Damping valves and shock absorbers

Abstract

To provide a damping valve which can inhibit increase of manufacturing costs without causing size increase even when enabling adjustment of damping force, and to provide a damper.SOLUTION: A damping valve V includes: a piston 5 having a valve seat 5d erected from an outer periphery of an opening end of a port 5b and enclosing the port 5b; an annular leaf valve 17 which is overlapped with the piston 5 and may be seated on or separated from a valve seat 5e; a facing member 12 which is disposed at the non-valve seat member side of the leaf valve 17, spaced apart from and facing the leaf valve 17; a biasing member 16 disposed between the leaf valve 17 and the facing member 12 and having a magnetic viscosity elastomer which biases the leaf valve 17 toward the valve seat 5e; and a coil 10 which causes a magnetic field to act on the biasing member 16.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a damping valve and a shock absorber. [Background technology]

[0002] Damping valves are used in shock absorbers used in vehicle suspensions, etc., and some damping valves allow adjustment of the damping force generated by the shock absorber. Such damping valves include, for example, a valve seat member having a port, a valve disc that opens and closes the port by seating on and off the valve seat member, a spring that urges the valve disc toward the valve seat member, and a solenoid that applies a thrust to the valve disc that counteracts the urging force of the spring, and the thrust acting on the valve disc is changed by adjusting the amount of current supplied to the solenoid, thereby changing the valve opening pressure and the degree of valve opening.

[0003] A shock absorber that uses such a damping valve includes, for example, a cylinder, a piston that is inserted into the cylinder and divides the cylinder into an extension-side chamber and a compression-side chamber that are filled with hydraulic oil, a piston rod that is inserted into the cylinder and connected to the piston, an outer cylinder that covers the cylinder, an intermediate cylinder that is arranged between the cylinder and the outer cylinder, a reservoir that is formed by an annular gap between the intermediate cylinder and the outer cylinder, a damping passage that is formed by the gap between the cylinder and the intermediate cylinder and that connects the extension-side chamber and the reservoir, a rectification passage that is provided in the piston and that allows hydraulic oil to flow only from the compression-side chamber to the extension-side chamber, and a suction passage that allows hydraulic oil to flow only from the reservoir to the compression-side chamber, and the damping valve is provided midway in the damping passage of the shock absorber.

[0004] In a shock absorber configured as described above, hydraulic oil is pushed out from the cylinder into the reservoir and passes through the damping valve when the shock absorber extends or retracts, so the damping force when the shock absorber extends or retracts can be adjusted by changing the valve opening pressure or degree of valve opening in the damping valve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-55571 Summary of the Invention [Problem to be solved by the invention]

[0006] However, since the aforementioned shock absorber is equipped with a damping valve equipped with a solenoid, the solenoid is installed so that it protrudes from the side of the outer cylinder, which increases the size of the shock absorber and the number of parts, resulting in higher manufacturing costs.

[0007] Furthermore, as disclosed in Patent Publication No. 2021-027143, there are shock absorbers in which a damping valve equipped with a solenoid is provided in the piston portion inside the cylinder, but this results in the piston portion becoming longer in both the radial and axial directions, making it difficult to ensure the stroke length of the shock absorber, leading to an increase in the outer diameter and an increase in the number of parts, which increases manufacturing costs.

[0008] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a damping valve and a shock absorber that allow adjustment of the damping force without increasing the size and suppressing increases in manufacturing costs. [Means for solving the problem]

[0009] In order to achieve the above object, the damping valve of the present invention comprises a valve seat member having a port and a valve seat that rises from the outer periphery of the open end of the port and surrounds the port, an annular leaf valve that is overlaid on the valve seat member and can be seated on and removed from the valve seat, an opposing member that is arranged on the opposite side of the leaf valve from the valve seat member and faces the leaf valve, a biasing member that is interposed between the leaf valve and the opposing member and has a magnetorheological elastomer that biases the leaf valve toward the valve seat, and a coil that applies a magnetic field to the biasing member.

[0010] The damping valve configured in this way employs a structure in which the leaf valve is biased by a biasing member having a magnetorheological elastomer whose elasticity can be changed by the action of a magnetic field, thereby enabling adjustment of the damping force. Furthermore, since the only parts required for adjusting the damping force are the biasing member and the coil, it is not only smaller than a large solenoid that has a fixed iron core, a movable iron core, and a spring in addition to the coil, but also requires fewer parts, so the damping valve can be installed in the piston section or base valve section of the shock absorber.

[0011] The damping valve may also include an axial member to which a valve seat member and an opposing member are attached, the leaf valve may be annular and its inner circumferential side may be fixed between the valve seat member of the axial member and the opposing member to allow deflection on the outer circumferential side, and the biasing member may be provided between the outer circumferential side of the leaf valve and the opposing member.

[0012] With a damping valve configured in this manner, unlike a general damping valve structure that is equipped with a leaf valve and a valve stopper and does not allow for damping force adjustment, damping force adjustment is possible simply by providing a coil and interposing a biasing member between the leaf valve and the valve stopper, so that a damping force adjustment function can be provided inexpensively and easily to a damping valve that does not allow for damping force adjustment.Furthermore, by fixing the leaf valve to the outer periphery of the shaft member, the bending direction of the leaf valve can be controlled, making it easier to align the biasing force of the biasing member with the bending direction of the leaf valve.

[0013] Furthermore, the damping valve may include a shaft member to which the valve seat member and the opposing member are attached, and a valve retainer member that is disposed between the leaf valve and the opposing member, is movable in the axial direction relative to the shaft member, and abuts on the side of the leaf valve opposite the valve seat member, and the biasing member is interposed between the opposing member and the valve retainer member and biases the leaf valve via the valve retainer member. Also, since the valve retainer member is movably provided on the outer periphery of the shaft member, the biasing force of the biasing member can be applied to the leaf valve in the axial direction via the valve retainer member, thereby efficiently suppressing deflection of the leaf valve.

[0014] With a damping valve configured in this manner, damping force adjustment is possible simply by providing a coil and interposing a biasing member between the leaf valve and the opposing member in place of a spring, as opposed to a damping valve structure that has a spring between the leaf valve and the opposing member and does not allow for damping force adjustment.This means that a damping force adjustment function can be added cheaply and easily to a damping valve that does not allow for damping force adjustment.

[0015] Furthermore, the valve seat member and the opposing member in the damping valve may be formed of a soft magnetic material. With this damping valve configured in this way, the valve seat member and the opposing member form a magnetic circuit that allows the magnetic field generated by the coil to act efficiently on the biasing member, making it possible to adjust the damping force with little power.

[0016] Furthermore, the shock absorber of the present invention includes a shock absorber body having an outer shell, a rod inserted into the outer shell so as to be axially movable, and two working chambers through which fluid flows as the rod moves relative to the outer shell, and a damping valve provided between the working chambers. A shock absorber configured in this manner includes a damping valve that can be manufactured inexpensively, thereby reducing costs. [Effects of the Invention]

[0017] According to the valve and shock absorber of the present invention, even if the damping force can be adjusted, the size is not increased and an increase in manufacturing costs can be suppressed. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view of a shock absorber to which a damping valve according to an embodiment is applied; [Figure 2] 1 is an enlarged cross-sectional view of a piston portion to which a damping valve according to an embodiment is applied; [Figure 3] FIG. 10 is an enlarged cross-sectional view of a piston portion to which a damping valve according to a first modified example of one embodiment is applied. [Figure 4] FIG. 10 is an enlarged cross-sectional view of a piston portion to which a damping valve according to a first modified example of one embodiment is applied. DETAILED DESCRIPTION OF THE INVENTION

[0019] The valve and shock absorber of the present invention will be described below with reference to the drawings. The damping valve V in one embodiment is used as a damping valve for the piston part of a shock absorber D, as shown in FIG.

[0020] Below, we will explain in detail the damping valve V and each part of the shock absorber D. The shock absorber D includes a shock absorber main body 1 having an outer shell 2 and a rod 3 inserted into the outer shell 2 so as to be axially movable, and a damping valve V provided between an extension-side chamber R1 and a compression-side chamber R2 as two working chambers formed in the shock absorber main body 1.

[0021] The shock absorber body 1 includes a cylinder 4, a piston 5 that is movably inserted into the cylinder 4 and divides the interior of the cylinder 4 into an extension-side chamber R1 and a compression-side chamber R2, a rod 3 that is inserted into the cylinder 4 and connected to the piston 5, and an outer shell 2 that covers the cylinder 4 and forms a reservoir chamber R between the cylinder 4 and the outer shell 2.

[0022] The cylinder 4 is cylindrical, and the piston 5 is inserted therein so as to be free to move, as described above. An expansion-side chamber R1 is defined above the piston 5 in FIG. 1, and a compression-side chamber R2 is defined below the piston 5 in FIG. 1. The expansion-side chamber R1 and the compression-side chamber R2 are filled with a liquid, specifically, hydraulic oil, for example. Note that the liquid may be water, an aqueous solution, or the like, in addition to hydraulic oil.

[0023] The cylinder 4 is housed in a cylindrical outer shell 2 with a bottom that is disposed on the outer periphery, and a reservoir chamber R is formed in the annular gap between the cylinder 4 and the outer shell 2. In this case, the reservoir chamber R is filled with hydraulic oil and gas, and when liquid is used as the hydraulic oil, it is preferable to use an inert gas such as nitrogen as the gas to prevent deterioration of the hydraulic oil.

[0024] A valve case 6 is fitted to the lower end of the cylinder 4 in FIG. 1, and the valve case 6 separates the compression-side chamber R2 from the reservoir chamber R. A rod guide 8 that slidably supports the rod 3 is fitted to the upper end of the cylinder 4 in FIG. 1. The rod guide 8 is fitted to the inner periphery of the outer shell 2, and is fixed to the outer shell 2 by crimping the upper end of the outer shell 2, stacked above the rod guide 8 in FIG. 1. When the rod guide 8 is fixed to the outer shell 2 in this manner, the cylinder 4 is sandwiched between the valve case 6 placed on the bottom of the outer shell 2 and the rod guide 8, and the cylinder 4 and the valve case 6 are fixed within the outer shell 2. Note that instead of crimping the upper open end of the outer shell 2, a cap may be screwed onto the upper open end, and the rod guide 8, cylinder 4, and valve case 6 may be sandwiched between the cap and the bottom of the outer shell 2 to fix these components within the outer shell 2.

[0025] 1, the rod 3 is made of a soft magnetic material and includes a small-diameter portion 3a at its lower end, the outer diameter of which is smaller than that of its upper portion, an annular recess 3b provided circumferentially on the outer periphery of the small-diameter portion 3a, a threaded portion 3c provided on the outer periphery of the lowest end of the small-diameter portion 3a, and a step 3d formed between the small-diameter portion 3a and a portion above the small-diameter portion 3a. The rod 3 is cylindrical, with the lower end of the small-diameter portion 3a closed, and includes a hole 3e that connects the inside of the rod 3 to the annular recess 3b.

[0026] A coil 10 is housed in an annular recess 3b formed in the small diameter portion 3a of the rod 3, and current can be supplied to the coil 10 from a power source (not shown) located outside the shock absorber D via a cord 11 inserted into the rod 3.

[0027] An annular valve stopper 12 made of a soft magnetic material, a cylindrical collar 13 made of a non-magnetic material, an annular spacer 14 made of a non-magnetic material, a compression-side leaf valve 15 as a leaf valve, a compression-side biasing member 16 as a biasing member, the piston 5 as a valve seat member, an extension-side leaf valve 17 as a leaf valve, an extension-side biasing member 18 as a biasing member, an annular spacer 19 made of a non-magnetic material, and an annular valve stopper 20 made of a soft magnetic material are fitted in this order onto the outer periphery of the small diameter portion 3a of the rod 3. The valve stopper 12, the collar 13, the spacer 14, the compression-side leaf valve 15, the piston 5, the extension-side leaf valve 17, the spacer 19, and the valve stopper 20 are sandwiched between a piston nut 21 threaded onto a threaded portion 3c of the small diameter portion 3a and a step portion 3d of the rod 3, and are fixed to the small diameter portion 3a. The compression-side biasing member 16 is interposed between the compression-side leaf valve 15 and the valve stopper 12 , and the expansion-side biasing member 18 is interposed between the expansion-side leaf valve 17 and the valve stopper 20 .

[0028] The valve stopper 12, which is located closer to the extension-side chamber than the piston 5, is made of a soft magnetic material, has an annular shape, is thicker on its inner periphery than its outer periphery, and has a protrusion 12a that protrudes downward in FIG. 1, where the inner periphery is closer to the piston. The valve stopper 20, which is located closer to the compression-side chamber than the piston 5, is made of a soft magnetic material, is thicker on its inner periphery than its outer periphery, and has a protrusion 20a that protrudes upward in FIG. 1, where the inner periphery is closer to the piston. The valve stopper 20 may be provided integrally with the piston nut 21.

[0029] The collar 13 is formed from a non-magnetic tube and is interposed between the valve stoppers 12 and 20. It is sandwiched between the step portion 3d of the rod 3 and the piston nut 21 and is fixed immovably to the outer periphery of the rod 3 together with the valve stoppers 12 and 20.

[0030] Spacer 14 is annular and made of a non-magnetic material, and is fitted onto the outer periphery of collar 13 and overlaps the lower part of valve stopper 12 in Figure 1. Spacer 19 is annular and made of a non-magnetic material, and is fitted onto the outer periphery of collar 13 and overlaps the upper part of valve stopper 20 in Figure 1. Spacers 14 and 19 are made of a single annular plate, but may be made of multiple annular plates.

[0031] The piston 5 is made of a soft magnetic material and is annular, and as shown in Fig. 2, it serves as a valve seat member in the damping valve V and is fitted onto the outer periphery of a collar 13 attached to the outer periphery of the small diameter portion 3a of the rod 3 serving as a shaft member. The small diameter portion 3a fitted with the collar 13 is inserted into the inner periphery of the piston 5, and the small diameter portion 3a of the rod 3 protrudes downward in Fig. 1 from the lower end of the piston 5 and functions as a shaft member.

[0032] In this embodiment, the piston 5 serving as a valve seat member includes an annular piston body 5a, a plurality of extension-side ports 5b and compression-side ports 5c arranged alternately on the same circumference of the piston body 5a and penetrating the piston body 5a in the axial direction, a petal-shaped extension-side valve seat 5d protruding axially from the lower end of the piston body 5a in Fig. 1 and surrounding only the extension-side port 5b, and a petal-shaped compression-side valve seat 5e protruding axially from the upper end of the piston body 5a in Fig. 1 and surrounding only the compression-side port 5c. A resin piston ring 22 that is in sliding contact with the inner circumference of the cylinder 4 is attached to the outer periphery of the piston 5, and the piston 5 is movable up and down within the cylinder 4 in Fig. 1, dividing the interior of the cylinder 4 into an extension-side chamber R1 and a compression-side chamber R2.

[0033] As described above, the piston 5 is provided with a plurality of expansion-side ports 5b and a plurality of compression-side ports 5c, which are arranged on the same circumference of the piston 5 centered at the center of the piston 5. The number of expansion-side ports 5b and compression-side ports 5c to be provided is arbitrary, and there may be only one.

[0034] Furthermore, the expansion-side valve seat 5d is a petal-shaped valve seat that surrounds only the outlet ends of the expansion-side ports 5b without communicating with each other, avoiding the outlet ends of the compression-side ports 5c, and the compression-side valve seat 5e is a petal-shaped valve seat that surrounds only the outlet ends of the compression-side ports 5c without communicating with each other, avoiding the outlet ends of the expansion-side ports 5b. Note that when the expansion-side ports 5b and the compression-side ports 5c are provided at an angle with respect to the axial direction of the piston body 5a, and the compression-side port 5c opens more radially outward than the expansion-side port 5b on the expansion-side chamber R1 side of the piston body 5a, and the expansion-side port 5b opens more radially outward than the compression-side port 5c on the compression-side chamber R2 side of the piston body 5a, both the expansion-side valve seat 5d and the compression-side valve seat 5e may be annular valve seats.

[0035] The compression-side leaf valve 15 is an annular plate made of a non-magnetic material, fitted onto the outer periphery of the collar 13, and overlapped so as to seat on the compression-side valve seat 5e on the expansion-side chamber side of the piston 5 as a valve seat member. The inner periphery is sandwiched and fixed between the piston 5 and the spacer 14, and is allowed to deflect on the outer periphery. When the outer periphery of the compression-side leaf valve 15 is seated on the compression-side valve seat 5e of the piston 5, it closes the upper end in FIG. 1, which is the outlet end of the compression-side port 5c. When the outer periphery of the compression-side leaf valve 15 is deflected upward in FIG. 2 and separated from the compression-side valve seat 5e, it opens the compression-side port 5c. Although the compression-side leaf valve 15 is illustrated as being made up of a single annular plate, it may be made up of multiple annular plates, in which case the outer diameters of the annular plates may be different.

[0036] 2 , which is the side opposite to the valve seat member of the compression-side leaf valve 15, the valve stopper 12, which serves as an opposing member opposing the compression-side leaf valve 15, is arranged on the side opposite to the valve seat member of the compression-side leaf valve 15 at a distance equal to the height of the spacer 14. When the compression-side leaf valve 15 bends and comes into contact with the outer periphery of the compression-side leaf valve 15, the valve stopper 12 restricts further bending of the compression-side leaf valve 15, thereby suppressing plastic deformation of the compression-side leaf valve 15.

[0037] The extension-side leaf valve 17 is an annular plate made of a non-magnetic material, fitted onto the outer periphery of the collar 13, and overlapped so as to seat on the extension-side valve seat 5d on the compression-side chamber side of the piston 5 as a valve seat member. The inner periphery is sandwiched and fixed between the piston 5 and a spacer 19, and is allowed to deflect on the outer periphery. When the outer periphery of the extension-side leaf valve 17 is seated on the extension-side valve seat 5d of the piston 5, it closes the lower end in FIG. 1, which is the outlet end of the extension-side port 5b. When the outer periphery of the extension-side leaf valve 17 is deflected downward in FIG. 2 and separated from the extension-side valve seat 5d, it opens the extension-side port 5b. Although the extension-side leaf valve 17 is shown as being made up of a single annular plate, it may be made up of multiple annular plates, in which case the outer diameters of the annular plates may be different.

[0038] 2 , which is the side opposite to the valve seat member of the extension side leaf valve 17, the valve stopper 20, which serves as an opposing member opposing the extension side leaf valve 17, is arranged at a distance equal to the height of the spacer 19 on the side opposite to the valve seat member of the extension side leaf valve 17. When the extension side leaf valve 17 bends and comes into contact with the outer periphery of the extension side leaf valve 17, the valve stopper 20 restricts further bending of the extension side leaf valve 17, thereby suppressing plastic deformation of the extension side leaf valve 17.

[0039] The compression-side biasing member 16 is annular and made of a magnetorheological elastomer, and is elastic. When a magnetic field is applied, its elastic modulus changes depending on the magnitude of the applied magnetic field. The compression-side biasing member 16 is fitted onto the outer periphery of the protrusion 12a of the valve stopper 12 to determine its radial position. Its axial length is set to be equal to or longer than the axial length of the spacer 14, and it is interposed in a compressed state between the valve stopper 12 and the compression-side leaf valve 15. Therefore, the compression-side biasing member 16 constantly biases the compression-side leaf valve 15 toward the piston 5 by the elastic force it generates.

[0040] The expansion-side biasing member 18 is annular and made of a magnetorheological elastomer, and has elasticity and a modulus of elasticity that changes according to the magnitude of the applied magnetic field. The expansion-side biasing member 18 is fitted onto the outer periphery of the protrusion 20a of the valve stopper 20 to determine its radial position, and its axial length is set to be equal to or longer than the axial length of the spacer 19. The expansion-side biasing member 18 is interposed in a compressed state between the valve stopper 20 and the expansion-side leaf valve 17. Therefore, the expansion-side biasing member 18 constantly biases the expansion-side leaf valve 17 toward the piston 5 by the elastic force it generates.

[0041] It is sufficient that the compression side biasing member 16 and the extension side biasing member 18 as biasing members are able to bias the corresponding compression side leaf valves 15 and extension side leaf valves 17 using a magnetorheological elastomer. Therefore, the entire compression side biasing member 16 and the extension side biasing member 18 may be made of a magnetorheological elastomer, or a portion of the compression side biasing member 16 and the extension side biasing member 18 may include a magnetorheological elastomer that can bias the compression side leaf valve 15 and the extension side leaf valve 17.

[0042] When current is applied to the coil 10 attached to the outer periphery of the small diameter portion 3a of the rod 3, the small diameter portion 3a, the valve stopper 12, the piston 5, and the valve stopper 20 are made of soft magnetic materials, and the spacers 14, 19 and the collar 13 are made of non-magnetic materials, so that magnetic field lines emitted from the coil 10 pass through the valve stopper 12, the compression-side biasing member 16, the piston 5, the extension-side biasing member 18, and the valve stopper 20 and return to the coil 10. The valve stopper 12, the piston 5, and the valve stopper 20 form a magnetic circuit, and when current is applied to the coil 10, a magnetic field can be efficiently applied to the compression-side biasing member 16 and the extension-side biasing member 18. Furthermore, the strength of the magnetic field applied to the compression-side biasing member 16 and the extension-side biasing member 18 can be adjusted by adjusting the amount of current applied to the coil 10, so that the elastic moduli of the compression-side biasing member 16 and the extension-side biasing member 18 can be increased or decreased by adjusting the amount of current applied to the coil 10. When the elastic modulus of the compression-side biasing member 16 and the expansion-side biasing member 18 changes, the biasing force applied by the compression-side biasing member 16 to the compression-side leaf valve 15 and the biasing force applied by the expansion-side biasing member 18 to the expansion-side leaf valve 17 change. Therefore, by adjusting the amount of current applied to the coil 10, the apparent bending rigidity of the compression-side leaf valve 15 and the expansion-side leaf valve 17 can be adjusted.

[0043] The damping valve V includes a piston 5 as a valve seat member having an extension side port 5b, a compression side port 5c, an extension side valve seat 5d surrounding the extension side port 5b, and a compression side valve seat 5e surrounding the compression side port 5c, an extension side leaf valve 17 superimposed on the piston 5 and separable from the extension side valve seat 5d, a compression side leaf valve 15 superimposed on the piston 5 and separable from the compression side valve seat 5e, a valve stopper 20 as an opposing member disposed on the opposite side of the valve seat member from the extension side leaf valve 17 at a distance and facing the extension side leaf valve 17, and a compression side leaf valve 15 as an opposing member disposed on the opposite side of the valve seat member from the compression side leaf valve 15 at a distance. the spring 15 is configured with a valve stopper 12 as an opposing member facing the spring 15; a biasing member 18 having a magnetorheological elastomer interposed between the extension-side leaf valve 17 and the valve stopper 20 and biasing the extension-side leaf valve 17 toward the extension-side valve seat 5d; a biasing member 16 having a magnetorheological elastomer interposed between the compression-side leaf valve 15 and the valve stopper 12 and biasing the compression-side leaf valve 15 toward the compression-side valve seat 5e; a coil 10 that applies a magnetic field to the extension-side biasing member 18 and the compression-side biasing member 16; and a small-diameter portion 3a as an axial member of the rod 3 that rises from the axial center of the piston 5.

[0044] Next, the valve case 6 is fitted to the lower end of the cylinder 4 to separate a compression side chamber R2 within the cylinder 4 from a reservoir chamber R formed between the cylinder 4 and the outer shell 2. The valve case 6 is equipped with a compression side damping passage 6a and a suction passage 6b that communicate between the compression side chamber R2 and the reservoir chamber R. A compression side valve 23 that opens and closes the compression side damping passage 6a and provides resistance to the flow of hydraulic oil passing through the compression side damping passage 6a is provided at the reservoir chamber side end, which is the lower end of the valve case 6 in FIG. 1, and a check valve 24 that opens and closes the suction passage 6b to allow hydraulic oil to flow through the suction passage 6b only from the reservoir chamber R to the compression side chamber R2 is provided at the compression side chamber side end, which is the upper end of the valve case 6 in FIG. 1.

[0045] The shock absorber D is configured as described above, and operation of the shock absorber D will be described below. First, when the rod 3 moves upward in FIG. 1 relative to the cylinder 4 and the shock absorber D extends, the piston 5 also moves upward together with the rod 3 relative to the cylinder 4, compressing the expansion-side chamber R1 and expanding the contraction-side chamber R2. As the expansion-side chamber R1 is compressed, the pressure in the expansion-side chamber R1 increases, and the expansion-side leaf valve 17 in the damping valve V is pressed by the pressure of the expansion-side chamber R1 acting through the expansion-side port 5b. When the force pressing the expansion-side leaf valve 17 downward in FIG. 2 due to the pressure in the expansion-side chamber R1 exceeds the biasing force of the expansion-side biasing member 18, the expansion-side leaf valve 17 bends, opening the expansion-side port 5b and providing resistance to the flow of hydraulic oil passing through the expansion-side port 5b. In this way, when the shock absorber D is extended, the extension-side leaf valve 17 applies resistance to the flow of hydraulic oil, so the pressure in the extension-side chamber R1 becomes higher than the pressure in the compression-side chamber R2, and the shock absorber D generates a damping force that suppresses the extension operation. Note that when the shock absorber D is extended, the compression-side leaf valve 15 is maintained in a state where it is seated on the compression-side valve seat 5e by the pressure in the extension-side chamber R1 and the biasing force of the compression-side biasing member 16, so the compression-side port 5c is blocked and the hydraulic oil does not pass through the compression-side port 5c.

[0046] In the damping valve V of this embodiment, the apparent flexural rigidity of the extension-side leaf valve 17 can be changed by adjusting the amount of current supplied to the coil 10, so that the damping force generated when the shock absorber D is extended can be adjusted to a high or low level.

[0047] Furthermore, when shock absorber D extends, rod 3 retracts from cylinder 4, causing a shortage of hydraulic oil in cylinder 4 to compensate for the volume of hydraulic oil retracted by rod 3. However, check valve 24 provided in valve case 6 opens and supplies this shortage of hydraulic oil from reservoir chamber R into cylinder 4. The opening pressure of check valve 24 is set very low to prevent the pressure inside cylinder 4 from dropping below atmospheric pressure.

[0048] Next, when the rod 3 moves downward relative to the cylinder 4 in FIG. 1 and the shock absorber D contracts, the piston 5 also moves downward relative to the cylinder 4 together with the rod 3, compressing the compression-side chamber R2 and expanding the extension-side chamber R1. As the compression-side chamber R2 compresses, the pressure in the compression-side chamber R2 increases, and the compression-side leaf valve 15 in the damping valve V is pressed by the pressure of the compression-side chamber R2 acting through the compression-side port 5c. When the force exerted upward in FIG. 2 by the pressure in the compression-side chamber R2 exceeds the biasing force of the compression-side biasing member 16, the compression-side leaf valve 15 bends, opening the compression-side port 5c and providing resistance to the flow of hydraulic oil passing through the compression-side port 5c. Furthermore, when the shock absorber D contracts, the hydraulic oil in the cylinder 4 becomes excessive by the volume of the rod 3 entering the cylinder 4, and the excess hydraulic oil moves to the reservoir chamber R via the compression-side damping passage 6a and the compression-side valve 23. In this way, when the shock absorber D is contracting, the compression-side leaf valve 15 and the compression-side valve 23 provide resistance to the flow of hydraulic oil, so the pressure in the compression-side chamber R2 becomes higher than the pressure in the extension-side chamber R1, and the shock absorber D generates a damping force that suppresses the extension operation. Note that when the shock absorber D is contracting, the expansion-side leaf valve 17 is maintained in a state of being seated on the expansion-side valve seat 5d by the pressure in the compression-side chamber R2 and the biasing force of the expansion-side biasing member 18, so the expansion-side port 5b is blocked and the hydraulic oil does not pass through the expansion-side port 5b.

[0049] In the damping valve V of this embodiment, the apparent flexural rigidity of the compression side leaf valve 15 can be changed by adjusting the amount of current supplied to the coil 10, so that the damping force generated when the shock absorber D is contracting can be adjusted to a high or low level.

[0050] As described above, the damping valve V comprises a piston (valve seat member) 5 having an extension side port 5b and a compression side port 5c, and extension side valve seats 5d and 5e rising from the outer peripheries of the open ends of the extension side port 5b and the compression side port 5c and surrounding the extension side port 5b and the compression side port 5c, an annular extension side leaf valve 17 and a compression side leaf valve 15 overlapping the piston (valve seat member) 5 and being able to seat and retract on the extension side valve seat 5d and the compression side valve seat 5e, and an annular extension side leaf valve 17 and a compression side leaf valve 15 arranged at intervals on the opposite side of the valve seat member from the extension side leaf valve 17 and the compression side leaf valve 15. The valve stoppers (opposing members) 12, 20 are positioned opposite the extension side leaf valve 17 and the compression side leaf valve 15, respectively; an extension side biasing member 18 and a compression side biasing member 16 are interposed between the extension side leaf valve 17 and the compression side leaf valve 15 and the valve stoppers (opposing members) 12, 20 and have a magnetorheological elastomer for biasing the extension side leaf valve 17 and the compression side leaf valve 15 toward the extension side valve seat 5d and the compression side valve seat 5e, respectively; and a coil 10 that applies a magnetic field to the extension side biasing member 18 and the compression side biasing member 16.

[0051] The damping valve V configured in this manner can adjust the damping force by adopting a structure in which the extension-side biasing member 18 and the compression-side biasing member 16 have a magnetorheological elastomer whose elasticity can be changed by the action of a magnetic field, and bias the extension-side leaf valve 17 and the compression-side leaf valve 15. Furthermore, the parts required to adjust the damping force are the extension-side biasing member 18, the compression-side biasing member 16, and the coil 10. Therefore, not only is the damping valve V smaller than a large solenoid that has a fixed iron core, a movable iron core, and a spring in addition to the coil, but the number of parts is also reduced, and therefore the damping valve V can be installed in the piston portion of the shock absorber D. Therefore, the damping valve V of this embodiment does not require an increase in size even though the damping force is adjustable, and an increase in manufacturing costs can be suppressed.

[0052] The expansion-side biasing member 18 and the compression-side biasing member 16 may both be annular, or may be composed of a plurality of columnar or arc-shaped magnetorheological elastomers in an axial view arranged in a circumferential direction between the valve stoppers 12, 20 and the leaf valves 15, 17. In this case, when each magnetorheological elastomer constituting the expansion-side biasing member 18 is provided at a position axially facing the open end of the expansion-side port 5b with respect to the expansion-side leaf valve 17, the apparent flexural rigidity of the expansion-side leaf valve 17 can be efficiently adjusted, and when each magnetorheological elastomer constituting the compression-side biasing member 16 is provided at a position axially facing the open end of the compression-side port 5c with respect to the compression-side leaf valve 15, the apparent flexural rigidity of the compression-side leaf valve 15 can be efficiently adjusted. The shapes of the magnetorheological elastomers included in the expansion-side biasing member 18 and the compression-side biasing member 16 can be arbitrarily modified as long as the magnetorheological elastomers can bias the leaf valves 15, 17 and the biasing force can be adjusted by the amount of current supplied to the coil 10. Furthermore, when the expansion-side biasing member 18 is held by the valve stopper 20 as the opposing member, or when the compression-side biasing member 16 is held by the valve stopper 12 as the opposing member, the shapes of the valve stoppers 12, 20 can be appropriately modified in accordance with the shapes of the corresponding expansion-side biasing member 18 and compression-side biasing member 16. Therefore, for example, holes may be formed in the valve stoppers 12, 20, and the compression-side biasing member 16 and the expansion-side biasing member 18 may be fitted into the holes to hold the compression-side biasing member 16 and the expansion-side biasing member 18 in the valve stoppers 12, 20.

[0053] In order to enable adjustment of the damping force during both the extension operation and the contraction operation of the shock absorber D, the damping valve V of this embodiment is provided with an extension-side leaf valve 17, a valve stopper 20, and an extension-side biasing member 18 interposed between the extension-side leaf valve 17 and the valve stopper 20, as well as a compression-side leaf valve 15, a valve stopper 12, and a compression-side biasing member 16 interposed between the compression-side leaf valve 15 and the valve stopper 12. If the damping force is to be adjusted only during the extension operation of the shock absorber D, the compression-side biasing member 16 may be eliminated, and if the damping force is to be adjusted only during the contraction operation of the shock absorber D, the extension-side biasing member 18 may be eliminated.

[0054] In addition, the damping valve V may be configured by using the valve case 6 as a valve seat member, placing a leaf valve on the valve seat surrounding the compression side damping passage 6a of the valve case 6, and arranging an opposing member opposite the leaf valve with a gap therebetween, and interposing a biasing member having a magnetorheological elastomer between the leaf valve and the opposing member, and installing a coil that applies a magnetic field to the biasing member.

[0055] The shock absorber D includes an outer shell 2, a rod 3 inserted axially within the outer shell 2 so as to be movable, a shock absorber main body 1 having an extension-side chamber (working chamber) R1 and a compression-side chamber (working chamber) R2 through which hydraulic oil (liquid) flows as the rod 3 moves relative to the outer shell 2, and a damping valve V provided between the extension-side chamber (working chamber) R1 and the compression-side chamber (working chamber) R2. The shock absorber D configured in this manner includes an inexpensive and compact damping valve V, and therefore does not increase in size even though the damping force is adjustable, thereby making it possible to suppress an increase in manufacturing costs.

[0056] In this embodiment, the piston 5 serves as the valve seat member and the damping valve V is installed in the piston portion of the shock absorber D, but the valve case 6 of the shock absorber D may serve as the valve seat member and the damping valve V may be installed between the compression side chamber R2 and the reservoir chamber R as two working chambers. In other words, the damping valve V may be installed in the base valve portion of the shock absorber D. In this way, by being installed between the two working chambers formed in the shock absorber D, the damping valve V can function as a damping force generation source in the shock absorber D and can adjust the damping force.

[0057] The shock absorber D is a twin-tube shock absorber that has a cylinder 4 inside the outer shell 2, the inside of the cylinder 4 divided into an extension-side chamber R1 and a compression-side chamber R2 by a piston 5, and a reservoir chamber R between the cylinder 4 and the outer shell 2. However, the shock absorber may be a mono-tube shock absorber in which the cylinder 4 is eliminated and a piston connected to a rod 3 is slidably inserted into the inner periphery of the outer shell 2. The mono-tube shock absorber D in this manner has two working chambers, an extension-side chamber and a compression-side chamber, so the damping valve V may be provided in the piston portion of the shock absorber D. The installation location of the damping valve changes depending on the configuration of the shock absorber D, but the damping valve V may be installed in an optimal location depending on the configuration of the shock absorber D.

[0058] Furthermore, in the damping valve V of this embodiment, the piston (valve seat member) 5 and the valve stoppers (opposing members) 12, 20, which are positioned so as to sandwich the biasing members 16, 18 in the axial direction, are formed of a soft magnetic material, and the piston (valve seat member) 5 and the valve stoppers (opposing members) 12, 20 form a magnetic circuit that allows the magnetic field generated by the coil 10 to act efficiently on the biasing members 16, 18, making it possible to adjust the damping force with less power.

[0059] Furthermore, in the damping valve V of this embodiment, a non-magnetic collar 13 is disposed between the piston 5 serving as a valve seat member and the small-diameter portion 3a holding the coil 10. This allows a magnetic circuit to be formed that allows the magnetic field lines of the coil 10 to pass more efficiently through the valve stoppers 12, 20 and the piston 5. By providing the collar 13 in this manner, a magnetic field can be applied more efficiently by the extension-side biasing member 18 and the compression-side biasing member 16. However, it is also possible to eliminate the collar 13 and fit the piston 5 directly onto the outer periphery of the small-diameter portion 3a. Alternatively, the valve stoppers 12, 20 may be fitted onto the outer periphery of the collar 13 so that the piston nut 21 also forms a magnetic circuit. When the collar 13 is eliminated, the inner and outer periphery of the piston 5 may be formed as separate parts, with the inner periphery made of a non-magnetic material and the outer periphery made of a soft magnetic material. Examples of soft magnetic materials that can be used include iron or iron powder molded by sintering. In this way, the magnetic field lines of the coil 10 pass through the outer periphery of the piston 5, so that a magnetic field can be efficiently applied to the expansion-side biasing member 18 and the compression-side biasing member 16. Furthermore, the outer periphery of the piston 5, the expansion-side biasing member 18, and the compression-side biasing member 16 may be disposed at positions where they overlap in the axial direction of the rod 3. In this way, it is possible to reduce the deviation between the direction of the magnetic field generated by the coil 10 and passing through the magnetorheological elastomer in the expansion-side biasing member 18 and the compression-side biasing member 16 and the direction of the line of action of the load that the expansion-side biasing member 18 and the compression-side biasing member 16 receive from the leaf valves 15, 17, and therefore it is possible to widen the adjustment range of the biasing force that the expansion-side biasing member 18 and the compression-side biasing member 16 apply to the leaf valves 15, 17. Since the coil 10 is installed on the outer periphery of the small diameter portion 3a serving as the shaft member, electricity can be passed through the coil 10 by wiring arranged inside the rod 3, and the installation of the coil 10 is easy; however, the coil 10 may be installed at a location other than the outer periphery of the small diameter portion 3a, and may be held by a valve seat member, for example.

[0060] In addition, the damping valve V of this embodiment has a small diameter portion (shaft member) 3a to which a piston (valve seat member) 5 and a valve stopper (opposing member) 12, 20 are attached, and the extension side leaf valve (leaf valve) 17 and the compression side leaf valve (leaf valve) 15 are annular and have their inner peripheral sides fixed between the piston (valve seat member) 5 of the small diameter portion (shaft member) 3a and the valve stopper (opposing member) 12, 20 to allow deflection on the outer peripheral side, and biasing members 16, 18 are provided between the outer peripheral sides of the extension side leaf valve (leaf valve) 17 and the compression side leaf valve (leaf valve) 15 and the valve stopper (opposing member) 12, 20. With the damping valve V configured in this manner, in contrast to the structure of a general damping valve that is equipped with a leaf valve and a valve stopper and does not allow for damping force adjustment, damping force adjustment is possible simply by providing the coil 10 and interposing the biasing member 16 (18) between the leaf valve 15 (17) and the valve stopper 12 (20), so that a damping force adjustment function can be provided inexpensively and easily to a damping valve that does not allow for damping force adjustment. Also, by fixing the leaf valve 15 (17) to the outer periphery of the small diameter portion (shaft member) 3 a, the bending direction of the leaf valve 15 (17) can be controlled, so that the biasing force of the biasing member 16 (18) can easily be made to act in the same direction as the bending direction of the leaf valve 15 (18).

[0061] The damping valve V1 may also be configured as the damping valve V1 of the first modified example of the embodiment shown in Fig. 3. The configuration of the damping valve V1 of the first modified example will be described below, but since the explanation of the same members as those of the damping valve V of the embodiment will be repeated, the same reference numerals will be used and detailed explanations will be omitted. The damping valve V1 of the first modified example is provided in the piston portion of the shock absorber D, and the other configurations of the shock absorber D are the same as those described above.

[0062] A damping valve V1 of a first modified example of an embodiment includes a piston 5 as a valve seat member, an extension-side leaf valve 17 and a compression-side leaf valve 15 that are seated on and retracted from an extension-side valve seat 5d and a compression-side valve seat 5e of the piston 5, opposing members 30 and 31 that are arranged at an opposite side of the valve seat member from the extension-side leaf valve 17 and the compression-side leaf valve 15 and that face the extension-side leaf valve 17 and the compression-side leaf valve 15 with a gap therebetween, a coil 10, a small-diameter portion 3a as an axial member of a rod 3 that rises from the piston 5, and a coil 10. a valve holding member 32 arranged between the opposing member 30 and the small diameter portion 3 a and movable in the axial direction around the outer periphery of the small diameter portion 3 a and abutting against the side of the extension-side leaf valve 17 opposite the valve seat member; a valve holding member 33 arranged between the compression-side leaf valve 15 and the opposing member 31 and movable in the axial direction around the outer periphery of the small diameter portion 3 a and abutting against the side of the compression-side leaf valve 15 opposite the valve seat member; an extension-side biasing member 34 interposed between the opposing member 30 and the valve holding member 32; and an extension-side biasing member 34 interposed between the opposing member 31 and the valve holding member 33.

[0063] The damping valve V1 is provided in the piston portion of the shock absorber D, similar to the damping valve V, and is assembled to the small diameter portion 3a of the rod 3 as a shaft member. On the outer periphery of the small diameter portion 3a of the rod 3, fitted in this order are an annular opposing member 31 made of a soft magnetic material, a cylindrical collar 36 made of a non-magnetic material, a cylindrical spacer 37 made of a non-magnetic material, a compression-side leaf valve 15 as a leaf valve, a compression-side biasing member 35 as a biasing member, a valve holding member 32, the piston 5 as a valve seat member, an extension-side leaf valve 17 as a leaf valve, a valve holding member 33, an extension-side biasing member 34 as a biasing member, and a cylindrical spacer 38 made of a non-magnetic material. The opposing member 31, collar 36, spacer 37, compression-side leaf valve 15, compression-side biasing member 35, valve holddown member 32, piston 5, extension-side leaf valve 17, valve holddown member 33, extension-side biasing member 34, and spacer 38 are sandwiched between the opposing member 30, which is made of a soft magnetic material and is screwed onto the threaded portion 3c of the small diameter portion 3a, and the stepped portion 3d of the rod 3, and are fixed to the small diameter portion 3a. In this way, the expansion-side biasing member 34 is interposed between the opposing member 30 and the valve holddown member 32 and biases the expansion-side leaf valve 17, and the compression-side biasing member 35 is interposed between the opposing member 31 and the valve holddown member 33.

[0064] The opposing member 31, which is located closer to the expansion-side chamber than the piston 5, is made of a soft magnetic material, is annular, has a thicker wall thickness on its inner periphery than on its outer periphery, and has a protrusion 31a that protrudes downward in FIG. 3, with the inner periphery being closer to the piston. The opposing member 30, which is located closer to the compression-side chamber than the piston 5, is made of a soft magnetic material, is annular, has a threaded groove on its inner periphery so as to function as a piston nut, has a flange 30a on its outer periphery, and has a protrusion 30b that protrudes upward in FIG. 3. The opposing member 30 may be separate from the piston nut and fixed immovably to the small diameter portion 3a.

[0065] The collar 36 is formed from a non-magnetic tube and is interposed between the opposing members 30 and 31. It is sandwiched between the step portion 3d of the rod 3 and the opposing member 30 and is fixed immovably to the outer periphery of the rod 3 together with the opposing members 30 and 31.

[0066] The spacer 37 is cylindrical and made of a non-magnetic material, and is fitted onto the outer periphery of the collar 36 and overlaps the lower part of the opposing member 31 in FIG. 3. The spacer 38 is annular and made of a non-magnetic material, and is fitted onto the outer periphery of the collar 36 and overlaps the upper part of the opposing member 30 in FIG. 3.

[0067] The compression-side leaf valve 15, the piston 5, and the extension-side leaf valve 17 are stacked in this order and fitted to the outer periphery of the collar 36, and their inner peripheries are sandwiched and fixed by spacers 37, 38. The compression-side leaf valve 15 is fixed at its inner periphery and allowed to flex at its outer periphery, and opens and closes the compression-side port 5c by coming into and out of contact with the compression-side valve seat 5e. The extension-side leaf valve 17 is fixed at its inner periphery and allowed to flex at its outer periphery, and opens and closes the extension-side port 5b by coming into and out of contact with the extension-side valve seat 5d.

[0068] 3, which is the side opposite the valve seat member of the compression-side leaf valve 15, a cylindrical valve holding member 33 having a flange on its outer periphery that abuts against the side opposite the valve seat of the compression-side leaf valve 15 is fitted onto the outer periphery of a collar 36 so as to be movable up and down. The valve holding member 33 is in sliding contact with the outer periphery of the collar 36, and therefore can move axially without axial wobble relative to the small diameter portion 3a, which serves as a shaft member with which the collar 36 is fitted.

[0069] 3, which is the side opposite to the valve seat member of the expansion-side leaf valve 17, a cylindrical valve holding member 32 having a flange on its outer periphery that abuts against the side opposite to the valve seat of the expansion-side leaf valve 17 is fitted to the outer periphery of a collar 36 so as to be movable up and down. The valve holding member 32 is in sliding contact with the outer periphery of the collar 36, and therefore can move axially without axial wobble relative to the small diameter portion 3a, which serves as a shaft member with which the collar 36 is fitted.

[0070] The compression-side biasing member 35 is annular and made of a magnetorheological elastomer, and is elastic. When a magnetic field is applied, its elastic modulus changes depending on the magnitude of the applied magnetic field. The compression-side biasing member 35 is fitted onto the outer periphery of the protrusion 31a of the opposing member 31 to determine its radial position. Its axial length is set to be equal to or longer than the axial length of the spacer 37, and it is interposed in a compressed state between the opposing member 31 and the valve holding member 33. Therefore, the compression-side biasing member 35 constantly biases the compression-side leaf valve 15 toward the piston 5 via the valve holding member 33 by the elastic force it generates.

[0071] The expansion-side biasing member 34 is annular and made of a magnetorheological elastomer, and has elasticity and a modulus of elasticity that changes according to the magnitude of the applied magnetic field when a magnetic field is applied. The expansion-side biasing member 34 is fitted onto the outer periphery of the protrusion 30b of the opposing member 30 to determine its radial position, and its axial length is set to be equal to or longer than the axial length of the spacer 38. The expansion-side biasing member 34 is interposed in a compressed state between the opposing member 30 and the valve holding member 32. Therefore, the expansion-side biasing member 34 constantly biases the expansion-side leaf valve 17 toward the piston 5 via the valve holding member 32 by the elastic force it generates.

[0072] In addition, since the compression side biasing member 35 and the extension side biasing member 34 as biasing members are only required to be able to bias the corresponding compression side leaf valves 15 and extension side leaf valves 17 using magnetorheological elastomer, they may be formed entirely from magnetorheological elastomer or may only partially have magnetorheological elastomer capable of biasing the compression side leaf valves 15 and extension side leaf valves 17.

[0073] When current is applied to the coil 10 attached to the outer periphery of the small diameter portion 3a of the rod 3, the small diameter portion 3a, the opposing member 31, the piston 5, and the opposing member 30 are made of soft magnetic materials, and the spacers 37, 38 and the collar 36 are made of non-magnetic materials, so that magnetic field lines emitted from the coil 10 pass through the opposing member 31, the compression-side biasing member 35, the piston 5, the extension-side biasing member 34, and the opposing member 30 and return to the coil 10. The opposing member 31, the piston 5, and the opposing member 30 form a magnetic circuit, and when current is applied to the coil 10, a magnetic field can be efficiently applied to the compression-side biasing member 35 and the extension-side biasing member 34. Furthermore, the strength of the magnetic field applied to the compression-side biasing member 35 and the extension-side biasing member 34 can be adjusted by adjusting the amount of current applied to the coil 10, so that the elastic moduli of the compression-side biasing member 35 and the extension-side biasing member 34 can be increased or decreased by adjusting the amount of current applied to the coil 10. When the elastic modulus of the compression-side biasing member 35 and the expansion-side biasing member 34 changes, the biasing force applied by the compression-side biasing member 35 to the compression-side leaf valve 15 and the biasing force applied by the expansion-side biasing member 34 to the expansion-side leaf valve 17 change. Therefore, by adjusting the amount of current applied to the coil 10, the valve opening pressure of the compression-side leaf valve 15 and the expansion-side leaf valve 17 can be adjusted.

[0074] Next, the operation of the shock absorber D equipped with the damping valve V1 of the first modified example will be described. First, when the rod 3 moves upward in FIG. 3 relative to the cylinder 4 and the shock absorber D extends, the piston 5 also moves upward together with the rod 3 relative to the cylinder 4, compressing the expansion-side chamber R1 and expanding the contraction-side chamber R2. As the expansion-side chamber R1 is compressed, the pressure in the expansion-side chamber R1 increases, and the expansion-side leaf valve 17 of the damping valve V1 is pressed by the pressure of the expansion-side chamber R1 acting through the expansion-side port 5b. When the force pressing the expansion-side leaf valve 17 downward in FIG. 3 due to the pressure in the expansion-side chamber R1 exceeds the biasing force of the expansion-side biasing member 34, the expansion-side leaf valve 17 bends, opening the expansion-side port 5b and providing resistance to the flow of hydraulic oil passing through the expansion-side port 5b. In this way, when the shock absorber D is extended, the extension-side leaf valve 17 applies resistance to the flow of hydraulic oil, so the pressure in the extension-side chamber R1 becomes higher than the pressure in the compression-side chamber R2, and the shock absorber D generates a damping force that suppresses the extension operation. Note that when the shock absorber D is extended, the pressure in the extension-side chamber R1 and the biasing force of the compression-side biasing member 35 keep the compression-side leaf valve 15 seated on the compression-side valve seat 5e, so the compression-side port 5c is blocked and the hydraulic oil does not pass through the compression-side port 5c.

[0075] In the damping valve V1 of this embodiment, the valve opening pressure of the extension-side leaf valve 17 can be changed by adjusting the amount of current supplied to the coil 10, so that the damping force generated when the shock absorber D is in an extension operation can be adjusted to a high or low level.

[0076] Furthermore, when shock absorber D extends, rod 3 retracts from cylinder 4, causing a shortage of hydraulic oil in cylinder 4 to compensate for the volume of hydraulic oil retracted by rod 3. However, check valve 24 provided in valve case 6 opens and supplies this shortage of hydraulic oil from reservoir chamber R into cylinder 4. The opening pressure of check valve 24 is set very low to prevent the pressure inside cylinder 4 from dropping below atmospheric pressure.

[0077] Next, when the rod 3 moves downward relative to the cylinder 4 in FIG. 3 and the shock absorber D contracts, the piston 5 also moves downward relative to the cylinder 4 together with the rod 3, compressing the compression-side chamber R2 and expanding the extension-side chamber R1. As the compression-side chamber R2 compresses, the pressure in the compression-side chamber R2 increases, and the compression-side leaf valve 15 in the damping valve V1 is pressed by the pressure of the compression-side chamber R2 acting through the compression-side port 5c. When the force exerted upward in FIG. 3 by the pressure in the compression-side chamber R2 exceeds the biasing force of the compression-side biasing member 35, the compression-side leaf valve 15 bends, opening the compression-side port 5c and providing resistance to the flow of hydraulic oil passing through the compression-side port 5c. Furthermore, when the shock absorber D contracts, the hydraulic oil in the cylinder 4 becomes excessive by the volume of the rod 3 entering the cylinder 4, and the excess hydraulic oil moves to the reservoir chamber R via the compression-side damping passage 6a and the compression-side valve 23. In this way, when the shock absorber D is contracting, the compression-side leaf valve 15 and the compression-side valve 23 provide resistance to the flow of hydraulic oil, so the pressure in the compression-side chamber R2 becomes higher than the pressure in the extension-side chamber R1, and the shock absorber D generates a damping force that suppresses the extension operation. Note that when the shock absorber D is contracting, the expansion-side leaf valve 17 is kept seated on the expansion-side valve seat 5d by the pressure in the compression-side chamber R2 and the biasing force of the expansion-side biasing member 34, so the expansion-side port 5b is blocked and the hydraulic oil does not pass through the expansion-side port 5b.

[0078] In the damping valve V1 of this embodiment, the valve opening pressure of the contraction side leaf valve 15 can be changed by adjusting the amount of current supplied to the coil 10, so that the damping force generated when the shock absorber D is contracting can be adjusted to a high or low level.

[0079] As described above, the damping valve V1 includes the piston (valve seat member) 5 having the extension side port 5b and the compression side port 5c, the extension side valve seats 5d and the compression side valve seats 5e rising from the outer peripheries of the open ends of the extension side port 5b and the compression side port 5c and surrounding the extension side port 5b and the compression side port 5c, the annular extension side leaf valves 17 and the compression side leaf valves 15 superimposed on the piston (valve seat member) 5 and capable of being seated on and removed from the extension side valve seats 5d and the compression side valve seats 5e, the opposing members 30 and 31 arranged on the opposite side of the valve seat member from the extension side leaf valves 17 and the compression side leaf valves 15 at a distance and opposing the extension side leaf valves 17 and the compression side leaf valves 15, the coil 10, the piston 5, and the valve holding member. the valve holding member 32 is disposed between the extension-side leaf valve 17 and the opposing member 30 and is movable axially around the small diameter portion 3a to abut against the side of the extension-side leaf valve 17 opposite the valve seat member; the valve holding member 33 is disposed between the compression-side leaf valve 15 and the opposing member 31 and is movable axially around the small diameter portion 3a to abut against the side of the compression-side leaf valve 15 opposite the valve seat member; the extension-side biasing member 34 is interposed between the opposing member 30 and the valve holding member 32 and biases the extension-side leaf valve 17; and the extension-side biasing member 34 is interposed between the opposing member 31 and the valve holding member 33 and biases the compression-side leaf valve 15.

[0080] The damping valve V1 configured as described above employs a structure in which the extension-side biasing member 34 and the compression-side biasing member 35, which have a magnetorheological elastomer whose elasticity can be changed by the action of a magnetic field, bias the extension-side leaf valve 17 and the compression-side leaf valve 15, respectively, thereby enabling adjustment of the damping force. Furthermore, the components required for adjusting the damping force are the extension-side biasing member 34, the compression-side biasing member 35, and the coil 10. Therefore, not only is the damping valve V1 smaller than a large solenoid that has a fixed iron core, a movable iron core, and a spring in addition to the coil, but the number of components is also reduced, and therefore the damping valve V1 can be installed in the piston portion of the shock absorber D. Therefore, the damping valve V1 of this embodiment does not require an increase in size even though the damping force is adjustable, and an increase in manufacturing costs can be suppressed.

[0081] Furthermore, according to the damping valve V1 of this embodiment, in contrast to the structure of a damping valve that has a spring between the leaf valve and the opposing member and does not allow for damping force adjustment, the damping force can be adjusted simply by providing the coil 10 and interposing the biasing member 35 (34) between the leaf valve 15 (17) and the opposing member 31 (30) instead of the spring, so that a damping force adjustment function can be provided inexpensively and easily to a damping valve that does not allow for damping force adjustment. Furthermore, since the valve holding member 32 (33) is movably provided on the outer periphery of the small diameter portion (shaft member) 3a, the biasing force of the biasing member 35 (34) can be applied to the leaf valve 17 (15) in the axial direction via the valve holding member 32 (33), so that deflection of the leaf valve 17 (15) can be efficiently suppressed.

[0082] The damping valve V2 may also be configured as in the second modified example of the embodiment shown in Fig. 4. The configuration of the damping valve V2 in the second modified example will be described below, but since the explanation of the same members as those of the damping valves V and V2 described above will be repeated, the same reference numerals will be used and detailed explanations will be omitted. The damping valve V2 of the second modified example is provided in the piston portion of the shock absorber D, and the other configurations of the shock absorber D are the same as those described above.

[0083] A damping valve V2 of a second modified example of an embodiment includes a piston 5 as a valve seat member, an extension-side leaf valve 17 and a compression-side leaf valve 15 that are capable of being seated on and separated from an extension-side valve seat 5d and a compression-side valve seat 5e of the piston 5, opposing members 30 and 31 that are arranged at an opposite side of the valve seat member from the extension-side leaf valve 17 and the compression-side leaf valve 15 and that face the extension-side leaf valve 17 and the compression-side leaf valve 15, a coil 10, a small-diameter portion 3a as an axial member of a rod 3 that rises from the piston 5, and an opposing member 30, 31 that faces the extension-side leaf valve 17 and the compression-side leaf valve 15. a valve holding member 32 arranged between the opposing member 30 and the small diameter portion 3 a and movable in the axial direction around the outer periphery of the small diameter portion 3 a and abutting against the side of the extension-side leaf valve 17 opposite the valve seat member; a valve holding member 33 arranged between the compression-side leaf valve 15 and the opposing member 31 and movable in the axial direction around the outer periphery of the small diameter portion 3 a and abutting against the side of the compression-side leaf valve 15 opposite the valve seat member; an extension-side biasing member 34 interposed between the opposing member 30 and the valve holding member 32; and an extension-side biasing member 34 interposed between the opposing member 31 and the valve holding member 33.

[0084] The damping valve V2 is provided in the piston portion of the shock absorber D, similar to the damping valves V and V1, and is assembled to the small diameter portion 3a of the rod 3 as a shaft member. On the outer periphery of the small diameter portion 3a of the rod 3, fitted in this order are an annular opposing member 31 made of a soft magnetic material, a cylindrical collar 36 made of a non-magnetic material, a cylindrical guide tube 40 made of a non-magnetic material, a compression-side leaf valve 15 as a leaf valve, a compression-side biasing member 35 as a biasing member, a valve holding member 32, the piston 5 as a valve seat member, an extension-side leaf valve 17 as a leaf valve, a valve holding member 33, an extension-side biasing member 34 as a biasing member, and a cylindrical guide tube 41 made of a non-magnetic material. The opposing member 31, collar 36, guide cylinder 40, compression-side leaf valve 15, compression-side biasing member 35, valve holddown member 32, piston 5, extension-side leaf valve 17, valve holddown member 33, extension-side biasing member 34, and guide cylinder 41 are sandwiched between the opposing member 30, which is made of a soft magnetic material and is screwed onto the threaded portion 3c of the small diameter portion 3a, and the step portion 3d of the rod 3, and are fixed to the small diameter portion 3a. In this way, the expansion-side biasing member 34 is interposed between the opposing member 30 and the valve holddown member 32 and biases the expansion-side leaf valve 17, and the compression-side biasing member 35 is interposed between the opposing member 31 and the valve holddown member 33.

[0085] The collar 36 is formed from a non-magnetic tube and is interposed between the opposing members 30 and 31. It is sandwiched between the step portion 3d of the rod 3 and the opposing member 30 and is fixed immovably to the outer periphery of the rod 3 together with the opposing members 30 and 31.

[0086] The guide tube 40 is cylindrical and made of a non-magnetic material, and is fitted onto the outer periphery of the collar 36 and overlaps the lower part of the opposing member 31 in FIG. 3. The guide tube 41 is annular and made of a non-magnetic material, and is fitted onto the outer periphery of the collar 36 and overlaps the upper part of the opposing member 30 in FIG. 3.

[0087] The piston 5 is fitted onto the outer periphery of the collar 36, and its inner periphery is sandwiched and fixed between guide cylinders 40, 41. The compression-side leaf valve 15 is fitted onto the outer periphery of the guide cylinder 40 so as to be axially movable, and can be moved entirely towards or away from the piston 5, and opens and closes the compression-side port 5c by being seated on and separated from a compression-side valve seat 5e. The extension-side leaf valve 17 is fitted onto the outer periphery of the guide cylinder 41 so as to be axially movable, and can be moved entirely towards or away from the piston 5, and can be seated on and separated from an extension-side valve seat 5d by being seated on and separated from an extension-side valve seat 5d by which the extension-side port 5b is opened and closed.

[0088] 3, which is the side opposite the valve seat member of the compression-side leaf valve 15, a cylindrical valve holding member 33 having a flange on its outer periphery that abuts against the side opposite the valve seat of the compression-side leaf valve 15 is fitted onto the outer periphery of a collar 36 so as to be movable up and down. The valve holding member 33 is in sliding contact with the outer periphery of the collar 36, and therefore can move axially without axial wobble relative to the small diameter portion 3a, which serves as a shaft member with which the collar 36 is fitted.

[0089] 3, which is the side opposite to the valve seat member of the expansion-side leaf valve 17, a cylindrical valve holding member 32 having a flange on its outer periphery that abuts against the side opposite to the valve seat of the expansion-side leaf valve 17 is fitted to the outer periphery of a collar 36 so as to be movable up and down. The valve holding member 32 is in sliding contact with the outer periphery of the collar 36, and therefore can move axially without axial wobble relative to the small diameter portion 3a, which serves as a shaft member with which the collar 36 is fitted.

[0090] The compression-side biasing member 35 is annular and made of a magnetorheological elastomer. It has elasticity and its elastic modulus changes depending on the magnitude of the applied magnetic field. The compression-side biasing member 35 is fitted onto the outer periphery of the protrusion 31a of the opposing member 31 to determine its radial position. Its axial length is set to be equal to or greater than the axial length of the guide tube 40. It is interposed in a compressed state between the opposing member 31 and the valve retaining member 33. Therefore, the compression-side biasing member 35 constantly biases the compression-side leaf valve 15 toward the piston 5 via the valve retaining member 33 with its own elastic force. When the force in the pressure in the compression-side chamber R2 moving the compression-side leaf valve 15 away from the piston 5 exceeds the biasing force of the compression-side biasing member 35, the compression-side leaf valve 15 moves upward in FIG. 4 to separate from the piston 5 and open the compression-side port 5c.

[0091] The expansion-side biasing member 34 is annular and made of a magnetorheological elastomer. It has elasticity and its elastic modulus changes according to the magnitude of the applied magnetic field. The expansion-side biasing member 34 is fitted onto the outer periphery of the protrusion 30b of the opposing member 30 to determine its radial position. Its axial length is set to be equal to or longer than the axial length of the guide tube 41. It is interposed in a compressed state between the opposing member 30 and the valve holding member 32. Therefore, the expansion-side biasing member 34 constantly biases the expansion-side leaf valve 17 toward the piston 5 via the valve holding member 32 with its own elastic force. When the force of the pressure in the expansion-side chamber R1, which moves the expansion-side leaf valve 17 away from the piston 5, exceeds the biasing force of the expansion-side biasing member 34, the expansion-side leaf valve 17 moves downward in FIG. 4 to separate from the piston 5 and open the expansion-side port 5b.

[0092] It is sufficient that the compression side biasing member 35 and the extension side biasing member 34 as biasing members are able to bias the corresponding compression side leaf valves 15 and extension side leaf valves 17 using magnetorheological elastomer, so the entire compression side biasing member 35 and the extension side biasing member 34 may be made of magnetorheological elastomer, or the compression side biasing member 35 and the extension side biasing member 34 may have a portion that includes magnetorheological elastomer that can bias the compression side leaf valve 15 and the extension side leaf valve 17.

[0093] When current is applied to the coil 10 attached to the outer periphery of the small diameter portion 3a of the rod 3, the small diameter portion 3a, the opposing member 31, the piston 5, and the opposing member 30 are made of soft magnetic materials, and the guide tubes 40, 41 and the collar 36 are made of non-magnetic materials, the magnetic field emitted from the coil 10 passes through the opposing member 31, the compression-side biasing member 35, the piston 5, the extension-side biasing member 34, and the opposing member 30 and returns to the coil 10. The opposing member 31, the piston 5, and the opposing member 30 form a magnetic circuit, and when current is applied to the coil 10, a magnetic field can be efficiently applied to the compression-side biasing member 35 and the extension-side biasing member 34. Furthermore, the strength of the magnetic field applied to the compression-side biasing member 35 and the extension-side biasing member 34 can be adjusted by adjusting the amount of current applied to the coil 10, so the elastic moduli of the compression-side biasing member 35 and the extension-side biasing member 34 can be increased or decreased by adjusting the amount of current applied to the coil 10. When the elastic modulus of the compression-side biasing member 35 and the expansion-side biasing member 34 changes, the biasing force applied by the compression-side biasing member 35 to the compression-side leaf valve 15 and the biasing force applied by the expansion-side biasing member 34 to the expansion-side leaf valve 17 change. Therefore, by adjusting the amount of current applied to the coil 10, the valve opening pressure of the compression-side leaf valve 15 and the expansion-side leaf valve 17 can be adjusted.

[0094] Next, the operation of the shock absorber D equipped with the damping valve V2 of the second modified example will be described. First, when the rod 3 moves upward in FIG. 3 relative to the cylinder 4 and the shock absorber D extends, the piston 5 also moves upward together with the rod 3 relative to the cylinder 4, compressing the expansion-side chamber R1 and expanding the contraction-side chamber R2. As the expansion-side chamber R1 is compressed, the pressure in the expansion-side chamber R1 increases, and the expansion-side leaf valve 17 of the damping valve V2 is pressed by the pressure of the expansion-side chamber R1 acting through the expansion-side port 5b. When the force pressing the expansion-side leaf valve 17 downward in FIG. 3 due to the pressure in the expansion-side chamber R1 exceeds the biasing force of the expansion-side biasing member 34, the expansion-side leaf valve 17 bends, opening the expansion-side port 5b and providing resistance to the flow of hydraulic oil passing through the expansion-side port 5b. In this way, when the shock absorber D is extended, the extension-side leaf valve 17 applies resistance to the flow of hydraulic oil, so the pressure in the extension-side chamber R1 becomes higher than the pressure in the compression-side chamber R2, and the shock absorber D generates a damping force that suppresses the extension operation. Note that when the shock absorber D is extended, the pressure in the extension-side chamber R1 and the biasing force of the compression-side biasing member 35 keep the compression-side leaf valve 15 seated on the compression-side valve seat 5e, so the compression-side port 5c is blocked and the hydraulic oil does not pass through the compression-side port 5c.

[0095] In the damping valve V2 of this embodiment, the valve opening pressure of the extension-side leaf valve 17 can be changed by adjusting the amount of current supplied to the coil 10, so that the damping force generated when the shock absorber D is in an extension operation can be adjusted.

[0096] Furthermore, when shock absorber D extends, rod 3 retracts from cylinder 4, causing a shortage of hydraulic oil in cylinder 4 to compensate for the volume of hydraulic oil retracted by rod 3. However, check valve 24 provided in valve case 6 opens and supplies this shortage of hydraulic oil from reservoir chamber R into cylinder 4. The opening pressure of check valve 24 is set very low to prevent the pressure inside cylinder 4 from dropping below atmospheric pressure.

[0097] Next, when the rod 3 moves downward relative to the cylinder 4 in FIG. 4 and the shock absorber D contracts, the piston 5 also moves downward relative to the cylinder 4 together with the rod 3, compressing the compression-side chamber R2 and expanding the extension-side chamber R1. As the compression-side chamber R2 compresses, the pressure in the compression-side chamber R2 increases, and the compression-side leaf valve 15 in the damping valve V1 is pressed by the pressure of the compression-side chamber R2 acting through the compression-side port 5c. When the force exerted upward in FIG. 4 by the pressure in the compression-side chamber R2 exceeds the biasing force of the compression-side biasing member 35, the compression-side leaf valve 15 bends, opening the compression-side port 5c and providing resistance to the flow of hydraulic oil passing through the compression-side port 5c. Furthermore, when the shock absorber D contracts, the hydraulic oil in the cylinder 4 becomes excessive by the volume of the rod 3 penetrating into the cylinder 4, and the excess hydraulic oil moves to the reservoir chamber R via the compression-side damping passage 6a and the compression-side valve 23. In this way, when the shock absorber D is contracting, the compression-side leaf valve 15 and the compression-side valve 23 provide resistance to the flow of hydraulic oil, so the pressure in the compression-side chamber R2 becomes higher than the pressure in the extension-side chamber R1, and the shock absorber D generates a damping force that suppresses the extension operation. Note that when the shock absorber D is contracting, the expansion-side leaf valve 17 is kept seated on the expansion-side valve seat 5d by the pressure in the compression-side chamber R2 and the biasing force of the expansion-side biasing member 34, so the expansion-side port 5b is blocked and the hydraulic oil does not pass through the expansion-side port 5b.

[0098] In the damping valve V2 of this embodiment, the valve opening pressure of the contraction side leaf valve 15 can be changed by adjusting the amount of current supplied to the coil 10, so that the damping force generated when the shock absorber D is contracting can be adjusted to a high or low level.

[0099] As described above, the damping valve V2 includes the piston (valve seat member) 5 having the extension side port 5b and the compression side port 5c, the extension side valve seats 5d and the compression side valve seats 5e rising from the outer peripheries of the open ends of the extension side port 5b and the compression side port 5c and surrounding the extension side port 5b and the compression side port 5c, the annular extension side leaf valves 17 and the compression side leaf valves 15 which are superimposed on the piston (valve seat member) 5 so as to be axially movable and are seated on and separated from the extension side valve seats 5d and the compression side valve seats 5e, the opposing members 30 and 31 which are arranged on the opposite side of the valve seat member from the extension side leaf valves 17 and the compression side leaf valves 15 at an interval and which face the extension side leaf valves 17 and the compression side leaf valves 15, the coil 10, the piston 5 and the opposing portions the valve holding member 32 is arranged between the extension-side leaf valve 17 and the opposing member 30 and is movable axially around the small diameter portion 3a to abut against the side of the extension-side leaf valve 17 opposite the valve seat member; the valve holding member 33 is arranged between the compression-side leaf valve 15 and the opposing member 31 and is movable axially around the small diameter portion 3a to abut against the side of the compression-side leaf valve 15 opposite the valve seat member; the extension-side biasing member 34 is interposed between the opposing member 30 and the valve holding member 32 and biases the extension-side leaf valve 17; and the extension-side biasing member 34 is interposed between the opposing member 31 and the valve holding member 33 and biases the compression-side leaf valve 15.

[0100] The damping valve V2 configured in this manner employs a structure in which the extension-side biasing member 34 and the compression-side biasing member 35, which have a magnetorheological elastomer whose elasticity can be changed by the action of a magnetic field, bias the extension-side leaf valve 17 and the compression-side leaf valve 15, respectively, thereby enabling adjustment of the damping force. Furthermore, the components required for adjusting the damping force are the extension-side biasing member 34, the compression-side biasing member 35, and the coil 10. Therefore, not only is the damping valve V2 smaller than a large solenoid that has a fixed iron core, a movable iron core, and a spring in addition to the coil, but the number of components is also reduced, and therefore the damping valve V2 can be installed in the piston portion of the shock absorber D. Therefore, the damping valve V2 of this embodiment does not increase in size even though the damping force is adjustable, and an increase in manufacturing costs can be suppressed.

[0101] Furthermore, according to the damping valve V2 of this embodiment, in contrast to the structure of a damping valve that has a spring between the leaf valve and the opposing member and does not allow for damping force adjustment, by simply providing a coil 10 and interposing a biasing member 35 (34) between the leaf valve 15 (17) and the opposing member 31 (30) instead of a spring, it is possible to adjust the damping force, so that a damping force adjustment function can be added inexpensively and easily to a damping valve that does not allow for damping force adjustment.

[0102] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]

[0103] 1··· Shock absorber body, 2··· Outer shell, 3··· Rod, 3a··· Small diameter portion (shaft member), 5··· Piston (valve seat member), 5b··· Extension side port (port), 5c··· Compression side port (port), 5d··· Extension side valve seat (valve seat), 5e··· Compression side valve seat (valve seat), 10··· Coil, 12, 20··· Valve stopper (opposing member), 15··· Compression side leaf valve (relief valve) Leaf valve), 16, 35... compression side biasing member (biasing member), 17... extension side leaf valve (leaf valve), 18, 34... extension side biasing member (biasing member), 30, 31... opposing member, 32, 33... valve holding member, D... shock absorber, R... reservoir chamber (operating chamber), R1... extension side chamber (operating chamber), R2... compression side chamber (operating chamber), V, V1, V2... damping valve

Claims

1. a valve seat member having a port and a valve seat rising from the outer periphery of an open end of the port and surrounding the port; a leaf valve that is annular and overlaps the valve seat member and can be seated on and removed from the valve seat; an opposing member disposed on a side opposite to the leaf valve seat member and facing the leaf valve with a gap therebetween; a biasing member having a magnetorheological elastomer interposed between the leaf valve and the opposing member and biasing the leaf valve toward the valve seat; a coil for applying a magnetic field to the biasing member; A damping valve characterized by:

2. a shaft member to which the valve seat member and the opposing member are attached, the leaf valve is annular, and an inner circumferential side thereof is fixed between the valve seat member and the opposing member of the shaft member, and deflection of the outer circumferential side thereof is permitted; The biasing member is provided between the outer circumferential side of the leaf valve and the opposing member.

2. The damping valve of claim 1.

3. a shaft member to which the valve seat member and the opposing member are attached; a valve holding member disposed between the leaf valve and the opposing member, axially movable relative to the shaft member, and abutting against the leaf valve on a side opposite to the valve seat member, The biasing member is interposed between the opposing member and the valve holding member, and biases the leaf valve via the valve holding member.

2. The damping valve of claim 1.

4. The valve seat member and the opposing member are made of a soft magnetic material.

2. The damping valve of claim 1.

5. a shock absorber body having an outer shell, a rod inserted into the outer shell so as to be axially movable, and at least two working chambers through which liquid flows as the rod moves relative to the outer shell; and a damping valve according to any one of claims 1 to 4, which is provided between the operating chambers. A shock absorber characterized by:

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