Accumulator and cylinder device

Abstract

This accumulator (10) is provided with: a hollow housing (11); a partition wall member (14) which is accommodated in the housing (11), divides the inside of the housing (11) into an air chamber (G) and a liquid chamber (L), moves in the housing (11), and can change the volume distribution between the air chamber (G) and the liquid chamber (L); and an elastic body (15) which is accommodated in the air chamber (G) and suppresses movement of the partition member (14) in the direction in which the volume of the air chamber (G) is reduced when the elastic body (15) comes into contact with the partition wall member (14), the elastic body (15) being separated from the partition wall member (14) when the partition wall member (14) maximizes the volume of the air chamber (G), and the elastic body (15) suppressing movement of the partition wall member (14) by abutting on the partition wall member (14) before the partition wall member (14) minimizes the volume of the air chamber (G).

Description

Accumulator and cylinder device

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

[0002] Accumulators are used in cylinder devices such as shock absorbers and gas springs, and pressurize the working chamber within the cylinder device so that an appropriate damping force or spring force is obtained when the cylinder device expands or contracts.

[0003] Such an accumulator, as disclosed in JP2006-342869A, for example, includes a housing and a free piston that is slidably inserted into the housing and divides the interior of the housing into a liquid chamber and an air chamber.

[0004] JP2006-342869A

[0005] In conventional accumulators, the smaller the volume of the air chamber, the greater the pressure inside the air chamber, allowing the liquid chamber to be pressurized to a high pressure. However, when a conventional accumulator is used in a cylinder device such as a shock absorber, it is necessary to preliminarily increase the pressure inside the air chamber in order to slow down the speed at which the cylinder device moves to the stroke end using the gas reaction force of the accumulator without using a system such as a cushion or hydraulic lock.

[0006] However, doing so makes it difficult to seal the air chamber and requires increasing the tension of the seal around the rod of the cylinder device, which hinders smooth extension and contraction of the cylinder device.

[0007] As described above, in conventional accumulators, the only way to obtain a pressure sufficient to reduce the speed at which a cylinder device or the like moves toward the stroke end is to pre-fill the accumulator with high-pressure gas, but this has the problem of adversely affecting the operation of the cylinder device.

[0008] Therefore, an object of the present invention is to provide an accumulator that can realize the characteristic of increasing the pressure during compression of the air chamber without increasing the pressure inside the air chamber, and a cylinder device that is suitable for use with such an accumulator.

[0009] In order to solve the above problem, the accumulator of the present invention comprises a hollow housing, a partition member that is accommodated within the housing and divides the interior of the housing into an air chamber and a liquid chamber and that can move within the housing to change the volume distribution between the air chamber and the liquid chamber, and an elastic body that is accommodated within the air chamber and that, when it abuts against the partition member, suppresses movement of the partition member in a direction that reduces the volume of the air chamber, and the elastic body is spaced 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 movement of the partition member.

[0010] With an accumulator configured in this manner, when the partition member displaces in the direction compressing the air chamber from the position where the volume of the air chamber is maximized, the elastic body is compressed along the way, and the elastic force of the elastic body is added to the reaction force of the gas in the air chamber, increasing the pressurizing force and slowing down the speed of movement of the partition member in the direction compressing the air chamber. In addition, there is no need to create high pressure inside the air chamber, and further, because the elastic body is separated from the partition member when the volume of the air chamber is maximized, the partition member can move smoothly when it begins to compress the air chamber, which has the advantage that the expandable body can also smoothly extend.

[0011] The cylinder device also includes a cylinder, a piston movably inserted into the cylinder and dividing the interior of the cylinder into an extension-side chamber and a compression-side chamber, and a rod movably inserted into the cylinder and connected to the piston, wherein one of the extension-side chamber and the compression-side chamber is open to the atmosphere and the other of the extension-side chamber and the compression-side chamber is filled with liquid, an accumulator, a communication passage connecting the liquid chamber to the other of the extension-side chamber and the compression-side chamber, and a valve provided in the communication passage that can open and close the communication passage and that, when open, provides resistance to the flow of liquid in one direction through the communication passage and is fully open to the flow of liquid in the other direction.

[0012] In this way, the cylinder device can exert a spring force in either the extension or 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 along the way, making it possible to mitigate the impact at the time of maximum extension or contraction without providing other systems such as a cushion or hydraulic locking mechanism inside the telescopic body, which allows the telescopic body to be made smaller and improves its mountability in equipment where it is difficult to secure installation space, such as saddle-type vehicles.Furthermore, the cylinder device can slow down the operation of either the extension or contraction, which not only makes it possible to polarize the operation speed depending on the operation direction, but also prevents an increase in the number of parts and costs.

[0013] Fig. 1 is a cross-sectional view of a cylinder device according to one embodiment. Fig. 2 is a side view of a saddle-ride type vehicle equipped with the cylinder device according to one embodiment. Fig. 3 is an enlarged cross-sectional view of a valve of the cylinder device according to one embodiment. Fig. 4 is a diagram showing pressurization characteristics of an accumulator according to one embodiment. Fig. 5 is a partially enlarged cross-sectional view of a valve of a first modified example of one embodiment. Fig. 6 is a partially enlarged cross-sectional view of a valve of a second modified example of one embodiment.

[0014] The present invention will be described based on the embodiment shown in the drawings. As shown in Figure 1, a cylinder device C equipped with an accumulator 10 in one embodiment includes an expandable body 1, the accumulator 10, a communication passage 16 that connects the inside of the expandable body 1 with the accumulator 10, and a valve V provided in the communication passage 16.

[0015] As shown in Figure 2, the telescopic body 1 in the cylinder device C is spanned across a link plate P that is rotatably connected to the lower end of a shock absorber D interposed between the body B and wheel W of the saddle-riding vehicle M and the body B of the saddle-riding vehicle M, and a swing arm S that is swingable relative to the body B of the saddle-riding vehicle M and holds the wheel W.

[0016] The shock absorber D is a telescopic shock absorber, and although not shown in detail, it is equipped with a cylinder and a rod that can move in and out of the cylinder, and when the rod moves axially relative to the cylinder, it exerts a damping force that prevents the shock absorber itself from expanding or contracting. The upper end of the shock absorber D is attached to the vehicle body B so as to be rotatable in the fore-and-aft direction of the vehicle body B, and the lower end of the shock absorber D is attached to a link plate P so as to be rotatable in the fore-and-aft direction of the vehicle body B. The link plate P is triangular in shape, 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 front end of the swing arm S is hingedly connected to the vehicle body B so as to be rotatable in the vertical direction, and the rear end thereof rotatably holds a wheel W, so that the swing arm S can swing in the vertical direction relative to the vehicle body B. In addition, the other end of the telescopic body 1 is hingedly connected to the middle part of the swing arm S.

[0017] Therefore, when the telescopic body 1 is rod-shaped and does not extend or retract, if the swing arm S rotates upward in Figure 2 relative to the vehicle body B and the wheel W approaches the vehicle body B, the link plate P rotates upward relative to the vehicle body B and compresses the shock absorber D, and the damping force generated by the shock absorber D suppresses movement of the wheel W relative to the vehicle body B. Also, when the telescopic body 1 is rod-shaped and does not extend or retract, if the swing arm S rotates downward in Figure 2 relative to the vehicle body B and the wheel W attempts to move away from the vehicle body B, the link plate P rotates downward relative to the vehicle body B and extends the shock absorber D, and the damping force generated by the shock absorber D suppresses movement of the wheel W relative to the vehicle body B. Therefore, the shock absorber D suppresses relative movement between the wheel W and the vehicle body B due to vibrations input while the saddle-type vehicle M is traveling, improving the ride comfort of the vehicle.

[0018] On the other hand, when the telescopic body 1 is extended, the cylinder device C rotates the swing arm S upward in FIG. 2 with the point of connection to the vehicle body B as a fulcrum, so that the wheel W approaches the vehicle body B and the vehicle height of the saddle-riding type vehicle M is lowered, and when the telescopic body 1 is retracted, the swing arm S rotates downward in FIG. 2 with the point of connection to the vehicle body B as a fulcrum, so that the wheel W moves away from the vehicle body B and the vehicle height of the saddle-riding type vehicle M is raised.

[0019] The following provides a detailed description of the accumulator 10 and the cylinder device C. The telescopic body 1 includes a cylinder 2, a piston 3 movably inserted into the cylinder 2 and dividing the interior of the cylinder 2 into an extension-side chamber R1 and a compression-side chamber R2, and a rod 4 movably inserted into the cylinder 2 and connected to the piston 3.

[0020] 1, the cylinder 2 is cylindrical and has a bottom, and is provided at its bottom 2a with an eye-shaped bracket 2b that is hingedly connected to a link plate P. An annular rod guide 5 is attached to the open end on the right side in FIG. 1. The piston 3 is provided on its outer periphery with an annular seal ring 3a and an annular piston ring 3b that slide against the inner periphery of the cylinder 2. The piston 3 divides the interior of the cylinder 2 into an expansion-side chamber R1 and a compression-side chamber R2, and can move smoothly within the cylinder 2 in the left-right direction in FIG. 1, which corresponds to the axial direction.

[0021] The rod 4 is inserted into the cylinder 2 by being inserted through the inner periphery of the rod guide 5, with its tip (left end in FIG. 1 ) connected to the piston 3 and its base (right end in FIG. 1 ) protruding outside the cylinder 2. The cylinder 2 is provided with a hole 2c that connects the compression-side chamber R2 inside the cylinder 2 to the left of the piston 3 to the outside of the cylinder 2, and the compression-side chamber R2 is open to the atmosphere. In addition, a connection hole 2d is provided on the side of the open end of the cylinder 2 to which a joint 6 facing the extension-side chamber R1 is attached.

[0022] The accumulator 10 comprises a hollow housing 11, a free piston 14 housed within the housing 11 and serving as a partition member that divides the interior of the housing 11 into an air chamber G and a liquid chamber L and that can move within the housing 11 to change the volume distribution between the liquid chamber L and the air chamber G, and a cylindrical cushion 15 serving as an elastic body that is housed within the air chamber G and, when it comes into contact with the free piston 14, suppresses movement of the free piston 14 in a direction that reduces the volume of the air chamber G.

[0023] The housing 11 is configured to include a cylindrical housing main body 12 having a bottom 12a and a cap 13 that closes the open end of the housing main body 12. The housing main body 12 is equipped with a valve hole 12b that penetrates the bottom 12a in the vertical direction in Fig. 1, which is a direction perpendicular to the axial direction, and a port 12c that communicates the inside of the valve hole 12b with the liquid chamber L. As shown in Fig. 3, the inner diameter of the valve hole 12b is smaller on the lower side, and a step 12b1 is provided below the port 12c in Fig. 3.

[0024] A joint 18 that connects the pipe 17 to the housing main body 12 is attached to the open end at the lower end of the valve hole 12b. One end of the pipe 17 is connected to the cylinder 2 via the joint 6, and the other end is connected to the accumulator 10 via the joint 18, thereby connecting the expansion-side chamber R1 and the valve hole 12b. In this manner, in the present embodiment, the pipe 17, the valve hole 12b, and the port 12c form a communication passage 16 that connects the expansion-side chamber R1 and the fluid chamber L of the accumulator 10.

[0025] The cap 13 comprises a cylindrical lid portion 13a with a bottom that is screwed to the inner periphery of the right end of the housing body 12 in Figure 1, which is on the air chamber G side, and closes the right end of the housing body 12 in Figure 1; a cylindrical valve case 13b that serves as a protrusion 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 allows gas to be injected into the air chamber G from the outside, and closes the open end of the housing body 12.

[0026] The lid portion 13a is provided with a seal ring 13d on its outer periphery and a threaded portion 13e provided to the right of the seal ring 13d in Fig. 1. 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 threaded portion 13e, the seal ring 13d is brought into close contact with the inner periphery of the housing body 12, sealing the inside of the accumulator 10 and preventing gas from leaking from inside the accumulator 10.

[0027] The free piston 14 is provided with a seal ring 14a on its outer periphery and is housed within the housing body 12 so as to be axially movable, with the seal ring 14a in sliding contact with the inner periphery of the housing body 12, dividing the interior of the housing body 12 into a liquid chamber L and an air chamber G and transmitting the pressure within the air chamber G to the liquid chamber L. When the free piston 14 is displaced left and right in Figure 1 within the housing 11, it changes the volume distribution between the air chamber G and the liquid chamber L within the housing 11. Compressed gas is sealed within the air chamber G, and the pressure within the air chamber G is always equal to or higher than atmospheric pressure. In the accumulator 10 of this embodiment, the liquid chamber L is connected to the extension-side chamber R1 of the telescopic body 1 via the communication passage 16, the compression-side chamber R2 of the telescopic body 1 is open to the atmosphere, and when the liquid chamber L and the extension-side chamber R1 are connected to each other, the piston 3 is pressed by the pressure of the extension-side chamber R1 to which the pressure of the liquid chamber L is propagated, causing the telescopic body 1 to fully contract, the compression-side chamber R2 to be fully compressed, and the volume of the extension-side chamber R1 to be maximized. When the telescopic body 1 is fully contracted in this manner, the accumulator 10 discharges a maximum amount of liquid to the outside, and the free piston 14 is disposed at a position (discharge-side stroke end) within the housing 11 where the volume of the liquid chamber L is minimized and the volume of the air chamber G is maximized.

[0028] The cushion 15 is made of resin, and specifically, is formed by molding urethane foam into a cylindrical shape. The cushion 15 has two annular recesses formed along the circumferential direction on its outer periphery to facilitate contraction and deformation when subjected to an axial load. The cushion 15 is fitted to the outer periphery of the valve case 13b of the cap 13 and housed in the air chamber G. When the free piston 14 is positioned at the discharge-side stroke end, the cushion 15 is housed in the air chamber G so that the free piston 14 is spaced apart from the cushion 15 in the axial direction. When the telescopic body 1 extends and liquid flows from the extension-side chamber R1 of the telescopic body 1 into the liquid chamber L, causing the free piston 14 to move in a direction compressing the air chamber G, the free piston 14 abuts against the cushion 15 before the telescopic body 1 reaches its maximum extension. This compresses the cushion 15 against any further movement of the free piston 14 in the direction compressing the air chamber G, thereby exerting a resilient force that prevents the free piston 14 from moving further. In this way, in the accumulator 10, when the free piston 14 is displaced from the discharge-side stroke end in a direction compressing the air chamber G, the cushion 15 is compressed midway, and the elastic force generated by the cushion 15 in addition to the pressure of the gas in the air chamber G acts on the free piston 14, so that, as shown in Fig. 4, the pressurization characteristic, which is the characteristic of the force exerted by the accumulator 10 to press the free piston 14 in response to the displacement of the free piston 14, can be changed midway through the displacement of the free piston 14. Note that Fig. 4 shows the pressurization characteristic of the accumulator 10 when the free piston 4 is displaced from the discharge-side stroke end in a direction compressing the air chamber G, with the displacement when the free piston 4 is at the discharge-side stroke end being set to 0 and the displacement when the free piston 4 abuts against the cushion 15 being set to X.

[0029] Furthermore, since the cushion 15 is made of foamed urethane, it contains countless air bubbles and occupies a small volume within the air chamber G. As a result, the volume within the air chamber G is secured and the change in volume within the air chamber G relative to the displacement of the free piston 14 is small, making it easy to tune the pressurization characteristics of the accumulator 10.

[0030] In this embodiment, the elastic body accommodated in the air chamber G is the cushion 15, but it may be a spring or other material other than the cushion 15. The cushion 15 is made of urethane foam, but it may be made of rubber, a synthetic resin with high elasticity, or the like. In this embodiment, the partition member is the free piston 14, but it may be made of a bellows, a diaphragm, or the like.

[0031] Furthermore, in the accumulator 10 of this embodiment, multiple annular adjustment shims 19 are stacked and fitted to the outer periphery of the valve case 13b. These adjustment shims 19 are sandwiched between the cushion 15 and the lid portion 13a of the cap 13 and fixed to the outer periphery of the valve case 13b. The adjustment shims 19 are provided to adjust the axial position of the cushion 15 relative to the housing 11, and the position of the left end of the cushion 15 in FIG. 1 , which is the tip of the cushion 15, can be adjusted by changing the number of stacked adjustment shims 19. The adjustment shims 19 can be omitted if unnecessary, but the number of adjustment shims installed can be changed as needed depending on the desired position of the cushion 15. Furthermore, instead of adjusting the position of the cushion 15 by the number of adjustment shims 19, multiple adjustment shims of different thicknesses may be prepared and the position of the cushion 15 may be adjusted using an adjustment shim of an appropriate thickness depending on the position of the cushion 15.

[0032] A valve V is accommodated in the valve hole 12b of the housing main body 12. In this embodiment, as shown in Fig. 3, the valve V includes a valve seat member 20 accommodated in the valve hole 12b, a valve element 21 that is removably seated on the valve seat member 20, a coil spring 22 as a biasing member that biases the valve element 21 toward the valve seat member 20, an aligning member 23 that aligns the valve element 21, a push rod 24 that is externally operated to press the valve element 21 against the biasing force of the coil spring 22, thereby separating the valve element 21 from the valve seat member 20, and an annular nut member 25 that is threadedly coupled to the open end of the valve hole 12b at the upper end in Fig. 3.

[0033] The valve seat member 20 is cylindrical and includes a large-diameter portion 20a having a large outer diameter that fits into the valve hole 12b, a small-diameter portion 20b having a smaller outer diameter below the large-diameter portion 20a in Fig. 3, and a hole 20c that penetrates the large-diameter portion 20a in the radial direction, and a valve seat 20d is formed by the annular lower end surface of the lower end of the small-diameter portion 20b, which is one end in the axial direction. In addition, a seal ring 20e is attached to the outer periphery of the large-diameter portion 20a and above the hole 20c in Fig. 3, so that when the valve seat member 20 is accommodated in the valve hole 12b, it comes into close contact with the wall surface that defines the valve hole 12b of the housing main body 12 to form a seal between the valve seat member 20 and the housing main body 12.

[0034] The aligning member 23 is cylindrical and includes a fitting portion 23a that fits onto 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 of the fitting portion 23a in FIG. 3, has an outer diameter smaller than that of the fitting portion 23a, and houses the valve body 21 and the coil spring 22 inside; and an aligning portion 23c that is provided in the shape of a flange from the lower end of the housing cylinder 23b in FIG. 3 toward the inner periphery.

[0035] The aligning member 23 is inserted into the valve hole 12b until the outer periphery of the fitting portion 23a at the lower end in Figure 3 abuts against the step 12b1 of the valve hole 12b. When the valve seat member 20 is accommodated in the valve hole 12b with the small-diameter portion 20b of the valve seat member 20 fitted into the inner periphery of the fitting portion 23a of the aligning member 23 and the step on the outer periphery between the large-diameter portion 20a and the small-diameter portion 20b abutting against the upper end of the fitting portion 23a in Figure 3, the port 12c of the housing body 12 and the hole 20c face each other, connecting the interior of the valve seat member 20 with the fluid chamber L of the accumulator 10.

[0036] The accommodating cylinder 23b includes a stopper 23b1, which is an annular step formed on the inner periphery by reducing the inner diameter of the lower side in FIG. 3 , and a hole 23b2 that penetrates radially above the stopper 23b1 in FIG. 3 . The outer diameter of the accommodating cylinder 23b is smaller than the inner diameter of the valve hole 12b below the step 12b1 in FIG. 3 . Therefore, when the aligning member 23 is accommodated in the valve hole 12b as described above, an annular gap is formed between the accommodating cylinder 23b and the wall surface of the valve hole 12b. The interior of the aligning member 23 communicates with the liquid chamber L through the valve seat member 20 and with the expansion-side chamber R1 through the hole 23b2, the valve hole 12b, and the piping 17.

[0037] 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 set arbitrarily as long as it does not interfere with the movement of the valve element 21 (described later) and its movement onto and off the valve seat 20d.

[0038] The valve body 21 includes a cylindrical 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 connected to the rear of the head 21a at the bottom in FIG. 3 and can be seated on and removed from the valve seat 20d, a cylindrical spring fitting portion 21c that extends from the bottom of the seat portion 21b in FIG. 3, and a cylindrical shaft portion 21d that extends from the bottom end of the spring fitting portion 21c in FIG. 3, has an outer diameter smaller than that of the spring fitting portion 21c, and slides against the inner periphery of the alignment portion 23c of the alignment member 23.

[0039] The outer diameter of the head 21a is smaller than the inner diameter of the small diameter portion 20b, and when the head 21a is inserted into the small diameter portion 20b, the valve body 21 forms a restricting flow path Pr in the annular gap between the outer periphery of the head 21a and the inner periphery of the small diameter portion 20b.

[0040] The seat portion 21b has an outer diameter larger than the outer diameter of the head portion 21a and the inner diameter of the valve seat 20d, and has a tapered surface whose outer diameter decreases toward the top in Fig. 3, with the tapered surface facing the valve seat 20d. The outer diameter of the seat portion 21b is larger than the inner diameter of the stopper 23b1 of the housing tube 23b, but smaller than the inner diameter of the housing tube 23b above the stopper 23b1 in Fig. 3.

[0041] Therefore, while housed within the housing cylinder 23b, the valve element 21 can move in the axial direction, which is the up-and-down direction in Fig. 3, and 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, causing the valve element 21 to close the communication passage 16. Furthermore, when the valve element 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 removed from the valve seat member 20, thereby fully opening the communication passage 16. In this state, because the head portion 21a of the valve element 21 is completely removed from the small diameter portion 20b, no restricting flow path Pr is formed between the valve element 21 and the valve seat member 20, and the valve V does not provide much resistance to the flow of liquid passing between the valve element 21 and the valve seat 20d. Even if the seat portion 21b is separated from the valve seat 20d, if the head portion 21a is partially 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 provides resistance to the flow of liquid passing through the restricted flow path Pr.

[0042] The outer diameter of the spring fitting portion 21c is smaller than the inner diameter of the housing tube 23b, forming an annular space between the spring fitting portion 21c and the housing tube 23b to accommodate the coil spring 22 serving as a biasing member, and fitting around the inner periphery 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 aligning portion 23c of the aligning member 23 in FIG. 3, and constantly biases the valve disc 21 in a direction to seat it on the valve seat 20d. Therefore, when no external force is applied to the valve disc 21, the valve disc 21 is biased by the coil spring 22 to a position where it seats on the valve seat 20d. Note that, because the coil spring 22 is fitted into the spring fitting portion 21c, it can apply a stable biasing force to the valve disc 21 without becoming eccentric.

[0043] The shaft portion 21d at the rear end of the valve disc 21 is slidably inserted into the inner periphery of the aligning portion 23c of the aligning member 23, and the valve disc 21 can move toward or away from the valve seat member 20, which is fitted into the fitting portion 23a of the aligning member 23, without axial wobble. Therefore, the head portion 21a of the valve disc 21 can smoothly move in and out of the small diameter portion 20b of the valve seat member 20 without interfering with the small diameter portion 20b.

[0044] The push rod 24 is rod-shaped and includes a main body 24a provided with a flange 24b that can abut against the end face of the large-diameter portion 20a of the valve seat member 20. The portion below the flange 24b in FIG. 3 is slidably inserted into the large-diameter portion 20a, and a pressing shaft 24c that extends axially from the lower end of the main body 24a and faces the upper end of the head 21a of the valve element 21 in FIG. 3. Even when the main body 24a enters the large-diameter portion 20a until the flange 24b abuts against the upper end of the large-diameter portion 20a in FIG. 3, the main body 24a does not face the hole 20c, so that the hole 20c is not blocked. The pressing shaft 24c has an outer diameter that is sufficiently smaller than the outer diameter of the head 21a of the valve element 21, so as not to provide resistance to the passage of liquid between the pressing shaft 24c and the small-diameter portion 20b when it enters the small-diameter portion 20b.

[0045] Furthermore, when the push rod 24 enters the large diameter portion 20a of the valve seat member 20 until the flange 24b abuts against the upper end of the large diameter portion 20a in Fig. 3, it abuts against the head 21a of the valve element 21 and pushes the valve element 21 downward in Fig. 3. Then, the valve element 21 moves away from the valve seat 20d, leaving a part of the head 21a inside the small diameter portion 20b.

[0046] The nut member 25 is cylindrical and has a threaded portion 25a on its outer periphery. The nut member 25 is threadedly coupled to the inner periphery of the upper end of the valve hole 12b (see FIG. 3 ) and attached to the housing main body 12. When attached to the valve hole 12b, the nut member 25 abuts against the outer periphery of the large-diameter portion 20a of the valve seat member 20 (see FIG. 3 ), sandwiching the valve seat member 20 and the aligning member 23 together with the step portion 12b1 to secure the valve seat member 20 and the aligning member 23 within the valve hole 12b. The nut member 25 also 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 axially (up and down in FIG. 3 ) from an uppermost position where the flange 24b abuts against the flange 25b of the nut member 25 to a lowermost position where the flange 24b abuts against the upper end of the large-diameter portion 20a of the valve seat member 20 (see FIG. 3 ).

[0047] The push rod 24 is connected via a wire (not shown) to a lever switch (not shown) provided near the handlebars of the saddle-riding vehicle M. When the driver of the saddle-riding vehicle M operates the lever switch to push the push rod 24 downward in Fig. 3, the push rod 24 pushes the valve body 21 downward in Fig. 3 against the biasing force of the coil spring 22, causing the valve body 21 to separate from the valve seat 20d and open the valve V. When the driver of the saddle-riding vehicle M operates the lever switch to move the push rod 24 upward in Fig. 3, the push rod 24 separates from the valve body 21, causing the biasing force of the coil spring 22 to push the valve body 21 upward in Fig. 3 and seat it on the valve seat 20d, closing the valve V. In this way, valve V is a normally closed valve that opens when the valve body 21 is pushed by operating the push rod 24, but closes when the pushing force of the push rod 24 is not acting, as the valve body 21 seats on the valve seat 20d due to the biasing force of the coil spring 22.

[0048] 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 compression-side chamber R2 is open to the atmosphere, and the extension-side chamber R1 is connected to the liquid chamber L pressurized by the air chamber G of the accumulator 10 via the communication passage 16. When the push rod 24 of the valve V is not operated and the push rod 24 does not apply a force that separates the valve body 21 from the valve seat 20d, and the valve V is closed, the communication between the extension-side chamber R1 and the liquid chamber L is cut off, and fluid exchange between the extension-side chamber R1 and the liquid chamber L is disabled. As a result, the cylinder device C is unable to perform either extension or contraction and becomes rod-shaped. On the other hand, when the push rod 24 in the valve V is operated to separate the valve element 21 from the valve seat 20d by the push rod 24 and open the valve V, the expansion-side chamber R1 and the liquid chamber L are connected, enabling fluid to flow between the expansion-side chamber R1 and the liquid chamber L, thereby enabling the cylinder device C to expand and contract. Furthermore, when the valve V is open, the compression-side chamber R2 is open to the atmosphere, and the pressure of the air chamber G is transmitted to the expansion-side chamber R1 to press the piston 3 toward the compression-side chamber R2, so the cylinder device C tries to contract while the valve V is open in a state where no external force is acting on it.

[0049] Based on the above, we will now explain the operation of the cylinder device C applied to the saddle-riding type vehicle M. First, when the valve V is closed, the cylinder device C becomes rod-shaped and cannot extend or retract. Therefore, when vibrations are input from the road surface while the saddle-riding type vehicle M is traveling and the swing arm S swings in the vertical direction in Figure 2 relative to the vehicle body B, the cylinder device C transmits the swing of the swing arm S to the link plate P, causing the shock absorber D to expand and contract, generating a damping force and suppressing vibration of the vehicle body B.

[0050] On the other hand, when the valve V is opened, a force in the extension direction acts on the telescopic body 1 due to the weight of the vehicle body B, and the pressure in the extension-side chamber R1 becomes greater than the pressure in the accumulator 10, so the cylinder device C extends to its maximum extent, and liquid moves from the extension-side chamber R1 to the liquid chamber L of the accumulator 10 via the communication passage 16 and the valve V. 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, and the vehicle height of the saddle-ride type vehicle M decreases by the amount of the decrease in distance.

[0051] When the valve V is opened, the push rod 24 separates the valve element 21 from the valve seat 20d but does not allow the head 21a to completely come out from inside the small diameter portion 20b of the valve seat member 20, so that a restricted flow path Pr is formed between the head 21a and the small diameter portion 20b. When the cylinder device C extends and liquid flows from the extension-side chamber R1 to the liquid chamber L, the high-pressure liquid pressed by the piston 3 passes between the valve element 21 and the valve seat 20d from the valve element 21 side toward the valve seat member 20 side and moves to the low-pressure liquid chamber L. Therefore, if the side of the valve element 21 facing the valve seat 20d is the front side and the opposite side is the back side, the valve element 21 is pressed toward the valve seat 20d by the pressure of the extension-side chamber R1, which is high pressure on the back side, and the valve element 21 does not move from the position where it is pressed by the push rod 24, and the head 21a is maintained in a state where it is inserted into the small diameter portion 20b. Therefore, the liquid flowing from the expansion-side chamber R1 to the liquid chamber L passes through the restrictor flow path Pr, and the flow of the liquid flowing from the expansion-side chamber R1 to the liquid chamber L is resisted by the restrictor flow path Pr.

[0052] In this way, when the valve V is opened, the cylinder device C receives the vehicle weight and the telescopic body 1 performs an extension operation, but because the restricting flow path Pr provides resistance to the flow of liquid, the extension speed becomes slower and the extension occurs slowly, and the vehicle height of the saddle riding type vehicle M also slowly decreases. Lowering the vehicle height on the rear wheel side of the saddle riding type vehicle M lowers the center of gravity of the vehicle, suppressing lift of the front wheel during acceleration and improving acceleration performance, so when accelerating, the driver can intentionally lower the vehicle height and improve acceleration performance by operating the lever switch to open the valve V. Furthermore, when lowering the vehicle height, the valve V provides resistance to the flow of liquid and slows the extension operation of the cylinder device C, thereby suppressing sudden changes in the vehicle body posture and improving handling stability.

[0053] Furthermore, as the telescopic body 1 extends from its fully contracted state, the liquid in the extension-side chamber R1 gradually moves to the liquid chamber L, and the free piston 14, which was at the discharge-side stroke end in the accumulator 10, moves in a direction that compresses the air chamber G. Then, when the telescopic body 1 extends to a certain extent, the free piston 14 eventually comes into contact with the cushion 15, and as the telescopic body 1 extends further, the free piston 14 moves further in a direction that compresses the air chamber G, thereby compressing the cushion 15. Then, the free piston 14 is restrained from moving in a direction that compresses the air chamber G by the force generated by the gas pressure in the air chamber G as well as the elastic force generated by the compression of the cushion 15. That is, in the accumulator 10, from the discharge-side stroke end until the free piston 14 abuts against the cushion 15, the free piston 14 is pressed in the direction of expanding the air chamber G only by the reaction force received from the gas in the air chamber G, but when the free piston 14 reaches the cushion 15 and moves further in the direction of compressing the air chamber G, the free piston 14 is pressed in the direction of expanding the air chamber G by the combined force of the reaction force of the gas and the elastic force generated by the cushion 15. Therefore, in the accumulator 10, the rate of change in the force pressing the free piston 14 in the direction of expanding the air chamber G relative to the displacement of the free piston 14 in the direction of compressing the air chamber G increases as shown in FIG. 4 midway between the fully contracted state and the fully extended state of the telescopic body 1, so that the moving speed of the free piston 14 and the extension speed of the telescopic body 1 can be decelerated. The force with which the accumulator 10 hinders the movement of the free piston 14 becomes even greater as the extension of the telescopic body 1 progresses, greatly reducing the extension speed of the telescopic body 1 and mitigating the impact when the piston 3 comes into contact with the rod guide 5 when the cylinder device C is fully extended.

[0054] In this way, the cylinder device C applied to the saddle-ride type vehicle M extends when the valve V is opened to lower the vehicle height on the rear wheel side, but the restricted flow path Pr of the valve V not only applies resistance to the flow of liquid to slow down the speed of lowering, but also increases the reaction force of the accumulator 10 midway, mitigating the impact when the telescopic body 1 is extended. Furthermore, when the valve V is closed while the cylinder device C is extended and the vehicle height is lowered, the liquid cannot move back and forth between the extension-side chamber R1 and the liquid chamber L, and the cylinder device C becomes a rod-shaped body, making it possible to maintain the vehicle height in a lowered state.

[0055] Furthermore, when the saddle-riding type vehicle M decelerates with the valve V open, the vehicle body B pitches forward and separates from the wheel W, and the force in the extension direction acting on the telescopic body 1 decreases, causing the pressure in the accumulator 10 to exceed the pressure in the extension-side chamber R1, resulting in a force in the contraction direction acting, and the cylinder device C contracts, causing the liquid to move from the fluid chamber L to the extension-side chamber R1 via 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, increasing the vertical distance between the vehicle body B and the wheel W, and the vehicle height of the saddle-riding type vehicle M increases by the amount of this increase in distance.

[0056] When the cylinder device C contracts and liquid flows from the liquid chamber L to the extension-side chamber R1, the liquid in the liquid chamber L, under the pressure of the air chamber G, moves from the valve seat member 20 side toward the valve element 21 side, passing between the valve element 21 and the valve seat 20d, and into the low-pressure extension-side chamber R1. Therefore, the valve element 21 receives pressure from the high-pressure liquid chamber L from the front side and retreats from the valve seat 20d to a position restricted by the stopper 23b1, causing the head portion 21a to completely come out of the small diameter portion 20b, maximizing the opening area of ​​the valve V. When the head portion 21a comes out of the valve seat member 20, no restrictive flow path Pr is formed between the head portion 21a and the valve seat member 20, and the valve V allows the flow of liquid from the liquid chamber L to the extension-side chamber R1 with almost no resistance.

[0057] In this way, when the liquid flows from the liquid chamber L to the extension-side chamber R1, almost no resistance is applied to the flow of the liquid, unlike when the liquid flows from the extension-side chamber R1 to the liquid chamber L, so the cylinder device C contracts quickly and the vehicle height of the saddle-riding type vehicle M is quickly raised. If the vehicle height of the rear wheel side of the saddle-riding type vehicle M is raised, lift-up of the rear wheel from the road surface during braking is suppressed, improving vehicle body stability during braking. Therefore, when braking, the driver can intentionally raise the vehicle height by operating the lever switch to open the valve V, thereby improving vehicle body stability during braking.

[0058] When raising the vehicle height, the valve V provides almost no resistance to the flow of liquid, allowing the cylinder device C to quickly contract, thereby immediately preventing the wheel W from lifting off the road surface during braking. If the valve V is closed while the cylinder device C is contracted and the vehicle height is raised, liquid cannot pass between the expansion-side chamber R1 and the liquid chamber L, and the cylinder device C becomes a rod-shaped body, allowing the vehicle height to be maintained at a raised state.

[0059] As described above, the accumulator 10 of this embodiment comprises a hollow housing 11, a free piston (partition member) 14 that is accommodated within the housing 11, divides the interior of the housing 11 into an air chamber G and a liquid chamber L, and can move within 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 accommodated within the air chamber G and that, when it comes into contact with the free piston (partition member) 14, suppresses movement of the free piston (partition member) 14 in a direction that reduces the volume of the air chamber G. The cushion (elastic body) 15 is spaced apart 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, suppressing movement of the free piston (partition member) 14.

[0060] In the accumulator 10 configured in this manner, when the free piston (partition member) 14 is displaced in a direction compressing the air chamber G from a position where the volume of the air chamber G is maximized, the cushion (elastic body) 15 is compressed along 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, increasing the pressurizing force and slowing down the speed of movement of the free piston (partition member) 14 in the direction compressing the air chamber G. Therefore, in the accumulator 10 of this embodiment, even without increasing the pressure of the gas in the air chamber G, the elastic force of the cushion (elastic body) 15 is applied to the free piston (partition member) 14 as it moves, thereby achieving the characteristic of increasing the pressurizing force as the air chamber G is compressed, and the free piston (partition member) 14 can be stopped slowly. In addition, since there is no need to create high pressure inside the air chamber G, there is no need to increase the contact surface pressure of the seal ring 14a with 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 when the free piston (partition member) 14 begins to compress the air chamber G, which has the advantage that the telescopic body 1 can also perform a smooth extension operation.

[0061] Furthermore, in the accumulator 10 of this embodiment, the partition member is the free piston 14, and the elastic body is a resin cushion 15. In the accumulator 10 configured in this manner, because the elastic body is the resin cushion 15, when the free piston 14 comes into contact with the cushion 15 and then displaces in the compression direction, an unbalanced load that would occur in a case where the elastic body is a coil spring is not applied to the free piston 14, and the free piston 14 is not tilted relative to the housing 11 due to the elastic force received from the cushion 15, so the free piston 14 can be displaced smoothly relative to the housing 11, and no pressure force due to uncontrollable stick-slip is generated.

[0062] Furthermore, since the cushion (elastic body) 15 in the accumulator 10 of this embodiment is made of urethane foam, it contains countless air bubbles and occupies a small volume within the air chamber G. As a result, the rate at which the volume within the air chamber G decreases is small, the volume within the air chamber G can be secured, and the change in the volume within the air chamber G relative to the displacement of the free piston (partition member) 14 is small, making it easy to tune the pressurization characteristics of the accumulator 10.

[0063] Furthermore, the housing 11 in the accumulator 10 of this embodiment has a cylindrical housing body 12 and a cap 13 that closes the opening of the housing body 12 on the air chamber side, and 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, and the cushion (elastic body) 15 is cylindrical and is fitted onto the outer periphery of the valve case (protrusion) 13b.

[0064] In the accumulator 10 configured in this manner, the cushion (elastic body) 15 is fixed within the air chamber G using the valve case 13b, so that the cushion (elastic body) 15 is positioned so as not to interfere with the air valve 13c filling the air chamber G with gas, and the air valve 13c and the cushion (elastic body) 15 can be installed comfortably within the narrow accumulator 10. Note that the cap 13 integrally includes the lid portion 13a and the valve case 13b as a protruding portion, but the lid portion 13a and the valve case 13b may be formed as separate parts.

[0065] Furthermore, the accumulator 10 of this embodiment includes an annular adjusting shim 19 that is sandwiched between the cushion (elastic body) 15 and the lid portion 13a on the outer periphery of the valve case (protruding portion) 13b. With the accumulator 10 configured in this manner, it is possible to adjust the contact position of the cushion (elastic body) 15 with the free piston (partition member) 14, and because the adjusting shim 19 is fixed using the cushion (elastic body) 15, there is no need to add a part to fix the adjusting shim 19.

[0066] The cylinder device C of this embodiment has a cylinder 2, a piston 3 that is movably inserted into the cylinder 2 and divides the inside of the cylinder 2 into an extension-side chamber R1 and a compression-side chamber R2, and a rod 4 that is movably inserted into the cylinder 2 and connected to the piston 3, and is equipped with an expandable body 1 in which the compression-side chamber R2 is open to the atmosphere and the extension-side chamber R1 is filled with liquid, an accumulator 10, and a communication passage 16 that connects the liquid chamber L to the extension-side chamber R1.

[0067] In the cylinder device C configured in this manner, the compression-side chamber R2 is open to the atmosphere and the pressure of the air chamber G acts on the extension-side chamber R1, thereby generating a spring force that contracts the telescopic body 1. As the telescopic body 1 undergoes an extension operation from the fully contracted state due to an external force and the extension of the telescopic body 1 progresses, the pressurizing force of the accumulator 10 increases, decelerating the extension speed at the extension-side stroke end where the telescopic body 1 is fully extended, thereby mitigating the impact at the time of full extension. In this way, in the cylinder device C, as the air chamber G is compressed, the pressurizing force of the accumulator 10 increases before the telescopic body 1 is fully compressed, so that the impact at the time of full extension can be mitigated without providing other systems such as a cushion or hydraulic locking mechanism inside the telescopic body 1. This allows the telescopic body 1 to be made smaller and improves the mountability in equipment where it is difficult to secure installation space, such as a saddle-type vehicle M.

[0068] Also, the extension-side chamber R1 may be open to the atmosphere, and the compression-side chamber R2 and the liquid chamber L may be connected by a communication passage 16. In this case, the cylinder device C exerts a spring force that extends the telescopic body 1, and when the telescopic body 1 contracts from the fully extended state due to an external force and the contraction of the telescopic body 1 progresses, liquid flows from the compression-side chamber R2 into the liquid chamber L, and the free piston 14 moves from the discharge-side stroke end in a direction that compresses the air chamber G. Therefore, in this case, the cylinder device C reduces the contraction speed at the contraction-side stroke end where the telescopic body 1 contracts to the fullest extent because the pressure force of the accumulator 10 increases as the telescopic body 1 contracts, thereby mitigating the impact at the fullest contraction. 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 fully compressed, so that the impact at the time of full contraction can be mitigated without providing other systems such as a cushion or hydraulic locking mechanism inside the telescopic body 1. This makes it possible to make the telescopic body 1 smaller and improves its mountability on equipment where it is difficult to secure installation space, such as a saddle-type vehicle M.

[0069] In addition, the cylinder device C of this embodiment is provided with a valve V that is provided in the communication passage 16 and is capable of opening and closing the communication passage 16, and when open, provides resistance to the flow of liquid in one direction through the communication passage 16 and is fully open to the flow of liquid in the other direction.

[0070] In this embodiment, the cylinder device C has the compression-side chamber R2 open to the atmosphere, and when the valve V is opened, the pressure of the air chamber G acts on the extension-side chamber R1, thereby generating a spring force that contracts the telescopic body 1. Furthermore, when the valve V is open, the cylinder device C applies resistance to the flow of liquid from the extension-side chamber R1 to the liquid chamber L through the restrictor flow path Pr, and applies almost no resistance to the flow of liquid from the liquid chamber L to the extension-side chamber R1. Therefore, when an extension operation is performed by an external force, the operation is slow, allowing the telescopic body 1 to be extended slowly, and when a contraction operation is performed spontaneously or by an external force, the operation is quick, allowing the telescopic body 1 to be contracted quickly.

[0071] Furthermore, if the compression-side chamber R2 is released to the atmosphere, the extension-side chamber R1 and the liquid chamber L are connected by the communication passage 16, and the installation direction of the valve V relative to the communication passage 16 is reversed, the cylinder device C will exert a spring force that contracts the telescopic body 1 when the valve V is open, and the valve V will provide resistance to the flow of liquid from the liquid chamber L to the extension-side chamber R1 through the restriction flow path Pr, while providing almost no resistance to the flow of liquid from the extension-side chamber R1 to the liquid chamber L. Therefore, when contracting spontaneously or due to an external force, the operation will be slow, allowing the telescopic body 1 to contract slowly, and when extending due to an external force, the operation will be quick, allowing the telescopic body 1 to extend quickly.

[0072] Alternatively, the expansion-side chamber R1 may be opened to the atmosphere, the compression-side chamber R2 and the liquid chamber L may be connected by the communication passage 16, and when the valve V is open, the restrictor flow path Pr may provide resistance to the flow of liquid from the compression-side chamber R2 to the liquid chamber L, so that almost no resistance is provided to the flow of liquid from the liquid chamber L to the expansion-side chamber R2. In this way, the cylinder device C exerts a spring force that extends the telescopic body 1 when the valve V is open, and operates slowly when contracting due to an external force, thereby slowly contracting the telescopic body 1, and operates quickly when extending spontaneously or due to an external force, thereby quickly extending the telescopic body 1.

[0073] Furthermore, the expansion-side chamber R1 may be opened to the atmosphere, the compression-side chamber R2 and the liquid chamber L may be connected by the communication passage 16, and when the valve V is open, the restrictor flow path Pr may provide resistance to the flow of liquid from the liquid chamber L to the expansion-side chamber R2, and almost no resistance may be provided to the flow of liquid from the compression-side 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 open, and operates slowly to slowly extend the telescopic body 1 when the telescopic body 1 is expanded spontaneously or by an external force, and operates quickly to quickly contract the telescopic body 1 when the telescopic body 1 is contracted by an external force.

[0074] In this way, the cylinder device C can slow down either the extension or contraction operation, and not only can the operation speed be polarized depending on the direction of operation, but also the number of parts and costs can be reduced.

[0075] Furthermore, the telescopic body 1 in the cylinder device C of this embodiment is spanned across a link plate P that is rotatably connected to the lower end of a shock absorber D interposed between the body B and wheel W of the saddle-riding vehicle M, the body B of the saddle-riding vehicle M, and a swing arm S that is swingable relative to the body B of the saddle-riding vehicle M and holds the wheel W, the compression side chamber R2 is open to the atmosphere and the extension side chamber R1 is filled with liquid, and the valve V provides resistance to the flow of liquid when the telescopic body 1 is extended, and is fully open when the telescopic body 1 is contracted. The cylinder device C configured in this manner can adjust the vehicle height on the rear wheel side of the saddle-riding vehicle M by opening and closing the valve V, and when the vehicle height on the rear wheel side is lowered during acceleration of the saddle-riding vehicle M, the valve V provides resistance to the flow of liquid, reducing acceleration due to low vehicle height, and the impact when the telescopic body 1 is fully extended can be mitigated by the pressure force of the accumulator 10, improving handling stability. Furthermore, when the vehicle height rises during braking, the valve V does not provide resistance to the flow of liquid, so the telescopic body 1 quickly contracts and the vehicle height rises quickly, improving vehicle stability during braking.

[0076] Furthermore, the valve V of the cylinder device C in this embodiment comprises a cylindrical valve seat member 20 having an annular valve seat 20d at one axial end, a valve disc 21 having a head 21a that can move in and out of the valve seat member 20 and an annular seat portion 21b that is connected to the rear of the head 21a and can be seated on and off the valve seat 20d, a coil spring (biasing member) 22 that biases the valve disc 21 toward the valve seat member 20, a restricting flow path Pr that is formed when the head 21a is inserted into the valve seat member 20, and when the seat portion 21b moves away from the valve seat 20d to open the valve, the entire head 21a comes out of the valve seat member 20 to fully open the valve, preventing a flow from the valve seat member side to the valve disc side, and the restricting flow path Pr provides resistance to a flow from the valve disc side to the valve seat member side with at least a part of the head 21a inserted into the valve seat member 20.

[0077] With the valve V configured in this manner, when the valve is open, the head 21a completely separates from the valve seat member 20, forming no restricting flow path Pr and providing almost no resistance to the flow of liquid passing through it from the valve seat member side to the valve disc side. Meanwhile, the restricting flow path Pr provides resistance to the flow of liquid passing through it from the valve disc side to the valve seat member side. In this way, the valve V can independently function as a check valve for the flow of liquid in one direction and as a valve that provides resistance to the flow of liquid in the other direction. Therefore, while conventional valves require a check valve and a valve that provides resistance in parallel, the valve V of this embodiment can independently function as both a check valve and a valve that provides resistance. As described above, the valve V of this embodiment can provide resistance to the flow in one direction but not the flow in the other direction when the valve is open, without increasing the number of parts or costs.

[0078] While the valve seat member 20 has the large diameter portion 20a and the small diameter portion 20b as described above, it is sufficient that the valve seat member 20 has at least the small diameter portion 20b that has the valve seat 20d at one axial end and allows the head 21a of the valve element 21 to move in and out, and other structural design changes can be made as desired for the valve seat member 20. Furthermore, although the biasing member is the coil spring 22, it may be a spring or elastic body other than a coil spring as long as it is capable of biasing the valve element 21 in the direction of seating it on the valve seat 20d.

[0079] Furthermore, in the valve V of this embodiment, the restricting flow path Pr is formed by an annular gap between the outer periphery of the head 21a of the valve element 21 and the inner periphery of the valve seat member 20. With the valve V configured in this manner, the annular gap formed between the head 21a and the valve seat member 20 prevents them from contacting each other, and therefore when the valve element 21 moves axially relative to the valve seat member 20 and the head 21a moves in and out of the valve seat member 20, the head 21a does not interfere with the valve seat member 20, allowing for smooth opening and closing of the valve.

[0080] Furthermore, the valve V of this embodiment is provided with an aligning member 23 that aligns the valve disc 21 with respect to the valve seat member 20 while allowing the valve disc 21 to move in the axial direction. With the valve V thus provided with the aligning member 23 that aligns the valve disc 21, the valve disc 21 can move in the axial direction without axial wobble when the head 21a of the valve disc 21 moves in and out of the valve seat member 20, so there is no need to worry about the head 21a scraping against the inner peripheral surface of the valve seat member 20, ensuring smooth axial movement of the valve disc 21 and allowing for smooth opening and closing of the valve.

[0081] In the valve V of this embodiment, the valve disc 21 is provided with a shaft portion 21d on the side opposite the valve seat, and the aligning member 23 is provided with an annular aligning portion 23c into which the shaft portion 21d is slidably inserted, but it is also possible to provide a hole along the axial direction on the valve disc 21 side and a shaft to be inserted into the hole in the valve disc 21 on the aligning member 23 side to align the valve disc 21 with the valve seat member 20, or the aligning member 23 may be provided on the housing main body 12. Also, a hole along the axial direction may be provided at the tip of the head 21a, and a shaft to be inserted into the hole in the head 21a may be provided at the tip of the push rod 24, and this shaft may serve as the aligning member.

[0082] However, as mentioned above, if the aligning member 23 is cylindrical and fits into the small-diameter portion 20b of the valve seat member 20 to accommodate the valve disc 21, and the aligning portion 23c of the aligning member 23 is configured to align the valve disc 21 and function as a spring retainer for the coil spring (biasing member) 22 that biases the valve disc 21, then the components that make up the valve V can be assembled and accommodated in the valve hole 12b in advance, making assembly of the valve V easier, and since the aligning member 23 and valve disc 21 can be assembled using the valve seat member 20 as a base, there are the advantages that it is easier to align the valve disc 21 with the valve seat member 20.

[0083] In the above description, the restricting flow path Pr is formed by an annular gap between the outer periphery of the head 21a of the valve disc 21 and the inner periphery of the valve seat member 20. However, as in the valve V1 of a first modified example of an embodiment shown in Fig. 5, the outer periphery of the head 21a may be in sliding contact with the inner periphery of the small-diameter portion 20b of the valve seat member 20, and a groove 21a1 may be formed on the outer periphery of the head 21a along the axial direction, so that the restricting flow path Pr is formed by the groove 21a1 formed in the head 21a until the seat portion 21b separates from the valve seat 20d and the head 21a completely leaves the small-diameter portion 20b. In this case, the valve disc 21 is aligned with the valve seat member 20 by the aligning member 23, so that even if the head 21a leaves the inner periphery of the valve seat member 20, the head 21a can re-enter the valve seat member 20 and close the valve V. Therefore, when the aligning member 23 is provided, the restricting flow path Pr may be formed by the groove 21a1 formed on the outer periphery of the head 21a. 6, a passage 21a2 may be formed in place of the groove 21a1, opening from the tip end of the head portion 21a to the base end of the head portion 21a, and the restriction flow path Pr may be formed by the passage 21a2. When the restriction flow path Pr is formed by the passage 21a2 in this manner, the flow path length of the restriction flow path Pr does not change until the head portion 21a is completely removed from the small diameter portion 20b, and the resistance that the restriction flow path Pr provides to the flow of liquid does not change.

[0084] In addition, the accumulator 10 can be used as an accumulator for various hydraulic circuits other than the cylinder device C described above, and the cylinder device C may also be used for a cylinder device other than one used for adjusting the vehicle height of a saddle-type vehicle M.

[0085] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims.

[0086] 1... Telescopic body, 2... Cylinder, 3... Piston, 4... Rod, 10... Accumulator, 11... Housing, 12... Housing body, 13... Cap, 13a... Lid portion, 13b... Valve case (protruding portion), 13c... Air valve, 14... Free piston (partition member), 15... Cushion (elastic body), 16... Connecting passage, 19... Adjusting shim, B... Vehicle body, C... Cylinder device, G... Air chamber, L... Fluid chamber, M... Saddle-ride type vehicle, P... Link plate, Pr... Restricted flow passage, R1... Extension side chamber, R2... Compression side chamber, S... Swing arm, V, V1, V2... Valve, W... Wheel

Claims

1. An accumulator comprising: a hollow housing; a partition member contained within said housing, dividing the interior of said housing into an air chamber and a liquid chamber and capable of moving within said housing to change the volume distribution between the air chamber and the liquid chamber; and an elastic body contained within said air chamber and which suppresses movement of the partition member in a direction decreasing the volume of the air chamber when it abuts against the partition member, wherein the elastic body is spaced 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 movement of the partition member.

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

3. The accumulator according to claim 1, characterized in that the elastic body is made of urethane foam.

4. An accumulator as described in claim 1, characterized in that the housing has a cylindrical housing body and a cap closing an opening of the housing body on the air chamber side, the cap having a lid portion closing the opening of the housing body and a protrusion rising from the lid portion, and the elastic body is cylindrical and fitted onto the outer periphery of the protrusion.

5. The accumulator according to claim 4, further comprising an annular adjustment shim that is disposed on the outer periphery of said protruding portion and is held between said elastic body and said lid portion.

6. A cylinder device comprising: a cylinder, a piston movably inserted into the cylinder and dividing the interior of the cylinder into an extension-side chamber and a compression-side chamber, and a rod movably inserted into the cylinder and connected to the piston, wherein one of the extension-side chamber and the compression-side chamber is open to the atmosphere and the other of the extension-side chamber and the compression-side chamber is filled with liquid; an accumulator as described in any one of claims 1 to 5; a communication passage connecting the liquid chamber to the other of the extension-side chamber and the compression-side chamber; and a valve provided in the communication passage and capable of opening and closing the communication passage, which, when open, provides resistance to the flow of liquid in one direction through the communication passage and is fully open to the flow of liquid in the other direction.

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