Accumulator and cylinder device

Abstract

To provide an accumulator capable of realizing characteristics of improving pressurization force in the middle of compression in a gas chamber without increasing a pressure in the gas chamber, and a cylinder device suitable for use of the accumulator.SOLUTION: An accumulator 10 of the present invention comprises: a hollow housing 11; a partition member 14 that is housed in the housing 11, divides the inside of the housing 11 into an air chamber G and a liquid chamber L, and can move within the housing 11 to change volume distribution between the air chamber G and the liquid chamber L; and an elastic body 15 that is housed in the air chamber G, and suppresses movement of the partition member 14 in a direction of decreasing a volume of the air chamber G when it comes in contact with the partition member 14. The elastic body 15 is separated from the partition member 14 when the partition member 14 maximizes the volume of the air chamber G, and comes in contact with the partition member 14 before the partition member 14 minimizes the volume of the air chamber G, to suppress the movement of the partition member 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an accumulator and a cylinder device.

Background Art

[0002] An accumulator is used, for example, in a cylinder device such as a shock absorber or a gas spring, and pressurizes the working chamber in the cylinder device so that an appropriate damping force or spring force can be obtained when the cylinder device expands and contracts.

[0003] Such an accumulator is configured, for example, to include a housing and a free piston that is slidably inserted into the housing and divides the inside of the housing into a liquid chamber and a gas chamber (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional accumulator, the smaller the volume of the gas chamber, the greater the pressure in the gas chamber, and the liquid chamber can be pressurized with a large pressure. However, when the conventional accumulator is used in a cylinder device such as a shock absorber, when the cylinder device moves to the stroke end, in order to decelerate the moving speed of the cylinder device to the stroke end by the gas reaction force of the accumulator without using a system such as a cushion or a hydraulic lock, it is necessary to set the pressure in the gas chamber to a high pressure in advance.

[0006] However, if this is done, it becomes difficult to seal the inside of the gas chamber, and the tightening force of the seal around the rod of the cylinder device must be increased, which hinders the smooth expansion and contraction of the cylinder device.

[0007] Thus, in a conventional accumulator, in order to obtain a pressing force capable of reducing the moving speed to the stroke end of a cylinder device or the like, it is necessary to previously enclose gas at a high pressure, but this causes a problem of adversely affecting the operation of the cylinder device.

[0008] Therefore, an object of the present invention is to provide an accumulator capable of realizing a characteristic that the pressing force increases during the compression of the air chamber without increasing the pressure in the air chamber, and a cylinder device suitable for using the accumulator.

Means for Solving the Problems

[0009] To solve the above problems, the accumulator of the present invention includes a hollow housing, a partition member that is housed in the housing, partitions the inside of the housing into an air chamber and a liquid chamber, and can move inside the housing to change the volume distribution between the air chamber and the liquid chamber, and an elastic body that is housed in the air chamber and abuts against the partition member to suppress the movement of the partition member in the direction of decreasing the volume of the air chamber of the partition member. The elastic body is separated from the partition member when the partition member maximizes the volume of the air chamber, and abuts against the partition member before the partition member minimizes the volume of the air chamber to suppress the movement of the partition member.

[0010] According to the accumulator configured as described above, when the partition member is displaced from the position where the volume of the air chamber is maximized in the direction of compressing the air chamber, the elastic body is compressed on the way, and the elastic force of the elastic body is added to the reaction force of the gas in the air chamber to increase the pressing force, so that the moving speed of the partition member in the direction of compressing the air chamber can be decelerated. Further, it is not necessary to increase the pressure in the air chamber. Furthermore, since the elastic body is separated from the partition member when the partition member maximizes the volume of the air chamber, the partition member can move smoothly in the situation where the partition member starts to compress the air chamber, so that the elastic body can also exhibit a smooth extension operation advantageously.

[0011] Further, the partition member in the accumulator is a free piston, and the elastic body may be a resin cushion. According to the accumulator configured in this way, since the elastic body is a resin cushion, when the free piston contacts the cushion and then displaces in the compression direction, an eccentric load as in the case where the elastic body is a coil spring does not act on the free piston, and the free piston does not tilt with respect to the housing due to the elastic force received from the cushion. The free piston can smoothly displace with respect to the housing and does not need to generate a pressing force due to uncontrollable stick-slip.

[0012] Furthermore, the elastic body in the accumulator may be formed of urethane foam. According to the accumulator configured in this way, since the elastic body contains innumerable bubbles and occupies a small volume in the air chamber, and the reduction rate of the volume in the air chamber is small, the volume in the air chamber can be secured, and the change in the volume in the air chamber with respect to the displacement of the partition member becomes small. Therefore, it becomes easy to tune the pressure characteristics of the accumulator.

[0013] In addition, the housing in the accumulator has a cylindrical housing body and a cap that closes the opening on the air chamber side of the housing body. The cap includes a lid portion that closes the opening of the housing body and a protruding portion that rises from the lid portion. The elastic body may be cylindrical and fitted to the outer periphery of the protruding portion.

[0014] By fixing the elastic body in the air chamber using the accumulator configured in this way and the valve case, the elastic body can be arranged so as not to interfere with the filling of gas into the air chamber by the air valve, and the air valve and the elastic body can be installed in the narrow accumulator without difficulty.

[0015] Furthermore, the accumulator may include an annular adjusting shim that is sandwiched between the outer periphery of the protruding portion and the lid portion and the elastic body. According to the accumulator configured in this way, it becomes possible to adjust the contact position of the elastic body as the partition member, and since the adjusting shim is fixed using the elastic body, it is not necessary to add parts for fixing the adjusting shim.

[0016] Further, the cylinder device includes a cylinder, a piston that is movably inserted into the cylinder and divides the inside of the cylinder into an extension chamber and a compression chamber, and a rod that is movably inserted into the cylinder and connected to the piston. One of the extension chamber and the compression chamber is open to the atmosphere, and the other is filled with a liquid. The device also includes a telescopic body, an accumulator, a communication passage that communicates the liquid chamber with the other of the extension chamber and the compression chamber, and a valve provided in the communication passage that can open and close the communication passage, and provides resistance to the flow of the liquid in one direction when the valve is opened, and is fully open to the flow of the liquid in the other direction.

[0017] In this way, in the cylinder device, when a spring force can be exerted on either the extension or the contraction of the telescopic body, and when the telescopic body is extended or contracted against the spring force by an external force, the pressure of the accumulator increases greatly in the middle, and the impact at the maximum extension or the maximum contraction can be alleviated without providing other systems such as a cushion or a hydraulic lock mechanism inside the telescopic body. Therefore, the telescopic body can be miniaturized, and the mountability to devices with difficult installation space such as straddle-type vehicles can be improved. Further, in this way, the cylinder device can slow down either the extension or the contraction operation, can give polarity to the operation speed depending on the operating direction, and can suppress the increase in the number of parts and cost.

Advantages of the Invention

[0018] According to the accumulator of the present invention, the characteristic that the pressure increases during the compression of the air chamber without increasing the pressure in the air chamber to a high pressure can be realized. Further, the cylinder device is optimal for the use of the accumulator.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0020] Based on the embodiment shown in the figure, the present invention will be described. As shown in FIG. 1, a cylinder device C including an accumulator 10 in an embodiment includes a telescopic body 1, an accumulator 10, a communication passage 16 that communicates between the inside of the telescopic body 1 and the accumulator 10, and a valve V provided in the communication passage 16.

[0021] As shown in FIG. 2, the telescopic body 1 in the cylinder device C is rotatably connected to a lower end of a shock absorber D interposed between a vehicle body B of a saddle-type vehicle M and a wheel W and the vehicle body B of the saddle-type vehicle M, and is bridged between a swing arm S that is swingable with respect to the vehicle body B of the saddle-type vehicle M and holds the wheel W.

[0022] The shock absorber D is a telescopic shock absorber. Although not shown in detail, it includes a cylinder and a rod that can move in and out of the cylinder. When the rod moves axially relative to the cylinder during expansion and contraction, it exerts a damping force that prevents its own expansion and contraction. The upper end of the shock absorber D is rotatably attached to the vehicle body B in the longitudinal direction of the vehicle body B, and the lower end of the shock absorber D is rotatably attached to the link plate P in the longitudinal direction of the vehicle body B. The link plate P is triangular, and the vicinity of each vertex is hingedly connected to the vehicle body B, the lower end of the shock absorber D, and one end of the telescopic body 1, respectively. Specifically, the front connection point of the link plate P is hingedly connected to the vehicle body B, the rear connection point of the link plate P is hingedly connected to the lower end of the shock absorber D, and the central connection point of the link plate P is hingedly connected to one end of the telescopic body 1. The swing arm S has its front end hingedly connected to the vehicle body B so as to be rotatable in the vertical direction, and rotatably holds the wheel W on the rear end side, and is swingable in the vertical direction with respect to the vehicle body B. Also, the other end of the telescopic body 1 is hingedly connected to the middle part of the swing arm S.

[0023] Therefore, when the telescopic body 1 is in a rod shape and does not expand and contract, when the swing arm S rotates upward in FIG. 2 with respect to the vehicle body B and the wheel W tries to approach the vehicle body B, the link plate P rotates upward with respect to the vehicle body B and compresses the shock absorber D. Thus, the movement of the wheel W relative to the vehicle body B is suppressed by the damping force generated by the shock absorber D. Also, when the telescopic body 1 is in a rod shape and does not expand and contract, when the swing arm S rotates downward in FIG. 2 with respect to the vehicle body B and the wheel W tries to move away from the vehicle body B, the link plate P rotates downward with respect to the vehicle body B and extends the shock absorber D. Thus, the movement of the wheel W relative to the vehicle body B is suppressed by the damping force generated by the shock absorber D. Therefore, the shock absorber D suppresses the relative movement between the wheel W and the vehicle body B due to the vibration input during the running of the saddle-riding type vehicle M, and improves the riding comfort in the vehicle.

[0024] On the contrary, when the telescopic body 1 is extended, the cylinder device C rotates the swing arm S upward in FIG. 2 with the connection point to the vehicle body B as the fulcrum, so that the wheel W approaches the vehicle body B and the vehicle height of the saddle-type vehicle M decreases. When the telescopic body 1 is contracted, the cylinder device C rotates the swing arm S downward in FIG. 2 with the connection point to the vehicle body B as the fulcrum, so that the wheel W moves away from the vehicle body B and the vehicle height of the saddle-type vehicle M increases.

[0025] Hereinafter, the accumulator 10 and the cylinder device C will be described in detail. The telescopic body 1 includes a cylinder 2, a piston 3 that is movably inserted into the cylinder 2 and divides the inside of the cylinder 2 into an extending chamber R1 and a pressure chamber R2, and a rod 4 that is movably inserted into the cylinder 2 and connected to the piston 3.

[0026] As shown in FIG. 1, the cylinder 2 has a bottomed cylindrical shape and includes an eye-type bracket 2b that is hinge-connected to the link plate P at the bottom 2a. An annular rod guide 5 is attached to the open end at the right end in FIG. 1. The piston 3 includes an annular seal ring 3a and an annular piston ring 3b that are in sliding contact with the inner circumference of the cylinder 2 on the outer circumference. The piston 3 divides the inside of the cylinder 2 into an extending chamber R1 and a pressure chamber R2 and can smoothly move in the left-right direction in FIG. 1, which is the axial direction, inside the cylinder 2.

[0027] The rod 4 is inserted through the inner circumference of the rod guide 5 and into the cylinder 2. The left end in FIG. 1, which is the tip, is connected to the piston 3, and the right end in FIG. 1, which is the base end, protrudes outside the cylinder 2. A hole 2c is provided in the cylinder 2 to communicate the pressure chamber R2 on the left side of the piston 3 inside the cylinder 2 to the outside of the cylinder 2, and the pressure chamber R2 is open to the atmosphere. A connection hole 2d for mounting a joint 6 facing the extending chamber R1 is provided on the side portion of the open end side of the cylinder 2.

[0028] The accumulator 10 includes a hollow housing 11, a free piston 14 that is housed within the housing 11, partitions the interior of the housing 11 into an air chamber G and a liquid chamber L, and is movable within the housing 11 to change the volume distribution between the liquid chamber L and the air chamber G, and a cylindrical cushion 15 that is housed within the air chamber G and, when in contact with the free piston 14, suppresses the movement of the free piston 14 in a direction that decreases the volume of the air chamber G.

[0029] The housing 11 includes a bottomed cylindrical housing body 12 having a bottom 12a, and a cap 13 that closes the open end of the housing body 12. The housing body 12 includes a valve hole 12b that penetrates in the vertical direction in FIG. 1, which is a direction perpendicular to the axial direction of the bottom 12a, and a port 12c that communicates the inside of the valve hole 12b with the liquid chamber L. Further, as shown in FIG. 3, the inner diameter of the valve hole 12b is smaller on the lower side, and a stepped portion 12b1 is provided below the port 12c in FIG. 3.

[0030] A joint 18 for connecting the pipe 17 to the housing body 12 is attached to the open end of the lower end of the valve hole 12b. One end of the pipe 17 is connected to the cylinder 2 via a joint 6, and the other end is connected to the accumulator 10 via the joint 18, and communicates the extension chamber R1 with the valve hole 12b. Thus, in the present embodiment, a communication passage 16 that communicates the extension chamber R1 and the liquid chamber L of the accumulator 10 is formed by the pipe 17, the valve hole 12b, and the port 12c.

[0031] The cap 13 includes a bottomed cylindrical lid portion 13a that is screwed to the inner periphery of the right end in FIG. 1, which is the air chamber G side of the housing body 12, and closes the right end in FIG. 1 of the housing body 12, a cylindrical valve case 13b as a protruding portion that rises from the lid portion 13a toward the air chamber G side, and an air valve 13c that is attached to the inner periphery of the valve case 13b and enables injection of gas from the outside into the air chamber G, and closes the open end of the housing body 12.

[0032] The lid portion 13a is provided with a seal ring 13d on its outer periphery and a screw portion 13e provided on the right side in FIG. 1 relative to the seal ring 13d. When the cap 13 is inserted into the inner periphery of the open end of the housing body 12 and screwed to the housing body 12 using the screw portion 13e, the seal ring 13d is brought into close contact with the inner periphery of the housing body 12 to seal the inside of the accumulator 10 and prevent leakage of gas from the inside of the accumulator 10.

[0033] The free piston 14 is provided with a seal ring 14a on its outer periphery and is axially movably accommodated in the housing body 12. The seal ring 14a is in sliding contact with the inner periphery of the housing body 12, partitioning the inside of the housing body 12 into a liquid chamber L and a gas chamber G, and transmitting the pressure in the gas chamber G to the liquid chamber L. When the free piston 14 is displaced in the left-right direction in FIG. 1 within the housing 11, the volume distribution of the gas chamber G and the liquid chamber L within the housing 11 changes. Compressed gas is enclosed in the gas chamber G, and the pressure in the gas chamber G is always equal to or higher than atmospheric pressure. Further, in the accumulator 10 of the present embodiment, the liquid chamber L communicates with the extending chamber R1 of the elastic body 1 via the communication passage 16, the pressure side chamber R2 of the elastic body 1 is open to the atmosphere, and when the liquid chamber L and the extending chamber R1 are placed in a communicating state, the piston 3 is pressed by the pressure in the extending chamber R1 to which the pressure of the liquid chamber L propagates, causing the elastic body 1 to contract to the maximum extent, the pressure side chamber R2 to be compressed to the maximum extent, and the volume of the extending chamber R1 to become the maximum. When the elastic body 1 contracts to the maximum extent in this way, the accumulator 10 discharges the liquid to the outside to the maximum extent, and the free piston 14 is disposed at a position (discharge side stroke end) where the volume of the liquid chamber L becomes the minimum and the volume of the gas chamber G becomes the maximum within the housing 11.

[0034] The cushion 15 is a resin cushion, specifically formed by molding foamed urethane into a cylindrical shape. Further, the cushion 15 is provided with annular recesses along the circumferential direction at two locations on the outer periphery so as to be easily compressed and deformed when receiving an axial load. It is fitted to the outer periphery of the valve case 13b in the cap 13 and is housed in the air chamber G. When the free piston 14 is located at the discharge-side stroke end described above, the cushion 15 is housed in the air chamber G so that the free piston 14 is axially separated from the cushion 15. Then, when the telescopic body 1 extends and the liquid flows from the extension chamber R1 of the telescopic body 1 into the liquid chamber L and the free piston 14 moves in the direction of compressing the air chamber G, the free piston 14 abuts against the cushion 15 before the telescopic body 1 reaches its maximum extension. The cushion 15 is compressed against further movement of the free piston 14 in the direction of compressing the air chamber G, thereby exerting a resilient force that hinders the movement of the free piston 14. In this way, when the free piston 14 is displaced from the discharge-side stroke end in the direction of compressing the air chamber G, the cushion 15 is compressed midway, so that in addition to the pressure of the gas in the air chamber G, the resilient force generated by the cushion 15 acts on the free piston 14. As shown in FIG. 4, the pressure characteristics, which are the characteristics of the force exerted by the accumulator 10 to press the free piston 14 with respect to the displacement of the free piston 14, can be changed midway through the displacement of the free piston 14. In FIG. 4, the displacement when the free piston 4 is at the discharge-side stroke end is set to 0, and the displacement when it abuts against the cushion 15 is set to X, and the pressure characteristics of the accumulator 10 when the free piston 4 is displaced from the discharge-side stroke end in the direction of compressing the air chamber G are shown.

[0035] Since the cushion 15 is formed of foamed urethane, it contains innumerable air bubbles and occupies a small volume in the air chamber G, and the reduction ratio of the volume in the air chamber G is small. Therefore, the volume in the air chamber G can be secured, and the change in the volume in the air chamber G with respect to the displacement of the free piston 14 becomes small, making it easy to tune the pressure characteristics of the accumulator 10.

[0036] In addition, in the present embodiment, the elastic body housed in the air chamber G is the cushion 15, but it may be a spring or the like in addition to the cushion 15. Further, the cushion 15 is formed of foamed urethane, but it may be made of rubber, a synthetic resin rich in elasticity, or the like. Also, in the present embodiment, the partition member is the free piston 14, but it may be a bellows, a diaphragm, or the like.

[0037] Also, in the accumulator 10 of the present embodiment, a plurality of annular adjustment washers 19 are laminated and fitted on the outer periphery of the valve case 13b, and these adjustment washers 19 are sandwiched between the cushion 15 and the lid portion 13a of the cap 13 and fixed on the outer periphery of the valve case 13b. The adjustment washer 19 is provided to adjust the axial position of the cushion 15 with respect to the housing 11, and the position of the left end in FIG. 1, which is the tip of the cushion 15, can be adjusted by the number of laminated adjustment washers 19. The adjustment washer 19 can be omitted if it is not necessary, but the number of installed washers can be arbitrarily changed according to the position where the cushion 15 is to be arranged. Further, instead of adjusting the position of the cushion 15 by the number of the adjustment washers 19, a plurality of adjustment washers with different thicknesses may be prepared, and the position of the cushion 15 may be adjusted by using an adjustment washer with a suitable thickness according to the position of the cushion 15.

[0038] And a valve V is housed in the valve hole 12b in the housing body 12. In the present embodiment, as shown in FIG. 3, the valve V includes a valve seat member 20 housed in the valve hole 12b, a valve body 21 that can be seated and separated from the valve seat member 20, a coil spring 22 as a biasing member that biases the valve body 21 toward the valve seat member 20, a centering member 23 that centers the valve body 21, a push rod 24 that presses the valve body 21 against the biasing force of the coil spring 22 by an external operation to separate the valve body 21 from the valve seat member 20, and an annular nut member 25 that is screwed to the upper end opening of the valve hole 12b in FIG. 3.

[0039] The valve seat member 20 is cylindrical, having a large-diameter portion 20a with a large outer diameter that fits into the valve hole 12b, a small-diameter portion 20b with a small outer diameter on the lower side in FIG. 3 of the large-diameter portion 20a, and a hole 20c that penetrates the large-diameter portion 20a in the radial direction. A valve seat 20d is formed by the annular lower end surface at the lower end of the small-diameter portion 20b, which is one end in the axial direction. Also, on the outer periphery of the large-diameter portion 20a and above the hole 20c in FIG. 3, a sealing ring 20e is mounted to seal between the valve seat member 20 and the housing body 12 by closely contacting the wall surface that forms the valve hole 12b of the housing body 12 when the valve seat member 20 is accommodated in the valve hole 12b.

[0040] The centering member 23 is cylindrical, having a fitting portion 23a that fits on the outer periphery of the small-diameter portion 20b of the valve seat member 20 and also fits into the valve hole 12b, a housing cylinder 23b that extends axially from the lower end in FIG. 3 of the fitting portion 23a and has a smaller outer diameter than the fitting portion 23a and houses the valve body 21 and the coil spring 22 inward, and a centering portion 23c provided in a flange shape from the lower end in FIG. 3 of the housing cylinder 23b to the inner peripheral side.

[0041] The centering member 23 is inserted into the valve hole 12b until the outer periphery of the lower end in FIG. 3 of the fitting portion 23a abuts against the stepped portion 12b1 in the valve hole 12b. The valve seat member 20 fits the small-diameter portion 20b of the valve seat member 20 into the inner periphery of the fitting portion 23a of the centering member 23, and makes the stepped portion at the boundary between the large-diameter portion 20a and the small-diameter portion 20b on the outer periphery abut against the upper end in FIG. 3 of the fitting portion 23a. When accommodated in the valve hole 12b, the port 12c of the housing body 12 and the hole 20c face each other, and the inside of the valve seat member 20 communicates with the liquid chamber L of the accumulator 10.

[0042] The housing cylinder 23b includes a stopper 23b1 which is an annular step portion formed on the inner circumference by making the inner diameter of the lower side in FIG. 3 smaller in the middle, and a hole 23b2 that penetrates in the radial direction on the upper side of the stopper 23b1 in FIG. 3. Further, the outer diameter of the housing cylinder 23b is made smaller than the inner diameter of the lower side in FIG. 3 of the step portion 12b1 of the valve hole 12b. Therefore, when the centering member 23 is housed in the valve hole 12b as described above, an annular gap is formed between the housing cylinder 23b and the wall surface of the valve hole 12b. The inside of the centering member 23 communicates with the liquid chamber L through the inside of the valve seat member 20, and communicates with the extension chamber R1 through the hole 23b2, the valve hole 12b, and the pipe 17.

[0043] The inner diameter of the housing cylinder 23b is slightly smaller than the outer diameter of the small-diameter portion 20b of the valve seat member 20, but can be arbitrarily set as long as it does not prevent the movement of the valve body 21 and the seating and unseating on the valve seat 20d described later.

[0044] The valve body 21 includes a columnar head 21a that can enter and exit the small-diameter portion 20b of the valve seat member 20, an annular seat portion 21b that is continuous with the lower side in FIG. 3 behind the head 21a and can seat and unseat on the valve seat 20d, a columnar spring fitting portion 21c that extends from the lower side in FIG. 3 of the seat portion 21b, and a columnar shaft portion 21d that extends from the lower end in FIG. 3 of the spring fitting portion 21c and has an outer diameter smaller than that of the spring fitting portion 21c and is in sliding contact with the inner circumference of the centering portion 23c of the centering member 23.

[0045] The outer diameter of the head 21a is smaller than the inner diameter of the small-diameter portion 20b. When the valve body 21 inserts the head 21a into the small-diameter portion 20b, a restricted flow path Pr is formed in the annular gap between the outer circumference of the head 21a and the inner circumference of the small-diameter portion 20b.

[0046] The seat portion 21b has a tapered surface whose outer diameter is larger than the outer diameter of the head 21a and the inner diameter of the valve seat 20d, and the outer diameter becomes smaller toward the upper side in FIG. 3, and the tapered surface faces the valve seat 20d. Further, the outer diameter of the seat portion 21b is larger than the inner diameter of the stopper 23b1 of the housing cylinder 23b, and is smaller than the inner diameter of the upper side in FIG. 3 of the stopper 23b1 of the housing cylinder 23b.

[0047] Therefore, with the valve body 21 being accommodated in the accommodation cylinder 23b, it can move in the axial direction which is the vertical direction in FIG. 3. When the seat portion 21b is seated on the valve seat 20d, the tapered surface abuts against the inner peripheral edge of the valve seat 20d and the valve body 21 closes the communication passage 16. Also, when the valve body 21 moves downward in FIG. 3 from the position where the seat portion 21b is seated on the valve seat 20d and the lower end of the seat portion 21b in FIG. 3 abuts against the stopper 23b1, the entire head portion 21a is completely pulled out of the valve seat member 20, and the communication passage 16 is opened to the maximum. In this state, since the head portion 21a of the valve body 21 has completely come out of the small-diameter portion 20b, a restricted flow path Pr is not formed between the valve body 21 and the valve seat member 20, and the valve V does not impose much resistance on the flow of the liquid passing between the valve body 21 and the valve seat 20d. Even if the seat portion 21b is separated from the valve seat 20d, if a part of the head portion 21a is inserted into the small-diameter portion 20b, the valve body 21 forms a restricted flow path Pr between itself and the valve seat member 20 and imposes resistance on the flow of the liquid passing through the restricted flow path Pr.

[0048] The outer diameter of the spring fitting portion 21c is smaller than the inner diameter of the accommodation cylinder 23b, forming an annular space for accommodating the coil spring 22 as a biasing member between the spring fitting portion 21c and the accommodation cylinder 23b, and fitting to the inner circumference of the coil spring 22 to guide the expansion and contraction of the coil spring 22. The coil spring 22 is interposed between the lower end of the seat portion 21b in FIG. 3 and the upper end of the centering portion 23c of the centering member 23 in FIG. 3, and constantly biases the valve body 21 in the direction of seating on the valve seat 20d. Therefore, in a state where no external force acts on the valve body 21, the valve body 21 is biased by the coil spring 22 and positioned at the position of seating on the valve seat 20d. Note that since the coil spring 22 is fitted to the spring fitting portion 21c, it can act on the valve body 21 with a stable biasing force without eccentricity.

[0049] The shaft portion 21d at the rear end in the valve body 21 is slidably inserted into the inner circumference of the centering portion 23c in the centering member 23, and the valve body 21 can move in the direction of approaching and separating without axial deviation with respect to the valve seat member 20 fitted to the fitting portion 23a of the centering member 23. Therefore, the head portion 21a of the valve body 21 can smoothly enter and exit the small-diameter portion 20b of the valve seat member 20 without interfering with the small-diameter portion 20b when entering and exiting the small-diameter portion 20b.

[0050] The push rod 24 is rod-shaped and includes a flange 24b capable of abutting against the end face of the large-diameter portion 20a of the valve seat member 20 in the middle, and a main body 24a whose lower side in FIG. 3 than the flange 24b is slidably inserted into the large-diameter portion 20a, and a pressing shaft 24c extending axially from the lower end of the main body 24a and facing the upper end of the head portion 21a of the valve body 21 in FIG. 3. The main body 24a does not face the hole 20c even if it penetrates into the large-diameter portion 20a until the flange 24b abuts against the upper end of the large-diameter portion 20a of the valve seat member 20 in FIG. 3, so that the hole 20c is not blocked. The pressing shaft 24c has an outer diameter sufficiently smaller than the outer diameter of the head portion 21a of the valve body 21 so as not to provide resistance when liquid passes between the pressing shaft 24c and the small-diameter portion 20b when the pressing shaft 24c penetrates into the small-diameter portion 20b.

[0051] Also, when the push rod 24 penetrates into the large-diameter portion 20a until the flange 24b abuts against the upper end of the large-diameter portion 20a of the valve seat member 20 in FIG. 3, it abuts against the head portion 21a of the valve body 21 and pushes the valve body 21 downward in FIG. 3, and the valve body 21 separates from the valve seat 20d while leaving a part of the head portion 21a in the small-diameter portion 20b.

[0052] The nut member 25 is cylindrical, has a threaded portion 25a on its outer periphery, and is threadedly coupled to the upper inner periphery of the valve hole 12b in FIG. 3 and attached to the housing body 12. When the nut member 25 is attached to the valve hole 12b, it abuts against the upper outer periphery of the large-diameter portion 20a of the valve seat member 20 in FIG. 3, and sandwiches the valve seat member 20 and the centering member 23 together with the stepped portion 12b1 to fix the valve seat member 20 and the centering member 23 within the valve hole 12b. Further, the nut member 25 has a flange 25b on its inner periphery that axially faces the flange 24b of the push rod 24. Therefore, the push rod 24 can move in the axial direction in the up-down direction in FIG. 3 within the range from the uppermost position where the flange 24b abuts against the flange 25b of the nut member 25 to the lowermost position where the flange 24b abuts against the upper end of the large-diameter portion 20a of the valve seat member 20 in FIG. 3.

[0053] The push rod 24 is connected via a wire (not shown) to a reverse switch (not shown) provided near the handle of the saddle-type vehicle M. When the push rod 24 is pushed downward in FIG. 3 by the operation of the reverse switch by the driver of the saddle-type vehicle M, the push rod 24 pushes the valve body 21 downward against the biasing force of the coil spring 22, causing the valve body 21 to separate from the valve seat 20d and the valve V to open. When the push rod 24 is moved upward in FIG. 3 by the operation of the reverse switch by the driver of the saddle-type vehicle M, the push rod 24 separates from the valve body 21. Therefore, the valve body 21 is pushed upward in FIG. 3 by the biasing force of the coil spring 22 and seats on the valve seat 20d, closing the valve V. In this way, the valve V is a normally-closed on-off valve that opens when the valve body 21 is pushed by the operation of the push rod 24 and closes when the biasing force of the coil spring 22 seats the valve body 21 on the valve seat 20d in a state where the pressing force of the push rod 24 does not act.

[0054] The accumulator 10 and the cylinder device C are configured as described above, and the operation of the valve V and the cylinder device C will be described below. In the cylinder device C, as described above, the pressure-side chamber R2 is open to the atmosphere, and the extension-side chamber R1 communicates with the liquid chamber L pressurized by the air chamber G of the accumulator 10 via the communication passage 16. When the valve V is closed without operating the push rod 24 in the valve V and without applying a force to separate the valve body 21 from the valve seat 20d from the push rod 24, the communication between the extension-side chamber R1 and the liquid chamber L is cut off and the liquid exchange between the extension-side chamber R1 and the liquid chamber L becomes impossible. Therefore, the cylinder device C cannot perform an extension operation or a contraction operation and becomes rod-shaped. On the other hand, when the push rod 24 in the valve V is operated to separate the valve body 21 from the valve seat 20d by the push rod 24 to open the valve V, the extension-side chamber R1 and the liquid chamber L are communicated and the liquid exchange between the extension-side chamber R1 and the liquid chamber L becomes possible. Therefore, the cylinder device C becomes in a state where it can expand and contract. Further, when the valve V is opened, the pressure-side chamber R2 is open to the atmosphere, and the pressure of the air chamber G is transmitted to the extension-side chamber R1 to press the piston 3 toward the pressure-side chamber R2 side. Therefore, the cylinder device C tends to contract during the opening of the valve V in a state where no external force is applied.

[0055] Based on the above, the operation of the cylinder device C applied to the straddle-type vehicle M will be described. First, when the valve V is closed, the cylinder device C becomes rod-shaped and cannot perform an extension operation or a contraction operation. Therefore, when the swing arm S swings in the vertical direction in FIG. 2 with respect to the vehicle body B due to the input of vibration from the road surface during the running of the straddle-type vehicle M, the cylinder device C transmits the swing of the swing arm S to the link plate P. Thus, the shock absorber D expands and contracts to generate a damping force, and the vibration of the vehicle body B is suppressed.

[0056] When the other party opens the valve V, a force in the extending direction acts on the expandable body 1 due to the weight of the vehicle body B, and the pressure in the extending chamber R1 becomes greater than the pressure in the accumulator 10. Therefore, the cylinder device C extends to its maximum extent, and the liquid moves from the extending chamber R1 through the communication passage 16 and the valve V to the liquid chamber L of the accumulator 10. When the cylinder device C extends, the swing arm S rotates in a direction approaching the vehicle body B, and the vertical distance between the vehicle body B and the wheel W decreases. Therefore, the vehicle height of the saddle-type vehicle M decreases by the amount of the decreased distance.

[0057] Here, when the valve V is opened, the push rod 24 separates the valve body 21 from the valve seat 20d but does not completely pull the head 21a out from inside the small-diameter portion 20b of the valve seat member 20. Therefore, a restricted flow path Pr is formed between the head 21a and the small-diameter portion 20b. When the cylinder device C extends and the liquid flows from the extending chamber R1 to the liquid chamber L, the high-pressure liquid pressed by the piston 3 passes between the valve body 21 and the valve seat 20d from the valve body 21 side toward the valve seat member 20 side and moves to the low-pressure liquid chamber L. Thus, when the side of the valve body 21 facing the valve seat 20d is defined as the front side and the opposite side as the back side, the valve body 21 is pressed toward the valve seat 20d side by the pressure in the extending chamber R1, which is high pressure on the back side. As a result, the valve body 21 does not move from the position where it is pushed by the push rod 24, and the head 21a remains in a state of penetrating into the small-diameter portion 20b. Therefore, the liquid flowing from the extending chamber R1 to the liquid chamber L passes through the restricted flow path Pr, and the restricted flow path Pr provides resistance to the flow of the liquid flowing from the extending chamber R1 to the liquid chamber L.

[0058] In this way, when the valve V is opened, the cylinder device C receives the vehicle weight and the telescopic body 1 exhibits an extension operation. However, since resistance is applied to the flow of the liquid by the restricted flow path Pr, the extension speed becomes slow and it extends slowly, and the vehicle height of the straddle-type vehicle M also slowly decreases. When the vehicle height on the rear wheel side of the straddle-type vehicle M is lowered, the vehicle center of gravity drops, suppressing the lifting of the front wheels during acceleration and improving the acceleration performance. Therefore, the driver can intentionally lower the vehicle height and improve the acceleration performance by operating the reverse switch to open the valve V during acceleration. And when lowering the vehicle height, since the valve V can resist the flow of the liquid and slow down the extension operation of the cylinder device C, sudden changes in the vehicle body posture can be suppressed and the handling stability can be improved.

[0059] Further, when the expandable body 1 extends from the most contracted state, the liquid in the expansion chamber R1 gradually moves into the liquid chamber L, and the free piston 14, which was at the discharge-side stroke end in the accumulator 10, moves in the direction of compressing the gas chamber G. When the expansion of the expandable body 1 progresses to a certain extent, eventually the free piston 14 comes into contact with the cushion 15, and when the free piston 14 further moves in the direction of compressing the gas chamber G due to further expansion of the expandable body 1, the cushion 15 is compressed. Then, a reaction force generated by the compression of the cushion 15 is added to the force generated due to the pressure of the gas in the gas chamber G, and the movement of the free piston 14 in the direction of compressing the gas chamber G is suppressed. That is, until the free piston 14 comes into contact with the cushion 15 from the discharge-side stroke end, the accumulator 10 presses the free piston 14 in the direction of expanding the gas chamber G only by the reaction force received from the gas in the gas chamber G. However, when the free piston 14 reaches the cushion 15 and further moves in the direction of compressing the gas chamber G, the accumulator 10 presses the free piston 14 in the direction of expanding the gas chamber G with the combined force of the gas reaction force and the elastic force generated by the compression of the cushion 15. Therefore, during the process from when the expandable body 1 is in the most contracted state to when it is in the most extended state, the accumulator 10 causes the rate of change of the force pressing the free piston 14 in the direction of expanding the gas chamber G with respect to the displacement of the free piston 14 in the direction of compressing the gas chamber G to increase as shown in FIG. 4, and can decelerate the moving speed of the free piston 14 and the expansion speed of the expandable body 1. And the force by which such an accumulator 10 obstructs the movement of the free piston 14 becomes even greater as the expansion of the expandable body 1 progresses, greatly reducing the expansion speed of the expandable body 1, and alleviating the impact when the piston 3 and the rod guide 5 come into contact when the cylinder device C is in the most extended state.

[0060] As described above, the cylinder device C applied to the straddle-type vehicle M extends when the valve V is opened to lower the vehicle height on the rear-wheel side. The restriction flow path Pr of the valve V not only can resist the flow of the liquid to slow down the lowering speed, but also can mitigate the impact at the time of full extension of the telescopic body 1 because the reaction force of the accumulator 10 increases halfway. Further, when the valve V is closed while the cylinder device C is extended and the vehicle height is lowered, the liquid cannot flow between the extension chamber R1 and the liquid chamber L, and the cylinder device C becomes a rod-shaped body and can maintain the state where the vehicle height is lowered.

[0061] Further, when the straddle-type vehicle M decelerates with the valve V kept open, if the vehicle body B pitches forward and the vehicle body B and the wheel W are separated, the force in the extending direction acting on the telescopic body 1 becomes small and the pressure in the accumulator 10 becomes larger than the pressure in the extension chamber R1, so that a force in the contracting direction acts. Therefore, the cylinder device C contracts and the liquid moves from the liquid chamber L to the extension chamber R1 through the communication passage 16 and the valve V. As the cylinder device C contracts, the swing arm S rotates in a direction away from the vehicle body B, and the vertical distance between the vehicle body B and the wheel W increases, and the vehicle height of the straddle-type vehicle M increases by the amount of the increased distance.

[0062] When the cylinder device C contracts and the liquid flows from the liquid chamber L to the extension chamber R1, the liquid in the liquid chamber L receiving the pressure of the air chamber G passes between the valve body 21 and the valve seat 20d from the valve seat member 20 side toward the valve body 21 side and moves to the low-pressure side extension chamber R1. Therefore, the valve body 21 retreats from the valve seat 20d to the position regulated by the stopper 23b1 under the pressure of the high-pressure side liquid chamber L from the front side, and the head 21a completely comes out of the small-diameter portion 20b to maximize the opening area of the valve V. When the head 21a comes out of the valve seat member 20, the restriction flow path Pr is not formed between the head 21a and the valve seat member 20, and the valve V allows the flow of the liquid from the liquid chamber L to the extension chamber R1 with almost no resistance.

[0063] Thus, when the liquid flows from the liquid chamber L to the extending chamber R1, unlike the case where the liquid flows from the extending chamber R1 to the liquid chamber L, it hardly resists the flow of the liquid. Therefore, the cylinder device C contracts promptly, and the vehicle height of the straddle-type vehicle M rises rapidly. Since raising the vehicle height on the rear-wheel side of the straddle-type vehicle M suppresses the lifting of the rear wheels from the road surface during braking and improves the vehicle body stability during braking, the driver can intentionally raise the vehicle height by operating the reverse switch to open the valve V during braking, thereby improving the vehicle body stability during braking.

[0064] And when raising the vehicle height, since the valve V hardly resists the flow of the liquid, the cylinder device C can contract promptly, so that the lifting of the wheels W from the road surface during braking can be suppressed immediately. When the valve V is closed while the cylinder device C contracts to raise the vehicle height, the liquid cannot flow back and forth between the extending chamber R1 and the liquid chamber L, and the cylinder device C becomes a rod-like body, maintaining the state where the vehicle height is raised.

[0065] As described above, the accumulator 10 of the present embodiment includes a hollow housing 11, a free piston (partition member) 14 that is housed in the housing 11, partitions the inside of the housing 11 into an air chamber G and a liquid chamber L, and moves inside the housing 11 to change the volume distribution between the air chamber G and the liquid chamber L, and a cushion (elastic body) 15 that is housed in the air chamber G and abuts against the free piston (partition member) 14 to suppress the movement of the free piston (partition member) 14 in the direction of decreasing the volume of the air chamber G of the free piston (partition member) 14. The cushion (elastic body) 15 is separated from the free piston (partition member) 14 when the free piston (partition member) 14 maximizes the volume of the air chamber G, and abuts against the free piston (partition member) 14 before the free piston (partition member) 14 minimizes the volume of the air chamber G to suppress the movement of the free piston (partition member) 14.

[0066] According to the accumulator 10 configured as described above, when the free piston (partition member) 14 is displaced from the position where the volume of the air chamber G is maximized in the direction of compressing the air chamber G, the cushion (elastic body) 15 is compressed on the way, and the elastic force of the cushion (elastic body) 15 is added to the reaction force of the gas in the air chamber G to increase the pressing force, so that the moving speed of the free piston (partition member) 14 in the direction of compressing the air chamber G can be decelerated. Therefore, in the accumulator 10 of the present embodiment, even if the pressure of the gas in the air chamber G is not increased to a high pressure, the elastic force of the cushion (elastic body) 15 is applied to the free piston (partition member) 14 during the movement of the free piston (partition member) 14, and the characteristic that the pressing force increases during the compression of the air chamber G can be realized, and the free piston (partition member) 14 can be stopped slowly. Further, since it is not necessary to increase the pressure in the air chamber G, it is not necessary to increase the contact surface pressure of the seal ring 14a with respect to the housing 11. Furthermore, since the cushion (elastic body) 15 is separated from the free piston (partition member) 14 when the free piston (partition member) 14 maximizes the volume of the air chamber G, the free piston (partition member) 14 can move smoothly in the situation where the free piston (partition member) 14 starts to compress the air chamber G. Therefore, there is an advantage that the telescopic body 1 can also exhibit a smooth extension operation.

[0067] Further, in the accumulator 10 of the present embodiment, the partition member is the free piston 14, and the elastic body is the resin cushion 15. According to the accumulator 10 configured as described above, since the elastic body is the resin cushion 15, when the free piston 14 is displaced in the compressing direction after contacting the cushion 15, an eccentric load as in the case where the elastic body is a coil spring does not act on the free piston 14, and the free piston 14 does not tilt with respect to the housing 11 due to the elastic force received from the cushion 15, and the free piston 14 can be displaced smoothly with respect to the housing 11, and it is not necessary to generate a pressing force due to uncontrollable stick-slip.

[0068] Furthermore, since the cushion (elastic body) 15 in the accumulator 10 of the present embodiment is formed of urethane foam, it contains innumerable air bubbles and occupies a small volume in the air chamber G, and the rate of decrease in the volume in the air chamber G is small. Therefore, the volume in the air chamber G can be secured, and the change in the volume in the air chamber G with respect to the displacement of the free piston (partition member) 14 becomes small, making it easy to tune the pressurization characteristics of the accumulator 10.

[0069] Also, the housing 11 in the accumulator 10 of the present embodiment has a cylindrical housing body 12 and a cap 13 that closes the opening on the air chamber side of the housing body 12. The cap 13 has a lid portion 13a that closes the opening of the housing body 12 and a valve case (protrusion) 13b that rises from the lid portion 13a. The cushion (elastic body) 15 is cylindrical and is fitted on the outer periphery of the valve case (protrusion) 13b.

[0070] The accumulator 10 configured in this way fixes the cushion (elastic body) 15 in the air chamber G by using the valve case 13b, so that the cushion (elastic body) 15 is arranged so as not to interfere with the filling of gas into the air chamber G by the air valve 13c, and the air valve 13c and the cushion (elastic body) 15 can be installed in the narrow accumulator 10 without difficulty. Note that the cap 13 integrally includes the lid portion 13a and the valve case 13b as a protrusion, but the lid portion 13a and the valve case 13b may be formed as separate parts.

[0071] Furthermore, the accumulator 10 of the present embodiment includes an annular adjusting shim 19 that is sandwiched between the outer periphery of the valve case (protrusion) 13b and the lid portion 13a between the cushion (elastic body) 15. According to the accumulator 10 configured in this way, it is possible to adjust the contact position of the free piston (partition member) 14 of the cushion (elastic body) 15, and since the adjusting shim 19 is fixed by using the cushion (elastic body) 15, it is not necessary to add parts for fixing the adjusting shim 19.

[0072] And the cylinder device C of the present embodiment includes a cylinder 2, a piston 3 that is movably inserted into the cylinder 2 and divides the inside of the cylinder 2 into an extending chamber R1 and a compression chamber R2, and a rod 4 that is movably inserted into the cylinder 2 and connected to the piston 3. The compression chamber R2 is open to the atmosphere, and the extending chamber R1 is filled with a liquid. The cylinder device C also includes an accumulator 10 and a communication passage 16 that connects the liquid chamber L to the extending chamber R1.

[0073] In the cylinder device C configured as described above, the compression chamber R2 is open to the atmosphere, and the pressure of the air chamber G acts on the extending chamber R1. Therefore, a spring force that contracts the telescopic body 1 can be exerted. When the telescopic body 1 exhibits an extension operation from the most contracted state due to an external force and the extension of the telescopic body 1 progresses, the pressure of the accumulator 10 increases, and the extension speed is decelerated at the stroke end on the extension side where the telescopic body 1 extends to the maximum. Thus, the impact at the maximum extension can be mitigated. In this way, in the cylinder device C, as the air chamber G is compressed, the pressure of the accumulator 10 increases before it is compressed to the maximum. Therefore, the impact at the maximum extension can be mitigated without providing other systems such as a cushion or a hydraulic lock mechanism inside the telescopic body 1. As a result, the telescopic body 1 can be miniaturized, and the mountability to devices such as the straddle-type vehicle M where it is difficult to secure an installation space can be improved.

[0074] Further, the extension chamber R1 may be opened to the atmosphere, and the pressure chamber R2 and the liquid chamber L may be connected by the communication passage 16. In this case, the cylinder device C exhibits a spring force for extending the telescopic body 1, and when the telescopic body 1 exhibits a contraction operation from the fully extended state due to an external force and the contraction of the telescopic body 1 progresses, liquid flows from the pressure chamber R2 into the liquid chamber L. Therefore, the free piston 14 moves in the direction of compressing the air chamber G from the discharge side stroke end. Thus, in this case, as the contraction of the telescopic body 1 progresses, the pressurizing force of the accumulator 10 increases, and the contraction speed is decelerated at the contraction side stroke end where the telescopic body 1 is fully contracted, so that the impact at the time of full contraction can be mitigated. In this way, in the cylinder device C, as the air chamber G is compressed, the pressurizing force of the accumulator 10 increases before it is fully compressed. Therefore, even without providing other systems such as a cushion or a hydraulic lock mechanism in the telescopic body 1, the impact at the time of full contraction can be mitigated, so that the telescopic body 1 can be miniaturized and the mountability to devices such as the straddle-type vehicle M where it is difficult to secure an installation space can be improved.

[0075] Further, the cylinder device C of the present embodiment is provided in the communication passage 16 and can open and close the communication passage 16. When the valve is opened, it provides resistance to the flow of liquid in one direction in the communication passage 16 and is fully open to the flow of liquid in the other direction, and is provided with a valve V.

[0076] In the present embodiment, the cylinder device C has the pressure chamber R2 open to the atmosphere, and when the valve V is opened, the pressure of the air chamber G acts on the extension chamber R1, so that a spring force for contracting the telescopic body 1 can be exhibited. Further, when the valve V of the cylinder device C is opened, the flow path Pr provides resistance to the flow of liquid from the extension chamber R1 to the liquid chamber L, and provides almost no resistance to the flow of liquid from the liquid chamber L to the extension chamber R1. Therefore, when extending due to an external force, the operation becomes slow and the telescopic body 1 is slowly extended, and when contracting spontaneously or due to an external force, the operation becomes sensitive and the telescopic body 1 can be quickly contracted.

[0077] Incidentally, if the pressure chamber R2 is vented to the atmosphere, the extension chamber R1 and the liquid chamber L are connected by the communication passage 16, and the orientation of the valve V installed with respect to the communication passage 16 is reversed, the cylinder device C exerts a spring force that contracts the telescopic body 1 when the valve V is opened, and the valve V provides resistance to the flow of liquid from the liquid chamber L to the extension chamber R1 with the restriction passage Pr, and provides almost no resistance to the flow of liquid from the extension chamber R1 to the liquid chamber L. Therefore, when the telescopic body 1 contracts spontaneously or by an external force, the operation becomes slow and the telescopic body 1 contracts slowly, and when the telescopic body 1 extends by an external force, the operation becomes sensitive and the telescopic body 1 can be quickly extended.

[0078] Alternatively, the extension chamber R1 may be vented to the atmosphere, the pressure chamber R2 and the liquid chamber L may be connected by the communication passage 16, and the valve V may provide resistance to the flow of liquid from the pressure chamber R2 to the liquid chamber L with the restriction passage Pr when the valve V is opened, and provide almost no resistance to the flow of liquid from the liquid chamber L to the pressure chamber R2. In this way, the cylinder device C exerts a spring force that extends the telescopic body 1 when the valve V is opened, and when the telescopic body 1 contracts by an external force, the operation becomes slow and the telescopic body 1 contracts slowly, and when the telescopic body 1 extends spontaneously or by an external force, the operation becomes sensitive and the telescopic body 1 can be quickly extended.

[0079] Furthermore, the extension chamber R1 may be vented to the atmosphere, the pressure chamber R2 and the liquid chamber L may be connected by the communication passage 16, and the valve V may provide resistance to the flow of liquid from the liquid chamber L to the pressure chamber R2 with the restriction passage Pr when the valve V is opened, and provide almost no resistance to the flow of liquid from the pressure chamber R2 to the liquid chamber L. In this way, the cylinder device C exerts a spring force that extends the telescopic body 1 when the valve V is opened, and when the telescopic body 1 extends spontaneously or by an external force, the operation becomes slow and the telescopic body 1 extends slowly, and when the telescopic body 1 contracts by an external force, the operation becomes sensitive and the telescopic body 1 can be quickly contracted.

[0080] In this way, the cylinder device C can slow down the operation of either extension or contraction, can not only give polarity to the operation speed depending on the operating direction, but also suppress the increase in the number of parts and cost.

[0081] Furthermore, the telescopic body 1 in the cylinder device C of the present embodiment is rotatably connected to the lower end of a shock absorber D interposed between the vehicle body B of the straddle-type vehicle M and the wheel W and the vehicle body B of the straddle-type vehicle M, and is bridged between a link plate P and a swing arm S that is swingable with respect to the vehicle body B of the straddle-type vehicle M and holds the wheel W. The pressure chamber R2 is open to the atmosphere and the extension chamber R1 is filled with liquid. The valve V resists the flow of the liquid during the extension operation of the telescopic body 1, while being fully open during the contraction operation of the telescopic body 1. The cylinder device C configured in this way can adjust the vehicle height on the rear wheel side of the straddle-type vehicle M by opening and closing the valve V. Moreover, when lowering the vehicle height on the rear wheel side during acceleration of the straddle-type vehicle M, the valve V resists the flow of the liquid to reduce the vehicle height acceleration, and the impact at the maximum extension of the telescopic body 1 can be mitigated by the pressurizing force of the accumulator 10, so that the handling stability can be improved. Further, when the vehicle height increases during braking, the valve V does not resist the flow of the liquid, and the telescopic body 1 contracts promptly, causing the vehicle height to rise promptly, thereby improving the vehicle body stability during braking.

[0082] Also, the valve V of the cylinder device C in the present embodiment is cylindrical and includes a valve seat member 20 having an annular valve seat 20d at one end in the axial direction, a valve body 21 having a head 21a that can enter and exit the valve seat member 20 and an annular seat portion 21b that is continuous behind the head 21a and can be seated and unseated from the valve seat 20d, a coil spring (biasing member) 22 that biases the valve body 21 toward the valve seat member 20, a restricted flow path Pr formed in a state where the head 21a is inserted into the valve seat member 20, and when the valve is opened and the seat portion 21b is separated from the valve seat 20d, the entire head 21a exits from the valve seat member 20 and is fully open with respect to the flow from the valve seat member side to the valve body side, and at least a part of the head 21a is inserted into the valve seat member 20 and resistance is provided by the restricted flow path Pr with respect to the flow from the valve body side to the valve seat member side.

[0083] According to the valve V configured as described above, at the time of valve opening, with respect to the flow from the valve seat member side to the valve body side, the head 21a hardly gives resistance to the flow of the liquid passing through without completely coming out of the valve seat member 20 to form the restricted flow path Pr. On the other hand, with respect to the flow from the valve body side to the valve seat member side, it is possible to give resistance to the flow of the liquid passing through by the restricted flow path Pr. In this way, the valve V can function as a check valve with respect to the flow of the liquid in one direction alone and as a valve that gives resistance to the flow of the liquid in the other direction. Therefore, according to the valve V of the present embodiment, in the conventional valve, a check valve and a valve that gives resistance had to be provided in parallel, but the functions of a check valve and a valve that gives resistance can be realized alone. From the above, according to the valve V of the present embodiment, it is possible to realize a valve that gives resistance to the flow in one direction but does not give resistance to the flow in the other direction at the time of valve opening without causing an increase in the number of parts and cost.

[0084] In addition, as described above, the valve seat member 20 includes a large-diameter portion 20a and a small-diameter portion 20b, but it only needs to have at least the small-diameter portion 20b that has a valve seat 20d at one end in the axial direction and allows the head 21a of the valve body 21 to enter and exit. Therefore, the other structure of the valve seat member 20 can be arbitrarily designed and changed. Further, the biasing member is a coil spring 22, but it may be a spring or an elastic body other than the coil spring as long as it can bias the valve body 21 in the direction of seating on the valve seat 20d.

[0085] Also, in the valve V of the present embodiment, the restricted flow path Pr is formed by an annular gap between the outer periphery of the head 21a of the valve body 21 and the inner periphery of the valve seat member 20. According to the valve V configured in this way, since an annular gap is formed between the head 21a and the valve seat member 20 and they are in non-contact with each other, when the valve body 21 moves axially with respect to the valve seat member 20 and the head 21a enters and exits the valve seat member 20, the head 21a does not interfere with the valve seat member 20, so the valve can be smoothly opened and closed.

[0086] Furthermore, in the valve V of the present embodiment, a centering member 23 is provided for centering the valve element 21 with respect to the valve seat member 20 while allowing axial movement of the valve element 21. According to the valve V provided with the centering member 23 for centering the valve element 21 in this way, when the head 21a of the valve element 21 enters and exits the valve seat member 20, the valve element 21 can move axially without axial misalignment, so there is no worry that the head 21a will bite into the inner peripheral surface of the valve seat member 20. Smooth axial movement of the valve element 21 is ensured, and the valve can be opened and closed smoothly.

[0087] In the valve V of the present embodiment, a shaft portion 21d is provided on the side of the valve element 21 opposite to the valve seat, and an annular centering portion 23c is provided in which the centering member 23 is slidably inserted into the shaft portion 21d. However, a hole may be provided along the axial direction on the valve element 21 side, and a shaft inserted into the hole of the valve element 21 may be provided on the centering member 23 side to center the valve element 21 with respect to the valve seat member 20. Alternatively, the centering member 23 may be provided on the housing body 12. Further, a hole may be provided along the axial direction at the tip of the head 21a, and a shaft inserted into the hole of the head 21a may be provided at the tip of the push rod 24, and this shaft may be used as the centering member.

[0088] However, as described above, when the centering member 23 is cylindrical and fits into the small-diameter portion 20b of the valve seat member 20 to accommodate the valve element 21, and the centering portion 23c of the centering member 23 functions as a spring receiver for a coil spring (biasing member) 22 that centers and biases the valve element 21, the components constituting the valve V can be pre-assembled and accommodated in the valve hole 12b, which facilitates the assembly of the valve V. In addition, since the centering member 23 and the valve element 21 can be assembled with the valve seat member 20 as a base, there is an advantage that it is easy to center the valve element 21 with respect to the valve seat member 20.

[0089] Incidentally, as described above, the restricted flow path Pr is formed by the annular gap between the outer periphery of the head 21a of the valve body 21 and the inner periphery of the valve seat member 20. However, like the valve V1 of the first modification of the embodiment shown in FIG. 5, the outer periphery of the head 21a is brought into sliding contact with the inner periphery of the small-diameter portion 20b of the valve seat member 20, and a groove 21a1 is provided along the axial direction on the outer periphery of the head 21a. Until the sheet portion 21b is separated from the valve seat 20d and the head 21a completely exits from the inside of the small-diameter portion 20b, the restricted flow path Pr may be formed by the groove 21a1 provided on the head 21a. In this case, since the valve body 21 is centered with respect to the valve seat member 20 by the centering member 23, even if the head 21a exits from the inner periphery of the valve seat member 20, the head 21a can enter the valve seat member 20 again and the valve V can be closed. Therefore, when the centering member 23 is provided, the restricted flow path Pr may be provided by the groove 21a1 formed on the outer periphery of the head 21a in this way. Further, in this case, like the valve V2 of the second modification shown in FIG. 6, instead of the groove 21a1, a passage 21a2 that opens from the tip of the head 21a and opens to the base end of the head 21a may be formed, and the restricted flow path Pr may be formed by the passage 21a2. When the restricted flow path Pr is formed by the passage 21a2 in this way, until the head 21a completely exits from the small-diameter portion 20b, the flow path length of the restricted flow path Pr does not change and the resistance applied to the liquid flow by the restricted flow path Pr does not change.

[0090] Incidentally, the accumulator 10 can be used as an accumulator used in various hydraulic circuits other than the cylinder device C described above, and the cylinder device C may also be used in a cylinder device used for vehicle height adjustment of the straddle-type vehicle M other than that.

[0091] As described above, the preferred embodiments of the present invention have been described in detail. However, modifications, deformations, and changes are possible without departing from the scope of the claims.

Explanation of Reference Numerals

[0092] 1... telescopic body, 2... cylinder, 3... piston, 4... rod, 10... accumulator, 11... housing, 12... housing body, 13... cap, 13a... lid part, 13b... valve case (protrusion), 13c... air valve, 14... free piston (partition member), 15... cushion (elastic body), 16... communication passage, 19... adjusting shim, B... vehicle body, C... cylinder device, G... air chamber, L... liquid chamber, M... saddle-type vehicle, P... link plate, Pr... restricted flow path, R1... extension chamber, R2... compression chamber, S... swing arm, V, V1, V2... valves, W... wheel

Claims

1. A hollow housing, a partition member that is housed within the housing, partitions the interior of the housing into a gas chamber and a liquid chamber, and is movable within the housing to change the volume distribution between the gas chamber and the liquid chamber, and an elastic body that is housed within the gas chamber and abuts against the partition member to suppress movement of the partition member in a direction that decreases the volume of the gas chamber. The elastic body is separated from the partition member when the partition member maximizes the volume of the gas chamber, and abuts against the partition member before the partition member minimizes the volume of the gas chamber to suppress movement of the partition member. An accumulator characterized by the above.

2. The partition member is a free piston, and the elastic body is a resin cushion. The accumulator according to claim 1, characterized by the above.

3. The elastic body is formed of foamed urethane. The accumulator according to claim 1, characterized by the above.

4. The housing has a cylindrical housing body, and a cap that closes the opening on the gas chamber side of the housing body. The cap has a lid portion that closes the opening of the housing body, and a protruding portion that rises from the lid portion. The elastic body is cylindrical and is fitted onto the outer periphery of the protruding portion. The valve according to claim 1, characterized by the above.

5. An annular adjusting shim is provided between the outer periphery of the protruding portion and the elastic body and is sandwiched between the elastic body and the lid portion. The accumulator according to claim 4, characterized by the above.

6. A cylinder, a piston that is movably inserted into the cylinder and partitions the interior of the cylinder into an extension chamber and a compression chamber, and a rod that is movably inserted into the cylinder and is connected to the piston, and a telescopic body in which one of the extension chamber and the compression chamber is open to the atmosphere and the other is filled with liquid, the accumulator according to any one of claims 1 to 5, a communication passage that connects the liquid chamber to the other of the extension chamber and the compression chamber, and a valve that is provided in the communication passage, can open and close the communication passage, provides resistance to the flow of liquid in one direction through the communication passage when the valve is open, and is fully open to the flow of liquid in the other direction. A cylinder device characterized by the above.

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