Check valve
The check valve design with a lower outer valve seat and conical coil spring minimizes hydraulic oil resistance and prevents stick-slip noise by ensuring smooth opening and uniform pressure fluctuations.
Patent Information
- Application Number
- JP2024038599
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-13
- Publication Date
- 2025-09-29
Smart Images
Figure 2025139653000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a check valve. [Background technology]
[0002] A check valve is used, for example, by being provided in the piston portion of a shock absorber that is interposed between the body and wheels of a vehicle and generates a damping force when expanding or contracting. Specifically, such a check valve includes a piston that is housed in the shock absorber and divides the inside of a cylinder into an extension-side chamber and a compression-side chamber, and serves as a valve seat member. The check valve also includes an annular leaf valve that is located on the extension-side chamber side of the piston, and a coil spring that biases the leaf valve toward the piston. The check valve opens and closes the port by seating on and lifting from an annular valve seat that surrounds a port provided in the piston.
[0003] Furthermore, when the shock absorber contracts, the check valve receives pressure from the compression-side chamber acting through the port, causing the leaf valve to move away from the valve seat and open the port, allowing hydraulic oil to flow from the compression-side chamber to the extension-side chamber. However, if resistance is applied to the flow of hydraulic oil when the valve is open, there is a possibility that the extension-side chamber will become pressurized below atmospheric pressure when the shock absorber contracts at high speed. Therefore, the check valve is required to apply as little resistance as possible to the flow of hydraulic oil when it is open.
[0004] To meet such demands, some check valves do not fix the inner circumference of the leaf valve, but instead slidably mount the leaf valve on the outer circumference of a cylindrical guide, allowing the entire leaf valve to move toward and away from the piston, widening the outlet end of the port when the valve is open and minimizing the resistance to the flow of hydraulic oil (see, for example, Patent Document 1). [Prior art documents] [Patent documents]
[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 6-69476 Summary of the Invention [Problem to be solved by the invention]
[0006] A check valve configured in this manner is advantageous in that when the valve is opened, the entire leaf valve moves away from the piston, allowing the port to open widely and reducing the resistance to the flow of hydraulic oil. However, on the other hand, if the leaf valve is tilted at an angle to the piston when the valve is open, stick-slip may occur between the leaf valve and the guide, causing abnormal noise.
[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a check valve that can reduce the resistance to the flow of liquid passing through it while suppressing the generation of abnormal noise. [Means for solving the problem]
[0008] In order to solve the above-mentioned problems, the check valve of the present invention comprises a port, a valve seat member having an annular valve seat disposed on the outer periphery of the outlet end of the port and surrounding the port, and an annular inner seat portion disposed on the inner periphery of the outlet end of the port, a leaf valve whose inner periphery is superimposed on the inner seat portion and whose outer periphery is allowed to deflect so that it can be seated on and removed from the valve seat, and a biasing member that biases the leaf valve toward the valve seat member, and the height of the valve seat in the axial direction of the valve seat member is lower than the inner seat portion.
[0009] With a check valve configured in this manner, the valve seat on which the outer periphery of the leaf valve sits is lower than the inner seat portion on which the inner periphery of the leaf valve overlaps, so when the valve is opened, a large gap is created between the valve seat and the leaf valve, reducing the resistance to the flow of liquid.Furthermore, when the entire leaf valve moves away from the valve seat and opens, it becomes flat, thereby suppressing the occurrence of stick-slip.
[0010] Furthermore, the leaf valves in the check valve may have non-uniform rigidity in the circumferential direction. With a check valve configured in this way, the leaf valve opens gradually from the circumferential portion with the highest rigidity, so that when the valve opens, the two chambers on either side of the valve seat member can be quickly connected to each other without causing a sudden pressure fluctuation between them.
[0011] The leaf valve in the check valve may also have an inner ring that overlaps the inner circumferential seat portion, an outer ring that is disposed on the outer periphery of the inner ring and that can close the outlet end of the port when seated on the valve seat, and one or more arms that connect the inner ring and the outer ring. With a check valve configured in this manner, the rigidity of the portion of the outer ring connected to the arms can be increased to facilitate separation from the valve seat, so the circumferential rigidity of the leaf valve can be easily adjusted by changing the location and number of arms, and the ease of opening the valve and the pressure fluctuation characteristics when the valve is open can be easily tuned.
[0012] Furthermore, the inner periphery of the leaf valve may be fixed to the inner periphery seat portion. With a check valve configured in this manner, the inner periphery of the leaf valve is fixed to the inner periphery seat portion, so the inner periphery of the leaf valve does not move relative to a member inserted into the inner periphery of the leaf valve, and stick-slip does not occur at all between the inner periphery of the leaf valve and the member, thereby effectively suppressing the generation of abnormal noise.
[0013] Furthermore, the leaf valve may have arms only within a 180-degree circumferential range. With a check valve configured in this way, the leaf valve gradually moves away from the valve seat, making it easier to open smoothly, thereby enjoying the advantage of reducing sudden changes in pressure fluctuations, and making it easier to achieve characteristics with little pressure fluctuation.
[0014] Furthermore, when a leaf valve has only one arm, the outer ring is more likely to move axially relative to the inner ring, and the part of the outer ring that is more likely to separate from the valve seat can be located at one point where the arm is connected.As a result, when the outer ring separates from the valve seat, it does not undergo wavy deformation at multiple points in the circumferential direction, allowing the valve to open smoothly and effectively suppressing sudden pressure fluctuations.In addition, when the arm bends, the outer ring is able to separate significantly from the valve seat, ensuring a sufficient flow rate and preventing unnecessary resistance to the flow of liquid through the port. [Effects of the Invention]
[0015] According to the check valve of the present invention, it is possible to reduce the resistance to the flow of liquid passing through while suppressing the generation of abnormal noise. [Brief explanation of the drawings]
[0016] [Figure 1] FIG. 1 is a vertical cross-sectional view of a shock absorber to which a check valve according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a check valve according to one embodiment of the present invention. [Figure 3] FIG. 3 is a plan view of a leaf valve in a check valve according to one embodiment of the present invention. [Figure 4] Figure 4(a) is a plan view of a first modified leaf valve, Figure 4(b) is a plan view of a second modified leaf valve, Figure 4(c) is a plan view of a third modified leaf valve, and Figure 4(d) is a plan view of a fourth modified leaf valve. [Figure 5] Figure 5(a) is a plan view of a fifth modified example of the leaf valve, and Figure 5(b) is a plan view of a sixth modified example of the leaf valve. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a first modified example of the biasing member. [Figure 7] FIG. 7 is a perspective view of a leaf valve with an integrated biasing member. DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention will be described below based on the embodiments shown in the drawings. As shown in Figure 1, a check valve V in one embodiment is applied to the piston portion of a shock absorber D, and includes a piston 1 as a valve seat member, a leaf valve 2 placed on the valve seat member, and a conical coil spring 3 as a biasing member that biases the leaf valve 2.
[0018] 1, a shock absorber D to which the check valve V is applied includes a cylinder 10, a rod 11 movably inserted into the cylinder 10, a piston 1 connected to the rod 11 and movably inserted into the cylinder 10 in the axial direction, serving as a valve seat member dividing the interior of the cylinder 10 into two working chambers: an expansion-side chamber R1 and a compression-side chamber R2, an outer cylinder 12 covering the outer periphery of the cylinder 10 and forming a reservoir R for storing liquid in an annular gap between the cylinder 10 and the outer cylinder 12, and a check valve V. This shock absorber D is installed between the body and axle of a vehicle (not shown) to suppress vibrations of the body and wheels. The check valve V may also be used in hydraulic equipment other than the shock absorber D.
[0019] Below, we will explain in detail each part of the check valve V and the shock absorber D. First, we will explain each part of the shock absorber D. The cylinder 10 is cylindrical, and has an annular rod guide 13 fitted to its upper end in FIG. 1, and a disk-shaped valve case 14 fitted to its lower end in FIG. 1, and is housed in an outer cylinder 12 that is a cylindrical cylinder with a bottom.
[0020] 1, an annular seal member 15 is laminated above the rod guide 13. The outer cylinder 12 is cylindrical with a bottom and has a crimped portion 12a formed by crimping the upper end toward the inner periphery, and the seal member 15, rod guide 13, cylinder 10, and valve case 14 are sandwiched between the crimped portion 12a and the bottom portion 12b.
[0021] The rod 11 is inserted into the cylinder 10 by being inserted through the inner periphery of the rod guide 13, and its upper end in Fig. 1 protrudes outside the cylinder 10. The rod guide 13 is annular and is fitted onto the inner periphery of the upper end of the cylinder 10 in Fig. 1, and its outer periphery is fitted onto the inner periphery of the upper end of the outer cylinder 12. The rod guide 13 is provided on its inner periphery with a cylindrical bushing 13a that comes into sliding contact with the outer periphery of the rod 11.
[0022] Rod 11 is guided in its axial movement relative to cylinder 10 by rod guide 13, allowing it to move in and out of cylinder 10 without axial wobble. Sealing member 15 has a seal lip 15a on its inner periphery that makes sliding contact with the outer periphery of rod 11, and an annular seal ring 15b on its outer periphery that closely contacts the inner periphery of outer cylinder 12 and the outer periphery of the upper end of rod guide 13, preventing liquid from leaking from inside cylinder 10 and outer cylinder 12 to the outside.
[0023] The rod 11 has a small diameter portion 11a at its lower end in FIG. 1, which is its tip, whose outer diameter is smaller than that of its upper side, a threaded portion 11b formed on the outer periphery of the lower end of the small diameter portion 11a, and a step portion 11c formed between the small diameter portion 11a and the upper side of the small diameter portion 11a. An annular piston 1 is attached to the outer periphery of the small diameter portion 11a of the rod 11.
[0024] When the rod 11 is inserted into the cylinder 10 via the inner periphery of the rod guide 13, the piston 1 attached to the rod 11 slides against the inner periphery of the cylinder 10, and the piston 1 divides the interior of the cylinder 10 into an extension-side chamber R1 at the top in FIG. 1 and a compression-side chamber R2 at the bottom in FIG. 1. The extension-side chamber R1 and the compression-side chamber R2 in the cylinder 10 are filled with a liquid such as hydraulic oil. A reservoir R formed between the cylinder 10 and the outer cylinder 12 stores a liquid and a gas. The liquid stored in the cylinder 10 and the reservoir R may be water, an aqueous solution, or other liquids, in addition to hydraulic oil. When the liquid is hydraulic oil, the gas filled in the reservoir R is preferably an inert gas such as nitrogen, but may also be other gases or air.
[0025] 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 12b of the outer cylinder 12, and the outer cylinder 12 is connected to the other of the vehicle body and the axle via the bracket (not shown).
[0026] In this way, shock absorber D is interposed between the vehicle body and the axle. When the vehicle travels on an uneven road surface and the wheels vibrate up and down relative to the vehicle body, rod 11 moves in and out of cylinder 10, expanding and contracting shock absorber D, and piston 1 moves up and down (axially) within cylinder 10.
[0027] As shown in FIG. 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 16 that is screwed onto the threaded portion 11b of the rod 11.
[0028] More specifically, the piston 1 includes an annular main body 1a having piston rings 1b attached to its outer periphery, a plurality of compression-side ports 1c provided in the main body 1a and opening from the lower end of the main body 1a in FIG. 2 and leading to the outer periphery at the upper end in FIG. 2, an expansion-side port 1d opening from the upper end of the main body 1a in FIG. 2 and leading to the outer periphery at the lower end in FIG. 2, an annular valve seat 1e provided in the main body 1a and arranged on the outer periphery at the upper end in FIG. 2, which is the outlet end of the compression-side port 1c, and surrounding the compression-side port 1c, and an annular inner seat portion 1f provided in the main body 1a and arranged on the inner periphery of the outlet end of the compression-side port 1c.
[0029] As described above, the main body 1a is annular, and the piston ring 1b attached to its outer periphery is in sliding contact with the inner periphery of the cylinder 10, dividing the interior of the cylinder 10 into an expansion-side chamber R1 and a compression-side chamber R2. The upper end of the main body 1a in FIG. 2 is provided with an annular window 1g, which is an annular recess communicating with the outlet end of the compression-side port 1c, which is the upper end in FIG. 2, and an annular groove 1h provided on the inner periphery of the annular window 1g. The valve seat 1e is provided to surround the outer periphery of the annular window 1g, and the inner seat portion 1f is provided on the inner periphery side of the annular groove 1h. Furthermore, as shown in FIG. 2, the main body 1a is provided with an annular expansion-side valve seat 1i, which protrudes from the lower end and is positioned on the outer periphery side of the expansion-side port 1d.
[0030] The compression-side port 1c as a port opens between the inner circumferential seat portion 1f and the valve seat 1e at the upper end of the main body 1a in FIG. 2, extends downward along the axial direction of the piston 1, and opens at the outer periphery of the expansion-side valve seat 1i at the lower end of the main body 1a in FIG. 2, thereby communicating the expansion-side chamber R1 and the compression-side chamber R2. Eight compression-side ports 1c are provided in the main body 1a at equal intervals in the circumferential direction of the main body 1a. The compression-side ports 1c are compression-side ports that allow liquid to flow from the compression-side chamber R2 to the expansion-side chamber R1 when the shock absorber D is contracting.
[0031] The valve seat 1e is provided at the upper end of the main body 1a in Figure 2, and is formed by an annular protrusion that protrudes upward from the upper end of the main body 1a, surrounds the outer periphery of the compression side port 1c, and is provided at its upper end with a flat seat surface 1e1 on which the leaf valve 2 of the check valve V seats and disengages.
[0032] On the other hand, the inner seat portion 1f is provided at the upper end of the main body portion 1a in Figure 2, and is formed by a circular protrusion that protrudes upward from the upper end of the main body portion 1a.It is arranged on the inner circumference of the compression side port 1c, and has a flat seat surface 1f1 at its upper end on which the inner circumference of the leaf valve 2 in the check valve V seats.
[0033] The height of the valve seat 1e in the axial direction of the piston 1 is lower than that of the inner seat portion 1f, and the seat surface 1e1 of the valve seat 1e is located lower than the seat surface 1f1 of the inner seat portion 1f. The height of a flat surface 1j at the upper end of the main body 1a in FIG. 2, between the annular window 1g and the annular groove 1h, is the same height as the seat surface 1e1 of the valve seat 1e and lower than that of the inner seat portion 1f. The height of the flat surface 1j only needs to be lower than that of the inner seat portion 1f. As long as the leaf valve 2 can be seated on the flat surface 1j and the valve seat 1e simultaneously and the outlet end of the compression-side port 1c can be blocked, there may be a difference in height between the flat surface 1j and the valve seat 1e; however, the height of the valve seat 1e is preferably set to be equal to or lower than that of the flat surface 1j.
[0034] Eight expansion-side ports 1d are provided at equal intervals around the main body 1a, and each port opens from the inner peripheral side of the expansion-side valve seat 1i at the lower end of the main body 1a in FIG. 2, extends upward along the axial direction of the piston 1, and opens into the annular groove 1h at the upper end of the main body 1a in FIG. 2, thereby communicating between the expansion-side chamber R1 and the compression-side chamber R2.
[0035] The shape and structure of the compression-side port 1c can be modified as long as its upper end in FIG. 2 opens between the valve seat 1e of the main body 1a and the inner seat portion 1f, and its lower end opens to the outer periphery of the expansion-side valve seat 1i of the main body 1a, thereby connecting the expansion-side chamber R1 and the compression-side chamber R2. The expansion-side port 1d can be provided so that its upper end in FIG. 2 opens to the outer periphery of the valve seat 1e of the main body 1a, and its shape and structure can be modified as long as it connects the expansion-side chamber R1 and the compression-side chamber R2. The number of the compression-side ports 1c and the expansion-side ports 1d is not limited to eight.
[0036] 2, a laminated leaf valve 17 is stacked below the piston 1. The laminated leaf valve 17 is configured by stacking multiple annular plates, and is fitted to the outer periphery of the small-diameter portion 11a of the rod 11 together with the piston 1 and fixed to the small-diameter portion 11a by a piston nut 16. The laminated leaf valve 17, fixed to the small-diameter portion 11a of the rod 11 in this manner, has its inner periphery fixed to the small-diameter portion 11a, and its outer periphery is seated on the expansion-side valve seat 1i, allowing bending of the outer periphery. Therefore, when the rod 11 moves upward in FIG. 1 relative to the cylinder 10 and the pressure in the expansion-side chamber R1 acting through the expansion-side port 1d increases and reaches the valve-opening pressure, the laminated leaf valve 17 bends its outer periphery and separates from the expansion-side valve seat 1i, allowing the flow of liquid through the expansion-side port 1d from the expansion-side chamber R1 to the compression-side chamber R2 while providing resistance to the flow of liquid. In addition, when the rod 11 moves downward in FIG. 1 relative to the cylinder 10, the stacked leaf valve 17 seats its outer circumferential side on the expansion-side valve seat 1i to close the expansion-side port 1d, thereby preventing liquid from flowing through the expansion-side port 1d from the compression-side chamber R2 to the expansion-side chamber R1.
[0037] The check valve V is configured to include a leaf valve 2 which is annular and has its inner periphery overlapping the inner periphery seat portion 1f of the piston 1 and is allowed to flex on its outer periphery so that it can be seated on and removed from the valve seat 1e, a conical coil spring 3 which is arranged on the opposite side of the leaf valve 2 to the piston and serves as a biasing member which biases the leaf valve 2 toward the piston 1, and a spring bearing 4 which is arranged on the opposite side of the leaf valve 2 to the piston and supports the end of the conical coil spring 3 on the opposite side of the leaf valve.
[0038] As shown in FIG. 3, the leaf valve 2 includes an annular inner ring 2a that is placed on the seat surface 1f1 of the inner seat portion 1f of the piston 1 serving as a valve seat member, an outer ring 2b that is disposed on the outer periphery of the inner ring 2a and that closes the annular window 1g when seated on the valve seat 1e, thereby blocking the outlet end of the compression side port 1c, and one arm 2c that connects the inner ring 2a and the outer ring 2b.
[0039] The leaf valve 2 is stacked above the piston 1 in FIG. 2, and the inner ring 2a is fitted onto the outer periphery of the small diameter portion 11a of the rod 11, so that the leaf valve 2 is attached to the outer periphery of the small diameter portion 11a. In this embodiment, the inner diameter of the inner ring 2a is approximately equal to the inner diameter of the piston 1, so that the leaf valve 2 is aligned concentrically with the piston 1 by the small diameter portion 11a of the rod 11. The outer diameter of the inner ring 2a is equal to the outer diameter of the seat surface 1f1 of the inner circumferential seat portion 1f, but may be slightly larger than the outer diameter of the seat surface 1f1 as long as it does not prevent the outer ring 2b from contacting the flat surface 1j between the annular groove 1h and the annular window 1g.
[0040] The spring bearing 4 includes a cylindrical collar 4a that fits onto the outer periphery of the small diameter portion 11a and abuts against the side of the inner ring 2a of the leaf valve 2 opposite the piston, and a flange-shaped spring seat 4b that is provided on the outer periphery of the upper end of the collar 4a in Figure 2.
[0041] The conical coil spring 3 serving as a biasing member is interposed in a compressed state between the leaf valve 2 and the spring bearing 4, with its lower end on the large diameter side in FIG. 2 abutting against the outer ring 2b of the leaf valve 2 and its upper end on the small diameter side in FIG. 2 abutting against the spring seat 4b of the spring bearing 4, and always exerts a resilient force to bias the outer ring 2b of the leaf valve 2 in the direction of seating it on the valve seat 1e.
[0042] The check valve V configured in this manner is assembled in order to the outer periphery of the small diameter portion 11a of the rod 11 together with the piston 1 and the stacked leaf valve 17, and then fixed to the rod 11 by being sandwiched between the piston nut 16, which is screwed onto the threaded portion 11b, and the step portion 11c.
[0043] Therefore, the leaf valve 2 in the check valve V is fixed with the inner ring 2a seated on the seat surface 1f1 of the inner seat portion 1f of the piston 1 by the collar 4a of the spring bearing 4, and the outer ring 2b on the outer periphery can be seated on and removed from the valve seat 1e by the deflection of the arm 2c.
[0044] Furthermore, in a no-load state where no external pressure is acting on the leaf valve 2, the leaf valve 2 is biased by the conical coil spring 3, and because the valve seat 1e is lower than the inner peripheral seat portion 1f, the arm 2c bends toward the piston 1, and the outer ring 2b seats on the flat surface 1j between the annular window 1g and the annular groove 1h and on the valve seat 1e, thereby closing the compression-side port 1c. Furthermore, in a state where the pressure in the expansion-side chamber R1 is higher than the pressure in the contraction-side chamber R2, the leaf valve 2 closes the contraction-side port 1c because the pressure in the expansion-side chamber R1 acts in addition to the biasing force of the conical coil spring 3 to press the outer ring 2b against the valve seat 1e and the flat surface 1j, thereby blocking the liquid from flowing through the contraction-side port 1c from the expansion-side chamber R1 to the contraction-side chamber R2. When the outer ring 2b of the leaf valve 2 is seated on the flat surface 1j and the valve seat 1e to close the compression-side port 1c, the arc-shaped hole between the inner ring 2a and the outer ring 2b faces the annular groove 1h through which the inlet of the expansion-side port 1d opens, so the expansion-side port 1d is not closed.
[0045] On the other hand, when the leaf valve 2 receives the pressure of the compression-side chamber R2 acting through the compression-side port 1c at the outer ring 2b and the arm 2c bends in a direction away from the piston 1 and separates from the valve seat 1e and the flat surface 1j, the leaf valve 2 opens the compression-side port 1c to allow the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1 through the compression-side port 1c, but provides almost no resistance to the flow of liquid. In this way, the check valve V is a valve in which the compression-side port 1c as a port is set as a one-way port that allows the flow of liquid only from the compression-side chamber R2 to the extension-side chamber R1, and provides almost no resistance to the flow of liquid passing through the compression-side port 1c.
[0046] As described above, the leaf valve 2 includes an inner ring 2a, an outer ring 2b disposed on the outer periphery of the inner ring 2a, and one arm 2c connecting the inner ring 2a and the outer ring 2b, and the arm 2c and the outer ring 2b are allowed to flex, with the outer ring 2b on the outer periphery being allowed to seat on and release from the valve seat 1e to open and close the compression-side port 1c. Therefore, the rigidity of the leaf valve 2 is highest at the portion where the arm 2c is provided and lowest at the portion 180 degrees opposite the connection position of the arm 2c, and the rigidity of the leaf valve 2 is non-uniform in the circumferential direction.
[0047] Furthermore, the inner seat portion 1f on which the inner periphery of the leaf valve 2 sits is higher than the valve seat 1e on which the outer periphery sits, so that when the outer periphery of the leaf valve 2 seats on the valve seat 1e, the arm 2c bends toward the piston 1 serving as a valve seat member, exerting a resilient force in a direction away from the valve seat 1e. Therefore, when the leaf valve 2 is biased by the conical coil spring 3 serving as a biasing member and pressed against the valve seat 1e, with the outer ring 2b seated on the valve seat 1e, the portion of the outer ring 2b connected to the arm 2c in the circumferential direction is most likely to separate from the valve seat 1e, and the portion of the outer ring 2b 180 degrees opposite the connected portion of the arm 2c in the circumferential direction is least likely to separate from the valve seat 1e. Thus, in the check valve V of this embodiment, the leaf valve 2 differs in ease of separation from the valve seat 1e along the circumferential direction.
[0048] Next, the valve case 14 fitted to the lower end of the cylinder 10 in FIG. 1 is disk-shaped and includes a main body 14a having a fitting portion 14b that fits to the inner periphery of the cylinder 10 and a large-diameter portion 14c that is continuous with the lower end of the fitting portion 14b and has an outer diameter larger than that of the fitting portion 14b and abuts against the lower end of the cylinder 10 in FIG. 1, and a plurality of leg portions 14d that protrude from the outer periphery of the lower end of the large-diameter portion 14c in FIG. 1 and are arranged at equal intervals in the circumferential direction and abut against the bottom portion 12b of the outer tube 12.
[0049] The valve case 14 is sandwiched and fixed between the cylinder 10 and the outer tube 12, and separates the interior of the cylinder 10 from the pressure side chamber R2 and the reservoir R formed between the cylinder 10 and the outer tube 12.
[0050] The main body 14a of the valve case 14 is provided with a compression side damping passage 14e that allows liquid to flow only from the compression side chamber R2 to the reservoir R and provides resistance to the liquid flow, and a suction passage 14f that allows liquid to flow only from the reservoir R to the compression side chamber R2 and provides almost no resistance to the liquid flow. Note that the space between the main body 14a of the valve case 14 and the bottom 12b of the outer cylinder 12 is in communication with the reservoir R via the legs 14d, 14d, so communication between the compression side chamber R2 and the reservoir R is ensured via the compression side damping passage 14e and the suction passage 14f.
[0051] In the shock absorber D configured as described above, when the rod 11 moves upward in FIG. 1 relative to the cylinder 10 during an extension operation, the upward movement of the piston 1 in FIG. 1 causes the liquid in the expansion-side chamber R1 to bend the laminated leaf valve 17, moving it away from the expansion-side valve seat 1i, and move through the expansion-side port 1d to the contraction-side chamber R2. The laminated leaf valve 17 provides resistance to this liquid flow, causing the pressure in the expansion-side chamber R1 to rise. Meanwhile, the expanding contraction-side chamber R2 is supplied with liquid from the reservoir R through the suction passage 14f provided in the valve case 14, but the suction passage 14f provides almost no resistance to the liquid flow, so the pressure in the contraction-side chamber R2 becomes approximately equal to the pressure in the reservoir R. In addition, since the pressure in the expansion-side chamber R1 of the leaf valve 2 in the check valve V is higher than the pressure in the contraction-side chamber R2 and the leaf valve 2 is biased by the conical coil spring 3, the outer ring 2b is brought into close contact with the valve seat 1e and the flat surface 1j, thereby blocking the contraction-side port 1c as a port and preventing the flow of liquid.
[0052] Therefore, when the shock absorber D performs an extension operation, the laminated leaf valve 17 applies resistance to the flow of fluid from the extension-side chamber R1 to the compression-side chamber R2, thereby increasing the pressure in the extension-side chamber R1 and generating an extension-side damping force that prevents the piston 1 from moving upward in FIG. 1 relative to the cylinder 10.
[0053] On the other hand, when the shock absorber D is in a contraction operation in which the rod 11 moves downward in FIG. 1 relative to the cylinder 10, the piston 1 moves downward in FIG. 1, and the liquid in the compression-side chamber R2 is compressed, bending the leaf valve 2 of the check valve V and moving it away from the valve seat 1e, and then passes through the compression-side port 1c as a port and moves to the extension-side chamber R1.
[0054] As described above, in check valve V, the valve seat 1e on which the outer ring 2b of the leaf valve 2 seats is lower than the inner circumferential seat portion 1f to which the inner ring 2a of the leaf valve 2 of the piston 1 serving as the valve seat member is fixed. Therefore, when the outer periphery of the leaf valve 2 seats on the valve seat 1e, the arm 2c bends toward the piston 1 serving as the valve seat member, exerting a resilient force in a direction away from the valve seat 1e. Also, as described above, in check valve V, the leaf valve 2 has non-uniform rigidity in the circumferential direction. Therefore, the portion of the outer ring 2b connected to the arm 2c in the circumferential direction is most likely to separate from the valve seat 1e, and the portion of the outer ring 2b 180 degrees opposite the connection position of the arm 2c in the circumferential direction is least likely to separate from the valve seat 1e.
[0055] Therefore, when the check valve V opens under the pressure of the compression-side chamber R2, the part where the arm 2c of the leaf valve 2 is connected separates from the valve seat 1e, and the part of the outer ring 2b that separates from the valve seat 1e gradually expands in the circumferential direction around the connected part of the arm 2c, and the part of the outer ring 2b that is 180 degrees opposite the connected part of the arm 2c is the last to separate from the valve seat 1e. Also, when the leaf valve 2 separates from the valve seat 1e and the check valve V opens, the valve seat 1e on which the outer periphery of the leaf valve 2 separates from is lower than the inner periphery seat portion 1f on which the inner periphery of the leaf valve 2 sits, so a large gap is formed between the valve seat 1e and the outer periphery of the leaf valve 2, and the resistance that the check valve V applies to the flow of liquid passing through the compression-side port 1c can be extremely small.
[0056] In this way, the check valve V does not move away from the valve seat 1e all at once in the circumferential direction, but opens gradually starting from the portion with higher rigidity in the circumferential direction, so that a sudden pressure fluctuation does not occur in the cylinder 10 when the valve opens, and the compression-side chamber R2 is quickly connected to the expansion-side chamber R1, preventing negative pressure in the expansion-side chamber R1. Furthermore, the leaf valve 2 in the check valve V of this embodiment is restrained with its inner circumferential side seated on the inner circumferential seat portion 1f, so stick-slip does not occur and abnormal noise does not occur. Incidentally, as in the check valve V of this embodiment, even in the case where the inner ring 2a on the inner periphery of the leaf valve 2 is not constrained by the collar 4a of the spring bearing 4 and the inner ring 2a is slidably fitted to the outer periphery of the collar 4a so that the inner ring 2a can separate from the inner periphery seat portion 1f and the entire leaf valve 2 can separate from the piston 1 serving as the valve seat member, the entire outer ring 2b on the outer periphery operates to separate from the piston 1 after the entire outer ring 2b on the outer periphery separates from the valve seat 1e and becomes flat, making it less likely that stick-slip will occur between the leaf valve 2 and the collar 4a, thereby suppressing the generation of abnormal noise.
[0057] In this way, when the shock absorber D is contracting, the check valve V opens quickly and provides almost no resistance to the flow of liquid, so the pressures in the expansion-side chamber R1 and the compression-side chamber R2 become approximately equal.
[0058] Furthermore, when the shock absorber D is contracting, the rod 11 enters the cylinder 10, and the cylinder 10 contains an excess of liquid corresponding to the volume of the rod 11 that has entered the cylinder 10. This excess liquid is discharged to the reservoir R via a compression-side damping passage 14e provided in the valve case 14. The compression-side damping passage 14e provides resistance to the flow of liquid from the compression-side chamber R2 to the reservoir R, and therefore the pressure in the cylinder 10 increases when the shock absorber D is contracting. The piston 1 in the shock absorber D is pressed upward in FIG. 1 by the pressure in the compression-side chamber R2 and pressed downward in FIG. 1 by the pressure in the extension-side chamber R1. However, the pressure-receiving area of the piston 1 that receives the pressure in the compression-side chamber R2 is larger than the pressure-receiving area that receives the pressure in the extension-side chamber R1 by the cross-sectional area of the rod 11, and therefore the shock absorber D generates a compression-side damping force that prevents the piston 1 from moving downward when it is contracting.
[0059] As described above, the check valve V of this embodiment comprises a compression side port (port) 1c, a piston (valve seat member) 1 having an annular valve seat 1e arranged on the outer periphery of the outlet end of the compression side port (port) 1c and surrounding the compression side port (port) 1c, and an annular inner circumferential seat portion 1f arranged on the inner periphery of the outlet end of the compression side port (port) 1c, an annular leaf valve 2 whose inner periphery is overlapped with the inner circumferential seat portion 1f and which is allowed to deflect on the outer periphery so that it can be seated on and removed from the valve seat 1e, and a conical coil spring (biasing member) 3 that biases the leaf valve 2 toward the piston (valve seat member) 1, and the height of the valve seat 1e in the axial direction of the piston (valve seat member) 1 is lower than the inner circumferential seat portion 1f.
[0060] With the check valve V configured in this manner, the valve seat 1e on which the outer periphery of the leaf valve 2 sits is lower than the inner periphery seat portion 1f on which the inner periphery of the leaf valve 2 of the piston (valve seat member) 1 overlaps, so when the leaf valve 2 moves away from the valve seat 1e and the check valve V opens, a large gap is formed between the valve seat 1e and the outer periphery of the leaf valve 2, making it possible to extremely reduce the resistance to the flow of liquid passing through the compression side port 1c. Also, when the entire leaf valve 2 moves away from the valve seat 1e and opens, it becomes flat, which prevents stick-slip and therefore reduces the generation of abnormal noise.
[0061] Furthermore, the leaf valve 2 in the check valve V of this embodiment has non-uniform rigidity in the circumferential direction, and therefore opens gradually from the portion of the leaf valve 2 with higher rigidity in the circumferential direction, thereby suppressing abrupt pressure fluctuations in the expansion-side chamber R1 and the contraction-side chamber R2 sandwiched between the piston (valve seat member) 1 when the leaf valve 2 opens, and quickly brings the expansion-side chamber R1 and the contraction-side chamber R2 into communication with each other. As described above, if the leaf valve 2 has non-uniform rigidity in the circumferential direction, this is preferable because it can suppress abrupt pressure fluctuations in the expansion-side chamber R1 and the contraction-side chamber R2 sandwiched between the piston (valve seat member) 1. However, a configuration may be adopted in which the leaf valve 2 is annular and has a plurality of holes that communicate with the expansion-side port 1d at equal intervals in the circumferential direction, so that the rigidity is not non-uniform in the circumferential direction. Even if such a configuration is adopted, the effect of the present invention is not lost because resistance can be reduced and stick-slip can be suppressed.
[0062] In addition, the check valve V of this embodiment is provided with an inner ring 2a in which the leaf valve 2 is superimposed on the inner seat portion 1f, an outer ring 2b that is arranged on the outer peripheral side of the inner ring 2a and can block the outlet end of the pressure side port (port) 1c when seated on the valve seat 1e, and one arm 2c that connects the inner ring 2a and outer ring 2b. According to the check valve V configured in this manner, the inner ring 2a and the outer ring 2b are connected by only one arm 2c, so that the outer ring 2b can easily move in the axial direction relative to the inner ring 2a, and the part of the outer ring 2b that is likely to separate from the valve seat 1e can be made to be the single point where the arm 2c is connected. Therefore, when the outer ring 2b separates from the valve seat 1e, it does not undergo wavy deformation at multiple points in the circumferential direction, allowing the valve to open smoothly and effectively suppressing sudden pressure fluctuations. In addition, when the arm 2c bends, the outer ring 2b is separated significantly from the valve seat 1e, ensuring a sufficient flow rate and preventing unnecessary resistance to the flow of liquid flowing through the pressure-side port (port) 1c.
[0063] Furthermore, the check valve V may include an inner ring 2a in which the leaf valve 2 is superimposed on the inner seat portion 1f, an outer ring 2b arranged on the outer peripheral side of the inner ring 2a and capable of blocking the outlet end of the pressure side port (port) 1c when seated on the valve seat 1e, and one or more arms 2c connecting the inner ring 2a and the outer ring 2b.
[0064] With the check valve V configured in this manner, the rigidity of the portion of the outer ring 2b connected to the arms 2c can be increased to facilitate separation from the valve seat 1e, so the circumferential rigidity of the leaf valve 2 can be easily adjusted by the installation locations and number of arms 2c, making it easy to tune the ease of opening the valve and the pressure fluctuation characteristics when the valve is open.
[0065] The number, locations, and shapes of the arms 2c can be arbitrarily modified. For example, as shown in Figure 4(a), if the circumferential width of the arms 2c is narrower at the middle than at the connection between the inner ring 2a and the outer ring 2b, the rigidity of the arms 2c can be lower than if the circumferential width of the arms 2c were uniform, and the opening pressure of the check valve V can be increased accordingly.
[0066] Furthermore, as shown in Figure 4(b), when two arms 2c are arranged perpendicular to each other between the inner ring 2a and outer ring 2b of the leaf valve 2, the rigidity of the outer ring 2b in a range of approximately 90 degrees (the shaded area in Figure 4(b)) where the arms 2c are arranged close to each other in the circumferential direction is increased, and the rigidity of the other range of approximately 270 degrees is decreased, and multiple arms 2c are arranged concentratedly in the circumferential direction of the leaf valve 2, thereby making it possible to set a range with high rigidity.
[0067] If multiple arms 2c are provided at equal intervals around the circumferential direction of the leaf valve 2, high rigidity and low rigidity portions will alternate, making it easier to open the high rigidity portions. However, if the circumferential length of the high rigidity and low rigidity portions is too short, it will be difficult for the leaf valve 2 to open smoothly from the valve seat 1e. Therefore, as shown in Figure 4(c), if the arms 2c are concentrated in a range of only 180 degrees around the circumferential direction of the leaf valve 2, the leaf valve 2 will gradually move away from the valve seat 1e, making it easier to open smoothly and offering the advantage of reducing sudden pressure fluctuations. This makes it easier to achieve characteristics with little pressure fluctuation.
[0068] Furthermore, as shown in Fig. 4(d), the arm 2c may be made longer to reduce the rigidity of the arm 2c. In the leaf valve 2 shown in Fig. 4(d), the arm 2c includes a first straight portion 2c1 extending radially from the inner ring 2a, a pair of second straight portions 2c2 and 2c3 extending radially from two positions on the outer ring 2b that are offset in the circumferential direction from the first straight portion 2c1, and an arc-shaped intermediate portion 2c4 that connects the tips of the second straight portions 2c2 and 2c3 and has a center connected to the first straight portion 2c1, thereby increasing the overall length of the arm 2c.
[0069] When the leaf valve 2 is configured in this manner, compared to when the inner ring 2a and the outer ring 2b are connected by an arm 2c that extends linearly in the radial direction as shown in Figure 3, the arm 2c shown in Figure 4(d) is longer and has lower bending rigidity, allowing the valve-opening pressure of the check valve V to be increased. By changing the shape of the arm 2c in this way, the overall length of the arm 2c can be adjusted, and the valve-opening pressure of the check valve V can be easily adjusted. The first straight portion 2c1 may be connected to a position offset from the center of the intermediate portion 2c4, so that the rigidity of the connection portion of the outer ring 2b to the second straight portion 2c3 and the connection portion of the second straight portion 2c4 differs. Furthermore, if the rigidity of the arm 2c is reduced, less force is required to seat the leaf valve 2 on the valve seat 1e, and therefore the biasing force of the conical coil spring 3 as a biasing member is reduced. Conversely, if the rigidity of the arm 2c is increased, more force is required to seat the leaf valve 2 on the valve seat 1e, and therefore the biasing force of the conical coil spring 3 as a biasing member is increased.
[0070] 4(d) is provided with one arm 2c, multiple arms 2c of the same shape may be provided, or multiple arms 2c of different shapes may be provided on one leaf valve 2. Furthermore, although not shown, the arm 2c may be configured to include two first straight sections connected to the inner ring 2a, one second straight section connected to the outer ring 2b, and an arc-shaped intermediate section connecting the tips of the first straight sections and having its center connected to the second straight section, or may be configured to include one first straight section connected to the inner ring 2a, one second straight section connected to the outer ring 2b, and an arc-shaped intermediate section connecting the tips of the first straight sections and the second straight sections.
[0071] 5(a), the leaf valve 2 may have an outer ring 2b whose axial thickness varies circumferentially to provide non-uniform circumferential rigidity. Alternatively, as shown in FIG. 5(b), the leaf valve 2 may be composed of an annular plate 21 and an annular plate 22 laminated on the annular plate 21 and having a notch 22a on its outer periphery, thereby varying the axial thickness of the leaf valve 2 in the circumferential direction to provide non-uniform circumferential rigidity of the leaf valve 2. In the case of the leaf valve 2 having an annular shape and no holes like the leaf valve 2 in FIG. 5(b), the inlet of the expansion-side port 1d provided in the piston 1 serving as the valve seat member may be designed to open to the outer periphery of the valve seat 1e, so that when the leaf valve 2 is seated on the valve seat 1e, only the compression-side port 1c is closed and the expansion-side port 1d is not closed. In this case, since the expansion-side port 1d does not open to the inner periphery of the valve seat 1e, the piston 1 can eliminate both the flat surface 1j and the annular groove 1h provided between the annular window 1g on the inner periphery of the valve seat 1e and the inner periphery seat portion 1f. In this way, when the piston 1 in the valve seat member is provided with the expansion-side port 1d that allows the liquid to pass to the opposite side in addition to the compression-side port 1c as a port, whether or not to provide the flat surface 1j and the annular groove 1h is determined depending on the opening position of the expansion-side port 1d. When the expansion-side port 1d opens to the inner periphery of the valve seat 1e, the leaf valve 2 is configured to include the inner ring 2a, the outer ring 2b, and the arms 2c, thereby eliminating the risk of clogging of the expansion-side port 1d by the leaf valve 2. However, when the expansion-side port 1d opens to the outer periphery of the valve seat 1e, the leaf valve 2 can have a configuration including the inner ring 2a, the outer ring 2b, and the arms 2c, and can have an annular shape without holes.
[0072] Furthermore, in the check valve V of this embodiment, the biasing member is a conical coil spring 3, and because the axial length of the conical coil spring 3 becomes very short when fully compressed, it is likely to be separated significantly from the valve seat 1e when the leaf valve 2 is opened, making it easier to ensure a sufficient flow rate, but is not limited to a conical coil spring 3. Therefore, for example, as shown in Fig. 6, the biasing member 31 may be composed of an annular guide ring 32 having radial guide pieces 32a on its outer periphery that is laminated on the side opposite the piston of the leaf valve 2, an annular shim 33 that is in sliding contact with the outer periphery of the guide pieces 32a of the guide ring 32 and is aligned with the leaf valve 2, laminated on the side opposite the piston of the outer ring 2b, and has a thickness in the axial direction that is thicker than that of the guide ring 32, and an elastic annular plate 34 that is laminated on the side opposite the piston of the guide ring 32 and shim 33. The biasing member 31 configured in this manner can bias the outer ring 2b of the leaf valve 2 toward the valve seat 1e by the elastic force exerted by the annular plate 34, which is deflected by the shim 33, and since its axial length is much shorter than that of the conical coil spring 3, the overall axial length of the check valve V can be shortened, making it easier to install it in a shock absorber D, etc.
[0073] 7, the biasing member 35 may be integral with the leaf valve 2 by a plurality of spring pieces 35a extending radially and obliquely from the outer periphery of the outer ring 2b of the leaf valve 2 toward the inner ring 2a. Specifically, a blank made of a thin, flat metal plate is punched to obtain a metal piece in which the spring pieces 35a of the biasing member 35 are connected to the outer periphery of the outer ring 2b of the leaf valve 2, and the portions of the metal piece corresponding to the spring pieces 35a are bent to obtain the leaf valve 2 integrated with the biasing member 35.
[0074] When the biasing member 35 is integrated into the leaf valve 2 in this manner, the assembly of the check valve V becomes easier, and the magnitude of the biasing force applied to the leaf valve 2 and the position at which it acts can be adjusted freely in the circumferential direction by setting the installation location of the spring pieces 35a and the spring constant of each spring piece 35a.
[0075] In the check valve V of this embodiment, the inner periphery of the leaf valve 2 is fixed to the inner periphery seat portion 1f by the collar 4a of the spring bearing 4. When the inner periphery of the leaf valve 2 is fixed to the inner periphery seat portion 1f in this manner, the inner periphery of the leaf valve 2 does not move relative to the rod 11 inserted into the inner periphery of the leaf valve 2, and stick-slip does not occur at all between the inner periphery of the leaf valve 2 and the rod 11, thereby effectively suppressing the generation of abnormal noise. Note that even if the check valve V is configured so that the leaf valve 2 can move entirely in the axial direction from the piston 1 serving as the valve seat member by slidably fitting the leaf valve 2 onto the collar 4a of the spring bearing 4 or the outer periphery of the rod 11, the leaf valve 2 operates so that the entire outer periphery of the leaf valve 2 moves away from the piston 1 after it has moved away from the valve seat 1e and flattened, making it less likely that stick-slip will occur between the leaf valve 2 and components inserted into the inner periphery of the leaf valve 2, such as the collar 4a or the rod 11, thereby suppressing the generation of abnormal noise.
[0076] In the above description, the piston 1 is used as the valve seat member, but the valve case 14 may be used as the valve seat member, and the check valve V may be applied to the suction passage 14f of the valve case 14. Furthermore, the check valve V is a valve that sets the port in the valve seat member to one-way and provides almost no resistance to the flow of liquid passing through it, and it goes without saying that it can be used in various hydraulic equipment other than the shock absorber D.
[0077] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]
[0078] 1···Piston (valve seat member), 1c···Compression side port (port), 1e···Valve seat, 1f···Inner peripheral seat portion, 2···Leaf valve, 2a···Inner ring, 2b···Outer ring, 2c···Arm, 3···Conical coil spring (biasing member), 31, 35···Body biasing member, V···Check valve
Claims
1. a valve seat member including a port, an annular valve seat disposed on an outer periphery of an outlet end of the port and surrounding the port, and an annular inner circumferential seat portion disposed on an inner periphery of the outlet end of the port; a leaf valve having an annular shape, an inner periphery of which is overlapped with the inner periphery seat portion and whose outer periphery is allowed to deform so as to be seated on and separated from the valve seat; a biasing member that biases the leaf valve toward the valve seat member, The height of the valve seat in the axial direction of the valve seat member is lower than that of the inner peripheral seat portion. A check valve characterized by:
2. The leaf valve has non-uniform rigidity in the circumferential direction.
2. The check valve according to claim 1.
3. The inner periphery of the leaf valve is fixed to the inner periphery seat portion.
2. The check valve according to claim 1.
4. The leaf valve is an inner ring that is superimposed on the inner circumferential sheet portion; an outer ring disposed on an outer peripheral side of the inner ring and capable of closing an outlet end of the port when seated on the valve seat; one or more arms connecting the inner and outer rings 3. The check valve according to claim 2.
5. The leaf valve is The arms are located only within a 180-degree range in the circumferential direction.
4. The check valve according to claim 3.
6. The leaf valve is having only one arm 4. The check valve according to claim 3.
Citation Information
Patent Citations
Piston check valve structure of hydraulic shock absorber
JP1994069476U