damper

Abstract

To provide a damper capable of generating stable damping force even when contraction operation is performed at high 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; an outer cylinder 4 which forms a tank T; an annular rod guide 10 which has a cylinder fitting portion 10d, an annular end portion 10d1 facing the extension-side chamber R1, and an outer cylinder fitting portion 10a fitting to an inner periphery of one end of the outer cylinder 4, and supporting the rod 2 inserted into the cylinder 1; and a check valve EC. The check valve EC includes: a plurality of ports 10f which is opened to the annular end 10d1 and communicates with the tank T; an annular valve element 13a which can separate from and approach the annular end portion 10d1 in an axial direction, and can open and close each of the ports 10f; and a spring 13c for energizing the valve element 13a toward the annular end portion 10d1. Only the flow of liquid from the tank T toward the extension-side chamber R1 is allowed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a damper.

Background Art

[0002] Conventionally, this type of damper is used for the purpose of suppressing vibrations of an installation target by being used for the installation target. As a damper, for example, there is known one that is 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 in a railway vehicle.

[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 partitions 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 valve case that closes the other end of the cylinder, a bottom cap that closes the other end of the outer tube, an extension - side damping valve provided on the piston to resist the flow of hydraulic oil from the extension - side chamber to the compression - side chamber, a compression - side damping valve provided on the valve case to resist the flow of hydraulic oil from the compression - side chamber to the tank, an extension - side check valve provided on the rod guide to allow only the flow of hydraulic oil from the tank to the extension - side chamber, and a compression - side check valve provided on the valve case to allow only the flow of hydraulic oil from the tank to the compression - side chamber (see, for example, Patent Document 1). And the extension - side check valve installed on the rod guide opens from the outer circumference of the annular rod guide and extends radially, and is accommodated in a valve hole that communicates with the middle of a passage that leads from the tank provided in the rod guide to the extension - side chamber.

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, when it exhibits a contraction operation, when the working oil moves from the compression chamber to the tank through the damping valve, the damping valve generates a damping force that resists the flow of the working oil and hinders the contraction operation, and the check valve on the extension side opens and the working oil is supplied from the tank to the extension chamber that expands due to the movement of the piston.

[0006] In this way, in a conventional damper, since the working oil is supplied to the extension chamber through the check valve on the extension side provided in the rod guide during the contraction operation, when the damper contracts at high speed, a large flow rate of the working oil flows through the check valve on the extension side. However, a check valve on the extension side is provided in the rod guide through which the rod is inserted on the inner circumference, and if the difference between the inner and outer diameters of the rod guide is increased, the rod diameter will be reduced and the strength will be insufficient, or the outer cylinder diameter will be increased and the mountability of the damper to railway vehicles etc. will deteriorate. Therefore, there is a limit to increasing the difference between the inner and outer diameters of the rod guide, so it is difficult to realize a check valve on the extension side that allows a large flow rate with the structure of the conventional check valve.

[0007] Therefore, in a conventional damper, it is difficult to increase the flow rate of the check valve on the extension side. When the damper exhibits a high-speed contraction operation, it has been pointed out that the check valve on the extension side becomes a resistance and it becomes difficult to supply the working oil from the tank to the extension chamber, and the pressure in the extension chamber may be reduced to below atmospheric pressure. There is a concern that bubbles will be generated in the working oil and a stable damping force cannot be generated, or external gas will be sucked into the cylinder.

[0008] Therefore, an object of the present invention is to provide a damper capable of generating a stable damping force even when contracting at high speed.

Means for Solving the Problems

[0009] To achieve the above object, the damper of the present invention includes a cylinder, a rod that is axially movably inserted into the cylinder, a piston that is movably inserted into the cylinder and is connected to the rod to partition the inside of the cylinder into an extension chamber and a compression chamber, an outer cylinder that covers the cylinder and forms a tank for storing liquid on the outer periphery of the cylinder, a cylinder fitting portion that fits on the inner periphery of one end of the cylinder, an annular end portion that faces the extension chamber of the cylinder fitting portion and surrounds the periphery of the rod, and an outer cylinder fitting portion that fits on the inner periphery of one end of the outer cylinder. It has an annular rod guide that supports the rod, and a check valve that allows only the flow of liquid from the tank to the extension chamber. The check valve includes a plurality of ports whose one ends open side by side along the circumferential direction on the annular end portion surrounding the rod of the rod guide and are respectively communicated with the tank, an annular valve body that can be moved closer and farther in the axial direction with respect to the annular end portion and can open and close each of the ports, and a spring that biases the valve body toward the annular end portion. 。

[0010] In the damper configured in this way, the check valve is provided with a plurality of ports that open side by side in the circumferential direction on the annular end portion surrounding the rod of the rod guide, and the open ends of the ports are opened and closed by an annular valve body that moves closer and farther from the annular end portion. Therefore, a plurality of ports can be efficiently arranged on a small rod guide to ensure a large total flow passage area of all the ports. Even if the flow rate of the liquid from the tank to the extension chamber is large, the movement of the liquid from the tank to the extension chamber can be allowed without giving too much resistance. Also, since the valve body is installed not in the rod guide but in the extension chamber and all the ports can be opened and closed by one valve body, it does not cause an increase in the size of the rod guide, a decrease in the outer diameter of the rod, or an increase in the inner diameter of the outer cylinder.

[0011] Further, the check valve in the damper includes an annular collar that is fitted on the outer periphery between the outer cylinder fitting portion and the cylinder fitting portion of the rod guide and is housed in the outer cylinder, and an annular passage formed along the circumferential direction between the rod guide and the collar. The other ends of each port communicate with the annular passage, and the collar may have a notch provided in a part of the outer periphery and a plurality of collar ports that open from the notch and communicate with the annular passage.

[0012] According to the damper configured in this way, even if a plurality of ports are arranged around the rod of the rod guide, the check valve can supply only the liquid to the extension chamber while preventing the entry of gas in the tank by arranging the color notch below the tank. Therefore, it is suitable for use in a horizontal installation to attenuate the horizontal vibration of the railway vehicle body.

[0013] Furthermore, the check valve in the damper includes an annular collar that is fitted on the outer periphery between the outer cylinder fitting portion and the cylinder fitting portion of the rod guide and is housed in the outer cylinder, and an annular passage formed along the circumferential direction between the rod guide and the collar. The other ends of the respective ports communicate with the annular passage, and the collar may have an internal passage that communicates with the annular passage through a plurality of suction pipes that are housed in the tank and have their proximal ends fitted to the collar.

[0014] According to the damper configured in this way, even if a plurality of ports are arranged around the rod of the rod guide, it is possible to supply only the liquid to the extension chamber while preventing the entry of gas in the tank by arranging the suction pipe fitted to the collar below the tank. Also, in the damper configured in this way, by arranging the tip of the suction pipe near the center of the lower part in the tank, it can be expected that the tip of the suction pipe will always be in the liquid even when the liquid level in the tank fluctuates due to vibration, effectively preventing gas from entering the extension chamber, and it is most suitable for use in a horizontal installation to attenuate the horizontal vibration of the railway vehicle body.

[0015] In addition, the rod guide in the damper has a cylindrical valve mounting portion that projects axially from the annular end portion, and an annular valve seat that surrounds the outer periphery of each port that opens to the outer peripheral side of the valve mounting portion. The valve body may be in sliding contact with the outer periphery of the valve mounting portion. In the damper configured in this way, since the valve body can approach and move away from the annular end portion without axial displacement with respect to the valve mounting portion, the valve body can be correctly opposed to the entire annular valve seat and can be seated and unseated. Therefore, even if a plurality of ports are opened at the annular end portion of the rod guide, all the ports can be stably closed simultaneously, and when the valve is opened, the valve body can quickly separate from the annular valve seat and does not give an excessive resistance to the flow of the liquid passing through the port.

[0016] Furthermore, the damper of the present invention includes a first cylinder that is disposed on the outer peripheral side of the cylinder and forms an extension passage that communicates with the extension chamber between the first cylinder and the cylinder, a second cylinder that is disposed on the outer peripheral side of the cylinder and forms a compression passage that communicates with the compression chamber between the second cylinder and the cylinder, an extension damping valve that gives resistance to the flow of the liquid from the extension chamber to the tank through the extension passage, a compression damping valve that gives resistance to the flow of the liquid from the compression chamber to the tank through the compression passage, and a valve case that fits between the other end of the cylinder and the second cylinder. The rod guide has a first cylinder fitting portion that fits into the first cylinder between the cylinder fitting portion and the outer cylinder fitting portion, and the first cylinder and the second cylinder may be sandwiched by the rod guide and the valve case.

[0017] According to the damper configured in this way, since the first cylinder and the second cylinder are sandwiched by the rod guide and the valve case, it is not necessary to join the first cylinder and the second cylinder by welding or screwing, the assemblability is improved, the processing cost can be reduced, and the first cylinder 5 and the second cylinder 6 can be fixed to the outer periphery of the cylinder without play by abutting the ends against each other and sandwiching them with the rod guide and the valve case.

Effect of the Invention

[0018] According to the damper of the present invention, a stable damping force can be generated even when the damper contracts at high speed.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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 movable in the axial direction, a piston 3 that is inserted into the cylinder 1 so as to be movable 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, an outer cylinder 4 that covers the cylinder 1 and forms a tank T for storing liquid on the outer periphery of the cylinder 1, an extension damping valve EV that gives resistance to the flow of liquid from the extension chamber R1 to the tank T, a compression damping valve CV that gives resistance to the flow of liquid from the compression chamber R2 to the tank T, a compression suction passage CS that allows only the flow of liquid from the tank T to the compression chamber R2, and an extension check valve EC. 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, in FIG. 1, the vertical direction is defined as the vertical direction of the damper D, the horizontal direction in FIG. 1 is defined as the horizontal direction of the damper D, and the direction penetrating the paper surface in FIG. 1 is defined 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 projects radially outward from the outer periphery of the left end in FIG. 1, an annular bottom-side flange 1b that projects radially outward from the outer periphery of the right end in FIG. 1, an annular convex portion 1c that projects radially outward from the outer periphery between the head-side flange 1a and the bottom-side flange 1b, an extension-side recess 1d formed by an annular recess between the outer periphery and the head-side flange 1a and the convex portion 1c, a compression-side recess 1e formed by an annular recess between the outer periphery and 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 and 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 in FIG. 1 of the cylinder 1 is closed by a valve case 9 fitted to the inner periphery of the right end. An annular rod guide 10 is fitted to the left end in FIG. 1 of the cylinder 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 arranged 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 arranged 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 accommodated 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 is provided with an annular first boss portion 5a attached by welding on its outer periphery. 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. When the first cylinder 5 is not provided, it is necessary to provide a 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 that penetrates the wall thickness of the second cylinder 6, and a continuous hole that penetrates 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, 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, so 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 in this way are fitted to the outer periphery of the cylinder 1, the end portions 5d, 6d facing each other are butted against each other. Then, with the flat surfaces 5b, 6b formed on the outer peripheries of the end portions 5d, 6d of the first cylinder 5 and the second cylinder 6 as a guide, when the first cylinder 5 and the second cylinder 6 are rotated and arranged so that the flat surfaces 5b, 6b are in 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] Also, when the end portions 5d and 6d of the first cylinder 5 and the second cylinder 6 are abutted against each other with the flat surfaces 5b and 6b facing each other, a flat surface flush with the flat surfaces 5b and 6b is formed. And a permanent magnet 40 is attached to the flat surface flush with the flat surfaces 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 flat surfaces 5b and 6b are used as marks for aligning the circumferential positions of the first cylinder 5 and the second cylinder 6 in this way, when the first cylinder 5 and the second cylinder 6 are abutted against each other to align the circumferential positions, a flat surface flush with the flat surfaces 5b and 6b for installing the permanent magnet 40 is formed by the flat surfaces 5b and 6b. Therefore, the permanent magnet 40 can be easily attached and the dropping off of the permanent magnet 40 can be prevented. Further, the above-mentioned flat surfaces 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, when the damper D is assembled, the permanent magnet 40 is in the liquid and is arranged below the tank T where contaminants accumulate, so that it becomes easy 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, and forms a tank T that covers the cylinder 1, the first cylinder 5 and the second cylinder 6 and stores liquid inside. The tank T is formed by an annular gap between the outer cylinder 4 and the first cylinder 5 and the second cylinder 6. In the tank T, in addition to the liquid, a gas is filled. The liquid is, for example, hydraulic oil, but may be a liquid other than hydraulic oil. The gas is, for example, an inert gas such as nitrogen, but may be air in addition to the inert gas. Although the first cylinder 5 and the second cylinder 6 are fitted on the outer periphery of the cylinder 1 and an extension side passage EP and a pressure side passage CP are provided between the cylinder 1, the first cylinder 5 and the second cylinder 6, a pipe line forming the extension side passage EP and the pressure side passage CP may be accommodated in the tank T instead of the first cylinder 5 and the second cylinder 6. In this case, the tank T may be formed by an annular gap between the cylinder 1 and the outer cylinder 4.

[0031] As shown in Fig. 3, the outer cylinder 4 is provided with a first hole 4a that faces the first boss portion 5a of the first cylinder 5 in the radial direction, and a second hole 4b that faces the second boss portion 6a of the second cylinder 6 in the radial direction. 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 arranged on the radially outer side of the first hole 4a in the outer cylinder 4 and the compression-side damping valve CV is arranged on the radially outer side of 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] Then, the first boss portion 5a of the first cylinder 5 described above is arranged at a position facing the first hole 4a of the outer cylinder 4 in the radial direction, and the second boss portion 6a of the second cylinder 6 is arranged at a position facing the second hole 4b of the outer cylinder 4 in the radial direction. Therefore, the flat surfaces 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 flat surfaces 5b and 6b with each other in the circumferential direction and the outer cylinder 4 is arranged 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 is 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 face 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 periphery at the left end in Fig. 1, which is one end 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 periphery 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 end 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 into 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 into 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 and a pressure chamber R2 filled with liquid. When the rod 2 and the piston 3 move axially inside the cylinder 1, the extension chamber R1 and the pressure chamber R2 expand and contract.

[0037] The valve case 9 is disk-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 continuous with the small-diameter portion 9a to the right in FIG. 1 and fits inside the second cylinder 6, a flange 9c provided on the outer periphery 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 accommodated a pressure-side check valve 15 including 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 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.

[0039] The bottom cap 16 is attached by welding to the right end in FIG. 1 of the outer cylinder 4, closes the right end in FIG. 1 of the outer cylinder 4, and in addition to having 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 communicates the recess 16a with the tank T, 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). Thus, 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 pressure-side chamber R2. Thus, the pressure-side suction passage CS is formed by the port 9e, the recess 16a, and the passage 16b.

[0041] The pressure-side check valve 15 opens the valve body 15a by compressing the coil spring 15c and moving it leftward in FIG. 1 within the recess 9d 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 valve body 15a of the pressure-side check valve 15 is pressed 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 close the port 9e and close the valve, thereby blocking 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 in a plurality on the same circumference, even if the flow rate of liquid from the tank T toward the pressure-side chamber R2 is large, the movement of liquid from the tank T to the pressure-side chamber R2 can be allowed 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 flow in the opposite direction.

[0042] Next, the rod guide 10 is annular. As shown in FIGS. 4 and 5, 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. 4 and has an outer diameter smaller than that of 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. 4 and has an outer diameter smaller than that of 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. 4 and has an outer diameter smaller than that of the first cylinder fitting portion 10c with the cylinder 1 fitted onto its outer circumference, an annular end portion 10d1 that faces the extension-side chamber R1 of the cylinder fitting portion 10d and surrounds the rod 3 at the right end in FIG. 1, an annular valve mounting portion 10e that projects from the inner circumference of the annular end portion 10d1, eight ports 10f that open from the outer circumference of the valve mounting portion 10e and lead to the outer circumference of the collar fitting portion 10b, and a return passage 10g that opens from the right end in FIG. 1 of the outer cylinder fitting portion 10a and leads to the left end.

[0043] Note that the eight ports 10f are arranged along the circumferential direction and open around the annular end portion 10d1 that surrounds the periphery of the rod 2 at the right end in FIG. 4 where one end faces the extending chamber R1 of the cylinder fitting portion 10d, and extend radially and open at equal intervals at the bottom of the annular passage 10b1 formed by an annular groove provided along the circumferential direction on the outer periphery of the collar fitting portion 10b. Since the annular passage 10b1 is provided on the entire outer circumference of the collar fitting portion 10b, it communicates with all of the eight ports 10f. Further, each port 10f communicates the extending chamber R1 and the tank T, respectively.

[0044] Also, on the inner circumference of the rod guide 10, a cylindrical bush 11 that slidably contacts the outer circumference of the rod 2 and guides the movement of the rod 2 in the axial direction to ensure smooth movement of the rod 2 is mounted, and a seal ring 12 that closely adheres to the outer circumference of the rod 2 is mounted.

[0045] Furthermore, an annular valve seat 10d2 that surrounds the outer circumference of each port 10f is provided with respect to the annular end portion 10d1 in the cylinder fitting portion 10d of the rod guide 10, and an annular inner circumferential seat portion 10d3 is provided on the inner circumference of each port 10f. An annular window 10d4, which is an annular recess communicating with one end of each port 10f, is provided between the annular valve seat 10d2 and the inner circumferential seat portion 10d3. Thus, the annular end portion 10d1 is an end portion facing the extending chamber R1 of the cylinder fitting portion 10d and includes the annular valve seat 10d2, the inner circumferential seat portion 10d3, and the annular window 10d4.

[0046] The valve mounting portion 10e is cylindrical and protrudes axially from the inside of the inner circumferential seat portion 10d3 on the inner circumferential side of each port 10f of the cylinder fitting portion 10d. Further, the valve mounting portion 10e includes a flange 10e1 that protrudes radially outward on the outer circumference at the right end in FIG. 4.

[0047] Further, as shown in FIGS. 3 and 4, the collar 14 fitted to the outer periphery of the color fitting portion 10b of the rod guide 10 is annular, and its outer diameter is smaller than the inner diameter of the outer cylinder 4. It is provided with a notch 14a provided in a part of the outer periphery, a plurality of collar ports 14b that open from the end face of the notch 14a and communicate with the inner periphery, and a pin insertion groove 14c provided at a position on the outer periphery that is circumferentially opposite to the notch 14a.

[0048] When the collar 14 is press-fitted and fitted to 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 collar port 14b of the collar 14 faces the annular passage 10b1 respectively. All of the collar ports 14b and all of the ports 10f communicate with each other through the annular passage 10b1. In the damper D of the present embodiment, the rod guide 10 is provided with an annular passage 10b1 that communicates the port 10f and the collar port 14b on the outer periphery of the color fitting portion 10b. However, an annular groove that forms an annular passage that communicates the port 10f and the collar port 14b may be provided on the inner periphery of the collar 14 instead of the outer periphery of the color fitting portion 10b.

[0049] Then, when the rod guide 10 with the collar 14 fitted to 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, 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. Further, the outer diameter of the color fitting portion 10b is smaller than the outer diameter of the first cylinder 5, the axial lengths of the collar 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 the collar 14, preventing the collar 14 from falling off the color fitting portion 10b.

[0050] 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 color port 14b that opens into the notch 14a of the collar 14 communicates with the tank T. Therefore, the inlet end of the port 10f in the rod guide 10 communicates with the tank T via the color port 14b, and the outlet end of the port 10f communicates with the extension chamber R1 in the cylinder 1.

[0051] Note that the color port 14b opens into the 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 color ports 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 surface 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. 4, the collar 14 is prevented from rotating in the circumferential direction with respect to the outer cylinder 4 and is positioned in the circumferential direction by inserting the pin 18 that penetrates 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 color port 14b is formed always faces downward of the damper D and faces the liquid, consideration is given so that the inlet end of the color port 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.

[0052] Also, in the present embodiment, the collar 14 is fitted to 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 color port 14b.

[0053] The check valve EC is configured to include a valve body 13a that uses the rod guide 10 as a valve seat member and opens and closes a port 10f provided in the rod guide 10, and a coil spring 13c as a spring that biases the valve body 13a. The valve body 13a and the coil spring 13c that constitute the check valve EC are attached to the outer periphery of the valve mounting portion 10e of the rod guide 10. More specifically, the valve body 13a is an annular plate that can separate from and seat on an annular valve seat 10d2 and an inner peripheral seat portion 10d3 provided at the annular end portion 10d1 at the right end in FIG. 1 of the cylinder fitting portion 10d to open and close the opening end of the port 10f. The valve body 13a has its inner periphery in sliding contact with the outer periphery of the valve mounting portion 10e, and can be displaced without axial displacement in the left-right direction in FIG. 1 of the outer periphery of the valve mounting portion 10e. When separated from the right end in FIG. 1 of the annular valve seat 10d2, each port 10f is opened at once, and when contacting the right end in FIG. 1 of the cylinder fitting portion 10d, each port 10f is blocked at once.

[0054] The conical coil spring 13c as a spring is fitted to the outer periphery of the valve mounting portion 10e and is interposed between a spring receiver 13b having an L-shaped cross section facing the valve body 13a in the axial direction and the valve body 13a to bias the valve body 13a toward the right end of the cylinder fitting portion 10d.

[0055] Note that the spring receiver 13b is in contact with a flange 10e1 provided on the outer periphery at the right end in FIG. 1 which is the tip of the valve mounting portion 10e, and is prevented from coming off the valve mounting portion 10e by a retaining ring 13d attached to the outer periphery of the valve mounting portion 10e.

[0056] The check valve EC configured as described above is installed in the extension suction passage ES formed by the port 10f, the annular passage 10b1, and the color port 14b, and opens and closes the port 10f. Then, with respect to the flow of liquid passing through the port 10f from the tank T toward the extension chamber R1, the valve body 13a compresses the coil spring 13c and moves to the tip side, which is the right side in FIG. 1, of the outer periphery of the valve mounting portion 10e of the rod guide 10 to open the valve, thereby opening the port 10f and allowing the flow of liquid moving from the tank T toward the extension chamber R1. Conversely, with respect to the flow of liquid 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, thus preventing the flow of liquid moving from the extension chamber R1 toward the tank T. The check valve EC is installed in the extension suction passage ES as described above, and sets the extension suction passage ES as a one-way passage that allows only the flow of liquid from the tank T toward the pressure chamber R2 and blocks the flow in the opposite direction.

[0057] The check valve EC includes a plurality of ports 10f that open circumferentially in an annular end portion 10d1 surrounding the rod 2 of the rod guide 10. Since the open ends of the ports 10f are opened and closed by an annular valve body 13a that is closer and farther from the annular end portion 10d1, a plurality of ports 10f can be efficiently arranged in the small rod guide 10 to ensure a large total flow passage area of all the ports 10f. Even if the flow rate of the liquid from the tank T to the extending side chamber R1 is large, the movement of the liquid from the tank T to the extending side chamber R1 can be allowed without giving too much resistance. Thus, when providing the extending side suction passage ES that communicates the extending 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 extending side chamber R1, and there is no shortage of liquid supply in the extending side chamber R1. Note that the spring in the check valve EC 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 in the extending side chamber R1 does not stagnate when the liquid of the maximum flow rate assumed to flow through the extending side suction passage ES in the environment where the damper D is actually used flows.

[0058] 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 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 the 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 slidably contact 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 gets over 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.

[0059] Note that, as described above, the collar 14 has the collar port 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 the collar 141 in FIG. 6.

[0060] As shown in Fig. 6, 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 provided on the inner circumference. It also has an internal passage 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 internal passage 141c, a pin insertion hole 141e that opens from the non-tank-side end, and a pin insertion groove 141f provided on the outer circumference at the upper end in Fig. 6. It is fitted on the outer circumference of the color fitting portion 10b of the rod guide 10. The base end of the suction pipe 142, whose tip is arranged near the center of the tank T, is fitted and attached to each of the insertion holes 141d of the Color 141.

[0061] As shown in Fig. 6, the rod guide 10 into which the Color 141 is fitted has a large diameter portion 10b2 where the color fitting portion 10b is fitted into the large inner diameter portion 141a of the Color 141 and a small diameter portion 10b3 that is fitted into the small inner diameter portion 141b according to the inner circumferential shape of the 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. Otherwise, it has substantially the same configuration as the rod guide 10 shown in Fig. 6.

[0062] 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 to prevent rotation. 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 adheres to the seal ring 143, and the small inner diameter portion 141b of the collar 141 fits into the small diameter portion 10b3 of the collar fitting portion 10b and adheres to 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 internal passage 141c formed on the inner circumference of the collar 141 and communicates 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 opens at a position surrounding the rod 2 of the rod guide 10 and extends radially to communicate with all of the eight ports 10f leading to the outer periphery of the collar fitting portion 10b, and can communicate with the internal passage 141c of the collar 141 and the five suction pipes 142. 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 collar port 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.

[0063] As described above, in the rod guide 10 with the collar 141 shown in FIG. 6 attached, the extension side suction passage ES is formed by the suction pipe 142, the internal passage 141c, the annular passage G, and the port 10f. Similar to the damper D shown in FIG. 1, a check valve EC is provided in the extension side suction passage ES. Therefore, when the liquid is insufficient in the extension side chamber R1, the check valve EC opens and the liquid is supplied from the tank T to the extension side chamber R1 through the extension side suction passage ES.

[0064] 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 within the liquid even if the liquid level in the tank T fluctuates, preventing gas from mixing into the extension chamber R1.

[0065] 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.

[0066] The adapter 31 includes a rectangular base plate 31a that abuts against the valve mounting 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 face on the side opposite to the outer cylinder and leads to the hole 23b while avoiding the stepped hole 31b. 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 to be bolted to the first pedestal 23.

[0067] 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. The extension-side pipe 32 is clamped between the stepped portion of the stepped hole 31b and the stepped portion 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.

[0068] The adapter 33 includes a rectangular base plate 33a that abuts against 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.

[0069] 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. The pressure-side pipe 34 is clamped between the stepped portion of the stepped hole 33b and the stepped portion 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.

[0070] In this 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.

[0071] The valve housing 60 is fixed to the adapter 31 by bolts (not shown) while being in contact with the counter first pedestal side surface of the base plate 31a of the adapter 31. Therefore, 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 communicated with the stepped hole 31b in the adapter 31 and the other end communicated 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 abolished, and a structure may be adopted in which the valve housing 60 holds the extension side pipe 32, 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.

[0072] 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 is communicated with the extension side chamber R1 through the extension side pipe 32, the extension side passage EP, and the through hole 1f, and is communicated with the tank T through the inclined hole 31c 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) in the first hole 4a. 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.

[0073] 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 energization amount. Also, when the solenoid 62 is not energized, it does not apply a thrust force to the valve body 61a.

[0074] Therefore, since the solenoid 62 can adjust the thrust force applied to the valve body 61a according to the energization amount, it can adjust the opening pressure of the variable relief valve 61 up and down. In the case of this embodiment, the variable relief valve 61 has the minimum opening pressure when the current amount supplied to the solenoid 62 is maximum, and the maximum opening pressure when no current is supplied to the solenoid 62. Therefore, the variable relief valve 61 can control the pressure of the upstream extension chamber R1 communicated through the extension passage EP by the energization amount to the solenoid 62.

[0075] 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 opening pressure of the variable relief valve 64.

[0076] 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. Therefore, 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 communicated with the stepped hole 33b in the adapter 33 and the other end communicated with the hole 33c. The variable relief valve 61 is provided in the valve housing 63 and 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. However, for example, the base plate 33a of the adapter 33 may be eliminated, 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 may be adopted in which the adapter 33 is integrally and inseparably provided with respect to the valve housing 63.

[0077] 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 is communicated with the pressure-side chamber R2 through the pressure-side pipe 34, the pressure-side passage CP, and the through hole 1g, and is communicated with the tank T through the hole 33c and inside the second hole 4b and 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.

[0078] 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.

[0079] 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 large or small. 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.

[0080] Damper D is configured as described above, and the operation of damper D will be described below. First, the operation when damper D extends will be described. When damper D extends, piston 3 moves to the left in FIG. 1 with respect to cylinder 1, so 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. Resistance is applied to such liquid movement by the variable relief valve 61, so 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, in the compression chamber R2 where the volume expands due to the movement of piston 3, there is a shortage of liquid, but this shortage of 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.

[0081] Thus, during the extension operation of damper D, the pressure in the extension chamber R1 acting on the extension chamber side surface of piston 3 becomes higher than the pressure in the compression chamber R2 acting on the compression chamber side surface of piston 3, and 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 damper D can be adjusted in height by the extension damping valve EV.

[0082] 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 compression chamber R2 is reduced and the extension chamber R1 is enlarged. Since the reduced compression chamber R2 communicates with the tank T through the compression passage CP and the compression damping valve CV, the liquid in the compression chamber R2 is discharged to the tank T through the compression passage CP and the compression damping valve CV. Since resistance is applied to such liquid movement by the variable relief valve 64, the pressure in the compression 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, there is a shortage of liquid, but this shortage of liquid is supplied to the extension chamber R1 from the tank T through the extension suction passage ES when the check valve EC opens. Therefore, the pressure in the extension chamber R1 becomes approximately equal to the pressure in the tank T.

[0083] In this way, during the contraction operation of the damper D, the pressure in the compression chamber R2 acting on the compression 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 compression 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 compression damping force generated during the contraction operation of the damper D can be adjusted in magnitude by the compression damping valve CV.

[0084] In this way, when the damper D extends, the extension damping valve EV applies 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 damping force. Therefore, the liquid column compression rigidity becomes high, and a sufficiently large damping force can be generated even when extending at an extremely low speed, without causing a shortage of damping force. Also, when the damper D contracts, the compression damping valve CV applies resistance to the flow of the liquid from the compression chamber R2 to the tank T, compresses only the liquid in the compression chamber R2, and generates a compression damping force. Therefore, a sufficiently large damping force can be generated even when extending at an extremely low speed, without causing a shortage of damping force.

[0085] 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 longer a 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 aspect, 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.

[0086] When the damper D contracts, as described above, the liquid is supplied from the tank T to the extension 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 chamber R1 during the contraction of the damper D increases.

[0087] 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.

[0088] 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 contracts at a high speed in order to further increase the compression-side damping force when the damper D contracts in the extremely low speed range, 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 chamber R1.

[0089] 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 inserted into the cylinder 1 movably and connected to the rod 2 to partition the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, an outer cylinder 4 covering the cylinder 1 to form a tank T for storing a liquid on the outer periphery of the cylinder 1, a cylinder fitting portion 10d fitted to the inner periphery of one end of the cylinder 1, an annular end portion 10d1 facing the extension chamber R1 of the cylinder fitting portion 10d and surrounding the periphery of the rod 2, and an outer cylinder fitting portion 10a fitted to the inner periphery of one end of the outer cylinder 4. The damper D further includes an annular rod guide 10 for supporting the rod 2 and a check valve EC that allows only the flow of the liquid from the tank T toward the extension chamber R1. The check valve EC includes a plurality of ports 10f having one end opened along the circumferential direction in the annular end portion 10d and communicating with the tank T respectively, an annular valve body 13a that can be moved closer to or farther from the annular end portion 10d1 in the axial direction and can open and close each of the ports 10f, and a coil spring (spring) 13c that biases the valve body 13a toward the annular end portion 10d1.

[0090] The damper D configured as described above includes a plurality of ports 10f that open circumferentially in an annular end portion 10d1 where the check valve EC surrounds the rod 2 of the rod guide 10. Since the open ends of the ports 10f are opened and closed by an annular valve body 13a that is closer and farther from the annular end portion 10d1, a plurality of ports 10f can be efficiently arranged in the small rod guide 10 to ensure a large total flow passage area of all the ports 10f. Even if the flow rate of the liquid from the tank T to the extending chamber R1 is large, the movement of the liquid from the tank T to the extending chamber R1 can be allowed without giving too much resistance. Therefore, when providing the extending suction passage ES that communicates the extending 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. Thus, a large flow rate of liquid can be supplied from the tank T to the extending chamber R1, and there will be no shortage of liquid supply in the extending chamber R1. Further, since the valve body 13a is installed not in the rod guide 10 but in the extending chamber R1 and all the ports 10f can be opened and closed by one valve body 13a, it does not cause an increase in the size of the rod guide 10, a decrease in the outer diameter of the rod, or an increase in the inner diameter of the outer cylinder. From the above, according to the damper D of the present embodiment, even if the check valve EC is provided in the rod guide 10, a large flow rate can be allowed to pass through. Thus, there will be no shortage of liquid supply in the extending chamber R1, the generation of bubbles in the cylinder 1 is suppressed, and a stable damping force can be generated. Furthermore, according to the damper D of the present embodiment, since it does not cause an increase in the size of the check valve EC, the mountability is not impaired.

[0091] Furthermore, in the damper D of the present embodiment, a check valve EC is fitted to the outer periphery between the outer cylinder fitting portion 10a and the cylinder fitting portion 10d of the rod guide 10 and is accommodated in the outer cylinder 4. The damper D includes an annular collar 14 and an annular passage 10b1 formed along the circumferential direction between the rod guide 10 and the collar 14. The other ends of the respective ports 10f communicate with the annular passage 10b1. The collar 14 includes a notch 14a provided in a part of the outer periphery and a plurality of collar ports 14b that open from the notch 14a and communicate with the annular passage 10b1. 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, the check valve EC can prevent the entry of gas in the tank T by arranging the notch 14a of the collar 14 below the tank T and supply only the liquid to the extension chamber R1. Therefore, it is suitable for use in a horizontal installation for damping the horizontal lateral vibration of the car body of a railway vehicle.

[0092] Also, the damper D of the present embodiment includes an annular collar 141 fitted to the outer periphery between the outer cylinder fitting portion 10a and the cylinder fitting portion 10d of the rod guide 10 and accommodated in the outer cylinder 4, and an annular passage G formed along the circumferential direction between the rod guide 10 and the collar 141. The other ends of the respective ports 10f communicate with the annular passage G. The collar 141 includes an internal passage 141c that is accommodated in the tank T and communicates with the annular passage G through a plurality of suction pipes 142 whose proximal ends are fitted to the collar 141. 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, the check valve EC can prevent the entry of gas in the tank T by arranging the suction pipes 142 provided in the collar 141 below the tank T and supply only the liquid to the extension chamber R1. Further, in the damper D of the present embodiment, since the tip of the suction pipe 142 is arranged near the center of the lower part in the tank T, it can be expected that the tip of the suction pipe 142 will always be in the liquid even if the damper D vibrates and the liquid level in the tank T fluctuates. Thus, it can effectively prevent the entry of gas into the extension chamber R1 and is most suitable for use in a horizontal installation for damping the horizontal lateral vibration of the car body of a railway vehicle.

[0093] Furthermore, in the damper D of the present embodiment, the rod guide 10 has a cylindrical valve mounting portion 10e that protrudes axially from the annular end portion 10d1, and an annular valve seat 10d2 that surrounds the outer periphery of each port 10f that opens to the outer peripheral side of the valve mounting portion 10e. The valve body 13a is in sliding contact with the outer periphery of the valve mounting portion 10e. In the damper D configured in this way, the valve body 13a can approach and move away from the annular end portion 10d1 without axial displacement with respect to the valve mounting portion 10e. Therefore, the valve body 13a can be seated and unseated facing the entire annular valve seat 10d2. Even if a plurality of ports 10f are opened in the annular end portion 10d1 of the rod guide 10, all the ports 10f can be stably closed simultaneously, and when the valve is opened, it can quickly separate from the annular valve seat 10d2 without giving unnecessary resistance to the flow of the liquid passing through the port 10f.

[0094] Also, the damper D of the present embodiment includes a first cylinder 5 disposed on the outer peripheral side of the cylinder 1 and forming an extension side passage EP that communicates with the extension side 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 side passage CP that communicates with the compression side chamber R2 between the second cylinder 6 and the cylinder 1, an extension side damping valve EV that provides resistance to the flow of the liquid from the extension side chamber R1 to the tank T via the extension side passage EP, a compression side damping valve CV that provides resistance to the flow of the liquid from the compression side chamber R2 to the tank T via the compression side passage CP, and a valve case 9 that fits between the other end of the cylinder 1 and the second cylinder 6. The rod guide 10 includes a first cylinder fitting portion 10c that fits into the first cylinder 5 between the cylinder fitting portion 10d and the outer cylinder fitting portion 10a. The first cylinder 5 and the second cylinder 6 are sandwiched between the rod guide 10 and the valve case 9. According to the damper D configured in this way, since the first cylinder 5 and the second cylinder 6 are sandwiched between the rod guide 10 and the valve case 9, it is not necessary to connect the first cylinder 5 and the second cylinder 6 by welding or screwing, so the assemblability is improved, the processing cost can be reduced, and the ends 5d, 6d can be fixed without play on the outer periphery of the cylinder 1 by being abutted against each other and sandwiched between the rod guide 10 and the valve case 9.

[0095] 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 described above, it is advantageous in that the end portions 5d and 6d are brought into contact with each other and clamped between the rod guide 10 and the valve case 9 so that they can be fixed to the outer periphery of the cylinder 1 without play.

[0096] Also, according to the damper D of the present embodiment, since it is provided with a check valve EC and the check valve EC can allow a large flow rate even during a rapid contraction operation, a shortage of liquid supply in the extension chamber R1 is prevented, the generation of bubbles in the cylinder 1 is suppressed, and a stable damping force can be generated.

[0097] Moreover, according to 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, thereby increasing the liquid column compression rigidity. Therefore, according to the damper D of the present embodiment, since the liquid column compression rigidity during the extension operation can be increased, a damping force can be generated without shortage even when the extension operation is performed at an extremely low speed.

[0098] Furthermore, according to the damper D of the present embodiment, the extension passage EP and the compression passage CP are formed by a first cylinder 5 and a second cylinder 6 disposed on the outer periphery of the cylinder 1, respectively, 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 compression 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 pipe length connecting the two, and the outlet of the compression passage CP and the compression damping valve CV can be arranged in close proximity to shorten the pipe length (the total length of the extension pipe 32 and the total length of the compression pipe 34) connecting the two.

[0099] 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 compression 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 compression passage CP and the compression damping valve CV can be arranged in close proximity. From the above, since the pipe length can be shortened even if the installation positions of the extension damping valve EV and the compression damping valve CV with respect to the outer cylinder 4 are changed, the ratio of reducing the volume in the tank T by the pipe can also be reduced, and the diameter of the outer cylinder 4 does not become significantly 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 compression 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.

[0100] Also, in the damper D of the present embodiment, the cylinder 1 has 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 of forming the extension-side passage EP and the compression-side passage CP by forming recesses on the inner circumferences of the first cylinder 5 and the second cylinder 6, the processing is easier and the processing cost can be reduced.

[0101] 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, by providing the cylinder 1 with the head-side flange 1a and the bottom-side flange 1b, there is an advantage that play is less likely to occur between the cylinder 1 and the first cylinder 5 and the second cylinder 6.

[0102] 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 outside. The first cylinder 5 has an annular first boss portion 5a whose inner circumference communicates with the extension-side passage EP facing the first hole 4a. The second cylinder 6 has an annular second boss portion 6a whose inner circumference communicates with the compression-side passage CP facing the second hole 4b. 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 within 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 within the second hole 4b.

[0103] According to the damper D configured as described above, 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, 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. Therefore, 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 secured 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.

[0104] Moreover, in the damper D of the present embodiment, the first cylinder 5 and the second cylinder 6 abut against each other at the end portions 5d, 6d facing each other, and have flat surfaces 5b, 6b for circumferential alignment on the outer peripheries of the end portions 5d, 6d facing each other, and are provided with permanent magnets 40 attached to the flat surfaces 5b, 6b. According to the damper D configured as described above, since the permanent magnets 40 are installed on the flat surfaces 5b, 6b provided on the outer peripheries 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, the liquid can be purified, and the biting-in 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 can be suppressed. Also, since the permanent magnets 40 are attached to the flat surfaces 5b, 6b that serve as marks for circumferential alignment between the first cylinder 5 and the second cylinder 6, there is no concern about the permanent magnets 40 falling off from the first cylinder 5 and the second cylinder 6, and since the operator visually recognizes the position of the flat surfaces 5b, 6b when attaching the permanent magnets 40, the first cylinder 5 and the second cylinder 6 can be accurately arranged at appropriate positions.

[0105] Note that the extension-side damping valve EV and the compression-side damping valve CV are damping valves provided with variable relief valves 61 and 64 for 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.

[0106] 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.

Explanation of Reference Numerals

[0107] 1... cylinder, 2... rod, 3... piston, 4... outer cylinder, 10... rod guide, 10a... outer cylinder fitting portion, 10b1, G... annular passage, 10d... cylinder fitting portion, 10d1... annular end portion, 10d2... annular valve seat, 10e... valve mounting portion, 13a... valve body, 13c... spring, 14, 141... collar, 14a... notch, 14b... collar port, 141c... internal passage, 142... suction pipe, CS... compression-side suction passage, CV... compression-side damping valve, D... damper, EC... check valve, 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, an outer cylinder covering the cylinder and forming a tank for storing liquid on the outer periphery of the cylinder, a cylinder fitting portion fitted to the inner periphery of one end of the cylinder, an annular end portion facing the extension chamber of the cylinder fitting portion and surrounding the periphery of the rod, and an outer cylinder fitting portion fitted to the inner periphery of one end of the outer cylinder, and having an annular rod guide for supporting the rod, a check valve provided in the rod guide and allowing only the flow of liquid from the tank toward the extension chamber, The check valve, a plurality of ports having one ends opened side by side along the circumferential direction to the annular end portion and each communicating with the tank, an annular valve body axially movable relative to the annular end portion and capable of opening and closing each of the ports, a spring for biasing the valve body toward the annular end portion A damper characterized by the above.

2. The check valve, an annular collar fitted to the outer periphery between the outer cylinder fitting portion and the cylinder fitting portion of the rod guide and housed in the outer cylinder, an annular passage formed along the circumferential direction between the rod guide and the collar, the other ends of the respective ports each communicating with the annular passage, The collar having a notch provided in a part of the outer periphery and a plurality of collar ports opened from the notch and communicating with the annular passage The damper according to claim 1, characterized by the above.

3. The check valve, an annular collar fitted to the outer periphery between the outer cylinder fitting portion and the cylinder fitting portion of the rod guide and housed in the outer cylinder, an annular passage formed along the circumferential direction between the rod guide and the collar, the other ends of the respective ports each communicating with the annular passage, The collar having an internal passage communicating with the annular passage through a plurality of suction pipes housed in the tank and having proximal ends fitted to the collar The damper according to claim 1, characterized by the above.

4. The rod guide has a cylindrical valve mounting portion protruding axially from the annular end portion and an annular valve seat surrounding the outer periphery of each of the ports opening to the outer peripheral side of the valve mounting portion, The valve body is in sliding contact with the outer periphery of the valve mounting portion The damper according to claim 1, characterized in that...

5. A first cylinder disposed on the outer peripheral side of the cylinder and forming an extension side passage communicating with the extension side chamber between the first cylinder and the cylinder; A second cylinder disposed on the outer peripheral side of the cylinder and forming a compression side passage communicating with the compression side chamber between the second cylinder and the cylinder; An extension side damping valve that provides resistance to the flow of liquid from the extension side chamber to the tank through the extension side passage; A compression side damping valve that provides resistance to the flow of liquid from the compression side chamber to the tank through the compression side passage; A valve case fitted to the other end of the cylinder and the second cylinder; The rod guide has a first cylinder fitting portion that fits into the first cylinder between the cylinder fitting portion and the outer cylinder fitting portion; The first cylinder and the second cylinder are sandwiched by the rod guide and the valve case; The damper according to any one of claims 1 to 4, characterized in that...

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