Valve equipment and shock absorbers

Abstract

A valve device and a shock absorber capable of improving the ride comfort of a vehicle without increasing the overall length. [Solution] A shock absorber D comprises a shaft member 2, a valve seat member 3 attached to the outer periphery of the shaft member 2, a main valve assembly A that is annular and is stacked on the valve seat member and has a first valve 4 and a second valve 5, a bypass path P that is provided on the shaft member and communicates between an expansion-side chamber R1 and a compression-side chamber R2, a sub-valve disc 6 that is attached to the outer periphery of the shaft member 2 and stacked on the main valve assembly A, and has a disk portion 6a that is attached to the outer periphery of the shaft member 2 and has a cylindrical portion 6b that rises from the outer periphery of the disk portion 6a and annular seat portion 6c that is provided on the inner periphery of the cylindrical portion 6b, and a sub-valve B that has a sub-valve valve body 7 that is attached to the outer periphery of the shaft member 2 and has its outer periphery facing the inner periphery of the seat portion 6c, and the sub-valve disc 6 has a recess 6d that opens from the inner periphery of the disk portion 6a, communicates with an opening 2f, and forms a part of the bypass path P.

Description

[Technical field]

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

[0002] A shock absorber is, for example, installed between the body and wheels of a vehicle and is used to suppress vibration of the vehicle body by generating a damping force by providing resistance to the flow of liquid that occurs when the vehicle expands or contracts.

[0003] Such shock absorbers are being improved day by day in order to achieve damping force characteristics that can further improve the ride comfort of vehicles. When the shock absorber's extension / contraction speed is in the very low speed range, the damping force is quickly increased in relation to the extension / contraction speed, but in the low speed range, the damping coefficient is reduced so that the damping force does not become excessive, and in the high speed range, the damping coefficient is further reduced by one step to exert a damping force proportional to the extension / contraction speed. This creates a demand for a shock absorber that achieves damping force characteristics that can effectively damp wheel vibrations in the very low speed range while improving the ride comfort of the vehicle in other speed ranges.

[0004] A shock absorber that realizes such a damping force characteristic includes, for example, a cylinder, a piston rod 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 dividing the inside of the cylinder into an extension-side chamber and a compression-side chamber, an annular extension-side leaf valve and a compression-side leaf valve whose inner periphery is fixed to the piston rod and which open and close a port provided in the piston, a bypass passage that bypasses the port via the piston rod and connects the extension-side chamber and the compression-side chamber, and a sub-valve provided in the bypass passage (for example, see Patent Document 1).

[0005] According to the above configuration, the bypass passage in which the sub-valve is provided communicates between the expansion-side chamber and the compression-side chamber by bypassing the port, so that the flow path area of ​​the sub-valve does not become a bottleneck, the resistance of the sub-valve becomes greater than the resistance that the expansion-side leaf valve and the compression-side leaf valve provide to the flow of hydraulic oil, and the characteristics of the sub-valve override the characteristics of the expansion-side leaf valve and the compression-side leaf valve, resulting in excessive damping force. This prevents this phenomenon, and the ride comfort of the vehicle can be improved. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2022-13974 Summary of the Invention [Problem to be solved by the invention]

[0007] In a conventional valve device, when a sub-valve is provided in a bypass passage that communicates between the expansion-side chamber and the compression-side chamber through the piston rod, a valve holder that holds the sub-valve is attached to the tip of the piston rod so as not to interfere with the expansion-side leaf valve and the compression-side leaf valve.

[0008] Specifically, the sub-valve is configured to include a retaining shaft, a nut portion connected to the retaining shaft and screwed to the tip of the piston rod, a flange extending from between the retaining shaft and the nut portion toward the outer periphery, a valve holder which is attached to the tip of the piston rod and has a cylindrical annular portion which rises from the outer periphery of the flange toward the anti-piston side and has an annular protrusion on its inner periphery, and a ring-shaped valve body which is annular and fixed to the outer periphery of the retaining shaft of the valve holder to allow bending on the outer periphery side and has an outer periphery which faces the annular protrusion.

[0009] As described above, in conventional valve devices, a valve holder equipped with a retaining shaft that holds the annular valve body is attached to the end of the piston rod, which increases the overall length of the shock absorber. In other words, if one tries to ensure the stroke length of the shock absorber, the overall length of the shock absorber also increases.

[0010] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a valve device and a shock absorber that can improve the ride comfort of a vehicle without increasing the overall length. [Means for solving the problem]

[0011] The valve device that solves the above problem includes a main valve assembly including a shaft member, a valve seat member that is annular and attached to the outer periphery of the shaft member, separating two working chambers and having a first main passage and a second main passage that communicate between the two working chambers, a first valve that is annular and attached to the outer periphery of the shaft member and stacked on one side of the valve seat member to open and close the first main passage, and a second valve that is annular and attached to the outer periphery of the shaft member and stacked on the other side of the valve seat member to open and close the second main passage, and a second valve that is annular and attached to the outer periphery of the shaft member and stacked on the other side of the valve seat member to open and close the second main passage. the sub-valve having a bypass passage having an opening on the other side of the working chamber, a sub-valve disc having an annular disc portion attached to the outer periphery of the shaft member and stacked on the main valve assembly, a cylindrical portion rising from the outer periphery of the disc portion and an annular seat portion provided on the inner periphery of the cylindrical portion, and a sub-valve having a sub-valve body having an annular shape attached to the outer periphery of the shaft member and stacked on the disc portion, the sub-valve body being allowed to deflect on its outer periphery, with its outer periphery facing the inner periphery of the seat portion, and the sub-valve disc has a recessed portion that opens from the inner periphery on the sub-valve body side of the disc portion, extends toward the outer periphery, and communicates with the opening portion to form a part of the bypass passage.

[0012] In a valve device configured in this manner, there is no need for the sub-valve disc to function as a nut to secure the main valve assembly to the shaft member, nor is there a need to have a retaining shaft to hold the sub-valve body; the main valve assembly and the sub-valve can be fitted onto the shaft member in that order and secured with a single nut, making it possible to shorten the overall length.

[0013] In addition, according to the valve device, the bypass passage is parallel to the first main passage and the second main passage, so that the pressure loss due to the sub-valve is added to the pressure loss in the first valve or the second valve, thereby suppressing override that would cause excessive damping force.

[0014] Furthermore, the recess provided in the sub-valve disc in the valve device may have an annular recess provided on the inner periphery of the disc portion on the sub-valve valve body side and facing the opening. According to a valve device configured in this manner, since the inner periphery of the disc portion is provided with an annular recess facing the opening, it is easy to make the annular recess face the opening, and even if there are dimensional errors in the settings of the first valve and the second valve and in the components of the main valve assembly, the axial position of the sub-valve disc can be easily positioned to a position where the annular recess faces the opening, and fine adjustment of the number of stacked shims is also not required.

[0015] Also, the recess provided in the sub-valve disc in the valve device may have a communication recess extending from the annular recess and communicating the annular recess with the other side of the working chamber, and the sum of the cross-sectional areas of the communication recesses as viewed from the center of the disc portion may be equal to or greater than the cross-sectional area of ​​the annular recess. According to the valve device configured in this manner, even if some parts associated with the sub-valve valve body are stacked on the disc portion, the communication between the bypass path and the compression side chamber can be ensured by the recess, the flow path is not narrowed by the communicating recess within the recess, and it is possible to prevent unnecessary resistance from being applied to the flow of liquid passing through the recess, and unnecessary override from being superimposed on the damping force.

[0016] The shock absorber of the present invention includes a cylinder, a piston rod inserted into the cylinder, and a valve device, the shaft member being the piston rod, the valve seat member being slidably inserted into the cylinder to divide the cylinder into an expansion-side chamber and a compression-side chamber, and the bypass path being provided with a damping force adjustment valve capable of adjusting the flow path area. According to the shock absorber configured in this manner, the main valve assembly and the sub-valve can be fitted to the shaft member in order and fixed with one nut, so that the overall length of the valve device can be shortened, and the overall length is not increased, and override in which the damping force becomes excessive due to the pressure loss caused by the sub-valve being added to the pressure loss in the first valve or the second valve can be suppressed, and an optimal damping force can be generated in the shock absorber used in the vehicle, improving the ride comfort of the vehicle. Effect of the Invention

[0017] According to the valve device and shock absorber of the present invention, the ride comfort of the vehicle can be improved without increasing the overall length. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a vertical cross-sectional view of a shock absorber according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a partially enlarged cross-sectional view of the shock absorber according to one embodiment of the present invention. [Diagram 3] Figure 3(a) is a plan view of the sub-valve disc, and Figure 3(b) is a cross-sectional view of the sub-valve disc. [Figure 4] FIG. 4 is a diagram showing the damping force characteristics of the shock absorber according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention will be described below based on the embodiments shown in the drawings. As shown in Figures 1 and 2, a valve device V in one embodiment is configured to include a piston rod 2 as an axial member, a main valve assembly A having a piston 3 attached to the outer periphery of the piston rod 2, a compression side leaf valve 4 and an extension side leaf valve 5, a bypass path P, and a sub-valve B having a sub-valve disc 6 and a sub-valve valve body 7 attached to the outer periphery of the piston rod 2, and is applied to the piston part of a shock absorber D.

[0020] Hereinafter, each part of the valve device V and the shock absorber D will be described in detail. As shown in Fig. 1, the shock absorber D includes a cylinder 1, a piston rod 2 movably inserted into the cylinder 1, a piston 3 attached to the piston rod 2 and slidably inserted into the cylinder 1 to divide the inside of the cylinder 1 into an expansion side chamber R1 and a compression side chamber R2, and a valve device V in which the piston rod 2 serves as an axis member and the piston 3 serves as a valve seat member. Although not shown, the shock absorber D is interposed between the vehicle body and the rear wheel of a saddle-type vehicle such as a motorcycle, for example, and generates a damping force during expansion and contraction to suppress vibration of the vehicle body. The shock absorber D may be used in vehicles other than saddle-type vehicles, and may be used in equipment other than vehicles.

[0021] As shown in Fig. 1, the cylinder 1 is cylindrical, and its upper end in Fig. 1 is closed by a cap 11. An annular rod guide 10, through which the piston rod 2 is inserted, is attached to the lower end in Fig. 1 of the cylinder 1. The rod guide 10 is provided on its inner periphery with an annular seal member 10a that comes into sliding contact with the outer periphery of the piston rod 2, and an annular bush 10b. The seal member 10a seals the outer periphery of the piston rod 2 to hermetically seal the inside of the cylinder 1, and the bush 10b guides the movement of the piston rod 2 in the axial direction.

[0022] The inside of the cylinder 1 is divided into an expansion-side chamber R1 and a contraction-side chamber R2 filled with liquid by a piston 3 serving as a valve seat member attached to the outer periphery of the tip of a piston rod 2. Note that although the liquid is hydraulic oil in this embodiment, liquids other than hydraulic oil, such as water or an aqueous solution, can also be used.

[0023] The piston rod 2 is cylindrical and hollow, and its lower end in Fig. 1 penetrates the rod guide 10 and protrudes to the outside of the cylinder 1. As shown in Fig. 2, the piston rod 2 has an upper end portion with a smaller outer diameter than the lower end, and includes a small diameter portion 2a with a smaller outer diameter that functions as a shaft member, a large diameter portion 2b on the lower side of the small diameter portion 2a in Fig. 2, a step portion 2c formed on the outer periphery at the boundary between the small diameter portion 2a and the large diameter portion 2b, a screw portion 2d provided on the outer periphery at the upper end of the small diameter portion 2a in Fig. 2, two horizontal holes 2e that open from the sides of the large diameter portion 2b and communicate the extension-side chamber R1 with the inside of the piston rod 2, and two horizontal holes 2f provided in the vicinity of the screw portion 2d of the small diameter portion 2a. The inside of the piston rod 2 is communicated with the expansion-side chamber R1 via a horizontal hole 2e, and is communicated with the compression-side chamber R2 via a horizontal hole 2f.

[0024] 2, the opening at the upper end of the piston rod 2 is closed by a plug 20, and the inside of the piston rod 2 is communicated with the compression side chamber R2 through a horizontal hole 2f. A bracket 12 is attached to the lower end of the piston rod 2 in FIG. 1, which rotatably holds a wheel of a saddle-type vehicle (not shown) and can be connected to a swing arm attached to the vehicle body so as to be swingable in the vertical direction. An annular spring bearing 14 is attached to the outer periphery of the bracket 12. An annular spring bearing 17 is attached to the outer periphery of the cylinder 1, and a suspension spring 19 that biases the shock absorber D in the extension direction is interposed between the spring bearings 14, 17.

[0025] The piston 3 is annular and attached to the outer periphery of the small diameter portion 2a of the piston rod 2, and includes a compression side port 3a as a first main passage and an expansion side port 3b as a second main passage that communicate the expansion side chamber R1 and the compression side chamber R2 in parallel, respectively. A compression side leaf valve 4 as a first valve that is annular and attached to the outer periphery of the small diameter portion 2a and opens and closes the compression side port 3a is stacked on the lower side of one side of the piston 3 in FIG. 2. An expansion side leaf valve 5 as a second valve that is annular and attached to the outer periphery of the small diameter portion 2a and opens and closes the expansion side port 3b is stacked on the upper side of the other side of the piston 3 in FIG. The piston 3, the compression side leaf valve 4, and the expansion side leaf valve 5 are fitted to the outer periphery of the small diameter portion 2a of the piston rod 2, and are fixed to the piston rod 2 by a piston nut 13 that is screwed to the upper end of the small diameter portion 2a.

[0026] In the valve device V of this embodiment, the compression-side leaf valve 4 is a laminated leaf valve that is configured by stacking multiple annular plates at the lower end in FIG. 2 facing the expansion-side chamber R1 of the piston 3, and is fixed to the piston rod 2 at the inner circumferential side to allow bending on the outer circumferential side. When the outer circumferential side is bent by the pressure of the compression-side chamber R2, the compression-side leaf valve 4 opens the compression-side port 3a and provides resistance to the flow of liquid passing through the compression-side port 3a. In addition, when the shock absorber D is expanded, when the pressure in the expansion-side chamber R1 becomes higher than the pressure in the compression-side chamber R2, the compression-side leaf valve 4 closes to block the compression-side port 3a. Note that the compression-side leaf valve 4 is a valve that provides resistance to the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1 when the shock absorber D is contracted, but it may be a check valve that does not provide resistance. In addition, below the compression side leaf valve 4 in Figure 2, a small-diameter spacer 15 which is annular and has an outer diameter smaller than the outer diameter of the annular plate on the anti-piston side of the compression side leaf valve 4 and forms a fulcrum for bending of the compression side leaf valve 4 at its outer peripheral edge, and a valve stopper 16 which restricts excessive bending of the compression side leaf valve 4 are stacked and attached to the outer periphery of the piston rod 2.

[0027] In the valve device V of this embodiment, the expansion-side leaf valve 5 is configured by stacking a plurality of annular plates at the upper end in Fig. 2 facing the compression-side chamber R2 of the piston 3, and is a laminated leaf valve whose inner circumferential side is fixed to the piston rod 2 to allow bending on the outer circumferential side, and which opens the expansion-side port 3b and provides resistance to the flow of liquid passing through the expansion-side port 3b when the outer circumferential side is bent by the pressure of the expansion-side chamber R1. In addition, the expansion-side leaf valve 5 closes to block the expansion-side port 3b when the shock absorber D contracts and the pressure in the compression-side chamber R2 becomes higher than the pressure in the expansion-side chamber R1.

[0028] 2, a plurality of shims 18 are provided above the expansion-side leaf valve 5. The shims 18 are annular and have an outer diameter smaller than the outer diameter of the annular plate on the anti-piston side of the expansion-side leaf valve 5, and adjust the axial position of the sub-valve disc 6 with respect to the piston rod 2. The number of shims 18 can be arbitrarily changed as long as the sub-valve disc 6 can be disposed in an appropriate position.

[0029] The above-mentioned piston 3 functions as a valve seat member in a valve device V having a compression side port 3a as a first main passage and an extension side port 3b as a second main passage, the compression side leaf valve 4 functions as a first valve that opens and closes the first main passage, and the extension side leaf valve 5 functions as a second valve that opens and closes the second main passage, and the piston 3, the compression side leaf valve 4, and the extension side leaf valve 5 constitute a main valve assembly A.

[0030] When the main valve assembly A configured in this manner is attached to the outer periphery of the small diameter portion 2a of the piston rod 2, which is an axial member, the horizontal hole 2f opening from the side of the small diameter portion 2a of the piston rod 2 opens to the compression side chamber side, which is the other side of the main valve assembly A, and the bypass path P is connected to the compression side chamber R2 through the horizontal hole 2f.

[0031] Next, the sub-valve B is laminated on the compression side chamber side at the top of the main valve assembly A in Fig. 2 via a shim 18 and attached to the outer periphery of the piston rod 2. The sub-valve B includes an annular sub-valve disc 6, a valve stopper 8 laminated on the sub-valve disc 6, a spacer 30 laminated on the valve stopper 8, a sub-valve body 7 laminated on the spacer 30, a spacer 31 laminated on the sub-valve body 7, and a valve stopper 9 laminated on the spacer 31, and is fixed to the piston rod 2 by being sandwiched together with the main valve assembly A by a piston nut 13 screwed to a threaded portion 2d formed on the outer periphery at the upper end of the small diameter portion 2a and a step portion 2c of the piston rod 2.

[0032] The sub-valve disc 6 is fitted onto the outer periphery of the small diameter portion 2a of the piston rod 2, and is provided with a disc portion 6a which is attached to the outer periphery of the small diameter portion 2a and is stacked on the anti-piston side of the main valve assembly A via a shim 18, a cylindrical portion 6b which rises from the outer periphery of the disc portion 6a toward the anti-piston side which is the upper side in FIG. 2, a ring-shaped seat portion 6c which protrudes radially inward from the inner periphery at the upper end of the cylindrical portion 6b in FIG. 2, and a recessed portion 6d which opens from the inner periphery on the sub-valve valve body side which is the upper side in FIG. 2 of the disc portion 6a and extends toward the outer periphery.

[0033] As shown in Figures 2 and 3, the disk portion 6a is formed in a circular ring shape and is provided with an annular recess 6d1 that opens from the inner periphery on the upper side, which is the sub-valve valve body side in Figure 2, and four communicating recesses 6d2 that extend radially in the radial direction from the outer periphery of the annular recess 6d1 on the upper side, which is the sub-valve valve body side.

[0034] The annular recess 6d1 is formed with a depth reaching from the upper end of the disk portion 6a to near the center in the axial direction, and when the sub-valve disk 6 is stacked on the upper side of the main valve assembly A in FIG. 2 with the shim 18 sandwiched therebetween, it faces the horizontal hole 2f opening to the side of the small diameter portion 2a of the piston rod 2. The communication recess 6d2 communicates with the annular recess 6d1, and the horizontal hole 2f forming the opening in the bypass path P is communicated to the compression side chamber R2 via the annular recess 6d1 and the communication recess 6d2. In this way, the annular recess 6d1 and the communication recess 6d2 form a recess 6d extending from the inner periphery to the outer periphery of the disk portion 6a, and even when the sub-valve disk 6 is attached to the outer periphery of the piston rod 2, the opening of the bypass path P is communicated to the compression side chamber R2 by the recess 6d. As described above, the bypass path P is formed by the horizontal hole 2e provided in the piston rod 2 as the shaft member, the horizontal hole 2f as the opening in the piston rod 2, and the recess 6d provided in the sub-valve disk 6. The recess 6d thus provided in the sub-valve disc 6 constitutes a part of the bypass path P.

[0035] In this embodiment, the sub-valve disc 6 has an annular recess 6d1 on the inner circumference of the disc portion 6a. When the annular recess 6d1 is fitted to the outer circumference of the small diameter portion 2a of the piston rod 2 at a position facing the horizontal hole 2f in the axial direction, the horizontal hole 2f and the annular recess 6d1 always face each other without circumferential positioning, and the bypass path P can be reliably communicated with the pressure side chamber R2. Although the depth from the upper end of the disc portion 6a to the bottom of the four communicating recesses 6d2 is shallower than the depth of the annular recess 6d1, the total cross-sectional area of ​​the four communicating recesses 6d2 as viewed from the center of the disc portion 6a is equal to or greater than the cross-sectional area of ​​the annular recess 6d1 in FIG. 2. The total cross-sectional area of ​​the four communicating recesses 6d2 as viewed from the center of the disc portion 6a is the flow path area that is effective when the liquid passes through the communicating recesses 6d2. Therefore, by setting the cross-sectional area as described above, consideration is given to not narrowing the flow path by the communicating recesses 6d2 in the recess 6d. In this embodiment, the communicating recess 6d2 is formed as a vertical groove extending radially from the outer periphery of the annular recess 6d1. However, as long as the annular recess 6d1 is connected to the compression side chamber R2, which is the other side of the working chamber, the shape and structure can be designed as desired, and the number of communicating recesses 6d2 can also be designed as desired as long as the total cross-sectional area of ​​the communicating recesses 6d2 is greater than or equal to the cross-sectional area of ​​the annular recess 6d1.

[0036] Next, the cylindrical portion 6b rises upward in FIG. 2 from the outer periphery of the upper end of the disk portion 6a in FIG. 2, and is provided with an annular seat portion 6c that protrudes radially inward like a flange on the inner periphery of the upper end in FIG. 2. The inner periphery of the seat portion 6c faces the outer periphery of the sub-valve valve body 7 arranged on the inner periphery side with a small gap therebetween, and functions as a valve seat for the sub-valve B. In addition, the axial width of the inner periphery of the seat portion 6c is narrowed, and the upper and lower parts of the seat portion 6c in FIG. 2 are tapered so that the axial width becomes narrower toward the inner periphery, so that the area of ​​the gap between the seat portion 6c and the sub-valve valve body 7 increases quickly when the sub-valve valve body 7 is bent and displaced in the axial direction. In addition, if the axial width of the inner periphery of the seat portion 6c is simply made extremely narrow, the strength of the tip side of the seat portion 6c is reduced, so that eight ribs 6e connected to the seat portion 6c are intermittently provided in the circumferential direction at the upper end of the cylindrical portion 6b in FIG. 2, which are connected to the seat portion 6c, are provided at intervals in the circumferential direction to ensure the strength of the seat portion 6c. The ribs 6e may be provided arbitrarily, and the number of ribs provided and the circumferential width thereof may be changed arbitrarily.

[0037] When the sub-valve disc 6 configured in this manner is stacked above the main valve assembly A via the shims 18, as described above, the annular recess 6d1 faces the horizontal hole 2f and the bypass path P is not blocked by the sub-valve disc 6 and communicates with the compression side chamber R2 via the recess 6d. Note that the axial position of the sub-valve disc 6 with respect to the piston rod 2 is adjusted depending on the number of shims 18 stacked between the main valve assembly A and the sub-valve disc 6, so it is sufficient to adjust the number of shims 18 stacked so that the recess 6d and the horizontal hole 2f face each other in the radial direction.

[0038] The valve stopper 8 is annular and has an outer diameter smaller than the inner diameter of the seat portion 6c of the sub-valve disc 6 so as to be insertable into the cylindrical portion 6b, and is stacked on the upper end of the disc portion 6a in Figure 2 and fitted onto the outer periphery of the small diameter portion 2a of the piston rod 2. When the outer periphery of the sub-valve disc 7 bends axially downward by a predetermined amount in Figure 2, the valve stopper 8 comes into contact with the sub-valve disc 7 to prevent the sub-valve disc 7 from bending excessively.

[0039] A tapered surface 8a is formed from the radially middle portion on the opposite side of the sub-valve body, which is the lower end of the valve stopper 8 in Fig. 2, toward the outer periphery so as to move away from the disk portion 6a, the inner diameter of the tapered surface 8a is larger than the outer diameter of the annular recess 6d1, and a flat surface 8b on the inner side than the tapered surface 8a at the lower end abuts against the outer periphery of the annular recess 6d1 of the disk portion 6a. Therefore, the flat surface 8b of the valve stopper 8 does not enter the annular recess 6d1, but is supported by abutting against the upper end surface of the disk portion 6a in Fig. 2.

[0040] In this way, the valve stopper 8 has a tapered surface 8a on its outer periphery on the side opposite the sub-valve valve body, and the recess 6d has a communicating recess 6d2 that extends radially from the outer periphery of the annular recess 6d1 and has a tip that reaches the outer periphery side beyond the flat surface 8b. An annular gap is created between the disc portion 6a and the tapered surface 8a, and the recess 6d is not blocked even if the valve stopper 8 is placed above the disc portion 6a in Figure 2 while being contained within the cylindrical portion 6b, so there is no need to worry about communication between the bypass path P and the compression side chamber R2 being cut off.

[0041] 2, the sub-valve body 7 in this embodiment is configured to have three elastic leaf valves 7a, 7b, 7c stacked together, the inner periphery of which is fixed to the outer periphery of the small diameter portion 2a of the piston rod 2. Of the three leaf valves constituting the sub-valve body 7, the central leaf valve 7b has an outer diameter larger than the outer diameters of the leaf valves 7a, 7c located at both the upper and lower ends. The number of leaf valves constituting the sub-valve body 7 can be set arbitrarily depending on the damping force generated in the shock absorber D by the valve device V, and may be a single valve instead of a multiple valve.

[0042] The outer diameter of the central leaf valve 7b in the sub-valve disc 7 is slightly smaller than the inner diameter of the annular seat 6c of the sub-valve disc 6, and the sub-valve disc 7 is positioned at a position where the outer peripheral surface of the leaf valve 7b faces the inner peripheral surface of the seat 6c and is fixed to the small diameter portion 2a. Annular spacers 30, 31 are interposed between the lower leaf valve 7c in Fig. 2 and the valve stopper 8, and between the upper leaf valve 7a in Fig. 2 and the valve stopper 9, respectively, and the outer diameter of the spacers 30, 31 is smaller than the outer diameters of the leaf valves 7a, 7c, so that the outer periphery of the sub-valve disc 7 can be deflected in the up-down direction in Fig. 2 with the outer peripheral edges of the spacers 30, 31 on the sub-valve disc side as a fulcrum.

[0043] In addition, when the outer periphery of the leaf valve 7b at the center faces the inner periphery of the annular seat 6c of the sub-valve disc 6 without bending, there is almost no gap between the outer periphery of the leaf valve 7b and the inner periphery of the seat 6c, and the sub-valve B is in a closed state. The gap between the sub-valve valve 7 and the seat 6c communicates with the compression side chamber R2 and also communicates with the expansion side chamber R1 through the inside of the cylindrical part 6b of the sub-valve disc 6, the recess 6d, the horizontal hole 2f, the inside of the piston rod 2, and the horizontal hole 2e. In this way, the sub-valve B functions as a valve that opens and closes the bypass path P. When the damping force control valve 40 provided in the bypass path P, which will be described later, is open and liquid can pass through the bypass path P, the sub-valve B provides a large resistance to the flow of liquid that tries to pass through the bypass path P when it is in a closed state. Therefore, in an extremely low speed range where the piston speed is close to 0, such as when the shock absorber D starts to move, the sub-valve valve 7 does not bend and is maintained in the initial mounting state shown in FIG. 2.

[0044] On the other hand, when the outer periphery of the sub-valve body 7 bends upward or downward in Figure 2, the outer periphery of the leaf valve 7b shifts upward or downward in the axial direction relative to the inner periphery of the seat 6c, increasing the area of ​​the annular gap between the outer periphery of the leaf valve 7b and the inner periphery of the seat 6c, causing the sub-valve B to enter an open state and providing resistance to the flow of liquid passing through the gap according to the size of the gap.

[0045] In addition, when liquid can pass through the bypass path P, the differential pressure between the expansion side chamber R1 and the contraction side chamber R2 when the sub-valve valve body 7 bends and moves away from the seat 6c to open, i.e., the opening pressure of the sub-valve B, is lower than the opening pressures of the compression side leaf valve 4 and the extension side leaf valve 5. When the piston speed is in the low speed range, the sub-valve B opens as described above, but the compression side leaf valve 4 and the extension side leaf valve 5 do not open, and the liquid passes only through the bypass path P.

[0046] The valve stopper 9 is annular, disposed above the sub-valve element 7 in Fig. 2, and fitted onto the outer periphery of the small diameter portion 2a of the piston rod 2. When the outer periphery of the sub-valve element 7 is deflected axially upward by a predetermined amount in Fig. 2, the valve stopper 9 comes into contact with the sub-valve element 7 to prevent the sub-valve element 7 from deflecting excessively. The valve stopper 9 does not need to be housed within the cylindrical portion 6b and is disposed at a position shifted upward from the cylindrical portion 6b in Fig. 2, so that the outer diameter may be larger than the inner diameter of the cylindrical portion 6b. However, if the outer diameter is larger than the inner diameter of the cylindrical portion 6b, the gap between the cylindrical portion 6b and the valve stopper 9 becomes narrow, which may provide unintended resistance to the flow of liquid passing through the bypass path P, so the outer diameter is set to a level that does not provide resistance.

[0047] In addition, a tapered surface 9a is formed from the radial middle portion of the valve stopper 9 on the side opposite the sub-valve body 7, which is the upper end in Fig. 2, to the outer periphery so as to move away from the sub-valve body 7, but the tapered surface 9a does not have to be provided. However, if the tapered surface 9a is provided, the valve stopper 9 can be a common part with the valve stopper 8, making it easier to manage and manufacture the parts of the valve device V.

[0048] The spacer 30 is composed of multiple small-diameter annular plates, and adjusts the axial position of the sub-valve valve body 7 so that the outer periphery of the sub-valve valve body 7 faces the inner periphery of the seat portion 6c of the sub-valve disk 6. The spacer 30 is fitted to the outer periphery of the small-diameter portion 2a, and even if there is a dimensional error in each part stacked below the spacer 30 in FIG. 2, the axial position of the sub-valve valve body 7 can be adjusted to an appropriate position by changing the number of stacked spacers 30. In addition, the spacer 30 not only serves as a fulcrum for the deflection of the sub-valve valve body 7, but also adjusts the axial distance between the sub-valve valve body 7 and the valve stopper 8. Therefore, when the outer periphery of the sub-valve valve body 7 bends downward in FIG. 2 and abuts against the valve stopper 8, further deflection of the sub-valve valve body 7 is restricted, suppressing excessive deflection of the sub-valve valve body 7 and protecting the sub-valve valve body 7, and the maximum deflection amount of the sub-valve valve body 7 can be adjusted by the number of stacked spacers 30.

[0049] Like the spacer 30, the spacer 31 is composed of multiple small-diameter annular plates and is fitted onto the outer periphery of the small diameter portion 2a, and not only serves as a fulcrum for the deflection of the sub-valve disc 7, but also adjusts the axial distance between the sub-valve disc 7 and the valve stopper 9. Therefore, when the outer periphery of the sub-valve disc 7 bends upward in Figure 2 and abuts against the valve stopper 9, further deflection of the sub-valve disc 7 is restricted, suppressing excessive deflection of the sub-valve disc 7 and protecting the sub-valve disc 7, and the maximum amount of deflection of the sub-valve disc 7 can be adjusted by the number of spacers 31 stacked.

[0050] The sub-valve B, main valve assembly A, spacer 15, valve stopper 16 and shim 18 constructed in this manner are assembled to the outer periphery of the small diameter portion 2a of the piston rod 2, and then are clamped between the piston nut 13, which is screwed to the threaded portion 2d formed on the outer periphery of the tip of the small diameter portion 2a, and the step portion 2c of the piston rod 2, and are fixed to the piston rod 2 as a shaft member.

[0051] Next, a damping force control valve 40, which is a needle valve composed of an annular valve seat 41 and a needle valve body 42, is housed in the piston rod 2 between the horizontal holes 2e and 2f which form the bypass path P. The annular valve seat 41 is fitted and fixed to the inner periphery of the piston rod 2. The needle valve body 42 is provided with a conical needle 42a at its upper end in FIG. 2 which is the tip end, and a large-diameter sliding portion 42b which comes into sliding contact with the inner periphery of the piston rod 2 at its lower end in FIG. 2 which is the base end.

[0052] The needle valve body 42, together with the annular valve seat 41, constitutes the damping force control valve 40, and by moving in the vertical direction in FIG. 2, which is the axial direction, inside the piston rod 2, the needle 42a at the tip can be moved closer to or farther from the lower open end of the annular valve seat 41, thereby adjusting the size of the annular gap between the needle 42a and the annular valve seat 41. Thus, when the needle valve body 42 is moved in the axial direction, the damping force control valve 40 can adjust the flow path area and adjust the resistance applied to the flow of liquid passing through the bypass path P. In addition, when the needle 42a of the needle valve body 42 is seated on the open end of the annular valve seat 41, the damping force control valve 40 can close and cut off communication between the expansion-side chamber R1 and the compression-side chamber R2 through the bypass path P.

[0053] 2 below the horizontal hole 2e, and a notched groove 42c is provided on the outer periphery. The outer diameter of the needle valve body 42 above the sliding part 42b in FIG. 2 is smaller than the inner diameter of the piston rod 2, and when the damping force control valve 40 is opened, the liquid can pass between the outer periphery above the sliding part 42b of the needle valve body 42 and the inner periphery of the piston rod 2, and move back and forth through the bypass path P.

[0054] A control rod 43 is inserted into the piston rod 2 to displace the needle valve body 42 in the axial direction. As shown in FIG. 1, the control rod 43 is inserted into the piston rod 2 so as to be movable in the axial direction with its upper end in contact with the lower end of the sliding portion 42b of the needle valve body 42, and its lower end protrudes upward from the lower end of the piston rod 2 and is in contact with an adjuster 44 rotatably attached to the bracket 12. When the adjuster 44 is rotated, the adjuster 44 moves in the lateral direction in FIG. 1 relative to the bracket 12, and displaces the needle valve body 42 in the vertical direction in FIG. 2 within the piston rod 2 through the control rod 43. Thus, by rotating the adjuster 44, the valve opening of the damping force control valve 40 can be adjusted to adjust the flow area in the bypass path P, and the bypass path P can be blocked.

[0055] Next, in this embodiment, as shown in FIG. 1, the cap 11 includes a cap portion 11a that is attached to the upper end of the cylinder 1 in FIG. 1, a tank holding portion 11b that holds the tank 23, and a connection portion 11c that extends from the side of the cap portion 11a and is connected to the tank holding portion 11b.

[0056] The cap portion 11a is cylindrical with a bottom and is attached to the upper end of the cylinder 1 in Fig. 1 to close the upper end of the cylinder 1, and is provided with a bracket 11d at the top, which is the upper part in Fig. 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 by 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 a resilient force to elastically support the vehicle body.

[0057] Returning to the description, a cylindrical tank 23 is attached to the tank holding portion 11b. A free piston 24 is slidably inserted into the tank 23, and the inside of the tank 23 is divided by the free piston 24 into a liquid chamber L filled with liquid and an air chamber G filled with gas. Note that gas is sealed in the air chamber G so that the pressure in the air chamber G is at least equal to or higher than atmospheric pressure when the shock absorber D is fully extended. Note that the liquid chamber L and the air chamber G in the tank 23 may be divided by using a diaphragm, a bladder, or the like, other than the free piston 24.

[0058] The fluid chamber L in the tank 23 is connected to the compression side chamber R2 in the cylinder 1 through a compression side damping passage 11e and a suction passage 11f provided in the connection portion 11c. A compression side damping valve 21 is provided in the compression side damping passage 11e, which allows fluid to flow only from the compression side chamber R2 to the fluid chamber L of the tank 23 and provides resistance to the fluid flow, and an extension side check valve 22 is provided in the suction passage 11f, which allows fluid to flow only from the fluid chamber L to the compression side chamber R2.

[0059] The valve device V and shock absorber D of this embodiment are configured as described above, and the operation of the valve device V and shock absorber D according to this embodiment will be described below. First, the operation of the shock absorber D in a state in which the damping force control valve 40 is fully opened and the flow area of ​​the bypass path P is maximized will be described.

[0060] When the shock absorber D expands, the piston 3 moves downward in the cylinder 1 to compress the expansion-side chamber R1. When the expansion speed of the shock absorber D is in the very low speed range, the pressure in the expansion-side chamber R1 rises, but the pressure difference between the expansion-side chamber R1 and the pressure difference between the expansion-side chamber R2 does not reach the opening pressure of the expansion-side leaf valve 5, so the expansion-side leaf valve 5 does not open and keeps the expansion-side port 3b closed. The compression-side leaf valve 4 receives the pressure in the expansion-side chamber R1 from the back side and closes the compression-side port 3a. When the expansion speed of the shock absorber D is in the very low speed range, the pressure in the expansion-side chamber R1 rises, but the pressure difference between the expansion-side chamber R2 and the pressure difference between the expansion-side chamber R1 and the pressure difference between the compression-side chamber R2 does not reach the opening pressure of the sub-valve B, so the sub-valve B is in a closed state, and a large resistance is applied when the liquid passes through the gap between the leaf valve 7b and the seat 6c of the sub-valve B, and the pressure in the expansion-side chamber R1 rises quickly.

[0061] In addition, as the shock absorber D extends, the piston rod 2 retreats from the cylinder 1, causing a shortage of liquid in the cylinder 1. However, the extension-side check valve 22 opens and the shortage liquid is supplied from the tank 23 to the cylinder 1, compensating for the volume of the piston rod 2 retreating from the cylinder 1.

[0062] In this way, when the extension speed of the shock absorber D is in the extremely low speed range, the shock absorber D generates a damping force that hinders extension mainly due to the resistance that the sub-valve B provides to the liquid. Therefore, when the bypass path P is opened by the damping force control valve 40, the extension side damping force characteristics of the shock absorber D (damping force characteristics relative to the extension speed of the shock absorber D) when the extension speed of the shock absorber D is in the extremely low speed range have a very large damping coefficient and exhibit a large increase in response to an increase in piston speed, as shown in Fig. 4.

[0063] When the extension speed of the shock absorber D is in the low-speed range beyond the very low-speed range, the pressure in the expansion-side chamber R1 rises, but the pressure difference between the pressure in the compression-side chamber R2 does not reach the opening pressure of the expansion-side leaf valve 5, so the expansion-side leaf valve 5 does not open and keeps the expansion-side port 3b closed. The compression-side leaf valve 4 receives the pressure in the expansion-side chamber R1 from the back side and closes the compression-side port 3a. When the extension speed of the shock absorber D is in the low-speed range, the pressure difference between the pressure in the expansion-side chamber R1 and the pressure in the compression-side chamber R2 exceeds the opening pressure of the sub-valve B, so the sub-valve valve body 7 bends, the sub-valve B opens, and the flow path area of ​​the gap between the leaf valve 7b and the seat 6c becomes large. Therefore, the liquid cannot pass through the blocked expansion-side port 3b and the compression-side port 3a, but moves from the expansion-side chamber R1 to the compression-side chamber R2 through the bypass path P. The liquid encounters resistance when passing through the gap between the leaf valve 7b and seat 6c of the open sub-valve B when passing through the bypass path P. Therefore, when the extension speed of the shock absorber D is in the low-speed range, the shock absorber D generates a damping force that hinders extension mainly by the resistance that the sub-valve B provides to the liquid. Therefore, as shown in Figure 4, the damping force characteristics of the extension side of the shock absorber D when the extension speed of the shock absorber D is in the very low-speed range has a smaller slope compared to when the extension speed is in the very low-speed range due to the opening of the sub-valve B.

[0064] Furthermore, when the extension speed of the shock absorber D exceeds the low speed range and is in the medium-high speed range, the pressure difference between the pressure in the expansion-side chamber R1 and the pressure in the compression-side chamber R2 reaches the valve opening pressure of the expansion-side leaf valve 5, and the expansion-side leaf valve 5 bends and opens, opening the expansion-side port 3b. The compression-side leaf valve 4 receives the pressure of the expansion-side chamber R1 from the back side and closes the compression-side port 3a. Also, when the extension speed of the shock absorber D is in the medium-high speed range, the pressure difference between the pressure in the expansion-side chamber R1 and the pressure in the compression-side chamber R2 exceeds the valve opening pressure of the sub-valve B, and the degree of opening of the sub-valve B becomes larger than when the extension speed is in the low speed range. The liquid can pass through the bypass path P, but the expansion-side port 3b as the second main passage is also opened, so the liquid moves from the expansion-side chamber R1 to the compression-side chamber R2 through both. When the extension speed of the shock absorber D is in the medium to high speed range, the flow rate of the liquid moving from the extension side chamber R1 to the compression side chamber R2 increases, so that the sub-valve valve body 7 abuts against the valve stopper 9 to restrict the deflection, and the resistance of the liquid passing through the sub-valve B becomes greater than the resistance of the liquid passing through the extension side leaf valve 5, so that the liquid has difficulty passing through the bypass path P, and most of the liquid moving from the extension side chamber R1 to the compression side chamber R2 passes through the extension side port 3b. Therefore, when the extension speed of the shock absorber D is in the medium to high speed range, the shock absorber D generates a damping force that hinders the extension mainly by the resistance that the extension side leaf valve 5 provides to the liquid. Therefore, the extension side damping force characteristic of the shock absorber D when the extension speed of the shock absorber D is in the medium to high speed range is proportional to the extension speed of the shock absorber D specific to the extension side leaf valve 5 as shown in FIG. 4, but the damping coefficient is smaller than when the extension speed is in the low speed range.

[0065] On the other hand, when the shock absorber D contracts, the piston 3 moves upward in the cylinder 1 to compress the compression side chamber R2. When the contraction speed of the shock absorber D is in the very low speed range, the pressure in the compression side chamber R2 rises, but the pressure difference between the pressure in the expansion side chamber R1 does not reach the valve opening pressure of the compression side leaf valve 4, so the compression side leaf valve 4 does not open and keeps the compression side port 3a closed. The expansion side leaf valve 5 receives the pressure in the compression side chamber R2 from the back side and closes the expansion side port 3b. When the contraction speed of the shock absorber D is in the very low speed range, the pressure in the compression side chamber R2 rises, but the pressure difference between the pressure in the expansion side chamber R1 does not reach the valve opening pressure of the sub-valve B, so the sub-valve B is in a closed state, and a large resistance is applied when the liquid passes through the gap between the leaf valve 7b and the seat 6c in the sub-valve B.

[0066] Furthermore, when shock absorber D contracts, the piston rod 2 enters cylinder 1, and the volume of liquid in cylinder 1 that corresponds to the volume of the piston rod 2 entering cylinder 1 becomes excessive, so the excess liquid moves from inside cylinder 1 to tank 23 via compression side damping valve 21. Therefore, the pressure in compression side chamber R2 is quickly increased by sub-valve B and compression side damping valve 21. Furthermore, when shock absorber D contracts, liquid moves from cylinder 1 to tank 23, compensating for the volume of the piston rod 2 entering cylinder 1.

[0067] In this way, when the contraction speed of the shock absorber D is in the extremely low speed range, the shock absorber D generates a damping force that hinders contraction mainly by the resistance to the liquid provided by the sub-valve B and the compression side damping valve 21. Therefore, in a state in which the bypass path P is opened by the damping force control valve 40, the compression side damping force characteristic of the shock absorber D (the damping force characteristic with respect to the extension speed of the shock absorber D) when the contraction speed of the shock absorber D is in the extremely low speed range has a very large damping coefficient and a characteristic that rises significantly with respect to an increase in the piston speed, as shown in Fig. 4.

[0068] When the contraction speed of the shock absorber D is in the low-speed range beyond the very low-speed range, the pressure in the compression-side chamber R2 rises, but the pressure difference between the pressure in the expansion-side chamber R1 does not reach the opening pressure of the compression-side leaf valve 4, so the compression-side leaf valve 4 does not open and keeps the compression-side port 3a closed. The expansion-side leaf valve 5 receives the pressure in the compression-side chamber R2 from the back side and closes the expansion-side port 3b. When the expansion speed of the shock absorber D is in the low-speed range, the pressure difference between the pressure in the compression-side chamber R2 and the pressure in the expansion-side chamber R1 exceeds the opening pressure of the sub-valve B, so the sub-valve valve body 7 bends, the sub-valve B opens, and the flow path area of ​​the gap between the leaf valve 7b and the seat 6c becomes large. Therefore, the liquid cannot pass through the blocked compression-side port 3a and the expansion-side port 3b, but moves from the compression-side chamber R2 to the expansion-side chamber R1 through the bypass path P. When the liquid passes through the bypass path P, it encounters resistance when passing through the gap between the leaf valve 7b and the seat 6c of the open sub-valve B. Therefore, when the contraction speed of the shock absorber D is in the low-speed range, the shock absorber D generates a damping force that hinders contraction mainly by the resistance that the sub-valve B and the compression side damping valve 21 provide to the liquid. Therefore, as shown in Figure 4, the compression side damping force characteristic of the shock absorber D when the contraction speed of the shock absorber D is in the very low-speed range has a smaller slope compared to when the contraction speed is in the very low-speed range due to the opening of the sub-valve B.

[0069] Furthermore, when the contraction speed of the shock absorber D exceeds the low speed range and is in the medium-high speed range, the pressure difference between the pressure in the expansion-side chamber R1 and the pressure in the contraction-side chamber R2 reaches the valve opening pressure of the contraction-side leaf valve 4, and the contraction-side leaf valve 4 is bent and opens, opening the contraction-side port 3a. The expansion-side leaf valve 5 receives the pressure of the expansion-side chamber R1 from the back side and closes the expansion-side port 3b. Also, when the contraction speed of the shock absorber D is in the medium-high speed range, the pressure difference between the pressure in the expansion-side chamber R2 and the pressure in the expansion-side chamber R1 exceeds the valve opening pressure of the sub-valve B, and the degree of opening of the sub-valve B becomes larger than when the contraction speed is in the low speed range. The liquid can pass through the bypass path P, but the contraction-side port 3a as the first main passage is also opened, so the liquid moves from the contraction-side chamber R2 to the expansion-side chamber R1 through both. When the contraction speed of the shock absorber D is in the medium to high speed range, the flow rate of the liquid moving from the compression side chamber R2 to the expansion side chamber R1 increases, so that the sub-valve valve body 7 abuts against the valve stopper 8 and the deflection is restricted, and the resistance to the liquid passing through the sub-valve B becomes greater than the resistance to the liquid passing through the compression side leaf valve 4, so that the liquid has difficulty passing through the bypass path P, and most of the liquid moving from the compression side chamber R2 to the expansion side chamber R1 passes through the compression side port 3a. Therefore, when the contraction speed of the shock absorber D is in the medium to high speed range, the shock absorber D generates a damping force that prevents contraction mainly due to the resistance to the liquid that the compression side leaf valve 4 and the compression side damping valve 21 provide. Therefore, the damping force characteristic of the compression side of the shock absorber D when the contraction speed of the shock absorber D is in the medium to high speed range is proportional to the contraction speed of the shock absorber D by the compression side leaf valve 4 and the compression side damping valve 21 as shown in FIG. 4, but the damping coefficient is further reduced compared to when the contraction speed is in the low speed range.

[0070] When the damping force control valve 40 is fully open, the situation is as described above; however, by changing the flow area of ​​the bypass path P using the damping force control valve 40, the flow rate of liquid passing through the bypass path P can be adjusted, and the damping force when the expansion / contraction speed of the shock absorber D is in the very low speed range to low speed range can be adjusted.

[0071] Here, the shock absorber D of this embodiment is configured to include a bypass path P that communicates the expansion-side chamber R1 and the compression-side chamber R2 in parallel with the compression-side port 3a as the first main passage and the expansion-side port 3b as the second main passage, a compression-side leaf valve 4 that opens and closes the compression-side port 3a and an expansion-side leaf valve 5 that opens and closes the expansion-side port 3b, and a sub-valve B that opens and closes the bypass path P and has a valve opening pressure lower than the compression-side leaf valve 4 and the expansion-side leaf valve 5. In the shock absorber D configured in this manner, even if the deflection of the sub-valve B is restricted by the valve stoppers 8 and 9, it does not affect the flow of liquid passing through the compression-side port 3a and the expansion-side port 3b.

[0072] That is, in the shock absorber D of this embodiment, the sub-valve B does not become a bottleneck that limits the flow path area of ​​the compression side port 3a as the first main passage and the expansion side port 3b as the second main passage to a minimum. Therefore, even if the expansion / contraction speed of the shock absorber D reaches a high speed range, most of the liquid in the expansion-side chamber R1 compressed by the piston 3 flows through the compression side port 3a or the expansion-side port 3b, so that the pressure loss due to the sub-valve B is added to the pressure loss in the compression side leaf valve 4 or the expansion side leaf valve 5, and override that causes excessive damping force can be suppressed.

[0073] In the shock absorber D of this embodiment, the speed range in which the sub-valve B generates a damping force is the very low speed range, and the speed range in which the compression side leaf valve 4 and the extension side leaf valve 5 generate a damping force is the medium to high speed range. However, the speeds divided into the very low speed, low speed, and medium to high speed range can be set arbitrarily by the designer.

[0074] As described above, the valve device V of the present embodiment includes a piston rod (shaft member) 2, a piston (valve seat member) 3 which is annular and is attached to the outer periphery of the piston rod (shaft member) 2, separates an expansion-side chamber (working chamber) R1 from a compression-side chamber (working chamber) R2, and has a compression-side port (first main passage) 3a and an expansion-side port (second main passage) 3b which communicate the expansion-side chamber (working chamber) R1 and the compression-side chamber (working chamber) R2, respectively, and The main valve assembly A includes a compression side leaf valve (first valve) 4 attached to the piston rod (shaft member) 2 and stacked on one side of the piston (valve seat member) 3 to open and close a compression side port (first main passage) 3a, and an extension side leaf valve (second valve) 5 annularly attached to the outer periphery of the piston rod (shaft member) 2 and stacked on the other side of the piston (valve seat member) 3 to open and close an extension side port (second main passage) 3b. a sub-valve B having a sub-valve valve body 7 which is annular, is attached to the outer periphery of the piston rod (shaft member) 2 and stacked on the disc portion 6a, is allowed to deflect on the outer periphery side, and has an outer periphery facing the inner periphery of the seat portion 6c, and the sub-valve disc 6 has a recess 6d which opens from the inner periphery on the sub-valve valve body side of the disc portion 6a, extends toward the outer periphery, and is in communication with the horizontal hole (opening) 2f to form a part of the bypass path P.

[0075] In the valve device V thus configured, the sub-valve B is stacked on a main valve assembly A including a piston (valve seat member) 3 having a compression side port (first main passage) 3a and an extension side port (second main passage) 3b, a compression side leaf valve (first valve) 4 stacked on the piston (valve seat member) 3, and an extension side leaf valve (second valve) 5 for opening and closing the extension side port (second main passage) 3b. The main valve assembly A includes a sub-valve disc 6 and a sub-valve valve body 7 both of which are attached to the outer periphery of the piston rod (shaft member) 2. Since the sub-valve disc 6 is configured with the main valve assembly A and the disc portion 6a of the sub-valve disc 6 is open to the inner circumference and has a recess 6d facing the horizontal hole (opening) 2f of the bypass passage P, thereby communicating the bypass passage P with the compression side chamber R2, the sub-valve disc 6 does not need to function as a nut that fixes the main valve assembly A to the piston rod (shaft member) 2, nor does it need to have a retaining shaft that holds the sub-valve valve body 7, and the main valve assembly A and the sub-valve B can be fitted onto the piston rod (shaft member) 2 in that order and fixed with one piston nut 13. This makes it possible to shorten the overall length of the valve device V.

[0076] Furthermore, according to the valve device V of this embodiment, the bypass passage P is parallel to the compression side port (first main passage) 3a and the extension side port (second main passage) 3b, so that the pressure loss due to the sub-valve B is added to the pressure loss in the compression side leaf valve (first valve) 4 or the extension side leaf valve (second valve) 5, suppressing override in which the damping force becomes excessive, and an optimum damping force can be generated in the shock absorber D used in the vehicle, improving the ride comfort in the vehicle. As described above, according to the valve device V, it is possible to improve the ride comfort in the vehicle without increasing the overall length.

[0077] Moreover, the recess 6d provided in the sub-valve disc 6 in the valve device V of this embodiment has an annular recess 6d1 provided on the inner periphery of the disc portion 6a on the sub-valve valve body side and facing the horizontal hole (opening) 2f. According to the valve device V configured in this manner, since the inner periphery of the disc portion 6a has the annular recess 6d1 facing the horizontal hole (opening) 2f, it is easy to make the annular recess 6d1 face the horizontal hole (opening) 2f, and even if there is a dimensional error in setting the number of stacked annular plates in the compression side leaf valve (first valve) 4 and the expansion side leaf valve (second valve) 5 and each component of the main valve assembly A, the axial position of the sub-valve disc 6 can be easily positioned to a position where the annular recess 6d1 faces the horizontal hole (opening) 2f, and fine adjustment of the number of stacked shims 18 is also not required. Furthermore, regardless of the circumferential position of the sub-valve disc 6 relative to the piston rod (shaft member) 2, as long as the axial position is correct, the annular recess 6d1 will always face the horizontal hole (opening) 2f, so there is no need to position the sub-valve disc 6 circumferentially relative to the piston rod (shaft member) 2, and this reduces the burden of the assembly work of the valve device V.

[0078] Moreover, the recess 6d provided in the sub-valve disc 6 in the valve device V of this embodiment includes a communication recess 6d2 that extends from the annular recess 6d1 and communicates the annular recess 6d1 with the compression side chamber (the other of the working chambers) R2, and the total cross-sectional area of ​​the communication recess 6d2 when viewed from the center of the disc portion 6a is equal to or greater than the cross-sectional area of ​​the annular recess 6d1. According to the valve device V configured in this manner, even if some part (the valve stopper 8 in this example) associated with the sub-valve valve body 7 is stacked on the disc portion 6a, the recess 6d can ensure communication between the bypass path P and the compression side chamber R2, and the flow path is not narrowed by the communication recess 6d2 in the recess 6d, so that it is possible to prevent unnecessary resistance from being applied to the flow of liquid passing through the recess 6d and unnecessary override from being superimposed on the damping force.

[0079] Furthermore, the shock absorber D of this embodiment includes a cylinder 1, a piston rod 2 inserted into the cylinder 1, and a valve device V, with the piston rod 2 as the shaft member, the valve seat member being slidably inserted into the cylinder 1 to partition the cylinder 1 into an expansion-side chamber R1 and a compression-side chamber R2, and a damping force control valve 40 capable of adjusting the flow path area is provided in the bypass path P. In the shock absorber D configured in this manner, as described above, the main valve assembly A and the sub-valve B can be fitted into the piston rod (shaft member) 2 in that order and fixed with one piston nut 13, and the overall length of the valve device V can be shortened, without increasing the overall length. Furthermore, according to the shock absorber D of this embodiment, since the bypass path P is parallel to the compression side port (first main passage) 3a and the extension side port (second main passage) 3b, the pressure loss due to the sub-valve B is added to the pressure loss in the compression side leaf valve (first valve) 4 or the extension side leaf valve (second valve) 5, and override in which the damping force becomes excessive can be suppressed, and an optimum damping force can be generated for the shock absorber D used in the vehicle, improving the ride comfort of the vehicle. As described above, according to the shock absorber D, the ride comfort of the vehicle can be improved without increasing the overall length. Furthermore, according to the shock absorber D of this embodiment, the flow rate passing through the bypass path P can be reduced compared to the case where the sub-valve B is in series with the compression side port (first main passage) 3a and the extension side port (second main passage) 3b, in which the flow rate increases when the outer diameter of the piston rod 2 is small, so that the maximum deflection amount of the sub-valve valve body 7 can be reduced, deterioration of the sub-valve valve body 7 can be prevented, and the sub-valve valve body 7 with low deflection rigidity can be used. In addition, according to the shock absorber D of this embodiment, since the bypass path P is provided with the damping force adjustment valve 40, it is also possible to adjust the damping force when the expansion / contraction speed of the shock absorber D is in the low speed range.

[0080] In addition, the valve device V in this embodiment is provided in the piston portion of the shock absorber D, with the piston rod 2 of the shock absorber D as the shaft member and the piston 3 as the valve seat member, but the valve device V may be provided between the compression side chamber R2 and the tank 23, with the compression side damping passage 11e as the first main passage, the compression side damping valve 21 as the first valve, the suction passage 11f as the second main passage, the extension side check valve 22 as the second valve, and the working chamber as the compression side chamber R2 and the tank 23.

[0081] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0082] 1 cylinder, 2 piston rod (shaft member), 2f horizontal hole (opening), 3 piston (valve seat member), 3a compression side port (first main passage), 3b extension side port (second main passage), 4 compression side leaf valve (first valve), 5 extension side leaf valve (second valve), 6 sub-valve disc, 6a disc portion, 6b cylindrical portion, 6c seat portion, 6d recess, 6d1 annular recess, 6d2 connecting recess, 7 sub-valve body, A main valve assembly, B sub-valve, D shock absorber, P bypass path, R1 extension side chamber (operating chamber), R2 compression side chamber (operating chamber), V valve device

Claims

1. A shaft member; a main valve assembly including: a valve seat member which is annular and attached to an outer periphery of the shaft member, separating two working chambers and having a first main passage and a second main passage which communicate between the working chambers; a first valve which is annular and attached to an outer periphery of the shaft member and stacked on one side of the valve seat member for opening and closing the first main passage; and a second valve which is annular and attached to an outer periphery of the shaft member and stacked on the other side of the valve seat member for opening and closing the second main passage; a bypass passage provided in the shaft member, communicating one of the working chambers with the other of the working chambers, the bypass passage having an opening on a side of the shaft member and on the other side of the working chamber relative to the main valve assembly; a sub-valve having a sub-valve disc having an annular disc portion attached to the outer periphery of the shaft member and stacked on the main valve assembly, a cylindrical portion rising from the outer periphery of the disc portion, and an annular seat portion provided on the inner periphery of the cylindrical portion; and a sub-valve having a sub-valve body having an annular shape attached to the outer periphery of the shaft member and stacked on the disc portion, the sub-valve body being allowed to deflect on its outer periphery side, with its outer periphery facing the inner periphery of the seat portion, The sub-valve disc has a recess that opens from an inner periphery on the sub-valve valve body side of the disc portion, extends toward an outer periphery, and communicates with the opening to form a part of the bypass passage. A valve device comprising:

2. The recess provided in the sub-valve disc is The disk portion has an annular recess provided on its inner periphery on the sub-valve body side and facing the opening.

2. The valve device according to claim 1.

3. The recess provided in the sub-valve disc is a communication recess extending from the annular recess and communicating the annular recess with the other side of the working chamber; The sum of the cross-sectional areas of the communicating recesses when viewed from the center of the disk portion is equal to or greater than the cross-sectional area of ​​the annular recess.

3. The valve device according to claim 2.

4. A cylinder; A piston rod inserted into the cylinder; The valve device according to any one of claims 1 to 3, The shaft member is the piston rod, the valve seat member is slidably inserted into the cylinder to partition the cylinder into an expansion-side chamber and a compression-side chamber, A damping force adjustment valve capable of adjusting a flow area is provided in the bypass passage. A shock absorber characterized by:

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