Damping valves and shock absorbers

Abstract

To provide an attenuation valve which can shorten a manufacturing time, can reduce a cost, is easy in dimension management, and has no troublesomeness at the tuning of valve-opening pressure, and a damper.SOLUTION: An attenuation valve V comprises: a valve seat member 5 having a port 5c, and a valve seat 5e erecting from an external periphery of an opening end of the port 5c, and surrounding the port 5c; a leaf valve 11 which can approach and separate from the valve seat member 5, and is seated on and separated from the valve seat 5e; a small-sized shim 12 which can approach and separate from the valve seat member 5, and is smaller than the leaf valve 11 in a contour; a disc 13 which can approach and separate from the valve seat member 5, has a disc-side port 13a penetrating in an axial direction within a range at an internal peripheral side rather than an external periphery of the leaf valve 11 when viewed from an axial direction, and is overlapped on an anti-valve seat member side of the shim 12; and a spring member 14 arranged at the anti-valve seat member side of the disc 13, and energizing the disc 13, the shim 12 and the leaf valve 11 toward the valve seat member 5.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] The damping valve is used for a base valve part or the like of a shock absorber used in a vehicle suspension or the like. Such a damping valve includes, for example, an annular valve case having a port that partitions between a pressure chamber and a reservoir partitioned in the shock absorber and communicates the pressure chamber and the reservoir, and an annular valve seat surrounding the outer periphery of the port; a cylindrical guide rod inserted on the inner peripheral side of the valve case; an annular leaf valve laminated axially movably on the valve case to open and close the port; a disk that is annular and slidably mounted on the outer periphery of the guide rod, is axially movable with respect to the valve case, and has a support projection that supports the inner periphery on the side opposite to the valve case of the leaf valve; a spring receiver that houses the leaf valve and the disk and includes a top portion and a plurality of leg portions that hang down from the outer periphery of the top portion and are fitted to the outer periphery of the valve case; and a coil spring interposed between the top portion of the spring receiver and the disk to urge the leaf valve together with the disk toward the valve case (see, for example, Patent Document 1).

[0003] Then, with respect to the flow of hydraulic oil from the reservoir toward the pressure chamber, the leaf valve and the disk compress the coil spring and separate from the valve case, thereby opening the port.

[0004] Conversely, with respect to the flow of hydraulic oil from the pressure chamber toward the reservoir, the hydraulic oil attempting to pass through the hole of the disk pushes and deflects the inner peripheral side of the leaf valve toward the valve case side, and the leaf valve separates from the support projection, so that the hydraulic oil passes through the gap formed between the leaf valve and the support projection. The damping valve generates a damping force by providing resistance to the flow of the hydraulic oil passing through the gap formed between the leaf valve and the support projection.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2005-69422 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the damping valve described above, the disc is provided with an annular support projection to support the inner circumference of the leaf valve, and the surface of the support projection that contacts the inner circumference of the leaf valve is higher than the surface of the disc that contacts the outer circumference of the leaf valve by the height of the support projection.

[0007] Therefore, when the disc moves toward the valve case due to the pressure in the compression chamber, the inner circumference of the leaf valve flexes due to the support projection. This flexing of the leaf valve causes it to exert a restoring force, setting the opening pressure at which the leaf valve opens the hole in the disc. Thus, in conventional damping valves, the opening pressure at which the leaf valve opens the hole in the disc is set by the height of the support projection.

[0008] Thus, the disc has a special shape with support protrusions on its inner circumference, and can only be manufactured by machining, which is time-consuming and costly. During machining, dimensional accuracy of the height of the support protrusions is required, and discs with different support protrusions must be manufactured each time to tune the opening pressure of the leaf valve.

[0009] In short, conventional damping valves were time-consuming and costly to manufacture, required precise dimensional control, and posed the cumbersome task of manufacturing discs with support protrusions of varying heights each time the valve opening pressure needed tuning.

[0010] Therefore, the present invention aims to provide a damping valve and a shock absorber utilizing this damping valve that enable shortening of manufacturing time and cost reduction, facilitate dimensional control, and eliminate the hassle of tuning the valve opening pressure. [Means for solving the problem]

[0011] To achieve the above objective, the damping valve of the present invention comprises a valve seat member having a port and an annular valve seat rising from the outer circumference of the opening end of the port and surrounding the port; an annular leaf valve that is movable toward and toward the valve seat member and seats toward and away from the valve seat; a shim that is movable toward and toward the valve seat member and is superimposed on the side of the leaf valve opposite the valve seat member, and whose outer shape is smaller than that of the leaf valve; a disc that is movable toward and toward the valve seat member and has a disc-side port that penetrates axially in a range on the inner circumference side of the leaf valve when viewed from the axial direction, and is superimposed on the side of the shim opposite the valve seat member; and a spring member that is positioned on the side of the disc opposite the valve seat member and biases the disc, shim, and leaf valve toward the valve seat member.

[0012] In this type of damping valve, the leaf valve is given initial deflection by stacking shims on the disc. Therefore, there is no need to provide support protrusions on the disc itself to give initial deflection to the leaf valve, simplifying the shape of the disc, and allowing adjustment of the leaf valve opening pressure by replacing shims of different thicknesses.

[0013] Furthermore, the valve seat side end of the disc in the damping valve may be flat, and a damping valve configured in this way can be manufactured at a lower cost.

[0014] Furthermore, the damping valve may include a guide member that is axial in shape and extends axially relative to the valve seat member, with a shim and a disc mounted on its outer circumference so as to be axially slidable, and the shim may have a notch on its inner circumference that forms a gap between it and the guide member. With a damping valve configured in this way, even if the shim is not fixed to the disc, communication between the disc-side ports can be ensured by the notch when the inner circumference of the leaf valve flexes and the valve opens. In addition, with a shock absorber configured in this way, processing to fix the shim and disc and surface processing of the shim are unnecessary, so costs can be reduced even further.

[0015] Furthermore, the damping valve includes a spring receiver having an annular top and a plurality of legs hanging down from the outer circumference of the top, with the lower ends of the legs fitted onto the outer circumference of the valve seat member. The spring member is interposed between the top of the spring receiver and the disc, and the end of the spring member opposite the valve seat member abuts against the top and legs of the spring receiver. The end of the disc opposite the valve seat member may be flat. With a damping valve configured in this way, the spring member is centered by abutting against the top and legs of the spring receiver, so even if the end of the disc opposite the valve seat member is flat, the spring member can apply a stable biasing force to the disc without axial misalignment. Therefore, with a damping valve, it is not necessary to provide fitting parts or the like on the disc to prevent axial misalignment of the spring member, and the shape of the end of the disc opposite the valve seat member is also simplified, making disc processing easier and reducing manufacturing costs.

[0016] Furthermore, the shock absorber comprises a shock absorber body having an outer shell, a rod inserted into the outer shell so as to be movable in the axial direction, and two working chambers through which liquid flows as the rod moves relative to the outer shell, and a damping valve provided between the working chambers. With a shock absorber configured in this way, costs can be reduced because it is equipped with a damping valve that can be manufactured at low cost, and the damping force can be easily tuned by replacing shims. [Effects of the Invention]

[0017] The valves and buffers of the present invention not only enable shorter manufacturing times and lower costs, but also facilitate dimensional control and eliminate the hassle of tuning the valve opening pressure. [Brief explanation of the drawing]

[0018] [Figure 1] This is a cross-sectional view of a shock absorber to which a damping valve according to one embodiment is applied. [Figure 2] This is an enlarged cross-sectional view of a piston portion to which a damping valve of one embodiment is applied. [Figure 3] This is a plan view of a shim in a damping valve according to one embodiment. [Modes for carrying out the invention]

[0019] Hereinafter, the valve and shock absorber of the present invention will be described based on the drawings. In one embodiment, the damping valve V is used as the damping valve of the piston portion of the shock absorber D as shown in FIG. 1.

[0020] Hereinafter, each part of the damping valve V and the shock absorber D will be described in detail. The shock absorber D includes a shock absorber body 1 having an outer shell 2 and a rod 3 movably inserted axially into the outer shell 2, and a damping valve V provided between a extending chamber R1 and a compression chamber R2 which are two working chambers formed in the shock absorber body 1.

[0021] The shock absorber body 1 includes a cylinder 4, a piston 5 movably inserted into the cylinder 4 and partitioning the inside of the cylinder 4 into the extending chamber R1 and the compression chamber R2, a rod 3 inserted into the cylinder 4 and connected to the piston 5, and an outer shell covering the cylinder 4 and forming a reservoir chamber R between itself and the cylinder 4.

[0022] The cylinder 4 is cylindrical, and the piston 5 is movably inserted therein as described above. The extending chamber R1 is partitioned above the piston 5 in FIG. 1, and the compression chamber R2 is partitioned below the piston 5 in FIG. 1. The extending chamber R1 and the compression chamber R2 are filled with a liquid, specifically, for example, hydraulic oil. In addition to hydraulic oil, water, aqueous solution, etc. may be filled as the liquid.

[0023] Further, the cylinder 4 is housed in a bottomed cylindrical outer shell 2 disposed on the outer peripheral side, and a reservoir chamber R is formed in the annular gap between the cylinder 4 and the outer shell 2. In this case, the reservoir chamber R is filled with hydraulic oil and gas. When the liquid is hydraulic oil, an inert gas such as nitrogen may be used as the gas to prevent deterioration of the hydraulic oil.

[0024] Furthermore, a valve case 6 is fitted to the lower end of cylinder 4 in Figure 1, and the valve case 6 separates the compression chamber R2 from the reservoir chamber R. Also, a rod guide 8 is fitted to the upper end of cylinder 4 in Figure 1, which slidably supports the rod 3. This rod guide 8 is fitted to the inner circumference of the outer shell 2 and crimps the upper end of the outer shell 2. ,a The rod guide 8 is fixed to the outer shell 2. When the rod guide 8 is fixed to the outer shell 2 in this way, the cylinder 4 is sandwiched between the valve case 6, which is placed on the bottom of the outer shell 2, and the rod guide 8, and the cylinder 4 is fixed together with the valve case 6 within the outer shell 2. Alternatively, instead of crimping the upper opening of the outer shell 2, a cap may be screwed onto the upper opening, and the rod guide 8, cylinder 4, and valve case 6 may be sandwiched between this cap and the bottom of the outer shell 2, thereby fixing these components within the outer shell 2.

[0025] The piston 5 is annular and, as shown in Figures 1 and 2, serves as a valve seat member in the damping valve V and is fixed to the lower end in Figure 1, which is one end of the rod 3. The piston 5 as a valve seat member comprises an annular base 5a, a cylindrical portion 5b provided on the outer circumference of the base 5a and sliding against the inner circumference of the cylinder 4, ports 5c provided at equal intervals on the same circumference as the base 5a and passing through the base 5a axially to connect the extension chamber R1 and the compression chamber R2, annular windows 5d provided on the upper end side of the base 5a in Figure 2 and leading to the open ends of each port 5c, and an annular valve seat 5e rising from the outer circumference side of the base 5a above the open ends of the ports 5c in Figure 2 and surrounding each port 5c.

[0026] Multiple ports 5c are provided on the piston 5, and each is positioned on the same circumference centered on the center of the piston 5. The number of ports 5c is arbitrary and may be one.

[0027] Furthermore, the annular window 5d is formed in an annular recess provided in the base 5a and is connected to each port 5c. The annular window 5d is formed with a width from the inner circumference of each port 5c to the outer circumference of each port 5c, and the depth of the portion of the annular window 5d on the inner circumference of each port 5c is deeper than the portion directly facing each port 5c. In this embodiment, the valve seat 5e is an annular shape and rises from the outer circumference of the annular window 5d, which is at the upper end of the piston 5 in Figure 2 and is connected to the opening end of the port 5c, surrounding the outer circumference of the port 5c. However, it may also be a petal-shaped valve seat that independently surrounds each of the ports 5c.

[0028] Furthermore, as shown in Figure 2, a piston ring 10 is fitted into an annular groove 5b1 provided on the outer circumference of the cylindrical portion 5b, which slides against the inner circumference of the cylinder 4 to seal the space between the outer circumference of the piston 5 and the inner circumference of the cylinder 4.

[0029] The damping valve V comprises a piston 5 with a port 5c as a valve seat member, an annular leaf valve 11 that is movable toward and toward the piston 5 and seats toward and away from the valve seat 5e, a circular shim 12 that is movable toward and toward the piston 5 and is superimposed on the side of the leaf valve 11 opposite the valve seat member and has an outer diameter smaller than that of the leaf valve 11, and a circular disk-side port 13a that is movable toward and toward the piston 5 and penetrates axially in a range that is more outer than the outer circumference of the shim 12 and more inner than the outer circumference of the leaf valve 11 when viewed from the axial direction. The device includes a disc 13 that is superimposed on the side of the shim 12 opposite the valve seat member, a spring member 14 positioned on the side of the disc 13 opposite the valve seat member and biasing the disc 13, shim 12, and leaf valve 11 toward the piston 5, a cylindrical spring receiver 15 that fits onto the outer circumference of the base 5a of the piston 5 and houses the leaf valve 11, shim 12, disc 13, and spring member 14, and a shaft-shaped guide member 16 that extends axially relative to the piston 5 and on which the shim 12 and disc 13 are mounted so as to be slidable in the axial direction.

[0030] The guide member 16 comprises a cylindrical guide tube 16a and a flange 16b provided on the outer circumference of the upper end of the guide tube 16a in Figure 2. In this embodiment, the guide member 16 is superimposed on the piston 5 and rises vertically, with the lower end of the guide tube 16a abutting against the upper end in Figure 2, which is on the inner circumference of the base 5a of the piston 5, beyond the port 5c and annular window 5d. The guide member 16 functions as a guide that positions the shim 12 and disk 13, which are mounted on the outer circumference of the guide tube 16a, in the radial direction and guides their movement in the axial direction.

[0031] The leaf valve 11 is configured as a laminated leaf valve formed from multiple annular plates. The inner diameter of each annular plate constituting the leaf valve 11 is larger than the outer diameter of the guide cylinder 16a of the guide member 16 and the inner diameter of the annular window 5d, and the outer diameter of each annular plate is larger than the inner circumference of the upper end surface of the valve seat 5e of the piston 5. In addition, the leaf valve 11 is movable in the axial direction and can be moved closer to or further away from the piston 5.

[0032] Furthermore, when the leaf valve 11 is placed on the piston 5, its outer circumference can seat on the valve seat 5e, and the outer circumference seated on the valve seat 5e acts as a fulcrum, allowing for downward deflection toward the inner side of the piston 5 in Figure 2. The base 5a of the piston 5 is provided with an annular recessed annular window 5d, and the depth of the portion of the annular window 5d on the inner side of the port 5c is greater. As described above, when the inner circumference of the leaf valve 11 deflects toward the piston 5, the inner circumference of the leaf valve 11 comes into contact with the base 5a of the piston 5, preventing the leaf valve 11 from blocking the port 5c.

[0033] The number of annular plates constituting the leaf valve 11 can be arbitrarily changed according to the desired damping force, and the leaf valve 11 may be composed of a single annular plate.

[0034] The shim 12 is annular in shape, with an inner diameter set to allow sliding contact with the outer circumference of the guide cylinder 16a, and an outer diameter set to be larger than the inner diameter of the leaf valve 11. Therefore, when the shim 12 is placed on the leaf valve 11, its outer circumference abuts against the inner circumference of the side of the leaf valve 11 opposite the piston, thereby supporting the inner circumference of the leaf valve 11. Furthermore, as shown in Figure 3, the shim 12 has three notches 12a on its inner circumference, which slide against the outer circumference of the guide cylinder 16a of the guide member 16, allowing it to move axially toward and away from the piston 5 while being guided by the guide cylinder 16a. The diameter of the circle passing through the outer circumference of the notches 12a is smaller than the inner diameter of the leaf valve 11. In this embodiment, three protrusions 12b are formed between the notches 12a on the inner circumference of the shim 12, and the tips of the protrusions 12b that slide against the outer circumference of the guide cylinder 16a are arc-shaped. In this embodiment, the inner diameter of the shim 12 is the diameter of the circle passing through the tips of the protrusions 12b. By widening the circumferential width of the notch 12a and forming an arc-shaped protrusion 12b on the inner circumference of the shim 12, the protrusion 12b is brought into sliding contact with the outer circumference of the guide cylinder 16a, allowing the shim 12 to move smoothly in the axial direction relative to the guide cylinder 16a. The number of notches 12a provided on the inner circumference of the shim 12, their circumferential width, and the locations of the shim 12 in the circumferential direction can be arbitrarily modified in the design. Furthermore, the shim 12 does not have to be annular; it can be any shape as long as radial alignment is possible, and the outer shape of the shim 12 is smaller than the leaf valve 11, and it is sufficient that the shape ensures communication between the port 5c and the disk-side port 13a (described later) through the gap between the shim 12 and the leaf valve 11 when the leaf valve 11 is deflected.

[0035] The disc 13 has an annular shape with a thicker wall than the flat shim 12, both on the piston-side end face which is the lower end face in Figure 2 and on the opposite side which is the anti-piston side face which is the upper end face in Figure 2. It has multiple disc-side ports 13a that penetrate the wall thickness in a range that is further outward than the outer circumference of the shim 12 and further inward than the outer circumference of the leaf valve 11 when viewed from the axial direction. In this embodiment, the disc-side ports 13a are provided at equal intervals on the same circumference centered on the center of the disc 13, but the number of disc-side ports 13a can be arbitrarily changed and may be just one.

[0036] Furthermore, the disc 13 is slidably mounted on the outer circumference of the guide cylinder 16a of the guide member 16, and can move axially toward or away from the piston 5 while being guided by the guide cylinder 16a. Also, the disc 13 does not have to be annular, and can be any shape as long as radial alignment is possible.

[0037] The spring retainer 15 comprises an annular top portion 15a and a plurality of arc-shaped legs 15b extending circumferentially from the outer circumference of the top portion 15a toward the piston 5 at equal intervals. In Figure 2, the lower end of each leg 15b is fitted to the outer circumference of the base portion 5a of the piston 5, while the top portion 15a is fitted to the outer circumference of the guide cylinder 16a and its upper end abuts against the lower end of the flange 16b. The leaf valve 11, shim 12, disc 13, and spring member 14 are housed on the inner circumference of each leg 15b of the spring retainer 15. The diameter of the circle passing through the inner circumference of each leg 15b is slightly larger than the outer diameter of the leaf valve 11, and each leg 15b faces the outer circumference of the leaf valve 11 with a gap between them. Therefore, the spring retainer 15 centers the leaf valve 11 so that it does not deviate radially from the valve seat 5e even when the leaf valve 11 repeatedly moves axially away from the piston 5. Furthermore, the diameter of the circle passing through the inner circumference of each leg portion 15b is larger than the outer diameter of the disc 13, so the spring retainer 15 does not obstruct the axial movement of the disc 13.

[0038] The spring member 14 is a coil spring with a larger diameter on the side opposite the piston 5 (downward side) than on the side opposite the piston (upward side), and is interposed in a compressed state between the top 15a of the spring receiver 15 and the disc 13. Therefore, the spring member 14 biases the disc 13, shim 12, and leaf valve 11 toward the piston 5. The end of the spring member 14 opposite the piston (upper end in Figure 2) abuts against both the top 15a and leg 15b of the spring receiver 15, so the spring member 14 is positioned radially by the spring receiver 15. Therefore, even without providing a fitting portion on the disc 13 side that fits into the lower end of the spring member 14 in Figure 2, the spring member 14 can provide a stable biasing force to the disc 13 without radial displacement.

[0039] The damping valve V configured in this way is assembled in the following order on the outer circumference of the small-diameter portion 3a provided at the tip of the rod 3: guide member 16, spring receiver 15, spring member 14, disc 13, shim 12, leaf valve 11, and piston 5. It is then fixed to the rod 3 by being sandwiched between the piston nut 17 screwed onto the tip of the small-diameter portion 3a and the stepped portion 3b formed at the end of the small-diameter portion 3a of the rod 3. Note that the guide member 16, spring receiver 15, spring member 14, disc 13, shim 12, leaf valve 11, and piston 5 may be temporarily assembled into an assembly before being assembled to the outer circumference of the small-diameter portion 3a of the rod 3.

[0040] As described above, when biased by the spring member 14 and there is no other pressure load, the disc 13 comes into contact with the shim 12, the shim 12 comes into contact with the inner circumference of the leaf valve 11, and the outer circumference of the leaf valve 11 sits on the valve seat 5e of the piston 5. In this state, the contact between the disc 13 and the shim 12, and the contact between the shim 12 and the leaf valve 11, cuts off communication between the port 5c of the piston 5 and the disc-side port 13a of the disc 13, causing the damping valve V to close.

[0041] Furthermore, when the leaf valve 11, shim 12, and disc 13 move upward in Figure 2 away from the piston 5, and the leaf valve 11 moves away from the valve seat 5e, the damping valve V creates a gap between the leaf valve 11 and the valve seat 5e, opening port 5c. In this state, when the damping valve V is open, port 5c, which is in communication with the compression chamber R2, is connected to the extension chamber R1 through the gap between the legs 15b, 15b of the spring receiver 15.

[0042] Furthermore, when the leaf valve 11, shim 12, and disc 13 are pressed toward the piston 5 due to the pressure on the extension chamber R1 side, the inner circumference of the disc 13 Sim Because the shims 12 are stacked, there is a difference in level (height) between the disc 13, which the outer circumference of the leaf valve 11 abuts against, and the shim 12, which the inner circumference of the leaf valve 11 abuts against. As a result, the leaf valve 11 flexes its inner circumference by the thickness of the shim 12 while its outer circumference is sandwiched between the disc 13 and the valve seat 5e. When the inner circumference of the leaf valve 11 flexes by the thickness of the shim 12, it exerts a biasing force that tries to push the shim 12 and disc 13 upward in Figure 2, away from the piston 5, due to its own restoring force. Therefore, unless the force pushing the inner circumference of the leaf valve 11 downward in Figure 2 due to the pressure of the hydraulic fluid trying to pass through the disc-side port 13a overcomes the biasing force of the leaf valve 11, the leaf valve 11 will not separate from the shim 12 and will maintain the shim 12 in close contact with the disc 13. Then, when the pressure of the hydraulic fluid attempting to pass through the disc-side port 13a pushes the inner circumference of the leaf valve 11 downward in Figure 2, and overcomes the biasing force of the leaf valve 11, the inner circumference of the leaf valve 11 bends, creating a gap between the shim 12 and the leaf valve 11 or between the shim 12 and the disc 13, causing the damping valve V to open and connect the disc-side port 13a and port 5c. Even if the shim 12 sticks to the leaf valve 11 and displaces together with the leaf valve 11, the inner circumference of the shim 12 is provided TaSince a flow path is formed between the notch 12a and the guide cylinder 16a, when the inner circumference of the leaf valve 11 is deflected and the damping valve V opens, the disk-side port 13a and port 5c can be reliably connected. Furthermore, when pressure is received from the disk-side port 13a, as described above, the shim 12 gives the leaf valve 11 an initial deflection, so the opening pressure of the leaf valve 11 can be adjusted by adjusting the thickness (height) of the shim 12.

[0043] Next, the valve case 6 is fitted to the lower end of the cylinder 4 and separates the pressure chamber R2 inside the cylinder 4 from the reservoir chamber R formed between the cylinder 4 and the outer shell 2. The valve case 6 is equipped with a pressure damping passage 6a and a suction passage 6b that connect the pressure chamber R2 and the reservoir chamber R. Furthermore, at the reservoir chamber side end, which is the lower end in Figure 1 of the valve case 6, there is a pressure leaf valve 20 that opens and closes the pressure damping passage 6a and provides resistance to the flow of hydraulic fluid passing through the pressure damping passage 6a. At the pressure chamber side end, which is the upper end in Figure 1 of the valve case 6, there is a check valve 21 that opens and closes the suction passage 6b and allows only the flow of hydraulic fluid from the reservoir chamber R to the pressure chamber R2 through the suction passage 6b.

[0044] The shock absorber D is configured as described above, and the operation of the shock absorber D will be explained below. First, when the rod 3 moves upward relative to the cylinder 4 in Figure 1 and the shock absorber D extends, the piston 5 also moves upward relative to the cylinder 4 together with the rod 3, compressing the extension chamber R1 and expanding the compression chamber R2. As the extension chamber R1 is compressed, the pressure inside the extension chamber R1 increases, and the disc 13, shim 12, and leaf valve 11 in the damping valve V are pressed toward the piston 5 by the pressure of the extension chamber R1 transmitted into the spring receiver 15. Then, as described above, the outer circumference of the leaf valve 11 is sandwiched between the disc 13 and the valve seat 5e, and the inner circumference of the leaf valve 11 is deflected downward by the thickness of the shim 12, giving the leaf valve 11 an initial deflection.

[0045] When the pressure in the extension chamber R1 does not reach the opening pressure of the leaf valve 11, the inner circumference of the leaf valve 11 contacts the shim 12, causing the shim 12 to be in close contact with the disk 13, thus maintaining the leaf valve 11 in a closed state at the disk-side port 13a. On the other hand, when the pressure in the extension chamber R1 exceeds the opening pressure of the leaf valve 11, the inner circumference of the leaf valve 11 bends more than the thickness of the shim 12, causing the damping valve V to open.

[0046] When the damping valve V opens, if the leaf valve 11 separates from the shim 12, creating a gap between them, the hydraulic fluid that has passed through the disc-side port 13a flows through the gap between the shim 12 and the leaf valve 11 to the port 5c of the piston 5, and then flows into the compression chamber R2. Because the leaf valve 11 resists this flow of hydraulic fluid, the pressure in the extension chamber R1 becomes higher than the pressure in the compression chamber R2, and the shock absorber D generates a damping force that suppresses extension.

[0047] Furthermore, when the damping valve V opens, if the shim 12 separates from the disc 13 together with the leaf valve 11, a gap will be created between the shim 12 and the disc 13. As a result, the hydraulic fluid that has passed through the disc-side port 13a passes through the gap and then flows through the notch 12a on the inner circumference of the shim 12 towards the port 5c provided on the piston 5, and then into the compression chamber R2. Because the leaf valve 11 provides resistance to this flow of hydraulic fluid, the pressure in the extension chamber R1 becomes higher than the pressure in the compression chamber R2, and the shock absorber D generates a damping force that suppresses the extension operation.

[0048] Thus, in the damping valve V of this embodiment, since the shim 12 is not fixed to the disk 13, if the shim 12 is attracted to the disk 13, when the leaf valve 11 bends, a gap is created between the shim 12 and the leaf valve 11, and the disk-side port 13a and port 5c are connected through the gap between the shim 12 and the leaf valve 11. On the other hand, if the shim 12 is attracted to the leaf valve 11, when the leaf valve 11 bends, the shim 12 and the leaf valve 11 may move together and separate from the disk 13. If the shim 12 is simply an annular shape and its inner circumference slides against the outer circumference of the guide cylinder 16a of the guide member 16 over its entire circumference, when the shim 12 and the leaf valve 11 move together and separate from the disk 13, the shim 12 and the leaf valve 11 will block the flow path from the disk-side port 13a to port 5c. In contrast, the damping valve V of this embodiment is provided with a notch 12a on the inner circumference of the shim 12, and a flow path is formed between the shim 12 and the guide cylinder 16a by the notch 12a. Therefore, even if the shim 12 and the leaf valve 11 move together and separate from the disk 13, the disk-side port 13a and port 5c are reliably in communication.

[0049] Furthermore, if the shim 12 is fixed to the disk 13, or if the surface of the shim 12 facing the leaf valve 11 is made rougher to prevent the shim 12 from adhering to the leaf valve 11, then the blockage of the flow path when the damping valve V is opened can be prevented without providing a notch 12a on the inner circumference of the shim 12. In other words, by providing a notch 12a on the inner circumference of the shim 12, the advantage of preventing blockage of the flow path can be enjoyed without requiring the shim 12 to be fixed to the disk 13 or surface processing.

[0050] Furthermore, when the shock absorber D extends, the rod 3 retracts from inside the cylinder 4, resulting in a shortage of hydraulic fluid within the cylinder 4 equivalent to the volume of the retracted rod 3. This shortage of hydraulic fluid is supplied to the cylinder 4 from the reservoir chamber R when the check valve 21 installed in the valve case 6 opens. The opening pressure of the check valve 21 is set to a very low level to ensure that the pressure inside the cylinder 4 does not fall below atmospheric pressure.

[0051] Next, when the rod 3 moves downward relative to the cylinder 4 in Figure 1 and the shock absorber D contracts, the piston 5 also moves downward relative to the cylinder 4 along with the rod 3, compressing the compression chamber R2 and expanding the extension chamber R1. As the compression of the compression chamber R2 increases, the pressure inside the compression chamber R2 rises, and the disc 13, shim 12, and leaf valve 11 in the damping valve V are pushed away from the piston 5 by the pressure of the compression chamber R2 acting through the port 5c. As mentioned above, the leaf valve 11 is biased by the spring member 14 and seats on the valve seat 5e, closing the port 5c. However, when the force pushing up the disc 13, shim 12, and leaf valve 11 by the pressure of the compression chamber R2 overcomes the biasing force of the spring member 14, the spring member 14 is compressed and moves away from the valve seat 5e, moving upward in Figure 2.

[0052] When the leaf valve 11 separates from the valve seat 5e of the piston 5, a gap is formed between the leaf valve 11 and the valve seat 5e, and the hydraulic fluid in the compression chamber R2 passes through the port 5c and the gap between the leaf valve 11 and the valve seat 5e, and moves to the extension chamber R1 through the gap between the legs 15b, 15b of the spring support 15. In the damping valve V of this embodiment, the biasing force of the spring member 14 is made very small, so the resistance that the damping valve V exerts on the flow of hydraulic fluid when the leaf valve 11 lifts from the piston 5 and opens is extremely small, and the pressure difference between the compression chamber R2 and the extension chamber R1 is also small.

[0053] When the shock absorber D retracts, the rod 3 enters the cylinder 4, resulting in an excess of hydraulic fluid in the cylinder 4 equivalent to the volume of the rod 3 that enters the cylinder 4. This excess hydraulic fluid is discharged into the reservoir chamber R via the pressure-side damping passage 6a when the pressure-side leaf valve 20, located in the valve case 6, opens. The pressure-side leaf valve 20 resists the flow of hydraulic fluid through this pressure-side damping passage 6a, causing the pressure inside the cylinder 4 to rise, and the shock absorber D generates a damping force that suppresses its retraction.

[0054] As described above, the damping valve V is configured to include a piston (valve seat member) 5 having a port 5c and an annular valve seat 5e rising from the outer circumference of the opening end of the port 5c; an annular leaf valve 11 that is movable toward and toward the piston (valve seat member) 5 and seats away from and on the valve seat 5e; a shim 12 that is movable toward and toward the piston (valve seat member) 5 and is superimposed on the side of the leaf valve 11 opposite the piston (side of the valve seat member), and whose outer shape is smaller than that of the leaf valve 11; a disc 13 that is movable toward and toward the piston (valve seat member) 5 and has a disc-side port 13a that penetrates axially in a range that is further outward than the outer circumference of the shim 12 and further inward than the outer circumference of the leaf valve 11 when viewed from the axial direction, and is superimposed on the side of the shim 12 opposite the piston (side of the valve seat member); and a spring member 14 that is positioned on the side of the disc 13 opposite the piston (side of the valve seat member) and biases the disc 13, shim 12 and leaf valve 11 toward the piston (valve seat member) 5.

[0055] In the damping valve V configured in this way, the leaf valve 11 is given initial deflection by stacking shims 12 on the disc 13. Therefore, there is no need to provide support protrusions on the disc 13 itself to give initial deflection to the leaf valve 11, the shape of the disc 13 is simplified, and the opening pressure of the leaf valve 11 can be adjusted by replacing the shims 12 with shims of different thicknesses.

[0056] As a result of simplifying the shape of the disc 13, the disc 13 can be manufactured using inexpensive processing methods that do not require much processing time, such as press working. Furthermore, by using shims 12 with a relatively uniform thickness formed by press working, advanced dimensional control becomes unnecessary. Since shims 12 of different thicknesses can be prepared, the opening pressure of the leaf valve 11 can be tuned, eliminating the need to manufacture expensive and complexly shaped discs each time for tuning the opening pressure.

[0057] Based on the above, the damping valve V of this embodiment not only enables shorter manufacturing times and reduced costs, but also facilitates dimensional control and eliminates the hassle of tuning the opening pressure of the leaf valve 11.

[0058] Furthermore, in the damping valve V of this embodiment, the piston-side end (valve seat member side end) of the disc 13 is flat. The shape of the part of the disc 13 that does not interfere with the valve seat 5e and does not come into contact with the shim 12 and leaf valve 11 can be arbitrarily designed, but by making the entire piston-side end (valve seat member side end) flat, the shape of the disc 13 is further simplified, and the manufacturing cost of the damping valve V is also reduced.

[0059] Furthermore, the damping valve V of this embodiment includes a guide member 16 that is axial in shape and extends axially relative to the piston (valve seat member) 5, with a shim 12 and a disc 13 mounted on its outer circumference so as to be slidable in the axial direction, and the shim 12 has a notch 12a on its inner circumference that forms a gap between it and the guide member 16. With the shock absorber D configured in this way, even if the shim 12 is not fixed to the disc 13, communication between the disc-side port 13a and port 5c can be ensured by the notch 12a when the inner circumference of the leaf valve 11 flexes and the valve opens. In addition, with the damping valve V configured in this way, processing to fix the shim 12 and the disc 13 and surface processing of the shim 12 are unnecessary, so costs can be reduced even further.

[0060] In this embodiment, a guide member 16 is provided, and the shim 12 and disc 13 are slidably mounted on the outer circumference of the guide member 16. As a result, both the shim 12 and disc 13 can move axially relative to the piston (valve seat member) 5 without axial misalignment, and the damping valve V can exert a stable damping force. As mentioned above, the guide member 16 is separate from the rod 3, but if the shim 12 and disc 13 are to be slidably brought into direct contact with the outer circumference of the small-diameter portion 3a of the rod 3, the rod 3 itself can be used as a guide member.

[0061] Furthermore, the damping valve V of this embodiment includes a spring receiver 15 having an annular top portion 15a and a plurality of legs 15b hanging down from the outer circumference of the top portion 15a, with the lower ends of the legs 15b fitted onto the outer circumference of the piston (valve seat member) 5. The spring member 14 is interposed between the top portion 15a of the spring receiver 15 and the disc 13, with the end of the spring member 14 opposite the piston (end opposite the valve seat member) in contact with the top portion 15a and legs 15b of the spring receiver 15, and the end of the disc 13 opposite the piston (end opposite the valve seat member) being flat. With the damping valve V configured in this way, the spring member 14 is centered by contacting the top portion 15a and legs 15b of the spring receiver 15, so even if the end of the disc 13 opposite the piston (end opposite the valve seat member) is flat, the spring member 14 can apply a stable biasing force to the disc 13 without axial misalignment. Therefore, with the damping valve V of this embodiment, it is not necessary to provide a fitting portion or the like on the disc 13 to prevent misalignment of the spring member 14, and the shape of the end of the disc 13 opposite the piston (the end opposite the valve seat member) is also simplified, making it easier to process the disc 13 and reducing manufacturing costs. Furthermore, since the damping valve V of this embodiment is equipped with a guide member 16 and a spring receiver 15, when assembling the damping valve V onto the rod 3, the components constituting the damping valve V can be temporarily assembled and put into an assembly, making the work of assembling the damping valve V onto the rod 3 easier.

[0062] As mentioned above, the inner circumference of the shim 12 is not supported, so the shim 12 can move axially in accordance with the bending deformation of the inner circumference of the leaf valve 11. However, an annular flange protruding from the outer circumference of the piston 5 side end (valve seat member side end) of the guide member 16 may be provided, and the inner circumference of the shim 12 on the piston 5 side (valve seat member side) may be supported by the flange, thereby restricting the movement of the shim 12 toward the piston 5 side (valve seat member side). In this case, when the inner circumference of the leaf valve 11 bends and opens the disk side port 13a, the shim 12 is supported by the flange and reliably separated from the inner circumference of the leaf valve 11, ensuring communication between port 5c and disk side port 13a. Therefore, when a flange is provided on the guide member 16 in this manner, the notch 12a on the inner circumference of the shim 12 can be eliminated, and by eliminating the notch 12a and providing a notch on the outer circumference of the shim 12 that functions as an orifice in the radial direction, an orifice can be easily provided on the damping valve V.

[0063] Furthermore, the shock absorber D comprises an outer shell 2, a rod 3 inserted into the outer shell 2 so as to be movable in the axial direction, and a shock absorber body 1 having an extension chamber (operating chamber) R1 and a compression chamber (operating chamber) R2 through which hydraulic fluid (liquid) passes as the rod 3 moves relative to the outer shell 2, and a damping valve V provided between the extension chamber (operating chamber) R1 and the compression chamber (operating chamber) R2. With the shock absorber D configured in this way, costs can be reduced because it is equipped with a damping valve V that can be manufactured at low cost, and the damping force can be easily tuned by replacing the shim 12. Therefore, the shock absorber D of this embodiment not only enables a reduction in manufacturing time and cost, but also makes dimensional control easy and eliminates the hassle of tuning the valve opening pressure.

[0064] In this embodiment, the valve seat member is the piston 5, and the damping valve V is installed on the piston portion of the buffer D. However, the valve case 6 of the buffer D may be used as the valve seat member, and the damping valve V may be installed between the pressure chamber R2 and the reservoir chamber R, which are two working chambers. In other words, the damping valve V may be installed on the base valve portion of the buffer D. When the valve case 6 is used as the valve seat member, the passage configuration of the valve case 6 should be the same as the passage configuration of the piston 5 shown in Figure 2, so the valve case 6 should be provided with a port that allows bidirectional passage of hydraulic fluid. When the valve case 6 is used as the valve seat member, the leaf valve 11 can be used as a damping valve during the contraction operation of the buffer D by providing resistance when the hydraulic fluid (liquid) moves from the pressure chamber R2 to the reservoir chamber R, and the leaf valve 11 can be installed to move away from the piston 5 and open when the hydraulic fluid (liquid) moves from the reservoir chamber R to the pressure chamber R2. In this way, the damping valve V is installed between the two working chambers formed in the buffer D. and others This allows it to be used as a damping force source in shock absorber D.

[0065] Furthermore, the damping valve V may be installed upside down in the piston and base valve sections. In addition, the shock absorber D may be a single-tube type shock absorber in which a piston connected to a rod 3 is slidably inserted into the inner circumference of the outer shell 2. In such a single-tube type shock absorber D, the working chamber consists of two chambers, an extension chamber and a compression chamber, so the damping valve V can be provided in the piston section of the shock absorber D. The installation location of the damping valve will vary depending on the configuration of the shock absorber D, but the damping valve V should be installed in the optimal location according to the configuration of the shock absorber D.

[0066] Although preferred embodiments of the present invention have been described in detail above, modifications, alterations, and changes are permitted as long as they do not deviate from the scope of the claims. [Explanation of Symbols]

[0067] 1... Shock absorber body, 2... Outer shell, 3... Rod, 5... Piston (valve seat member), 5c... Port, 5e... Valve seat, 11... Leaf valve, 12... Shim, 12a... Notch, 13... Disc, 13a... Disc side port, 14... Spring member, 15... Spring support, 15a... Top, 15b... Leg, 16... Guide member, D... Shock absorber, R... Reservoir chamber (operating chamber), R1... Extension chamber (operating chamber), R2... Compression chamber (operating chamber), V... Damping valve

Claims

1. A valve seat member having a port and a valve seat that rises from the outer circumference of the open end of the port and surrounds the port, A leaf valve that is annular in shape and movable toward and away from the valve seat member, and that seats toward and away from the valve seat, A shim that is movable relative to the valve seat member, overlaps the leaf valve on the side opposite the valve seat member, and has an outer shape smaller than the leaf valve, A disk that is movable relative to the valve seat member and has a disk-side port that penetrates axially in a range on the inner side of the leaf valve's outer circumference from the axial direction, and is superimposed on the side of the shim opposite the valve seat member, The disc is provided with a spring member positioned on the side opposite the valve seat member, which biases the disc, the shim, and the leaf valve toward the valve seat member. A damping valve characterized by the following features.

2. The valve seat member side end of the aforementioned disc is flat. The damping valve according to feature 1.

3. The valve seat member is axial in shape and extends axially with respect to the valve seat member, and includes a guide member on which the shim and the disk are mounted so as to be slidable in the axial direction, The shim has a notch on its inner circumference that forms a gap between it and the guide member. The damping valve according to claim 1 or 2.

4. It has an annular top and a plurality of legs hanging down from the outer circumference of the top, and is equipped with a spring receiver whose lower end is fitted onto the outer circumference of the valve seat member, The spring member is interposed between the top of the spring receiver and the disk. The end of the spring member opposite the valve seat member is in contact with the top and leg portions of the spring support. The side of the disc opposite the valve seat member is flat. A damping valve according to any one of claims 1 to 3.

5. A buffer body having an outer shell, a rod inserted into the outer shell so as to be movable in the axial direction, and at least two working chambers through which liquid flows as the rod moves relative to the outer shell, The system comprises a damping valve according to any one of claims 1 to 4, provided between the operating chambers. A buffer characterized by the following features.

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