Shock absorber

Abstract

 A shock absorber (D) according to the present invention comprises: a cylinder (1); a piston rod (2) that is inserted into the cylinder (1) in a movable manner in the shaft direction; a piston (3) that partitions the inside of the cylinder (1) into an extension side room (R1) and a compression side room (R2); an outer tube (4) that covers the outer circumferential side of the cylinder (1) to form an annular passage (C); a tank (18) that reserves liquid; a main damping passage (M) that imparts resistance to the flow of the liquid passing between the extension side room (R1) and the compression side room (R2); an outside passage (P) that is provided outside the cylinder (1); an exhaust passage (EP) that connects the compression side room (R2) and the tank (18); a suction passage (SP) that connects the tank (18) and the compression side room (R2); a variable valve (21) that is provided in the outside passage (P); a compression side damping valve (30) that is provided in the exhaust passage (EP); and a suction check valve (31) that is provided in the suction passage (SP).

Description

buffer

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

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

[0003] As disclosed in JP2020-143685A, for example, such a shock absorber includes a cylinder, a piston that is movably inserted into the cylinder and divides the interior of the cylinder into an extension-side chamber and a compression-side chamber filled with hydraulic oil, a piston rod that is movably inserted into the cylinder and connected to the piston, a tank that stores hydraulic oil, a hard-side damping element that is provided on the piston and connects the extension-side chamber and the compression-side chamber and provides resistance to the flow of hydraulic oil passing through it, a bypass path that bypasses the hard-side damping element and connects the extension-side chamber and the compression-side chamber, and a soft-side damping element that is provided in the bypass path in series with a solenoid valve.

[0004] Another shock absorber, as disclosed in JP2020-143682A, for example, is configured to include a cylinder, a piston that is movably inserted into the cylinder and divides the interior of the cylinder into an extension-side chamber and a compression-side chamber filled with hydraulic oil, a piston rod that is movably inserted into the cylinder and connected to the piston, a tank that stores hydraulic oil, a hard-side damping element that is provided on the piston and connects the extension-side chamber and the compression-side chamber and provides resistance to the flow of hydraulic oil passing through, a bypass path that bypasses the hard-side damping element and connects the extension-side chamber and the compression-side chamber, a soft-side damping element that is provided in the bypass path in series with a solenoid valve, and a low-pressure priority valve that connects the low-pressure side of both ends of the bypass path that sandwich the solenoid valve and the soft-side damping element to the tank.

[0005] In a shock absorber configured in this manner, the opening area of ​​the bypass passage is adjusted using an electromagnetic valve, thereby adjusting 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 range of damping force adjustment and outputting a damping force that is optimal for suppressing vehicle vibrations.

[0006] JP2020-143685AJP2020-143682A

[0007] Conventional shock absorbers allow for a wide range of damping force adjustment, but because they use 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, causing the damping force to plateau during contraction, making it difficult to meet the demand for high damping force during contraction.

[0008] On the other hand, in other conventional shock absorbers, by providing a low-pressure priority valve, the pressure in the compression side chamber can be increased to above the tank pressure not only during extension but also during compression, thereby enabling high damping force to be exerted during compression and enabling a wide range of damping force adjustment even on the compression side. However, as mentioned above, in other conventional shock absorbers, the low-pressure priority valve is an essential component, and it is necessary to secure installation space for the low-pressure priority valve, which results in the shock absorber becoming larger.

[0009] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a shock absorber that can be made compact and that can exert a high damping force during contraction while ensuring a wide range of damping force adjustment.

[0010] In order to solve the above-mentioned problems, the shock absorber of the present invention includes a cylinder, a piston rod inserted into the cylinder so as to be movably in the axial direction, a piston connected to the piston rod and inserted into the cylinder so as to be movably in the axial direction, 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 tube and communicating with the extension-side chamber, a tank for storing liquid, a main damping passage that provides resistance to the flow of liquid moving between the extension-side chamber and the compression-side chamber, an external passage that is provided outside the cylinder and has one end connected to the extension-side chamber via the annular passage and the other end connected to the compression-side chamber, a discharge passage that connects the compression-side chamber and the tank, a suction passage that connects the tank and the compression-side chamber, a variable valve that is provided in the external passage and is capable of changing the distribution ratio of the flow rate between the main damping passage and the external passage, a compression-side damping valve that is provided in the discharge passage and provides resistance to the flow of liquid from the compression-side chamber to the tank, and a suction check valve that is provided in the suction passage and allows only the flow of liquid from the tank to the compression-side chamber.

[0011] 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 connects the extension side chamber and the compression side chamber, and by opening and closing the variable valve, the flow distribution ratio between the main damping passage and the external passage can be adjusted, thereby making it possible to adjust the damping force while ensuring a wide 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, thereby generating a higher damping force than before.

[0012] FIG. 1 is a cross-sectional view of a shock absorber according to one embodiment. FIG. 2 is a diagram showing damping force characteristics of a shock absorber according to one embodiment. FIG. 3 is a partially enlarged cross-sectional view of a shock absorber having a specific structure. FIG. 4 is an enlarged cross-sectional view of a low-speed valve, a compression side damping valve, and an intake check valve having specific structures. FIG. 5 is a partially enlarged cross-sectional view of a first modified example of a shock absorber having a specific structure. FIG. 6 is a partially enlarged cross-sectional view of a second modified example of a shock absorber having a specific structure. FIG. 7 is a partially enlarged cross-sectional view of a third modified example of a shock absorber having a specific structure. FIG. 8 is a partially enlarged cross-sectional view of a fourth modified example of a shock absorber having a specific structure. FIG. 9 is a cross-sectional view of a shock absorber according to another embodiment. FIG. 10 is a partially enlarged cross-sectional view of a shock absorber according to another embodiment having a specific structure.

[0013] 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 interior of the cylinder 1 into an extension-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 periphery and communicating with the extension-side chamber R1, a tank 18 for storing liquid, a main damping passage M providing resistance to the flow of liquid between the extension-side chamber R1 and the compression-side chamber R2, and a shock absorber D provided outside the cylinder 1 and having one end the external passage P, one end of which is connected to the expansion-side chamber R1 via the annular passage C and the other end of which is connected to the compression-side chamber R2; a discharge passage EP which connects the compression-side chamber R2 with the tank 18; an intake passage SP which connects the tank 18 with the compression-side chamber R2; a variable valve 21 which is provided in the external passage P and can change the distribution ratio of the flow rate between the main damping passage M and the external passage P; a compression-side damping valve 30 which is provided in the discharge passage EP and which applies resistance to the flow of liquid from the compression-side chamber R2 toward the tank 18; and an intake check valve 31 which is provided in the suction passage SP and which allows only the flow of liquid from the tank 18 toward the compression-side chamber R2.

[0014] Although not shown, this shock absorber D is installed between the body and rear wheel of a saddle-ride type vehicle such as a motorcycle to suppress vibrations of the body and rear wheel. Note that the shock absorber D may also be used to suppress vibrations of vehicles other than saddle-ride type vehicles.

[0015] 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 closed by a rod guide 17 and its lower end closed by a cap 10. The cylinder 1 also has a through-hole 1a on the side near its upper end, which connects the inside and outside of the cylinder 1, and a flange 1b on the outer periphery of its lower end. A seal ring 11 that fits tightly against the inner periphery of the cap 10 is attached to the outer periphery of the flange 1b, providing a seal between the cylinder 1 and the cap 10.

[0016] Furthermore, a piston rod 2 is inserted into the cylinder 1 so as to be movable in the axial direction, and the upper end of the piston rod 2 in FIG. 1, which is the tip end, protrudes outward from the upper end of the cylinder 1 in FIG.

[0017] 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 the 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.

[0018] A piston 3 attached to a piston rod 2 is inserted into the cylinder 1 so as to be axially movable, and the interior of the cylinder 1 is divided by the piston 3 into an expansion-side chamber R1 above the piston 3 and a compression-side chamber R2 below the piston 3. The expansion-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.

[0019] Next, the piston 3 is annular and attached to the outer periphery of the small diameter portion 2a of the piston rod 2, and is provided with an expansion-side port 3a and a compression-side port 3b that respectively communicate in parallel with the expansion-side chamber R1 and the compression-side chamber R2. An expansion-side main damping valve 13 is annular and attached to the outer periphery of the small diameter portion 2a and opens and closes the expansion-side port 3a, and is stacked at the lower end of the piston 3 in FIG. 1. Also, an expansion-side main damping valve 14 is annular and attached to the outer periphery of the small diameter portion 2a and opens and closes the compression-side port 3b, and 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 onto 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 threaded onto the lower end of the small diameter portion 2a.

[0020] 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 on the lower end of the piston 3 in FIG. 1 , has an inner circumferential side fixed, and opens the expansion-side port 3a when the outer circumferential side is deflected by the pressure in the expansion-side chamber R1. The expansion-side main damping valve 13 is capable of opening and closing the expansion-side port 3a, opens when the shock absorber D expands, and provides resistance to the flow of fluid passing through the expansion-side port 3a from the expansion-side chamber R1 to the compression-side chamber R2, and closes when the shock absorber D contracts, and blocks 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 provides resistance to the flow of fluid from the expansion-side chamber R1 to the compression-side chamber R2 and can exert a damping force that prevents the expansion of the shock absorber D when the shock absorber D expands.

[0021] In contrast, in the shock absorber D of this embodiment, the compression side main damping valve 14 is a laminated leaf valve configured by stacking multiple annular plates on the upper end of the piston 3 in FIG. 1 , with the inner circumferential side fixed and opening the compression side port 3b when the outer circumferential side is deflected by the pressure in the compression side chamber R2. The compression side main damping valve 14 is capable of opening and closing the compression side port 3b, and opens when the shock absorber D contracts to provide resistance to the flow of fluid passing through the compression side port 3b from the compression side chamber R2 to the expansion side chamber R1, and closes to block the compression side port 3b when the shock absorber D expands. 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 fluid 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 it contracts. Also, 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 the annular plate that constitutes the extension side main damping valve 13 and the compression side main damping valve 14, or by a stamping provided in the valve seat of the piston 3 on which the annular plate is seated and released.

[0022] In this way, 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. Furthermore, 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 fluid passing through the expansion-side port 3a and the compression-side port 3b and moving back and forth 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 fluid passing through the expansion-side port 3a, and the compression-side main damping valve 14 provides resistance to the flow of fluid 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 configure a main damping passage M that provides resistance to the flow of fluid 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 fluid reciprocating between the expansion-side chamber R1 and the compression-side chamber R2.

[0023] As shown in Figure 1, the outer tube 4 is cylindrical and covers the outer periphery of the cylinder 1, forming an annular passage C with the annular gap between it and the cylinder 1. The outer tube 4 has a hole 4a provided slightly above the lower end to communicate between the inside and outside, and a threaded portion 4b provided on the outer periphery at a position spaced apart and above the hole 4a. The lower end of the outer tube 4 in Figure 1 is closed by a cap 10 that is screwed together using the threaded portion 4b on the outer periphery.

[0024] 1, a rod guide 17 is fixed to the inner periphery of the upper end of the outer tube 4, 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 an annular seal member 17b and an annular bushing 17c at its inner periphery that 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 axial movement of the piston rod 2 with the bushing 17c.

[0025] The cap 10 is cylindrical with a bottom, 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.

[0026] More specifically, as shown in FIG. 1 , the cylindrical portion 10a includes a threaded portion 10a1 on the inner periphery at the upper end, an annular sealing groove 10a2 on the inner periphery below the threaded portion 10a1, and an annular groove 10a3 on the inner periphery below the sealing groove 10a2. The lower end of the cylinder 1 (see FIG. 1 ) and the lower end of the outer tube 4 (see FIG. 1 ) are inserted into the inner periphery of the cylindrical portion 10a. More specifically, when the cylinder 1 is inserted into the cylindrical portion 10a, the outer periphery of the flange 1b of the cylinder 1 is fitted into the inner periphery of the cylindrical portion 10a. Then, the lower end of the outer tube 4, which covers the outer periphery of the cylinder 1, is inserted into the cylindrical portion 10a, and the threaded portion 4b is threadedly coupled to the threaded portion 10a1. Then, the flange 1b of the cylinder 1 is sandwiched between 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 cap 10.

[0027] 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.

[0028] Furthermore, 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 tightly to the outer periphery of the outer tube 4, thereby sealing the gap between the cap 10 and the outer tube 4.

[0029] 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.

[0030] Next, the bottom 10b of the cap 10 has a recess 10b1 in the center of its 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 via the bracket 10c to a swing arm that holds the rear wheel of a saddle-riding type vehicle. Note that, although the present embodiment has been described in which 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, the piston rod 2 may also be connected to the rear wheel of the saddle-riding type vehicle and the cap 10 may also be connected to the body of the saddle-riding type vehicle.

[0031] 1, the cap 10 in this embodiment includes a valve housing 10d that is connected to the side of the cylindrical portion 10a and arranged parallel to the cylindrical portion 10a, and also includes a tank 18 that is arranged parallel to the 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 that is filled with liquid and an air chamber G that is filled with gas. Note that gas is sealed in the air chamber G so that the pressure in the air chamber G is at least equal to or greater than atmospheric pressure when the shock absorber D is fully extended. Note that the partition between the liquid chamber L and the air chamber G in the tank 18 may be formed by using an elastic partition such as the bladder 19 or a diaphragm, or by using a free piston.

[0032] The valve housing 10d is provided inside with 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 an intake passage SP that branch off from the external passage P midway, 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 an intake check valve 31 provided in the intake passage SP.

[0033] 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 that connects the expansion-side chamber R1 and the compression-side chamber R2, bypassing the main damping passage M provided in the piston 3. Note that the external passage P only needs to connect 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 modified as desired.

[0034] 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 in 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 in the external passage P.

[0035] In this embodiment, variable valve 21 includes valve element 21a that can open and close external passage P that forms part of the bypass path, spring 21b that biases valve element 21a to close, and solenoid 21c that can generate a thrust in the valve opening direction against the biasing force of spring 21b, and is an electromagnetic valve whose degree of opening can be adjusted according to the amount of current supplied to solenoid 21c and which closes when the current to solenoid 21c is cut off. Note that variable valve 21 is an electromagnetic valve whose degree of opening can be adjusted in this way, but it may also be an electromagnetic valve whose valve opening pressure can be adjusted, or it may be a variable valve in which the valve opening degree or valve opening pressure is adjusted manually.

[0036] 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 low-speed extension-side valve 22 has a lower valve opening pressure than the main extension-side damping valve 13, and opens prior to the main extension-side damping valve 13 to generate a damping force when the extension speed of the shock absorber D is low.

[0037] 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 before the compression side main damping valve 14 to generate a damping force.

[0038] 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 expansion-side chamber R1 to the compression-side chamber R2 and provides resistance to the flow of liquid passing through, and the compression-side low speed valve 23, which allows only the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1 and provides resistance to the flow of liquid passing through. These extension-side low speed valve 22 and the compression-side low speed valve 23 are defined as low speed valves, but any valve that allows the flow of liquid reciprocating between the expansion-side chamber R1 and the compression-side chamber R2 and provides resistance to the flow of liquid passing through may also be defined as the low speed valve.

[0039] The exhaust passage EP and the suction passage SP are branched off from the external passage P at a position closer to the compression side chamber than the variable valve 21, the extension side low speed valve 22, and the compression side low speed valve 23, and are each connected to the fluid chamber L of the tank 18.

[0040] 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 flow 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.

[0041] The shock absorber D of this embodiment is configured as described above, and operation of the shock absorber D will be described below. When the shock absorber D extends, the piston rod 2 retracts from the cylinder 1, and the piston 3 compresses the extension-side chamber R1. Then, the liquid in the extension-side chamber R1 moves to the compression-side chamber R2 through an orifice (not shown) in the main damping passage M, the extension-side main damping valve 13 in the main damping passage M, or the low-speed extension-side valve 22 in the external passage P. At the same time, the suction check valve 31 opens, and an amount of liquid equivalent to the volume of the piston rod 2 retracted 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 extension-side chamber R1 to the compression-side chamber R2 by the main damping passage M or the low-speed extension-side valve 22, and an extension-side damping force is generated due to this resistance. With regard to the resistance provided 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) provides resistance to the flow of 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 provides resistance to the flow of liquid by the extension side main damping valve 13. Then, by changing the amount of current supplied to the variable valve 21, 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.

[0042] Specifically, during the extension operation of the shock absorber D, when the variable valve 21 is open, the fluid passes through the main damping passage M and the low speed extension side valve 22, but when the variable valve 21 is closed, the external passage P is blocked and the fluid cannot pass through the low speed extension side 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. Furthermore, 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 fluid passing through the external passage P increases, so that the proportion of fluid passing through the low speed extension side valve 22 increases and the proportion of fluid 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-side valve 22, as shown by the dashed line in Fig. 2, to hard characteristics generated mainly by the main damping passage M, as shown by the solid line in Fig. 2, by adjusting the amount of current supplied to the variable valve 21. Furthermore, when the extension speed reaches 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 fluid preferentially passes through the main damping passage M, so that the shock absorber D generates damping force by the extension-side main damping valve 13.

[0043] Conversely, when the shock absorber D is contracting, 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 an 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. At the same time, an excess of liquid corresponding to the volume of the piston rod 2 that has entered the cylinder 1 is created in the cylinder 1, 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. 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 is generated due to the resistances described above. With regard to the resistance provided 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) provides 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 provided to the flow of the liquid by the compression side main damping valve 14. Then, by changing the amount of current supplied to the variable valve 21, the distribution ratio of the liquid passing through the main damping passage M and the low-speed compression valve 23 during the contraction operation of the shock absorber D changes.

[0044] 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, but passes only through the main damping passage M and moves 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 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 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 compression speed is in the low-speed range during compression, the damping force characteristics generated by the shock absorber D can be changed within a range from a soft characteristic in which resistance is applied to the fluid 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. Furthermore, when the compression speed reaches the high-speed range during compression, the compression side main damping valve 14 opens widely regardless of the opening degree of the variable valve 21, and the fluid 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 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, so 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 therefore the shock absorber D can generate a higher compression side damping force than conventional shock absorbers.

[0045] In the shock absorber D of this embodiment, the extension side low speed valve 22 and the compression side low speed valve 23 are provided as low speed valves, but it is also possible to eliminate the extension side low speed valve 22 and the compression side low speed valve 23 and adjust the damping force by changing the valve opening degree of the variable valve 21.

[0046] 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 interior of the cylinder 1 into an extension-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 that is connected to the extension-side chamber R1, the tank 18 that stores liquid, the main damping passage M that provides resistance to the flow of liquid moving back and forth between the extension-side chamber R1 and the compression-side chamber R2, and the main damping passage M that is provided outside the cylinder 1 and has one end the external passage P, one end of which is connected to the expansion-side chamber R1 via an annular passage C and the other end of which is connected to the compression-side chamber R2; a discharge passage EP which connects the compression-side chamber R2 with the tank 18; an intake passage SP which connects the tank 18 with the compression-side chamber R2; a variable valve 21 which is provided in the external passage P and can change the distribution ratio of the flow rate between the main damping passage M and the external passage P; a compression-side damping valve 30 which is provided in the discharge passage EP and provides resistance to the flow of liquid from the compression-side chamber R2 toward the tank 18; and an intake check valve 31 which is provided in the suction passage SP and allows only the flow of liquid from the tank 18 toward the compression-side chamber R2.

[0047] In the shock absorber D configured as described above, 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 by opening and closing the variable valve 21, the flow rate distribution ratio between the main damping passage M and the external passage P can be adjusted to adjust the level of the damping force while ensuring a damping force adjustment range. In addition, since the compression-side damping valve 30 is provided in the discharge passage EP, the pressure in the compression-side chamber R2 can be increased to or above the tank pressure during compression without providing a low-pressure priority valve, thereby generating a higher damping force than conventional shock absorbers. As described above, the shock absorber D of this embodiment can exert a high damping force during compression while ensuring a damping force adjustment range, and can be made smaller.

[0048] Furthermore, 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 that provide resistance to the flow of fluid 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 extension / contraction speed and to generate a damping force that is suitable for when the saddle-ride type vehicle is traveling on good roads with few bumps and no vibrations at high speeds.

[0049] 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 integrated into the valve housing 10d provided outside the cylinder 1, making it easier to assemble the shock absorber D.

[0050] In the above explanation, the valve housing 10d, the variable valve 21, the extension side low speed valve 22, the compression side low speed valve 23, the compression side damping valve 30, and the suction check valve 31 have been explained using circuit diagrams. However, the specific structures will be explained below.

[0051] 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 screw-connected to the inner periphery of the upper end of the valve accommodating portion 40. The variable valve 21, 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 are accommodated in the space formed by the valve accommodating portion 40 and the valve cap 41.

[0052] The valve accommodating portion 40 has an inner diameter that increases in stages 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 on the inner periphery of the small-diameter portion 40a from a position closer to the bottom than the opening of passage 40e and communicates with the inside of the tank 18.

[0053] 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.

[0054] The valve cap 41 is cylindrical with a top and has a threaded portion 41a on the outer periphery at the bottom end in Figure 3, and is fixed to the valve accommodating portion 40 by threading 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 is attached to the outer periphery of the valve cap 41, and is in close contact with the inner periphery of the large diameter portion 40c of the valve accommodating portion 40, and the space formed by the valve accommodating portion 40 and the valve cap 41 is sealed by the seal ring 41b.

[0055] 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 that is 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.

[0056] 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 iron core (not shown) housed on the bottom side of the frame 35, a second annular fixed iron core 36 fitted into the inner periphery of the open end of the frame 35 and facing the first fixed iron core across a gap, a plunger disposed between the first fixed iron core and the second fixed iron core 36 and driven downward from the frame 35 by supplying current to the coil, and a push rod 37 connected to the plunger and inserted into the inner periphery of the second fixed iron core 36.

[0057] 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 current is applied to the coil (not shown), the plunger is attracted to the second fixed iron core 36, generating a thrust that pushes the valve body 43 downward in FIG. 3 via the push rod 37.

[0058] The valve seat member 42 is cylindrical and has four ports 42a that are spaced apart along the circumferential direction and communicate with 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.

[0059] The valve element 43 has a cylindrical shape 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, allowing axial movement within the valve seat member 42. The valve element 43 has a hole 43a at its top and four ports 43b spaced apart along the circumferential direction of the cylindrical portion to communicate with the inside and outside. When the valve seat member 42 and the valve element 43 are viewed axially, the ports 42a and 43b are located in the same circumferential phase. When the top of the valve element 43 abuts against the bottom of the annular recess 36a of the second fixed core 36 of the solenoid Sol, the port 43b is positioned higher in FIG. 3 than the port 42a of the valve seat member 42 and faces the inner periphery of the valve seat member 42, thereby blocking the flow. 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, the port 43b eventually comes to face the port 42a, and when the two are at exactly the same height, they face each other directly and the degree of overlap is maximized.

[0060] Therefore, when the valve element 43 is driven by the solenoid Sol, the valve element 43 moves axially within the valve seat member 42, thereby changing the state of communication between the ports 42a and 43b of the valve seat member 42 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; when no current is supplied to the solenoid Sol, the valve element 43 closes the port 42a; and when current is supplied to the solenoid Sol, the valve element 43 moves downward and faces the port 43b toward the port 42a, opening the port 42a. Furthermore, the variable valve 21 can adjust the axial position of the valve element 43 relative to the valve seat member 42 in accordance with the amount of current supplied to the solenoid Sol, so that the degree of opening of the port 42a can be varied 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 as long as the number is the same, and the shapes of the ports 42a and 43b can also be changed as desired.

[0061] 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 that opens from the bottom of the cylindrical portion 44a and leads to 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 decreases midway and includes a step portion 44g provided midway on the outer periphery, a valve mounting portion 44h whose outer diameter is smaller below the step portion 44g in Fig. 3, and a thread portion 44i provided on the outer periphery of the tip, which is the lower end of the valve mounting portion 44h in Fig. 3. 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, but the aforementioned hole 44d is located on the outer periphery of the shaft portion 44c and opens toward the cylindrical portion, which is higher than the stepped portion 44g in FIG. 3, and is therefore not blocked.

[0062] 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 inside the cylindrical portion 44a, a gap is provided between the cylindrical portion 44a and the valve seat member 42 to form play.

[0063] The inner diameter of the cylindrical portion 44a is larger at the open end than at the bottom, so that even when the valve seat member 42 is housed inside the cylindrical portion 44a, the port 42a of the valve seat member 42 faces the part of the cylindrical portion 44a with the larger inner diameter, preventing the port 42a from being blocked. The case 44 also has a notch 44e that extends 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.

[0064] 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 the radial and axial directions.

[0065] Then, the case 44 is inserted into the valve cap 41, and the flange 44b is completely housed within the valve cap 41. Then, a retaining ring 46, the inner diameter of which is smaller than the outer diameter of the flange 44b, is fitted into the annular groove 41c provided on the inner periphery of the valve cap 41. The case 44 is then temporarily secured by the retaining ring 46, preventing it from falling off the valve cap 41 while allowing it to move axially relative to the valve cap 41.

[0066] The valve seat member 42, the valve element 43, and the coil spring 45 are housed within the cylindrical portion 44a of the case 44, and the case 44, together with the valve seat member 42, the valve element 43, and the coil spring 45 housed therein, is temporarily assembled to the valve cap 41 by a retaining ring 46. When the flange 44b abuts against the retaining ring 46 and movement of the case 44 in the direction of retraction relative to the valve cap 41 is restricted, a gap is generated between the lower end of the valve seat member 42, the upper end of which in FIG. 3 abuts against the bottom of the annular recess 36a of the second fixed iron 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 bottom of the cylindrical portion 44a of the case 44, a gap is created between the upper end of the flange 44b of the case 44 in FIG. 3 and the frame 35 and second fixed iron 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 second fixed iron core 36. Therefore, when the case 44 that houses the valve seat member 42 is temporarily fixed to the valve cap 41 that houses the solenoid Sol with the retaining ring 46, the case 44 can move slightly in the axial direction.

[0067] 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 housed 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 centers 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.

[0068] Next, the coil spring 45 is sandwiched in a compressed state between the lower end of the valve element 43 in FIG. 3 and the bottom of the cylindrical portion 44a of the case 44, and constantly biases the valve element 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 element 43, the coil spring 45 positions the valve element 43 in contact with the second fixed core 36 to block 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, ensuring communication between the inside and outside of the case 44 even after the case 44 is assembled to the valve cap 41. The number of notches 44e can be changed as desired.

[0069] The variable valve 21 configured as described above is accommodated inside a valve housing 10d formed by the valve housing 40 and the valve cap 41, with most of the case 44 inserted into the valve accommodating portion 40 and the solenoid Sol inserted into the valve cap 41. When the solenoid Sol is not energized, the valve element 43 is pushed up by the coil spring 45, blocking the port 42a of the valve seat member 42 at its outer periphery and closing the valve. When the solenoid Sol is energized, the valve element 43 moves downward in FIG. 3 against the biasing force of the coil spring 45, opening the valve by positioning the port 43b opposite the port 42a. 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 degree of opening of the variable valve 21 can be adjusted by adjusting the amount of electricity supplied to the solenoid Sol.

[0070] 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 a seal ring 44f is tightly fitted onto the inner periphery of the medium diameter portion 40b to seal the gap between the case 44 and the valve accommodating portion 40. 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.

[0071] 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 mounted on the outer periphery of the valve mounting portion 44h of the shaft portion 44c.

[0072] 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 44 h, 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 44 h and fitted onto the inner periphery of the small diameter portion 40 a of the valve accommodating portion 40.

[0073] 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 attached to the outer periphery. The valve disc 50 is fitted onto the outer periphery of the valve attachment portion 44h of the shaft portion 44c. When inserted into the valve accommodating portion 40 together with the case 44, the valve disc 50 is fitted onto the inner periphery above the step portion 40a1 of the small-diameter portion 40a in FIG. 4, and the seal ring 50c is tightly attached to the inner periphery of the medium-diameter portion 40b. Thus, the valve disc 50 divides the interior of the valve accommodating portion 40 into an upper space and a lower space above the valve disc 50, and the upper space and the lower space are communicated only through the expansion-side low-speed port 50a and the compression-side low-speed port 50b. The upper space partitioned within the valve accommodating portion 40 by the valve disc 50 is in communication with the expansion-side chamber R1 via a hole 44d provided in the case 44, the inside of the cylindrical portion 44a of the case 44, a 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 within the valve accommodating portion 40 by the valve disc 50 is in communication with the compression-side chamber R2 via a 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 between the expansion-side chamber R1 and the compression-side chamber R2 outside the cylinder 1, bypassing the main damping passage M.

[0074] The low-speed extension valve 22 includes a guide tube 51 that is attached to the outer periphery of the valve mounting portion 44 h and that is 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 that is fitted to the outer periphery of the valve mounting portion 44 h, and an annular spring member 54 that is interposed between the valve body 52 and the spring bearing 53.

[0075] Although not shown, the valve element 52 is configured to include 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 port 50 a in FIG. 4 , a plurality of sub-leaf valves that are stacked below the leaf valve in FIG. 4 on the back surface of the leaf valve and have gradually smaller outer diameters, and a plurality of spacers that are stacked below the sub-leaf valves in FIG. 4 and have smaller outer diameters than the sub-leaf valves.

[0076] The spring bearing 53 has an annular seat portion 53a that protrudes toward the valve disc on the outer periphery of its upper end in Fig. 4. The spring member 54 is annular and elastic, and its outer periphery abuts against the upper end of the seat portion 53a of the spring bearing 53 in Fig. 4, while its inner periphery abuts against the lower end of the spacer of the valve body 52 in Fig. 4.

[0077] 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, it bends the outer periphery of the leaf valve and separates it 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 bends and the entire valve body 52 moves downward in FIG. 4 relative to the guide cylinder 51, thereby widely opening the low speed extension port 50a. Therefore, the low speed extension valve 22 quickly builds up the damping force when the shock absorber D extends at an extremely low speed, and when the shock absorber D extends at a low speed exceeding the extremely low speed, it widely opens the low speed extension port 50a and reduces the damping coefficient, thereby improving the ride comfort of the saddle-ride type vehicle when traveling on good roads.

[0078] On the other hand, the compression side low speed valve 23 is configured to include a guide tube 55 that is attached to the outer periphery of the valve mounting portion 44h and is 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 movable in the axial direction, 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 an annular spring member 58 that is interposed between the valve body 56 and the spring bearing 57.

[0079] Although not shown, the valve element 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 50 b in FIG. 4, a plurality of sub-leaf valves that are stacked above the leaf valve in FIG. 4 on the back surface of the leaf valve and have gradually smaller outer diameters, and a plurality of spacers that are stacked above the sub-leaf valves in FIG. 4 and have smaller outer diameters than the sub-leaf valves.

[0080] The spring bearing 57 has an annular seat portion 57a ​​that protrudes toward the valve disc on the outer periphery of its lower end in Fig. 4. The spring member 58 is annular and elastic, and its outer periphery abuts against the lower end of the seat portion 57a ​​of the spring bearing 57 in Fig. 4, while its inner periphery abuts against the upper end of the spacer of the valve body 56 in Fig. 4.

[0081] When the compression side low speed valve 23 configured in this manner receives pressure from 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 Figure 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 builds up 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 is possible to widely open the compression side low speed port 50b and reduce the damping coefficient, thereby improving the ride comfort of the saddle-type vehicle when traveling on good roads.

[0082] The low speed extension side valve 22 and the low speed compression side valve 23 configured as described above each include a guide tube 51, 55, a valve element 52, 56 movably attached to the outer periphery of the guide tube 51, 55 in the axial direction, a disk-shaped spring bearing 53, 57 superimposed on the guide tube 51, 55, and annular spring members 54, 58 interposed between the valve element 52, 56 and the spring bearing 53, 57. In the low speed extension side valve 22 and the low speed compression side valve 23 configured as described above, the spring members 54, 58 are formed of annular flat springs. Therefore, the lift amount of the valve element 52, 56 from the valve disc 50 can be secured while shortening the overall axial length, and the ports 50a, 50b can be widely opened. Therefore, 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, the extension side low speed valve 22 and the compression side low speed valve 23 configured in this manner are compact yet capable of generating a damping force suitable for driving on good roads, and the size of the shock absorber D equipped with a large number of valves can be prevented from increasing, thereby improving the mountability of the shock absorber D on a saddle-type vehicle.

[0083] Note that the extension side low speed valve 22 and the compression side low speed valve 23 are both configured by stacking multiple sub-leaf valves on the back side of the leaf valves, but the number of stacked sub-leaf valves can be changed as needed depending on the desired damping force characteristics when the shock absorber D expands and contracts at low speed, and sub-leaf valves can be eliminated if they are not needed. In addition, the setting of the outer diameter of the sub-leaf valves can also be appropriately changed in design depending on the desired damping force characteristics when the shock absorber D expands and contracts at low speed. In addition, the extension side low speed valve 22 and the compression side low speed valve 23 may be configured by stacking annular plates without including a spring member.

[0084] 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 into the inner periphery of the small diameter portion 40a of the valve accommodating portion 40.

[0085] 4, the valve disc 60 has an annular recess 60a that opens from the lower end, and a port 60b that penetrates from the annular recess 60a to the upper end along the axial direction. The valve disc 60 is fitted onto the outer 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 is fitted onto the inner periphery of the small diameter portion 40a of the valve accommodating portion 40, and the outer periphery of its lower end abuts against a step 40a1 that is formed on the inner periphery of the small diameter portion 40a and closer to the bottom than the passage 40e.

[0086] The valve disc 60 also 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.

[0087] The compression side damping valve 30 is a laminated leaf valve formed of a plurality of annular plates that are stacked on the lower end of the valve disc 60 in Figure 4 and whose inner peripheral side is fixed to the outer periphery of the valve mounting portion 44h, and is allowed to flex on the outer peripheral side with the inner peripheral side as the fixed end. Also, the outer diameter of the uppermost annular plate in Figure 4, which has the largest outer diameter of the compression side damping valve 30, is smaller than the inner diameter of the step portion 40a1 in the valve accommodating portion 40, and the compression side damping valve 30 can flex on the outer peripheral side without interfering with the inner periphery of the valve accommodating portion 40.

[0088] 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 retract from the annular recess 60a.

[0089] As described above, the valve element 61 has arms extending radially from the inner periphery of the annular ring, and its outer periphery is in sliding contact with the inner periphery of the outer wall that forms the annular recess 60a of the valve disc 60. 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 axially within the annular recess 60a. Furthermore, because the inner diameter of the annular ring is larger than the inner diameter of the annular recess 60a, the valve element 61 does not close the port 60b.

[0090] 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 abutting against the step 40a1, the valve body 61 faces the step 40a1 and will 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 separated from the valve body 61.

[0091] The spring member 62 is a conical coil spring that is housed within the annular recess 60a and interposed between the bottom of the annular recess 60a and the valve body 61, 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 impart excessive resistance to the flow of liquid passing through the port 60b.

[0092] In the suction check valve 31 configured in this manner, the spring member 62 contracts and the valve element 61 moves toward the bottom 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 causes the valve element 61 to abut against the step 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 element 61 abuts against the step 40a1, it cannot move any further out of the annular recess 60a and its movement is restricted.

[0093] On the other hand, the compression side damping valve 30 bends its outer circumferential side to separate it from the valve element 61, whose movement is restricted by abutting against the step portion 40a1, to open the port 60b and provide resistance to the flow of liquid passing through the port 60b, against the flow of liquid passing through the port 60b from the compression side chamber R2 toward the tank 18. 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 to the bottom side within the annular recess 60a to open the port 60b.

[0094] 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 Figure 4, and the port 60b of the valve disc 60 functions as a discharge passage EP and a suction passage SP to open and close the common port 60b. Alternatively, the valve disc 60 may be provided with a port that functions as a discharge passage EP and a port that functions as a suction passage SP, and the compression side damping valve 30, which is a stacked leaf valve or the like that opens and closes the port that functions as the discharge passage EP, and the suction check valve 31, which is a leaf valve or the like that opens and closes the port that functions as the suction passage SP, may be installed on the lower side of the valve disc 60 in Figure 4. However, if the port 60b of the valve disc 60 functions as the discharge passage EP and the suction passage SP as shown in Figure 4, 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, compression side damping valve 30, and suction check valve 31 is shortened, which is advantageous in terms of reducing the size of the valves.

[0095] 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 in this manner are assembled to the outer periphery of the valve mounting portion 44h of the shaft portion 44c in the following order: low speed compression side valve 23, valve disc 50, low speed extension side valve 22, valve disc 60, suction check valve 31, and compression side damping valve 30. Then, the assembly is fixed to the valve mounting portion 44h by a nut 59 that is screwed onto the tip of the valve mounting portion 44h.

[0096] 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 assembled to the valve mounting portion 44h of the case 44, the solenoid Sol is 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, is temporarily fixed to the valve cap 41 using the retaining ring 46. As a result, all of the valves installed outside the cylinder 1 of the shock absorber D are assembled, and the valve assembly is completed.

[0097] When the assembled valve assembly 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 attachment 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 that make up the variable valve 21 are fixed, except for the movable parts.

[0098] Furthermore, when the valve assembly is accommodated and fixed in the valve housing 10d, the valve disc 60 is subjected to 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 space 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 space between the valve disc 60 and the valve accommodating portion 40. Alternatively, the solenoid Sol may be accommodated in the valve cap 41, and the case 44, which accommodates the valve seat member 42, the valve element 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 the 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.

[0099] In the specific shock absorber D configured in this manner, resistance can be applied to the flow of fluid 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 this resistance. Then, the distribution ratio of fluid 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 current supplied to the variable valve 21, so the damping force can be adjusted between soft characteristics generated mainly by the low speed extension-side valve 22 and hard characteristics generated mainly by the main damping passage M.

[0100] Furthermore, during the contraction operation of the shock absorber D, resistance is applied to the flow of fluid 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 fluid from the compression side chamber R2 to the tank 18 by the compression side damping valve 30, and a compression side damping force is generated due to the above-mentioned resistances. Since the distribution ratio of fluid passing through the main damping passage M and the compression side low speed valve 23 during the contraction operation of the shock absorber D can be adjusted according to the amount of current supplied to the variable valve 21, the damping force can be adjusted within a range from a soft characteristic in which resistance is applied mainly by the compression side low speed valve 23 to the fluid 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.

[0101] 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 by opening and closing the variable valve 21, the flow rate distribution ratio between the main damping passage M and the external passage P can be adjusted to adjust the level of the damping force while ensuring a damping force adjustment range. In addition, since the compression-side damping valve 30 is provided in the discharge passage EP, the pressure in the compression-side chamber R2 can be increased to or above the tank pressure during compression, thereby generating a higher damping force than conventional shock absorbers. As described above, the shock absorber D of this embodiment can exert a high damping force during compression while ensuring a damping force adjustment range.

[0102] Furthermore, 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. This makes it possible to adjust the damping force in the low-speed range of extension / contraction speed, and also generates a damping force suitable for when a saddle-type vehicle is traveling on good roads with few bumps and no vibrations at high speeds.

[0103] Furthermore, in the shock absorber D having a specific structure, the variable valve 21, the extension side low speed valve 22, the compression side low speed valve 23, the compression side damping valve 30, and the suction check valve 31 can be integrated into the valve housing 10d, making it easier to assemble the shock absorber D.

[0104] The shock absorber D having the specific structure includes a valve housing 10d that houses the variable valve 21, the compression side damping valve 30, and the suction check valve 31, and the variable valve 21, the compression side damping valve 30, and the suction check valve 31 are inserted coaxially 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 inside the valve housing 10d is also facilitated, thereby reducing manufacturing costs.

[0105] 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 disc 43 that moves relatively to the valve seat member 42 to open and close the port 42a, and a case 44 that has a cylindrical portion 44a that houses the valve seat member 42 and the valve disc 43 and a shaft 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 shaft 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 shaft portion 44c of the case 44 that houses the valve seat member 42 and the valve disc 43 of the variable valve 21, and therefore the compression side damping valve 30 and the suction check valve 31 can be pre-assembled to the variable valve 21 and housed in the valve housing 10d as a valve assembly, making it possible to very easily assemble the shock absorber D and reduce manufacturing costs.

[0106] Furthermore, in a shock absorber D having a specific structure, the variable valve 21 has a valve seat member 42 with a port 42a, a valve disc 43 that moves relatively to the valve seat member 42 to open and close the port 42a, and a case 44 that has a cylindrical portion 44a that houses the valve seat member 42 and the valve disc 43 and a shaft portion 44c that is connected to the cylindrical portion 44a, and the extension side low speed valve (low speed valve) 22, the compression side low speed valve (low speed valve) 23, the compression side damping valve 30, and the suction check valve 31 are attached to the shaft portion 44c of the case 44. According to the shock absorber D configured in this manner, all of the valves installed outside the cylinder 1 are attached to the shaft portion 44c of the case 44 that houses the valve seat member 42 and the valve disc 43 of the variable valve 21. Therefore, all of the valves installed outside the cylinder 1 can be pre-assembled 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 manufacturing costs.

[0107] 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, together with the valve accommodating portion 40, constitutes the valve housing 10d, and the valve assembly can be assembled by assembling all of the valves that are 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 of the assembled valve assembly to the valve accommodating portion 40, which simplifies the assembly work and makes it less likely for the valve assembly to become loose, as it can be fixed within the valve housing 10d with only one screw connection.

[0108] 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 that faces the outer periphery of the leaf valve 65.

[0109] 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.

[0110] 5, the inner peripheral side of the main body portion 66a is provided with an annular recess 66a1 that opens from the lower end in FIG. 5 and faces the hole 44d provided in the case 44, and a plurality of grooves 66a2 that extend 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 remains in communication with the inside of the cylindrical portion 66b of the valve seat member 66.

[0111] 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.

[0112] The leaf valve 65 is constructed by stacking multiple annular plates with the same inner diameter, and the inner periphery is fixed to the outer periphery of the valve mounting portion 44h, allowing the outer periphery to bend in both the up and down directions in FIG. 5. The leaf valve 65 is constructed by stacking multiple annular plates with gradually decreasing outer diameters above and below the annular plate with the largest outer diameter at the center. The number of stacked annular plates in the leaf valve 65 can be changed as desired depending on the desired damping force of the shock absorber D. The central annular plate with the largest outer diameter in the leaf valve 65 has its outer periphery facing the inner periphery of the annular seat portion 66c with almost no gap between them.

[0113] The valve stoppers 67, 68 are annular and are arranged at a position spaced apart from the leaf valve 65 via extremely small diameter spacers 69, 70 stacked one above the other in FIG. 5 of the leaf valve 65, and when the outer periphery 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, thereby protecting the leaf valve 65.

[0114] The spacers 69, 70 are each constructed by stacking a plurality of 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.

[0115] 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 bends downward in Figure 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 bends upward in Figure 5 to provide resistance to the flow of the liquid. In this way, the extension-side low speed valve 22 and the compression-side low speed valve 23 are constituted by the leaf valve 65 and the valve seat member 66, and the leaf valve 65 and the valve seat member 66 are shared by each other.

[0116] When the extension speed of the shock absorber D is extremely low with the variable valve 21 open, 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 barely bends or, even if it bends downward in FIG. 5 , it bends only to the extent that its outer periphery faces the inner periphery of the annular seat 66 c, and therefore, liquid encounters relatively large resistance when passing between the leaf valve 65 and the annular seat 66 c. Therefore, the low-speed extension-side valve 22 can quickly build up damping force when the shock absorber D extends at extremely low speed. Furthermore, 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, and the outer periphery of the leaf valve 65 bends significantly downward in FIG. 5 , creating a large annular gap between the outer periphery of the leaf valve 65 and the inner periphery of the annular seat 66 c, allowing 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.

[0117] On the other hand, when the contraction speed of the shock absorber D is extremely slow with the variable valve 21 open, there is little difference between the pressure in the compression-side chamber R2 and the pressure in the expansion-side chamber R1, so the leaf valve 65 barely bends, or even if it bends upward in FIG. 5, it bends only to the extent that its outer periphery faces the inner periphery of the annular seat 66c, and therefore, liquid encounters relatively large resistance when passing between the leaf valve 65 and the annular seat 66c. Therefore, the low-speed contraction-side valve 23 can quickly build up the damping force when the shock absorber D contracts at extremely low speed. Furthermore, when the contraction speed of the shock absorber D becomes low beyond the extremely low speed, the difference between the pressure in the compression-side chamber R2 and the pressure in the expansion-side chamber R1 becomes large, and the outer periphery 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 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 side 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.

[0118] In the shock absorber D having the extension side low speed valve 22 and the compression side low speed valve 23 configured in this manner, the extension side low speed valve 22 and the compression side low speed valve 23 share the leaf valve 65 and the valve seat member 66, eliminating the need to provide independent leaf valves for each valve, and therefore the overall axial length is further shortened, and the overall length of the valve housing 10d is also shortened, thereby enabling a further miniaturization of the shock absorber D. Furthermore, even in the shock absorber D having the extension side low speed valve 22 and the compression side low speed valve 23 that share the leaf valve 65 and the valve seat member 66, all of 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 disc 43 of the variable valve 21. Therefore, all of the valves installed outside the cylinder 1 can be pre-assembled 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 manufacturing costs.

[0119] 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.

[0120] In the second modified example, the extension side low speed valve 22 and the compression side low speed valve 23 are stacked above and below a valve disc 71 that is provided on the outer periphery of a valve seat member 42 with an annular extension side low speed port 71 a and a compression side low speed port 71 b that penetrate the outer periphery in the axial direction.

[0121] More specifically, the valve seat member 42 is cylindrical and includes a port 42a, a threaded portion 42b formed on the outer periphery at the upper end, and a stepped portion 42c provided on the outer periphery. Note that, since the low extension side speed valve 22, the low compression side speed 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 extension side speed valve 22, the low compression side speed valve 23, and the valve disc 71.

[0122] The valve disc 71 is annular and includes an extension-side low-speed port 71a and a compression-side low-speed port 71b that penetrate from the upper end to the lower end along the axial direction, and a seal ring 71c 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 its outer periphery is fitted into the inner periphery of the tubular portion 44a of the case 44. When the valve disc 71 is attached to the outer periphery of the valve seat member 42 and housed in the tubular portion 44a, it divides the interior of the tubular portion 44a into an upper space that is connected to the extension-side chamber R1 via the notch 44e, the passage 40d, and the annular passage C, and a lower space that is connected to the compression-side chamber R2 via the variable valve 21, the hole 44d opening 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 tightly attached to the cylindrical portion 44a, and the upper and lower spaces defined within the cylindrical portion 44a are connected only through the extension side low speed port 71a and the compression side low speed port 71b.

[0123] The extension-side low speed valve 22 is a laminated leaf valve formed by stacking multiple annular plates, and its inner periphery is fixed to the outer periphery of the valve seat member 42. The inner periphery is laminated below the valve disc 71 in FIG. 6, allowing deflection on the outer periphery, thereby opening and closing the lower end of the extension-side low speed port 71a in FIG. 6. Therefore, during expansion of the shock absorber D, the extension-side low speed valve 22 deflects its outer periphery to open the extension-side low speed port 71a and provide resistance to the flow of liquid passing through the extension-side low speed port 71a from the expansion-side chamber R1 to the compression-side chamber R2. During contraction of the shock absorber D, the extension-side low speed valve 22 closes the extension-side low speed port 71a to block the flow of liquid attempting to pass through the extension-side low speed port 71a from the compression-side chamber R2 to the expansion-side chamber R1, thereby blocking the extension-side low speed port 71a and preventing the flow of liquid.

[0124] On the other hand, the compression side low speed valve 23 is a laminated leaf valve formed by stacking multiple annular plates, and its inner periphery is fixed to the outer periphery of the valve seat member 42. It is stacked above the valve disc 71 in FIG. 6 and is allowed to flex on its outer periphery, thereby opening and closing the upper end of the compression side low speed port 71b in FIG. 6. Therefore, during the contraction operation of the shock absorber D, the compression side low speed valve 23 flexes its outer periphery to open the compression side low speed port 71b and provide resistance to the flow of liquid passing through the compression side low speed port 71b from the compression side chamber R2 to the expansion side chamber R1. Furthermore, during the expansion operation of the shock absorber D, the compression side low speed valve 23 closes and blocks the compression side low speed port 71b against the flow of liquid attempting to pass through the compression side low speed port 71b from the expansion side chamber R1 to the compression side chamber R2, thereby blocking the flow of liquid.

[0125] The low speed extension side valve 22, the valve disc 71, and the low speed compression side valve 23 configured as described above are assembled in this order to the outer periphery of the valve seat member 42, and then sandwiched between the annular nut member 72 that is screwed onto the threaded portion 42b and the step portion 42c, and fixed to the valve seat member 42. In this embodiment, a collar 73 that is L-shaped in cross section and can be fitted into the annular recess 36a of the second fixed iron 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 iron core 36.

[0126] The cylindrical portion 44a in the case 44 is expanded in diameter at the top in order to accommodate the extension side low speed valve 22 and the compression side low speed valve 23 inside the cylindrical portion 44a, and 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 in the shaft portion 44c, the axial length of the valve mounting portion 44h is shortened accordingly.

[0127] In the shock absorber D having the extension side low speed valve 22 and the compression side low speed valve 23 configured in this manner, the extension side low speed valve 22 and the compression side low speed valve 23 are disposed on the outer periphery of the valve seat member 42 of the variable valve 21 and are 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. Furthermore, even in the shock absorber D having the extension side low speed valve 22 and the compression side low speed 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 of 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.

[0128] 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 valves becomes large and the bending rigidity can be reduced accordingly. This reduces the change in the characteristics of the extension side low speed valve 22 and the compression side low speed valve 23 per stacked leaf valve, making it easier to tune the characteristics of the extension side low speed valve 22 and the compression side low speed valve 23.

[0129] Furthermore, while the specific shock absorber D described above includes the extension side low speed valve 22 and the compression side low speed valve 23, it is also possible to eliminate the extension side low speed valve 22 and the compression side low speed valve 23 and instead house the variable valve 21, the compression side damping valve 30, and the suction check valve 31 in the valve housing 10d, as in a third modified example shown in Fig. 7. In this case, only the valve disc 60, the suction check valve 31, and the compression side damping valve 30 are attached to the shaft portion 44c of the case 44 of the variable valve 21 and housed in the valve housing portion 40. Even in the shock absorber D configured in this manner, the flow rate passing through the main damping passage M can be adjusted according to the degree of opening of the variable valve 21, so that not only can the damping force be adjusted high or low while ensuring a damping force adjustment range, but also, since the compression side damping valve 30 is provided in the discharge passage EP, the pressure in the compression side chamber R2 can be increased to or above the tank pressure during the contraction operation, thereby generating a higher damping force than in the past. Furthermore, with the shock absorber D configured in this manner, by eliminating the extension side low speed valve 22 and the compression side low speed valve 23, the overall length of the valve housing 10d is shortened accordingly, making it possible to further miniaturize the shock absorber D. Furthermore, since the valves installed outside the cylinder 1 are attached to the case 44 of the variable valve 21, all of the valves installed outside the cylinder 1 can be pre-assembled and housed in the valve housing 10d as a valve assembly, making it extremely easy to assemble the shock absorber D and further reducing manufacturing costs.

[0130] Furthermore, as in a fourth modified example shown in Figure 8, the valve housing 10d and the tank 18 may be installed separately, offset circumferentially to the side of the cap 10, with only the variable valve 21 housed in the valve housing 10d, and a tank holding portion 10e for holding the tank 18 may be provided on the side of the tubular portion 10a of the cap 10, with a passage 10e1 in the tank holding portion 10e connecting the tank 18 to the compression side chamber R2, and 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 installing the compression side damping valve 30 and the suction check valve 31 in the tank holding portion 10e, the compression side damping valve 30, which is a stacked 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 arranged above the valve disc 80 in Fig. 8, and the suction check valve 31, which is composed 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 arranged below the valve disc 80 in Fig. 8, but the structure shown in Fig. 4 may also be adopted. Also, in the fourth modified example, only the variable valve 21 is provided, but the variable valve 21, the low extension side speed valve 22, and the low compression side speed valve 23 may be provided inside the valve housing 10d.

[0131] 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 that houses the variable valve 21, so the valve housing 10d can be made smaller.

[0132] Next, a shock absorber D1 according to another embodiment will be described as shown in Fig. 9. In the description of the shock absorber D1 according to another embodiment, the components of the shock absorber D1 that are common to the shock absorber D according to the first embodiment will be denoted by the same reference numerals as those of the shock absorber D according to the first embodiment, and detailed description thereof will be omitted.

[0133] As shown in FIG. 9, a shock absorber D1 in another embodiment includes a cylinder 1, a piston rod 2 inserted into the cylinder 1 so as to be axially movable, a piston 3 connected to the piston rod 2 and inserted into the cylinder 1 so as to be axially movable, and dividing the interior of the cylinder 1 into an extension-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 periphery and communicating with the extension-side chamber R1, a tank 18 for storing liquid, a main damping passage M providing resistance to the flow of liquid moving back and forth between the extension-side chamber R1 and the compression-side chamber R2, and a damping passage M 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 that connects the compression-side chamber R2 with the tank 18; an intake passage SP that connects the tank 18 with the compression-side chamber R2; a variable valve 121 that is provided in the external passage P and can change the distribution ratio of the flow rate between the main damping passage M and the external passage P; a compression-side damping valve 30 that is provided in the discharge passage EP and provides resistance to the flow of liquid from the compression-side chamber R2 toward the tank 18; and an intake check valve 31 that is provided in the suction passage SP and allows only the flow of liquid from the tank 18 toward the compression-side chamber R2.

[0134] Furthermore, in the shock absorber D1 of another embodiment, the external passage P is configured to include an expansion-side bypass path B1 that bypasses the main damping passage M, connects the expansion-side chamber R1 and the compression-side chamber R2, and allows only fluid to flow from the expansion-side chamber R1 to the compression-side chamber R2, and a compression-side bypass path B2 that bypasses the main damping passage M, connects the compression-side chamber R2 and the expansion-side chamber R1, and allows only fluid to flow from the compression-side chamber R2 to the expansion-side chamber R1. The variable valve 121 is provided midway between the expansion-side bypass path B1 and the compression-side bypass path B2, and is configured as a variable valve that can increase the flow path area of ​​either the expansion-side bypass path B1 or the flow path area of ​​the compression-side bypass path B2 and decrease the other, which is different from the shock absorber D of the above-described embodiment.

[0135] The following describes in detail the differences between the shock absorber D1 of the other embodiment and the shock absorber D of the first embodiment. In the shock absorber D1 of the other embodiment, the configurations of the extension-side bypass path B1, the compression-side bypass path B2, and the variable valve 121 provided in the cap 10 are different from those of the shock absorber D. However, the other configurations, such as the cylinder 1, the piston rod 2, the piston 3, the outer tube 4, the cap 10, the main damping passage M, the external passage P, and the tank 18, are the same as those of the shock absorber D.

[0136] The external passage P is configured to include an expansion-side bypass path B1 that bypasses the main damping passage M, connects the expansion-side chamber R1 and the compression-side chamber R2, and allows only the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2, and a compression-side bypass path B2 that bypasses the main damping passage M, connects the expansion-side chamber R2 and the expansion-side chamber R1, and allows only the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1.

[0137] The valve housing 10d of the cap 10 is provided with an extension side bypass passage B1 and a compression side bypass passage B2 that open from the annular groove 10a3 of the cylindrical portion 10a and lead to a recess 10b1 provided in the bottom portion 10b, a discharge passage EP and a suction passage SP that connect the compression side chamber R2 and the tank 18, variable valves 121 provided midway along the extension side bypass passage B1 and the compression side bypass passage B2, an extension side low speed valve 22 serving as a low speed valve provided on the extension side bypass passage B1, a compression side bypass low speed valve 123 provided on the compression side bypass passage B2, a compression side damping valve 30 provided in the discharge passage EP, and a suction check valve 31 provided in the suction passage SP.

[0138] The expansion-side bypass passage B1 and the compression-side bypass passage B2 have one ends communicated with 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 ends open to the recess 10b1 of the cap 10 and communicated with the compression-side chamber R2 in the cylinder 1. In this way, the expansion-side bypass passage B1 and the compression-side bypass passage B2 function as external passages P and are arranged in parallel with each other via the annular passage C, connecting the expansion-side chamber R1 and the compression-side chamber R2. The expansion-side bypass passage B1, together with the annular passage C, constitutes the expansion-side bypass passage B1 that bypasses the main damping passage M provided in the piston 3, and the compression-side bypass passage B2, together with the annular passage C, constitutes the compression-side bypass passage B2 that bypasses the main damping passage M provided in the piston 3. The expansion-side bypass passage B1 and the compression-side bypass passage B2 may be designed in any manner as long as they bypass the main damping passage M and connect the expansion-side chamber R1 and the compression-side chamber R2.

[0139] Further, the extension side bypass path B1 is provided with an extension side bypass low speed valve 122. The extension side bypass low speed valve 122 is a damping valve that opens the extension side bypass path B1 to a liquid flow from the extension side chamber R1 to the compression side chamber R2 to provide resistance to the liquid flow, and closes the extension side bypass path B1 to a liquid flow from the compression side chamber R2 to the extension side chamber R1 to block the extension side bypass path B1, and has a valve opening pressure lower than that of the extension side main damping valve 13, so that when the extension speed of the shock absorber D1 is low, the valve opens before the extension side main damping valve 13 to generate a damping force. By providing the one-way extension side bypass low speed valve 122 in the extension side bypass path B1 in this way, the extension side bypass path B1 is set as a one-way path that allows liquid to flow only from the extension side chamber R1 to the compression side chamber R2. The expansion-side bypass path B1 may be provided with a check valve, instead of the expansion-side bypass low-speed valve 122, that allows only the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2, and may be set as a one-way path that allows only the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2.

[0140] Furthermore, the compression side bypass path B2 is provided with a compression side bypass low speed valve 123. The compression side bypass low speed valve 123 is a damping valve that opens the compression side bypass path B2 to the flow of fluid from the compression side chamber R2 to the expansion side chamber R1 to provide resistance to the flow of fluid, and closes the compression side bypass path B2 to the flow of fluid from the expansion side chamber R1 to the compression side chamber R2 to block the compression side bypass path B2, and has a valve opening pressure lower than that of the compression side main damping valve 14, so that when the contraction speed of the shock absorber D1 is low, the valve opens prior to the compression side main damping valve 14 to generate damping force. By providing the one-way compression side bypass low speed valve 123 in the compression side bypass path B2 in this way, the compression side bypass path B2 is set as a one-way path that allows fluid to flow only from the compression side chamber R2 to the expansion side chamber R1. In addition, the compression side bypass path B2 may be set as a one-way path that allows only the flow of liquid from the compression side chamber R2 to the expansion side chamber R1, by providing a check valve that allows only the flow of liquid from the compression side chamber R2 to the expansion side chamber R1 instead of the compression side bypass low speed valve 123.

[0141] In another embodiment, the variable valve 121 includes a valve element 121a that is provided between the extension side bypass path B1 and the compression side bypass path B2 and that can open and close the extension side bypass path B1 and the compression side bypass path B2, a spring 121b that biases the valve element 121a, and a solenoid 121c that applies a thrust to the valve element 121a that counteracts the biasing force of the spring 121b, thereby switching the position of the valve element 121a.

[0142] The valve element 121a is a solenoid valve having an expansion side blocking position for blocking the expansion side bypass path B1, an expansion side connecting position for connecting the expansion side bypass path B1, a compression side blocking position for blocking the compression side bypass path B2, and a compression side connecting position for connecting the compression side bypass path B2. When the solenoid 121c is not energized and only the biasing force of the spring 121b acts, the valve element 121a takes the expansion side blocking position for the expansion side bypass path B1 to block the expansion side bypass path B1 and takes the compression side connecting position for the compression side bypass path B2 to fully open the compression side bypass path B2. When the maximum current is supplied to the solenoid 121c, the valve element 121a takes the expansion side connecting position for the expansion side bypass path B1 to fully open the expansion side bypass path B1 and takes the compression side blocking position for the compression side bypass path B2 to block the compression side bypass path B2. The valve element 121a reduces the opening area of ​​the expansion-side bypass path B1 while increasing the opening area of ​​the compression-side bypass path B2 as the amount of current supplied to the solenoid 121c decreases, and conversely, the valve element 121a reduces the opening area of ​​the expansion-side bypass path B1 while decreasing the opening area of ​​the compression-side bypass path B2 as the amount of current supplied to the solenoid 121c increases. Thus, the variable valve 121 is configured as a variable valve that increases the flow path area of ​​either the expansion-side bypass path B1 or the compression-side bypass path B2 while decreasing the other.

[0143] The discharge passage EP and the suction passage SP communicate between the compression side chamber R2 and the liquid chamber L of the tank 18. 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 flow 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.

[0144] The shock absorber D1 of another embodiment is configured as described above, and operation of the shock absorber D1 will be described below. When the shock absorber D1 extends, the piston rod 2 retracts 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 bypass low-speed valve 122 in the expansion-side bypass path B1. At the same time, the suction check valve 31 opens, and an amount of liquid equivalent to the volume of the piston rod 2 retracted 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 bypass low-speed valve 122, and an expansion-side damping force is generated due to this resistance. With regard to the resistance provided when the liquid passes through the main damping passage M, when the extension speed of the shock absorber D1 is in the low-speed range, the extension side main damping valve 13 does not open and an orifice (not shown) provides resistance to the flow of liquid, and when the extension speed of the shock absorber D1 is in the high-speed range, the extension side main damping valve 13 opens and provides resistance to the flow of liquid by the extension side main damping valve 13. Then, by changing the amount of current supplied to the variable valve 121, the distribution ratio of the liquid passing through the main damping passage M and the extension side bypass passage B1 changes when the shock absorber D1 is extended.

[0145] Specifically, during the extension operation of the shock absorber D1, when the variable valve 121 opens the extension side bypass path B1, the fluid passes through the main damping passage M and the extension side bypass low speed valve 122, but when the variable valve 121 closes the extension side bypass path B1, the fluid cannot pass through the extension side bypass low speed valve 122 and moves from the expansion side chamber R1 to the compression side chamber R2 through only the main damping passage M. Furthermore, when the amount of current supplied to the variable valve 121 is increased, the degree of opening of the variable valve 121 when opening the expansion side bypass path B1 increases, and the flow rate of fluid passing through the expansion side bypass path B1 increases, so that the proportion of fluid passing through the expansion side bypass low speed valve 122 increases and the proportion of fluid passing through the main damping passage M decreases.

[0146] Therefore, by adjusting the amount of current supplied to the variable valve 121, the damping force characteristics generated by the shock absorber D1 during an extension operation when the extension speed is in the low-speed range can be changed within a range from soft characteristics generated mainly by the extension-side bypass low-speed valve 122, as shown by the dashed line in Fig. 2, to hard characteristics generated mainly by the main damping passage M, as shown by the solid line in Fig. 2, by adjusting the amount of current supplied to the variable valve 121. Furthermore, during an extension operation when the extension speed reaches a high-speed range, the extension-side main damping valve 13 opens widely regardless of the opening degree of the variable valve 121, and the fluid preferentially passes through the main damping passage M, so that the shock absorber D1 generates damping force by the extension-side main damping valve 13.

[0147] Conversely, when the shock absorber D1 is contracting, 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 an 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 bypass low speed valve 123 of the compression side bypass path B2. At the same time, an excess of liquid corresponding to the volume of the piston rod 2 that has entered the cylinder 1 is created in the cylinder 1, 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. 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 bypass low speed valve 123, 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 is generated due to the resistances described above. With regard to the resistance provided when the liquid passes through the main damping passage M, when the contraction speed of the shock absorber D1 is in the low-speed range, the compression side main damping valve 14 does not open and an orifice (not shown) provides resistance to the flow of the liquid, and when the contraction speed of the shock absorber D1 is in the high-speed range, the compression side main damping valve 14 opens and resistance is provided to the flow of the liquid by the compression side main damping valve 14. Then, by changing the amount of current supplied to the variable valve 121, the distribution ratio of the liquid passing through the main damping passage M and the compression side bypass low speed valve 123 changes when the shock absorber D1 is contracting.

[0148] Specifically, during the contraction operation of the shock absorber D1, when the variable valve 121 opens the compression side bypass path B2, the fluid passes through the main damping passage M and the compression side bypass low speed valve 123, but when the variable valve 121 closes the compression side bypass path B2, the fluid cannot pass through the compression side bypass low speed valve 123 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 no current is supplied to the variable valve 121, or when current is supplied but not to the maximum extent, the variable valve 121 opens the compression side bypass path B2, but when the amount of current supplied to the variable valve 121 is reduced, the degree of opening of the variable valve 121 increases and the flow rate of fluid passing through the compression side bypass path B2 increases, so that the proportion of fluid passing through the compression side bypass low speed valve 123 increases and the proportion of fluid passing through the main damping passage M decreases.

[0149] Therefore, by adjusting the amount of current supplied to the variable valve 121, when the compression speed is in the low-speed range during compression, the damping force characteristics generated by the shock absorber D1 can be changed within a range from a soft characteristic in which resistance is applied to the fluid flowing from the compression side chamber R2 to the expansion side chamber R1 by the compression side bypass low speed valve 123 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 121. Furthermore, when the compression speed reaches the high-speed range during compression, the compression side main damping valve 14 opens widely regardless of the opening degree of the variable valve 121, and the fluid 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 D1 generates a damping force by the compression side main damping valve 14. Furthermore, when the shock absorber D1 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, so 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, allowing the shock absorber D1 to generate a high damping force even when contracting.

[0150] The variable valve 121 decreases the flow area of ​​the compression side bypass path B2 when the flow path area of ​​the extension side bypass path B1 is increased, and increases the flow area of ​​the compression side bypass path B2 when the flow path area of ​​the extension side bypass path B1 is decreased. Therefore, when the shock absorber D1 is operating in an extension operation, the flow path area of ​​the extension side bypass path B1 is reduced to generate a hard damping force. Even if an upward impact from the road surface occurs and the operation of the shock absorber D1 switches from an extension operation to a contraction operation, the increased flow area of ​​the compression side bypass path B2 makes it easier for the shock absorber D1 to contract, preventing a stiff ride. This reduces the impact vibration acting on the vehicle body, thereby improving the ride comfort of the saddle-ride type vehicle.

[0151] Conversely, when the shock absorber D1 is contracting, the flow area of ​​the compression side bypass path B2 is reduced to generate a hard damping force. Even when the shock absorber D1 switches from contraction to extension / contraction when the vehicle comes across a depression in the road surface, the flow area of ​​the extension side bypass path B1 is larger, making it easier for the shock absorber D1 to extend, and changes in the vehicle body posture are alleviated, thereby improving the ride comfort of the vehicle.

[0152] In addition, in the shock absorber D1 of other embodiments, the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 are provided as low speed valves, but it is also possible to provide a check valve that sets the extension side bypass path B1 to a one-way path instead of the extension side bypass low speed valve 122 and a check valve that sets the compression side bypass path B2 to a one-way path instead of the compression side bypass low speed valve 123, and to adjust the damping force by changing the opening degree of the variable valve 121.

[0153] As described above, the shock absorber D1 of another 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 tank 18 for storing liquid, the main damping passage M that provides resistance to the flow of liquid moving back and forth between the expansion-side chamber R1 and the compression-side chamber R2, and the damping passage M that bypasses the main damping passage M and communicates the expansion-side chamber R1 and the compression-side chamber R2. an expansion-side bypass passage B1 that communicates the expansion-side chamber R2 with the expansion-side chamber R1 and allows only a flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2; a compression-side bypass passage B2 that bypasses the main damping passage M to communicate the expansion-side chamber R2 with the expansion-side chamber R1 and allows only a flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1; a discharge passage EP that communicates the compression-side chamber R2 with the tank 18; a suction passage SP that communicates the tank 18 with the compression-side chamber R2; a variable valve 121 that can increase the flow path area of ​​the compression side bypass passage B2 and decrease the other, a compression side damping valve 30 that is provided in the discharge passage EP and that applies resistance to the flow of liquid from the compression side chamber R2 toward the tank 18, and a suction check valve 31 that is provided in the suction passage SP and that allows only the flow of liquid from the tank 18 toward the compression side chamber R2, and an external passage P that bypasses the main damping passage M and communicates between the expansion side chamber R1 and the compression side chamber R2 and The variable valve 121 is provided midway between the extension side bypass path B1 and the compression side bypass path B2, and is configured to be able to increase the flow area of ​​one of the extension side bypass path B1 and the compression side bypass path B2 and decrease the other.

[0154] The shock absorber D1 configured in this manner is equipped with a compression side damping valve 30 and a suction check valve 31, so that the pressure in the compression side chamber can be increased to above the tank pressure during contraction operation without having to be equipped with a low pressure priority valve, thereby providing a high damping force, thereby allowing the shock absorber to be made smaller.

[0155] Furthermore, according to the shock absorber D1 of another embodiment, the expansion-side bypass path B1 and the compression-side bypass path B2 that bypass the main damping passage M that communicates between the expansion-side chamber R1 and the compression-side chamber R2 are provided with variable valves 121, and by opening and closing the variable valves 121, the flow rate distribution ratio between the main damping passage M and the expansion-side bypass path B1 and the compression-side bypass path B2 can be adjusted, thereby adjusting the damping force while ensuring a sufficient damping force adjustment range.

[0156] Furthermore, in the shock absorber D1 of another embodiment, the expansion-side bypass path B1 is provided with an expansion-side bypass low-speed valve 122 that applies resistance to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2 and blocks the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1, and the compression-side bypass path B2 is provided with a compression-side bypass low-speed valve 123 that applies resistance to the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1 and blocks the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2.

[0157] With the shock absorber D1 configured in this manner, not only can the variable valve 121 adjust the damping force in the low-speed range where the extension / contraction speed is high or low, but the extension side bypass low-speed valve 122 and the compression side bypass low-speed valve 123 can generate a damping force suitable for when the saddle-type vehicle is traveling on good roads with few bumps and no vibrations at high speeds. Furthermore, the extension side bypass low speed valve 122 functions as a check valve that sets the extension side bypass path B1 to a one-way path that allows only liquid to flow from the extension side chamber R1 to the compression side chamber R2, and the compression side bypass low speed valve 123 functions as a check valve that sets the compression side bypass path B2 to a one-way path that allows only liquid to flow from the compression side chamber R2 to the extension side chamber R1. Therefore, there is no need to install check valves other than the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 for the extension side bypass path B1 and the compression side bypass path B2, which does not lead to an increase in the size of the shock absorber D1 and makes it possible to reduce the manufacturing cost while improving the ride comfort of the vehicle.

[0158] In the shock absorber D1 of the other embodiments, the extension side bypass path B1 and the compression side bypass path B2 are provided outside the cylinder 1, so that the variable valve 121, the extension side bypass low speed valve 122, the compression side bypass low speed valve 123, the compression side damping valve 30, and the suction check valve 31 can be integrated into the valve housing 10d provided outside the cylinder 1, which makes it easy to assemble the shock absorber D1.

[0159] In the above explanation, the valve housing 10d, the variable valve 121, the extension side bypass low speed valve 122, the compression side bypass low speed valve 123, the compression side damping valve 30, and the suction check valve 31 have been explained using circuit diagrams, but the specific structures will be explained below.

[0160] As shown in FIG. 10 , the valve housing 10 d includes a valve accommodating portion 140 having a bottomed cylindrical shape and an open upper end, and a valve cap 141 having a topped cylindrical shape and screw-connected to the inner periphery of the upper end of the valve accommodating portion 140. The variable valve 121, the extension side bypass low speed valve 122, the compression side bypass low speed valve 123, the compression side damping valve 30, and the suction check valve 31 are accommodated in the space formed by the valve accommodating portion 140 and the valve cap 141.

[0161] The valve accommodating portion 140 has an inner diameter that increases in stages from the bottom side toward the top, and is provided with a small-diameter portion 140a with a small inner diameter, a medium-diameter portion 140b that is continuous with the upper part of the small-diameter portion 140a and has an inner diameter larger than that of the small-diameter portion 140a, a large-diameter portion 140c that is continuous with the upper part of the medium-diameter portion 140b and has an inner diameter larger than that of the medium-diameter portion 140b, and a cap attachment portion 140d that is continuous with the upper part of the large-diameter portion 140c and has an inner diameter larger than that of the large-diameter portion 140c, onto which the valve cap 141 is attached, as well as a passage 140e that opens from the annular groove 10a3 of the cap 10 and leads to the inner periphery of the large-diameter portion 140c, a passage 140f that opens from the bottom 10b of the cap 10 and leads to the inner periphery of the medium-diameter portion 140b, and a passage 140g that opens from the inner periphery of the small-diameter portion 140a and communicates with the inside of the tank 18.

[0162] The interior of the valve accommodating portion 140 is connected to the expansion-side chamber R1 via a passage 140e and an annular passage C, to the compression-side chamber R2 via a passage 140f, and to the tank 18 via the passage 140f.

[0163] 10, the valve cap 141 is fixed to the valve accommodating portion 140 by threading the threaded portion 141a into the threaded portion 140h provided on the inner periphery of the cap mounting portion 140d of the valve accommodating portion 140. A seal ring 141b is attached to the outer periphery of the valve cap 141, and is in close contact with the inner periphery of the cap mounting portion 140d of the valve accommodating portion 140. The space formed by the valve accommodating portion 140 and the valve cap 141 is sealed by the seal ring 141b.

[0164] The variable valve 121 is configured as a solenoid valve including a solenoid Sol, a valve seat member 142 having a compression side port 142a and an extension side port 142b, a valve body 143 that is driven by the solenoid Sol and moves relative to the valve seat member 142 to open and close the compression side port 142a and the extension side port 142b, a case 144 that houses the valve seat member 142 and the valve body 143, and a coil spring 145 that biases the valve body 143.

[0165] 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 iron core (not shown) housed on the bottom side of the frame 35, a second annular fixed iron core 36 fitted into the inner periphery of the open end of the frame 35 and facing the first fixed iron core across a gap, a plunger disposed between the first fixed iron core and the second fixed iron core 36 and driven downward from the frame 35 by supplying current to the coil, and a push rod 37 connected to the plunger and inserted into the inner periphery of the second fixed iron core 36.

[0166] In the solenoid Sol configured in this manner, the tip of the push rod 37, which is the lower end in FIG. 10, abuts against the valve body 143, and when electricity is applied to the coil (not shown), the plunger is attracted to the second fixed iron core 36, generating a thrust that pushes the valve body 143 downward in FIG. 10 via the push rod 37.

[0167] The valve seat member 142 is cylindrical and includes a plurality of compression side ports 142a that are spaced apart along the circumferential direction near the upper end in Fig. 10 and that communicate between the inside and the outside, a plurality of expansion side ports 142b that are spaced apart along the circumferential direction on the lower side in Fig. 10 and that communicate between the inside and the outside, and a threaded portion 142c that is on the outer periphery and that is directed between the compression side ports 142a and the expansion side ports 142b. Note that the expansion side bypass low speed valve 122 and the compression side bypass low speed valve 123 are attached to the outer periphery of the valve seat member 142, above the threaded portion 142c, in the central portion in the axial direction. Therefore, the compression side ports 142a and the expansion side ports 142b are open at the top and bottom avoiding the central portion of the valve seat member 142 so as not to be blocked by the expansion side bypass low speed valve 122 and the compression side bypass low speed valve 123. A collar 147 is attached to the upper end of the valve seat member 142, and is fitted snugly into the annular recess 36a of the second fixed core 36, and the valve seat member 142 is radially aligned by the solenoid Sol.

[0168] The valve disc 143 is cylindrical with a top, with its outer periphery in sliding contact with the inner periphery of the valve seat member 142. Its axial length is shorter than that of the valve seat member 142, allowing axial movement within the valve seat member 142. The valve disc 143 has a hole 143a at its top, as well as a plurality of ports 143b spaced apart along the circumferential direction of the cylindrical portion to communicate between the inside and the outside, and a plurality of ports 143c spaced apart along the circumferential direction of the cylindrical portion to communicate between the inside and the outside, at positions shifted downward in Figure 10 from ports 143b. A coil spring 145 is disposed below the valve disc 143 to urge the valve disc 143 upward.

[0169] When the valve seat member 142 and the valve element 143 are viewed in the axial direction, the compression-side port 142a and the port 143b are provided at positions where they are in phase with each other in the circumferential direction, and the expansion-side port 142b and the port 143c are provided at positions where they are in phase with each other in the circumferential direction. Furthermore, when the top of the valve element 143 abuts against the bottom of the annular recess 36a of the second fixed iron core 36 of the solenoid Sol, the port 143b directly faces the compression-side port 142a of the corresponding valve seat member 142 and is communicated with, and the port 143c is positioned higher in Figure 10 than the expansion-side port 142b of the corresponding valve seat member 142 and faces the inner periphery of the valve seat member 142 and is blocked. 10 from the position where the top of the valve disc 143 abuts against the second fixed core 36 relative to the valve seat member 142, the degree of overlap between the port 143 b and the compression-side port 142 a decreases, and the port 143 c faces the expansion-side port 142 b, increasing the degree of overlap between the port 143 c and the expansion-side port 142 b. Furthermore, when the valve disc 143 moves downward in FIG. 10 to the maximum relative to the valve seat member 142, the communication between the port 143 b and the compression-side port 142 a is cut off and opens to the inner periphery of the valve seat member 142, and the port 143 c faces directly toward the corresponding expansion-side port 142 b and is communicated with.

[0170] Therefore, when the valve body 143 is driven by the solenoid Sol, the valve body 143 moves axially within the valve seat member 142, thereby transitioning from a state in which the compression side port 142a of the valve seat member 142 is completely opened and the extension side port 142b is completely blocked, to a state in which the degree of opening of the compression side port 142a is reduced and the degree of opening of the extension side port 142b is increased, thereby completely blocking the compression side port 142a of the valve seat member 142 and completely opening the extension side port 142b.

[0171] In this way, the valve element 143 moves relative to the valve seat member 142 to open and close the compression side port 142a and the extension side port 142b of the valve seat member 142. When no current is supplied to the solenoid Sol, the valve element 143 opens the compression side port 142a and closes the extension side port 142b. When current is supplied to the solenoid Sol, the valve element 143 moves downward, and when a maximum current is supplied to the solenoid Sol, the valve element 143 closes the compression side port 142a and opens the extension side port 142b. Furthermore, when the amount of current supplied to the solenoid Sol is increased, the variable valve 121 can decrease the degree of opening of the compression side port 142a while increasing the degree of opening of the extension side port 142b. When the amount of current supplied to the solenoid Sol is decreased, the variable valve 121 can increase the degree of opening of the compression side port 142a while decreasing the degree of opening of the extension side port 142b. Therefore, the variable valve 121 can change the degree of opening of the compression side port 142a and the expansion side port 142b depending on the amount of current supplied to the solenoid Sol, and can switch between a state in which the compression side port 142a is opened and the expansion side port 142b is blocked, and a state in which the compression side port 142a is blocked and the expansion side port 142b is opened. Note that the number of ports 143b corresponding to the compression side ports 142a and the number of ports 143c corresponding to the expansion side ports 142b can be changed as desired, provided that they are the same. Furthermore, the shapes of the ports 143b corresponding to the compression side ports 142a and the ports 143c corresponding to the expansion side ports 142b can also be changed as desired.

[0172] Next, the expansion side bypass low speed valve 122 and the compression side bypass low speed valve 123 are attached to the outer periphery of the valve seat member 142. Specifically, the expansion side bypass low speed valve 122 and the compression side bypass low speed valve 123 are attached to the outer periphery of the valve seat member 142 in this order from the bottom in FIG.

[0173] The expansion-side bypass low-speed valve 122 is configured to include an expansion-side valve disc 150 that is annular and attached to the outer periphery of the valve seat member 142 and that has an expansion-side bypass port 150a that forms a part of the expansion-side bypass path B1, and a leaf valve 51 that is annular and attached to the outer periphery of the valve seat member 142 and that is stacked on the lower end of the expansion-side valve disc 150 in FIG. 10 and that opens and closes the lower end that serves as the outlet end of the expansion-side bypass port 150a.

[0174] As described above, the expansion-side valve disc 150 is annular and has the expansion-side bypass port 150a penetrating in the axial direction, and its inner circumferential side is fixed to the valve seat member 142 and attached to the outer circumferential side of the valve seat member 142. The leaf valve 151 is a laminated leaf valve formed by stacking a plurality of annular plates, and is stacked at the lower end of the expansion-side valve disc 150 with its inner circumferential side fixed to the valve seat member 142 to close the expansion-side bypass port 150a. In addition, the leaf valve 151 is allowed to flex on its unfixed outer circumferential side, and by flexing its outer circumferential side, it opens the expansion-side bypass port 150a while providing resistance to the flow of liquid passing through the expansion-side bypass port 150a.

[0175] The compression side bypass low speed valve 123 includes a compression side valve disc 152 that is annular and attached to the outer periphery of the valve seat member 142 and has a compression side bypass port 152a that forms part of the compression side bypass path B2, and a leaf valve 153 that is annular and attached to the outer periphery of the valve seat member 142 and stacked on the compression side valve disc 152 to open and close the compression side bypass port 152a.

[0176] As described above, the compression-side valve disc 152 is annular and has a compression-side bypass port 152a penetrating therethrough in the axial direction, and its inner circumferential side is fixed to the valve seat member 142 and attached to the outer circumferential side of the valve seat member 142. The leaf valve 153 is a laminated leaf valve formed by stacking a plurality of annular plates, and is stacked at the lower end of the compression-side valve disc 152 with its inner circumferential side fixed to the valve seat member 142 to close the compression-side bypass port 52a. In addition, the leaf valve 153 is allowed to flex on its unfixed outer circumferential side, and by flexing its outer circumferential side, it opens the compression-side bypass port 52a while providing resistance to the flow of liquid passing through the compression-side bypass port 52a.

[0177] The extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 configured in this manner are arranged with a cylindrical spacer 155 sandwiched between them, with the extension side bypass low speed valve 122 disposed at the lower part in FIG. 10 and the compression side bypass low speed valve 123 disposed at the upper part in FIG. 10 , and are fitted onto the outer periphery of the valve seat member 142. After that, they are fixed to the valve seat member 142 by being sandwiched between the retaining ring 54 attached to the outer periphery of the valve seat member 142 and the nut 156 screwed onto the threaded portion 142 c of the valve seat member 142.

[0178] The extension side bypass low speed valve 122, the compression side bypass low speed valve 123, the valve seat member 142, the valve body 143, and the coil spring 145 are housed in a case 144. The case 144 includes a cylindrical portion 144a with a bottom, a flange 144b provided on the outer periphery of the upper end of the cylindrical portion 144a in FIG. 10 , a shaft portion 144c extending downward from the center of the lower end of the cylindrical portion 144a in FIG. 10 , a hole 144d opening from the bottom of the cylindrical portion 144a and communicating with the outer periphery of the shaft portion 144c, and a hole 144e opening from the side of the cylindrical portion 144a and communicating between the inside and outside of the cylindrical portion 144a. A part of the upper end including the flange 144b is housed in the valve cap 141. The shaft portion 144c has a threaded portion 144f on the outer periphery of the tip, and the compression side damping valve 30 and the suction check valve 31 are attached to the outer periphery.

[0179] 10, the inner diameter of the cylindrical portion 144a is larger on the opening side than on the bottom side, and the lower end of the valve seat member 142 is fitted into the small-diameter inner periphery on the bottom side of the cylindrical portion 144a. The expansion-side port 142b of the valve seat member 142 faces the part of the cylindrical portion 144a with a larger inner diameter, and is not blocked by the case 144.

[0180] An expansion side valve disc 150 of the expansion side bypass low speed valve 122 and a compression side valve disc 152 of the compression side bypass low speed valve 123, which are fixed to the outer periphery of the valve seat member 142, are fitted into the inner periphery of the large-diameter portion of the cylindrical portion 144a. The space between the expansion side valve disc 150 and the compression side valve disc 152 inside the cylindrical portion 144a is communicated with the outside of the case 144 via a hole 144e provided in the case 144. A seal ring 150b that is in close contact with the inner periphery of the cylindrical portion 144a of the case 144 is attached to the outer periphery of the expansion side valve disc 150, and the gap between the expansion side valve disc 150 and the case 144 is sealed by this seal ring 150b. Furthermore, a seal ring 52b that is in close contact with the inner circumference of the cylindrical portion 144a of the case 144 is attached to the outer periphery of the compression-side valve disc 152, and the seal ring 52b seals the gap between the compression-side valve disc 152 and the case 144. Therefore, the space is communicated with the compression-side chamber R2 through the expansion-side bypass port 150a, the lower part of the expansion-side valve disc 150 in the cylindrical portion 144a, the expansion-side port 142b, the port 143c, the hole 144d, and the passage 140f, and is also communicated with the expansion-side chamber R1 through the hole 144e, the passage 140e, and the annular passage C. Furthermore, the space is communicated with the compression-side chamber R2 through the expansion-side bypass port 150a, the upper part of the expansion-side valve disc 150 in the cylindrical portion 144a, the compression-side port 142a, the port 143b, the hole 144d, and the passage 140f.

[0181] Therefore, during the extension operation of the shock absorber D1, the extension-side bypass low speed valve 122 opens to allow and resist the flow of liquid from the expansion-side chamber R1 through the annular passage C, the passage 140e, the hole 144e, and the expansion-side bypass port 150a toward the compression-side chamber R2, and conversely closes the expansion-side bypass port 150a to block the flow of liquid from the compression-side chamber R2 toward the expansion-side chamber R1. In this way, the extension-side bypass path B1 is formed by the through-hole 1a of the cylinder 1, the annular passage C, the passage 140e, the hole 144e, the expansion-side bypass port 150a, the inside of the valve seat member 142, the hole 144d, and the passage 140f. Furthermore, during the contraction operation of the shock absorber D1, the compression-side bypass low speed valve 123 opens to allow and resist the flow of liquid from the compression-side chamber R2 through the passage 140f, the hole 144d, the valve seat member 142, and the compression-side bypass port 152a toward the expansion-side chamber R1, and conversely closes the compression-side bypass port 152a to block the flow of liquid from the expansion-side chamber R1 toward the compression-side chamber R2. In this way, the compression-side bypass path B2 is formed by the through-hole 1a of the cylinder 1, the annular passage C, the passage 140e, the hole 144e, the compression-side bypass port 52a, the valve seat member 142, the hole 144d, and the passage 140f.

[0182] 10, a flange 144b at the upper end of the case 144 is fitted onto the inner periphery of the valve cap 141. A seal ring 144g that tightly fits onto the inner periphery of the valve cap 141 is attached to the outer periphery of the flange 144b, thereby sealing the gap between the case 144 and the valve cap 141.

[0183] Then, the case 144 is inserted into the valve cap 141, and the flange 144b is completely housed within the valve cap 141. Then, a retaining ring 146 having an inner diameter smaller than the outer diameter of the flange 144b is fitted into the annular groove 141c provided on the inner periphery of the valve cap 141. The case 144 is then temporarily secured by the retaining ring 146, preventing it from falling off the valve cap 141 while allowing it to move axially relative to the valve cap 141.

[0184] Furthermore, a valve seat member 142, a valve element 143, and a coil spring 145 are housed within a cylindrical portion 144a of the case 144, and the case 144, together with the valve seat member 142, the valve element 143, and the coil spring 145 housed therein, is temporarily assembled to the valve cap 141 by a retaining ring 146. When the flange 144b abuts against the retaining ring 146 and movement of the case 144 in the retracting direction relative to the valve cap 141 is restricted, a gap is generated between the lower end of the valve seat member 142, the upper end of which in FIG. 10 abuts against the bottom of the annular recess 36a of the second fixed iron core 36 of the solenoid Sol, and the bottom of the cylindrical portion 144a of the case 144. 10 of the valve seat member 142 abuts against the inner surface of the bottom of the cylindrical portion 144a of the case 144, a gap is created between the upper end of the flange 144b of the case 144 in FIG. 10 and the frame 35 and second fixed iron core 36 of the solenoid Sol, so that the upper end of the flange 144b in FIG. 10 does not abut against the frame 35 and the second fixed iron core 36. Therefore, when the case 144 that houses the valve seat member 142 is temporarily fixed to the valve cap 141 that houses the solenoid Sol with the retaining ring 146, the case 144 can move slightly in the axial direction.

[0185] Next, the coil spring 145 is sandwiched in a compressed state between the lower end of the valve element 143 in Figure 10 and the bottom of the cylindrical portion 144a of the case 144, and constantly urges the valve element 143, the push rod 37 of the solenoid Sol, and the plunger (not shown) upward in Figure 10. When the solenoid Sol is not energized and does not apply thrust to the valve element 143, the coil spring 145 positions the valve element 143 in contact with the second fixed iron core 36, opening the compression-side port 142a of the valve seat member 142 and blocking the expansion-side port 142b.

[0186] The variable valve 121 configured in this manner has most of the case 144 inserted into the valve accommodating portion 140 and the solenoid Sol inserted into the valve cap 141, and is accommodated inside the valve housing 10d formed by the valve accommodating portion 140 and the valve cap 141. When the solenoid Sol is not energized, the variable valve 121 is in a state in which the valve element 143 is pushed up by the coil spring 145, opening the compression side port 142a of the valve seat member 142 at its outer periphery and blocking the extension side port 142b. When a maximum current is supplied to the solenoid Sol, the valve element 143 moves maximally downward in FIG. 10 against the biasing force of the coil spring 145, blocking the compression side port 142a and opening the extension side port 142b. Furthermore, when the amount of current supplied to the solenoid Sol is less than the maximum current, the valve body 143 moves to a position where the thrust of the solenoid Sol and the spring force of the coil spring 145 are balanced, so that the variable valve 121 can adjust the degree of opening of the compression side port 142a and the degree of opening of the extension side port 142b according to the amount of current supplied to the solenoid Sol.

[0187] The cylindrical portion 144a of the case 144 is fitted onto the inner circumference of the medium diameter portion 140b of the valve accommodating portion 140, and a seal ring 144h attached to the outer circumference of the cylindrical portion 144a is tightly fitted onto the inner circumference of the medium diameter portion 140b, thereby sealing the space between the case 144 and the valve accommodating portion 140.

[0188] Next, the compression side damping valve 30 and the suction check valve 31 are attached to the outer periphery of the shaft portion 144c. The compression side damping valve 30 and the suction check valve 31 are each attached to the outer periphery of the shaft portion 144c, and are stacked on a valve disc 60 that is also attached to the outer periphery of the shaft portion 144c and fits onto the inner periphery of the medium diameter portion 140b of the valve accommodating portion 140.

[0189] 10 , and a port 60b that passes through from the annular recess 60a to the upper end along the axial direction. The valve disc 60 is fitted onto the outer periphery of the shaft portion 144c, and when inserted into the valve accommodation portion 140 together with the case 144, the outer periphery of the lower end abuts against a step portion 140i between the small diameter portion 140a and the medium diameter portion 140b of the valve accommodation portion 140.

[0190] The valve disc 60 also divides the space into one space within the valve accommodating portion 140 that is connected to the compression side chamber R2 via a passage 140e between the valve accommodating portion 140 and the bottom of the case 144, and another space that is connected to the tank 18 via a passage 140f within the small diameter portion 140a of the valve accommodating portion 140.

[0191] The compression side damping valve 30 is a laminated leaf valve formed of a plurality of annular plates that are stacked on the lower end of the valve disc 60 in Fig. 10 and whose inner circumferential side is fixed to the outer circumferential side of the shaft portion 144c, and is allowed to flex on the outer circumferential side with the inner circumferential side as the fixed end. Also, the outer diameter of the uppermost annular plate in Fig. 10 which has the largest outer diameter of the compression side damping valve 30 is smaller than the inner diameter of the step portion 140i in the valve accommodating portion 140, and the compression side damping valve 30 can flex on the outer circumferential side without interfering with the inner circumferential side of the valve accommodating portion 140.

[0192] 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 retract from the annular recess 60a.

[0193] As described above, the valve element 61 has arms extending radially from the inner periphery of the annular ring, and its outer periphery is in sliding contact with the inner periphery of the outer wall that forms the annular recess 60a of the valve disc 60. 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 axially within the annular recess 60a. Furthermore, because the inner diameter of the annular ring is larger than the inner diameter of the annular recess 60a, the valve element 61 does not close the port 60b.

[0194] In another embodiment, the outer diameters of the annular recess 60a and the valve body 61 are larger than the inner diameter of the step 140i formed in the small diameter portion 140a of the valve accommodating portion 140, and when the valve disc 60 is fixed with its outer periphery abutting against the step 140i, the valve body 61 faces the step 140i 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 separated from the valve body 61.

[0195] The spring member 62 is a conical coil spring that is housed in the annular recess 36a and interposed between the bottom of the annular recess 60a and the valve body 61, and constantly urges 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 impart excessive resistance to the flow of liquid passing through the port 60b.

[0196] In the suction check valve 31 configured in this manner, the spring member 62 contracts and the valve element 61 moves toward the bottom 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 causes the valve element 61 to abut against the step 140i 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 element 61 abuts against the step 140i, it cannot retract any further from the annular recess 60a and its movement is restricted.

[0197] 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 it away from the valve element 61, whose movement is restricted by abutting against the step portion 140i, to open the port 60b and provide 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.

[0198] 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 Figure 10, and the port 60b of the valve disc 60 functions as a discharge passage EP and a suction passage SP to open and close the common port 60b. Alternatively, the valve disc 60 may be provided with a port that functions as a discharge passage EP and a port that functions as a suction passage SP, and the compression side damping valve 30 made of a laminated leaf valve or the like that opens and closes the port that functions as the discharge passage EP may be arranged on the lower side of the valve disc 60 in Figure 10, and the suction check valve 31 made of a leaf valve or the like that opens and closes the port that functions as the suction passage SP may be arranged. However, as shown in Figure 10, if the port 60b of the valve disc 60 is made to function 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 miniaturizing the valve.

[0199] The compression side damping valve 30 and suction check valve 31 configured in this manner are assembled to the outer periphery of the shaft portion 144c of the case 144 in the order of valve disc 60, suction check valve 31 and compression side damping valve 30, and then fixed to the shaft portion 144c by a nut 159 that is screwed onto the tip of the shaft portion 144c.

[0200] As described above, after the compression side damping valve 30 and the suction check valve 31 are assembled to the shaft portion 144c of the case 144, the solenoid Sol is housed in the valve cap 141, and the case 144, which houses the valve seat member 142, the valve body 143, and the coil spring 145, to which the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 are attached, is temporarily fixed to the valve cap 141 using the retaining ring 146.As a result, all of the valves installed outside the cylinder 1 in the shock absorber D1 are assembled, and the valve assembly is completed.

[0201] When the assembled valve assembly is inserted into the valve accommodating portion 140 and the valve cap 141 is screwed into the valve accommodating portion 140, the entire valve assembly is sandwiched between the valve cap 141 and the step portion 140i against which the valve disc 60 attached to the shaft portion 144c abuts, and the valve assembly is fixed within the valve housing 10d. When the case 144 was temporarily fixed to the valve cap 141, there was axial play between the case 144 and the valve cap 141, allowing for axial movement, but because the entire valve assembly is sandwiched between the step portion 140i and the valve cap 141, all of the parts constituting the variable valve 121 are fixed except for the movable parts.

[0202] Furthermore, when the valve assembly is accommodated in and fixed to the valve housing 10d, the valve disc 60 is subjected to axial force and comes into close contact with the step portion 140i of the valve accommodating portion 140, preventing the passage 140f communicating with the compression side chamber R2 and the passage 140g 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 140. A seal ring that comes into close contact with the inner periphery of the valve accommodating portion 140 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 140. Alternatively, the solenoid Sol may be accommodated in the valve cap 141, and a case 144 having a cylindrical portion 144a that accommodates the valve seat member 142, the valve element 143, and the coil spring 145 of the variable valve 121 may be temporarily fixed to the valve cap 141 using a retaining ring 146, and then the compression side damping valve 30 and the suction check valve 31 may be assembled to the shaft portion 144c of the case 144.

[0203] In the specific shock absorber D1 configured in this manner, resistance can be applied to the flow of fluid from the extension-side chamber R1 to the compression-side chamber R2 during extension operation by the main damping passage M or the extension-side bypass low speed valve 122, and an extension-side damping force is generated due to this resistance. Then, the distribution ratio of the fluid passing through the main damping passage M and the extension-side bypass low speed valve 122 during extension operation of this shock absorber D1 can be adjusted according to the amount of current supplied to the variable valve 121, so that the damping force can be adjusted between soft characteristics generated mainly by the extension-side bypass low speed valve 122 and hard characteristics generated mainly by the main damping passage M.

[0204] Furthermore, during the contraction operation of the shock absorber D1, resistance is applied to the flow of fluid from the compression side chamber R2 to the expansion side chamber R1 by the main damping passage M or the compression side bypass low speed valve 123, and resistance is applied to the flow of fluid from the compression side chamber R2 to the tank 18 by the compression side damping valve 30, and a compression side damping force is generated due to the above-mentioned resistances. Since the distribution ratio of the fluid passing through the main damping passage M and the compression side bypass low speed valve 123 during the contraction operation of the shock absorber D1 can be adjusted according to the amount of current supplied to the variable valve 121, the damping force can be adjusted within a range from a soft characteristic in which resistance is applied mainly by the compression side bypass low speed valve 123 to the fluid 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.

[0205] In the shock absorber D1 having such a specific structure, the variable valves 121 are provided in the extension-side bypass passage B1 and the compression-side bypass passage B2 that bypass the main damping passage M that communicates the extension-side chamber R1 and the compression-side chamber R2, and the opening and closing of the variable valves 121 adjust the flow distribution ratio between the main damping passage M and the extension-side bypass passage B1 and the compression-side bypass passage B2, thereby adjusting the level of the damping force while ensuring a damping force adjustment range. In addition, since the compression-side damping valve 30 is provided in the discharge passage EP, the pressure in the compression-side chamber R2 can be increased to or above the tank pressure during a contraction operation, thereby generating a higher damping force than conventional shock absorbers. As described above, the shock absorber D1 of this embodiment can exert a high damping force during a contraction operation while ensuring a damping force adjustment range.

[0206] Furthermore, in the shock absorber D1 having a specific structure, an extension side bypass low speed valve 122 is provided in the extension side bypass path B1, and a compression side bypass low speed valve 123 is provided in the compression side bypass path B2, so that the damping force in the low extension / contraction speed range can be adjusted to a high or low level, and a damping force suitable for driving on good roads with few bumps and no vibrations at high speeds can be generated.

[0207] Furthermore, in the shock absorber D1 having a specific structure, the variable valve 121, the extension side bypass low speed valve 122, the compression side bypass low speed valve 123, 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 D1.

[0208] In addition, in the shock absorber D1 of another embodiment, the variable valve 121 includes a cylindrical valve seat member 142 having an expansion-side port 142b and a compression-side port 142a, and a cylindrical valve element 143 that moves relatively with respect to the valve seat member 142 to open and close the expansion-side port 142b and the compression-side port 142a. The expansion-side bypass low-speed valve 122 includes an annular expansion-side valve disc 150 that is attached to the outer periphery of the valve seat member 142 and has an expansion-side bypass port 150a that forms a part of the expansion-side bypass path B1, and a cylindrical valve element 143 that is attached to the outer periphery of the valve seat member 142. The compression side bypass low speed valve 123 includes a compression side valve disc 152 which is annular and attached to the outer periphery of the valve seat member 142 and has a compression side bypass port 52a which forms a part of the compression side bypass path B2, and a leaf valve 153 which is annular and attached to the outer periphery of the valve seat member 142 and attached to the compression side valve disc 152, and which opens and closes the compression side bypass port 52a.

[0209] According to the shock absorber D1 configured in this manner, the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 are disposed on the outer circumferential side of the valve seat member 142 of the variable valve 121. This reduces the overall axial length of the variable valve 121, the extension side bypass low speed valve 122, and the compression side bypass low speed valve 123, and also reduces the overall length of the valve housing 10d, thereby enabling the shock absorber D1 to be made even more compact. Furthermore, since the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 are arranged on the outer periphery of the valve seat member 142 of the variable valve 121, the outer diameters of the leaf valves 51, 53 in the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 are increased, and the bending rigidity can be reduced accordingly. As a result, the change in the characteristics of the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123 per stacked annular plate is reduced, making it easier to tune the characteristics of the extension side bypass low speed valve 122 and the compression side bypass low speed valve 123.

[0210] Furthermore, in a shock absorber D1 of another embodiment, the variable valve 121 includes a case 144 having a cylindrical portion 144a that houses the valve seat member 142, the valve element 143, the extension side bypass low speed valve 122, and the compression side bypass low speed valve 123, and a shaft portion 144c that is connected to the cylindrical portion 144a, and the compression side damping valve 30 and the suction check valve 31 are attached to the shaft portion 144c of the case 144. According to the shock absorber D1 configured in this manner, the variable valve 121, the extension side bypass low speed valve 122, the compression side bypass low speed valve 123, the compression side damping valve 30, and the suction check valve 31 can be assembled to the case 144 in advance and housed in the valve housing 10d as a valve assembly, which makes it very easy to assemble the shock absorber D1 and further reduces manufacturing costs.

[0211] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims.

[0212] 1... cylinder, 2... piston rod, 3... piston, 4... outer tube, 10d... valve housing, 18... tank, 21, 121... variable valve, 22... extension side low speed valve (low speed valve), 23... compression side low speed valve (low speed valve), 30... compression side damping valve, 31... suction check valve, 42, 142... valve seat member, 42a... port, 43, 143... valve body, 44, 144... case, 44a, 144a... cylindrical portion, 44c, 144c... shaft portion, 122... extension side valve bypass low speed valve, 123... compression side bypass low speed valve, 142a... compression side port, 142b... expansion side port, 150... expansion side valve disc, 150a... expansion side bypass port, 151, 153... leaf valve, 152... compression side valve disc, 152a... compression side bypass port, B1... expansion side bypass path, B2... compression side bypass path, C... annular passage, D, D1... shock absorber, EP... discharge passage, P... external passage, M... main damping passage, R1... expansion side chamber, R2... compression side chamber, SP... suction passage

Claims

a piston rod connected to the piston rod and inserted into the cylinder so as to be axially movable, and a piston which is connected to the piston rod and inserted into the cylinder so as to be axially movable, and which divides the inside of the cylinder into an extension-side chamber and a compression-side chamber; an outer tube which covers the outer periphery of the cylinder and forms an annular passage between the cylinder and the outer periphery and which is connected to the extension-side chamber; a tank for storing liquid; a main damping passage which provides resistance to a flow of liquid moving between the extension-side chamber and the compression-side chamber; an external passage which is provided outside the cylinder and has one end which is connected to the extension-side chamber via the annular passage and the other end which is connected to the compression-side chamber; a discharge passage which connects the compression-side chamber and the tank; a suction check valve provided in the suction passage for allowing only a flow of liquid from the tank to the compression side chamber.

2. A shock absorber as claimed in claim 1, further comprising a low-speed valve provided in series with the variable valve in the external passage to provide resistance to the flow of liquid moving between the expansion-side chamber and the compression-side chamber.

3. A shock absorber as claimed in claim 1, comprising a valve housing which houses 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 being coaxially inserted into the valve housing.

4. A shock absorber as claimed in claim 1, wherein the external passage includes an extension side bypass passage which bypasses the main damping passage, connects the extension side chamber with the compression side chamber, and allows only liquid to flow from the extension side chamber to the compression side chamber, and a compression side bypass passage which bypasses the main damping passage, connects the compression side chamber with the extension side chamber, and allows only liquid to flow from the compression side chamber to the extension side chamber, and the variable valve is provided midway between the extension side bypass passage and the compression side bypass passage and is configured to be able to increase one of the flow area of ​​the extension side bypass passage and the flow area of ​​the compression side bypass passage and decrease the other.

5. A shock absorber as claimed in claim 3, wherein the variable valve has a valve seat member with a port, a valve body that moves relative to the valve seat member to open and close the port, and a case 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 are attached to the axial portion of the case.

6. A shock absorber as claimed in claim 4, wherein the extension side bypass passage has an extension side bypass low speed valve midway which provides resistance to the flow of liquid from the extension side chamber to the compression side chamber and blocks the flow of liquid from the compression side chamber to the extension side chamber, and the compression side bypass passage has a compression side bypass low speed valve midway which provides resistance to the flow of liquid from the compression side chamber to the extension side chamber and blocks the flow of liquid from the extension side chamber to the compression side chamber.

7. A shock absorber as claimed in claim 5, further comprising a low-speed valve provided in series with the variable valve in the external passage to provide resistance to the flow of liquid moving between the expansion-side chamber and the compression-side chamber, the low-speed valve being attached to the shaft portion of the valve seat member.

8. A shock absorber as claimed in claim 6, wherein the variable valve has a cylindrical valve seat member having an extension side port and a compression side port, and a cylindrical valve body which moves relative to the valve seat member to open and close the extension side port and the compression side port, the extension side bypass low speed valve has an annular extension side valve disc which is attached to the outer periphery of the valve seat member and has an extension side bypass port which forms a part of the extension side bypass path, and a leaf valve which is annular attached to the outer periphery of the valve seat member and is stacked on the extension side valve disc to open and close the extension side bypass port, and the compression side bypass low speed valve has an annular compression side valve disc which is attached to the outer periphery of the valve seat member and has a compression side bypass port which forms a part of the compression side bypass path, and a leaf valve which is annular attached to the outer periphery of the valve seat member and is stacked on the compression side valve disc to open and close the compression side bypass port.

9. A shock absorber as claimed in claim 8, wherein the variable valve has a case having a cylindrical portion that houses the valve seat member, the valve body, the extension side bypass low speed valve and the compression side bypass low speed valve, and an axial portion connected to the cylindrical portion, and the compression side damping valve and the suction check valve are attached to the axial portion of the case.

Images