Laminated leaf valve and shock absorber

Abstract

A laminated leaf valve (V) of the present invention is allowed to deflect on a free end side and is stacked on a valve seat member (1) having a port (1c) to open and close the port (1c). The laminated leaf valve (V) comprises: an annular first leaf valve (2) having a through-hole (2a) that communicates with the port (1c); an annular second leaf valve (3) that is stacked on a back surface of the first leaf valve (2); and an annular third leaf valve (4) that is stacked on a back surface of the second leaf valve (3). The second leaf valve (3) is provided with: a plurality of communication holes (3a) formed at intervals in the circumferential direction and capable of communicating with the through-hole (2a); a plurality of cutout passages (3c) that open from the outer periphery serving as the free end and respectively lead to the corresponding communication holes (3a); and a fragile part (3d) for reducing rigidity, between the communication holes (3a, 3a) in the circumferential direction.

Description

Stacked leaf valves and shock absorbers

[0001] The present invention relates to stacked leaf valves and shock absorbers.

[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 port provided in the piston to connect the extension-side chamber and the compression-side chamber, and a stacked leaf valve placed on top of the piston to open and close the port.

[0004] The stacked leaf valve has its inner periphery fixed to the piston rod and overlapped on the piston to close the port, and opens the port by deflecting its outer periphery when pressure is applied upstream of the port.

[0005] In such stacked leaf valves, when the piston moves slowly relative to the cylinder, it may be desirable to build up a damping force proportional to the piston velocity, in which case a choke passage may be provided.

[0006] Specifically, as disclosed in JPH11-294515A, for example, a stacked leaf valve equipped with a choke passage comprises: a first leaf valve of an annular shape which is stacked directly on the piston and has an arc-shaped through-hole facing the port; a second leaf valve of an annular shape which has the same inner and outer diameter as the first leaf valve and is stacked on the side opposite the piston of the first leaf valve; the ...nular shape which has a plurality of arc-shaped communicating holes which communicate with the through-hole and notched passages which open from the outer periphery and communicate with the communicating holes; and a third leaf valve of an annular shape which has the same inner and outer diameter as the first and second leaf valves and is stacked on the side opposite the piston of the second leaf valve.

[0007] By sandwiching the second leaf valve between the first leaf valve and the third leaf valve, the stacked leaf valve closes the port while communicating the port with the outside of the stacked leaf valve via the through hole, the communication hole, and the notched passage, and the notched passage forms a choke or orifice.

[0008] In a laminated leaf valve configured in this manner, when the piston moves at a low speed, it does not deflect and remains seated on the valve seat formed on the piston and surrounding the port, but a damping force can be generated by passing the hydraulic oil through a choke passage.

[0009] JPH11-294515A

[0010] In this way, in a stacked leaf valve, the second leaf valve has a plurality of arc-shaped communicating holes arranged at equal intervals around the circumference, and a plurality of cutout passages that open from the outer periphery and communicate with each of the communicating holes.Since the communicating holes must be connected to the through holes of the first leaf valve, the circumferential length of the communicating holes is made as long as possible to ensure communication between the communicating holes and the through holes.

[0011] In the second leaf valve, the notched passage opens at the center of the arc-shaped communicating hole, and arc-shaped, elongated arm-like portions are formed on both sides of the notched passage at the outer periphery of the communicating hole. Therefore, if the circumferential length of the communicating hole is increased as described above, the length of the arm-like portions extending from the circumferential ends of the communicating hole to the notched passage will necessarily increase.

[0012] As a result, when the second leaf valves are transported or stored, the arm-shaped portions of the second leaf valves may enter the communicating holes of adjacent second leaf valves, causing the arm-shaped portions of adjacent second leaf valves to become entangled, which requires time and effort to untangle and separate the entangled second leaf valves when assembling the stacked leaf valves.

[0013] On the other hand, if the circumferential length of the communicating holes is shortened to shorten the circumferential length of the arm-like portions, it is possible to prevent the arm-like portions of the second leaf valve from becoming entangled with each other, but the spacing between the communicating holes in the circumferential direction of the second leaf valve becomes wider, which increases the bending rigidity of the second leaf valve and makes it less likely to deform.If this happens, and the first and third leaf valves are distorted when the second leaf valve is sandwiched between them, gaps will be created between the second leaf valve and the first and third leaf valves, preventing the choke characteristics provided by the notches from being exhibited as intended.

[0014] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a laminated leaf valve and a shock absorber that can be easily assembled and that can provide good choke characteristics.

[0015] In order to solve the above problems, the stacked leaf valve of the present invention is annular, with either the inner or outer periphery being a free end so that bending on the free end side is permitted, and is stacked on a valve seat member having a port to open and close the port, and comprises: an annular first leaf valve having a through hole communicating with the port; an annular second leaf valve stacked on the anti-seat side that forms the back surface of the first leaf valve; and an annular third leaf valve stacked on the anti-seat side that forms the back surface of the second leaf valve, and the second leaf valve has a plurality of communication holes that are spaced apart circumferentially and can communicate with the through holes, a plurality of notched passages that open from the free end and lead to the corresponding communication holes, and weak parts that reduce rigidity between the communication holes in the circumferential direction.

[0016] In a stacked leaf valve configured in this manner, the second leaf valve has weak portions with low rigidity between the communicating holes provided intermittently in the circumferential direction, making it easy to flex and bend, and can fit tightly to both the first leaf valve and the third leaf valve without creating gaps between them, thereby preventing the communicating holes from communicating with the working chamber through any means other than the notched passage. Furthermore, the provision of such weak portions ensures the ease of deformation of the second leaf valve and allows the second leaf valve to fit tightly to both the first leaf valve and the third leaf valve, so that the circumferential length of each communicating hole can be narrowed, preventing adjacent second leaf valves from becoming entangled during transportation or storage, reducing the effort required to separate the second leaf valves and reducing the workload when assembling the stacked leaf valve.

[0017] FIG. 1 is a longitudinal sectional view of a shock absorber to which a stacked leaf valve according to one embodiment of the present invention is applied. FIG. 2 is an enlarged sectional view of a stacked leaf valve according to one embodiment of the present invention. FIG. 3(a) is a plan view of a first leaf valve in a stacked leaf valve according to one embodiment of the present invention. FIG. 3(b) is a plan view of a second leaf valve in a stacked leaf valve according to one embodiment of the present invention. FIG. 3(c) is a plan view of a third leaf valve in a stacked leaf valve according to one embodiment of the present invention. FIG. 4 is a plan view of a second leaf valve in a stacked leaf valve according to a first modified example of the present invention. FIG. 5 is a plan view of a second leaf valve in a stacked leaf valve according to a second modified example of the present invention. FIG. 6 is a plan view of a second leaf valve in a stacked leaf valve according to a third modified example of the present invention.

[0018] The present invention will be described below based on the embodiments shown in the drawings. As shown in Figure 1, a stacked leaf valve V in one embodiment is applied to the piston portion of a shock absorber D. The stacked leaf valve V is annular, with its outer periphery as a free end, allowing for deflection on the free end side, and is stacked on a piston 1 serving as a valve seat member having a compression-side port 1c as a port, to open and close the compression-side port 1c. The stacked leaf valve V also includes a first annular leaf valve 2 having a through-hole 2a communicating with the compression-side port 1c, a second annular leaf valve 3 stacked on the back surface of the first leaf valve 2 on the side opposite the piston, and a third annular leaf valve 4 stacked on the back surface of the second leaf valve 3 on the side opposite the piston.

[0019] 1, a shock absorber D to which a laminated leaf valve V is applied includes a cylinder 10 as an outer tube, a rod 11 movably inserted into the cylinder 10, a piston 1 as a valve seat member connected to the rod 11 and inserted axially movably into the cylinder 10 to divide the interior of the cylinder 10 into two working chambers, an expansion-side chamber R1 and a compression-side chamber R2, and a laminated leaf valve V. This shock absorber D is used by being interposed between the body and axle of a vehicle (not shown), and suppresses vibrations of the vehicle body and wheels.

[0020] Hereinafter, each part of the stacked leaf valve V and the shock absorber D will be described in detail. First, each part of the shock absorber D will be described. As shown in Fig. 1 , the shock absorber D 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 connected to the rod 11 and movably inserted into the cylinder 10, which divides the interior of the cylinder 10 into an expansion-side chamber R1 and a compression-side chamber R2 as working chambers.

[0021] A bracket (not shown) is provided at the base end of the rod 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).

[0022] 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.

[0023] The shock absorber D 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 1 from the rod 11.

[0024] 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 a liquid. The liquid filled in the shock absorber D may be hydraulic oil, water, an aqueous solution, or other liquid. On the other hand, compressed air or a gas such as nitrogen gas is sealed in the air chamber G.

[0025] When the 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.

[0026] 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.

[0027] 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.

[0028] 1, the piston 1 serving as a valve seat member 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 screwed onto a threaded portion 11d of the rod 11. The piston 1 is also assembled to the rod 11, and the outer periphery of the piston 1 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.

[0029] 2 , a plurality of expansion-side ports 1b are provided in the main body 1a, opening from the lower end of the main body 1a in FIG. 2 and leading to the outer periphery at the upper end in FIG. 2 , a plurality of compression-side ports 1c as ports opening from the upper end of the main body 1a in FIG. 2 and leading to the outer periphery at the lower end in FIG. 2 , a ring-shaped seat portion 1d protruding downward from the lower end of the main body 1a in FIG. 2 and surrounding the outer periphery of the expansion-side port 1b, and a ring-shaped seat portion 1e protruding upward from the upper end of the main body 1a in FIG. 2 and surrounding the outer periphery of the compression-side port 1c.

[0030] 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 inner periphery seat portion 1f at its lower end, which protrudes downward from the inner periphery of the lower opening end of the expansion-side port 1b, and an inner periphery seat portion 1g at its upper end, which protrudes upward from the inner periphery of the upper opening end of the compression-side port 1c, as shown in Fig. 2 .

[0031] Eight expansion-side ports 1b are provided at equal intervals in the circumferential direction of the main body portion 1a, and each expansion-side port 1b opens between the inner seat portion 1f and the seat portion 1d at the lower end of the main body portion 1a in FIG. 2, extends obliquely upward, and opens at the outer periphery of the seat portion 1e at the upper end of the main body portion 1a in FIG. 2, thereby connecting the expansion-side chamber R1 and the compression-side chamber R2. Note that a plurality of expansion-side ports 1b are provided at equal intervals in the circumferential direction of the main body portion 1a. Furthermore, the expansion-side ports 1b are expansion-side ports that allow liquid to flow from the expansion-side chamber R1 to the compression-side chamber R2 when the shock absorber D is extended.

[0032] The compression-side port 1c as a port opens between the inner peripheral seat portion 1g and the seat portion 1e at the upper end of the main body portion 1a in FIG. 2, extends downward in the axial direction, and opens at the outer periphery of the seat portion 1d at the lower end of the main body portion 1a in FIG. 2, thereby connecting the expansion-side chamber R1 and the compression-side chamber R2. The compression-side ports 1c are provided in the main body portion 1a in a number of eight, the same as the expansion-side ports 1b, at equal intervals in the circumferential direction of the main body portion 1a. The compression-side ports 1c are compression-side ports that allow liquid to flow from the compression-side chamber R2 to the expansion-side chamber R1 during contraction of the shock absorber D. The number of the expansion-side ports 1b and the compression-side ports 1c provided on the piston 1 can be arbitrarily changed in design. Furthermore, the expansion-side ports 1b and the compression-side ports 1c may be provided along the axial direction of the main body portion 1a as long as they are surrounded by the corresponding seats 1d and 1e, respectively.

[0033] In this embodiment, the seat portion 1d is provided at the lower end of the main body portion 1a in FIG. 2 and is formed by an annular protrusion protruding downward from the lower end of the main body portion 1a. It surrounds the outer periphery of the expansion-side port 1b and functions 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 FIG. 2 and is formed by an annular protrusion protruding upward from the upper end of the main body portion 1a. It surrounds the outer periphery of the compression-side port 1c and functions as a compression-side valve seat. It is sufficient that the seat portions 1d and 1e surround the ports 1b and 1c, respectively, and function as valve seats. Depending on the arrangement of the ports 1b and 1c relative to the main body portion 1a, the seat portions 1d and 1e may be petal-shaped and connected to the inner periphery seat portions 1f and 1g to independently surround the ports 1b and 1c.

[0034] Next, the stacked leaf valve V includes a first annular leaf valve 2 having a through hole 2a connected to the compression side port 1c, a second annular leaf valve 3 overlapped on the side opposite the piston that forms the back surface of the first leaf valve 2, and a third annular leaf valve 4 overlapped on the side opposite the piston that forms the back surface of the second leaf valve 3.

[0035] 2 , which is the expansion-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 11 a 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 for deflection on the outer periphery side. In this embodiment, the laminated leaf valve V includes a plurality of leaf valves that are annular and have an outer diameter smaller than that of the third leaf valve 4 and are stacked on the back surfaces of the three leaf valves, the first leaf valve 2, the second leaf valve 3, and the third leaf valve 4, so that the outer diameters of the leaf valves gradually decrease. However, the leaf valves stacked on the back surfaces of at least the first leaf valve 2, the second leaf valve 3, and the third leaf valve 4 may be eliminated, or the number of leaf valves stacked may be changed.

[0036] Furthermore, above the stacked leaf valve V in FIG. 2, there are stacked a spacer 5 whose outer diameter is smaller than that of the uppermost leaf valve of the stacked leaf valve V, and an annular valve stopper 6 whose outer diameter is approximately the same as that of the first leaf valve 2. When the stacked leaf valve V is fixed to the small diameter portion 11a of the rod 11 together with the spacer 5, the stacked leaf valve V can bend with the outer peripheral edge of the spacer 5 as a fulcrum, and if the amount of bending becomes too great, the stacked leaf valve V will come into contact with the valve stopper 6, restricting further bending and preventing deterioration due to excessive bending.

[0037] When the stacked leaf valves V are stacked on the upper end of the piston 1 in FIG. 2, the lowermost first leaf valve 2 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 compression side port 1c.

[0038] Furthermore, when the laminated leaf valve V receives pressure from the compression-side chamber R2 acting through the compression-side port 1c and bends its outer periphery to separate from the seat portion 1e, it opens the compression-side port 1c, allowing the liquid to flow from the compression-side chamber R2 to the expansion-side chamber R1 through the gap between the compression-side port 1c and the seat portion 1e, while providing resistance to the flow. In this way, the laminated leaf valve V functions as a compression-side damping valve that opens and closes the compression-side port 1c to provide resistance to the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1.

[0039] The first leaf valve 2, the second leaf valve 3, and the third leaf valve 4 all have the same inner diameter and outer diameter. As shown in Fig. 3, the first leaf valve 2 is annular and has arc-shaped through-holes 2a spaced apart in the circumferential direction in a range facing between the inner circumferential seat portion 1g and the seat portion 1e of the piston 1 as viewed in the axial direction. When the first leaf valves 2 are stacked at the upper end of the piston 1 in Fig. 2, the through-holes 2a face between the inner circumferential seat portion 1g and the seat portion 1e and communicate with the compression-side port 1c. Note that a plurality of through-holes 2a may be provided lined up in the circumferential direction.

[0040] 3, the second leaf valve 3 is annular and has three arc-shaped communication holes 3a spaced apart in the circumferential direction in an area facing the inner circumferential seat portion 1g and the seat portion 1e of the piston 1 as viewed from the axial direction, three arc-shaped holes 3b provided between the communication holes 3a, 3a in an area facing the inner circumferential seat portion 1g and the seat portion 1e of the piston 1 as viewed from the axial direction, and three notched passages 3c opening from the outer periphery and communicating with the corresponding communication holes 3a. The third leaf valve 4 is annular and has no holes or the like as shown in FIG.

[0041] When the second leaf valve 3 is stacked on the rear surface of the first leaf valve 2 opposite the piston side, and the third leaf valve 4 is stacked on the rear surface of the second leaf valve 3 opposite the piston side, the second leaf valve 3 is sandwiched between the first leaf valve 2 and the third leaf valve 4, and the communication hole 3a faces the through hole 2a of the first leaf valve 2, and the communication hole 3a communicates with the compression-side port 1c via the through hole 2a. Furthermore, the communication hole 3a is blocked at its upper side by the third leaf valve 4 stacked on the second leaf valve 3, so that the communication hole 3a communicates with the expansion-side chamber R1 only via the notched passage 3c. Furthermore, the notched passage 3c is blocked at its upper and lower ends by the first leaf valve 2 and the third leaf valve 4, forming an elongated choke passage that communicates the communication hole 3a with the expansion-side chamber R1. Although the first leaf valve 2, second leaf valve 3 and third leaf valve 4 have the same outer diameter, this can be changed as desired as long as, when the second leaf valve 3 is sandwiched between the first leaf valve 2 and the third leaf valve 4, the communication hole 3a communicates with the outer periphery of the stacked leaf valve V only through the notched passage 3c and the notched passage 3c functions as a choke passage by covering the top and bottom of the notched passage 3c. In this embodiment, the notched passage 3c functions as a choke passage, but it may also function as an orifice instead.

[0042] Although the three holes 3b between the communication holes 3a, 3a communicate with the compression side port 1c when they are axially opposed to the through-hole 2a, they do not function as passages because they are blocked by the third leaf valve 4, but their provision in the second leaf valve 3 reduces the flexural rigidity of the second leaf valve 3. In other words, although the holes 3b are not used as passages, they reduce the rigidity of the second leaf valve 3 at the locations where the holes 3b are installed in the second leaf valve 3, and weakened portions 3d are formed around the locations.

[0043] In this way, the second leaf valve 3 has the communication holes 3a and the holes 3b alternately provided at intervals in the circumferential direction, and the rigidity of the second leaf valve 3 is low all around. The first leaf valve 2 also has an arc-shaped through-hole 2a that is wide in the circumferential direction, and so has low rigidity all around, similar to the second leaf valve 3. Therefore, the first leaf valve 2 and the second leaf valve 3 are more likely to bend in the radial and circumferential directions than the third leaf valve.

[0044] Next, the extension-side leaf valves 7 are stacked below the piston 1 in FIG. 1. The extension-side leaf valves 7 are laminated leaf valves formed by stacking a plurality of annular plates, and are stacked at the lower end of the piston 1 in FIG. 2 as a valve seat member, and are fixed to the outer periphery of the small diameter portion 11a of the rod 11 together with the piston 1. The inner periphery of the lowermost annular plate of the extension-side leaf valve 7 abuts against the inner periphery seat portion 1f, 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 valve 7 is allowed to bend in a direction away from the piston 1 on the outer periphery side, which is the free end side, and the outer periphery side is seated on and removed from the seat portion 1d.

[0045] When the outer peripheral side of the extension-side leaf valve 7 is seated on the seat portion 1d, it is in close contact with the inner peripheral seat portion 1f and the seat portion 1d, blocking the outlet end of the extension-side port 1b that opens between the inner peripheral seat portion 1f and the seat portion 1d. When the free end is bent by pressure from the extension-side port 1b side and separated from the seat portion 1d, it opens the extension-side port 1b and provides resistance to the flow of liquid passing through the gap that is generated between it and the seat portion 1d.

[0046] The valve stopper 6, spacer 5, stacked leaf valve V, piston 1, and extension-side leaf valve 7 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.

[0047] The laminated leaf 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 Figure 1 relative to the cylinder 10, the upward movement of the piston 1 in Figure 1 causes the liquid in the expansion-side chamber R1, which is compressed, to bend the expansion-side leaf valve 7 and pass through the expansion-side port 1b and move to the compression-side chamber R2. Furthermore, during the extension operation of the shock absorber D, the laminated leaf valve V closes and seats on the seat portion 1e, but the compression-side port 1c is connected to the expansion-side chamber R1 through the through-hole 2a, the communication hole 3a, and the notched passage 3c, so that the liquid in the expansion-side chamber R1 can move to the compression-side chamber R2 through the choke passage formed by the notched passage 3c.

[0048] During the extension operation of the shock absorber D, when the piston speed is low and the pressure in the expansion-side chamber R1 does not reach the valve opening pressure of the expansion-side leaf valve 7, the liquid cannot pass through the expansion-side port 1b because the expansion-side port 1b is kept closed by the expansion-side leaf valve 7, and instead passes through the compression-side port 1c and the choke passage to move from the expansion-side chamber R1 to the compression-side chamber R2.

[0049] Therefore, when the shock absorber D is extending and the piston speed is low, the choke passage provides resistance to the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2, and the shock absorber D generates a damping force that hinders the extension operation.

[0050] On the other hand, when the piston speed exceeds the low speed and becomes high speed during the extension operation of the shock absorber D, the pressure in the extension-side chamber R1 reaches the valve opening pressure of the extension-side leaf valve 7, causing the extension-side leaf valve 7 to bend and open. Then, the liquid passes through the extension-side port 1b and then passes between the extension-side leaf valve 7 and the seat portion 1d, moving from the extension-side chamber R1 to the compression-side chamber R2.

[0051] Therefore, when the shock absorber D is extended and the piston speed is high, the extension-side leaf valve 7 provides resistance to the flow of fluid from the extension-side chamber R1 to the compression-side chamber R2, and the shock absorber D generates a damping force that hinders the extension operation.

[0052] As described above, when shock absorber D extends, if the piston speed is low, it generates a damping force specific to a choke that rises in proportion to the piston speed, and if the piston speed is high, it generates a damping force specific to a leaf valve that increases in proportion to the piston speed, although the rate at which the damping force increases with respect to the piston speed is smaller than at low speeds. Note that as shock absorber D extends, free piston 14 rises in Figure 1 in accordance with the volume of rod 11 retracted from cylinder 10, expanding air chamber G and compensating for the volume of rod 11 retracted from cylinder 10.

[0053] On the other hand, 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 in FIG. 1 causes the liquid in the compression-side chamber R2 to bend the laminated leaf valve V and move through the compression-side port 1c to the expansion-side chamber R1.

[0054] Furthermore, when the shock absorber D is contracting, if the piston speed is low and the pressure in the compression-side chamber R2 does not reach the valve-opening pressure of the stacked leaf valve V, the stacked leaf valve V does not bend and remains seated on the seat portion 1e, so that the liquid passes through the compression-side port 1c and the choke passage and moves from the compression-side chamber R2 to the extension-side chamber R1.

[0055] Therefore, when the shock absorber D is contracting and the piston speed is low, the choke passage provides resistance to the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1, and the shock absorber D generates a damping force that hinders the contraction operation.

[0056] On the other hand, when the shock absorber D is contracting, if the piston speed exceeds the low speed and becomes high, the pressure in the compression side chamber R2 reaches the valve opening pressure of the laminated leaf valve V, causing the laminated leaf valve V to bend and open, and the liquid passes through the compression side port 1c and then passes between the laminated leaf valve V and the seat portion 1e, moving from the compression side chamber R2 to the extension side chamber R1.

[0057] Therefore, when the shock absorber D is contracting and the piston speed is high, the stacked leaf valve V provides resistance to the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1, and the shock absorber D generates a damping force that hinders the contraction operation.

[0058] As described above, when shock absorber D contracts, if the piston speed of shock absorber D is low, a damping force characteristic of a choke is generated, in which the damping force increases proportionally to the piston speed, and if the piston speed is high, a damping force characteristic of a leaf valve is generated, in which the rate at which the damping force increases with respect to the piston speed is smaller than at low speeds, but the damping force increases proportionally to the piston speed. As shock absorber D contracts, free piston 14 moves down in FIG. 1 in accordance with the volume of rod 11 entering cylinder 10, thereby reducing air chamber G and compensating for the volume of rod 11 entering cylinder 10.

[0059] Here, the second leaf valve 3 in the stacked leaf valve V has communicating holes 3a and holes 3b alternately arranged at intervals in the circumferential direction, and has weak portions 3d with low rigidity formed by providing holes 3b between the communicating holes 3a, 3a, so that the second leaf valve 3 can tightly fit to the first leaf valve 2 and the third leaf valve 4. Therefore, no gap is created between the first leaf valve 2 or the third leaf valve 4, and the communicating holes 3a can be prevented from communicating with the expansion-side chamber R1 through any means other than the choke passage. Therefore, the shock absorber D can generate a desired damping force by the choke passage when the piston speed during expansion / contraction operation is low.

[0060] As described above, the stacked leaf valve V of this embodiment is annular, with its outer periphery as a free end, allowing deflection on the free end side, and is stacked on a piston (valve seat member) 1 having a compression side port (port) 1c to open and close the compression side port (port) 1c. The stacked leaf valve V comprises an annular first leaf valve 2 having a through hole 2a communicating with the compression side port (port) 1c, an annular second leaf valve 3 stacked on the anti-piston side (anti-valve seat side) which forms the back surface of the first leaf valve 2, and an annular third leaf valve 4 stacked on the anti-piston side (anti-valve seat side) which forms the back surface of the second leaf valve 3. The second leaf valve 3 comprises a plurality of communication holes 3a spaced apart in the circumferential direction and capable of communicating with the through hole 2a, a plurality of cutout passages 3c which open from the outer periphery which forms the free end and lead to the corresponding communication holes 3a, and weak portions 3d which reduce rigidity between the communication holes 3a, 3a in the circumferential direction.

[0061] In the stacked leaf valve V configured in this manner, the second leaf valve 3 has weak portions 3d with low rigidity between the communicating holes 3a, 3a provided intermittently in the circumferential direction, making it easy to flex and bend, and can tightly fit both the first leaf valve 2 and the third leaf valve 4 without creating gaps between them, thereby preventing the communicating holes 3a from communicating with the expansion-side chamber R1 through any route other than the choke passage. Therefore, the provision of the weak portions 3d ensures the ease of deformation of the second leaf valve 3 and allows the second leaf valve 3 to tightly fit both the first leaf valve 2 and the third leaf valve 4, making it possible to narrow the circumferential length of each communicating hole 3a. Furthermore, narrowing the circumferential width of each communicating hole 3a shortens the circumferential length W of arm-shaped portions 3e, which are outer peripheral portions of the communicating holes 3a in the second leaf valve 3 and extend from the circumferential ends of the communicating holes 3a to the notched passages 3c, as shown in FIG. 3 . As described above, according to the stacked leaf valve V of this embodiment, the circumferential length W of the arm-like portions 3 e can be shortened, which prevents the arm-like portions 3 e of two adjacent second leaf valves 3 from becoming entangled when the second leaf valves 3 are transported or stored, and reduces the effort required to separate the second leaf valves 3, thereby reducing the workload when assembling the stacked leaf valve V. As described above, the stacked leaf valve V of this embodiment can improve assembly ease and achieve good choke characteristics.

[0062] Furthermore, in the stacked leaf valve V of this embodiment, the fragile portions 3 d are formed by holes 3 b provided between the communicating holes 3 a, 3 a in the circumferential direction of the second leaf valve 3. With the stacked leaf valve V configured in this manner, the fragile portions 3 d can be formed without affecting the inner and outer periphery shapes of the second leaf valve 3, so that even with the fragile portions 3 d provided, workers assembling the stacked leaf valve V can perform the assembly work without any discomfort.

[0063] The holes 3b for forming the fragile portion 3d in the second leaf valve 3 may be circular or have another shape instead of an arc shape, and two or more holes 3b may be provided between the communicating holes 3a in the circumferential direction of the second leaf valve 3, as in the first modified example of the stacked leaf valve V shown in Figure 4. Furthermore, the number and shapes of the holes 3b may differ between the communicating holes 3a. The rigidity of the fragile portion 3d can be adjusted by the number and opening area of ​​the holes 3b provided between the communicating holes 3a, 3a, so the number and opening area of ​​the holes 3b may be set to be optimal depending on the rigidity required of the second leaf valve 3.

[0064] Furthermore, instead of being formed by providing holes 3b between the communicating holes 3a, 3a in the circumferential direction of the second leaf valve 3, the fragile portions 3d may be formed by notches 3f, 3g that open from the inner or outer periphery of the second leaf valve 3 and are provided in positions that do not face the through-holes 2a of the first leaf valve 2, as in the second modified example of the stacked leaf valve V shown in Fig. 5. With the stacked leaf valve V configured in this manner, even if the notches 3f, 3g are provided in the second leaf valve 3, the rigidity between the communicating holes 3a, 3a can be reduced, so that the desired choke characteristics can be obtained and entanglement of the arm-like portions 3e can be suppressed, thereby improving ease of assembly. The notches 3f, 3g may be provided at positions that avoid the axial range of the second leaf valve 3 that extends from the inner periphery of the seat portion 1e to the outer periphery of the inner seat portion 1g, and the weakened portion 3d may be formed by providing only the notch 3f that opens from the inner periphery or only the notch 3g that opens from the outer periphery between the communicating holes 3a, 3a of the second leaf valve 3. Since the notches 3f, 3g are provided at positions that do not communicate with the through-hole 2a, as long as they avoid the notched passage 3c and the communicating hole 3a, the circumferential ends of the second leaf valve 3 can be extended to the inner periphery or outer periphery of the communicating hole 3a while being located between the communicating holes 3a, 3a in the circumferential direction of the second leaf valve 3. This allows the rigidity of the inner periphery or outer periphery of the communicating hole 3a of the second leaf valve 3 to be reduced, thereby improving the design flexibility of the rigidity of the second leaf valve 3.

[0065] Furthermore, instead of all of the communicating holes 3 a being equally spaced circumferentially with respect to the second leaf valve 3, some or all of the communicating holes 3 a may be spaced unequal, as in the third modified example of the stacked leaf valve V shown in FIG. 6 . By spaced unequally in some or all of the communicating holes 3 a, the second leaf valve 3 is provided with wide and narrow circumferentially spaced communicating holes 3 a. Even if the second leaf valve 3 has a fragile portion 3 d, the wide-spaced portions tend to be more rigid than the narrow-spaced portions. This creates a difference in the circumferential rigidity of the entire stacked leaf valve V, allowing the outer periphery of the stacked leaf valve V to differ in flexibility in the circumferential direction. This difference in flexibility in the circumferential direction prevents the entire periphery of the stacked leaf valve V from suddenly separating from the seat portion 1 e during valve opening, thereby reducing pressure fluctuations during valve opening and reducing the occurrence of abnormal noise and sudden changes in damping force.

[0066] 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 piston (valve seat member) 1 that is housed in the cylinder (outer tube) 10 and partitions the cylinder (outer tube) 10 into an expansion-side chamber (working chamber) R1 and a compression-side chamber (working chamber) R2 and that has a compression-side port (port) 1c, and a laminated leaf valve V that is laminated on the piston (valve seat member) 1. The shock absorber D configured in this manner can improve assembly ease and achieve good choke characteristics.

[0067] 1, the two working chambers are an expansion-side chamber R1 and a compression-side chamber R2, and the laminated leaf valve V is provided above the piston 1 serving as a valve seat member in FIG. 1, and the laminated leaf valve V is used as a valve that generates a compression-side damping force, but the laminated leaf valve V may be provided on both the expansion-side chamber side and the compression-side chamber side, or only on the compression-side chamber side, of the piston 1. Also, in the case where the shock absorber D is a twin-tube shock absorber that has an outer shell as an outer tube around the outer periphery of the cylinder and a reservoir between the cylinder and the outer shell, the valve case that separates the compression-side chamber and the reservoir may be used as a valve seat member, and the laminated leaf valve V may be provided to open and close a port of the valve case.

[0068] Furthermore, as described above, the stacked leaf valve V is configured so as to open outward, with the inner periphery as the fixed end and fixed to the small diameter portion 11a of the rod 11, and the outer periphery as the free end, allowing for bending on the free end side, but the stacked leaf valve V may also be configured so as to open inward, with the outer periphery as the fixed end and the inner periphery as the free end, allowing for bending on the inner periphery side. When the stacked leaf valve V is configured so as to open inward, the outer diameters of the stacked leaf valves V may be made uniform, the outer peripheries of the stacked leaf valves V may be fixed immovably to the valve seat member, and the notched passages may be opened from the inner periphery, which is the free end of the stacked leaf valve V, to communicate with the communication hole.

[0069] 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.

[0070] DESCRIPTION OF SYMBOLS 1: Piston (valve seat member), 1c: Compression side port (port), 2: First leaf valve, 2a: Through hole, 3: Second leaf valve, 3a: Communication hole, 3b: Notched passage, 3c: Hole, 3d: Weak portion, 4: Third leaf valve, 10: Cylinder (outer tube), 11: Rod, D: Shock absorber, V: Stacked leaf valve, R1: Expansion side chamber (operating chamber), R2: Compression side chamber (operating chamber)

Claims

1. A stacked leaf valve which is annular with either an inner or outer periphery as a free end, allowing deflection on the free end side, and is stacked on a valve seat member having a port to open and close the port, comprising: a first annular leaf valve having a through hole communicating with the port; a second annular leaf valve stacked on the anti-valve-seat side surface which forms the back surface of the first leaf valve; and a third annular leaf valve stacked on the anti-valve-seat side surface which forms the back surface of the second leaf valve, wherein the second leaf valve has a plurality of communication holes spaced apart in the circumferential direction and capable of communicating with the through holes, a plurality of notched passages which open from the free end and lead to the respective communication holes, and weak portions which reduce rigidity between the communication holes in the circumferential direction.

2. A stacked leaf valve as claimed in claim 1, wherein the fragile portion is formed by a hole provided between the communication holes in the circumferential direction of the second leaf valve.

3. A stacked leaf valve as claimed in claim 1, wherein the fragile portion is formed by a notch provided in a circumferential direction of the second leaf valve between the communication holes and at a position not facing the through hole.

4. A stacked leaf valve according to claim 1, wherein the second leaf valve has a portion where the circumferential spacing between the communication holes is wide and a portion where the circumferential spacing is narrow.

5. A shock absorber comprising: an outer tube; a rod inserted into said outer tube so as to be axially movable; a valve seat member housed within said outer tube to partition said outer tube into two working chambers and having a port; and a laminated leaf valve according to any one of claims 1 to 4 laminated on said valve seat member.

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