Damping valve and buffer

Abstract

To provide a damping valve capable of functioning as a check valve while suppressing fatigue of a leaf valve, and a buffer which can improve riding quality.SOLUTION: A damping valve EV, CV includes: an annular valve body 21, 27 having a fixed end and a free end; a valve seat member 20, 26 having an annular opposing seat part 20b, 26b opposing to a peripheral surface in a side of the free end of the valve body 21, 27, and a port 20c, 26d provided closer to the fixed end of the valve body 21, 27 than opposing seat part 20b, 26b; and an orifice O1, O2 which is provided in the valve body 21, 27 of the valve seat member 20, 26, and communicates a valve seat member side and an opposite valve seat member side of the valve body 21, 27 with the valve body 21, 27 directly opposing the opposing seat part 20b, 26b.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A shock absorber is used, for example, by being interposed between the body and wheels of a vehicle for the purpose of improving the ride comfort of the vehicle, and suppresses vibration of the body and wheels by the damping force that it exerts when expanding and contracting.

[0003] Such a shock absorber includes, for example, a cylinder, a rod that is movably inserted into the cylinder, a piston that is slidably inserted into the cylinder and divides the inside of the cylinder into an expansion side chamber and a compression side chamber, a free piston that is slidably inserted into the cylinder and divides an air chamber below the compression side chamber in the cylinder, a damping passage provided in the piston that connects the expansion side chamber and the compression side chamber, and a damping valve provided in the damping passage.

[0004] In recent years, in order to improve ride comfort in vehicles, there has been a demand for vehicle shock absorbers to exhibit damping force characteristics in which the damping coefficient is high in the very low speed range where the extension / retraction speed is lower than low speed, so that the damping force is quickly increased in response to the change in the extension / retraction stroke, and the damping coefficient is smaller in the low speed range than in the very low speed range, and further, in the medium to high speed range above low speed, the damping coefficient is proportional to the extension / retraction speed but smaller than in the low speed range.

[0005] In order to meet such demands, the damping valve is equipped with an annular leaf valve that is fixed on the inner circumference and allows deflection on the outer circumference, and a valve seat member that is annular and has an annular opposing seat portion that faces the outer circumference of the leaf valve but does not contact the outer circumference, and has a port on the inner circumference of the opposing seat portion, and provides resistance to the flow of hydraulic oil between the extension side chamber and the compression side chamber.

[0006] In a damping valve configured in this manner, when the shock absorber's expansion / contraction speed is in the very low speed range, the leaf valve does not bend significantly and the flow path area between the opposing seat is restricted to an extremely small value, resulting in a damping force characteristic that rises sharply in accordance with the expansion / contraction speed, thereby achieving damping force characteristics suitable for the vehicle (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-183918 A Summary of the Invention [Problem to be solved by the invention]

[0008] In conventional damping valves, when the leaf valve does not bend and faces the opposing seat radially, the gap between the leaf valve and the opposing seat becomes very narrow, making it difficult for hydraulic oil to pass through the gap.As a result, when the shock absorber's expansion / contraction speed is in the very low speed range, the damping force rises suddenly, but if the bending rigidity of the leaf valve is increased, the damping force may become excessive.

[0009] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a damping valve and a shock absorber that can prevent the damping force from becoming excessive. [Means for solving the problem]

[0010] In order to solve the above problems, the damping valve of the present invention comprises an annular valve body whose inner circumference is a fixed end and whose outer circumference is a free end allowing the free end to flex relative to the fixed end, a valve seat member having an annular opposing seat portion opposing at least a portion of the circumferential surface of the free end side of the valve body, and a port provided radially on the fixed end side of the valve body relative to the opposing seat portion, and an orifice provided in the valve body communicating between the valve seat member side and the anti-valve seat member side of the valve body with the valve body and the opposing seat portion directly facing each other.

[0011] With the damping valve configured in this manner, even if the free end of the valve body and the opposing seat face each other, liquid can pass through the orifice in places other than the gap between the valve body and the opposing seat. Therefore, with the damping valve, even if the flexural rigidity of the valve body is set high, the damping force does not become excessive when the expansion and contraction speed of the shock absorber is in the extremely low speed range.

[0012] The valve seat member in the damping valve may include an annular valve seat that is provided between the opposing seat portion and the port and faces the valve body in the axial direction so as to be able to seat and separate from the valve body. The damping valve configured in this manner can function as a damping valve for the flow of liquid passing through the port in one direction, and can function as a check valve for the flow of liquid passing through the port in the other direction.

[0013] Furthermore, the valve disc in the damping valve may include a first leaf valve that is annular and has an outer periphery, which is the peripheral surface of a free end, facing the opposing seat portion and has a hole penetrating in the axial direction so as to be able to be seated and removed from the annular valve seat, a second leaf valve that is annular and stacked on the opposite valve seat member side of the first leaf valve and has a notch that opens from the outer periphery, which is the free end, and communicates with the hole, and a third leaf valve that is annular and stacked on the opposite valve seat member side of the second leaf valve, and the orifice may be formed by the notch. According to the damping valve configured in this manner, when the valve disc bends toward the opposite valve seat member side so as to move away from the valve seat member 20, it functions as a damping valve, and when the valve disc bends toward the valve seat member side and sits on the annular valve seat, the free end of the third leaf valve faces the opposing seat portion, minimizing the gap between the third leaf valve and the opposing seat portion and making it difficult for liquid to pass through the gap, so that when it functions as a check valve, even if it has an orifice, the port can be substantially closed.

[0014] In addition, the valve body in the damping valve may be annular, with the peripheral surface of the outer periphery, which is the free end, facing the opposing seat portion, and may have a notch that opens from the outer periphery, which is the free end, and the orifice may be formed by the notch. With the damping valve configured in this way, it is sufficient to provide the notch that forms the orifice in the free end of the valve body, making it easy to provide the orifice.

[0015] Furthermore, the orifice in the damping valve may be formed by a groove provided in the annular seat portion of the valve seat member. With the damping valve configured in this manner, it is easy to provide the orifice since it is sufficient to provide the groove that forms the orifice in the opposing seat portion.

[0016] Furthermore, the shock absorber of the present invention includes an outer tube, a rod inserted into the outer tube so as to be axially movable, a shock absorber body having at least two working chambers through which liquid flows by the movement of the rod relative to the outer tube, and a damping valve provided between the working chambers. In the shock absorber configured in this manner, it is possible to prevent the damping force from becoming excessive in the extremely low expansion / contraction speed range, and to improve the ride comfort of the vehicle. Effect of the Invention

[0017] The damping valve of the present invention can prevent the damping force from becoming excessive, and the shock absorber of the present invention can improve the ride comfort in the vehicle. [Brief description of the drawings]

[0018] [Figure 1] 1 is a vertical sectional view of a shock absorber to which a damping valve according to an embodiment of the present invention is applied; [Diagram 2] 1 is a partially enlarged cross-sectional view of a shock absorber to which a damping valve according to an embodiment of the present invention is applied; [Diagram 3] Fig. 3(A) is a plan view of a first leaf valve constituting a valve body of a damping valve according to an embodiment of the present invention. Fig. 3(B) is a plan view of a second leaf valve constituting a valve body of a damping valve according to an embodiment of the present invention. Fig. 3(C) is a plan view of a third leaf valve constituting a valve body of a damping valve according to an embodiment of the present invention. [Figure 4] 4 is a diagram showing the damping force characteristics of a shock absorber to which the damping valve according to the embodiment of the present invention is applied. FIG. [Diagram 5] FIG. 4 is a partially enlarged cross-sectional view of a damping valve in a first modified example of one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention will be described below based on the embodiment shown in the drawings. As shown in Fig. 1 and Fig. 2, a shock absorber D in one embodiment includes a shock absorber body A that is expandable and contractible and has a cylinder 1 as an outer tube and a rod 2 movably inserted into the cylinder 1, and an expansion-side sub-valve EV and a compression-side sub-valve CV as damping valves provided between an expansion-side chamber R1 and a compression-side chamber R2 as two working chambers provided in the shock absorber body A. This shock absorber D is used by being interposed between the body and wheels of a vehicle (not shown) to suppress vibration of the body and wheels.

[0020] Hereinafter, each part of the shock absorber D will be described in detail. As shown in Fig. 1, the shock absorber main body A includes a cylindrical cylinder 1 with a bottom as an outer tube, a rod 2 movably inserted into the cylinder 1, and a piston 3 connected to the rod 2, movably inserted into the cylinder 1, and partitioning the inside of the cylinder 1 into an expansion-side chamber R1 and a compression-side chamber R2 as working chambers.

[0021] A bracket (not shown) is provided at the base end of the rod 2, which is the upper end in Fig. 1, and the rod 2 is connected to one of the vehicle body and the wheel via the bracket (not shown). A bracket (not shown) is also provided at the bottom 1a of the cylinder 1, and the cylinder 1 is connected to the other of the vehicle body and the wheel via the bracket (not shown).

[0022] In this way, shock absorber D is interposed between the vehicle body and the wheels. When the vehicle runs on an uneven road surface and the wheels vibrate up and down relative to the vehicle body, the rod 2 moves in and out of the cylinder 1, the shock absorber D expands and contracts, and the piston 3 moves up and down (axially) within the cylinder 1.

[0023] The shock absorber body A also includes an annular rod guide 10 that closes the upper end of the cylinder 1 and through which the rod 2 is slidably inserted around its inner periphery. Thus, the inside of the cylinder 1 is an enclosed space. A free piston 11 is slidably inserted into the cylinder 1 on the opposite side of the piston 3 from the rod 2.

[0024] A liquid chamber L is formed above the free piston 11 in the cylinder 1, and an air chamber G is formed below it. The liquid chamber L is further divided by the piston 3 into an extension side chamber R1 on the rod 2 side and a compression side chamber R2 on the piston 3 side, and the extension side chamber R1 and the compression side chamber R2 are each filled with liquid. The liquid filled in the shock absorber body A may be hydraulic oil, water, an aqueous solution, or other liquid. On the other hand, the air chamber G is filled with compressed air or a gas such as nitrogen gas.

[0025] When the rod 2 retreats from the cylinder 1 during the extension operation of the shock absorber D and the internal volume of the cylinder increases by the volume of the retreated rod 2, the free piston 11 moves upward within the cylinder 1 to expand the air chamber G. Conversely, when the rod 2 advances into the cylinder 1 during the contraction operation of the shock absorber D and the internal volume of the cylinder decreases by the volume of the advanced rod 2, the free piston 11 moves downward within the cylinder 1 to reduce the air chamber G.

[0026] Incidentally, instead of the free piston 11, a bladder, a bellows or the like may be used to separate the liquid chamber L and the air chamber G, and the configuration of the movable partition that serves as this partition can be appropriately changed.

[0027] Furthermore, in this embodiment, the shock absorber D is a single-rod, single-cylinder shock absorber, and when the shock absorber D expands or contracts, the free piston 11 expands or contracts the air chamber G to compensate for the volume of the rod 2 moving in and out of the cylinder 1. However, the configuration for this volume compensation can also be changed as appropriate.

[0028] For example, in the case where the free piston 11 and the air chamber G are eliminated and an outer tube is provided around the outer periphery of the cylinder 1, and a reservoir for storing liquid is formed between the cylinder 1 and the outer tube to make the shock absorber a twin-cylinder type shock absorber, the reservoir may be used to compensate for the volume of the rod 2 moving in and out of the cylinder 1. The reservoir may be formed in a tank that is separate from the cylinder 1. The shock absorber D may also be configured as a double-rod type shock absorber in which the piston 3 is attached to the center of the rod 2 and the ends of the rod 2 protrude outside the cylinder 1 from both ends of the cylinder 1.

[0029] The rod 2 is cylindrical and has a reduced outer diameter at the tip side. The rod 2 is equipped with a small diameter section 2a having the smallest diameter at the tip side, a large diameter section 2b having an outer diameter larger than that of the small diameter section 2a and provided above the small diameter section 2a in Figure 2, a step section 2c provided at the boundary between the small diameter section 2a and the large diameter section 2b, a screw section 2d provided on the outer periphery of the tip of the small diameter section 2a, and four through holes 2e, 2f, 2g, 2h provided at positions shifted from each other upward in Figure 2 from the screw section 2d of the small diameter section 2a and communicating between the inside and the outside of the small diameter section 2a.

[0030] A valve seat member 20, a valve disc 21, a spacer 22, and a valve stopper 23 of the extension side sub-valve EV, a spacer 24, a partition member 25, a valve seat member 26, a valve disc 27, a spacer 28, and a valve stopper 29 of the compression side sub-valve CV, a main valve stopper 6, a compression side main valve 5, a piston 3, and an extension side main valve 4 are assembled in this order to the small diameter portion 2a of the rod 2, and fixed by a piston nut 33 screwed into the threaded portion 2d at the tip of the small diameter portion 2a.

[0031] 1 and 2, the piston 3 is annular and fixed to the outer periphery of the small diameter portion 2a of the rod 2, and is in sliding contact with the inner periphery of the cylinder 1, dividing the inside of the cylinder 1 into an expansion-side chamber R1 on the upper side in Fig. 1 and a compression-side chamber R2 on the lower side in Fig. 1. The piston 3 is provided with an expansion-side passage 3a and a compression-side passage 3b that communicate the expansion-side chamber R1 and the compression-side chamber R2.

[0032] The expansion-side main valve 4 is laminated at the lower end of the piston 3 in FIG. 2. The expansion-side main valve 4 is annular and fitted to the outer periphery of the small diameter portion 2a of the rod 2 to open and close the expansion-side passage 3a. The expansion-side main valve 4 is a laminated leaf valve formed by laminating a plurality of annular plates, and the inner periphery side is fixed to the small diameter portion 2a of the rod 2 to allow bending on the outer periphery side. When the expansion-side main valve 4 is seated on the lower end of the piston 3, it closes the outlet end of the lower end of the expansion-side passage 3a, and when the outer periphery side is bent and separated from the piston 3, it opens the expansion-side passage 3a and provides resistance to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2 through the expansion-side passage 3a. The expansion-side main valve 4 is seated on the piston 3 to close the expansion-side passage 3a against the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1.

[0033] At the upper end of the piston 3 in FIG. 2, a contraction-side main valve 5 is laminated, which is annular and fitted to the outer periphery of the small diameter portion 2a of the rod 2 to open and close the contraction-side passage 3b. The contraction-side main valve 5 is a laminated leaf valve formed by laminating a plurality of annular plates, and the inner periphery side is fixed to the small diameter portion 2a of the rod 2 to allow bending on the outer periphery side. When the contraction-side main valve 5 is seated on the upper end of the piston 3, it closes the outlet end of the upper end of the contraction-side passage 3b, and when the outer periphery side is bent and separated from the piston 3, it opens the contraction-side passage 3b and provides resistance to the flow of liquid from the contraction-side chamber R2 to the expansion-side chamber R1 through the contraction-side passage 3b. The contraction-side main valve 5 is seated on the piston 3 to close the contraction-side passage 3b against the flow of liquid from the expansion-side chamber R1 to the contraction-side chamber R2. A main valve stopper 6 is laminated above the contraction-side main valve 5 in FIG. 2. When the compression side main valve 5 is deflected significantly, the main valve stopper 6 comes into contact with the side of the compression side main valve 5 opposite the piston to support the compression side main valve 5 and prevent excessive stress from acting on the compression side main valve 5, thereby protecting the compression side main valve 5.

[0034] In this embodiment, the expansion-side sub-valve EV serving as a damping valve includes a valve seat member 20, a valve element 21, and an orifice O1 provided in the valve element 21, as shown in FIG. The valve seat member 20 is annular and comprises a perforated disk-shaped partition body 20a that fits onto the outer periphery of the small diameter portion 2a, an annular opposing seat portion 20b that protrudes downward from the outer periphery of the lower end of the partition body 20a in FIG. 2, a plurality of ports 20c that are provided on the same circumference and on the inner side of the opposing seat portion 20b at the lower end of the partition body 20a in FIG. 2, a window 20d that is annular recessed portion that is provided at the lower end of the partition body 20a in FIG. 2 and communicates with the outlet ends of each port 20c, an annular valve seat 20e that is provided at the lower end of the partition body 20a in FIG. 2 and protrudes downward from between the opposing seat portion 20b and the port 20c, and an annular inner seat portion 20f that is provided on the inner circumference of the window 20d.

[0035] The facing seat 20b surrounds the outer periphery of the annular valve seat 20e with a gap from the partition body 20a, and protrudes downward from the lower end of the annular valve seat 20e. That is, the height of the facing seat 20b is higher than the annular valve seat 20e when viewed from the partition body 20a, and the height difference between the facing seat 20b and the annular valve seat 20e is at least higher than the axial thickness of the valve body 21 described later. In addition, in the case of this embodiment, the inner circumference of the valve body 21 is a fixed end and the outer circumference is a free end, so that the annular valve seat 20e is provided on the inner circumference side of the facing seat 20b in the valve seat member 20, which is the fixed end side of the valve body 21 in the radial direction. In addition, the height of the seat surface of the inner circumference seat 20f, which is the lower end surface in FIG. 2, is higher than the height of the seat surface of the annular valve seat 20e, which is the lower end surface in FIG. 2, and is lower than the facing seat 20b.

[0036] In this embodiment, the opposing seat 20b and the annular valve seat 20e protrude axially relative to the partition body 20a, and an annular recess is formed between the opposing seat 20b and the annular valve seat 20e. However, when the inner circumference of the valve body 21 is a fixed end, the annular valve seat 20e is provided on the inner circumference of the opposing seat 20b, and as long as the height of the opposing seat 20b is higher than that of the annular valve seat 20e as described above, the opposing seat 20b and the annular valve seat 20e may be integrally arranged to protrude axially from the partition body 20a without having an annular recess between them.

[0037] As shown in FIG. 2, the valve body 21 is composed of three leaf valves 21a, 21b, 21c, each of which has an inner circumferential side fixed to the small diameter portion 2a as a fixed end and an outer circumferential side which is allowed to bend as a free end. The valve body 21 is overlapped on the lower end of the partition body 20a of the valve seat member 20 in FIG. 2 and fixed to the outer circumferential side of the small diameter portion 2a.

[0038] The valve body 21 includes a first leaf valve 21a which is annular, elastic, and located at the top in Figure 2, a second leaf valve 21b which is annular, elastic, and stacked on the anti-valve seat member side of the first leaf valve 21a and has the same inner and outer diameters as the first leaf valve 21a, and a third leaf valve 21c which is annular, elastic, and stacked on the anti-valve seat member side of the second leaf valve 21b and has the same inner and outer diameters as the first leaf valve 21a.

[0039] As shown in Fig. 3(A), the first leaf valve 21a is annular and has a hole 21a1 penetrating in the axial direction, and when there is no load and it is not deflected, the peripheral surface of the outer periphery which is the free end faces the opposing seat portion 20b and faces the annular valve seat 20e with a gap in the axial direction, and when it is deflected toward the valve seat member, it can seat on the annular valve seat 20e. As shown in Fig. 3(B), the second leaf valve 21b is annular and is stacked on the opposite side of the first leaf valve 21a to the valve seat member, and has a notch 21b1 which opens from the outer periphery which is the free end and communicates with the hole 21a1. The notch 21b1 is configured to include a plurality of arc-shaped portions 21b2 provided on the same circumference of the second leaf valve 21b, and a straight portion 21b3 which opens from the outer periphery of the leaf valve 21b and communicates with the arc-shaped portion 21b2. As shown in FIG. 3(C), the third leaf valve 21c is annular and is stacked on the side opposite the valve seat member of the second leaf valve 21b.

[0040] When the first leaf valve 21a, the second leaf valve 21b and the third leaf valve 21c of the valve body 21 are overlapped, the space connected to the port 20c on the valve seat member side of the valve body 21 is connected to the expansion side chamber R1 on the opposite side of the valve body 21 to the valve seat member side by the hole 21a1 and the notch 21b1, and the upper and lower parts of the straight portion 21b3 at the notch 21b1 in Figure 2 are blocked by the first leaf valve 21a and the third leaf valve 21c, leaving an opening on the outer periphery of the second leaf valve 21b of the straight portion 21b3, and the straight portion 21b3 functions as an orifice O1.

[0041] When the valve body 21 thus configured is placed on the inner peripheral seat 20f of the partition body 20a of the valve seat member 20, the first leaf valve 21a of the valve body 21 faces the opposing seat 20b in the radial direction, and faces the annular valve seat 20e in the axial direction with a gap therebetween because the inner peripheral seat 20f is higher than the annular valve seat 20e. In this way, the outer peripheral surface of the free end of the first leaf valve 21a of the valve body 21 faces the inner peripheral surface of the opposing seat 20b of the valve seat member 20 in the radial direction with a small gap therebetween. Therefore, when the first leaf valve 21a faces the opposing seat 20b, the gap between the first leaf valve 21a and the opposing seat 20b is extremely small, making it difficult for liquid to pass through the gap, and this state is the state in which the expansion-side sub-valve EV is closed. In this state in which the expansion-side sub-valve EV is closed, the passage of liquid is permitted almost exclusively through the orifice O1. Furthermore, as long as at least a portion of the outer peripheral surface on the free end side of the valve body 21 faces radially against the opposing seat portion 20b, the extension side sub-valve EV can open and close the port 20c, so it is not necessary for the entire outer peripheral surface of the first leaf valve 21a to face radially against the entire inner peripheral surface of the opposing seat portion 20b.

[0042] The spacer 22 laminated on the side opposite the valve seat member 20 of the valve body 21 has an outer diameter smaller than that of the valve body 21 and is fixed immovably to the small diameter portion 2a. The spacer 22 is composed of one annular plate, but may be composed of multiple annular plates. When the valve body 21 receives pressure from the upper side of the valve seat member 20 in FIG. 2, which is passing through the port 20c downward, the outer periphery of the spacer 22 is deflected downward in FIG. 2 with the outer periphery of the spacer 22 as a fulcrum. Then, the outer periphery of the first leaf valve 21a is no longer directly opposed to the inner periphery of the opposing seat portion 20b in the radial direction, and is shifted downward with respect to the opposing seat portion 20b, and the area of ​​the flow path formed by the gap between the first leaf valve 21a and the opposing seat portion 20b is increased according to the amount of deflection of the first leaf valve 21a. When the first leaf valve 21a and the opposing seat portion 20b are misaligned in this manner and no longer face each other directly, the expansion-side sub-valve EV opens, and the expansion-side sub-valve EV provides resistance to the flow of liquid while allowing the liquid to flow through the gap via the valve body 21.

[0043] When the valve element 21 receives pressure from the lower part of the valve seat member 20 in Fig. 2 of the liquid passing upward through the port 20c, the valve element 21 bends the outer periphery upward in Fig. 2 with the inner peripheral edge of the inner peripheral seat portion 20f of the valve seat member 20 as a fulcrum. When the valve element 21 bends by a preset amount or more, the first leaf valve 21a seats on the annular valve seat 20e to close the port 20c. Even when the first leaf valve 21a is seated on the annular valve seat 20e, the port 20c and the notch 21b1 are connected by the hole 21a1, but the outer periphery of the third leaf valve 21c stacked on the side of the valve seat member opposite the second leaf valve 21b with the notch 21b1 radially faces the opposing seat 20b, making the annular gap between the third leaf valve 21c and the opposing seat 20b extremely small, making it difficult for liquid to pass through the gap between the third leaf valve 21c and the opposing seat 20b. Therefore, in the extension-side sub-valve EV as a damping valve in this embodiment, when liquid flows from the upper side to the lower side in Fig. 2 through the port 20c, the free end of the valve element 21 bends toward the side opposite to the valve seat member to open and allow the liquid to flow, and conversely, when liquid flows from the lower side to the upper side in Fig. 2 through the port 20c, the free end of the valve element 21 bends toward the valve seat member to seat on the annular valve seat 20e and block the liquid flow. In this way, the extension-side sub-valve EV functions as a damping valve that opens to allow the liquid flowing in one direction through the port 20c while providing resistance, and also functions as a check valve that closes to block the liquid flowing in the other direction through the port 20c.

[0044] The expansion-side sub-valve EV allows the liquid to flow from the lower side to the upper side through the orifice O1 until the valve body 21 is deflected toward the valve seat member and the third leaf valve 21c faces the opposing seat 20b in the radial direction. The amount of deflection until the valve body 21 abuts against the annular valve seat 20e when functioning as a check valve and the amount of deflection until the third leaf valve 21c faces the opposing seat 20b can be adjusted by setting the height of the seating surfaces of the inner circumferential seat 20f and the annular valve seat 20e, but the amount of deflection may be adjusted by interposing a spacer between the inner circumferential seat 20f and the valve body 21. When a spacer is used, the height of the seating surface of the inner circumferential seat 20f may be made lower than the height of the seating surface of the annular valve seat 20e, and the amount of deflection may be adjusted by the number of stacked spacers.

[0045] The valve stopper 23 is laminated on the side of the spacer 22 opposite the valve seat member, and when the valve body 21 bends significantly, it comes into contact with the valve body 21 to support the valve body 21 and prevent excessive stress from acting on the valve body 21, thereby protecting the valve body 21.

[0046] A spacer 24 is stacked below the valve stopper 23 in Fig. 2. The spacer 24 is formed in a bottomed cylindrical shape, and a hole 24a is provided at the bottom to allow the small diameter portion 2a of the rod 2 to pass through. A notch 24c is provided in the cylindrical portion 24b to communicate the inside and outside, and the spacer 24 is fixed to the outer periphery of the small diameter portion 2a of the rod 2 with the opening side facing downward in Fig. 2. The cylindrical portion 24b faces the through holes 2e and 2f provided in the small diameter portion 2a in the radial direction, and the inside of the cylindrical portion 24b is connected to the inside of the rod 2. Since the spacer 24 is disposed on the side opposite the valve seat member of the valve body 21, the upper end of the spacer 24 may be used as a valve stopper, and the valve stopper 23 may be eliminated.

[0047] The partition member 25 is a bottomed cylinder, and has a hole 25a at the bottom that allows the small diameter portion 2a of the rod 2 to pass through. The partition member 25 is placed on the lower end of the spacer 24 in FIG. 2 with the opening facing upward, and is fixed to the outer periphery of the small diameter portion 2a of the rod 2 by fitting the cylindrical portion to the outer periphery of the valve seat member 20. The partition member 25 has an outer diameter smaller than the inner diameter of the cylinder 1, and forms an annular gap between the partition member 25 and the cylinder 1. The partition member 25 separates the space R3 into the contraction side chamber R2 together with the valve seat member 20. The space R3 is connected to the expansion side chamber R1 through a port 20c provided in the valve seat member 20, and is connected to the contraction side chamber R2 through the notch 24c of the spacer 24, the through holes 2e and 2f of the small diameter portion 2a, and the inside of the rod 2. The port 20c, the space R3, the through holes 2e, 2f, and the rod 2 form an expansion-side sub-passage EP as a damping passage that connects the expansion-side chamber R1 and the compression-side chamber R2. The expansion-side sub-passage EP thus configured connects the expansion-side chamber R1 and the compression-side chamber R2 in parallel with the expansion-side passage 3a provided in the piston 3. Therefore, the expansion-side sub-valve EV is provided in the expansion-side sub-passage EP that bypasses the expansion-side passage 3a and connects the expansion-side chamber R1 and the compression-side chamber R2.

[0048] In this embodiment, the compression side sub-valve CV as a damping valve is disposed between the partition member 25 and the compression side main valve 5 and is attached to the outer periphery of the small diameter portion 2a, as shown in Fig. 2. In detail, the compression side sub-valve CV includes a valve seat member 26 and a valve body 27.

[0049] The valve seat member 26 is annular and includes a partition body 26a in the shape of a disk with a hole that fits onto the outer periphery of the small diameter portion 2a, an annular opposing seat portion 26b that protrudes downward from the outer periphery of the lower end of the partition body 26a in FIG. 2, an annular groove 26c provided on the inner periphery of the partition body 26a, a plurality of ports 26d that open from the inner periphery side of the opposing seat portion 26b at the lower end of the partition body 26a in FIG. 2 and communicate with the annular groove 26c, and 2, an annular valve seat 26f provided at the lower end of partition body 26a in FIG. 2 so as to protrude downward from between opposing seat portion 26b and port 26d, an annular inner seat portion 26g provided on the inner circumference of window 26e, and a plurality of regulating portions 26h protruding in the axial direction from within window 26e of partition body 26a.

[0050] The facing seat 26b surrounds the outer periphery of the annular valve seat 26f and protrudes downward from the lower end of the annular valve seat 26f. That is, the height of the facing seat 26b is higher than the annular valve seat 26f when viewed from the partition body 26a, and the height difference between the facing seat 26b and the annular valve seat 26f is at least higher than the axial thickness of the valve body 27 described later. In addition, in the case of this embodiment, the inner circumference of the valve body 27 is a fixed end and the outer circumference is a free end, so that the annular valve seat 26f is provided on the inner circumference side of the facing seat 26b in the valve seat member 26 that is the fixed end side of the valve body 27 in the radial direction. In addition, the height of the seat surface of the inner circumference seat 26g, which is the lower end surface in FIG. 2, is higher than the height of the seat surface of the annular valve seat 26f, which is the lower end surface in FIG. 2, and is lower than the facing seat 26b.

[0051] In this embodiment, the opposing seat 26b and the annular valve seat 26f protrude axially as one unit with respect to the partition body 26a, and the annular valve seat 26f is provided adjacent to the inside of the opposing seat 26b. However, if the inner circumference side of the valve body 27 is a fixed end, the annular valve seat 26f may be spaced apart from the opposing seat 26b and protrude from the partition body 26a on the inner circumference side of the opposing seat 26b.

[0052] In addition, in the contraction side sub-valve CV, the valve seat member 26 is provided with a plurality of restricting portions 26h that protrude in the axial direction from the inner circumferential side, which is the lower end of the partition body 26a and is closer to the fixed end of the valve body 27 than the annular valve seat 26f in the radial direction. In this embodiment, the restricting portions 26h are provided between the annular valve seat 26f and the inner circumferential seat portion 26g and between the ports 26d, 26d in the window 26e in the circumferential direction of the partition body 26a, but the installation position of the restricting portions 26h can be arbitrarily changed in design as long as they are between the annular valve seat 26f and the inner circumferential seat portion 26g and do not interfere with the port 26d. In addition, the shape of the restricting portions 26h when the valve seat member 26 is viewed in the axial direction may be an arc shape or a circle, and can be arbitrarily changed in design. The restricting portion 26h is provided between the ports 26d, 26d, in order to avoid the port 26d, but is preferably provided at equal intervals on the same circumference in order to uniformly support the valve element 27 in the circumferential direction when the valve element 27 is deflected toward the valve seat member, but does not necessarily have to be provided at equal intervals on the same circumference as long as it can support the valve element 27. The height of the seating surface of the restricting portion 26h is the same as the seating surface of the annular valve seat 26f, but may be lower than that of the annular valve seat 26f as long as the valve element 27 can be supported by being in contact with the leaf valve 27a when seated on the annular valve seat 26f.

[0053] As shown in FIG. 2, the valve body 27 has an inner circumferential side fixed to the small diameter portion 2a as a fixed end and an outer circumferential side which is allowed to deflect as a free end, and is composed of a leaf valve 27a and two elastic annular plates 27b, 27c stacked on the leaf valve 27a. The valve body 27 is stacked on the lower end of the partition body 26a of the valve seat member 26 in FIG. 2 and fixed to the outer circumferential edge of the small diameter portion 2a.

[0054] The valve body 27 comprises a leaf valve 27a, which is annular, elastic, and located at the top in Figure 2, having a notch 27a1 opening from the outer periphery which serves as a free end, an annular plate 27b, which is annular, elastic, and stacked on the anti-valve seat member side of the leaf valve 27a and has a smaller outer diameter than the leaf valve 27a, and an annular plate 27c, which is annular, elastic, and stacked on the anti-valve seat member side of the annular plate 27b, and has a smaller outer diameter than the annular plate 27b.

[0055] In the valve body 27 thus configured, the space communicating with the port 26d on the valve seat member side of the valve body 27 is communicated with the expansion side chamber R1 on the opposite side of the valve body 27 to the valve seat member side by a notch 27a1 provided in the leaf valve 27a, and the notch 27a1 functions as an orifice O2.

[0056] When the valve body 27 thus configured is placed on the inner peripheral seat 26g of the partition body 26a of the valve seat member 26, the leaf valve 27a of the valve body 27 faces the opposing seat 26b in the radial direction, and faces the annular valve seat 26f with a gap in the axial direction because the inner peripheral seat 26g is higher than the annular valve seat 26f. In this way, the outer peripheral surface of the free end of the leaf valve 27a of the valve body 27 faces the inner peripheral surface of the opposing seat 26b of the valve seat member 26 with a small gap in the radial direction, so that when the leaf valve 27a faces the opposing seat 26b, the gap between the leaf valve 27a and the opposing seat 26b is extremely small, making it difficult for liquid to pass through the gap, and this state is the state in which the contraction-side sub-valve CV is closed. In this state in which the contraction-side sub-valve CV is closed, the passage of liquid is permitted almost exclusively through the orifice O2. Furthermore, as long as at least a portion of the outer peripheral surface on the free end side of the valve body 27 is radially opposed to the opposing seat portion 26b, the compression side sub-valve CV can open and close the port 26d, so it is not necessary for the entire outer peripheral surface of the leaf valve 27a to be radially opposed to the entire inner peripheral surface of the opposing seat portion 26b.

[0057] The spacer 28 stacked on the valve body 27 on the side opposite the valve seat member has an outer diameter smaller than that of the annular plate 27c arranged on the valve body 27 on the side opposite the valve seat member, and is fixed to the small diameter portion 2a. The spacer 28 is composed of one annular plate, but may be composed of multiple annular plates. Therefore, when the valve body 27 receives pressure from the upper side of the valve seat member 26 in FIG. 2, which is passing through the port 26d downward, the outer periphery of the spacer 28 is deflected downward in FIG. 2 with the outer periphery of the spacer 28 as a fulcrum. Then, the outer periphery of the leaf valve 27a is no longer directly opposite the inner periphery of the facing seat portion 26b in the radial direction, and is shifted downward with respect to the facing seat portion 26b, and the area of ​​the flow path formed by the gap between the leaf valve 27a and the facing seat portion 26b is increased according to the amount of deflection of the leaf valve 27a. When the leaf valve 27a and the opposing seat 26b are misaligned in this manner and no longer face each other directly, the compression side sub-valve CV opens, and the compression side sub-valve CV provides resistance to the flow of liquid while allowing the liquid to flow through the gap via the valve body 27.

[0058] When the valve element 27 receives pressure from the lower part of the valve seat member 26 in FIG. 2 of the liquid passing through the port 26d in an upward direction, the valve element 27 bends the outer circumferential side upward in FIG. 2 with the inner circumferential edge of the inner circumferential seat portion 26g of the valve seat member 26 as a fulcrum. When the valve element 27 bends by a preset amount or more, the leaf valve 27a seats on the annular valve seat 26f and maintains a state in which the port 26d communicates with the expansion-side chamber R1 only through the orifice O2. In other words, even if the leaf valve 27a is placed in a closed state facing the opposing seat portion 26b in the radial direction and is placed in a closed state by the pressure of the liquid passing through the port 26d in an upward direction from the lower part of the valve seat member 26 in FIG. 2 of the valve seat member 26, and the leaf valve 27a seats on the annular valve seat 26f, the contraction-side sub-valve CV communicates between the expansion-side chamber R1 and the port 26d through the orifice O2, thereby limiting the flow path area. In this way, when liquid flows from top to bottom through port 26d in Fig. 2, the free end of the valve element 27 bends toward the side opposite to the valve seat member to open and allow the liquid to flow, and conversely, when liquid flows from bottom to top through port 26d in Fig. 2, the free end of the valve element 27 bends toward the valve seat member to seat on the annular valve seat 26f and provide resistance to the liquid flow through the orifice O2. In this way, the compression side sub-valve CV functions as a damping valve that opens to allow and provide resistance to the flow of liquid flowing in one direction through port 26d, and conversely, functions as a check valve that activates only the orifice O2 for the flow of liquid flowing in the other direction through port 26d.

[0059] The compression side sub-valve CV allows liquid to flow from the lower side to the upper side through the port 26d until the valve element 27 bends toward the valve seat member and seats on the annular valve seat 26f. The amount of bending of the valve element 27 until it abuts on the annular valve seat 26f can be adjusted by setting the height of the seating surfaces of the inner circumferential seat portion 26g and the annular valve seat 26f, but the amount of bending may also be adjusted by interposing a spacer between the inner circumferential seat portion 26g and the valve element 27. When a spacer is used, the height of the seating surface of the inner circumferential seat portion 26g may be made lower than the height of the seating surface of the annular valve seat 26f, and the amount of bending may be adjusted by the number of stacked spacers.

[0060] The valve stopper 29 is laminated on the side of the spacer 28 opposite the valve seat member, and when the valve element 27 bends significantly, it comes into contact with the valve element 27 to support the valve element 27 and prevent excessive stress from acting on the valve element 27, thereby protecting the valve element 27.

[0061] When the compression side sub-valve CV configured in this manner is stacked on the outer periphery of the small diameter portion 2a and below the spacer 24, the annular groove 26c formed on the inner periphery of the valve seat member 26 faces the through holes 2g and 2h provided in the small diameter portion 2a in the radial direction, so that the port 26d is communicated with the inside of the rod 2. Therefore, the expansion side chamber R1 is communicated with the compression side chamber R2 through the port 26d, the through holes 2g and 2h, and the inside of the rod 2. The port 26d, the through holes 2g and 2h, and the inside of the rod 2 form a compression side sub-passage CP as a damping passage that communicates the expansion side chamber R1 and the compression side chamber R2. The compression side sub-passage CP configured in this manner is parallel to the compression side passage 3b provided in the piston 3 and communicates the expansion side chamber R1 and the compression side chamber R2. Therefore, the compression side sub-valve CV is provided in the compression side sub-passage CP that bypasses the compression side passage 3b and communicates the expansion side chamber R1 and the compression side chamber R2.

[0062] Next, a cylindrical rotary valve 12 is housed within the rod 2, with its outer circumferential surface in sliding contact with the inner circumferential surface of the rod 2, and is allowed to rotate in the circumferential direction within the rod 2. The rotary valve 12 has holes 12a, 12b, 12c, and 12d that communicate with the inside and outside at positions that can face the through holes 2e, 2f, 2g, and 2h, respectively, and when rotated by a control rod 13 inserted within the rod 2, the degree of communication between the through hole 2e and the hole 12a, the through hole 2f and the hole 12b, the through hole 2g and the hole 12c, and the through hole 2h and the hole 12d can be changed, and the through holes 2e, 2f, 2g, and 2h can be blocked without facing the holes 12a, 12b, 12c, and 12d. In other words, the rotary valve 12 can adjust the areas of the four flow passages consisting of the through hole 2e and the hole 12a, the through hole 2f and the hole 12b, the through hole 2g and the hole 12c, and the through hole 2h and the hole 12d depending on the circumferential rotation position relative to the rod 2, and can adjust the resistance to the flow of hydraulic oil passing through the flow passages. In this embodiment, the control rod 13 is driven by a rotary actuator (not shown) such as a stepping motor attached to the tip of the rod 2, but the rotary actuator may be housed within the rod 2.

[0063] When the rotary valve 12 communicates the corresponding holes 12a, 12b with the through holes 2e, 2f, the expansion-side chamber R1 communicates with the compression-side chamber R2 through the expansion-side sub-passage EP. When the rotary valve 12 communicates the corresponding holes 12c, 12d with the through holes 2g, 2h, the expansion-side chamber R1 communicates with the compression-side chamber R2 through the compression-side sub-passage CP. In this way, the rotary valve 12 is provided in the middle of the expansion-side sub-passage EP and the compression-side sub-passage CP, and when rotated by the control rod 13, the degree of communication (flow path area) between the holes 12a, 12b, 12c, 12d and the corresponding through holes 2e, 2f, 2g, 2h can be changed to change the resistance to the flow of the liquid passing through the expansion-side sub-passage EP and the compression-side sub-passage CP. The rotary valve 12 has two holes 12a, 12b for adjusting the flow area of ​​the expansion-side sub-passage EP and two holes 12c, 12d for adjusting the flow area of ​​the compression-side sub-passage CP, but the number of holes can be changed as desired according to the setting of the maximum flow area. The number of through holes in the rod 2 may be set in accordance with the number of holes in the rotary valve 12. Furthermore, the holes 12a, 12b, 12c, and 12d in the rotary valve 12 may be offset in the circumferential direction, and the through holes 2e, 2f, 2g, and 2h in the rod 2 may be positioned appropriately in accordance with the holes 12a, 12b, 12c, and 12d. In addition, depending on the damping force characteristics desired for the shock absorber D, the hole 12b and the through hole 2f may be made to communicate with each other when the hole 12a and the through hole 2e provided in the middle of the extension side sub-passage EP face each other and communicate with each other, or the hole 12b and the through hole 2f may be set to face each other at a timing different from the timing at which the hole 12a and the through hole 2e face each other, and the same applies to the relationship between the holes 12c, 12d and the through holes 2g, 2h provided in the middle of the compression side sub-passage CP.

[0064] The expansion side sub-valve EV and the compression side sub-valve CV, which serve as damping valves, and the shock absorber D are configured as described above. Below, the operation of the expansion side sub-valve EV and the compression side sub-valve CV, which serve as damping valves, and the shock absorber D will be described.

[0065] First, when the shock absorber D expands, the piston 3 moves upward in the cylinder 1 in FIG. 1 to compress the expansion-side chamber R1. When the expansion-side sub-passage EP and the compression-side sub-passage CP are in communication with each other through the rotary valve 12, the liquid in the expansion-side chamber R1 compressed by the upward movement of the piston 3 tries to move to the expanding compression-side chamber R2 through the expansion-side sub-passage EP together with the expansion-side passage 3a provided in the piston 3. Here, when the expansion speed of the shock absorber D is in the extremely low speed range and close to 0, the pressure in the expansion-side chamber R1 increases, but the differential pressure between the pressure in the expansion-side chamber R1 and the pressure in the compression-side chamber R2 does not reach the opening pressure of the expansion-side main valve 4, so the expansion-side main valve 4 does not open and keeps the expansion-side passage 3a closed. The compression-side main valve 5 receives the pressure in the expansion-side chamber R1 from the back side and closes the compression-side passage 3b.

[0066] When the piston speed during the extension operation of the shock absorber D is close to 0, the pressure in the expansion-side chamber R1 rises, but the pressure difference between the expansion-side chamber R1 and the compression-side chamber R2 does not reach the valve-opening pressure of the valve body 21 in the expansion-side sub-valve EV. Therefore, even if the valve body 21 bends, the outer peripheral surface of the first leaf valve 21a faces the axial width range of the inner circumference of the opposing seat 20b, thereby closing the valve. The flow path area in the annular gap between the valve body 21 and the opposing seat 20b is kept extremely small, and the expansion-side chamber R1 is connected to the port 20c almost exclusively through the orifice O1.

[0067] On the other hand, when the extension speed of the shock absorber D is in the extremely low speed range and close to 0, the pressure in the expansion-side chamber R1 rises, but the pressure difference between the pressure in the expansion-side chamber R1 and the pressure in the contraction-side chamber R2 is small, so the valve element 27 in the compression-side sub-valve CV does not bend toward the valve seat member until it seats on the annular valve seat 26f. In this way, when the extension speed of the shock absorber D is in the extremely low speed range and close to 0, the valve element 27 remains closed by facing the outer circumferential surface of the leaf valve 27a within the axial width range of the inner circumferential surface of the facing seat 26b, and the flow passage area in the annular gap between the valve element 27 and the facing seat 26b is kept extremely small, and the expansion-side chamber R1 is communicated with the port 26d almost only by the orifice O2.

[0068] Therefore, when the extension speed of the shock absorber D is in the very low speed range and close to 0, the extension-side main valve 4 also keeps the extension-side passage 3a closed, so that the liquid in the extension-side chamber R1 passes through the orifice O1 in the extension-side sub-passage EP and passes through the orifice O2 in the compression-side sub-passage CP to move to the compression-side chamber R2 because the extension-side sub-valve EV and the compression-side sub-valve CV are kept closed. Therefore, when the extension speed of the shock absorber D is in the very low speed range and close to 0, a damping force is generated by the resistance given when the liquid passes through the orifices O1 and O2, so that the characteristic of the damping force generated with respect to the piston speed of the shock absorber D (damping force characteristic) is a characteristic in which the damping force rises without becoming excessive, as shown in FIG.

[0069] Furthermore, when the piston speed during the expansion operation of the shock absorber D increases and changes from the very low speed range to the low speed range, the pressure difference between the pressure in the expansion-side chamber R1 and the pressure in the contraction-side chamber R2 exceeds the valve-opening pressure of the valve body 21, so that the valve body 21 bends and opens by shifting its outer periphery downward in FIG. 2 from the range of the axial width of the inner periphery of the opposing seat portion 20b, making the flow path area of ​​the annular gap between the valve body 21 and the opposing seat portion 20b larger than the flow path area of ​​the orifice O1. Then, the liquid passes through the expansion-side sub-valve EV and moves from the expansion-side chamber R1 to the contraction-side chamber R2 through the expansion-side sub-passage EP. On the other hand, when the piston speed during the extension operation of the shock absorber D increases and changes from the very low speed range to the low speed range, the valve element 27 of the compression side sub-valve CV is deflected by the pressure in the expansion side chamber R1 and seats on the annular valve seat 26f of the valve seat member 26. As a result, the port 26d is kept in communication with the expansion side chamber R1 only through the orifice O2, and the liquid is allowed to pass through the compression side sub-passage CP. However, the flow path area of ​​the expansion side sub-valve EV is larger than the flow path area of ​​the orifice O2.

[0070] Therefore, when the piston speed during the extension operation of the shock absorber D increases and changes from the very low speed range to the low speed range, the damping force is generated mainly by the valve body 21 and the opposing seat 20b of the extension side sub-valve EV, and the flow path area of ​​the extension side sub-valve EV increases in response to the increase in the piston speed. As a result, the damping force characteristic of the shock absorber D becomes a characteristic with a smaller slope than the damping force characteristic line in the very low speed range, as shown in FIG. 4.

[0071] Furthermore, when the piston speed during the extension operation of the shock absorber D increases and exceeds the low-speed range, the valve body 21 is largely deflected and abuts against the valve stopper 23, maximizing the flow passage area in the annular gap between the opposing seat 20b, while the extension-side main valve 4 is deflected and separated from the piston 3 to open the extension-side passage 3a. Then, the liquid moves from the extension-side chamber R1 to the compression-side chamber R2 through the gap between the extension-side main valve 4 and the piston 3, and the deflection amount of the extension-side main valve 4 increases due to the increase in the piston speed, and the flow passage area in the gap between the extension-side main valve 4 and the piston 3 becomes larger than the flow passage area in the annular gap between the valve body 21 and the opposing seat 20b in the extension-side sub-valve EV. Therefore, the shock absorber D generates a damping force mainly by the resistance that the extension-side main valve 4 provides to the flow of the liquid. Therefore, when the piston speed during the extension operation of the shock absorber D increases and exceeds the low-speed range, the damping force characteristic of the shock absorber D becomes a characteristic that generates a damping force with a substantially constant slope with respect to the increase in the piston speed as shown in FIG. 4. Since the resistance to the flow of liquid passing through the extension-side sub-passage EP can be adjusted by rotating the rotary valve 12, the damping force of the shock absorber D of this embodiment can be adjusted to a high or low level. During extension of the shock absorber D, the rod 2 retreats from the cylinder 1, but the free piston 11 moves upward in FIG. 2 within the cylinder 1 to expand the air chamber G and compensate for the volume of the rod 2 retreated from the cylinder 1.

[0072] Next, when the shock absorber D contracts, the piston 3 moves downward in FIG. 1 inside the cylinder 1 to compress the compression side chamber R2. When the expansion side sub-passage EP and the compression side sub-passage CP are in communication with each other through the rotary valve 12, the liquid in the compression side chamber R2 compressed by the downward movement of the piston 3 tries to move to the expanding expansion side chamber R1 through the compression side sub-passage CP together with the compression side passage 3b provided in the piston 3. Here, when the contraction speed of the shock absorber D is in the extremely low speed range and close to 0, the pressure in the compression side chamber R2 rises, but the pressure difference between the pressure in the compression side chamber R2 and the pressure in the expansion side chamber R1 does not reach the opening pressure of the compression side main valve 5, so the compression side main valve 5 does not open and keeps the compression side passage 3b closed. The expansion side main valve 4 receives the pressure of the compression side chamber R2 from the back side and closes the expansion side passage 3a.

[0073] When the piston speed during the contraction operation of the shock absorber D is close to 0, the pressure in the compression side chamber R2 rises, but the pressure difference between the pressure in the expansion side chamber R1 does not reach the valve opening pressure of the valve body 27 in the compression side sub-valve CV. Therefore, even if the valve body 27 bends, the outer peripheral surface of the leaf valve 27a faces the range of the axial width of the inner circumference of the opposing seat 26b, thereby entering a closed state. The flow path area in the annular gap between the valve body 27 and the opposing seat 26b is kept extremely small, and the expansion side chamber R1 is connected to the port 26d almost exclusively by the orifice O2.

[0074] On the other hand, when the contraction speed of the shock absorber D is in the extremely low speed range and close to 0, the pressure in the contraction side chamber R2 rises, but the pressure difference between the pressure in the contraction side chamber R2 and the pressure in the expansion side chamber R1 is small, so the valve element 21 in the expansion side sub-valve EV does not bend toward the valve seat member until it is seated on the annular valve seat 20e. In this way, when the contraction speed of the shock absorber D is in the extremely low speed range and close to 0, the valve element 21 faces the outer peripheral surface of the first leaf valve 21a within the axial width range of the inner circumference of the opposing seat portion 20b, and remains closed, so that the flow passage area in the annular gap between the valve element 21 and the opposing seat portion 20b is kept extremely small, and the expansion side chamber R1 is communicated with the port 20c almost only by the orifice O1.

[0075] Therefore, when the contraction speed of the shock absorber D is in the very low speed range and close to 0, the compression side main valve 5 also keeps the compression side passage 3b closed, so that the liquid in the compression side chamber R2 passes through the orifice O2 in the compression side sub-passage CP and passes through the orifice O1 in the expansion side sub-passage EP to move to the expansion side chamber R1 because the expansion side sub-valve EV and the compression side sub-valve CV keep closed. Therefore, when the contraction speed of the shock absorber D is in the very low speed range and close to 0, a damping force is generated by the resistance given when the liquid passes through the orifices O1 and O2, so that the characteristic of the damping force generated with respect to the piston speed of the shock absorber D (damping force characteristic) is a characteristic that the damping force rises without becoming excessive, as shown in FIG.

[0076] Furthermore, when the piston speed during the contraction operation of the shock absorber D increases and changes from the very low speed region to the low speed region, the pressure difference between the pressure in the compression side chamber R2 and the pressure in the expansion side chamber R1 exceeds the valve opening pressure of the valve body 27, so that the valve body 27 opens by bending so that the outer periphery of the valve body 27 is shifted downward in FIG. 2 from the range of the axial width of the inner periphery of the opposing seat portion 26b, and the flow passage area of ​​the annular gap between the valve body 27 and the opposing seat portion 26b becomes larger than the flow passage area of ​​the orifice O2. Then, the liquid passes through the annular gap between the leaf valve 27a and the opposing seat portion 26b in the contraction side sub-valve CV, passes through the contraction side sub-passage CP, and moves from the contraction side chamber R2 to the expansion side chamber R1. On the other hand, when the piston speed during the contraction operation of the shock absorber D increases and changes from the very low speed region to the low speed region, the valve body 21 in the expansion side sub-valve EV is bent by the pressure in the compression side chamber R2 and seats on the annular valve seat 20e of the valve seat member 20. Then, the outer periphery of the third leaf valve 21c stacked on the side opposite to the valve seat member of the second leaf valve 21b having the notch 21b1 faces the opposing seat portion 20b in the radial direction, and the annular gap between the third leaf valve 21c and the opposing seat portion 20b is made extremely small, making it difficult for liquid to pass through the gap between the third leaf valve 21c and the opposing seat portion 20b. Therefore, when the contraction speed of the shock absorber D reaches the low speed range, the expansion-side sub-valve EV closes the opening of the port 26d to prevent liquid from passing through the compression-side sub-passage CP.

[0077] In this manner, when the piston speed during the contraction operation of the shock absorber D increases and changes from the very low speed range to the low speed range, the compression side sub-valve CV makes its flow passage area larger than the flow passage area of ​​the orifice O2, and the expansion side sub-valve EV functions as a check valve to close the expansion side sub-passage EP.

[0078] Therefore, when the piston speed during the contraction operation of the shock absorber D increases and changes from the very low speed range to the low speed range, the damping force is generated mainly by the valve body 27 and the opposing seat 26b in the compression side sub-valve CV, and the flow path area in the compression side sub-valve CV increases in response to the increase in the piston speed, so that the damping force characteristics of the shock absorber D have a slope smaller than that of the damping force characteristic line in the very low speed range, as shown in Figure 4.

[0079] Furthermore, when the piston speed during the contraction operation of the shock absorber D increases and exceeds the low-speed range, the valve body 27 is largely deflected and abuts against the valve stopper 29, maximizing the flow path area in the annular gap between the opposing seat portion 26b, while the contraction-side main valve 5 is deflected and separated from the piston 3 to open the contraction-side passage 3b. Then, the liquid moves from the contraction-side chamber R2 to the extension-side chamber R1 through the gap between the contraction-side main valve 5 and the piston 3, and the deflection amount of the contraction-side main valve 5 increases due to the increase in the piston speed, so that the flow path area in the gap between the contraction-side main valve 5 and the piston 3 becomes larger than the flow path area in the annular gap between the valve body 27 and the opposing seat portion 26b in the contraction-side sub-valve CV. Therefore, the shock absorber D generates a damping force mainly due to the resistance that the contraction-side main valve 5 provides to the flow of the liquid. Therefore, when the piston speed during the contraction operation of the shock absorber D increases and exceeds the low-speed range, the damping force characteristic of the shock absorber D becomes a characteristic that generates a damping force with a substantially constant slope with respect to the increase in the piston speed as shown in FIG. 4. Since the resistance to the flow of liquid passing through the compression side sub-passage CP can be adjusted by rotating the rotary valve 12, the damping force of the shock absorber D in this embodiment can be adjusted to a high or low level. When the shock absorber D is contracting, the rod 2 enters the cylinder 1, and the free piston 11 moves downward in FIG. 2 within the cylinder 1 to reduce the air chamber G and compensate for the volume of the rod 2 that has entered the cylinder 1.

[0080] As described above, the extension side sub-valve EV and the compression side sub-valve CV as damping valves in this embodiment include annular valve disc 21, 27 whose inner periphery is a fixed end and whose outer periphery is a free end that is allowed to bend relative to the fixed end, annular opposing seats 20b, 26b that are annular and face at least a part of the circumferential surface on the free end side of the valve disc 21, 27, and valve seat members 20, 26 having ports 20c, 26d provided radially closer to the fixed end side of the valve disc 21, 27 than the opposing seats 20b, 26b, and orifices O1, O2 provided in the valve disc 21, 27 to communicate between the valve seat member side and the anti-valve seat member side of the valve disc 21, 27 with the valve disc 21, 27 and the opposing seats 20b, 26b facing each other.

[0081] With the extension side sub-valve EV and the compression side sub-valve CV as the damping valves configured in this manner, even if the free ends of the valve bodies 21 and 27 face the opposing seats 20b and 26b, liquid can pass through the orifices O1 and O2 in places other than the gaps between the valve bodies 21 and 27 and the opposing seats 20b and 26b. Therefore, with the extension side sub-valve EV and the compression side sub-valve CV as the damping valves, even if the flexural rigidity of the valve bodies 21 and 27 is set high, the damping force does not become excessive when the expansion / contraction speed of the shock absorber D is in the extremely low speed range. Furthermore, with the extension side sub-valve EV and the compression side sub-valve CV as the damping valves, even if the flexural rigidity of the valve bodies 21 and 27 is set high, the damping force does not become excessive when the expansion / contraction speed of the shock absorber D is in the extremely low speed range. Therefore, the design freedom of the flexural rigidity of the valve bodies 21 and 27 is improved, and it becomes easier to obtain the desired damping force characteristics.

[0082] In addition, the extension side sub-valve EV and the compression side sub-valve CV as damping valves in the present embodiment described above open and open the ports 20c, 26d when the valve bodies 21, 27 are deflected toward the side opposite the valve seat member, and seat on the annular valve seats 20e, 26f to function as check valves when the valve bodies 21, 27 are deflected toward the valve seat member side. However, as in the valve disclosed in JP 2019-183918, the annular valve seats 20e, 26f may be eliminated and the ports 20c, 26d may be opened whether the valve bodies 21, 27 are deflected toward the valve seat member side or toward the side opposite the valve seat member side.

[0083] In addition, the valve seat members 20, 26 in the extension side sub-valve EV and the compression side sub-valve CV as the damping valves in this embodiment are provided between the opposing seat portions 20b, 26b and the ports 20c, 26d and include annular valve seats 20e, 26f that face the valve bodies 21, 27 in the axial direction and allow the valve bodies 21, 27 to be seated on and off. According to the extension side sub-valve EV and the compression side sub-valve CV configured as described above as damping valves, when pressure is applied from the port 20c, 26d side, the valve elements 21, 27 bend to open the port 20c, 26d and provide resistance to the flow of liquid passing through the port 20c, 26d. When pressure is applied to the valve elements 21, 27 toward the valve seat members 20, 26, the valve elements 21, 27 seat on the annular valve seats 20e, 26f to block the port 20c, 26d. Therefore, the extension side sub-valve EV and the compression side sub-valve CV function as damping valves for the flow of liquid passing through the port 20c, 26d in one direction and function as a check valve for the flow of liquid passing through the port 20c, 26d in the other direction.

[0084] Furthermore, the valve body 21 in the expansion side sub-valve EV as a damping valve in this embodiment includes a first leaf valve 21a which is annular and has an outer periphery, which is the peripheral surface of a free end, facing the opposing seat portion 20b and has a hole 21a1 penetrating in the axial direction so as to be able to seat on and separate from the annular valve seat 20e, a second leaf valve 21b which is annular and stacked on the anti-valve seat member side of the first leaf valve 21a and has a notch 21b1 which opens from the outer periphery, which is the free end, and communicates with the hole 21a1, and a third leaf valve 21c which is annular and stacked on the anti-valve seat member side of the second leaf valve 21b, and an orifice O1 is formed by the notch 21b1. According to the extension-side sub-valve EV as a damping valve configured in this manner, when the valve element 21 bends toward the opposite side to the valve seat member 20 so as to move away from the valve seat member 20, the valve element 21 functions as a damping valve by providing resistance to the flow of liquid passing through the gap between the valve element 21 and the opposing seat portion 20b, and when the valve element 21 bends toward the valve seat member side and seats on the annular valve seat 20e, the outer periphery, which is the free end of the third leaf valve 21c, faces the opposing seat portion 20b directly, minimizing the gap between the third leaf valve 21c and the opposing seat portion 20b and making it difficult for liquid to pass through the gap, so that when functioning as a check valve, the port 20c can be substantially closed even if the orifice O1 is provided. Therefore, according to the extension-side sub-valve EV as a damping valve configured in this manner, when functioning as a check valve, the port 20c can be substantially closed even if the orifice O1 is provided, so that the damping force characteristic of the extension side of the shock absorber D can be set independently.

[0085] Furthermore, the valve element 27 in the compression side sub-valve CV as a damping valve may be annular, with the peripheral surface of the outer periphery, which is the free end, facing the opposing seat portion 26b, and may be provided with a notch 27a1 opening from the outer periphery, which is the free end, and the orifice O2 may be formed by the notch 27a1. In this way, when the compression side sub-valve CV functions as a check valve, if it is not necessary to completely close the port 26d with the valve element 27, and if the port 26d is opened whether the valve element 27 is deflected toward the valve seat member side or toward the anti-valve seat member side, it is sufficient to provide a notch that forms the orifice O2 at the free end of the valve element 27, which makes it easy to provide the orifice O2. In addition, in the case where the orifice O2 is provided by providing the notch 27a1 on the outer periphery of the valve body 27, and it is desired to shut off the port 26d when the valve body 27 is seated on the annular valve seat 26f, the depth of the notch 27a1 may be set to such a depth that the tip of the notch 27a1 does not face the port 26d when the valve body 27 is seated on the annular valve seat 26f. In this way, when the valve body 27 receives the pressure of the expansion-side chamber R1 from the back side and sits on the annular valve seat 26f, the communication between the notch 27a1 and the port 26d is cut off, and the port 26d can be shut off by the valve body 27. In this way, even when the orifice O2 is formed by providing the notch 27a1 on the free end of the valve body 27, it is also possible to completely shut off the port 26d by the valve body 27.

[0086] Furthermore, as shown in FIG. 5, the orifice may be formed by a groove 26b1 provided in the opposing seat portion 26b of the valve seat member 26, instead of providing it in the valve element 27. When the extension side sub-valve EV and the compression side sub-valve CV as damping valves function as check valves, if it is not necessary to completely close the port 26d by the valve element 27 and the port 26d is to be opened whether the valve element 27 is deflected toward the valve seat member side or toward the anti-valve seat member side, it is sufficient to provide the groove 26b1 forming the orifice in the opposing seat portion 26b, which makes it easy to provide the orifice.

[0087] In the above description, the inner circumferential side of the valve body 21, 27 is the fixed end, the outer circumferential side is the free end, and the outer circumferential surface of the valve body 21, 27 is opposed to the inner circumferential surface of the opposed seat portion 20b, 26b to constitute the extension side sub-valve EV and the compression side sub-valve CV as the damping valve, but the damping valve may be constituted by setting the outer circumferential side of the valve body as the fixed end, the inner circumferential side as the free end, providing the opposed seat portion on the inner circumferential side of the valve body, and opposing the inner circumferential surface of the valve body to the outer circumferential surface of the opposed seat portion. In that case, the orifice may be formed by a notch that opens from the inner circumferential side of the valve body.

[0088] In addition, the valve seat member 26 in the compression side sub-valve CV as a damping valve in this embodiment is provided with a regulating portion 26h that is provided radially closer to the fixed end of the valve body 27 than the annular valve seat 26f, faces the valve body 27 in the axial direction, and abuts against the valve body 27 to regulate the deflection of the valve body 27 when the free end of the valve body 27 deflects toward the valve seat member by more than a predetermined amount.

[0089] According to the compression side sub-valve CV configured as above as a damping valve, when the middle portion of the valve body 27 is pressed toward the valve seat member and bends to come into contact with the regulating portion 26h, the middle portion of the valve body 27 is supported by the regulating portion 26h and the valve body 27 is prevented from bending further. Therefore, even if excessive pressure acts on the valve body 27, the stress on the leaf valve 27a can be reduced and fatigue of the leaf valve 27a can be suppressed.

[0090] The shock absorber D of this embodiment includes a cylinder (outer tube) 1, a rod 2 inserted axially movably into the cylinder (outer tube) 1, a shock absorber body A having at least an extension-side chamber (operating chamber) R1 and a compression-side chamber (operating chamber) R2 through which liquid flows by the movement of the rod 2 relative to the cylinder (outer tube) 1, and an extension-side sub-valve EV and a compression-side sub-valve CV as damping valves provided between the extension-side chamber (operating chamber) R1 and the compression-side chamber (operating chamber) R2. Since the shock absorber D configured in this manner includes the extension-side sub-valve EV and the compression-side sub-valve CV, it is possible to suppress the damping force from becoming excessive in the extremely low speed range of the expansion / contraction speed of the shock absorber D, and to improve the ride comfort of the vehicle. In addition, since a damping force is generated when the liquid flows from the expansion side chamber R1 to the compression side chamber R2, and the expansion side sub-passage EP can be closed when the liquid flows from the compression side chamber R2 to the expansion side chamber R1, the damping force characteristics of the expansion side of the shock absorber D can be set independently. The compression side sub-valve CV generates a damping force when the liquid flows from the compression side chamber R2 to the expansion side chamber R1, and provides resistance at the orifice O2 when the liquid flows from the expansion side chamber R1 to the compression side chamber R2, so that the damping force characteristics of the compression side of the shock absorber D can be set independently.

[0091] In the shock absorber D of this embodiment, the extension side sub-valve EV and the compression side sub-valve CV as damping valves are provided in the extension side sub-passage EP and the compression side sub-passage CP that bypass the extension side passage 3a and the compression side passage 3b in the piston 3, and the damping valves are arranged in parallel with the extension side main valve 4 and the compression side main valve 5 in the piston 3, but the damping valves may be used as the extension side main valve or the compression side main valve. Also, in the shock absorber D of this embodiment, the extension side sub-valve EV and the compression side sub-valve CV as damping valves are provided in the extension side sub-passage EP and the compression side sub-passage CP that bypass the extension side passage 3a and the compression side passage 3b in the piston 3, but the shock absorber D may be provided with only the extension side sub-valve EV or only the compression side sub-valve CV.

[0092] In addition, in the example shown in Fig. 1, the two working chambers are the expansion-side chamber R1 and the compression-side chamber R2, but in the case where the shock absorber D is a double-tube shock absorber having an outer shell as an outer tube on the outer periphery of the cylinder and a reservoir between the cylinder and the outer shell, a damping valve DV may be provided between the compression-side chamber and the reservoir. Therefore, the port in the damping valve may communicate between the expansion-side chamber R1 and the compression-side chamber R2, or may communicate between the compression-side chamber and the reservoir.

[0093] In the shock absorber D of this embodiment, the speed range in which damping force is generated mainly by the extension side sub-valve EV and the compression side sub-valve CV as damping valves is set to the low speed range. However, the speeds that divide the extremely low speed, the low speed, and the high speed that exceeds the low speed can be arbitrarily set by the designer.

[0094] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0095] 1···Cylinder (outer tube), 2···Rod, 20, 26···Valve seat member, 20b, 26b···Opposite seat portion, 26b1···Groove, 20c, 26d···Port, 20e, 26f···Annular valve seat, 26h···Restriction portion, 21, 27···Valve body, 21a···First leaf valve, 21b···Second leaf valve, 21b1, 27a1···Notch, 21c···Third leaf valve, A···Shock absorber body, CV···Compression side sub-valve (damping valve) D···Shock absorber, EV···Extension side sub-valve (damping valve), O1, O2···Orifice, R1···Extension side chamber (operating chamber), R2···Compression side chamber (operating chamber)

Claims

1. an annular valve body having one of its inner periphery and outer periphery as a fixed end and the other of its inner periphery and outer periphery as a free end, the free end being allowed to bend relative to the fixed end; a valve seat member having an annular opposing seat portion opposing at least a portion of a peripheral surface of the valve body on the free end side, and a port provided radially closer to the fixed end side of the valve body than the opposing seat portion; an orifice provided in the valve body or the valve seat member, which communicates between the valve seat member side and the opposite valve seat member side of the valve body in a state where the valve body and the opposing seat portion are directly opposite each other; A damping valve characterized by:

2. The valve seat member is an annular valve seat that is provided between the opposing seat portion and the port and that faces the valve body in the axial direction and allows the valve body to be seated and separated; 2. The damping valve of claim 1.

3. The valve body is a first leaf valve having an annular shape with a peripheral surface of a free end facing the opposing seat portion and having a hole penetrating in the axial direction, the first leaf valve being capable of being seated on and removed from the annular valve seat; a second leaf valve having an annular shape, stacked on the side of the first leaf valve opposite the valve seat member, and having a notch that opens from a free end and communicates with the hole; a third leaf valve that is annular and is stacked on the opposite side of the second leaf valve from the valve seat member, The orifice is formed by the notch.

3. The damping valve according to claim 2.

4. The valve body is The seat has a circular free end, the peripheral surface of which faces the opposing seat portion, and a notch that opens from the free end. The orifice is formed by the notch.

2. The damping valve of claim 1.

5. the valve seat member has a groove formed in the opposing seat portion, The orifice is formed by the groove.

2. The damping valve of claim 1.

6. When the valve body is bent and displaced axially from the opposing seat, the valve opens and provides resistance to the flow of liquid flowing through the gap between the valve body and the opposing seat.

2. The damping valve of claim 1.

7. A gap is provided between the valve body and the annular valve seat.

3. The damping valve according to claim 2.

8. The gap formed between the peripheral surface of the free end side of the valve body and the opposing seat portion is narrower than the gap between the valve body and the annular valve seat.

8. The damping valve of claim 7.

9. a shock absorber body having an outer tube, a rod inserted into the outer tube so as to be movable in an axial direction, and at least two working chambers through which liquid flows as the rod moves relative to the outer tube; and a damping valve according to any one of claims 1 to 8, which is provided between the operating chambers. A shock absorber characterized by:

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