Damper

Abstract

To provide a damper which can reduce a manufacturing cost even with an annular passage provided therein.SOLUTION: A damper D of the present invention includes: a cylinder 1; a piston rod 2 axially movably inserted into the cylinder 1; a piston 3 connected to the piston rod 2 and partitioning the cylinder 1 into an extension-side chamber R1 and a compression-side chamber R2; a cap 10 having a bottomed-cylindrical small inner-diameter part (insertion part) 10a2 in which the other end of the cylinder 1 is inserted on an inner periphery of the cylinder part 10a and that closes the other end of the cylinder 1; an outer tube 4 having an annular passage C that communicates with the extension-side chamber R1 between the cylinder 1 and itself while covering an outer peripheral side of the cylinder 1, the outer tube being screwed to a tip end side on the inner periphery of the cylinder part 10a of the cap 10 from the small inner-diameter part (insertion part) 10a2; and a stopper S provided to prevent a falling-off of the cylinder 1 from the cap 10 by being attached to the outer tube 4 and facing one end of the cylinder 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a shock absorber.

Background Art

[0002] A shock absorber is used, for example, interposed between the vehicle body and wheels of a saddle-riding type vehicle, and suppresses vibrations of the vehicle body and wheels with the damping force generated during expansion and contraction.

[0003] Such a shock absorber includes, for example, a cylinder, a piston movably inserted into the cylinder and partitioning the inside of the cylinder into an extension chamber and a compression chamber filled with hydraulic oil, a piston rod movably inserted into the cylinder and connected to the piston, a tank for storing hydraulic oil, a hard-side damping element provided on the piston for communicating the extension chamber and the compression chamber and giving resistance to the flow of the hydraulic oil passing therethrough, a bypass passage bypassing the bird-side damping element and communicating the extension chamber and the compression chamber, and a soft-side damping element provided in series with a solenoid valve in the bypass passage (see, for example, Patent Document 1).

[0004] In the shock absorber configured as described above, by adjusting the opening area of the bypass passage with a solenoid valve, the distribution ratio of the flow rate of the hydraulic oil passing through the hard-side damping element and the soft-side damping element is adjusted, and a wide damping force adjustment range is obtained to output an optimal damping force for suppressing vibrations of the vehicle.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a conventional shock absorber, the outer periphery of the cylinder is covered with an outer tube, and the outer periphery of the cylinder is cut or ground to form an annular groove between the upper end and the lower end of the cylinder, and an annular passage communicating with the extension chamber is formed between the outer tube and the cylinder by the annular groove. A bypass passage is formed by an external passage where a solenoid valve and a soft-side damping element are installed and the annular passage.

[0007] Further, the external passage is provided in a cap screwed to the outer periphery of the outer tube, and a flange provided on the outer periphery of the lower end of the cylinder is sandwiched between the end of the outer tube and the bottom of the cap, so that the cylinder and the outer tube are fixed to the cap.

[0008] In this way, in the conventional shock absorber, in order to form the bypass passage, groove processing for forming an annular groove on the outer periphery of the cylinder is required, and there is a problem that the manufacturing cost increases.

[0009] Therefore, an object of the present invention is to provide a shock absorber capable of reducing the manufacturing cost even if it has an annular passage inside.

Means for Solving the Problems

[0010] To solve the above problems, the shock absorber of the present invention includes a cylinder, a piston rod inserted axially movably into the cylinder and protruding outward from one end of the cylinder, and a piston connected to the piston rod and inserted axially movably into the cylinder and partitioning the inside of the cylinder into an extension chamber and a compression chamber. A cap having a bottomed cylindrical shape and having an insertion portion into which the other end of the cylinder is inserted on the inner periphery of the cylindrical portion to close the other end of the cylinder, and an outer tube that covers the outer peripheral side of the cylinder and forms an annular passage communicating with the extension chamber between the outer tube and the cylinder and is screwed on the inner periphery of the cylindrical portion of the cap on the tip side rather than the fitting portion. And a stopper attached to the outer tube and facing one end of the cylinder to prevent the cylinder from falling off the cap.

[0011] According to the buffer configured as described above, since the other end of the cylinder is inserted into the cylindrical portion of the cap, the outer tube is screwed to the cylindrical portion of the cap, and the outer tube is provided with a stopper that faces one end of the cylinder and prevents the cylinder from falling off the cap, it is not necessary to adopt a structure in which a flange is provided at the other end of the cylinder and the flange is sandwiched between the outer tube and the cap. Therefore, it is not necessary to perform grooving to form an annular groove on the outer periphery of the cylinder.

[0012] In addition, the cap in the buffer has a first stepped portion that abuts against the end of the outer tube on the inner periphery of the cylindrical portion, and the cylinder may be press-fitted into the insertion portion of the cap.

[0013] According to the buffer configured as described above, since the end of the outer tube can abut against the first stepped portion, an axial force can be applied to the outer tube to firmly fix the outer tube to the cap. At the same time, since the cylinder is press-fitted into the insertion portion of the cap, it is possible to prevent the annular passage from communicating with the pressure side chamber through the space between the cylinder and the cap, eliminating the need to install a sealing member between the cylinder and the cap and further reducing the manufacturing cost.

[0014] Furthermore, the cap in the buffer has a second stepped portion that abuts against the other end of the cylinder on the inner periphery of the cylindrical portion, and the cylinder is clamped by the second stepped portion and the stopper. According to the buffer configured as described above, the cylinder can be firmly fixed by sandwiching it between the outer tube and the cap. At the same time, since the cylinder is in close contact with the second stepped portion of the cap, it is possible to prevent the annular passage from communicating with the pressure side chamber through the space between the cylinder and the cap, eliminating the need to install a sealing member between the cylinder and the cap and further reducing the manufacturing cost.

[0015] In addition, the stopper in the shock absorber may include a snap ring mounted on the inner circumference of the outer tube, a cylindrical fitting portion that fits onto the inner circumference of the outer tube and also fits onto the outer circumference of one end of the cylinder, and a collar having an opposing portion provided on the inner circumference of the fitting portion and facing one end of the cylinder. According to the shock absorber configured in this way, the collar that fits onto the inner circumference of the outer tube can center one end of the cylinder concentrically with respect to the outer tube. The use of the snap ring facilitates the fixing of the collar and also makes the inner circumference machining of the outer tube inexpensive.

[0016] Furthermore, the shock absorber includes a main damping passage that provides resistance to the flow of liquid traveling between the extension side chamber and the compression side chamber, a bypass passage that bypasses the main damping passage and connects the extension side chamber and the compression side chamber, and a variable damping valve that provides resistance to the flow of liquid passing through the bypass passage. The cap has a first port that opens on the bottom side rather than the tip of the outer tube of the cylindrical portion and communicates with the annular passage, and a second port that opens on the bottom side rather than the cylinder and communicates with the compression side chamber. The bypass passage may be formed by an external passage that connects the first port and the second port and is provided with a variable damping valve, and the annular passage.

[0017] According to the shock absorber configured in this way, the variable damping valve provided in the bypass passage enables adjustment of the damping characteristics. Even when the cylinder is inserted into the cylindrical portion of the cap and the outer tube is screwed together, the external passage that constitutes the bypass passage is not blocked by the cylinder and the outer tube, and it is not necessary to provide holes in the cylinder and the outer tube to ensure communication of the bypass passage and the external passage. Therefore, the manufacturing cost is further reduced and the assemblability is also improved.

Advantages of the Invention

[0018] According to the shock absorber of the present invention, even if it has an annular passage inside, the manufacturing cost can be reduced.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIG. 1, a shock absorber D in one embodiment includes a cylinder 1, a piston rod 2 that is inserted into the cylinder 1 so as to be movable in the axial direction and protrudes outward from the upper end in FIG. 1 which is one end of the cylinder 1, a piston 3 that is connected to the piston rod 2 and is inserted into the cylinder 1 so as to be movable in the axial direction and partitions the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, a cap 10 that is bottomed cylindrical and closes the lower end in FIG. 1 which is the other end of the cylinder 1, an outer tube 4 that covers the outer peripheral side of the cylinder 1 and forms an annular passage C between the outer tube 4 and the cylinder 1 and is screwed to the cap 10, and a stopper S that is attached to the outer tube 4 and faces the upper end of the cylinder 1 to prevent the cylinder 1 from falling off the cap 10.

[0021] And although not shown in the figure, this shock absorber D is interposed between the vehicle body and the rear wheel in a saddle-type vehicle such as a motorcycle and is used to suppress the vibrations of the vehicle body and the rear wheel. Note that the shock absorber D may be used to suppress vibrations other than those in saddle-type vehicles.

[0022] The following will describe each part of the shock absorber D in detail. As shown in FIG. 1, the cylinder 1 is cylindrical, and the lower end in FIG. 1, which is the other end, is closed by the cap 10. Further, a through-hole 1a that communicates the inside and outside of the cylinder 1 is provided on the side portion near the upper end in FIG. 1, which is one end of the cylinder 1. Inside the cylinder 1, a piston rod 2 is inserted so as to be movable in the axial direction, and the upper end in FIG. 1, which is the tip of the piston rod 2, protrudes outward from the upper end in FIG. 1 of the cylinder 1.

[0023] The piston rod 2 is provided with a small-diameter portion 2a at the lower end in FIG. 1, the outer diameter of which is smaller than that of the upper part, and a piston 3 is mounted on the outer periphery. Further, a bracket 6 that can be connected to the vehicle body in a saddle-type vehicle is mounted on the upper end in FIG. 1 of the piston rod 2.

[0024] Inside the cylinder 1, a piston 3 attached to the piston rod 2 is inserted so as to be movable in the axial direction, and the inside of the cylinder 1 is partitioned by the piston 3 into an extension chamber R1 above the piston 3 and a compression chamber R2 below the piston 3. The extension chamber R1 and the compression chamber R2 are filled with a liquid such as hydraulic oil. Note that the liquid is hydraulic oil in the present embodiment, but it may be a liquid such as water or an aqueous solution other than hydraulic oil.

[0025] Subsequently, the piston 3 is annular and is mounted on the outer periphery of the small-diameter portion 2a of the piston rod 2, and is provided with an extension port 3a and a compression port 3b that communicate the extension chamber R1 and the compression chamber R2 in parallel. An extension main damping valve 13 that is annular and mounted on the outer periphery of the small-diameter portion 2a and opens and closes the extension port 3a is laminated on the lower end in FIG. 1 of the piston 3. Further, a compression main damping valve 14 that is annular and mounted on the outer periphery of the small-diameter portion 2a and opens and closes the compression port 3b is laminated on the upper end in FIG. 1 of the piston 3. The piston 3, the extension main damping valve 13, and the compression main damping valve 14 are fitted on the outer periphery of the small-diameter portion 2a of the piston rod 2 and are fixed to the piston rod 2 by a piston nut 15 screwed to the lower end of the small-diameter portion 2a.

[0026] In the shock absorber D of the present embodiment, the extension-side main damping valve 13 is configured by laminating a plurality of annular plates at the lower end of the piston 3 in FIG. 1. The inner peripheral side is fixed, and when the outer peripheral side is deflected by the pressure in the extension-side chamber R1, it is a laminated leaf valve that opens the extension port 3a. The extension-side main damping valve 13 can open and close the extension port 3a. When the shock absorber D extends, it opens the valve and provides resistance to the flow of the liquid passing from the extension-side chamber R1 to the compression-side chamber R2 through the extension port 3a. When the shock absorber D contracts, it closes the valve and blocks the extension port 3a. Note that the extension-side main damping valve 13 may be any damping valve that can provide resistance to the flow of the liquid from the extension-side chamber R1 to the compression-side chamber R2 and exert a damping force that hinders the extension of the shock absorber D during the extension of the shock absorber D. Therefore, it may be a damping valve other than the laminated leaf valve.

[0027] On the other hand, in the shock absorber D of the present embodiment, the compression-side main damping valve 14 is configured by laminating a plurality of annular plates at the upper end of the piston 3 in FIG. 1. The inner peripheral side is fixed, and when the outer peripheral side is deflected by the pressure in the compression-side chamber R2, it is a laminated leaf valve that opens the compression port 3b. The compression-side main damping valve 14 can open and close the compression port 3b. When the shock absorber D contracts, it opens the valve and provides resistance to the flow of the liquid passing from the compression-side chamber R2 to the extension-side chamber R1 through the compression port 3b. When the shock absorber D extends, it closes the valve and blocks the compression port 3b. Note that the compression-side main damping valve 14 may be any damping valve that can provide resistance to the flow of the liquid from the compression-side chamber R2 to the extension-side chamber R1 and exert a damping force that hinders the contraction of the shock absorber D during the contraction of the shock absorber D. Therefore, it may be a damping valve other than the laminated leaf valve. Also, although not shown, an orifice is provided in parallel with the extension-side main damping valve 13 and the compression-side main damping valve 14. The orifice is formed, for example, by a notch provided in the annular plate constituting the extension-side main damping valve 13 and the compression-side main damping valve 14, or by an indentation provided in the valve seat of the piston 3 where the annular plate seats and disengages.

[0028] In this way, the extension port 3a and the compression port 3b in the piston 3 communicate the extension chamber R1 and the compression chamber R2. Further, with respect to the flow of the liquid that travels between the extension chamber R1 and the compression chamber R2 through the extension port 3a and the compression port 3b, when the extension main damping valve 13 and the compression main damping valve are closed, resistance is applied by the orifice, and when the extension main damping valve 13 and the compression main damping valve are open, the extension main damping valve 13 applies resistance to the flow of the liquid passing through the extension port 3a, and the compression main damping valve 14 applies resistance to the flow of the liquid passing through the compression port 3b. In the present embodiment, these extension port 3a, compression port 3b, orifice, extension main damping valve 13, and compression main damping valve 14 constitute a main damping passage M that applies resistance to the flow of the liquid moving between the extension chamber R1 and the compression chamber R2. Note that the main damping passage M may be configured with only a single passage and a bidirectional valve such as an orifice or a choke provided in the passage that applies resistance to the flow of the liquid reciprocating between the extension chamber R1 and the compression chamber R2.

[0029] As shown in FIG. 1, the outer tube 4 is cylindrical and covers the outer periphery of the cylinder 1, and forms an annular passage C by the annular gap therebetween. The outer tube 4 includes a screw portion 4a slightly upward from the lower end of the outer periphery, and also includes an annular groove 4b provided in the inner periphery near the upper end and an annular groove 4c provided in the inner periphery at a position spaced downward from the annular groove 4b. Further, the lower end of the outer tube 4 in FIG. 1 is closed by a cap 10 that is screwed using the screw portion 4a on the outer periphery.

[0030] Furthermore, inside the outer tube 4, a stopper S is provided, which is composed of an annular collar 11 and a snap ring 12 attached to the annular groove 4c to prevent the collar 11 from coming off upward in FIG. 1.

[0031] Color 11 includes a cylindrical fitting portion 11a that fits onto the inner circumference of the outer tube 4 and also fits onto the outer circumference of the upper end in FIG. 1 which is one end of the cylinder 1, and an opposing portion 11b provided on the inner circumference of the fitting portion 11a and opposing the upper end of the cylinder 1. The upward movement in FIG. 1 is restricted by the snap ring 12. Since the upward movement in FIG. 1 of the color 11 with respect to the outer tube 4 is restricted by the snap ring 12 that fixes the color 11 to the inner circumference of the outer tube 4, the stopper S composed of the color 11 and the snap ring 12 restricts the upward movement of the cylinder 1 in FIG. 1 and prevents it from coming off the cap 10. Also, the color 11 positions the cylinder 1 concentrically in the radial direction with respect to the outer tube 4 and closes the upper end in FIG. 1 of the annular passage C between the cylinder 1 and the outer tube 4.

[0032] Also, a snap ring 16 is attached to the annular groove 4b on the upper end side of the outer tube 4. This snap ring 16 abuts against the outer circumference of the upper end in FIG. 1 of the rod guide 17 that fits onto the inner circumference of the upper end of the outer tube 4, and restricts the upward movement of the rod guide 17 from the outer tube 4 in FIG. 1.

[0033] The rod guide 17 is annular and includes an annular seal member 17a that slidably contacts the outer circumference of the piston rod 2 on the inner circumference and an annular bush 17b. The seal member 17a seals the outer circumference of the piston rod 2 to seal the inside of the cylinder 1, and the bush 17b guides the axial movement of the piston rod 2.

[0034] Note that a gap is provided between the lower end in FIG. 1 of the rod guide 17 and the snap ring 12 in the stopper S, so that when disassembling the shock absorber D, the rod guide 17 can be pushed into the gap side to remove the snap ring 16 that restricts the upward movement of the rod guide 17 in FIG. 1.

[0035] The cap 10 is formed in a bottomed cylindrical shape having a cylindrical portion 10a and a bottom portion 10b that closes the lower end of the cylindrical portion 10a. The lower end of the cylinder 1 is inserted into the cylindrical portion 10a, and the cylindrical portion 10a is screwed to the outer periphery of the outer tube 4.

[0036] More specifically, as shown in FIG. 2, the inner diameter of the cylindrical portion 10a increases in four steps from the bottom portion 10b side toward the tip. The minimum inner diameter portion 10a1 with the smallest inner diameter at the deepest part, the small inner diameter portion 10a2 adjacent to the upper side of the minimum inner diameter portion 10a1 in FIG. 2 and having a larger inner diameter than the minimum inner diameter portion 10a1, the middle inner diameter portion 10a3 adjacent to the upper side of the small inner diameter portion 10a2 in FIG. 2 and having a larger inner diameter than the small inner diameter portion 10a2, and the large inner diameter portion 10a4 adjacent to the upper side of the middle inner diameter portion 10a3 in FIG. 2 and having the largest inner diameter. Further, the cylindrical portion 10a includes a small diameter step portion 10a5 as a second step portion formed between the minimum inner diameter portion 10a1 and the small inner diameter portion 10a2, a middle diameter step portion 10a6 formed between the small inner diameter portion 10a2 and the middle inner diameter portion 10a3, and a large diameter step portion 10a7 as a first step portion formed between the middle inner diameter portion 10a3 and the large inner diameter portion 10a4. In addition, an annular groove 10a8 is provided on the inner periphery of the large inner diameter portion 10a4, and a screw portion 10a9 is provided on the inner periphery of the large inner diameter portion 10a4 above the annular groove 10a8 in FIG. 1. Further, the cap 10 includes a bracket 10c that can be connected to a swing arm that holds the rear wheel in a saddle-type vehicle (not shown) at the lower end of the bottom portion 10b. In the present embodiment, the piston rod 2 is described as being connected to the vehicle body of the saddle-type vehicle and the cap 10 is described as being connected to the rear wheel of the saddle-type vehicle. Conversely, the piston rod 2 may be connected to the rear wheel of the saddle-type vehicle and the cap 10 may be connected to the vehicle body of the saddle-type vehicle.

[0037] In addition, in the present embodiment, as shown in FIG. 1, the cap 10 integrally includes a tank 18 at the tip of a tank connection portion 10d extending from the side of the cylindrical portion 10a. The tank 18 has a cylindrical shape and houses a bladder 19 inside. The inside of the tank 18 is partitioned into a liquid chamber L filled with liquid by the bladder 19 and a gas chamber G filled with gas. Note that gas is enclosed in the gas chamber G such that at least the pressure inside the gas chamber G is equal to or higher than the atmospheric pressure when the shock absorber D is fully extended. Note that the partition between the liquid chamber L and the gas chamber G inside the tank 18 may be formed by using a free piston in addition to using an elastic partition such as a bladder or a diaphragm.

[0038] Subsequently, the outer periphery of the lower end of the cylinder 1 is press-fitted into the inner periphery of the small inner diameter portion 10a2 of the cylindrical portion 10a of the cap 10, and the cylinder 1 is fixed to the cap 10. In this way, the small inner diameter portion 10a2 functions as an insertion portion into which the cylinder 1 is inserted. Further, the lower end in FIG. 2, which is the other end of the cylinder 1, is inserted into the small inner diameter portion 10a2 until it abuts against the small diameter step portion 10a5, which is the second step portion of the cylindrical portion 10a.

[0039] In addition, the outer tube 4 is inserted into the large inner diameter portion 10a4 of the cylindrical portion 10a of the cap 10, and the screw portion 4a on the outer periphery is screwed to the screw portion 10a9 provided on the inner periphery of the large inner diameter portion 10a4, and is fixed to the cap 10. The outer tube 4 abuts the lower end in FIG. 2 against the large diameter step portion 10a7, which is the first step portion of the cylindrical portion 10a, and a frictional force is generated between the screw threads of the screw portions 4a and 10a9 by the axial force acting downward from the screw portion 4a, so that it is firmly fixed to the cap 10. Note that a seal ring 20 that closely adheres to the outer periphery of the outer tube 4 is accommodated in an annular groove 10a8 provided on the inner periphery of the large inner diameter portion 10a4 of the cylindrical portion 10a, and the space between the outer tube 4 and the cap 10 is sealed.

[0040] In this way, when the cylinder 1 and the outer tube 4 are attached to the cap 10, the fitting portion 11a of the collar 11 in the stopper S mounted on the inner periphery of the outer tube 4 fits onto the outer periphery of the upper end of the cylinder 1 in FIG. 1, and the opposing portion 11b abuts against the upper end of the cylinder 1 or faces it with a slight gap therebetween. Thus, the upper end of the cylinder 1 is centered with respect to the cap 10 and the outer tube 4 by the stopper S, and the cylinder 1 is prevented from falling out from within the small inner diameter portion 10a2 serving as the insertion portion of the cap 10.

[0041] Furthermore, when the cylinder 1 and the outer tube 4 are attached to the cap 10, the outer tube 4 covers the outer periphery of the cylinder 1 and forms an annular passage C therebetween as described above. Since a through hole 1a is provided near the upper end of the cylinder 1, the annular passage C communicates with the extension chamber R1 within the cylinder 1 through the through hole 1a.

[0042] In addition, the cap 10 is provided with an external passage P that communicates with the extension chamber R1 via the annular passage C and also communicates with the pressure chamber R2. Specifically, the external passage P includes a first port P1 that opens to the inner periphery of the middle inner diameter portion 10a3 located on the bottom side rather than the tip of the outer tube 4 of the cylindrical portion 10a and communicates with the annular passage C, a second port P2 that opens to the inner periphery of the minimum inner diameter portion 10a1 located on the bottom side rather than the cylinder 1 of the cylindrical portion 10a and communicates with the pressure chamber R2, and a connection passage P3 that connects the first port P1 and the second port P2. Therefore, the annular passage C and the external passage P bypass the main damping passage M to communicate the extension chamber R1 and the pressure chamber R2, constituting a bypass path B. Since the lower end of the outer tube 4 abuts against the large diameter step portion 10a7, there is no concern that the outer tube 4 blocks the first port P1. Also, since the outer periphery of the lower end of the cylinder 1 is press-fitted into the inner periphery of the small inner diameter portion 10a2 of the cap 10, the pressure chamber R2 is not communicated with the annular passage C through the space between the cylinder 1 and the cap 10. Further, since the second port P2 opens to the inner periphery of the minimum inner diameter portion 10a1, the second port P2 can be linearly opened from the lateral direction with respect to the cap 10, so that the second port P2 can be formed easily and at low cost. If the minimum inner diameter portion 10a1 is not provided in the cylindrical portion 10a, the second port P2 may be provided to open from the bottom 10b, and the other end face of the cylinder 1 may be brought into contact with the bottom 10b.

[0043] Furthermore, in the tank connection portion 10d of the cap 10, there are provided a variable damping valve 21 disposed in the middle of the external passage P and capable of adjusting the flow area in the bypass path B, an extension side sub-damping valve 22 disposed in series with the variable damping valve 21 in the middle of the external passage P and providing resistance to the flow of liquid from the extension chamber R1 to the pressure chamber R2, and a pressure side sub-damping valve 23 disposed in series with the variable damping valve 21 in the middle of the external passage P and in parallel with the extension side sub-damping valve 22 and providing resistance to the flow of liquid from the pressure chamber R2 to the extension chamber R1. Also, in the middle of the external passage P, the side closer to the pressure chamber than the installation positions of the variable damping valve 21, the extension side sub-damping valve 22, and the pressure side sub-damping valve 23 communicates with the liquid chamber L in the tank 18.

[0044] In this embodiment, the variable damping valve 21 includes a valve body 21a that can open and close the bypass passage B, a spring 21b that biases the valve body 21a to close, and a solenoid 21c that can generate a thrust force to push the valve body 21a in the opening direction against the biasing force of the spring 21b. The degree of valve opening can be adjusted according to the amount of current supplied to the solenoid 21c, and it is an electromagnetic valve that closes when the current to the solenoid 21c is cut off. Note that although the variable damping valve 21 is an electromagnetic valve whose degree of valve opening can be adjusted in this way, it may be an electromagnetic valve whose opening pressure can be adjusted, or it may be a variable valve whose adjustment of the degree of valve opening or adjustment of the opening pressure is performed manually.

[0045] The extension-side auxiliary damping valve 22 is a damping valve that opens to resist the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2 and closes to block the passage for the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1. When the flow rate passing through is the same, it is a damping valve that provides less resistance to the flow of liquid than the extension-side main damping valve 13.

[0046] The compression-side auxiliary damping valve 23 is a damping valve that opens to resist the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1 and closes to block the passage for the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2. When the flow rate passing through is the same, it is a damping valve that provides less resistance to the flow of liquid than the compression-side main damping valve 14. Note that an orifice may be provided in parallel with the extension-side auxiliary damping valve 22 and the compression-side auxiliary damping valve 23.

[0047] The shock absorber D of this embodiment is configured as described above, and the operation of the shock absorber D will be described below. When the shock absorber D extends, the piston rod 2 withdraws from the cylinder 1 and the piston 3 compresses the extension chamber R1. Then, the liquid in the extension chamber R1 moves to the compression chamber R2 through an orifice (not shown) in the main damping passage M, the extension main damping valve 13 in the main damping passage M, or the extension sub-damping valve 22 in the bypass passage B, and the liquid corresponding to the volume of the piston rod 2 withdrawn from the cylinder 1 is supplied from the tank 18 into the cylinder 1. Resistance is applied to the flow of the liquid from the extension chamber R1 toward the compression chamber R2 by the orifice (not shown), the main damping passage M, or the extension sub-damping valve 22, and an extension damping force due to the resistance is generated. And, the distribution ratio of the liquid passing through the main damping passage M and the extension sub-damping valve 22 during the extension operation of this shock absorber D changes according to the amount of electricity supplied to the variable damping valve 21. Regarding the resistance applied when the liquid passes through the main damping passage M, when the extension speed of the shock absorber D is in the low speed range, the extension main damping valve 13 does not open and the flow of the liquid is resisted by the orifice (not shown), and when the extension speed of the shock absorber D is in the high speed range, the extension main damping valve 13 opens and the flow of the liquid is resisted by the extension main damping valve 13.

[0048] Specifically, when the shock absorber D extends, the liquid passes through the main damping passage M and the extension-side auxiliary damping valve 22 when the variable damping valve 21 opens. However, when the variable damping valve 21 closes, the bypass passage B is blocked, so the liquid cannot pass through the extension-side auxiliary damping valve 22 and moves from the extension-side chamber R1 to the compression-side chamber R2 only through the main damping passage M. Also, when a current is supplied to the variable damping valve 21 to open it and the amount of current supplied is increased, the opening degree of the variable damping valve 21 increases and the flow rate of the liquid passing through the bypass passage B increases. Therefore, the proportion of the liquid passing through the extension-side auxiliary damping valve 22 increases, and the proportion of the liquid passing through the main damping passage M decreases. Thus, by adjusting the amount of current supplied to the variable damping valve 21, the damping force characteristic generated by the shock absorber D during the extension operation can be changed within the range from the soft characteristic mainly generated by the extension-side auxiliary damping valve 22 to the hard characteristic mainly generated by the main damping passage M, as shown in FIG. 3, by adjusting the amount of current supplied to the variable damping valve 21.

[0049] Conversely, when the shock absorber D contracts, the piston rod 2 penetrates into the cylinder 1 and the piston 3 compresses the compression-side chamber R2. Then, the liquid in the compression-side chamber R2 moves through an orifice (not shown) in the main damping passage M, the compression-side main damping valve 14 in the main damping passage M, or the compression-side auxiliary damping valve 23 of the bypass passage B to the extension-side chamber R1, and at the same time, the liquid corresponding to the volume of the piston rod 2 that has penetrated into the cylinder 1 is discharged from the compression-side chamber R2 into the tank 18. Regarding the flow of the liquid from the compression-side chamber R2 to the extension-side chamber R1, resistance is applied by the main damping passage M or the compression-side auxiliary damping valve 23, and a compression-side damping force is generated due to this resistance. And the distribution ratio of the liquid passing through the main damping passage M and the compression-side auxiliary damping valve 23 during the contraction operation of this shock absorber D changes according to the amount of energization of the variable damping valve 21. Regarding the resistance applied when the liquid passes through the main damping passage M, when the contraction speed of the shock absorber D is in the low-speed range, the compression-side main damping valve 14 does not open and resistance is applied to the flow of the liquid by an orifice (not shown), and when the contraction speed of the shock absorber D is in the high-speed range, the compression-side main damping valve 14 opens and resistance is applied to the flow of the liquid by the compression-side main damping valve 14.

[0050] Specifically, when the shock absorber D contracts, the liquid passes through the main damping passage M and the pressure-side auxiliary damping valve 23 when the variable damping valve 21 opens. However, when the variable damping valve 21 closes, the bypass passage B is blocked, so the liquid cannot pass through the pressure-side auxiliary damping valve 23 and moves from the pressure-side chamber R2 to the extension-side chamber R1 only through the main damping passage M. Also, when a current is supplied to the variable damping valve 21 to open it and the amount of current supplied is increased, the degree of opening of the variable damping valve 21 increases and the flow rate of the liquid passing through the bypass passage B increases. Therefore, the proportion of the liquid passing through the pressure-side auxiliary damping valve 23 increases, and the proportion of the liquid passing through the main damping passage M decreases. Thus, by adjusting the amount of current supplied to the variable damping valve 21, the damping force characteristics generated by the shock absorber D during the contraction operation can be changed, as shown in FIG. 3, from the soft characteristics mainly generated by the pressure-side auxiliary damping valve 23 to the hard characteristics mainly generated by the main damping passage M, within the range of adjustment of the amount of current supplied to the variable damping valve 21.

[0051] As described above, the shock absorber D of the present embodiment includes a cylinder 1, a piston rod 2 that is inserted into the cylinder 1 so as to be movable in the axial direction and protrudes outward from one end of the cylinder 1, a piston 3 that is connected to the piston rod 2 and is inserted into the cylinder 1 so as to be movable in the axial direction and divides the inside of the cylinder 1 into an extension-side chamber R1 and a pressure-side chamber R2, a cap 10 having a small inner diameter portion (insertion portion) 10a2 that is bottomed cylindrical and into which the other end of the cylinder 1 is inserted on the inner periphery of the cylindrical portion 10a to close the other end of the cylinder 1, an outer tube 4 that is cylindrical and forms an annular passage C that communicates with the extension-side chamber R1 between the outer periphery of the cylinder 1 and is screwed on the inner periphery of the cylindrical portion 10a of the cap 10 on the tip side of the small inner diameter portion (insertion portion) 10a2, and a stopper S that is attached to the outer tube 4 and faces one end of the cylinder 1 to prevent the cylinder 1 from falling off the cap 10.

[0052] According to the buffer D configured in this way, the other end of the cylinder 1 is inserted into the cylindrical portion 10a of the cap 10, the outer tube 4 is screwed to the cylindrical portion 10a of the cap 10, and the outer tube 4 is provided with a stopper S that faces one end of the cylinder 1 and prevents the cylinder 1 from falling off the cap 10. Therefore, it is not necessary to adopt a structure in which a flange is provided at the other end of the cylinder 1 and the flange is sandwiched between the outer tube 4 and the cap 10, and it is not necessary to perform groove processing for forming an annular groove on the outer periphery of the cylinder 1. Thus, according to the buffer D of the present embodiment, since groove processing of the cylinder 1 is not required when forming the annular passage C between the cylinder 1 and the outer tube 4, the manufacturing cost can be reduced even if the annular passage C is provided inside.

[0053] Also, in the buffer D of the present embodiment, the cap 10 has a large-diameter step portion (first step portion) 10a7 that abuts against the end portion of the outer tube 4 on the inner periphery of the cylindrical portion 10a, and the cylinder 1 is press-fitted into the small inner-diameter portion (insertion portion) 10a2 of the cap 10. According to the buffer D configured in this way, since the end portion of the outer tube 4 can abut against the first step portion (large-diameter step portion) 10a7, an axial force can be applied to the outer tube 4 to firmly fix the outer tube 4 to the cap 10. At the same time, since the cylinder 1 is press-fitted into the small inner-diameter portion (insertion portion) 10a2 of the cap 10, it is possible to prevent the annular passage C from communicating with the pressure-side chamber R2 through the space between the cylinder 1 and the cap 10, and it is not necessary to install a sealing member between the cylinder 1 and the cap 10, further reducing the manufacturing cost. Also, since the outer tube 4 abuts against the large-diameter step portion (first step portion) 10a7, by providing the first port P1 of the bypass path B on the bottom side rather than the large-diameter step portion (first step portion) 10a7 of the cylindrical portion 10a, it is possible to prevent the outer tube 4 from blocking the first port P1. Furthermore, since the stopper S only needs to prevent the cylinder 1 from falling off the cap 10, it is not necessary to apply an axial force to the cylinder 1, high strength is not required, and an inexpensive configuration can be adopted.

[0054] And, the stopper S in the shock absorber D of the present embodiment includes a snap ring 12 attached to the inner periphery of the outer tube 4, a fitting portion 11a that fits onto the inner periphery of the outer tube 4 and also fits onto the outer periphery of one end of the cylinder 1, and a collar 11 having an opposing portion 11b provided on the inner periphery of the fitting portion 11a and facing one end of the cylinder 1. According to the shock absorber D configured in this way, the collar 11 that fits onto the inner periphery of the outer tube 4 can center one end of the cylinder 1 concentrically with respect to the outer tube 4. The use of the snap ring 12 facilitates the fixing of the collar 11 and also makes the inner periphery machining of the outer tube 4 inexpensive. Although it is also possible to configure the stopper S only with the collar 11 by screwing the collar 11 to the inner periphery of the outer tube 4, in terms of cost, since machining to provide screw portions on the inner periphery of the outer tube 4 and the outer periphery of the collar 11 is required, it is more advantageous to configure the stopper S with the snap ring 12 and the collar 11.

[0055] It is also possible to integrate the stopper S with the rod guide 17 by providing a fitting portion that fits onto the outer periphery of the cylinder 1 on the outer periphery of the lower end of the rod guide 17 in FIG. 1. In this case, since the rod guide 17 approaches and faces or abuts against one end of the cylinder 1, it becomes impossible to push the rod guide 17 into the outer tube 4. If a structure in which the rod guide 17 is fixed with the snap ring 16 is adopted, the shock absorber D cannot be disassembled. Therefore, the snap ring 16 may be abolished and screw portions may be provided on the outer periphery of the rod guide 17 and the inner periphery of the outer tube 4, and the rod guide 17 may be screwed to the outer tube 4.

[0056] Furthermore, the shock absorber D of the present embodiment includes a main damping passage M that provides resistance to the flow of liquid flowing back and forth between the extension chamber R1 and the compression chamber R2, a bypass passage B that bypasses the main damping passage M and connects the extension chamber R1 and the compression chamber R2, and a variable damping valve 21 that provides resistance to the flow of liquid passing through the bypass passage B. The cap 10 has a first port P1 that opens on the bottom side rather than the tip of the outer tube 4 of the cylindrical portion 10a and communicates with the annular passage C, and a second port P2 that opens on the bottom side rather than the cylinder 1 and communicates with the compression chamber. The bypass passage B is formed by an external passage P that connects the first port P1 and the second port P2 and is provided with the variable damping valve 21, and the annular passage C.

[0057] According to the shock absorber D configured as described above, the damping characteristics can be adjusted by the variable damping valve 21 provided in the bypass passage B. Even when the cylinder 1 is inserted into the cylindrical portion 10a of the cap 10 and the outer tube 4 is screwed, the external passage P that constitutes the bypass passage B is not blocked by the cylinder 1 and the outer tube 4, and holes for ensuring the communication of the bypass passage B and the external passage P do not need to be provided in the cylinder 1 and the outer tube 4. Therefore, the manufacturing cost is further reduced and the assemblability is also improved.

[0058] In the above description, the small inner diameter portion 10a2 of the cap 10 is used as the insertion portion, and the lower end in FIG. 2 as the other end of the cylinder 1 is press-fitted into the small inner diameter portion 10a2. However, as in the shock absorber D1 of the first modification of the embodiment shown in FIG. 4, a screw groove may be provided on the inner periphery of the small inner diameter portion 10a2, and a screw portion 1b may be provided on the outer periphery of the other end of the cylinder 1. The other end of the cylinder 1 may be screwed to the small inner diameter portion 10a2 of the cap 10 to fix the cylinder 1 to the cap 10. In this case, if a small diameter step portion (second step portion) 10a5 that abuts against the other end surface of the cylinder 1 is provided on the cylindrical portion 10a of the cap 10, when the cylinder 1 is screwed to the cap 10, the cylinder 1 is pressed against the small diameter step portion (second step portion) 10a5, and the space between the cylinder 1 and the cap 10 is sealed, so that a sealing member does not need to be provided. Therefore, the manufacturing cost of the shock absorber D can be further reduced.

[0059] Furthermore, as described above, the other end of the cylinder 1 is press-fitted into the small-inner-diameter portion 10a2, which is the insertion portion of the cylindrical portion 10a of the cap 10. However, if the cylinder 1 is not fixed to the cap 30 merely by inserting the other end of the cylinder 1 into the small-inner-diameter portion 10a2, as in the shock absorber D2 of the second modification of the embodiment shown in FIG. 5, the inner diameter of the cylindrical portion 30a is enlarged in three steps from the bottom portion 30b side toward the tip. The step portion where the end face of the outer tube 4 abuts against the cylindrical portion 30a is eliminated, and the cylinder 1 may be fixed by sandwiching the cylinder 1 between the stopper S and the cap 30 by screwing the outer tube 4 to the cylindrical portion 10a of the cap 10. In this case, the cylindrical portion 30a of the cap 30 includes a small-diameter portion 30a1 having the smallest inner diameter at the deepest part, a middle-diameter portion 30a2 adjacent to the upper side of the small-diameter portion 30a1 in FIG. 2 and having a larger inner diameter than the small-diameter portion 30a1, a large-diameter portion 30a3 adjacent to the upper side of the middle-diameter portion 30a2 in FIG. 5 and having a larger inner diameter than the middle-diameter portion 30a2, a small-step portion 30a4 as a second step portion formed between the small-diameter portion 30a1 and the middle-diameter portion 30a2, and a large-step portion 30a5 formed between the middle-diameter portion 30a2 and the large-diameter portion 30a3. In addition, an annular groove 30a6 is provided on the inner periphery of the large-diameter portion 30a3, and a screw portion 30a7 is provided on the inner periphery of the large-diameter portion 30a3 above the annular groove 30a6 in FIG. 5.

[0060] And the outer periphery of the lower end of the cylinder 1 is inserted into the inner periphery of the middle-diameter portion 30a2 in the cylindrical portion 10a of the cap 10. In this way, the middle-diameter portion 30a2 functions as an insertion portion into which the cylinder 1 is inserted. Also, the lower end in FIG. 5, which is the other end of the cylinder 1, is inserted into the middle-diameter portion 30a2 until it abuts against the small-step portion 30a4, which is the second step portion in the cylindrical portion 30a.

[0061] Also, the outer tube 4 is inserted into the large-diameter portion 30a3 in the cylindrical portion 30a of the cap 30, and the screw portion 4a on the outer periphery is screwed to the screw portion 30a7 provided on the inner periphery of the large-diameter portion 30a3, so that the outer tube 4 is fixed to the cap 10. When the outer tube 4 is screwed to the screw portion 30a7, the cylinder 1 is sandwiched between the stopper S attached to the inner periphery of the outer tube 4 and the small-step portion 30a4, which is the first step portion of the cap 30, and the cylinder 1 is fixed to the cap 30.

[0062] In addition, a seal ring 20 that closely adheres to the outer periphery of the outer tube 4 is accommodated in an annular groove 30a6 provided on the inner periphery of the large-diameter portion 30a3 of the cylindrical portion 30a, and the space between the outer tube 4 and the cap 30 is sealed.

[0063] Furthermore, when the cylinder 1 and the outer tube 4 are attached to the cap 10, the outer tube 4 covers the outer periphery of the cylinder 1 and forms an annular passage C therebetween as described above. Since a through-hole 1a is provided near the upper end of the cylinder 1, the annular passage C communicates with the extension chamber R1 inside the cylinder 1 through the through-hole 1a. Note that the cap 30 includes a bracket 30c and a tank connection portion 30d connected to the tank 18, similar to the cap 10. Also, an external passage P communicating with the annular passage C, a variable damping valve 21, an extension-side auxiliary damping valve 22, and a compression-side auxiliary damping valve 23 are provided in the tank connection portion 30d. In the shock absorber D2 of the second modification, since the cylinder 1 is sandwiched between the small-diameter portion 30a4 as the second step portion formed on the inner periphery of the cylindrical portion 30a of the cap 30 and the stopper S of the outer tube 4, the other end surface of the cylinder 1 and the small-diameter portion 30a4 are in close contact and the compression chamber R2 does not communicate with the annular passage C through the space between the cylinder 1 and the cap 10. Note that even when the outer tube 4 is screwed to the cylindrical portion 30a, a sufficient distance is provided between the first port P1 and the screw portion 30a7 so that the lower end of the outer tube 4 does not face the first port P1 that opens to the large-diameter portion 30a3.

[0064] Thus, in the shock absorber D2 of the second modification, the cap 30 includes a small step portion (second step portion) 30a4 that abuts against the other end of the cylinder 1 on the inner periphery of the cylindrical portion 30a, and the cylinder 1 is sandwiched between the small step portion (second step portion) 30a4 and the stopper S. According to the shock absorber D2 configured in this way, the cylinder 1 can be firmly fixed by being sandwiched between the outer tube 4 and the cap 30. Moreover, since the cylinder 1 is in close contact with the small step portion (second step portion) 30a4 of the cap 30, it is possible to prevent the annular passage C from communicating with the compression chamber R2 through the space between the cylinder 1 and the cap 10, eliminating the need to install a sealing member between the cylinder 1 and the cap 10 and further reducing the manufacturing cost.

[0065] Note that in the shock absorbers D, D1, and D2 of the present embodiment, in addition to the variable damping valve 21 in the bypass passage B, an extension side auxiliary damping valve 22 and a compression side auxiliary damping valve 23 are provided. However, since the variable damping valve 21 can adjust the opening area of the bypass passage B to provide resistance to the flow of the liquid passing through and can adjust the damping force, the damping force can still be adjusted even if the extension side auxiliary damping valve 22 and the compression side auxiliary damping valve 23 are abolished.

[0066] Furthermore, as in the shock absorber D3 of the third modification of the embodiment shown in FIG. 6, the stopper S1 may be composed of a bump stopper 40 screwed to the outer tube 4 and a rod guide 17 to prevent the cylinder 1 from falling off the cap 10. Specifically, as shown in FIG. 6, the shock absorber D3 of the third modification sandwiches the cylinder 1 with a small diameter step portion 10a5 of the cap 10 screwed to the outer periphery of the lower end of the outer tube 4 in FIG. 6 and a stopper S1 composed of a bump stopper 40 and a rod guide 17 to fix the cylinder 1 and prevent it from falling off the cap 10.

[0067] More specifically, the bump stopper 40 includes an annular top portion 40a and a cylindrical portion 40b that extends from the outer periphery of the top portion 40a toward the cylinder side and has a threaded portion 40b1 on the outer periphery, and is screwed to the inner periphery of the upper end of the outer tube 4 in FIG. 6. The bump stopper 40 faces the cylindrical bump cushion 41 mounted on the outer periphery of the upper end of the piston rod 2 in FIG. 6, and abuts against the bump cushion 41 when the shock absorber D3 is fully contracted. When the bump cushion 41 abuts against the bump stopper 40 and is compressed by the contraction of the shock absorber D3, it exerts an elastic force to prevent further contraction of the shock absorber D3 and mitigate the impact at the full contraction of the shock absorber D3.

[0068] In the third modification, the collar 11 is abolished and the rod guide 17 is fitted to the outer periphery of the cylinder 1. Therefore, the rod guide 17 has an annular fitting portion 17c that fits to the outer periphery of the cylinder 1 at the outer periphery of the lower end in FIG. 6. Further, the cylinder 1 abuts the upper end in FIG. 6 against the inner peripheral side surface of the lower end of the rod guide 17 in FIG. 6, which is the fitting portion 17c, and is centered by the fitting portion 17c of the rod guide 17 to restrict movement in the radial direction and upward movement.

[0069] Also, in the shock absorber D3 of the third modification, a valve case 43 with an extension side sub-damping valve 22 and a compression side sub-damping valve 23 assembled therein is fitted to the inner periphery of the lower end of the cylinder 1 in FIG. 6. The valve case 43 is annular and includes an annular case body 43a that fits to the inner periphery of the lower end of the cylinder 1, a flange 43b provided on the outer periphery of the lower end of the case body 43a in FIG. 6 and abutting against the lower end of the cylinder 1, and an extension side port 43c and a compression side port 43d that penetrate the case body 43a in the axial direction.

[0070] The cylinder 1 with the valve case 43 fitted to its lower end inner circumference is tightened by screwing the bump stopper 40 into the inner circumference of the upper end of the outer tube 4. As the cylindrical portion 40b of the bump stopper 40 abuts against the outer circumference of the upper end of the rod guide 17 in FIG. 6, the rod guide 17 is tightened so as to move downward. Thus, between the rod guide 17 and the cap 10, the cylinder 1 and the flange 43b of the valve case 43 receive an axial load and are firmly fixed. By configuring the stopper S1 with the bump stopper 40 and the rod guide 17 and adopting a structure in which the bump stopper 40 is screwed to the outer tube 4, it is possible to apply a desired axial force to the cylinder 1 and press it against the cap 10 for fixation, thereby preventing the cylinder 1 from falling off the cap 10.

[0071] Note that an extension side sub-damping valve 22, which is an annular leaf valve that opens and closes the upper end opening of the extension side port 43c, is laminated above the valve case 43 in FIG. 6, and a compression side sub-damping valve 23, which is an annular leaf valve that opens and closes the lower end opening of the compression side port 43d, is laminated below the valve case 43 in FIG. 6. These extension side sub-damping valve 22 and compression side sub-damping valve 23 are sandwiched by a center rod 44 that is inserted through the inner circumference of the case body 43a, has a screw portion 44a at its tip, and a flange 44b at its base end, and a nut 45 that is screwed to the screw portion 44a of the center rod 44, and is fixed to the valve case 43.

[0072] Thus, in the shock absorber D3 of the third modification, the cap 10 has a small-diameter stepped portion (second stepped portion) 10a5 that abuts against the valve case 43 fitted to the lower end of the cylinder 1 on the inner circumference of the cylindrical portion 10a, and the cylinder 1 is sandwiched between the small-diameter stepped portion (second stepped portion) 10a5 and the stopper S1. According to the shock absorber D3 configured in this way, the cylinder 1 can be firmly fixed by being sandwiched between the outer tube 4 and the cap 10. Also, since the cylinder 1 is in close contact with the small-diameter stepped portion (second stepped portion) 10a5 of the cap 10, it is possible to prevent the annular passage C from communicating with the compression chamber R2 through the space between the cylinder 1 and the cap 10, eliminating the need to install a sealing member between the cylinder 1 and the cap 10 and further reducing the manufacturing cost. Further, since the valve case 43 to which the extension-side auxiliary damping valve 22 and the compression-side auxiliary damping valve 23 are assembled can be fixed to the cap 10 together with the cylinder 1, the extension-side auxiliary damping valve 22 and the compression-side auxiliary damping valve 23 can be easily assembled. When the extension-side auxiliary damping valve 22 and the compression-side auxiliary damping valve 23 are not necessary, the valve case 43 can be eliminated, and the cylinder 1 can be directly abutted against the small-diameter stepped portion (second stepped portion) 10a5 and fixed to the cap 10.

[0073] As described above, the preferred embodiments of the present invention have been described in detail. However, modifications, variations, and changes are possible without departing from the scope of the claims.

Description of Reference Numerals

[0074] 1... cylinder, 2... piston rod, 3... piston, 4... outer tube, 10, 30... cap, 10a, 30a... cylindrical portion, 10a2... small inner diameter portion (insertion portion), 10a5... small-diameter stepped portion (second stepped portion), 10a7... large-diameter stepped portion (first stepped portion), 11... collar, 11a... fitting portion, 11b... opposing portion, 21... variable damping valve, 30a2... medium-diameter portion, 30a4... small stepped portion (second stepped portion), B... bypass passage, C... annular passage, D, D1, D2, D3... shock absorber, M... main damping passage, P... external passage, P1... first port, P2... second port, R1... extension chamber, R2... compression chamber, S, S1... stopper

Claims

1. A cylinder, a piston rod that is inserted into the cylinder so as to be axially movable and protrudes outward from one end of the cylinder, a piston that is connected to the piston rod and is inserted into the cylinder so as to be axially movable, and partitions the inside of the cylinder into an extension chamber and a compression chamber, a bottomed cylindrical cap having an insertion portion into which the other end of the cylinder is inserted on the inner periphery of the cylindrical portion and closing the other end of the cylinder, an outer tube that covers the outer peripheral side of the cylinder and forms an annular passage communicating with the extension chamber between the outer tube and the cylinder, and is screwed to the inner periphery of the cylindrical portion of the cap on the tip side of the insertion portion, and a stopper that is attached to the outer tube and prevents the cylinder from falling off from the cap facing one end of the cylinder. A shock absorber characterized by the above.

2. The cap has a first step portion that abuts on the end portion of the outer tube on the inner periphery of the cylindrical portion, and the cylinder is press-fitted into the insertion portion of the cap. The shock absorber according to claim 1, characterized by the above.

3. The cap has a second step portion that abuts on the other end of the cylinder on the inner periphery of the cylindrical portion, and the cylinder is sandwiched between the second step portion and the stopper. The shock absorber according to claim 1, characterized by the above.

4. The stopper is a snap ring attached to the inner periphery of the outer tube, and a collar having a cylindrical fitting portion that is fitted to the inner periphery of the outer tube and fitted to the outer periphery of one end of the cylinder, and an opposing portion provided on the inner periphery of the fitting portion and facing one end of the cylinder. The shock absorber according to any one of claims 1 to 3, characterized by the above.

5. A main damping passage that resists the flow of liquid flowing back and forth between the extension chamber and the compression chamber, a bypass passage that bypasses the main damping passage and communicates the extension chamber and the compression chamber, and a variable damping valve that resists the flow of liquid passing through the bypass passage. The cap has a first port that opens on the bottom side of the tip of the outer tube of the cylindrical portion and communicates with the annular passage, and a second port that opens on the bottom side of the cylinder and communicates with the compression chamber. The bypass passage is formed by an external passage that connects the first port and the second port and in which the variable damping valve is provided, and the annular passage. The shock absorber according to any one of claims 1 to 3, characterized in that...

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