Laminate leaf valve and buffer

Abstract

To provide a laminate leaf valve and a buffer which can provide an excellent choke property while improving an assembly property.SOLUTION: A laminate leaf valve V of the present invention is laminated on a valve seat member 1 having a port 1c to open and close the port 1c. The laminate leaf valve includes: a circular first leaf valve 2 having a through hole 2a communicating with the port 1c; a circular second leaf valve 3 laminated on a back face of the first leaf valve 2; and a circular third leaf valve 4 laminated on a back face of the second leaf valve 3. The second leaf valve 3 includes: a plurality of communication holes 3a provided in a circumferential direction with an interval therebetween and communicating with the through hole 2a; a plurality of notch chokes 3b opening from an outer periphery as free end and communicating with the corresponding communication holes 3a; and a fragile part 3d formed on both sides in a circumferential direction of the notch passage 3b which is an outer peripheral part of the communication hole 3a, the fragile part lowering rigidity of an arm part 3c.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[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 that 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 inside 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 stacked on the piston to open and close the port.

[0004] The stacked leaf valve has an inner periphery fixed to a piston rod and overlaps with a piston to close a port, and opens the port by deflecting the 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, a stacked leaf valve with a choke passage comprises a first leaf valve which is annular and has an arc-shaped through hole facing a port, a second leaf valve which is annular and has inner and outer diameters with the first leaf valve and is stacked on the anti-piston side of the first leaf valve, and has a plurality of arc-shaped through holes which communicate with the through hole and notched passages which open from the outer periphery and communicate with the through holes, and a third leaf valve which is annular and has the same inner and outer diameters as the first and second leaf valves, and is stacked on the anti-piston side of the second leaf valve (see, for example, Patent Document 1).

[0007] By sandwiching the second leaf valve between the first leaf valve and the third leaf valve, the stacked leaf valve connects the port to the outside of the stacked leaf valve through the through hole, communication hole and notch while blocking the port, and the notch passage forms a choke or orifice.

[0008] In a laminated leaf valve constructed in this manner, when the piston moves at a slow speed, it does not bend but 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 the cutout passage. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 11-294515 Summary of the Invention [Problem to be solved by the invention]

[0010] In this manner, in a stacked leaf valve, the second leaf valve has a plurality of arc-shaped communicating holes arranged at equal intervals in the circumferential direction, and a plurality of notched passages which open from the outer periphery and communicate with each of the communicating holes. Because 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 arms 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 arms extending from the circumferential ends of the communicating hole to the notched passage will necessarily be increased.

[0012] As a result, when the second leaf valves are transported or stored, the arms of adjacent second leaf valves may become entangled, for example, by entering the communicating hole of an adjacent second leaf valve, and this requires time-consuming work 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 communication hole is shortened to shorten the circumferential length of the arms, it is possible to prevent the second leaf valve from becoming entangled, but the shortened length of the arms increases the bending rigidity of the arms and makes them less likely to deform. As a result, when the second leaf valve is sandwiched between the first and third leaf valves, the arms are less likely to come into close contact with the first and third leaf valves, creating gaps between the arms and the first and third leaf valves, which causes a problem that the choke characteristics and orifice characteristics of the cutout passage are not exhibited as intended.

[0014] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a laminated leaf valve and shock absorber that can be easily assembled and have good characteristics. [Means for solving the problem]

[0015] In order to solve the above problems, the stacked leaf valve of the present invention is annular in shape with either the inner or outer periphery as a free end to allow bending on the free end side, 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 connected to the port; an annular second leaf valve stacked on the anti-valve-seat side surface that forms the back surface of the first leaf valve; and an annular third leaf valve stacked on the anti-valve-seat side surface that forms the back surface of the second leaf valve, and 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 cutout passages that open from the free end and each lead to a corresponding communication hole, and a fragile portion that reduces the rigidity of an arm portion formed on the outer periphery of the communication hole, at least on one side in the circumferential direction of the cutout passage.

[0016] In the stacked leaf valve configured in this manner, the arm portion of the second leaf valve has a weak portion with low rigidity and is easily bent and deformed, and can fit tightly to both the first leaf valve 2 and the third leaf valve 4 without creating a gap between the first leaf valve and the third leaf valve, thereby preventing the communication hole from communicating with the working chamber through anything other than the choke passage. Also, since the arm portion has a weak portion in this manner, it can fit tightly to both the first leaf valve and the third leaf valve, so that the circumferential length of each communication hole in the second leaf valve can be narrowed, and the workload when assembling the stacked leaf valve V can be reduced.

[0017] Furthermore, the weakened portion in the stacked leaf valve may be formed by a notch that opens from the circumferential end of the communicating hole and extends toward the free end of the arm. With a stacked leaf valve configured in this manner, the weakened portion can be formed without affecting the shape of the inner and outer periphery of the second leaf valve, so that even if the weakened portion is provided, a worker assembling the stacked leaf valve can perform the assembly work without feeling uncomfortable.

[0018] Furthermore, the weakened portion in the stacked leaf valve may be formed by a notched groove that opens from the free end side of the arm and extends toward the circumferential end of the communication hole. In a stacked leaf valve configured in this manner, the notched groove is provided at a position that does not communicate with the through hole, so that as long as the notched passage and the communication hole are avoided, there is a high degree of freedom in designing the location and shape of the opening in the second leaf valve and it is also easy to tune the rigidity of the arm.

[0019] The weak portion in the stacked leaf valve may be formed by a hole provided in the arm portion. With a stacked leaf valve configured in this manner, the weak portion can be formed without affecting the shape of the inner and outer periphery of the second leaf valve, so that even if the weak portion is provided, a worker assembling the stacked leaf valve can perform the assembly work without feeling uncomfortable, and since the stiffness of the arm portion can be easily adjusted by adjusting the number of holes provided and the opening area, tuning of the stiffness of the arm portion is also easy.

[0020] The shock absorber of the present invention includes an outer tube, a rod inserted into the outer tube so as to be axially movable, a valve seat member housed in the outer tube to divide two working chambers into the outer tube and having ports, and a laminated leaf valve laminated on the valve seat member. The shock absorber configured in this manner can improve assembly ease and provide good choke characteristics. Effect of the Invention

[0021] According to the laminated leaf valve and shock absorber of the present invention, it is possible to improve the ease of assembly and obtain good choke characteristics. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a vertical sectional view of a shock absorber to which a laminated leaf valve according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a laminated leaf valve according to one embodiment of the present invention. [Diagram 3]Figure 3(a) is a plan view of a first leaf valve in a stacked leaf valve of an embodiment of the present invention, Figure 3(b) is a plan view of a second leaf valve in the stacked leaf valve of an embodiment of the present invention, and Figure 3(c) is a plan view of a third leaf valve in the stacked leaf valve of an embodiment of the present invention. [Figure 4] FIG. 4 is a plan view of a second leaf valve in a stacked leaf valve according to a first modified example of an embodiment of the present invention. [Diagram 5] FIG. 5 is a plan view of a second leaf valve in a stacked leaf valve according to a second modified example of an embodiment of the present invention. [Figure 6] FIG. 6 is a plan view of a second leaf valve in a stacked leaf valve according to a third modified example of an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will be described below based on the embodiment shown in the drawings. As shown in FIG. 1, a laminated leaf valve V in one embodiment is applied to a piston part of a shock absorber D, and is laminated on a piston 1 as a valve seat member having a compression side port 1c as a port, with an outer periphery as a free end and allowing bending of the free end side, to open and close the compression side port 1c. The laminated leaf valve V also includes a first leaf valve 2 having a through hole 2a communicating with the compression side port 1c, a second leaf valve 3 having an annular shape laminated on the side opposite the piston that is the back surface of the first leaf valve 2, and a third leaf valve 4 having an annular shape laminated on the side opposite the piston that is the back surface of the second leaf valve 3.

[0024] 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 inside 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 the axle of a vehicle (not shown), and suppresses vibrations of the vehicle body and wheels.

[0025] Hereinafter, each part of the laminated 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 bottomed cylindrical cylinder 10 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 inside of the cylinder 10 into an expansion-side chamber R1 and a compression-side chamber R2 as working chambers.

[0026] 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).

[0027] In this way, the shock absorber D is interposed between the vehicle body and the axle. When the vehicle runs on an uneven road surface and the wheels vibrate up and down relative to the vehicle body, the rod 11 moves in and out of the cylinder 10, the shock absorber D expands and contracts, and the piston 1 moves up and down (axially) within the cylinder 10.

[0028] 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 around its inner periphery. Thus, the inside of the cylinder 10 is an enclosed space. A free piston 14 is slidably inserted into the cylinder 10 on the opposite side of the piston 1 to the rod 11.

[0029] 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 11 side and a compression side chamber R2 on the piston side, and the extension side chamber R1 and the compression side chamber R2 are each filled with liquid. The liquid filled in the shock absorber D may be hydraulic oil, water, an aqueous solution, or other liquid. On the other hand, the air chamber G is filled with compressed air or a gas such as nitrogen gas.

[0030] When the rod 11 retreats from the cylinder 10 during the extension operation of the shock absorber D, the free piston 14 moves upward within the cylinder 10 in accordance with the volume of the retreated rod 11, expanding the air chamber G and compensating for the volume of the rod 11 retreating from the cylinder 10. Conversely, when the shock absorber D contracts, the rod 11 advances into the cylinder 10, and the free piston 14 moves downward within the cylinder 10 in accordance with the volume of the advanced 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, a bellows, or the like may be used to separate the liquid chamber L and the air chamber G, and the configuration of the movable partition that serves as this partition can be changed as appropriate.

[0031] As described above, in this embodiment, the shock absorber D is a single-rod, single-cylinder shock absorber, and when the shock absorber D expands or contracts, the free piston (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 changed as appropriate. For example, when 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 double-cylinder shock absorber, the volume of the rod 11 moving in and out of the cylinder 10 may be compensated for by the reservoir. 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 outside the cylinder 10 from both ends of the cylinder 10.

[0032] The rod 11 has a reduced outer diameter at the tip side, and is equipped with a small diameter portion 11a having a small outer diameter at the tip side, 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 Figure 1, a step portion 11c provided at the boundary between the small diameter portion 11a and the large diameter portion 11b, and a screw portion 11d provided on the outer periphery of the tip of the small diameter portion 11a.

[0033] 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 attached to the rod 11, and its outer periphery is brought into sliding contact with the inner periphery of the cylinder 10, dividing the inside of the cylinder 10 into an expansion-side chamber R1 and a compression-side chamber R2 serving as working chambers.

[0034] 2 and surrounding the outer periphery of the compression side port 1c. In more detail, the piston 1 includes a circular main body portion 1a having a cylindrical portion on its outer periphery that protrudes downward in FIG. 2, a plurality of expansion side ports 1b provided in the main body portion 1a and opening from the lower end of the main body portion 1a in FIG. 2 and leading to the outer periphery at 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 outer periphery at the lower end in FIG. 2, a circular seat portion 1d protruding downward from the lower end of the main body portion 1a in FIG. 2 and surrounding the outer periphery of the expansion side port 1b, and a circular seat portion 1e protruding upward from the upper end of the main body portion 1a in FIG. 2 and surrounding the outer periphery of the compression side port 1c.

[0035] 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, which is a lower end and protrudes downward from the inner periphery side of the lower opening end of the expansion-side port 1b, and an inner periphery seat portion 1g, which is an upper end and protrudes upward from the inner periphery side of the upper opening end of the compression-side port 1c, as shown in Fig. 2.

[0036] The expansion-side ports 1b are provided in eight pieces at equal intervals in the circumferential direction of the main body 1a, and open between the inner peripheral seat portion 1f and the seat portion 1d at the lower end of the main body 1a in FIG. 2, extend obliquely upward, and open on the outer periphery of the seat portion 1e at the upper end of the main body 1a in FIG. 2, thereby communicating the expansion-side chamber R1 and the compression-side chamber R2. The expansion-side ports 1b are provided in multiple pieces at equal intervals in the circumferential direction of the main body 1a. The expansion-side ports 1b are expansion-side ports that allow the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2 during the expansion operation of the shock absorber D.

[0037] 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, opens on the outer periphery of the seat portion 1d at the lower end of the main body portion 1a in FIG. 2, and communicates with 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 the same number as the expansion side ports 1b, eight of which are equally spaced in the circumferential direction of the main body portion 1a. The compression side ports 1c are compression side ports that allow the flow of liquid from the compression side chamber R2 to the expansion side chamber R1 during the contraction operation of the shock absorber D. The number of the expansion side ports 1b and the compression side ports 1c provided for the piston 1 can be arbitrarily changed in design, and 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.

[0038] 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, and functions as an expansion-side valve seat by surrounding the outer periphery of the expansion-side port 1b. 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, and functions as a contraction-side valve seat by surrounding the outer periphery of the contraction-side port 1c. Note that the seat portions 1d and 1e only need to be able to function as valve seats surrounding the ports 1b and 1c, and may be petal-shaped so as to be connected to the inner seat portions 1f and 1g and independently surround the ports 1b and 1c depending on the arrangement of the ports 1b and 1c relative to the main body portion 1a.

[0039] Next, the stacked leaf valve V includes a first leaf valve 2 having a through hole 2a connected to the compression side port 1c, a second leaf valve 3 having a circular shape overlapped on the anti-piston side which forms the back surface of the first leaf valve 2, and a third leaf valve 4 having a circular shape overlapped on the anti-piston side which forms the back surface of the second leaf valve 3.

[0040] As described above, the laminated leaf valve V is formed by laminating the annular leaf valves 2, 3, and 4, and is laminated at the upper part in FIG. 2 on the expansion side chamber side of the piston 1 as a valve seat member, and is fixed to the outer periphery of the small diameter part 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, and deflection on the outer periphery side which is the free end is permitted. In this embodiment, the laminated leaf valve V includes a plurality of leaf valves which are annular and have an outer diameter smaller than that of the third leaf valve 4 and are laminated so as to gradually become smaller on the backs of the three leaf valves, the first leaf valve 2, the second leaf valve 3, and the third leaf valve 4, but at least the leaf valves laminated on the backs of the first leaf valve 2, the second leaf valve 3, and the third leaf valve 4 may be eliminated, or the number of laminated sheets may be changed.

[0041] Additionally, above the stacked leaf valve V in FIG. 2 are stacked a spacer 5 whose outer diameter is smaller than that of the uppermost leaf valve of the stacked leaf valve V, and a circular valve stopper 6 whose outer diameter is approximately equal to 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. 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.

[0042] When the stacked leaf valve V is stacked on the upper end of the piston 1 in Figure 2, the first leaf valve 2 at the bottom in Figure 2 abuts against the inner seat portion 1g and the seat portion 1e, closing the upper opening end in Figure 2, which is the outlet end of the compression side port 1c.

[0043] In addition, when the laminated leaf valve V receives the pressure of 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 and allows 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, and provides 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.

[0044] 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 from the axial direction. When the first leaf valve 2 is stacked on the upper end of the piston 1 in Fig. 2, each through hole 2a faces between the inner circumferential seat portion 1g and the seat portion 1e and communicates with the compression side port 1c. Note that a plurality of through holes 2a may be provided lined up in the circumferential direction.

[0045] Next, as shown in Fig. 3, the second leaf valve 3 is annular and includes three arc-shaped communication holes 3a 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, three notched passages 3b opening from the outer periphery which is the free end and leading to the center of the corresponding communication hole 3a, arm portions 3c formed on both sides of the notched passages 3b in the circumferential direction on the outer periphery of the communication hole 3a, and fragile portions 3d which reduce the rigidity of the arm portions 3c. As shown in Fig. 3, the third leaf valve 4 is annular and does not include any holes or the like.

[0046] When the second leaf valve 3 is stacked on the rear surface of the first leaf valve 2 on the side opposite the piston, and the third leaf valve 4 is stacked on the rear surface of the second leaf valve 3 on the side opposite the piston, 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 one of the through holes 2a of the first leaf valve 2 and communicates with the compression-side port 1c via the through hole 2a. In addition, the communication hole 3a is closed at the 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 3b. Furthermore, the notched passage 3b is closed at the top and bottom 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, the second leaf valve 3 and the third leaf valve 4 have the same outer diameter, the diameter 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 3b and the notched passage 3b functions as a choke by covering the top and bottom of the notched choke 3b. In this embodiment, the notched passage 3b functions as a choke, but may function as an orifice instead of a choke. In this embodiment, the communication hole 3a is arc-shaped, but may be linear as long as it is along the circumferential direction.

[0047] The arm portion 3c is formed on the outer periphery of the communication hole 3a on both sides of the notch passage 3b in the circumferential direction by providing a plurality of communication holes 3a that are provided at intervals in the circumferential direction in the second leaf valve 3 and notch passages 3b that open from the outer periphery of the second leaf valve 3 and communicate with the corresponding communication holes 3a. The arm portion 3c is on the outer periphery of the communication hole 3a and is in the range from the circumferential end of the communication hole 3a to the notch passage 3b, and the circumferential length varies depending on the circumferential length of the communication hole 3a. Therefore, the circumferential length of the arm portion 3c becomes longer by increasing the circumferential length of the communication hole 3a, and becomes shorter by decreasing the circumferential length of the communication hole 3a.

[0048] In the laminated leaf valve V of this embodiment, the second leaf valve 3 has notches 3e, 3e that open from both circumferential ends of the communication hole 3a and extend toward the outer periphery, which is the free end, and the notches 3e, 3e form a portion where the radial width of the arm 3c narrows on the outer periphery side of the communication hole 3a of the second leaf valve 3, and this portion functions as a weak portion 3d, reducing the bending configuration of the arm 3c. Thus, in this embodiment, the second leaf valve 3 has weak portions 3d formed by the notches 3e, 3e that lead to the communication hole 3a in each arm 3c. Therefore, the provision of the weak portions 3d makes it easier for the arm 3c to bend from the weak portion 3d on the cutout passage side, which is the tip. In the stacked leaf valve V of this embodiment, the cutout passage 3b is connected to the center of the communicating hole 3a, and arm portions 3c are formed on both circumferential sides of the cutout passage 3b at the outer periphery of the communicating hole 3a. However, the cutout passage 3b may be connected to the circumferential end of the communicating hole 3a and arm portion 3c may be provided on only one side of the cutout passage 3b in the circumferential direction. In that case, a weak portion 3d may be provided by providing a cutout 3e that opens on the opposite side of the communicating hole 3a to the cutout passage 3b in the circumferential direction.

[0049] Next, the extension-side leaf valve 7 is laminated below the piston 1 in FIG. 1. The extension-side leaf valve 7 is a laminated leaf valve formed by laminating a plurality of annular plates, and is laminated at the lower end of the piston 1 as a valve seat member in FIG. 2, and is fixed to the outer periphery of the small diameter part 11a of the rod 11 together with the piston 1. The inner periphery side of the lowermost annular plate of the extension-side leaf valve 7 is in contact with the inner periphery seat part 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 off the seat part 1d.

[0050] When the outer circumferential side of the expansion-side leaf valve 7 is seated on the seat portion 1d, it is in close contact with the inner circumferential seat portion 1f and the seat portion 1d, blocking the outlet end of the expansion-side port 1b that opens between the inner circumferential seat portion 1f and the seat portion 1d. When the free end is bent by pressure from the expansion-side port 1b side and separated from the seat portion 1d, it opens the expansion-side port 1b and provides resistance to the flow of liquid passing through the gap generated between the expansion-side leaf valve 7 and the seat portion 1d.

[0051] The valve stopper 6, spacer 5, stacked leaf valve V, piston 1 and extension side leaf valve 7 constructed in this manner are successively assembled to the outer periphery of the small diameter portion 11a 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 11d of the small diameter portion 11a, and the step portion 11c of the rod 11.

[0052] The laminated leaf valve V and the shock absorber D are configured as described above, and their operation will be described below. First, when the shock absorber D performs an expansion operation and the piston 1 moves upward in FIG. 1 relative to the cylinder 10, the liquid in the expansion-side chamber R1, which is compressed by the upward movement of the piston 1 in FIG. 1, bends the expansion-side leaf valve 7 and passes through the expansion-side port 1b and tries to move to the compression-side chamber R2. Also, during the expansion operation of the shock absorber D, the laminated leaf valve V closes and sits 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 3b, so that the liquid in the expansion-side chamber R1 can move to the compression-side chamber R2 through the choke formed by the notched passage 3b.

[0053] During the extension operation of the shock absorber D, when the piston speed is low and the pressure in the extension-side chamber R1 does not reach the opening pressure of the extension-side leaf valve 7, the liquid cannot pass through the extension-side port 1b because the extension-side port 1b is kept in a closed state by the extension-side leaf valve 7, and instead passes through the compression-side port 1c and the choke passage to move from the extension-side chamber R1 to the compression-side chamber R2.

[0054] Therefore, when the shock absorber D is expanding and the piston speed is low, the choke passage provides resistance to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2, and the shock absorber D generates a damping force that hinders the expansion operation.

[0055] On the other hand, during the extension operation of the shock absorber D, when the piston speed exceeds the low speed and becomes high speed, the pressure in the extension-side chamber R1 reaches the opening pressure of the extension-side leaf valve 7, so that the extension-side leaf valve 7 is bent and opens. 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, and moves from the extension-side chamber R1 to the compression-side chamber R2.

[0056] Therefore, when the shock absorber D is expanding and the piston speed is high, the expansion-side leaf valve 7 provides resistance to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2, and the shock absorber D generates a damping force that hinders the expansion operation.

[0057] As described above, when shock absorber D extends, if the piston speed is low, a damping force characteristic of a choke is generated, which is proportional 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 of increase in the damping force 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 extends, free piston 14 rises in FIG. 1 in accordance with the volume of rod 11 retracted from cylinder 10, expanding air chamber G, and the volume of rod 11 retracted from cylinder 10 is compensated for.

[0058] 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 pass through the compression-side port 1c to move to the expansion-side chamber R1.

[0059] In addition, 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 moves from the compression side chamber R2 to the expansion side chamber R1 through the compression side port 1c and the choke passage.

[0060] 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 expansion side chamber R1, and the shock absorber D generates a damping force that impedes the contraction operation.

[0061] On the other hand, when the shock absorber D is contracting, if the piston speed exceeds the low speed and becomes high speed, the pressure in the compression side chamber R2 reaches the opening pressure of the stacked leaf valve V, causing the stacked leaf valve V to bend and open. The liquid then passes through the compression side port 1c, and then passes between the stacked leaf valve V and the seat portion 1e, moving from the compression side chamber R2 to the expansion side chamber R1.

[0062] 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 impedes the contraction operation.

[0063] 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 rises in proportion to the piston speed, and if the piston speed is high, the rate at which the damping force increases with respect to the piston speed is smaller than at low speed, but a damping force characteristic of a leaf valve is generated in which the damping force rises in proportion to the piston speed. Note that as shock absorber D contracts, free piston 14 moves down in FIG. 1 in accordance with the volume of rod 11 entering cylinder 10, reducing air chamber G, and the volume of the rod 11 entering cylinder 10 is compensated for.

[0064] Here, a weak portion 3d is provided on the arm portion 3c formed on the outer periphery of the communication hole 3a of the second leaf valve 3 in the laminated leaf valve V, which is formed by a notch 3e that opens at the circumferential end of the communication hole 3a and extends toward the outer periphery, and reduces the rigidity of the arm portion 3c, so that the tip side of the arm portion 3c is easily bent starting from the weak portion 3d. Therefore, when the second leaf valve 3 is sandwiched between the first leaf valve 2 and the third leaf valve 4, the arm portion 3c can be closely attached to the first leaf valve 2 and the third leaf valve 4 according to the surfaces of the first leaf valve 2 and the third leaf valve 4, so that no gap is generated between the arm portion 3c and the first leaf valve 2 or the third leaf valve 4, and the communication hole 3a can be prevented from being communicated with the expansion-side chamber R1 through anything other than the choke passage. Therefore, when the piston speed during the expansion / contraction operation is low, the shock absorber D can generate a desired damping force by the choke passage.

[0065] 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 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 includes 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 is 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 is the back surface of the second leaf valve 3. The second leaf valve 3 includes a plurality of communication holes 3a which are provided at intervals in the circumferential direction and can communicate with the through hole 2a, a plurality of cutout passages 3b which open from the outer periphery which is the free end and lead to the corresponding communication holes 3a, and fragile portions 3d which reduce the rigidity of arms 3c which are formed on the outer periphery of the communication holes 3a and on both circumferential sides of the cutout passages 3b.

[0066] In the stacked leaf valve V configured in this manner, the arm portion 3c of the second leaf valve 3 has a fragile portion 3d that reduces the rigidity and is therefore easily bent and deformed, and can be tightly fitted to both the first leaf valve 2 and the third leaf valve 4 without creating a gap between them, thereby preventing the communication hole 3a from communicating with the expansion-side chamber R1 through anything other than the choke passage. Therefore, since the arm portion 3c has the fragile portion 3d, the second leaf valve 3 can be tightly fitted to both the first leaf valve 2 and the third leaf valve 4, and therefore the circumferential length of each communication hole 3a in the second leaf valve 3 can be narrowed.

[0067] Furthermore, narrowing the circumferential width of each communication hole 3a makes it possible to shorten the circumferential length W of the arm portion 3c, as shown in Fig. 3. In this manner, according to the stacked leaf valve V of this embodiment, since the circumferential length W of the arm portion 3c can be shortened, it is possible to prevent the arm portions 3c of adjacent second leaf valves 3,3 from becoming entangled when the second leaf valves 3 are transported or stored, and the effort required to separate the second leaf valves 3,3 is reduced, thereby reducing the workload when assembling the stacked leaf valve V. As described above, according to the stacked leaf valve V of this embodiment, it is possible to improve the ease of assembly and obtain good choke characteristics.

[0068] Since the notched passage 3b forming the choke passage is always communicated with the communication hole 3a, the arms 3c are formed on both sides of the notched passage 3b in the circumferential direction on the outer periphery of one communication hole 3a. However, even if the weak portion 3d is provided on only one of the pair of arms 3c, 3c on the outer periphery of one communication hole 3a, the one arm 3c can be deformed following the first leaf valve 2 and the third leaf valve 4, thereby increasing the degree of contact of the other arm 3c with the first leaf valve 2 and the third leaf valve 4. Therefore, the weak portion 3d may be provided on only one of the pair of arms 3c formed on both sides of the notched passage 3b on the outer periphery of one communication hole 3a. Moreover, the longer the length of the notch 3e is, the closer the tip of the notch 3e is to the outer periphery of the second leaf valve 3, the narrower the radial width of the weak portion 3d is, and the lower the rigidity is. Therefore, the rigidity of the weak portion 3d can be adjusted by the length of the notch 3e.

[0069] In the stacked leaf valve V of this embodiment, the fragile portion 3d is formed by a notch 3e that opens from the circumferential end of the communicating hole 3a and extends toward the outer periphery, which is the free end side of the arm portion 3c. With the stacked leaf valve V configured in this manner, the fragile portion 3d can be formed without affecting the shape of the inner and outer peripheries of the second leaf valve 3, so that even with the fragile portion 3d provided, a worker assembling the stacked leaf valve V can perform the assembly work without feeling any discomfort.

[0070] In addition, in order to form the fragile portion 3d in the second leaf valve 3, other than providing a notch 3e opening into the circumferential end of the communicating hole 3a, as in the first modified example of the stacked leaf valve V shown in Figure 4, a communicating hole 3a having a wider radial width at its circumferential end in the second leaf valve 3 may be provided, thereby narrowing the radial width of the base end portion of the arm portion 3c1 on the outer periphery of the communicating hole 3a, and the base end portion of the arm portion 3c1 may be made into the fragile portion 3d1.

[0071] Also, the fragile portion 3d2 may be formed by a notched groove 3f that opens from the outer periphery that is the free end of the arm portion 3c and extends toward the end of the communication hole 3a in the circumferential direction, as in the second modified example of the laminated leaf valve V shown in FIG. 5. According to the laminated leaf valve V configured in this manner, the second leaf valve 3 is provided with the notched groove 3f to form the fragile portion 3d2, and the rigidity of the arm portion 3c can be reduced, so that the desired choke characteristics can be obtained, and the entanglement of the arm portions 3c can be suppressed, so that the ease of assembly can be improved. The notched groove 3f may be provided so that the tip does not communicate with the communication hole 3a and the through hole 2a of the first leaf valve 2 when the second leaf valve 3 is viewed from the axial direction. Since the notched groove 3f is provided at a position that does not communicate with the through hole 2a, it is sufficient to avoid the notched passage 3b and the communication hole 3a, so that the design freedom of the opening location and shape for the second leaf valve 3 is high, and tuning of the rigidity of the arm portion 3c is also easy.

[0072] Furthermore, the fragile portion 3d3 may be formed by a hole 3g provided in the arm portion 3c, as in the third modified example of the stacked leaf valve V shown in Fig. 6. According to the stacked leaf valve V configured in this manner, the fragile portion 3d can be formed without affecting the shape of the inner and outer periphery of the second leaf valve 3, so that even if the fragile portion 3d is provided, the worker assembling the stacked leaf valve V can perform the assembly work without feeling uncomfortable. Furthermore, since the rigidity of the arm portion 3c can be easily adjusted by adjusting the number of holes 3g provided in one arm portion 3c and the opening area, tuning of the rigidity of the arm portion 3c is also easy.

[0073] The shock absorber D of this embodiment includes a cylinder (outer tube) 10, a rod 11 inserted axially movably into the cylinder (outer tube) 10, a piston (valve seat member) 1 that is accommodated in the cylinder (outer tube) 10 and divides an expansion side chamber (operating chamber) R1 and a compression side chamber (operating chamber) R2 in the cylinder (outer tube) 10 and 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 the ease of assembly and obtain good choke characteristics.

[0074] In addition, in the example shown in Fig. 1, the two working chambers are the expansion side chamber R1 and the compression side chamber R2, the laminated leaf valve V is provided above the piston 1 as the valve seat member in Fig. 1, and the laminated leaf valve V is used as a valve that generates a damping force on the compression side, 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 double-tube shock absorber that has an outer shell as an outer tube on the outer periphery of the cylinder and a reservoir between the cylinder and the outer shell, the valve case that separates the compression side chamber and the reservoir may be used as the valve seat member, and the laminated leaf valve V may be provided to open and close the port of the valve case.

[0075] Furthermore, as described above, the stacked leaf valve V is configured so as to open outward, with the inner periphery as a fixed end, the inner periphery fixed to the small diameter portion 11a of the rod 11, and the outer periphery as a free end, allowing bending on the free end side, but the stacked leaf valve V may be configured so as to open inward, with the outer periphery as a fixed end, the inner periphery as a free end, allowing bending on the inner periphery side. When the stacked leaf valve V is configured to open inward in this manner, the outer diameters of the stacked leaf valves V may be unified, the outer periphery of the stacked leaf valve V may be fixed immovably to the valve seat member, and the notched passage may be opened from the inner periphery, which is the free end of the stacked leaf valve V, to communicate with the communication hole.

[0076] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0077] Reference Signs List 1 piston (valve seat member), 1c pressure side port (port), 2 first leaf valve, 2a through hole, 3 second leaf valve, 3a communication hole, 3b notch passage, 3c hole, 3d, 3d1 arm, 3d, 3d1, 3d2, 3d3 weak part, 3e notch, 3f notch groove, 3g hole, 4 third leaf valve, 10 cylinder (outer tube), 11 rod, D shock absorber, V laminated leaf valve, R1 expansion side chamber (operating chamber), R2 compression side chamber (operating chamber)

Claims

1. A laminated leaf valve having an annular shape with an inner periphery or an outer periphery as a free end, allowing the free end side to bend, and laminated on a valve seat member having a port to open and close the port, a first leaf valve having an annular shape and a through hole communicating with the port; a second leaf valve having an annular shape and overlapping a side surface of the first leaf valve opposite the valve seat, the side surface being a back surface of the first leaf valve; a third leaf valve having an annular shape and overlapping a side surface opposite to the valve seat that serves as a back surface of the second leaf valve, The second leaf valve is a plurality of communication holes provided at intervals in a circumferential direction and capable of communicating with the through hole; a plurality of notched passages each opening from the free end and communicating with a corresponding one of the communication holes; a weakened portion that reduces the rigidity of an arm portion formed on at least one side of the circumferential direction of the notched passage at an outer periphery of the communication hole; 1. A laminated leaf valve comprising:

2. The fragile portion is formed by a notch that opens from a circumferential end of the communication hole and extends toward the free end of the arm portion.

2. The laminated leaf valve of claim 1.

3. The weakened portion is formed by a notched groove that opens from the free end side of the arm portion and extends toward the end of the communication hole in the circumferential direction.

2. The laminated leaf valve of claim 1.

4. The weakened portion is formed by a hole provided in the arm portion.

2. The laminated leaf valve of claim 1.

5. Outer tube and a rod inserted into the outer tube so as to be movable in an axial direction; a valve seat member housed within the outer tube to define two working chambers within the outer tube and having a port; and a laminated leaf valve according to any one of claims 1 to 4 laminated to the valve seat member. A shock absorber characterized by:

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