buffer

Abstract

To provide a buffer which can exert a high attenuation force during contraction operation while maintaining an attenuation force adjustment width.SOLUTION: A buffer D according to the present invention includes: a cylinder 1; a piston rod 2 inserted into the cylinder 1 in an axially movable manner; a piston 3 defining the inside of the cylinder 1 into an extension-side chamber R1 and a compressed-side chamber R2; an outer tube 4 forming an annular passage C covering an outer peripheral side of the cylinder 1; a tank 18 for storing liquid; a main attenuation passage M for applying resistance to a flow of liquid between the extension-side chamber R1 and the compressed-side chamber R2; an outer passage P provided on an outer side of the cylinder 1; a discharge passage EP which communicates the tank 18 and the compressed-side chamber R2; a suction passage SP which communicates the tank 18 and the compressed-side chamber R2; a variable valve 21 provided on the outer passage P; a compressed-side attenuation valve 30 provided on the discharge passage EP; and a suction check valve 31 provided on the suction passage SP.SELECTED DRAWING: Figure 3

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

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

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Conventional shock absorbers allow for a wide range of damping force adjustment, but they employ a structure where the compression chamber is directly connected to the tank. As a result, during compression, the pressure in the compression chamber cannot be raised above the tank pressure, and the damping force during compression is capped. Therefore, it has been difficult to meet the demand for high damping force during compression.

[0007] Therefore, the present invention aims to provide a shock absorber that can exert high damping force during compression operation while ensuring a wide range of damping force adjustment. [Means for solving the problem]

[0008] To solve the aforementioned problems, the buffer of the present invention comprises a cylinder, a piston rod inserted into the cylinder so as to be movable in the axial direction, a piston connected to the piston rod and inserted into the cylinder so as to be movable in the axial direction, and dividing the inside of the cylinder into an extension chamber and a compression chamber, an outer tube covering the outer circumference of the cylinder and forming an annular passage between it and the cylinder that communicates with the extension chamber, a tank for storing liquid, a main damping passage that provides resistance to the flow of liquid moving back and forth between the extension chamber and the compression chamber, an external passage provided outside the cylinder, one end of which communicates with the extension chamber via the annular passage and the other end of which communicates with the compression chamber, a discharge passage connecting the compression chamber and the tank, a suction passage connecting the tank and the compression chamber, a variable valve provided in the external passage that can change the flow rate distribution ratio between the main damping passage and the external passage, a compression damping valve provided in the discharge passage that provides resistance to the flow of liquid from the compression chamber to the tank, and a suction check valve provided in the suction passage that allows only the flow of liquid from the tank to the compression chamber.

[0009] With this type of shock absorber, a variable valve is provided in the external passage that bypasses the main damping passage connecting the extension chamber and the compression chamber. By opening and closing the variable valve, the flow rate distribution ratio between the main damping passage and the external passage can be adjusted to ensure a wide range of damping force adjustments while also allowing for adjustment of the damping force. Furthermore, since a compression damping valve is provided in the discharge passage, the pressure in the compression chamber can be increased to above the tank pressure during contraction, generating a higher damping force than conventional shock absorbers.

[0010] Furthermore, the shock absorber may be equipped with a low-speed valve in the external passage, which is provided in series with the variable valve and resists the flow of liquid moving between the extension chamber and the compression chamber. With a shock absorber configured in this way, the variable valve is opened and the low-speed valve in the external passage is activated, allowing the damping force to be adjusted to high or low in the low-speed range of the extension and contraction speed, and generating a damping force suitable for driving on smooth roads with few bumps, where the saddle-type vehicle does not vibrate at high speeds.

[0011] Furthermore, the buffer includes a valve housing that accommodates a variable valve, a compression damping valve, and a suction check valve, and the variable valve, compression damping valve, and suction check valve may be coaxially inserted into the valve housing. With a buffer configured in this way, the valve housing can be cylindrical, and the assembly work of housing the variable valve, compression damping valve, and suction check valve within the valve housing is also simplified, thus reducing manufacturing costs.

[0012] Furthermore, the variable valve in the buffer has a valve seat member with a port, a valve body that moves relative to the valve seat member to open and close the port, and a case that has a cylindrical portion housing the valve seat member and valve body, and a shaft portion connected to the cylindrical portion. The compression damping valve and suction check valve may be mounted on the shaft portion of the case. With a buffer configured in this way, since the compression damping valve and suction check valve are mounted on the shaft portion of the case housing the valve seat member and valve body of the variable valve, the compression damping valve and suction check valve can be pre-assembled to the variable valve and housed in the valve housing as a valve assembly, making the assembly of the buffer very easy and reducing manufacturing costs.

[0013] Furthermore, the low-speed valve in the shock absorber may be mounted on the shaft of the valve seat member. With a shock absorber configured in this way, all valves installed outside the cylinder are mounted on the shaft of the case that houses the valve seat member and valve body of the variable valve. As a result, all valves installed outside the cylinder can be pre-assembled and housed in the valve housing as a valve assembly, making the assembly of the shock absorber very easy and further reducing manufacturing costs. [Effects of the Invention]

[0014] According to the shock absorber of the present invention, it is possible to achieve high damping force during compression operation while ensuring a wide range of damping force adjustment. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a cross-sectional view of a buffer in one embodiment. [Figure 2] Figure 2 shows the damping force characteristics of a shock absorber in one embodiment. [Figure 3] Figure 3 is a partially enlarged cross-sectional view of a buffer with a specific structure. [Figure 4] Figure 4 is an enlarged cross-sectional view of a low-speed valve, a compression-side damping valve, and a suction check valve with their specific structures. [Figure 5] Figure 5 is a partially enlarged cross-sectional view of a first modified example of a buffer with a specific structure. [Figure 6] Figure 6 is a partially enlarged cross-sectional view of a second modified example of a buffer with a specific structure. [Figure 7] Figure 7 is a partially enlarged cross-sectional view of a third modified example of a buffer with a specific structure. [Figure 8] Figure 8 is a partially enlarged cross-sectional view of a fourth modified example of a buffer with a specific structure. [Modes for carrying out the invention]

[0016] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIG. 1, in one embodiment, a shock absorber D includes a cylinder 1, a piston rod 2 that is inserted into the cylinder 1 so as to be axially movable, and a piston rod 2 that is connected to the piston rod 2 and is inserted into the cylinder 1 so as to be axially movable and divides the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2. A piston 3, an outer tube 4 that covers the outer peripheral side of the cylinder 1 and forms an annular passage C communicating with the extension chamber R1 between the outer tube 4 and the cylinder 1, a tank 18 that stores liquid, a main damping passage M that provides resistance to the flow of liquid flowing back and forth between the extension chamber R1 and the compression chamber R2, an external passage P that is provided outside the cylinder 1 and has one end communicating with the extension chamber R1 through the annular passage C and the other end communicating with the compression chamber R2, a discharge passage EP that communicates the compression chamber R2 and the tank 18, a suction passage SP that communicates the tank 18 and the compression chamber R2, a variable valve 21 provided in the external passage P that can change the distribution ratio of the flow rates of the main damping passage M and the external passage P, a compression-side damping valve 30 provided in the discharge passage EP that provides resistance to the flow of liquid from the compression chamber R2 to the tank 18, and a suction check valve 31 provided in the suction passage SP that allows only the flow of liquid from the tank 18 to the compression chamber R2.

[0017] And although not shown in the drawings, this shock absorber D is interposed and used between the vehicle body and the rear wheel in a saddle-type vehicle such as a motorcycle, and suppresses the vibrations of the vehicle body and the rear wheel. Note that the shock absorber D may be used for suppressing vibrations other than saddle-type vehicles.

[0018] Hereinafter, each part of the shock absorber D will be described in detail. As shown in FIG. 1, the cylinder 1 is cylindrical, the upper end in FIG. 1 is closed by a rod guide 17, and the lower end in FIG. 1 is closed by a cap 10. Further, the cylinder 1 includes a through hole 1a that communicates the inside and outside of the cylinder 1 on a side portion near the upper end in FIG. 1, and a flange 1b on the outer periphery of the lower end in FIG. 1. A seal ring 11 that closely contacts the inner periphery of the cap 10 is mounted on the outer periphery of the flange 1b, and the space between the cylinder 1 and the cap 10 is sealed.

[0019] Further, a piston rod 2 is inserted into the cylinder 1 so as to be axially movable, and the upper end in FIG. 1, which is the tip of the piston rod 2, protrudes outward from the upper end in FIG. 1 of the cylinder 1.

[0020] The piston rod 2 has a small-diameter portion 2a with an outer diameter smaller at the lower end in FIG. 1 than at the upper end, and a piston 3 is mounted on the outer periphery thereof. Further, a bracket 6 that can be connected to the vehicle body in a straddle-type vehicle is mounted on the upper end in FIG. 1 of the piston rod 2.

[0021] A piston 3 attached to the piston rod 2 is inserted into the cylinder 1 so as to be axially movable, and the inside of the cylinder 1 is partitioned by the piston 3 into an expansion chamber R1 above the piston 3 and a compression chamber R2 below the piston 3. The expansion chamber R1 and the compression chamber R2 are filled with a liquid such as hydraulic oil. Note that the liquid is hydraulic oil in the present embodiment, but it may be a liquid such as water or an aqueous solution other than hydraulic oil.

[0022] Subsequently, the piston 3 is annular and is mounted on the outer periphery of the small-diameter portion 2a of the piston rod 2, and includes an expansion port 3a and a compression port 3b that respectively communicate with the expansion chamber R1 and the compression chamber R2 in parallel. An expansion main damping valve 13 that is annular and is mounted on the outer periphery of the small-diameter portion 2a to open and close the expansion port 3a is laminated on the lower end in FIG. 1 of the piston 3. Further, a compression main damping valve 14 that is annular and is mounted on the outer periphery of the small-diameter portion 2a to open and close the compression port 3b is laminated on the upper end in FIG. 1 of the piston 3. The piston 3, the expansion main damping valve 13, and the compression main damping valve 14 are fitted on the outer periphery of the small-diameter portion 2a of the piston rod 2 and are fixed to the piston rod 2 by a piston nut 15 screwed to the lower end of the small-diameter portion 2a.

[0023] In this embodiment of the shock absorber D, the extension-side main damping valve 13 is constructed by stacking multiple annular plates on the lower end of the piston 3 in Figure 1. The inner circumference is fixed, and when the outer circumference bends due to the pressure in the extension-side chamber R1, it opens the extension-side port 3a. The extension-side main damping valve 13 is capable of opening and closing the extension-side port 3a. When the shock absorber D extends, it opens to resist the flow of liquid passing through the extension-side port 3a from the extension-side chamber R1 to the compression-side chamber R2. When the shock absorber D contracts, it closes to block the extension-side port 3a. Note that the extension-side main damping valve 13 can be any damping valve that can resist the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2 and exert a damping force that hinders the extension of the shock absorber D when it extends. Therefore, it may be a damping valve other than a stacked leaf valve.

[0024] In contrast, the compression-side main damping valve 14 in the buffer D of this embodiment is a laminated leaf valve constructed by stacking multiple annular plates on the upper end of the piston 3 in Figure 1, with the inner circumference fixed and the outer circumference bending due to the pressure in the compression-side chamber R2, thereby opening the compression-side port 3b. The compression-side main damping valve 14 is capable of opening and closing the compression-side port 3b, opening when the buffer D contracts to provide resistance to the flow of liquid passing through the compression-side port 3b from the compression-side chamber R2 to the extension-side chamber R1, and closing when the buffer D extends to block the compression-side port 3b. Note that the compression-side main damping valve 14 only needs to be a damping valve capable of providing resistance to the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1 and exerting a damping force that prevents the buffer D from contracting when the buffer D contracts, so it may be a damping valve other than a laminated leaf valve. Also, although not shown in the figure, an orifice is provided in parallel with the extension-side main damping valve 13 and the compression-side main damping valve 14. The orifice is formed, for example, by a notch in the annular plate that constitutes the extension-side main damping valve 13 and the compression-side main damping valve 14, or by a mark made on the valve seat of the piston 3 on which the annular plate sits and separates.

[0025] Thus, the extension port 3a and the compression port 3b of the piston 3 connect the extension chamber R1 and the compression chamber R2. Furthermore, when the extension main damping valve 13 and the compression main damping valve 14 are closed, the orifice provides resistance to the flow of liquid moving back and forth between the extension chamber R1 and the compression chamber R2 through the extension port 3a and the compression port 3b. When the extension main damping valve 13 and the compression main damping valve 14 are open, the extension main damping valve 13 provides resistance to the flow of liquid passing through the extension port 3a, and the compression main damping valve 14 provides resistance to the flow of liquid passing through the compression port 3b. In this embodiment, the extension port 3a, the compression port 3b, the orifice, the extension main damping valve 13, and the compression main damping valve 14 constitute a main damping passage M that provides resistance to the flow of liquid moving between the extension chamber R1 and the compression chamber R2. The main damping passage M may be configured with only a single passage and a bidirectional valve, such as an orifice or choke, provided in the passage to resist the flow of liquid reciprocating between the extension chamber R1 and the compression chamber R2.

[0026] As shown in Figure 1, the outer tube 4 is cylindrical and covers the outer circumference of the cylinder 1, forming an annular passage C through the annular gap between it and the cylinder 1. The outer tube 4 has a hole 4a located slightly above its lower end that connects the inside and outside, and a threaded portion 4b located on its outer circumference, spaced above the hole 4a. The lower end of the outer tube 4 in Figure 1 is closed by a cap 10 that is screwed in using the threaded portion 4b on its outer circumference.

[0027] Furthermore, a rod guide 17 is fixed to the inner circumference of the upper end of the outer tube 4 in Figure 1, and the upper end of the outer tube 4 is closed by the rod guide 17. The rod guide 17 is annular in shape and has a fitting portion 17a at its lower end into which the upper end of the cylinder 1 fits, and has an annular sealing member 17b and an annular bush 17c on its inner circumference that slide against the outer circumference of the piston rod 2. The rod guide 17 is fixed to the outer tube 4 to position the cylinder 1 radially concentrically with the outer tube 4 and closes the upper end of the annular passage C between the cylinder 1 and the outer tube 4 in Figure 1. In addition, the rod guide 17 seals the outer circumference of the piston rod 2 with the sealing member 17b, sealing the inside of the cylinder 1, and the bush 17c guides the axial movement of the piston rod 2.

[0028] The cap 10 is a bottomed cylindrical shape, comprising a cylindrical portion 10a and a bottom portion 10b that closes the lower end of the cylindrical portion 10a. The lower end of the cylinder 1 is inserted into the cylindrical portion 10a, and the cylindrical portion 10a is screw-connected to the outer circumference of the outer tube 4.

[0029] More specifically, as shown in Figure 1, the cylindrical portion 10a includes a threaded portion 10a1 provided on the inner circumference of the upper end, an annular sealing groove 10a2 provided on the inner circumference below the threaded portion 10a1, and an annular groove 10a3 provided on the inner circumference below the sealing groove 10a2. The lower end of the cylinder 1 in Figure 1 and the lower end of the outer tube 4 in Figure 1 are inserted into the inner circumference of the cylindrical portion 10a. More specifically, when the cylinder 1 is inserted into the cylindrical portion 10a, the outer circumference of the flange 1b of the cylinder 1 is fitted into the inner circumference of the cylindrical portion 10a. Then, the lower end of the outer tube 4, which covers the outer circumference of the cylinder 1, is inserted into the cylindrical portion 10a, and the threaded portion 4b is screwed into the threaded portion 10a1. As a result, the flange 1b of the cylinder 1 is sandwiched from above and below by the lower end of the outer tube 4 and the bottom 10b of the cap 10, and the cylinder 1 is fixed to the outer tube 4 and the cap 10.

[0030] When the outer tube 4 is fixed to the cap 10 in this manner, the hole 4a in the outer tube 4 faces the annular groove 10a3 of the cap 10. Therefore, the annular passage C formed between the cylinder 1 and the outer tube 4 is connected to the annular groove 10a3 via the hole 4a in the outer tube 4, and also to the extension chamber R1 via the through hole 1a in the cylinder 1.

[0031] Furthermore, the lower outer circumference of the outer tube 4, between the hole 4a and the threaded portion 4b, faces the sealing groove 10a2 of the cylindrical portion 10a of the cap 10. Therefore, the annular sealing ring 20 housed within the sealing groove 10a2 adheres tightly to the outer circumference of the outer tube 4, sealing the space between the cap 10 and the outer tube 4.

[0032] Furthermore, since the seal ring 11 fitted to the outer circumference of the flange 1b of the cylinder 1 is in close contact with the inner circumference of the cylindrical portion 10a of the cap 10, and is closer to the bottom than the annular groove 10a3, the space between the cylinder 1 and the cap 10 is also sealed, preventing the annular passage C from communicating with the pressure chamber R2 inside the cylinder 1 through the space between the cylinder 1 and the cap 10.

[0033] Next, the bottom portion 10b of the cap 10 has a recess 10b1 in the center of the upper end in Figure 1. Furthermore, a bracket 10c is provided at the lower end of the bottom portion 10b of the cap 10, and the lower end of the shock absorber D can be connected to the swing arm that holds the rear wheel of the saddle-type vehicle via the bracket 10c. In this embodiment, the piston rod 2 is connected to the body of the saddle-type vehicle and the cap 10 is connected to the rear wheel of the saddle-type vehicle, but conversely, the piston rod 2 may be connected to the rear wheel of the saddle-type vehicle and the cap 10 may be connected to the body of the saddle-type vehicle.

[0034] Furthermore, in this embodiment, as shown in Figure 1, the cap 10 includes a valve housing 10d that is connected to the side of the cylindrical portion 10a and arranged parallel to the cylindrical portion 10a, and an integrated tank 18 that is arranged parallel to the valve housing 10d on the side of the valve housing 10d. The tank 18 is cylindrical and houses a bladder 19 inside. The inside of the tank 18 is divided by the bladder 19 into a liquid chamber L filled with liquid 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 an elastic partition such as a bladder 19 or a diaphragm, the partition between the liquid chamber L and the air chamber G inside the tank 18 may also be achieved by using a free piston.

[0035] Inside the valve housing 10d, there is an external passage P that opens from the annular groove 10a3 of the cylindrical portion 10a and leads to a recess 10b1 provided in the bottom portion 10b, a discharge passage EP and a suction passage SP that branch off from the external passage P, a variable valve 21 provided in the external passage P, an extension-side low-speed valve 22 and a compression-side low-speed valve 23 provided in the external passage P as low-speed valves, a compression-side damping valve 30 provided in the discharge passage EP, and a suction check valve 31 provided in the suction passage SP.

[0036] The external passage P has one end connected to the extension chamber R1 inside the cylinder 1 via the annular groove 10a3, hole 4a, annular passage C, and through hole 1a, while the other end opens into the recess 10b1 of the cap 10 and connects to the compression chamber R2 inside the cylinder 1. In this way, the external passage P and the annular passage C are provided outside the cylinder 1 and form a bypass path that connects the extension chamber R1 and the compression chamber R2 by bypassing the main damping passage M provided in the piston 3. Note that the external passage P only needs to connect the extension chamber R1 and the compression chamber R2 outside the cylinder via the annular passage C, so the configuration can be arbitrarily changed to that extent.

[0037] Furthermore, the external passage P is provided with a variable valve 21, an extension-side low-speed valve 22, and a compression-side low-speed valve 23. The variable valve 21 is installed in series with the extension-side low-speed valve 22 and the compression-side low-speed valve 23 relative to the external passage P, while the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are installed in parallel with respect to the external passage P.

[0038] In this embodiment, the variable valve 21 includes a valve body 21a capable of opening and closing an external passage P that forms part of the bypass path, a spring 21b that biases the valve body 21a to close, and a solenoid 21c capable of generating thrust in the opening direction against the biasing force of the spring 21b. The degree of opening can be adjusted according to the amount of current supplied to the solenoid 21c, and the valve closes when the current to the solenoid 21c is cut off. In this embodiment, the variable valve 21 is a solenoid valve capable of adjusting the degree of opening, but it may also be a solenoid valve capable of adjusting the opening pressure, or a variable valve in which the degree of opening or the opening pressure is adjusted by manual operation.

[0039] The extension-side low-speed valve 22 is a damping valve that opens to resist the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2, and closes to block the passage when liquid flows from the compression-side chamber R2 to the extension-side chamber R1. Its opening pressure is lower than that of the extension-side main damping valve 13, and it opens before the extension-side main damping valve 13 when the extension speed of the buffer D is low, thereby generating damping force.

[0040] The compression-side low-speed valve 23 is a damping valve that opens to resist the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1, and closes to block the passage when liquid flows from the extension-side chamber R1 to the compression-side chamber R2. Its opening pressure is lower than that of the compression-side main damping valve 14, and it opens before the compression-side main damping valve 14 when the contraction speed of the buffer D is low, thereby generating damping force.

[0041] In this embodiment, an extension-side low-speed valve 22 is provided in the external passage P, which allows only the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2 and provides resistance to the flow of liquid passing through it, and a compression-side low-speed valve 23 is provided, which allows only the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1 and provides resistance to the flow of liquid passing through it. These extension-side low-speed valve 22 and compression-side low-speed valve 23 are designated as low-speed valves, but any valve that allows the flow of liquid reciprocating between the extension-side chamber R1 and the compression-side chamber R2 and provides resistance to the flow of liquid passing through it may also be designated as a low-speed valve.

[0042] The discharge passage EP and the suction passage SP are located in the middle of the external passage P and branch off from the pressure chamber side of the variable valve 21, the extension-side low-speed valve 22, and the compression-side low-speed valve 23, and are connected to the liquid chamber L of the tank 18, respectively.

[0043] The pressure-side damping valve 30 is provided in the discharge passage EP and is a damping valve that opens to resist the flow of liquid from the pressure-side chamber R2 to the tank 18, and closes to block the discharge passage EP when liquid flows from the tank 18 to the pressure-side chamber R2. The suction check valve 31 is provided in the suction passage SP and is a damping valve that opens to allow the flow of liquid from the tank 18 to the pressure-side chamber R2 to pass through with almost no resistance, but closes to block the suction passage SP when liquid flows from the pressure-side chamber R2 to the tank 18.

[0044] The shock absorber D of this embodiment is configured as described above, and the operation of the shock absorber D will be explained below. When the shock absorber D extends, the piston rod 2 retracts from the cylinder 1 and the piston 3 compresses the extension chamber R1. As a result, the liquid in the extension chamber R1 moves to the compression chamber R2 through the orifice (not shown) in the main damping passage M, the extension main damping valve 13 in the main damping passage M, or the extension low-speed valve 22 in the external passage P. At the same time, the suction check valve 31 opens, and liquid equivalent to the volume of the piston rod 2 that retracted from the cylinder 1 is supplied from the tank 18 into the cylinder 1 via the suction passage SP. The flow of liquid from the extension chamber R1 to the compression chamber R2 is resisted by the main damping passage M or the extension low-speed valve 22, and an extension damping force is generated due to this resistance. Regarding the resistance applied when the liquid passes through the main damping passage M, when the extension speed of the buffer D is in the low-speed range, the extension-side main damping valve 13 does not open and resistance is applied to the liquid flow by an orifice (not shown). When the extension speed of the buffer D is in the high-speed range, the extension-side main damping valve 13 opens and resistance is applied to the liquid flow by the extension-side main damping valve 13. When the amount of current supplied to the variable valve 21 is changed, the distribution ratio of the liquid passing through the main damping passage M and the extension-side low-speed valve 22 changes when the buffer D is extended.

[0045] Specifically, during the extension operation of the buffer D, when the variable valve 21 is open, the liquid passes through the main damping passage M and the extension-side low-speed valve 22. However, when the variable valve 21 is closed, the external passage P is blocked, so the liquid cannot pass through the extension-side low-speed valve 22 and moves only through the main damping passage M from the extension-side chamber R1 to the compression-side chamber R2. Furthermore, when current is supplied to the variable valve 21 to open it and the amount of current supplied is increased, the degree of opening of the variable valve 21 increases, and the flow rate of liquid passing through the external passage P increases. As a result, the proportion of liquid passing through the extension-side low-speed valve 22 increases, while the proportion of liquid passing through the main damping passage M decreases. Therefore, by adjusting the amount of current supplied to the variable valve 21, the damping force characteristics generated by the shock absorber D when the extension speed is in the low-speed range during extension operation can be changed, as shown in Figure 2, from the soft characteristics mainly generated by the extension-side low-speed valve 22 (shown by the dashed line in Figure 2) to the hard characteristics mainly generated by the main damping passage M (shown by the solid line in Figure 2), by adjusting the amount of current supplied to the variable valve 21. Furthermore, when the extension speed is in the high-speed range during extension operation, the extension-side main damping valve 13 opens wide regardless of the degree of opening of the variable valve 21, causing the liquid to preferentially pass through the main damping passage M, and thus the shock absorber D generates damping force through the extension-side main damping valve 13.

[0046] Conversely, when the shock absorber D is contracted, the piston rod 2 enters the cylinder 1 and the piston 3 compresses the compression chamber R2. As a result, the liquid in the compression chamber R2 moves to the extension chamber R1 through an orifice (not shown) in the main damping passage M, the main compression damping valve 14 in the main damping passage M, or the low-speed compression valve 23 in the external passage P. At the same time, the volume of liquid due to the piston rod 2 entering the cylinder 1 becomes excess in the cylinder 1, so the liquid in the compression chamber R2 passes through the compression damping valve 30 and is discharged from the compression chamber R2 to the tank 18. The flow of liquid from the compression chamber R2 to the extension chamber R1 is resisted by the main damping passage M or the low-speed compression valve 23, and the flow of liquid from the compression chamber R2 to the tank 18 is resisted by the compression damping valve 30, generating a compression damping force due to the aforementioned resistances. Regarding the resistance applied when the liquid passes through the main damping passage M, when the contraction speed of the buffer D is in the low-speed range, the pressure-side main damping valve 14 does not open and resistance is applied to the liquid flow by an orifice (not shown). When the contraction speed of the buffer D is in the high-speed range, the pressure-side main damping valve 14 opens and resistance is applied to the liquid flow by the pressure-side main damping valve 14. When the amount of current supplied to the variable valve 21 is changed, the distribution ratio of the liquid passing through the main damping passage M and the pressure-side low-speed valve 23 changes when the buffer D is contracting.

[0047] Specifically, during the contraction operation of the buffer D, when the variable valve 21 is open, the liquid passes through the main damping passage M and the compression-side low-speed valve 23. However, when the variable valve 21 is closed, the external passage P is blocked, so the liquid cannot pass through the compression-side low-speed valve 23 and moves only through the main damping passage M from the compression-side chamber R2 to the extension-side chamber R1. Furthermore, when current is supplied to the variable valve 21 to open it and the amount of current supplied is increased, the degree of opening of the variable valve 21 increases, and the flow rate of liquid passing through the external passage P increases. As a result, the proportion of liquid passing through the compression-side low-speed valve 23 increases, while the proportion of liquid passing through the main damping passage M decreases. Therefore, by adjusting the amount of current supplied to the variable valve 21, the damping force characteristics generated by the buffer D during contraction when the contraction speed is in the low-speed range can be changed, as shown in Figure 2, from a soft characteristic where resistance is applied to the liquid moving from the compression chamber R2 to the extension chamber R1 by the compression-side low-speed valve 23 (shown by the dashed line in Figure 2) to a hard characteristic where resistance is applied by the main damping passage M (shown by the solid line in Figure 2). Furthermore, during contraction when the contraction speed is in the high-speed range, the compression-side main damping valve 14 opens wide regardless of the degree of opening of the variable valve 21, and the liquid moving from the compression chamber R2 to the extension chamber R1 preferentially passes through the compression-side main damping valve 14. As a result, the buffer D generates damping force through the compression-side main damping valve 14. Furthermore, when the shock absorber D is contracted, excess liquid in the cylinder 1 passes through the pressure-side damping valve 30 and moves from the pressure-side chamber R2 to the tank 18. As a result, the pressure in the pressure-side chamber R2 can be increased to a pressure higher than the tank pressure by the pressure-side damping valve 30, and the shock absorber D can generate a higher pressure-side damping force than conventional shock absorbers.

[0048] In this embodiment, the shock absorber D is provided with an extension-side low-speed valve 22 and a compression-side low-speed valve 23 as low-speed valves. However, it is also possible to eliminate the extension-side low-speed valve 22 and the compression-side low-speed valve 23 and adjust the damping force by changing the degree of opening of the variable valve 21.

[0049] As described above, the buffer D of this embodiment comprises a cylinder 1, a piston rod 2 inserted into the cylinder 1 so as to be movable in the axial direction, a piston 3 connected to the piston rod 2 and inserted into the cylinder 1 so as to be movable in the axial direction, and dividing the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, an outer tube 4 covering the outer circumference of the cylinder 1 and forming an annular passage C between it and the cylinder 1 that communicates with the extension chamber R1, a tank 18 for storing liquid, a main damping passage M that provides resistance to the flow of liquid moving back and forth between the extension chamber R1 and the compression chamber R2, and a part provided outside the cylinder 1 at one end The system includes an external passage P which is connected to the extension chamber R1 via an annular passage C and whose other end is connected to the pressure chamber R2, a discharge passage EP which connects the pressure chamber R2 and the tank 18, a suction passage SP which connects the tank 18 and the pressure chamber R2, a variable valve 21 provided in the external passage P which can change the flow rate distribution ratio between the main damping passage M and the external passage P, a pressure damping valve 30 provided in the discharge passage EP which provides resistance to the flow of liquid from the pressure chamber R2 to the tank 18, and a suction check valve 31 provided in the suction passage SP which allows only the flow of liquid from the tank 18 to the pressure chamber R2.

[0050] In the shock absorber D configured in this way, a variable valve 21 is provided in the external passage P that bypasses the main damping passage M connecting the extension chamber R1 and the compression chamber R2. By opening and closing the variable valve 21, the flow rate distribution ratio between the main damping passage M and the external passage P can be adjusted to ensure a wide range of damping force adjustment while also allowing for adjustment of the damping force to a high or low level. Furthermore, since a compression damping valve 30 is provided in the discharge passage EP, the pressure in the compression chamber R2 can be increased to above the tank pressure during contraction, generating a higher damping force than conventional shock absorbers. In summary, according to the shock absorber D of this embodiment, a high damping force can be exerted during contraction while ensuring a wide range of damping force adjustment.

[0051] Furthermore, the shock absorber D of this embodiment is equipped with an extension-side low-speed valve (low-speed valve) 22 and a compression-side low-speed valve (low-speed valve) 23, which are provided in series with the variable valve 21 in the external passage P and provide resistance to the flow of liquid moving between the extension-side chamber R1 and the compression-side chamber R2. With the shock absorber D configured in this way, the variable valve 21 is opened to activate the extension-side low-speed valve (low-speed valve) 22 and the compression-side low-speed valve (low-speed valve) 23 in the external passage P, allowing for adjustment of the damping force in the low-speed range of extension and compression speeds, and generating a damping force suitable for when a saddle-type vehicle travels on smooth roads with few bumps where vibrations do not occur at high speeds.

[0052] Furthermore, in the buffer D of this embodiment, since an external passage P is provided outside the cylinder 1, the variable valve 21, the extension-side low-speed valve 22, the compression-side low-speed valve 23, the compression-side damping valve 30, and the suction check valve 31 can be consolidated into a valve housing 10d located outside the cylinder 1, making the assembly of the buffer D easier.

[0053] In the above explanation, the valve housing 10d, variable valve 21, extension-side low-speed valve 22, compression-side low-speed valve 23, compression-side damping valve 30, and suction check valve 31 were described using circuit diagrams. The following will provide a detailed explanation of their specific structures.

[0054] As shown in Figure 3, the valve housing 10d comprises a bottomed cylindrical valve housing 40 with an open upper end, and a toped cylindrical valve cap 41 that is screw-connected to the inner circumference of the upper end of the valve housing 40. The space formed by the valve housing 40 and the valve cap 41 houses the variable valve 21, the extension low-speed valve 22, the compression low-speed valve 23, the compression damping valve 30, and the suction check valve 31.

[0055] The valve housing 40 has an inner diameter that gradually widens from the bottom upwards, and includes a small-diameter section 40a with a small inner diameter, a medium-diameter section 40b with an inner diameter larger than the small-diameter section 40a, and a large-diameter section 40c with an inner diameter larger than the medium-diameter section 40b. It also includes a passage 40d that opens from the annular groove 10a3 of the cap 10 and leads to the inner circumference of the large-diameter section 40c, a passage 40e that opens from the bottom 10b of the cap 10 and leads to the inner circumference of the small-diameter section 40a, and a passage 40f that opens on the inner circumference of the small-diameter section 40a from the bottom side of the opening of passage 40e and communicates with the inside of the tank 18.

[0056] Furthermore, the extension chamber R1 is connected to the compression chamber R2 by the passage 40d in the valve housing 40, the inside of the valve housing 40, the passage 40e, and the annular passage C, and the compression chamber R2 is connected to the tank 18 by the passage 40e, the inside of the valve housing 40, and the passage 40f. Thus, the external passage P is formed by the passage 40d in the valve housing 40, the inside of the valve housing 40, and the passage 40e.

[0057] The valve cap 41 is cylindrical with a top, and has a threaded portion 41a on the outer circumference of its lower end in Figure 3. It is fixed to the valve housing 40 by screwing the threaded portion 41a to a threaded portion 40g provided on the inner circumference of the large diameter portion 40c of the valve housing 40. A seal ring 41b is fitted to the outer circumference of the valve cap 41, which is in close contact with the inner circumference of the large diameter portion 40c of the valve housing 40. The seal ring 41b seals the space formed between the valve housing 40 and the valve cap 41.

[0058] The variable valve 21 is configured as a solenoid valve comprising a solenoid Sol, a valve seat member 42 having a port 42a, a valve body 43 driven by the solenoid Sol to move relative to the valve seat member 42 to open and close the port 42a, a case 44 housing the valve seat member 42 and the valve body 43, and a coil spring 45 for biasing the valve body 43.

[0059] The solenoid Sol, although not shown in detail, consists of a bottomed cylindrical frame 35, a coil (not shown) housed within the frame 35, a first fixed core (not shown) housed at the bottom of the frame 35, an annular second fixed core 36 fitted to the inner circumference of the open end of the frame 35 and facing the first fixed core with a gap between them, and the first fixed core and the second fixed core 36 It includes a plunger provided between the two and driven downward from the frame 35 by the supply of current to the coil, and a push rod 37 connected to the plunger and inserted into the inner circumference of the second fixed iron core 36.

[0060] In this configuration, the solenoid Sol has the tip of the push rod 37, which is the lower end in Figure 3, in contact with the valve body 43. When current is supplied to the coil (not shown), the plunger is attracted to the second fixed iron core 36, generating a thrust that pushes the valve body 43 downward in Figure 3 via the push rod 37.

[0061] The valve seat member 42 is cylindrical and has four ports 42a spaced apart along the circumferential direction that communicate the inside and outside. The valve seat member 42 is fitted without play at its upper end in Figure 3 into the annular recess 36a of the second fixed core 36 and is radially centered by the solenoid Sol.

[0062] The valve body 43 is cylindrical with a top, and its outer circumference slides against the inner circumference of the valve seat member 42. Its axial length is shorter than that of the valve seat member 42, and it is permitted to move axially within the valve seat member 42. The valve body 43 has a hole 43a at its top, as well as four ports 43b that communicate inside and outside, arranged circumferentially and spaced apart along the cylindrical portion. When viewed from the axial direction, the valve seat member 42 and the valve body 43 are positioned in the same phase in the circumferential direction. Furthermore, when the top of the valve body 43 contacts the bottom of the annular recess 36a of the second fixed core 36 of the solenoid Sol, the ports 43b are positioned above the ports 42a of the valve seat member 42 in Figure 3 and are blocked from the inner circumference of the valve seat member 42. Then, as the valve body 43 moves downward in Figure 3 from the position where its top contacts the second fixed iron core 36 relative to the valve seat member 42, port 43b eventually comes into contact with port 42a, and when the two are at exactly the same height, they face each other and the degree of overlap is maximized.

[0063] Therefore, when the valve body 43 is driven by the solenoid Sol, the valve body 43 moves axially within the valve seat member 42, thereby changing the communication state between port 42a and port 43b from a state where port 42a of the valve seat member 42 is completely closed to a state where port 42a is fully open. In this way, the valve body 43 can open and close port 42a of the valve seat member 42 by moving relative to the valve seat member 42. If no current is supplied to the solenoid Sol, port 42a is closed, and if current is supplied to the solenoid Sol, it moves downward and port 43b faces port 42a, opening port 42a. Furthermore, since the variable valve 21 can adjust the axial relative position of the valve body 43 with respect to the valve seat member 42 according to the amount of current supplied to the solenoid Sol, the degree of opening of port 42a can be changed by adjusting the amount of current supplied to the solenoid Sol. Although there are four ports 42a and four ports 43b, the number of ports can be changed as long as the number is the same, and the shape of ports 42a and 43b can also be changed as desired.

[0064] The case 44 comprises a bottomed cylindrical portion 44a, a flange 44b provided on the outer circumference of the upper end of the cylindrical portion 44a in Figure 3, a shaft portion 44c extending downward from the center of the lower end of the cylindrical portion 44a in Figure 3, and a hole 44d opening from the bottom of the cylindrical portion 44a and leading to the outer circumference of the shaft portion 44c, with a portion of the upper end including the flange 44b housed inside the valve cap 41. The shaft portion 44c has a smaller outer diameter midway along its circumference and comprises a stepped portion 44g provided midway along its outer circumference, a valve mounting portion 44h with a smaller outer diameter below the stepped portion 44g in Figure 3, and a threaded portion 44i provided on the outer circumference of the tip of the valve mounting portion 44h which is the lower end in Figure 3. Furthermore, the extension-side low-speed valve 22, the compression-side low-speed valve 23, the compression-side damping valve 30, and the suction check valve 31 are mounted on the outer circumference of the valve mounting portion 44h. However, since the aforementioned hole 44d is on the outer circumference of the shaft portion 44c and opens towards the cylindrical portion side which is above the stepped portion 44g in Figure 3, the hole 44d is not blocked.

[0065] As shown in Figure 4, the inner diameter of the cylindrical portion 44a is larger than the outer diameter of the valve seat member 42. When the valve seat member 42 is housed inside the cylindrical portion 44a, a gap is created between the cylindrical portion 44a and the valve seat member 42, allowing for some play.

[0066] Furthermore, the inner diameter of the cylindrical portion 44a is larger at the open end than at the bottom, so that even when the valve seat member 42 is housed inside the cylindrical portion 44a, the port 42a of the valve seat member 42 faces the larger portion of the cylindrical portion 44a, preventing the port 42a from being blocked. The case 44 also includes a notch 44e that extends from the outer circumference of the flange 44b to the inner circumference of the cylindrical portion 44a, and a seal ring 44f that is fitted around the outer circumference of the cylindrical portion 44a.

[0067] As shown in Figure 4, the outer diameter of the flange 44b, which has the largest outer diameter of the case 44, is smaller than the inner diameter of the valve cap 41. When the upper end of the case 44 is inserted into the valve cap 41, the case 44 is loosely fitted into the valve cap 41, allowing for radial and axial movement.

[0068] Then, the case 44 is inserted into the valve cap 41, and the flange 44b is fully housed inside the valve cap 41. After that, a retaining ring 46, whose inner diameter is smaller than the outer diameter of the flange 44b, is fitted into the annular groove 41c provided on the inner circumference of the valve cap 41. The case 44 is then temporarily secured by the retaining ring 46, preventing it from falling off the valve cap 41 while still allowing axial movement relative to the valve cap 41.

[0069] The valve seat member 42, valve body 43, and coil spring 45 are housed within the cylindrical portion 44a of the case 44, and the case 44, along with the valve seat member 42, valve body 43, and coil spring 45 housed inside, is temporarily assembled to the valve cap 41 by a retaining ring 46. When the flange 44b abuts against the retaining ring 46 and the movement of the case 44 toward the valve cap 41 is restricted, the annular recess 36a of the second fixed core 36 of the solenoid Sol is located at the bottom of Figure 3. above The valve seat member 42 whose end is in contact with under A gap is created between the end and the bottom of the cylindrical portion 44a of the case 44. Furthermore, in the cylindrical portion 44a of the case 44 bottom With the lower end of the valve seat member 42 in Figure 3 in contact with the inner surface of the part, a gap is created between the upper end of the flange 44b of the case 44 in Figure 3 and the frame 35 and second fixed core 36 of the solenoid Sol, so that the upper end of the flange 44b in Figure 3 does not come into contact with the frame 35 and the second fixed core 36. Therefore, when the case 44 housing the valve seat member 42 is temporarily fastened to the valve cap 41 housing the solenoid Sol with the retaining ring 46, the case 44 can move slightly in the axial direction.

[0070] Furthermore, as mentioned above, the inner diameter of the cylindrical portion 44a in the case 44 is larger than the outer diameter of the valve seat member 42. When the valve seat member 42 is housed in the case 44 and temporarily fastened to the valve cap 41 with the retaining ring 46, even if there is a misalignment between the axis of the valve seat member 42, which is radially aligned by the solenoid Sol, and the case 44, the case 44 does not interfere with the valve seat member 42 and does not affect the radial position of the valve seat member 42 relative to the solenoid Sol.

[0071] Next, the coil spring 45 is compressed and sandwiched between the lower end of the valve body 43 in Figure 3 and the bottom of the cylindrical portion 44a of the case 44, constantly biasing the valve body 43 and the push rod 37 and plunger (not shown) of the solenoid Sol upward in Figure 3. When the solenoid Sol is not energized and does not provide thrust to the valve body 43, the coil spring 45 positions the valve body 43 in contact with the second fixed iron core 36, blocking the port 42a of the valve seat member 42, thereby closing the variable valve 21. Four notches 44e are provided at equal intervals in the circumferential direction of the case 44, ensuring communication between the inside and outside of the case 44 even after the case 44 is assembled to the valve cap 41. The number of notches 44e can be arbitrarily changed.

[0072] In this configuration, the variable valve 21 is housed inside the valve housing 10d formed by the valve housing 40 and the valve cap 41, with most of the case 44 being inserted into the valve housing 40 and the solenoid Sol being inserted into the valve cap 41. When the solenoid Sol is not energized, the valve body 43 is pushed up by the coil spring 45, blocking the port 42a of the valve seat member 42 on its outer circumference and closing the valve. When the solenoid Sol is energized, the valve body 43 moves downward in Figure 3 against the biasing force of the coil spring 45, opening the valve by bringing port 43b opposite port 42a. Furthermore, since the degree of opposition between port 43b of the valve body 43 and port 42a of the valve seat member 42 can be changed according to the amount of current supplied to the solenoid Sol, the degree of valve opening of the variable valve 21 can be adjusted by adjusting the amount of current supplied to the solenoid Sol.

[0073] Furthermore, the cylindrical portion 44a of the case 44 is fitted onto the inner circumference of the medium-diameter portion 40b of the valve housing 40, and the seal ring 44f is tightly pressed against the inner circumference of the medium-diameter portion 40b, sealing the space between the case 44 and the valve housing 40. In addition, when the case 44 is inserted into the valve housing 40, the notch 44e in the flange 44b communicates with the passage 40d provided in the valve housing 40.

[0074] Next, the extension-side low-speed valve 22, the compression-side low-speed valve 23, the compression-side damping valve 30, and the suction check valve 31 are mounted on the outer circumference of the valve mounting portion 44h of the shaft portion 44c.

[0075] As shown in Figure 4, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are mounted on the outer circumference of the valve mounting portion 44h, respectively, and are stacked above and below the valve disc 50 in Figure 4, which is also mounted on the outer circumference of the valve mounting portion 44h and fits into the inner circumference of the small-diameter portion 40a of the valve housing portion 40.

[0076] The valve disc 50 is annular in shape and includes an extension-side low-speed port 50a and a compression-side low-speed port 50b that penetrate from the upper end to the lower end along the axial direction, and a seal ring 50c mounted on its outer circumference. The valve disc 50 is fitted to the outer circumference of the valve mounting portion 44h on the shaft portion 44c, and when inserted into the valve housing portion 40 together with the case 44, it fits to the inner circumference above the stepped portion 40a1 of the small-diameter portion 40a in Figure 4, and the seal ring 50c is brought into close contact with the inner circumference of the medium-diameter portion 40b. Thus, the valve disc 50 divides the inside of the valve housing portion 40 into an upper space and a lower space, and communicates the upper space and the lower space only through the extension-side low-speed port 50a and the compression-side low-speed port 50b. The upper space partitioned within the valve housing 40 by the valve disc 50 is connected to the extension chamber R1 via a hole 44d in the case 44, the cylindrical portion 44a of the case 44, a notch 44e in the flange 44b, a passage 40d, an annular groove 10a3, a hole 4a, an annular passage C, and a through hole 1a. The lower space partitioned within the valve housing 40 by the valve disc 50 is connected to the compression chamber R2 via a passage 40e in the valve housing 40. Thus, the external passage P is formed by the extension low-speed port 50a, the compression low-speed port 50b, a hole 44d in the case 44, the cylindrical portion 44a of the case 44, a notch 44e in the flange 44b, a passage 40d, an annular groove 10a3, and a hole 4a, and bypasses the main damping passage M to connect the extension chamber R1 and the compression chamber R2 outside the cylinder 1.

[0077] The extension-side low-speed valve 22 comprises a guide cylinder 51 mounted on the outer circumference of the valve mounting portion 44h and positioned in contact with the inner circumference of the lower end of the valve disc 50 in Figure 4; a valve body 52 mounted on the outer circumference of the guide cylinder 51 so as to be movable in the axial direction; a disc-shaped spring retainer 53 superimposed on the lower end of the guide cylinder 51 in Figure 4 and fitted onto the outer circumference of the valve mounting portion 44h; and an annular spring member 54 interposed between the valve body 52 and the spring retainer 53.

[0078] The valve body 52, although not shown in the symbols, is composed of an annular leaf valve stacked on the lower end of the valve disc 50 in Figure 4 to open and close the lower end of the extension-side low-speed port 50a in Figure 4, a plurality of sub-leaf valves stacked on the lower side of the leaf valve in Figure 4, which are on the back of the leaf valve, with their outer diameters decreasing in stages, and a plurality of spacers stacked on the lower side of the sub-leaf valves in Figure 4, with an outer diameter smaller than that of the sub-leaf valves.

[0079] The spring retainer 53 has an annular seat portion 53a on the outer circumference of its upper end in Figure 4 that protrudes toward the valve disc side. The spring member 54 is annular. in It is elastic, with its outer circumference in contact with the upper end of the seat portion 53a of the spring receiver 53 in Figure 4, and its inner circumference in contact with the lower end of the spacer in the valve body 52 in Figure 4.

[0080] The extension-side low-speed valve 22, configured in this way, when it receives pressure from the extension chamber R1 through the extension-side low-speed port 50a, flexes the outer circumference of the leaf valve, separating it from the valve disc 50 and opening the extension-side low-speed port 50a. Furthermore, as the extension speed of the shock absorber D increases, the spring member 54 flexes, causing the entire valve body 52 to move downward relative to the guide cylinder 51 in Figure 4, thereby greatly opening the extension-side low-speed port 50a. Thus, the extension-side low-speed valve 22 can quickly build up damping force when the shock absorber D extends at extremely low speeds, and when the shock absorber D extends at low speeds beyond extremely low speeds, it can greatly open the extension-side low-speed port 50a and reduce the damping coefficient, thereby improving the ride comfort of a saddle-type vehicle when driving on good roads.

[0081] On the other hand, the compression-side low-speed valve 23 is configured to include a guide cylinder 55 mounted on the outer circumference of the valve mounting portion 44h and positioned in contact with the inner circumference of the upper end of the valve disc 50 in Figure 4, a valve body 56 mounted on the outer circumference of the guide cylinder 55 so as to be movable in the axial direction, a disc-shaped spring retainer 57 superimposed on the upper end of the guide cylinder 55 in Figure 4 and fitted onto the outer circumference of the valve mounting portion 44h, and an annular spring member 58 interposed between the valve body 56 and the spring retainer 57.

[0082] The valve body 56, although not indicated in the reference numerals, has a configuration similar to that of the extension-side low-speed valve 22, and comprises an annular leaf valve stacked on the upper end of the valve disc 50 in Figure 4 to open and close the upper end of the compression-side low-speed port 50b in Figure 4, a plurality of sub-leaf valves stacked on the upper side of the leaf valve in Figure 4, which are the back surfaces of the leaf valve, with their outer diameters decreasing in stages, and a plurality of spacers stacked on the upper side of the sub-leaf valves in Figure 4, with their outer diameters smaller than those of the sub-leaf valves.

[0083] The spring retainer 57 has an annular seat portion 57a ​​on the outer circumference of its lower end in Figure 4 that protrudes toward the valve disc side. The spring member 58 is annular in It is elastic, with its outer circumference in contact with the lower end of the seat portion 57a ​​of the spring receiver 57 in Figure 4, and its inner circumference in contact with the upper end of the spacer in the valve body 56 in Figure 4.

[0084] The compression-side low-speed valve 23, configured in this way, receives pressure from the compression chamber R2 through the compression-side low-speed port 50b, causing the outer circumference of the leaf valve to flex and move away from the valve disc 50, thereby opening the compression-side low-speed port 50b. Additionally, as the contraction speed of the shock absorber D increases, the spring member 58 flexes, causing the entire valve body 56 to move upward relative to the guide cylinder 55 in Figure 4, thereby greatly opening the compression-side low-speed port 50b. Therefore, the compression-side low-speed valve 23 can quickly generate damping force when the shock absorber D contracts at extremely low speeds, and when the shock absorber D contracts at speeds exceeding extremely low speeds, it can greatly open the compression-side low-speed port 50b and reduce the damping coefficient, thereby improving the ride comfort of a saddle-type vehicle when driving on good roads.

[0085] As described above, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are both configured with guide cylinders 51 and 55, valve bodies 52 and 56 mounted on the outer circumference of the guide cylinders 51 and 55 so as to be movable in the axial direction, disc-shaped spring receivers 53 and 57 superimposed on the guide cylinders 51 and 55, and annular spring members 54 and 58 interposed between the valve bodies 52 and 56 and the spring receivers 53 and 57. With the extension-side low-speed valve 22 and the compression-side low-speed valve 23 configured in this way, since the spring members 54 and 58 are made of annular flat springs, the overall length in the axial direction can be shortened while still ensuring the lift amount of the valve bodies 52 and 56 from the valve disc 50, the ports 50a and 50b can be opened wide, and even if the flow rate through ports 50a and 50b increases, it can exert a damping force suitable for driving on good roads without providing excessive resistance. Therefore, with the extension-side low-speed valve 22 and compression-side low-speed valve 23 configured in this way, it is possible to generate damping force suitable for driving on good roads while maintaining a compact size, suppress the increase in size of the shock absorber D equipped with numerous valves, and improve the mountability of the shock absorber D on saddle-type vehicles.

[0086] Furthermore, both the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are constructed by stacking multiple sub-leaf valves on the back side of a leaf valve. However, the number of stacked sub-leaf valves can be arbitrarily changed according to the desired damping force characteristics when the shock absorber D expands and contracts at low speeds, and sub-leaf valves can be eliminated if they are not needed. In addition, the outer diameter of the sub-leaf valves can be appropriately designed and modified according to the desired damping force characteristics when the shock absorber D expands and contracts at low speeds. Moreover, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 may be constructed by stacking annular plates without a spring member.

[0087] The compression damping valve 30 and the suction check valve 31 are each mounted on the outer circumference of the valve mounting portion 44h, and are stacked on a valve disc 60 which is also mounted on the outer circumference of the valve mounting portion 44h and fits onto the inner circumference of the small diameter portion 40a of the valve housing portion 40.

[0088] The valve disc 60 is annular in shape and includes an annular recess 60a that opens from the lower end in Figure 4, and a port 60b that penetrates from the annular recess 60a to the upper end along the axial direction. The valve disc 60 is fitted onto the outer circumference of the valve mounting portion 44h on the shaft portion 44c, and when inserted into the valve housing portion 40 together with the case 44, it fits onto the inner circumference of the small diameter portion 40a of the valve housing portion 40, and the lower end outer circumference abuts against a stepped portion 40a1 formed on the inner circumference of the small diameter portion 40a, which is lower than the passage 40e.

[0089] Furthermore, the valve disc 60 divides the valve housing 40 into two spaces: one above the valve disc 50, which is connected to the pressure chamber R2 by a passage 40e, and another below, which is connected to the tank 18 by a passage 40f.

[0090] The compression damping valve 30 is a laminated leaf valve formed from multiple annular plates stacked on the lower end of the valve disc 60 in Figure 4, with their inner circumferences fixed to the outer circumference of the valve mounting portion 44h. The inner circumference is fixed, allowing for deflection of the outer circumference. Furthermore, the outer diameter of the uppermost annular plate in Figure 4, which has the largest outer diameter of the compression damping valve 30, is smaller than the inner diameter of the stepped portion 40a1 in the valve housing portion 40. This allows the compression damping valve 30 to deflect on its outer circumference without interfering with the inner circumference of the valve housing portion 40.

[0091] The suction check valve 31 includes a valve body 61 that is inserted axially so as to be movable within an annular recess 60a of the valve disc 60, and a spring member 62 that is housed within the annular recess 60a and biases the valve body 61 in a direction that causes it to retract from the annular recess 60a.

[0092] As described above, the valve body 61 has arms extending radially from the inner circumference of the ring, and its outer circumference slides against the inner circumference of the outer peripheral wall forming the annular recess 60a of the valve disc 60. Furthermore, the inner diameter of the ring is larger than the inner diameter of the annular recess 60a, allowing it to move axially within the annular recess 60a. In addition, since the inner diameter of the ring of the valve body 61 is larger than the inner diameter of the annular recess 60a, it does not block the port 60b.

[0093] Furthermore, in this embodiment, the outer diameter of the annular recess 60a and the valve body 61 is larger than the inner diameter of the stepped portion 40a1 formed in the small-diameter portion 40a of the valve housing 40. When the valve disc 60 is fixed with its outer circumference in contact with the stepped portion 40a1, the valve body 61 will not fall out of the annular recess 60a by facing the stepped portion 40a1. In addition, the inner diameter of the valve body 61 is smaller than the outer diameter of the compression damping valve 30, allowing the compression damping valve 30 to seat and dissipate from the valve body 61.

[0094] The spring member 62 is a conical coil spring and is interposed between the bottom of the annular recess 60a and the valve body 61, and is housed within the annular recess 60a, constantly biasing the valve body 61 in the direction of retracting from the annular recess 60a. Note that the spring member 62 may be any spring that does not impose excessive resistance on the flow of liquid passing through the port 60b, and may be a spring other than a coil spring.

[0095] In the suction check valve 31 configured in this way, when liquid flows through port 60b from tank 18 to pressure chamber R2, the spring member 62 contracts and the valve body 61 moves toward the bottom within the annular recess 60a, thus opening port 60b and allowing liquid to flow from tank 18 to pressure chamber R2. Conversely, when liquid flows through port 60b from pressure chamber R2 to tank 18, the suction check valve 31 causes the valve body 61 to come into contact with the stepped portion 40a1. When the valve body 61 comes into contact with the stepped portion 40a1, it cannot exit further from the annular recess 60a and its movement is restricted.

[0096] On the other hand, the pressure-side damping valve 30 flexes its outer circumference to separate the valve body 61, which is in contact with the stepped portion 40a1 and whose movement is restricted, from the liquid flow passing through port 60b from the pressure-side chamber R2 to the tank 18, thereby opening port 60b and providing resistance to the liquid flow passing through port 60b. Conversely, the pressure-side damping valve 30 flexes its outer circumference toward the annular recess 60a toward the liquid flow passing through port 60b from the pressure-side chamber R2 to the tank 18, while the suction check valve 31 moves the valve body 61 toward the bottom of the annular recess 60a to open port 60b.

[0097] The compression damping valve 30 and the suction check valve 31 are both installed on the lower side of the valve disc 60 in Figure 4, and the port 60b of the valve disc 60 functions as the discharge passage EP and the suction passage SP, opening and closing the common port 60b. Alternatively, the valve disc 60 may be provided with a port that functions as a discharge passage EP and a port that functions as a suction passage SP, and the compression damping valve 30, which is made of a laminated leaf valve or the like, which opens and closes the port that functions as a discharge passage EP, and the suction check valve 31, which is made of a leaf valve or the like, which opens and closes the port that functions as a suction passage SP, may be installed on the lower side of the valve disc 60 in Figure 4. However, as shown in Figure 4, if the structure shown in Figure 4 is adopted, in which the port 60b of the valve disc 60 functions as a discharge passage EP and a suction passage SP, and the common port 60b is opened and closed by the compression damping valve 30 and the suction check valve 31, the overall axial length of the valve disc 60, the compression damping valve 30 and the suction check valve 31 is shortened, which is advantageous in terms of miniaturizing the valve.

[0098] The extension-side low-speed valve 22, compression-side low-speed valve 23, compression-side damping valve 30, and suction check valve 31 configured in this way are assembled on the outer circumference of the valve mounting portion 44h on the shaft portion 44c in the order of compression-side low-speed valve 23, valve disc 50, extension-side low-speed valve 22, valve disc 60, suction check valve 31, and compression-side damping valve 30, and then fixed to the valve mounting portion 44h by a nut 59 that is screwed onto the tip of the valve mounting portion 44h.

[0099] As described above, after assembling the extension-side low-speed valve 22, the compression-side low-speed valve 23, the compression-side damping valve 30, and the suction check valve 31 to the valve mounting portion 44h of the case 44, the solenoid Sol is housed inside the valve cap 41, and the case 44, which houses the valve seat member 42, valve body 43, and coil spring 45 of the variable valve 21 inside the cylindrical portion 44a, is temporarily fixed to the valve cap 41 using the retaining ring 46. At this point, all the valves installed outside the cylinder 1 of the shock absorber D are assembled, and the valve assembly is completed.

[0100] When the assembled valve assembly is inserted into the valve housing 40 and the valve cap 41 is screwed onto the valve housing 40, the entire valve assembly is held between the stepped portion 40a1 and the valve cap 41, with the valve disc 60 mounted on the valve mounting portion 44h making contact, and the valve assembly is fixed within the valve housing 10d. In the state where the case 44 is temporarily fixed to the valve cap 41, there is axial play between the case 44 and the valve cap 41, allowing it to move in the axial direction. However, since the entire valve assembly is held between the stepped portion 40a1 and the valve cap 41, all parts of the variable valve 21 except for the movable parts are fixed in place.

[0101] Furthermore, once the valve assembly is housed and fixed in the valve housing 10d, the valve disc 60 receives axial force and comes into close contact with the stepped portion 40a1 of the valve housing 40. This prevents the passage 40e, which communicates with the pressure chamber R2, and the passage 40f, which communicates with the tank 18, from communicating through the space between the valve disc 60 and the valve housing 40, except through the port 60b. Alternatively, a sealing ring may be provided on the outer circumference of the valve disc 60 that comes into close contact with the inner circumference of the valve housing 40 to seal the space between the valve disc 60 and the valve housing 40. Alternatively, the solenoid Sol may be housed inside the valve cap 41, and the case 44, which houses the valve seat member 42, valve body 43, and coil spring 45 of the variable valve 21 inside the cylindrical portion 44a, may be temporarily fixed to the valve cap 41 using a retaining ring 46. Then, the extension low-speed valve 22, compression low-speed valve 23, compression damping valve 30, and suction check valve 31 may be assembled to the valve mounting portion 44h of the case 44.

[0102] The specific shock absorber D configured in this way can apply resistance to the flow of liquid from the extension chamber R1 to the compression chamber R2 during extension operation by the main damping passage M or the extension-side low-speed valve 22, generating an extension-side damping force due to this resistance. Furthermore, since the distribution ratio of the liquid passing through the main damping passage M and the extension-side low-speed valve 22 during the extension operation of this shock absorber D can be adjusted according to the amount of current supplied to the variable valve 21, the damping force can be adjusted from a soft characteristic mainly generated by the extension-side low-speed valve 22 to a hard characteristic mainly generated by the main damping passage M.

[0103] Furthermore, when the shock absorber D is contracting, resistance is applied to the liquid flow from the compression chamber R2 to the extension chamber R1 by the main damping passage M or the compression-side low-speed valve 23, and resistance is applied to the liquid flow from the compression chamber R2 to the tank 18 by the compression-side damping valve 30, generating a compression-side damping force due to the aforementioned resistances. Since the distribution ratio of the liquid passing through the main damping passage M and the compression-side low-speed valve 23 during the contraction operation of the shock absorber D can be adjusted according to the amount of current supplied to the variable valve 21, the damping force can be adjusted from a soft characteristic, where resistance is mainly applied to the liquid flowing from the compression chamber R2 to the extension chamber R1 by the compression-side low-speed valve 23, to a hard characteristic, where resistance is mainly applied by the main damping passage M.

[0104] In the shock absorber D with this specific structure, a variable valve 21 is provided in the external passage P that bypasses the main damping passage M connecting the extension chamber R1 and the compression chamber R2. By opening and closing the variable valve 21, the flow rate distribution ratio between the main damping passage M and the external passage P can be adjusted to ensure a wide range of damping force adjustment while also allowing for adjustment of the damping force. Furthermore, since a compression damping valve 30 is provided in the discharge passage EP, the pressure in the compression chamber R2 can be increased to above the tank pressure during contraction, generating a higher damping force than conventional shock absorbers. In summary, according to the shock absorber D of this embodiment, a high damping force can be achieved during contraction while ensuring a wide range of damping force adjustment.

[0105] Furthermore, in the shock absorber D with a specific structure, an extension-side low-speed valve (low-speed valve) 22 and a compression-side low-speed valve (low-speed valve) 23 are provided in series with the variable valve 21 in the external passage P to provide resistance to the flow of liquid moving between the extension-side chamber R1 and the compression-side chamber R2. This allows for adjustment of the damping force in the low-speed range of extension and compression, and generates a damping force suitable for when the saddle-type vehicle is traveling on smooth roads with few bumps where it does not vibrate at high speeds.

[0106] Furthermore, in a shock absorber D with a specific structure, the variable valve 21, the extension-side low-speed valve 22, the compression-side low-speed valve 23, the compression-side damping valve 30, and the suction check valve 31 can be integrated into the valve housing 10d, making the assembly of the shock absorber D easier.

[0107] Furthermore, the buffer D, which has a specific structure, includes a valve housing 10d that houses a variable valve 21, a compression damping valve 30, and a suction check valve 31. Since the variable valve 21, the compression damping valve 30, and the suction check valve 31 are coaxially inserted into the valve housing 10d, the valve housing 10d can be cylindrical in shape, and the assembly work of housing the variable valve 21, the compression damping valve 30, and the suction check valve 31 inside the valve housing 10d is also simplified, thus reducing manufacturing costs.

[0108] Furthermore, in the buffer D with a specific structure, the variable valve 21 has a valve seat member 42 with a port 42a, a valve body 43 that moves relative to the valve seat member 42 to open and close the port 42a, and a case 44 having a cylindrical portion 44a that houses the valve seat member 42 and the valve body 43, and a shaft portion 44c connected to the cylindrical portion 44a. The compression damping valve 30 and the suction check valve 31 are mounted on the shaft portion 44c of the case 44. With the buffer D configured in this way, since the compression damping valve 30 and the suction check valve 31 are mounted on the shaft portion 44c of the case 44 that houses the valve seat member 42 and the valve body 43 of the variable valve 21, the compression damping valve 30 and the suction check valve 31 can be pre-assembled to the variable valve 21 and housed in the valve housing 10d as a valve assembly, making the assembly of the buffer D very easy and reducing manufacturing costs.

[0109] Furthermore, in the buffer D with a specific structure, the variable valve 21 has a valve seat member 42 with a port 42a, a valve body 43 that moves relative to the valve seat member 42 to open and close the port 42a, and a case 44 having a cylindrical portion 44a that houses the valve seat member 42 and the valve body 43, and a shaft portion 44c connected to the cylindrical portion 44a. The extension-side low-speed valve (low-speed valve) 22, the compression-side low-speed valve (low-speed valve) 23, the compression-side damping valve 30, and the suction check valve 31 are mounted on the shaft portion 44c of the case 44. With the buffer D configured in this way, all the valves installed outside the cylinder 1 are mounted on the shaft portion 44c of the case 44 that houses the valve seat member 42 and the valve body 43 of the variable valve 21. Therefore, all the valves installed outside the cylinder 1 can be pre-assembled and housed in the valve housing 10d as a valve assembly, making the assembly of the buffer D very easy and further reducing manufacturing costs.

[0110] Furthermore, in the buffer D of this embodiment, the solenoid Sol, valve seat member 42, valve body 43, coil spring 45, and case 44 of the variable valve 21 can be temporarily fixed to the valve cap 41 which, together with the valve housing 40, constitutes the valve housing 10d. All valves installed outside the cylinder 1 can be assembled into the case 44 to create a valve assembly. The valve assembly can then be installed in the appropriate position within the valve housing 10d simply by screwing the valve cap 41 of the assembled valve assembly into the valve housing 40. can Therefore, the assembly process is simplified, and since the valve assembly can be fixed inside the valve housing 10d with only one screw connection, loosening is less likely to occur, and the size can be reduced even when equipped with a large number of valves.

[0111] In the specific shock absorber D described above, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are arranged stacked on both the upper and lower sides of the valve disc 50. However, as shown in the first modified example in Figure 5, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 may be composed of a leaf valve 65 and a valve seat member 66 facing the outer circumference of the leaf valve 65.

[0112] Specifically, the valve seat member 66 comprises an annular main body portion 66a that fits onto the outer circumference of the shaft portion 44c above the valve mounting portion 44h in Figure 5, a cylindrical portion 66b that rises downward from the outer circumference of the lower end of the main body portion 66a, and an annular seat portion 66c that protrudes inward from the inner circumference of the cylindrical portion 66b.

[0113] The inner circumference of the main body portion 66a is provided with an annular recess 66a1 that opens from the lower end in Figure 5 and faces the hole 44d provided in the case 44, and a plurality of grooves 66a2 that extend radially outward from the recess 66a1. Therefore, even when the valve seat member 66 is fitted to the base of the shaft portion 44c, the hole 44d is in communication with the cylindrical portion 66b of the valve seat member 66.

[0114] The inner circumference of the cylindrical portion 66b of the valve seat member 66 configured in this way is provided with valve stoppers 67 and 68, and a leaf valve 65 which is installed between the valve stoppers 67 and 68 together with spacers 69 and 70.

[0115] The leaf valve 65 is constructed by stacking multiple annular plates of equal inner diameter, with its inner circumference fixed to the outer circumference of the valve mounting portion 44h, allowing for deflection in both the vertical and horizontal directions on the outer circumference side as shown in Figure 5. The leaf valve 65 is constructed by stacking multiple annular plates with progressively smaller outer diameters above and below an annular plate with the largest outer diameter at the center. The number of stacked annular plates in the leaf valve 65 can be arbitrarily changed according to the desired damping force of the shock absorber D. Furthermore, the central annular plate with the largest outer diameter in the leaf valve 65 is positioned so that its outer circumference faces the inner circumference of the annular seat portion 66c with almost no gap.

[0116] The valve stoppers 67 and 68 are annular in shape and are positioned away from the leaf valve 65 via extremely small diameter spacers 69 and 70 stacked vertically in Figure 5. When the outer circumference of the leaf valve 65 bends significantly and contacts the leaf valve 65, the stoppers restrict further bending of the leaf valve 65, thereby protecting the leaf valve 65.

[0117] The spacers 69 and 70 are each constructed by stacking multiple annular plates, and by adjusting the number of stacked annular plates, they play a role in adjusting the position of the valve stoppers 67 and 68 relative to the leaf valve 65, and in positioning the leaf valve 65 so that the outer circumference of the annular plate with the largest outer diameter of the leaf valve 65 faces directly in the axial direction to the inner circumference of the annular seat portion 66c of the valve seat member 66.

[0118] Furthermore, the leaf valve 65 has its inner circumference fixed to the outer circumference of the valve mounting portion 44h, and its outer circumference can bend vertically. Therefore, when the buffer D extends and the liquid flows through the outer passage P from the extension chamber R1 to the compression chamber R2, the outer circumference bends downward in Figure 5, providing resistance to the liquid flow. When the buffer D contracts and the liquid flows through the outer passage P from the compression chamber R2 to the extension chamber R1, the outer circumference bends upward in Figure 5, providing resistance to the liquid flow. Thus, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are composed of a leaf valve 65 and a valve seat member 66, and the leaf valve 65 and the valve seat member 66 are shared.

[0119] Furthermore, when the variable valve 21 is open and the extension speed of the buffer D is extremely low, there is not much difference between the pressure in the extension chamber R1 and the pressure in the compression chamber R2. As a result, the leaf valve 65 hardly bends at all, or even if it bends downward in Figure 5, it only bends to the extent that its outer circumference faces the inner circumference of the annular seat portion 66c. Therefore, the liquid experiences relatively large resistance when passing between the leaf valve 65 and the annular seat portion 66c. For this reason, the low-speed extension valve 22 can quickly generate damping force when the buffer D extends at an extremely low speed. Also, when the extension speed of the buffer D exceeds the extremely low speed and becomes low, the difference between the pressure in the extension chamber R1 and the pressure in the compression chamber R2 becomes large, and the outer circumference of the leaf valve 65 bends significantly downward in Figure 5. This creates a large annular gap between the outer circumference of the leaf valve 65 and the inner circumference of the annular seat portion 66c, allowing the liquid to pass through. Therefore, when the shock absorber D extends at a low speed exceeding a very low speed, the damping coefficient of the extension valve 22 becomes smaller than at very low speeds, suppressing excessive damping force and generating a damping force suitable for driving on good roads.

[0120] Conversely, when the variable valve 21 is open and the shock absorber D is contracting at an extremely low speed, there is little difference between the pressure in the compression chamber R2 and the pressure in the extension chamber R1. As a result, the leaf valve 65 hardly bends at all, or even if it bends upward in Figure 5, it only bends to the extent that its outer circumference faces the inner circumference of the annular seat portion 66c. Therefore, the liquid experiences relatively large resistance when passing between the leaf valve 65 and the annular seat portion 66c. For this reason, the low-speed compression valve 23 can quickly generate damping force when the shock absorber D is contracting at an extremely low speed. Furthermore, when the contraction speed of the shock absorber D exceeds an extremely low speed and becomes low, the difference between the pressure in the compression chamber R2 and the pressure in the extension chamber R1 becomes large, causing the outer circumference of the leaf valve 65 to bend significantly upward in Figure 5. This creates a large annular gap between the outer circumference of the leaf valve 65 and the inner circumference of the annular seat portion 66c, allowing the liquid to pass through. Therefore, when the shock absorber D contracts at a speed exceeding a very low speed, the damping coefficient of the compression-side low-speed valve 23 becomes smaller than at very low speeds, suppressing excessive damping force and generating a damping force suitable for driving on good roads.

[0121] In the shock absorber D configured in this way, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 share the leaf valve 65 and valve seat member 66, eliminating the need for each to have its own leaf valve. This further shortens the axial length and the overall length of the valve housing 10d, allowing for a more compact shock absorber D. Furthermore, even in the shock absorber D, which has the extension-side low-speed valve 22 and the compression-side low-speed valve 23 sharing the leaf valve 65 and valve seat member 66, all valves installed outside the cylinder 1 are mounted on the shaft portion 44c of the case 44 that houses the valve seat member 42 and valve body 43 of the variable valve 21. Therefore, all valves installed outside the cylinder 1 can be pre-assembled and housed in the valve housing 10d as a valve assembly, making the assembly of the shock absorber D very easy and further reducing manufacturing costs.

[0122] Furthermore, in the specific shock absorber D described above, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 were provided on the outer circumference of the shaft portion 44c of the case 44 of the variable valve 21. However, as shown in the second modified example in Figure 6, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 may be housed within the cylindrical portion 44a of the case 44 and provided on the outer circumference of the valve seat member 42.

[0123] In this second modified example, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are stacked above and below a valve disc 71, which has annular extension-side low-speed ports 71a and compression-side low-speed ports 71b on the outer circumference of a valve seat member 42 that penetrate in the axial direction.

[0124] More specifically, the valve seat member 42 is cylindrical and has a port 42a, as well as a threaded portion 42b formed on the outer circumference of its upper end and a stepped portion 42c provided on the outer circumference. Since the extension-side low-speed valve 22, the compression-side low-speed valve 23, and the valve disc 71 are mounted on the outer circumference of the valve seat member 42 above the stepped portion 42c, the port 42a is open below the stepped portion 42c in Figure 6 so as not to be blocked by the extension-side low-speed valve 22, the compression-side low-speed valve 23, and the valve disc 71.

[0125] The valve disc 71 is annular in shape and includes an extension-side low-speed port 71a and a compression-side low-speed port 71b that penetrate from the upper end to the lower end along the axial direction, and a seal ring 71c mounted on its outer circumference. The valve disc 71 is mounted on the outer circumference of the valve seat member 42, above the stepped portion 42c in Figure 6, and its outer circumference is fitted to the inner circumference of the cylindrical portion 44a of the case 44. When the valve disc 71 is mounted on the outer circumference of the valve seat member 42 and housed in the cylindrical portion 44a, it divides the inside of the cylindrical portion 44a into an upper space that communicates with the extension-side chamber R1 via a notch 44e, a passage 40d, and an annular passage C, and a lower space that communicates with the compression-side chamber R2 via a hole 44d that opens to the variable valve 21 and the shaft portion 44c, and a passage 40e. When the valve disc 71 is housed in the cylindrical portion 44a together with the valve seat member 42, the seal ring 71c is brought into close contact with the cylindrical portion 44a, and the upper space and the lower space partitioned within the cylindrical portion 44a are connected only through the extension-side low-speed port 71a and the compression-side low-speed port 71b.

[0126] The extension-side low-speed valve 22 is a laminated leaf valve formed by stacking multiple annular plates. Its inner circumference is fixed to the outer circumference of the valve seat member 42 and is stacked below the valve disc 71 in Figure 6, allowing for flexure of the outer circumference, and opening and closing the lower end of the extension-side low-speed port 71a in Figure 6. Therefore, when the buffer D extends, the extension-side low-speed valve 22 flexes its outer circumference to open the extension-side low-speed port 71a and provide resistance to the flow of liquid passing through the extension-side low-speed port 71a from the extension-side chamber R1 to the compression-side chamber R2. Furthermore, when the buffer D contracts, the extension-side low-speed valve 22 closes the extension-side low-speed port 71a to block the flow of liquid attempting to pass through it from the compression-side chamber R2 to the extension-side chamber R1, thereby preventing the flow of liquid.

[0127] On the other hand, the compression-side low-speed valve 23 is a laminated leaf valve formed by stacking multiple annular plates, with its inner circumference fixed to the outer circumference of the valve seat member 42 and stacked above the valve disc 71 in Figure 6, allowing for deflection of the outer circumference, and opening and closing the upper end of the compression-side low-speed port 71b in Figure 6. Therefore, when the buffer D is contracting, the compression-side low-speed valve 23 deflects its outer circumference to open the compression-side low-speed port 71b and provide resistance to the flow of liquid passing through the compression-side low-speed port 71b from the compression-side chamber R2 to the extension-side chamber R1. Furthermore, when the buffer D is extending, the compression-side low-speed valve 23 closes the valve to block the flow of liquid attempting to pass through the compression-side low-speed port 71b from the extension-side chamber R1 to the compression-side chamber R2, thereby preventing the flow of liquid.

[0128] The extension-side low-speed valve 22, valve disc 71, and compression-side low-speed valve 23, configured in this manner, are assembled in order around the outer circumference of the valve seat member 42, and then fixed to the valve seat member 42 by being sandwiched between an annular nut member 72 screwed to the threaded portion 42b and a stepped portion 42c. In this embodiment, a collar 73 with an L-shaped cross-section that can be fitted into the annular recess 36a of the second fixed core 36 of the solenoid Sol and covers the outer circumference of the nut member 72 is provided at the upper end of the valve seat member 42 in Figure 6, enabling the valve seat member 42 to be centered by the second fixed core 36.

[0129] Furthermore, the cylindrical portion 44a of the case 44 is widened at the top to accommodate the extension-side low-speed valve 22 and the compression-side low-speed valve 23 inside the cylindrical portion 44a. Also, since it is sufficient to mount only the compression-side damping valve 30 and the suction check valve 31 on the outer circumference of the valve mounting portion 44h of the shaft portion 44c, the axial length of the valve mounting portion 44h is shortened accordingly.

[0130] In the buffer D configured in this way, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are arranged on the outer circumference of the valve seat member 42 of the variable valve 21 and housed within the case 44. As a result, the axial length of the shaft portion 44c is shortened, and the overall length of the valve housing 10d is also shortened, allowing the buffer D to be made even more compact. Furthermore, even in the buffer D, which has the extension-side low-speed valve 22 and the compression-side low-speed valve 23 on the outer circumference of the valve seat member 42, the valves that are installed outside the cylinder 1 are mounted in the case 44 of the variable valve 21. Therefore, all the valves that are installed outside the cylinder 1 can be pre-assembled and housed in the valve housing 10d as a valve assembly, making the assembly of the buffer D very easy and further reducing manufacturing costs.

[0131] Furthermore, in the second modified example, shock absorber D, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are arranged on the outer circumference of the valve seat member 42 of the variable valve 21. Therefore, when the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are made of leaf valves, the outer diameter of the leaf valves becomes larger, which reduces the bending rigidity. This reduces the change in the characteristics of each individual extension-side low-speed valve 22 and compression-side low-speed valve 23 in the stacked leaf valves, making it easier to tune the characteristics of the extension-side low-speed valve 22 and the compression-side low-speed valve 23.

[0132] Furthermore, while the specific shock absorber D described above is equipped with an extension-side low-speed valve 22 and a compression-side low-speed valve 23, as shown in the third modified example in Figure 7, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 may be eliminated, and the variable valve 21, the compression-side damping valve 30, and the suction check valve 31 may be housed in the valve housing 10d. In this case, only the valve disc 60, the suction check valve 31, and the compression-side damping valve 30 should be assembled to the shaft portion 44c of the case 44 of the variable valve 21 and housed in the valve housing portion 40. Even with a shock absorber D configured in this way, the flow rate passing through the main damping passage M can be adjusted according to the degree of opening of the variable valve 21, so that the damping force can be adjusted to a high or low level while ensuring a wide range of damping force adjustment. Moreover, since the discharge passage EP is equipped with a compression-side damping valve 30, the pressure in the compression-side chamber R2 can be increased to above the tank pressure during contraction operation, generating a higher damping force than conventional methods. Furthermore, with the shock absorber D configured in this way, the extension-side low-speed valve 22 and the compression-side low-speed valve 23 are eliminated, which shortens the overall length of the valve housing 10d, making the shock absorber D even more compact. Also, since the valves that are installed outside the cylinder 1 are mounted in the case 44 of the variable valve 21, all the valves that are installed outside the cylinder 1 can be pre-assembled and housed in the valve housing 10d as a valve assembly, making the assembly of the shock absorber D very easy and further reducing manufacturing costs.

[0133] Furthermore, as shown in the fourth modified example in Figure 8, the valve housing 10d and the tank 18 may be individually installed offset circumferentially to the side of the cap 10, with only the variable valve 21 housed in the valve housing 10d, and a tank holding portion 10e for holding the tank 18 provided to the side of the cylindrical portion 10a of the cap 10, with a passage 10e1 connecting the tank 18 and the pressure side chamber R2 provided in the tank holding portion 10e, and a pressure side damping valve 30 and a suction check valve 31 provided within the tank holding portion 10e, in the middle of the passage 10e1. In the installation of the pressure-side damping valve 30 and the suction check valve 31 in the tank holding section 10e, the pressure-side damping valve 30, which is a stacked leaf valve that opens and closes a port 80a that forms part of the discharge passage EP provided in the valve disc 80, is positioned above the valve disc 80 in Figure 8, and the suction check valve 31, which is composed of a leaf valve that opens and closes a port 80b that forms part of the suction passage SP provided in the valve disc 80, and a spring that biases the leaf valve in the closing direction, is positioned below the valve disc 80 in Figure 8. However, the structure shown in Figure 4 may also be adopted. Furthermore, in the fourth modified example, only the variable valve 21 is provided, but the variable valve 21, the extension-side low-speed valve 22, and the compression-side low-speed valve 23 may also be provided in the valve housing 10d.

[0134] In this fourth specific modification of the buffer D, the compression damping valve 30 and the suction check valve 31 are located in the tank holding section 10e that holds the tank 18, rather than in the valve housing 10d that houses the variable valve 21, so the valve housing 10d can be made smaller.

[0135] 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]

[0136] 1...Cylinder, 2...Piston rod, 3...Piston, 4...Outer tube, 10d...Valve housing, 18...Tank, 21...Variable valve, 22...Rebound low-speed valve (low-speed valve), 23...Compression low-speed valve (low-speed valve), 30...Compression damping valve, 31...Suction check valve, 42...Valve seat member, 42a...Port, 43...Valve body, 44...Case, 44a...Cylinder section, 44c...Shaft section, C...Annular passage, D...Buffer, EP...Discharge passage, P...External passage, M...Main damping passage, R1...Rebound chamber, R2...Compression chamber, SP...Discharge passage

Claims

1. Cylinder and A piston rod is inserted into the cylinder so as to be movable in the axial direction, A piston connected to the piston rod and inserted into the cylinder so as to be movable in the axial direction, and which divides the inside of the cylinder into an extension chamber and a compression chamber, An outer tube that covers the outer circumference of the cylinder and forms an annular passage between itself and the cylinder that communicates with the extension chamber, A tank for storing liquid, A main damping passage that provides resistance to the flow of liquid moving back and forth between the extension chamber and the compression chamber, An external passage is provided outside the cylinder, with one end communicating with the extension chamber via the annular passage and the other end communicating with the compression chamber, A discharge passage connecting the pressure chamber and the tank, A suction passage connecting the tank and the pressure side chamber, A variable valve provided in the external passage, which can change the flow rate distribution ratio between the main damping passage and the external passage by adjusting the degree of valve opening or the valve opening pressure, A pressure-side damping valve is provided in the discharge passage to provide resistance to the flow of liquid from the pressure-side chamber to the tank, The suction passage is provided with a suction check valve that allows only the flow of liquid from the tank to the pressure chamber. A buffer characterized by the following features.

2. The external passage is provided with a low-speed valve in series with the variable valve, which provides resistance to the flow of liquid moving between the extension chamber and the compression chamber. The shock absorber according to feature 1.

3. The valve housing comprises the variable valve, the pressure-side damping valve, and the suction check valve, The variable valve, the compression damping valve, and the suction check valve are coaxially inserted into the valve housing. The shock absorber according to claim 1 or 2.

4. The variable valve comprises a valve seat member having a port, a valve body that moves relative to the valve seat member to open and close the port, and a case having a cylindrical portion that houses the valve seat member and the valve body, and a shaft portion connected to the cylindrical portion. The compression damping valve and the suction check valve are mounted on the shaft portion of the case. The shock absorber according to feature 3.

5. The external passage is provided with a low-speed valve that is installed in series with the variable valve and provides resistance to the flow of liquid moving between the extension chamber and the compression chamber. The low-speed valve is mounted on the shaft portion of the valve seat member. The shock absorber according to feature 4.

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