JP2024052377A - Shock absorbers, suspension systems - Google Patents

Abstract

[Problem] To provide a technology that can improve both ride comfort in the high piston speed range and handling stability in the low piston speed range. [Solution] A groove 39 recessed annularly from a first outer round portion 37 is formed in a piston 31, and a plurality of laminates arranged such that the inner periphery side is supported by the piston 31 and the outer periphery side is a free end include a first laminate 101 seated on the first outer round portion 37, a second laminate 102 arranged on the opposite side of the piston 31 with respect to the first laminate 101, and a third laminate 103 arranged on the opposite side with respect to the second laminate 102, and the second laminate 102 has a recess formed on the outer periphery that partially deflects the first laminate 101 when the pressure in the second oil chamber becomes higher than the pressure in the first oil chamber, and a ring 142 that deflects the third laminate 103 so that the outer periphery is positioned on the opposite side of the inner periphery when no pressure difference occurs between the first oil chamber and the second oil chamber. [Selected Figure] Figure 2

Description

The present invention relates to a shock absorber and a suspension system.

For example, the valve structure of the shock absorber described in Patent Document 1 is configured as follows. In other words, the cylinder is divided into two oil chambers by a partition member that includes a valve member that forms a circular elastic plate and is supported on its inner or outer periphery side, and a valve seat that receives the free end side of the valve member. A damping flow path is formed by the deflection of the valve member according to the pressure difference between these two oil chambers, and a damping force is applied to the forward and backward movement of the piston rod relative to the cylinder. In this valve structure, the valve member is configured by overlapping a sub-valve, an intermediate seat, and a main valve that form a circular elastic plate with the same inner and outer diameters from the valve seat side, and the seat surface of the valve seat is circular and abuts against the sub-valve. In addition, the intermediate seat is formed with a sector-shaped cutout that opens to the free end side and partially deflects the sub-valve, and the sub-valve opens from the part that corresponds to the cutout.

Patent No. 3471438

The shock absorber described in Patent Document 1 had room for improvement in terms of improving the ride comfort of the vehicle when the piston speed is in the high-speed range while improving the vehicle handling stability when the piston speed is in the low-speed range.
An object of the present invention is to provide a shock absorber and the like that can achieve both improved ride comfort in the high piston speed range and improved handling stability in the low piston speed range.

The present invention, which was completed with such a purpose, comprises a piston that divides an oil chamber in a cylinder in which hydraulic oil is accommodated into a first oil chamber and a second oil chamber, and a plurality of laminates that are supported on the piston at the inner periphery and arranged so that the outer periphery is a free end, and that are elastically deformable when the pressure in the second oil chamber becomes higher than the pressure in the first oil chamber, and that are laminated in the center line direction of the cylinder. The piston is formed with a groove that is recessed annularly from the seating surface on the side of the first oil chamber, and a communication passage that communicates the groove with the second oil chamber, and the plurality of laminates are formed by connecting the piston to the seating surface on the side of the first oil chamber. The shock absorber has a first stack that sits on the seat of the piston, a second stack that is disposed on the opposite side of the first stack from the piston, and a third stack that is disposed on the opposite side of the second stack, and the second stack has a recess that is formed on the outer periphery and that partially deflects the first stack when the pressure in the second oil chamber becomes higher than the pressure in the first oil chamber, and a protrusion that deflects the third stack so that the outer periphery is positioned on the opposite side from the inner periphery when there is no pressure difference between the first oil chamber and the second oil chamber.

The present invention makes it possible to improve both ride comfort at high piston speeds and handling stability at low piston speeds.

1 is a diagram showing an example of a schematic configuration of a suspension device according to a first embodiment; FIG. 2 is a diagram showing an example of a schematic configuration of a piston portion. 13 is a diagram showing an example of a piston as viewed in the axial direction from a second side. FIG. FIG. 2 is a diagram showing an example of a piston as viewed in the axial direction from a first side. FIG. 4 is a diagram showing an example of a partial perspective view of components that configure a piston portion. FIG. 13 is a view showing an example of a third valve as viewed in the axial direction. FIG. 13 is a view showing an example of a fourth valve as viewed in the axial direction. FIG. 4 is a diagram showing an example of a damping force characteristic of a shock absorber. FIG. 13 is a diagram showing an example of a third valve according to a first modified example. FIG. 13 is a diagram showing an example of a third valve according to a second modified example. FIG. 13 is a diagram illustrating an example of a third valve according to a third modified example. FIG. 13 is a diagram showing an example of a fourth valve according to a first modified example when viewed in the axial direction from a first side. FIG. 13 is a diagram showing an example of a fourth valve according to a second modified example when viewed in the axial direction from the first side. FIG. 11 is a partial cross-sectional view showing an example of a fourth valve according to a second modified example. FIG. 13 is a diagram showing an example of a schematic configuration of a second stack of an expansion side damping valve group according to a second embodiment, as viewed in the axial direction from a first side. 13A and 13B are diagrams illustrating an example of a convex portion according to a first modified example. 13A and 13B are diagrams illustrating an example of a convex portion according to a second modified example. FIG. 13 is a diagram showing an example of a schematic configuration of a second stack according to a third embodiment. A diagram showing an example of a schematic configuration of a second stack according to a fourth embodiment, as viewed in the axial direction from the second side. FIG. 13 is a diagram showing an example of a schematic configuration of a second stack according to a fifth embodiment, as viewed in the axial direction from the first side. A figure showing an example of a schematic configuration of a second stack according to a sixth embodiment when viewed in the axial direction from the first side, and a figure showing an example of a schematic configuration of a third valve when viewed in the axial direction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
First Embodiment
FIG. 1 is a diagram showing an example of a schematic configuration of a suspension device 1 according to the first embodiment.
The suspension system 1 is a strut-type suspension used in four-wheeled vehicles such as passenger automobiles, and as shown in Fig. 1, comprises a hydraulic shock absorber 2 and a coil spring 3 arranged on the outside of the shock absorber 2. The suspension system 1 also comprises a lower spring seat 4 that supports an end of the coil spring 3 on a first axial side (lower side in Fig. 1) of a rod 20 described below, and an upper spring seat 5 that supports an end of the coil spring 3 on a second axial side (upper side in Fig. 1) of the rod 20.

The suspension 1 also includes a vehicle body bracket 6 that is attached to the second axial end of the rod 20 for mounting the suspension 1 to a vehicle, and a wheel side bracket 7 that is fixed to the first axial end of the rod 20 in the cylinder section 10 (described later) for mounting the suspension 1 to a wheel. The suspension 1 also includes a dust cover 8 that covers at least a portion of the cylinder section 10 and the rod 20.

Below, the axial direction of the rod 20 may be simply referred to as the "axial direction". The axial direction is also the direction of the center line of the cylindrical cylinder 11, which will be described later. In the axial direction, the first side (lower side in FIG. 1) and the second side (upper side in FIG. 1) may be simply referred to as the "first side" and the "second side", respectively. Also, the direction that intersects with the axial direction (e.g., the perpendicular direction) may be referred to as the "radial direction". In the radial direction, the center line side of the cylinder 11 may be simply referred to as the "inner side", and the side away from the center line may be simply referred to as the "outer side".

The shock absorber 2 includes a cylinder portion 10 that contains oil as an example of hydraulic oil, and a rod 20 whose second end protrudes from the cylinder portion 10 and whose first end is slidably inserted into the cylinder portion 10. The shock absorber 2 also includes a piston portion 30 provided at the first end of the rod 20, and a bottom portion 50 provided at the first end of the cylinder portion 10.

The cylinder section 10 has a cylinder 11 that contains oil and an outer cylinder body 12 that is provided on the outside of the cylinder 11. The cylinder section 10 also has a rod guide section 14 that movably supports the rod 20, a bump stopper cap 15 that is attached to the second end of the outer cylinder body 12, and an oil seal 16 that prevents oil from leaking from within the cylinder section 10 and prevents foreign matter from entering the cylinder section 10.

FIG. 2 is a diagram showing an example of a schematic configuration of the piston portion 30. As shown in FIG.
FIG. 3 is a diagram showing an example of the piston 31 as viewed in the axial direction from the second side.
FIG. 4 is a diagram showing an example of the piston 31 when viewed in the axial direction from the first side.
FIG. 5 is a diagram showing an example of a partial perspective view of components that configure the piston portion 30. As shown in FIG.

The piston section 30 moves in the axial direction in accordance with the movement of the rod 20. The piston section 30 includes a piston 31 having a plurality of oil passages (described later) formed therethrough in the axial direction, a compression side damping valve group 40 provided on the second side of the piston 31, and an extension side damping valve group 100 provided on the first side of the piston 31. The piston section 30 also includes an annular member 44 arranged on the first side of the extension side damping valve group 100, a valve stopper 45, and a nut 46. The piston 31, the compression side damping valve group 40, the extension side damping valve group 100, the annular member 44, and the valve stopper 45 are fastened to the rod 20 by the nut 46.

(Piston 31)
The piston 31 divides the space inside the cylinder 11 into a first oil chamber Y1 which is a space on a first side in the axial direction, and a second oil chamber Y2 which is a space on a second side in the axial direction.
The piston 31 has a through hole 31H provided on the inside, a compression side oil passage 311 provided on the outside of the through hole 31H, and an extension side oil passage 312 provided on the outside of the through hole 31H.

The piston 31 also has a second inner round portion 32 provided on the inside of the second side and a second outer round portion 33 provided on the outside of the second side. The piston 31 also has a second inclined portion 34 provided on the second side and an outer end portion 35 provided on the second side.

The piston 31 also has a first inner round portion 36 provided on the first side, a first outer round portion 37 provided on the first side, and an annular protrusion portion 38 provided on the first side.

The through hole 31H is formed in the axial direction of the piston 31. The end portion of the rod 20 on the first side is inserted into the through hole 31H. In this way, the piston 31 is attached to the tip portion of the rod 20 on the first side.
The compression side oil passage 311 is an oil passage that enables oil to flow between the first oil chamber Y1 and the second oil chamber Y2 during the compression stroke of the shock absorber 2. As shown in Fig. 3, the compression side oil passage 311 is provided at a plurality of locations (four locations in this embodiment) at approximately equal intervals in the circumferential direction.
The extension-side oil passage 312 is an oil passage that enables oil to flow between the second oil chamber Y2 and the first oil chamber Y1 during the extension stroke of the shock absorber 2. As shown in Fig. 4, the extension-side oil passage 312 is provided at a plurality of locations (four locations in this embodiment) at approximately equal intervals in the circumferential direction.

The second inner round portion 32 is formed in a substantially annular shape and is provided on the outer periphery of the through hole 31H. The second inner round portion 32 protrudes in the axial direction further toward the second side from the second end face 31A formed on the second side. In this embodiment, the second inner round portion 32 contacts an inner portion of the compression side damping valve group 40.

The second outer round portion 33 is formed in a substantially annular shape and is formed outside the pressure side oil passage 311. The second outer round portion 33 protrudes further in the axial direction from the second end face 31A toward the second side. The protruding height of the second outer round portion 33 is slightly higher than that of the second inner round portion 32.

The second outer round portion 33 is formed along a plane that is approximately perpendicular to the axial direction of the piston 31. The second outer round portion 33 is the most protruding part on the second side of the piston 31. The second outer round portion 33 forms a part that contacts the outer part of the compression side damping valve group 40.

The second inclined portion 34 is formed by a surface that is inclined with respect to the axial direction of the piston 31. The second inclined portion 34 is connected to the second outer round portion 33 and the outer end portion 35, respectively.
The outer end portion 35 is provided outward from the second inclined portion 34. In addition, the outer end portion 35 is formed by a surface that is approximately perpendicular to the axial direction of the piston 31.

The first inner round portion 36 is formed in a substantially annular shape and is provided on the outer periphery of the through hole 31H. The first inner round portion 36 protrudes in the axial direction further toward the first side from the first end face 31B formed on the first side. In this embodiment, the first inner round portion 36 contacts an inner portion of the extension side damping valve group 100.

The first outer round portion 37 is formed in a substantially circular ring shape. The first outer round portion 37 is formed on the first side, outside the extension side oil passage 312 and inside the compression side oil passage 311. The first outer round portion 37 protrudes further in the axial direction toward the first side from the first end face 31B. The protruding height of the first outer round portion 37 is slightly higher than that of the first inner round portion 36. In this embodiment, the first outer round portion 37 protrudes toward the extension side damping valve group 100 and functions as a seating surface on which a first valve 110 (described later) of the extension side damping valve group 100 is seated.

A first inner round portion 36 is provided on the inside of the first end face 31B, and a first outer round portion 37 is provided on the outside of the first end face 31B, so that an annular groove 39 recessed from the first outer round portion 37 to the second side is formed outside the first inner round portion 36 and inside the first outer round portion 37. The groove 39 communicates with the second oil chamber Y2 via the extension side oil passage 312. In other words, the extension side oil passage 312 functions as a communication passage that communicates the groove 39 and the second oil chamber Y2.

The annular protrusion 38 is a portion formed in a substantially cylindrical shape. The annular protrusion 38 is provided on an outer portion of the piston 31. The annular protrusion 38 protrudes toward the first side in the axial direction more than the first outer round portion 37. In other words, the annular protrusion 38 protrudes in the axial direction toward the first side further than the first outer round portion 37.
The piston 31 of the present embodiment is formed, for example, by filling a mold having a predetermined shape with metal powder and sintering the filled metal powder.

(Compression side damping valve group 40)
As shown in Fig. 2, the compression side damping valve group 40 is composed of a plurality of annular plates made of, for example, metal. A through hole 41H through which the rod 20 passes is formed on the inside of the compression side damping valve group 40. The compression side damping valve group 40 is formed to be larger than the outer diameter of the second outer round portion 33. The compression side damping valve group 40 covers the second side of the compression side oil passage 311 and always opens the second side of the extension side oil passage 312.

(Extension side damping valve group 100)
The extension side damping valve group 100 is configured by stacking seven plates made of metal. More specifically, the extension side damping valve group 100 has a first valve 110 seated on the first outer round portion 37 of the piston 31, a second valve 120 arranged adjacent to the first valve 110, a third valve 130 arranged adjacent to the second valve 120, and a fourth valve 140 arranged adjacent to the third valve 130. In addition, the extension side damping valve group 100 has a fifth valve 150 arranged adjacent to the fourth valve 140, a sixth valve 160 arranged adjacent to the fifth valve 150, and a seventh valve 170 arranged adjacent to the sixth valve 160. The first valve 110, the second valve 120, the third valve 130, the fourth valve 140, the fifth valve 150, the sixth valve 160 and the seventh valve 170 have a through hole 105 formed on the inside through which the rod 20 passes, and are arranged around the rod 20 in order from the piston 31 towards the first side. The diameter of the through hole 105 is smaller than the diameter of the first inner round portion 36, and the inner peripheries of the seven valves are fixed between the first inner round portion 36 and the annular member 44.

The first valve 110 has a circular outer periphery 111. The outer diameter of the first valve 110 is larger than the outer diameter of the first outer round portion 37 of the piston 31 and covers the first side of the groove 39 formed in the piston 31.
The first valve 110 has a plurality of slits 112 cut in a straight line from the outer circumferential end inward, formed in the circumferential direction. The inner positions of the slits 112 are located inside the first outer round portion 37 and outside the first inner round portion 36. Therefore, even when the first valve 110 is seated on the first outer round portion 37, the groove 39 and the first oil chamber Y1 communicate with each other via the slits 112. Therefore, the slits 112 function as an orifice that allows oil to flow from the second oil chamber Y2 to the first oil chamber Y1.

The second valve 120 has a circular outer periphery 121, and the outer diameter of the second valve 120 is the same as the outer diameter of the first valve 110. The second valve 120 reinforces the first valve 110 and serves to increase the rigidity of the first valve 110. By providing the second valve 120, it is possible to suppress excessive displacement and deformation of the first valve 110 without increasing the rigidity of the first valve 110 itself. Note that if sufficient rigidity can be ensured by the first valve 110 alone, it is not necessarily necessary to provide the second valve 120. Hereinafter, the first valve 110 and the second valve 120 may be referred to as the first laminate 101.

FIG. 6 is an example of a view of the third valve 130 as viewed in the axial direction.
The third bulb 130 has an outer periphery 131 in a cross shape. In other words, the third bulb 130 has a shape when viewed in the axial direction that is a square with four corners cut out in a fan shape. That is, the outer periphery 131 of the third bulb 130 has a pair of first sides 132 extending in the left-right direction of FIG. 6 and a pair of second sides 133 extending in the up-down direction of FIG. 6, in other words, in a direction perpendicular to the first sides 132. The distance between the pair of first sides 132 and the distance between the pair of second sides 133 are the same, and are the same as the outer diameter of the second bulb 120. The third bulb 130 also has four arcs 134 that connect the end of the first side 132 and the end of the second side 133. The size of all four arcs 134 is the same, and the four arcs 134 together form a virtual circle. The four arcs 134 are also arranged at equal intervals (every 90 degrees) around the through hole 105.
In the third bulb 130 configured as described above, the portion surrounded by the outer circumferential portion 131 and the through hole 105 comes into contact with the first stack 101. The portion of the third bulb 130 outside the arc 134 becomes a recess 135 that does not come into contact with the first stack 101.
In addition, the part of the outer circumferential portion 131 that is farthest from the center of the through hole 105 (for example, the connection point between the first side 132 and the arc 134, or the connection point between the second side 133 and the arc 134) may be the same as the radius of the second bulb 120.

FIG. 7 is an example of a view of the fourth valve 140 as viewed in the axial direction.
The fourth valve 140 has a disk 141 with a circular outer periphery 141a and a cylindrical ring 142 provided on the outer periphery 141a of the first side surface of the disk 141. The outer diameter of the disk 141 is the same as the outer diameter of the first valve 110. The outer diameter of the ring 142 is the same as the outer diameter of the disk 141, and the inner diameter of the ring 142 is larger than the inner diameter of the disk 141 (in other words, the diameter of the through hole 105). For example, the inner diameter of the ring 142 can be 9/10 of the outer diameter of the ring 142. In addition, the thickness of the ring 142 (in other words, the size in the axial direction) can be 1 time or more and 1.5 times or less than the thickness of the disk 141.

The ring 142 is joined to the disk 141 by welding. For example, welding may be performed in spots at a plurality of locations in the circumferential direction of the ring 142. The joining is not limited to welding, and the disk 141 and the ring 142 may be joined by adhesion or fusion.
As described above, the fourth valve 140 is formed by joining the disk 141, which is an example of a circular thin plate, to the ring 142, which has a thickness equal to or greater than the thickness of the disk 141. Therefore, the size of the fourth valve 140 in the axial direction (in other words, the center line direction) at the outer periphery is larger than the size of the fourth valve 140 in the axial direction at the inner periphery.

Hereinafter, the third valve 130 and the fourth valve 140 may be referred to as the second stack 102. As described above, the second stack 102 has a third valve 130 (an example of a non-circular member) that is disposed adjacent to the first stack 101 and has a non-circular outer periphery 131, and a fourth valve 140 (an example of a circular member) that is disposed on the opposite side of the piston 31 from the third valve 130, has a circular outer periphery 141a, and is provided with a ring 142.

The fifth bulb 150 has a circular outer periphery 151 , and the outer diameter of the fifth bulb 150 is the same as the outer diameter of the first bulb 110 .
The sixth valve 160 has a circular outer periphery 161, and the outer diameter of the sixth valve 160 is the same as the outer diameter of the first valve 110. The sixth valve 160 reinforces the fifth valve 150 and serves to increase the rigidity of the fifth valve 150. By providing the sixth valve 160, it is possible to suppress excessive displacement and deformation of the fifth valve 150 without increasing the rigidity of the fifth valve 150 itself. Note that if sufficient rigidity can be ensured by the fifth valve 150 alone, it is not necessarily necessary to provide the sixth valve 160.

The seventh bulb 170 has a circular outer periphery 171 and an outer diameter smaller than that of the sixth bulb 160. For example, the outer diameter of the seventh bulb 170 is 2/3 of that of the sixth bulb 160. The seventh bulb 170 reinforces the inner periphery of the fifth bulb 150 and the sixth bulb 160, and serves to increase the rigidity of the fifth bulb 150 and the sixth bulb 160. By providing the seventh bulb 170, it is possible to suppress excessive displacement and deformation of the fifth bulb 150 and the sixth bulb 160 without increasing the rigidity of the fifth bulb 150 and the sixth bulb 160 themselves. Note that if sufficient rigidity can be ensured with the fifth bulb 150 and the sixth valve 160, it is not necessarily necessary to provide the seventh bulb 170.

In the following, the fifth valve 150, the sixth valve 160, and the seventh valve 170 may be referred to as the third stack 103.

The outer diameter of the annular member 44 is smaller than that of the seventh valve 170. The outer diameter of the valve stopper 45 is smaller than that of the seventh valve 170 and larger than that of the annular member 44. The thickness of the valve stopper 45 is set to be approximately the same as that of the third stack 103, for example. The first stack 101, the second stack 102, and the third stack 103 are fixed between the annular member 44 and the valve stopper 45 and the piston 31 by the nut 46. As a result, the inner periphery of the first stack 101, the second stack 102, and the third stack 103 becomes the fixed end side and the outer periphery becomes the free end side, and the first stack 101, the second stack 102, and the third stack 103 bend from the outer periphery of the annular member 44. The valve stopper 45 suppresses excessive deformation of the first stack 101, the second stack 102, and the third stack 103.

As described above, the extension side damping valve group 100 has the first stack 101 seated on the first outer round portion 37 as an example of the end face of the piston 31, the second stack 102 arranged on the first side opposite the piston 31 with respect to the first stack 101, and the third stack 103 arranged on the first side with respect to the second stack 102. The first stack 101, the second stack 102, and the third stack 103 are attached to the rod 20 by the nut 46 via the annular member 44 and the valve stopper 45. As a result, the inner periphery of the third stack 103 is pressed by the annular member 44, so that the inner periphery of the first stack 101 and the inner periphery of the second stack 102 come into contact with each other, and the third stack 103 is attached in a state in which the inner periphery of the second stack 102 and the inner periphery of the third stack 103 come into contact with each other.

The fourth valve 140 of the second stack 102 has a structure in which the ring 142 is joined to the outer periphery 141a of the disk 141, so that the second side surface of the third stack 103 is pressed by the ring 142, and the outer periphery of the third stack 103 is bent so that it is located closer to the first side than the inner periphery. In other words, the second stack 102 has the ring 142 (an example of a convex portion) that bends the third stack 103 so that the outer periphery is located on the opposite side to the piston 31 (in other words, the first side) than the inner periphery, even when there is no pressure difference between the first oil chamber Y1 and the second oil chamber Y2, which are the two oil chambers. As a result, a force that causes the third stack 103 to return to its original shape acts on the ring 142, and an initial load in the direction toward the piston 31 acts on the first stack 101 and the second stack 102.

The action during the extension stroke will be described below.
FIG. 8 is a diagram showing an example of the damping force characteristic of the shock absorber 2. As shown in FIG.
In the extension side damping valve group 100 configured as above, first, when the piston speed is low, oil moves from the second oil chamber Y2 to the first oil chamber Y1 through the slit 112 formed in the first valve 110. In addition, a ring 142 is joined to the disk 141 of the fourth valve 140, and an initial load in the direction toward the piston 31 side is applied to the first stack 101 and the second stack 102. As a result, in the region where the piston speed is low, the rate of increase in the damping force relative to the increase in the piston speed becomes larger than when the slit 112 is not formed or when the initial load is not applied. In other words, the slope of the damping force curve shown in FIG. 8 becomes larger.

When the oil pressure in the second oil chamber Y2 increases as the piston speed approaches the medium speed region, the portion of the first stack 101 located outside the arc 134 of the third valve 130 (in other words, the portion facing the recess 135) bends from the arc 134 as the starting point, and the first stack 101 begins to open. As a result, the damping force curve becomes smooth without generating an inflection point in the area surrounded by the dotted circle in Figure 8. In other words, compared to when the outer periphery of the valve adjacent to the first stack 101 is circular, for example, the first stack 101 begins to open partially, and the oil pressure in the second oil chamber Y2 that begins to open becomes lower, so the slope of the damping force curve becomes gentler at an early stage when the piston speed approaches the medium speed region.

When the hydraulic pressure in the second oil chamber Y2 increases as the piston speed reaches a high speed range, the entire extension side damping valve group 100 begins to open. At this time, an annular groove 39 that communicates with the second oil chamber Y2 via the extension side oil passage 312 is formed in the portion of the piston 31 adjacent to the first valve 110, so the rate at which the damping force increases with increasing piston speed is smaller than in the case where the groove is not annular. In other words, the slope of the damping force curve shown in FIG. 8 becomes smaller.

In other words, according to the extension side damping valve group 100, as shown in the damping force curve in FIG. 8, in the low piston speed region, the slope is large and the damping force increases linearly, so handling stability is improved. On the other hand, in the high piston speed region, the slope is small, so the ride comfort of the vehicle is improved. In addition, in the medium piston speed region, the motion is smooth without inflection points, so abrupt changes in the movement of the rod 20 can be suppressed, and abnormal noises can be suppressed inside the vehicle.

In addition, with the extension side damping valve group 100, the initial load can be adjusted by adjusting the amount of initial deflection of the third stack 103 through the difference between the thickness of the disc 141 and the thickness of the ring 142 of the fourth valve 140, making it possible to adjust the hydraulic pressure when the entire first stack 101 begins to open.

In addition, according to the extension side damping valve group 100, the hydraulic pressure when the first stack 101 begins to partially open varies depending on the shape of the outer periphery 131 of the third valve 130, so it is possible to adjust the damping force characteristics by changing the shape of the third valve 130. In addition, it becomes easier to grasp the correlation between the shape of the outer periphery 131 of the third valve 130 and the damping force.

In addition, a circular disk having an outer diameter smaller than that of the first valve 110 is provided between the first stack 101 and the piston 31, and the initial load acting on the first stack 101 can be adjusted by changing the number and/or thickness of the disks.

Modifications to the shape of the outer circumferential portion 131 of the third bulb 130 will be described below.
(First modified example of the shape of the outer periphery 131 of the third bulb 130)
FIG. 9 is a diagram showing an example of a third valve 180 according to the first modified example.
The third bulb 180 according to the first modification has an outer circumferential portion 181 having a different shape from the outer circumferential portion 131 of the third bulb 130, and the shape when viewed in the axial direction is a rectangle with four corners cut out in a fan shape. That is, the outer circumferential portion 181 has a pair of first sides 182 extending in the left-right direction in FIG. 9 and a pair of second sides 183 extending in the up-down direction in FIG. 9, in other words, in a direction perpendicular to the first sides 182. The distance between the pair of second sides 183 is larger than the distance between the pair of first sides 182, the distance between the pair of second sides 183 is the same as the outer diameter of the second bulb 120, and the distance between the pair of first sides 182 is smaller than the outer diameter of the second bulb 120. The third bulb 180 has four arcs 184 connecting the end of the first side 182 and the end of the second side 183. The four arcs 184 are all the same size.

In the third bulb 180, the portion surrounded by the outer periphery 181 and the through hole 105 comes into contact with the first laminate 101. The portion of the third bulb 180 outside the arc 184 becomes a recess 185 that does not come into contact with the first laminate 101.

The third valve 180 configured as described above differs from the third valve 130 in that the four arcs 184 from which the first laminate 101 starts to bend are not uniform, and there are some parts where the first laminate 101 is more likely to bend than when the first laminate 101 starts to bend from the arc 134. As a result, the bending characteristics in the damping force curve shown in FIG. 8 are further alleviated.

(Second modified example of the shape of the outer periphery 131 of the third bulb 130)
FIG. 10 is a diagram showing an example of a third valve 190 according to the second modified example.
The third bulb 190 according to the second modification has an outer circumferential portion 191 having a shape in which the left and right ends in Fig. 10 are cut out from a circle 192 having the same outer diameter as the outer diameter of the second bulb 120. In other words, the outer circumferential portion 191 has a pair of sides 193 extending in the up and down direction in Fig. 10.
In third bulb 190, a portion surrounded by outer circumferential portion 191 and through hole 105 comes into contact with first stack 101. Then, a portion of third bulb 190 outside a pair of sides 193 becomes recessed portion 194 that does not come into contact with first stack 101.

With the third valve 190 configured as described above, the portion of the first stack 101 located outside the edge 193 of the third valve 190 according to the second modified example (in other words, the portion facing the recess 194) bends starting from the edge 193, and the first stack 101 begins to open. As a result, the damping force curve becomes smooth without generating an inflection point in the area circled by the dotted line in FIG. 8.

(Third modified example of the shape of the outer periphery 131 of the third bulb 130)
FIG. 11 is a diagram showing an example of a third valve 195 according to the third modified example.
A third bulb 195 according to the third modification has an outer circumferential portion 196 that is an ellipse whose major axis has the same outer diameter as the outer diameter of the second bulb 120 .
In third bulb 195, a portion surrounded by outer periphery 196 and through hole 105 comes into contact with first stack 101. Then, a portion of third bulb 195 outside outer periphery 196 becomes recess 197 that does not come into contact with first stack 101.

With the third valve 195 configured as described above, the portion of the first stack 101 located outside the outer periphery 196 of the third valve 195 according to the third modified example (in other words, the portion facing the recess 197) bends starting from the outer periphery 196, and the first stack 101 begins to open. As a result, the damping force curve becomes smooth without generating an inflection point in the area circled by the dotted line in FIG. 8.

(First Modification of the Fourth Valve 140)
FIG. 12 is a diagram showing an example of a fourth valve 145 according to a first modified example when viewed in the axial direction from the first side.
The fourth valve 145 according to the first modification is different from the fourth valve 140 in that it has a circular disk 146 in which the center of a through hole 105 formed in the central part through which a rod passes is offset from the center of the circle of the outer periphery 146a, and a ring 142 joined to the outer periphery 146a of the disk 146. The distance from the center of the through hole 105 to the farthest part of the outer periphery 146a is set to be the same as the radius of the second valve 120, and the distance from the center of the through hole 105 to the nearest part of the outer periphery 146a is set to be smaller than the radius of the second valve 120.

According to the fourth valve 145 of the first modified example configured as described above, unlike the fourth valve 140, the initial load acting on the first stack 101 is not uniform in the circumferential direction, and there are portions of the first stack 101 that are more likely to bend than when the initial load is applied by the fourth valve 140. As a result, the bending characteristics in the damping force curve shown in FIG. 8 are further alleviated.
The fourth valve 145 according to the first modified example may be applied even when the third valve 180 according to the first modified example, the third valve 190 according to the second modified example, or the third valve 195 according to the third modified example is used instead of the third valve 130.

(Second Modification of the Fourth Valve 140)
FIG. 13 is a diagram showing an example of a fourth valve 147 according to the second modified example, as viewed in the axial direction from the first side.
FIG. 14 is a partial cross-sectional view showing an example of a fourth valve 147 according to the second modified example.
The fourth valve 147 according to the second modification is circular and has an outer diameter that is the same as the outer diameter of the first valve 110. The fourth valve 147 has a protrusion 148 that protrudes toward the first side formed by pressing the entire outer periphery of the fourth valve 147. In other words, the fourth valve 147 according to the second modification differs from the fourth valve 140 in that, instead of providing a ring 142 on the first side of the disk 141, the protrusion 148 is formed by pressing.

In the fourth valve 147 configured as described above, the second side surface of the third laminate 103 is pressed by the convex portion 148, and the outer periphery of the third laminate 103 is bent so that it is located closer to the first side than the inner periphery. This causes a force to act on the convex portion 148, which causes the third laminate 103 to return to its original shape, and an initial load acts on the first laminate 101 in a direction toward the piston 31. As a result, in the region where the piston speed is low, the rate at which the damping force increases in response to an increase in piston speed can be made greater than when no initial load is acting.

The fourth valve 147 according to the second modified example may be applied even when the third valve 180 according to the first modified example, the third valve 190 according to the second modified example, or the third valve 195 according to the third modified example is used instead of the third valve 130. Also, in the fourth valve 147 according to the second modified example, the center of the through hole 105 through which the rod 20 passes may be shifted from the center of the outer periphery, as in the fourth valve 145 according to the first modified example.

Second Embodiment
The extension side damping valve group 200 according to the second embodiment is different from the extension side damping valve group 100 according to the first embodiment in that the second stack 202 corresponds to the second stack 102. The points that differ from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and second embodiments, and detailed descriptions thereof will be omitted.

FIG. 15 is a diagram showing an example of a schematic configuration of the second stack 202 of the expansion side damping valve group 200 according to the second embodiment, as viewed in the axial direction from the first side.
The second laminate 202 differs from the second laminate 102 of the first embodiment in that it does not have a third valve 130 and does not protrude toward the first side along its entire circumference like the ring 142 of the fourth valve 140.

More specifically, the second stack 202 has a disk 240 having a circular outer periphery 241 and a protrusion 242 provided on the outer periphery 241 of the disk 240 and protruding towards the first side.
The disk 240 has the same shape as the disk 141 according to the first embodiment.

The convex portion 242 has a first convex portion 251 and a second convex portion 252, which are arc-shaped. The first convex portion 251 differs from the ring 142 according to the first embodiment only in its circumferential size. The circumferential size of the first convex portion 251 can be, for example, 1/6 to 1/4 of that of the ring 142. The second convex portion 252 has the same shape as the first convex portion 251, and the first convex portion 251 and the second convex portion 252 are arranged symmetrically with respect to the center of the disc 240.

The first convex portion 251 and the second convex portion 252 can be, for example, joined to the disk 240 by welding, similar to the ring 142. This is not limited to welding, and the first convex portion 251 and the second convex portion 252 and the disk 240 may be joined by adhesion or welding.

As described above, in the second laminate 202, the convex portion 242 having a thickness equal to or greater than the thickness of the disc 240 is joined to the disc 240, which is an example of a circular thin plate. Therefore, in the second laminate 202, the size in the axial direction (in other words, the center line direction) of the outer periphery to which the convex portion 242 is joined is larger than the size in the axial direction of the inner periphery.
In the second stack 202, the convex portion 242 comes into contact with the third stack 103. Then, a portion between the first convex portion 251 and the second convex portion 252 in the circumferential direction becomes a concave portion 255 that does not come into contact with the third stack 103.

In the extension side damping valve group 200 configured as described above, the second side surface of the third stack 103 is pressed by the convex portion 242 of the second stack 202, and the outer periphery of the third stack 103 is bent so that it is located closer to the first side than the inner periphery. As a result, a force acts on the convex portion 242 to return the third stack 103 to its original shape, and an initial load acts on the first stack 101 in a direction toward the piston 31.

However, in the circumferential direction of the second laminate 202, the magnitude of the initial load is different between the area where the convex portion 242 is provided and the area where the convex portion 242 is not provided (in other words, the area facing the concave portion 255), so the initial load acting on the first laminate 101 is greater in the area where the convex portion 242 is provided than in the area where the convex portion 242 is not provided.

Therefore, when the oil pressure in the second oil chamber Y2 increases as the piston speed approaches the medium speed region, the portion of the first stack 101 facing the portion of the second stack 202 where the convex portion 242 is not provided (in other words, the portion facing the concave portion 255) begins to open before the portion corresponding to the portion where the convex portion 242 is provided. As a result, the damping force curve becomes smooth without generating an inflection point in the area surrounded by the dotted circle in Figure 8. In other words, unlike the case where, for example, a convex portion protruding to the first side is provided around the entire circumference of the second stack 202, the first stack 101 begins to open partially, and the oil pressure in the second oil chamber Y2 where it begins to open becomes lower, so the slope of the damping force curve becomes gentler at an early stage when the piston speed approaches the medium speed region.

As a result, according to the extension side damping valve group 200, as in the extension side damping valve group 100 according to the first embodiment, as shown in the damping force curve in FIG. 8, in the low speed region of the piston speed, the slope is large and the damping force increases linearly, so that the handling stability is improved. On the other hand, in the high speed region of the piston speed, the slope is small, so that the ride comfort of the vehicle is improved. In addition, in the medium speed region of the piston speed, the motion is smooth without the occurrence of an inflection point, so that the movement of the rod 20 can be prevented from suddenly changing, and the generation of abnormal noise inside the vehicle can be prevented.

In addition, with the extension side damping valve group 200, the initial load can be adjusted by adjusting the amount of initial deflection of the third stack 103 through the difference between the thickness of the disk 240 of the second stack 202 and the thickness of the protrusion 242, making it possible to adjust the hydraulic pressure when the entire first stack 101 begins to open.

Moreover, according to the extension side damping valve group 200, the oil pressure when the first stack 101 starts to partially open varies depending on the shape of the convex portion 242 of the second stack 202, so it is possible to adjust the damping force characteristics by changing the shape of the convex portion 242. Also, it becomes easy to grasp the correlation between the shape of the convex portion 242 and the damping force.
Modifications of the protrusion 242 will be described below.

(First Modification of the Protrusion 242)
FIG. 16 is a diagram showing an example of a convex portion 262 according to the first modified example.
The convex portion 262 according to the first modification is different from the convex portion 242 in that it is disposed asymmetrically with respect to the center of the disk 240 .

The convex portion 262 has a first convex portion 271 and a second convex portion 272, which are arc-shaped. The circumferential size of the first convex portion 271 is larger than the circumferential size of the second convex portion 272. The circumferential size of the first convex portion 271 is larger than the circumferential size of the first convex portion 251, and can be, for example, 1/4 to 1/3 of the ring 142. The circumferential size of the second convex portion 272 is smaller than the circumferential size of the second convex portion 252, and can be, for example, 1/10 to 1/12 of the ring 142. The circumferential center of the first convex portion 271 and the circumferential center of the second convex portion 272 are arranged symmetrically with respect to the center of the disc 240.

With the above configuration, the convex portion 262 comes into contact with the third stack 103 , and the portion between the first convex portion 271 and the second convex portion 272 in the circumferential direction forms a concave portion 275 that does not come into contact with the third stack 103 .
According to the convex portion 262 of the first modified example configured as described above, unlike the convex portion 242, the portions where the first laminate 101 is more likely to flex are no longer equally spaced in the circumferential direction, so that the bending characteristics in the damping force curve shown in Figure 8 are further mitigated.

(Second Modification of the Protrusion 242)
FIG. 17 is a diagram showing an example of a convex portion 282 according to the second modified example.
The convex portion 282 according to the second modification has a first convex portion 291, a second convex portion 292, and a third convex portion 293, which are arc-shaped. The circumferential sizes of the first convex portion 291 and the second convex portion 292 are the same as the circumferential sizes of the first convex portion 271 and the second convex portion 272 according to the first modification, respectively. The circumferential size of the third convex portion 293 is smaller than the circumferential size of the second convex portion 292, and can be exemplified as 1/12 to 1/24 of the ring 142. The circumferential center of the first convex portion 291, the circumferential center of the second convex portion 292, and the circumferential center of the third convex portion 293 are arranged symmetrically with respect to the center of the disk 240.

With the above configuration, the convex portion 282 comes into contact with the third stack 103, and the portion between the first convex portion 291 and the second convex portion 292 in the circumferential direction, and the portion between the second convex portion 292 and the third convex portion 293 become recesses 295 that do not come into contact with the third stack 103.
According to the convex portion 282 of the second modified example configured as described above, unlike the convex portion 242, the portions where the first laminate 101 is more likely to flex are no longer equally spaced in the circumferential direction, so that the bending characteristics in the damping force curve shown in Figure 8 are further mitigated.

Third Embodiment
FIG. 18 is a diagram showing an example of a schematic configuration of a second stack 302 according to the third embodiment.
The second laminate 302 according to the third embodiment differs from the second laminate 202 according to the second embodiment in that it has a different disk 340 corresponding to the disk 240 and does not have a protrusion 242 joined to the disk 240. The differences from the second embodiment will be described below. The same reference numerals are used for the same parts in the second and third embodiments, and detailed descriptions thereof will be omitted.

The disk 340 according to the third embodiment has a circular shape with an outer diameter that is the same as the outer diameter of the first valve 110. The disk 340 has a protrusion 341 that protrudes toward the first side formed on the outer periphery by pressing.

The convex portion 341 has an arc-shaped first convex portion 351 and a second convex portion 352. The circumferential sizes and positions of the first convex portion 351 and the second convex portion 352 are the same as the sizes and positions of the first convex portion 251 and the second convex portion 252 according to the second embodiment, respectively.
In other words, the second laminate 302 of the third embodiment differs in that, while the convex portion 242 of the second laminate 202 of the second embodiment is joined to the circular plate 240, the convex portion 341 is formed on the circular plate 340 by press processing.

The second laminate 302 according to the third embodiment configured as described above acts in the same manner as the second laminate 202 according to the second embodiment, and therefore can achieve the same effects as those achieved by the second laminate 202 described above.

The convex portion 341 may have two convex portions that are the same in size and position in the circumferential direction as the first convex portion 271 and the second convex portion 272 of the convex portion 262 according to the first modified example described above. This makes it possible to make the portions of the first laminate 101 that are prone to bending not equally spaced in the circumferential direction, thereby further mitigating the bending characteristics in the damping force curve shown in FIG. 8.

The convex portion 341 may have three convex portions that are the same in size and position in the circumferential direction as the first convex portion 291, the second convex portion 292, and the third convex portion 293 of the convex portion 282 according to the second modified example described above. This makes it possible to make the portions of the first laminate 101 that are prone to bending not equally spaced in the circumferential direction, thereby further mitigating the bending characteristics in the damping force curve shown in FIG. 8.

Fourth Embodiment
The extension side damping valve group 400 according to the fourth embodiment is different from the extension side damping valve group 100 according to the first embodiment in that the second stack 402 corresponds to the second stack 102. The points that differ from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and fourth embodiments, and detailed descriptions thereof will be omitted.

FIG. 19 is a diagram showing an example of a schematic configuration of a second stack 402 according to the fourth embodiment, as viewed in the axial direction from the second side.
The second stack 402 differs from the second stack 102 of the first embodiment in that it does not have a third valve 130 and has a protrusion 443 that protrudes from the disc 141 of the fourth valve 140 to the second side.

More specifically, the second laminate 402 has a disk 141, a ring 142 (see FIG. 7), and a protrusion 443 that is joined to the surface of the disk 141 on the second side and protrudes toward the second side.
The protrusion 443 may, for example, have the same shape and size as the convex portion 242 of the second stack 202 according to the second embodiment, although the protrusion 443 protrudes in a different direction. That is, the protrusion 443 has a first protrusion 451 and a second protrusion 452 that correspond to the first protrusion 251 and the second protrusion 252, which are arranged symmetrically with respect to the center of the disk 141.

The first protrusion 451 and the second protrusion 452 may be joined to the disk 141 by welding, similar to the ring 142. The joining is not limited to welding, and the first protrusion 451 and the second protrusion 452 may be joined to the disk 141 by adhesion or fusion.
In the second stack 402, the projection 443 comes into contact with the first stack 101. A portion between the first projection 451 and the second projection 452 in the circumferential direction becomes a recess 455 that does not come into contact with the first stack 101.

The extension side damping valve group 400 configured as above acts as follows. That is, when the oil pressure in the second oil chamber Y2 increases as the piston speed approaches the medium speed region, the portion of the first stack 101 that is not in contact with the first protrusion 451 and the second protrusion 452 of the second stack 402 (in other words, the portion facing the recess 455) bends before the portion in contact with the first protrusion 451 and the second protrusion 452, and the first stack 101 begins to open. As a result, the damping force curve becomes smooth without generating an inflection point in the area surrounded by the dotted circle in FIG. 8. That is, for example, compared to the case where all the circular valves adjacent to the first stack 101 are in contact with the first stack 101, the first stack 101 begins to open partially, and the oil pressure in the second oil chamber Y2 that begins to open becomes lower, so the slope of the damping force curve becomes gentler at an early stage when the piston speed approaches the medium speed region.

As a result, according to the extension side damping valve group 400, as in the extension side damping valve group 100 according to the first embodiment, as shown in the damping force curve in FIG. 8, in the low speed region of the piston speed, the slope is large and the damping force increases linearly, so that the handling stability is improved. On the other hand, in the high speed region of the piston speed, the slope is small, so that the ride comfort of the vehicle is improved. In addition, in the medium speed region of the piston speed, the motion is smooth without the occurrence of an inflection point, so that the movement of the rod 20 can be prevented from suddenly changing, and the generation of abnormal noise inside the vehicle can be prevented.

The protrusion 443 may have two protrusions that are the same in size and position in the circumferential direction as the first protrusion 271 and the second protrusion 272 of the protrusion 262 according to the first modified example described above. This makes it possible to make the portions of the first laminate 101 that are prone to bending not equally spaced in the circumferential direction, thereby further mitigating the bending characteristics in the damping force curve shown in FIG. 8.

The protrusion 443 may have three protrusions that are the same in size and position in the circumferential direction as the first protrusion 291, the second protrusion 292, and the third protrusion 293 of the protrusion 282 according to the second modified example described above. This makes it possible to make the portions of the first laminate 101 that are prone to bending not equidistant in the circumferential direction, thereby further mitigating the bending characteristics in the damping force curve shown in FIG. 8.

Fifth Embodiment
The extension side damping valve group 500 according to the fifth embodiment is different from the extension side damping valve group 100 according to the first embodiment in that the second stack 502 corresponds to the second stack 102. The points that differ from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and fifth embodiments, and detailed descriptions thereof will be omitted.

FIG. 20 is a diagram showing an example of a schematic configuration of a second stack 502 according to the fifth embodiment, as viewed in the axial direction from the first side.
The second stack 502 differs from the second stack 102 of the first embodiment in that it does not have the disk 141 of the fourth valve 140, and a ring 142 is joined to the first side surface of the third valve 130.
More specifically, the second laminate 502 has a third bulb 130 and a ring 142. The ring 142 can be, for example, spot-welded at a portion between a pair of first sides 132 (see FIG. 6 ) and a portion between a pair of second sides 133 (see FIG. 6 ) on the outer circumferential portion 131 of the third bulb 130.

Even in the extension side damping valve group 500 configured as above, when the oil pressure in the second oil chamber Y2 increases as the piston speed approaches the medium speed region, the portion of the first stack 101 that corresponds to the outside of the arc 134 of the third valve 130 bends from the arc 134 as the starting point, and the first stack 101 begins to open. As a result, the damping force curve becomes smooth without generating an inflection point in the area surrounded by the dotted circle in Figure 8. In other words, for example, compared to when the outer periphery of the valve adjacent to the first stack 101 is circular, the first stack 101 begins to open partially, and the oil pressure in the second oil chamber Y2 that begins to open becomes lower, so the slope of the damping force curve becomes gentler at an early stage when the piston speed approaches the medium speed region.

As a result, according to the extension side damping valve group 500, as in the extension side damping valve group 100 according to the first embodiment, as shown in the damping force curve in FIG. 8, in the low speed region of the piston speed, the slope is large and the damping force increases linearly, so that the handling stability is improved. On the other hand, in the high speed region of the piston speed, the slope is small, so that the ride comfort of the vehicle is improved. In addition, in the medium speed region of the piston speed, the motion is smooth without the occurrence of an inflection point, so that the movement of the rod 20 can be prevented from suddenly changing, and the generation of abnormal noise inside the vehicle can be prevented.

In addition, since the second laminate 502 does not have the disk 141 of the second laminate 102 according to the first embodiment, the number of parts can be reduced, and the rigidity can be reduced, thereby reducing the damping force.

The second laminate 502 may be formed by joining a ring 142 to the third valve 180 of the first modified example, the third valve 190 of the second modified example, or the third valve 195 of the third modified example, instead of the third valve 130.

Sixth Embodiment
The extension side damping valve group 600 according to the sixth embodiment is different from the extension side damping valve group 100 according to the first embodiment in that a second stack 602 corresponding to the second stack 102 is provided. The following describes the differences from the first embodiment. The same reference numerals are used for the same components in the first and sixth embodiments, and detailed descriptions thereof will be omitted.

FIG. 21 is a diagram showing an example of a schematic configuration of the second stack 602 according to the sixth embodiment when viewed in the axial direction from the first side, and a diagram showing an example of a schematic configuration of the third valve 630 when viewed in the axial direction.
The second stack 602 includes a third valve 630 corresponding to the third valve 130, and a ring 142 of the fourth valve 140. Unlike the second stack 102 according to the first embodiment, the second stack 602 does not include the disk 141 of the fourth valve 140. In the second stack 602, the ring 142 is fitted into the third valve 630.

The third valve 630 has radial portions 636 that protrude radially from the center of each of the four arcs 134, as compared to the third valve 130 according to the first embodiment. The radial portions 636 can be exemplified as a rectangle whose long side is in the radial direction and whose short side is perpendicular to the radial direction.

The third valve 630 configured as described above is bent so that the tip ends 637 of the four radial portions 636 are positioned on the first side of the ring 142, with the pair of first sides 132 and the pair of second sides 133 positioned on the second side of the ring 142. The ring 142 is then held by the force of the four radial portions 636 attempting to return to their original shape.

The distance from the center of the through hole 105 to the tip 637 of the radial portion 636 is set so that when the ring 142 is fitted into the third valve 630, the tip 637 is outside the inner surface of the ring 142 and inside the outer surface of the ring 142.

Even in the extension side damping valve group 600 configured as above, when the oil pressure in the second oil chamber Y2 increases as the piston speed approaches the medium speed region, the portion of the first stack 101 that corresponds to the outside of the arc 134 of the third valve 630 bends from the arc 134 as the starting point, and the first stack 101 begins to open. As a result, the damping force curve becomes smooth without generating an inflection point in the area surrounded by the dotted circle in Figure 8. In other words, compared to when the outer periphery of the valve adjacent to the first stack 101 is circular, for example, the first stack 101 begins to open partially, and the oil pressure in the second oil chamber Y2 that begins to open becomes lower, so the slope of the damping force curve becomes gentler at an early stage when the piston speed approaches the medium speed region.

As a result, according to the extension side damping valve group 600, as in the extension side damping valve group 100 according to the first embodiment, as shown in the damping force curve in FIG. 8, in the low speed region of the piston speed, the slope is large and the damping force increases linearly, so that the handling stability is improved. On the other hand, in the high speed region of the piston speed, the slope is small, so that the ride comfort of the vehicle is improved. In addition, in the medium speed region of the piston speed, the motion is smooth without the occurrence of an inflection point, so that the movement of the rod 20 can be prevented from suddenly changing, and the generation of abnormal noise inside the vehicle can be prevented.

In addition, the second laminate 602 does not have the disk 141 of the second laminate 102 according to the first embodiment, so the number of parts can be reduced, and the rigidity can be reduced, resulting in a smaller damping force. In addition, unlike the ring 142 of the second laminate 502 according to the fifth embodiment, which is joined to the third valve 130, the ring 142 of the second laminate 602 is not joined to the third valve 630, so the second laminate 602 can be easily manufactured.

The end of the first side 132 of the third bulb 630 and the end of the second side 133 may not be connected by the arc 134, but by a curvature having a greater curvature than that of the arc 134. This allows the base end of the bending radial portion 636 to be brought closer to the through hole 105, making it easier for the radial portion 636 to bend.

(Modifications of the piston 31)
The shape of the piston 31 to which the extension side damping valve group 100 according to the first embodiment to the extension side damping valve group 600 according to the sixth embodiment are applied is not particularly limited.
For example, the second inner round portion 32 and the second outer round portion 33 of the piston 31 with which the compression side damping valve group 40 contact may not form a circular seating surface, but may be non-circular and form an independent seating surface for each compression side oil passage 311.

Moreover, the piston 31 may be composed of two pistons divided in the axial direction, instead of being glass-shaped with an annular protrusion 38 on the outer periphery. It is preferable that a compression side oil passage is formed in one of the two pistons, and an extension side oil passage is formed in the other piston. This allows the compression side oil passage and the extension side oil passage to be the same size, and also makes it possible to form the same size seating surface. Furthermore, the compression side damping valve group 40 may be structured in the same manner as the extension side damping valve group 100 according to the first embodiment to the extension side damping valve group 600 according to the sixth embodiment. This allows the compression side to have the damping force characteristics shown in FIG. 8, similar to the above-mentioned extension side.
In addition, a circular disk having an outer diameter smaller than that of the main valve is provided between the piston in which the compression side oil passage is formed and the main valve seated on this piston, and by changing the number and/or thickness of these disks, it is possible to adjust the initial load acting on the main valve.

1...Suspension device, 2...Shock absorber, 3...Coil spring, 11...Cylinder, 20...Rod, 30...Piston portion, 31...Piston, 37...First outer round portion (an example of a seating surface), 39...Groove, 100, 200, 400, 500, 600...Extension side damping valve group, 101...First stack, 102, 202, 302, 402, 502, 602...Second stack, 103...Third stack, 110...First valve (an example of a valve), 112...Slit, 120...Second Valve, 130, 630...Third valve (an example of a non-circular member), 135, 185, 194, 197, 255, 275, 295, 455...Recess, 140...Fourth valve (an example of a circular member), 141...Disk (an example of a thin plate), 142...Ring (an example of a convex portion), 240...Disk (an example of a circular member), 242, 262, 282...Convex portion (an example of an arc-shaped member), 312...Extension side oil passage, 443...Protrusion (an example of an arc-shaped member), Y1...First oil chamber, Y2...Second oil chamber

Claims (16)

a piston that divides an oil chamber in a cylinder containing hydraulic oil into a first oil chamber and a second oil chamber;
a plurality of laminates arranged such that an inner circumferential side is supported by the piston and an outer circumferential side is a free end, the laminates being elastically deformable when the pressure in the second oil chamber becomes higher than the pressure in the first oil chamber, and the laminates being laminated in a center line direction of the cylinder;
Equipped with
The piston has a groove recessed in an annular shape from a seating surface on the side of the first oil chamber, and a communication passage communicating the groove with the second oil chamber,
the plurality of stacks include a first stack seated on the seat surface of the piston, a second stack disposed on an opposite side of the piston with respect to the first stack, and a third stack disposed on the opposite side with respect to the second stack,
the second stack has a recess formed on an outer periphery thereof for partially deflecting the first stack when the pressure in the second oil chamber becomes higher than the pressure in the first oil chamber, and a protrusion for deflecting the third stack so that the outer periphery is positioned on the opposite side from the inner periphery thereof when no pressure difference is generated between the first oil chamber and the second oil chamber.
Buffer device. The convex portion of the second laminate protrudes to the opposite side.
The shock absorber according to claim 1 . the first stack has a valve that is seated on the seat surface of the piston and has a slit formed on an outer periphery thereof, the slit communicating between the groove and the first oil chamber,
The shock absorber according to claim 1 . the second stack includes a non-circular member disposed adjacent to the first stack and having a non-circular outer periphery, and a circular member disposed on the opposite side to the non-circular member, having a circular outer periphery and having the protrusion.
The shock absorber according to claim 1 . The circular member has an outer circumferential portion having a larger size in the center line direction than an inner circumferential portion.
The shock absorber according to claim 4. The circular member is formed by joining a ring having a thickness equal to or greater than the thickness of a circular thin plate to the circular thin plate.
The shock absorber according to claim 5. The circular member has the protrusions formed by pressing an outer periphery of a circular thin plate.
The shock absorber according to claim 5. The non-circular member has an outer periphery having a rectangular shape with four fan-shaped corners cut out when viewed in the center line direction.
The shock absorber according to claim 4. The non-circular member has an outer periphery that is cut out so that both ends of the circle are parallel to each other when viewed in the center line direction.
The shock absorber according to claim 4. The non-circular member has an outer periphery having an elliptical shape when viewed in the center line direction.
The shock absorber according to claim 4. The center of the outer periphery of the circular member is offset from the center of the through hole formed inside the circular member.
The shock absorber according to claim 4. The second stack includes a non-circular member disposed adjacent to the first stack and having a non-circular outer periphery, and a ring joined to the outer periphery of the non-circular member on the opposite side.
The shock absorber according to claim 1 . The second laminate includes a circular member having a circular outer periphery and a plurality of arc-shaped members joined to the outer periphery of the circular member.
The shock absorber according to claim 1 . The second laminate is a member in which a plurality of arc-shaped convex portions are formed by applying press working to an outer periphery of a circular thin plate.
The shock absorber according to claim 1 . The second laminate includes a circular member having a circular outer periphery, a plurality of arc-shaped members joined to a surface of the circular member on the piston side, and a ring joined to a surface of the circular member on the opposite side.
The shock absorber according to claim 1 . A shock absorber according to any one of claims 1 to 15;
A coil spring disposed around the shock absorber;
A suspension device comprising: