Valve devices and shock absorbers

Abstract

The present invention provides a valve device and shock absorber that can improve ride comfort in a vehicle when the shock absorber expands and contracts at very low speeds. [Solution] The valve device V comprises a main passage MP, a bypass passage BP parallel to the main passage MP, a main valve MV1 and a main valve MV2 on one side provided in the main passage MP, and a sub-valve SV1 and a sub-valve SV2 on the other side provided in the bypass passage BP. The opening pressure of the sub-valve SV1 is lower than the opening pressure of the main valve MV1, and the opening pressure of the sub-valve SV2 is lower than the opening pressure of the main valve MV2.

Description

Technical Field

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

Background Art

[0002] A shock absorber is interposed, for example, between a vehicle body such as a motorcycle and a wheel, and is used to generate a damping force by providing resistance to the flow of liquid generated during expansion and contraction, thereby suppressing the vibration of the vehicle body.

[0003] Such shock absorbers are being improved daily to achieve damping force characteristics that can further improve the riding comfort in vehicles such as motorcycles. When the expansion and contraction speed of the shock absorber is in the very low speed range, there may be a need for a shock absorber that can quickly increase the damping force with respect to the expansion and contraction speed and effectively damp the vibration of the wheel in the very low speed range.

[0004] A shock absorber that realizes such damping force characteristics includes, for example, a cylinder, a piston rod that is movably inserted into the cylinder, and a valve device attached to the piston rod. The valve device includes a piston attached to the outer periphery of the tip of the piston rod and partitioning the inside of the cylinder into an extension chamber and a compression chamber, extension leaf valves and compression leaf valves that are annular and whose inner peripheries are fixed to the piston rod and open and close ports provided in the piston, a bypass passage that bypasses the port through the piston rod and connects the extension chamber and the compression chamber, an orifice provided in the bypass passage, and extension and compression on-off valves provided in parallel with the orifice in the bypass passage (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Conventional valve devices have an orifice and extension valves and compression valves arranged in parallel in a bypass path that connects the extension chamber and the compression chamber through the piston rod. This improves ride comfort when the shock absorber's extension and contraction speed is in the low speed range, while mitigating the abrupt change in damping force when moving from the low speed range to the high speed range.

[0007] However, in conventional valve devices, the damping force is exerted by the orifice when the shock absorber's expansion and contraction speed is in the low-speed range. Therefore, when the shock absorber expands and contracts in the very low-speed range, the hydraulic fluid passes through the orifice with little resistance, which can result in insufficient damping force in the very low-speed range, leaving room for improvement in the ride comfort of vehicles.

[0008] Therefore, the present invention aims to provide a valve device and a shock absorber that can improve the ride comfort in a vehicle when the shock absorber expands and contracts in the very low-speed range. [Means for solving the problem]

[0009] A valve device that solves the above problems comprises a main passage connecting one chamber and the other chamber, a bypass passage running parallel to the main passage and connecting one chamber and the other chamber, a one-side main valve provided in the main passage that opens to the flow of fluid from one chamber to the other chamber to resist the flow of fluid passing through, a other-side main valve provided in parallel with the one-side main valve to the main passage and opens to the flow of fluid from the other chamber to the one chamber to resist the flow of fluid passing through, a one-side sub-valve provided in the bypass passage that opens to the flow of fluid from one chamber to the other chamber to resist the flow of fluid passing through, and a other-side sub-valve provided in the bypass passage that opens to the flow of fluid from the other chamber to the one chamber to resist the flow of fluid passing through, characterized in that the opening pressure of the one-side sub-valve is lower than the opening pressure of the one-side main valve, and the opening pressure of the other-side sub-valve is lower than the opening pressure of the other-side main valve.

[0010] In this valve device, when the shock absorber's expansion and contraction speed is in the very low speed range, one or the other sub-valve opens, creating resistance to the fluid flow and generating a damping force. Compared to conventional valve devices that generate damping force using an orifice, this device can exert a sufficiently high damping force to suppress vibrations when the shock absorber expands and contracts at very low speeds.

[0011] Furthermore, the valve device may include a variable valve provided in series with respect to one sub-valve and the other sub-valve of the bypass path, allowing for adjustment of the opening area and thus adjusting the resistance to the flow of the fluid passing through it. With a valve device configured in this way, the ride comfort in the vehicle can be improved when the shock absorber expands and contracts in the very low-speed range, while the damping force can be adjusted to a high or low level by adjusting the flow area of ​​the bypass path with the variable valve.

[0012] Furthermore, the valve device includes a cylindrical housing with a bypass passage formed inside, and one side sub-valve has an annular valve seat member mounted on the outer circumference of the housing facing the other chamber and having an annular valve seat provided on the outer circumference of one end and a passage communicating with the bypass passage, and an annular leaf valve whose inner circumference is fixed to the outer circumference of the housing facing the other chamber and opens and closes the passage by seating the outer circumference away from the annular valve seat, and the other side sub-valve has a other side valve seat member provided on the inner circumference of the housing and having a other side port, and The variable valve comprises a valve body that is axially movable within a housing and seats away from the other valve seat member to open and close the other port, and a spring that is housed within the housing and biases the valve body toward the other valve seat member. The variable valve may also comprise a variable valve seat member fixed to the inner circumference of the housing and having a variable valve port, a variable valve body that is axially movable within the housing and seats away from the variable valve seat member to open and close the variable valve port, and an adjuster that can adjust the position of the variable valve body relative to the variable valve seat member.

[0013] With a valve device configured in this way, one sub-valve is mounted on the outer circumference of a cylindrical housing, and the other sub-valve and the variable valve seat member and variable valve body of the variable valve are housed inside the housing. This allows the one sub-valve and the other sub-valve to be easily arranged in parallel while utilizing the inside of the housing as a bypass path, and the variable valve and the other sub-valve to be easily arranged in series within the bypass path. This makes the valve device compact and facilitates its integration into a buffer.

[0014] Furthermore, the other-side sub-valve and the variable valve in the valve device may be housed in series within the housing, and the other-side valve seat member and the other-side valve body of the other-side sub-valve and the variable valve seat member and the variable valve body of the variable valve may be arranged coaxially.

[0015] With a valve device configured in this way, the other valve seat member and the other valve body, and the variable valve seat member and the variable valve body are arranged coaxially within the housing. Therefore, even if the outer diameter of the housing is reduced, the other valve seat member and the other valve body, and the variable valve seat member and the variable valve body can be accommodated without difficulty within the housing. This allows for a smaller housing diameter, making it easier to install the valve device inside the buffer and avoiding the need to enlarge the buffer to which the valve device is applied.

[0016] Furthermore, the other valve body in the valve device may be supported so as to be movable in the axial direction by a variable valve seat member and centered radially. In a valve device configured in this way, the other valve body is positioned radially by a variable valve seat member that is coaxially arranged within the housing, so that the other valve body can seat on and off the other valve seat member without axial wobble, allowing the other sub-valve to open and close stably. In addition, the parts that center the other valve body can be concentrated in the variable valve seat member that functions as the valve seat in the variable valve, thus reducing the number of parts and lowering costs.

[0017] Further, the shock absorber includes a cylinder, a piston rod axially movably inserted into the cylinder, a piston attached to the outer periphery of the piston rod and axially movably inserted into the cylinder to partition the inside of the cylinder into an extension chamber and a compression chamber, and a valve device. The main passage is formed in the piston, and the bypass passage is formed in the piston rod. One chamber may be the extension chamber and the other chamber may be the compression chamber.

[0018] According to the shock absorber configured as described above, the riding comfort of the vehicle when the shock absorber expands and contracts in the very low speed range can be improved, and the damping force when the shock absorber extends at a very low speed and the damping force when it contracts at a very low speed can be set independently. Also, according to the shock absorber, the riding comfort of the vehicle can be improved without causing an increase in the overall length, and the damping force can also be adjusted.

Advantages of the Invention

[0019] According to the valve device and the shock absorber of the present invention, the riding comfort of the vehicle when the shock absorber expands and contracts in the very low speed range can be improved.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a longitudinal sectional view of a shock absorber according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged sectional view of a shock absorber according to an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing the damping force characteristics of a shock absorber according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0021] The present invention will be described below based on the embodiments shown in the figures. As shown in Figures 1 and 2, the valve device V in one embodiment is applied to the piston portion of a buffer D, and comprises a main passage MP that connects the extension chamber R1 as one chamber and the compression chamber R2 as the other chamber in the buffer D, a bypass passage BP that is parallel to the main passage MP and connects the extension chamber R1 and the compression chamber R2, a one-sided main valve MV1 provided in the main passage MP that opens to the fluid flow from the extension chamber R1 to the compression chamber R2 and provides resistance to the flow of hydraulic fluid as the fluid passing through, and a one-sided main valve MV1 that is on the other side of the main passage MP The system includes a main valve MV2 located in parallel with the main valve MV1, which opens to resist the flow of hydraulic fluid passing through the fluid flow from the compression chamber R2 to the extension chamber R1, a sub-valve SV1 located in the bypass passage BP, which opens to resist the flow of hydraulic fluid passing through the fluid flow from the extension chamber R1 to the compression chamber R2, and a sub-valve SV2 located in the bypass passage BP, which opens to resist the flow of hydraulic fluid passing through the hydraulic fluid flow from the compression chamber R2 to the extension chamber R1.

[0022] The valve device V and shock absorber D will now be described in detail. As shown in Figure 1, the shock absorber D comprises a cylinder 1, a piston rod 2 which is movably inserted into the cylinder 1 and partly functions as a housing in the valve device V, a piston 3 which is attached to the piston rod 2 and slidably inserted into the cylinder 1 to divide the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, and a valve device V. Although not shown in the figures, the shock absorber D is interposed between the vehicle body and the rear wheel in a saddle-type vehicle such as a motorcycle to generate damping force during expansion and contraction to suppress vibrations of the vehicle body. The shock absorber D may also be used in vehicles other than saddle-type vehicles.

[0023] As shown in FIG. 1, the cylinder 1 is cylindrical, and the upper end in FIG. 1 is closed by a cap 11. Further, an annular rod guide 10 through which the piston rod 2 is inserted is attached to the lower end of the cylinder 1 in FIG. 1. The rod guide 10 includes an annular seal member 10a and an annular bush 10b that are in sliding contact with the outer periphery of the piston rod 2 on the inner periphery. The seal member 10a seals the outer periphery of the piston rod 2 to seal the inside of the cylinder 1, and the bush 10b guides the movement of the piston rod 2 in the axial direction.

[0024] The inside of the cylinder 1 is partitioned by a piston 3 attached to the outer periphery of the tip of the piston rod 2 into an extension chamber R1 and a compression chamber R2 filled with hydraulic oil as a fluid. Note that the fluid is hydraulic oil in this embodiment, but in addition to hydraulic oil, for example, liquids such as water and aqueous solutions and gases can also be used.

[0025] The piston rod 2 is cylindrical and hollow inside, and the lower end in FIG. 1 penetrates the rod guide 10 and protrudes outside the cylinder 1. As shown in FIG. 2, the piston rod 2 is cylindrical, the outer diameter of the upper end portion is smaller than that of the lower side, and it includes a small diameter portion 2a with a small outer diameter at the upper end portion, a large diameter portion 2b on the lower side of the small diameter portion 2a in FIG. 2, a step portion 2c formed at the boundary between the small diameter portion 2a and the large diameter portion 2b on the outer periphery, and a screw portion 2d provided on the outer periphery at the upper end of the small diameter portion 2a in FIG. 2. It also includes two horizontal holes 2e that open from the side of the large diameter portion 2b to communicate the extension chamber R1 into the piston rod 2, and two horizontal holes 2f provided near the screw portion 2d of the small diameter portion 2a. The inside of the piston rod 2 is communicated with the extension chamber R1 through the horizontal hole 2e and is also communicated with the compression chamber R2 through the horizontal hole 2f and the upper opening. A bypass path BP that bypasses the main passage MP and communicates the extension chamber R1 and the compression chamber R2 is formed by the piston rod 2. Thus, the piston rod 2 forms the bypass path BP and functions as a housing in the valve device V. Note that two horizontal holes 2e and 2f are provided respectively, but the number of installed horizontal holes 2e and 2f is not limited to two.

[0026] Furthermore, a bracket 12 is attached to the lower end of the piston rod 2 in Figure 1, which can be connected to a swing arm that is mounted on the vehicle body so as to be able to swing vertically and rotatably, and which rotatably holds the wheel in a saddle-type vehicle (not shown). An annular spring retainer 14 is attached to the outer circumference of the bracket 12. In addition, an annular spring retainer 17 is attached to the outer circumference of the cylinder 1, and a suspension spring 19 is interposed between the spring retainers 14 and 17 to bias the shock absorber D in the extension direction.

[0027] The piston 3 is annular in shape and mounted on the outer circumference of the small-diameter portion 2a of the piston rod 2. It has an extension port 3a and a compression port 3b, which serve as main passages MP connecting the extension chamber R1 and the compression chamber R2 in parallel. On the other side of the piston 3, in the upper part of Figure 2, there is a one-side main valve MV1 which is annular in shape and mounted on the outer circumference of the small-diameter portion 2a to open and close the extension port 3a. On the other side of the piston 3, in the lower part of Figure 2, there is a other-side main valve MV2 which is annular in shape and mounted on the outer circumference of the small-diameter portion 2a to open and close the compression port 3b.

[0028] In the valve device V of this embodiment, the one-sided main valve MV1 is constructed by stacking multiple annular plates on the upper end in Figure 2 that faces the compression chamber R2 of the piston 3. The inner circumference is fixed to the piston rod 2, and the outer circumference is allowed to bend. When the outer circumference bends due to the pressure in the extension chamber R1, it opens the extension port 3a while resisting the flow of hydraulic fluid passing through the extension port 3a, making it a stacked leaf valve. Furthermore, when the buffer D contracts and the pressure in the compression chamber R2 becomes higher than the pressure in the extension chamber R1, the one-sided main valve MV1 closes and blocks the extension port 3a.

[0029] Furthermore, above the main valve MV1 on one side in Figure 2, there are multiple shims 18 that are annular in shape and have an outer diameter smaller than the outer diameter of the annular plate on the non-piston side of the main valve MV1, and adjust the axial position of the sub-valve SV1 on one side with respect to the piston rod 2. The number of stacked shims 18 can be arbitrarily changed as long as the sub-valve SV1 on one side can be positioned appropriately.

[0030] In the valve device V of this embodiment, the other-side main valve MV2 is constructed by stacking multiple annular plates at the lower end in Figure 2 facing the extension chamber R1 of the piston 3. The inner circumference is fixed to the piston rod 2, and the outer circumference is allowed to bend. When the outer circumference bends due to the pressure in the compression chamber R2, it opens the compression port 3b while resisting the flow of hydraulic fluid passing through the compression port 3b, making it a laminated leaf valve. Furthermore, when the buffer D extends and the pressure in the extension chamber R1 becomes higher than the pressure in the compression chamber R2, the other-side main valve MV2 closes to block the compression port 3b. In addition, at the lower part of the other-side main valve MV2 in Figure 2, a small-diameter spacer 15, which is annular in shape and has an outer diameter smaller than the outer diameter of the annular plate on the opposite side of the piston of the other-side main valve MV2, and which forms a fulcrum for the bending of the other-side main valve MV2 at its outer edge, and a valve stopper 16 that restricts excessive bending of the other-side main valve MV2 are stacked and mounted on the outer circumference of the piston rod 2.

[0031] The piston 3, the main valve MV1 on one side, and the main valve MV2 on the other side are fitted onto the outer circumference of the small-diameter portion 2a of the piston rod 2 and fixed to the piston rod 2 by a piston nut 13 that is screwed onto the upper end of the small-diameter portion 2a. Although the main valve MV1 on one side and the main valve MV2 on the other side are both laminated leaf valves stacked on the piston 3 with the piston 3 as the valve seat member, any valve capable of opening the main passage MP and generating damping force when the differential pressure between one chamber and the other chamber reaches the opening pressure is acceptable, so valves other than laminated leaf valves are also acceptable, and a leaf valve composed of a single annular plate may also be used.

[0032] The aforementioned piston 3 is equipped with an extension port 3a and a compression port 3b, which serve as a main passage MP connecting the extension chamber R1 and the compression chamber R2. Since the extension port 3a and the compression port 3b connect the extension chamber R1 and the compression chamber R2 in parallel, the main valve MV1 on one side and the main valve MV2 on the other side are also arranged in parallel with the main passage MP.

[0033] Then, when the valve stopper 16, spacer 15, other-side main valve MV2, piston 3, one-side main valve MV1, and shim 18 are assembled in order around the outer circumference of the small-diameter portion 2a of the piston rod 2, the lateral hole 2f that opens from the side of the small-diameter portion 2a of the piston rod 2 opens towards the pressure-side chamber, which is on the other side of the shim 18, so that the bypass passage BP is connected to the pressure-side chamber R2 through the lateral hole 2f.

[0034] Next, the sub-valve SV1 on one side is stacked above the shim 18 in Figure 2 and attached to the outer circumference of the piston rod 2. The one-side sub-valve SV1 comprises a one-side valve seat member 6 which is annular and mounted on the outer circumference facing the compression chamber R2 of the piston rod 2 and has a passage 6d that communicates with the bypass passage BP; a leaf valve 7 which is annular and fixed to the outer circumference whose inner circumference faces the compression chamber R2 of the piston rod 2 to open and close the passage 6d; a spacer 8 which is mounted on the outer circumference of the small-diameter portion 2a and stacked above the leaf valve 7 in Figure 2; and a valve stopper 9 which is mounted on the outer circumference of the small-diameter portion 2a and stacked above the spacer 8 in Figure 2. The sub-valve SV1 is fixed to the piston rod 2 by being sandwiched together with the valve stopper 16, spacer 15, the other-side main valve MV2, the piston 3, the one-side main valve MV1, and the shim 18 by a piston nut 13 which is screw-connected to a threaded portion 2d formed on the outer circumference of the upper end of the small-diameter portion 2a of the piston rod 2 and the stepped portion 2c of the piston rod 2.

[0035] The one-sided valve seat member 6 comprises an annular disc portion 6a mounted on the outer circumference of the small-diameter portion 2a and stacked on the side of the shim 18 opposite the piston, an annular valve seat 6b rising from the outer circumference of the disc portion 6a toward the side opposite the piston, which is upward in Figure 2, an annular inner seat portion 6c rising from the inner circumference of the disc portion 6a toward the side opposite the piston, which is upward in Figure 2, and a passage 6d that communicates with the bypass passage BP, and is fitted onto the outer circumference of the small-diameter portion 2a of the piston rod 2.

[0036] The annular valve seat 6b is annular and protrudes upward in Figure 2 from the outer circumference of the upper end of the disc portion 6a in Figure 2. The inner circumferential seat portion 6c is annular and protrudes upward in Figure 2 from the inner circumference of the upper end of the disc portion 6a in Figure 2. In Figure 2, the height of the upper end of the annular valve seat 6b is higher than the height of the upper end of the inner circumferential seat portion 6c.

[0037] Furthermore, the valve seat member 6 on one side includes an annular recess 6e provided on the inner circumference at the upper end of the inner circumferential seat portion 6c, and a plurality of grooves 6f provided across the disc portion 6a and the inner circumferential seat portion 6c, extending radially from the outer circumference of the annular recess 6e.

[0038] The annular recess 6e is formed to a depth that extends from the upper end of the inner circumferential seat portion 6c to near the center in the axial direction of the disc portion 6a. When the one-side valve seat member 6 is stacked on top of the shim 18 in Figure 2, it faces the lateral hole 2f that opens to the side of the small-diameter portion 2a of the piston rod 2. Therefore, the annular recess 6e and the groove 6f communicating with the annular recess 6e are connected to the piston rod 2 through the lateral hole 2f to form the bypass passage BP. The annular recess 6e and the groove 6f form a passage 6d that communicates with the bypass passage BP. Since the annular recess 6e is annular, if the one-side valve seat member 6 is mounted on the outer circumference of the piston rod 2 in a position facing the lateral hole 2f, communication between the passage 6d and the bypass passage BP is ensured without having to position the one-side valve seat member 6 circumferentially relative to the piston rod 2, thus making it easy to assemble the one-side valve seat member 6 to the piston rod 2. Furthermore, the axial position of the one-side valve seat member 6 with respect to the piston rod 2 can be adjusted by the number of shims 18 stacked between the one-side main valve MV1 and the one-side valve seat member 6. Therefore, the number of shims 18 stacked should be adjusted so that the annular recess 6e and the lateral hole 2f face each other in the radial direction.

[0039] Although the depth from the upper end of the disc portion 6a to the bottom of the four grooves 6f is shallower than the depth of the annular recess 6e, the sum of the cross-sectional areas of the four grooves 6f viewed from the center of the disc portion 6a is greater than or equal to the cross-sectional area of ​​the annular recess 6e in Figure 2. The sum of the cross-sectional areas of the four grooves 6f viewed from the center of the disc portion 6a constitutes the effective flow area when the hydraulic fluid passes through the grooves 6f. Therefore, by setting the cross-sectional area as described above, care is taken to ensure that the flow path is not narrowed by the grooves 6f within the passage 6d. In this embodiment, the grooves 6f are formed as vertical grooves extending radially from the outer circumference of the annular recess 6e. However, as long as the annular recess 6e communicates with the pressure side chamber R2, which becomes the other chamber, the shape and structure can be arbitrarily modified, and the number of grooves 6f can also be arbitrarily modified as long as the sum of the cross-sectional areas of the grooves 6f is greater than or equal to the cross-sectional area of ​​the annular recess 6e.

[0040] In this embodiment, as shown in Figure 2, the leaf valve 7 is composed of an elastic annular plate whose inner circumference is fixed to the outer circumference of the small-diameter portion 2a of the piston rod 2. The leaf valve 7's inner circumference is sandwiched between the inner circumferential seat portion 6c of the one-side valve seat member 6 and the spacer 8, allowing for deflection of the outer circumference with the outer edge of the spacer 8 as a fulcrum, while the outer circumference is seated on the annular valve seat 6b of the one-side valve seat member 6.

[0041] Since the annular valve seat 6b is higher than the inner circumferential seat portion 6c, when the leaf valve 7 is seated on the annular valve seat 6b, it is given an initial deflection and the elastic force it generates presses against the annular valve seat 6b, thereby cutting off communication between the compression chamber R2 and the passage 6d. When the pressure of the hydraulic fluid attempting to move from the extension chamber R1, which is one chamber, to the compression chamber R2, which is the other chamber, through the bypass passage BP reaches the valve opening pressure, the leaf valve 7 deflects its outer circumference to separate from the annular valve seat 6b, connecting the passage 6d and the compression chamber R2, thereby allowing the flow of hydraulic fluid from the extension chamber R1 to the compression chamber R2 via the passage 6d, while also providing resistance to the flow of said hydraulic fluid.

[0042] On the other hand, the leaf valve 7 blocks the passage 6d by contacting the annular valve seat 6b against the flow of hydraulic fluid attempting to move from the compression chamber R2 (the other chamber) to the extension chamber R1 (the other chamber) through the bypass passage BP, thereby preventing the flow of hydraulic fluid from the compression chamber R2 to the extension chamber R1. In this way, the one-sided sub-valve SV1, provided in the bypass passage BP, opens to resist the flow of hydraulic fluid moving from the extension chamber R1 (the one chamber) to the compression chamber R2 (the other chamber), thereby resisting the flow of fluid passing through. Furthermore, the opening pressure, which is the differential pressure between the extension chamber R1 and the compression chamber R2 when the one-sided sub-valve SV1 opens, is set lower than the opening pressure of the one-sided main valve MV1 provided in the extension port 3a of the main passage MP, thereby resisting the flow of hydraulic fluid from the extension chamber R1 to the compression chamber R2 and generating a damping force when the buffer D extends at a very low speed. When the buffer D extends at a very low speed, the main valve MV1 on one side does not open, and the hydraulic fluid cannot pass through the extension port 3a. However, the sub-valve SV1 on the other side opens, so the hydraulic fluid in the extension chamber R1 moves to the compression chamber R2 through the bypass path BP.

[0043] The number of annular plates constituting the leaf valve 7 can be arbitrarily set according to the damping force characteristics generated in the shock absorber D by the valve device V, and may be one or more. Also, if it is not necessary to give the leaf valve 7 initial deflection, the annular valve seat 6b and the inner circumferential seat portion 6c may be set to the same height.

[0044] The valve stopper 9 is annular in shape and is positioned on the upper side of the leaf valve 7 in Figure 2, fitted onto the outer circumference of the small-diameter portion 2a of the piston rod 2. The valve stopper 9 contacts the leaf valve 7 when the outer circumference of the leaf valve 7 bends upward by a predetermined amount in Figure 2, preventing the leaf valve 7 from bending excessively.

[0045] Next, the piston rod 2, which functions as a housing, houses the other-side sub-valve SV2 and the variable valve VV. The other-side sub-valve SV2 comprises a other-side valve seat member 30 located on the inner circumference of the piston rod 2 and above the installation position of the lateral hole 2f in Figure 2, and having a other-side port 30c; a other-side valve body 31 housed within the piston rod 2 so as to be movable in the axial direction, which seats away from and onto the other-side valve seat member 30 to open and close the other-side port 30c; and a spring 32 housed within the piston rod 2 which biases the other-side valve body 31 toward the other-side valve seat member 30.

[0046] The other valve seat member 30 comprises a disc-shaped base 30a, an annular valve seat portion 30b that hangs downward from the outer circumference of the base 30a in Figure 2, and a other port 30c that penetrates the base 30a vertically in Figure 2. In this embodiment, it is fixed by screw connection to the piston rod 2 using a screw portion formed on the outer circumference (not shown in the reference numerals). The other valve seat member 30 may also be fixed by screw connection or by press-fitting into the inner circumference of the piston rod 2, or it may be integrated with the housing.

[0047] The other valve seat member 30 is formed inside the piston rod 2 with the valve seat portion 30b facing downward in Figure 2, and communicates the bypass passage BP with the pressure-side chamber R2, which is the other chamber, through the other port 30c. The inner diameter of the other port 30c may be set to a diameter that provides resistance to the flow of hydraulic fluid passing through the bypass passage BP.

[0048] The other valve body 31 is inserted into the small diameter portion 2a of the cylindrical piston rod 2 so as to be movable along the vertical direction in the axial direction in Figure 2, and comprises an axial body portion 31a, a spring receiving portion 31b provided on the outer circumference of the upper end of the body portion 31a, and a conical valve head 31c provided above the spring receiving portion 31b and capable of seating onto and detaching from the inner circumference of the lower end of the valve seat portion 30b of the other valve seat member 30.

[0049] When the valve head 31c of the other valve seat member 30 is seated on the valve seat portion 30b of the other valve seat member 30, the other port 30c is closed, cutting off communication between the bypass passage BP and the pressure chamber R2 via the other port 30c. When the other valve seat member 30 moves downward in Figure 2, separating the valve head 31c from the valve seat portion 30b, communication between the bypass passage BP and the pressure chamber R2 is restored via the other port 30c.

[0050] Furthermore, a variable valve seat member 41 of the variable valve VV is fixed within the piston rod 2, above the lateral hole 2e in Figure 2, and below the other valve seat member 30 in Figure 2.

[0051] The variable valve seat member 41 is cylindrical and has a through hole 41a in its middle portion that connects the inside and outside. It is fixed inside the piston rod 2 by press-fitting its outer circumference, which is below the through hole 41a, into the inner circumference of the press-fit portion 2g, which is on the inner circumference of the piston rod 2 and directly above the lateral hole 2e. As shown in Figure 2, the outer diameter of the upper portion of the variable valve seat member 41, including the through hole 41a, is smaller than that of the lower portion and is smaller than the inner diameter of the piston rod 2. An annular gap is formed between the outer circumference of the upper portion of the variable valve seat member 41 and the inner circumference of the piston rod 2 above the press-fit portion 2g, allowing the passage of hydraulic fluid. Therefore, even when the variable valve seat member 41 is press-fitted and fixed inside the piston rod 2, the inside of the piston rod 2 is not blocked by the annular gap, the through hole 41a, and the variable valve port 41b formed inside the variable valve seat member 41, ensuring communication between the extension chamber R1 and the compression chamber R2 via the bypass passage BP.

[0052] Furthermore, the lower end of the main body 31a of the other valve body 31 is inserted into the inner circumference of the variable valve seat member 41, on the side of Figure 2 above the through hole 41a. The other valve body 31 is allowed to move axially relative to the variable valve seat member 41, but its radial movement is restricted by the variable valve seat member 41. Therefore, the other valve body 31 is radially centered relative to the piston rod 2 by the variable valve seat member 41, can move axially within the piston rod 2 without wobbling, and can seat and dissipate from the valve seat portion 30b of the other valve seat member 30 without wobbling.

[0053] Furthermore, the valve head 31c of the other valve body 31 is conical in shape, and when it sits on the valve seat portion 30b, its tip is inserted into the valve seat portion 30b. Therefore, even if the other valve body 31 is misaligned with respect to the other valve seat member 30, when it sits on the valve seat portion 30b, it will sit on the entire inner circumference of the valve seat portion 30b, effectively blocking the other port 30c.

[0054] Furthermore, the inner diameter of the portion of the through-hole 41a of the variable valve seat member 41 that is lower than the upper end in Figure 2 is larger than the inner diameter of the through-hole 41a that is higher than the upper end in Figure 2. Therefore, even if the main body 31a of the other valve body 31 penetrates into the variable valve seat member 41 until it faces the through-hole 41a, the through-hole 41a is not blocked by the outer circumference of the main body 31a of the other valve body 31. Thus, even if the other valve body 31 is supported by the inner circumference of the variable valve seat member 41, the bypass path BP will not be blocked by the other valve body 31. Even if the other valve body 31 is inserted into the variable valve seat member 41, communication of the bypass passage BP is ensured by the annular gap between the variable valve seat member 41 and the piston rod 2, the through hole 41a, and the lower side in Figure 2 including the through hole 41a inside the variable valve seat member 41. Alternatively, a groove that is not closed by the other valve body 31 may be provided along the axial direction on the inner circumference of the variable valve seat member 41, thereby ensuring communication of the bypass passage BP with the groove and eliminating the annular gap between the through hole 41a, the variable valve seat member 41, and the piston rod 2.

[0055] Furthermore, a spring 32 is interposed between the spring receiving portion 31b of the other valve body 31 and the upper end of the variable valve seat member 41 in Figure 2, biasing the other valve body 31 toward the other valve seat member 30. The spring 32 constantly biases the other valve body 31 toward the other valve seat member 30, and the opening pressure at which the other valve body 31 separates from the other valve seat member 30 is set by the elastic force of the spring 32. Note that, in the lower part of the spring receiving portion 31b in Figure 2, a plurality of annular shims 33 are stacked and fitted around the outer circumference of the main body portion 31a, and the spring 32 is supported by the spring receiving portion 31b via the shims 33. Therefore, the opening pressure of the other sub-valve SV2 can be adjusted by setting the number of stacked shims 33 without replacing the spring 32. The outer diameter of the spring receiving portion 31b of the other valve body 31 and the outer diameter of the shim 33 are smaller than the inner diameter of the small diameter portion of the piston rod 2 which serves as the housing. Therefore, even if the outer circumference of the spring receiving portion 31b or the outer circumference of the shim 33 of the other valve body 31 faces the lateral hole 2f of the piston rod 2 in the radial direction, the lateral hole 2f will not be blocked. Thus, even if the other valve seat member 30 is positioned above the lateral hole 2f on the inner circumference of the piston rod 2 and very close to the lateral hole 2f, the other valve body 31 will not block the lateral hole 2f and interrupt communication between the passage 6d and the inside of the piston rod 2. Furthermore, if, with the other valve body 31 seated on the other valve seat member 30, the lower end of the shim 33 in Figure 2 is positioned above the lateral hole 2f of the piston rod 2, on the compression side chamber R2 side, then the degree of communication between the lateral hole 2f and the inside of the piston rod 2 is not narrowed when the other sub-valve SV2 is closed. This effectively prevents the other sub-valve SV2 from affecting the damping force when the buffer D, which allows the passage of hydraulic fluid through the one sub-valve SV1, is extended.

[0056] Next, the variable valve VV includes a variable valve seat member 41 fixed within the piston rod 2 and having a variable valve port 41b; a variable valve valve body 42 located within the piston rod 2 and positioned on the other sub-valve side opposite the variable valve seat member 41, housed within the piston rod 2 so as to be axially movable and seated on and off the variable valve seat member 41 to open and close the variable valve port 41b; and an adjuster 43 that can adjust the position of the variable valve valve body 42 relative to the variable valve seat member 41.

[0057] As shown in Figures 1 and 2, the variable valve body 42 is rod-shaped and has a conical needle 42a at its tip. Its lower end protrudes downward from the lower end of the piston rod 2 and is inserted into the piston rod 2 so as to be movable in the axial direction. The variable valve body 42, together with the variable valve seat member 41, constitutes a variable valve VV that allows for damping force adjustment. By moving the variable valve body 42 axially within the piston rod 2 in the vertical direction shown in Figure 2, the needle 42a at its tip can be moved closer to or further away from the inner peripheral edge of the lower end of the variable valve seat member 41, thereby adjusting the size of the annular gap between the needle 42a and the variable valve seat member 41.

[0058] Therefore, the variable valve VV can adjust the flow area by moving the variable valve body 42 axially, thereby adjusting the amount of resistance applied to the flow of liquid through the bypass passage BP. In addition, the variable valve VV can also close the valve by seating the needle 42a in the variable valve body 42 on the inner circumference of the lower end of the variable valve seat member 41, thereby blocking the variable valve port 41b and cutting off communication between the extension chamber R1 and the compression chamber R2 via the bypass passage BP.

[0059] Furthermore, the lower end of the variable valve body 42, which protrudes downward in Figure 1 from the lower end of the piston rod 2, has a conical surface that contacts an adjuster 43 rotatably mounted on the bracket 12. When the adjuster 43 is rotated, the adjuster 43 moves laterally in Figure 1 relative to the bracket 12, displacing the variable valve body 42 vertically in Figure 1 within the piston rod 2. Therefore, by rotating the adjuster 43, the valve opening of the variable valve VV can be adjusted to adjust the flow area in the bypass passage BP, and the bypass passage BP can be blocked. Even if the other valve body 31 penetrates deeply into the variable valve seat member 41 and contacts the upper end in Figure 2, which is the tip of the needle 42a of the variable valve body 42, the variable valve body 42 does not move downward in Figure 2 from the position supported by the adjuster 43. Therefore, even if the other valve body 31 moves axially within the variable valve seat member 41 and interferes with the variable valve body 42, the flow area in the variable valve VV does not change.

[0060] Next, in this embodiment, the cap 11, as shown in Figure 1, comprises a cap portion 11a that is attached to the upper end of the cylinder 1 in Figure 1, a tank holding portion 11b that holds the tank 23, and a connecting portion 11c that extends from the side of the cap portion 11a and is connected to the tank holding portion 11b.

[0061] The cap portion 11a is a bottomed cylindrical shape and is attached to the upper end of the cylinder 1 in Figure 1, closing the upper end of the cylinder 1. It also has a bracket 11d at its top, which is at the top of Figure 1, that can be connected to the body of a saddle-type vehicle (not shown). When the shock absorber D is interposed between the body of the saddle-type vehicle and the rear wheel using the bracket 11d of the cap 11 and the bracket 12 attached to the lower end of the piston rod 2, the suspension spring 19 exerts elastic force to elastically support the vehicle body.

[0062] Returning to the tank holding section 11b, a cylindrical tank 23 is attached. A free piston 24 is slidably inserted into the tank 23, and the tank 23 is divided by the free piston 24 into a liquid chamber L, which is filled with liquid, and a gas chamber G, which is filled with gas. The gas chamber G is filled with gas such that, when the buffer D is fully extended, the pressure inside the gas chamber G is at least equal to atmospheric pressure. In addition to using the free piston 24, the division between the liquid chamber L and the gas chamber G in the tank 23 may also be achieved by using a diaphragm, bladder, or the like.

[0063] The liquid chamber L in the tank 23 is connected to the pressure chamber R2 in the cylinder 1 through a pressure-side damping passage 11e and a suction passage 11f provided in the connection part 11c. The pressure-side damping passage 11e is provided with a pressure-side damping valve 21 that allows only the flow of liquid from the pressure chamber R2 to the liquid chamber L of the tank 23 and provides resistance to the flow of said liquid, and the suction passage 11f is provided with an extension-side check valve 22 that allows only the flow of liquid from the liquid chamber L to the pressure chamber R2.

[0064] The valve device V and buffer D of this embodiment are configured as described above, and the operation of the valve device V and buffer D according to this embodiment will be described below. First, the operation of buffer D when the variable valve VV is fully open and the flow area of ​​the bypass path BP is at its maximum will be described.

[0065] When the buffer D extends, the piston 3 moves downward inside the cylinder 1, compressing the extension chamber R1. When the buffer D's extension speed is in the very low speed range, the pressure in the extension chamber R1 (one chamber) increases, but the pressure difference with the pressure in the compression chamber R2 (the other chamber) does not reach the opening pressure of the main valve MV1 on one side. Therefore, the main valve MV1 on one side does not open and maintains the extension port 3a closed. The main valve MV2 on the other side receives the pressure from the extension chamber R1 from the rear side and closes the compression port 3b. When the buffer D's extension speed is in the very low speed range, the pressure in the extension chamber R1 increases, causing the leaf valve 7 to bend and separate from the annular valve seat 6b, and the sub-valve SV1 on one side opens. The sub-valve SV2 on the other side maintains a closed state as the valve body 31 on the other side sits on the valve seat portion 30b of the valve seat member 30 on the other side.

[0066] Therefore, when the shock absorber D extends and the extension speed is in the very low speed range, the hydraulic fluid cannot pass through the main passage MP, but it moves from the extension chamber R1 to the compression chamber R2 through the bypass passage BP, passage 6d, and one-sided sub-valve SV1. Also, since the variable valve VV is fully open, the annular gap between the leaf valve 7 and the annular valve seat 6b in the one-sided sub-valve SV1 is narrowest in the bypass passage BP.

[0067] Therefore, when the shock absorber D extends and the extension speed is in the very low speed range, the shock absorber D generates a damping force through the one-sided sub-valve SV1. Furthermore, the one-sided sub-valve SV1 can generate a greater damping force compared to the orifice even with a small flow rate of hydraulic fluid passing through it.

[0068] Furthermore, as the shock absorber D extends, the piston rod 2 retracts from inside the cylinder 1, causing a shortage of liquid inside the cylinder 1. However, the extension check valve 22 opens, supplying the missing liquid from the tank 23 into the cylinder 1, thus compensating for the volume lost when the piston rod 2 retracts from the cylinder 1.

[0069] Thus, when the extension speed of the buffer D is in the very low speed range, the buffer D generates a damping force that hinders extension mainly due to the resistance that the one-side sub-valve SV1 imparts to the liquid. Therefore, when the variable valve VV is fully open and the extension speed of the buffer D is in the very low speed range, the damping force characteristics on the extension side of the buffer D (the damping force characteristics with respect to the extension speed of the buffer D) are as shown in Figure 3, where the characteristics of the one-side sub-valve SV1 appear, and the damping force rises linearly from a state where the extension speed of the buffer D is 0. In conventional valve devices, when the extension speed of the buffer is in the very low speed range, as shown by the dashed line in Figure 3, the damping force is insufficient because the liquid passes through the orifice with little resistance. In contrast, in the valve device V of this embodiment, the damping force rises linearly from a state where the extension speed of the buffer D is 0, and the insufficient damping force is eliminated.

[0070] When the extension speed of buffer D is in the low-speed range beyond the very-low-speed range, the pressure in the extension chamber R1 rises, but the pressure difference with the pressure in the compression chamber R2 does not reach the opening pressure of the main valve MV1 on one side. Therefore, the main valve MV1 on one side does not open and maintains the blockage of the extension port 3a. The main valve MV2 on the other side receives the pressure from the extension chamber R1 from the rear side and blocks the compression port 3b. When the extension speed of buffer D is in the low-speed range, the sub-valve SV1 on one side deflects to its maximum extent, greatly opening the passage 6d, while the flow area of ​​the variable valve VV becomes narrower. Therefore, although the hydraulic fluid cannot pass through the blocked extension port 3a and compression port 3b, it moves from the extension chamber R1 to the compression chamber R2 via the bypass passage BP. Since the hydraulic fluid experiences the greatest resistance when passing through the variable valve VV in the bypass path BP, when the extension speed of the buffer D is in the low-speed range, the buffer D generates a damping force that hinders extension mainly due to the resistance that the variable valve VV imposes on the flow of the hydraulic fluid. Therefore, when the extension speed of the buffer D is in the low-speed range, the damping force characteristics on the extension side of the buffer D are as shown in Figure 3, and the damping force is proportional to the square of the speed, which is characteristic of the throttling caused by the variable valve VV.

[0071] Furthermore, when the extension speed of buffer D exceeds the low-speed range and is in the medium-high-speed range, the pressure difference between the pressure in the extension chamber R1 and the pressure in the compression chamber R2 reaches the opening pressure of the one-side main valve MV1, causing the one-side main valve MV1 to bend and open, opening the extension port 3a. The other-side main valve MV2 receives the pressure from the back side of the extension chamber R1 and closes the compression port 3b. The hydraulic fluid can pass through the bypass passage BP, but the extension port 3a, which is the main passage MP, is also opened, so it moves from the extension chamber R1 to the compression chamber R2 through both. When the extension speed of buffer D is in the medium-high-speed range, the flow rate of hydraulic fluid moving from the extension chamber R1 to the compression chamber R2 increases, so the resistance experienced by the hydraulic fluid passing through the variable valve VV and the one-side sub-valve SV1 in the bypass passage BP becomes greater than the resistance experienced by the liquid when passing through the one-side main valve MV1.

[0072] Therefore, the hydraulic fluid has difficulty passing through the bypass passage BP, and most of the fluid moving from the extension chamber R1 to the compression chamber R2 passes through the extension port 3a. Thus, when the extension speed of the buffer D is in the medium to high speed range, the buffer D generates a damping force that hinders extension mainly due to the resistance that the one-side main valve MV1 imposes on the flow of hydraulic fluid. Consequently, when the extension speed of the buffer D is in the medium to high speed range, the damping force characteristics on the extension side of the buffer D are proportional to the extension speed of the buffer D specific to the one-side main valve MV1, as shown in Figure 3, but the damping coefficient is somewhat smaller compared to when the extension speed is in the low speed range.

[0073] On the other hand, when the buffer D contracts, the piston 3 moves upward within the cylinder 1, compressing the compression chamber R2. When the contraction speed of the buffer D is in the very low speed range, the pressure in the compression chamber R2 rises, but the pressure difference with the pressure in the extension chamber R1 does not reach the opening pressure of the other-side main valve MV2, so the other-side main valve MV2 does not open and maintains the compression port 3b closed. The one-side main valve MV1 receives the pressure from the compression chamber R2 from the rear side and closes the extension port 3a. When the contraction speed of the buffer D is in the very low speed range, the pressure in the compression chamber R2 rises and the other-side valve body 31 receives the pressure from the compression chamber R2, retracting from the other-side valve seat member 30 and separating from the valve seat portion 30b, causing the other-side sub-valve SV2 to open. The one-side sub-valve SV1 maintains a closed state with the leaf valve 7 seated on the annular valve seat 6b.

[0074] Therefore, when the shock absorber D is contracting and the contraction speed is in the very low speed range, the hydraulic fluid cannot pass through the main passage MP, but it moves from the compression chamber R2 to the extension chamber R1 by passing through the bypass passage BP and the other-side sub-valve SV2. Also, since the variable valve VV is fully open, the annular gap between the other-side valve body 31 and the other-side valve seat member 30 in the other-side sub-valve SV2 is narrowest in the bypass passage BP.

[0075] Therefore, when the shock absorber D is contracting and the contraction speed is in the very low speed range, the shock absorber D generates a damping force through the other-side sub-valve SV2. Furthermore, the other-side sub-valve SV2 can generate a greater damping force compared to the orifice even with a small flow rate of hydraulic fluid passing through it.

[0076] Furthermore, when the buffer D contracts, the piston rod 2 enters the cylinder 1, and the volume of liquid in the cylinder 1 equals the volume of liquid the piston rod 2 enters the cylinder 1 becomes excess. This excess liquid then moves from the cylinder 1 to the tank 23 via the pressure-side damping valve 21. As a result, the pressure in the pressure-side chamber R2 rises rapidly due to the other-side sub-valve SV2 and the pressure-side damping valve 21. Also, when the buffer D contracts, liquid moves from the cylinder 1 to the tank 23, compensating for the volume of liquid that the piston rod 2 enters the cylinder 1.

[0077] Thus, when the contraction speed of the buffer D is in the very low speed range, the buffer D generates a damping force that hinders contraction mainly due to the resistance exerted on the flow of the hydraulic fluid by the other-side sub-valve SV2 and the compression-side damping valve 21. Therefore, when the variable valve VV is fully open and the contraction speed of the buffer D is in the very low speed range, the damping force characteristics on the compression side of the buffer D (the damping force characteristics with respect to the extension speed of the buffer D) are as shown in Figure 3, with the characteristics of the compression-side damping valve 21 and the other-side sub-valve SV2 appearing together, resulting in a characteristic where the damping force rises linearly from a state where the contraction speed of the buffer D is 0. In conventional valve devices, when the contraction speed of the buffer is in the very low speed range, as shown by the dashed line in Figure 3, the damping force is insufficient because the fluid passes through the orifice with little resistance. In contrast, in the valve device V of this embodiment, the damping force rises linearly from a state where the contraction speed of the buffer D is 0, and the insufficient damping force is eliminated.

[0078] When the contraction speed of buffer D is in the low speed range beyond the very low speed range, the pressure in the compression chamber R2 rises, but the pressure difference with the pressure in the extension chamber R1 does not reach the opening pressure of the other main valve MV2. Therefore, the other main valve MV2 does not open and maintains the closure of the compression port 3b. The one main valve MV1 receives the pressure from the back side of the compression chamber R2 and closes the extension port 3a. When the contraction speed of buffer D is in the low speed range, the other sub-valve SV2 deflects to its maximum extent, and the other valve body 31 retracts significantly from the other valve seat member 30, making the flow area of ​​the variable valve VV narrower. Therefore, although the hydraulic fluid cannot pass through the blocked extension port 3a and compression port 3b, it moves from the extension chamber R1 to the compression chamber R2 via the bypass path BP. Since the hydraulic fluid experiences the greatest resistance when passing through the variable valve VV in the bypass path BP, when the contraction speed of the buffer D is in the low-speed range, the buffer D generates a damping force that hinders contraction mainly due to the resistance that the variable valve VV imposes on the flow of the hydraulic fluid. Therefore, when the contraction speed of the buffer D is in the low-speed range, the damping force characteristics on the compression side of the buffer D, as shown in Figure 3, are such that the damping force is proportional to the square of the velocity, which is characteristic of the throttling by the variable valve VV, along with the characteristics of the compression damping valve 21.

[0079] Furthermore, when the contraction speed of buffer D exceeds the low-speed range and is in the medium-high-speed range, the pressure difference between the pressure in the extension chamber R1 and the pressure in the compression chamber R2 reaches the opening pressure of the other-side main valve MV2, causing the other-side main valve MV2 to bend and open, opening the compression port 3b. The one-side main valve MV1 receives the pressure of the extension chamber R1 from the rear side and closes the extension port 3a. The hydraulic fluid can pass through the bypass passage BP, but the compression port 3b, which is the main passage MP, is also opened, so it moves from the compression chamber R2 to the extension chamber R1 through both. When the contraction speed of buffer D is in the medium-high-speed range, the flow rate of hydraulic fluid moving from the compression chamber R2 to the extension chamber R1 increases, so the resistance experienced by the hydraulic fluid passing through the variable valve VV and the other-side sub-valve SV2 in the bypass passage BP is greater than the resistance experienced by the liquid when passing through the other-side main valve MV2.

[0080] Therefore, the hydraulic fluid has difficulty passing through the bypass passage BP, and most of the fluid moving from the compression chamber R2 to the extension chamber R1 passes through the compression port 3b. Thus, when the contraction speed of the buffer D is in the medium to high speed range, the buffer D generates a damping force that hinders contraction mainly due to the resistance that the other-side main valve MV2 and the compression damping valve 21 impart to the fluid. Consequently, when the contraction speed of the buffer D is in the medium to high speed range, the damping force characteristics on the compression side of the buffer D are proportional to the contraction speed of the buffer D due to the other-side main valve MV2 and the compression damping valve 21, as shown in Figure 3, but the damping coefficient becomes even smaller compared to when the contraction speed is in the low speed range.

[0081] As mentioned above, when the variable valve VV is fully open, the flow rate of the hydraulic fluid passing through the bypass passage BP can be adjusted by changing the flow area of ​​the bypass passage BP with the variable valve VV, and the damping force of the shock absorber D can be adjusted in the range from very low speed to low speed.

[0082] As described above, the valve device V of this embodiment includes a main passage MP connecting the extension chamber (one chamber) R1 and the compression chamber (the other chamber) R2, a bypass passage BP parallel to the main passage MP and connecting the extension chamber (one chamber) R1 and the compression chamber (the other chamber) R2, a one-sided main valve MV1 provided in the main passage MP that opens to the flow of hydraulic fluid (fluid) from the extension chamber (one chamber) R1 to the compression chamber (the other chamber) R2, thereby resisting the flow of hydraulic fluid (fluid) passing through, and a one-sided main valve MV1 provided in parallel with the one-sided main valve MV1 relative to the main passage MP that opens to the flow of hydraulic fluid (fluid) from the compression chamber (the other chamber) R2 to the extension chamber (one chamber) R1, thereby resisting the flow of hydraulic fluid (fluid) passing through. The system includes a main valve MV2 on the other side that provides resistance, a sub-valve SV1 on one side provided in the bypass passage BP that opens to resist the flow of hydraulic fluid from the extension chamber (one chamber) R1 to the compression chamber (the other chamber) R2, and a sub-valve SV2 on the other side provided in the bypass passage BP that opens to resist the flow of hydraulic fluid from the compression chamber (the other chamber) R2 to the extension chamber (one chamber) R1, wherein the opening pressure of the sub-valve SV1 on one side is lower than the opening pressure of the main valve MV1 on one side, and the opening pressure of the sub-valve SV2 on the other side is lower than the opening pressure of the main valve MV2 on the other side.

[0083] In the valve device V of this embodiment, when the shock absorber D expands and contracts in the very low-speed range, damping force is generated only by the sub-valve SV1 on one side and the sub-valve SV2 on the other side, and there is no orifice provided in parallel with the sub-valve SV1 on one side and the sub-valve SV2 on the other side. Therefore, in the valve device V of this embodiment, when the expansion and contraction speed of the shock absorber D is in the very low-speed range, the sub-valve SV1 on one side or the sub-valve SV2 on the other side opens, providing resistance to the flow of hydraulic fluid (fluid) and generating damping force. Compared to conventional valve devices that generate damping force by an orifice, this device can exert a sufficiently high damping force to suppress vibration when the shock absorber D expands and contracts in the very low-speed range. Therefore, according to the valve device V of this embodiment, the ride comfort in the vehicle can be improved when the shock absorber D expands and contracts in the very low-speed range. Furthermore, according to the valve device V of this embodiment, one-sided sub-valve SV1 and the other-sided sub-valve SV2 are provided in the bypass passage BP. The one-sided sub-valve SV1 provides resistance to the flow of hydraulic fluid from the extension chamber (one-sided chamber) R1 to the compression chamber (the other-sided chamber) R2, and the other-sided sub-valve SV2 provides resistance to the flow of hydraulic fluid from the compression chamber (the other-sided chamber) R2 to the extension chamber (one-sided chamber) R1. As a result, the damping force when the buffer D extends at a very low speed and the damping force when it contracts at a very low speed can be set independently. In other words, according to the valve device V of this embodiment, the damping force when the buffer D extends at a very low speed can be set by setting the opening pressure of the one-sided sub-valve SV1 without interference from the other-sided sub-valve SV2, and the damping force when the buffer D contracts at a very low speed can be set by setting the opening pressure of the other-sided sub-valve SV2 without interference from the one-sided sub-valve SV1.

[0084] In this embodiment, the valve device V has one chamber as the extension chamber R1 of the buffer D and the other chamber as the compression chamber R2 of the buffer D. However, one chamber may be the compression chamber R2 of the buffer D and the other chamber as the extension chamber R1 of the buffer D, or one chamber may be either the compression chamber R2 or the liquid chamber L of the buffer D and the other chamber may be the other of the compression chamber R2 or the liquid chamber L of the buffer D.

[0085] Furthermore, the valve device V of this embodiment is provided with a variable valve VV that is installed in series with respect to the bypass path BP, with respect to one sub-valve SV1 and the other sub-valve SV2, and whose opening area can be adjusted, thereby adjusting the resistance to the flow of the hydraulic fluid (fluid) passing through it. With the valve device V configured in this way, the ride comfort in the vehicle can be improved when the shock absorber D expands and contracts in the very low speed range, while the damping force can be adjusted to a high or low level by adjusting the flow area of ​​the bypass path BP with the variable valve VV.

[0086] Furthermore, the valve device V of this embodiment includes a cylindrical piston rod (housing) 2 with a bypass passage BP formed inside, and the one-side sub-valve SV1 has a one-side valve seat member 6 which is annular and mounted on the outer circumference of the piston rod (housing) 2 facing the pressure side chamber (other side chamber) R2 and has an annular valve seat 6b provided on the outer circumference of one end and a passage 6d that communicates with the bypass passage BP, and a leaf valve 7 which is annular and has its inner circumference fixed to the outer circumference of the piston rod (housing) 2 facing the pressure side chamber (other side chamber) R2 and opens and closes the passage 6d by seating its outer circumference away from the annular valve seat 6b, and the other-side sub-valve SV2 has a other-side valve seat provided on the inner circumference of the piston rod (housing) 2 and has a other-side port 30c The variable valve VV comprises a member 30, a other-side valve body 31 housed axially movable within the piston rod (housing) 2 and seating away from the other-side valve seat member 30 to open and close the other-side port 30c, and a spring 32 housed within the piston rod (housing) 2 and biasing the other-side valve body 31 toward the other-side valve seat member 30. The variable valve VV comprises a variable valve seat member 41 fixed to the inner circumference of the piston rod (housing) 2 and having a variable valve port 41b, a variable valve body 42 housed axially movable within the piston rod (housing) 2 and seating away from the variable valve seat member 41 to open and close the variable valve port 41b, and an adjuster 43 that can adjust the position of the variable valve body 42 relative to the variable valve seat member 41.

[0087] With the valve device V of this embodiment configured in this way, one-sided sub-valve SV1 is mounted on the outer circumference of a cylindrical piston rod (housing) 2, and the other-sided sub-valve SV2 and the variable valve seat member 41 and variable valve valve body 42 of the variable valve VV are housed inside the piston rod (housing) 2. As a result, the inside of the piston rod (housing) 2 can be used as a bypass path BP, and the one-sided sub-valve SV1 and the other-sided sub-valve SV2 can be easily arranged in parallel, and the variable valve VV and the other-sided sub-valve SV2 can be easily arranged in series inside the bypass path BP. This makes the valve device V compact and facilitates its integration into the buffer D.

[0088] Furthermore, in the valve device V of this embodiment, the other-side sub-valve SV2 and the variable valve VV are housed in series within the piston rod (housing) 2, and the other-side valve seat member 30 and the other-side valve body 31 of the other-side sub-valve SV2, and the variable valve seat member 41 and the variable valve body 42 of the variable valve VV are arranged coaxially. With the valve device V of this embodiment configured in this way, since the other-side valve seat member 30 and the other-side valve body 31 and the variable valve seat member 41 and the variable valve body 42 are arranged coaxially within the piston rod (housing) 2, the other-side valve seat member 30 and the other-side valve body 31 and the variable valve seat member 41 and the variable valve body 42 can be accommodated within the piston rod (housing) 2 without difficulty even if the outer diameter of the piston rod (housing) 2 is reduced.Therefore, with the valve device V of this embodiment, the diameter of the piston rod (housing) 2 can be reduced, making it even easier to install the valve device V inside the buffer D, and also avoiding the need to enlarge the buffer D to which the valve device V is applied.

[0089] Furthermore, in the valve device V of this embodiment, the other valve body 31 is supported so as to be movable in the axial direction by a variable valve seat member 41 and is centered radially. In the valve device V of this embodiment configured in this way, the other valve body 31 is positioned radially by the variable valve seat member 41 which is arranged coaxially within the piston rod (housing) 2, so that the other valve body 31 can seat and dissipate from the other valve seat member 30 without axial wobble, the other sub-valve SV2 can open and close stably, and the parts that center the other valve body 31 can be concentrated in the variable valve seat member 41 which functions as a valve seat in the variable valve VV, so that the number of parts can be reduced and costs can be reduced.

[0090] Furthermore, the buffer D of this embodiment comprises a cylinder 1, a piston rod 2 inserted into the cylinder 1 so as to be movable in the axial direction, a piston 3 mounted on the outer circumference of the piston rod 2 and inserted into the cylinder 1 so as to be movable in the axial direction, dividing the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, and a valve device V. The main passage MP is formed in the piston 3, and the bypass passage BP is formed in the piston rod 2, with one chamber being the extension chamber R1 and the other chamber being the compression chamber R2.

[0091] In the shock absorber D configured in this way, when the expansion and contraction speed of the shock absorber D is in the very low speed range, one side sub-valve SV1 or the other side sub-valve SV2 opens, providing resistance to the flow of hydraulic fluid and generating damping force. Therefore, compared to conventional valve devices that generate damping force using an orifice, the shock absorber D can exert a sufficiently high damping force to suppress vibrations when it expands and contracts at very low speeds. Thus, the shock absorber D of this embodiment can improve the ride comfort in a vehicle when the shock absorber D expands and contracts at very low speeds.

[0092] Furthermore, according to the buffer D of this embodiment, one-sided sub-valve SV1 and the other-sided sub-valve SV2 are provided in the bypass passage BP. The one-sided sub-valve SV1 provides resistance to the flow of hydraulic fluid from the extension chamber (one-sided chamber) R1 to the compression chamber (the other-sided chamber) R2, and the other-sided sub-valve SV2 provides resistance to the flow of hydraulic fluid from the compression chamber (the other-sided chamber) R2 to the extension chamber (one-sided chamber) R1. As a result, the damping force when the buffer D extends at a very low speed and the damping force when it contracts at a very low speed can be set independently.

[0093] Furthermore, according to the shock absorber D of this embodiment, the piston 3 equipped with the main passage MP, one main valve MV1, the other main valve MV2, and the one sub-valve SV1 can be fitted onto the outer circumference of the piston rod 2 which functions as a housing and fixed with a single piston nut 13. In addition, the variable valve seat member 41 and variable valve valve body 42 of the other sub-valve SV2 and variable valve VV are housed within the piston rod 2. Therefore, the overall length of the piston portion of the shock absorber D is not increased, and the stroke length can be secured even when a valve device V is provided. As described above, the shock absorber D can improve the ride comfort in a vehicle without increasing the overall length, and damping force adjustment is also possible.

[0094] In this embodiment, the valve device V is provided on the piston portion of the buffer D, with the piston rod 2 of the buffer D serving as the housing. However, as mentioned above, if one of the chambers is designated as the pressure chamber R2 and the other as the liquid chamber L, the valve device V may be provided between the pressure chamber R2 and the liquid chamber L.

[0095] Furthermore, in the buffer D of this embodiment, a liquid chamber L is provided outside the cylinder 1 to compensate for the volume of the piston rod 2 that moves in and out of the cylinder 1. However, when the valve device V is attached to the piston rod 2 and installed between the extension chamber R1 and the compression chamber R2, a free piston or diaphragm that forms an air chamber can be housed inside the cylinder 1, eliminating the compression damping passage 11e, suction passage 11f, compression damping valve 21, extension check valve 22, and tank 23, and the buffer D can be made into a so-called single-cylinder type buffer.

[0096] 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]

[0097] 1...Cylinder, 2...Piston rod (housing), 3...Piston, 6...One-side valve seat member, 6b...Annular valve seat, 6d...Passage, 7...Leaf valve, 30...Other-side valve seat member, 30c...Other-side port, 31...Other-side valve body, 32...Spring, 41...Variable valve seat member, 41b...Variable valve port, 42...Variable valve body, 43...Adjuster, BP...Bypass passage, D...Buffer, MP...Main passage, MV1...One-side main valve, MV2...Other-side main valve, R1...Rebound chamber (one-side chamber), R2...Compression chamber (other-side chamber), SV1...One-side sub-valve, SV2...Other-side sub-valve, VV...Variable valve

Claims

1. A main passageway connecting one room to the other room, A bypass road is provided parallel to the main passageway, connecting the one room and the other room. A one-side main valve is provided in the main passage and opens to the fluid flow from one chamber to the other chamber, thereby resisting the flow of fluid passing through it. A main valve is provided in parallel with the main valve on the one side with respect to the main passage, and opens to the flow of fluid from the other chamber to the one side chamber, thereby providing resistance to the flow of fluid passing through. A one-sided sub-valve is provided in the bypass path and opens to resist the flow of fluid from one chamber to the other chamber, The bypass path includes a sub-valve on the other side which is opened to resist the flow of fluid passing through it, with respect to the flow of fluid from the other chamber to the one chamber. The opening pressure of the aforementioned sub-valve on one side is lower than the opening pressure of the aforementioned main valve on one side. The opening pressure of the other-side sub-valve is lower than the opening pressure of the other-side main valve. A valve device characterized by the following features.

2. The bypass includes a variable valve provided in series with respect to one sub-valve and the other sub-valve, with adjustable opening area and adjustable resistance to the flow of fluid passing through. The valve device according to feature 1.

3. It comprises a cylindrical housing in which the bypass path is formed inside, The aforementioned one-sided sub-valve is A one-side valve seat member comprising an annular shape, mounted on the outer circumference of the housing facing the other chamber, and having an annular valve seat provided on the outer circumference of one end, and a passage communicating with the bypass passage, The device includes a leaf valve which is annular in shape, with its inner circumference fixed to the outer circumference facing the other chamber of the housing, and which causes the outer circumference to seat away from the annular valve seat to open and close the passage, The other side sub-valve is, A valve seat member for the other side, provided on the inner circumference of the housing and having a port for the other side, A valve body is housed within the housing so as to be movable in the axial direction and seats away from the other valve seat member to open and close the other port, The housing contains a spring that biases the other valve body toward the other valve seat member, The aforementioned variable valve is A variable valve seat member fixed to the inner circumference of the housing and equipped with a variable valve port, A variable valve valve body is housed within the housing so as to be movable in the axial direction and is capable of seating toward and away from the variable valve valve seat member to open and close the variable valve port, The variable valve body has an adjuster that can adjust the position of the variable valve seat member. The valve device according to feature 2.

4. The other sub-valve and the variable valve are housed in series within the housing, The other side valve seat member and the other side valve body in the other side sub-valve and the variable valve valve seat member and the variable valve valve body in the variable valve are arranged coaxially. The valve device according to feature 3.

5. The other valve body is supported by the variable valve seat member so as to be movable in the axial direction and is aligned radially. The valve device according to feature 4.

6. Cylinder and A piston rod is inserted into the cylinder so as to be movable in the axial direction, A piston is mounted on the outer circumference of the piston rod and inserted into the cylinder so as to be movable in the axial direction, dividing the inside of the cylinder into an extension chamber and a compression chamber, A valve device according to any one of claims 1 to 5, The main passage is formed in the piston, The bypass path is formed in the piston rod, The aforementioned one chamber is the extension chamber, The other chamber is the pressure side chamber. A buffer characterized by the following features.

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