Damping valves and shock absorbers

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; and 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, a port 20c, 26d provided closer to the fixed end of the valve body 21, 27 than the opposing seat part 20b, 26b, and an annular valve seat 20e, 26f which can sit on / leave the valve body 21, 27 while facing the valve body 21, 27 in an axial direction. The valve body 21,27 includes an annular leaf valve 21a, 27a, and an annular backup valve 21b, 27b which is overlapped with a side of the leaf valve 21a, 27a closer to the valve seat member, and restrains bending of a free end of the leaf valve 21a, 27a toward the valve seat member.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] A shock absorber is interposed between a vehicle body and a wheel in a vehicle, for example, for the purpose of improving the riding comfort in the vehicle, and suppresses the vibrations of the vehicle body and the wheel by the damping force exerted during expansion and contraction.

[0003] Such a shock absorber includes, for example, a cylinder, a rod movably inserted into the cylinder, a piston slidably inserted into the cylinder and partitioning the inside of the cylinder into an extension chamber and a compression chamber, a free piston slidably inserted into the cylinder and partitioning an air chamber below the compression chamber inside the cylinder, a damping passage provided in the piston and communicating the extension chamber and the compression chamber, and a damping valve provided in the damping passage.

[0004] In recent years, for shock absorbers for vehicles, in order to improve the riding comfort in the vehicle, the damping coefficient is increased in the very low speed range where the expansion and contraction speed is lower than the low speed, and the damping force is quickly raised against the switching of the expansion and contraction stroke. In the low speed range, the damping coefficient is made smaller than that in the very low speed range. Further, in the medium and high speed range exceeding the low speed, it is desired to exhibit a damping force characteristic that is proportional to the expansion and contraction speed but has a smaller damping coefficient than that in the low speed range.

[0005] In order to meet such a demand, the damping valve includes a leaf valve that is annular and has its inner peripheral side fixed and allows the outer peripheral side to flex, an annular opposing seat portion that is annular and faces the outer periphery of the leaf valve without contact, and a valve seat member having a port on the inner peripheral side of the opposing seat portion, and gives resistance to the flow of the hydraulic oil flowing back and forth between the extension chamber and the compression chamber.

[0006] In a damping valve configured in this way, when the expansion and contraction speed of the shock absorber is in the very low speed range, the leaf valve does not flex much, limiting the flow area between it and the opposing seat to an extremely small size. As a result, a damping force characteristic that rises sharply in accordance with the expansion and contraction speed can be obtained, and a damping force characteristic suitable for a vehicle can be realized (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-183918 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Conventional damping valves, by incorporating a leaf valve and an opposing seat, can improve damping force characteristics when the shock absorber expands and contracts at very low speeds. However, because the leaf valve flexes and opens during both the expansion and contraction of the shock absorber, it was not possible to obtain different damping force characteristics during expansion and contraction.

[0009] In contrast, one could consider providing a valve seat that contacts the leaf valve and closes the port when the leaf valve bends toward the valve seat member, and configuring the damping valve to open only when the hydraulic fluid flows through the port in one direction, thereby also functioning as a check valve. However, in this case, when the leaf valve seats on the valve seat and closes the port, it receives back pressure and the part of the leaf valve between the fixed end and the valve seat bends significantly toward the port, raising concerns about fatigue of the leaf valve, and simply providing a valve seat makes it difficult to make the damping valve function as a check valve.

[0010] Therefore, the present invention aims to provide a damping valve that can function as a check valve while suppressing fatigue of the leaf valve, and a shock absorber that can improve the ride comfort of a vehicle by incorporating the damping valve. [Means for solving the problem]

[0011] To solve the above problems, the damping valve of the present invention comprises an annular valve body in which one of the inner or outer circumferences is a fixed end and the other of the inner or outer circumferences is a free end, allowing deflection of the free end relative to the fixed end; an annular valve seat member having an annular opposing seat portion facing at least a part of the circumferential surface on the free end side of the valve body, a port provided radially on the fixed end side of the valve body than the opposing seat portion, and an annular valve seat provided between the opposing seat portion and the port, facing the valve body in the axial direction, allowing the valve body to seat and dissipate; and the valve body comprises an annular leaf valve and an annular backup valve superimposed on the valve seat member side of the leaf valve to suppress deflection of the free end of the leaf valve toward the valve seat member side. A gap is provided between the valve body and the annular valve seat. .

[0012] With this damping valve configuration, when the valve body receives pressure from the port side, the valve body flexes, opening the port and resisting the flow of liquid passing through the port. When the valve body receives pressure pushing it toward the valve seat member, the valve body seats on the annular valve seat and closes the port. Thus, it functions as a damping valve for liquid flow attempting to pass through the port in one direction and as a check valve for liquid flow attempting to pass through the port in the other direction. Furthermore, with this damping valve, when the valve body receives pressure pushing it toward the valve seat member while seated on the annular valve seat, the backup valve contacts the valve seat member side of the leaf valve to support the leaf valve and suppress the deflection of the middle portion of the leaf valve. This reduces the stress acting on the leaf valve and suppresses leaf valve fatigue.

[0013] Furthermore, the valve seat member in the damping valve is provided radially on the fixed end side of the valve body than the annular valve seat, and faces the valve body axially. It has a regulating part that contacts the valve body and restricts the deflection of the valve body when the free end of the valve body deflects by more than a predetermined amount toward the valve seat member. With a damping valve configured in this way, in addition to support by the backup valve, when the intermediate portion of the valve body is pressed toward the valve seat member and deflects, and contacts the regulating part, the intermediate portion of the valve body is supported by the regulating part, preventing further deflection of the valve body. Therefore, even if excessive pressure is applied to the valve body, the stress on the leaf valve can be reduced, and the fatigue of the leaf valve can be further suppressed.

[0014] Furthermore, the backup valve in the damping valve may have a notch that penetrates the wall thickness axially. With a damping valve configured in this way, the valve body flexes smoothly at the beginning of its deflection, preventing situations where the damping force characteristics change abruptly.

[0015] Furthermore, the backup valve in the damping valve may have a notch that penetrates the wall thickness axially in the area that contacts the regulating portion. With a damping valve configured in this way, the valve body 27 bends smoothly when it begins to deflect, preventing abrupt changes in damping force characteristics. Also, when the valve body returns away from the valve seat member from the state in which the backup valve is in contact with the regulating portion, the valve body can return quickly, preventing a delay in port opening. Furthermore, the gap formed between the circumferential surface on the free end side of the valve body and the opposing seat portion in the damping valve may be narrower than the gap between the valve body and the annular valve seat.

[0016] Furthermore, the shock absorber of the present invention includes a shock absorber body having an outer tube, a rod that is axially movably inserted into the outer tube, and at least two working chambers through which liquid flows back and forth due to 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 way, since the damping valve can also function as a check valve, the damping force characteristics can be independently set according to the extension or contraction of the shock absorber. In the very low speed range of the expansion and contraction speed, the damping coefficient can be increased to quickly build up the damping force against the switching of the expansion and contraction stroke, and in the low speed range, the damping coefficient can be made smaller than that in the very low speed range. Therefore, it is possible to realize damping force characteristics suitable for suppressing the vibration of the vehicle body in a vehicle and improve the riding comfort in the vehicle.

Advantages of the Invention

[0017] According to the damping valve of the present invention, it can function as a check valve while suppressing the fatigue of the leaf valve. According to the shock absorber of the present invention, the riding comfort in a vehicle can be improved.

Brief Description of the Drawings

[0018] [Figure 1] It is a longitudinal sectional view of a shock absorber to which the damping valve according to an embodiment of the present invention is applied. [Figure 2] It is a partially enlarged sectional view of a shock absorber to which the damping valve according to an embodiment of the present invention is applied. [Figure 3] It is a diagram showing the damping force characteristics of a shock absorber to which the damping valve according to an embodiment of the present invention is applied. [Figure 4] It is a partially enlarged sectional view of the damping valve in the first modification according to an embodiment of the present invention. <了 [Figure 5] It is a partially enlarged sectional view of the damping valve in the second modification according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0019] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2, a shock absorber D in one embodiment has a telescopic shock absorber body A having a cylinder 1 as an outer tube and a rod 2 movably inserted into the cylinder 1, and is provided between an extension chamber R1 and a compression chamber R2, which are two working chambers provided in the shock absorber body A, with an extension sub-valve EV and a compression sub-valve CV as damping valves. And in the case of this shock absorber D, it is interposed and used between the vehicle body and the wheel in a vehicle not shown, and suppresses the vibrations of the vehicle body and the wheel.

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

[0021] And a bracket (not shown) is provided at the base end, which is the upper end of the rod 2 in FIG. 1, and the rod 2 is connected to one of the vehicle body and the wheel via the bracket outside the drawing. Also, a bracket (not shown) is 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 outside the drawing.

[0022] In this way, the shock absorber D is interposed between the vehicle body and the wheel. And when the vehicle travels on a bumpy road surface or the like and the wheel vibrates up and down with respect to the vehicle body, the rod 2 enters and exits the cylinder 1 and the shock absorber D expands and contracts, and at the same time, the piston 3 moves up and down (in the axial direction) inside the cylinder 1.

[0023] Further, the shock absorber body A includes an annular rod guide 10 that closes the upper end of the cylinder 1 and has the rod 2 slidably inserted through the inner circumference. Therefore, the inside of the cylinder 1 is a sealed space. And a free piston 11 is slidably inserted on the side opposite to the rod 2 as viewed from the piston 3 inside the cylinder 1.

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

[0025] When the shock absorber D extends, the rod 2 retracts from the cylinder 1, and as the volume of the cylinder increases by the volume of the retracted rod 2, the free piston 11 moves upward inside the cylinder 1, expanding the air chamber G. Conversely, when the shock absorber D retracts, the rod 2 moves into the cylinder 1, and as the volume of the cylinder decreases by the volume of the invading rod 2, the free piston 11 moves downward inside the cylinder 1, shrinking the air chamber G.

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

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

[0028] For example, if the free piston 11 and the air chamber G are eliminated and an outer tube is provided on the outer circumference of the cylinder 1, and a reservoir for storing liquid is formed between the cylinder 1 and the outer tube, thereby making the buffer a double-cylinder type buffer, the volume of the rod 2 moving in and out of the cylinder 1 may be compensated by the reservoir. The reservoir may be formed in a tank separate from the cylinder 1. Alternatively, the buffer D may be configured as a double-rod type buffer in which a piston 3 is mounted in 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, with its outer diameter reduced towards the tip. It has a small diameter section 2a at the tip, a large diameter section 2b with a larger outer diameter than the small diameter section 2a and located above the small diameter section 2a in Figure 2, and a stepped section 2c at the boundary between the small diameter section 2a and the large diameter section 2b. and The small diameter portion 2a is provided with a threaded portion 2d on the outer circumference of its tip, and four through holes 2e, 2f, 2g, and 2h located above the threaded portion 2d in Figure 2, and communicating the inside and outside of the small diameter portion 2a.

[0030] The small-diameter portion 2a of the rod 2 is assembled in order to the extension sub-valve EV, including the valve seat member 20, valve body 21, spacer 22 and valve stopper 23, spacer 24 and partition member 25, the compression sub-valve CV, including the valve seat member 26, valve body 27, spacer 28 and valve stopper 29, the main valve stopper 6, the compression main valve 5, the piston 3 and the extension main valve 4, and is fixed in place by a piston nut 33 that is screwed onto the threaded portion 2d at the tip of the small-diameter portion 2a.

[0031] As shown in Figures 1 and 2, the piston 3 is annular in shape and fixed to the outer circumference of the small-diameter portion 2a of the rod 2, sliding against the inner circumference of the cylinder 1, dividing the inside of the cylinder 1 into an extension chamber R1 on the upper side of Figure 1 and a compression chamber R2 on the lower side of Figure 1. The piston 3 is also provided with an extension passage 3a and a compression passage 3b that connect the extension chamber R1 and the compression chamber R2.

[0032] At the lower end of the piston 3 in Figure 2, an annular extension main valve 4 is stacked, fitted to the outer circumference of the small-diameter portion 2a of the rod 2 to open and close the extension passage 3a. The extension main valve 4 is a laminated leaf valve composed of multiple annular plates stacked together, with its inner circumference fixed to the small-diameter portion 2a of the rod 2 and its outer circumference allowed to flex. When the extension main valve 4 is seated on the lower end of the piston 3, it closes the outlet end of the lower end of the extension passage 3a. When its outer circumference flexes and it moves away from the piston 3, it opens the extension passage 3a and resists the flow of liquid from the extension chamber R1 to the compression chamber R2. The extension main valve 4 also seats on the piston 3 and closes the extension passage 3a for the flow of liquid from the compression chamber R2 to the extension chamber R1.

[0033] At the upper end of the piston 3 in Figure 2, a compression-side main valve 5 is stacked. This valve is an annular shape and is fitted onto the outer circumference of the small-diameter portion 2a of the rod 2 to open and close the compression-side passage 3b. The compression-side main valve 5 is a laminated leaf valve composed of multiple annular plates stacked together. Its inner circumference is fixed to the small-diameter portion 2a of the rod 2, while its outer circumference is allowed to flex. When the compression-side main valve 5 is seated on the upper end of the piston 3, it closes the outlet end of the upper compression-side passage 3b. When its outer circumference flexes and it separates from the piston 3, it opens the compression-side passage 3b and resists the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1. The compression-side main valve 5 also closes the compression-side passage 3b when the liquid flows from the extension-side chamber R1 to the compression-side chamber R2, by seating on the piston 3. A main valve stopper 6 is stacked above the compression-side main valve 5 in Figure 2. The main valve stopper 6 contacts the non-piston side of the compression main valve 5 when the compression main valve 5 is deflected significantly, supporting the compression main valve 5 and preventing excessive stress from acting on it, thereby protecting the compression main valve 5.

[0034] In this embodiment, the extension sub-valve EV, which functions as a damping valve, comprises a valve seat member 20, a valve body 21, a spacer 22, and a valve stopper 23, as shown in Figure 2. The valve seat member 20 is annular and comprises a perforated disc-shaped partition body 20a that fits onto the outer circumference of the small-diameter portion 2a, an annular opposing seat portion 20b that protrudes downward from the outer circumference of the lower end of the partition body 20a in Figure 2, a plurality of ports 20c that are located on the same circumference as the opposing seat portion 20b at the lower end of the partition body 20a in Figure 2, an annular recessed window 20d at the lower end of the partition body 20a in Figure 2 that communicates with the outlet ends of each port 20c, an annular valve seat 20e that is located at the lower end of the partition body 20a in Figure 2 and protrudes downward from between the opposing seat portion 20b and the ports 20c, and an annular inner seat portion 20f provided on the inner circumference of the window 20d.

[0035] The opposing seat portion 20b surrounds the outer circumference of the annular valve seat 20e with a gap from the partition wall 20a and protrudes downward from the lower end of the annular valve seat 20e. In other words, the height of the opposing seat portion 20b is higher than that of the annular valve seat 20e when viewed from the partition wall 20a, and the height difference between the opposing seat portion 20b and the annular valve seat 20e is at least greater than the axial thickness of the valve body 21, which will be described later. In this embodiment, the inner circumference of the valve body 21 is a fixed end and the outer circumference is a free end, so the annular valve seat 20e is provided on the inner circumference side of the valve body 21, which is the fixed end side in the radial direction, relative to the opposing seat portion 20b of the valve seat member 20. Furthermore, the height of the seat surface of the inner circumferential seat portion 20f, which is the lower end surface in Figure 2, is higher than the height of the seat surface of the annular valve seat 20e, which is the lower end surface in Figure 2, and lower than that of the opposing seat portion 20b.

[0036] In this embodiment, the opposing seat portion 20b and the annular valve seat 20e protrude axially from the partition wall 20a, and an annular recess is formed between the opposing seat portion 20b and the annular valve seat 20e. However, if 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 portion 20b, and if the height of the opposing seat portion 20b is higher than the annular valve seat 20e as described above, the opposing seat portion 20b and the annular valve seat 20e may be provided to protrude axially from the partition wall 20a as a single unit without an annular recess between them.

[0037] As shown in Figure 2, the valve body 21 is composed of a leaf valve 21a made up of multiple annular plates, the inner circumference of which is fixed to the small diameter portion 2a and serves as a fixed end, and the outer circumference of which is allowed to bend and serves as a free end, and a backup valve 21b which is stacked on the valve seat member side of the leaf valve 21a, and is superimposed on the lower end in Figure 2 of the partition wall 20a of the valve seat member 20 and fixed to the outer circumference of the small diameter portion 2a.

[0038] The leaf valve 21a is composed of three elastic annular plates 21a1, 21a2, and 21a3, all of which have inner diameters set to be able to fit around the outer circumference of the small-diameter portion 2a. Specifically, it comprises an elastic annular plate 21a1 located at the top in Figure 2 and having the largest outer diameter, an annular plate 21a2 having a smaller outer diameter than annular plate 21a1 and being laminated on the side opposite the valve seat member of annular plate 21a1, and an annular plate 21a3 having a smaller outer diameter than annular plate 21a2 and being laminated on the side opposite the valve seat member of annular plate 21a2. The number of annular plates constituting the leaf valve 21a can be appropriately changed according to the desired damping force characteristics, and may be as few as one.

[0039] Furthermore, the backup valve 21b is laminated on the valve seat member side of the annular plate 21a1, which has the largest outer diameter of the leaf valve 21a, in Figure 2, and is an annular plate whose outer diameter is smaller than that of the annular plate 21a1 and whose inner diameter is equal to that of the annular plate 21a1. In this case, the outer diameter of the backup valve 21b is larger than the inner diameter of the seating surface at the lower end of the annular valve seat 20e.

[0040] When the valve body 21 configured in this way is placed on the inner circumferential seat portion 20f of the partition wall 20a of the valve seat member 20, the inner circumferential seat portion 20f is higher than the annular valve seat 20e, so the valve body 21 faces the annular valve seat 20e in the axial direction, forming an axial gap between the backup valve 21b and the annular valve seat 20e, and the outer circumferential surface of the free end of the annular plate 21a1, which has the largest outer diameter in the leaf valve 21a, faces the inner circumferential surface of the opposing seat portion 20b of the valve seat member 20 in the radial direction with a small gap between them. When the leaf valve 21a is directly facing the opposing seat portion 20b, the gap between the leaf valve 21a and the opposing seat portion 20b is extremely small, making it difficult for liquid to pass through the gap, and this state is considered the state in which the extension sub-valve EV closes. Furthermore, as long as at least a portion of the outer circumferential surface on the free end side of the valve body 21 faces the opposing seat portion 20b in the radial direction, the extension sub-valve EV can open and close the port 20c, so it is not necessary for the entire outer circumferential surface of the annular plate 21a1 to face the entire inner circumferential surface of the opposing seat portion 20b in the radial direction.

[0041] The spacer 22, which is stacked on the side of the valve body 21 opposite the valve seat member, has an outer diameter smaller than the outer diameter of the annular plate 21a3 located on the side of the leaf valve 21a that is furthest away from the valve seat member, and is fixed immovably to the small diameter portion 2a. The spacer 22 is composed of a single annular plate, but it may be composed of multiple annular plates. Therefore, when the leaf valve 21a and backup valve 21b of the valve body 21 receive pressure from the liquid attempting to pass downward from the top of the valve seat member 20 in Figure 2 towards the port 20c, the outer circumference of the spacer 22 flexes downward in Figure 2, using its outer edge as a fulcrum. As a result, the outer surface of the leaf valve 21a no longer faces the inner surface of the opposing seat portion 20b radially and shifts downward relative to the opposing seat portion 20b, increasing the area of ​​the flow path formed by the gap between the leaf valve 21a and the opposing seat portion 20b in proportion to the amount of flexure of the leaf valve 21a. When the leaf valve 21a and the opposing seat portion 20b become misaligned and no longer face each other directly, the extension sub-valve EV opens, and the extension sub-valve EV provides resistance to the flow of liquid while allowing the liquid to flow through the gap with the valve body 21.

[0042] Furthermore, when the valve body 21 receives pressure from liquid attempting to pass upward through port 20c from below in Figure 2, the leaf valve 21a and backup valve 21b of the valve body 21 flex upward on their outer circumference in Figure 2, using the inner edge of the inner circumferential seat portion 20f of the valve seat member 20 as a fulcrum. When the valve body 21 flexes beyond a preset amount, the backup valve 21b seats on the annular valve seat 20e, closing port 20c. In this way, the extension sub-valve EV, acting as a damping valve, allows liquid flow when the liquid flows from above to below in port 20c, by bending the free end of the valve body 21 toward the opposite side of the valve seat member and opening the valve. Conversely, when the liquid flows from below to above in port 20c, the free end of the valve body 21 flexes toward the valve seat member and seats on the annular valve seat 20e, blocking the liquid flow. Thus, the extension sub-valve EV functions as a damping valve that opens to allow and resist the flow of liquid through port 20c to one side, and conversely, can also function as a check valve that closes to block the flow of liquid through port 20c to the other side. The backup valve 21b overlaps the valve seat member side of the leaf valve 21a and supports the leaf valve 21a by contacting the valve seat side of the leaf valve 21a when the valve body 21 seats on the annular valve seat 20e, and restricts the portion of the leaf valve 21a between the annular valve seat 20e and the inner circumferential seat portion 20f from bending upward toward the valve seat member side due to pressure from below. In this way, the backup valve 21b supports the leaf valve 21a, suppressing excessive bending toward the valve seat member side when the valve body 21 seats on the annular valve seat 20e, and protects the leaf valve 21a by preventing excessive stress from acting on it.

[0043] Furthermore, the extension sub-valve EV allows liquid to flow from the bottom to the top of the port 20c until the valve body 21 bends toward the valve seat member and seats on the annular valve seat 20e. The amount of deflection before the valve body 21 contacts the annular valve seat 20e when it functions as a check valve can be adjusted by setting the height of the seating surfaces of the inner circumferential seat portion 20f and the annular valve seat 20e, but the amount of deflection may also be adjusted by interposing a spacer between the inner circumferential seat portion 20f and the valve body 21. When using a spacer, the height of the seating surface of the inner circumferential seat portion 20f may be set 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 spacers stacked.

[0044] The valve stopper 23 is laminated on the side of the spacer 22 opposite the valve seat member, and when the valve body 21 is deflected significantly, it contacts at least one or more of the annular plates 21a1, 21a2, 21a3 of 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.

[0045] A spacer 24 is stacked below the valve stopper 23 in Figure 2. The spacer 24 is formed in a bottomed cylindrical shape, with a hole 24a at the bottom that allows the small diameter portion 2a of the rod 2 to pass through, and a notch 24c that connects the inside and outside of the cylindrical portion 24b, with the opening facing downwards in Figure 2, and is fixed to the outer circumference of the small diameter portion 2a of the rod 2. The cylindrical portion 24b is radially opposite to the through holes 2e and 2f provided in the small diameter portion 2a, and the inside of the cylindrical portion 24b is in communication with the inside of the rod 2. Since the spacer 24 is positioned 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.

[0046] The partition member 25 is a bottomed cylindrical shape, with a hole 25a at its bottom that allows the small-diameter portion 2a of the rod 2 to pass through. The opening side faces upward and is superimposed on the lower end of the spacer 24 in Figure 2, and the cylindrical portion is fitted onto the outer circumference of the valve seat member 20, thereby fixing it to the outer circumference of the small-diameter portion 2a of the rod 2. The outer diameter of the partition member 25 is smaller than the inner diameter of the cylinder 1, forming an annular gap between it and the cylinder 1, and together with the valve seat member 20 Extension ventricular R1A space R3 is partitioned inside. Space R3 communicates with the extension chamber R1 via a port 20c provided in the valve seat member 20, and also communicates with the compression 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, space R3, the through holes 2e and 2f, and the inside of the rod 2 form an extension sub-passage EP, which acts as a damping passage connecting the extension chamber R1 and the compression chamber R2. The extension sub-passage EP configured in this way connects the extension chamber R1 and the compression chamber R2 in parallel with the extension passage 3a provided in the piston 3. Therefore, the extension sub-valve EV is provided in the extension sub-passage EP that bypasses the extension passage 3a and connects the extension chamber R1 and the compression chamber R2.

[0047] In this embodiment, the compression-side sub-valve CV, which acts as a damping valve, is positioned between the partition member 25 and the compression-side main valve 5 and mounted on the outer circumference of the small-diameter portion 2a, as shown in Figure 2. More specifically, the compression-side sub-valve CV comprises a valve seat member 26, a valve body 27, a spacer 28, and a valve stopper 29.

[0048] The valve seat member 26 is annular and includes a perforated disc-shaped partition body 26a that fits onto the outer circumference of the small diameter portion 2a, an annular opposing seat portion 26b that protrudes downward from the outer circumference of the lower end of the partition body 26a in Figure 2, an annular groove 26c provided on the inner circumference of the partition body 26a, and a plurality of ports 26d that open from the inner circumference side of the opposing seat portion 26b at the lower end of the partition body 26a in Figure 2 and communicate with the annular groove 26c, and the part of the partition body 26a The partition wall 26a comprises a window 26e which is an annular recess at the lower end of the partition wall 26a and communicates with the outlet end of each port 26d, an annular valve seat 26f which is provided at the lower end of the partition wall 26a and protrudes downward from between the opposing seat portion 26b and the port 26d, an annular inner circumferential seat portion 26g provided on the inner circumference of the window 26e, and a plurality of restricting portions 26h which protrude axially from inside the window 26e of the partition wall 26a.

[0049] The opposing seat portion 26b surrounds the outer circumference of the annular valve seat 26f and protrudes downward from the lower end of the annular valve seat 26f. In other words, the height of the opposing seat portion 26b is higher than that of the annular valve seat 26f when viewed from the partition body 26a, and the height difference between the opposing seat portion 26b and the annular valve seat 26f is at least greater than the axial thickness of the valve body 27, which will be described later. In this embodiment, the inner circumference of the valve body 27 is a fixed end and the outer circumference is a free end, so the annular valve seat 26f is provided on the inner circumference side of the valve body 27, which is the fixed end side in the radial direction, relative to the opposing seat portion 26b of the valve seat member 26. Furthermore, the height of the seat surface of the inner circumferential seat portion 26g, which is the lower end surface in Figure 2, is higher than the height of the seat surface of the annular valve seat 26f, which is the lower end surface in Figure 2, and lower than that of the opposing seat portion 26b.

[0050] In this embodiment, the opposing seat portion 26b and the annular valve seat 26f protrude axially from the partition wall 26a as a single unit, and the annular valve seat 26f is provided in a continuous manner inside the opposing seat portion 26b. However, if the inner circumference side of the valve body 27 is a fixed end, the annular valve seat 26f may protrude from the partition wall 26a on the inner circumference side of the opposing seat portion 26b, spaced apart from the opposing seat portion 26b.

[0051] Furthermore, in the compression-side sub-valve CV, the valve seat member 26 is located at the lower end of the partition wall 26a and has a plurality of restricting portions 26h that protrude axially from the inner circumference side, which is radially closer to the fixed end of the valve body 27 than the annular valve seat 26f. In this embodiment, the restricting portions 26h are provided between the annular valve seat 26f and the inner circumference seat portion 26g, and between the ports 26d, 26d in the window 26e in the circumferential direction of the partition wall 26a. However, the installation position of the restricting portions 26h can be arbitrarily changed in the design as long as they are between the annular valve seat 26f and the inner circumference seat portion 26g and do not interfere with the ports 26d. Also, the shape of the restricting portion 26h when viewed from the axial direction of the valve seat member 26 can be arc-shaped or circular, and can be arbitrarily changed in the design. The restricting portion 26h is positioned to avoid the port 26d, and is therefore located between ports 26d, 26d. It is preferable that the restricting portion 26h be provided at equal intervals on the same circumference to uniformly support the valve body 27 in the circumferential direction when the valve body 27 bends toward the valve seat member, but it is not necessary that it be provided at equal intervals on the same circumference as long as it can support the valve body 27. Furthermore, the height of the seating surface of the restricting portion 26h is the same as the height of the seating surface of the annular valve seat 26f, but it may be lower than the annular valve seat 26f as long as the valve body 27 can contact the backup valve 27b and support the valve body 27 when seated on the annular valve seat 26f.

[0052] As shown in Figure 2, the valve body 27 is composed of a leaf valve 27a made up of multiple annular plates, the inner circumference of which is fixed to the small diameter portion 2a and serves as a fixed end, and the outer circumference of which is allowed to bend and serves as a free end, and a backup valve 27b which is stacked on the valve seat member side of the leaf valve 27a, and is superimposed on the lower end in Figure 2 of the partition wall body 26a of the valve seat member 26 and fixed to the outer circumference of the small diameter portion 2a.

[0053] The leaf valve 27a is composed of three elastic annular plates 27a1, 27a2, and 27a3, all of which have inner diameters set to be able to fit around the outer circumference of the small-diameter portion 2a. Specifically, it comprises an elastic annular plate 27a1 located at the top in Figure 2 and having the largest outer diameter, an annular plate 27a2 having a smaller outer diameter than annular plate 27a1 and being laminated on the side opposite the valve seat member of annular plate 27a1, and an annular plate 27a3 having a smaller outer diameter than annular plate 27a2 and being laminated on the side opposite the valve seat member of annular plate 27a2.

[0054] Furthermore, the backup valve 27b is laminated on the valve seat member side of the annular plate 27a1, which has the largest outer diameter of the leaf valve 27a, in Figure 2. The backup valve 27b is an annular plate whose outer diameter is smaller than that of the annular plate 27a1 and the annular valve seat 26f, and whose inner diameter is equal to that of the annular plate 27a1. In this case, the outer diameter of the backup valve 27b is smaller than the inner diameter of the seating surface at the lower end of the annular valve seat 26f. Therefore, even if the valve body 27 bends toward the valve seat member, it is the annular plate 27a1 of the leaf valve 27a that will seat on the annular valve seat 26f.

[0055] When the valve body 27 configured in this way is placed on the inner circumferential seat portion 26g of the partition wall 26a of the valve seat member 26, the inner circumferential seat portion 26g is higher than the annular valve seat 26f. As a result, the valve body 27 faces the annular valve seat 26f in the axial direction, creating an axial gap between the backup valve 27b and the annular valve seat 26f. At the same time, the outer circumferential surface of the free end of the annular plate 27a1, which has the largest outer diameter in the leaf valve 27a, faces the inner circumferential surface of the opposing seat portion 26b of the valve seat member 26 with a small gap between them in the radial direction. When the leaf valve 27a faces the opposing seat portion 26b, the gap between the leaf valve 27a and the opposing seat portion 26b is extremely small, making it difficult for liquid to pass through the gap. This state is considered the state in which the pressure-side sub-valve CV closes. Furthermore, as long as at least a portion of the outer circumferential surface on the free end side of the valve body 27 faces the opposing seat portion 26b in the radial direction, the compression-side sub-valve CV can open and close the port 26d. Therefore, it is not necessary for the entire outer circumferential surface of the annular plate 27a1 to face the entire inner circumferential surface of the opposing seat portion 26b in the radial direction.

[0056] The spacer 28, which is stacked on the side of the valve body 27 opposite the valve seat member, has an outer diameter smaller than the outer diameter of the annular plate 27a3 located on the side of the leaf valve 27a that is furthest away from the valve seat member, and is fixed immovably to the small diameter portion 2a. The spacer 28 is composed of a single annular plate, but it may be composed of multiple annular plates. Therefore, when the leaf valve 27a and backup valve 27b of the valve body 27 receive pressure from the liquid attempting to pass downward from the top of the valve seat member 26 in Figure 2 towards the port 26d, the outer circumference of the spacer 28 flexes downward in Figure 2, using its outer edge as a fulcrum. As a result, the outer surface of the leaf valve 27a no longer faces the inner surface of the opposing seat portion 26b radially and shifts downward relative to the opposing seat portion 26b, increasing the area of ​​the flow path formed by the gap between the leaf valve 27a and the opposing seat portion 26b in proportion to the amount of deflection of the leaf valve 27a. When the leaf valve 27a and the opposing seat portion 26b become misaligned and no longer face each other directly, the pressure-side sub-valve CV opens, and the pressure-side sub-valve CV provides resistance to the flow of liquid while allowing the liquid to flow through the gap with the valve body 27.

[0057] Furthermore, when the valve body 27 receives pressure from liquid attempting to pass upward through port 26d from below in Figure 2, the leaf valve 27a and backup valve 27b of the valve body 27 flex upward on their outer side in Figure 2, using the inner edge of the inner circumferential seat portion 26g of the valve seat member 26 as a fulcrum. When the valve body 27 flexes beyond a preset amount, the annular plate 27a1 of the leaf valve 27a seats on the annular valve seat 26f, closing port 26d. In this way, the pressure-side sub-valve CV, acting as a damping valve, allows liquid flow when the liquid flows from above to below in port 26d, by bending the free end of the valve body 27 toward the opposite side of the valve seat member and opening the valve. Conversely, when the liquid flows from below to above in Figure 2, the free end of the valve body 27 flexes toward the valve seat member and seats on the annular valve seat 26f, blocking the liquid flow. Thus, the pressure-side sub-valve CV functions as a damping valve that allows and resists the flow of liquid through port 26d to one side by opening it, and conversely, it can also function as a check valve that closes and blocks the flow of liquid through port 26d to the other side. The backup valve 27b overlaps the valve seat member side of the leaf valve 27a and supports the leaf valve 27a by abutting against the valve seat side of the leaf valve 27a when the leaf valve 27a seats on the annular valve seat 26f, and restricts the portion of the leaf valve 27a between the annular valve seat 26f and the inner circumferential seat portion 26g from bending upward toward the valve seat member side due to pressure from below. In this way, the backup valve 27b supports the leaf valve 27a and suppresses the large bending of the leaf valve 27a toward the valve seat member side when the valve body 27 seats on the annular valve seat 26f, thereby preventing excessive stress from acting on the leaf valve 27a and protecting the leaf valve 27a. Furthermore, in addition to the configuration of the extension sub-valve EV, the valve seat member 26 in the compression sub-valve CV is equipped with a restricting portion 26h on the inner circumference side of the annular valve seat 26f. When the intermediate portion between the part of the valve body 27 that abuts the annular valve seat 26f and the part that abuts the inner circumferential seat portion 26g, which faces the valve body 27 in the axial direction, deflects by more than a predetermined amount, it abuts against the backup valve 27b and supports it from the valve seat member side, thereby restricting the deflection of the valve body 27 between the annular valve seat 26f and the fixed end.Therefore, in the compression-side sub-valve CV, the deflection of the intermediate part of the leaf valve 27a can be suppressed not only by the backup valve 27b but also by the regulating section 26h, thus further reducing fatigue of the leaf valve 27a. The height between the regulating section 26h and the annular valve seat 26f should be set so that the regulating section 26h does not interfere with the seating of the valve body 27 on and off the annular valve seat 26f. To that extent, a predetermined amount that becomes the amount of deflection when the valve body 27 contacts the regulating section 26h can be arbitrarily set, but the predetermined amount should be set so that the valve body 27 is supported by the regulating section 26h before the stress on the valve body 27 becomes excessive.

[0058] The compression-side sub-valve CV allows liquid to flow from the bottom to the top of the port 26d until the valve body 27 bends toward the valve seat member and seats onto the annular valve seat 26f. The amount of deflection, which is the amount of deflection until the valve body 27 contacts the annular valve seat 26f when it functions as a check valve, 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 deflection may also be adjusted by interposing a spacer between the inner circumferential seat portion 26g and the valve body 27. When using a spacer, the height of the seating surface of the inner circumferential seat portion 26g may be set lower than the height of the seating surface of the annular valve seat 26f, and the amount of deflection may be adjusted by the number of spacers stacked.

[0059] The valve stopper 29 is stacked on the side of the spacer 28 opposite the valve seat member, and when the valve body 27 is deflected significantly, it contacts at least one or more of the annular plates 27a1, 27a2, 27a3 of the valve body 27 to support the valve body 27 and prevent excessive stress from acting on the valve body 27, thereby protecting the valve body 27.

[0060] When the compression sub-valve CV configured in this way is stacked on the outer circumference of the small-diameter portion 2a below the spacer 24, the annular groove 26c formed on the inner circumference of the valve seat member 26 faces radially the through holes 2g and 2h provided in the small-diameter portion 2a, so that the port 26d communicates with the inside of the rod 2. Therefore, the extension chamber R1 communicates with the compression 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 sub-passage CP, which is a damping passage that connects the extension chamber R1 and the compression chamber R2. The compression sub-passage CP configured in this way connects the extension chamber R1 and the compression chamber R2 in parallel with the compression passage 3b provided in the piston 3. Therefore, the compression sub-valve CV is provided in the compression sub-passage CP that connects the extension chamber R1 and the compression chamber R2 by bypassing the compression passage 3b.

[0061] Next, a cylindrical rotary valve 12 is housed inside the rod 2, with its outer surface sliding against the inner surface of the rod 2, allowing it to rotate circumferentially within the rod 2. The rotary valve 12 has holes 12a, 12b, 12c, and 12d that communicate inside and outside, positioned to face the through holes 2e, 2f, 2g, and 2h, respectively. When rotated by a control rod 13 inserted inside the rod 2, the degree of communication between through hole 2e and hole 12a, through hole 2f and hole 12b, through hole 2g and hole 12c, and through hole 2h and hole 12d can be changed, and through holes 2e, 2f, 2g, and 2h can be blocked without facing holes 12a, 12b, 12c, and 12d. In other words, the rotary valve 12 can adjust the area of ​​the four flow paths, which consist of through-hole 2e and hole 12a, through-hole 2f and hole 12b, through-hole 2g and hole 12c, and through-hole 2h and hole 12d, by adjusting the rotational position of the rotary valve 12 in the circumferential direction relative to the rod 2, thereby adjusting the resistance applied to the flow of hydraulic fluid passing through these flow paths. In this embodiment, the control rod 13 is driven by a rotary actuator, such as a stepping motor (not shown), attached to the tip of the rod 2, but the rotary actuator may be housed inside the rod 2.

[0062] When the rotary valve 12 connects holes 12a and 12b to the through holes 2e and 2f, respectively, the extension chamber R1 and the pressure chamber R2 are connected through the extension sub-passage EP. When the rotary valve 12 connects holes 12c and 12d to the through holes 2g and 2h, respectively, the extension chamber R1 and the pressure chamber R2 are connected through the pressure sub-passage CP. Thus, the rotary valve 12 is installed in the middle of the extension sub-passage EP and the pressure sub-passage CP, and when rotated by the control rod 13, it can change the degree of connection (flow path area) between holes 12a, 12b, 12c, and 12d and the corresponding through holes 2e, 2f, 2g, and 2h, thereby changing the resistance to the liquid flow passing through the extension sub-passage EP and the pressure sub-passage CP. The rotary valve 12 is equipped with two holes 12a and 12b for adjusting the flow area of ​​the extension sub-passage EP and two holes 12c and 12d for adjusting the flow area of ​​the compression sub-passage CP, but the number of holes can be arbitrarily changed according to the setting of the maximum flow area. and others The number of through-holes provided in the rod 2 should be set to correspond to the number of holes provided. Furthermore, the holes 12a, 12b, 12c, and 12d provided in the rotary valve 12 may be offset in the circumferential direction, and the installation positions of the through-holes 2e, 2f, 2g, and 2h provided in the rod 2 should also be set to appropriate positions corresponding to 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 through-hole 2f may communicate when the hole 12a and 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 through-hole 2f may be set to face each other at a different timing than when the hole 12a and through-hole 2e face each other, and the same applies to the relationship between the holes 12c and 12d provided in the middle of the compression-side sub-passage CP and the through-holes 2g and 2h.

[0063] As described above, the extension sub-valve EV and compression sub-valve CV, which function as damping valves, and the shock absorber D are configured as such. The operation of the extension sub-valve EV and compression sub-valve CV, which function as damping valves, and the shock absorber D will be explained below.

[0064] First, when the shock absorber D extends, the piston 3 moves upward in Figure 1 within the cylinder 1, compressing the extension chamber R1. When the extension sub-passage EP and the compression sub-passage CP are in communication by the rotary valve 12, the liquid in the extension chamber R1, which is compressed by the upward movement of the piston 3, attempts to move to the expanding compression chamber R2 through the extension sub-passage EP together with the extension passage 3a provided in the piston 3. Here, when the extension speed of the shock absorber D is in the very low speed range and close to 0, although the pressure in the extension chamber R1 rises, the pressure difference between the pressure in the extension chamber R1 and the pressure in the compression chamber R2 does not reach the opening pressure of the extension main valve 4, so the extension main valve 4 does not open and maintains the extension passage 3a closed. The compression main valve 5 receives the pressure of the extension chamber R1 from the rear side and closes the compression passage 3b.

[0065] When the piston speed of the shock absorber D is close to 0 during extension operation, the pressure in the extension chamber R1 rises, but the pressure difference with the pressure in the compression chamber R2 does not reach the opening pressure of the valve body 21 in the extension sub-valve EV. Therefore, even if the valve body 21 bends, the outer surface of the annular plate 21a1 in the leaf valve 21a faces the range of the axial width of the inner circumference of the opposing seat portion 20b, resulting in a closed valve state and maintaining an extremely small flow area in the annular gap between the valve body 21 and the opposing seat portion 20b.

[0066] On the other hand, in the compression-side sub-valve CV, when the extension speed of the buffer D is in the very low speed range and is close to 0, the pressure in the extension-side chamber R1 increases, but the pressure difference between the pressure in the extension-side chamber R1 and the pressure in the compression-side chamber R2 is small, and the valve body 27 does not deflect until it seats on the annular valve seat 26f toward the valve seat member. In this way, when the extension speed of the buffer D is in the very low speed range and is close to 0, the valve body 27 remains closed with the outer circumferential surface of the annular plate 27a1 in the leaf valve 27a facing the inner axial width of the opposing seat portion 26b, and the flow area in the annular gap between the valve body 27 and the opposing seat portion 26b is kept extremely small.

[0067] Therefore, when the extension speed of the buffer D is in the very low speed range and close to zero, the liquid in the extension chamber R1 has difficulty passing through the extension sub-passage EP and the compression sub-passage CP because the extension sub-valve EV and the compression sub-valve CV remain closed. Also, the extension main valve 4 remains closed through the extension passage 3a. Therefore, when the extension speed of the buffer D is in the very low speed range and close to zero, the damping force characteristics (damping force characteristics) generated with respect to the piston speed of the buffer D become a characteristic that rises sharply, as shown in Figure 3.

[0068] Furthermore, when the piston speed of the buffer D increases during extension operation and changes from the very low speed range to the low speed range, the pressure difference between the pressure in the extension chamber R1 and the pressure in the compression chamber R2 exceeds the opening pressure of the valve body 21. As a result, the valve body 21 bends so that its outer circumference shifts downward in Figure 2 from the axial width range of the inner circumference of the opposing seat portion 20b, opening the valve and increasing the flow area of ​​the annular gap between the valve body 21 and the opposing seat portion 20b. Consequently, the liquid passes through the extension sub-valve EV, and then through the extension sub-passage EP to move from the extension chamber R1 to the compression chamber R2. On the other hand, when the piston speed of the buffer D increases during extension operation and changes from the very low speed range to the low speed range, the valve body 27 in the compression sub-valve CV bends under the pressure in the extension chamber R1 and seats on the annular valve seat 26f in the valve seat member 26, blocking the port 26d and preventing the liquid from passing through the compression sub-passage CP.

[0069] Therefore, when the piston speed of the shock absorber D increases during extension operation and changes from the very low speed range to the low speed range, the flow area in the extension sub-valve EV increases in proportion to the increase in piston speed. As a result, the damping force characteristics of the shock absorber D become less sloped than the damping force characteristic curve in the very low speed range, as shown in Figure 3.

[0070] Furthermore, when the piston speed increases during the extension operation of the buffer D and exceeds the low-speed range, the valve body 21 deflects significantly and contacts the valve stopper 23, maximizing the flow area in the annular gap between it and the opposing seat portion 20b, while the extension-side main valve 4 deflects and separates from the piston 3, opening the extension-side passage 3a. As a result, 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. With increasing piston speed, the amount of deflection of the extension-side main valve 4 increases, and the flow area in the gap between the extension-side main valve 4 and the piston 3 becomes larger than the flow area in the annular gap between the valve body 21 and the opposing seat portion 20b in the extension-side sub-valve EV. Therefore, the buffer D generates a damping force mainly due to the resistance that the extension-side main valve 4 exerts on the liquid flow. Thus, when the piston speed increases during the extension operation of the buffer D and exceeds the low-speed range, the damping force characteristics of the buffer D change as the piston speed increases, as shown in Figure 3, to generate a damping force with a nearly constant slope with respect to the increase in piston speed. Furthermore, by rotating the rotary valve 12, the resistance applied to the flow of liquid passing through the extension sub-passage EP can be adjusted, so 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 extends, the rod 2 retracts from inside the cylinder 1, but the free piston 11 moves upward in Figure 2 inside the cylinder 1 to enlarge the air chamber G, compensating for the volume of the rod 2 that has retracted from inside the cylinder 1.

[0071] As the piston speed increases during the extension operation of the buffer D and exceeds the low-speed range, the pressure in the extension chamber R1 significantly exceeds the pressure in the compression chamber R2. This increases the difference between the pressure in the extension chamber R1 acting on the valve body 27 from below in Figure 2 and the pressure in the compression chamber R2 acting on it from above in Figure 2 via the port 26d. Consequently, the leaf valve 27a in the valve body 27 of the compression sub-valve CV is pressed upward by the pressure in the extension chamber R1. However, since its outer circumference is supported by the annular valve seat 26f and its inner circumference is supported by the inner seat portion 26g, the intermediate portion of the leaf valve 27a between the part that contacts the annular valve seat 26f and the part that contacts the inner seat portion 26g flexes so that it becomes convex upward in Figure 2. The backup valve 27b abuts against the valve seat member side of the leaf valve 27a and supports the leaf valve 27a. This suppresses the deflection of the intermediate portion of the leaf valve 27a, thereby suppressing upward convex deflection deformation of the intermediate portion of the leaf valve 27a, reducing the stress acting on the leaf valve 27a, and suppressing fatigue of the leaf valve 27a. Furthermore, when the valve body 27 is pressed by the pressure in the extension chamber R1 and the backup valve 27b abuts against the regulating portion 26h of the valve seat member 26, the regulating portion 26h supports the leaf valve 27a, preventing further deflection of the intermediate portion of the leaf valve 27a. This prevents the stress on the leaf valve 27a from increasing further, further suppressing fatigue of the leaf valve 27a.

[0072] Next, when the shock absorber D contracts, the piston 3 moves downward in Figure 1 within the cylinder 1, compressing the compression chamber R2. When the extension sub-passage EP and the compression sub-passage CP are in communication by the rotary valve 12, the liquid in the compression chamber R2, which is compressed by the downward movement of the piston 3, attempts to move to the expanding extension chamber R1 through the compression sub-passage CP along with the compression passage 3b provided in the piston 3. Here, when the contraction speed of the shock absorber D is in the very low speed range and close to 0, the pressure in the compression chamber R2 rises, but the pressure difference between the pressure in the compression chamber R2 and the pressure in the extension chamber R1 does not reach the opening pressure of the compression main valve 5, so the compression main valve 5 does not open and maintains the compression passage 3b closed. The extension main valve 4 receives the pressure of the compression chamber R2 from the rear side and closes the extension passage 3a.

[0073] When the piston speed of the shock absorber D is close to 0 during contraction, the pressure in the compression chamber R2 rises, but the pressure difference with the pressure in the extension chamber R1 does not reach the opening pressure of the valve body 27 in the compression sub-valve CV. Therefore, even if the valve body 27 bends, the outer surface of the annular plate 27a1 in the leaf valve 27a faces the range of the axial width of the inner circumference of the opposing seat portion 26b, resulting in a closed valve state and maintaining an extremely small flow area in the annular gap between the valve body 27 and the opposing seat portion 26b.

[0074] On the other hand, in the extension sub-valve EV, when the contraction speed of the buffer D is in the very low speed range and close to 0, the pressure in the compression chamber R2 increases, but the pressure difference between the pressure in the compression chamber R2 and the pressure in the extension chamber R1 is small, and the valve body 21 does not deflect until it seats on the annular valve seat 20e toward the valve seat member. Thus, when the contraction speed of the buffer D is in the very low speed range and close to 0, the valve body 21 remains closed with the outer circumferential surface of the annular plate 21a1 in the leaf valve 21a facing the inner circumference of the opposing seat portion 20b within the range of the axial width, and the flow area in the annular gap between the valve body 21 and the opposing seat portion 20b is kept extremely small.

[0075] Therefore, when the contraction speed of the buffer D is in the very low speed range and close to zero, the liquid in the compression chamber R2 has difficulty passing through the extension sub-passage EP and the compression sub-passage CP because the extension sub-valve EV and the compression sub-valve CV remain closed. Also, the compression main valve 5 remains closed through the compression passage 3b. Therefore, when the contraction speed of the buffer D is in the very low speed range and close to zero, the damping force characteristics (damping force characteristics) generated with respect to the piston speed of the buffer D become a characteristic that rises sharply, as shown in Figure 3.

[0076] Furthermore, when the piston speed of the shock absorber D increases during its contraction operation and changes from a very low speed range to a low speed range, the pressure difference between the pressure in the compression chamber R2 and the pressure in the extension chamber R1 exceeds the opening pressure of the valve body 27. As a result, the valve body 27 bends so that its outer circumference shifts downward in Figure 2 from the axial width range of the inner circumference of the opposing seat portion 26b, opening the valve and increasing the flow area of ​​the annular gap between the valve body 27 and the opposing seat portion 26b. Consequently, the liquid passes through the compression sub-valve CV, and then through the compression sub-passage CP to move from the compression chamber R2 to the extension chamber R1. On the other hand, when the piston speed of the shock absorber D increases during its contraction operation and changes from a very low speed range to a low speed range, the valve body 21 in the extension sub-valve EV bends under the pressure in the compression chamber R2 and seats on the annular valve seat 20e in the valve seat member 20, blocking the port 20c and preventing the liquid from passing through the extension sub-passage EP.

[0077] Therefore, when the piston speed of the shock absorber D increases during its contraction operation and changes from the very low speed range to the low speed range, the flow path area in the compression-side sub-valve CV increases in proportion to the increase in piston speed. As a result, the damping force characteristics of the shock absorber D become less sloped than the damping force characteristic curve in the very low speed range, as shown in Figure 3.

[0078] Furthermore, when the piston speed increases during the contraction operation of the shock absorber D and exceeds the low-speed range, the valve body 27 deflects significantly and contacts the valve stopper 29, maximizing the flow area in the annular gap between it and the opposing seat portion 26b, while the compression-side main valve 5 deflects and separates from the piston 3, opening the compression-side passage 3b. As a result, the liquid moves from the compression-side chamber R2 to the extension-side chamber R1 through the gap between the compression-side main valve 5 and the piston 3. With increasing piston speed, the amount of deflection of the compression-side main valve 5 increases, and the flow area in the gap between the compression-side main valve 5 and the piston 3 becomes larger than the flow area in the annular gap between the valve body 27 and the opposing seat portion 26b of the compression-side sub-valve CV. Therefore, the shock absorber D generates damping force mainly due to the resistance that the compression-side main valve 5 exerts on the liquid flow. Thus, when the piston speed increases during the contraction operation of the shock absorber D and exceeds the low-speed range, the damping force characteristics of the shock absorber D change as the piston speed increases, as shown in Figure 3, to generate a damping force with a nearly constant slope with respect to the increase in piston speed. Furthermore, by rotating the rotary valve 12, the resistance applied to the liquid flow through the pressure-side sub-passage CP can be adjusted, so 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 contracted, the rod 2 enters the cylinder 1, but the free piston 11 moves downward in Figure 2 within the cylinder 1, reducing the size of the air chamber G and compensating for the volume of the rod 2 that has entered the cylinder 1.

[0079] As the piston speed of the shock absorber D increases during its contraction operation and exceeds the low-speed range, the pressure in the compression chamber R2 significantly exceeds the pressure in the extension chamber R1. This increases the difference between the pressure in the compression chamber R2 acting on the valve body 21 from below in Figure 2 and the pressure in the extension chamber R1 acting on it from above in Figure 2 via the port 20c. Consequently, the leaf valve 21a in the valve body 21 of the extension sub-valve EV is pressed upward by the pressure in the compression chamber R2. However, since its outer circumference is supported by the annular valve seat 20e and its inner circumference is supported by the inner circumferential seat portion 20f, the intermediate portion of the leaf valve 21a between the part that contacts the annular valve seat 20e and the part that contacts the inner circumferential seat portion 20f flexes so that it becomes convex upward in Figure 2. The backup valve 21b abuts against the valve seat member side of the leaf valve 21a and supports the leaf valve 21a. By suppressing the deflection of the intermediate portion of the leaf valve 21a, upward convex deflection deformation of the intermediate portion of the leaf valve 21a is suppressed, reducing the stress acting on the leaf valve 21a and suppressing fatigue of the leaf valve 21a.

[0080] As described above, the extension sub-valve EV and compression sub-valve CV as damping valves of this embodiment include annular valve bodies 21 and 27 whose inner circumference is a fixed end and whose outer circumference is a free end, allowing deflection of the free end relative to the fixed end; annular opposing seat portions 20b and 26b that are annular and face at least a part of the circumferential surface on the free end side of the valve bodies 21 and 27; ports 20c and 26d provided radially on the fixed end side of the valve bodies 21 and 27 than the opposing seat portions 20b and 26b; and opposing seat portions 20b, The valve seat members 20 and 26 are provided between ports 20c and 26d and have annular valve seats 20e and 26f that are axially opposed to the valve bodies 21 and 27 and can seat and dissipate from the valve bodies 21 and 27. The valve bodies 21 and 27 each include annular leaf valves 21a and 27a and annular backup valves 21b and 27b that are superimposed on the valve seat member side of the leaf valves 21a and 27a to suppress the deflection of the free ends of the leaf valves 21a and 27a toward the valve seat member side.

[0081] With the extension sub-valve EV and compression sub-valve CV configured as damping valves in this way, when the valve bodies 21 and 27 receive pressure from the port 20c and 26d side, the valve bodies 21 and 27 bend, opening the ports 20c and 26d and resisting the flow of liquid passing through the ports 20c and 26d. At the same time, when the valve bodies 21 and 27 receive pressure that pushes them toward the valve seat members 20 and 26, the valve bodies 21 and 27 seat on the annular valve seats 20e and 26f, blocking the ports 20c and 26d. Thus, they function as damping valves for liquid flow attempting to pass through ports 20c and 26d in one direction and as check valves for liquid flow attempting to pass through ports 20c and 26d in the other direction. Furthermore, with the extension sub-valve EV and compression sub-valve CV acting as damping valves, when the valve bodies 21 and 27 are seated on the annular valve seats 20e and 26f and subjected to pressure that pushes them toward the valve seat members 20 and 26, the backup valves 21b and 27b contact the valve seat member side of the leaf valves 21a and 27a, supporting the leaf valves 21a and 27a and suppressing the deflection of the intermediate portion of the leaf valves 21a and 27a. As a result, the stress acting on the leaf valves 21a and 27a is reduced, and fatigue of the leaf valves 21a and 27a can be suppressed. Therefore, with the extension sub-valve EV and compression sub-valve CV acting as damping valves in this embodiment, the leaf valves 21a and 27a can function as check valves while suppressing fatigue of the leaf valves 21a and 27a.

[0082] Furthermore, when the leaf valves 21a and 27a bend away from the valve seat members 20 and 26 to open the ports 20c and 26d, and then return to their original position with their outer circumference facing the opposing seat portions 20b and 26b, the backup valves 21b and 27b mitigate the force of the leaf valves 21a and 27a's return to their original position. This prevents the leaf valves 21a and 27a from forcefully colliding with the annular valve seats 20e and 26f, thereby suppressing the generation of abnormal noise. In addition, when the leaf valve 21a bends toward the valve seat member 20 due to pressure from the rear side, it receives support from the backup valve 21b, which reduces the amount of bending, and by bending toward the valve seat member 20, it can suppress rapid pressure fluctuations in the compression chamber R2. Furthermore, when the leaf valve 27a bends toward the valve seat member 26 due to pressure from the rear side, it receives support from the backup valve 27b, which reduces the amount of bending, and by bending toward the valve seat member 26, it can suppress rapid pressure fluctuations in the extension chamber R1.

[0083] As described above, the extension sub-valve EV and compression sub-valve CV are configured as damping valves by making the inner circumference of the valve bodies 21 and 27 a fixed end and the outer circumference a free end, and positioning the outer surfaces of the valve bodies 21 and 27 opposite the inner surfaces of the opposing seat portions 20b and 26b. However, a damping valve may also be configured by making the outer circumference of the valve body a fixed end and the inner circumference a free end, providing an opposing seat portion on the inner circumference of the valve body, and positioning the inner surface of the valve body opposite the outer surface of the opposing seat portion. As described above, when the valve bodies 21 and 27 bend toward the valve seat member and seat on the annular valve seats 20e and 26f, the ports 20c and 26d are completely closed. However, a groove communicating from the inner circumference to the outer circumference may be provided in the annular valve seats 20e and 26f to form an orifice, so that when the valve bodies 21 and 27 bend toward the valve seat member and seat on the annular valve seats 20e and 26f, liquid flow may be allowed only through the orifice.

[0084] Furthermore, in the compression-side sub-valve CV, which serves as a damping valve in this embodiment, the valve seat member 26 is provided radially on the fixed end side of the valve body 27 than the annular valve seat 26f, and faces the valve body 27 in the axial direction. It includes a restricting portion 26h that contacts the valve body 27 when the free end of the valve body 27 bends by more than a predetermined amount toward the valve seat member, thereby restricting the bending of the valve body 27.

[0085] With the compression sub-valve CV configured as a damping valve in this way, in addition to being supported by the backup valve 27b, when the intermediate portion of the valve body 27 is pressed toward the valve seat member and bends, and comes into contact with the regulating portion 26h, the intermediate portion of the valve body 27 is supported by the regulating portion 26h, preventing further bending of the valve body 27. Therefore, even if excessive pressure is applied to the valve body 27, the stress on the leaf valve 27a can be reduced, and fatigue of the leaf valve 27a can be further suppressed.

[0086] In the compression-side sub-valve CV, the outer diameter of the backup valve 27b is smaller than the inner diameter of the annular valve seat 26f, and only the leaf valve 27a can seat and unseat in the axial direction opposite to the annular valve seat 26f, and the backup valve 27b cannot contact the annular valve seat 26f. However, the outer diameter of the backup valve 27b may be increased so that when the valve body 27 bends toward the valve seat member, the backup valve 27b seats on the annular valve seat 26f and closes the port 26d. Furthermore, in the extension sub-valve EV, the outer diameter of the backup valve 21b is larger than the inner diameter of the annular valve seat 20e, and both the backup valve 21b and the leaf valve 21a face the annular valve seat 20e in the axial direction. When the valve body 21 bends toward the valve seat member, the backup valve 21b seats on the annular valve seat 20e and closes the port 20c. However, the outer diameter of the backup valve 21b may be made smaller than the inner diameter of the annular valve seat 20e, so that the leaf valve 21a seats on and off the annular valve seat 20e.

[0087] Furthermore, as shown in Figure 4, if the backup valve 21b has a notch 21b1 that penetrates the wall thickness axially and faces the leaf valve 21a, liquid can easily enter between the leaf valve 21a and the backup valve 21b through the notch 21b1, thereby suppressing sticking between the leaf valve 21a and the backup valve 21b. Therefore, with the extension sub-valve EV configured as a damping valve in this way, the valve body 21 will bend smoothly at the beginning of its deflection, preventing situations where the damping force characteristics change abruptly. The notch 21b1 should be provided in such a manner that it can prevent the passage of liquid when the valve body 21 comes into contact with the annular valve seat 20e, and its shape and number can be arbitrarily set.

[0088] Furthermore, as shown in Figure 5, if the backup valve 27b has a notch 27b1 that penetrates the wall thickness axially and faces the leaf valve 27a in the area that abuts against the restricting portion 26h, even if the backup valve 27b abuts against the restricting portion 26h, the notch 27b1 is provided, making it easier for liquid to enter between the leaf valve 27a and the backup valve 27b and between the restricting portion 26h and the backup valve 27b through the notch 27b1, thereby suppressing sticking between the leaf valve 27a and the backup valve 27b and between the restricting portion 26h and the backup valve 27b. Therefore, with the compression sub-valve CV configured as a damping valve in this way, the valve body 27 bends smoothly at the beginning of its deflection, preventing a sudden change in damping force characteristics. Furthermore, when the valve body 27 returns away from the valve seat member 26 from the state in which the backup valve 27b is in contact with the regulating portion 26h, the valve body 27 can return quickly, preventing a delay in opening of the port 26d. The notch 27b1 should be provided in such a manner that it can prevent the passage of liquid when the valve body 27 is in contact with the annular valve seat 26f, but it is preferable that it is provided so that it is not closed by the regulating portion 26h when the backup valve 27b is in contact with the regulating portion 26h. If the notch 27b1 is not closed by the restricting portion 26h, when the backup valve 27b comes into contact with the restricting portion 26h, liquid can more easily enter between the restricting portion 26h and the backup valve 27b through the notch 27b1, thereby further suppressing adhesion between the restricting portion 26h and the backup valve 27b.

[0089] Furthermore, the buffer D of this embodiment comprises a cylinder (outer tube) 1, a rod 2 inserted into the cylinder (outer tube) 1 so as to be movable in the axial direction, a buffer body A having at least an extension chamber (operating chamber) R1 and a compression chamber (operating chamber) R2 through which liquid passes as the rod 2 moves relative to the cylinder (outer tube) 1, and an extension sub-valve EV and a compression sub-valve CV as damping valves provided between the extension chamber (operating chamber) R1 and the compression chamber (operating chamber) R2. In the shock absorber D configured in this way, the extension sub-valve EV generates damping force when the liquid moves from the extension chamber R1 to the compression chamber R2, and closes the extension sub-passage EP when the liquid moves from the compression chamber R2 to the extension chamber R1, so the damping force characteristics on the extension side of the shock absorber D can be set independently. Similarly, the compression sub-valve CV generates damping force when the liquid moves from the compression chamber R2 to the extension chamber R1, and closes the compression sub-passage CP when the liquid moves from the extension chamber R1 to the compression chamber R2, so the damping force characteristics on the compression side of the shock absorber D can be set independently. Furthermore, the extension sub-valve EV and compression sub-valve CV, acting as damping valves, can increase the damping coefficient in the very low speed range to quickly build up the damping force in response to the switching of the extension and compression strokes, and can reduce the damping coefficient in the low speed range compared to the very low speed range, thus achieving damping force characteristics suitable for suppressing vibrations of the vehicle body and improving ride comfort in the vehicle.

[0090] In this embodiment, the shock absorber D has extension sub-valve EV and compression sub-valve CV as damping valves, which are provided in extension sub-passage EP and compression sub-passage CP that bypass the extension passage 3a and compression passage 3b in the piston 3, and the damping valves are arranged in parallel with the extension main valve 4 and compression main valve 5 in the piston 3, but the damping valves may also be used as either the extension main valve or the compression main valve. Furthermore, in this embodiment, the shock absorber D has extension sub-valve EV and compression sub-valve CV as damping valves, which are provided in extension sub-passage EP and compression sub-passage CP that bypass the extension passage 3a and compression passage 3b in the piston 3, but only the extension sub-valve EV or only the compression sub-valve CV may be provided in the shock absorber D.

[0091] Furthermore, although Figure 1 shows the two working chambers as the extension chamber R1 and the compression chamber R2, if the shock absorber D is a twin-tube type shock absorber with an outer shell as an outer tube around the outer circumference of the cylinder and a reservoir between the cylinder and the outer shell, then a damping valve will be placed between the compression chamber and the reservoir. Bu It may be provided. Therefore, the port in the damping valve may connect the extension chamber R1 and the compression chamber R2, or it may connect the compression chamber and the reservoir.

[0092] Furthermore, in the shock absorber D of this embodiment, the speed range in which damping force is generated mainly by the extension sub-valve EV and compression sub-valve CV, which act as damping valves, is set to the low-speed range. However, the speeds that distinguish between very low speed, low speed, and high speeds exceeding low speed can be arbitrarily set by the designer.

[0093] Although preferred embodiments of the present invention have been described in detail above, modifications, alterations, and changes are permitted as long as they do not deviate from the scope of the claims. [Explanation of symbols]

[0094] 1...Cylinder (outer tube), 2...Rod, 20,26...Valve seat members, 20b,26b...Opposite seat section, 20c,26d...Port, 20e,26f...Annular valve seat, 26h...Regulating section, 21,27...Valve body, 21a,27a...Leaf valve, 21b,27b...Backup valve, 21b1,27b1...Notch, A...Shock absorber body, CV...Compression side sub-valve (damping valve), D...Shock absorber, EV...Rebound side sub-valve (damping valve), R1...Rebound side chamber (actual chamber), R2...Compression side chamber (actual chamber)

Claims

1. An annular valve body in which one of the inner or outer circumferences is a fixed end and the other of the inner or outer circumferences is a free end, and deflection of the free end relative to the fixed end is permitted, The valve seat member comprises an annular valve seat having an annular opposing seat portion facing at least a part of the circumferential surface on the free end side of the valve body, a port provided radially on the fixed end side of the valve body than the opposing seat portion, and an annular valve seat provided between the opposing seat portion and the port, facing the valve body in the axial direction, and on which the valve body can seat and dissipate. The valve body comprises an annular leaf valve and an annular backup valve which is superimposed on the valve seat member side of the leaf valve and suppresses the deflection of the free end of the leaf valve toward the valve seat member side. A gap is provided between the valve body and the annular valve seat. A damping valve characterized by the following features.

2. The valve seat member is provided radially on the fixed end side of the valve body than the annular valve seat, and faces the valve body in the axial direction. It has a restricting portion that contacts the valve body when the free end of the valve body bends toward the valve seat member by a predetermined amount or more, thereby restricting the bending of the free end of the valve body. The damping valve according to feature 1.

3. The backup valve has a notch that penetrates the wall thickness in the axial direction. The damping valve according to feature 1.

4. The backup valve has a notch that penetrates the wall thickness axially in the area that contacts the regulating portion. The damping valve according to feature 2.

5. The gap formed between the circumferential surface on 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. The damping valve according to feature 1.

6. A buffer body having an outer tube, a rod inserted into the outer tube so as to be movable in the axial direction, and at least two working chambers through which liquid flows as the rod moves relative to the outer tube, The facility comprises a damping valve according to any one of claims 1 to 5, provided between the operating chambers. A buffer characterized by the following features.

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