Damping valve and shock absorber

Abstract

This damper valve (EV, CV) is provided with: an annular valve body (21, 27) having a fixed end and a free end; a valve seat member (20, 26) having an annular opposing seat section (20b, 26b) that faces the circumferential surface of the free end side of the valve body (21, 27), and a port (20c, 26d) that is provided closer to the fixed end side of the valve body (21, 27) than the opposing seat section (20b, 26b); and orifices (O1, O2) which are provided in the valve bodies (21, 27) or the valve seat members (20, 26) and which communicate the valve seat member side and the opposite side of the valve bodies (21, 27) with each other in a state in which the valve bodies (21, 27) and the opposing seat sections (20b, 26b) face each other.

Description

Technical Field

[0001] The invention relates to a damping valve and a buffer. Background Art

[0002] The shock absorber is, for example, interposed between the vehicle body and wheels to improve the ride comfort of the vehicle. The damping force generated by the shock absorber during expansion and contraction can suppress the vibration of the vehicle body and wheels.

[0003] This type of buffer, for example, has a cylinder, a rod that can be freely movably inserted into the cylinder, a piston that can be freely slidably inserted into the cylinder and divides the cylinder into an extension side chamber and a compression side chamber, a free piston that can be freely slidably inserted into the cylinder and divides the lower part of the compression side chamber in the cylinder into a gas chamber, a damping channel arranged on the piston and connecting the extension side chamber and the compression side chamber, and a damping valve arranged on the damping channel.

[0004] In recent years, in order to improve vehicle ride comfort, the following damping force characteristic requirements have been proposed for vehicle shock absorbers: the damping coefficient is increased in the micro-low speed range, which is lower than the low speed, and the damping force increases rapidly with the switching of the telescopic stroke, while the damping coefficient in the low speed range is smaller than that in the micro-low speed range, and is proportional to the telescopic speed in the medium and high speed range, which is higher than the low speed, but the damping coefficient is smaller than that in the low speed range.

[0005] In order to meet such requirements, the damping valve has a leaf valve and a valve seat component, wherein the leaf valve is annular and has a fixed inner peripheral side and allows the outer peripheral side to flex, while the valve seat component is annular and has an annular relatively set seat portion that is non-contactingly opposite to the outer periphery of the leaf valve and a port on the inner peripheral side of the relatively set seat portion; the damping valve applies resistance to the flow of hydraulic oil shuttling between the extension side chamber and the compression side chamber.

[0006] In a damping valve constructed in this manner, for example, as shown in JP2019-183918A, when the expansion and contraction speed of the buffer is in the micro-low speed range, the leaf valve hardly bends, thereby limiting the flow path area between it and the relatively arranged seat portion to an extremely small amount. Therefore, a damping force characteristic that can increase rapidly relative to the expansion and contraction speed can be obtained, and a damping force characteristic that is more suitable for the vehicle can be achieved. Prior art literature Patent Literature

[0007] Patent Document 1: JP2019-183918A Summary of the Invention Problems to be solved by the invention

[0008] In a conventional damping valve, when the leaf valve is not bent and is in a radially opposite position to the opposite seat, the gap between the leaf valve and the opposite seat is very narrow, and hydraulic oil has difficulty passing through the gap. Therefore, when the expansion and contraction speed of the buffer is in the micro-low speed range, its damping force characteristic exhibits a rapid increase, but increasing the flexural rigidity of the leaf valve may lead to excessive damping force.

[0009] Therefore, an object of the present invention is to provide a damping valve and a shock absorber capable of preventing excessive damping force. Solutions to Problems

[0010] In order to solve the above problems, the damping valve of the present invention has an annular valve body, a valve seat component and a throttle hole, wherein one side of the inner periphery or outer periphery of the annular valve body is a fixed end, and the other side of the inner periphery or outer periphery is a free end and the free end is allowed to bend toward the fixed end; the valve seat component has an annular relatively set seat portion that is annular and opposite to at least a part of the circumference of the free end side of the valve body, and a port arranged on the fixed end side of the valve body in the radial direction than the relatively set seat portion; the throttle hole is arranged on the valve body, and connects the valve seat component side of the valve body with the side opposite to the valve seat component when it is directly opposite to the valve body and the relatively set seat portion.

[0011] With this damping valve structure, even when the free end of the valve body and the opposing seat are facing each other, liquid can still flow through the orifice, in addition to the gap between the valve body and the opposing seat. Therefore, even if the flexural rigidity of the valve body is set high, the damping force will not be excessive when the shock absorber's expansion and contraction speed is within the low-speed range. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a longitudinal sectional view of a shock absorber to which a damping valve according to an embodiment of the present invention is applied. Figure 2 This is a partially enlarged cross-sectional view of a shock absorber to which a damping valve according to an embodiment of the present invention is applied. Figure 3 (A) is a plan view of a first leaf valve constituting a valve element of a damping valve according to an embodiment of the present invention. Figure 3 (B) is a plan view of the second leaf valve constituting the valve element of the damping valve according to the embodiment of the present invention. Figure 3 (C) is a plan view of a third leaf valve constituting a valve element of the damping valve according to one embodiment of the present invention. Figure 4 FIG. 1 is a diagram showing the damping force characteristics of a shock absorber to which the damping valve according to one embodiment of the present invention is applied. Figure 5 This is a partially enlarged cross-sectional view of a damping valve in a first modified example of one embodiment of the present invention. DETAILED DESCRIPTION

[0013] The present invention will be described below based on the embodiments shown in the drawings. Figure 1 and Figure 2 As shown, a shock absorber D in one embodiment comprises a telescopic shock absorber body A having a cylinder 1 as an outer tube and a rod 2 movably inserted into the cylinder 1; an extension-side auxiliary valve EV and a compression-side auxiliary valve CV serving as damping valves, which are disposed between an extension-side chamber R1 and a compression-side chamber R2 serving as working chambers, both of which are disposed within the shock absorber body A. Furthermore, when the shock absorber D is used, it can be interposed between a vehicle body and a wheel (not shown) to suppress vibrations of the vehicle body and the wheel.

[0014] Next, each part of the buffer D is described in detail. Figure 1 As shown, the buffer body A comprises: a cylindrical cylinder 1 with a bottom, which serves as an outer tube; a rod 2, which is movably inserted into the cylinder 1; and a piston 3, which is connected to the rod 2 and, while being movably inserted into the cylinder 1, divides the cylinder 1 into an extension side chamber R1 and a compression side chamber R2 serving as a working chamber.

[0015] Moreover, the rod 2 Figure 1 A bracket (not shown) is provided at the upper end, or base end, of the cylinder 1, and the rod 2 is connected to one of the vehicle body and the wheel via the bracket (not shown). Furthermore, a bracket (not shown) is also provided at the bottom 1a of the cylinder 1, and the cylinder 1 is connected to the other of the vehicle body and the wheel via the bracket (not shown).

[0016] In this way, the shock absorber D is sandwiched between the vehicle body and the wheel. Furthermore, if the wheel vibrates up and down relative to the vehicle body, such as when the vehicle is traveling on an uneven road, the rod 2 moves in and out of the cylinder 1, causing the shock absorber D to expand and contract, while the piston 3 moves up and down (axially) within the cylinder 1.

[0017] The shock absorber body A also includes a rod guide 10, which blocks the upper end of the cylinder 1 while allowing the rod 2 to slide freely within the inner circumference. This creates a sealed space within the cylinder 1. Furthermore, the free piston 11 is slidably inserted on the side opposite the rod 2, as viewed from the piston 3 within the cylinder 1.

[0018] A liquid chamber L is formed above the free piston 11 in the cylinder 1, and a gas chamber G is formed below. Furthermore, the liquid chamber L is divided by the piston 3 into an expansion-side chamber R1 on the rod 2 side and a compression-side chamber R2 on the piston 3 side. Each of the expansion-side chamber R1 and the compression-side chamber R2 is filled with liquid. The liquid filling the shock absorber body A can also be hydraulic oil, water, an aqueous solution, or other liquids. Meanwhile, the gas chamber G contains compressed air, nitrogen, or other gas.

[0019] Furthermore, when the shock absorber D extends, the rod 2 withdraws from the cylinder 1, increasing the volume within the cylinder. When the increase reaches the volume of the withdrawn rod 2, the free piston 11 moves upward within the cylinder 1, expanding the gas chamber G. Conversely, when the shock absorber D contracts, the rod 2 enters the cylinder 1, decreasing the volume within the cylinder. When the decrease reaches the volume of the entered rod 2, the free piston 11 moves downward within the cylinder 1, shrinking the gas chamber G.

[0020] In addition, an air bag, a bellows, or the like may be used instead of the free piston 11 to partition the liquid chamber L and the gas chamber G. The structure of the movable partition wall serving as the partition may be appropriately changed.

[0021] Furthermore, in this embodiment, the damper D is a single-rod, single-cylinder type. When the damper D is extended or retracted, the free piston 11 expands or contracts the gas chamber G to compensate for the volume generated by the rod 2 entering or exiting the cylinder 1. However, the structure for this volume compensation may be appropriately modified.

[0022] For example, if the free piston 11 and gas chamber G are eliminated and an outer tube is provided on the outer periphery of the cylinder 1, a liquid storage chamber is formed between the cylinder 1 and the outer tube to store liquid, and the damper is a multi-tube type, the liquid storage chamber can also compensate for the volume generated by the rod 2 entering or exiting the cylinder 1. Alternatively, the liquid storage chamber can be formed in a liquid reservoir tank separate from the cylinder 1. Furthermore, the damper D can be configured as a double-rod type damper, with the piston 3 mounted in the center of the rod 2 and the ends of the rod 2 protruding from both ends of the cylinder 1.

[0023] The rod 2 is cylindrical and has a reduced outer diameter on the front end side, and comprises a small diameter portion 2a having the smallest diameter on the front end side, and a portion having an outer diameter larger than the small diameter portion 2a and provided on the small diameter portion 2a. Figure 2 The large diameter portion 2b on the upper middle side, the step portion 2c provided at the junction of the small diameter portion 2a and the large diameter portion 2b, the threaded portion 2d provided on the outer periphery of the front end of the small diameter portion 2a, and the threaded portion 2d provided further to the outside than the threaded portion 2d of the small diameter portion 2a. Figure 2 Four through holes 2e, 2f, 2g, and 2h are located in the upper middle portion and are staggered with each other and connect the inside and outside of the small-diameter portion 2a.

[0024] The valve seat component 20, valve body 21, gasket 22 and valve stopper 23, liner 24, partition component 25 on the extension side auxiliary valve EV, the valve seat component 26, valve body 27, gasket 28 and valve stopper 29 on the compression side auxiliary valve CV, main valve stopper 6, compression side main valve 5, piston 3, and extension side main valve 4 are assembled in sequence on the small diameter portion 2a of the rod 2, and are fixed by a piston nut 33 screwed onto the threaded portion 2d at the front end of the small diameter portion 2a.

[0025] like Figure 1 and Figure 2 As shown, the piston 3 is annular and fixed to the outer periphery of the small diameter portion 2a of the rod 2 and in sliding contact with the inner periphery of the cylinder 1, thereby dividing the cylinder 1 into Figure 1 The elongated side chamber R1 on the upper middle side and Figure 1 The compression side chamber R2 at the lower middle side. In addition, the piston 3 is provided with an expansion side passage 3a and a compression side passage 3b for communicating the expansion side chamber R1 and the compression side chamber R2.

[0026] Piston 3 Figure 2 At the lower end of the piston 3, the expansion-side main valve 4 is stacked. This annular expansion-side main valve is fitted onto the outer periphery of the small-diameter portion 2a of the rod 2 and is used to open or close the expansion-side passage 3a. The expansion-side main valve 4 is a laminated leaf valve composed of multiple annular plates. Its inner periphery is fixed to the small-diameter portion 2a of the rod 2, allowing for deflection on the outer periphery. When seated on the lower end of the piston 3, the expansion-side main valve 4 closes the lower outlet of the expansion-side passage 3a. If the outer periphery is deflected and separated from the piston 3, the expansion-side passage 3a is opened and resistance is applied to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2 through the expansion-side passage 3a. Furthermore, the expansion-side main valve 4, seated on the piston 3, closes the expansion-side passage 3a to prevent the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1.

[0027] Piston 3 Figure 2The upper end of the compression side main valve 5 is stacked with the compression side main valve 5, which is annular and is embedded in the outer periphery of the small diameter portion 2a of the rod 2, and is used to open or close the compression side channel 3b. The compression side main valve 5 is a stacked leaf valve composed of a plurality of stacked annular plates, the inner peripheral side of which is fixed to the small diameter portion 2a of the rod 2, allowing the outer peripheral side to bend. Moreover, the compression side main valve 5 closes the outlet end of the upper end of the compression side channel 3b when it is seated on the upper end of the piston 3. If the outer peripheral side is flexed and separated from the piston 3, the compression side channel 3b is opened, and resistance is applied to the flow of liquid from the compression side chamber R2 to the extension side chamber R1 through the compression side channel 3a. In addition, for the flow of liquid flowing from the extension side chamber R1 to the compression side chamber R2, the compression side main valve 5 is seated on the piston 3 to close the compression side channel 3b. In addition, the compression side main valve 5 Figure 2 A main valve stopper 6 is stacked in the upper middle portion. When the compression-side main valve 5 is significantly deflected, the main valve stopper 6 abuts against the side of the compression-side main valve 5 opposite the piston, supporting the compression-side main valve 5 and preventing excessive stress from acting on the compression-side main valve 5, thereby protecting the compression-side main valve 5.

[0028] In this embodiment, if Figure 2 As shown in FIG. 1 , the extension-side auxiliary valve EV used as a damping valve comprises a valve seat member 20, a valve body 21, and an orifice O1 provided on the valve body 21. The valve seat member 20 is annular and comprises: a disc-shaped partition 20a with an opening fitted on the outer periphery of the small-diameter portion 2a; Figure 2 The outer periphery of the middle and lower end is projected downwardly, and the relative seat portion 20b is arranged at a position lower than the separator 20a. Figure 2 The lower end of the relative seat portion 20b is closer to the inner circumference and multiple ports 20c are arranged on the same circumference, and the separator 20a is provided with a plurality of ports 20c. Figure 2 The window 20d of the annular recessed portion is provided at the lower end of the separator 20a and communicates with the outlet end of each port 20c. Figure 2 An annular valve seat 20e protrudes downward from between the opposing seat portion 20b and the port 20c at the middle lower end, and an annular inner peripheral seat portion 20f is provided on the inner peripheral portion of the window 20d.

[0029] The relatively set seat portion 20b surrounds the outer circumference of the annular valve seat 20e with a gap relative to the partition body 20a, protrudes downward and exceeds the lower end of the annular valve seat 20e. That is, when observed from the partition body 20a, the height of the relatively set seat portion 20b is higher than the annular valve seat 20e, and the height difference between the relatively set seat portion 20b and the annular valve seat 20e is greater than the axial thickness of the leaf valve 21a of the valve body 21 described below. In addition, in this embodiment, since the inner periphery of the valve body 21 is a fixed end and the outer periphery is a free end, the annular valve seat 20e is radially arranged on the fixed end side (inner peripheral side) of the valve body 21 relative to the relatively set seat portion 20b of the valve seat member 20. In addition, the inner peripheral seat portion 20f Figure 2 The height of the lower end surface (seat surface) of the annular valve seat 20e is higher than that of the annular valve seat 20e. Figure 2 The height of the middle and lower end surface (seat surface) is lower than the relatively set seat portion 20b.

[0030] In addition, in the present embodiment, the relatively arranged seat portion 20b and the annular valve seat 20e protrude axially relative to the partition body 20a, and an annular recess is formed between the relatively arranged seat portion 20b and the annular valve seat 20e. However, in the case where the inner circumferential side of the valve body 21 is a fixed end, the annular valve seat 20e is provided on the inner circumferential side of the relatively arranged seat portion 20b. If the height of the relatively arranged seat portion 20b is higher than the annular valve seat 20e as described above, the relatively arranged seat portion 20b and the annular valve seat 20e can be provided to protrude axially from the partition body 20a as a whole without an annular recess between the two.

[0031] like Figure 2 As shown, the valve body 21 is composed of three leaf valves 21a, 21b, and 21c. The inner peripheral side of each leaf valve is fixed to the small diameter portion 2a as a fixed end, and the outer peripheral side that allows for deflection is used as a free end. The valve body is superimposed on the partition 20a of the valve seat member 20. Figure 2 The lower end shown is fixed to the outer periphery of the small diameter portion 2a.

[0032] The valve body 21 has a first leaf valve 21a, which is annular and is arranged at Figure 2 The second leaf valve 21b is annular and elastic, stacked on the side of the first leaf valve 21a opposite to the valve seat component, and has the same inner and outer diameters as the first leaf valve 21a; the third leaf valve 21c is annular and elastic, stacked on the side of the second leaf valve 21b opposite to the valve seat component, and has the same inner and outer diameters as the first leaf valve 21a.

[0033] like Figure 3As shown in (A), the first leaf valve 21a is annular and has a hole 21a1 extending in the axial direction. When not subjected to any load and not bent, the peripheral surface of the free end (outer periphery) is directly opposite to the seat portion 20b provided oppositely, and is axially opposite to the annular valve seat 20e through a gap. If it bends toward the valve seat member, it can be seated on the annular valve seat 20e. Figure 3 As shown in (B), the second leaf valve 21b has a cutout 21b1 that is annular and is stacked on the side of the first leaf valve 21a opposite to the valve seat member, and is connected to the hole 21a1 from the free end (outer peripheral end). The cutout 21b1 is constructed to have a plurality of arc-shaped portions 21b2 arranged on the same circumference of the second leaf valve 21b, and a straight portion 21b3 that opens from the outer periphery of the leaf valve 21b and communicates with the arc-shaped portions 21b2. In addition, as shown in FIG. Figure 3 As shown in (C), the third leaf valve 21c is annular and is stacked on the side of the second leaf valve 21b opposite to the valve seat member.

[0034] If the first leaf valve 21a, the second leaf valve 21b and the third leaf valve 21c of the valve body 21 are overlapped, the space communicating with the port 20c on the valve seat member side of the valve body 21 is communicated with the extension side chamber R1 on the opposite side of the valve seat member of the valve body 21 through the hole 21a1 and the cutout 21b1, and the opening on the outer peripheral portion of the second leaf valve 21b that retains the straight portion 21b3 is connected to the straight portion 21b3 of the cutout 21b1. Figure 2 The upper and lower parts of the throttle body 21 are closed by the first leaf valve 21a and the third leaf valve 21c, and the straight portion 21b3 can function as the orifice O1.

[0035] Furthermore, when the valve body 21 of this structure overlaps the inner circumferential seat portion 20f of the partition 20a of the valve seat member 20, the first leaf valve 21a of the valve body 21 becomes radially opposed to the opposing seat portion 20b. Furthermore, because the inner circumferential seat portion 20f is higher than the annular valve seat 20e, it axially faces the annular valve seat 20e through a gap. Thus, the outer circumferential surface of the free end of the first leaf valve 21a of the valve body 21 becomes radially opposed to the inner circumferential surface of the opposing seat portion 20b of the valve seat member 20, with a slight gap. Consequently, when the first leaf valve 21a is directly opposed to the opposing seat portion 20b, the gap between them is extremely small, making it difficult for liquid to pass through this gap. This state is considered the closed state of the extension-side auxiliary valve EV. Thus, when the extension-side auxiliary valve EV is closed, liquid is allowed to pass almost exclusively through the orifice O1. In addition, if at least a portion of the outer peripheral surface of the free end side of the valve body 21 is radially opposite to the relatively set seat portion 20b, the extension-side auxiliary valve EV can open or close the port 20c, so there is no need for the entire outer peripheral surface of the first leaf valve 21a to be radially opposite to the entire inner peripheral surface of the relatively set seat portion 20b.

[0036] The outer diameter of the gasket 22 stacked on the side of the valve body 21 opposite to the valve seat member is smaller than that of the valve body 21 and is fixed to the small diameter portion 2a in an immovable manner. In addition, although the gasket 22 is composed of a single annular plate, it can also be composed of multiple annular plates. Therefore, when the valve body 21 is subjected to the pressure from the valve seat member 20, the gasket 22 is fixed to the small diameter portion 2a. Figure 2 When the pressure of the liquid passes through the port 20c downward, the outer peripheral edge of the gasket 22 is used as a fulcrum to move the outer peripheral side. Figure 2 The first leaf valve 21a deflects downwardly and radially. As a result, the outer circumference of the first leaf valve 21a no longer directly faces the inner circumference of the opposing seat 20b, but instead shifts downward relative to the opposing seat 20b. This causes the area of ​​the flow path formed by the gap between the first leaf valve 21a and the opposing seat 20b to increase as the degree of deflection of the first leaf valve 21a increases. Thus, when the first leaf valve 21a deflects and no longer directly faces the opposing seat 20b, the extension-side auxiliary valve EV opens. The extension-side auxiliary valve EV, through the valve body 21, allows liquid to flow through the gap while also applying resistance to the flow of liquid.

[0037] In addition, the valve body 21 is subjected to the Figure 2 When the pressure of the liquid passes through the port 20c upward, the outer peripheral side of the valve seat member 20 is moved toward the inner peripheral edge of the inner peripheral seat portion 20f as a fulcrum. Figure 2 bends in the upper middle portion. Moreover, when the valve body 21 bends more than the preset deflection amount, the first leaf valve 21a sits on the annular valve seat 20e to close the port 20c. Although the port 20c and the cutout 21b1 are connected through the hole 21a1 when the first leaf valve 21a is seated on the annular valve seat 20e, the outer periphery of the third leaf valve 21c stacked on the opposite side of the valve seat member of the second leaf valve 21b having the cutout 21b1 becomes radially opposite to the relatively set seat portion 20b, and the annular gap between the third leaf valve 21c and the relatively set seat portion 20b becomes extremely small, so it is difficult for the liquid to pass through the gap between the third leaf valve 21c and the relatively set seat portion 20b. Therefore, the extension side auxiliary valve EV used as a damping valve in this embodiment is Figure 2 When the liquid flows downward through the port 20c, the free end of the valve body 21 bends toward the side opposite to the valve seat member to open the valve and allow the liquid to flow. Figure 2 When liquid flows upward through port 20c from the lower center, the free end of valve body 21 flexes toward the valve seat member and seats on annular valve seat 20e, thereby blocking the flow of liquid. In this way, the extension-side auxiliary valve EV functions as a damping valve, opening the valve to allow liquid flowing through port 20c from one side and applying resistance to the flow of liquid. Conversely, it also functions as a check valve, closing the valve to block the flow of liquid flowing through port 20c from the other side.

[0038] Furthermore, the extension-side auxiliary valve EV allows liquid to flow upward from the lower side through the orifice O1 until the valve body 21 flexes toward the valve seat member and the third leaf valve 21c aligns radially with the opposing seat portion 20b. When the valve body 21 functions as a check valve, the amount of deflection until it abuts the annular valve seat 20e and the amount of deflection until the third leaf valve 21c aligns with the opposing seat portion 20b can be adjusted by setting the seat surface height of the inner circumferential seat portion 20f and the annular valve seat 20e. This deflection can also be adjusted by interposing a gasket between the inner circumferential seat portion 20f and the valve body 21. If a gasket is used, the seat surface height of the inner circumferential seat portion 20f is set lower than the seat surface height of the annular valve seat 20e, and the amount of deflection can be adjusted by the number of gaskets stacked.

[0039] The valve stopper 23 is stacked on the side of the gasket 22 opposite to the valve seat component. When the valve body 21 is greatly deflected, it abuts against the valve body 21 to support the valve body 21, thereby preventing excessive stress from acting on the valve body 21 and protecting the valve body 21.

[0040] Valve stopper 23 Figure 2 The liner 24 is formed into a bottomed cylindrical shape, with a hole 24a at the bottom to allow the small diameter portion 2a of the rod 2 to pass through, and a notch 24c that connects the inside and outside is provided on the cylindrical portion 24b, with the opening facing the Figure 2 2a and is fixed to the outer periphery of the small-diameter portion 2a of the rod 2. Furthermore, the cylindrical portion 24b is radially opposed to the through-holes 2e and 2f provided in the small-diameter portion 2a. Therefore, the interior of the cylindrical portion 24b communicates with the interior of the rod 2. Furthermore, since the gasket 24 is disposed on the side of the valve body 21 opposite to the valve seat member, the upper end of the gasket 24 can be utilized as a valve stopper, eliminating the need for the valve stopper 23.

[0041] The partition member 25 is a bottomed cylindrical member with a hole 25a on the bottom thereof for allowing the small diameter portion 2a of the rod 2 to pass therethrough, and the opening side thereof is directed upward to align with the spacer 24. Figure 2The lower end of the valve seat member 20 overlaps with the lower end of the valve seat member 20, while the cylindrical portion fits into the outer circumference of the valve seat member 20 and is fixed to the outer circumference of the small-diameter portion 2a of the rod 2. The outer diameter of the partition member 25 is smaller than the inner diameter of the cylinder 1, forming an annular gap between it and the cylinder 1. Together with the valve seat member 20, it partitions off a space R3 within the expansion-side chamber R1. Space R3 communicates with the expansion-side chamber R1 via the port 20c provided on the valve seat member 20, and with the compression-side chamber R2 via the notch 24c of the gasket 24, the through-holes 2e and 2f in the small-diameter portion 2a, and the interior of the rod 2. Furthermore, the port 20c, space R3, through-holes 2e and 2f, and the interior of the rod 2 form an expansion-side secondary passage EP, which serves as a damping passage connecting the expansion-side chamber R1 and the compression-side chamber R2. This thus constructed expansion-side secondary passage EP is connected in parallel with the expansion-side passage 3a provided on the piston 3, connecting the expansion-side chamber R1 and the compression-side chamber R2. Therefore, the expansion-side sub-valve EV is provided on the expansion-side sub-passage EP, and the expansion-side sub-passage communicates the expansion-side chamber R1 and the contraction-side chamber R2 while bypassing the expansion-side passage 3a.

[0042] In this embodiment, the compression side auxiliary valve CV used as a damping valve is as follows: Figure 2 As shown in FIG. 2 , the sub-valve CV is disposed between the partition member 25 and the compression-side main valve 5 and is attached to the outer periphery of the small-diameter portion 2 a. Specifically, the sub-valve CV includes a valve seat member 26 and a valve body 27 .

[0043] The valve seat member 26 is annular and comprises: a disc-shaped partition 26a having an opening, which is fitted on the outer periphery of the small diameter portion 2a; an annular seat portion 26b which is oppositely arranged from the partition 26a. Figure 2 The outer periphery of the lower end protrudes downward; annular groove 26c, which is provided on the inner periphery of the separator 26a; a plurality of ports 26d, which are larger than the separator 26a Figure 2 The lower end of the relatively set seat portion 26b is closer to the inner peripheral side opening and communicates with the annular groove 26c; the window 26e is located at the separator 26a Figure 2 The lower end of the valve seat 26f is connected to the outlet end of each port 26d and is composed of an annular recess; an annular valve seat 26f is provided at the separator 26a. Figure 2 an annular inner peripheral seat portion 26g, which is provided on the inner peripheral portion of the window 26e; a plurality of limiting portions 26h, which protrude axially from the window 26e of the separator 26a.

[0044] The relatively set seat portion 26b surrounds the outer periphery of the annular valve seat 26f and protrudes further downward than the lower end of the annular valve seat 26f. That is, when viewed from the partition 26a, the height of the relatively set seat portion 26b is higher than the annular valve seat 26f, and the height difference between the relatively set seat portion 26b and the annular valve seat 26f is at least greater than the axial thickness of the leaf valve 27a of the valve body 27 described below. In addition, in this embodiment, since the inner periphery of the valve body 27 is a fixed end and the outer periphery is a free end, the annular valve seat 26f is radially arranged on the fixed end side (i.e., the inner periphery side) of the valve body 27 relative to the relatively set seat portion 26b of the valve seat member 26. In addition, the inner periphery seat portion 26g Figure 2 The height of the lower end surface (seat surface) of the annular valve seat 26f is higher than that of the annular valve seat 26f. Figure 2 The height of the middle lower end surface (seat surface) is lower than the opposite seat portion 26b.

[0045] In addition, in this embodiment, relative to the separator 26a, the relatively set seat portion 26b and the annular valve seat 26f are an integral whole with each other and protrude axially, and the annular valve seat 26f is connected to the inner side of the relatively set seat portion 26b, but when the inner circumferential side of the valve body 27 is a fixed end, on the inner circumferential side of the relatively set seat portion 26b, the annular valve seat 26f can be separated from the relatively set seat portion 26b and protrude from the separator 26a.

[0046] Furthermore, in the compression-side auxiliary valve CV, the valve seat member 26 has a plurality of restricting portions 26h at the lower end of the partition body 26a. These restricting portions 26h protrude axially from the fixed end side (inner circumference side) radially closer to the valve body 27 than the annular valve seat 26f. In this embodiment, the restricting portions 26h are provided between the annular valve seat 26f and the inner circumferential seat portion 26g, and between the ports 26d and 26d within the window 26e in the circumferential direction of the partition body 26a. However, the position of the restricting portions 26h between the annular valve seat 26f and the inner circumferential seat portion 26g can be designed and modified as desired, as long as they do not interfere with the ports 26d. Furthermore, the shape of the restricting portions 26h of the valve seat member 26, when viewed axially, can be either arcuate or circular, and can be designed and modified as desired. Furthermore, the restricting portions 26h are provided at positions avoiding the ports 26d and between the ports 26d and 26d. When the valve body 27 flexes toward the valve seat member, the restricting portions 26h uniformly support the valve body 27 in the circumferential direction. Therefore, they are preferably provided at equal intervals on the same circumference. However, they may be provided at unequal intervals on the same circumference as long as they can support the valve body 27. Furthermore, while the height of the seat surface of the restricting portions 26h is the same as that of the annular valve seat 26f, they may be provided lower than the annular valve seat 26f, as long as they abut against the leaf valve 27a when the valve body 27 is seated on the annular valve seat 26f and thus support the valve body 27.

[0047] like Figure 2 As shown, the valve body 27 is composed of a leaf valve 27a, two elastic annular plates 27b and 27c stacked on the leaf valve 27a, and a partition 26a of the valve seat member 26. Figure 2 The lower end of the small diameter portion 2a is fixed to the outer periphery of the small diameter portion 2a.

[0048] The valve body 27 has a leaf valve 27a which is annular and is arranged at Figure 2 The top of the annular plate 27 is elastic and has a cutout 27a1 opening from the free end (periphery); the annular plate 27b is annular, elastic and stacked on the side of the leaf valve 27a opposite to the valve seat component, and has an outer diameter smaller than the leaf valve 27a; the annular plate 27c is annular, elastic and stacked on the side of the annular plate 27b opposite to the valve seat component, and has an outer diameter smaller than the annular plate 27b.

[0049] Moreover, in the valve body 27 constructed in this manner, the space connected to the port 26d on the valve seat member side of the valve body 27 is connected to the extension side chamber R1 on the opposite side of the valve seat member of the valve body 27 through the incision 27a1 provided on the leaf valve 27a, and the incision 27a1 can play the role of a throttling hole O2.

[0050] Furthermore, when the valve body 27 of this structure overlaps the inner circumferential seat portion 26g of the partition 26a of the valve seat member 26, the leaf valve 27a of the valve body 27 directly faces the opposing seat portion 26b in the radial direction. Furthermore, the inner circumferential seat portion 26g is higher than the annular valve seat 26f, and therefore axially faces the annular valve seat 26f with a gap. Thus, the outer circumferential surface of the free end of the leaf valve 27a of the valve body 27 radially faces the inner circumferential surface of the opposing seat portion 26b of the valve seat member 26, with a slight gap. Therefore, when the leaf valve 27a directly faces the opposing seat portion 26b, the gap between the leaf valve 27a and the opposing seat portion 26b is extremely small, making it difficult for liquid to pass through this gap. This state is considered the closed state of the compression-side auxiliary valve CV. Thus, when the compression-side auxiliary valve CV is closed, liquid is mostly permitted to pass only through the orifice O2. In addition, if at least a portion of the outer peripheral surface of the free end side of the valve body 27 is radially opposite to the relatively set seat portion 26b, the compression side auxiliary valve CV can open or close the port 26d. Therefore, the entire outer peripheral surface of the leaf valve 27a does not need to be radially opposite to the entire inner peripheral surface of the relatively set seat portion 26b.

[0051] The outer diameter of the gasket 28 stacked on the side of the valve body 27 opposite to the valve seat member is smaller than the outer diameter of the annular plate 27c arranged on the side of the valve body 27 opposite to the valve seat member. The gasket is fixed to the small diameter portion 2a in an immovable manner. In addition, although the gasket 28 is composed of a single annular plate, it can also be composed of multiple annular plates. Therefore, when the valve body 27 is subjected to the pressure from the valve seat member 26, the gasket 28 is fixed to the small diameter portion 2a. Figure 2 When the pressure of the liquid flowing downward through the port 26d is applied, the outer periphery of the gasket 28 is used as a fulcrum to cause the outer periphery to move laterally. Figure 2 The leaf valve 27a deflects downwardly and in the middle. This causes the outer circumference of the leaf valve 27a to no longer be in direct radial opposition to the inner circumference of the opposing seat 26b, and the leaf valve 27a deflects downward relative to the opposing seat 26b. The area of ​​the flow path formed by the gap between the leaf valve 27a and the opposing seat 26b increases as the degree of deflection of the leaf valve 27a increases. Thus, when the leaf valve 27a is no longer in direct radial opposition to the opposing seat 26b, the compression-side auxiliary valve CV opens. The compression-side auxiliary valve CV, through the valve body 27, allows liquid to flow through the gap while also applying resistance to the flow of liquid.

[0052] In addition, the valve body 27 is subjected to the pressure from the valve seat member 26. Figure 2 When the pressure of the liquid in the middle and lower part is to flow upward through the port 26d, the outer peripheral side is moved toward the inner peripheral edge of the inner peripheral seat portion 26g of the valve seat member 26. Figure 2 When the valve body 27 deflects beyond the predetermined deflection amount, the leaf valve 27a is seated on the annular valve seat 26f, and the port 26d is maintained in communication with the expansion side chamber R1 only through the orifice O2. In other words, even if the compression side auxiliary valve CV changes from the closed valve state in which the leaf valve 27a and the opposing seat portion 26b are directly opposite in the radial direction to the closed state in which the leaf valve 27a is directly opposite to the opposing seat portion 26b, Figure 2 The pressure of the liquid flowing upward through the port 26d from the middle lower part causes the leaf valve 27a to be seated on the annular valve seat 26f. The expansion side chamber R1 and the port 26d can be connected through the orifice O2 to limit the flow path area. Figure 2 When the liquid flows downward through the port 26d, the free end of the valve body 27 bends toward the side opposite to the valve seat member to open the valve and allow the liquid to flow. Figure 2 As liquid flows upward through port 26d from the lower center, the free end of valve body 27 flexes toward the valve seat member and seats on annular valve seat 26f, resisting the flow of liquid through orifice O2. In this way, the compression-side sub-valve CV functions as a damping valve, opening the valve to allow liquid flowing through port 26d from one side and resisting its flow. Conversely, it also functions as a check valve, effectively restricting the flow of liquid flowing through port 26d from the other side through only orifice O2.

[0053] Furthermore, the compression-side sub-valve CV allows liquid to flow from the lower side to the upper side through port 26d until the valve body 27 flexes toward the valve seat member and seats on the annular valve seat 26f. The amount of flexure until the valve body 27 abuts the annular valve seat 26f can be adjusted by setting the height of the seat surface of the inner circumferential seat portion 26g and the annular valve seat 26f. This flexure can also be adjusted by interposing a gasket between the inner circumferential seat portion 26g and the valve body 27. If a gasket is used, the seat surface height of the inner circumferential seat portion 26g is set lower than the seat surface height of the annular valve seat 26f, and the flexure can be adjusted by adjusting the number of gaskets stacked.

[0054] The valve stopper 29 is stacked on the side of the gasket 28 opposite to the valve seat component. When the valve body 27 is greatly deflected, it abuts against the valve body 27 and supports the valve body 27 to prevent excessive stress from acting on the valve body 27, thereby protecting the valve body 27.

[0055] When the compression-side auxiliary valve CV of this structure is stacked on the outer circumference of the small-diameter portion 2a, below the gasket 24, the annular groove 26c formed on the inner circumference of the valve seat member 26 radially opposes the through-holes 2g and 2h provided in the small-diameter portion 2a. Consequently, the port 26d communicates with the interior of the rod 2. Consequently, the expansion-side chamber R1 communicates with the compression-side chamber R2 via the port 26d, the through-holes 2g and 2h, and the interior of the rod 2. Furthermore, the port 26d, the through-holes 2g and 2h, and the interior of the rod 2 form a compression-side auxiliary passage CP, which serves as a damping passage connecting the expansion-side chamber R1 and the compression-side chamber R2. This compression-side auxiliary passage CP, thus constructed, is connected in parallel with the compression-side passage 3b provided in the piston 3, connecting the expansion-side chamber R1 and the compression-side chamber R2. Therefore, the compression-side sub-valve CV is provided on the compression-side sub-passage CP, and the compression-side sub-passage communicates between the expansion-side chamber R1 and the compression-side chamber R2 while bypassing the compression-side passage 3b.

[0056] Furthermore, a cylindrical rotary valve 12 is housed within the rod member 2. This cylindrical rotary valve has an outer circumferential surface in sliding contact with the inner circumferential surface of the rod member 2, allowing for circumferential rotation within the rod member 2. Rotary valve 12 has holes 12a, 12b, 12c, and 12d, respectively, at positions corresponding to through-holes 2e, 2f, 2g, and 2h, connecting the inside and outside. Rotating rotary valve 12 via a control rod 13 inserted within the rod member 2 not only changes the degree of interconnectivity between through-hole 2e and hole 12a, through-hole 2f and hole 12b, through-hole 2g and hole 12c, and through-hole 2h and hole 12d, but also allows through-holes 2e, 2f, 2g, and 2h to be offset from holes 12a, 12b, 12c, and 12d, thereby blocking them. Specifically, rotary valve 12 can adjust the areas of the four flow paths defined by through-hole 2e and hole 12a, through-hole 2f and hole 12b, through-hole 2g and hole 12c, and through-hole 2h and hole 12d, respectively, based on its rotational position relative to the circumferential direction of rod 2, thereby adjusting the resistance exerted on the flow of hydraulic oil through these flow paths. Furthermore, in this embodiment, control rod 13 is driven by a rotary actuator (not shown), such as a stepping motor, mounted at the distal end of rod 2. The rotary actuator can be housed within rod 2.

[0057] Furthermore, when the rotary valve 12 is in a state where the through-holes 2e and 2f are connected to the corresponding holes 12a and 12b, respectively, the expansion-side chamber R1 and the compression-side chamber R2 are connected via the expansion-side sub-passage EP. Furthermore, when the rotary valve 12 is in a state where the through-holes 2g and 2h are connected to the corresponding holes 12c and 12d, respectively, the expansion-side chamber R1 and the compression-side chamber R2 are connected via the compression-side sub-passage CP. Thus, the rotary valve 12 is positioned midway between the expansion-side sub-passage EP and the compression-side sub-passage CP. Rotating the control rod 13 can change the degree of connection (flow path area) between the holes 12a, 12b, 12c, and 12d and the corresponding through-holes 2e, 2f, 2g, and 2h, respectively, thereby varying the resistance applied to the flow of liquid passing through the expansion-side sub-passage EP and the compression-side sub-passage CP. The rotary valve 12 also includes two holes 12a and 12b for adjusting the flow area of ​​the extension-side auxiliary passage EP, and two holes 12c and 12d for adjusting the flow area of ​​the compression-side auxiliary passage CP. However, the number of holes provided can be arbitrarily changed based on the maximum flow area. Furthermore, the number of through-holes provided in the rod 2 can be set based on the number of holes provided in the rotary valve 12. Furthermore, the holes 12a, 12b, 12c, and 12d provided in the rotary valve 12 can be staggered in the circumferential direction, and the through-holes 2e, 2f, 2g, and 2h provided in the rod 2 can be appropriately positioned to correspond to the holes 12a, 12b, 12c, and 12d. In addition, according to the damping force characteristics required by the buffer D, when the hole 12a and the through hole 2e arranged in the middle of the extension side sub-channel EP are opposite to each other and connected to each other, the hole 12b and the through hole 2f are connected. It can also be set so that the timing when the hole 12a and the through hole 2e are opposite to each other is different from the timing when the hole 12b and the through hole 2f are opposite to each other. This setting method is also applicable to the relationship between the holes 12c, 12d and the through holes 2g, 2h arranged in the middle of the compression side sub-channel CP.

[0058] The expansion-side auxiliary valve EV and the compression-side auxiliary valve CV and the shock absorber D functioning as the damping valve are configured in this manner. Next, operations of the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV and the shock absorber D functioning as the damping valve will be described.

[0059] First, when the buffer D extends, the piston 3 moves in the cylinder 1 toward Figure 1The upward movement compresses the expansion-side chamber R1. With the expansion-side sub-channel EP and the compression-side sub-channel CP connected via the rotary valve 12, the liquid in the expansion-side chamber R1, compressed by the upward movement of the piston 3, attempts to move through the expansion-side channel 3a and the expansion-side sub-channel EP provided on the piston 3 toward the expanded compression-side chamber R2. At this time, when the expansion speed of the damper D is within the slightly low speed range and close to zero, although the pressure in the expansion-side chamber R1 rises, the differential pressure between the pressure in the expansion-side chamber R1 and the pressure in the compression-side chamber R2 does not reach the opening pressure of the expansion-side main valve 4. Therefore, the expansion-side main valve 4 does not open, but maintains the expansion-side channel 3a closed. The compression-side main valve 5, receiving pressure from the expansion-side chamber R1 from behind, closes the compression-side channel 3b.

[0060] When the piston speed of the buffer D is close to zero when it is extended, although the pressure in the extension side chamber R1 rises, the differential pressure between it and the pressure in the compression side chamber R2 does not reach the valve opening pressure of the valve body 21 on the extension side auxiliary valve EV. Even if the valve body 21 is bent to make the outer peripheral surface of the first leaf valve 21a relative to the inner periphery of the relatively set seat portion 20b within the axial width range and become a closed valve state, the flow path area of ​​the annular gap between the valve body 21 and the relatively set seat portion 20b is maintained in an extremely small state, and basically the extension side chamber R1 and the port 20c are connected only through the throttle hole O1.

[0061] On the other hand, when the expansion speed of the damper D is within the slightly slow speed range and near zero, although the pressure in the expansion-side chamber R1 rises, the differential pressure between the expansion-side chamber R1 and the compression-side chamber R2 is small, and the valve body 27 of the compression-side sub-valve CV does not flex toward the valve seat member until it seats on the annular valve seat 26f. Thus, when the expansion speed of the damper D is within the slightly slow speed range and near zero, the valve body 27 maintains the closed position by aligning the outer circumferential surface of the leaf valve 27a with the axial width of the inner circumference of the opposing seat portion 26b. This maintains the flow path area of ​​the annular gap between the valve body 27 and the opposing seat portion 26b at a minimum, allowing communication between the expansion-side chamber R1 and the port 26d essentially only through the orifice O2.

[0062] Therefore, when the expansion speed of the shock absorber D is within the slightly low speed range and close to zero, the expansion-side main valve 4 also closes the expansion-side passage 3a. Since the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV are closed, the liquid in the expansion-side chamber R1 flows through the orifice O1 in the expansion-side auxiliary passage EP and through the orifice O2 in the compression-side auxiliary passage CP, moving toward the compression-side chamber R2. Therefore, when the expansion speed of the shock absorber D is within the slightly low speed range and close to zero, the damping force is generated by the resistance generated when the liquid passes through the orifices O1 and O2. Therefore, the characteristics of the damping force generated in response to the piston speed of the shock absorber D (damping force characteristics) are as follows: Figure 4 As shown, the damping force increases but does not become excessive.

[0063] Furthermore, when the piston speed of the buffer D increases during the extension operation and changes from the slightly low speed range to the low speed range, the pressure difference between the pressure of the extension side chamber R1 and the pressure of the compression side chamber R2 exceeds the valve opening pressure of the valve body 21, so the valve body 21 bends its outer periphery from the axial width range relative to the inner periphery of the seat portion 20b to the inner periphery of the seat portion 20b. Figure 2 The valve is opened by offsetting the center and bottom, making the flow area of ​​the annular gap between the valve body 21 and the opposing seat portion 20b larger than the flow area of ​​the orifice O1. Therefore, liquid can flow from the expansion-side chamber R1 to the compression-side chamber R2 through the expansion-side auxiliary valve EV and the expansion-side auxiliary passage EP. Meanwhile, when the piston speed increases during the extension of the damper D, shifting from the slightly low speed range to the low speed range, the valve body 27 of the compression-side auxiliary valve CV deflects in response to the pressure within the expansion-side chamber R1 and seats on the annular valve seat 26f of the valve seat member 26. Consequently, communication between the port 26d and the expansion-side chamber R1 is maintained only through the orifice O2, allowing liquid to flow through the compression-side auxiliary passage CP. However, the flow area of ​​the expansion-side auxiliary valve EV is larger than that of the orifice O2.

[0064] Therefore, when the piston speed of the buffer D increases during the extension action and changes from the slightly low speed range to the low speed range, the damping force is mainly generated by the valve body 21 of the extension-side auxiliary valve EV and the seat portion 20b provided opposite thereto. The flow path area of ​​the extension-side auxiliary valve EV increases as the piston speed increases. Therefore, the damping force characteristics of the buffer D are as follows: Figure 4 As shown, the slope of its characteristic curve is smaller than the damping force characteristic curve in the micro-low speed range.

[0065] Furthermore, when the piston speed of the buffer D increases and exceeds the low-speed range during the extension action, the valve body 21 bends significantly and abuts against the valve stopper 23, thereby maximizing the flow path area of ​​the annular gap between it and the relatively set seat portion 20b. On the other hand, the extension-side main valve 4 bends away from the piston 3, opening the extension-side channel 3a. As a result, the liquid moves from the extension-side chamber R1 to the compression-side chamber R2 through the gap between the extension-side main valve 4 and the piston 3. As the piston speed increases, the deflection of the extension-side main valve 4 increases, and the flow path area of ​​the gap between the extension-side main valve 4 and the piston 3 becomes larger than the flow path area of ​​the annular gap between the valve body 21 of the extension-side auxiliary valve EV and the relatively set seat portion 20b. Therefore, the buffer D mainly generates damping force through the resistance to the flow of the liquid applied by the extension-side main valve 4. Therefore, when the piston speed increases and exceeds the low-speed range during the extension action of the buffer D, as the piston speed increases, the damping force characteristics of the buffer D change as follows: Figure 4 As shown, the damping force is generated with a nearly constant slope relative to the increase in piston speed. In addition, the resistance applied to the flow of the liquid through the extension-side auxiliary channel EP is adjusted by rotating the rotary valve 12. Therefore, in the shock absorber D of this embodiment, the magnitude of the damping force can be adjusted. In addition, when the shock absorber D is extended, the rod 2 is withdrawn from the cylinder 1, but the free piston 11 is moved toward the cylinder 1. Figure 2 The movement in the middle and upper part causes the gas chamber G to expand to compensate for the volume generated by the rod 2 withdrawing from the cylinder 1.

[0066] Next, when the buffer D contracts, the piston 3 moves in the cylinder 1 toward Figure 1 The downward movement of the piston 3 compresses the compression-side chamber R2. When the extension-side sub-channel EP and the compression-side sub-channel CP are connected via the rotary valve 12, the liquid in the compression-side chamber R2, compressed by the downward movement of the piston 3, attempts to move toward the expanded extension-side chamber R1 through the compression-side channel 3b and the compression-side sub-channel CP provided on the piston 3. When the contraction speed of the shock absorber D is within the slightly low speed range and approaches zero, although the pressure in the compression-side chamber R2 rises, the differential pressure between the pressure in the compression-side chamber R2 and the pressure in the extension-side chamber R1 does not reach the valve-opening pressure of the compression-side main valve 5. Therefore, the compression-side main valve 5 does not open, but instead maintains the compression-side channel 3b closed. The extension-side main valve 4 is subjected to the pressure of the compression-side chamber R2 from the back, thereby closing the extension-side channel 3a.

[0067] When the piston speed during the contraction of the buffer D approaches zero, although the pressure in the compression-side chamber R2 rises, the differential pressure between the pressure in the compression-side chamber R2 and the pressure in the extension-side chamber R1 does not reach the valve-opening pressure of the valve body 27 in the compression-side auxiliary valve CV. Therefore, even if the valve body 27 bends, the outer peripheral surface of the leaf valve 27a is relative to the axial width range of the inner periphery of the relatively set seat portion 26b and becomes a closed valve state, thereby maintaining the flow path area of ​​the annular gap between the valve body 27 and the relatively set seat portion 26b at an extremely small state, and basically only through the throttle hole O2 does the extension-side chamber R1 and the port 26d become connected.

[0068] On the other hand, when the contraction speed of the damper D is within the slightly slow speed range and near zero, although the pressure in the contraction-side chamber R2 rises, the differential pressure between the pressure in the contraction-side chamber R2 and the pressure in the expansion-side chamber R1 is small, and the valve body 21 of the expansion-side sub-valve EV does not flex toward the valve seat member until it seats on the annular valve seat 20e. Thus, when the contraction speed of the damper D is within the slightly slow speed range and near zero, the valve body 21 maintains a closed state by aligning the outer circumference of the first leaf valve 21a with the inner circumference of the opposing seat portion 20b within the axial width. This maintains the flow path area of ​​the annular gap between the valve body 21 and the opposing seat portion 20b at a minimal level, allowing communication between the expansion-side chamber R1 and the port 20c to flow essentially only through the orifice O1.

[0069] Therefore, when the contraction speed of the shock absorber D is within the slightly low speed range and close to zero, the contraction-side main valve 5 also closes the contraction-side passage 3b. Since the extension-side auxiliary valve EV and the contraction-side auxiliary valve CV are closed, the liquid in the contraction-side chamber R2 flows toward the extension-side chamber R1 through the orifice O2 in the contraction-side auxiliary passage CP and through the orifice O1 in the extension-side auxiliary passage EP. Therefore, when the contraction speed of the shock absorber D is within the slightly low speed range and close to zero, the damping force is generated by the resistance generated by the liquid flowing through the orifices O1 and O2. Therefore, the characteristics of the damping force generated in response to the piston speed of the shock absorber D (damping force characteristics) are as follows: Figure 4 As shown, the damping force increases but does not become excessive.

[0070] Furthermore, when the piston speed of the shock absorber D increases during the contraction operation and changes from the slightly low speed range to the low speed range, the pressure difference between the pressure of the compression side chamber R2 and the pressure of the expansion side chamber R1 exceeds the valve opening pressure of the valve body 27. Therefore, the valve body 27 bends its outer periphery from the axial width range relative to the inner periphery of the seat portion 26b to the inner periphery of the seat portion 26b. Figure 2The valve is opened by a mid-downward offset, making the flow area of ​​the annular gap between the valve body 27 and the opposing seat 26b larger than the flow area of ​​the orifice O2. This allows liquid to flow from the compression-side chamber R2 to the expansion-side chamber R1 through the compression-side secondary passage CP via the annular gap between the leaf valve 27a and the opposing seat 26b of the compression-side secondary valve CV. Meanwhile, when the piston speed of the damper D increases during contraction, shifting from the slightly low speed range to the low speed range, the valve body 21 of the expansion-side secondary valve EV deflects in response to the pressure within the compression-side chamber R2, seating on the annular valve seat 20e of the valve seat member 20. At this time, the outer periphery of the third leaf valve 21c, stacked on the opposite side of the valve seat member of the second leaf valve 21b having the cutout 21b1, radially opposes the opposing seat portion 20b. This minimizes the annular gap between the third leaf valve 21c and the opposing seat portion 20b, making it difficult for liquid to pass through the gap between the third leaf valve 21c and the opposing seat portion 20b. Therefore, when the contraction speed of the damper D falls into the low speed range, the expansion-side sub-valve EV closes the opening of the port 26d, preventing liquid from passing through the compression-side sub-passage CP.

[0071] In this way, when the piston speed increases when the buffer D performs a contraction action and changes from a slightly low-speed range to a low-speed range, the compression-side auxiliary valve CV makes the flow path area larger than the flow path area of ​​the throttle hole O2, and the extension-side auxiliary valve EV functions as a check valve to block the extension-side auxiliary channel EP.

[0072] Therefore, when the piston speed of the shock absorber D increases during the contraction operation and changes from the slightly low speed range to the low speed range, the damping force is mainly generated by the valve body 27 of the compression side auxiliary valve CV and the seat portion 26b provided opposite thereto. The flow path area of ​​the compression side auxiliary valve CV increases as the piston speed increases. Therefore, the damping force characteristics of the shock absorber D are as follows: Figure 4 As shown, the slope of its characteristic curve is smaller than the damping force characteristic curve in the micro-low speed range.

[0073] Furthermore, when the piston speed of the buffer D increases and exceeds the low-speed range during its contraction, the valve body 27 bends significantly and abuts against the valve stopper 29, thereby maximizing the flow path area of ​​the annular gap between the relatively set seat portion 26b. On the other hand, the compression-side main valve 5 bends away from the piston 3 to open the compression-side channel 3b. As a result, the liquid moves from the compression-side chamber R2 to the extension-side chamber R1 through the gap between the compression-side main valve 5 and the piston 3. As the piston speed increases, the deflection of the compression-side main valve 5 increases, and the flow path area of ​​the gap between the compression-side main valve 5 and the piston 3 becomes larger than the flow path area of ​​the annular gap between the valve body 27 of the compression-side auxiliary valve CV and the relatively set seat portion 26b. Therefore, the buffer D mainly generates damping force through the resistance applied to the flow of the liquid by the compression-side main valve 5. Therefore, when the piston speed of the buffer D increases and exceeds the low-speed range during its contraction, as the piston speed increases, the damping force characteristics of the buffer D change as follows: Figure 4 As shown, the damping force is generated with a nearly constant slope relative to the increase in piston speed. In addition, the resistance applied to the flow of the liquid passing through the compression-side auxiliary channel CP is adjusted by rotating the rotary valve 12. Therefore, in the shock absorber D of this embodiment, the magnitude of the damping force can be adjusted. In addition, when the shock absorber D is contracted, the rod 2 enters the cylinder 1, but the free piston 11 moves toward the cylinder 1. Figure 2 The movement in the middle and lower part causes the gas chamber G to shrink to compensate for the volume of the rod 2 entering the cylinder 1.

[0074] As described above, the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV, serving as damping valves in this embodiment, comprise annular valve bodies 21, 27, valve seat members 20, 26, and orifices O1, O2. The annular valve bodies 21, 27 have fixed ends on their inner circumferences and free ends on their outer circumferences, allowing the free ends to flex relative to the fixed ends. The valve seat members 20, 26 have annular opposing seats 20b, 26b that oppose at least a portion of the circumference of the free ends of the valve bodies 21, 27, and ports 20c, 26d that are radially closer to the fixed ends of the valve bodies 21, 27 than the opposing seats 20b, 26b. The orifices O1, O2 are provided in the valve bodies 21, 27 to connect the valve seat member side of the valve bodies 21, 27 with the side opposite the valve seat member when the valve bodies 21, 27 and the opposing seats 20b, 26b are facing each other.

[0075] With the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV configured in this manner as damping valves, even when the free ends of the valve bodies 21 and 27 are directly opposed to the opposing seats 20b and 26b, liquid can flow through the orifices O1 and O2, in addition to the gaps between the valve bodies 21 and 27 and the opposing seats 20b and 26b. Therefore, even with high flexural rigidity of the valve bodies 21 and 27, the damping force is not excessive when the shock absorber D is expanding or contracting within the slow speed range. Furthermore, even with high flexural rigidity of the valve bodies 21 and 27, the damping force is not excessive when the shock absorber D is expanding or contracting within the slow speed range. This increases the degree of freedom in designing the flexural rigidity of the valve bodies 21 and 27, making it easier to achieve desired damping force characteristics.

[0076] Furthermore, the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV, which function as damping valves in the present embodiment, open ports 20c and 26d when the valve bodies 21 and 27 deflect toward the side opposite to the valve seat member. When the valve bodies 21 and 27 deflect toward the valve seat member, they seat on the annular valve seats 20e and 26f, functioning as check valves. However, as shown in Japanese Patent Application Laid-Open No. 2019-183918, a valve can be configured to eliminate the annular valve seats 20e and 26f, allowing ports 20c and 26d to be opened regardless of whether the valve bodies 21 and 27 deflect toward the valve seat member or toward the side opposite to the valve seat member.

[0077] In addition, the valve seat components 20, 26 on the extension-side auxiliary valve EV and the compression-side auxiliary valve CV used as damping valves in this embodiment have annular valve seats 20e, 26f, which are arranged between the relatively arranged seat portions 20b, 26b and the ports 20c, 26d and are axially opposite to the valve bodies 21, 27, and can allow the valve bodies 21, 27 to be unseated and seated. According to the extension-side auxiliary valve EV and the compression-side auxiliary valve CV constructed in this manner as damping valves, when subjected to pressure from the port 20c, 26d side, the valve bodies 21, 27 flex to open the ports 20c, 26d and apply resistance to the flow of liquid passing through the ports 20c, 26d. If the valve bodies 21, 27 are subjected to pressure pressed toward the valve seat members 20, 26 side, the valve bodies 21, 27 sit on the annular valve seats 20e, 26f to block the ports 20c, 26d. Therefore, they act as damping valves for the flow of liquid through the ports 20c, 26d from one side, and can act as check valves for the flow of liquid through the ports 20c, 26d from the other side.

[0078] The valve body 21 of the extension-side auxiliary valve EV, which functions as a damping valve in this embodiment, comprises a first leaf valve 21a, which is annular and has its free end circumference (i.e., outer periphery) facing the opposing seat portion 20b. It has a hole 21a1 extending axially therethrough and is removably seated on the annular valve seat 20e. A second leaf valve 21b, which is annular and stacked on the opposite side of the first leaf valve 21a from the valve seat member, has a notch 21b1 extending from its free end (i.e., outer periphery) and communicating with the hole 21a1. A third leaf valve 21c, which is annular and stacked on the opposite side of the second leaf valve 21b from the valve seat member, forms the orifice O1. The notch 21b1 forms the orifice. With the expansion-side auxiliary valve EV configured in this manner as a damping valve, when the valve body 21 deflects away from the valve seat member and leaves the valve seat member 20, the valve body 21 applies resistance to the flow of liquid passing through the gap between the valve body 21 and the opposing seat portion 20b, thereby functioning as a damping valve. Furthermore, when the valve body 21 deflects toward the valve seat member and seats on the annular valve seat 20e, the free end (i.e., the outer periphery) of the third leaf valve 21c faces the opposing seat portion 20b, minimizing the gap between the third leaf valve 21c and the opposing seat portion 20b and making it difficult for liquid to pass through this gap. Consequently, even with the orifice O1, the expansion-side auxiliary valve EV, which functions as a damping valve, can substantially close the port 20c when functioning as a check valve. Therefore, the damping force characteristics of the expansion side of the shock absorber D can be individually set.

[0079] Furthermore, the valve body 27 of the compression-side auxiliary valve CV, which functions as a damping valve, has a notch 27a1. This notch is annular, with the circumference of its free end (i.e., its outer periphery) facing the opposing seat portion 26b, and opens from the free end (i.e., its outer periphery). The orifice O2 can be formed by this notch 27a1. Thus, when the compression-side auxiliary valve CV functions as a check valve, and when the valve body 27 does not need to completely block the port 26d, the port 26d can be opened by flexing the valve body 27 toward either the valve seat member or the side opposite the valve seat member. This simplifies the design of the orifice O2 by simply providing the notch in the free end of the valve body 27. Furthermore, when the slit 27a1 is provided on the outer circumference of the valve body 27 to form the orifice O2, if it is desired that the valve body 27 be seated on the annular valve seat 26f to block the port 26d, the depth of the slit 27a1 can be set so that the tip of the slit 27a1 does not face the port 26d when the valve body 27 is seated on the annular valve seat 26f. In this manner, when the valve body 27 is subjected to pressure from the expansion-side chamber R1 from behind and seats on the annular valve seat 26f, the communication between the slit 27a1 and the port 26d is severed, allowing the valve body 27 to block the port 26d. Thus, even when the slit 27a1 is provided on the free end of the valve body 27 to form the orifice O2, the valve body 27 can completely block the port 26d.

[0080] In addition, if Figure 5 As shown, the throttle hole may also be formed by a groove 26b1 provided on the relatively set seat portion 26b of the valve seat member 26 instead of being provided on the valve body 27. When the extension side auxiliary valve EV and the compression side auxiliary valve CV used as the damping valve play the function of the check valve, when there is no need to completely block the port 26d by the valve body 27, the port 26d can be opened regardless of whether the valve body 27 is bent toward the valve seat member side or the side opposite to the valve seat member. Therefore, it is sufficient to provide the groove 26b1 for forming the throttle hole on the relatively set seat portion 26b. Therefore, the setting of the throttle hole is simplified.

[0081] In the above case, the inner circumferences of the valve bodies 21 and 27 are fixed ends, while the outer circumferences are free ends. The outer circumferences of the valve bodies 21 and 27 are opposed to the inner circumferences of the opposing seats 20b and 26b, thereby forming the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV, which function as damping valves. However, the outer circumferences of the valve bodies can also be fixed ends, while the inner circumferences are free ends. An opposing seat can be provided on the inner circumference of the valve bodies, and the inner circumference of the valve bodies can be opposed to the outer circumferences of the opposing seats to form a damping valve. In this case, the orifice can be formed by a cutout extending from the inner circumference of the valve body.

[0082] In addition, the valve seat member 26 of the compression side auxiliary valve CV of the damping valve in this embodiment also has a limiting portion 26h, which is arranged on the fixed end side of the valve body 27 radially closer to the annular valve seat 26f and is axially opposite to the valve body 27. When the free end of the valve body 27 is deflected toward the valve seat member side by more than a specified amount, the limiting portion abuts against the valve body 27 to limit the deflection of the valve body 27.

[0083] According to the compression-side auxiliary valve CV used as a damping valve constructed in this manner, when the middle portion of the valve body 27 is pressed toward the valve seat member and bends to abut against the limiting portion 26h, the middle portion of the valve body 27 will also be supported by the limiting portion 26h to prevent the valve body 27 from further bending. Therefore, even if excessive pressure acts on the valve body 27, the stress acting on the leaf valve 27a can be reduced, thereby suppressing fatigue of the leaf valve 27a.

[0084] The shock absorber D of this embodiment includes a cylinder (outer tube) 1, a rod 2 axially movably inserted into the cylinder (outer tube) 1, a shock absorber body A having at least an expansion-side chamber (operating room) R1 and a compression-side chamber (operating room) R2, which is reciprocated by the movement of the rod 2 relative to the cylinder (outer tube) 1, and an expansion-side auxiliary valve EV and a compression-side auxiliary valve CV, which serve as damping valves and are disposed between the expansion-side chamber (operating room) R1 and the compression-side auxiliary valve CV. The shock absorber D thus configured, by including the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV, can suppress the occurrence of excessive damping force when the shock absorber D's expansion and contraction speed is in the slow and slow speed range, thereby improving vehicle ride comfort. In addition, a damping force is generated when the liquid flows from the extension side chamber R1 to the compression side chamber R2, and the extension side sub-channel EP can be closed when the liquid flows from the compression side chamber R2 to the extension side chamber R1. Therefore, the damping force characteristics of the extension side of the buffer D can be set separately, and the compression side sub-valve CV generates a damping force when the liquid flows from the compression side chamber R2 to the extension side chamber R1, and applies resistance through the throttle hole O2 when the liquid flows from the extension side chamber R1 to the compression side chamber R2. Therefore, the damping force characteristics of the compression side of the buffer D can be set separately.

[0085] Furthermore, in the shock absorber D of this embodiment, the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV, which function as damping valves, are disposed in the expansion-side auxiliary passage EP and the compression-side auxiliary passage CP, which bypass the expansion-side passage 3a and the compression-side passage 3b, respectively, of the piston 3. The damping valves are connected in parallel with the expansion-side main valve 4 and the compression-side main valve 5 of the piston 3. However, the damping valves may also be utilized as either the expansion-side main valve or the compression-side main valve. Furthermore, in the shock absorber D of this embodiment, the expansion-side auxiliary valve EV and the compression-side auxiliary valve CV, which function as damping valves, are disposed in the expansion-side auxiliary passage EP and the compression-side auxiliary passage CP, which bypass the expansion-side passage 3a and the compression-side passage 3b, respectively, of the piston 3. However, it is also possible to provide only the expansion-side auxiliary valve EV or only the compression-side auxiliary valve CV in the shock absorber D.

[0086] In addition, if Figure 1 As shown, the two working chambers serve as the expansion-side chamber R1 and the compression-side chamber R2, respectively. However, if the shock absorber D is a multi-tube type shock absorber having a housing serving as an outer tube around the outer periphery of the cylinder and a fluid reservoir between the cylinder and the housing, a damping valve DV may be provided between the compression-side chamber and the fluid reservoir. Thus, the damping valve port can connect the expansion-side chamber R1 with the compression-side chamber R2, or it can connect the compression-side chamber with the fluid reservoir.

[0087] In addition, in the shock absorber D of this embodiment, the speed range in which the damping force is generated mainly by the extension-side auxiliary valve EV and the compression-side auxiliary valve CV serving as damping valves is set to the low-speed range, but the designer can arbitrarily set the speed values ​​used to divide the speed into slightly low speed, low speed and speed higher than low speed.

[0088] While the preferred embodiments of the present invention have been described in detail above, modifications, variations, and alterations may be made without departing from the scope of the claims. Explanation of symbols

[0089] 1 cylinder (outer tube) 2 rods 20, 26 valve seat components 20b, 26b are provided with seats opposite to each other 26b1 groove Ports 20c and 26d 20e, 26f annular valve seat 26h Restriction Department 21, 27 valve body 21a First leaf valve 21b Second leaf valve 21b1, 27a1 incisions 21c Third leaf valve A. Buffer body CV compression side auxiliary valve (damping valve) D buffer EV extension side auxiliary valve (damping valve) O1, O2 throttle holes R1 extension side chamber (studio) R2 compression side chamber (studio)

Claims

1. A damping valve, comprising: An annular valve body, wherein one of the inner or outer circumferences is a fixed end and the other of the inner or outer circumference is a free end that allows the free end to flex relative to the fixed end; The valve seat member is annular and has an annular opposing seat portion opposing at least a portion of the circumferential surface of the free end side of the valve body, and a port arranged radially closer to the fixed end side of the valve body than the opposing seat portion. The throttle hole is provided on the valve body or the valve seat member, and connects the valve seat member side of the valve body with the side opposite to the valve seat member in a state where the valve body and the oppositely provided seat portion are directly opposed to each other.

2. The damping valve according to claim 1, wherein: The valve seat component has an annular valve seat, The valve body is disposed between the oppositely disposed seat portion and the port and is opposite to the valve body in the axial direction and can allow the valve body to be seated thereon.

3. The damping valve according to claim 2, wherein: The valve body has: a first leaf valve, which is annular and has a circumferential surface of a free end facing the oppositely disposed seat portion, has a hole penetrating in the axial direction, and can be seated on the annular valve seat; a second leaf valve having an annular shape and being stacked on the side of the first leaf valve opposite to the valve seat member and having a cutout opening communicating with the hole from a free end opening; a third leaf valve having an annular shape and stacked on the side of the second leaf valve opposite to the valve seat member; The throttle hole is formed by the cutout.

4. The damping valve according to claim 1, wherein: The valve body has: The cutout is annular and has a peripheral surface of a free end that is directly opposite to the oppositely disposed seat portion and opens from the free end. The throttle hole is formed by the cutout.

5. The damping valve according to claim 1, characterized in that The valve seat member has a groove formed on the oppositely disposed seat portion; The throttle hole is formed by the groove.

6. A buffer, characterized in that: have: A buffer body having an outer tube, a rod inserted into the outer tube movably in the axial direction, and at least two working chambers in which the liquid is reciprocated by the movement of the rod relative to the outer tube; The damping valve according to any one of claims 1 to 5, which is arranged between the working chambers.

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