Damping valve and shock absorber

Abstract

A damping valve (V) according to the present invention comprises: a valve seat member (1) that is circular and has a plurality of ports (1b, 1c) and seat sections (1d, 1e); and layered leaf valves (2, 3) that are annular, are layered on the valve seat member (1), and are allowed to bend at the outer circumferential sides thereof to separate from and seat against the seat sections (1d, 1e) and open and close the ports (1b, 1c). The layered leaf valves (2, 3) have annular first leaf valves (2a, 3a), and annular second leaf valves (2b, 3b) that are overlaid on back surfaces of the first leaf valves (2a, 3a), which are the surfaces on the opposite side from the valve seat. The second leaf valves (2b, 3b) are provided with holes (2b1, 2b2, 3b1) that face the first leaf valves (2a, 3a) in the axial direction, and cutout passages (2b3, 2b4, 3b2) that open from the outer circumferences and extend to the holes (2b1, 2b2, 3b1).

Description

Damping valves and shock absorbers

[0001] The present invention relates to a damping 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 it expands or contracts.

[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 damping valve provided in the damping passage.

[0004] The damping valve may, for example, include a piston that is slidably inserted into the cylinder of the shock absorber to divide the inside of the cylinder into an extension-side chamber and a compression-side chamber, and that has a port that connects the extension-side chamber with the compression-side chamber and a seat portion that surrounds the outer periphery of the port; and a laminated leaf valve that is annular, has its inner periphery as a fixed end, is fixed to the piston rod, and has its outer periphery as a free end, is allowed to flex, and is laminated on the piston.

[0005] In such damping valves, in order to smooth the opening action of the stacked leaf valves when they bend and move away from their seats, attempts have been made to gradually open the stacked leaf valves from one or more circumferential positions. For example, as disclosed in JP 2006-194336 A, such damping valves include a stacked leaf valve made up of multiple leaf valves, in which a ring with a two-sided outer periphery is stacked on the back side of the first leaf valve that abuts on the seat, making it easier to open the portion of the leaf valve not supported by the ring. In addition, there are also damping valves in which a D-shaped spacer is stacked on the stacked leaf valve to restrain the inner periphery of the stacked leaf valve, thereby varying the apparent rigidity of the entire stacked leaf valve in the circumferential direction and causing the stacked leaf valve to open first from the portion with weaker rigidity.

[0006] JP2006-194336A

[0007] Conventional damping valves are excellent in that they can smooth the opening action by opening the leaf valve from a single part, thereby suppressing pressure fluctuations that occur when the entire circumference of the leaf valve suddenly moves away from the seat, and can mitigate the generation of abnormal noise and sudden changes in damping force.However, they require the leaf valve to be stacked with a spacer or leaf valve that has a different outer peripheral shape from the leaf valve, which makes assembly difficult and limits the freedom of the damping force characteristics of the damping valve.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a damping valve and a shock absorber that are easy to assemble and that can improve the degree of freedom in damping force characteristics.

[0009] In order to solve the above-mentioned problems, the damping valve of the present invention comprises: a circular valve seat member having a plurality of ports arranged circumferentially and a seat portion surrounding the outer periphery of the ports; and an annular laminated leaf valve stacked on the valve seat member, with the inner periphery side serving as a fixed end and the outer periphery side serving as a free end that is allowed to flex and can be seated on and removed from the seat portion to open and close the port, wherein the laminated leaf valve has an annular first leaf valve and an annular second leaf valve stacked on the anti-seat side that forms the back surface of the first leaf valve, and the second leaf valve has a hole that faces the first leaf valve in the axial direction and a cutout passage that opens from the outer periphery and leads to the hole.

[0010] With a damping valve configured in this manner, the first leaf valve and the second leaf valve that make up the stacked leaf valve are both annular in shape, making assembly easy, and by adjusting the position, opening area, and circumferential width of the hole provided in the second leaf valve, the position, ease of bending, and circumferential length of the flexible portion in the stacked leaf valve can be adjusted as desired.

[0011] Fig. 1 is a longitudinal sectional view of a shock absorber to which a damping valve according to an embodiment of the present invention is applied. Fig. 2 is an enlarged sectional view of the damping valve according to an embodiment of the present invention. Fig. 3 is a plan view of an extension-side second leaf valve in the damping valve according to an embodiment of the present invention. Fig. 4 is a plan view of a modified extension-side second leaf valve in the damping valve according to an embodiment of the present invention. Fig. 5 is a plan view of a compression-side second leaf valve in the damping valve according to an embodiment of the present invention. Fig. 6 is a plan view of a damping valve according to a first modified example of an embodiment of the present invention. Fig. 7 is a plan view of a damping valve according to a second modified example of an embodiment of the present invention.

[0012] The present invention will be described below based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2 , a damping valve V in one embodiment is applied to a piston portion of a shock absorber D, and includes a piston 1 serving as a valve seat member having ports 1b and 1c and seat portions 1d and 1e surrounding the ports 1b and 1c, and stacked leaf valves 2 and 3 for opening and closing the ports 1b and 1c. As shown in FIG. 1 , the shock absorber D to which the damping valve V is applied includes a shock absorber main body A that is extendable and has a cylinder 10 serving as an outer tube and a rod 11 movably inserted into the cylinder 10, and a damping valve V provided between an expansion-side chamber R1 and a compression-side chamber R2 serving as two working chambers provided in the shock absorber main body A. This shock absorber D is installed between the body and axle of a vehicle (not shown) to suppress vibrations of the vehicle body and wheels.

[0013] Hereinafter, a detailed description will be given of each part of the damping 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 1 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 extension-side chamber R1 and a compression-side chamber R2 as working chambers.

[0014] 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).

[0015] 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 1 moves up and down (axially) within cylinder 10.

[0016] 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 along its inner periphery, 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 1 from the rod 11.

[0017] 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 1 into an extension-side chamber R1 on the rod 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.

[0018] 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.

[0019] 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) 11 expands or contracts the air chamber G to compensate 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 to make the shock absorber a twin-cylinder shock absorber, the reservoir may be used to compensate 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 14 is attached to the center of the rod 11 and the ends of the rod 11 protrude from both ends of the cylinder 10.

[0020] 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.

[0021] The damping 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 1 serving as a valve seat member constituting the damping valve V is annular and fitted onto the outer periphery of a small diameter portion 11a of the rod 11, and is fixed to the rod 11 by a piston nut 15 that is screwed onto a threaded portion 11d of the rod 11. The piston 1 is also assembled to the rod 11, and its outer periphery is in sliding contact with the inner periphery of a 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.

[0022] More specifically, the piston 1 includes a circular main body portion 1a, a plurality of extension-side ports 1b provided in the main body portion 1a, each opening from the lower end of the main body portion 1a in FIG. 2 and leading to the upper end in FIG. 2, a plurality of compression-side ports 1c opening from the upper end of the main body portion 1a in FIG. 2 and leading to the lower end in FIG. 2, a seat portion 1d protruding downward from the lower end of the main body portion 1a in FIG. 2 and surrounding the outer periphery of port 1b, and a seat portion 1e protruding upward from the upper end of the main body portion 1a in FIG. 2 and surrounding the outer periphery of port 1c.

[0023] As described above, the main body 1a is annular, and its outer periphery is in sliding contact with the inner periphery of the cylinder 10. In addition to the seat portions 1d and 1e, the main body 1a is provided with an annular inner periphery seat portion 1f at its lower end, which protrudes downward from the inner periphery of the lower opening end of port 1b, and an annular inner periphery seat portion 1g at its upper end, which protrudes upward from the inner periphery of the upper opening end of port 1c, as shown in Figure 2.

[0024] The port 1b opens from the outer circumferential side of the inner circumferential seat portion 1f at the upper end of the main body portion 1a in Fig. 2, extends in the axial direction, and communicates with the lower end of the main body portion 1a in Fig. 2, connecting the expansion-side chamber R1 and the compression-side chamber R2. Note that a plurality of ports 1b are provided in the main body portion 1a at equal intervals in the circumferential direction of the main body portion 1a. Furthermore, the port 1b is an expansion-side port that allows liquid to flow from the expansion-side chamber R1 to the compression-side chamber R2 when the shock absorber D is extended.

[0025] The port 1c opens from the outer periphery of the inner seat portion 1g at the lower end of the main body portion 1a in Figure 2, extends in the axial direction, and communicates with the upper end of the main body portion 1a in Figure 2, connecting the expansion-side chamber R1 and the compression-side chamber R2. The ports 1c are provided in the main body portion 1a at equal intervals in the circumferential direction of the main body portion 1a, and the same number as the ports 1b. The ports 1c are compression-side ports that allow liquid to flow from the compression-side chamber R2 to the expansion-side chamber R1 when the shock absorber D is contracting. The number of expansion-side ports 1b and compression-side ports 1c provided relative to the piston 1 can be arbitrarily changed in design.

[0026] In this embodiment, the seat portion 1d is provided at the lower end of the main body portion 1a in Figure 2, has a petal shape when viewed in the axial direction, protrudes downward from the lower end of the main body portion 1a, is connected to the inner seat portion 1f, and independently surrounds the ports 1b, functioning as an expansion-side valve seat. On the other hand, the seat portion 1e is provided at the upper end of the main body portion 1a in Figure 2, has a petal shape when viewed in the axial direction, protrudes upward from the upper end of the main body portion 1a, and is connected to the inner seat portion 1g, independently surrounds the ports 1c, functioning as a compression-side valve seat. Note that the seat portions 1d and 1e only need to surround the ports 1b and 1c and function as valve seats, and may be annular or other shapes other than petal shapes depending on the arrangement of the ports 1b and 1c relative to the main body portion 1a.

[0027] The stacked leaf valve 2 is formed by stacking annular leaf valves 2a, 2b, and 2c, and is stacked at the bottom in Figure 2, which is the compression chamber side of the piston 1 serving as a valve seat member, and is fixed to the outer periphery of the small diameter portion 11a of the rod 11 together with the piston 1, with the inner periphery being the fixed end and the outer periphery being the free end, allowing deflection on the outer periphery side.

[0028] 2 of the piston 1 and abutting the inner peripheral seat portion 1f and the seat portion 1d, an annular first leaf valve 2a overlapping the back surface of the first leaf valve 2a on the anti-valve seat side, and a third leaf valve 2c overlapping the back surface of the second leaf valve 2b on the anti-valve seat side. In this embodiment, the stacked leaf valve 2 includes a plurality of annular leaf valves, each having an outer diameter smaller than that of the third leaf valve 2c, stacked on the back surfaces of the three leaf valves, the first leaf valve 2a, the second leaf valve 2b, and the third leaf valve 2c, so as to gradually decrease in size. However, leaf valves other than at least the first leaf valve 2a and the second leaf valve 2b may be eliminated, or the number of leaf valves stacked may be changed. Furthermore, when an orifice is provided in the damping valve V, a leaf valve with an orifice having a notched orifice opening from the outer periphery may be provided on the piston side of the first leaf valve 2a in the stacked leaf valve 2, or an orifice may be provided by stamping on the seat portion 1d of the piston 1 as a valve seat member.

[0029] 2, a spacer 4 having an outer diameter smaller than that of the laminated leaf valve 2 is stacked below the laminated leaf valve 2, and when the laminated leaf valve 2 is fixed to the small-diameter portion 11a of the rod 11 together with the spacer 4, the laminated leaf valve 2 can bend with the outer circumferential edge of the spacer 4 as a fulcrum. When the laminated leaf valves 2 are stacked at the lower end of the piston 1 in FIG. 2, the uppermost first leaf valve 2a in FIG. 2 abuts against the inner circumferential seat portion 1f and the seat portion 1d, thereby closing the lower opening end in FIG. 2, which is the outlet end of the port 1b. When the laminated leaf valve 2 receives pressure from the expansion-side chamber R1 acting through the port 1b, the outer circumferential side of the laminated leaf valve 2 is bent and separated from the seat portion 1d, thereby opening the port 1b, allowing the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2 through the gap between the expansion-side chamber R1 and the seat portion 1d and providing resistance to the flow. In this way, the laminated leaf valve 2 functions as an expansion-side damping valve that opens and closes the expansion-side port 1b to provide resistance to the flow of fluid from the expansion-side chamber R1 to the compression-side chamber R2.

[0030] In this embodiment, the first leaf valve 2a, the second leaf valve 2b, and the third leaf valve 2c all have the same inner and outer diameters. The second leaf valve 2b, which is sandwiched between the first leaf valve 2a and the third leaf valve 2c, is annular, as shown in FIG. 3 , and has two arc-shaped holes 2b1 and 2b2 spaced apart in the circumferential direction near the centers of the inner and outer peripheries. The second leaf valve 2b also has a notched passage 2b3 that opens from the outer periphery and communicates with hole 2b1, and a notched passage 2b4 that opens from the outer periphery and communicates with hole 2b2. Therefore, the rigidity of the second leaf valve 2b in the circumferential direction where holes 2b1 and 2b2 are provided is low, making it more flexible. Furthermore, the second leaf valve 2b is provided with a pair of arms 2b5 and 2b6 facing each other across a notched passage 2b3 on the outer circumferential side of the hole 2b1, and a pair of arms 2b7 and 2b8 facing each other across a notched passage 2b4 on the outer circumferential side of the hole 2b2. In this way, the second leaf valve 2b is provided with the holes 2b1 and 2b2 and the notched passages 2b3 and 2b4 communicating with each of the holes 2b1 and 2b2, thereby forming pairs of arms 2b5, 2b6, 2b7, and 2b8 on the outer circumferential sides of the holes 2b1 and 2b2, respectively.

[0031] The radial width of hole 2b1 is wider than the radial width of hole 2b2, and the circumferential length of hole 2b1 is longer than the circumferential length of hole 2b2. The rigidity of the second leaf valve 2b is lower in the portion where holes 2b1 and 2b2 are provided than in the portion where holes 2b1 and 2b2 are not provided, and the portion where hole 2b1 is provided is the lowest in the circumferential direction, followed by the portion where hole 2b2 is provided.

[0032] Furthermore, the radial widths of the outer peripheral portion of the hole 2b1 in the second leaf valve 2b are different on both sides of the cutout passage 2b3, and of the arms 2b5, 2b6 on the outer peripheral side of the hole 2b1 as viewed from the center of the second leaf valve 2b in Fig. 3, the radial width of the arm 2b5 on the left side of the cutout passage 2b3 is shorter than the radial width of the arm 2b6 on the right side of the cutout passage 2b3. Therefore, the rigidity of the second leaf valve 2b is lower on the left side of the cutout passage 2b3 as viewed from the center of the second leaf valve 2b than on the right side of the hole 2b1. In this way, by making the radial width of the hole 2b1 different on both sides of the cutout passage 2b3 and forming the arms 2b5, 2b6 with different radial lengths on the outer peripheral side of the hole 2b1, the rigidity of the location of the hole 2b1 of the second leaf valve 2b can be set to vary in the circumferential direction.

[0033] Furthermore, in the second leaf valve 2 shown in Fig. 3, the notched passages 2b3, 2b4 that communicate with the holes 2b1, 2b2 communicate with the centers of the holes 2b1, 2b2 in the circumferential direction of the second leaf valve 2b, but the notched passages 2b3, 2b4 may also communicate with positions offset from the centers of the holes 2b1, 2b2 toward the circumferential ends, as shown in Fig. 4. In this way, by communicating the notched passage 2b3 with a position offset from the circumferential center of the hole 2b1 toward the circumferential end, the circumferential lengths of the arms 2b5, 2b6 can be made different, and the rigidity of the installation position of the hole 2b1 of the second leaf valve 2b can be set to vary in the circumferential direction. 4, the cutout passage 2b4 may be connected to the circumferential end of the hole 2b2, in which case, by connecting the cutout passage 2b4 to the hole 2b2, only one arm 2b7 is formed on the outer circumferential side of the hole 2b2 in the second leaf valve 2b. Even in this case, the rigidity of the second leaf valve 2b in the circumferential direction at a portion where no arm exists on the outer circumferential side of the hole 2b2 can be reduced, so that the rigidity of the second leaf valve 2b at the location of the hole 2b2 can be set to vary in the circumferential direction.

[0034] When the second leaf valve 2b is placed on top of the first leaf valve 2a, the holes 2b1 and 2b2 of the second leaf valve 2b face the first leaf valve 2a in the axial direction. Furthermore, when the third leaf valve 2c is placed on top of the second leaf valve 2b, the holes 2b1 and 2b2 face the third leaf valve 2c in the axial direction. Therefore, in the stacked leaf valve 2 of this embodiment, the two holes 2b1 and 2b2 of the second leaf valve 2b are covered by the first leaf valve 2a and the third leaf valve 2c, and are connected to the compression-side chamber R2 outside the stacked leaf valve 2 only by the notched passages 2b3 and 2b4, respectively.

[0035] The stacked leaf valve 3 is formed by stacking annular leaf valves 3a, 3b, and 3c, and is stacked at the upper part in Figure 2, which is on the extension-side chamber side of the piston 1 serving as a valve seat member, and is fixed to the outer periphery of the small diameter portion 11a of the rod 11 together with the piston 1, with the inner periphery being the fixed end and the outer periphery being the free end, allowing deflection on the outer periphery side.

[0036] 2 of the piston 1 and abutting against the inner peripheral seat portion 1g and the seat portion 1e, an annular second leaf valve 3b overlapping the anti-valve seat side surface that forms the back surface of the first leaf valve 3a, and a third leaf valve 3c overlapping the anti-valve seat side surface that forms the back surface of the second leaf valve 3b. In this embodiment, the stacked leaf valve 3 includes a plurality of annular leaf valves, each having an outer diameter smaller than that of the third leaf valve 3c, stacked on the back surfaces of the three leaf valves, the first leaf valve 3a, the second leaf valve 3b, and the third leaf valve 3c, so that the outer diameters of the leaf valves become gradually smaller. However, leaf valves other than at least the first leaf valve 3a and the second leaf valve 3b may be eliminated, or the number of leaf valves stacked may be changed. Furthermore, when an orifice is provided in the damping valve V, a leaf valve with an orifice having a notched orifice opening from the outer periphery may be provided on the piston side of the first leaf valve 3a in the stacked leaf valve 3, or an orifice may be provided by stamping on the seat portion 1e of the piston 1 as a valve seat member.

[0037] 2, a spacer 5 having an outer diameter smaller than that of the laminated leaf valve 3 is stacked above the laminated leaf valve 3, and when the laminated leaf valve 3 is fixed to the small-diameter portion 11a of the rod 11 together with the spacer 5, the laminated leaf valve 3 can bend with the outer circumferential edge of the spacer 5 as a fulcrum. When the laminated leaf valves 3 are stacked at the upper end of the piston 1 in FIG. 2, the lowermost first leaf valve 3a in FIG. 2 abuts against the inner circumferential seat portion 1g and the seat portion 1e, thereby closing the upper opening end in FIG. 2, which is the outlet end of the port 1c. When the laminated leaf valve 3 receives pressure from the compression-side chamber R2 acting through the port 1c, the outer circumferential side of the laminated leaf valve 3 is bent and separated from the seat portion 1e, thereby opening the port 1c, allowing the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1 through the gap between the valve and the seat portion 1e and providing resistance to the flow. In this way, the laminated leaf valve 3 functions as a compression-side damping valve that opens and closes the compression-side port 1c to provide resistance to the flow of fluid from the compression-side chamber R2 to the expansion-side chamber R1.

[0038] In this embodiment, the first leaf valve 3 a and the second leaf valve 3 b have the same inner diameter and outer diameter, and the third leaf valve 3 c is annular and has the same inner diameter as the first leaf valve 3 a and the second leaf valve 3 b, but its outer diameter is smaller than the outer diameters of the first leaf valve 3 a and the second leaf valve 3 b.

[0039] The second leaf valve 3b, which is sandwiched between the first leaf valve 3a and the third leaf valve 3c, is annular, as shown in Fig. 5, and has arc-shaped holes 3b1 formed along the circumferential direction near the centers of the inner and outer peripheries in the radial direction. The second leaf valve 3b also has notched passages 3b2 that open from the outer periphery and communicate with the holes 3b1. Therefore, the rigidity of the second leaf valve 3b in the circumferential direction where the holes 3b1 are formed is low, making it more flexible. The second leaf valve 3b may also have different radial widths on both sides of the notched passages 3b1 on the outer periphery of the hole 3b1, thereby varying the rigidity of the location where the holes 3b1 are formed in the second leaf valve 3b in the circumferential direction. Furthermore, the notched passages 3b2 that are in communication with the holes 3b1 may be in communication with a location other than the center of the hole 3b1 in the circumferential direction of the second leaf valve 3b.

[0040] When the second leaf valve 3b is placed over the first leaf valve 3a, the hole 3b1 of the second leaf valve 3b faces the first leaf valve 3a in the axial direction. Furthermore, the outer diameter of the third leaf valve 3c is larger than the diameter of a circle that is centered at the center of the second leaf valve 3b and is tangent to the outer periphery of the hole 3b1, but is smaller than the outer diameter of the second leaf valve 3b. Therefore, when the third leaf valve 3c is placed over the second leaf valve 3b, the third leaf valve 3c partially overlaps the hole 3b1 in the axial direction and closes the hole 3b1, but does not impede communication of the hole 3b1 with the expansion-side chamber R1 via the notched passage 3b2.

[0041] The compression-side laminated leaf valve 3, piston 1, and extension-side laminated leaf valve 2 configured as described above are assembled in this order to the outer periphery of the small-diameter portion 11a of the rod 11, and then sandwiched and fixed to the rod 11 by a piston nut 15 that is screwed onto a threaded portion 11d of the small-diameter portion 11a and a step portion 11c of the rod 11. An annular valve stopper 6 is stacked above the compression-side laminated leaf valve 3 and attached to the small-diameter portion 11a, so that when the laminated leaf valve 3 bends and abuts against the valve stopper 6, further bending of the laminated leaf valve 3 is restricted, thereby protecting the laminated leaf valve 3. When the extension-side laminated leaf valve 2 bends and abuts against the piston nut 15, further bending of the laminated leaf valve 2 is restricted, thereby protecting the laminated leaf valve 2.

[0042] The damping 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 1 moves upward in FIG. 1 relative to the cylinder 10, the upward movement of the piston 1 in FIG. 1 causes the liquid in the expansion-side chamber R1, which is compressed, to bend the laminated leaf valve 2 and move through the expansion-side port 1b to the compression-side chamber R2. Therefore, when the shock absorber D performs an extension operation, the laminated leaf valve 2 provides resistance to the flow of liquid from the expansion-side chamber R1 to the compression-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] As shown in Figure 3, the second leaf valve 2b in the stacked leaf valve 2 has two holes 2b1, 2b2 located near the center of the inner and outer peripheries in the radial direction, offset in the circumferential direction. Hole 2b1 has a larger opening area than hole 2b2, so that the rigidity of the second leaf valve 2b is lowest at the location where hole 2b1 is provided, and the rigidity of the location where hole 2b2 is provided is lower than the rigidity of a portion without any holes. In other words, there are two locations in the circumferential direction where the rigidity of the second leaf valve 2b is reduced, resulting in a change in rigidity in the circumferential direction. The first leaf valve 2a is most flexible at the location axially facing hole 2b1, which has the lowest rigidity, of the second leaf valve 2b stacked on its back surface, followed by the location axially facing hole 2b2, which has the lowest rigidity, and is less flexible in other portions.

[0044] Therefore, when the laminated leaf valve 2 receives the pressure of the expansion-side chamber R1 through the port 1b and opens, the outer periphery of the hole 2b1 of the laminated leaf valve 2 first bends in the radial direction and moves away from the seat portion 1d, then the outer periphery of the hole 2b2 bends in the radial direction and moves away from the seat portion 1d, and finally the outer periphery of the portion other than the holes 2b1 and 2b2 bends in the radial direction and moves away from the seat portion 1d. In this way, the entire periphery of the laminated leaf valve 2 does not move away from the seat portion 1d all at once, but opens gradually in the above-mentioned order, which reduces pressure fluctuations when the laminated leaf valve 2 opens, thereby reducing the generation of abnormal noise and sudden changes in damping force.

[0045] In this way, by providing the holes 2b1, 2b2 in the second leaf valve 2b, the outer periphery of the stacked leaf valve 2 at the locations where the holes 2b1, 2b2 are provided can be made more flexible, so that the circumferential locations of the holes 2b1, 2b2 on the second leaf valve 2b can be used to determine which circumferential location of the stacked leaf valve 2 is to be opened. Furthermore, because the second leaf valve 2b is provided with two holes 2b1, 2b2, the flexibility of the outer peripheries of the holes 2b1, 2b2 in the stacked leaf valve 2 can be adjusted depending on the opening areas of the holes 2b1, 2b2, so that the outer periphery of the hole 2b1, which has a larger opening area, can be opened earlier in time, and the outer periphery of the hole 2b2, which has a smaller opening area, can be opened later than the opening of the outer periphery of the hole 2b1. Furthermore, by setting the circumferential width of the holes 2b1, 2b2, it is possible to set the circumferential length of the portion of the laminated leaf valve 2 that is most likely to bend, thereby tuning the circumferential width of the portion of the laminated leaf valve 2 that first opens. In addition, the ease of opening of the laminated leaf valve 2 can be tuned by the radial width of the holes 2b1, 2b2. The number of holes provided in the second leaf valve 2b may be one or three or more, and the design can be modified as appropriate depending on the type of valve opening operation desired for the laminated leaf valve 2.

[0046] Furthermore, because the holes 2b1 and 2b2 are connected to the compression-side chamber R2 through the cutout passages 2b3 and 2b4, when the cylinder 10 is filled with liquid after the damping valve V is assembled and inserted into the cylinder 10, the holes 2b1 and 2b2 are also easily filled with liquid, so that gas is not left behind in the holes 2b1 and 2b2 and the stacked leaf valve 2 does not repeatedly deflect, causing the leftover gas to escape from the holes 2b1 and 2b2 and enter the expansion-side chamber R1 and the compression-side chamber R2, thereby disrupting the damping force generated by the shock absorber D. Furthermore, the holes 2b1 and 2b2 are not sealed but are connected to the compression-side chamber R2 through the cutout passages 2b3 and 2b4, so that liquid can freely flow in and out of the holes 2b1 and 2b2 when the stacked leaf valve 2 deflects, preventing excessive pressure buildup and pressure reduction in the holes 2b1 and 2b2, allowing the stacked leaf valve 2 to perform a smooth valve opening operation.

[0047] Next, when the shock absorber D contracts and the piston 1 moves downward in FIG. 1 relative to the cylinder 10, the downward movement of the piston 1 causes the liquid in the compression-side chamber R2 to bend the compression-side stacked leaf valve 3 and move through the compression-side port 1c to the extension-side chamber R1.

[0048]

[0033] More specifically, when the shock absorber D contracts, the pressure in the compression-side chamber R2 acts on the underside of the laminated leaf valve 3 in Figure 2 through the compression-side port 1c, and the action of this pressure bends the free end of the laminated leaf valve 3 and separates from the seat portion 1e, causing the liquid in the compression-side chamber R2 to move to the expansion-side chamber R1 through the gap formed between the laminated leaf valve 3 and the seat portion 1e. Therefore, when the shock absorber D contracts, the laminated leaf valve 3 provides 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. 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.

[0049] As shown in Fig. 5, the second leaf valve 3b in the stacked leaf valve 3 has holes 3b1 near the center of the inner and outer peripheries in the radial direction. The rigidity of the second leaf valve 3b at the location where the hole 3b1 is provided is lower than the rigidity of a portion without the hole. The first leaf valve 3a is more likely to bend at the location in the axial direction facing the hole 3b1 of the second leaf valve 3b stacked on its back surface, which has lower rigidity, but is less likely to bend in other portions.

[0050] Therefore, when the laminated leaf valve 3 receives pressure from the compression-side chamber R2 via the port 1c and opens, the outer periphery of the hole 3b1 of the laminated leaf valve 3 first bends in the radial direction and moves away from the seat portion 1e, and then the outer periphery of the portion other than the hole 3b1 bends in the radial direction and moves away from the seat portion 1e. In this way, the entire periphery of the laminated leaf valve 3 does not move away from the seat portion 1e all at once, but opens gradually in the above-mentioned order, which reduces pressure fluctuations when the laminated leaf valve 3 opens, thereby reducing the generation of abnormal noise and sudden changes in damping force.

[0051] By providing the hole 3b1 in the second leaf valve 3b in this way, the outer periphery of the laminated leaf valve 3 at the location of the hole 3b1 can be made more flexible. Therefore, the circumferential location of the hole 3b1 on the second leaf valve 3b can be controlled to determine which circumferential location of the laminated leaf valve 3 is to be opened. Furthermore, the flexibility of the outer periphery of the hole 3b1 in the laminated leaf valve 3 can be adjusted by adjusting the opening area of ​​the hole 3b1 in the second leaf valve 3b. Furthermore, the circumferential length of the more flexible portion of the laminated leaf valve 3 can be controlled by adjusting the circumferential width of the hole 3b1, allowing tuning of the circumferential width of the portion of the laminated leaf valve 3 that first opens. Furthermore, the radial width of the hole 3b1 can be adjusted to tune the ease of opening the laminated leaf valve 3. The second leaf valve 3b may have one or more holes, and the design can be modified appropriately depending on the desired valve opening operation of the laminated leaf valve 3.

[0052] Furthermore, in the stacked leaf valve 3, the outer diameter of the third leaf valve 3c is smaller than the outer diameters of the first leaf valve 3a and the second leaf valve 3b, and therefore, compared to the stacked leaf valve 2, which has the same outer diameter, the outer peripheries of the first leaf valve 3a and the second leaf valve 3b are not supported by the third leaf valve 3c, making them more likely to deflect. Therefore, the stacked leaf valve 3 can generate a lower damping force than the stacked leaf valve 2, and the difference in rigidity in the circumferential direction of the stacked leaf valve 3 is greater, which increases the difference in the amount of deflection of the stacked leaf valve 3 in the circumferential direction at the initial stage of valve opening, allowing for a slightly larger change in damping force at the initial stage of valve opening.

[0053] Furthermore, because the hole 3b1 is communicated with the expansion-side chamber R1 through the cutout passage 3b2, when the cylinder 10 is filled with liquid after the damping valve V is assembled and inserted into the cylinder 10, the hole 3b1 is also easily filled with liquid. This prevents gas from being left behind in the hole 3b1 and from repeatedly deflecting the laminated leaf valve 3, causing the leftover gas to escape from the hole 3b1 and enter the expansion-side chamber R1 and the compression-side chamber R2, thereby disrupting the damping force generated by the shock absorber D. Furthermore, because the hole 3b1 is not sealed but is communicated with the expansion-side chamber R1 through the cutout passage 3b2, liquid can freely flow in and out of the hole 3b1 when the laminated leaf valve 3 deflects. This prevents excessive pressure buildup and pressure reduction within the hole 3b1, allowing the laminated leaf valve 3 to perform a smooth valve opening operation.

[0054] As described above, the damping valve V of this embodiment is made up of a piston (valve seat member) 1 that is circular and has a plurality of ports 1b, 1c arranged in a circumferential direction and seat portions 1d, 1e that surround the outer peripheries of the ports 1b, 1c, and a laminated leaf valve 2 that is annular and laminated on the piston (valve seat member) 1, with the inner periphery side being a fixed end and the outer periphery side being a free end that is allowed to bend and seat on and off the seat portions 1d, 1e, and that opens and closes the ports 1b, 1c. , 3, and the stacked leaf valves 2, 3 have annular first leaf valves 2a, 3a and annular second leaf valves 2b, 3b superimposed on the anti-valve seat side which forms the back surface of the first leaf valves 2a, 3a, and the second leaf valves 2b, 3b have holes 2b1, 2b2, 3b1 axially opposed to the first leaf valves 2a, 3a and cutout passages 2b3, 2b4, 3b2 which open from the outer periphery and communicate with the holes 2b1, 2b2, 3b1.

[0055] In the damping valve V configured in this manner, by providing holes 2b1, 2b2, 3b1 in the second leaf valves 2b, 3b, it is possible to set flexible portions in the circumferential direction of the stacked leaf valves 2, 3, and the stacked leaf valves 2, 3 do not suddenly move away from the seats 1d, 1e over their entire peripheries but open from the flexible portions, thereby mitigating pressure fluctuations when the stacked leaf valves 2, 3 are opened, thereby mitigating the generation of abnormal noise and sudden changes in damping force. Furthermore, with the damping valve V configured in this manner, the first leaf valves 2a, 3a and the second leaf valves 2b, 3b constituting the stacked leaf valves 2, 3 are both annular in shape, making it easy to grip the outer peripheries with a chuck, and as such, it is easier to assemble than conventional damping valves that include leaf valves with an outer diameter other than annular, such as a D-shape, which makes it difficult to grip with a chuck. Furthermore, by adjusting the position, opening area and circumferential width of the holes 2b1, 2b2 and 3b1 provided in the second leaf valves 2b and 3b, the position, ease of bending and circumferential length of the flexible portions in the laminated leaf valves 2 and 3 can be adjusted as desired, thereby improving the degree of freedom in the damping force characteristics.

[0056] Furthermore, the second leaf valve 2b in the damping valve V of this embodiment is provided with a pair of arms 2b5, 2b6 that face each other across the cutout passage 2b3 on the outer circumferential side of the hole 2b1, and the arms 2b5, 2b6 have different radial lengths. According to the damping valve V configured in this manner, the rigidity of the location where the hole 2b1 of the second leaf valve 2b is provided can be set to vary in the circumferential direction, so that the ease of bending can be varied in the circumferential direction in the easily bending portion of the laminated leaf valve 2, thereby further improving the degree of freedom in the damping force characteristics. Furthermore, in a modified second leaf valve 2b of the damping valve V of this embodiment shown in Figure 4, the cutout passages 2b3, 2b4 are connected to the holes 2b1, 2b2 at positions that are offset from the circumferential center toward the circumferential ends. Even in this way, the rigidity of the installation locations of the holes 2b1, 2b2 of the second leaf valve 2b can be set to differ in the circumferential direction, so that the flexibility in the flexible parts of the stacked leaf valve 2 can be varied in the circumferential direction, further improving the flexibility of the damping force characteristics.

[0057] Furthermore, according to the damping valve V, the holes 2b1, 2b2, and 3b1 provided in the second leaf valves 2b and 3b are not sealed by the cutout passages 2b3, 2b4, and 3b2 opening from the outer periphery of the second leaf valves 2b and 3b and communicate with the outside of the stacked leaf valves 2 and 3, so that no gas is left behind in the holes 2b1, 2b2, and 3b1, and no disturbances are caused in the generated damping force. Furthermore, according to the damping valve V, liquid can freely flow in and out of the holes 2b1, 2b2, and 3b1 when the ports 1b and 1c of the stacked leaf valves 2 and 3 are opened and closed, so that excessive pressure buildup and pressure reduction do not occur in the holes 2b1, 2b2, and 3b1, and the stacked leaf valves 2 and 3 can open smoothly. Note that, although the holes 2b1, 2b2, and 3b1 are shown as having an arc shape extending along the circumferential direction of the second leaf valves 2b and 3b, they may have shapes other than an arc shape.

[0058] Furthermore, the stacked leaf valves 2, 3 in the damping valve V of this embodiment are provided with third leaf valves 2c, 3c that are annular and have the same inner and outer diameters as the second leaf valves 2b, 3b and are stacked on the backside of the second leaf valves 2b, 3b. According to the damping valve V configured in this manner, the third leaf valves 2c, 3c having the same inner and outer diameters are stacked on the backside of the second leaf valves 2b, 3b. Therefore, the overall rigidity of the stacked leaf valves 2, 3 is higher than when they are configured with the first leaf valves 2a, 3a and the second leaf valves 2b, 3b, and the generated damping force can be increased. In addition, the difference in rigidity of the stacked leaf valves 2, 3 in the circumferential direction can be reduced. Therefore, the difference in the amount of deflection of the stacked leaf valves 2, 3 in the initial stage of valve opening is reduced in the circumferential direction, thereby alleviating stress during the valve opening operation and mitigating changes in the damping force in the initial stage of valve opening.

[0059] Furthermore, like the damping valve V1 of the first modified example of this embodiment shown in Fig. 6, the stacked leaf valve 2 may include a fourth leaf valve 2d that is annular and has an outer diameter smaller than that of the second leaf valve 2b, and is stacked on the back surface of the second leaf valve 2b facing part of the holes 2b1, 2b2, as shown in Fig. 6. Specifically, the outer diameter of the fourth leaf valve 2d, as shown by a dashed line in Fig. 6, is larger than the diameter of a circle C1 that has the smallest diameter among circles that touch the inner peripheries of the holes 2b1, 2b2, and is smaller than the diameter of a circle C2 that has the largest diameter among circles that touch the outer peripheries of the holes 2b1, 2b2, and is shown by a dashed line in Fig. 6. When the fourth leaf valve 2d is stacked on the second leaf valve 2b, the outer periphery of the fourth leaf valve 2d overlaps part of the holes 2b1, 2b2. With the damping valve V1 configured in this manner, compared to when a third leaf valve 2c having the same inner and outer diameters as the second leaf valve 2b is stacked on the back surface of the second leaf valve 2b, the overall rigidity of the stacked leaf valve 2 is lower and the outer peripheries of the first leaf valve 2a and the second leaf valve 2b that are not supported by the fourth leaf valve 2d are more likely to bend, so that the generated damping force can be lowered and the difference in rigidity of the stacked leaf valve 2 in the circumferential direction becomes larger, which increases the difference in the amount of bending of the stacked leaf valve 2 in the circumferential direction at the beginning of valve opening, and therefore the change in damping force at the beginning of valve opening can be increased.

[0060] 7, the stacked leaf valves 2 may include a fifth leaf valve 2e that is annular and has an outer diameter smaller than that of the second leaf valve 2b, and that is stacked on the back surface of the second leaf valve 2b without facing the holes 2b1, 2b2. Specifically, the outer diameter of the fifth leaf valve 2e, as shown by a dashed line in FIG. 7, is smaller than the diameter of a circle C1 that has the smallest diameter among circles that are tangent to the inner peripheries of the holes 2b1, 2b2, as shown by a dashed line in FIG. 7, and when the fifth leaf valve 2e is stacked on the second leaf valve 2b, the outer periphery thereof does not overlap the holes 2b1, 2b2. With the damping valve V2 configured in this manner, compared to the case where a third leaf valve 2c having the same inner and outer diameters as the second leaf valve 2b is stacked on the back surface of the second leaf valve 2b, the overall rigidity of the stacked leaf valve 2 is further reduced and the outer peripheries of the first leaf valve 2a and the second leaf valve 2b that are not supported by the fifth leaf valve 2e are more likely to bend, so the overall rigidity of the stacked leaf valve 2 is further reduced, the generated damping force can be further reduced, and the difference in rigidity of the stacked leaf valve 2 in the circumferential direction is further increased, so the difference in the amount of deflection of the stacked leaf valve 2 in the circumferential direction at the initial stage of valve opening is further increased, and the change in damping force at the initial stage of valve opening can be greater.

[0061] As can be understood from the above, the damping force characteristics can be tuned depending on the outer diameters of the third leaf valves 2c, 3c, fourth leaf valve 2d, and fifth leaf valve 2e stacked on the back side of the second leaf valve 2b, and the smaller the diameter of the leaf valves stacked on the back side of the second leaf valves 2b, 3b, the lower the rigidity of the stacked leaf valves 2, 3, and the lower the damping force. Therefore, the damping force characteristics of the damping valve V can be adjusted by setting the outer diameter of the leaf valves stacked on the back side of the second leaf valves 2b, 3b.

[0062] The shock absorber D of this embodiment includes a cylinder (outer tube) 10, a rod 11 inserted into the cylinder (outer tube) 10 so as to be axially movable, a shock absorber main body A having at least an extension-side chamber (working chamber) R1 and a compression-side chamber (working chamber) R2 through which fluid flows as the rod 11 moves relative to the cylinder (outer tube) 10, and a damping valve V provided between the extension-side chamber (working chamber) R1 and the compression-side chamber (working chamber) R2. The shock absorber D configured in this manner improves assembly ease and allows for an improved degree of freedom in damping force characteristics.

[0063] 1, the two working chambers are an extension-side chamber R1 and a compression-side chamber R2, and an extension-side laminated leaf valve 2 and a compression-side laminated leaf valve 3 are provided above and below the piston 1 serving as a valve seat member in FIG. 1, but a laminated leaf valve may be provided only on the extension-side chamber side or the compression-side chamber side of the piston 1. Also, in the case where the shock absorber D is a twin-tube shock absorber having an outer shell as an outer tube on the outer periphery of the cylinder and a reservoir between the cylinder and the outer shell, a valve seat member and a laminated leaf valve may be provided between the compression-side chamber and the reservoir, and a damping valve V may be provided between the compression-side chamber and the reservoir.

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

[0065] DESCRIPTION OF SYMBOLS 1: Piston (valve seat member), 1b, 1c: Port, 1d, 1e: Seat portion, 2, 3: Stacked leaf valve, 2a, 3a: First leaf valve, 2b, 3b: Second leaf valve, 2b1, 2b2, 3b1: Hole, 2b3, 2b4, 3b2: Notched passage, Arm: 2b5, 2b6, 2b7, 2b8, 2c: Third leaf valve, 2d: Fourth leaf valve, 2e: Fifth leaf valve, 10: Cylinder (outer tube), 11: Rod, A: Shock absorber body, D: Shock absorber, V, V1, V2: Damping valve, R1: Extension side chamber (operating chamber), R2: Compression side chamber (operating chamber)

Claims

1. A damping valve comprising: a valve seat member having a circular shape and a plurality of ports arranged in a circumferential direction and a seat portion surrounding the outer periphery of the ports; and annular laminated leaf valves stacked on the valve seat member, with an inner periphery side as a fixed end and an outer periphery side as a free end that is allowed to flex and seat on and off the seat portion for opening and closing the ports, wherein the laminated leaf valve has an annular first leaf valve and an annular second leaf valve stacked on the anti-seat side which forms the back surface of the first leaf valve, and the second leaf valve has a hole axially facing the first leaf valve and a notched passage opening from the outer periphery and leading to the hole.

2. A damping valve as claimed in claim 1, wherein the laminated leaf valve has a third leaf valve which is annular and overlaps the rear side of the second leaf valve so as to be capable of closing the hole of the second leaf valve.

3. A damping valve as claimed in claim 1, wherein the laminated leaf valve comprises a fourth leaf valve which is annular and has an outer diameter smaller than that of the second leaf valve, and which faces a part of the hole and is laminated on the rear side of the second leaf valve.

4. A damping valve as claimed in claim 1, wherein the stacked leaf valve comprises a fifth leaf valve which is annular in shape and has an outer diameter smaller than that of the second leaf valve, and which is stacked on the rear side of the second leaf valve without facing the hole.

5. A damping valve as claimed in claim 1, wherein the second leaf valve has a pair of arms facing each other on the outer circumferential side of the hole with the notched passage therebetween, and the radial lengths of the arms are different from each other.

6. A damping valve as claimed in claim 1, wherein the notched passage communicates with a position offset from the circumferential centre of the hole towards the circumferential end.

7. A shock absorber comprising: an outer tube; a shock absorber body having an outer tube, a rod inserted into said outer tube so as to be axially movable, and at least two working chambers through which liquid flows as a result of movement of said rod relative to said outer tube; and a damping valve as described in any one of claims 1 to 6, which is provided between said working chambers.

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