Valve device

Abstract

To provide a valve device capable of generating stable damping force. [Solution] The valve device V1 of the present invention comprises a valve seat member 1 having a port 1c and an annular valve seat 1e arranged on the outer circumference of the outlet end of the port 1c and surrounding the port 1c; an annular leaf valve 2 whose inner circumference is fixed and whose outer circumference is allowed to bend, and which can seat on and off the valve seat 1e; a biasing member 3 that biases the leaf valve 2 toward the valve seat member 1; and a valve stopper 4 provided on the side of the biasing member 3 opposite the leaf valve, which restricts the bending of the leaf valve 2 when the outer circumference of the leaf valve 2 bends and contacts the valve stopper 4. The biasing member 3 is configured to contact the valve stopper 4 between the state in which the outer circumference of the leaf valve 2 is seated on the valve seat 1e and the state in which it contacts the valve stopper 4.

Description

Technical Field

[0001] The present invention relates to a valve device.

Background Art

[0002] A valve device is used, for example, in a piston portion of a shock absorber that is interposed between a vehicle body and a wheel in a vehicle and generates a damping force when expanding and contracting. Specifically, such a damping valve includes an annular leaf valve disposed on the extension chamber side of a piston that is housed in a shock absorber and partitions the inside of a cylinder into an extension chamber and a compression chamber as a valve seat member, a spring that biases the leaf valve toward the piston, and a valve stopper provided on the side of the spring opposite to the leaf valve. The valve seat surrounds a port provided in the piston and opens and closes the port by separating from and seating on the annular valve seat (see, for example, Patent Document 1).

[0003] When the shock absorber contracts, the valve device receives the pressure of the compression chamber acting through the port, allows the leaf valve to separate from the valve seat and open, and permits the flow of hydraulic oil from the compression chamber to the extension chamber. If it is desired to provide resistance to the flow of hydraulic oil by the valve device during valve opening, the biasing force of the spring may be increased.

[0004] In a conventional valve device, the spring is a star-shaped spring having an annular fixing portion laminated on the back side of the leaf valve via a spacer and a leg portion that functions as a spring inclined from the fixing portion toward the leaf valve. Therefore, when generating a damping force by the valve device during valve opening, an initial deflection may be given to the leg portion in advance to bias the leaf valve. [[ID=!]]

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In conventional valve devices, as mentioned above, damping force can be generated by increasing the biasing force of the spring. However, since the spring legs are not supported in any way, there is a risk that the leaf valve will vibrate finely when it flexes and opens, causing the damping force to become unstable.

[0007] Therefore, the present invention aims to provide a valve device capable of generating a stable damping force. [Means for solving the problem]

[0008] To solve the aforementioned problems, the valve device of the present invention comprises a valve seat member having a port and an annular valve seat arranged on the outer circumference of the outlet end of the port and surrounding the port; an annular leaf valve whose inner circumference is fixed and whose outer circumference is allowed to bend, and which can seat on and off the valve seat; a biasing member that biases the leaf valve toward the valve seat member; and a valve stopper provided on the side of the biasing member opposite the leaf valve, which restricts the bending of the leaf valve when the outer circumference of the leaf valve bends and contacts the valve stopper, wherein the biasing member contacts the valve stopper between the state in which the outer circumference of the leaf valve is seated on the valve seat and the state in which it contacts the valve stopper.

[0009] With a valve device configured in this way, the biasing member is supported by contacting the valve stopper, and vibrations of the leaf valve and the biasing member are suppressed, thereby suppressing the fine vibrations of the leaf valve when it bends and opens.

[0010] Furthermore, the biasing force of the biasing member in the valve device may change when it comes into contact with the valve stopper. With a valve device configured in this way, when the deflection of the leaf valve increases, the biasing member comes into contact with and is supported by the valve stopper, and the spring stiffness of the biasing member appears to increase, so that the fine vibration of the leaf valve when it deflects and opens can be effectively suppressed. In addition, with a valve device configured in this way, the biasing force of the biasing member that biases the leaf valve can be changed, so that the damping force can be changed in multiple stages before and after the biasing member comes into contact with the valve stopper and before and after the leaf valve comes into contact with the valve stopper.

[0011] Furthermore, the biasing member in the valve device may contact the valve stopper while the outer circumference of the leaf valve is bending and contacting the valve stopper. With a valve device configured in this way, when the bending of the leaf valve increases, the biasing member contacts and supports the valve stopper, suppressing vibrations of the leaf valve and the biasing member. This suppresses the fine vibrations of the leaf valve when it bends and opens.

[0012] Furthermore, the valve seat member in the valve device has an outer port positioned on the outer circumference of the valve seat and an annular outer valve seat positioned on the outer circumference of the outlet end of the outer port and surrounding the outer port, and the leaf valve in the valve device may be able to seat and detach from the outer valve seat together with the valve seat. With a valve device configured in this way, when the deflection of the leaf valve increases, an annular gap is created not only between the leaf valve and the outer valve seat, but also between the leaf valve and the valve seat, allowing the passage of liquid. Therefore, the damping force can be changed in multiple stages before and after the biasing member contacts the valve stopper, before and after the leaf valve contacts the valve stopper, and before and after the leaf valve separates from the valve seat.

[0013] Furthermore, the valve seat member in the valve device may have an annular inner valve seat positioned on the inner circumference of the outlet end of the port, and the leaf valve in the valve device may be able to seat and detach from the inner valve seat together with the valve seat. With a valve device configured in this way, when the deflection of the leaf valve increases, an annular gap is created not only between the leaf valve and the valve seat, but also between the leaf valve and the inner valve seat, allowing the passage of liquid. Thus, the damping force can be changed in multiple stages, not only before and after the biasing member contacts the valve stopper and before and after the leaf valve contacts the valve stopper, but also before and after the leaf valve separates from the inner valve seat.

[0014] Furthermore, the biasing member in the valve device has an annular fixing portion that is positioned and fixed on the side of the leaf valve that is not the valve seat member, and a plurality of spring portions that extend radially from the outer circumference of the fixing portion and abut against the side surface of the leaf valve that is not the valve seat member. The spring portions have a base end that extends from the outer circumference of the fixing portion in a direction away from the leaf valve, and a tip that bends and extends from the tip of the base end in a direction approaching the leaf valve and abuts against the side end of the leaf valve that is not the valve seat member. The bent portion between the base end and the tip may abut against the valve stopper.

[0015] With this valve device configuration, the spring portion is shaped to be convex toward the valve stopper, so even if the deflection of the leaf valve is small, the bent portion can contact the valve stopper and support the spring portion, thereby stabilizing the damping force. Furthermore, with this valve device, because the spring portion is shaped to be convex toward the valve stopper, when the bent portion contacts and is supported by the valve stopper, only the tip portion is effective as a spring, so the biasing force that biases the leaf valve can be easily adjusted by setting the spring constant of only the tip portion.

[0016] Furthermore, the bending stiffness of the base end of the spring portion of the biasing member may differ from the bending stiffness of the tip portion of the spring member. In a valve device configured in this way, the degree of freedom in setting the spring constant of the spring portion before and after the bent portion contacts the valve stopper is increased. By lowering the bending stiffness of the base end and increasing the bending stiffness of the tip portion, the base end becomes more flexible together with the leaf valve, the bent portion quickly contacts the valve stopper, and fine vibrations of the leaf valve are more easily suppressed.

[0017] Furthermore, the spring portion of the biasing member may have a curved portion at the tip of its end that curves toward the side opposite the leaf valve and contacts the leaf valve. With a valve device configured in this way, since the spring portion has a curved portion that contacts the leaf valve, even if the leaf valve flexes and the contact portion where the curved portion contacts the leaf valve changes, the curved portion slides smoothly on the side of the leaf valve opposite the piston, without hindering the flexing of the leaf valve, and thus the smooth flexing of the leaf valve can be guaranteed. [Effects of the Invention]

[0018] According to the valve device of the present invention, a stable damping force can be generated. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a longitudinal cross-sectional view of a buffer to which the valve device of the first embodiment of the present invention is applied. [Figure 2] Figure 2 is an enlarged cross-sectional view of a valve device according to the first embodiment of the present invention. [Figure 3] Figure 3 is a plan view of the biasing member in a valve device according to the first embodiment of the present invention. [Figure 4] Figure 4 is an enlarged cross-sectional view of a valve device according to the first embodiment of the present invention, showing the biasing seat in contact with the valve stopper. [Figure 5] Figure 5 is an enlarged cross-sectional view of a valve device according to the first embodiment of the present invention, showing the leaf valve in contact with the valve stopper. [Figure 6]FIG. 6 is a diagram showing the damping force characteristics of a shock absorber to which the valve device of the first embodiment is applied. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a valve device in a modified example of the first embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing the damping force characteristics of a shock absorber to which the valve device of a modified example of the first embodiment is applied. [Figure 9] FIG. 9 is an enlarged cross-sectional view of a valve device of the second embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described based on several embodiments shown in the drawings. As shown in FIG. 1, the valve device V1 in the first 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 stacked on the piston 1, a biasing member 3 for biasing the leaf valve 2, and a valve stopper 4 for restricting the deflection of the leaf valve 2 when the leaf valve 2 deflects and contacts.

[0021] As shown in FIG. 1, the shock absorber D to which the valve device V1 is applied includes a cylinder 10, a rod 11 movably inserted into the cylinder 10, a piston 1 as a valve seat member connected to the rod 11 and axially movably inserted into the cylinder 10 to partition the inside of the cylinder 10 into an extension chamber R1 and a compression chamber R2 as two working chambers, an outer cylinder 12 covering the outer periphery of the cylinder 10 to form a reservoir R for storing liquid in an annular gap between the outer cylinder 12 and the cylinder 10, and the valve device V1. And in the case of this shock absorber D, it is interposed and used between the vehicle body and the axle of a vehicle not shown, and suppresses the vibration of the vehicle body and wheels.

[0022] Hereinafter, each part of the valve device V1 and the shock absorber D will be described in detail. First, each part of the shock absorber D will be described. The cylinder 10 is cylindrical, and an annular rod guide 13 is fitted to the upper end in FIG. 1, and a disk-shaped valve case 14 is fitted to the lower end in FIG. 1, and it is housed in a bottomed cylindrical outer cylinder 12.

[0023] Furthermore, an annular sealing member 15 is stacked above the rod guide 13 in Figure 1. The outer cylinder 12 is a bottomed cylindrical shape and has a crimped portion 12a formed by crimping the upper end toward the inner circumference, and the sealing member 15, rod guide 13, cylinder 10, and valve case 14 are sandwiched between the crimped portion 12a and the bottom portion 12b.

[0024] The rod 11 is inserted into the cylinder 10 by passing through the inner circumference of the rod guide 13, with its upper end protruding outside the cylinder 10 in Figure 1. The rod guide 13 is annular in shape and is fitted to the inner circumference of the upper end of the cylinder 10 in Figure 1, while its outer circumference is fitted to the inner circumference of the upper end of the outer cylinder 12. It is equipped with a cylindrical bush 13a on its inner circumference that slides against the outer circumference of the rod 11.

[0025] The rod 11 is guided by the rod guide 13 to move axially relative to the cylinder 10, allowing it to enter and exit the cylinder 10 without wobbling. The sealing member 15 has a sealing lip 15a on its inner circumference that slides against the outer circumference of the rod 11, and an annular sealing ring 15b on its outer circumference that is in close contact with the inner circumference of the outer cylinder 12 and the outer circumference of the upper end of the rod guide 13, thereby preventing leakage of liquid from inside the cylinder 10 and the outer cylinder 12 to the outside.

[0026] The rod 11 has a small-diameter portion 11a at its tip, which is the lower end in Figure 1, the outer diameter of which is smaller than that of the upper end, a threaded portion 11b formed on the outer circumference of the lower end of the small-diameter portion 11a, and a stepped portion 11c formed between the small-diameter portion 11a and the upper side of the small-diameter portion 11a. An annular piston 1 is mounted on the outer circumference of the small-diameter portion 11a of the rod 11.

[0027] When the rod 11 is inserted into the cylinder 10 via the inner circumference of the rod guide 13, the piston 1 attached to the rod 11 slides against the inner circumference of the cylinder 10, and the inside of the cylinder 10 is divided by the piston 1 into an extension chamber R1 in the upper part of Figure 1 and a compression chamber R2 in the lower part of Figure 1. The extension chamber R1 and the compression chamber R2 inside the cylinder 10 are filled with a liquid such as hydraulic oil. In addition, a reservoir R formed between the cylinder 10 and the outer cylinder 12 stores liquid and gas. The liquid stored inside the cylinder 10 and in the reservoir R may be water, an aqueous solution, or other liquids in addition to hydraulic oil. When a liquid is used as hydraulic oil, the gas filled in the reservoir R may be an inert gas such as nitrogen, but other gases or air may also be used.

[0028] Furthermore, a bracket (not shown) is provided at the base end of the rod 11, which is the upper end in Figure 1, and the rod 11 is connected to one of the vehicle body and the axle via the aforementioned 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 aforementioned bracket (not shown).

[0029] In this way, the shock absorber D is interposed between the vehicle body and the axle. When the vehicle travels on an uneven road surface, causing the wheels to vibrate vertically relative to the vehicle body, the rod 11 moves in and out of the cylinder 10, causing the shock absorber D to expand and contract, and the piston 1 moves vertically (axially) within the cylinder 10.

[0030] As shown in Figures 1 and 2, the piston 1, which serves as the valve seat member, is annular in shape and fitted onto the outer circumference of the small-diameter portion 11a of the rod 11. It is fixed to the rod 11 by a piston nut 16 that is screwed onto the threaded portion 11b of the rod 11.

[0031] More specifically, the piston 1 comprises an annular main body portion 1a with a piston ring 1b mounted on its outer circumference, a plurality of compression ports 1c provided on the main body portion 1a, which open from the lower end in Figure 2 of the main body portion 1a and lead to the outer circumference of the upper end in Figure 2, an extension port 1d provided on the main body portion 1a, which opens from the upper end in Figure 2 and leads to the outer circumference of the lower end in Figure 2, a valve seat 1e provided on the main body portion 1a and positioned on the outer circumference of the upper end in Figure 2, which is the outlet end of the compression ports 1c, and surrounding the compression ports 1c, and an annular inner valve seat 1j provided on the main body portion 1a and positioned on the inner circumference side of the outlet end of the compression ports 1c.

[0032] As described above, the main body 1a is annular in shape, and a piston ring 1b mounted on its outer circumference slides against the inner circumference of the cylinder 10, dividing the inside of the cylinder 10 into an extension chamber R1 and a compression chamber R2. Furthermore, at the upper end of the main body 1a in Figure 2, there is an annular recessed window 1g through which the outlet ends of the compression port 1c (which are the upper ends in Figure 2) are connected, and an annular groove 1h is provided on the inner circumference of the annular window 1g. The valve seat 1e is provided so as to surround the outer circumference of the annular window 1g, and the inner valve seat 1j is provided between the annular window 1g and the annular groove 1h and is located on the inner circumference side of the compression port 1c. In addition, an annular inner circumferential seat portion 1f is provided on the inner circumference side of the annular groove 1h of the main body 1a. Moreover, as shown in Figure 2, the main body 1a is provided with an annular extension valve seat 1i that protrudes from the lower end and is located on the outer circumference side of the extension port 1d.

[0033] The compression port 1c, acting as a port, opens at the upper end of the main body 1a in Figure 2, between the inner valve seat 1j and the valve seat 1e, extends downward along the axial direction of the piston 1, and opens at the lower end of the main body 1a in Figure 2, on the outer circumference of the extension valve seat 1i, connecting the extension chamber R1 and the compression chamber R2. Eight compression ports 1c are provided at equal intervals around the main body 1a. The compression ports 1c are compression ports that allow liquid to flow from the compression chamber R2 to the extension chamber R1 when the buffer D is contracting.

[0034] The valve seat 1e is located at the upper end of the main body 1a in Figure 2 and is formed by an annular projection that protrudes upward from the upper end of the main body 1a, surrounding the outer circumference of the pressure port 1c, and the leaf valve 2 in the valve device V1 sits on and off the upper end of the valve seat 1e. As described above, the valve seat 1e is an annular valve seat arranged on the outer circumference of the pressure ports 1c which are arranged in a circumferential direction, but it may also be a petal-shaped valve seat that individually surrounds the pressure ports 1c.

[0035] On the other hand, the inner valve seat 1j is located at the upper end of the main body 1a in Figure 2 and is formed by an annular projection that protrudes upward from the upper end between the annular window 1g and the annular groove 1h of the main body 1a, surrounding the inner circumference of the compression port 1c, and the leaf valve 2 in the valve device V1 sits on and off its upper end.

[0036] Furthermore, the inner circumferential seat portion 1f is provided at the upper end of the main body portion 1a in Figure 2, and is formed by an annular projection that protrudes upward from the upper end of the main body portion 1a, and is positioned on the inner circumference of the compression port 1c, and has a flat seat surface at its upper end on which the inner circumference of the leaf valve 2 in the valve device V1 is seated.

[0037] Eight extension ports 1d are provided at equal intervals in the circumferential direction relative to the main body 1a. They open from the inner circumferential side of the extension valve seat 1i at the lower end of the main body 1a in Figure 2, extend upward along the axial direction of the piston 1, and open into the annular groove 1h at the upper end of the main body 1a in Figure 2, connecting the extension chamber R1 and the compression chamber R2.

[0038] Furthermore, the compression port 1c can be modified in shape and structure as long as its upper end in Figure 2 opens between the valve seat 1e and the inner circumferential seat portion 1f of the main body 1a, and its lower end opens on the outer circumference side of the extension valve seat 1i of the main body 1a, thereby enabling communication between the extension chamber R1 and the compression chamber R2. The extension port 1d may also be provided so that its upper end in Figure 2 opens on the outer circumference side of the valve seat 1e of the main body 1a, and its shape and structure can be modified as long as it enables communication between the extension chamber R1 and the compression chamber R2. Moreover, the number of compression ports 1c and extension ports 1d is not limited to eight.

[0039] Next, a laminated leaf valve 17 is stacked on top of the piston 1 in the lower part of Figure 2. The laminated leaf valve 17 is made up of multiple annular plates stacked together and is fitted together with the piston 1 to the outer circumference of the small diameter portion 11a of the rod 11 and fixed to the small diameter portion 11a by the piston nut 16. In this way, the laminated leaf valve 17 fixed to the small diameter portion 11a of the rod 11 has its inner circumference fixed to the small diameter portion 11a, and its outer circumference seats on the extension valve seat 1i, while allowing the outer circumference to flex. Therefore, when the rod 11 moves upward in Figure 1 relative to the cylinder 10, and the pressure in the extension chamber R1 acting through the extension port 1d rises to reach the valve opening pressure, the laminated leaf valve 17 flexes its outer circumference, separating it from the extension valve seat 1i, allowing the liquid to flow from the extension chamber R1 to the compression chamber R2 through the extension port 1d, while also providing resistance to the liquid flow. Furthermore, when the rod 11 moves downward in Figure 1 relative to the cylinder 10, the stacked leaf valve 17 seats its outer circumference on the extension valve seat 1i, closing the extension port 1d and preventing the liquid from flowing from the compression chamber R2 to the extension chamber R1 through the extension port 1d.

[0040] The valve device V1 comprises a piston 1 as a valve seat member configured as described above, a leaf valve 2 which is annular in shape with its inner circumference overlapping the inner seat portion 1f of the piston 1 and allowing deflection on its outer circumference so that it can seat on and off the inner valve seat 1j and valve seat 1e, a biasing member 3 which is positioned on the side of the leaf valve 2 opposite the piston and biases the leaf valve 2 toward the piston 1, and a valve stopper 4 which is positioned on the side of the biasing member 3 opposite the leaf valve.

[0041] As shown in Figure 2, the leaf valve 2 is annular in shape and is superimposed on the seat surface of the inner circumferential seat portion 1f of the piston 1, the inner valve seat 1j, and the valve seat 1e, which serve as the valve seat member.

[0042] More specifically, the leaf valve 2 is stacked above the piston 1 in Figure 2 and fitted onto the outer circumference of the small-diameter portion 11a of the rod 11, and is fixed to the small-diameter portion 11a by the piston nut 16. The leaf valve 2 also has a hole 2a facing the annular groove 1h which leads to the extension port 1d, and even when seated on the inner valve seat 1j and valve seat 1e, the extension port 1d is always in communication with the extension chamber R1 via the hole 2a.

[0043] The leaf valve 2 has its inner circumference fixed immovably to the inner circumference seat portion 1f, allowing for deflection of the outer circumference. When the outer circumference is deflected and the valve opens by separating from the valve seat 1e, the pressure port 1c communicates with the pressure chamber R2 through the annular gap between it and the valve seat 1e, allowing liquid to flow through the pressure port 1c from the pressure chamber R2 to the extension chamber R1, while also providing resistance to this liquid flow. Furthermore, when the amount of deflection of the outer circumference of the leaf valve 2 increases and it separates from the inner valve seat 1j, the pressure port 1c communicates with the extension chamber R1 through the gap between it and the inner valve seat 1j and through the hole 2a, allowing liquid to flow through the pressure port 1c from the pressure chamber R2 to the extension chamber R1, while also providing resistance to this liquid flow, and increasing the degree of communication between the pressure port 1c and the extension chamber R1.

[0044] A biasing member 3 is superimposed on the side of the leaf valve 2 opposite the piston. As shown in Figures 2 and 3, the biasing member 3 comprises an annular fixing portion 31 that is positioned and fixed on the side of the leaf valve 2 opposite the piston, and five spring portions 32 that extend radially from the outer circumference of the fixing portion 31 and contact the side surface of the leaf valve 2 opposite the piston.

[0045] The fixing portion 31 is annular in shape and is superimposed on the inner circumference of the leaf valve 2 on the side opposite the piston. Together with the leaf valve 2, it is fitted onto the outer circumference of the small diameter portion 11a of the rod 11 and fixed to the small diameter portion 11a by the piston nut 16. Therefore, the leaf valve 2 can bend its outer circumference using the outer edge of the fixing portion 31 as a fulcrum.

[0046] The spring portion 32 includes a base end portion 32a extending from the outer circumference of the fixed portion 31 in a direction away from the leaf valve 2, a tip portion 32b extending from the tip of the base end portion 32a in a direction approaching the leaf valve 2 and contacting the end of the leaf valve 2 on the side opposite the piston, a bent portion 32c between the base end portion 32a and the tip portion 32b, and a curved portion 32d at the tip of the tip portion 32b having a curved surface that curves toward the side opposite the leaf valve and contacts the leaf valve 2.

[0047] When the fixed portion 31 of the biasing member 3 configured in this way is placed on the inner circumference of the leaf valve 2 on the side opposite the piston, the base end portion 32a of the spring portion 32 is tilted upward in Figure 2, and the entire portion is separated from the side of the leaf valve 2 on the side opposite the piston. The tip portion 32b, which is connected to the tip of the base end portion 32a, is bent at the bent portion 32c and tilts toward the leaf valve 2, so that the curved portion 32d at the tip comes into contact with the outer circumference of the leaf valve 2 on the side opposite the piston.

[0048] Therefore, the biasing member 3 has its fixed portion 31 and curved portion 32d in contact with the leaf valve 2, and the portion between the base end 32a and the curved portion 32d of the tip 32b is separated from the leaf valve 2. The spring portion 32 of the biasing member 3 is given an initial deflection when the leaf valve 2 is not deflected and is seated on the inner valve seat 1j and valve seat 1e, and generates a biasing force that presses the leaf valve 2 toward the piston 1, which is a valve seat member, with the curved portion 32d, which is in contact with the side of the leaf valve 2 opposite the piston, as the point of force application. When the outer circumference of the leaf valve 2 deflects, the entire spring portion 32 deflects, increasing the biasing force that presses the leaf valve 2 toward the piston 1. Furthermore, the initial deflection applied to the biasing member 3 can be arbitrarily adjusted according to the damping force characteristics generated by the valve device V1. When the leaf valve 2 is not deflected and is seated on the inner valve seat 1j and valve seat 1e, the spring portion 32 in the biasing member 3 can be made not to deflect, thereby preventing the leaf valve 2 from being biased.

[0049] On the side of the biasing member 3's fixing portion 31 that is not on the leaf valve side, annular spacers 5 and 6 are stacked, and a valve stopper 4 is stacked further above the upper spacer 6 in Figure 2. The spacers 5 and 6 are fitted onto the outer circumference of the small diameter portion 11a of the rod 11 and are fixed to the small diameter portion 11a by a piston nut 16. Furthermore, the outer diameter of the spacers 5 and 6 is less than or equal to the outer diameter of the fixing portion 31 so as not to hinder the elastic deformation of the spring portion 32 in the biasing member 3.

[0050] The valve stopper 4 is annular in shape and includes an annular valve retaining portion 4a that protrudes from the outer circumference toward the leaf valve side, and a plurality of through holes 4b provided on the inner circumference side of the valve retaining portion 4a. The valve stopper 4 is superimposed on the upper part of the spacer 6 in Figure 2, fitted onto the outer circumference of the small diameter portion 11a of the rod 11, and fixed to the outer circumference of the small diameter portion 11a by the piston nut 16. Alternatively, the through holes 4b may be provided in a position where the bent portion 32c of the biasing member 3 does not overlap with the valve stopper 4 when viewed from the axial direction, or the valve stopper 4 and the biasing member 3 may be assembled by positioning them in the circumferential direction so that the through holes 4b and the bent portion 32c do not face each other.

[0051] When the leaf valve 2 is not bent and is seated on the inner valve seat 1j and valve seat 1e, an initial gap is created between the leaf valve side on the inner circumference side of the valve stopper 4's valve retaining portion 4a and the bent portion 32c of the biasing member 3. However, when the outer circumference of the leaf valve 2 bends and moves away from the valve seat 1e, as shown in Figure 4, the spring portion 32 of the biasing member 3 also bends together with the leaf valve 2, and the bent portion 32c comes into contact with the lower surface of the valve stopper 4.

[0052] As the leaf valve 2 bends further from the state where the bent portion 32c of the spring portion 32 is in contact with the lower surface of the valve stopper 4, only the tip portion 32b of the spring portion 32 is supported by the valve stopper 4 at the bent portion 32c and bends, biasing the leaf valve 2 toward the piston. As the bending of the outer circumference of the leaf valve 2 progresses, it moves away from the inner valve seat 1j, and as it bends further, as shown in Figure 5, its outer circumference comes into contact with the valve retaining portion 4a of the valve stopper 4. When the leaf valve 2 comes into contact with the valve retaining portion 4a, the valve stopper 4 restricts the bending of the outer circumference of the leaf valve 2 in the direction away from the piston 1, which is the valve seat member. The vertical length of the initial gap between the valve stopper 4 and the bent portion 32c of the biasing member 3 can be adjusted by the axial length of the combined spacers 5 and 6. In the illustration, two spacers 5 and 6 are interposed between the valve stopper 4 and the fixing portion 31 of the biasing member 3. However, the number of spacers can be arbitrarily changed according to the desired initial gap, and the initial gap may be adjusted with only one spacer. Furthermore, the amount of protrusion of the valve retaining portion 4a of the valve stopper 4 toward the piston can be set according to the maximum deflection amount that should be allowed for the leaf valve 2. If it is not necessary to provide the valve retaining portion 4a, the valve stopper 4 may be made into an annular flat plate and the valve retaining portion 4a may be eliminated.

[0053] In the valve device V1 configured in this way, the piston 1, leaf valve 2, biasing member 3, spacers 5 and 6, and valve stopper 4, which serve as valve seat members, are assembled in order to the outer circumference of the small diameter portion 11a of the rod 11 together with the stacked leaf valve 17. They are then fixed to the rod 11 by being sandwiched between the piston nut 16, which is screw-connected to the threaded portion 11b, and the stepped portion 11c.

[0054] Next, the valve case 14 fitted to the lower end of the cylinder 10 in Figure 1 is disc-shaped and has a main body portion 14a having a fitting portion 14b that fits onto the inner circumference of the cylinder 10 and a large-diameter portion 14c that is connected to the lower end of the fitting portion 14b and has a larger outer diameter than the fitting portion 14b and abuts against the lower end of the cylinder 10 in Figure 1, and a plurality of leg portions 14d that protrude from the outer circumference of the lower end of the large-diameter portion 14c in Figure 1 and are provided at equal intervals in the circumferential direction and abut against the bottom portion 12b of the outer cylinder 12.

[0055] The valve case 14 is held and fixed between the cylinder 10 and the outer cylinder 12, and also partitions the inside of the cylinder 10 and the pressure side chamber R2 from the reservoir R formed between the cylinder 10 and the outer cylinder 12.

[0056] Furthermore, the main body portion 14a of the valve case 14 is provided with a pressure-side damping passage 14e that allows only the flow of liquid from the pressure-side chamber R2 to the reservoir R and provides resistance to the liquid flow, and a suction passage 14f that allows only the flow of liquid from the reservoir R to the pressure-side chamber R2 and provides almost no resistance to the liquid flow. The space between the main body portion 14a of the valve case 14 and the bottom portion 12b of the outer cylinder 12 is connected to the reservoir R via the legs 14d, 14d, so that communication between the pressure-side chamber R2 and the reservoir R is ensured via the pressure-side damping passage 14e and the suction passage 14f.

[0057] In the buffer D configured in this way, when the rod 11 moves upward in Figure 1 relative to the cylinder 10, the upward movement of the piston 1 in Figure 1 causes the liquid in the compressed extension chamber R1 to flex the stacked leaf valve 17, separating it from the extension valve seat 1i, and move into the compression chamber R2 through the through hole 4b of the valve stopper 4, the hole 2a of the leaf valve 2, and the extension port 1d. The stacked leaf valve 17 provides resistance to this liquid flow, causing the pressure in the extension chamber R1 to rise. On the other hand, liquid is supplied to the expanding compression chamber R2 from the reservoir R via 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 compression chamber R2 becomes approximately equal to the pressure in the reservoir R. In the valve device V1, the leaf valve 2 is biased by the biasing member 3 because the pressure in the extension chamber R1 is higher than the pressure in the compression chamber R2, and it is in close contact with the inner valve seats 1j and 1e, thereby blocking the compression port 1c which acts as a port and preventing the flow of liquid.

[0058] Therefore, when the shock absorber D extends, the stacked leaf valve 17 resists the flow of liquid from the extension chamber R1 to the compression chamber R2, increasing the pressure in the extension chamber R1 and generating an extension damping force that prevents the piston 1 from moving upward in Figure 1 relative to the cylinder 10.

[0059] On the other hand, when the shock absorber D is in a contraction operation, with the rod 11 moving downward in Figure 1 relative to the cylinder 10, the downward movement of the piston 1 in Figure 1 increases the pressure in the compressed compression chamber R2. When the force pressing the leaf valve 2 by the pressure in the compression chamber R2 exceeds the biasing force of the biasing member 3, the leaf valve 2 in the valve device V1 bends and opens, separating from the valve seat 1e, allowing the liquid to pass through the compression port 1c, which acts as a port, and move from the compression chamber R2 to the extension chamber R1, while providing resistance to the flow of the liquid. Therefore, when the shock absorber D is in a contraction operation, the pressure in the compression chamber R2 becomes higher than the pressure in the extension chamber R1 due to the valve device V1.

[0060] Furthermore, when the piston speed during the contraction operation of the shock absorber D is in the very low speed range, although the outer circumference of the leaf valve 2 flexes, the bent portion 32c of the spring portion 32 of the biasing member 3 does not come into contact with the valve stopper 4, and the entire spring portion 32 flexes together with the leaf valve 2, biasing the leaf valve 2 toward the piston 1. The tip of the tip portion 32b of the spring portion 32 of the biasing member 3 is provided with a curved portion 32d having a curved surface that comes into contact with the side surface of the leaf valve 2 opposite the piston. Even if the leaf valve 2 flexes and the contact portion of the curved portion 32d that comes into contact with the leaf valve 2 changes, the curved portion 32d can slide smoothly on the side surface of the leaf valve 2 opposite the piston, so as not to hinder the flexing of the leaf valve 2, the smooth flexing of the leaf valve 2 can be guaranteed.

[0061] Furthermore, when the shock absorber D contracts, the rod 11 enters the cylinder 10, resulting in an excess of liquid in the cylinder 10 equal to the volume of the rod 11 that enters the cylinder 10. This excess liquid is discharged to the reservoir R via the pressure-side damping passage 14e provided in the valve case 14. The pressure-side damping passage 14e then resists the flow of liquid from the pressure-side chamber R2 to the reservoir R, so the pressure inside the cylinder 10 increases when the shock absorber D contracts.

[0062] In this manner, when the shock absorber D is in a contracted state and the piston speed during the contraction of the shock absorber D is in the very low speed range, the shock absorber D generates a damping force through the valve device V1 and the compression damping passage 14e. However, because the entire spring portion 32 of the biasing member 3 is deflected, the biasing force of the biasing member 3 that biases the leaf valve 2 is small. As a result, the damping force characteristics in the shock absorber D are such that the damping force increases with the piston speed, but the rate of increase in damping force is small, as shown in Figure 6.

[0063] When the piston speed of the shock absorber D in the contraction direction exceeds the very low speed range and reaches the low speed range, the deflection of the outer circumference of the leaf valve 2 increases, and the bent portion 32c of the spring portion 32 comes into contact with the valve stopper 4. The leaf valve 2 separates from the valve seat 1e, but either comes into contact with the inner valve seat 1j or, even if separated, only a small gap is created between it and the inner valve seat 1j. Therefore, most of the liquid passing through the pressure-side port 1c passes through the annular gap between the leaf valve 2 and the valve seat 1e. When the bent portion 32c of the spring portion 32 comes into contact with the valve stopper 4, the bent portion 32c is supported by the valve stopper 4, and the tip portion 32b of the spring portion 32 begins to deflect with the bent portion 32c as the fulcrum. As a result, the spring constant of the biasing member 3 appears to increase, and the degree of increase in the biasing force of the biasing member 3 relative to the amount of deflection of the leaf valve 2 increases. Therefore, when the piston speed during the compression operation of the shock absorber D is in the low-speed range, the damping force characteristics of the shock absorber D, as shown in Figure 6, show a greater degree of increase in damping force with respect to piston speed compared to when the piston speed is in the very low-speed range.

[0064] Furthermore, when the piston speed of the shock absorber D in the contraction direction exceeds the low speed range and reaches the medium speed range, both the deflection of the outer circumference of the leaf valve 2 and the deflection of the tip 32b of the spring portion 32 increase. As a result, the leaf valve 2 is separated from both the valve seat 1e and the inner valve seat 1j to a sufficient extent for liquid to pass through. Consequently, the liquid moves from the compression chamber R2 to the extension chamber R1 not only through the annular gap between the leaf valve 2 and the valve seat 1e, but also through the annular gap and hole 2a between the leaf valve 2 and the inner valve seat 1j. Thus, when the piston speed during the contraction operation of the shock absorber D is in the medium speed range, the flow path area in the valve device V1 increases. Therefore, as shown in Figure 6, the damping force characteristics in the shock absorber D show a smaller increase in damping force with respect to piston speed compared to when the piston speed is in the low speed range.

[0065] Furthermore, when the piston speed of the shock absorber D in the contraction direction exceeds the medium speed range and reaches the high speed range, both the deflection of the outer circumference of the leaf valve 2 and the deflection of the tip 32b of the spring portion 32 increase, causing the outer circumference of the leaf valve 2 to come into contact with the valve retaining portion 4a of the valve stopper 4, and further deflection of the leaf valve 2 is restricted by the valve stopper 4.

[0066] Thus, when the piston speed during the contraction operation of the shock absorber D is in the high-speed range, the flow path area in the valve device V1 does not increase and remains constant. Therefore, as shown in Figure 6, the damping force characteristics of the shock absorber D show a greater degree of increase in damping force with respect to piston speed compared to when the piston speed is in the medium-speed range. Furthermore, if the valve retaining portion 4a is eliminated, the maximum amount of deflection that the leaf valve 2 can be allowed to be increases, which can reduce the slope of the damping force characteristics in the high-speed range of piston speed, as described later.

[0067] Furthermore, as the deflection of the leaf valve 2 increases, the bent portion 32c of the spring portion 32 in the biasing member 3 comes into contact with the valve stopper 4. When the spring portion 32 is supported by the valve stopper 4, only the tip portion 32b becomes effective as a spring. This appears to increase the spring rigidity of the biasing member 3, and also suppresses vibrations of the spring portion 32. As a result, the fine vibrations of the leaf valve 2 when it deflects and opens can be suppressed. Therefore, in the valve device V1 of the first embodiment, fine vibrations of the leaf valve 2 can be suppressed and a stable damping force can be generated.

[0068] As described above, the valve device V1 of the first embodiment comprises a piston (valve seat member) 1 having a compression port (port) 1c and an annular valve seat 1e arranged on the outer circumference of the outlet end of the compression port (port) 1c and surrounding the compression port (port) 1c; a leaf valve 2 which is annular and has its inner circumference fixed, with its outer circumference allowed to bend, and is capable of seating on and off the valve seat 1e; a biasing member 3 which biases the leaf valve 2 toward the piston (valve seat member) 1; and a valve stopper 4 provided on the side of the biasing member 3 opposite the leaf valve, which restricts the bending of the leaf valve 2 when the outer circumference of the leaf valve 2 bends and contacts the valve stopper 4. The biasing member 3 is configured to contact the valve stopper 4 between the state in which the outer circumference of the leaf valve 2 is seated on the valve seat 1e and the state in which it contacts the valve stopper 4.

[0069] With the valve device V1 configured in this way, the biasing member 3 is supported by contacting the valve stopper 4, so vibrations of the leaf valve 2 and the biasing member 3 are suppressed, and fine vibrations of the leaf valve 2 when the leaf valve 2 bends and opens are suppressed.

[0070] Furthermore, the biasing member 3 in the valve device V1 of the first embodiment is configured to contact the valve stopper 4 while the outer circumference of the leaf valve 2 is bending and contacting the valve stopper 4.

[0071] With the valve device V1 configured in this way, when the deflection of the leaf valve 2 increases, the biasing member 3 contacts and is supported by the valve stopper 4, and vibrations of the leaf valve 2 and the biasing member 3 are suppressed. Therefore, when the leaf valve 2 deflects and opens, fine vibrations of the leaf valve 2 can be suppressed. Thus, the valve device V1 of the first embodiment can generate a stable damping force.

[0072] In this configuration, the bent portion 32c of the biasing member 3 contacts the valve stopper 4 after the outer circumference of the leaf valve 2 has bent. However, the biasing member 3 may contact the valve stopper 4 in advance while the leaf valve 2 is seated on the valve seat 1e, and be supported by the valve stopper 4. Even if the biasing member 3 contacts the valve stopper 4 in advance while the leaf valve 2 is seated on the valve seat 1e, and is supported by the valve stopper 4, vibrations of the leaf valve 2 and the biasing member 3 are suppressed, thereby preventing the leaf valve 2 from vibrating finely when it bends and opens.

[0073] Furthermore, in the valve device V1 of the first embodiment, the biasing member 3 changes the biasing force that biases the leaf valve 2 when it comes into contact with the valve stopper 4. With the valve device V1 configured in this way, when the deflection of the leaf valve 2 increases, the biasing member 3 comes into contact with and is supported by the valve stopper 4, and the spring rigidity of the biasing member 3 appears to increase, so the fine vibration of the leaf valve 2 when it deflects and opens can be effectively suppressed. In addition, with the valve device V1 configured in this way, the biasing force that biases the leaf valve 2 of the biasing member 3 can be changed, and the damping force can be changed in multiple stages before and after the biasing member 3 comes into contact with the valve stopper 4 and before and after the leaf valve 2 comes into contact with the valve stopper 4, so that a damping force can be generated according to the specifications required of the shock absorber D to which the valve device V1 is applied.

[0074] Furthermore, the biasing member 3 in the valve device V1 of the first embodiment is configured to contact the valve stopper 4 while the outer circumference of the leaf valve 2 is bending and contacting the valve stopper 4.

[0075] With the valve device V1 configured in this way, when the deflection of the leaf valve 2 increases, the biasing member 3 contacts and is supported by the valve stopper 4, and vibrations of the leaf valve 2 and the biasing member 3 are suppressed. Therefore, when the leaf valve 2 deflects and opens, fine vibrations of the leaf valve 2 can be suppressed. Thus, the valve device V1 of the first embodiment can generate a stable damping force.

[0076] Furthermore, in the valve device V1 of the first embodiment, the piston (valve seat member) 1 has an annular inner valve seat 1j positioned on the inner circumference of the outlet end of the compression port (port) 1c, and the leaf valve 2 is able to seat and dissipate from the inner valve seat 1j together with the valve seat 1e. With the valve device V1 configured in this way, when the deflection of the leaf valve 2 increases, an annular gap is created not only between the leaf valve 2 and the valve seat 1e, but also between the leaf valve 2 and the inner valve seat 1j, allowing the passage of liquid. Therefore, the damping force can be changed in multiple stages before and after the biasing member 3 contacts the valve stopper 4, before and after the leaf valve 2 contacts the valve stopper 4, and before and after the leaf valve 2 separates from the inner valve seat 1j. Thus, the valve device V1 can generate a damping force that corresponds to the specifications required for the shock absorber D to which it is applied.

[0077] Furthermore, in the valve device V1 of the first embodiment, the biasing member 3 has an annular fixing portion 31 that is positioned and fixed on the side of the leaf valve 2 opposite the valve seat member, and a plurality of spring portions 32 that extend radially from the outer circumference of the fixing portion 31 and abut against the side surface of the leaf valve 2 opposite the valve seat member. The spring portion 32 has a base end portion 32a that extends from the outer circumference of the fixing portion 31 in a direction away from the leaf valve 2, and a tip portion 32b that bends and extends from the tip of the base end portion 32a in a direction approaching the leaf valve 2 and abuts against the side end of the leaf valve 2 opposite the valve seat member, and the bent portion 32c between the base end portion 32a and the tip portion 32b abuts against the valve stopper 4.

[0078] With the valve device V1 configured in this way, the spring portion 32 has a shape that is convex toward the valve stopper 4, so even if the deflection of the leaf valve 2 is small, the bent portion 32c can contact the valve stopper 4 and support the spring portion 32, thereby stabilizing the damping force. Furthermore, with the valve device V1, since the spring portion 32 has a shape that is convex toward the valve stopper 4, when the bent portion 32c contacts and is supported by the valve stopper 4, only the tip portion 32b is effective as a spring, so the biasing force that biases the leaf valve 2 can be easily adjusted by setting the spring constant of only the tip portion 32b.

[0079] Furthermore, the biasing member 3 only needs to be able to contact the leaf valve 2 and bias it, and when the leaf valve 2 bends, it needs to contact the valve stopper 4 and be supported by the valve stopper 4 while applying a biasing force to the leaf valve 2. Therefore, configurations other than the aforementioned fixed part 31 and spring parts 32 radially provided on the outer circumference of the fixed part 31 can also be adopted. For example, the biasing member 3 may consist of an annular disc whose inner circumference is fixed to the small diameter part 11a and which is positioned spaced apart from the leaf valve 2 and allows bending on the outer circumference, and an elastic body such as rubber fixed to the outer circumference of the disc and contacting the side of the leaf valve 2 opposite the piston. With the biasing member 3 configured in this way, when the disc is not in contact with the valve stopper 4, the disc and the elastic body bias the leaf valve 2, and when the disc bends and contacts the valve stopper 4, the leaf valve 2 can be biased solely by the elastic force generated by the elastic body.

[0080] Furthermore, the spring portion 32 of the biasing member 3 of the valve device V1 in the first embodiment is provided with a curved portion 32d at the tip of the tip portion 32b, which has a curved surface that curves toward the side opposite the leaf valve and contacts the leaf valve 2. With the valve device V1 configured in this way, since the spring portion 32 is provided with a curved portion 32d that has a curved surface that contacts the leaf valve 2, even if the leaf valve 2 flexes and the contact portion where the curved portion 32d contacts the leaf valve 2 changes, the curved portion 32d slides smoothly on the side of the leaf valve 2 opposite the piston, and does not hinder the flexing of the leaf valve 2, thus ensuring the smooth flexing of the leaf valve 2.

[0081] The number of spring portions 32 in the biasing member 3 can be arbitrarily changed in the design, but it is preferable to provide three or more from the viewpoint of biasing the annular leaf valve 2. In addition, the height of some or all of the bent portions 32c of the spring portion 32 in the biasing member 3 can be made different in the axial direction of the biasing member 3 so that the timing at which the bent portions 32c contact the valve stopper 4 differs for some or all of the bent portions 32c. In this way, by making the contact of the bent portions 32c with the valve stopper 4 at a staggered timing rather than all of them contacting the valve stopper 4 simultaneously due to the deflection of the leaf valve 2, the abrupt change in damping force at the inflection point of the damping force characteristics can be mitigated.

[0082] Furthermore, by varying the thickness or width of part or all of the spring portion 32 in the biasing member 3, the bending rigidity of part or all of the spring portion 32 can be varied, thereby causing the opening timing and degree of deflection of the leaf valve 2 to differ in the circumferential direction. In this way, the damping force characteristics change smoothly, and abrupt changes in damping force at the inflection point of the damping force can be mitigated.

[0083] Furthermore, the bending rigidity of the base end 32a and the tip end 32b of the spring portion 32 in the biasing member 3 may be made different. Specifically, as shown in Figure 7, the fixing portion 31 and the base end 32a connected to the fixing portion 31 and the tip end 32b may be made of materials with different bending rigidities, and the base end 32a and the tip end 32b may be joined together to form the biasing member 3. The biasing member 3 may be made of metal, or of synthetic resin if joining is possible. Alternatively, another spring having only a fixing portion and a base end may be prepared, and the other spring may be placed on top of the biasing member 3 to support the base end 32b of the biasing member 3 with the other spring, thereby making the bending rigidity of the base end 32a and the tip end 32b appear to be different.

[0084] In this modified version of the valve device V1, the degree of freedom in setting the spring constant of the spring portion 32 before and after the bent portion 32c contacts the valve stopper 4 is increased. For example, if the bending stiffness of the base portion 32a is lowered and the bending stiffness of the tip portion 32b is increased, the base portion 32a will bend more easily, and the leaf valve 2 will also bend more easily, causing the bent portion 32c to quickly contact the valve stopper 4, making it easier to suppress fine vibrations of the leaf valve 2. Subsequently, the biasing force of the tip portion 32b increases in response to the increase in the amount of deflection of the leaf valve 2, suppressing the deflection of the leaf valve 2 and obtaining damping force characteristics with a high damping coefficient. Furthermore, since the bending stiffness of the tip portion 32b can be freely set, the damping force characteristics from the time the bent portion 32c contacts the valve stopper 4 until the leaf valve 2 contacts the valve stopper 4 can be adjusted by setting the bending stiffness of the tip portion 32b. Specifically, as shown in Figure 8, the damping coefficient (slope) in the damping characteristics in the low-speed range can be adjusted by the bending stiffness of the tip portion 32b within the range indicated by the shaded area. In order to make the bending stiffness of the base portion 32a and the tip portion 32b of the spring portion 32 of the biasing member 3 different, as mentioned above, in addition to creating the fixing portion 31 and the base portion 32a and the tip portion 32b from materials with different bending stiffness, even if the biasing member 3 is made of a single material, the bending stiffness of the two can be made different by making the width and thickness of the base portion 32a different from the width and thickness of the tip portion 32b. In this case, in order to make the bending stiffness of the tip portion 32b higher than the bending stiffness of the base portion 32a, for example, the width of the tip portion 32b can be made wider than the width of the base portion 32a, or the thickness of the tip portion 32b can be made thicker than the thickness of the base portion 32a. Furthermore, to make the bending rigidity of the tip portion 32b lower than that of the base portion 32a, for example, the width of the tip portion 32b can be made narrower than the width of the base portion 32a, or the thickness of the tip portion 32b can be made thinner than the thickness of the base portion 32a.

[0085] As mentioned above, the piston 1, as a valve seat member, has an inner valve seat 1j on the inner circumference of the compression port 1c, which is a port, in addition to the valve seat 1e, and the leaf valve 2 seats on and off the inner valve seat 1j and the valve seat 1e. However, the inner valve seat 1j and the hole 2a in the leaf valve 2 may be eliminated, and the leaf valve 2 may be configured to seat on and off only the valve seat 1e. In this case, the damping force characteristics will differ from those shown in Figure 6, and the characteristics in the medium speed range, when the leaf valve 2 separates from the inner valve seat 1j, will not appear between the characteristics in the low speed range when the spring portion 32 is supported by the valve stopper 4 and the characteristics in the high speed range when the deflection of the leaf valve 2 is restricted by the valve stopper 4, resulting in the characteristics shown by the dashed line in Figure 6.

[0086] Furthermore, the valve device may be configured as the valve device V2 of the second embodiment shown in Figure 9. In the valve device V2 of the second embodiment, the structure of the piston 1 as a valve seat member differs from that of the valve device V1 of the first embodiment. In describing the valve device V2 of the second embodiment, in order to avoid repetition of the explanation, the same configuration as the valve device V1 will be omitted from the explanation, and the configuration that differs from the valve device V1 will be described in detail.

[0087] The piston 1 in the valve device V2, as a valve seat member, has a compression port 1c and a valve seat 1e as ports, as well as an outer port 1k located on the outer circumference of the valve seat 1e, and an annular outer valve seat 1m located on the outer circumference of the outlet end of the outer port 1k and surrounding the outer port 1k. It does not have the inner valve seat 1j that the piston 1 of the valve device V1 had.

[0088] The outer port 1k is a pressure-side port through which liquid passes when the buffer D contracts, allowing liquid flow from the pressure-side chamber R2 to the extension-side chamber R1. The pressure-side port 1c and the outer port 1k are in parallel, connecting the pressure-side chamber R2 and the extension-side chamber R1. The piston 1 is equipped with an annular valve seat 1e between the pressure-side port 1c and the outer port 1k, and the outer circumference of the outer port 1k is surrounded by the outer valve seat 1m.

[0089] When the leaf valve 2 is placed on the inner circumferential seat portion 1f of the piston 1, it also contacts the valve seat 1e and the outer valve seat 1m, with its inner side fixed to the small diameter portion 11a of the rod 11, allowing for deflection of the outer side. When the outer side of the leaf valve 2 is deflected, it first forms an annular gap between itself and the outer valve seat 1m, and as the deflection increases, it also forms an annular gap between itself and the valve seat 1e, allowing sufficient liquid to pass through.

[0090] In the valve device V2 of the second embodiment, the biasing member 3, spacers 5 and 6, and valve stopper 4 are stacked on the side opposite the piston of the leaf valve 2, similar to the valve device V1 of the first embodiment, and are fixed to the small diameter portion 11a of the rod 11 by a piston nut 16.

[0091] In the valve device V2 configured in this way, when the shock absorber D is in contraction operation and the piston speed during the shock absorber D's contraction operation is in the very low speed range, the amount of deflection of the leaf valve 2 is small, and although the leaf valve 2 moves away from the outer valve seat 1m, it remains seated on the inner valve seat 1e. Therefore, the liquid moves from the compression chamber R2 to the extension chamber R1 by passing only through the outer port 1k. Furthermore, when the piston speed during the shock absorber D's contraction operation is in the very low speed range, the spring portion 32 of the biasing member 3 does not come into contact with the valve stopper 4 and the entire member deflects, so the biasing force of the biasing member 3 that biases the leaf valve 2 is small, and the damping force characteristics in the shock absorber D are such that the damping force increases with the piston speed, but the degree of increase in damping force is small, as shown in Figure 6.

[0092] When the piston speed of the shock absorber D in the contraction direction exceeds the very low speed range and reaches the low speed range, the deflection of the outer circumference of the leaf valve 2 increases, and the bent portion 32c of the spring portion 32 comes into contact with the valve stopper 4. Although the leaf valve 2 moves away from the outer valve seat 1m, it either comes into contact with the valve seat 1e or, even if it moves away, only a small gap is created between it and the valve seat 1e. Therefore, most of the liquid moving from the compression chamber R2 to the extension chamber R1 passes through the annular gap between the leaf valve 2 and the outer valve seat 1m. When the bent portion 32c of the spring portion 32 comes into contact with the valve stopper 4, the bent portion 32c is supported by the valve stopper 4, and the tip portion 32b of the spring portion 32 begins to deflect with the bent portion 32c as the fulcrum. As a result, the spring constant of the biasing member 3 appears to increase, and the degree of increase in the biasing force of the biasing member 3 relative to the amount of deflection of the leaf valve 2 increases. Therefore, when the piston speed during the compression operation of the shock absorber D is in the low-speed range, the damping force characteristics of the shock absorber D, as shown in Figure 6, show a greater degree of increase in damping force with respect to piston speed compared to when the piston speed is in the very low-speed range.

[0093] Furthermore, when the piston speed of the shock absorber D in the contraction direction exceeds the low speed range and reaches the medium speed range, both the deflection of the outer circumference of the leaf valve 2 and the deflection of the tip 32b of the spring portion 32 increase. As a result, the leaf valve 2 is separated from both the outer valve seat 1m and the valve seat 1e to a sufficient extent for liquid to pass through. Consequently, the liquid moves from the compression chamber R2 to the extension chamber R1 not only through the annular gap between the leaf valve 2 and the outer valve seat 1m, but also through the annular gap between the leaf valve 2 and the valve seat 1e. Thus, when the piston speed of the shock absorber D is in the medium speed range during contraction, the flow path area in the valve device V1 increases. Therefore, as shown in Figure 6, the damping force characteristics of the shock absorber D show a smaller increase in damping force with respect to piston speed compared to when the piston speed is in the low speed range.

[0094] Furthermore, when the piston speed of the shock absorber D in the contraction direction exceeds the medium speed range and reaches the high speed range, both the deflection of the outer circumference of the leaf valve 2 and the deflection of the tip 32b of the spring portion 32 increase, causing the outer circumference of the leaf valve 2 to come into contact with the valve retaining portion 4a of the valve stopper 4, and further deflection of the leaf valve 2 is restricted by the valve stopper 4.

[0095] Thus, when the piston speed during the contraction operation of the shock absorber D is in the high-speed range, the flow path area in the valve device V1 does not increase and remains constant. Therefore, as shown in Figure 6, the damping force characteristics of the shock absorber D show a greater degree of increase in damping force with respect to piston speed compared to when the piston speed is in the medium-speed range. Furthermore, if the valve retaining portion 4a is eliminated, the maximum amount of deflection that the leaf valve 2 can be allowed to be increases, which can reduce the slope of the damping force characteristics in the high-speed range of piston speed, as described later.

[0096] Furthermore, as the deflection of the leaf valve 2 increases, the bent portion 32c of the spring portion 32 in the biasing member 3 comes into contact with the valve stopper 4. When the spring portion 32 is supported by the valve stopper 4, only the tip portion 32b becomes effective as a spring. This appears to increase the spring rigidity of the biasing member 3, and also suppresses vibrations of the spring portion 32. As a result, the fine vibrations of the leaf valve 2 when it deflects and opens can be suppressed. Therefore, in the valve device V2 of the second embodiment, fine vibrations of the leaf valve 2 can be suppressed and a stable damping force can be generated.

[0097] Thus, in the second form of valve device V2, the piston (valve seat member) 1 has an outer port 1k positioned on the outer circumference of the valve seat 1e, and an annular outer valve seat 1m positioned on the outer circumference of the outlet end of the outer port 1k and surrounding the outer port 1k, and the leaf valve 2 can seat and detach from the outer valve seat 1m together with the valve seat 1e. With the valve device V2 configured in this way, when the deflection of the leaf valve 2 increases, an annular gap is created not only between the leaf valve 2 and the outer valve seat 1m, but also between the leaf valve 2 and the valve seat 1e, allowing the passage of liquid. Therefore, the damping force can be changed in multiple stages before and after the biasing member 3 contacts the valve stopper 4, before and after the leaf valve 2 contacts the valve stopper 4, and before and after the leaf valve 2 separates from the valve seat 1e, so that the damping force can be changed in multiple stages.

[0098] For convenience, the operation of the valve device V1 in the first embodiment and the valve device V2 in the second embodiment is described using classifications such as very low speed range, low speed range, medium speed range, and high speed range for the piston speed when the buffer D is contracted. However, the piston speeds that define these classifications can be changed as needed.

[0099] Furthermore, although the valve seat member is described as the piston 1 above, the valve case 14 may be used as the valve seat member, and valve devices V1 and V2 may be applied to the suction passage 14f in the valve case 14.

[0100] Furthermore, as mentioned above, valve devices V1 and V2 are used to generate damping force when the shock absorber D contracts, but they may also be used to generate damping force when the shock absorber D extends. In that case, valve devices V1 and V2 can be assembled below the piston 1 on the compression chamber side, and a flange can be provided on the outer circumference of the piston nut 16 and used as a valve stopper. Alternatively, valve devices V1 and V2 can be placed on the reservoir side of the valve case 14 so that they generate damping force when the shock absorber D contracts.

[0101] Furthermore, as described above, the bent portion 32c of the biasing member 3 is made to abut against the lower surface of the valve stopper 4. However, a structure may also be adopted in which the bent portion 32c enters the through hole 4b of the valve stopper 4, and the portion of the biasing member 3 other than the bent portion 32c is made to abut against the valve stopper 4.

[0102] 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]

[0103] 1...Piston (valve seat member), 1c...Compression side port (port), 1e...Valve seat, 1j...Inner valve seat, 1k...Outer port, 1m...Outer valve seat, 2...Leaf valve, 3...Biasing member, 4...Valve stopper, 31...Fixed part, 32...Spring part, 32a...Base end, 32b...Tip, 32c...Bent part, 32d...Curved part, V1, V2...Valve device

Claims

1. A valve seat member having a port and a valve seat positioned on the outer circumference of the outlet end of the port and surrounding the port, A leaf valve that is annular in shape, with its inner circumference fixed and its outer circumference allowed to flex, and which can seat and dissipate from the valve seat, A biasing member that biases the leaf valve toward the valve seat member, The biasing member is provided on the side opposite to the leaf valve and includes a valve stopper that restricts the deflection of the leaf valve when the outer circumference of the leaf valve bends and makes contact with it. The biasing member contacts the valve stopper from the state in which the outer circumference of the leaf valve is seated on the valve seat until it contacts the valve stopper. A valve device characterized by the following features.

2. The biasing member, when it comes into contact with the valve stopper, changes the biasing force that biases the leaf valve. The valve device according to feature 1.

3. The biasing member contacts the valve stopper while the outer circumference of the leaf valve is bending and contacts the valve stopper. The valve device according to feature 1.

4. The valve seat member has an outer port positioned on the outer circumference of the valve seat, and an annular outer valve seat positioned on the outer circumference of the outlet end of the outer port and surrounding the outer port. The leaf valve is capable of seating together with the valve seat and the outer valve seat. The valve device according to feature 1.

5. The valve seat member has an annular inner valve seat positioned on the inner circumference of the outlet end of the port, The leaf valve is separable from the inner valve seat together with the valve seat. The valve device according to feature 1.

6. The biasing member is An annular fixing portion is positioned and fixed on the side opposite the valve seat member of the leaf valve, It has a plurality of spring portions that extend radially from the outer circumference of the fixed portion and abut against the side surface of the anti-valve seat member of the leaf valve, The aforementioned spring portion is A base end portion extending from the outer circumference of the fixed portion in a direction away from the leaf valve, It has a tip portion that extends from the tip of the base end in a direction approaching the leaf valve and abuts against the side end of the leaf valve opposite the valve seat member, The bent portion between the base end and the tip end is brought into contact with the valve stopper. The valve device according to feature 1.

7. The bending stiffness of the base end of the spring portion is different from the bending stiffness of the tip end of the spring portion. The valve device according to feature 6.

8. The spring portion has a curved portion at the tip of the tip that curves toward the side away from the leaf valve and contacts the leaf valve. The valve device according to feature 6.

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