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 technology]

[0002] A shock absorber is used, for example, by being interposed between the body and wheels of a saddle-type vehicle, and suppresses vibration between the body and wheels by the damping force generated when the shock absorber expands or contracts.

[0003] Such a shock absorber includes, for example, a cylinder, a piston movably inserted into the cylinder to divide the inside of the cylinder into an extension-side chamber and a compression-side 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 to communicate between the extension-side chamber and the compression-side chamber and to provide resistance to the flow of hydraulic oil passing through, a bypass path that bypasses the hard-side damping element to communicate between the extension-side chamber and the compression-side chamber, and a soft-side damping element provided in the bypass path in series with a solenoid valve (for example, see Patent Document 1).

[0004] In a shock absorber configured in this manner, the opening area of ​​the bypass passage can be adjusted with an electromagnetic valve to adjust the distribution ratio of the flow rate of hydraulic oil passing through the hard damping element and the soft damping element, thereby providing a wide damping force adjustment range and outputting a damping force optimal for suppressing vehicle vibrations. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-143685 A Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional shock absorbers allow for a wide range of damping force adjustment, but because they have a structure in which the compression chamber is directly connected to the tank, the pressure in the compression chamber cannot be increased above the tank pressure during contraction, and the damping force during contraction hits a plateau, making it difficult to meet the demand for high damping force during contraction.

[0007] Therefore, an object of the present invention is to provide a shock absorber that is capable of exerting a high damping force during contraction while ensuring a damping force adjustment range. [Means for solving the problem]

[0008] In order to solve the above problems, the shock absorber of the present invention includes a cylinder, a piston rod inserted into the cylinder so as to be axially movable, a piston connected to the piston rod and inserted into the cylinder so as to be axially movably, and dividing the inside of the cylinder into an extension-side chamber and a compression-side chamber, an outer tube covering the outer periphery of the cylinder and forming an annular passage between the cylinder and the outer periphery and communicating with the extension-side chamber, a tank for storing liquid, a main damping passage providing resistance to the flow of liquid moving between the extension-side chamber and the compression-side chamber, an external passage provided outside the cylinder, one end of which is connected to the extension-side chamber via the annular passage and the other end of which is connected to the compression-side chamber, a discharge passage connecting the compression-side chamber and the tank, a suction passage connecting the tank and the compression-side chamber, a variable valve provided in the external passage and capable of changing the distribution ratio of the flow rate of the main damping passage and the external passage, a compression-side damping valve provided in the discharge passage and providing resistance to the flow of liquid from the compression-side chamber to the tank, and a suction check valve provided in the suction passage and allowing only the flow of liquid from the tank to the compression-side chamber.

[0009] According to a shock absorber configured in this manner, a variable valve is provided in the external passage that bypasses the main damping passage that communicates between the expansion side chamber and the compression side chamber, and 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 adjust the damping force while ensuring a damping force adjustment range.In addition, since a compression side damping valve is provided in the discharge passage, the pressure in the compression side chamber can be increased to above the tank pressure during contraction operation, thereby generating a higher damping force than before.

[0010] The shock absorber may further include a low-speed valve that is provided in series with the variable valve in the external passage and provides resistance to the flow of liquid moving between the expansion-side chamber and the compression-side chamber. With this type of shock absorber, the variable valve is opened to activate the low-speed valve in the external passage, thereby adjusting the damping force in the low expansion / contraction speed range, and a damping force suitable for driving on good roads with few bumps and no vibrations at high speeds can be generated.

[0011] Furthermore, the shock absorber may include a valve housing that accommodates the variable valve, the compression side damping valve, and the suction check valve, and the variable valve, the compression side damping valve, and the suction check valve may be coaxially inserted into the valve housing. With this type of shock absorber, the valve housing can be made cylindrical, and the assembly work of accommodating the variable valve, the compression side damping valve, and the suction check valve in the valve housing is also facilitated, thereby reducing manufacturing costs.

[0012] The variable valve in the shock absorber may have a valve seat member with a port, a valve body that moves relatively 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 an axial portion connected to the cylindrical portion, and the compression side damping valve and the suction check valve may be attached to the axial portion of the case. According to the shock absorber configured in this manner, the compression side damping valve and the suction check valve are attached to the axial portion of the case that houses the valve seat member and the valve body of the variable valve, so that the compression side damping valve and the suction check valve can be assembled in advance to the variable valve and housed in the valve housing as a valve assembly, making it very easy to assemble the shock absorber and reducing manufacturing costs.

[0013] Furthermore, the low-speed valve in the shock absorber may be attached to the shaft portion of the valve seat member. With this shock absorber configured in this manner, all the valves installed outside the cylinder are attached to the shaft portion of the case that houses the valve seat member and the valve body of the variable valve, and therefore all the valves installed outside the cylinder can be assembled in advance and housed in the valve housing as a valve assembly, making it extremely easy to assemble the shock absorber and further reducing manufacturing costs. Effect of the Invention

[0014] According to the shock absorber of the present invention, a high damping force can be exerted during the contraction operation while ensuring a damping force adjustment range. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view of a shock absorber according to one embodiment. [Diagram 2] FIG. 2 is a diagram showing the damping force characteristics of the shock absorber in one embodiment. [Diagram 3] FIG. 3 is a partially enlarged cross-sectional view of a shock absorber having a specific structure. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the low speed valve, the compression damping valve and the suction check valve with specific structures. [Diagram 5] FIG. 5 is a partially enlarged cross-sectional view of a first modified example of a shock absorber having a specific structure. [Figure 6] FIG. 6 is a partially enlarged cross-sectional view of a second modified example of a shock absorber having a specific structure. [Figure 7] FIG. 7 is a partially enlarged cross-sectional view of a third modified example of a shock absorber having a specific structure. [Figure 8] FIG. 8 is a partially enlarged cross-sectional view of a shock absorber having a specific structure according to a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the present invention will be described based on the embodiment shown in the drawings. As shown in Fig. 1, a shock absorber D in one embodiment includes 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 expansion-side chamber R1 and a compression-side chamber R2, an outer tube 4 covering the outer periphery of the cylinder 1 and forming an annular passage C between the cylinder 1 and the outer tube 4 and communicating with the expansion-side chamber R1, a tank 18 for storing liquid, a main damping passage M providing resistance to the flow of liquid moving between the expansion-side chamber R1 and the compression-side chamber R2, and a shock absorber 5 provided outside the cylinder 1 and having one end. The external passage P is connected at one end to the expansion-side chamber R1 via an annular passage C and at the other end to the compression-side chamber R2, a discharge passage EP connecting the compression-side chamber R2 with the tank 18, a suction passage SP connecting the tank 18 with the compression-side chamber R2, a variable valve 21 provided in the external passage P and capable of changing the distribution ratio of the flow rate between the main damping passage M and the external passage P, a compression-side damping valve 30 provided in the discharge passage EP and providing resistance to the flow of liquid from the compression-side chamber R2 to the tank 18, and a suction check valve 31 provided in the suction passage SP and allowing only the flow of liquid from the tank 18 to the compression-side chamber R2.

[0017] Although not shown, this shock absorber D is used by being interposed between the body and the rear wheel of a saddle-type vehicle such as a motorcycle, and suppresses vibration of the body and the rear wheel. Note that the shock absorber D may be used to suppress vibration of vehicles other than saddle-type vehicles.

[0018] Each part of the shock absorber D will be described in detail below. As shown in Fig. 1, the cylinder 1 is cylindrical, with its upper end in Fig. 1 closed by a rod guide 17 and its lower end in Fig. 1 closed by a cap 10. The cylinder 1 also has a through hole 1a that communicates between the inside and outside of the cylinder 1 on the side 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 is in close contact with the inner periphery of the cap 10 is attached to the outer periphery of the flange 1b, sealing the gap between the cylinder 1 and the cap 10.

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

[0020] The piston rod 2 has a small diameter portion 2a at its lower end in Fig. 1, the outer diameter of which is smaller than that of its upper portion, and the piston 3 is attached to its outer periphery. A bracket 6 that can be connected to the body of a saddle-type vehicle is attached to the upper end of the piston rod 2 in Fig. 1.

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

[0022] Next, the piston 3 is annular and is attached to the outer periphery of the small diameter portion 2a of the piston rod 2, and has an expansion side port 3a and a compression side port 3b that communicate the expansion side chamber R1 and the compression side chamber R2 in parallel, respectively. An expansion side main damping valve 13 that is annular and is attached to the outer periphery of the small diameter portion 2a and opens and closes the expansion side port 3a is stacked at the lower end of the piston 3 in FIG. 1. Also, a compression side main damping valve 14 that is annular and is attached to the outer periphery of the small diameter portion 2a and opens and closes the compression side port 3b is stacked at the upper end of the piston 3 in FIG. 1. The piston 3, the expansion side main damping valve 13, and the compression side main damping valve 14 are fitted to 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 that is screwed to the lower end of the small diameter portion 2a.

[0023] In the shock absorber D of this embodiment, the expansion-side main damping valve 13 is a laminated leaf valve that is configured by stacking a plurality of annular plates at the lower end of the piston 3 in FIG. 1, and is fixed at the inner circumferential side and opens the expansion-side port 3a when the outer circumferential side is deflected by the pressure of the expansion-side chamber R1. The expansion-side main damping valve 13 can open and close the expansion-side port 3a, and opens the valve when the shock absorber D expands to provide resistance to the flow of liquid passing through the expansion-side port 3a from the expansion-side chamber R1 to the compression-side chamber R2, and closes the valve when the shock absorber D contracts to block the expansion-side port 3a. Note that the expansion-side main damping valve 13 may be a damping valve other than a laminated leaf valve as long as it is a damping valve that provides resistance to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2 and exerts a damping force that hinders the expansion of the shock absorber D when the shock absorber D expands.

[0024] On the other hand, in the shock absorber D of this embodiment, the compression side main damping valve 14 is a laminated leaf valve that is configured by laminating a plurality of annular plates on the upper end of the piston 3 in FIG. 1, and is fixed on the inner circumferential side, and opens the compression side port 3b when the outer circumferential side is deflected by the pressure of the compression side chamber R2. The compression side main damping valve 14 can open and close the compression side port 3b, and opens the valve when the shock absorber 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 expansion side chamber R1, and closes the valve when the shock absorber D expands to block the compression side port 3b. Note that the compression side main damping valve 14 may be a damping valve other than a laminated leaf valve as long as it can provide resistance to the flow of liquid from the compression side chamber R2 to the expansion side chamber R1 and exert a damping force that prevents the shock absorber D from contracting when the shock absorber D contracts. Although not shown, an orifice is provided in parallel with the expansion side main damping valve 13 and the compression side main damping valve 14. The orifice is formed, for example, by a notch provided in an annular plate constituting the expansion side main damping valve 13 and the compression side main damping valve 14, or by a stamping provided on the valve seat of the piston 3 on which the annular plate sits and leaves.

[0025] In this manner, the expansion side port 3a and the compression side port 3b of the piston 3 communicate with the expansion side chamber R1 and the compression side chamber R2. When the expansion side main damping valve 13 and the compression side main damping valve 14 are closed, the orifice provides resistance to the flow of liquid passing through the expansion side port 3a and the compression side port 3b to move between the expansion side chamber R1 and the compression side chamber R2. When the expansion side main damping valve 13 and the compression side main damping valve 14 are open, the expansion side main damping valve 13 provides resistance to the flow of liquid passing through the expansion side port 3a, and the compression side main damping valve 14 provides resistance to the flow of liquid passing through the compression side port 3b. In this embodiment, the expansion side port 3a, the compression side port 3b, the orifice, the expansion side main damping valve 13, and the compression side main damping valve 14 constitute a main damping passage M that provides resistance to the flow of liquid moving between the expansion side chamber R1 and the compression side chamber R2. The main damping passage M may be configured to include only a single passage and a bidirectional valve, such as an orifice or a choke, that is provided in the passage and provides resistance to the flow of liquid reciprocating between the expansion-side chamber R1 and the compression-side chamber R2.

[0026] As shown in Fig. 1, the outer tube 4 is cylindrical and covers the outer periphery of the cylinder 1, forming an annular passage C by the annular gap between the outer tube 4 and the cylinder 1. The outer tube 4 has a hole 4a that is provided slightly above the lower end and communicates between the inside and outside, and a threaded portion 4b that is provided on the outer periphery at a position above and spaced apart from the hole 4a. The lower end of the outer tube 4 in Fig. 1 is closed by a cap 10 that is screwed together using the threaded portion 4b on the outer periphery.

[0027] A rod guide 17 is fixed to the inner circumference of the upper end of the outer tube 4 in FIG. 1, and the upper end of the outer tube 4 is closed by the rod guide 17. The rod guide 17 is annular, and has a fitting portion 17a at its lower end into which the upper end of the cylinder 1 fits, and has an annular seal member 17b and an annular bush 17c at its inner circumference, which come into sliding contact with the outer periphery of the piston rod 2. The rod guide 17 is fixed to the outer tube 4 to position the cylinder 1 concentrically with the outer tube 4 in the radial direction, and closes the upper end of the annular passage C between the cylinder 1 and the outer tube 4 in FIG. 1. The rod guide 17 seals the outer periphery of the piston rod 2 with the seal member 17b to hermetically seal the inside of the cylinder 1, and guides the movement of the piston rod 2 in the axial direction with the bush 17c.

[0028] The cap 10 is cylindrical and has 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 screwed to the outer periphery of the outer tube 4.

[0029] More specifically, as shown in FIG. 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 FIG. 1 and the lower end of the outer tube 4 in FIG. 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, and then the lower end of the outer tube 4 covering the outer circumference of the cylinder 1 is inserted into the cylindrical portion 10a, and the threaded portion 4b is screwed to the threaded portion 10a1. Then, 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 portion 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 of 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 communicates with the annular groove 10a3 via the hole 4a provided in the outer tube 4, and also communicates with the expansion-side chamber R1 via the through hole 1a provided in the cylinder 1.

[0031] In addition, the outer periphery of the lower end of the outer tube 4 between the hole 4a and the screw portion 4b faces the sealing groove 10a2 of the tubular portion 10a of the cap 10, so that the annular seal ring 20 housed in the sealing groove 10a2 adheres closely to the outer periphery of the outer tube 4, thereby sealing the gap between the cap 10 and the outer tube 4.

[0032] Furthermore, the seal ring 11 attached to the outer periphery of the flange 1b of the cylinder 1 is in close contact with the inner periphery of the tubular portion 10a of the cap 10, closer to the bottom than the annular groove 10a3, so that the gap between the cylinder 1 and the cap 10 is also sealed, preventing the annular passage C from communicating with the compression side chamber R2 in the cylinder 1 through the gap between the cylinder 1 and the cap 10.

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

[0034] In this embodiment, as shown in FIG. 1, the cap 10 includes a valve housing 10d arranged parallel to the tubular portion 10a and connected to the lateral side of the tubular portion 10a, and also includes a tank 18 arranged parallel to the lateral side of the valve housing 10d. The tank 18 is cylindrical and contains a bladder 19 therein. 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 so that the pressure in the air chamber G is at least equal to or higher than atmospheric pressure when the shock absorber D is fully extended. The liquid chamber L and the air chamber G in the tank 18 may be divided by using an elastic partition such as the bladder 19 or a diaphragm, or by using a free piston.

[0035] Provided inside the valve housing 10d are 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, an exhaust 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 as low speed valves provided in the external passage P, a compression side damping valve 30 provided in the exhaust passage EP, and a suction check valve 31 provided in the suction passage SP.

[0036] One end of the external passage P is connected to the expansion-side chamber R1 in the cylinder 1 via the annular groove 10a3, the hole 4a, the annular passage C, and the through hole 1a, and the other end opens to the recess 10b1 of the cap 10 and is connected to the compression-side chamber R2 in the cylinder 1. In this way, the external passage P and the annular passage C form a bypass path that is provided outside the cylinder 1 and communicates between the expansion-side chamber R1 and the compression-side chamber R2 by bypassing the main damping passage M provided in the piston 3. Note that the external passage P only needs to communicate between the expansion-side chamber R1 and the compression-side chamber R2 outside the cylinder via the annular passage C, so the design of the configuration can be changed as desired to that extent.

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

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

[0039] The low speed extension side valve 22 is a damping valve that opens to provide resistance to the flow of liquid from the extension side chamber R1 to the compression side chamber R2, and closes to block the passage of liquid from the compression side chamber R2 to the extension side chamber R1. The opening pressure of the low speed extension side valve 22 is lower than that of the main extension side damping valve 13, and when the extension speed of the shock absorber D is low, the valve opens prior to the main extension side damping valve 13 to generate a damping force.

[0040] The compression side low speed valve 23 is a damping valve that opens to provide resistance to the flow of liquid from the compression side chamber R2 to the expansion side chamber R1, and closes to block the passage of liquid from the expansion side chamber R1 to the compression side chamber R2. The valve opening pressure is lower than that of the compression side main damping valve 14, and when the contraction speed of the shock absorber D is low, the valve opens prior to the compression side main damping valve 14 to generate a damping force.

[0041] In this embodiment, the external passage P is provided with the extension-side low speed valve 22, 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 therethrough, and the compression-side low speed valve 23, 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 therethrough. These extension-side low speed valve 22 and the compression-side low speed valve 23 are defined as low speed valves. However, 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 therethrough may be defined as the low speed valve.

[0042] The exhaust passage EP and the suction passage SP branch off from the external passage P on the compression side chamber side relative to the variable valve 21, the low extension speed valve 22, and the low compression side speed valve 23, and are each connected to the fluid chamber L of the tank 18.

[0043] The compression side damping valve 30 is provided in the discharge passage EP and serves as a damping valve that opens to provide resistance to the flow of liquid from the compression side chamber R2 toward the tank 18 and closes to block the discharge passage EP to provide resistance to the flow of liquid from the tank 18 toward the compression side chamber R2. The suction check valve 31 is provided in the suction passage SP and serves as a damping valve that opens to allow the passage of liquid from the tank 18 toward the compression side chamber R2 with almost no resistance to the flow of liquid, but closes to block the suction passage SP to provide resistance to the flow of liquid from the compression side chamber R2 toward 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 described below. When the shock absorber D is expanded, the piston rod 2 retreats from the cylinder 1 and the piston 3 compresses the expansion-side chamber R1. Then, the liquid in the expansion-side chamber R1 moves to the compression-side chamber R2 through an orifice (not shown) in the main damping passage M, the expansion-side main damping valve 13 in the main damping passage M, or the expansion-side low speed valve 22 in the external passage P, and the suction check valve 31 opens, and the liquid equivalent to the volume of the piston rod 2 retreated from the cylinder 1 is supplied from the tank 18 to the cylinder 1 through the suction passage SP. Resistance is applied to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2 by the main damping passage M or the expansion-side low speed valve 22, and an expansion-side damping force due to the resistance is generated. With regard to the resistance given when the liquid passes through the main damping passage M, when the extension speed of the shock absorber D is in the low-speed range, the extension side main damping valve 13 does not open and an orifice (not shown) applies resistance to the flow of the liquid, and when the extension speed of the shock absorber D is in the high-speed range, the extension side main damping valve 13 opens and resistance is applied to the flow of the liquid by the extension side main damping valve 13. When the amount of electricity supplied to the variable valve 21 is changed, the distribution ratio of the liquid passing through the main damping passage M and the low speed extension side valve 22 during the extension operation of the shock absorber D changes.

[0045] Specifically, during the extension operation of the shock absorber D, when the variable valve 21 is open, the liquid passes through the main damping passage M and the low speed extension valve 22, but when the variable valve 21 is closed, the external passage P is blocked and the liquid cannot pass through the low speed extension valve 22, but passes only through the main damping passage M and moves from the extension side chamber R1 to the compression side chamber R2. In addition, when a 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, so that the proportion of liquid passing through the low speed extension valve 22 increases and 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 within a range from soft characteristics generated mainly by the low-speed extension valve 22 shown by the dashed line in Fig. 2 to hard characteristics generated mainly by the main damping passage M shown by the solid line in Fig. 2 by adjusting the amount of current supplied to the variable valve 21, as shown in Fig. 2. Also, when the extension speed is in the high-speed range during extension operation, the extension-side main damping valve 13 opens widely regardless of the opening degree of the variable valve 21, and the liquid preferentially passes through the main damping passage M, so that the shock absorber D generates a damping force by the extension-side main damping valve 13.

[0046] On the other hand, when the shock absorber D is contracted, the piston rod 2 enters the cylinder 1 and the piston 3 compresses the compression side chamber R2. Then, the liquid in the compression side chamber R2 moves to the expansion side chamber R1 through the orifice (not shown) in the main damping passage M, the compression side main damping valve 14 in the main damping passage M or the compression side low speed valve 23 in the external passage P, and the liquid in the compression side chamber R2 passes through the compression side damping valve 30 and is discharged from the compression side chamber R2 to the tank 18 because the liquid in the volume of the piston rod 2 that entered the cylinder 1 becomes excessive in the cylinder 1. Resistance is applied to the flow of liquid from the compression side chamber R2 to the expansion side chamber R1 by the main damping passage M or the compression side low speed valve 23, and resistance is applied to the flow of liquid from the compression side chamber R2 to the tank 18 by the compression side damping valve 30, and a compression side damping force due to each of the resistances described above is generated. With regard to the resistance given when the liquid passes through the main damping passage M, when the contraction speed of the shock absorber D is in the low-speed range, the compression side main damping valve 14 does not open and an orifice (not shown) applies resistance to the flow of the liquid, and when the contraction speed of the shock absorber D is in the high-speed range, the compression side main damping valve 14 opens and resistance is applied to the flow of the liquid by the compression side main damping valve 14. Then, by changing the amount of electricity supplied to the variable valve 21, 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 changes.

[0047] Specifically, during the contraction operation of the shock absorber 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, but when the variable valve 21 is closed, the external passage P is blocked and the liquid cannot pass through the compression side low speed valve 23, and passes only through the main damping passage M to move from the compression side chamber R2 to the expansion side chamber R1. Furthermore, when a current is supplied to the variable valve 21 to open it and the amount of current supplied is increased, the degree to which the variable valve 21 is opened increases and the flow rate of liquid passing through the external passage P increases, so that the proportion of liquid passing through the compression side low speed valve 23 increases and 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, when the contraction speed is in the low-speed range during contraction, the damping force characteristics generated by the shock absorber D are changed within a range from a soft characteristic in which resistance is applied to the liquid flowing from the compression side chamber R2 to the expansion side chamber R1 by the compression side low speed valve 23 shown by the dashed line in Fig. 2 to a hard characteristic in which resistance is applied by the main damping passage M shown by the solid line in Fig. 2 by adjusting the amount of current supplied to the variable valve 21, as shown in Fig. 2. Also, when the contraction speed is in the high-speed range during contraction, the compression side main damping valve 14 opens widely regardless of the opening degree of the variable valve 21, and the liquid flowing from the compression side chamber R2 to the expansion side chamber R1 passes preferentially through the compression side main damping valve 14, so that the shock absorber D generates a damping force by the compression side main damping valve 14. Furthermore, when the shock absorber D is contracting, excess liquid in the cylinder 1 passes through the compression side damping valve 30 and flows from the compression side chamber R2 to the tank 18. Therefore, the pressure in the compression side chamber R2 can be increased to a pressure higher than the tank pressure by the compression side damping valve 30, and the shock absorber D can generate a higher compression side damping force than conventional shock absorbers.

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

[0049] As described above, the shock absorber D of this embodiment includes the cylinder 1, the piston rod 2 inserted into the cylinder 1 so as to be axially movable, the piston 3 connected to the piston rod 2 and inserted into the cylinder 1 so as to be axially movable and dividing the inside of the cylinder 1 into an expansion-side chamber R1 and a compression-side chamber R2, the outer tube 4 covering the outer periphery of the cylinder 1 and forming an annular passage C between the cylinder 1 and the outer periphery of the cylinder 1 and communicating with the expansion-side chamber R1, the tank 18 for storing liquid, the main damping passage M providing resistance to the flow of liquid moving between the expansion-side chamber R1 and the compression-side chamber R2, and a shock absorber 5 provided outside the cylinder 1 and having one end the external passage P is connected at one end to the expansion-side chamber R1 via an annular passage C and at the other end to the compression-side chamber R2, a discharge passage EP connecting the compression-side chamber R2 with the tank 18, a suction passage SP connecting the tank 18 with the compression-side chamber R2, a variable valve 21 provided in the external passage P and capable of changing the distribution ratio of the flow rate between the main damping passage M and the external passage P, a compression-side damping valve 30 provided in the discharge passage EP and providing resistance to the flow of liquid from the compression-side chamber R2 to the tank 18, and a suction check valve 31 provided in the suction passage SP and allowing only the flow of liquid from the tank 18 to the compression-side chamber R2.

[0050] In the shock absorber D configured in this manner, the variable valve 21 is provided in the external passage P that bypasses the main damping passage M that communicates the expansion side chamber R1 and the compression side chamber R2, and the variable valve 21 is opened and closed to adjust the flow rate distribution ratio between the main damping passage M and the external passage P, thereby adjusting the damping force while securing the damping force adjustment range. In addition, since the discharge passage EP is provided with the compression side damping valve 30, the pressure in the compression side chamber R2 can be increased to above the tank pressure during contraction, thereby generating a higher damping force than in the past. As described above, the shock absorber D of this embodiment can generate a high damping force during contraction while securing the damping force adjustment range.

[0051] Moreover, the shock absorber D of this embodiment is provided with an extension-side low-speed valve (low-speed valve) 22 and a compression-side low-speed valve (low-speed valve) 23 that 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 manner, 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, thereby making it possible to adjust the damping force in the low-speed range of the extension / contraction speed and to generate a damping force suitable for driving a saddle-type vehicle on a good road with few bumps and no vibrations at high speeds.

[0052] Furthermore, in the shock absorber D of this embodiment, an external passage P is provided outside the cylinder 1, so that the variable valve 21, the low speed extension valve 22, the low speed compression valve 23, the compression side damping valve 30 and the suction check valve 31 can be concentrated in the valve housing 10d provided outside the cylinder 1, making it easier to assemble the shock absorber D.

[0053] In the above explanation, the valve housing 10d, the variable valve 21, the low speed extension valve 22, the low speed compression valve 23, the compression damping valve 30, and the suction check valve 31 are explained using circuit diagrams. However, the specific structures will be explained below.

[0054] As shown in FIG. 3, the valve housing 10d includes a valve accommodating portion 40 having a bottomed cylindrical shape and an open upper end, and a valve cap 41 having a topped cylindrical shape that is screwed to the inner periphery of the upper end of the valve accommodating portion 40. The space formed by the valve accommodating portion 40 and the valve cap 41 accommodates the variable valve 21, the low extension side speed valve 22, the low compression side speed valve 23, the compression side damping valve 30, and the suction check valve 31.

[0055] The valve accommodating portion 40 has an inner diameter that increases stepwise from the bottom side toward the top, and is provided with a small diameter portion 40a having a small inner diameter, a medium diameter portion 40b having an inner diameter larger than that of the small diameter portion 40a, and a large diameter portion 40c having an inner diameter larger than that of the medium diameter portion 40b. The valve accommodating portion 40 is also provided with a passage 40d that opens from the annular groove 10a3 of the cap 10 and leads to the inner periphery of the large diameter portion 40c, a passage 40e that opens from the bottom 10b of the cap 10 and leads to the inner periphery of the small diameter portion 40a, and a passage 40f that opens from the inner periphery of the small diameter portion 40a, closer to the bottom than the opening of the passage 40e, and communicates with the inside of the tank 18.

[0056] The expansion-side chamber R1 is connected to the compression-side chamber R2 by the passage 40d in the valve accommodating portion 40, the interior of the valve accommodating portion 40, the passage 40e, and the annular passage C, and the compression-side chamber R2 is connected to the tank 18 by the passage 40e, the interior of the valve accommodating portion 40, and the passage 40f. Thus, an external passage P is formed by the passage 40d in the valve accommodating portion 40, the interior of the valve accommodating portion 40, and the passage 40e.

[0057] 3, is provided with a threaded portion 41a on the outer periphery of the lower end, and is fixed to the valve accommodating portion 40 by screwing the threaded portion 41a into a threaded portion 40g provided on the inner periphery of the large diameter portion 40c of the valve accommodating portion 40. A seal ring 41b that is in close contact with the inner periphery of the large diameter portion 40c of the valve accommodating portion 40 is attached to the outer periphery of the valve cap 41, and the space formed by the valve accommodating portion 40 and the valve cap 41 is sealed by the seal ring 41b.

[0058] The variable valve 21 is configured as a solenoid valve including 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 that houses the valve seat member 42 and the valve body 43, and a coil spring 45 that biases the valve body 43.

[0059] Although not shown in detail, the solenoid Sol comprises a cylindrical frame 35 with a bottom, a coil (not shown) housed within the frame 35, a first fixed core (not shown) housed on the bottom side of the frame 35, an annular second fixed core 36 that is fitted into the inner periphery of the opening end of the frame 35 and faces the first fixed core across a gap, a plunger that is provided between the first and second fixed cores and driven downward from the frame 35 by supplying current to the coil, and a push rod 37 that is connected to the plunger and inserted into the inner periphery of the second fixed core 36.

[0060] In the solenoid Sol configured in this manner, the tip of the push rod 37, which is the lower end in FIG. 3, abuts against the valve body 43, and when electricity is applied to the coil (not shown), the plunger is attracted to the second fixed core 36, generating a thrust via the push rod 37 that pushes the valve body 43 downward in FIG. 3.

[0061] The valve seat member 42 is cylindrical and has four ports 42a that are spaced apart along the circumferential direction and communicate between the inside and outside. The upper end of the valve seat member 42 in FIG. 3 is fitted snugly into the annular recess 36a of the second fixed core 36 and is radially aligned by the solenoid Sol.

[0062] The valve body 43 is cylindrical with a top, and its outer periphery is in sliding contact with the inner periphery of the valve seat member 42. Its axial length is shorter than that of the valve seat member 42, and it is allowed to move in the axial direction within the valve seat member 42. The valve body 43 has a hole 43a at the top and four ports 43b that are spaced apart along the circumferential direction of the cylinder and communicate with the inside and outside. When the valve seat member 42 and the valve body 43 are viewed from the axial direction, the ports 42a and 43b are provided at positions that are in phase with each other in the circumferential direction. When the top of the valve body 43 abuts against the bottom of the annular recess 36a of the second fixed core 36 in the solenoid Sol, the port 43b is located above the port 42a of the valve seat member 42 in FIG. 3 and faces the inner periphery of the valve seat member 42 to be blocked. Then, as the valve body 43 moves downward in FIG. 3 from the position where its top abuts against the second fixed iron core 36 relative to the valve seat member 42, eventually port 43b comes to face port 42a, and when the two are at exactly the same height, they face each other directly and the degree of overlap is maximized.

[0063] Therefore, when the valve element 43 is driven by the solenoid Sol, the valve element 43 moves in the axial direction within the valve seat member 42, thereby changing the communication state between the port 42a and the port 43b from a state in which the port 42a of the valve seat member 42 is completely blocked to a state in which the port 42a is fully opened. In this way, the valve element 43 moves relative to the valve seat member 42 to open and close the port 42a of the valve seat member 42, and closes the port 42a when no current is supplied to the solenoid Sol, and opens the port 42a when current is supplied to the solenoid Sol and moves downward to make the port 43b face the port 42a. In addition, the variable valve 21 can adjust the relative position of the valve element 43 in the axial direction with respect to the valve seat member 42 according to the amount of current supplied to the solenoid Sol, so that the degree of opening of the port 42a can be changed by adjusting the amount of current supplied to the solenoid Sol. Although four ports 42a and four ports 43b are provided, the number of ports can be changed as desired so long as the numbers are the same. Furthermore, the shapes of ports 42a and ports 43b can also be changed as desired.

[0064] The case 44 includes a cylindrical portion 44a with a bottom, a flange 44b provided on the outer periphery of the upper end of the cylindrical portion 44a in Fig. 3, a shaft portion 44c extending downward from the center of the lower end of the cylindrical portion 44a in Fig. 3, and a hole 44d opening from the bottom of the cylindrical portion 44a and communicating with the outer periphery of the shaft portion 44c, and a part of the upper end including the flange 44b is housed in the valve cap 41. The shaft portion 44c has an outer diameter that becomes smaller halfway and includes a step portion 44g provided halfway on the outer periphery, a valve mounting portion 44h whose outer diameter is smaller below the step portion 44g in Fig. 3, and a screw portion 44i provided on the outer periphery of the tip, which is the lower end in Fig. 3 of the valve mounting portion 44h. The low speed extension valve 22, the low speed compression valve 23, the compression side damping valve 30, and the suction check valve 31 are attached to the outer periphery of the valve attachment portion 44h. However, since the aforementioned hole 44d is located on the outer periphery of the shaft portion 44c and opens toward the cylindrical portion, which is above the stepped portion 44g in FIG. 3, the hole 44d is not blocked.

[0065] As shown in FIG. 4, the inner diameter of the cylindrical portion 44a is larger than the outer diameter of the valve seat member 42, and when the valve seat member 42 is housed in the cylindrical portion 44a, a gap is provided between the cylindrical portion 44a and the valve seat member 42 to form play.

[0066] In addition, the inner diameter of the cylindrical portion 44a is larger on the open end side than on the bottom side, and even when the valve seat member 42 is housed in the cylindrical portion 44a, the port 42a of the valve seat member 42 faces the part of the cylindrical portion 44a with the larger inner diameter, and the port 42a is not blocked. In addition, the case 44 is provided with a notch 44e that leads from the outer periphery of the flange 44b to the inner periphery of the cylindrical portion 44a, and a seal ring 44f that is attached to the outer periphery of the cylindrical portion 44a.

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

[0068] Then, case 44 is inserted into valve cap 41 and flange 44b is completely accommodated within valve cap 41. Then, a retaining ring 46 having an inner diameter smaller than the outer diameter of flange 44b is fitted into annular groove 41c provided on the inner circumference of valve cap 41. Case 44 is then temporarily secured in place by retaining ring 46, preventing it from falling off valve cap 41 while allowing it to move axially relative to valve cap 41.

[0069] The valve seat member 42, the valve body 43, and the coil spring 45 are housed in the cylindrical portion 44a of the case 44, and the case 44, together with the valve seat member 42, the valve body 43, and the coil spring 45 housed therein, is temporarily assembled to the valve cap 41 by the retaining ring 46. When the flange 44b abuts against the retaining ring 46 and movement of the case 44 in the direction of retracting from the valve cap 41 is restricted, a gap is generated between the upper end of the valve seat member 42, the lower end of which in FIG. 3 abuts against the bottom of the annular recess 36a of the second fixed core 36 of the solenoid Sol, and the bottom of the cylindrical portion 44a of the case 44. 3 of the valve seat member 42 abuts against the inner surface of the top of the cylindrical portion 44a of the case 44, a gap is generated between the upper end of the flange 44b of the case 44 in FIG. 3 and the frame 35 and second fixed core 36 of the solenoid Sol, so that the upper end of the flange 44b in FIG. 3 does not abut against the frame 35 and the second fixed core 36. Therefore, when the case 44 housing the valve seat member 42 is temporarily fixed to the valve cap 41 housing the solenoid Sol by the retaining ring 46, the case 44 can move slightly in the axial direction.

[0070] Furthermore, as described above, the inner diameter of the cylindrical portion 44a of the case 44 is larger than the outer diameter of the valve seat member 42, and when the valve seat member 42 is accommodated in the case 44 and temporarily fixed to the valve cap 41 with the retaining ring 46, even if there is a misalignment between the axial center 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 sandwiched in a compressed state between the lower end of the valve body 43 in FIG. 3 and the bottom of the cylindrical portion 44a of the case 44, and constantly biases the valve body 43, the push rod 37 of the solenoid Sol, and the plunger (not shown) upward in FIG. 3. When the solenoid Sol is not energized and does not apply thrust to the valve body 43, the coil spring 45 abuts the valve body 43 against the second fixed core 36 to position the valve body 43 at a position that blocks the port 42a of the valve seat member 42, thereby closing the variable valve 21. Four notches 44e are provided at equal intervals around the circumference of the case 44, and communication between the inside and outside of the case 44 can be ensured even after the case 44 is assembled to the valve cap 41. The number of notches 44e can be changed as desired.

[0072] The variable valve 21 configured in this manner has most of the case 44 inserted into the valve accommodating portion 40 and the solenoid Sol inserted into the valve cap 41, and is accommodated inside the valve housing 10d formed by the valve accommodating portion 40 and the valve cap 41. When the solenoid Sol is not energized, the valve element 43 is pushed up by the coil spring 45 and the outer periphery of the valve element 43 blocks the port 42a of the valve seat member 42 to close the valve, and when the solenoid Sol is energized, the valve element 43 moves downward in FIG. 3 against the biasing force of the coil spring 45 and opens the valve by opposing the port 43b to the port 42a. In addition, the degree of opposition between the port 43b of the valve element 43 and the port 42a of the valve seat member 42 can be changed depending on the amount of electricity supplied to the solenoid Sol, so the variable valve 21 can adjust the degree of opening by adjusting the amount of electricity supplied to the solenoid Sol.

[0073] Note that the cylindrical portion 44a of the case 44 is fitted onto the inner periphery of the medium diameter portion 40b of the valve accommodating portion 40, and the seal ring 44f is in close contact with the inner periphery of the medium diameter portion 40b to seal between the case 44 and the valve accommodating portion 40. In addition, when the case 44 is inserted into the valve accommodating portion 40, a notch 44e in the flange 44b communicates with a passage 40d provided in the valve accommodating portion 40.

[0074] Next, the low speed extension valve 22, the low speed compression valve 23, the compression damping valve 30, and the suction check valve 31 are attached to the outer periphery of the valve attachment portion 44h of the shaft portion 44c.

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

[0076] The valve disc 50 is annular, and includes an expansion-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 that is attached to the outer periphery. The valve disc 50 is fitted to the outer periphery of the valve attachment portion 44h of the shaft portion 44c, and when inserted into the valve accommodating portion 40 together with the case 44, it is fitted to the inner periphery above the step portion 40a1 of the small diameter portion 40a in FIG. 4, and the seal ring 50c is brought into close contact with the inner periphery of the medium diameter portion 40b. Thus, the valve disc 50 divides the inside of the valve accommodating portion 40 into a space above the valve disc 50 and a space below the valve disc 50, and the upper space and the lower space communicate with each other only through the expansion-side low-speed port 50a and the compression-side low-speed port 50b. The upper space partitioned in the valve accommodating portion 40 by the valve disc 50 is communicated with the expansion-side chamber R1 through the hole 44d provided in the case 44, the inside of the cylindrical portion 44a of the case 44, the notch 44e provided in the flange 44b, the passage 40d, the annular groove 10a3, the hole 4a, the annular passage C, and the through hole 1a. The lower space partitioned in the valve accommodating portion 40 by the valve disc 50 is communicated with the compression-side chamber R2 through the passage 40e provided in the valve accommodating portion 40. Thus, the external passage P is formed by the expansion-side low-speed port 50a, the compression-side low-speed port 50b, the hole 44d provided in the case 44, the inside of the cylindrical portion 44a of the case 44, the notch 44e provided in the flange 44b, the passage 40d, the annular groove 10a3, and the hole 4a, and communicates the expansion-side chamber R1 and the compression-side chamber R2 outside the cylinder 1 by bypassing the main damping passage M.

[0077] The low speed extension valve 22 includes a guide tube 51 that is attached to the outer periphery of the valve mounting portion 44h and arranged in contact with the inner periphery of the lower end of the valve disc 50 in FIG. 4, a valve body 52 that is attached to the outer periphery of the guide tube 51 so as to be axially movable, a disk-shaped spring bearing 53 that is overlapped on the lower end of the guide tube 51 in FIG. 4 and fitted to the outer periphery of the valve mounting portion 44h, and an annular spring member 54 that is interposed between the valve body 52 and the spring bearing 53.

[0078] Although not shown, the valve body 52 is composed of an annular leaf valve that is stacked on the lower end of the valve disc 50 in FIG. 4 and opens and closes the lower end of the low speed extension side port 50a in FIG. 4, a plurality of sub-leaf valves whose outer diameters gradually decrease are stacked below in FIG. 4 on the back surface of the leaf valve, and a plurality of spacers that are stacked below the sub-leaf valves in FIG. 4 and have an outer diameter smaller than that of the sub-leaf valves.

[0079] The spring bearing 53 has an annular seat portion 53a that protrudes toward the valve disc on the outer periphery of the upper end in Fig. 4. The spring member 54 has an annular elasticity, and the outer periphery abuts against the upper end of the seat portion 53a of the spring bearing 53 in Fig. 4, and the inner periphery abuts against the lower end of the spacer of the valve body 52 in Fig. 4.

[0080] When the low speed extension valve 22 configured in this manner receives pressure from the extension chamber R1 through the low speed extension port 50a, the outer periphery of the leaf valve is bent and separated from the valve disc 50, thereby opening the low speed extension port 50a, and when the extension speed of the shock absorber D increases, the spring member 54 is bent and the entire valve body 52 moves downward in FIG. 4 relative to the guide tube 51, thereby widely opening the low speed extension port 50a. Therefore, the low speed extension valve 22 can quickly build up the damping force when the shock absorber D extends at an extremely low speed, and can widely open the low speed extension port 50a to reduce the damping coefficient when the shock absorber D extends at a low speed exceeding the extremely low speed, thereby improving the ride comfort of the saddle-type vehicle when traveling on good roads.

[0081] On the other hand, the compression side low speed valve 23 is configured with a guide tube 55 that is attached to the outer periphery of the valve mounting portion 44h and arranged in contact with the inner periphery of the upper end of the valve disc 50 in Figure 4, a valve body 56 that is attached to the outer periphery of the guide tube 55 so as to be axially movable, a disk-shaped spring bearing 57 that is overlapped on the upper end of the guide tube 55 in Figure 4 and fitted to the outer periphery of the valve mounting portion 44h, and annular spring member 58 that is interposed between the valve body 56 and the spring bearing 57.

[0082] Although not shown, the valve body 56 has a similar configuration to the low speed extension side valve 22, and is configured to include an annular leaf valve that is stacked on the upper end of the valve disc 50 in FIG. 4 and opens and closes the upper end of the low speed compression side port 50b in FIG. 4, a plurality of sub-leaf valves whose outer diameters gradually decrease are stacked on the upper side in FIG. 4 that forms the back surface of the leaf valve, and a plurality of spacers that are stacked above the sub-leaf valves in FIG. 4 and have an outer diameter smaller than that of the sub-leaf valves.

[0083] The spring bearing 57 has an annular seat portion 57a ​​that protrudes toward the valve disc on the outer periphery of the lower end in Fig. 4. The spring member 58 has an annular elasticity, and the outer periphery abuts against the lower end of the seat portion 57a ​​of the spring bearing 57 in Fig. 4, and the inner periphery abuts against the upper end of the spacer of the valve body 56 in Fig. 4.

[0084] When the compression side low speed valve 23 configured in this manner receives the pressure of the compression side chamber R2 through the compression side low speed port 50b, it bends the outer periphery of the leaf valve and separates it from the valve disc 50, thereby opening the compression side low speed port 50b, and when the contraction speed of the shock absorber D increases, the spring member 58 bends and the entire valve body 56 moves upward in Fig. 4 relative to the guide cylinder 55, thereby widely opening the compression side low speed port 50b. Therefore, the compression side low speed valve 23 quickly starts the damping force when the shock absorber D contracts at an extremely low speed, and when the shock absorber D contracts at a low speed exceeding the extremely low speed, it can widely open the compression side low speed port 50b to reduce the damping coefficient, thereby improving the ride comfort of the saddle-type vehicle when traveling on good roads.

[0085] The low speed extension valve 22 and the low speed compression valve 23 configured as described above are both configured to include guide tubes 51, 55, valve bodies 52, 56 movably attached to the outer periphery of the guide tubes 51, 55 in the axial direction, disk-shaped spring bearings 53, 57 superimposed on the guide tubes 51, 55, and annular spring members 54, 58 interposed between the valve bodies 52, 56 and the spring bearings 53, 57. The low speed extension valve 22 and the low speed compression valve 23 configured as described above are configured to include spring members 54, 58 formed of annular flat springs, so that the lift amount of the valve bodies 52, 56 from the valve disc 50 can be secured while shortening the overall axial length, and the ports 50a, 50b can be opened widely, and even if the flow rate passing through the ports 50a, 50b increases, a damping force suitable for driving on good roads can be exerted without excessive resistance. Therefore, according to the low speed extension valve 22 and the low speed compression valve 23 configured in this manner, it is possible to generate a damping force suitable for driving on good roads while being compact, and it is possible to prevent the shock absorber D, which is equipped with a large number of valves, from becoming large in size, and it is also possible to improve the mountability of the shock absorber D on a saddle-type vehicle.

[0086] Although both the low speed extension valve 22 and the low speed compression valve 23 are configured by stacking a plurality of sub-leaf valves on the back side of the leaf valve, the number of stacked sub-leaf valves can be changed arbitrarily according to the desired damping force characteristics when the shock absorber D expands and contracts at low speed, and the sub-leaf valves can be eliminated if they are not required. The outer diameter of the sub-leaf valve can also be appropriately changed according to the desired damping force characteristics when the shock absorber D expands and contracts at low speed. The low speed extension valve 22 and the low speed compression valve 23 may be configured by stacking annular plates without a spring member.

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

[0088] 4, and a port 60b that penetrates from the annular recess 60a to the upper end along the axial direction. The valve disc 60 fits onto the outer periphery of the valve mounting portion 44h of the shaft portion 44c, and when inserted into the valve accommodating portion 40 together with the case 44, the valve disc 60 fits onto the inner periphery of the small diameter portion 40a of the valve accommodating portion 40 and brings the outer periphery of the lower end into contact with a step 40a1 that is formed on the inner periphery of the small diameter portion 40a and is located closer to the bottom than the passage 40e.

[0089] In addition, the valve disc 60 divides the interior of the valve accommodating portion 40 into an upper space between the valve disc 50 and the valve disc 60, which is connected to the compression side chamber R2 by a passage 40e, and a lower space which is connected to the tank 18 via a passage 40f.

[0090] The compression side damping valve 30 is a laminated leaf valve formed of multiple annular plates that are laminated on the lower end of the valve disc 60 in Fig. 4 and whose inner circumferential side is fixed to the outer circumferential side of the valve mounting portion 44h, and the inner circumferential side is allowed to bend. Also, the outer diameter of the uppermost annular plate in Fig. 4, which has the maximum outer diameter of the compression side damping valve 30, is smaller than the inner diameter of the step portion 40a1 in the valve accommodation portion 40, and the compression side damping valve 30 can bend on the outer circumferential side without interfering with the inner circumferential side of the valve accommodation portion 40.

[0091] The suction check valve 31 includes a valve body 61 that is inserted axially movably into the annular recess 60a of the valve disc 60, and a spring member 62 that is housed in the annular recess 60a and biases the valve body 61 in a direction to withdraw it from the annular recess 60a.

[0092] As described above, the valve element 61 has arms extending radially from the inner circumference of the annular ring, and its outer circumference is in sliding contact with the inner circumference of the outer circumferential wall that forms the annular recess 60a of the valve disc 60, and the inner diameter of the annular ring is larger than the inner diameter of the annular recess 60a, allowing the valve element 61 to move in the axial direction within the annular recess 60a. In addition, since the inner diameter of the annular ring of the valve element 61 is larger than the inner diameter of the annular recess 60a, the valve element 61 does not close the port 60b.

[0093] In this embodiment, the outer diameters of the annular recess 60a and the valve body 61 are larger than the inner diameter of the step 40a1 formed in the small diameter portion 40a of the valve accommodating portion 40, and when the valve disc 60 is fixed with its outer periphery in contact with the step 40a1, the valve body 61 faces the step 40a1 and does not fall out of the annular recess 60a. Also, the inner diameter of the valve body 61 is smaller than the outer diameter of the compression side damping valve 30, so that the compression side damping valve 30 can be seated on and removed from the valve body 61.

[0094] The spring member 62 is a conical coil spring that is interposed between the bottom of the annular recess 60a and the valve body 61 and is housed within the annular recess 60a, and constantly biases the valve body 61 in a direction to retract from the annular recess 60a. Note that the spring member 62 may be a spring other than a coil spring as long as it does not provide excessive resistance to the flow of liquid passing through the port 60b.

[0095] In the suction check valve 31 configured in this manner, the spring member 62 contracts and the valve body 61 moves toward the bottom side within the annular recess 60a in response to the flow of liquid passing through the port 60b from the tank 18 toward the compression side chamber R2, thereby opening the port 60b and allowing the flow of liquid from the tank 18 toward the compression side chamber R2. Conversely, the suction check valve 31 abuts the valve body 61 against the step portion 40a1 in response to the flow of liquid passing through the port 60b from the compression side chamber R2 toward the tank 18. When the valve body 61 abuts against the step portion 40a1, it cannot retreat any further from the annular recess 60a and its movement is restricted.

[0096] On the other hand, the compression side damping valve 30 bends its outer circumferential side against the flow of liquid passing through the port 60b from the compression side chamber R2 toward the tank 18, moving away from the valve element 61 whose movement is restricted by abutting against the step portion 40a1, thereby opening the port 60b and providing resistance to the flow of liquid passing through the port 60b. Conversely, the compression side damping valve 30 bends its outer circumferential side toward the annular recess 60a against the flow of liquid passing through the port 60b from the compression side chamber R2 toward the tank 18, while the suction check valve 31 moves the valve element 61 toward the bottom side within the annular recess 60a to open the port 60b.

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

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

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

[0100] When the valve assembly thus assembled is inserted into the valve accommodating portion 40 and the valve cap 41 is screwed into the valve accommodating portion 40, the entire valve assembly is sandwiched between the valve cap 41 and the step 40a1 against which the valve disc 60 attached to the valve mounting portion 44h abuts, and the valve assembly is fixed within the valve housing 10d. When the case 44 was temporarily fixed to the valve cap 41, there was axial play between the case 44 and the valve cap 41, allowing for axial movement, but because the entire valve assembly is sandwiched between the step 40a1 and the valve cap 41, all of the parts constituting the variable valve 21 are fixed except for the movable parts.

[0101] Furthermore, when the valve assembly is accommodated in and fixed to the valve housing 10d, the valve disc 60 receives an axial force and comes into close contact with the step portion 40a1 of the valve accommodating portion 40, preventing the passage 40e communicating with the compression side chamber R2 and the passage 40f communicating with the tank 18 from communicating with any place other than the port 60b through the gap between the valve disc 60 and the valve accommodating portion 40. Note that a seal ring that comes into close contact with the inner periphery of the valve accommodating portion 40 may be provided on the outer periphery of the valve disc 60 to seal the gap between the valve disc 60 and the valve accommodating portion 40. In addition, the solenoid Sol may be housed in the valve cap 41, and the case 44, which houses the valve seat member 42, the valve body 43, and the coil spring 45 of the variable valve 21 in the cylindrical portion 44a, may be temporarily fixed to the valve cap 41 using a retaining ring 46, and then the low speed extension side valve 22, the low speed compression side valve 23, the compression side damping valve 30, and the suction check valve 31 may be assembled to the valve mounting portion 44h of the case 44.

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

[0103] During contraction of the shock absorber D, resistance is applied to the flow of liquid from the compression side chamber R2 to the expansion side chamber R1 by the main damping passage M or the compression side low speed valve 23, and resistance is applied to the flow of liquid from the compression side chamber R2 to the tank 18 by the compression side damping valve 30, generating a compression side damping force due to each of the resistances described above. Since the distribution ratio of the liquid passing through the main damping passage M and the compression side low speed valve 23 during contraction of the shock absorber D can be adjusted according to the amount of electricity supplied to the variable valve 21, the damping force can be adjusted to a high or low level within a range from a soft characteristic in which resistance is applied mainly by the compression side low speed valve 23 to the liquid flowing from the compression side chamber R2 to the expansion side chamber R1 to a hard characteristic in which resistance is applied mainly by the main damping passage M.

[0104] In the shock absorber D having such a specific structure, the variable valve 21 is provided in the external passage P that bypasses the main damping passage M that communicates the expansion side chamber R1 and the compression side chamber R2, and the variable valve 21 is opened and closed to adjust the flow rate distribution ratio between the main damping passage M and the external passage P, thereby adjusting the damping force while securing the damping force adjustment range. In addition, since the discharge passage EP is provided with the compression side damping valve 30, the pressure in the compression side chamber R2 can be increased to above the tank pressure during contraction, thereby generating a higher damping force than in the past. As described above, the shock absorber D of this embodiment can exert a high damping force during contraction while securing the damping force adjustment range.

[0105] In addition, in the shock absorber D having 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. Therefore, the damping force in the low speed range of extension / contraction speed can be adjusted to a high or low level, and a damping force suitable for driving on good roads with few bumps and no vibration at high speeds can be generated.

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

[0107] Furthermore, a shock absorber D having a specific structure includes a valve housing 10d that accommodates the variable valve 21, the compression side damping valve 30, and the suction check valve 31. The variable valve 21, the compression side damping valve 30, and the suction check valve 31 are coaxially inserted into the valve housing 10d, so that the valve housing 10d can be made cylindrical and the assembly work of accommodating the variable valve 21, the compression side damping valve 30, and the suction check valve 31 in the valve housing 10d is also facilitated, thereby reducing manufacturing costs.

[0108] Furthermore, in a shock absorber D having a specific structure, the variable valve 21 has a valve seat member 42 having a port 42a, a valve body 43 that moves relatively 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 an axis portion 44c that is connected to the cylindrical portion 44a, and the compression side damping valve 30 and the suction check valve 31 are attached to the axis portion 44c of the case 44. According to the shock absorber D configured in this manner, the compression side damping valve 30 and the suction check valve 31 are attached to the axis portion 44c of the case 44 that houses the valve seat member 42 and the valve body 43 of the variable valve 21, so that the compression side damping valve 30 and the suction check valve 31 can be assembled in advance to the variable valve 21 and housed in the valve housing 10d as a valve assembly, which makes it very easy to assemble the shock absorber D and reduces the manufacturing cost.

[0109] Furthermore, in a shock absorber D having a specific structure, the variable valve 21 has a valve seat member 42 having a port 42a, a valve body 43 that moves relatively 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 an axis portion 44c that is connected to the cylindrical portion 44a, and the low speed extension valve (low speed valve) 22, the low speed compression valve (low speed valve) 23, the compression side damping valve 30, and the suction check valve 31 are attached to the axis portion 44c of the case 44. According to the shock absorber D configured in this manner, all the valves installed outside the cylinder 1 are attached to the axis portion 44c of the case 44 that houses the valve seat member 42 and the valve body 43 of the variable valve 21, so that all the valves installed outside the cylinder 1 can be assembled in advance and housed in the valve housing 10d as a valve assembly, which makes it very easy to assemble the shock absorber D and further reduces the manufacturing cost.

[0110] Furthermore, in the shock absorber D of this embodiment, the solenoid Sol of the variable valve 21, the valve seat member 42, the valve body 43, the coil spring 45 and the case 44 can be temporarily fixed to the valve cap 41 which constitutes the valve housing 10d together with the valve accommodating portion 40, and the valve assembly can be assembled by attaching all of the valves that are to be installed outside the cylinder 1 to the case 44. The valve assembly can be installed in the appropriate position within the valve housing 10d simply by screwing the valve cap 41 in the assembled valve assembly to the valve accommodating portion 40, which simplifies the assembly work and, since the valve assembly can be fixed within the valve housing 10d by screwing at only one point, loosening is less likely to occur and the assembly can be made compact even if a large number of valves are provided.

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

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

[0113] 5 and facing a hole 44d provided in the case 44, and a plurality of grooves 66a2 extending radially from the recess 66a1 toward the outer periphery in the radial direction. Therefore, even when the valve seat member 66 is fitted to the base of the shaft portion 44c, the hole 44d communicates with the inside of the cylindrical portion 66b of the valve seat member 66.

[0114] Valve stoppers 67, 68 and a leaf valve 65 installed together with spacers 69, 70 between the valve stoppers 67, 68 are provided on the inner periphery of the cylindrical portion 66b of the valve seat member 66 configured in this manner.

[0115] The leaf valve 65 is configured by laminating multiple annular plates having the same inner diameter, and the inner circumference is fixed to the outer circumference of the valve mounting portion 44h, allowing the outer circumference side to bend in both the up and down directions in FIG. 5. The leaf valve 65 is configured by laminating multiple annular plates whose outer diameters gradually decrease from above to below the annular plate having the largest outer diameter at the center. The number of laminated annular plates in the leaf valve 65 can be arbitrarily changed according to the desired damping force of the shock absorber D. The annular plate having the largest outer diameter at the center of the leaf valve 65 faces the inner circumference of the annular seat portion 66c with almost no gap at its outer circumference.

[0116] The valve stoppers 67, 68 are annular and are arranged at a position separated from the leaf valve 65 via extremely small diameter spacers 69, 70 which are stacked one above the other in FIG. 5 of the leaf valve 65. When the outer circumferential side of the leaf valve 65 bends significantly and comes into contact with the leaf valve 65, the valve stoppers 67, 68 restrict further bending of the leaf valve 65 to protect the leaf valve 65.

[0117] The spacers 69, 70 are each constructed by stacking multiple annular plates, and by adjusting the number of stacked annular plates, they serve to adjust the position of the valve stoppers 67, 68 relative to the leaf valve 65 and to position the leaf valve 65 so that the outer periphery of the annular plate having the maximum outer diameter of the leaf valve 65 faces directly against the inner periphery of the annular seat portion 66c of the valve seat member 66 in the axial direction.

[0118] The leaf valve 65 has an inner circumferential side fixed to the outer circumferential side of the valve mounting portion 44h and an outer circumferential side that can be bent in the vertical direction, so that when the shock absorber D expands and the liquid flows through the external passage P from the expansion-side chamber R1 to the compression-side chamber R2, the outer circumferential side is bent downward in Fig. 5 to provide resistance to the flow of the liquid, and when the shock absorber D contracts and the liquid flows through the external passage P from the compression-side chamber R2 to the expansion-side chamber R1, the outer circumferential side is bent upward in Fig. 5 to provide resistance to the flow of the liquid. In this way, the low speed extension valve 22 and the low speed compression valve 23 are constituted by the leaf valve 65 and the valve seat member 66, and share the leaf valve 65 and the valve seat member 66.

[0119] When the variable valve 21 is open and the extension speed of the shock absorber D is extremely low, there is little difference between the pressure in the expansion-side chamber R1 and the pressure in the contraction-side chamber R2, so the leaf valve 65 hardly bends or, even if it bends downward in FIG. 5, it bends within a range where the outer periphery faces the inner periphery of the annular seat 66c, so that the liquid receives a relatively large resistance when passing between the leaf valve 65 and the annular seat 66c. Therefore, the low speed extension valve 22 can quickly build up the damping force when the shock absorber D extends at an extremely low speed. Also, when the extension speed of the shock absorber D becomes low beyond the extremely low speed, the difference between the pressure in the expansion-side chamber R1 and the pressure in the contraction-side chamber R2 becomes large, so that the outer periphery side of the leaf valve 65 bends significantly downward in FIG. 5, so that a large annular gap is generated between the outer periphery of the leaf valve 65 and the inner periphery of the annular seat 66c, allowing the liquid to pass through. Therefore, when the shock absorber D extends at a low speed exceeding the very low speed, the damping coefficient of the low speed extension valve 22 becomes smaller than that at the very low speed, thereby preventing the damping force from becoming excessive and generating a damping force suitable for driving on good roads.

[0120] On the other hand, when the contraction speed of the shock absorber D is extremely low with the variable valve 21 open, there is little difference between the pressure in the contraction side chamber R2 and the pressure in the expansion side chamber R1, so the leaf valve 65 hardly bends or, even if it bends upward in FIG. 5, it bends within a range where the outer periphery faces the inner periphery of the annular seat 66c, so that the liquid receives a relatively large resistance when passing between the leaf valve 65 and the annular seat 66c. Therefore, the contraction side low speed valve 23 can quickly build up the damping force when the shock absorber D contracts at an extremely low speed. Also, when the contraction speed of the shock absorber D becomes low beyond the extremely low speed, the difference between the pressure in the contraction side chamber R2 and the pressure in the expansion side chamber R1 becomes large, so that the outer periphery side of the leaf valve 65 bends significantly upward in FIG. 5, so that a large annular gap is generated between the outer periphery of the leaf valve 65 and the inner periphery of the annular seat 66c, allowing the liquid to pass through. Therefore, when the shock absorber D contracts at a low speed exceeding the very low speed, the damping coefficient of the compression low speed valve 23 becomes smaller than that at the very low speed, thereby preventing the damping force from becoming excessive and generating a damping force suitable for driving on good roads.

[0121] In the shock absorber D having the low speed extension valve 22 and the low speed compression valve 23 configured as described above, the low speed extension valve 22 and the low speed compression valve 23 share the leaf valve 65 and the valve seat member 66, and therefore there is no need to provide an independent leaf valve for each, so that the overall length in the axial direction is further shortened, and the overall length of the valve housing 10d is also shortened, and the shock absorber D can be further downsized. Also, even in the shock absorber D having the low speed extension valve 22 and the low speed compression valve 23 that share the leaf valve 65 and the valve seat member 66, all the valves installed outside the cylinder 1 are attached to the shaft portion 44c of the case 44 that accommodates the valve seat member 42 and the valve body 43 of the variable valve 21, so that all the valves installed outside the cylinder 1 can be assembled in advance and accommodated in the valve housing 10d as a valve assembly, which makes it very easy to assemble the shock absorber D and further reduces the manufacturing cost.

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

[0123] In the second modified example, the expansion side low speed valve 22 and the compression side low speed valve 23 are stacked above and below a valve disc 71 that is annular and has an expansion side low speed port 71a and a compression side low speed port 71b that penetrate the outer periphery of a valve seat member 42 in the axial direction.

[0124] More specifically, the valve seat member 42 is cylindrical and has the port 42a, a threaded portion 42b formed on the outer periphery of the upper end, and a stepped portion 42c provided on the outer periphery. Since the low speed extension side valve 22, the low speed compression side valve 23, and the valve disc 71 are attached to the outer periphery of the valve seat member 42 above the stepped portion 42c, the port 42a opens downward in FIG. 6 from the stepped portion 42c so as not to be blocked by the low speed extension side valve 22, the low speed compression side valve 23, and the valve disc 71.

[0125] The valve disc 71 is annular, and includes an expansion-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 that is attached to the outer periphery. The valve disc 71 is attached to the outer periphery of the valve seat member 42, above the step portion 42c in FIG. 6, and the outer periphery is fitted to the inner periphery of the cylindrical portion 44a of the case 44. When the valve disc 71 is attached to the outer periphery of the valve seat member 42 and accommodated in the cylindrical portion 44a, the valve disc 71 divides the inside of the cylindrical portion 44a into an upper space that communicates with the expansion-side chamber R1 via the notch 44e, the passage 40d, and the annular passage C, and a lower space that communicates with the compression-side chamber R2 via the variable valve 21, the hole 44d that opens in the shaft portion 44c, and the 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, thereby communicating the upper and lower spaces partitioned within the cylindrical portion 44a only through the extension side low speed port 71a and the compression side low speed port 71b.

[0126] The low speed extension valve 22 is a laminated leaf valve formed by laminating a plurality of annular plates, and the inner periphery side is fixed to the outer periphery of the valve seat member 42, and laminated below the valve disc 71 in FIG. 6, so that the bending of the outer periphery side is permitted, and opens and closes the lower end of the low speed extension port 71a in FIG. 6. Thus, the low speed extension valve 22 bends the outer periphery against the flow of liquid passing through the low speed extension port 71a from the expansion side chamber R1 to the compression side chamber R2 during the expansion operation of the shock absorber D, thereby opening the low speed extension port 71a and providing resistance. Also, the low speed extension valve 22 closes against the flow of liquid passing through the low speed extension port 71a from the compression side chamber R2 to the expansion side chamber R1 during the contraction operation of the shock absorber D, blocking the low speed extension port 71a and preventing the flow of the liquid.

[0127] On the other hand, the compression side low speed valve 23 is a laminated leaf valve formed by laminating a plurality of annular plates, and the inner periphery side is fixed to the outer periphery of the valve seat member 42, and is laminated on the upper side of the valve disc 71 in FIG. 6, so that the bending of the outer periphery side is permitted, and opens and closes the upper end of the compression side low speed port 71b in FIG. 6. Therefore, the compression side low speed valve 23 bends the outer periphery against the flow of liquid passing through the compression side low speed port 71b from the compression side chamber R2 to the expansion side chamber R1 during the contraction operation of the shock absorber D, thereby opening the compression side low speed port 71b and providing resistance. Also, the compression side low speed valve 23 closes against the flow of liquid that attempts to pass through the compression side low speed port 71b from the expansion side chamber R1 to the compression side chamber R2 during the expansion operation of the shock absorber D, blocking the compression side low speed port 71b and preventing the flow of the liquid.

[0128] The low speed expansion side valve 22, the valve disc 71, and the low speed compression side valve 23 thus configured are assembled in order to the outer periphery of the valve seat member 42, and then are sandwiched between the annular nut member 72 screwed to the screw portion 42b and the step portion 42c, and fixed to the valve seat member 42. In this embodiment, a collar 73 having 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 periphery of the nut member 72 is provided at the upper end of the valve seat member 42 in FIG. 6, thereby enabling alignment of the valve seat member 42 with the second fixed core 36.

[0129] In addition, the cylindrical portion 44a in the case 44 is expanded in diameter on the upper side in order to accommodate the low speed extension side valve 22 and the low speed compression side 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 periphery of the valve mounting portion 44h on the shaft portion 44c, the axial length of the valve mounting portion 44h is shortened accordingly.

[0130] In the shock absorber D having the low speed extension side valve 22 and the low speed compression side valve 23 configured as described above, the low speed extension side valve 22 and the low speed compression side valve 23 are disposed on the outer periphery of the valve seat member 42 of the variable valve 21 and housed in the case 44, so that the axial length of the shaft portion 44c is shortened accordingly, and the overall length of the valve housing 10d is also shortened, thereby making it possible to further miniaturize the shock absorber D. Also, even in the shock absorber D having the low speed extension side valve 22 and the low speed compression side valve 23 on the outer periphery of the valve seat member 42, the valves installed outside the cylinder 1 are attached to the case 44 of the variable valve 21, so that all the valves installed outside the cylinder 1 can be assembled in advance and housed in the valve housing 10d as a valve assembly, so that the assembly of the shock absorber D is very easy and the manufacturing cost can be further reduced.

[0131] Furthermore, in the shock absorber D of the second modified example, the extension side low speed valve 22 and the compression side low speed valve 23 are arranged on the outer circumferential side 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 leaf valves, the outer diameter of the leaf valve becomes large and the bending rigidity can be reduced accordingly. As a result, the change in the characteristics of the extension side low speed valve 22 and the compression side low speed valve 23 per one of the stacked leaf valves becomes small, which makes it easier to tune the characteristics of the extension side low speed valve 22 and the compression side low speed valve 23.

[0132] In addition, the specific shock absorber D described above includes the low speed extension valve 22 and the low speed compression valve 23, but as in the third modified example shown in Fig. 7, the low speed extension valve 22 and the low speed compression valve 23 may be eliminated and the variable valve 21, the compression damping valve 30, and the suction check valve 31 may be accommodated in the valve housing 10d. In this case, only the valve disc 60, the suction check valve 31, and the compression damping valve 30 may be attached to the shaft portion 44c of the case 44 of the variable valve 21 and accommodated in the valve accommodating portion 40. Even in the shock absorber D configured in this way, the flow rate passing through the main damping passage M can be adjusted according to the opening degree of the variable valve 21, so that not only can the damping force be adjusted to a high or low level while securing the damping force adjustment range, but also, since the exhaust passage EP includes the compression damping valve 30, the pressure in the compression chamber R2 can be increased to above the tank pressure during the contraction operation, thereby generating a damping force higher than that of the conventional shock absorber. In addition, according to the shock absorber D configured in this manner, by eliminating the low speed extension side valve 22 and the low speed compression side valve 23, the overall length of the valve housing 10d is shortened accordingly, making it possible to further miniaturize the shock absorber D. Since the valves installed outside the cylinder 1 are attached to the case 44 of the variable valve 21, all the valves installed outside the cylinder 1 can be pre-assembled and housed in the valve housing 10d as a valve assembly, making it very easy to assemble the shock absorber D and further reducing manufacturing costs.

[0133] Furthermore, as in a fourth modified example shown in Figure 8, the valve housing 10d and the tank 18 may be individually installed circumferentially offset to the side of the cap 10, and only the variable valve 21 may be accommodated in the valve housing 10d. A tank holding portion 10e for holding the tank 18 may be provided on the side of the cylindrical portion 10a of the cap 10. A passage 10e1 communicating the tank 18 with the compression side chamber R2 may be provided in the tank holding portion 10e. The compression side damping valve 30 and the suction check valve 31 may be provided within the tank holding portion 10e in the middle of the passage 10e1. In providing the compression side damping valve 30 and the suction check valve 31 in the tank holding portion 10e, the compression side damping valve 30 made of a laminated leaf valve that opens and closes a port 80a that forms a part of the discharge passage EP provided in the valve disc 80 is provided at the upper part of the valve disc 80 in Fig. 8, and the suction check valve 31 made of a leaf valve that opens and closes a port 80b that forms a part of the suction passage SP provided in the valve disc 80 and a spring that biases the leaf valve in the valve closing direction is provided at the lower part of the valve disc 80 in Fig. 8, but the structure shown in Fig. 4 may also be adopted. In addition, 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 be provided in the valve housing 10d.

[0134] In the fourth variant of the specific shock absorber D configured in this manner, the compression side damping valve 30 and the suction check valve 31 are provided in the tank holding portion 10e that holds the tank 18, rather than in the valve housing 10d in which the variable valve 21 is housed, so that the valve housing 10d can be made smaller.

[0135] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0136] 1····cylinder, 2···piston rod, 3···piston, 4···outer tube, 10d···valve housing, 18···tank, 21···variable valve, 22···low speed extension valve (low speed valve), 23···low speed compression valve (low speed valve), 30···compression damping valve, 31···suction check valve, 42···valve seat member, 42a···port, 43···valve body, 44···case, 44a···tubular portion, 44c···shaft portion, C···annular passage, D···shock absorber, EP···discharge passage, P···external passage, M···main damping passage, R1···rebound chamber, R2···compression chamber, SP···discharge passage

Claims

1. A cylinder; a piston rod inserted into the cylinder so as to be axially movable; a piston connected to the piston rod and inserted into the cylinder so as to be axially movably, the piston dividing the interior of the cylinder into an extension-side chamber and a compression-side chamber; an outer tube covering an outer peripheral side of the cylinder and forming an annular passage between the outer tube and the cylinder, the annular passage communicating with the expansion-side chamber; a tank for storing a liquid; a main damping passage that provides resistance to the flow of fluid moving back and forth between the expansion-side chamber and the compression-side chamber; an external passage provided outside the cylinder, one end of which is connected to the expansion-side chamber via the annular passage and the other end of which is connected to the compression-side chamber; a discharge passage communicating the compression side chamber with the tank; a suction passage communicating the tank with the compression-side chamber; a variable valve provided in the external passage and capable of changing a distribution ratio of a flow rate between the main damping passage and the external passage by adjusting a valve opening degree or a valve opening pressure; a compression side damping valve provided in the discharge passage to provide resistance to the flow of liquid from the compression side chamber toward the tank; a suction check valve provided in the suction passage to allow only the flow of liquid from the tank toward the pressure-side chamber; A shock absorber characterized by:

2. a low-speed valve provided in series with the variable valve in the external passage to provide resistance to the flow of fluid moving between the expansion-side chamber and the compression-side chamber; 2. The shock absorber according to claim 1.

3. a valve housing that accommodates the variable valve, the compression side damping valve, and the suction check valve; The variable valve, the compression side damping valve, and the suction check valve are coaxially inserted into the valve housing.

3. The shock absorber according to claim 1 or 2.

4. The variable valve includes a valve seat member having a port, a valve element that moves relatively to the valve seat member to open and close the port, and a case that includes a cylindrical portion that houses the valve seat member and the valve element and a shaft portion that is connected to the cylindrical portion; The compression side damping valve and the suction check valve are attached to the shaft portion of the case.

4. The shock absorber according to claim 3.

5. a low-speed valve provided in series with the variable valve in the external passage to provide resistance to the flow of fluid moving between the expansion-side chamber and the compression-side chamber; The low-speed valve is attached to the shaft portion of the valve seat member.

5. The shock absorber according to claim 4.

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