Valve and shock absorber

Abstract

A valve (V) according to the present invention comprises a leaf valve (1) in which either an inner peripheral side or an outer peripheral side is a fixed end and deflection of a free end is permitted, and a valve seat member (2) which includes an annular fixed end-side seat portion (2c), a plurality of ports (2d) provided at intervals in the circumferential direction on the free end side of the fixed end-side seat portion (2c), a free end side seat portion (2e) with respect to which the free end side of the leaf valve (1) is seated and unseated, and a recessed portion (2f) provided over the entire width between the ports (2d) and the fixed end-side seat portion (2c), wherein the recessed portion (2f) comprises: a first recessed portion (2f1) that is provided in an annular shape on the fixed end-side seat portion side; and a second recessed portion (2f2) that is provided in an annular shape on the port side adjacent to the first recessed portion (2f1) and that is deeper than the first recessed portion (2f1).

Description

Valves and shock absorbers

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

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

[0003] Such a shock absorber includes, for example, a cylinder, a piston rod movably inserted into the cylinder, a piston slidably inserted into the cylinder to divide the interior of the cylinder into an extension-side chamber and a compression-side chamber, a free piston slidably inserted into the cylinder to divide an air chamber below the compression-side chamber in the cylinder, a damping passage provided in the piston to connect the extension-side chamber and the compression-side chamber, and a valve provided in the damping passage.

[0004] The valve includes, for example, a piston slidably inserted into a cylinder of a shock absorber, dividing the interior of the cylinder into an expansion-side chamber and a compression-side chamber, and including a port communicating the expansion-side chamber and the compression-side chamber, and an annular leaf valve fixed to the piston rod with its inner circumferential side as a fixed end and its outer circumferential side as a free end, which is allowed to flex and is stacked on the piston. The piston also includes an annular seat portion provided on the inner circumferential side of the port and on which the inner circumferential side of the leaf valve is stacked, and an outer circumferential seat portion surrounding the port and abutting against the free end of the leaf valve. The leaf valve receives pressure from hydraulic oil passing through the port, causing its outer circumferential side (free end) to flex and separate from the outer circumferential seat portion, opening the port, while providing resistance to the flow of hydraulic oil passing through a gap between the leaf valve and the outer circumferential seat portion, thereby generating a damping force.

[0005] In a valve configured in this way, when the leaf valve bends significantly on its periphery, a gap forms between it and the annular seat, which had been in close contact with it until then, causing hydraulic oil passing through the port to be sucked into the gap. Many of the components that make up the shock absorber are manufactured by cutting, and are cleaned before assembly to remove cutting chips and burrs. However, any chips that remain after the cleaning process can remain inside the shock absorber as contaminants. When the leaf valve bends significantly, contaminants floating in the hydraulic oil enter the gap and become trapped between the leaf valve and the annular seat. This can cause problems such as an inability to seal the entire outer seat even after the leaf valve is released, making it impossible to close the port, or the leaf valve lifting off the outer seat, causing the outer periphery of the leaf valve to vibrate and generate abnormal noise.

[0006] Therefore, in conventional valves, as disclosed in, for example, JPS63-14038U, the outer diameter of the annular seat portion is reduced and a deep recess is provided between the annular seat and the port to prevent contaminants from getting caught in the leaf valve, thereby solving the above problem (see, for example, Patent Document 1).

[0007] JPS63-14038U

[0008] Conventional valves can prevent contaminants from getting caught between the leaf valve and the annular seat portion of the valve seat member, but the radial width of the annular seat portion must be narrowed.

[0009] If the radial width of the annular seat portion is narrowed, a deep recess is formed adjacent to the annular seat portion, which reduces the strength of the annular seat portion and causes sagging during molding of the annular seat portion, making it more likely that the flatness of the surface on which the leaf valve sits will vary.This variation will have a greater impact on the seating position of the leaf valve, resulting in a new problem of greater variation in the valve characteristics.

[0010] The new problem could be solved by increasing the radial width of the annular seat portion, but then a recess could not be formed between the annular seat portion and the port, and the previous problem of contaminants getting caught in the leaf valve could not be solved. On the other hand, if a recess was formed between the annular seat portion and the port and the radial width of the annular seat portion was increased, the valve seat member would become larger and would no longer be suitable for use in a shock absorber, so it is difficult to adopt such a measure.

[0011] Therefore, an object of the present invention is to provide a damping valve that can prevent contaminants from getting caught in the leaf valve and also suppress variations in characteristics, and a shock absorber that can generate a stable damping force.

[0012] In order to solve the above problem, the valve of the present invention comprises: an annular leaf valve having one of the inner and outer circumferential sides as a fixed end and the other of the inner and outer circumferential sides as a free end; an annular fixed end seat portion that abuts the fixed end of the leaf valve; a plurality of ports arranged circumferentially spaced apart on the free end side of the leaf valve on the fixed end seat portion; a free end seat portion that surrounds the ports together with the fixed end seat portion and on which the free end side of the leaf valve is seated and separated; and a valve seat member having a recess provided between the port and the fixed end seat portion, wherein the recess has a first recess that is arranged annularly on the fixed end seat portion side, and a second recess that is arranged annularly on the port side adjacent to the first recess and is deeper than the first recess.

[0013] In a valve configured in this manner, a recess is provided between the fixed-end seat portion and the port, the recess having a shallow first recess on the fixed-end seat portion side and a deep second recess on the port side, so that even if the free end of the leaf valve bends, liquid is less likely to be drawn into the recess, and even if contaminants are present in the liquid passing through the port, the contaminants are captured in the deep second recess before entering the first recess, thereby preventing them from entering between the first recess and the compression-side leaf valve. Furthermore, in a valve configured in this manner, even if the recess is provided adjacent to the compression-side port side of the fixed-end seat portion, a decrease in the strength of the fixed-end seat portion is suppressed, and flatness errors are less likely to occur during molding of the fixed-end seat portion.

[0014] Fig. 1 is a longitudinal sectional view of a shock absorber to which a valve according to an embodiment of the present invention is applied. Fig. 2 is an enlarged sectional view of the valve according to an embodiment of the present invention. Fig. 3 is a plan view of a valve seat member in the valve according to an embodiment of the present invention. Fig. 4(a) is a partially enlarged sectional view of a first modified example of the valve seat member in the valve according to an embodiment of the present invention. Fig. 4(b) is a partially enlarged sectional view of a second modified example of the valve seat member in the valve according to an embodiment of the present invention. Fig. 4(c) is a partially enlarged sectional view of a third modified example of the valve seat member in the valve according to an embodiment of the present invention.

[0015] The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1 , a valve V in one embodiment is applied to a piston portion of a shock absorber D, and includes a compression-side leaf valve 1 as an annular leaf valve having an inner circumferential side as a fixed end and an outer circumferential side as a free end, and a piston 2 as a valve seat member having a compression-side port 2d as a port opened and closed by the compression-side leaf valve 1. As shown in FIG. 1 , the shock absorber D to which the valve V is applied includes a shock absorber main body A that is extendable and contractible and has a cylinder 10 as an outer tube and a rod 11 movably inserted into the cylinder 10, and a valve V provided between an expansion-side chamber R1 and a compression-side chamber R2 as two working chambers provided in the shock absorber main body A. The shock absorber D is installed between a vehicle body and an axle of a vehicle (not shown) to suppress vibrations of the vehicle body and wheels.

[0016] Hereinafter, a detailed description will be given of each part of the valve V and the shock absorber D. First, the respective parts of the shock absorber D will be described. As shown in Fig. 1 , the shock absorber main body A includes a cylindrical cylinder 10 with a bottom as an outer tube, a rod 11 movably inserted into the cylinder 10, and a piston 2 as a valve seat member that is connected to the rod 11 and movably inserted into the cylinder 10, and that divides the interior of the cylinder 10 into an expansion-side chamber R1 and a compression-side chamber R2 as working chambers.

[0017] A bracket (not shown) is provided at the base end of the rod 11, which is the upper end in Fig. 1, and the rod 11 is connected to one of the vehicle body and the axle via the bracket (not shown). A bracket (not shown) is also provided at the bottom 10a of the cylinder 10, and the cylinder 10 is connected to the other of the vehicle body and the axle via the bracket (not shown).

[0018] In this way, shock absorber D is interposed between the vehicle body and the axle. When the vehicle travels on an uneven road surface and the wheels vibrate up and down relative to the vehicle body, rod 11 moves in and out of cylinder 10, expanding and contracting shock absorber D, and piston 2 moves up and down (axially) within cylinder 10.

[0019] The shock absorber main body A also includes an annular rod guide 13 that closes the upper end of the cylinder 10 and through which the rod 11 is slidably inserted, forming an enclosed space inside the cylinder 10. A free piston 14 is slidably inserted into the cylinder 10 on the opposite side of the piston 2 from the rod 11.

[0020] A liquid chamber L is formed above the free piston 14 in the cylinder 10, and an air chamber G is formed below it. The liquid chamber L is further divided by the piston 2 into an extension-side chamber R1 on the rod 11 side and a compression-side chamber R2 on the piston 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 main 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.

[0021] When the rod 11 retracts from the cylinder 10 during extension of the shock absorber D, the free piston 14 moves upward within the cylinder 10 in accordance with the volume of the retracted rod 11, expanding the air chamber G and compensating for the volume of the rod 11 retracted from the cylinder 10. Conversely, when the shock absorber D retracts, the rod 11 enters the cylinder 10, and the free piston 14 moves downward within the cylinder 10 in accordance with the volume of the entered rod 11, contracting the air chamber G and compensating for the volume of the rod 11 entering the cylinder 10. Note that instead of the free piston 14, a bladder, 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 changed as appropriate.

[0022] As described above, in this embodiment, the shock absorber D is a single-rod, single-cylinder shock absorber. When the shock absorber D extends or retracts, the free piston (movable partition) 14 expands or contracts the air chamber G, thereby compensating for the volume of the rod 11 moving in and out of the cylinder 10. However, the configuration for this volume compensation can also be modified as appropriate. For example, if the free piston 14 and the air chamber G are eliminated and an outer tube is provided outside the cylinder 10, and a reservoir for storing liquid and gas is formed between the cylinder 10 and the outer tube, the shock absorber may be configured as a twin-cylinder shock absorber, in which the reservoir compensates for the volume of the rod 11 moving in and out of the cylinder 10. Note that the reservoir may be formed in a tank separate from the cylinder 10. The shock absorber D may also be configured as a double-rod shock absorber in which the piston 2 is attached to the center of the rod 11 and the ends of the rod 11 protrude from both ends of the cylinder 10.

[0023] The rod 11 has a reduced outer diameter at the tip end, and includes a small diameter portion 11a having a small outer diameter at the tip end, a large diameter portion 11b having an outer diameter larger than that of the small diameter portion 11a and provided above the small diameter portion 11a in FIG. 1, a step portion 11c provided at the boundary between the small diameter portion 11a and the large diameter portion 11b, and a threaded portion 11d provided on the outer periphery of the tip end of the small diameter portion 11a.

[0024] The valve V of this embodiment is attached to a rod 11 and applied to a piston portion of a shock absorber D. As shown in Fig. 1, the piston 2 serving as a valve seat member constituting the valve V is annular and fitted onto the outer periphery of the small diameter portion 11a of the rod 11, and is fixed to the rod 11 by a piston nut 15 that is threaded onto a threaded portion 11d of the rod 11. The piston 2 is also attached to the rod 11, and its outer periphery is in sliding contact with the inner periphery of the cylinder 10, dividing the interior of the cylinder 10 into an expansion-side chamber R1 and a compression-side chamber R2 that serve as working chambers.

[0025] More specifically, the piston 2 comprises an annular main body portion 2a, a cylindrical portion 2b provided on the outer periphery of the lower end of the main body portion 2a in FIG. 2, an annular fixed end seat portion 2c provided on the inner periphery of the upper end of the main body portion 2a in FIG. 2, compression side ports 2d as a plurality of ports provided at intervals in the circumferential direction on the outer periphery of the fixed end seat portion 2c of the main body portion 2a and penetrating the main body portion 2a in the axial direction, and a cylindrical portion 2b provided at the upper end of the main body portion 2a in FIG. 2 on the outer periphery of the compression side port 2d and connected to the fixed end side seat portion 2c and the compression side port 2d. 2, a recess 2f is provided across the entire width between the compression side port 2d and the fixed end side seat portion 2c at the upper end of the main body portion 2a in FIG. 2, an expansion side port 2g is provided at the lower end of the main body portion 2a in FIG. 2, opening from the inner side of the compression side port 2d and opening at the upper end of the main body portion 2a in FIG. 2 toward the outer side than the free end side seat portion 2e, and an annular outer peripheral seat portion 2h is provided at the lower end of the main body portion 2a in FIG. 2, between the compression side port 2d and the expansion side port 2g.

[0026] Piston rings 2i are attached to the outer peripheries of the main body portion 2a and the cylindrical portion 2b, with their outer peripheries in sliding contact with the inner periphery of the cylinder 10. As shown in Figures 2 and 3, the fixed-end-side seat portion 2c is provided on the inner periphery of the upper end of the main body portion 2a in Figure 2, has an annular shape, protrudes upward beyond the recessed portion 2f provided on the outer periphery, and has a flat surface at its upper end on which the compression-side leaf valve 1 is placed.

[0027] The free end side seat portion 2e is annular and is provided on the outer periphery of the upper end of the main body portion 2a in Figure 2, and functions as a valve seat on which the free end of the compression side leaf valve 1 seats and leaves.It protrudes upward beyond the recess 2f and the outlet end of the compression side port 2d, and has a flat surface at its upper end on which the compression side leaf valve 1 seats and leaves.

[0028] The compression-side ports 2d are provided at the expansion-side chamber end, which is the upper end of the main body portion 2a in FIG. 2, on the outer periphery of the fixed-end-side seat portion 2c in FIG. 3, with eight ports evenly spaced around the same circumference. They open from the upper end of the main body portion 2a in FIG. 2, extend along the axial direction, and connect to the lower end of the main body portion 2a. The compression-side ports 2d are also located at the upper end of the main body portion 2a in FIG. 2, and open to the inner periphery of the annular free-end-side seat portion 2e. Furthermore, the compression-side ports 2d are located at the lower end of the main body portion 2a in FIG. 2, and open to the outer periphery of the outer periphery seat portion 2h. In this way, the compression-side ports 2d communicate between the expansion-side chamber R1 and the compression-side chamber R2.

[0029] An inner seat portion 2j and an outer seat portion 2h disposed on the outer periphery of the inner seat portion 2j are provided at the lower end of the main body portion 2a in Fig. 2. The inner seat portion 2j and the outer seat portion 2h are both annular and protrude in the axial direction from the lower end of the main body portion 2a, and an annular groove is formed between the inner seat portion 2j and the outer seat portion 2h.

[0030] The expansion-side ports 2g open from an annular groove between the inner circumferential seat portion 2j and the outer circumferential seat portion 2h at the compression-side chamber side end, which is the lower end of the main body portion 2a in Fig. 2, and communicate with the outer periphery of the free-end-side seat portion 2e at the upper end of the main body portion 2a in Fig. 2, thereby connecting the expansion-side chamber R1 and the compression-side chamber R2. In this embodiment, the expansion-side ports 2g obliquely penetrate between the compression-side ports 2d, 2d of the main body portion 2a so as not to interfere with the compression-side ports 2d, and open to the outer periphery of the free-end-side seat portion 2e at the upper end of the main body portion 2a in Fig. 2, and eight expansion-side ports 2g are provided at equal intervals in the circumferential direction of the main body portion 2a.

[0031] The recess 2f is provided at the upper end of the main body 2a in Fig. 2, and includes a first recess 2f1 provided on the fixed-end-side seat portion side, which is the inner peripheral side, and a second recess 2f2 provided adjacent to the first recess 2f1 on the outer peripheral side, which is the port side, and which is deeper than the first recess 2f1. In this embodiment, the recess 2f is provided in an annular shape around the entire circumference between the fixed-end-side seat portion 2c and the compression-side port 2d, and both the first recess 2f1 and the second recess 2f2 are also formed in annular shapes.

[0032] 2, the radial width of the first recess 2f1 is wider than the radial width of the bottom surface of the second recess 2f2 and is further wider than the radial width of the opening side of the second recess 2f2, and the depth of the first recess 2f1 is shallower than the depth of the second recess 2f2. Note that in the valve V of this embodiment, the compression side port 2d opens to the inclined surface on the outer periphery side of the second recess 2f2, but it may also open to the outer periphery of the second recess 2f2 without contacting the second recess 2f2.

[0033] The height of the upper end surface of the first recess 2f1 is lower than the height of the upper end surfaces of the fixed-end-side sheet portion 2c and the free-end-side sheet portion 2e in Fig. 2, forming a recess with a certain depth between the fixed-end-side sheet portion 2c and the free-end-side sheet portion 2e. In this embodiment, the depth of the first recess 2f1 from the upper end of the fixed-end-side sheet portion 2c in Fig. 2 is set to approximately 0.1 mm to 0.5 mm. The second recess 2f2 is an annular recess that is connected to the outer periphery of the first recess 2f1 and is deeper than the first recess 2f1.

[0034] The valve V of this embodiment also includes lands 2k, which are protrusions projecting upward in FIG. 2 from the first recess 2f1. As shown in FIG. 3, the lands 2k are provided on the outer periphery of the first recess 2f1, with eight lands 2k provided radially inward of each compression-side port 2d. The upper end surface of each land 2k in FIG. 2 is set to be tangent to a line connecting the upper end surface of the fixed-end seat portion 2c and the upper end surface of the free-end seat portion 2e. The land 2k may be a single annular or C-shaped land, or multiple lands 2k may be provided intermittently in the circumferential direction as shown in FIG. 3. When multiple lands 2k are provided, they may be arc-shaped or may have a shape other than an arc-shaped. When the land 2k is annular, the recess 2f may be divided radially into an inner side and an outer side of the land 2k. Although the land 2k is provided radially inward of each compression-side port 2d, it may be provided elsewhere than the radially inward side of the compression-side port 2d.

[0035] The compression-side leaf valve 1 serving as a leaf valve is a laminated leaf valve formed by laminating a plurality of annular plates, and is laminated on the upper end of the piston 2 serving as a valve seat member in FIG. 2 and is fixed to the outer periphery of the small diameter portion 11a of the rod 11 together with the piston 2. The compression-side leaf valve 1 has an inner periphery of the lowest annular plate 1a as a fixed end 1b fixed to the rod 11 and abutting against a fixed end seat portion 2c, and an outer periphery as a free end 1c which is allowed to bend in a direction away from the piston 2 and causes the free end to be seated on and unseated from a free end seat portion 2e.

[0036] When the compression-side leaf valve 1 has its free end 1c seated on the free-end-side seat 2e, it is in close contact with the fixed-end-side seat 2c and the free-end-side seat 2e, blocking the outlet end of the compression-side port 2d that opens between the fixed-end-side seat 2c and the free-end-side seat 2e. When the pressure from the compression-side port 2d bends the free end 1c and separates it from the free-end-side seat 2e, the compression-side port 2d is opened and resistance is applied to the flow of liquid passing through the gap formed between the free-end-side seat 2e and the free-end-side seat 2e. Furthermore, even when the compression-side leaf valve 1 is pressed toward the piston 2 by the pressure from the expansion-side chamber R1 with its free end 1c seated on the free-end-side seat 2e, the land 2k supports an intermediate portion between the fixed-end-side seat 2c and the free-end-side seat 2e of the compression-side leaf valve 1, and this intermediate portion bends convexly toward the recess 2f, preventing a large stress from acting on the compression-side leaf valve 1. 2, which is the abutment surface of the land 2k that abuts against the compression-side leaf valve 1, is set to be tangent to a straight line connecting the upper end surface of the fixed-end-side seat portion 2c and the upper end surface of the free-end-side seat portion 2e, so when the compression-side leaf valve 1 is supported by the land 2k, the section from the part of the compression-side leaf valve 1 that abuts against the outer peripheral edge of the fixed-end-side seat portion 2c to the inner peripheral edge of the free-end-side seat portion 2e is supported without being significantly bent along the way. Therefore, because it is supported by the land 2k, the middle part of the compression-side leaf valve 1 does not bend toward the piston 2 under pressure from the expansion-side chamber R1, and fatigue of the compression-side leaf valve 1 is effectively suppressed. Furthermore, since the land 2k is required to be able to support the middle portion of the compression side leaf valve 1 without hindering the compression side leaf valve 1 from seating on the free end side seat portion 2e, the height of the contact surface of the land 2k that contacts the compression side leaf valve 1 may be set to less than the height tangent to the straight line connecting the upper end surface of the fixed end side seat portion 2c and the upper end surface of the free end side seat portion 2e, as long as it protrudes upward from the first recess 2f1 in Figure 2.

[0037] 2, a circular valve stopper 4 attached to the outer periphery of the small diameter portion 11a of the rod 11 is stacked above the compression-side leaf valve 1. When the free end 1c of the compression-side leaf valve 1 bends upward away from the piston 2 in the figure and abuts against the upper surface of the outer periphery of the compression-side leaf valve 1, the valve stopper 4 restricts further bending of the compression-side leaf valve 1 in the direction away from the piston 2, thereby protecting the compression-side leaf valve 1 from excessive stress.

[0038] The piston 2 serving as a valve seat member is manufactured by sintering, while the compression-side leaf valve 1 serving as a leaf valve is formed from an annular plate obtained by punching a steel plate, and the hardness of the piston 2 is lower than that of the compression-side leaf valve 1. The above-described manufacturing methods and materials for the piston 2 and the compression-side leaf valve 1 are one example, and in order to make the hardness of the piston 2 lower than that of the compression-side leaf valve 1, it is sufficient to select a material such that the hardness of the piston 2 is lower than that of the compression-side leaf valve 1, and the manufacturing method can be designed and modified as desired.

[0039] The extension-side leaf valves 3 are stacked below the piston 2 in FIG. 1. The extension-side leaf valves 3 are laminated leaf valves formed by stacking a plurality of annular plates, and are stacked at the lower end of the piston 2 as a valve seat member in FIG. 2, and are fixed to the outer periphery of the small diameter portion 11a of the rod 11 together with the piston 2. The inner periphery of the uppermost annular plate of the extension-side leaf valve 3 abuts against the inner periphery seat portion 2j, and the inner periphery side fixed to the rod 11 is the fixed end, and the outer periphery side is the free end. Therefore, the extension-side leaf valves 3 are allowed to bend in a direction away from the piston 2 on the outer periphery side, which is the free end side, and the outer periphery side is seated on and removed from the outer periphery seat portion 2h.

[0040] When the free end of the expansion-side leaf valve 3 is seated on the outer peripheral seat portion 2h, it is in close contact with the inner peripheral seat portion 2j and the outer peripheral seat portion 2h, blocking the outlet end of the expansion-side port 2g that opens between the inner peripheral seat portion 2j and the outer peripheral seat portion 2h. When the free end is bent by pressure from the expansion-side port 2g side and separated from the outer peripheral seat portion 2h, the expansion-side port 2g is opened and resistance is applied to the flow of liquid passing through the gap generated between the expansion-side leaf valve 3 and the outer peripheral seat portion 2h.

[0041] The valve stopper 4, the compression-side leaf valve 1, the piston 2, and the extension-side leaf valve 3 configured in this manner are assembled in this order to the outer periphery of the small diameter portion 11 a of the rod 11, and then are fixed to the rod 11 by being sandwiched between the piston nut 15, which is screwed to the threaded portion 11 d of the small diameter portion 11 a, and the step portion 11 c of the rod 11.

[0042] The valve V and shock absorber D are configured as described above, and their operation will be described below. First, when the shock absorber D performs an extension operation and the piston 2 moves upward in FIG. 1 relative to the cylinder 10, the upward movement of the piston 2 in FIG. 1 causes the liquid in the expansion-side chamber R1, which is compressed, to bend the expansion-side leaf valve 3 and move through the expansion-side port 2g to the contraction-side chamber R2. Therefore, when the shock absorber D performs an extension operation, the expansion-side leaf valve 3 provides resistance to the flow of liquid from the expansion-side chamber R1 to the contraction-side chamber R2, increasing the pressure in the expansion-side chamber R1. As the shock absorber D performs an extension operation, the free piston 14 rises in FIG. 1 in accordance with the volume of the rod 11 retracted from the cylinder 10, expanding the air chamber G and compensating for the volume of the rod 11 retracted from the cylinder 10.

[0043] On the other hand, when the shock absorber D contracts and the piston 2 moves downward in FIG. 1 relative to the cylinder 10, the downward movement of the piston 2 in FIG. 1 causes the liquid in the compression-side chamber R2 to bend the compression-side leaf valve 1, pass through the compression-side port 2d, and move to the extension-side chamber R1.

[0044]

[0033] More specifically, when the shock absorber D is contracting, the pressure in the compression-side chamber R2 acts on the underside of the compression-side leaf valve 1 in Figure 2 through the compression-side port 2d, and the free end 1c of the compression-side leaf valve 1 is bent and separated from the free-end-side seat portion 2e by the action of this pressure, and the liquid in the compression-side chamber R2 moves to the expansion-side chamber R1 through the gap formed between the compression-side leaf valve 1 and the free-end-side seat portion 2e. Therefore, when the shock absorber D is contracting, the compression-side leaf valve 1 applies resistance to the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1, increasing the pressure in the compression-side chamber R2, and the shock absorber D generates a compression-side damping force that hinders the contraction. Note that, as the shock absorber D contracts, the free piston 14 moves downward in Figure 1 in accordance with the volume of the rod 11 entering the cylinder 10, thereby reducing the air chamber G and compensating for the volume of the rod 11 entering the cylinder 10.

[0045] Here, during the contraction operation of the shock absorber D, the compression-side leaf valve 1 has its inner circumferential side as the fixed end 1b in contact with the fixed-end seat portion 2c and its outer circumferential side as the free end 1c seated on the free-end seat portion 2e until it opens, and a recess 2f is provided on the inner circumferential side of the compression-side port 2d, and the recess 2f faces, with a gap therebetween, the underside of the compression-side leaf valve 1. Therefore, even if the gap between the compression-side leaf valve 1 and the recess 2f expands when the free end 1c of the compression-side leaf valve 1 bends to open, the first recess 2f1 and the second recess 2f2 of the recess 2f are already filled with liquid, and liquid is unlikely to be drawn into the recess 2f even when the compression-side leaf valve 1 bends.

[0046] In addition, the recess 2f has a second recess 2f2 that is deeper than the shallow first recess 2f1 and is located closer to the compression side port 2d than the shallow first recess 2f1, so that contaminants such as cutting chips and iron powder in the liquid are captured by the deeper second recess 2f2 before they enter the first recess 2f1, thereby preventing them from entering between the first recess 2f1 and the compression side leaf valve 1.

[0047] Furthermore, in the valve V of this embodiment, a land 2k is provided on the inside, which is the fixed end side of the compression side leaf valve 1 in the radial direction of the compression side port 2d, so even if the bending action of the compression side leaf valve 1 causes contaminants to overcome the second recess 2f2 and move into the first recess 2f1, the land 2k gets in the way, making it difficult for them to reach the first recess 2f1.

[0048] Furthermore, even if contaminants larger than the difference in height between the compression-side leaf valve 1 and the bottom surface of the first recess 2f1 of the piston 2 when the compression-side leaf valve 1 is seated on the free-end-side seat portion 2e enter the first recess 2f1 when the compression-side leaf valve 1 deflects, in the valve V of this embodiment, the hardness of the piston 2 is lower than that of the compression-side leaf valve 1. Therefore, when the compression-side leaf valve 1 deflects many times and repeatedly seats and disengages from the free-end-side seat portion 2e, the contaminants are repeatedly struck by the compression-side leaf valve 1 and embedded in the bottom of the first recess 2f1, and eventually do not interfere with the compression-side leaf valve 1. Therefore, in the valve V of this embodiment, even if contaminants enter the first recess 2f1, the contaminants are embedded and captured in the main body 2a of the piston 2, preventing the compression-side leaf valve 1 from floating up from the free-end-side seat portion 2e and enabling the liquid in the shock absorber D to be purified.

[0049] Furthermore, because the recess 2f is divided into a shallow first recess 2f1 and a deep second recess 2f2 on the fixed-end side, compared to the conventional valve V in which a recess whose depth suddenly increases is formed in the fixed-end seat portion, even if the recess 2f is provided adjacent to the compression-side port side of the fixed-end seat portion 2c, a decrease in the strength of the fixed-end seat portion 2c is suppressed, and errors in flatness are less likely to occur during molding of the fixed-end seat portion 2c. As a result, the seating of the fixed-end seat portion 2c of the piston 2 of the compression-side leaf valve 1 is stable, and the resistance that the valve V provides to the liquid flow is stable.

[0050] As described above, the valve V of this embodiment comprises: a compression side leaf valve (leaf valve) 1 that is annular and has an inner circumferential side that is a fixed end and an outer circumferential side that is a free end; an annular fixed end side seat portion 2c that abuts against the fixed end of the compression side leaf valve (leaf valve) 1; a plurality of compression side ports (ports) 2d that are provided at intervals in the circumferential direction on the free end side of the leaf valve 1 in the fixed end side seat portion 2c; a free end side seat portion 2e that surrounds the compression side port (port) 2d together with the fixed end side seat portion 2c and on which the free end side of the compression side leaf valve (leaf valve) 1 is seated and separated; and a piston (valve seat member) 2 that has a recess 2f provided between the compression side port (port) 2d and the fixed end side seat portion 2c, wherein the recess 2f comprises a first recess 2f1 that is provided annularly on the fixed end side seat portion side; and a second recess 2f2 that is provided annularly on the port side adjacent to the first recess 2f1 and is deeper than the first recess 2f1.

[0051] In the valve V configured in this manner, a recess 2f is provided between the fixed-end-side seat portion 2c and the compression-side port (port) 2d, and the recess 2f includes a first recess 2f1 that is shallow on the fixed-end-side seat portion side and a second recess 2f2 that is deep on the port side. This makes it difficult for liquid to be drawn into the recess 2f even when the free end 1c of the compression-side leaf valve (leaf valve) 1 is deflected, and even if contaminants are present in the liquid passing through the compression-side port (port) 2d, the contaminants are captured in the deep second recess 2f2 before entering the first recess 2f1, thereby preventing them from entering between the first recess 2f1 and the compression-side leaf valve (leaf valve) 1. Furthermore, in the valve V configured in this manner, even if the recess 2f is provided adjacent to the compression-side port side of the fixed-end-side seat portion 2c, a decrease in the strength of the fixed-end-side seat portion 2c is suppressed, and errors in flatness are less likely to occur during molding of the fixed-end-side seat portion 2c.

[0052] As described above, the valve V of this embodiment can prevent the trapping of contaminants in the compression side leaf valve (leaf valve) 1 and suppress variations in damping force, thereby achieving stable characteristics without variations. Furthermore, the valve V of this embodiment can prevent the trapping of contaminants in the compression side leaf valve (leaf valve) 1, thereby preventing the generation of abnormal noise due to the trapping of contaminants in the compression side leaf valve (leaf valve) 1.

[0053] In the valve V of this embodiment, the depth of the first recess 2f1 in the recess 2f is constant. By making the depth of the first recess 2f1 constant in this manner, it is possible to prevent contaminants from being caught by the compression-side leaf valve 1 while suppressing a decrease in the strength of the piston (valve seat member) 2, and it is easier to ensure the strength of the fixed-end-side seat portion 2c, thereby suppressing variations in the characteristics of the valve V and effectively suppressing variations in the damping force. As shown in FIG. 4 , the depth of the first recess 2f1 may be increased toward the compression-side port 2d, as long as it is not greater than the depth of the second recess 2f2. For example, the bottom surface of the first recess 2f1 may be tapered as shown in FIG. 4( a), curved as shown in FIG. 4( b), or gradually deepened in a stepped manner as shown in FIG. 4( c). Furthermore, when the bottom surface of the first recess 2f1 is a tapered surface, the inclination angle of the bottom surface of the first recess 2f1 is smaller than the inclination angle of the inner inclined surface of the bottom surface of the second recess 2f2, and the gradient rate of the bottom surface of the first recess 2f1 is lower than the gradient rate of the inner inclined surface of the bottom surface of the second recess 2f2.

[0054] In this way, when the depth of the first recess 2f1 is set to become deeper as it approaches the compression side port (port) 2d, the gap between the compression side leaf valve (leaf valve) 1 and the first recess 2f1 becomes wider as it approaches the compression side port (port) 2d, so that the force sucking liquid into the first recess 2f1 when the compression side leaf valve (leaf valve) 1 bends is weakened, thereby improving the effect of preventing contaminants from entering the first recess 2f1.

[0055] Furthermore, the piston (valve seat member) 2 in the valve V of this embodiment is provided with a land 2k that protrudes from the bottom of the first recess 2f1 and abuts against the valve seat member side of the compression-side leaf valve (leaf valve) 1 to support the compression-side leaf valve (leaf valve) 1. With the valve V configured in this manner, even if the recess 2f is provided between the fixed-end side seat portion 2c and the free-end side seat portion 2e, the land 2k supports the compression-side leaf valve (leaf valve) 1, preventing the compression-side leaf valve (leaf valve) 1 from receiving pressure from the anti-piston (valve seat member) side and bending toward the piston (valve seat member) and causing a large stress to act on the compression-side leaf valve (leaf valve) 1, and suppressing fatigue of the compression-side leaf valve (leaf valve) 1.

[0056] Furthermore, the land 2k in the valve V of this embodiment is provided at a position radially opposite the compression-side port (port) 2d. With the valve V configured in this manner, even if the bending action of the compression-side leaf valve (leaf valve) 1 causes contaminants to move over the second recess 2f2 and into the first recess 2f1, the land 2k prevents the contaminants from entering the first recess 2f1, thereby further preventing the contaminants from entering the first recess 2f1.

[0057] Furthermore, the hardness of the piston (valve seat member) 2 in the valve V of this embodiment is lower than the hardness of the compression-side leaf valve (leaf valve) 1. According to the valve V configured in this manner, the hardness of the piston (valve seat member) 2 is lower than the hardness of the compression-side leaf valve (leaf valve) 1. Therefore, even if contaminants enter the first recess 2f1, when the compression-side leaf valve (leaf valve) 1 bends and returns, the contaminants are struck and embedded in and captured by the piston (valve seat member) 2, thereby preventing the compression-side leaf valve (leaf valve) 1 from floating up from the free-end-side seat portion 2e and enabling the liquid in the shock absorber D to be purified.

[0058] Furthermore, the recess 2f in the valve V of this embodiment is provided across the entire width between the compression side port 2d and the fixed end side seat portion 2c in the piston (valve seat member) 2. In the valve V configured in this manner, the recess 2f is provided across the entire width between the compression side port 2d and the fixed end side seat portion 2c in the piston (valve seat member) 2, which further suppresses the drawing of liquid into the recess 2f due to the bending of the free end 1c of the compression side leaf valve (leaf valve) 1, thereby further suppressing the intrusion of contaminants between the first recess 2f1 and the compression side leaf valve (leaf valve) 1.

[0059] Furthermore, in the valve V of this embodiment, the depth of the first recess 2f1 from the fixed end side seat portion 2c is set in the range of 0.1 mm to 0.5 mm, so that a sufficiently large gap is formed between the compression side leaf valve (leaf valve) 1 and the bottom of the first recess 2f1, thereby weakening the force that sucks liquid into the first recess 2f1 when the compression side leaf valve (leaf valve) 1 bends, thereby improving the effect of preventing contaminants from entering the first recess 2f1.

[0060] The shock absorber D of this embodiment includes a cylinder (outer tube) 10, a rod 11 movably inserted into the cylinder (outer tube) 10 in the axial direction, a shock absorber main body A having at least an expansion-side chamber (working chamber) R1 and a compression-side chamber (working chamber) R2 through which liquid flows as the rod 11 moves relative to the cylinder (outer tube) 10, and a valve V provided between the expansion-side chamber (working chamber) R1 and the compression-side chamber (working chamber) R2. According to the shock absorber D configured in this manner, the valve V provides a stable resistance to the flow of liquid without variation, thereby generating a stable damping force without variation. Therefore, using the shock absorber D in a vehicle suspension can improve the ride comfort of the vehicle and prevent abnormal noise caused by contaminants getting caught in the compression-side leaf valve (leaf valve) 1.

[0061] 1, the two working chambers are the expansion-side chamber R1 and the compression-side chamber R2, and the leaf valve is the compression-side leaf valve 1, but the valve of the present invention may be applied to a valve that generates an expansion-side damping force by using the expansion-side leaf valve 3 as the leaf valve and the expansion-side port 2g as the port and providing a recess on the compression-side chamber side of the piston 2. Also, in the case where the shock absorber D is a twin-cylinder shock absorber that has 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 valve seat member and a leaf valve may be provided between the compression-side chamber and the reservoir, and a valve V may be provided between the compression-side chamber and the reservoir.

[0062] Furthermore, as described above, both the fixed end side sheet portion 2c and the free end side sheet portion 2e are annular sheet portions, and the recess 2f is also annular, but the free end side sheet portion may be a petal-shaped sheet portion that is connected to the outer periphery of the annular fixed end side sheet portion 2c and independently surrounds each port, and in that case, the recess provided between the fixed end side sheet portion and the port may also not be annular, but may be provided with a recess having a first recess and a second recess that are independently provided on the fixed end side sheet portion side of each port.

[0063] In the above-described embodiment, the inner circumferential side of the compression-side leaf valve (leaf valve) 1 is fixed to the small-diameter portion 11a of the rod 11, and the compression-side leaf valve (leaf valve) 1 is configured as an outward-opening valve with the inner circumferential side as the fixed end 1b and the outer circumferential side as the free end 1c, allowing for bending on the outer circumferential side. However, if the leaf valve is configured as an inward-opening valve with the outer circumferential side as the fixed end and the inner circumferential side as the free end, allowing for bending on the inner circumferential side, the valve seat member may be annular, with a fixed-end seat portion on the outer circumferential side of the valve seat member and a free-end seat portion on the inner circumferential side, and further with a first recess, a second recess, and a port provided in this order from the outer circumferential side of the valve seat member between the fixed-end seat portion and the free-end seat portion. Even in a valve employing an inward-opening leaf valve, the first recess and the second recess are provided on the valve seat member closer to the fixed-end seat portion than the port, thereby preventing contaminants from getting caught in the leaf valve and suppressing variations in damping force. Furthermore, while the valve V is used as a damping valve that exerts a damping force by providing resistance to the flow of liquid passing through a port when the valve is open, it may also be used as a check valve that provides almost no resistance to the flow of liquid passing through a port when the valve is open. In this way, even when the valve V is used as a check valve, it is possible to prevent contaminants from getting caught in the leaf valve and to suppress variations in the characteristics of the check valve.

[0064] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made thereto without departing from the scope of the appended claims.

[0065] 1... Leaf valve, 1b... Fixed end, 1c... Free end, 2... Piston (valve seat member), 2c... Fixed end side seat portion, 2d... Compression side port (port), 2e... Free end side seat portion, 2f... Recess, 2f1... First recess, 2f2... Second recess, 10... Cylinder (outer tube), 11... Rod, A... Shock absorber body, D... Shock absorber, V... Valve, R1... Extension side chamber (operating chamber), R2... Compression side chamber (operating chamber)

Claims

1. A valve comprising: an annular leaf valve having one of an inner circumference and an outer circumference as a fixed end and the other of the inner circumference and the outer circumference as a free end; a valve seat member having: an annular fixed end seat portion which abuts the fixed end of the leaf valve; a plurality of ports provided at intervals in the circumferential direction on the free end side of the leaf valve on the fixed end seat portion; a free end seat portion which surrounds the ports together with the fixed end seat portion and on which the free end side of the leaf valve is seated and separated; and a recess provided between the ports and the fixed end seat portion, wherein the recess has a first recess which is provided annularly on the fixed end seat portion side, and a second recess which is provided annularly on the port side adjacent to the first recess and is deeper than the first recess.

2. A valve according to claim 1, wherein the depth of said first recess is constant.

3. A valve as claimed in claim 1, wherein said valve seat member has a land which protrudes from the bottom of said first recess and abuts against the valve seat member side of said leaf valve to support said leaf valve.

4. A valve as set forth in claim 3, wherein said land is provided at a position radially opposite said port.

5. The valve according to claim 1, wherein the hardness of said valve seat member is lower than the hardness of said leaf valve.

6. A valve as claimed in claim 1, wherein the recess is provided across the entire width between the port and the fixed end side seat portion of the valve seat member.

7. A valve as claimed in claim 1, wherein the depth of said first recess from said fixed end side seat portion is set in the range of 0.1 mm to 0.5 mm.

8. A shock absorber comprising: an outer tube; a shock absorber body having an outer tube, a rod inserted into the outer tube so as to be axially movable, and at least two working chambers through which liquid flows as a result of movement of the rod relative to the outer tube; and a valve according to any one of claims 1 to 7 provided between the working chambers.

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