this way, even if it is not possible to provide a sufficient gap between the outer peripheral surface of the collar 14 and the inner peripheral surface of the outer cylinder 4, when the liquid passes through the gap between the end face of the notch 14a and the outer cylinder 4, the gap does not impose an excessive resistance on the flow of the liquid. Further, as shown in FIG. 1, the collar 14 is prevented from rotating in the circumferential direction and positioned in the circumferential direction with respect to the outer cylinder 4 by inserting a pin 18 passing through the outer cylinder 4 into the pin insertion groove 14c, so that the notch 14a faces downward of the damper D. Therefore, in the tank T of the damper D used in the horizontal position, the gas fills the upper part of the tank T in FIG. 1, and since the notch 14a where the inlet end of the passage 14b is formed always faces downward of the damper D and faces the liquid, consideration is given so that the inlet end of the passage 14b does not face the gas. Note that the return passage 10g provided in the rod guide 10 has an opening facing the pin insertion groove 14c of the collar 14, and consideration is given so that it is not blocked even by the fitting of the collar 14 to the collar fitting portion 10b of the rod guide 10.

[0049] Also, in the present embodiment, the collar 14 is fitted on the outer periphery of the collar fitting portion 10b of the rod guide 10, and the space between the collar 14 and the rod guide 10 is sealed by press-fitting the collar 14 onto the outer periphery of the rod guide 10. However, a sealing member may be provided between the collar 14 and the rod guide 10 to prevent the port 10f from communicating with the tank T without passing through the passage 14b.

[0050] Furthermore, on the outer periphery of the valve mounting portion 10e of the rod guide 10, there are a valve body 13a formed of an annular plate that is seated away from the right end in FIG. 1 of the cylinder fitting portion 10d and can open and close the opening end of the port 10f, a spring receiver 13b having an L-shaped cross section that is fitted to the outer periphery of the valve mounting portion 10e and faces the valve body 13a in the axial direction, a conical coil spring 13c serving as a spring that is interposed between the valve body 13a and the spring receiver 13b and biases the valve body 13a toward the right end of the cylinder fitting portion 10d, and a retaining ring 13d that is mounted in an annular groove 10e1 provided on the outer periphery of the right end in FIG. 1, which is the tip of the valve mounting portion 10e, to prevent the spring receiver 13b from coming off the valve mounting portion 10e. The valve body 13a has its inner periphery slidably contacting the outer periphery of the valve mounting portion 10e and can be displaced in the axial direction, which is the left-right direction in FIG. 1, of the outer periphery of the valve mounting portion 10e. When it is separated from the right end in FIG. 1 of the cylinder fitting portion 10d, it opens the port 10f, and when it abuts against the right end in FIG. 1 of the cylinder fitting portion 10d, it blocks the port 10f.

[0051] The above-described extension check valve 13 is installed in the extension suction passage ES formed by the port 10f, the annular groove 10b1, and the passage 14b to open and close the port 10f. When the liquid flows from the tank T toward the extension chamber R1 through the port 10f, the valve body 13a compresses the coil spring 13c and moves the outer periphery of the valve mounting portion 10e of the rod guide 10 toward the tip side, which is the right side in FIG. 1, to open the valve. Thus, the port 10f is opened to allow the liquid flow moving from the tank T toward the extension chamber R1. Conversely, when the liquid flows from the extension chamber R1 toward the tank T, the valve body 13a is pressed against the right end in FIG. 1 of the cylinder fitting portion 10d by the pressure in the extension chamber R1 and the biasing force of the coil spring 13c to close the port 10f and close the valve. Therefore, the liquid flow moving from the extension chamber R1 toward the tank T is blocked. The extension check valve 13 is installed in the extension suction passage ES as described above, and is set as a one-way passage that allows only the liquid flow from the tank T toward the pressure chamber R2 through the extension suction passage ES and blocks the flow in the opposite direction.

[0052] Since the extension-side check valve 13 opens the ports 10f that are arranged in a plurality on the same circumference around the rod 2 of the rod guide 10, even if the flow rate of the liquid from the tank T to the extension-side chamber R1 is large, the movement of the liquid from the tank T to the extension-side chamber R1 can be allowed without giving much resistance. In this way, when providing the extension-side suction passage ES that communicates the extension-side chamber R1 and the tank T, a plurality of ports 10f are provided around the rod 2 with respect to the rod guide 10 through which the rod 2 is inserted in the center and fitted to the cylinder 1 to secure the flow passage area. Therefore, a large flow rate of liquid can be supplied from the tank T to the extension-side chamber R1, and there is no shortage of liquid supply in the extension-side chamber R1. Note that the spring in the extension-side check valve 13 may be a spring other than the coil spring 13c. Note that the number of ports 10f installed is appropriately set so that the supply of liquid is not delayed in the extension-side chamber R1 when the liquid of the maximum flow rate assumed to pass through the extension-side suction passage ES in the environment where the damper D is actually used flows.

[0053] The rod guide 10 configured as described above is fitted with the collar 14 on its outer periphery and the extension side check valve 13 is attached to the valve mounting portion 10e, and then it is fitted to the left end in FIG. 1 of the cylinder 1 with the first cylinder 5 and the second cylinder 6 fitted on its outer periphery. At that time, the outer periphery of the first cylinder fitting portion 10c of the rod guide 10 is fitted to the inner periphery of the left end in FIG. 1 of the first cylinder 5. Further, a valve case 9 with a pressure side check valve 15 attached is fitted to the inner periphery of the right end in FIG. 1 of the second cylinder 6 and the cylinder 1 with the first cylinder 5 and the second cylinder 6 fitted on its outer periphery. The cylinder 1, the first cylinder 5, the second cylinder 6, the valve case 9, and the rod guide 10 assembled in this way are inserted into the outer cylinder 4 with the bottom cap 16 attached to the right end in FIG. 1, and then are clamped by the seal case 17 screwed to the inner periphery of the left end in FIG. 1 of the outer cylinder 4 and the bottom cap 16 and fixed inside the outer cylinder 4. The seal case 17 is annular and has a screw portion 17a screwed to the screw portion 4c formed on the inner periphery of the left end in FIG. 1 of the outer cylinder 4 on its outer periphery, and a seal ring 17b and a dust seal 17c that are housed in the annular recess provided at the left end east end in FIG. 1 on its inner periphery and are in sliding contact with the outer periphery of the rod 2. Therefore, when the seal case 17 is screwed and tightened to the outer cylinder 4, an axial force is applied to the cylinder 1, the first cylinder 5, the second cylinder 6, the valve case 9, and the rod guide 10 by the seal case 17 and the bottom cap 16 and they are fixed inside the outer cylinder 4. The outer periphery of the rod 2 is sealed by the seal ring 17b as described above, and the liquid that adheres to the outer periphery of the rod 2 and crosses the seal ring 12 attached to the rod guide 10 is scraped off by the seal ring 17b and then returned to the tank T through the return passage 10g of the rod guide 10.

[0054] Note that, as described above, the collar 14 has the passage 14b opened to the notch 14a to suck the liquid from the tank T and supply it to the extension side chamber R1, but a suction pipe 142 may be attached to the collar 141 as shown in FIG. 4.

[0055] As shown in Fig. 4, Color 141 is annular, with an outer diameter smaller than the inner diameter of the outer cylinder 4, a larger inner diameter on the tank side, and a large inner diameter portion 141a and a small inner diameter portion 141b on the inner circumference. It also has a recess 141c that opens radially from a part of the inner circumference in the circumferential direction of the large inner diameter portion 141a, five insertion holes 141d that open from the tank-side end and communicate with the recess 141c, a pin insertion hole 141e that opens from the non-tank-side end, and a pin insertion groove 141f provided at the upper end in Fig. 4 on the outer circumference. It is fitted on the outer circumference of the color fitting portion 10b of the rod guide 10. Suction pipes 142 with their tips arranged near the center of the tank T are respectively installed in the insertion holes 141d of Color 141.

[0056] As shown in Fig. 4, the rod guide 10 onto which Color 141 is fitted has a large diameter portion 10b2 where the color fitting portion 10b is fitted to the large inner diameter portion 141a of Color 141 and a small diameter portion 10b3 where it is fitted to the small inner diameter portion 141b, according to the inner circumferential shape of Color 141. It also has annular grooves 10b4 and 10b5 for accommodating seal rings 143 and 144 on the outer circumferences of the large diameter portion 10b2 and the small diameter portion 10b3 respectively, and has the same configuration as the rod guide 10 shown in Fig. 1.

[0057] The axial length of the collar 141 is equal to the axial length of the collar fitting portion 10b. The axial length of the large inner diameter portion 141a is longer than the axial length of the large diameter portion 10b2, and the axial length of the small inner diameter portion 141b is shorter than the axial length of the small diameter portion 10b3. When the collar 141 is fitted into the collar fitting portion 10b of the rod guide 10, the pin 19 attached to the rod guide 10 is inserted into the pin insertion hole 141e and is prevented from rotating. Then, the large inner diameter portion 141a of the collar 141 fits into the large diameter portion 10b2 of the collar fitting portion 10b and is in close contact with the seal ring 143. The small inner diameter portion 141b of the collar 141 fits into the small diameter portion 10b3 of the collar fitting portion 10b and is in close contact with the seal ring 144. At the same time, an annular passage G is formed between the inner circumference of the collar 141 and the collar fitting portion 10b. The annular passage G communicates with the recess 141c formed on the inner circumference of the collar 141 and is communicated with the inside of the tank T through the suction pipe 142. Further, since the annular passage G is formed so as to surround the periphery of the collar fitting portion 10b, it can communicate with the recess 141c of the collar 141 and the suction pipe 142 so as to face all of the eight ports 10f that open at a position surrounding the rod 2 of the rod guide 10 and extend radially and lead to the outer periphery of the collar fitting portion 10b. In this way, instead of providing an annular groove on the inner circumference of the collar 141 or the outer circumference of the collar fitting portion 10b, an annular passage G that communicates the port 10f and the passage 14b may be provided by configuring the inner circumference shape of the collar 141 and the outer circumference shape of the collar fitting portion 10b of the rod guide 10 as described above.

[0058] Thus, in the rod guide 10 with the collar 141 shown in FIG. 4 attached, a rod-side suction passage ES is formed by the suction pipe 142, the recess 141c, the annular passage G, and the port 10f. Similar to the damper D shown in FIG. 1, a rod-side check valve 13 is provided in the rod-side suction passage ES. Therefore, when the liquid level in the rod-side chamber R1 is insufficient, the rod-side check valve 13 opens and the liquid is supplied from the tank T to the rod-side chamber R1 through the rod-side suction passage ES.

[0059] Further, when the rod guide 10 with the collar 141 is fitted into the cylinder 1, the first cylinder 5, and the outer cylinder 4, the collar 141 has a pin 18 penetrating the outer cylinder 4 inserted into the pin insertion groove 141f, similar to the collar 14 shown in FIG. 1, to prevent circumferential rotation with respect to the outer cylinder 4 and to be positioned. As a result, the suction pipe 142 is disposed below the tank T. The suction pipe 142 extends from the collar 141 into the tank T, with its tip disposed near the center of the tank T. The damper D, which is used in a horizontal position, vibrates as it expands and contracts, and it can be expected that the tip of the suction pipe 142 will always be inside the liquid even if the liquid level in the tank T fluctuates, thereby preventing gas from mixing into the extension chamber R1.

[0060] Subsequently, the extension damping valve EV is attached to the first pedestal 23 attached to the outer cylinder 4 via an adapter 31, and the compression damping valve CV is attached to the second pedestal 24 attached to the outer cylinder 4 via an adapter 33.

[0061] The adapter 31 includes a rectangular base plate 31a that abuts against the valve attachment surface 23a at the end of the first pedestal 23 on the side opposite to the outer cylinder, a stepped hole 31b that penetrates the center of the base plate 31a and communicates with the hole 23b of the first pedestal 23 and has a smaller inner diameter on the side opposite to the outer cylinder than on the outer cylinder side, and an inclined hole 31c that opens from the end surface on the side opposite to the outer cylinder, avoiding the stepped hole 31b, and leads to the hole 23b. The adapter 31 configured in this way, although not shown in the figure, has insertion holes at its four corners that allow bolts to pass through. After being overlapped with the first pedestal 23, bolts (not shown in the figure) inserted into the insertion holes are coupled to the screw holes of the first pedestal 23, thereby bolt-fastening the adapter 31 to the first pedestal 23.

[0062] One end of the extension-side pipe 32 is fitted into the portion with a small inner diameter of the stepped hole 31b of the adapter 31. The other end of the extension-side pipe 32 is fitted into the first boss portion 5a of the first cylinder 5. Therefore, through the extension-side pipe 32, the extension-side passage EP between the cylinder 1 and the first cylinder 5 communicates with the inside of the stepped hole 31b. Note that the extension-side pipe 32 is sandwiched between the stepped portion of the stepped hole 31b and the step of the continuous hole formed by the first boss portion 5a and the hole 5c in the first cylinder 5 described above, and is fixed to the adapter 31 and the first cylinder 5.

[0063] The adapter 33 includes a rectangular base plate 33a that abuts on the valve mounting surface 24a at the anti-outer cylinder side end of the second pedestal 24, a stepped hole 33b that penetrates the center of the base plate 33a and communicates with the hole 24b of the second pedestal 24 and has a smaller inner diameter on the anti-outer cylinder side than on the outer cylinder side, and an inclined hole 33c that opens from the end surface on the anti-outer cylinder side avoiding the stepped hole 33b and leads to the hole 24b. The adapter 33 configured in this way has insertion holes for allowing bolts to pass through at the four corners (not shown). After being overlaid on the second pedestal 24, the adapter 33 is bolted to the second pedestal 24 by coupling bolts (not shown) inserted into the insertion holes to the screw holes of the second pedestal 24.

[0064] One end of the pressure-side pipe 34 is fitted into the portion with a small inner diameter of the stepped hole 33b of the adapter 33. The other end of the pressure-side pipe 34 is fitted into the second boss portion 6a of the second cylinder 6. Therefore, through the pressure-side pipe 34, the pressure-side passage CP between the cylinder 1 and the second cylinder 6 communicates with the inside of the stepped hole 33b. Note that the pressure-side pipe 34 is sandwiched between the stepped portion of the stepped hole 33b and the step of the continuous hole formed by the second boss portion 6a and the hole 6c in the second cylinder 6 described above, and is fixed to the adapter 33 and the second cylinder 6.

[0065] In the present embodiment, the extension-side damping valve EV includes a valve housing 60 held by the first pedestal 23 via the adapter 31, a variable relief valve 61 provided in the valve housing 60, and a solenoid 62 for adjusting the opening pressure of the variable relief valve 61.

[0066] The valve housing 60 is fixed to the adapter 31 by bolts (not shown) while being in contact with the opposite first pedestal side surface of the base plate 31a of the adapter 31. Thus, the valve housing 60 is fixed to the first pedestal 23 via the adapter 31. The valve housing 60 is provided with a flow path 60a having one end communicating with the stepped hole 31b in the adapter 31 and the other end communicating with the inclined hole 31c. The variable relief valve 61 is provided in the valve housing 60 and in the middle of the flow path 60a. In the present embodiment, the extension side damping valve EV is connected to the first pedestal 23 via the adapter 31. However, for example, the base plate 31a of the adapter 31 may be eliminated, and a structure may be adopted in which the extension side pipe 32 is held by the valve housing 60 so that the extension side damping valve EV is directly held by the first pedestal 23, or a structure in which the adapter 31 is integrally and inseparably provided with respect to the valve housing 60 may be adopted.

[0067] The variable relief valve 61 includes a valve body 61a that opens and closes the flow path 60a, a spring 61b that biases the valve body 61a in a direction to block the flow path 60a, and a pilot passage 61c that applies pressure in a direction to open the flow path 60a. The flow path 60a communicates with the extension side chamber R1 via the extension side pipe 32, the extension side passage EP, and the through hole 1f, and also communicates with the tank T through the inclined hole 31c and inside the first hole 4a and outside the extension side pipe 32 (between the inner circumference of the first hole 4a and the outer circumference of the extension side pipe 32). The pilot passage 61c in the variable relief valve 61 applies the pressure of the extension side chamber R1 to the valve body 61a in the valve opening direction.

[0068] The solenoid 62 is attached to the left end in FIG. 3 of the valve housing 60. Although not shown in detail, it includes a plunger 62a, a coil that drives the plunger 62a, a fixed core that attracts the plunger 62a when the coil is energized, and a frame 62b that houses the coil and the fixed core. And when the solenoid 62 is energized, it drives the plunger 62a in a direction protruding from the frame 62b and applies a thrust force that presses the valve body 61a of the variable relief valve 61 in the valve opening direction against the biasing force of the spring 61b. The solenoid 62 can adjust the thrust force up and down according to the applied amount of energization. Also, when the solenoid 62 is not energized, it does not apply a thrust force to the valve body 61a.

[0069] Therefore, since the solenoid 62 can adjust the thrust force applied to the valve body 61a according to the amount of energization, it can adjust the valve opening pressure of the variable relief valve 61 to be larger or smaller. In the case of this embodiment, for the variable relief valve 61, when the current amount supplied to the solenoid 62 is maximum, the valve opening pressure is minimum, and when no current is supplied to the solenoid 62, the valve opening pressure is maximum. Therefore, the variable relief valve 61 can control the pressure of the upstream extension chamber R1 communicated through the extension passage EP by the amount of energization to the solenoid 62.

[0070] In this embodiment, the pressure-side damping valve CV includes a valve housing 63 held by the second pedestal 24 via an adapter 33, a variable relief valve 64 provided in the valve housing 63, and a solenoid 65 that adjusts the valve opening pressure of the variable relief valve 64.

[0071] The valve housing 63 is fixed to the adapter 33 by bolts (not shown) while being in contact with the counter first pedestal side surface of the base plate 33a of the adapter 33. Thus, the valve housing 63 is fixed to the second pedestal 24 via the adapter 33. The valve housing 63 is provided with a flow path 63a having one end communicating with the stepped hole 33b in the adapter 33 and the other end communicating with the hole 33c, and the variable relief valve 61 is provided in the valve housing 63 in the middle of the flow path 63a. In the present embodiment, the pressure-side damping valve CV is connected to the second pedestal 24 via the adapter 33. For example, the base plate 33a of the adapter 33 may be abolished, and a structure may be adopted in which the pressure-side pipe 34 is held by the valve housing 63 so that the pressure-side damping valve CV is directly held by the second pedestal 24, or a structure in which the adapter 33 is integrally and inseparably provided with respect to the valve housing 63 may be adopted.

[0072] The variable relief valve 64 includes a valve body 64a that opens and closes the flow path 63a, a spring 64b that biases the valve body 64a in a direction to block the flow path 63a, and a pilot passage 64c that applies pressure in a direction to open the flow path 63a. The flow path 63a communicates with the pressure-side chamber R2 via the pressure-side pipe 34, the pressure-side passage CP, and the through hole 1g, and also communicates with the tank T via the hole 33c and inside the second hole 4b outside the pressure-side pipe 34 (between the inner circumference of the second hole 4b and the outer circumference of the pressure-side pipe 34). The pilot passage 64c in the variable relief valve 64 applies the pressure of the pressure-side chamber R2 to the valve body 64a in the valve-opening direction.

[0073] The solenoid 65 is attached to the left end in FIG. 3 of the valve housing 63. Although not shown in detail, it includes a plunger 65a, a coil that drives the plunger 65a, a fixed core that attracts the plunger 65a when the coil is excited, and a frame 65b that houses the coil and the fixed core. And when the solenoid 65 is energized, it drives the plunger 65a in a direction protruding from the frame 65b, and applies a thrust force that presses the valve body 64a of the variable relief valve 64 in the valve opening direction against the biasing force of the spring 64b. The solenoid 65 can adjust the thrust force up and down according to the applied energization amount. Also, when the solenoid 65 is not energized, it does not apply a thrust force to the valve body 64a.

[0074] Therefore, since the solenoid 65 can adjust the thrust force applied to the valve body 64a according to the energization amount, it can adjust the opening pressure of the variable relief valve 64 to be larger or smaller. In the case of this embodiment, the variable relief valve 64 has the minimum opening pressure when the current amount supplied to the solenoid 65 is maximum, and the maximum opening pressure when no current is supplied to the solenoid 65. Therefore, the variable relief valve 64 can control the pressure of the upstream pressure side chamber R2 communicated through the pressure side passage CP by the energization amount to the solenoid 65.

[0075] The damper D is configured as described above, and the operation of the damper D will be described below. First, the operation when the damper D extends will be described. When the damper D extends, the piston 3 moves to the left in FIG. 1 with respect to the cylinder 1, so that the extension chamber R1 shrinks and the compression chamber R2 expands. Since the shrinking extension chamber R1 communicates with the tank T through the extension passage EP and the extension damping valve EV, the liquid in the extension chamber R1 is discharged to the tank T through the extension passage EP and the extension damping valve EV. A resistance is applied to such liquid movement by the variable relief valve 61, so that the pressure in the extension chamber R1 is adjusted to be higher than the pressure in the tank T and equal to the opening pressure of the variable relief valve 61. Also, although the liquid is insufficient in the compression chamber R2 whose volume expands due to the movement of the piston 3, the shortage of the liquid is supplied to the compression chamber R2 from the tank T through the compression suction passage CS when the compression check valve 15 opens. Therefore, the pressure in the compression chamber R2 becomes approximately equal to the pressure in the tank T.

[0076] As described above, during the extension operation of the damper D, the pressure in the extension chamber R1 acting on the extension chamber side surface of the piston 3 becomes higher than the pressure in the compression chamber R2 acting on the compression chamber side surface of the piston 3, and the damper D generates an extension damping force that hinders its own extension operation. Also, since the opening pressure of the variable relief valve 61 can be adjusted in magnitude according to the amount of current supplied to the solenoid 62, the extension damping force generated during the extension operation of the damper D can be adjusted in height by the extension damping valve EV.

[0077] Next, the operation when the damper D contracts will be described. When the damper D contracts, the piston 3 moves to the right in FIG. 1 with respect to the cylinder 1, so that the pressure chamber R2 is reduced and the extension chamber R1 is enlarged. Since the reduced pressure chamber R2 communicates with the tank T through the pressure side passage CP and the pressure side damping valve CV, the liquid in the pressure chamber R2 is discharged to the tank T through the pressure side passage CP and the pressure side damping valve CV. Since a resistance is applied to such liquid movement by the variable relief valve 64, the pressure in the pressure chamber R2 is adjusted to be higher than the pressure in the tank T and equal to the opening pressure of the variable relief valve 64. Also, in the extension chamber R1 where the volume expands due to the movement of the piston 3, the liquid is insufficient, but this insufficient amount of liquid is supplied to the extension chamber R1 from the tank T through the extension suction passage ES when the extension check valve 13 opens. Therefore, the pressure in the extension chamber R1 becomes approximately equal to the pressure in the tank T.

[0078] As described above, during the contraction operation of the damper D, the pressure in the pressure chamber R2 acting on the pressure chamber side surface of the piston 3 becomes higher than the pressure in the extension chamber R1 acting on the extension chamber side surface of the piston 3, and the damper D generates a pressure side damping force that hinders its own contraction operation. Also, since the opening pressure of the variable relief valve 64 can be adjusted in magnitude according to the amount of current supplied to the solenoid 65, the pressure side damping force generated during the contraction operation of the damper D can be adjusted in magnitude by the pressure side damping valve CV.

[0079] As described above, when the damper D extends, the extension side damping valve EV applies a resistance to the flow of the liquid from the extension chamber R1 to the tank T, compresses only the liquid in the extension chamber R1, and generates an extension side damping force. Therefore, the liquid column compression rigidity becomes high, and a sufficient damping force can be generated even when extending at an extremely low speed, without causing a lack of damping force. Also, when the damper D contracts, the pressure side damping valve CV applies a resistance to the flow of the liquid from the pressure chamber R2 to the tank T, compresses only the liquid in the pressure chamber R2, and generates a pressure side damping force. Therefore, a sufficient damping force can be generated even when extending at an extremely low speed, without causing a lack of damping force.

[0080] Further, since the damper D generates the extension-side damping force with the extension-side damping valve EV and the compression-side damping force with the compression-side damping valve CV, there is no constraint that the cross-sectional area of the rod 2 must be half of the cross-sectional area of the piston 3. Therefore, the outer diameter of the rod 2 can be made as small as possible considering the strength surface, and the inner diameter of the cylinder 1 can be made as large as possible, and the compression-side damping force during the contraction operation of the damper D can be increased.

[0081] When the damper D contracts, as described above, the liquid is supplied from the tank T to the extension-side chamber R1 through the extension-side suction passage ES. However, if the cross-sectional area of the rod 2 is reduced and the inner diameter of the cylinder 1 is increased to increase the compression-side damping force of the damper D, the amount of liquid to be supplied from the tank T to the extension-side chamber R1 when the damper D contracts increases.

[0082] On the other hand, in the damper D of the present embodiment, since the extension-side check valve 13 opens and closes a plurality of ports 10f provided around the rod 2 of the rod guide 10 with an annular valve body 13a disposed on the outer periphery of the rod 2, an extension-side suction passage ES with a sufficiently large flow passage area can be formed with respect to the small rod guide 10.

[0083] Therefore, even if the damper D with a reduced cross-sectional area of the rod 2 and an increased inner diameter of the cylinder 1 to further increase the compression-side damping force when the damper D contracts in the extremely low speed range contracts at high speed, an extension-side suction passage ES with a sufficiently large flow passage area can be formed in the rod guide 10, so that poor liquid supply does not occur in the extension-side chamber R1.

[0084] As described above, the damper D of the present embodiment includes a cylinder 1, a rod 2 inserted into the cylinder 1 so as to be axially movable, a piston 3 movably inserted into the cylinder 1 and connected to the rod 2 to partition the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, a first cylinder 5 disposed on the outer peripheral side of the cylinder 1 and forming an extension passage EP communicating with the extension chamber R1 between the first cylinder 5 and the cylinder 1, a second cylinder 6 disposed on the outer peripheral side of the cylinder 1 and forming a compression passage CP communicating with the compression chamber R2 between the second cylinder 6 and the cylinder 1, an outer cylinder 4 disposed on the outer peripheral sides of the first cylinder 5 and the second cylinder 6 and forming a tank T for storing a liquid between the first cylinder 5 and the second cylinder 6, an extension suction passage ES allowing only the flow of the liquid from the tank T toward the extension chamber R1, a compression suction passage CS allowing only the flow of the liquid from the tank T toward the compression chamber R2, an extension damping valve EV providing resistance to the flow of the liquid from the extension chamber R1 toward the tank T through the extension passage EP, and a compression damping valve CV providing resistance to the flow of the liquid from the compression chamber R2 toward the tank T through the compression passage CP.

[0085] The damper D configured as described above generates an extension damping force by compressing only the liquid in the extension chamber R1 by providing resistance to the flow of the liquid from the extension chamber R1 to the tank T with the extension damping valve EV during the extension operation, so that the liquid column compression rigidity can be increased. Further, in the damper D of the present embodiment, during the extension operation, the extension damping valve EV provides resistance to the flow of the liquid from the extension chamber R1 to the tank T, compressing only the liquid in the extension chamber R1 to generate an extension damping force, and during the contraction operation, the compression damping valve CV provides resistance to the flow of the liquid from the compression chamber R2 to the tank T, compressing only the liquid in the compression chamber R2 to generate a compression damping force. Therefore, since the outer diameter of the rod 2 and the inner diameter of the cylinder 1 are not restricted as in the conventional damper, the outer diameter of the rod 2 can be reduced and the inner diameter of the cylinder 1 can be increased as long as there are no strength problems.

[0086] As described above, according to the damper D of the present embodiment, the liquid column compression rigidity during the extension operation can be increased and the outer diameter of the rod 2 can be reduced, so that a damping force can be generated without shortage even when the extension operation is performed at an extremely low speed. Further, according to the damper D of the present embodiment, the inner diameter of the cylinder 1 can be increased, so that the damping force during the contraction operation at an extremely low speed can also be increased. Further, according to the damper D of the present embodiment, the extension passage EP and the pressure passage CP are respectively formed by the first cylinder 5 and the second cylinder 6 disposed on the outer periphery of the cylinder 1, and can rotate relative to each other in the circumferential direction before being fixed. Therefore, two passages, i.e., the extension passage EP and the pressure passage CP, can be provided on the outer periphery of the cylinder 1 without significantly reducing the volume in the tank T, and the circumferential arrangement of the first cylinder 5 and the circumferential arrangement of the second cylinder 6 can be set independently of each other. Thus, the outlet of the extension passage EP and the extension damping valve EV can be arranged in close proximity to shorten the pipeline length for communicating the two, and the outlet of the pressure passage CP and the pressure damping valve CV can be arranged in close proximity to shorten the pipeline length (the total length of the extension pipe 32 and the total length of the pressure pipe 34) for communicating the two.

[0087] As described above, according to the damper D of the present embodiment, since the first cylinder 5 and the second cylinder 6 on the outer periphery of the cylinder 1 can rotate relative to each other in the circumferential direction before being fixed, even if the installation positions of the extension damping valve EV and the pressure damping valve CV with respect to the outer cylinder 4 are changed according to the equipment on which the damper D is installed, the outlet of the extension passage EP and the extension damping valve EV can be arranged in close proximity while the outlet of the pressure passage CP and the pressure damping valve CV can be arranged in close proximity. As described above, since the pipeline length can be shortened even if the installation positions of the extension damping valve EV and the pressure damping valve CV with respect to the outer cylinder 4 are changed, the ratio of reducing the volume in the tank T by the pipeline can also be reduced, and the diameter of the outer cylinder 4 does not become extremely thick to ensure the volume in the tank T. Therefore, according to the damper D of the present embodiment, it is easy to change the installation locations of the extension damping valve EV and the pressure damping valve CV on the outer cylinder 4 according to the equipment, and the damper D does not become larger in size. Thus, the mountability and practicality of the damper D on the equipment can be improved.

[0088] Furthermore, according to the damper D of the present embodiment, since the first cylinder 5 and the second cylinder 6 can be fitted to the outer periphery of the cylinder 1 from both sides of the cylinder 1, compared with the case where the first cylinder 5 and the second cylinder 6 are formed of a single pipe, when assembling the damper D, the seal rings 20 and 21 between the cylinder 1, the first cylinder 5, and the second cylinder 6 are not damaged or worn. Note that the first cylinder 5 and the second cylinder 6 may have their facing end portions 5d and 6d spaced apart from each other. However, as in the damper D of the present embodiment, it is advantageous in that the end portions 5d and 6d can be brought into contact with each other and clamped between the rod guide 10 and the valve case 9 so as to be fixed to the outer periphery of the cylinder 1 without play. Also, when the end portions 5d and 6d are brought into contact with each other and the first cylinder 5 and the second cylinder 6 are clamped between the rod guide 10 and the valve case 9, the first cylinder 5 and the second cylinder 6 do not need to be joined by welding or screwing, so the assemblability is improved and the processing cost can be reduced.

[0089] Also, in the damper D of the present embodiment, the cylinder 1 includes an extension-side recess 1d provided on the outer periphery and forming an extension-side passage EP between the cylinder 1 and the first cylinder 5, a compression-side recess 1e provided on the outer periphery and forming a compression-side passage CP between the cylinder 1 and the second cylinder 6, and a convex portion 1c protruding radially outward from between the extension-side recess 1d and the compression-side recess 1e and partitioning the extension-side recess 1d and the compression-side recess 1e. In the damper D configured in this way, if the outer periphery of the cylinder 1 is processed to provide the extension-side recess 1d and the compression-side recess 1e, the extension-side passage EP between the cylinder 1 and the first cylinder 5 and the compression-side passage CP between the cylinder 1 and the second cylinder 6 can be formed. Therefore, compared with the case where recesses are formed in the inner circumferences of the first cylinder 5 and the second cylinder 6 to form the extension-side passage EP and the compression-side passage CP, the processing is easy and the processing cost can be reduced.

[0090] Note that in the damper D of the present embodiment, the head-side flange 1a and the bottom-side flange 1b are provided at the ends of the cylinder 1, but these head-side flange 1a and bottom-side flange 1b may be omitted. However, the cylinder 1 having the head-side flange 1a and the bottom-side flange 1b has the advantage that play is less likely to occur between the cylinder 1, the first cylinder 5, and the second cylinder 6.

[0091] Furthermore, in the damper D of the present embodiment, the outer cylinder 4 has a first hole 4a and a second hole 4b that communicate the inside and the outside. The first cylinder 5 has a first boss portion 5a on the outer periphery at a position facing the first hole 4a, and the inside of the first boss portion 5a communicates with the extension side passage EP. The second cylinder 6 has a second boss portion 6a on the outer periphery at a position facing the second hole 4b, and the inside of the second boss portion 6a communicates with the compression side passage CP. An extension side damping valve EV installed outside the outer cylinder 4 is communicated with the extension side passage EP through an extension side pipe 32 inserted into the first hole 4a and the first boss portion 5a, and the extension side damping valve EV is communicated with the tank T through the outside of the extension side pipe 32 inside the first hole 4a. A compression side damping valve CV installed outside the outer cylinder 4 is communicated with the compression side passage CP through a compression side pipe 34 inserted into the second hole 4b and the second boss portion 6a, and the compression side damping valve CV is communicated with the tank T through the outside of the compression side pipe 34 inside the second hole 4b.

[0092] According to the damper D configured as described above, before the first cylinder 5 and the second cylinder 6 on the outer periphery of the cylinder 1 are fixed, they can rotate relative to each other in the circumferential direction. Therefore, the first boss portion 5a can be arranged in the vicinity of the extension side damping valve EV, and the second boss portion 6a can be arranged in the vicinity of the compression side damping valve CV. As a result, the extension side pipe 32 and the compression side pipe 34 that reduce the volume in the tank T become shorter, and the first hole 4a and the second hole 4b can be used as passages for returning the liquid that has passed through the extension side damping valve EV and the compression side damping valve CV to the tank T. Furthermore, since the first cylinder 5 is provided with the first boss portion 5a and the second cylinder 6 is provided with the second boss portion 6a, and it is not necessary to thicken the entire length of the first cylinder 5 and the second cylinder 6 for the attachment of the extension side pipe 32 and the compression side pipe 34, the volume in the tank T can be ensured without significantly increasing the diameter of the outer cylinder 4. Also, according to the damper D of the present embodiment, since the first cylinder 5 is provided with the first boss portion 5a and the second cylinder 6 is provided with the second boss portion 6a, the attachment of the extension side pipe 32 and the compression side pipe 34 becomes easy, and the assembly work of the damper D becomes easy.

[0093] Further, in the damper D of the present embodiment, the first cylinder 5 and the second cylinder 6 abut against each other with the end portions 5d and 6d facing each other, and have flat surfaces 5b and 6b for circumferential alignment on the outer circumferences of the end portions 5d and 6d facing each other, and are provided with permanent magnets 40 attached to the flat surfaces 5b and 6b. According to the damper D configured in this way, since the permanent magnets 40 are installed on the flat surfaces 5b and 6b provided on the outer circumferences of the first cylinder 5 and the second cylinder 6, contaminants such as cutting chips generated when processing the components constituting the damper D in the liquid in the tank T can be captured by the permanent magnets 40, and the liquid can be purified to suppress the biting of contaminants by the extension side damping valve EV, the compression side damping valve CV, the extension side check valve 13, and the compression side check valve 15. Further, since the permanent magnet 40 is attached to the flat surfaces 5b and 6b which serve as marks for circumferential alignment of the first cylinder 5 and the second cylinder 6, there is no worry about the permanent magnet 40 falling off from the first cylinder 5 and the second cylinder 6, and since the operator visually recognizes the positions of the flat surfaces 5b and 6b when attaching the permanent magnet 40, the first cylinder 5 and the second cylinder 6 can be accurately arranged at appropriate positions.

[0094] Note that the damper D of the present embodiment is annular and includes a rod guide 10 that fits on the outer circumference of the cylinder 1 and through which the rod 2 is inserted on the inner circumference. The rod guide 10 includes an extension side suction passage ES that allows only the flow of liquid from the tank T toward the extension side chamber R1. The extension side suction passage ES includes a plurality of ports 10f that open side by side around the rod 2 at the cylinder side end of the cylinder fitting portion 10d of the rod guide 10 that fits on the cylinder 1. Therefore, according to the damper D of the present embodiment, an extension side suction passage ES with a sufficiently secured flow passage area can be formed for the small rod guide 10, and even when the damper D contracts at high speed, insufficient suction of liquid in the extension side chamber R1 does not occur, and a stable compression side damping force can be generated.

[0095] Further, the damper D of the present embodiment is annular and axially movable relative to the cylinder-side end of the cylinder fitting portion 10d of the rod guide 10, and includes an annular valve body 13a that opens and closes the outlet end of each port 10f, and a spring (conical coil spring) 13c that biases the valve body 13a toward the cylinder fitting portion 10d. In the damper D configured in this way, when the valve body 13a is separated from the cylinder fitting portion 10d of the rod guide 10, all of the outlet ends of the ports 10f can be opened, so that when the damper D contracts, the liquid can be quickly supplied from the tank T into the extension chamber R1, and a situation where the liquid is insufficient in the extension chamber R1 is not caused.

[0096] Furthermore, the damper D of the present embodiment includes a collar 14 that fits on the outer periphery of the rod guide 10 and faces the tank T. The collar 14 may have a notch 14a facing downward of the tank T, a passage 14b that opens from the notch 14a and communicates with the inner periphery, and an annular passage that communicates the port 10f and the passage 14b may be provided between the collar 14 and the rod guide 10. According to the damper D configured in this way, even if a plurality of ports 10f are arranged around the rod 2 of the rod guide 10, only the liquid can be supplied to the extension chamber R1 while preventing the intrusion of gas from below the tank T, so it is optimal for use as a damper that is installed horizontally and attenuates the horizontal lateral vibration of the body of a railway vehicle.

[0097] Also, the damper D of the present embodiment includes a collar 141 that fits on the outer periphery of the rod guide 10 and faces the tank T, and a plurality of suction pipes 142 that are attached to the collar and whose tips face the center below the tank T. An annular passage that communicates with the inside of the suction pipe 142 and also communicates with the port 10f is provided between the rod guide 10 and the collar 141. According to the damper D configured in this way, since the tips of the suction pipes 142 are arranged near the center below the tank T, even if the damper D vibrates, only the liquid can be supplied to the extension chamber R1 while preventing the intrusion of gas from below the tank T, so it is optimal for use as a damper that is installed horizontally and attenuates the horizontal lateral vibration of the body of a railway vehicle.

[0098] Note that the extension-side damping valve EV and the compression-side damping valve CV are damping valves equipped with variable relief valves 61 and 64 capable of adjusting the damping force. However, when the damper D does not require damping force adjustment, they may be damping valves incapable of adjusting the damping force.

[0099] As described above, the preferred embodiments of the present invention have been described in detail. However, modifications, deformations, and changes are possible without departing from the scope of the claims.

Description of Reference Numerals

[0100] 1... cylinder, 1c... convex portion, 1d... extension-side concave portion, 1e... compression-side concave portion, 2... rod, 3... piston, 4... outer cylinder, 4a... first hole, 4b... second hole, 5... first cylinder, 5a... first boss portion, 5b... plane, 5d... end face, 6... second cylinder, 6a... second boss portion, 6b... plane, 6d... end face, 31... extension-side pipe, 33... compression-side pipe, 30... permanent magnet, CP... compression-side passage, CS... compression-side suction passage, CV... compression-side damping valve, D... damper, EP... extension-side passage, ES... extension-side suction passage, EV... extension-side damping valve, R1... extension-side chamber, R2... compression-side chamber, T... tank

Claims

1. A cylinder, a rod inserted axially movably into the cylinder, a piston inserted movably into the cylinder and connected to the rod to partition the inside of the cylinder into an extension chamber and a compression chamber, a first cylinder disposed on the outer peripheral side of the cylinder and forming an extension passage communicating with the extension chamber between the first cylinder and the cylinder, a second cylinder disposed on the outer peripheral side of the cylinder and forming a compression passage communicating with the compression chamber between the second cylinder and the cylinder, an outer cylinder disposed on the outer peripheral sides of the first cylinder and the second cylinder and forming a tank for storing a liquid between the outer cylinder and the first cylinder and the second cylinder, an extension suction passage allowing only the flow of the liquid from the tank toward the extension chamber, a compression suction passage allowing only the flow of the liquid from the tank toward the compression chamber, an extension damping valve applying resistance to the flow of the liquid from the extension chamber toward the tank through the extension passage, and a compression damping valve applying resistance to the flow of the liquid from the compression chamber toward the tank through the compression passage. A damper characterized by the above.

2. The cylinder has, an extension recess provided on the outer periphery and forming the extension passage between the extension recess and the first cylinder, a compression recess provided on the outer periphery and forming the compression passage between the compression recess and the second cylinder, and a convex portion protruding radially outward from between the extension recess and the compression recess and partitioning the extension recess and the compression recess. The damper according to claim 1, characterized by the above.

3. The outer cylinder has a first hole and a second hole communicating the inside and the outside, the first cylinder has a first boss portion whose inner periphery communicates with the extension passage facing the first hole, the second cylinder has a second boss portion whose inner periphery communicates with the compression passage facing the second hole, communicating an extension damping valve installed outside the outer cylinder through an extension pipe inserted into the first hole and the first boss portion with the extension passage, and communicating the extension damping valve with the tank through the outside of the extension pipe in the first hole, communicating a compression damping valve installed outside the outer cylinder through a compression pipe inserted into the second hole and the second boss portion with the compression passage, and communicating the compression damping valve with the tank through the outside of the compression pipe in the second hole. The damper according to claim 2, characterized by the above.

4. The first cylinder and the second cylinder abut against each other with their facing end portions, and have planes for circumferential alignment on the outer circumferences of their facing end portions. It is provided with permanent magnets attached to the planes. The damper according to any one of claims 1 to 3, characterized in that.

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