buffer

Abstract

To provide a shock absorber that can change only the damping force during extension or contraction even if comprising a needle valve.SOLUTION: A shock absorber D comprises: a cylinder 1; a piston 2 that is inserted into the cylinder 1 so as to be movable in an axial direction; a piston rod 3 that is inserted into the cylinder 1 and connected to the piston 2; a shock absorber body DB having a plurality of working chambers R2, 4 filled with liquid; a first path P1 and a bypass path PB that allow communication between the working chambers R2, 4; a damping valve 5 that is provided in the first path P1, and applies resistance to a flow of liquid from one working chamber R2 to another working chamber 4; a check valve 6 that is provided in the bypass path PB, and allows only a flow of liquid from the one working chamber R2 to the other working chamber 4; and a needle valve 7 that is provided in series with the check valve 6 in the bypass path PB, and capable of changing the area of a flow path.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

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

[0003] Such a shock absorber includes, for example, a cylinder, a piston movably inserted into the cylinder and partitioning the inside of the cylinder into an extension chamber and a compression chamber filled with hydraulic oil, a piston rod movably inserted into the cylinder and connected to the piston, a tank for storing hydraulic oil, and a side damping valve provided on the piston to resist the flow of hydraulic oil from the extension chamber to the compression chamber stretch a compression check valve provided on the piston to allow only the flow of hydraulic oil from the compression chamber to the extension chamber, a compression damping valve to resist the flow of hydraulic oil from the compression chamber to the tank, an extension check valve to allow only the flow of hydraulic oil from the tank to the compression chamber, and a needle valve provided in parallel with the compression damping valve and the extension check valve to resist the flow of hydraulic oil from the compression chamber to the tank (see, for example, Patent Document 1).

[0004] In the shock absorber configured as described above, an adjuster for operating the needle valve externally is provided, and by adjusting the flow passage area of the needle valve by operating the adjuster, the damping force generated during contraction can be adjusted up and down.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In conventional shock absorbers, the damping force during shock absorber contraction can be adjusted by adjusting the flow area of ​​the needle valve. However, since the needle valve only restricts the flow path, it allows the hydraulic fluid to flow not only from the pressure chamber to the tank, but also from the tank to the pressure chamber.

[0007] Therefore, in conventional shock absorbers, if the damping force during compression is adjusted by changing the flow area of ​​the needle valve, the resistance that the needle valve exerts on the flow of hydraulic fluid from the tank to the pressure chamber during shock absorber extension also changes, thus altering the damping force characteristics during shock absorber extension.

[0008] This is also true for shock absorbers that have a passage in the piston rod that bypasses the damping valve provided in the piston and connects the extension chamber and the compression chamber, and that houses a needle valve in this passage. In such cases, the needle valve allows the hydraulic fluid to pass in both directions between the extension chamber and the compression chamber, so any change in the flow area of ​​the needle valve will cause a change in the damping force when the shock absorber is extended and when it is retracted.

[0009] Therefore, the present invention aims to provide a shock absorber that, even when equipped with a needle valve, can change only the damping force during extension or contraction. [Means for solving the problem]

[0010] To solve the aforementioned problems, the shock absorber of the present invention comprises a shock absorber body having a cylinder, a piston inserted into the cylinder so as to be axially movable, a piston rod inserted into the cylinder and connected to the piston, and a plurality of working chambers filled with liquid, Working chambers The system includes a first passage and a bypass passage connecting the two, a damping valve provided in the first passage that resists the flow of liquid from one working chamber to the other, a check valve provided in the bypass passage that allows only the flow of liquid from one working chamber to the other, and a needle valve provided in series with the check valve in the bypass passage that can change the flow area.

[0011] In a buffer configured in this way, the check valve blocks the bypass path during either the extension or contraction stroke of the buffer. Therefore, the needle valve can adjust only the damping force during the other extension or contraction stroke of the buffer without affecting the damping force during the other stroke.

[0012] Furthermore, the buffer may be configured such that the buffer body has an extension chamber and a compression chamber partitioned by a piston within a cylinder, and a tank for storing liquid, and includes a second passage and a third passage that connect the extension chamber and the compression chamber in parallel, a suction passage that connects the compression chamber and the tank, an extension damping valve provided in the second passage that resists the flow of liquid from the extension chamber to the compression chamber, a compression check valve provided in the third passage that allows only the flow of liquid from the compression chamber to the extension chamber, and an extension check valve provided in the suction passage that allows only the flow of liquid from the tank to the compression chamber, and the first passage and bypass passage connect the compression chamber and the tank with the working chamber being the compression chamber and the tank, the damping valve resists the flow of liquid while allowing only the flow of liquid from the compression chamber to the tank, and the check valve allows only the flow of liquid from the compression chamber to the tank. In a shock absorber configured in this way, the bypass passage is blocked by a check valve during the extension stroke. This prevents the hydraulic fluid from moving to the pressure chamber through the bypass passage when the extension speed is extremely low, allowing the pressure in the pressure chamber to decrease rapidly, thereby improving the damping force generation response.

[0013] Furthermore, the buffer includes a housing that accommodates a check valve and a needle valve, the needle valve includes a cylindrical needle case inserted into the housing and a needle inserted into the needle case so as to be movable in the axial direction, the needle case has an annular recess formed at one end by an enlarged inner diameter, the check valve includes a disc-shaped valve seat member sandwiched between one end of the needle case and the housing, facing the annular recess and in close contact with the needle case and the housing, and having a hole that penetrates its wall thickness, an annular valve body housed in the annular recess so as to be movable in the axial direction and seating away from the valve seat member, and an annular biasing member housed in the annular recess and biasing the annular valve body toward the valve seat member, and the bypass passage may connect the pressure side chamber and the tank through the hole and the inside of the needle case. With a buffer configured in this way, it is possible to prevent the hydraulic fluid from passing through the bypass passage during the extension stroke of the buffer, without providing seals between the valve seat member and the needle case, and between the valve seat member and the housing, and also to prevent the hydraulic fluid from moving from the pressure chamber to the tank without passing through the check valve and needle valve during the contraction stroke of the buffer.

[0014] Furthermore, the needle case in the buffer may have an annular valve seat on its inner circumference for seating the needle. With a buffer configured in this way, the needle case not only functions as the case for the needle valve that houses the needle and has an annular valve seat, but also as the case for housing the annular valve body and biasing member. Therefore, the check valve and the needle valve can be placed in series very close together, and the overall size of the check valve and needle valve can be reduced. Thus, with a buffer configured in this way, even if a check valve and a needle valve are included, an increase in size can be avoided.

[0015] In addition, the annular valve body and the biasing member in the shock absorber may be positioned radially by the side wall surface of the annular recess in the needle case. According to the shock absorber configured as described above, when the entire annular valve body separates from the valve seat member and reseats, axial displacement of the annular valve body and the biasing member in the radial direction is suppressed, so that the operation of the annular valve body is stabilized and the hole can be stably closed when the annular valve body seats on the annular valve seat.

Advantages of the Invention

[0016] According to the tubular linear motor of the present invention, the mass thrust density can be improved.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a longitudinal sectional view of a shock absorber in one embodiment as seen from the front. [Figure 2] FIG. 2 is a view showing a reaction unit attached to a straddle-type vehicle. [Figure 3] FIG. 3 is a longitudinal sectional view of a shock absorber in one embodiment as seen from the side. [Figure 4] FIG. 4 is a hydraulic circuit diagram of a shock absorber in one embodiment. [Figure 5] FIG. 5 is a sectional view of a check valve and a needle valve of a shock absorber in one embodiment. [Figure 6] FIG. 6 is a sectional view of a damping valve of a shock absorber in one embodiment. [Figure 7] FIG. 7 is a sectional view of a modified example of a check valve and a needle valve of a shock absorber in one embodiment. [Figure 8] FIG. 8 is a schematic longitudinal sectional view of a first modified example of a shock absorber in one embodiment.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2, a shock absorber D in one embodiment includes a cylinder 1, a piston 2 that is movably inserted into the cylinder 1 and partitions the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2 filled with liquid, a piston rod 3 that is movably inserted into the cylinder 1 and connected to the piston 2, and a shock absorber main body DB including a tank 4 for storing liquid. A first passage P1 and a bypass passage PB that communicate the compression chamber R2 and the tank 4 as working chambers to each other, a compression-side damping valve 5 as a damping valve provided in the first passage P1 to resist the flow of liquid from the compression chamber R2 as one working chamber to the tank 4 as the other working chamber, a check valve 6 provided in the bypass passage PB to allow only the flow of liquid from the compression chamber R2 to the tank 4, and a needle valve 7 provided in series with the check valve 6 in the bypass passage PB and capable of changing the flow area are provided.

[0019] And, as shown in FIG. 2, this shock absorber D is interposed and used between the vehicle body F and the rear wheel W in a saddle-type vehicle M such as a motorcycle, and suppresses the vibrations of the vehicle body F and the rear wheel W. Note that the shock absorber D may be used to suppress vibrations other than in the saddle-type vehicle M.

[0020] The following describes in detail each part of the buffer D. As shown in Figure 1, the buffer body DB of this embodiment comprises a cylinder 1, a piston 2 which is movably inserted into the cylinder 1 and divides the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2 which are filled with liquid, a piston rod 3 which is movably inserted into the cylinder 1 and connected to the piston 2, and a tank 4 for storing liquid. Furthermore, as shown in the circuit diagram in Figure 4, the buffer D of this embodiment includes, in addition to the buffer body DB, the first passage P1, the bypass passage PB, the pressure-side damping valve 5, the check valve 6, and the needle valve 7, a second passage P2 and a third passage P3 that connect the extension-side chamber R1 and the pressure-side chamber R2 in parallel, respectively, a suction passage P4 that connects the pressure-side chamber R2 and the tank 4, an extension-side damping valve 8 provided in the second passage P2 that provides resistance to the flow of liquid from the extension-side chamber R1 to the pressure-side chamber R2, a pressure-side check valve 9 provided in the third passage P3 that allows only the flow of liquid from the pressure-side chamber R2 to the extension-side chamber R1, and an extension-side check valve 10 provided in the suction passage P4 that allows only the flow of liquid from the tank 4 to the pressure-side chamber R2.

[0021] An upper cap 11 is attached to the upper end of cylinder 1 in Figure 1 by screw fastening, and the opening at the upper end of cylinder 1 is closed by the upper cap 11.

[0022] Furthermore, a rod guide 15, which is annular in shape and through which the piston rod 3 is inserted, is attached to the lower end of cylinder 1 in Figure 1. The rod guide 15 slides against the outer circumference of the piston rod 3 and guides the axial movement of the piston rod 3 relative to cylinder 1.

[0023] Furthermore, an annular sealing member 16 is attached to the lower end of the rod guide 15 in Figure 1. The sealing member 16 slides against the outer circumference of the piston rod 3, which is inserted through the inner circumference, sealing the space between the piston rod 3 and the rod guide 15, thereby sealing the inside of the cylinder 1. Note that the sealing member 16 may be attached to the cylinder 1 instead of the rod guide 15. Also, the means for fixing the rod guide 15 and the sealing member 16 to the cylinder 1 can be arbitrarily changed in design.

[0024] The inside of cylinder 1 is divided by piston 2 into an extension chamber R1 and a compression chamber R2, both of which are filled with liquid. In this embodiment, the liquid is hydraulic fluid, but other liquids such as water or aqueous solutions can also be used.

[0025] A bracket B1 is attached to the lower end of the piston rod 3, which is inserted into the cylinder 1 and connected to the piston 2, in Figure 1. This bracket B1 can be connected to the swing arm SA that holds the rear wheel W in the saddle-type vehicle M.

[0026] The piston 2 is provided with a second passage P2 and a third passage P3 that connect the extension chamber R1 and the compression chamber R2 in parallel. Furthermore, the piston 2 is provided with an extension damping valve 8 that can open and close the second passage P2 and resist the flow of hydraulic fluid from the extension chamber R1 to the compression chamber R2, and a compression check valve 9 that can open and close the third passage P3 and allow only the flow of hydraulic fluid from the compression chamber R2 to the extension chamber R1.

[0027] The extension damping valve 8 is a valve that can exert a damping force that prevents the extension of the shock absorber D during its extension stroke by resisting the flow of hydraulic fluid from the extension chamber R1 to the compression chamber R2. Specifically, the extension damping valve 8 is a laminated leaf valve constructed by stacking multiple annular plates on the upper end of the piston 2 in Figure 1, with the inner circumference fixed and the outer circumference bending due to the pressure in the extension chamber R1, thereby opening the second passage P2.

[0028] Furthermore, the compression check valve 9 only needs to be a valve that can allow the flow of hydraulic fluid from the compression chamber R2 to the extension chamber R1 without much resistance during the contraction stroke of the shock absorber D. Specifically, the compression check valve 9 is composed of a leaf valve that is superimposed on the lower end of the piston 2 in Figure 1 and has its inner circumference fixed, and is a valve that opens the second passage P2 when its outer circumference bends due to the pressure in the compression chamber R2.

[0029] In this embodiment, as shown in Figures 1 and 3, the upper cap 11 comprises a cap portion 11a mounted on the upper end of the cylinder 1 in Figure 1, a tank holding portion 11b for holding the tank 4, a cylindrical connecting portion 11c extending from the side of the cap portion 11a and connected to the tank holding portion 11b, a cylindrical first housing 11d provided between the connecting portion 11c and the tank holding portion 11b to house a first valve unit V1 equipped with a check valve 6 and a needle valve 7, and a cylindrical second housing 11e provided between the connecting portion 11c and the tank holding portion 11b to house a second valve unit V2 equipped with a compression damping valve 5 and an extension check valve 10.

[0030] The cap portion 11a is a top-shaped cylindrical part that is screw-fastened to the upper end of the cylinder 1 in Figure 1, closing the upper end of the cylinder 1. It also has a bracket B2 at its top, which is located above in Figure 1 and can be connected to the body F of a saddle-type vehicle M. The connecting portion 11c is cylindrical and protrudes from the side of the cap portion 11a, curving downward in Figure 3 and connected to a socket-shaped tank holding portion 11b via a first housing 11d and a second housing 11e. The inside of the connecting portion 11c is in communication with the pressure chamber R2 inside the cylinder 1 via the inside of the cap portion 11a.

[0031] The tank holding portion 11b is cylindrical with a top end, and its upper end is integrally connected to the first housing 11d and the second housing 11e. It has a threaded portion 11b3 on the inner circumference of its lower end. The cylindrical tank 4 is screwed onto the threaded portion 11b3 on the inner circumference of the lower end of the tank holding portion 11b.

[0032] In this embodiment, the tank 4 is cylindrical and screwed onto the tank holding portion 11b. A free piston 12 is slidably inserted into the tank 4, and the tank 4 is divided by the free piston 12 into a liquid chamber L filled with hydraulic fluid and an air chamber G filled with gas. The air chamber G is filled with gas such that the pressure inside the air chamber G is at least equal to atmospheric pressure when the buffer D is fully extended. In addition to using the free piston 12, the partition between the liquid chamber L and the air chamber G in the tank 4 may also be achieved by using a diaphragm, bladder, or the like.

[0033] The liquid chamber L in the tank 4 is connected to the first housing 11d via a port 11b1 provided in the tank holding portion 11b, and is also connected to the second housing 11e via a port 11b2 provided inside the tank holding portion 11b.

[0034] As shown in Figure 3, the first housing 11d is cylindrical with a closed lower end that forms the bottom, and is integrally provided along the vertical direction to the side of the connecting portion 11c, with the lower end that forms the bottom being integrated with the connecting portion 11c and the tank holding portion 11b. The second housing 11e, as shown in Figure 1, is cylindrical with a closed bottom, and is provided laterally between the lower end of the connecting portion 11c and the upper end of the tank holding portion 11b.

[0035] A lateral hole 11f is provided at the bottom of the first housing 11d and the bottom of the second housing 11e, and the inside of the first housing 11d and the inside of the second housing 11e are in communication through the lateral hole 11f. In addition, the inside of the connecting part 11c is in communication with the inside of the second housing 11e. As mentioned above, the inside of the connecting part 11c is in communication with the pressure side chamber R2, so the inside of the first housing 11d is in communication with the pressure side chamber R2 via the lateral hole 11f, the inside of the second housing 11e and the connecting part 11c, and the inside of the second housing 11e is in communication with the pressure side chamber R2 via the lateral hole 11f. Therefore, the liquid chamber L is connected to the pressure chamber R2 via port 11b1, the first housing 11d, the lateral hole 11f, the second housing 11e, and the connecting part 11c, and is also connected to the pressure chamber R2 via port 11b2, the second housing 11e, and the connecting part 11c.

[0036] Furthermore, a bypass path PB is formed connecting the pressure chamber R2 and the tank 4 by port 11b1, the inside of the first housing 11d, the lateral hole 11f, the inside of the second housing 11e, and the inside of the connecting part 11c, and a first passage P1 and a suction passage P4 are formed connecting the pressure chamber R2 and the tank 4 by port 11b2, the inside of the second housing 11e, and the inside of the connecting part 11c. Note that the arrangement and installation direction of the first housing 11d and the second housing 11e relative to the cap portion 11a are not limited to the arrangement and installation direction described above and can be changed in design.

[0037] As shown in Figure 3, a threaded portion 11d1 is formed on the inner circumference of the open end of the first housing 11d, and the first valve unit V1 housed in the first housing 11d is screwed into the threaded portion 11d1. The first valve unit V1 includes a passage Pv1 that connects the lateral hole 11f and the port 11b1, and a check valve 6 and a needle valve 7 provided in series with the passage Pv1. The check valve 6 allows only the flow of hydraulic fluid from the pressure-side chamber R2, which is connected to the lateral hole 11f, through the passage Pv1 towards the tank 4, which is connected to the port 11b1, thus setting the passage Pv1, which forms part of the bypass passage PB, as a one-way passage. The needle valve 7 is a valve that changes the flow area by driving a linear actuator 100 attached to the open end of the first housing 11d, and by changing the flow area, it changes the resistance to the flow of hydraulic fluid passing through it. Therefore, the check valve 6 sets the bypass path PB as a one-way passage from the pressure chamber R2 to the tank 4, and the needle valve 7 provides resistance to the flow of hydraulic fluid passing through the bypass path PB from the pressure chamber R2 to the tank 4.

[0038] As shown in Figure 1, a threaded portion 11e1 is formed on the inner circumference of the open end of the second housing 11e, and the second valve unit V2, which is housed in the second housing 11e, is screwed into the threaded portion 11e1.

[0039] As shown in Figure 1, the second valve unit V2 includes passages Pv2 and Pv3 that connect the inside of the connection part 11c and the port 11b2 in parallel, a compression damping valve 5 provided in passage Pv2, and an extension check valve 10 provided in passage Pv3. The compression damping valve 5 allows only the flow of hydraulic fluid from the pressure chamber R2, which is connected to the inside of the connection part 11c, through passage Pv2 toward the tank 4, which is connected to the port 11b2, thereby providing resistance to the flow of hydraulic fluid passing through and setting passage Pv2 as a one-way passage. Passage Pv2 connects the inside of the connection part 11c and the port 11b2 and forms part of the first passage P1, and the compression damping valve 5 provides resistance to the flow of hydraulic fluid passing from the pressure chamber R2 toward the tank 4. The extension check valve 10 allows only the flow of hydraulic fluid from the tank 4, which is connected to the port 11b2, towards the pressure chamber R2, which is connected to the connection part 11c via passage Pv3, thus setting passage Pv3 as a one-way passage. Passage Pv3 connects the inside of the connection part 11c and the port 11b2, forming part of the suction passage P4.

[0040] The shock absorber D, configured in this way, operates as follows: During the extension stroke of the shock absorber D, in which the piston 2 moves downward relative to the cylinder 1 in Figure 1, hydraulic fluid moves from the extension chamber R1, which is compressed by the piston 2, to the compression chamber R2 via the second passage P2. During this extension stroke, the shock absorber D generates an extension damping force that hinders extension by applying resistance to the flow of hydraulic fluid through the second passage P2 with the extension damping valve 8.

[0041] Furthermore, during the extension stroke of the shock absorber D, the piston rod 3 retracts from the cylinder 1, resulting in a shortage of hydraulic fluid in the pressure chamber R2 by the volume of the piston rod 3 that retracts from the cylinder 1. This shortage of hydraulic fluid is supplied from the liquid chamber L of the tank 4 by the free piston 12 moving within the tank 4, which expands the air chamber G, causing the extension check valve 10 to open and supplying the hydraulic fluid to the pressure chamber R2 via the suction passage P4. During the extension stroke of the shock absorber D, the compression damping valve 5, acting as a damping valve, closes to block the first passage P1, and the check valve 6 also closes to block the bypass passage PB. Therefore, the damping force characteristics during the extension stroke of the shock absorber D are determined by the extension damping valve 8, and the needle valve 7 does not affect the damping force during the extension stroke.

[0042] On the other hand, during the contraction stroke of the buffer D, in which the piston 2 moves upward in Figure 1 relative to the cylinder 1, the hydraulic fluid in the compression chamber R2, which is compressed by the piston 2, moves to the extension chamber R1 via the third passage P3 by opening the compression check valve 9. Also, during the contraction stroke of the buffer D, the piston rod 3 enters the cylinder 1, so there is an excess of hydraulic fluid in the cylinder 1 equal to the volume of the piston rod 3 that enters the cylinder 1. If the contraction speed of the buffer D is low and the pressure in the compression chamber R2 does not reach the opening pressure of the compression damping valve 5, this excess hydraulic fluid is discharged to the liquid chamber L in the tank 4 via the bypass passage PB by opening only the check valve 6. If the contraction speed of the buffer D is high and the pressure in the compression chamber R2 reaches the opening pressure of the compression damping valve 5, not only the check valve 6 but also the compression damping valve 5 is opened, and the excess hydraulic fluid is discharged to the liquid chamber L in the tank 4 via the first passage P1 and the bypass passage PB. Furthermore, within the tank 4 from which the hydraulic fluid is discharged, the free piston 12 moves within the tank 4, reducing the size of the air chamber G.

[0043] Thus, during the contraction stroke of the buffer D, depending on the contraction speed of the buffer D, the hydraulic fluid moves from the pressure chamber R2 to the tank 4, passing through only the needle valve 7 or through the pressure damping valve 5 and the needle valve 7. In summary, during the contraction stroke of the buffer D, when the contraction speed of the buffer D is low, the bypass passage PB is opened, creating communication between the extension chamber R1 and the pressure chamber R2 in the cylinder 1, and the needle valve 7 provides resistance to the flow of hydraulic fluid from the pressure chamber R2 to the tank 4. When the contraction speed of the buffer D is high, the first passage P1 and the bypass passage PB are opened, creating communication between the extension chamber R1 and the pressure chamber R2 in the cylinder 1, and the pressure damping valve 5 and the needle valve 7 provide resistance to the flow of hydraulic fluid from the pressure chamber R2 to the tank 4.

[0044] During the contraction stroke of the shock absorber D, the extension chamber R1 and the compression chamber R2 are connected through the third passage P3, so the pressure in both the extension chamber R1 and the compression chamber R2 rises to approximately the same level. In the shock absorber D of this embodiment, the area of ​​the piston 2 facing the extension chamber R1 is smaller than the area of ​​the piston 2 facing the compression chamber R2 by the area of ​​the piston rod 3. Therefore, the contracting shock absorber D exerts a damping force in the direction that opposes the contraction, with a value equal to the pressure in the cylinder 1 multiplied by the area of ​​the piston rod 3. In other words, in the case of a shock absorber D set as a single-rod type with a piston rod 3 present on only one side of the piston 2, a damping force proportional to the cross-sectional area of ​​the piston rod 3 is generated during the contraction stroke.

[0045] Furthermore, the shock absorber D is equipped with a needle valve 7, and by adjusting the flow area of ​​the needle valve 7, the resistance that the needle valve 7 exerts on the flow of the hydraulic fluid can be changed, so the shock absorber D can adjust the damping force on the compression side.

[0046] As mentioned above, the needle valve 7, by blocking the bypass path PB with the check valve 6 during the extension stroke of the buffer D, allows for adjustment of the damping force during the contraction stroke of the buffer D without affecting the damping force during the extension stroke. Therefore, even if the flow path area of ​​the needle valve 7 is changed to adjust the damping force during the contraction stroke of the buffer D, the damping force during the extension stroke of the buffer D does not change, and changing the flow path area of ​​the needle valve 7 does not cause any change in the damping force during both the extension and contraction strokes of the buffer D.

[0047] The above explains the principle behind the compression damping valve 5, check valve 6, and needle valve 7 as damping valves. Below, we will explain the specific configurations of the compression damping valve 5, check valve 6, and needle valve 7. Due to the component configuration, the configuration of the needle valve 7 will be explained first, followed by the configuration of the check valve 6.

[0048] As shown in Figure 5, the needle valve 7 comprises a cylindrical needle case 71, a needle 72 inserted into the needle case 71 so as to be movable in the axial direction, and a linear actuator 100 for driving the needle 72, and is housed in the first housing 11d.

[0049] The needle case 71 is cylindrical and includes an enlarged diameter portion 71a at one end, which is the lower end in Figure 5, and whose outer diameter is larger than that of the other end; an annular recess 71b on the inner circumference of the enlarged diameter portion 71a and whose inner diameter is larger than that of the other end; a socket portion 71c protruding downward from the outer circumference of the end of the enlarged diameter portion 71a; an annular groove 71d on the outer circumference and provided at the other end; a hole 71e that penetrates the wall thickness between the enlarged diameter portion 71a and the annular groove 71d in the radial direction; and an annular valve seat 71f on the inner circumference and provided between the annular recess 71b and the hole 71e in the axial direction, on which the needle 72 sits and moves.

[0050] The inner diameter of the annular recess 71b is smaller than the inner diameter of the socket portion 71c provided at the end of the enlarged portion 71a, and larger than the inner diameter of the other end of the needle case 71. Therefore, the lower end in Figure 5, which is one end of the needle case 71, has a shape in which the inner diameter is enlarged in two stages.

[0051] Furthermore, when viewed from one end of the needle case 71, the axial end face on the inner circumference side of the annular recess 71b is shallower than the axial end face on the outer circumference side, and an annular projection 71b1 is formed on the inner circumference side of the annular recess 71b.

[0052] The annular groove 71d is provided along the circumferential direction on the outer circumference of the portion of the needle case 71 at the other end where the outer diameter is smaller. An O-ring 77 is housed within the annular groove 71d.

[0053] The hole 71e extends radially through the space between the enlarged diameter portion 71a and the annular groove 71d, that is, the portion on the other end of the needle case 71 where the outer diameter is smaller, thus connecting the inside and outside of the needle case 71. Therefore, the inside of the needle case 71 is always in communication with the inside of the tank 4 via the hole 71e and the port 11b1.

[0054] The annular valve seat 71f is annular and is located on the inner circumference of the needle case 71, between the annular recess 71b and the hole 71e. The inner diameter of the annular valve seat 71f is smaller than the inner diameter of the other end of the needle case 71, and gradually widens from the middle of the axial direction toward the other end of the needle case 71. Therefore, since the inner circumference of the annular valve seat 71f is widened as described above, the annular valve seat 71f has a tapered surface 71f1 on its inner circumference.

[0055] The needle 72 is axial in shape and comprises a conical valve head 72a at its lower end in Figure 5 that can penetrate the inner circumference of the annular valve seat 71f, a flange-shaped seating portion 72b connected to the rear end of the valve head 72a (which is the upper end in Figure 5) that can seat on and off the inner circumference of the upper end of the annular valve seat 71f, a guide portion 72c located in the center with a larger outer diameter than the other parts that slides against the inner circumference of the needle case 71 on the other end side of the hole 71e, and a guide shaft 72d with a smaller diameter than the other parts that protrudes axially from the rear end of the guide portion 72c. The needle 72 is inserted into the needle case 71 so as to be movable in the axial direction, and by sliding the guide portion 72c against the inner circumference of the needle case 71, it can move axially without radial deviation relative to the needle case 71. The guide shaft 72d protrudes outward from the opening on the other end side of the needle case 71.

[0056] When the needle 72 seats its seating portion 72b on the other end surface of the annular valve seat 71f in the axial direction, it closes the needle valve 7. When the seating portion 72b is moved away from the other end surface of the annular valve seat 71f, a gap is created between the valve head 72a and the tapered surface 71f1, opening the needle valve 7. When the needle valve 7 is open, the gap between the valve head 72a and the tapered surface 71f1 limits the flow area of ​​the bypass passage PB, providing resistance to the flow of hydraulic fluid passing through the needle valve 7. Furthermore, when the needle valve 7 is open, changing the axial position of the needle 72 relative to the needle case 71 changes the size of the gap (flow area) between the valve head 72a and the tapered surface 71f1, and thus changes the resistance to the flow of hydraulic fluid passing through the needle valve 7. In this way, by adjusting the axial position of the needle 72 relative to the needle case 71, the flow area of ​​the needle valve 7 can be changed, thereby adjusting the resistance applied to the flow of hydraulic fluid passing through the needle valve 7.

[0057] Furthermore, a seal retaining member 73 with an L-shaped cross-section is laminated at the upper end of the needle case 71. This member is annular in shape, with the guide shaft 72d of the needle 72 inserted through its inner circumference and a flange 73a on its outer circumference. 、An annular sealing member 74 is laminated on the upper end of the sealing retaining member 73, and the sealing member 74 slides against the outer circumference of the guide shaft 72d of the needle 72, thereby sealing the outer circumference of the needle 72. The guide shaft 72d of the needle 72, which protrudes upward from the needle case 71, is inserted into the adapter 75, and the upper end of the guide shaft 72d always protrudes upward in Figure 5 of the adapter 75.

[0058] The needle case 71, which houses the needle 72, is fixed within the first housing 11d together with the seal retaining member 73 and the seal member 74 by a standard adapter 75 that is screwed onto a threaded portion 11d1 provided on the inner circumference of the first housing 11d. The adapter 75 is cylindrical and has an inner diameter that decreases in two stages on the upper end side in Figure 5, with a small diameter portion 75a and a large diameter portion 75b formed on the inner circumference, a threaded portion 75c provided on the outer circumference that screws onto the threaded portion 11d1 of the first housing 11d, and an annular groove 75d provided above the threaded portion 75c in Figure 5. A seal ring 76 is fitted inside the annular groove 75d of the adapter 75, which is in close contact with the inner circumference on the open end side of the threaded portion 11d1 of the first housing 11d, and seals between the adapter 75 and the first housing 11d. Furthermore, to facilitate screwing the adapter 75 into the first housing 11d, the upper end of the adapter 75 is provided with an operating portion 75e, which is a projection with a groove that allows insertion of a tool for rotating the adapter 75.

[0059] The seal member 74 is housed within the small-diameter portion 75a of the adapter 75, and the flange 73a of the seal retaining member 73 is housed within the large-diameter portion 75b of the adapter 75, along with the needle case 71. The flange 73a of the seal retaining member 73 is sandwiched between the needle case 71 and the small-diameter portion 75a and large-diameter portion 75b of the adapter 75, and the seal retaining member 73 is fixed immovably to the adapter 75 and the needle case 71. Furthermore, the portion of the seal retaining member 73 smaller in diameter than the flange 73a enters the small-diameter portion 75a of the adapter 75 and faces the seal member 74 in the axial direction, preventing the seal member 74 from falling out of the small-diameter portion 75a of the adapter 75.

[0060] The guide shaft 72d of the needle 72, which protrudes upward from the upper end of the adapter 75, slides against the inner surface of the upper end portion of the adapter 75, which has the smallest inner diameter, thereby suppressing radial axial runout of the guide shaft 72d. In this way, the needle 72 is supported at two points, with the guide shaft 72d sliding against the inner surface of the upper end of the adapter 75 and the guide portion 72c sliding against the inner surface of the needle case 71. This allows the needle 72 to seat and dissipate from the annular valve seat 71f without axial runout during axial movement, enabling stable changes in the flow path area.

[0061] The linear actuator 100 is fixed to the open end of the first housing 11d by bolts 110. Specifically, the linear actuator 100 includes a stepping motor 101 with a rotor (not shown) and a conversion unit 102 equipped with a feed screw mechanism that converts the rotational motion of the rotor into linear motion of a push rod 103 and outputs it. In the linear actuator 100, the push rod 103 abuts against the guide shaft 72d at the rear end of a needle 72 that is axially movable inside a needle case 71 fixed inside the first housing 11d. When the stepping motor 101 is driven to displace the push rod 103 in the axial direction, the needle 72 moves axially relative to the needle case 71. Therefore, by driving the linear actuator 100, the needle 72 can be moved closer to or further away from the annular valve seat 71f provided in the needle case 71 to adjust the flow area when the needle valve 7 is closed and open.

[0062] Note that the guide shaft 72d of the needle 72 and the push rod 103 are only in contact and not connected. When the needle 72 receives pressure from the hydraulic fluid attempting to pass through the inner circumference of the annular valve seat 71f of the needle case 71, it is pressed upward relative to the needle case 71 in Figure 5 and comes into contact with the push rod 103. Therefore, when the push rod 103 is displaced upward, the needle 72 is pressed by the hydraulic fluid and follows the displacement of the push rod 103, moving upward in a direction away from the annular valve seat 71f, thereby increasing the flow area of ​​the needle valve 7. On the other hand, when the push rod 103 is displaced downward in Figure 5, the needle 72 is pushed by the push rod 103 and moves downward relative to the needle case 71, towards the annular valve seat 71f, thereby decreasing the flow area of ​​the needle valve 7. Therefore, the guide shaft 72d of the needle 72 and the push rod 103 do not need to be connected and only need to be in contact with each other, although they may be connected.

[0063] Furthermore, in the shock absorber D of this embodiment, the first housing 11d is provided on the cylinder 1 and upper cap 11 along the vertical direction, and its open end faces upward, so that the linear actuator 100 is mounted on the upper side of the shock absorber D. In the shock absorber D of this embodiment, the upper cap 11 is connected to the vehicle body F of the saddle-type vehicle M, and the linear actuator 100 is positioned on the vehicle body F side, so the wiring length for supplying power to the linear actuator 100 can be shortened, and the linear actuator 100 can be protected by keeping it away from the ground.

[0064] Next, the check valve 6 comprises a disc-shaped valve seat member 61 fitted to the lower end of the needle case 71 in Figure 5, an annular valve body 62 housed in an annular recess 71b of the needle case 71 and movable axially relative to the valve seat member 61, and an annular biasing member 63 housed on the inner circumference of the needle case 71 and biasing the annular valve body 62 toward the valve seat member 61, with the needle case 71 being used as a case to house the annular valve body 62 and the biasing member 63.

[0065] The valve seat member 61 is disc-shaped and includes a cylindrical protrusion 61a that projects axially from the end on the needle valve side, and a plurality of holes 61b arranged on the circumference of a circle with a smaller diameter than the protrusion 61a, which penetrate the thickness of the protrusion 61a in the axial direction. The holes 61b in the valve seat member 61 communicate the inside of the needle case 71 with the lateral holes 11f in the upper cap 11.

[0066] The valve seat member 61 is fitted to the end of the needle case 71 by inserting its protrusion 61a into the annular recess 71b of the needle case 71 and inserting its outer circumference into the socket portion 71c. Therefore, the axial end face of the outer circumference portion of the valve seat member 61 that is further out than the protrusion 61a abuts against the axial end face of the enlarged diameter portion 71a. In this way, the valve seat member 61 of the check valve 6 is fitted to the inner circumference of one end of the needle case 71 and is fixed inside the first housing 11d by being sandwiched between the adapter 75, which is screwed into the first housing 11d together with the needle case 71, and the bottom of the first housing 11d, receiving axial force. In detail, the seal retaining member 73, the needle case 71, and the outer circumference of the valve seat member 61 are sandwiched between the adapter 75 and the bottom of the first housing 11d, and receive axial force from the adapter 75 and the bottom of the first housing 11d. Therefore, the outer circumference of the valve seat member 61 on the needle case side and the axial end of the enlarged diameter portion 71a of the needle case 71 are in close contact due to the axial force, so it is possible to prevent hydraulic fluid from passing between the valve seat member 61 and the needle case 71 without providing a seal. Also, the outer circumference of the valve seat member 61 on the side opposite the needle case and the bottom of the first housing 11d are in close contact due to the axial force, so it is possible to prevent hydraulic fluid from passing between the valve seat member 61 and the first housing 11d without providing a seal.

[0067] The annular valve body 62 is annular in shape and is superimposed on the valve seat member 61 so as to be axially movable as a whole, and is housed in the annular recess 71b of the needle case 71. The outer diameter of the annular valve body 62 is slightly smaller than the outer diameter of the convex portion 61a and the outer diameter of the annular recess 71b, and the inner diameter of the annular valve body 62 is set to a diameter that allows it to close each hole 61b when it comes into contact with the valve seat member 61.

[0068] The biasing member 63 is an elastic bendable washer housed in the annular recess 71b of the needle case 71 and is interposed between the annular valve body 62 and the protrusion 71b1 of the needle case 71 in a compressed state in the axial direction, constantly biasing the annular valve body 62 toward the valve seat member 61. Therefore, when the upward pressing force on the annular valve body 62 due to the pressure of the pressure chamber R2 acting through the hole 61b exceeds the biasing force of the biasing member 63, the biasing member 63 is compressed in the axial direction, causing the entire assembly to retract axially from the valve seat member 61 and open the hole 61b. When the annular valve body 62 separates from the valve seat member 61, the hole 61b opens, allowing the hydraulic fluid to move from the pressure chamber R2 through the inner circumference of the annular valve body 62 and the biasing member 63, and through the inside of the needle case 71 to the tank 4. On the other hand, the annular valve body 62 contacts the valve seat member 61 and closes the hole 61b until the pressure in the pressure chamber R2 exceeds the pressure from the tank 4 received from the rear side and the differential pressure between the two reaches the opening pressure of the check valve 6. The annular valve body 62 and the biasing member 63 are positioned radially by the side wall surface that forms the annular recess 71b of the needle case 71, and do not wobble radially even when moved toward or away from the valve seat member 61, so that the operation is stable and the hole 61b can be stably closed when seated on the valve seat member 61.

[0069] Furthermore, the biasing member 63 only needs to be able to bias the annular valve body 62 and not obstruct the passage of hydraulic fluid through the needle case 71 when the annular valve body 62 opens the hole 61b of the valve seat member 61. Therefore, in addition to a bent washer, a wave washer, an annular disc spring, or an elastic body may also be used.

[0070] The check valve 6 and needle valve 7 are configured as described above and constitute a first valve unit V1 housed in the first housing 11d with components other than the linear actuator 100. Furthermore, a passage Pv1 is formed by the hole 61b in the valve seat member 61, the inside of the needle case 71 and the hole 71e, which connects the lateral hole 11f communicating with the pressure side chamber R2 and the port 11b1 communicating with the tank 4, and also forms part of the bypass passage PB. aisleA check valve 6 and a needle valve 7 are provided in series on Pv1. When the needle case 71 is fitted into the adapter 75, the O-ring 77 housed in the annular groove 71d of the needle case 71 is compressed, applying a tightening force to the inner circumferential surface of the large diameter portion 75b of the adapter 75 and making tight contact, thereby temporarily fixing the needle case 71 to the adapter 75. Therefore, by providing an O-ring 77 on the outer circumference of the needle case 71 that makes tight contact with the adapter 75, the needle case 71 holding the check valve 6, the needle 72, the seal retaining member 73, and the seal member 74 can be held assembled inside the adapter 75 by the O-ring 77, making it easier to screw the first valve unit V1 into the first housing 11d.

[0071] When the needle valve 7 is open, as the buffer D contracts, the pressure in the pressure chamber R2 acting through the hole 61b causes the annular valve body 62 to separate from the valve seat member 61, opening the check valve 6 and opening the bypass passage PB. Therefore, during the contraction stroke of the buffer D, the check valve 6 opens and the bypass passage PB is opened, and the hydraulic fluid moves from the pressure chamber R2 to the tank 4 by passing through the check valve 6 and needle valve 7 located in the bypass passage PB. The needle valve 7 imparts resistance to the flow of the hydraulic fluid in proportion to the flow path area.

[0072] On the other hand, when the seating portion 72b is seated on the annular valve seat 71f and the needle valve 7 is closed, even if the buffer D contracts, the hydraulic fluid cannot pass through the bypass passage PB, thus preventing the movement of hydraulic fluid from the pressure chamber R2 to the tank 4 through the bypass passage PB.

[0073] Furthermore, regardless of whether the needle valve 7 is open or closed, if the buffer D extends, the check valve 6 remains closed, blocking the bypass passage PB, so the hydraulic fluid does not pass through the bypass passage PB.

[0074] Furthermore, since the valve seat member 61, the needle case 71, and the bottom of the first housing 11d are in close contact under the action of axial force, a short circuit between the pressure chamber R2 and the tank 4 is prevented via the valve seat member 61 and the needle case 71 without passing through the check valve 6, and a short circuit between the pressure chamber R2 and the tank 4 is prevented via the valve seat member 61 and the first housing 11d without passing through the check valve 6 and the needle valve 7. Therefore, even without providing seals between the valve seat member 61 and the needle case 71 and between the valve seat member 61 and the bottom of the first housing 11d, it is possible to prevent the hydraulic fluid from passing through the bypass path PB during the extension stroke of the buffer D, and to prevent the hydraulic fluid from moving from the pressure chamber R2 to the tank 4 without passing through the check valve 6 and the needle valve 7 during the contraction stroke of the buffer D.

[0075] Next, the specific compression damping valve 5 and extension check valve 10 that constitute the second valve unit V2 housed in the second housing 11e will be described. The second valve unit V2 is inserted into the second housing 11e in the upper cap 11, as shown in Figure 6. ruba The valve retaining shaft 21, the disc 22 mounted on the outer circumference of the valve retaining shaft 21, the annular leaf valve 23 superimposed on the left end of the disc 22 in Figure 6 and with its inner circumference fixed to the outer circumference of the valve retaining shaft 21, the annular valve retaining member 24 positioned on the side of the leaf valve 23 opposite the disc, the annular spring receiver 25 attached to the left end of the valve retaining shaft 21 in Figure 6, the spring 26 interposed between the valve retaining member 24 and the spring receiver 25 and biasing the leaf valve 23 toward the disc 22 via the valve retaining member 24, and the inner circumference of the right end of the disc 22 in Figure 6 Overlapping A cylindrical collar 27 that fits onto the outer circumference of the valve retaining shaft 21, an annular check valve body 28 that is axially movable on the right end of the disc 22 in Figure 6 and positioned on the outer circumference of the collar 27, a nut 29 screwed onto the right end of the valve retaining shaft 21 in Figure 6, and a spring 19 interposed between the check valve body 28 and the collar 27 to bias the check valve body 28 toward the disc 22. , theThe device is configured to include a cap 18 that is screwed onto the threaded portion 11e1 of the housing 11e, and a cylindrical spacer 17 that is interposed between the outer circumference of the disk 22 and the cap 18.

[0076] As shown in Figure 6, the valve retaining shaft 21 is cylindrical and has a small-diameter portion 21a formed with a smaller outer diameter from the middle to the tip (right end in Figure 6) which is inserted into the inner circumference of the disk 22, and a threaded portion 21b provided on the outer circumference of the tip of the small-diameter portion 21a. An annular spring receiver 25 is attached to the outer circumference of the base end in Figure 6.

[0077] The disk 22 is annular in shape and has a port 22a that penetrates its thickness axially and a port 22b that penetrates its thickness axially. Port 22a functions as a passage Pv2 that connects the inside of the connection part 11c that communicates with the pressure side chamber R2 and the port 11b2 that communicates with the tank 4, and also forms part of the first passage P1. Port 22b functions as a passage Pv3 that connects the inside of the connection part 11c that communicates with the pressure side chamber R2 and the port 11b2 that communicates with the tank 4, and also forms part of the suction passage P4.

[0078] The leaf valve 23 has its inner circumference fixed to the outer circumference of the small-diameter portion 21a of the valve holding shaft 21, allowing for deflection on the outer circumference. It is also superimposed on the left end of the disk 22 in Figure 6. When it contacts the disk 22, it blocks the port 22a, and when its outer circumference is deflected, it opens the port 22a.

[0079] The valve retaining member 24 is a cylinder with a flange on its outer circumference, which is superimposed on the leaf valve 23 on the side opposite the disc and fitted to the outer circumference of the valve holding shaft 21 on the base end side of the small diameter portion 21a so as to be axially movable, and can move axially closer to or further away from the disc 22.

[0080] A spring 26, made of a coil spring, is interposed in a compressed state between the valve retaining member 24 and the spring receiver 25. The spring 26 constantly biases the leaf valve 23 toward the disc 22 via the valve retaining member 24, causing it to seat on the disc 22.

[0081] The cylindrical collar 27 is superimposed on the inner circumference of the right end of the disc 22 in Figure 6 and is fixedly mounted on the outer circumference of the small diameter portion 21a of the valve holding shaft 21. The collar 27 is equipped with a flange-shaped spring receiver 27a on the outer circumference of the right end in Figure 6. The check valve body 28 is annular in shape, with an inner diameter larger than the outer diameter of the collar 27, and is superimposed on the right end of the disc 22 in Figure 6 so as to be movable in the axial direction. When it contacts the disc 22, it closes the port 22b, and when it moves away from the disc 22, it opens the port 22b. The outer circumference of the check valve body 28 is guided by an annular guide (not shown) provided on the outer circumference of the disc 22, allowing it to move toward and away from the disc 22 without axial wobble.

[0082] The nut 29 is screwed onto the threaded portion 21b at the tip of the small-diameter portion 21a of the valve retaining shaft 21. When the nut 29 is screwed onto the valve retaining shaft 21, the disc 22, leaf valve 23, and collar 27 are held between the nut 29 and the stepped portion 21c formed by the small-diameter portion 21a of the valve retaining shaft 21, and are fixed immovably to the valve retaining shaft 21.

[0083] A conical coil spring 19 is interposed in a compressed state between the check valve body 28 and the spring receiver 27a in the collar 27, and the spring 19 constantly biases the check valve body 28 toward the disk 22 so that it seats on the disk 22.

[0084] The disc 22, leaf valve 23, valve retaining member 24, spring receiver 25, spring 26, collar 27, check valve body 28, nut 29, and spring 19, configured in this way, are assembled and integrated onto the valve holding shaft 21 to form a valve assembly.

[0085] The valve assembly is fully housed within the second housing 11e when it is inserted into the second housing 11e until the outer circumference of the right end of the disc 22 in Figure 6 abuts against the stepped portion 11e2 formed within the second housing 11e. After a cylindrical spacer 17 is placed on the outer circumference of the left end of the disc 22 in Figure 6 of the valve assembly housed within the second housing 11e, a cap 18 that seals the second housing 11e is screwed onto the threaded portion 11e1 of the second housing 11e. The disc 22 and spacer 17 are then sandwiched between the cap 18 and the stepped portion 11e2, fixing the valve assembly within the second housing 11e.

[0086] Furthermore, the spacer 17 is provided with a through hole 17a, ensuring communication between the tank 4 and the inside of the second housing 11e via the port 11b2 and the through hole 17a. During the contraction stroke of the buffer D, the pressure in the pressure chamber R2 acts on the leaf valve 23 through the connection part 11c and port 22a. When the force that attempts to bend the outer circumference of the leaf valve 23 due to this pressure overcomes the elastic force of the leaf valve 23 and the biasing force of the spring 26, the outer circumference of the leaf valve 23 bends, separating from the disc 22 and opening port 22a, thus communicating the pressure chamber R2 with the tank 4 and allowing the hydraulic fluid to pass from the pressure chamber R2 to the tank 4, while also providing resistance to the flow of the hydraulic fluid.

[0087] Thus, port 22a, together with port 11b2, the inside of the second housing 11e, and the inside of the connecting portion 11c, forms a first passage P1 that connects the compression chamber R2 and the tank 4. The disc 22, leaf valve 23, valve retaining member 24, spring receiver 25, and spring 26 form a compression damping valve 5 that generates damping force during the contraction stroke of the shock absorber D. Note that the configuration of the compression damping valve 5 and the extension check valve 10 is just one example, and other configurations are possible, and the design can be modified.

[0088] On the other hand, during the extension stroke of the buffer D, the pressure in the tank 4 acts on the check valve body 28 through ports 11b2 and 22b. When the force exerted by this pressure to separate the check valve body 28 from the disc 22 overcomes the biasing force of the spring 19, the check valve body 28 separates from the disc 22, opening port 22b and connecting the tank 4 to the pressure chamber R2, allowing the hydraulic fluid to pass from the tank 4 to the pressure chamber R2.

[0089] Thus, port 22b, together with port 11b2, the inside of the second housing 11e, and the inside of the connecting part 11c, forms a suction passage P4 that connects the pressure side chamber R2 and the tank 4. The disc 22, check valve body 28, collar 27, and spring 19 form an extension side check valve 10 that opens the suction passage P4 during the extension stroke of the buffer D.

[0090] As described above, the shock absorber D, which includes a compression damping valve 5, a check valve 6, a needle valve 7, an extension check valve 10, a first passage P1, a bypass passage PB, and a suction passage P4, generates an extension damping force that hinders extension by applying resistance to the flow of hydraulic fluid through the second passage P2 via the extension damping valve 8 when extending. During the extension stroke of the shock absorber D, the check valve body 28 separates from the disc 22 and opens the port 22b, so the extension check valve 10 opens, and hydraulic fluid equivalent to the volume of the piston rod 3 exiting the cylinder 1 is supplied from the tank 4 to the compression chamber R2 via the suction passage P4.

[0091] Furthermore, during the extension stroke of the shock absorber D, the compression damping valve 5, acting as a damping valve, closes to block the first passage P1. Even if the needle 72 in the needle valve 7 separates from the annular valve seat 71f and opens the bypass passage PB, the annular valve body 62 contacts the valve seat member 61, closing the hole 61b and blocking the bypass passage PB. Therefore, the damping force characteristics during the extension stroke of the shock absorber D are determined solely by the extension damping valve 8, and the needle valve 7 does not affect the damping force during the extension stroke.

[0092] On the other hand, during the contraction stroke of the shock absorber D, the hydraulic fluid in the pressure chamber R2 opens the pressure check valve 9 and moves to the extension chamber R1 via the third passage P3, and the hydraulic fluid becomes excessive in the cylinder 1 due to the volume of the piston rod 3 entering the cylinder 1. When the needle 72 in the needle valve 7 separates from the annular valve seat 71f and opens the bypass passage PB, and the contraction speed of the shock absorber D is low and the pressure in the pressure chamber R2 does not reach the opening pressure of the pressure damping valve 5, the aforementioned excess hydraulic fluid pushes the annular valve body 62, separates from the annular valve body 62, passes through the hole 61b, and then moves from the pressure chamber R2 to the tank 4 through the gap between the needle 72 and the annular valve seat 71f. Therefore, in this case, the shock absorber D generates a damping force that hinders the contraction of the shock absorber body DB by the needle valve 7. Furthermore, the resistance that the flow path area in the needle valve 7 imposes on the flow of hydraulic fluid can be adjusted by the linear actuator 100, thereby adjusting the damping force during the contraction stroke of the shock absorber D.

[0093] In the case where the needle 72 in the needle valve 7 separates from the annular valve seat 71f and opens the bypass passage PB, and the shock absorber D contracts quickly and the pressure in the pressure chamber R2 reaches the opening pressure of the pressure damping valve 5, the aforementioned excess hydraulic fluid not only passes through the check valve 6 and needle valve 7 in the bypass passage PB, but also presses against the spring 26 and leaf valve 23, compressing the spring 26 and bending the outer circumference of the leaf valve 23, separating it from the disc 22, and moves from the pressure chamber R2 to the tank 4 through the port 22a. Therefore, in this case, the shock absorber D generates a damping force that hinders the contraction of the shock absorber body DB by the needle valve 7 and the pressure damping valve 5. In this case as well, the needle valve 7 contributes to the generation of the damping force, so the damping force during the contraction stroke of the shock absorber D can be adjusted by adjusting the flow area of ​​the needle valve 7 with the linear actuator 100. Furthermore, if the needle 72 in the needle valve 7 is seated on the annular valve seat 71f and the bypass passage PB is blocked, the hydraulic fluid cannot pass through the bypass passage PB and only passes through the compression damping valve 5. As a result, the shock absorber D generates a damping force that prevents the shock absorber body DB from contracting solely through the compression damping valve 5.

[0094] As mentioned above, the needle valve 7, by blocking the bypass path PB with the check valve 6 during the extension stroke of the buffer D, allows for adjustment of the damping force during the contraction stroke of the buffer D without affecting the damping force during the extension stroke. Therefore, even if the flow path area of ​​the needle valve 7 is changed to adjust the damping force during the contraction stroke of the buffer D, the damping force during the extension stroke of the buffer D does not change, and changing the flow path area of ​​the needle valve 7 does not cause any change in the damping force during both the extension and contraction strokes of the buffer D.

[0095] As described above, the buffer D of this embodiment comprises a cylinder 1, a piston 2 inserted into the cylinder 1 so as to be axially movable, a piston rod 3 inserted into the cylinder 1 and connected to the piston 2, a buffer body DB having a pressure side chamber R2 filled with hydraulic fluid (liquid) and a tank 4 (multiple working chambers), a first passage P1 and a bypass passage PB connecting the pressure side chamber R2 and the tank 4, a pressure side damping valve (damping valve) 5 provided in the first passage P1 to resist the flow of hydraulic fluid (liquid) from the pressure side chamber (one working chamber) R2 to the tank (the other working chamber) 4, a check valve 6 provided in the bypass passage PB to allow only the flow of hydraulic fluid (liquid) from the pressure side chamber (one working chamber) R2 to the tank (the other working chamber) 4, and a needle valve 7 provided in series with the check valve 6 in the bypass passage PB and capable of changing the flow area.

[0096] In the shock absorber D configured in this way, the check valve 6 blocks the bypass path PB during the extension stroke of the shock absorber D, so the needle valve 7 can adjust only the damping force during the contraction stroke of the shock absorber D without affecting the damping force during the extension stroke. Therefore, according to the shock absorber D of this embodiment, even if the flow path area of ​​the needle valve 7 is changed to adjust the damping force during the contraction stroke of the shock absorber D, the damping force during the extension stroke of the shock absorber D is not changed, so even if the needle valve 7 is provided, only the damping force during contraction can be changed.

[0097] Furthermore, the buffer D of this embodiment has a buffer body DB which comprises an extension chamber R1 and a compression chamber R2 partitioned by a piston 2 within the cylinder 1, and a tank 4 for storing hydraulic fluid (liquid), a second passage P2 and a third passage P3 which connect the extension chamber R1 and the compression chamber R2 in parallel, a suction passage P4 which connects the compression chamber R2 and the tank 4, an extension damping valve 8 provided in the second passage P2 which resists the flow of hydraulic fluid (liquid) from the extension chamber R1 to the compression chamber R2, and a valve provided in the third passage P3 which allows only the flow of hydraulic fluid (liquid) from the compression chamber R2 to the extension chamber R1. The shock absorber D is configured to include a pressure-side check valve 9 and an extension-side check valve 10 provided in the suction passage P4 that allows only the flow of hydraulic fluid (liquid) from the tank 4 to the pressure-side chamber R2. The first passage P1 and the bypass passage PB connect the pressure-side chamber R2 and the tank 4, with the working chamber being the pressure-side chamber R2 and the tank 4. The pressure-side damping valve (damping valve) 5 provides resistance to the flow of hydraulic fluid (liquid) while allowing only the flow of hydraulic fluid (liquid) from the pressure-side chamber R2 to the tank 4, and the check valve 6 is configured to allow only the flow of hydraulic fluid (liquid) from the pressure-side chamber R2 to the tank 4. In the shock absorber D configured in this way, the bypass passage PB is blocked by the check valve 6 during the extension stroke, so when the extension speed is extremely low, it is possible to prevent the hydraulic fluid from moving to the pressure-side chamber R2 through the bypass passage PB and quickly lower the pressure in the pressure-side chamber R2, thereby improving the responsiveness of damping force generation.

[0098] Furthermore, the buffer D of this embodiment includes a first housing (housing) 11d that houses a check valve 6 and a needle valve 7. The needle valve 7 includes a cylindrical needle case 71 inserted into the first housing (housing) 11d, and a needle 72 inserted into the needle case 71 so as to be movable in the axial direction. The needle case 71 has an annular recess 71b formed at one end by an enlarged inner diameter. The check valve 6 is connected to one end of the needle case 71 and the first housing (housing) 11d. The bypass passage PB comprises a disc-shaped valve seat member 61 that is sandwiched and faces the annular recess 71b, making close contact with the needle case 71 and the first housing (housing) 11d, and has a hole 61b that penetrates the thickness of the wall; an annular valve body 62 that is housed in the annular recess 71b so as to be movable in the axial direction and seats away from the valve seat member 61; and an annular biasing member 63 that is housed in the annular recess 71b and biases the annular valve body 62 toward the valve seat member 61. The bypass passage PB connects the pressure side chamber R2 and the tank 4 via the hole 61b and the inside of the needle case 71.

[0099] With the buffer D configured in this way, the valve seat member 61 is sandwiched between the needle case 71 and the first housing (housing) 11d, so that an axial force can be applied to the valve seat member 61, the needle case 71 and the first housing (housing) 11d to make them tightly sealed. Therefore, with the buffer D configured in this way, even without providing seals between the valve seat member 61 and the needle case 71 and between the valve seat member 61 and the bottom of the first housing (housing) 11d, it is possible to prevent the hydraulic fluid from passing through the bypass passage PB during the extension stroke of the buffer D, and to prevent the hydraulic fluid from moving from the pressure side chamber R2 to the tank 4 without passing through the check valve 6 and the needle valve 7 during the contraction stroke of the buffer D.

[0100] Furthermore, in the buffer D of this embodiment, the needle case 71 is equipped with an annular valve seat 71f on its inner circumference, on which the needle 72 sits and unseats. With the buffer D configured in this way, the needle case 71 not only functions as a case for the needle valve 7 that houses the needle 72 and is equipped with the annular valve seat 71f, but also functions as a case that houses the annular valve body 62 and the biasing member 63. As a result, the check valve 6 and the needle valve 7 can be arranged in series very close together, and the overall size of the check valve 6 and the needle valve 7 can be reduced. Therefore, with the buffer D configured in this way, even if a check valve 6 and a needle valve 7 are provided, an increase in size can be avoided.

[0101] Furthermore, in the buffer D of this embodiment, the annular valve body 62 and the biasing member 63 are radially positioned by the side wall surface of the annular recess 71b in the needle case 71. With the buffer D configured in this way, radial axial wobble of the annular valve body 62 and the biasing member 63 is suppressed when the entire annular valve body 62 separates from the valve seat member 61 and then re-seats, so that the operation of the annular valve body 62 is stable and the hole 61b can be stably closed when the annular valve body 62 sits on the valve seat member 61.

[0102] In this embodiment, the flow path area of ​​the needle valve 7 is adjusted by the linear actuator 100 in the buffer D. However, an adjuster capable of adjusting the axial position of the needle 72 relative to the needle case 71 may be provided at the open end of the first housing 11d, allowing the user of the buffer D to manually operate the adjuster to change the flow path area of ​​the needle valve 7.

[0103] Furthermore, in the shock absorber D of this embodiment, the check valve 6 and needle valve 7 are housed in the first housing 11d of the upper cap 11, and the compression damping valve 5 and extension check valve 10 are housed in the second housing 11e. However, the first housing 11d may be eliminated from the upper cap 11, and the second housing 11e may be used as the housing, with the check valve 6, needle valve 7, compression damping valve 5 and extension check valve 10 housed in the second housing 11e.

[0104] In this case, as shown in Figure 7, the device comprises an annular disc 30 with a port 30c, a cylindrical member 31 connected to the disc 30, a compression damping valve 5 for opening and closing the port 30c, an extension check valve 10 installed on the disc 30, a check valve 6 assembled to the disc 30, a cylindrical needle case 33 fitted to the outer circumference of the cylindrical member 31, a needle 34 housed in the needle case 33, a cylindrical adapter 35 on which the needle case 33 is screwed and which is screwed to a threaded portion 11e1 in the second housing 11e, and a cylindrical spacer 36 interposed between the adapter 35 and the outer circumference of the disc 30.

[0105] The disk 30 is comprised of an annular main body 30a that divides the second housing 11e into a space communicating with the connecting portion 11c and a space communicating with the port 11b2, an annular valve case 30b that protrudes to the right in Figure 7 from the main body 30a, and a port 30c that connects the spaces, formed by an annular groove that opens from the left end in Figure 7 of the main body 30a and a plurality of holes that open axially from the right end in Figure 7 of the main body 30a and lead to the annular groove.

[0106] The check valve 6 is housed within the valve case 30b. Specifically, it consists of a valve seat member 61 with a hole 61b fixed immovably to the valve case 30b, an annular valve body 62 housed within the valve case 30b and movable axially relative to the valve seat member 61, and a biasing member 63 interposed between the bottom of the valve case 30b and the annular valve body 62. The check valve 6, configured in this way, is housed within the valve case 30b and integrated with the disc 30. The check valve 6 is then pushed to the left by the pressure of the pressure chamber R2 acting within the connection portion 11c and through the hole 61b, causing the annular valve body 62 to separate from the valve seat member 61, thereby opening the hole 61b and opening the valve.

[0107] The cylindrical member 31 is screwed onto the inner circumference of the disk 30 and connected to the disk 30, with its inner circumference communicating with the inside of the valve case 30b. The outer diameter of the cylindrical member 31 becomes larger towards the left side in Figure 7, and a stepped portion 31a is formed on the outer circumference of the cylindrical member 31. A laminated leaf valve 32, which is made up of multiple annular leaf valves stacked on top of each other, is fitted onto the outer circumference of the cylindrical member 31. The inner circumference of the laminated leaf valve 32 is sandwiched between the stepped portion 31a of the cylindrical member 31 and the left end of the disk 30 in Figure 7. In this way, the inner circumference of the laminated leaf valve 32 is fixed immovably to the cylindrical member 31, and deflection of the outer circumference is permitted, partially covering the annular groove that forms the port 30c of the disk 30. Furthermore, a spring receiver 37 is mounted on the outer circumference to the left of the stepped portion 31a in Figure 7, on the side opposite the disk of the laminated leaf valve 32, so as to be movable in the axial direction.

[0108] Furthermore, an extension check valve 10 is housed within the annular groove of the disc 30. This check valve 10 consists of an annular check valve body 38, which has an inner diameter larger than the inner diameter of the annular groove and an outer diameter larger than the outer diameter of the laminated leaf valve 32, and a wave washer 39 that biases the check valve body 38 to contact the outer circumference of the laminated leaf valve 32. The check valve body 38 is supported at its outer circumference by an annular valve stopper 40 mounted on the outer circumference of the disc 30, preventing it from falling out of the annular groove of the disc 30.

[0109] The needle case 33 is cylindrical overall and includes a cylindrical housing portion 33a for housing the needle 34, a cylindrical fitting portion 33b that protrudes from the housing portion 33a toward the cylindrical member 31 and fits onto the outer circumference of the left end of the cylindrical member 31 in Figure 7, an annular valve seat 33c provided on the inner circumference between the housing portion 33a and the fitting portion 33b, and a hole 33d provided on the left end side of the annular valve seat 33c in Figure 7 and communicating the inside and outside of the housing portion 33a. Furthermore, the outer diameter of the housing portion 33a is larger than the outer diameter of the fitting portion 33b, and the needle case 33 has a stepped portion 33e on its outer circumference.

[0110] The needle 34 is housed within the needle case 33 and comprises a conical valve head 34a that can seat and detach from the annular valve seat 33c, a threaded portion 34b that is connected to the left end of the valve head 34a in Figure 7 and screwed onto the inner circumference of the needle case 33, and an operating portion 34c that is connected to the left end of the threaded portion 34b in Figure 7 and slides against the inner circumference of the needle case 33, and has a groove 34c1 at its rear end that allows a tool to be inserted.

[0111] The needle valve 7 is composed of a needle case 33 and a needle 34. Since the needle 34 is screwed into the needle case 33, rotating the operating part 34c moves the needle 34 axially closer to or further away from the annular valve seat 33c of the needle case 33, thereby changing the flow area in the needle valve 7. In addition, a detent N is provided between the needle case 33 and the needle 34, which functions as a circumferential positioning and anti-rotation mechanism for the needle 34 relative to the needle case 33 through the fitting of a sphere and a groove.

[0112] The needle case 33 is screwed onto the inner circumference of a cylindrical adapter 35, which is screwed onto a threaded portion 11e1 inside the second housing 11e, and is fixed inside the second housing 11e. A cylindrical spacer 36 with a through hole 36a is interposed between the adapter 35 and the outer circumference of the disc 30. When the adapter 35 is screwed into the second housing 11e, the spacer 36 and the disc 30 are sandwiched between the adapter 35 and a stepped portion 11e2 provided in the middle of the second housing 11e. In this way, the adapter 35 connects the needle case 33 to the second housing 11e and fixes the disc 30 to the second housing 11e.

[0113] Furthermore, a coil spring 41 is interposed in a compressed state between the stepped portion 33e on the outer circumference of the needle case 33, which is fixed inside the second housing 11e, and the spring retainer 37 mounted on the outer circumference of the cylindrical member 31 assembled to the disc 30. The coil spring 41 constantly biases the laminated leaf valve 32 toward the disc 30 side via the spring retainer 37.

[0114] When the outer circumference of the laminated leaf valve 32 contacts the disc 30, the laminated leaf valve 32 covers the inner circumference of the annular groove that forms the port 30c of the disc 30, the inner circumference of the check valve body 38 housed in the annular groove contacts the outer circumference of the laminated leaf valve 32 on the disc side, and the outer circumference of the check valve body 38 on the opposite side of the disc contacts the valve stopper 40, thereby closing the port 30c. On the other hand, when the outer circumference of the laminated leaf valve 32 flexes and separates from the disc 30, the laminated leaf valve 32 also separates from the check valve body 38 and opens the port 30c. In this way, the check valve body 38 also functions as a valve seat for the laminated leaf valve 32.

[0115] Port 30c is connected to the pressure chamber R2 via the connection part 11c and to the tank 4 via the through hole 36a and port 11b2 of the spacer 36. During the compression stroke of the shock absorber D, the outer circumference of the laminated leaf valve 32 is deflected by the pressure in the pressure chamber R2 acting through port 30c, causing the outer circumference of the laminated leaf valve 32 to separate from the check valve body 38 and the disc 30, opening port 30c and allowing hydraulic fluid to move from the pressure chamber R2 to the tank 4. The laminated leaf valve 32 also provides resistance to the flow of hydraulic fluid passing through port 30c. The amount of deflection of the laminated leaf valve 32 can be tuned by setting the deflection stiffness of the laminated leaf valve 32 and the spring constant of the coil spring 41. In this way, the compression damping valve 5 is formed by the disc 30, the laminated leaf valve 32, the check valve body 38, the spring receiver 37, and the coil spring 41. Note that the configuration of the compression damping valve 5 and the extension check valve 10 is just one example, and other configurations are possible, allowing for design modifications.

[0116] Furthermore, regarding the flow of hydraulic fluid from the pressure chamber R2 to the tank 4, the check valve body 38 is restricted by the valve stopper 40 and positioned at the opening of the annular groove, but since its inner diameter is larger than the inner diameter of the annular groove, it allows the flow of hydraulic fluid.

[0117] On the other hand, during the extension stroke of the buffer D, the outer circumference of the stacked leaf valve 32 comes into contact with the disc 30. However, the check valve body 38 receives pressure from the tank 4, compresses the wave washer 39, and moves towards the bottom within the annular groove, separating from the stacked leaf valve 32 and opening the port 30c. In this way, the pressure-side damping valve 5 provides resistance to the flow of hydraulic fluid from the pressure-side chamber R2 to the tank 4 through port 30c, while the extension-side check valve 10 allows the flow of hydraulic fluid from the tank 4 to the pressure-side chamber R2 through port 30c.

[0118] Furthermore, the pressure chamber R2 and the tank 4 are in communication through the connection part 11c, the hole 61b in the check valve 6, the disk 30, the cylindrical member 31, the needle case 33, the hole 33d, the through hole 36a in the spacer 36, and the port 11b2, and the bypass path PB is formed by the hole 61b in the check valve 6, the disk 30, the cylindrical member 31, the needle case 33, and the hole 33d.

[0119] During the contraction stroke of buffer D, when the needle valve 7 opens, the check valve 6 also opens, allowing the hydraulic fluid to move from the pressure chamber R2 to the tank 4 through the needle valve 7. On the other hand, during the extension stroke of buffer D, the check valve 6 closes, so the hydraulic fluid cannot pass through the bypass path PB and moves from the tank 4 to the pressure chamber R2 through the extension check valve 10.

[0120] In this way, the first housing 11d is eliminated from the upper cap 11, and the second housing 11e is used as the housing, allowing the check valve 6, needle valve 7, compression damping valve 5, and extension check valve 10 to be housed within the second housing 11e. abolition Alternatively, the first housing 11d may be used as a housing, and the check valve 6, needle valve 7, compression damping valve 5, and extension check valve 10 may be housed within the first housing 11d.

[0121] In the aforementioned buffer D, the working chamber consists of a compression chamber R2 and a tank 4, and the first passage P1 and bypass passage PB connect the compression chamber R2 and the tank 4. However, as shown in Figure 8, the working chamber may consist of an extension chamber R3 and a compression chamber R4, and the bypass passage PB connects the extension chamber R3 and the compression chamber R4 in the buffer body DB1. A damping valve may be provided in the first passage P1, and a check valve 6 and a needle valve 7 may be provided in series with the bypass passage PB. The shock absorber D1 shown in Figure 8 comprises a cylinder 50, a piston 51 inserted into the cylinder 50 so as to be movable in the axial direction, a piston rod 52 inserted into the cylinder 50 so as to be movable in the axial direction and connected to the piston 51, a shock absorber body DB1 having an extension chamber R3 and a compression chamber R4 partitioned by the piston 51 within the cylinder 50, a first passage P5 and a bypass passage PB1 connecting the extension chamber R3 and the compression chamber R4, a damping valve 53 provided in the first passage P5 that allows only the flow of hydraulic fluid from the extension chamber R3 to the compression chamber R4 and provides resistance to the flow of hydraulic fluid passing through it, a check valve 6 provided in the bypass passage PB1 that allows only the flow of hydraulic fluid from the extension chamber R3 to the compression chamber R4, and a needle valve 7 provided in series with the check valve 6 in the bypass passage PB1 and capable of changing the flow area. In this shock absorber D1, the extension chamber R3 and the compression chamber R4 become the working chambers.

[0122] Furthermore, a free piston 54 is inserted axially movably into the cylinder 50 of the shock absorber body DB, and the free piston 54 divides the gas chamber G1, which is filled with gas on the opposite side of the compression chamber R4 to the extension chamber within the cylinder 50. The piston 51 is provided with a compression passage P6 that connects the extension chamber R3 and the compression chamber R4 in parallel with the first passage P5, and a compression valve 55 that provides resistance to the flow of hydraulic fluid from the compression chamber R4 to the extension chamber R3 in the compression passage P6.

[0123] The buffer D1 configured in this way is a single-tube type buffer. When the extension chamber R3 and the compression chamber R4 of the buffer D1 are used as working chambers and the extension chamber R3 and the compression chamber R4 are connected by a bypass passage PB1, as shown in the figure, if the bypass passage PB1, check valve 6 and needle valve 7 are installed inside the piston rod 52, it is possible to install the bypass passage PB1, check valve 6 and needle valve 7 while avoiding an increase in the outer diameter of the buffer D1. When the needle valve 7 is installed inside the piston rod 52 in this way, it is preferable to form the piston rod 52 in a cylindrical shape and use a control rod inserted inside the piston rod 52 to provide power to the needle valve 7 to change the flow area.

[0124] When the shock absorber D1 extends, the hydraulic fluid moves from the extension chamber R3 to the compression chamber R4 through the damping valve 53, and at the same time, the check valve 6 opens, causing the hydraulic fluid to move from the extension chamber R3 to the compression chamber R4 through the check valve 6 and the needle valve 7. Therefore, in the shock absorber D1 configured in this way, the damping valve 53 and the needle valve 7 provide resistance to the flow of hydraulic fluid, generating a damping force that hinders the extension of the shock absorber body DB1. Furthermore, by changing the flow path area of ​​the needle valve 7, the resistance that the needle valve 7 provides to the flow of hydraulic fluid can be changed, making it possible to adjust the damping force during the extension stroke of the shock absorber D. Note that the change in volume inside the cylinder 50 due to the piston rod 52 retracting from the cylinder 50 during the extension stroke of the shock absorber D1 is compensated by the free piston 54 moving inside the cylinder 50 and expanding the air chamber G1.

[0125] On the other hand, when the shock absorber D1 contracts, the hydraulic fluid moves from the compression chamber R4 to the extension chamber R3 by passing through the compression valve 55. During the contraction stroke of the shock absorber D1, the check valve 6 does not open, so the hydraulic fluid cannot pass through the bypass path PB1 where the needle valve 7 is installed, and moves only through the compression valve 55. Therefore, in the shock absorber D1 configured in this way, the compression valve 55 alone provides resistance to the flow of the hydraulic fluid and generates a damping force that prevents the contraction of the shock absorber body DB1, so the needle valve 7 does not affect the damping force during the contraction stroke. Furthermore, the change in volume inside the cylinder 50 due to the piston rod 52 entering the cylinder 50 during the contraction stroke of the shock absorber D1 is compensated by the free piston 54 moving inside the cylinder 50 and reducing the size of the air chamber G1.

[0126] With the shock absorber D1 configured as described above, even if the damping force during the extension stroke of the shock absorber D1 is adjusted by changing the flow area of ​​the needle valve 7, the damping force during the contraction stroke of the shock absorber D is not changed. Therefore, even with the needle valve 7, it is possible to change only the damping force during extension.

[0127] Furthermore, if the direction of hydraulic fluid flow permitted by the check valve 6 in the buffer D1 is reversed, that is, if the check valve 6 is set to only allow the flow of hydraulic fluid from the compression chamber R4 to the extension chamber R3, then when the buffer D1 contracts, the hydraulic fluid will pass through not only the compression valve 55 but also the needle valve 7, and when the buffer D1 extends, the hydraulic fluid will pass only through the damping valve 53. With this setting, it becomes possible to adjust the damping force during the contraction stroke of the buffer D1 by changing the flow area of ​​the needle valve 7, while preventing any change in the damping force during the extension stroke of the buffer D. In this case, the compression valve 55 functions as a damping valve, and the compression passage P6 in which the compression valve 55 is provided functions as the first passage. With the buffer D1 configured in this way, even if the damping force during the contraction stroke of the buffer D1 is adjusted by changing the flow area of ​​the needle valve 7, the damping force during the extension stroke of the buffer D is not changed, so even if the needle valve 7 is provided, only the damping force during contraction can be changed.

[0128] Although preferred embodiments of the present invention have been described in detail above, modifications, alterations, and changes are permitted as long as they do not deviate from the scope of the claims. [Explanation of symbols]

[0129] 1.50...Cylinder, 2.51...Piston, 3.52...Piston rod, 4...Tank (operating chamber), 5...Compression damping valve (damping valve), 6...Check valve, 7...Needle valve, 8...Rebound damping valve, 9...Compression check valve, 10...Rebound check valve, 11d...First housing (housing), 11e...Second housing (housing), 33, 71... Needle case, 34, 72... Needle, 53... Damping valve, 61... Valve seat member, 61b... Hole, 62... Annular valve body, 63... Biasing member, 71b... Annular recess, 71f... Annular valve seat, D, D1... Buffer, DB, DB1... Buffer body, P1, P5... First passage, P2... Second passage, P3... Third passage, P4... Suction passage, PB, PB1... Bypass passage, R1... Expansion chamber, R2... Compression chamber (working chamber), R3... Expansion chamber (working chamber), R4... Compression chamber (working chamber)

Claims

1. A buffer body having a cylinder, a piston inserted into the cylinder so as to be axially movable, a piston rod inserted into the cylinder and connected to the piston, and a plurality of working chambers filled with liquid, A first passage and a bypass passage that connect the aforementioned operating chambers, A damping valve provided in the first passage that provides resistance to the flow of liquid from one working chamber to the other working chamber, A check valve provided in the bypass path that allows only the flow of liquid from one working chamber to the other working chamber, The bypass path is provided with a needle valve installed in series with the check valve, which can change the flow path area. The aforementioned shock absorber body is, The cylinder contains an extension chamber and a compression chamber, which are partitioned by the piston, It has a tank for storing liquid, A second passage and a third passage that connect the extension chamber and the compression chamber in parallel, A suction passage connecting the pressure chamber and the tank, An extension damping valve provided in the second passage to provide resistance to the flow of liquid from the extension chamber to the compression chamber, A pressure-side check valve provided in the third passage, which allows only the flow of liquid from the pressure-side chamber to the extension-side chamber, The suction passage is provided with an extension check valve that allows only the flow of liquid from the tank to the pressure chamber, The first passage and the bypass passage connect the pressure chamber and the tank, with the working chamber being the pressure chamber and the tank. The damping valve provides resistance to the flow of liquid while allowing only the flow of liquid from the pressure chamber to the tank. The check valve allows only the flow of liquid from the pressure chamber to the tank. A buffer characterized by the following features.

2. A buffer body having a cylinder, a piston inserted into the cylinder so as to be axially movable, a piston rod inserted into the cylinder and connected to the piston, and a plurality of working chambers filled with liquid, A first passage and a bypass passage that connect the aforementioned operating chambers, A damping valve provided in the first passage that provides resistance to the flow of liquid from one working chamber to the other working chamber, A check valve provided in the bypass path that allows only the flow of liquid from one working chamber to the other working chamber, A needle valve is provided in series with the check valve in the bypass path, and the flow path area can be changed. The housing comprises the check valve and the needle valve, The aforementioned needle valve is A cylindrical needle case inserted into the housing, The needle is inserted into the needle case so as to be movable in the axial direction, The needle case has an annular recess formed at one end by an enlarged inner diameter, The aforementioned check valve is A disc-shaped valve seat member is sandwiched between one end of the needle case and the housing, facing the annular recess and in close contact with the needle case and the housing, and has a hole that penetrates the thickness of the wall, An annular valve body is housed in the annular recess so as to be movable in the axial direction and seated toward and away from the valve seat member, It has an annular biasing member housed in the annular recess and biasing the annular valve body toward the valve seat member, The bypass path connects the working chambers through the hole and the inside of the needle case. A buffer characterized by the following features.

3. The needle case has an annular valve seat on its inner circumference on which the needle sits and separates. The buffer according to feature 2.

4. The annular valve body and the biasing member are positioned radially by the side wall surface of the annular recess in the needle case. The buffer according to feature 2.

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