JP7356622B1 - buffer - Google Patents

Abstract

The buffer (D) includes a cylinder (1), a piston (2) movably inserted into the cylinder (1), a piston rod (3) connected to the piston (2), and stores liquid. A tank (4), a first passage (P1) and a second passage (P2) that connect the expansion side chamber (R1) and the compression side chamber (R2) in parallel, respectively, and the compression side chamber (R2) and the tank (4). a third passage (P3) that communicates with A valve unit (V) is provided which is removably installed in the middle of the three passages (P3). Further, the valve unit (V) includes a compression side damping valve (V1), a compression side relief valve (V2), and a growth side check valve (V3) in parallel.

Description

The present invention relates to a shock absorber.

A shock absorber is used, for example, by being interposed between the vehicle body and wheels of a straddle-type vehicle, and suppresses vibrations of the vehicle body and wheels using damping force generated during expansion and contraction.

When used in relatively lightweight straddle-type vehicles, some shock absorbers do not include a damping valve on the compression side, since vibrations of the vehicle body can be sufficiently suppressed by exerting damping force only when the shock absorber is extended.

Such a shock absorber includes, for example, a cylinder, a piston that is movably inserted into the cylinder and divides the cylinder into a compression side chamber and a compression side chamber filled with hydraulic oil, and a piston that is movably inserted into the cylinder and divides the cylinder into a compression side chamber and a compression side chamber filled with hydraulic oil. a piston rod that is connected to the piston, a tank that stores hydraulic oil, a compression side port and a compression side port that are provided in the piston and that communicate the growth side chamber and the compression side chamber, and a growth side chamber that is provided in the growth side port. A compression side damping valve that provides resistance to the flow of hydraulic fluid from the pressure side chamber toward the compression side chamber, a pressure side check valve that is provided at the pressure side port and allows only the flow of liquid from the compression side chamber toward the expansion side chamber, and the pressure side chamber and the tank. It is configured to include a tank passage that communicates with the tank passage.

When the shock absorber configured in this manner is extended, the hydraulic oil moves from the compression side chamber where it is compressed to the compression side chamber where it expands through the rebound side damping valve, so that the pressure in the expansion side chamber increases and the expansion occurs. Generates a damping force that prevents operation. In addition, when the shock absorber is contracted, the hydraulic oil moves from the pressure side chamber where it is compressed to the expansion side chamber where it expands via the pressure side check valve. It generates almost no damping force that interferes with operation.

Japanese Patent Application Publication No. 2000-130488

In this way, shock absorbers used in relatively lightweight straddle-type vehicles are configured to exert damping force only when they are extended, but in cases where damping force is required to be exerted even when they are retracted. There is. Here, in order for the shock absorber to exert damping force even during contraction, it is necessary to provide a pressure-side damping valve between the pressure-side chamber and the tank, which provides resistance to the flow of hydraulic oil from the pressure-side chamber to the tank. be.

However, it is not possible to additionally provide a compression side damping valve to a conventional shock absorber, and if a shock absorber that exerts damping force even during contraction operation is desired compared to a conventional shock absorber, the manufacturer of the shock absorber In this case, it is necessary to design and manufacture a new shock absorber equipped with a pressure-side damping valve in place of the conventional shock absorber. Therefore, there is a desire to be able to easily add a function that can exert a damping force during contraction operation to a shock absorber that is not equipped with a compression side damping valve.

Therefore, an object of the present invention is to provide a shock absorber that can be easily added with a function of exerting a damping force during the contraction operation.

In order to solve the above-mentioned problems, the shock absorber of the present invention includes a cylinder, a piston that is movably inserted into the cylinder and divides the cylinder into a compression side chamber and a compression side chamber filled with liquid, and A piston rod movably inserted into the piston and connected to the piston, a tank for storing liquid, a first passage and a second passage communicating in parallel with the expansion side chamber and the compression side chamber, respectively, and the compression side chamber and the tank. a third passage communicating with the first passage; a rebound damping valve provided in the first passage to provide resistance to the flow of liquid from the compression side chamber to the compression side chamber; It is equipped with a pressure side check valve that allows only the flow of liquid, and a valve unit that is removably installed in the middle of the third passage, and the valve unit is a pressure side damping valve that provides resistance to the flow of liquid from the pressure side chamber to the tank. is placed in parallel with the pressure side damping valve, and when the valve is closed, communication between the pressure side chamber and the tank is cut off, and when the pressure difference between the pressure in the pressure side chamber and the pressure in the tank reaches the valve opening pressure, the valve opens and the pressure side damping valve is opened, and the pressure side damping valve is connected to the tank. The tank includes a pressure-side relief valve that allows liquid to flow toward the pressure-side chamber, and an expansion-side check valve that is arranged in parallel with the pressure-side damping valve and allows only the liquid to flow from the tank toward the pressure-side chamber.

In the shock absorber configured in this way, a valve unit including a pressure side damping valve, a pressure side relief valve, and a growth side check valve in parallel is removably installed in the middle of the third passage communicating the pressure side chamber and the tank. Therefore, by simply attaching the valve unit, a shock absorber that exerts damping force only during extension can function as a shock absorber that exerts damping force not only during extension but also during contraction. Furthermore, by removing the valve unit, the shock absorber can be used as a shock absorber that exerts damping force only during the extension operation.

Depending on the presence or absence of the valve unit, the shock absorber can be set to either a shock absorber that generates damping force during both extension and contraction operations, or a shock absorber that generates damping force only during extension operation. A shock absorber manufacturer can assemble shock absorbers other than the valve unit using the same parts on the same line, and can manufacture the shock absorber with or without a valve unit depending on the user's request. Therefore, the manufacturer can reduce the manufacturing cost of the buffer.

Furthermore, according to the shock absorber configured as described above, since the valve unit is equipped with a pressure side relief valve, the pressure inside the cylinder is maintained even when the shock absorber shrinks at a high speed when the shock absorber is contracted. This can prevent it from becoming too large.

FIG. 1 is a longitudinal sectional view of a shock absorber in one embodiment. FIG. 2 is an enlarged sectional view of a valve unit portion of a shock absorber in one embodiment.

The present invention will be described below based on the embodiments shown in the figures. As shown in FIGS. 1 and 2, the shock absorber D in one embodiment includes a cylinder 1, a growth side chamber R1 and a pressure side chamber R2 that are movably inserted into the cylinder 1 and filled with liquid. A piston 2 partitioned into two parts, a piston rod 3 movably inserted into the cylinder 1 and connected to the piston 2, a tank 4 for storing liquid, a growth side chamber R1 and a pressure side chamber R2 are arranged in parallel. A first passage P1 and a second passage P2 that communicate with each other, a third passage P3 that communicates between the pressure side chamber R2 and the tank 4, and a flow of liquid provided in the first passage P1 and directed from the expansion side chamber R1 to the pressure side chamber R2. A compression side damping valve 5 that provides resistance to the expansion side, a compression side check valve 6 that is provided in the second passage P2 and allows only the flow of liquid from the compression side chamber R2 to the expansion side chamber R1, and a compression side check valve 6 that can be attached and detached in the middle of the third passage P3. The valve unit V is provided with a valve unit V provided in the valve unit V. In the case of this shock absorber D, it is used by being interposed between the vehicle body and wheels of a vehicle (not shown), and suppresses vibrations of the vehicle body and wheels.

Each part of the buffer D will be explained in detail below. As shown in FIG. 1, an annular cap 10, an annular seal member 8, and an annular rod guide 7 are inserted into the inner periphery of the cylinder 1 at the lower end in FIG. ing. The rod guide 7 is fixed within the cylinder 1 by a caulked portion 1a on the outer periphery of the cylinder 1. The cap 10 and the seal member 8 are held between the rod guide 7 and the caulking portion 1b at the lower end of the cylinder 1, and are fixed to the cylinder 1. Note that the design of the means for fixing the cap 10, the seal member 8, and the rod guide 7 to the cylinder 1 can be changed as desired.

Further, a housing 11 is attached to the upper end of the cylinder 1 in FIG. 1 to close the upper end of the cylinder 1, connect the cylinder 1 and the tank 4, and house the valve unit V. A piston rod 3 having a piston 2 attached to its tip is movably inserted into the cylinder 1.

The piston rod 3 is inserted into the cylinder 1 by being slidably inserted through the inner periphery of the seal member 8 and the inner periphery of the rod guide 7, and is guided to move in the axial direction by the rod guide 7. The seal member 8 is in sliding contact with the outer periphery of the piston rod 3 to seal the outer periphery of the piston rod 3 and thereby hermetically seal the inside of the cylinder 1 .

Further, the inside of the cylinder 1 is divided by the piston 2 into a growth side chamber R1 and a pressure side chamber R2 filled with liquid. Note that in this embodiment, the liquid is hydraulic oil, but other liquids such as water and an aqueous solution can also be used.

The piston 2 is connected to the tip of the piston rod 3, which is the upper end in FIG. A bracket B1 is attached to the lower end of the piston rod 3 in FIG. 1, which can be connected to a member that holds a wheel in a vehicle (not shown), and a cylindrical bump cushion 14 is provided on the outer periphery near the lower end in FIG. It is installed.

When the bump cushion 14 is compressed by coming into contact with the cap 10 fixed to the inner periphery of the lower end of the cylinder 1 when the shock absorber D is at its maximum contraction, it exerts an elastic force and when the shock absorber D is at its maximum contraction. Alleviate the impact.

The piston 2 is provided with a first passage P1 and a second passage P2 that connect the expansion side chamber R1 and the compression side chamber R2 in parallel, respectively. Further, the piston 2 includes a rebound damping valve 5 that can open and close the first passage P1 and provides resistance to the flow of liquid from the growth side chamber R1 to the compression side chamber R2, and a second passage P2 that can open and close the second passage P2. A pressure side check valve 6 is provided that allows only the flow of liquid from the compression side chamber R2 toward the expansion side chamber R1. Note that the first passage P1 and the second passage P2 only need to communicate the expansion side chamber R1 and the compression side chamber R2, so they may be installed outside the piston 2, so for example, they may be installed on the outer periphery of the cylinder 1 (not shown). It may be formed by providing an outer cylinder and utilizing the gap between the cylinder 1 and the outer cylinder. Note that the expansion side damping valve 5 only needs to be provided in the first passage P1, and the compression side check valve 6 only needs to be provided in the second passage P2, so the installation locations of the expansion side damping valve 5 and the compression side check valve 6 are may be determined depending on the manner in which the first passage P1 and the second passage P2 are installed.

The expansion-side damping valve 5 may be any valve that can exert a damping force that provides resistance to the flow of hydraulic oil from the expansion-side chamber R1 toward the compression-side chamber R2 and prevents the shock absorber D from expanding when the shock absorber D is extended. Specifically, the growth side damping valve 5 is constructed by laminating a plurality of annular plates on the upper end of the piston 2 in FIG. 1, and opens the first passage P1 when bent by the pressure of the growth side chamber R1. It may be a laminated leaf valve or the like.

Further, the pressure side check valve 6 may be any valve that can only allow the flow of hydraulic oil from the pressure side chamber R2 toward the expansion side chamber R1 without providing any significant resistance during the contraction operation of the shock absorber D. Specifically, the pressure side check valve 6 is composed of, for example, an annular plate stacked on the lower end of the piston 2 in FIG. 1, and a spring with a small spring constant that presses the annular plate. It may be a valve or the like that opens the two passages P2.

In this embodiment, the housing 11 includes an upper cap 11a attached to the upper end of the cylinder 1 in FIG. 11b, and a cylindrical socket 11c that is connected to the lower end of the cylindrical portion 11b in FIG. 1 and holds the tank 4.

Further, the upper cap 11a is connected to the upper end of the cylinder 1 in FIG. 1 to close the upper end of the cylinder 1, and is provided with a bracket B2 at the upper end in FIG. 1 that can be connected to the body of a vehicle (not shown).

In the shock absorber D of this embodiment, as shown in FIGS. 1 and 2, the cylindrical portion 11b extends horizontally with one end integrated with the side of the upper cap 11a, and the inner periphery of the open end extends horizontally. It is provided with a threaded portion 11b1. The inside of the cylindrical portion 11b is a valve hole h, and a valve unit V is housed in the valve hole h. Further, the inside of the cylindrical portion 11b is communicated with a pressure side chamber R2 in the cylinder 1 through a port 11a1 formed in the upper cap 11a. Note that the port 11a1 communicates with the deepest part of the valve hole h.

The socket 11c has an annular shape, has an upper end connected to the side of the cylindrical part 11b, is integrally connected to the lower part in FIG. 1, extends vertically downward, and has a threaded part 11c1 on the outer periphery of the lower end. There is. A cylindrical tank 4 is screwed onto a threaded portion 11c1 on the outer periphery of the lower end of the socket 11c.

The interior of the socket 11c communicates with the inside of the cylindrical portion 11b via a port 11b2 that opens on the side of the cylindrical portion 11b. The deepest part of the valve hole h communicates with the pressure side chamber R2 via the port 11a1, and the middle part communicates with the inside of the socket 11c via the port 11b2.

In this embodiment, the tank 4 has a cylindrical shape and is screwed into the socket 11c. A diaphragm 12 is slidably inserted into the tank 4, and the inside of the tank 4 is divided by the diaphragm 12 into a liquid chamber L filled with liquid and an air chamber G filled with gas. There is. The air chamber G is filled with gas so that at least the pressure within the air chamber G is equal to or higher than atmospheric pressure when the shock absorber D is fully extended. Note that the liquid chamber L and the air chamber G in the tank 4 may be partitioned by using a free piston, a bladder, or the like instead of using the diaphragm 12.

The liquid chamber L in the tank 4 is communicated with the pressure side chamber R2 via a port 11b2 opening into the socket 11c, a valve hole h, and a port 11a1. In this way, in the shock absorber D of this embodiment, the third passage P3 is formed by the port 11b2, the valve hole h, and the port 11a1.

In this way, the housing 11 connects the cylinder 1 and the tank 4, and has a third passage P3 that communicates the pressure side chamber R2 and the tank 4, and a valve hole that accommodates the valve unit V in the middle of the third passage P3. It is equipped with h. The housing 11 includes a cylindrical portion 11b forming a valve hole h on the side of an upper cap 11a that closes the upper end of the cylinder 1, and a socket 11c for attaching the tank 4 below the cylindrical portion 11b. . Therefore, by arranging the valve unit V on the side of the cylinder 1, it is possible to suppress the overall length of the shock absorber D from increasing. Note that the valve hole h is formed by the cylindrical portion 11b arranged along the radial direction with respect to the cylinder 1, and the opening end faces away from the cylinder, so that the valve unit V can be attached and detached from the shock absorber D. This can be done easily from the side.

Continuing, the valve unit V is accommodated in a valve hole h that forms a part of the third passage P3 in the housing 11, and is installed in the middle of the third passage P3. Further, the valve unit V is removably housed in a cylindrical portion 11b that forms a valve hole h of the housing 11. The valve unit V includes a pressure side damping passage PV1, a pressure side relief passage PV2, a suction passage PV3, and a damping force adjustment passage PV4 connected in parallel in the middle of the third passage P3, and a pressure side damping passage PV1 provided in the pressure side damping passage PV1 and connected from the pressure side chamber R2. A pressure-side damping valve V1 that provides resistance to the flow of liquid toward the tank 4, and a pressure-side damping valve V1 provided in the pressure-side relief passage PV2 and arranged in parallel with the pressure-side damping valve V1, cut off communication between the pressure-side chamber R2 and the tank 4 when the valve is closed, and A pressure-side relief valve V2 is provided in the suction passage PV3, and a pressure-side relief valve V2 opens when the differential pressure between the pressure in the chamber R2 and the pressure in the tank 4 reaches the valve-opening pressure to allow liquid to flow from the pressure-side chamber R2 toward the tank 4. an expansion side check valve V3 which is arranged in parallel with the compression side damping valve V1 and allows only the flow of liquid from the tank 4 toward the pressure side chamber R2; It is provided with a needle valve V4 which provides resistance to the flow of liquid flowing between the tank 4 and the pressure side chamber R2, and which allows the resistance to be adjusted by external operation.

Specifically, the valve unit V includes a cylindrical valve holding shaft 21 inserted into a valve hole h in the housing 11, a needle 22 inserted into the valve holding shaft 21, and a valve holding shaft 21 on the outer periphery of the valve holding shaft 21. The attached valve disk 23, the collar 24 attached to the outer periphery of the valve holding shaft 21, the annular spacer 25, the annular plate 26, and the annular plate 27 fitted to the outer periphery of the collar 24 so as to be movable in the axial direction. , a disc spring 28 which is also arranged on the outer periphery of the collar 24 and biases the spacer 25, annular plate 26 and annular plate 27 toward the valve disk 23 side, and a disc spring 28 which is also arranged on the outer periphery of the collar 24, and a disc spring 28 that attaches the valve disk 23 and the collar 24 to the valve holding shaft 21. It includes a fixing nut 29, a valve body 30 and a spring 31 housed in the needle 22, and a cylindrical case 32 mounted on the inner periphery of the proximal opening of the valve holding shaft 21.

As shown in FIG. 2, the valve holding shaft 21 has a cylindrical shape, and has a large diameter portion 21a having the largest inner and outer diameters at the base end, a small diameter portion 21b having the smallest inner and outer diameters at the tip, the large diameter portion 21a, and the small diameter portion. 21b is provided with a medium diameter portion 21c whose inner and outer diameters are intermediate between the large diameter portion 21a and the small diameter portion 21b. Further, the valve holding shaft 21 includes a flange 21d provided on the outer periphery of the large diameter portion 21a and in the middle in the axial direction, and a hole 21e that communicates between the inside and outside of the medium diameter portion 21c.

Further, the valve holding shaft 21 is provided with an annular groove 21f and a threaded portion 21g on the outer periphery of the large diameter portion 21a and on the distal end side of the flange 21d. It is fixed to the housing 11 by being screwed into the threaded portion 11b1 on the inner periphery. The outer circumferential shape of the large diameter portion 21a on the proximal end side of the flange 21d has a hexagonal shape that allows for gripping of a tool, and the valve holding shaft 21 can be easily screwed to the cylindrical portion 11b by using the tool. .

Further, a seal ring 21i is attached to the outer periphery of the annular groove 21f of the large diameter portion 21a, and when the valve holding shaft 21 is inserted into the cylindrical portion 11b, the seal ring 21i comes into close contact with the inner periphery of the cylindrical portion 11b. Thus, a seal is established between the valve holding shaft 21 and the cylindrical portion 11b. A valve disc 23 that fits into the inner circumference of the cylindrical portion 11b is attached to the outer periphery of the small diameter portion 21b of the valve holding shaft 21, and the valve holding shaft 21 is held in the housing until the flange 21d comes into contact with the end surface of the cylindrical portion 11b. When inserted into the valve hole h formed by the cylindrical portion 11b of 11, the inside of the valve hole h is divided into a chamber A communicating with the pressure side chamber R2 via the port 11a1 and a chamber communicating with the tank 4 via the port 11b2. It is divided into B. The inside of the valve holding shaft 21 communicates with the pressure side chamber R2 via the chamber A in the valve hole h and the port 11a1, and communicates with the liquid chamber in the tank 4 via the hole 21e, the chamber B in the valve hole h, and the port 11b2. It is communicated with L.

Furthermore, the inner periphery of the large diameter portion 21a of the valve holding shaft 21 is reduced in diameter at the tip end, and a threaded portion 21h is provided on the reduced diameter inner periphery. A stepped portion is formed on the inner peripheral side of the valve holding shaft 21 at the boundary between the medium diameter portion 21c and the small diameter portion 21b. In this way, the stepped portion formed on the inner periphery of the valve holding shaft 21 forms the annular valve seat 33 in the needle valve V4.

The needle 22 includes a head 22a and an operation barrel 22b connected to the head 22a, and is inserted into the valve holding shaft 21 so as to be movable in the axial direction, that is, in the left-right direction in FIG.

The head 22a has a cylindrical shape, and includes a needle portion 22a1 that is provided on the outer periphery of the tip at the right end in FIG. The flange 22a2 is provided with a flange 22a2 that can be moved to and from the seat. The needle portion 22a1 has a shape that becomes tapered toward the tip, and can be inserted into the small diameter portion 21b of the valve holding shaft 21. Further, the outer diameter of the proximal end of the needle portion 22a1 is slightly smaller than the inner diameter of the annular valve seat 33, and when the needle 22 moves in the axial direction within the valve holding shaft 21, the needle portion 22a1 and the annular valve The size of the flow path area formed by the gap between the inner edge of the seat 33 and the inner edge of the seat 33 can be adjusted. In this way, the needle 22 and the annular valve seat 33 form a needle valve V4 within the valve holding shaft 21 that communicates the pressure side chamber R2 and the tank 4. By adjusting the axial position relative to 21, the flow area of the damping force adjustment passage PV4 formed within the valve holding shaft 21 can be adjusted in size.

Further, the flange 22a2 faces the annular valve seat 33 in the axial direction, and when the needle 22 moves to the right side in FIG. Communication between the inside of the small diameter portion 21b and the inside of the medium diameter portion 21c of the valve holding shaft 21 can be cut off. On the contrary, when the flange 22a2 is spaced apart from the annular valve seat 33, the inside of the small diameter part 21b and the inside of the medium diameter part 21c of the valve holding shaft 21 communicate with each other.

The operating tube 22b has a cylindrical shape with a bottom and includes a cylindrical portion 22b1 and a bottom portion 22b2 having a larger outer diameter than the cylindrical portion 22b1. groove 22b3, and a through hole 22b4 that is formed in the side of the cylindrical portion 22b1 and communicates between the inside and outside of the cylindrical portion 22b1. A rear end 22a3 of the head 22a on the rear side than the flange 22a2 is press-fitted into the cylindrical portion 22b1 of the operating barrel 22b, so that the operating barrel 22b and the head 22a are integrally connected.

The bottom portion 22b2 of the operating barrel 22b has a blind hole 22b5 that opens from the side, and a threaded portion 21h formed on the inner periphery of the large diameter portion 21a of the valve holding shaft 21 on the outer periphery and on the distal end side of the blind hole 22b5. A screw portion 22b6 for screwing is provided. Further, a seal ring 22b7 is attached to the outer periphery of the cylinder portion 22b1 of the operation cylinder 22b.

Then, the needle 22 is inserted into the valve holding shaft 21 and is attached to the valve holding shaft 21 by screwing the threaded portion 22b6 onto the threaded portion 21h. When the needle 22 is inserted into the valve holding shaft 21, the seal ring 22b7 comes into sliding contact with the inner periphery of the middle diameter portion 21c of the valve holding shaft 21, and the space between the needle 22 and the valve holding shaft 21 is sealed.

In addition, since the threaded part 22b6 of the needle 22 is screwed into the threaded part 21h, when a driver (not shown) is inserted into the groove 22b3 at the rear end of the operation tube 22b and the needle 22 is rotated, the needle 22 will hold the valve. It moves within the shaft 21 in the axial direction, which is the left-right direction in FIG.

When the needle 22 is accommodated in the valve holding shaft 21 as described above, an annular gap is formed between the outer circumference of the bottom portion 22b2 of the operating barrel 22b of the needle 22 and the inner circumference of the large diameter portion 21a of the valve holding shaft 21. Ru. After inserting the needle 22 into the valve holding shaft 21, when the case 32 is press-fitted into the inner circumference of the large diameter portion 21a of the valve holding shaft 21, the bottom 22b2 of the operation tube 22b and the large diameter portion 21a of the valve holding shaft 21 are connected to each other. The gap between the two is closed. The case 32 is cylindrical and allows the rear end of the bottom 22b2 of the operating barrel 22b to be inserted through the case 32, so that it does not interfere with insertion of the screwdriver into the groove 22b3 in the operating barrel 22b, and the needle relative to the valve holding shaft 21 does not get in the way. 22 is also allowed to move in the axial direction.

The case 32 is provided with grooves 32a along the axial direction at equal intervals in the circumferential direction on the right end side in FIG. 2, which is the tip side of the inner circumference. When the case 32 is press-fitted into the large diameter portion 21a of the valve holding shaft 21 and fixed, the groove 32a faces the blind hole 22b5 of the operation tube 22b. A ball 34 and a spring 35 that biases the ball 34 in a direction to push the ball 34 out of the blind hole 22b5 are inserted into the blind hole 22b5. The case 32, the ball 34, and the spring 35 form a detent mechanism, and when the ball 34 enters the groove 32a oppositely, the valve holding shaft 21 of the needle 22 is rotated as long as the needle 22 is not rotated with a torque greater than the detent torque. rotation in the circumferential direction can be restricted. Since the positional relationship between the needle 22 and the annular valve seat 33 is maintained by the detent mechanism in this way, it is possible to prevent the flow path area of the needle valve V4 from changing arbitrarily while the straddle-type vehicle is running.

Further, a valve body 30 and a spring 31 are housed within the needle 22 . Specifically, the valve body 30 is a spherical body, and the annular rear end of the head 22a of the needle 22 serves as a relief valve valve seat 36, and the valve body 30 is relieved by moving in the axial direction within the cylindrical portion 22b1 of the operation cylinder 22b. The valve seat 36 can be moved into and out of the valve seat 36. Further, a spring 31, which is a coil spring, is interposed between the valve body 30 and the bottom portion 22b2 of the operating cylinder 22b, and biases the valve body 30 toward the relief valve seat 36.

The diameter of the valve body 30 is larger than the inner peripheral diameter of the rear end of the head 22a, and when seated on the relief valve seat 36, it cuts off communication between the inside of the needle part 22a1 and the inside of the operation cylinder 22b. When separated from the relief valve seat 36, the inside of the needle portion 22a1 and the inside of the operating cylinder 22b are communicated with each other.

Since the cylindrical portion 22b1 of the operating barrel 22b of the needle 22 is provided with a through hole 22b4, the inside of the operating barrel 22b communicates with the inside of the medium diameter portion 21c of the valve holding shaft 21 through the through hole 22b4. The inside of the medium diameter portion 21c of the valve holding shaft 21 is communicated with the tank 4 via the hole 21e and the chamber B, so the inside of the operating cylinder 22b is communicated with the tank 4. Further, the inside of the operation cylinder 22b communicates with the inside of the small diameter portion 21b of the valve holding shaft 21 through the inside of the head 22a of the needle 22. The inside of the small diameter portion 21b of the valve holding shaft 21 is communicated with the pressure side chamber R2 via the chamber A and the port 11a1, so the inside of the operating cylinder 22b is also communicated with the pressure side chamber R2. In this way, the inside of the needle 22 forms a pressure side relief passage PV2 arranged in parallel with the damping force adjustment passage PV4 formed within the valve holding shaft 21, and the valve body 30 and the spring are arranged in the pressure side relief passage PV2. 31 and a relief valve seat 36 are provided.

The pressure side relief valve V2 is in a closed state in which the valve body 30 continues to contact the relief valve seat 36 by the spring 31 until the differential pressure between the pressure in the pressure side chamber R2 and the pressure in the tank 4 reaches the valve opening pressure. maintained. In addition, in the pressure side relief valve V2, when the differential pressure between the pressure in the pressure side chamber R2 and the pressure in the tank 4 becomes the valve opening pressure, the valve body 30 is pushed by the pressure in the pressure side chamber R2 and compresses the spring 31. The relief valve is separated from the valve seat 36 to open the pressure side relief passage PV2. The opening pressure at which the pressure side relief valve V2 opens is set to be lower than the maximum pressure that the seal member 8 that seals the outer periphery of the piston rod 3 can withstand.

Note that when the needle valve V4 is abolished, the rear end of the valve holding shaft 21 is closed with a cap instead of the needle 22, and the valve body 30 and the spring 31 disposed between the valve body 30 and the cap are closed. The pressure side relief valve V2 may be constructed by housing it in the valve holding shaft 21 and using the stepped portion between the small diameter portion 21b and the medium diameter portion 21c as a relief valve seat.

On the outer periphery of the small diameter portion 21b of the valve holding shaft 21, a nut is screwed into which the valve disc 23 and the collar 24 are screwed onto the stepped portion on the outer periphery of the small diameter portion 21b and the medium diameter portion 21c and the outer periphery of the tip of the small diameter portion 21b. 29 and fixed. Furthermore, an annular spacer 25 , an annular plate 26 , an annular plate 27 , and an annular disc spring 28 are fitted around the outer periphery of the collar 24 .

The valve disk 23 is annular and has a plurality of ports 23a arranged on the same circumference and passing through the wall thickness of the valve disk 23 in the axial direction, and a plurality of ports 23a provided at the right end in FIG. 2 and communicating with each port 23a. An annular window 23b formed by an annular recess, an annular valve seat 23c that protrudes in the axial direction from the right end in FIG. A seal ring 23e is attached thereto. As described above, when the valve disc 23 is attached to the outer periphery of the small diameter portion 21b of the valve holding shaft 21 and inserted into the valve hole h, it fits into the inner periphery of the cylindrical portion 11b and moves inside the valve hole h. It is divided into room A and room B. The seal ring 23e provided on the outer periphery of the valve disc 23 is in close contact with the inner periphery of the cylindrical part 11b to seal between the valve disc 23 and the cylindrical part 11b. This prevents chambers A and B from communicating through the tube.

The port 23a communicates the chamber A communicating with the pressure side chamber R2 and the chamber B communicating with the tank 4, and functions as the pressure side damping passage PV1 and the suction passage PV3 in the shock absorber D of this embodiment.

The collar 24 has a cylindrical shape, and includes a fitting cylindrical portion 24a in which a spacer 25, an annular plate 26, an annular plate 27, and an annular disc spring 28 are fitted on the outer periphery of the fitting cylindrical portion 24a. The fitting cylinder 24a has a flange 24b provided at the right end, and is stacked on the valve disk 23 with the left end in FIG. 2 of the fitting cylinder portion 24a in contact with the inner periphery of the right end in FIG.

As described above, the valve disk 23 and the collar 24 are sandwiched between the stepped portion on the outer periphery of the valve holding shaft 21 and the nut 29 in an overlapping state, and are immovably fixed to the valve holding shaft 21.

The spacer 25 is a small-diameter annular plate, and is slidably fitted to the outer periphery of the fitting cylindrical portion 24a of the collar 24, and is movable in the axial direction relative to the valve disc 23. 23 can be viewed from near and far. Note that the outer diameter of the spacer 25 is small so as not to block the port 23a.

The annular plate 26 is an annular plate that is slidably fitted to the outer periphery of the fitting cylindrical portion 24a of the collar 24 and stacked on the spacer 25 on the side opposite to the valve disk. It can move in the axial direction relative to the valve disk 23, and can move near and far from the valve disk 23. Note that the outer diameter of the annular plate 26 is smaller than the inner diameter of the valve seat 23c, and since the annular window 23b is provided in the valve disc 23, deflection toward the outer peripheral side of the valve disc 23 is allowed. .

The annular plate 27 is an annular plate that is slidably fitted to the outer periphery of the fitting cylindrical portion 24a of the collar 24 and stacked on the annular plate 26 on the side opposite to the valve disk. It can move in the axial direction relative to the valve disk 23, and can move near and far from the valve disk 23. The outer diameter of the annular plate 27 is slightly larger than the outer diameter of the valve seat 23c so that it can be moved into and out of the valve seat 23c of the valve disc 23. Further, the annular plate 27 includes a plurality of holes 27a arranged on the same circumference and passing through the annular plate 27 in the axial direction. The diameter of the circumscribed circle of each hole 27a is less than the diameter of the annular plate 26, and when the annular plate 26 is in contact with the annular plate 27, the hole 27a in the annular plate 27 is closed, and the outer circumference of the annular plate 26 is closed. When the valve is bent toward the valve disk 23 and separated from the annular plate 27, the hole 27a is opened. Therefore, when the annular plate 27 is seated on the valve seat 23c with the annular plate 26 in contact with the annular plate 27, the port 23a is closed and the communication between the chambers A and B is cut off. Even when seated on the seat 23c, when the annular plate 26 bends toward the valve disk 23 and separates from the annular plate 27, the hole 27a is opened and the chambers A and B are communicated with each other. Further, when the outer periphery of the annular plate 27 bends toward the side opposite to the valve disk, or when the annular plate 27 moves on the collar 24 in a direction away from the valve disk 23, the port 23a is opened and the chambers A and B are communicated with each other. Ru.

The disc spring 28 is fitted onto the outer periphery of the fitting cylindrical portion 24a of the collar 24, and is interposed between the flange 24b and the annular plate 27 in a state in which initial deflection is applied, and the spacer is always provided. 25, the annular plate 26 and the annular plate 27 are urged toward the valve disk 23 side.

With respect to the flow of liquid passing through the port 23a from the pressure side chamber R2 toward the tank 4, the annular plate 27 is seated on the valve seat 23c under the pressure of the pressure side chamber R2 and the biasing force of the disc spring 28, and the port is closed. However, the annular plate 26 receives the pressure of the pressure side chamber R2 through the hole 27a, bends around the outer edge of the spacer 25 as a fulcrum, and separates from the annular plate 27 to open the port 23a, allowing the tank to flow from the pressure side chamber R2. It allows the liquid to flow towards the 4th direction and provides resistance to this liquid flow. Note that the spacer 25 determines the fulcrum of deflection of the annular plate 26, and by setting the outer diameter of the spacer 25, the amount of resistance that the annular plate 26 gives to the flow of liquid can be adjusted. In this way, the annular plate 26 functions as a valve body in the compression side damping valve V1, the annular plate 27 functions as a valve seat, and the annular plate 26 and the annular plate 27 form the compression side damping valve V1. ing. Note that when the inner periphery of the annular plate 26 is directly supported by the valve disk 23, the spacer 25 may be omitted, or a plurality of annular plates may be stacked to form the valve body of the compression side damping valve V1. Good too.

On the other hand, with respect to the flow of liquid passing through the port 23a from the tank 4 toward the pressure side chamber R2, the annular plate 27 bends under the pressure of the tank 4 and separates from the valve seat 23c, or is moved by a disc spring. 28 is compressed to separate it from the valve disk 23 and open the port 23a, allowing the liquid to flow from the tank 4 toward the pressure side chamber R2 without providing much resistance. In this case, the annular plate 26 receives pressure from the tank 4 side, comes into contact with the annular plate 27, and bends together with the annular plate 27, or moves on the collar 24 and moves away from the valve disk 23. In this way, the annular plate 26 and the annular plate 27 function as a valve body in the expansion side check valve V3, and the valve disc 23 functions as a valve seat in the expansion side check valve V3. 26, annular plate 27, disc spring 28, and collar 24 form an expansion side check valve V3.

Further, in this embodiment, the compression side damping valve V1 and the expansion side check valve V3 are arranged in parallel at the port 23a of the valve disk 23, and the port 23a allows the flow of liquid from the pressure side chamber R2 toward the tank 4. The pressure side damping passage PV1 functions as a suction passage PV3 that allows liquid to flow from the tank 4 toward the pressure side chamber R2.

In addition, the valve disk 23 is provided with a port corresponding to the pressure side damping passage PV1, a port corresponding to the suction passage PV3, a pressure side damping valve V1 for opening and closing the port corresponding to the pressure side damping passage PV1, and a port corresponding to the suction passage PV3. You may provide the expansion side check valve V3 which opens and closes the port corresponding to .

The pressure side damping valve V1 is configured as described above, but it may be any valve that can provide resistance to the flow of liquid from the pressure side chamber R2 toward the tank 4 and generate a damping force when the shock absorber D is contracted. Therefore, the design of the valve structure can be changed as appropriate to that extent.

Furthermore, although the expansion side check valve V3 is configured as described above, it may be any valve that can only allow the flow of liquid from the tank 4 toward the pressure side chamber R2, so the structure of the valve can be appropriately designed to that extent. Can be changed.

Note that valves having the same configuration as the compression side damping valve V1 and the expansion side check valve V3 may be used as the expansion side damping valve 5 and the compression side check valve 6 in the piston 2.

The specifically configured valve unit V includes a compression side damping passage PV1, a compression side relief passage PV2, a suction passage PV3, and a damping force adjustment passage PV4 that are arranged in parallel with each other, and includes a compression side damping valve V1, a compression side relief valve V2, and a rebound side check. A valve V3 and a needle valve V4 are provided in parallel. Therefore, when the valve unit V is inserted into the valve hole h of the housing 11, the compression side damping valve V1, the compression side relief valve V2, the rebound side check valve V3, and the needle valve V4 can be installed in parallel with each other in the middle of the third passage P3. .

An example of how to assemble the valve unit V configured as described above will be described below. First, the disc spring 28, the annular plate 27, the annular plate 26, and the spacer 25 are fitted to the outer periphery of the fitting cylindrical part 24a of the collar 24 in this order. and assemble. Next, the valve disc 23 and the collar 24, on which the disc spring 28, the annular plate 27, the annular plate 26, and the spacer 25 are assembled, are fitted in order onto the outer periphery of the small diameter portion 21b of the valve holding shaft 21. After attaching, the nut 29 is screwed onto the outer periphery of the tip of the small diameter portion 21b. Then, the valve disk 23 and the collar 24, to which the disc spring 28, the annular plate 27, the annular plate 26, and the spacer 25 are assembled, are fixed to the outer periphery of the small diameter portion 21b of the valve holding shaft 21 by nuts 29.

Next, the spring 31 and the valve body 30 are sequentially inserted into the operating barrel 22b of the needle 22, and the rear end 22a3 of the head 22a is press-fitted into the open end of the operating barrel 22b. and assemble the pressure side relief valve V2 and needle 22. Continuing, after inserting the spring 35 and the ball 34 in order into the blind hole 22b5 opened on the side of the bottom 22b2 of the operation tube 22b of the needle 22, while inserting the needle 22 into the valve holding shaft 21, The threaded portion 22b6 on the outer periphery of the bottom portion 22b2 is screwed into the threaded portion 21h of the valve holding shaft 21.

When the needle 22 is screwed and housed in the valve holding shaft 21, the groove 32a side is inserted into the annular gap between the inner periphery of the large diameter portion 21a of the valve holding shaft 21 and the outer periphery of the operating barrel 22b. 21, and press-fit the case 32 to the inner periphery of the large diameter portion 21a. Then, the case 32 is fixed to the valve holding shaft 21 and prevents the needle 22 from coming off from the valve holding shaft 21.

In this way, when the valve disc 23, collar 24, spacer 25, annular plate 26, annular plate 27, disc spring 28, needle 22 housing the pressure side relief valve V2, and case 32 are assembled to the valve holding shaft 21, Assembly of valve unit V is completed. The completed valve unit V is one unit including a compression side damping valve V1, a compression side relief valve V2, a rebound side check valve V3, and a needle valve V4. The valve unit V is inserted into the cylindrical portion 11b of the housing 11, and is inserted into the valve hole h by screwing the threaded portion 11b1 with the threaded portion 21g on the outer periphery of the large diameter portion 21a of the valve holding shaft 21. and is fixed to the housing 11. Since the valve unit V is screwed to the housing 11, it can be easily attached to and removed from the housing 11. Note that any fastening means other than screw fastening may be used as long as the fastening means allows the valve unit V to be attached to and removed from the housing 11.

The buffer D is configured as described above, and its operation will be explained below. In the extension stroke of the shock absorber D in which the piston 2 moves downward in FIG. 1 relative to the cylinder 1, liquid moves from the expansion side chamber R1 compressed by the piston 2 to the compression side chamber R2 via the first passage P1. In this extension stroke, the expansion-side damping valve 5 provides resistance to the flow of liquid passing through the first passage P1, and the shock absorber D generates an expansion-side damping force that prevents the expansion.

In addition, in the extension stroke of the shock absorber D, the piston rod 3 withdraws from the cylinder 1, so there is a shortage of liquid in the pressure side chamber R2 by the volume of the piston rod 3 withdrawn from the cylinder 1. , the diaphragm 12 expands to expand the air chamber G, and the liquid is supplied from the liquid chamber L of the tank 4 to the pressure side chamber R2 via the expansion side check valve V3. Specifically, the annular plate 27 is separated from the valve seat 23c in response to the pressure of the tank 4, and the expansion side check valve V3 is opened, so that the liquid passes through the port 23a and moves from the tank 4 to the pressure side chamber R2. .

On the other hand, in the contraction stroke of the shock absorber D in which the piston 2 moves upward in FIG. It moves to the expansion side chamber R1 via the passage P2. In addition, during the contraction stroke of the shock absorber D, the piston rod 3 enters into the cylinder 1, so there is an excess of liquid in the cylinder 1 corresponding to the volume of the piston rod 3 entering into the cylinder 1. The liquid is discharged to the liquid chamber L in the tank 4 via the pressure side damping valve V1, and the diaphragm 12 contracts to reduce the air chamber G. In this manner, during the contraction stroke of the buffer D, the pressure side damping valve V1 and the needle valve V4 provide resistance to the flow of liquid from the pressure side chamber R2 toward the tank 4. Therefore, in the contraction stroke of the shock absorber D, the second passage P2 is opened, so that the expansion side chamber R1 and the compression side chamber R2 in the cylinder 1 are in communication with each other, and the compression side damping valve V1 and the needle valve V4 are connected to each other from the compression side chamber R2. Provides resistance to the flow of liquid towards tank 4. Therefore, in the contraction stroke of the shock absorber D, the pressures in both the expansion side chamber R1 and the pressure side chamber R2 increase to become approximately the same pressure. In the shock absorber D of this embodiment, the area of the piston 2 facing the expansion side chamber R1 is smaller than the area of the piston 2 facing the compression side chamber R2 by the area of the piston rod 3, so that the shock absorber D performs a contraction operation. The shock absorber D exerts a damping force equal to the pressure inside the cylinder 1 multiplied by the area of the piston rod 3 in a direction that prevents the contraction operation. That is, in the case of the shock absorber D set as a single rod type in which the piston rod 3 is present only on one side of the piston 2 described above, a damping force proportional to the cross-sectional area of the piston rod 3 is generated during the contraction operation.

In the shock absorber D of this embodiment, the valve unit V includes the needle valve V4, and the resistance that the needle valve V4 gives to the flow of liquid can be changed by adjusting the flow path area in the needle valve V4. The damping force on the compression side of the shock absorber D can be adjusted.

Further, in the contraction stroke of the shock absorber D, when the differential pressure between the pressure in the pressure side chamber R2 and the pressure in the tank 4 reaches the opening pressure of the pressure side relief valve V2, the ball 34 retreats from the relief valve seat 36. Since the pressure side relief valve V2 opens, the pressure side chamber R2 and the tank 4 are communicated with each other through the pressure side relief passage PV2. By opening the pressure side relief passage PV2, the liquid in the cylinder 1 escapes to the tank 4, and the pressure in the cylinder 1 is adjusted so as not to exceed the opening pressure of the pressure side relief valve V2.

Here, in a shock absorber used in a relatively lightweight straddle-type vehicle, the outer diameter of the piston rod may be made thinner because there is no problem in terms of strength and the weight of the shock absorber can be reduced. The damping force generated when the shock absorber is retracted is proportional to the cross-sectional area of the piston rod 3, as described above. Therefore, if such a shock absorber is to exhibit a large damping force during contraction while reducing the outer diameter of the piston rod, it is necessary to increase the pressure inside the cylinder. In order to make the pressure inside the cylinder high during contraction, it is sufficient to increase the resistance that the pressure-side damping valve V1 gives to the flow of liquid. However, if the shock absorber D is contracted at high speed during contraction, the pressure inside the cylinder will increase. may become so large that it exceeds the withstand pressure of the seal member that seals the outer periphery of the piston rod. However, in the shock absorber D of this embodiment, as described above, the valve unit V includes the pressure side relief valve V2 arranged in parallel with the pressure side damping valve V1. Therefore, even if the contraction speed of the shock absorber D becomes high during the contraction operation of the shock absorber D, it is possible to prevent the pressure side relief valve V2 from opening and the pressure inside the cylinder 1 to become excessive, and to prevent the pressure inside the piston rod 3 from becoming excessive. It is possible to protect the seal member 8 that seals the outer periphery and prevent liquid from leaking between the piston rod 3 and the seal member 8.

Further, when the valve unit V is removed from the housing 11 and the opening of the cylindrical portion 11b is closed with a cap (not shown), the shock absorber D generates a damping force only when it is extended and is contracted. No damping force is generated during operation. In this way, by attaching the valve unit V, the shock absorber D can exert damping force both during the extension operation and during the contraction operation, but if the valve unit V is removed from the shock absorber D, the damping force will be exerted only during the extension operation. It acts as a buffer that generates force.

As described above, the shock absorber D of the present embodiment includes a cylinder 1, a piston 2 that is movably inserted into the cylinder 1 and divides the cylinder 1 into a growth side chamber R1 and a compression side chamber R2 filled with liquid. A piston rod 3 movably inserted into the cylinder 1 and connected to the piston 2, a tank 4 for storing liquid, and a first passage P1 and a first passage P1 that communicate in parallel with the expansion side chamber R1 and the compression side chamber R2, respectively. A second passage P2, a third passage P3 that communicates the compression side chamber R2 and the tank 4, and a growth side damping valve that is provided in the first passage P1 and provides resistance to the flow of liquid from the growth side chamber R1 to the compression side chamber R2. 5, a pressure side check valve 6 provided in the second passage P2 and allowing only the flow of liquid from the compression side chamber R2 toward the expansion side chamber R1, and a valve unit V detachably provided in the middle of the third passage P3. The valve unit V includes a pressure side damping valve V1 that provides resistance to the flow of liquid from the pressure side chamber R2 toward the tank 4, and a pressure side damping valve V1 that is arranged in parallel with the pressure side damping valve V1 to communicate between the pressure side chamber R2 and the tank 4 when the valve is closed. and a pressure side relief valve V2 that opens when the pressure difference between the pressure in the pressure side chamber R2 and the pressure in the tank 4 reaches the valve opening pressure and allows the flow of liquid from the pressure side chamber R2 toward the tank 4, and a pressure side damping valve. The expansion side check valve V3 is arranged in parallel with the valve V1 and allows only the flow of liquid from the tank 4 toward the pressure side chamber R2.

In the shock absorber D configured in this way, a valve unit V including a pressure side damping valve V1, a pressure side relief valve V2, and a growth side check valve V3 in parallel has a third passage P3 that communicates between the pressure side chamber R2 and the tank 4. Since it is removably installed in the middle of the valve unit, just by attaching the valve unit V, a shock absorber that exerts damping force only during extension operation can be used as a shock absorber that exerts damping force not only during extension operation but also during contraction operation. Can function. Moreover, if the valve unit V is removed, the shock absorber D can be used as a shock absorber that exerts damping force only during the extension operation.

Depending on the presence or absence of the valve unit V, the shock absorber D can be set to either a shock absorber that generates damping force during both extension and contraction operations, or a shock absorber that generates damping force only during extension operation. can. The manufacturer of the shock absorber D can assemble the shock absorbers D other than the valve unit V using the same parts on the same line, and can manufacture the shock absorber D by determining the presence or absence of the valve unit V according to the user's request. Therefore, the manufacturer can reduce the manufacturing cost of the buffer D.

Therefore, according to the shock absorber D configured as described above, the function of exerting a damping force during the contraction operation can be easily added to the shock absorber which is not equipped with a compression side damping valve. Furthermore, since the manufacturer of the shock absorber D can assemble the shock absorbers D other than the valve unit V using the same parts on the same line, the manufacturing cost of the shock absorber D at the manufacturer can also be reduced.

Furthermore, according to the shock absorber D configured as described above, since the valve unit V is provided with the pressure side relief valve V2, even when the shock absorber D is contracted at a high speed when the shock absorber D is in operation to contract. It is possible to prevent the pressure inside the cylinder 1 from becoming excessive.

Further, the shock absorber D of the present embodiment includes a housing 11 that connects the cylinder 1 and the tank 4 and has a third passage P3 and a valve hole h provided in the middle of the third passage P3, and has a valve unit. V is accommodated within the valve hole h. According to the shock absorber D configured in this way, the valve unit V is accommodated in the valve hole h of the housing 11 that connects the cylinder 1 and the tank 4. It is possible to suppress the total length of the buffer D from increasing. Note that the valve hole h is formed by a cylindrical portion 11b arranged along the radial direction of the cylinder 1, and when the opening end faces away from the cylinder, the valve unit V can be attached and detached from the shock absorber D. This can be done easily from the side.

Further, in the shock absorber D of the present embodiment, the valve unit V is arranged in parallel with the pressure side damping valve V1, and is a needle valve that provides resistance to the flow of liquid from the pressure side chamber R2 toward the tank 4 and can adjust the flow path area. Since it is equipped with V4, it is also possible to adjust the damping force during contraction operation.

Further, in the shock absorber D of this embodiment, the needle valve V4 includes an annular valve seat 33 and a needle 22 that can be moved closer to or closer to the annular valve seat 33, and the pressure side relief valve V2 is housed in the needle 22. . According to the shock absorber D configured in this manner, the pressure side relief valve V2 is housed within the needle 22, so that the entire valve unit V can be downsized. In addition, since the pressure side relief valve V2 is accommodated in the needle 22, the opening pressure of the pressure side relief valve V2 can be kept constant regardless of the position of the needle 22.

Furthermore, in the shock absorber D of the present embodiment, the needle 22 has a cylindrical shape and is provided on the outer periphery of the distal end and is insertable into the annular valve seat 33. The head 22a has a flange 22a2 that can be seated on and taken off from the valve seat 33, and the inside and outside communicate with a groove (operation part) 22b3 that has a cylindrical shape with a bottom and is formed in the bottom part 22b2 and that allows operation from the outside. The pressure side relief valve V2 has an operation tube 22b having a through hole 22b4 and connected to the rear of the head 22a, and the pressure side relief valve V2 has an annular rear end 22a3 of the head 22a as an annular relief valve seat 36. A valve body 30 is detachable from the relief valve valve seat 36 and is housed in the operation tube 22b, and a valve body 30 is interposed between the valve body 30 and the operation tube 22b and is housed in the operation tube 22b. It has a spring 31 that biases the body 30 toward the relief valve seat 36, and when the valve body 30 is separated from the relief valve seat 36, the inside of the head 22a and the through hole 22b4 are communicated. .

According to the shock absorber D configured in this way, a space is provided in the head 22a of the needle 22 and a space for accommodating the valve body 30 and the spring 31 in the operating cylinder 22b, so that the head 22a forming the needle 22 can be relieved. By using it as the valve seat 36, the pressure side relief valve V2 can be easily housed within the needle 22. Therefore, according to the shock absorber D configured in this way, the pressure side relief valve V2 and the needle 22 can be further downsized.

Furthermore, the shock absorber D of the present embodiment includes a seal member 8 that comes into sliding contact with the outer circumference of the piston rod 3 to seal the outer circumference of the piston rod 3, and the seal member 8 can withstand the opening pressure of the pressure side relief valve V2. set below the maximum pressure to be obtained. According to the shock absorber D configured in this way, the pressure inside the cylinder 1 does not exceed the maximum pressure that the seal member 8 can withstand. Prevents liquid leakage.

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

DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Cylinder, 3... Piston rod, 4... Tank, 5... Rebound side damping valve, 6... Compression side check valve, 8... Seal member, 22 ...Needle, 22a...Head, 22a1...Needle part, 22a2...Flange, 22a3...Back end of head, 22b...Operation tube, 22b3...Groove (operation part) ), 22b4...Through hole, 30...Valve body, 31...Spring, 33...Annular valve seat, 36...Relief valve seat, D...Buffer, h... Valve hole, P1...first passage, P2...second passage, P3...third passage, R1...growth side chamber, R2...compression side chamber, V...valve unit, V1... ...Valve unit, V2...Compression side relief valve, V3...Rebound side check valve, V4...Needle valve

Claims (6)

cylinder and
a piston that is movably inserted into the cylinder and divides the cylinder into a growth side chamber and a pressure side chamber filled with liquid;
a piston rod movably inserted into the cylinder and connected to the piston;
A tank for storing liquid,
a first passage and a second passage that connect the expansion side chamber and the compression side chamber in parallel, respectively;
a third passage communicating the pressure side chamber and the tank;
a growth-side damping valve that is provided in the first passage and provides resistance to the flow of liquid from the growth-side chamber toward the compression-side chamber;
a pressure side check valve that is provided in the second passage and allows only the flow of liquid from the pressure side chamber toward the expansion side chamber;
and a valve unit removably provided in the middle of the third passage,
The valve unit includes:
a pressure-side damping valve that provides resistance to the flow of liquid from the pressure-side chamber toward the tank;
A valve is arranged in parallel with the pressure side damping valve to cut off communication between the pressure side chamber and the tank when the valve is closed, and to open the valve when the differential pressure between the pressure in the pressure side chamber and the pressure in the tank reaches a valve opening pressure. a pressure side relief valve that allows liquid to flow from the pressure side chamber toward the tank;
A buffer comprising: a rebound check valve that is arranged in parallel with the pressure damping valve and allows only the flow of liquid from the tank to the pressure chamber. A housing that connects the cylinder and the tank and has the third passage and a valve hole provided in the middle of the third passage,
The shock absorber according to claim 1, wherein the valve unit is housed within the valve hole. The valve unit includes:
The shock absorber according to claim 1, further comprising a needle valve arranged in parallel with the pressure side damping valve to provide resistance to the flow of liquid from the pressure side chamber to the tank and to be able to adjust a flow path area. The needle valve has an annular valve seat and a needle that can move toward and away from the annular valve seat,
The shock absorber according to claim 3, wherein the pressure side relief valve is housed within the needle. The needle is
A head having a cylindrical shape and having a needle portion provided on the outer periphery of the tip and capable of being inserted into the inside of the annular valve seat, and a flange provided at an intermediate portion of the outer periphery and capable of being seated on and off the annular valve seat; ,
An operation tube that is shaped like a cylinder with a bottom and is connected to the rear of the head, and includes an operation section formed at the bottom that allows operation from the outside, and a through hole that communicates between the inside and outside. have,
The pressure side relief valve has an annular rear end of the head as an annular relief valve seat, a valve body that can be attached to and detached from the relief valve seat and is housed in the operation cylinder, and the valve body. and a spring that is interposed between the operating cylinder and the operating cylinder and is housed in the operating cylinder and urges the valve body toward the relief valve seat, and the valve body is connected to the relief valve valve. The shock absorber according to claim 4, wherein when the shock absorber is separated from the seat, the inside of the head and the through hole are communicated with each other. a sealing member that slides on the outer periphery of the piston rod to seal the outer periphery of the piston rod;
The shock absorber according to any one of claims 1 to 5, wherein the opening pressure of the pressure side relief valve is set to be less than a maximum pressure that the sealing member can withstand.