JP7154166B2 - buffer - Google Patents

Description

The present invention relates to shock absorbers.

Some shock absorbers have two valves that open in the same stroke (see Patent Documents 1 and 2, for example).

JP 2016-173140 A JP 2015-132313 A

By having two valves that open in the same stroke, one valve can be opened in a region where the piston speed is lower than the other valve, and both valves can be opened in a region where the piston speed is higher than this. It becomes possible. In such a structure, it is required to improve the durability of the low-speed side valve in particular.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shock absorber capable of improving the durability of the valve.

In order to achieve the above object, the present invention provides a piston slidably provided in a cylinder and partitioning the inside of the cylinder into two chambers, and a piston connected to the piston and extending to the outside of the cylinder. A rod, a first passage and a second passage through which the working fluid flows from the chamber on the upstream side to the chamber on the downstream side in the cylinder due to the movement of the piston, and the first passage formed in the piston. a first damping force generating mechanism that generates a damping force; and a second passage that is provided in an annular valve seat member arranged in one of the two chambers and that is parallel to the first passage. a second damping force generating mechanism for generating a damping force provided in the a first sub-valve provided on the first sub-valve and a second sub-valve provided on the other side; and a bottomed cylindrical cap member provided between the piston and the valve seat member in the second passage, wherein the valve seat The member is provided in the cap member, the first sub-valve is provided in the one chamber, the second sub-valve is provided in the cap chamber between the bottom of the cap member and the valve seat member, and the second passage has an orifice on the upstream side or downstream side of the flow of the working fluid when the first sub-valve is opened, and the first damping force generating mechanism is closed in a region where the piston speed is low. When the second damping force generating mechanism is open and the piston speed is higher than the low speed, both the first damping force generating mechanism and the second damping force generating mechanism are open, and the valve seat member passage portion is: The upstream end and downstream end of the flow of working fluid are shifted in the radial direction of the valve seat member.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve the durability of a valve|bulb.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the shock absorber of 1st Embodiment which concerns on this invention. It is a fragmentary sectional view showing the principal part of the shock absorber of a 1st embodiment concerning the present invention. FIG. 4 is a partial cross-sectional view showing the vicinity of the cap member and the valve seat member of the shock absorber of the first embodiment according to the present invention; 1 shows a valve seat member of a shock absorber according to a first embodiment of the present invention, where (a) is a perspective view seen from one side in the axial direction, and (b) is a perspective view seen from the other side in the axial direction. be. It is a sectional view showing the important section of the shock absorber of a 2nd embodiment concerning the present invention. It is a sectional view showing the important section of the shock absorber of a 3rd embodiment concerning the present invention. FIG. 11 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of a shock absorber according to a third embodiment of the present invention;

[First embodiment]
A first embodiment according to the present invention will be described with reference to FIGS. 1 to 4. FIG. In the following, for convenience of explanation, the upper side in FIGS. 1 to 3 and 5 to 7 is referred to as "upper", and the lower side in FIGS. 1 to 3 and 5 to 7 is referred to as "lower". .

The shock absorber 1 of the first embodiment, as shown in FIG. 1, is a so-called monotube hydraulic shock absorber, and includes a cylinder 2 in which hydraulic fluid (not shown) as working fluid is enclosed. The cylinder 2 has a cylindrical shape with a bottom. The cylinder 2 is an integrally molded product comprising a cylindrical body portion 11 and a bottom portion 12 that is formed on the lower side of the body portion 11 and closes the lower portion of the body portion 11 . A mounting eye 13 is fixed to the bottom portion 12 at an outer position opposite the body portion 11 .

The damper 1 has a partition body 15 and a piston 18 which are both slidably provided inside the cylinder 2 . A partition 15 is provided between the piston 18 and the bottom 12 of the cylinder 2 . The piston 18 defines two chambers, an upper chamber 19 and a lower chamber 20, within the cylinder 2, and the partition 15 defines a lower chamber 20 and a gas chamber 16 within the cylinder 2. . In other words, the piston 18 is slidably provided within the cylinder 2 and partitions the interior of the cylinder 2 into an upper chamber 19 on one side and a lower chamber 20 on the other side. An upper chamber 19 and a lower chamber 20 in the cylinder 2 are filled with oil as working fluid, and a gas chamber 16 in the cylinder 2 is filled with gas.

The shock absorber 1 includes a piston rod 21 having one axial end portion disposed inside the cylinder 2 and connected and fixed to the piston 18 and having the other end portion extending outside the cylinder 2 . The piston rod 21 passes through the upper chamber 19 and does not pass through the lower chamber 20 . Therefore, the upper chamber 19 is a rod-side chamber through which the piston rod 21 passes, and the lower chamber 20 is a bottom-side chamber on the bottom 12 side of the cylinder 2 .

Piston 18 and piston rod 21 move together. In the extension stroke of the shock absorber 1 in which the piston rod 21 increases the amount of protrusion from the cylinder 2, the piston 18 moves toward the upper chamber 19 side, and the piston rod 21 reduces the amount of protrusion from the cylinder 2 of the shock absorber 1. During the compression stroke, the piston 18 moves toward the lower chamber 20 side.

A rod guide 22 is fitted and fixed to the upper end opening side of the cylinder 2 , and a seal member 23 is fitted to the upper side of the rod guide 22 , which is the outer side of the cylinder 2 . The upper end portion of the cylinder 2 is crimped radially inward to form a locking portion 26 , and the locking portion 26 and the rod guide 22 sandwich the sealing member 23 . A friction member 24 is provided between the rod guide 22 and the seal member 23 .

The rod guide 22, the friction member 24 and the seal member 23 all have an annular shape, and the piston rod 21 is slidably inserted through each of the rod guide 22, the friction member 24 and the seal member 23. are extended from the inside of the cylinder 2 to the outside. The piston rod 21 has one axial end portion fixed to the piston 18 inside the cylinder 2 and the other axial end portion protruding outside the cylinder 2 via a rod guide 22, a friction member 24 and a seal member 23. there is

The rod guide 22 supports the piston rod 21 axially movably while restricting its radial movement, and guides the movement of the piston rod 21 . The seal member 23 is in close contact with the cylinder 2 at its outer peripheral portion, and slidably contacts the outer peripheral portion of the piston rod 21 moving in the axial direction at its inner peripheral portion. Thereby, the seal member 23 prevents the oil in the cylinder 2 from leaking to the outside. The friction member 24 applies frictional force to the piston rod 21 .

The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28 having a smaller diameter. The main shaft portion 27 of the piston rod 21 is slidably fitted to the rod guide 22, the friction member 24 and the seal member 23, and the mounting shaft portion 28 is arranged in the cylinder 2 and connected to the piston 18 and the like. . An end portion of the main shaft portion 27 on the mounting shaft portion 28 side forms a shaft stepped portion 29 extending in the direction perpendicular to the axis. A passage notch 30 extending in the axial direction is formed in the outer peripheral portion of the mounting shaft portion 28 at an intermediate position in the axial direction, and a male thread 31 is formed at the tip position on the side opposite to the main shaft portion 27 in the axial direction. It is The passage cutout portion 30 is formed, for example, by notching the outer peripheral portion of the mounting shaft portion 28 in a plane parallel to the central axis of the mounting shaft portion 28 . The passage cutouts 30 can be formed in a so-called width across flat shape at two locations that are 180 degrees apart in the circumferential direction of the mounting shaft portion 28 .

The piston rod 21 is provided with an annular stopper member 32, a pair of support members 33, a coil spring 34, and a shock absorber 35 in a portion between the piston 18 and the rod guide 22 of the main shaft portion 27. . The stopper member 32 has the piston rod 21 inserted through its inner peripheral side, and is fixed to the main shaft portion 27 by caulking. One supporting member 33, a coil spring 34, and the other supporting member 33 are arranged in order from the stopper member 32 side. The pair of support bodies 33 and coil springs 34 are arranged between the stopper member 32 and the rod guide 22 and have the piston rod 21 inserted therein. The buffer 35 has the piston rod 21 inserted therein and is arranged between the other support 33 and the rod guide 22 . When the piston rod 21 protrudes from the cylinder 2 by a predetermined length, the stopper member 32, the pair of supports 33, the coil spring 34, and the damping body 35 come into contact with the rod guide 22 at the damping body 35, and the damping body 35 and the coil spring 34 is elastically deformed.

The shock absorber 1 is supported by the vehicle body with the portion of the piston rod 21 protruding from the cylinder 2 arranged at the upper portion thereof, and is connected to the wheel side with the mounting eye 13 on the cylinder 2 side arranged at the lower portion thereof. Conversely, the cylinder 2 side may be supported by the vehicle body, and the piston rod 21 may be connected to the wheel side.

As shown in FIG. 2, the piston 18 includes a metal piston body 36 connected to the piston rod 21 and an annular synthetic resin body that is integrally attached to the outer peripheral surface of the piston body 36 and slides inside the cylinder 2. and a sliding member 37 made of

The piston body 36 has a plurality of passage holes 38 (only one is shown because of the cross section in FIG. 2) that can communicate the upper chamber 19 and the lower chamber 20, and the upper chamber 19 and the lower chamber 20 can communicate. A plurality of passage holes 39 (only one portion is shown in FIG. 2 because of the cross section) are provided.

A plurality of passage holes 38 are formed at an equal pitch in the circumferential direction of the piston body 36 with one passage hole 39 sandwiched therebetween, and constitute half of the total number of the passage holes 38, 39. . The plurality of passage holes 38 are crank-shaped with two bending points, one axial side of the piston 18 (the upper side in FIG. 2) is open radially inward of the piston 18 from one side. The piston body 36 is formed with an annular groove 55 that communicates with the plurality of passage holes 38 on the lower chamber 20 side in the axial direction.

A first damping force generating mechanism 41 is provided on the lower chamber 20 side of the annular groove 55 to open and close passages in the annular groove 55 and in the plurality of passage holes 38 to generate a damping force. By arranging the first damping force generating mechanism 41 on the lower chamber 20 side, the passages in the plurality of passage holes 38 and the annular groove 55 move upstream in the movement of the piston 18 toward the upper chamber 19 side, that is, in the extension stroke. This is an extension-side passage through which oil flows out from the upper chamber 19 on the side toward the lower chamber 20 on the downstream side. The first damping force generating mechanism 41 provided for the passages in the plurality of passage holes 38 and the annular groove 55 extends from the passages in the plurality of passage holes 38 and the annular groove 55 to the lower chamber 20 . It is a damping force generating mechanism on the elongation side that generates damping force by suppressing the flow of oil liquid.

The passage holes 39, which constitute the remaining half of the total number of the passage holes 38, 39, are formed at equal pitches in the circumferential direction of the piston body 36 with one passage hole 38 therebetween. The plurality of passage holes 39 are crank-shaped with two bending points. (upper side in FIG. 2) is open radially inward of the piston 18 from the other side. The piston main body 36 is formed with an annular groove 56 that communicates with the plurality of passage holes 39 on the side of the upper chamber 19 in the axial direction.

A first damping force generating mechanism 42 is provided on the upper chamber 19 side of the annular groove 56 to open and close passages in the plurality of passage holes 39 and the annular groove 56 to generate a damping force. By arranging the first damping force generating mechanism 42 on the upper chamber 19 side, the passages in the plurality of passage holes 39 and in the annular groove 56 move upstream in the movement of the piston 18 toward the lower chamber 20 side, that is, in the compression stroke. This is a contraction-side passage through which oil flows from the lower chamber 20 on the side toward the upper chamber 19 on the downstream side. The first damping force generating mechanism 42 provided for the passages in the plurality of passage holes 39 and the annular groove 56 extends from the passages in the plurality of passage holes 39 and the annular groove 56 on the contraction side to the upper chamber 19 . It is a damping force generation mechanism on the compression side that generates damping force by suppressing the flow of the oil liquid.

The piston body 36 has a substantially disk shape, and an insertion hole 44 into which the mounting shaft portion 28 of the piston rod 21 is inserted is formed through the piston body 36 in the radial direction. The insertion hole 44 has a small-diameter hole portion 45 on one axial side into which the mounting shaft portion 28 of the piston rod 21 is fitted, and a large-diameter hole portion 46 on the other axial side having a larger diameter than the small-diameter hole portion 45 . is doing. A small-diameter hole portion 45 is provided on the upper chamber 19 side in the axial direction, and a large-diameter hole portion 46 is provided on the lower chamber 20 side in the axial direction.

An annular inner seat portion 47 is formed at the axial end of the piston body 36 on the lower chamber 20 side, radially inward of the piston body 36 from the opening of the annular groove 55 on the lower chamber 20 side. there is At the end of the piston body 36 on the side of the lower chamber 20 in the axial direction, the first damping force generating mechanism 41 is provided outside the opening of the annular groove 55 on the side of the lower chamber 20 in the radial direction of the piston body 36 . An annular valve seat portion 48 forming a part thereof is formed.

An annular inner seat portion 49 is formed at the end of the piston body 36 in the axial direction on the upper chamber 19 side, radially inward of the opening of the annular groove 56 on the upper chamber 19 side of the piston body 36 . . At the end of the piston body 36 on the side of the upper chamber 19 in the axial direction, the first damping force generating mechanism 42 is provided outside the opening of the annular groove 56 on the side of the upper chamber 19 in the radial direction of the piston body 36 . An annular valve seat portion 50 forming a part thereof is formed.

In the insertion hole 44 of the piston body 36 , the large-diameter hole portion 46 is provided closer to the inner seat portion 47 in the axial direction than the small-diameter hole portion 45 . The passage in the large-diameter hole portion 46 of the piston body 36 and the passage in the passage notch portion 30 of the piston rod 21 overlap each other in the axial direction and are always communicated with each other.

In the piston body 36, the radially outer side of the valve seat portion 48 has a stepped shape whose axial height is lower than that of the valve seat portion 48, and the lower chamber of the passage hole 39 on the contraction side is formed in this stepped portion. 20 side openings are arranged. Similarly, in the piston body 36, the radially outer side of the valve seat portion 50 has a stepped shape whose axial height is lower than that of the valve seat portion 50. An opening on the upper chamber 19 side of the hole 38 is arranged.

The compression-side first damping force generating mechanism 42 includes a valve seat portion 50 of the piston 18, and a plurality of (specifically, two) having the same inner diameter and the same outer diameter in order from the piston 18 side in the axial direction. A disk 62, one disk 63, a plurality of (specifically four) disks 64 with the same inner diameter and the same outer diameter, and a plurality of (specifically two) disks with the same inner diameter and the same outer diameter ), a plurality of (specifically, four) discs 66 having the same inner diameter and having an outer diameter that decreases with distance from the piston 18 in the axial direction, one disc 67, and one disc 68. and one annular member 69 . The discs 62 to 68 and the annular member 69 are made of metal, and each of them has a perforated circular plate shape with a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The disc 62 has an outer diameter that is larger than the inner diameter of the inner seat portion 49 of the piston 18 and smaller than the inner diameter of the valve seat portion 50 , and is always in contact with the inner seat portion 49 . The disc 63 has an outer diameter larger than the outer diameter of the disc 62 and smaller than the inner diameter of the valve seat portion 50 . The plurality of discs 64 have an outer diameter substantially equal to the outer diameter of the valve seat portion 50 of the piston 18 and can be seated on the valve seat portion 50 .

The plurality of discs 65 have outer diameters smaller than the outer diameter of the discs 64 . Among the plurality of discs 66 , the one with the largest diameter has an outer diameter smaller than that of the disc 65 . The disc 67 has an outer diameter that is smaller than the outer diameter of the smallest one of the discs 66 and is equal to the outer diameter of the inner seat portion 49 of the piston 18 . The disc 68 has an outer diameter that is larger than the outer diameter of the smallest one of the discs 66 and smaller than the outer diameter of the largest one. The annular member 69 has an outer diameter that is smaller than the outer diameter of the disk 68 and larger than the outer diameter of the shaft step portion 29 of the piston rod 21 . The annular member 69 is thicker and more rigid than the disks 62 to 68 and abuts against the shaft stepped portion 29 .

A plurality of discs 64 , a plurality of discs 65 , and a plurality of discs 66 constitute a contraction-side main valve 71 that can be seated on and removed from the valve seat portion 50 . By separating the main valve 71 from the valve seat portion 50 , the passages in the plurality of passage holes 39 and the annular groove 56 are communicated with the upper chamber 19 , and the flow of oil between the main valve 71 and the valve seat portion 50 . to generate a damping force. The annular member 69 and the disk 68 abut against the main valve 71 to restrict the deformation of the main valve 71 in the opening direction beyond a specified limit.

The passages in the plurality of passage holes 39 and the annular groove 56, and the passages between the main valve 71 and the valve seat portion 50 appearing when the valve is opened, move inside the cylinder 2 by the movement of the piston 18 toward the lower chamber 20 side. A contraction-side first passage 72 is formed through which oil flows from the lower chamber 20 on the upstream side to the upper chamber 19 on the downstream side. The compression-side first damping force generating mechanism 42 that generates damping force includes the main valve 71 and the valve seat portion 50 , and is therefore provided in the first passage 72 . The first passage 72 is formed in the piston 18 including the valve seat portion 50, and allows oil to pass therethrough when the piston rod 21 and the piston 18 move toward the compression side.

Here, in the first damping force generating mechanism 42 on the compression side, both the valve seat portion 50 and the main valve 71 in contact therewith are in contact with the upper chamber 19 and the lower chamber 20. A fixed orifice communicating with is not formed. That is, the compression-side first damping force generating mechanism 42 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other if the valve seat portion 50 and the main valve 71 are in contact with each other over the entire circumference. In other words, the first passage 72 does not have a fixed orifice that constantly communicates the upper chamber 19 and the lower chamber 20 , and is not a passage that constantly communicates the upper chamber 19 and the lower chamber 20 .

The extension-side first damping force generating mechanism 41 includes a valve seat portion 48 of the piston 18, and includes one disc 82, one disc 83, and one disc 83 in order from the piston 18 side in the axial direction. A disc 84, a plurality of (specifically four) discs 85 having the same inner diameter and the same outer diameter, one disc 86, and a plurality of (specifically two) having the same inner diameter and the same outer diameter. , a plurality of (specifically two) discs 88 having the same inner diameter and having an outer diameter that decreases with distance from the piston 18 in the axial direction, and one disc 89 . The discs 82 to 89 are made of metal, and each of them has a perforated circular plate shape with a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The disc 82 has an outer diameter that is larger than the inner diameter of the inner seat portion 47 of the piston 18 and smaller than the inner diameter of the valve seat portion 48 , and is always in contact with the inner seat portion 47 . As shown in FIG. 3, the disc 82 has passages in the annular groove 55 and the plurality of passage holes 38, passages in the large diameter hole portion 46 of the piston 18, and passages in the passage cutout portion 30 of the piston rod 21. A cutout portion 90 is formed from an intermediate position outside the radially inner seat portion 47 to the inner peripheral edge. The notch 90 is formed when the disk 82 is press-molded. The disk 83 has the same outer diameter as the disk 82 and does not have a notch like the disk 82 does. The disk 84 has an outer diameter larger than that of the disk 83 .

The plurality of discs 85 have an outer diameter slightly larger than the outer diameter of the valve seat portion 48 of the piston 18 and can be seated on the valve seat portion 48 . The disc 86 has an outer diameter smaller than that of the disc 85 . The plurality of discs 87 have outer diameters smaller than the outer diameter of the discs 86 . Among the plurality of discs 88 , the outer diameter of the larger one is smaller than the outer diameter of the disc 87 . The disc 89 has a smaller outer diameter than the smaller one of the plurality of discs 88 and has an outer diameter equivalent to the outer diameter of the inner seat portion 47 of the piston 18 . The disc 89 can be a common part having the same shape as the disc 67 . The plurality of discs 88 and 89 are thicker and more rigid than the discs 85-87.

A plurality of discs 85 , a single disc 86 , a plurality of discs 87 , and a plurality of discs 88 constitute an extension-side main valve 91 that can be seated and removed from the valve seat portion 48 . By being separated from the valve seat portion 48 , the main valve 91 communicates the passages in the annular groove 55 and the plurality of passage holes 38 with the lower chamber 20 , and allows the oil to flow between the valve seat portion 48 and the valve seat portion 48 . to generate a damping force.

As shown in FIG. 2, the passages in the plurality of passage holes 38 and the annular groove 55 and the passage between the main valve 91 and the valve seat portion 48 appearing when the valve is open are directed to the upper chamber 19 side of the piston 18. , the oil flows from the upper chamber 19 on the upstream side in the cylinder 2 to the lower chamber 20 on the downstream side. The extension-side first damping force generating mechanism 41 that generates damping force includes a main valve 91 and a valve seat portion 48 , and is therefore provided in the first passage 92 . The first passage 92 is formed in the piston 18 including the valve seat portion 48, and allows oil to pass therethrough when the piston rod 21 and the piston 18 move to the extension side.

In the extension-side first damping force generating mechanism 41, the upper chamber 19 and the lower chamber 20 are communicated with each other even when the valve seat portion 48 and the main valve 91 abutting thereon are in contact with each other. No fixed orifices are formed. That is, the extension-side first damping force generating mechanism 41 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other when the valve seat portion 48 and the main valve 91 are in contact with each other over the entire circumference. In other words, the first passage 92 does not have a fixed orifice that constantly communicates the upper chamber 19 and the lower chamber 20, and is not a passage that constantly communicates the upper chamber 19 and the lower chamber 20.

As shown in FIG. 3, one cap member 101 and one disk 102 are arranged in order from the first damping force generating mechanism 41 side on the side opposite to the piston 18 of the first damping force generating mechanism 41 on the rebound side. , one disk 103, one disk 104, one spring member 105, one disk 106, one disk 107, and one O-ring 108 on the outer peripheral side. One valve seat member 109, one disc 110, one disc 111, one spring member 112, one disc 113, and one annular member 114 are attached to the piston rod 21. A shaft portion 28 is fitted inside each of them. As shown in FIG. 2, the mounting shaft portion 28 of the piston rod 21 is formed with a male thread 31 at a portion protruding beyond the annular member 114, and a nut 115 is screwed onto the male thread 31. As shown in FIG. Nut 115 abuts annular member 114 .

As shown in FIG. 3, cap member 101, discs 102-104, 106, 107, 110, 111, 113, spring members 105, 112, valve seat member 109, and annular member 114 are all made of metal. Each of the discs 102-104, 106, 107, 110, 111, 113 and the annular member 114 is in the form of a perforated circular flat plate having a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted. . The cap member 101, the spring members 105 and 112, and the valve seat member 109 all form an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The cap member 101 is an integrally molded product having a bottomed cylindrical shape, and is formed by, for example, plastic working or cutting of a metal plate. The cap member 101 includes a perforated disk-shaped bottom portion 122, an intermediate tapered portion 123 extending from the outer peripheral edge portion of the bottom portion 122 to one side of the bottom portion 122 in the axial direction while increasing in diameter, and the bottom portion of the intermediate tapered portion 123. It has a cylindrical tubular portion 124 extending in a direction opposite to the bottom portion 122 from an edge portion opposite to 122 . The cap member 101 is arranged in such a manner that the bottom portion 122 faces the piston 18 , contacts the disk 89 , and is fitted to the mounting shaft portion 28 at the inner peripheral portion of the bottom portion 122 .

An annular convex portion 126 is formed on the outer peripheral side of the bottom portion 122 so as to protrude toward the cylindrical portion 124 in the axial direction. The cap member 101 is thicker than the disks 85 to 88, and has a higher rigidity than the disks 85 to 88 in combination with the formation of the annular projection 126 and the bottomed cylindrical shape. . Therefore, the cap member 101 abuts on the main valve 91 and restricts deformation in the opening direction of the main valve 91 composed of the plurality of discs 85 to 88 beyond a specified limit.

The valve seat member 109 is in the shape of a perforated disc having a through hole 131 formed in the center in the radial direction thereof, through which the mounting shaft portion 28 is inserted through in the thickness direction. The through-hole 131 has a small-diameter hole portion 136 on one axial side into which the mounting shaft portion 28 of the piston rod 21 is fitted, and a large-diameter hole portion 137 on the other axial side having a larger diameter than the small-diameter hole portion 136 . is doing.

The valve seat member 109 has an inner seat portion 134 and a valve seat portion 135 (second seat portion) in order from the inner side in the radial direction of the valve seat member 109 on the large diameter hole portion 137 side in the axial direction. An inner seat portion 138 and a valve seat portion 139 (first seat portion) are provided in order from the inner side in the radial direction of the valve seat member 109 on the side of the small diameter hole portion 136 on the opposite side.

The inner seat portion 134 has an annular shape and protrudes to one side along the axial direction of the valve seat member 109 from the inner peripheral edge portion of the valve seat member 109 . The valve seat portion 135 also has an annular shape and protrudes from a predetermined radially outer position of the valve seat member 109 to the same side as the inner seat portion 134 along the axial direction of the valve seat member 109 . The inner seat portion 134 and the valve seat portion 135 are flush with the front end surfaces on the protruding side extending in the direction orthogonal to the axis. The inner seat portion 134 has a large-diameter hole portion 137 on the radially inner side thereof.

The inner seat portion 138 also has an annular shape and protrudes from the inner peripheral edge portion of the valve seat member 109 along the axial direction of the valve seat member 109 to the side opposite to the inner seat portion 134 . The inner seat portion 138 has a small-diameter hole portion 136 on the radially inner side thereof. The inner seat portions 134, 138 have the same outer diameter. The valve seat portion 139 also has an annular shape and protrudes from a predetermined radially outer position of the valve seat member 109 to the same side as the inner seat portion 138 along the axial direction of the valve seat member 109 . The inner seat portion 138 and the valve seat portion 139 are also flush with the front end surfaces on the protruding side extending in the direction orthogonal to the axis. The valve seat portion 135 and the valve seat portion 139 protrude in opposite directions and have the same inner diameter and the same outer diameter.

The valve seat member 109 has an axially extending end face between the inner seat portion 138 and the valve seat portion 139 from the outer side in the radial direction of the valve seat member 109 from the valve seat portion 135 on the side of the valve seat portion 135 in the axial direction. A plurality of passage holes 141 (only one of which is shown in FIGS. 2 and 3 because they are cross sections) are formed through the valve seat member 109 in the axial direction. The passage hole 141 is linear. In the valve seat member 109 , an annular groove 142 is formed between the inner seat portion 138 and the valve seat portion 139 to communicate with the plurality of passage holes 141 . A first passage portion 151 provided in the valve seat member 109 is formed inside the plurality of passage holes 141 and the annular groove 142 .

As shown in FIG. 2, the valve seat member 109 has an inner seat portion 134 and a valve seat portion 135 from the outside in the radial direction of the valve seat member 109 from the valve seat portion 139 of the end face on the side of the valve seat portion 139 in the axial direction. A plurality of passage holes 143 (only one of which is shown in FIG. 2 because it is a cross section) are formed extending through the end face between and axially through the valve seat member 109 . The passage hole 143 is linear. The valve seat member 109 has an annular groove 144 formed between the inner seat portion 134 and the valve seat portion 135 for communicating with the plurality of passage holes 143 . A second passage portion 152 provided in the valve seat member 109 is formed inside the plurality of passage holes 143 and the annular groove 144 . A plurality of first passage portions 151 and a plurality of second passage portions 152 constitute a valve seat member passage portion 150 provided in the valve seat member 109 and through which oil flows.

As shown in FIG. 4, the valve seat member 109 has a plurality of passage holes 141, specifically twelve passage holes 141, which are aligned in the radial direction of the valve seat member 109, They are formed at equal pitches with one passage hole 143 sandwiched therebetween. The valve seat member 109 has a plurality of, specifically twelve, passage holes 143 aligned in the radial direction of the valve seat member 109 and one passage hole between each in the circumferential direction of the valve seat member 109 . They are formed at equal pitches with the hole 141 interposed therebetween. Passage holes 143 are arranged at half pitches of the arrangement pitch of the passage holes 141 . As shown in FIG. 4(a), an annular groove 142 communicating with a plurality of passage holes 141 has an annular shape. As shown in FIG. 4(b), an annular groove 144 communicating with a plurality of passage holes 143 is formed. is also circular.

As shown in FIG. 3, the valve seat member 109 is formed with an annular seal groove 145 recessed radially inward at an axially intermediate position of the outer peripheral portion. An O-ring 108 is arranged in this seal groove 145 . The valve seat member 109 is fitted in the cylindrical portion 124 of the cap member 101 at the outer peripheral portion thereof with the inner seat portion 134 and the valve seat portion 135 directed toward the bottom portion 122 side. It is In this state, the O-ring 108 seals the gap between the tubular portion 124 of the cap member 101 and the valve seat member 109 .

The cap member 101, the O-ring 108 and the valve seat member 109 form a cap chamber 146 inside. The cap chamber 146 is provided between the bottom portion 122 of the cap member 101 and the valve seat member 109 . Disks 102-104, spring member 105 and disks 106, 107 are provided in this cap chamber 146. As shown in FIG. As shown in FIG. 2 , the annular valve seat member 109 and the bottomed cylindrical cap member 101 are arranged in the lower chamber 20 which is one of the upper chamber 19 and the lower chamber 20 . At this time, the valve seat member 109 has the valve seat portion 135 on the cap chamber 146 side and the valve seat portion 139 on the lower chamber 20 side. The valve seat member 109 separates the cap chamber 146 and the lower chamber 20 and is provided facing both the cap chamber 146 and the lower chamber 20 .

As shown in FIG. 3 , the disk 102 has an outer diameter smaller than the inner diameter of the protrusion 126 of the cap member 101 and abuts radially inward of the protrusion 126 of the bottom 122 . The disk 102 can be a common part with the same shape as the disk 89 . The disc 103 has an outer diameter smaller than the inner diameter of the protrusion 126 and larger than the outer diameter of the disc 102 . A notch 153 is formed in the disk 103 from a midway position outside the outer peripheral portion of the disk 102 in the radial direction to the inner peripheral edge. The notch 153 is formed when the disk 103 is press-molded. Note that the disk 103 can be a common component having the same shape as the disk 82 . The disc 104 has an outer diameter equivalent to that of the disc 102 .

The passage in the notch 153 of the disk 103 always communicates the inside of the cap chamber 146 with the passage in the passage notch 30 of the piston rod 21 . Therefore, the cap chamber 146 consists of a passage in the notch 153 of the disk 103, a passage in the passage notch 30 of the piston rod 21, a passage in the large diameter hole 137 of the valve seat member 109, and a large diameter hole of the piston 18. 2 through passages in portion 46, passages in notch 90 of disk 82, passages in annular groove 55 of piston 18 and in passage holes 38. ing.

As shown in FIG. 3, the spring member 105 includes a base plate portion 155 having a perforated circular plate shape with a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted, and an outer peripheral edge portion of the base plate portion 155. and a leg plate portion 156 extending radially outward from the base plate portion 155 so as to be located on one side in the axial direction as it goes radially outward. A plurality of leg plate portions 156 are formed on the spring member 105 at intervals in the circumferential direction of the substrate portion 155 .

The disk 106 has an outer diameter equivalent to that of the disks 102 and 104, and its thickness is slightly larger than the height of the leg plate 156 from the base plate 155 in the axial direction of the spring member 105 in its natural state. It's getting smaller.

The disk 107 has an outer diameter slightly larger than the outer diameter of the valve seat portion 135 of the valve seat member 109 and is always in contact with the inner seat portion 134 so that it can be seated on the valve seat portion 135 . The spring member 105 abuts on the disk 107 with the leg plate portion 156 extending from the substrate portion 155 toward the disk 107 . The leg plate portion 156 is elastically deformed by coming into contact with the disc 107 and applies a preload in the direction in which the disc 107 is seated on the valve seat portion 135 .

The spring member 105 , the disk 106 and the disk 107 constitute a sub-valve 171 (second sub-valve) that can be seated on and removed from the valve seat portion 135 . The sub-valve 171 is provided in the cap chamber 146 and is separated from the valve seat portion 135 in the cap chamber 146 so that the second passage portion 152 in the plurality of passage holes 143 and the annular groove 144 and the cap The lower chamber 20 is communicated with the chamber 146 and the upper chamber 19 shown in FIG. At this time, the sub-valve 171 suppresses the flow of oil between the valve seat portion 135 and generates a damping force. The sub-valve 171 is an inflow valve that opens when oil is allowed to flow into the cap chamber 146 from the lower chamber 20 through the plurality of passage holes 143 and the second passage portion 152 in the annular groove 144. is a check valve that regulates the outflow of oil from the lower chamber 20 through the second passage portion 152 . Here, since the passage hole 141 forming the first passage portion 151 opens radially outward from the valve seat portion 135 , it always communicates with the cap chamber 146 independently of the sub-valve 171 .

The second passage portion 152 in the plurality of passage holes 143 and the annular groove 144, the passage between the sub-valve 171 and the valve seat portion 135 appearing when the valve is opened, the cap chamber 146, and the notch portion 153 of the disc 103. Passages, passages in the passage notch 30 of the piston rod 21, passages in the large diameter hole 137 of the valve seat member 109, passages in the large diameter hole 46 of the piston 18, and passages in the notch 90 of the disc 82 and the passages in the annular groove 55 of the piston 18 and the passages in the plurality of passage holes 38 move to the upper chamber downstream from the lower chamber 20 upstream in the cylinder 2 due to the movement of the piston 18 toward the lower chamber 20 side. 19 constitutes a second passage 172 through which oil flows out. The second passage 172 serves as a contraction-side passage through which oil flows from the lower chamber 20 on the upstream side toward the upper chamber 19 on the downstream side during the movement of the piston 18 toward the lower chamber 20 side, that is, the compression stroke. The second passage 172 includes a passage in the passage cutout portion 30 formed by notching the piston rod 21 , in other words, a part thereof is formed by notching the piston rod 21 .

A sub-valve 171 consisting of a spring member 105, discs 106 and 107, a valve seat portion 135, discs 102 to 104, and a cap member 101 are provided in a second passage 172 on the contraction side. A compression-side second damping force generating mechanism 173 is configured that opens and closes and suppresses the flow of oil from the second passage 172 to the upper chamber 19 to generate a damping force. In other words, the valve seat portion 135 of the second damping force generating mechanism 173 is provided on the valve seat member 109 . The sub-valve 171 that constitutes the compression-side second damping force generating mechanism 173 is a compression-side sub-valve.

In the second passage 172, when the second damping force generating mechanism 173 is in the open state, the passage in the notch 90 of the disk 82 has the narrowest passage cross-sectional area among the fixed passage cross-sectional areas. is narrower than its upstream and downstream sides resulting in an orifice 175 in the second passageway 172 . The orifice 175 is arranged downstream of the sub-valve 171 in the flow of oil when the sub-valve 171 opens and the oil flows through the second passage 172 . The orifice 175 is formed by notching the disk 82 of the first damping force generating mechanism 41 that contacts the piston 18 .

The second damping force generating mechanism 173 on the compression side has a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to communicate with each other in both the valve seat portion 135 and the sub-valve 171 in contact therewith. is not formed. That is, the contraction-side second damping force generating mechanism 173 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other if the valve seat portion 135 and the disc 107 are in contact with each other over the entire circumference. In other words, the second passageway 172 does not have a fixed orifice that constantly communicates the upper chamber 19 and the lower chamber 20, and is not a passageway that constantly communicates the upper chamber 19 and the lower chamber 20 with each other. The bottom portion 122 of the cap member 101 is thicker and more rigid than the disk 107 that constitutes the sub-valve 171, and contacts the sub-valve 171 to restrict deformation in the opening direction of the sub-valve 171 beyond a prescribed limit.

The second passage 172 on the contraction side that allows communication between the upper chamber 19 and the lower chamber 20 is arranged in parallel with the first passage 72 on the contraction side that similarly allows communication between the upper chamber 19 and the lower chamber 20. A first damping force generating mechanism 42 is provided in the first passage 72, and a second damping force generating mechanism 173 is provided in the second passage 172, respectively. Therefore, both the first damping force generating mechanism 42 and the second damping force generating mechanism 173 on the compression side are arranged in parallel.

As shown in FIG. 3, the disc 110 has an outer diameter slightly larger than the outer diameter of the valve seat portion 139 of the valve seat member 109, and is always in contact with the inner seat portion 138 and against the valve seat portion 139. It is possible to sit down. Disk 110 can be a common part with the same shape as disk 107 . The outer diameter of disk 111 is smaller than the outer diameter of disk 110 and equal to the outer diameter of inner seat portion 138 . The disc 111 can be a common part having the same shape as the disc 106 .

The spring member 112 includes a base plate portion 191 having a perforated circular flat plate shape of a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted, and a radial direction of the base portion 191 from the outer peripheral edge portion of the base plate portion 191 . It has a leg plate portion 192 extending outward so as to be located on one side in the axial direction as it goes radially outward. A plurality of leg plate portions 192 are formed on the spring member 112 at intervals in the circumferential direction of the substrate portion 191 . The height of the leg plate portion 192 in the natural state from the substrate portion 191 in the axial direction of the substrate portion 191 is slightly larger than the thickness of the disk 111 . The spring member 112 can be a common part having the same shape as the spring member 105 .

The spring member 112 contacts the disk 110 with the leg plate portion 192 extending toward the disk 110 from the substrate portion 191 . The leg plate portion 192 is elastically deformed by coming into contact with the disc 110 and applies a preload in the direction in which the disc 110 is seated on the valve seat portion 139 . The disk 113 has an outer diameter larger than that of the disk 110, is thicker than the disk 110, and has high rigidity. The annular member 114 has an outer diameter smaller than the outer diameter of the disk 113 and is thicker than the disk 110 and has high rigidity.

The disk 110 , the disk 111 and the spring member 112 constitute a sub-valve 181 (first sub-valve) that can be seated on and removed from the valve seat portion 139 . The sub-valve 181 is provided in the lower chamber 20 and allows the cap chamber 146 and the lower chamber 20 to communicate with each other by being separated from the valve seat portion 139 . At this time, the sub-valve 181 suppresses the flow of oil between the valve seat portion 139 and generates a damping force. The sub-valve 181 is a discharge valve that opens when oil is discharged from the cap chamber 146 to the lower chamber 20 through the plurality of passage holes 141 of the valve seat member 109 and the first passage portion 151 in the annular groove 142 . It is a check valve that regulates the inflow of oil from the lower chamber 20 into the cap chamber 146 through the first passage portion 151 . Here, since the passage hole 143 forming the second passage portion 152 is open radially outward of the valve seat portion 139 , it always communicates with the lower chamber 20 independently of the sub-valve 181 .

Passages in the plurality of passage holes 38 and the annular groove 55 of the piston 18, passages in the notch 90 of the disk 82, passages in the passage notch 30 of the piston rod 21, and the large diameter hole 46 of the piston 18. and the passage in the large diameter hole portion 137 of the valve seat member 109, the passage in the cutout portion 153 of the disk 103, the cap chamber 146, the plurality of passage holes 141 of the valve seat member 109 and the annular groove 142. The first passage portion 151 and the passage between the sub-valve 181 and the valve seat portion 139 appearing when the valve is opened become the upstream side in the cylinder 2 due to the movement of the piston 18 toward the upper chamber 19 side shown in FIG. A second passage 182 is formed through which oil flows from the upper chamber 19 to the lower chamber 20 on the downstream side. The second passage 182 serves as an elongation-side passage through which oil flows from the upper chamber 19 on the upstream side toward the lower chamber 20 on the downstream side during the movement of the piston 18 toward the upper chamber 19 side, that is, the extension stroke. The second passage 182 includes a passage in the passage cutout portion 30 formed by notching the piston rod 21 , in other words, a part thereof is formed by notching the piston rod 21 .

A cap member 101, a sub-valve 181, a valve seat portion 139, a disk 113, and an annular member 114 are provided in a second passage 182 on the extension side, and open and close the second passage 182 to open and close the second passage 182. A second damping force generating mechanism 183 on the elongation side for generating a damping force by suppressing the flow of oil from the lower chamber 20 to the lower chamber 20 is configured. In other words, the second damping force generating mechanism 183 has the valve seat portion 139 provided on the valve seat member 109 . The sub-valve 181 that constitutes the extension-side second damping force generating mechanism 183 is an extension-side sub-valve.

In the second passage 182, when the second damping force generating mechanism 183 is in the open state, the passage in the notch 90 of the disc 82 has the narrowest passage cross-sectional area among the fixed passage cross-sectional areas. becomes narrower than its upstream and downstream sides and forms an orifice 175 also in the second passage 182 . The orifice 175 is common to the second passages 172,182. The orifice 175 is arranged on the upstream side of the sub-valve 181 when the sub-valve 181 opens and the oil flows through the second passage 182 . The orifice 175 may be arranged downstream of the sub-valve 181 when the sub-valve 181 opens and the oil flows through the second passage 182 . The sub-valve 181 and the above-described sub-valve 171 are opened and closed independently.

The extension-side second damping force generating mechanism 183 has a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to communicate with each other, even when the valve seat portion 139 and the disc 110 abutting thereon are in contact with each other. is not formed. That is, the extension-side second damping force generating mechanism 183 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other when the valve seat portion 139 and the disc 110 are in contact with each other over the entire circumference. In other words, the second passageway 182 does not have a fixed orifice that constantly communicates the upper chamber 19 and the lower chamber 20, and is not a passageway that constantly communicates the upper chamber 19 and the lower chamber 20 with each other. The annular member 114 and the disc 113 contact the sub-valve 181 to prevent the sub-valve 181 from deforming in the opening direction beyond a specified limit.

In the shock absorber 1, at least in the axial direction of the oil flow in the piston 18, the upper chamber 19 and the lower chamber 20 are composed of the first damping force generating mechanisms 41, 42 and the second damping force generating mechanism 173, Only via 183 can be communicated. Therefore, the shock absorber 1 is not provided with a fixed orifice that constantly communicates between the upper chamber 19 and the lower chamber 20 at least on the passage of oil that passes through the piston 18 in the axial direction.

A second passage 182 on the extension side that communicates between the upper chamber 19 and the lower chamber 20 includes a first passage 92 on the extension side that similarly communicates between the upper chamber 19 and the lower chamber 20, and a passage on the upper chamber 19 side. The first damping force generating mechanism 41 is connected to the first passage 92, and the second damping force A generating mechanism 183 is provided respectively. Therefore, both the first damping force generating mechanism 41 and the second damping force generating mechanism 183 on the extension side are arranged in parallel.

The second damping force generating mechanism 173, 183 includes a valve seat member 109, a sub-valve 181 provided on one side of a valve seat member passage portion 150, which is a portion of the second passages 172, 182 provided on the valve seat member 109, and a valve. A sub-valve 171 provided on the other side of the seat member passage portion 150 , and a bottomed cylindrical cap member 101 provided between the piston 18 and the valve seat member 109 in the second passages 172 and 182 . The valve seat member 109 is provided inside the cap member 101 , the sub-valve 181 is provided on the lower chamber 20 side of the valve seat member 109 , and the sub-valve 171 is provided between the bottom portion 122 of the cap member 101 and the valve seat member 109 . is provided in the cap chamber 146 of the.

In the valve seat member passage portion 150 , the first passage portion 151 provided with the sub-valve 181 and opened and closed by the sub-valve 181 has the upstream end of the oil flow on the cap chamber 146 side radially outside the valve seat portion 135 . , and the downstream end of the oil flow, which is on the sub-valve 181 side, opens radially inward of a valve seat portion 139 having the same diameter as the valve seat portion 135 . Therefore, in the first passage portion 151, the upstream end and the downstream end of the flow of the hydraulic fluid, which is the working fluid, are offset in the radial direction of the valve seat member 109. Specifically, the downstream end of the flow of the working fluid is is disposed radially inward of the valve seat member 109 relative to the upstream end.

The second passage portion 152 of the valve seat member passage portion 150 is provided with a sub-valve 171 and is opened and closed by the sub-valve 171 . , and the downstream end of the oil flow on the sub-valve 171 side opens radially inward of the valve seat portion 135 having the same diameter as the valve seat portion 139 . Therefore, the upstream end and the downstream end of the second passage portion 152 for the flow of the hydraulic fluid, which is the working fluid, are offset in the radial direction of the valve seat member 109. Specifically, the downstream end for the flow of the working fluid is is disposed radially inward of the valve seat member 109 relative to the upstream end.

In other words, on the sub-valve 181 side of the valve seat member 109 , a valve seat portion 139 is formed on which the sub-valve 181 is seated on the radially outer side of the valve seat member 109 relative to the first passage portion 151 . A valve seat portion 135 on which the sub-valve 171 is seated is formed outside the second passage portion 152 in the radial direction of the valve seat member 109 on the side of the sub-valve 171 . have the same diameter.

When assembling the piston 18 and the like to the piston rod 21, the annular member 69, the disk 68, the disk 67, and the plurality of disks 66 are mounted on the shaft stepped portion 29 while the mounting shaft portion 28 of the piston rod 21 is inserted therethrough. , a plurality of discs 65, a plurality of discs 64, a disc 63, a plurality of discs 62, and a piston 18 are stacked in order. At this time, the piston 18 is oriented so that the small-diameter hole portion 45 is located on the shaft step portion 29 side. In addition, while inserting the mounting shaft portions 28 respectively, the piston 18 is mounted with a disc 82, a disc 83, a disc 84, a plurality of discs 85, a plurality of discs 86, a plurality of discs 87, and a plurality of discs. The disk 88, the disk 89, and the cap member 101 are stacked in order. At this time, the cap member 101 contacts the disk 89 with the bottom portion 122 facing the piston 18 . Further, the disk 102, the disk 103, the disk 104, and the spring member 105 are stacked in order on the bottom portion 122 of the cap member 101 while inserting the mounting shaft portions 28 respectively. At this time, the spring member 105 is oriented such that the leg plate portion 156 extends from the base portion 155 to the side opposite to the piston 18, as shown in FIG.

In addition, the disk 106 , the disk 107 , and the valve seat member 109 with the O-ring 108 mounted thereon are sequentially stacked on the spring member 105 while inserting the mounting shafts 28 respectively. At this time, the valve seat member 109 is oriented such that the inner seat portion 134 and the valve seat portion 135 are located on the disk 107 side, and the outer peripheral portion and the O-ring 108 are fitted to the cylindrical portion 124 of the cap member 101 . Further, the disk 110, the disk 111, the spring member 112, the disk 113, and the annular member 114 are sequentially stacked on the valve seat member 109 while the mounting shaft portion 28 is inserted therethrough. At this time, the spring member 112 is oriented such that the leg plate portion 192 extends from the base plate portion 191 toward the piston 18 side. In this state, as shown in FIG. 2, the nut 115 is screwed onto the male thread 31 of the piston rod 21 projecting beyond the annular member 114, and the nut 115 and the shaft stepped portion 29 support the inner peripheral side of them. direction to clamp.

In this state, the inner peripheral side of the main valve 71 is clamped by the inner seat portion 49 of the piston 18 and the disc 67 via the discs 62 and 63, and abuts against the valve seat portion 50 of the piston 18 over the entire periphery. In this state, the inner peripheral side of the main valve 91 is clamped by the inner seat portion 47 of the piston 18 and the disc 89 via the discs 82 to 84, and is in contact with the valve seat portion 48 of the piston 18 over the entire periphery. touch. In this state, the sub-valve 171 is clamped on the inner peripheral side between the inner seat portion 134 of the valve seat member 109 and the disc 104 and contacts the valve seat portion 135 of the valve seat member 109 over the entire periphery. In this state, the sub-valve 181 is clamped on the inner peripheral side between the inner seat portion 138 of the valve seat member 109 and the disk 113 and contacts the valve seat portion 139 of the valve seat member 109 over the entire periphery.

Of the first damping force generating mechanism 41 and the second damping force generating mechanism 183, both of which are on the rebound side, the main valve 91 of the first damping force generating mechanism 41 has higher rigidity than the sub-valve 181 of the second damping force generating mechanism 183. High valve opening pressure. Therefore, in the extension stroke, the second damping force generating mechanism 183 is opened while the first damping force generating mechanism 41 is closed in an extremely low speed region in which the piston speed is lower than a predetermined value. Also, in the normal speed range where the piston speed is equal to or higher than the predetermined value, both the first damping force generating mechanism 41 and the second damping force generating mechanism 183 are opened. The sub-valve 181 is a very low speed valve that opens in a region where the piston speed is very low to generate a damping force.

That is, in the extension stroke, as the piston 18 moves toward the upper chamber 19, the pressure in the upper chamber 19 increases and the pressure in the lower chamber 20 decreases. Since neither of the damping force generating mechanisms 173, 183 has a fixed orifice, oil does not flow until the second damping force generating mechanism 183 is opened. Therefore, the damping force rises sharply in the extension stroke when the piston speed is less than the first predetermined value v1. In addition, the piston speed is in a region higher than the first predetermined value v1 at which the second damping force generating mechanism 183 opens, and is lower than the second predetermined value v2, which is higher than the first predetermined value v1. In the low speed region (v1 or more and less than v2), the first damping force generation mechanism 41 is closed and the second damping force generation mechanism 183 is opened.

That is, the sub-valve 181 is separated from the valve seat portion 139, and the upper chamber 19 and the lower chamber 20 are communicated with each other through the second passage 182 on the expansion side. Therefore, the oil in the upper chamber 19 flows through the passages in the plurality of passage holes 38 of the piston 18 and the annular groove 55 , the orifice 175 , the passages in the passage cutout 30 of the piston rod 21 , and the large-diameter hole in the piston 18 . passages in the portion 46 , passages in the large-diameter hole portion 137 of the valve seat member 109 , passages in the notch portion 153 of the disk 103 , cap chambers 146 , passage holes 141 , and annular grooves 142 . It flows into the lower chamber 20 via the 1 passage portion 151 and the passage between the sub-valve 181 and the valve seat portion 139 . As a result, a damping force with valve characteristics (a characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in an extremely low speed region (v1 or more and less than v2) where the piston speed is lower than the second predetermined value v2.

Further, in the extension stroke, in the normal speed range where the piston speed is equal to or higher than the second predetermined value v2, the first damping force generating mechanism 41 opens while the second damping force generating mechanism 183 remains open. That is, the sub-valve 181 is separated from the valve seat portion 139, and oil flows from the upper chamber 19 to the lower chamber 20 through the second passage 182 on the extension side. The orifice 175 provided on the downstream side of the valve 91 restricts the flow of the oil, so that the pressure applied to the main valve 91 increases and the differential pressure increases, causing the main valve 91 to separate from the valve seat portion 48. , the oil flows from the upper chamber 19 to the lower chamber 20 through the first passage 92 on the extension side. Therefore, the oil in the upper chamber 19 flows into the lower chamber 20 through passages in the plurality of passage holes 38 and the annular groove 55 and passages between the main valve 91 and the valve seat portion 48 . As a result, even in the normal speed region where the piston speed is equal to or higher than the second predetermined value, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) can be obtained. The increase rate of the rebound damping force with respect to the increase in the piston speed in the normal speed region is lower than the increase rate of the rebound damping force with respect to the increase in the piston speed in the extremely low speed region. In other words, the slope of the increase rate of the damping force on the extension side with respect to the increase in the piston speed in the normal speed region can be flatter than in the extremely low speed region.

Here, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the second predetermined value v2, the differential pressure between the upper chamber 19 and the lower chamber 20 is in the low speed region equal to or higher than the first predetermined value v1 and less than the second predetermined value v2. However, since the first passage 92 is not throttled by an orifice, the oil can flow through the first passage 92 at a large flow rate by opening the main valve 91 . By this and by narrowing the second passage 182 with the orifice 175, deformation of the sub-valve 181 can be suppressed.

Also, at this time, the sub-valve 171 in the closed state is subjected to opposite pressures from the lower chamber 20 and the cap chamber 146 . Even if the differential pressure between the upper chamber 19 and the lower chamber 20 increases, since the orifice 175 is formed on the upstream side of the sub-valve 171 in the second passage 182, the pressure rise in the cap chamber 146 will cause the pressure in the upper chamber 19 to rise. The increase in pressure between the cap chamber 146 and the lower chamber 20 is suppressed. Therefore, it is possible to suppress an increase in the pressure difference between the cap chamber 146 and the lower chamber 20 that the sub-valve 171 in the closed state receives, thereby preventing a large back pressure from being applied to the sub-valve 171 from the cap chamber 146 side toward the lower chamber 20 side. can be suppressed.

The shock absorber 1 is provided with a first passage 92 and a second passage 182 in parallel with a flow path through which oil flows from the upper chamber 19 to the lower chamber 20 in the extension stroke, and the main valve 91 and the sub valve 181 are provided in parallel. there is Orifice 175 is also connected in series with sub-valve 181 .

As described above, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the second predetermined value v2, the main valve 91 opens to allow a large amount of oil to flow through the first passage 92. . As a result, the flow rate through the passage between the sub-valve 181 and the valve seat portion 139 is reduced. Therefore, the valve rigidity of the sub-valve 181 can be lowered. Therefore, for example, when the piston speed is in the normal speed region (v2 or higher), it is possible to reduce the increase rate of the damping force with respect to the increase in the piston speed. In other words, the slope of the rate of increase of the damping force on the extension side with respect to the increase in piston speed in the normal speed region (v2 or more) can be made flatter than in the extremely low speed region (less than v2). Thereby, the degree of freedom in design can be expanded.

Of the first damping force generating mechanism 42 and the second damping force generating mechanism 173 on the compression side, the main valve 71 of the first damping force generating mechanism 42 has higher rigidity than the sub valve 171 of the second damping force generating mechanism 173. High valve opening pressure. Therefore, in the compression stroke, when the piston speed is lower than a predetermined value, the second damping force generating mechanism 173 is opened while the first damping force generating mechanism 42 is closed, and the piston speed is reduced to this predetermined value. In the above normal speed range, both the first damping force generating mechanism 42 and the second damping force generating mechanism 173 are opened. The sub-valve 171 is a very low speed valve that opens in a region where the piston speed is very low to generate a damping force.

That is, in the compression stroke, as the piston 18 moves toward the lower chamber 20, the pressure in the lower chamber 20 increases and the pressure in the upper chamber 19 decreases. Since neither of the damping force generating mechanisms 173, 183 has a fixed orifice, oil does not flow until the second damping force generating mechanism 173 is opened. Therefore, the damping force rises sharply. In a region where the piston speed is higher than the third predetermined value at which the second damping force generating mechanism 173 opens and is lower than the fourth predetermined value, which is higher than the third predetermined value and lower than the fourth predetermined value, the second The first damping force generating mechanism 42 is closed, and the second damping force generating mechanism 173 is opened.

That is, the sub-valve 171 is separated from the valve seat portion 135, and the lower chamber 20 and the upper chamber 19 are communicated with each other through the second passage 172 on the contraction side. Therefore, the oil in the lower chamber 20 flows through the second passage portion 152 in the plurality of passage holes 143 and the annular groove 144, the passage between the sub-valve 171 and the valve seat portion 135, the cap chamber 146, and the disk 103. A passage in the notch 153 , a passage in the passage notch 30 of the piston rod 21 , a passage in the large-diameter hole 137 of the valve seat member 109 , a passage in the large-diameter hole 46 of the piston 18 , and the orifice 175 . , and passages in the annular groove 55 of the piston 18 and in the plurality of passage holes 38 into the upper chamber 19 . As a result, even in an extremely low speed region in which the piston speed is lower than the fourth predetermined value, a damping force with a valve characteristic (a characteristic in which the damping force is substantially proportional to the piston speed) can be obtained.

In the compression stroke, the first damping force generating mechanism 42 opens while the second damping force generating mechanism 173 remains open in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value. In other words, the sub-valve 171 is separated from the valve seat portion 135, and oil flows from the lower chamber 20 to the upper chamber 19 through the second passage 172 on the contraction side. Since the flow rate of the oil is restricted at , the differential pressure generated in the main valve 71 provided in the first passage 72 increases, the main valve 71 is separated from the valve seat portion 50, and the contraction-side first 1 passage 72 allows oil to flow from the lower chamber 20 to the upper chamber 19 . Therefore, the oil in the lower chamber 20 flows through passages in the plurality of passage holes 39 and the annular groove 56 and passages between the main valve 71 and the valve seat portion 50 . As a result, even in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) can be obtained. The increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region is lower than the increase rate of the compression damping force with respect to the increase in piston speed in the extremely low speed region. In other words, the slope of the increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region can be flatter than in the extremely low speed region.

In the compression stroke, the differential pressure between the lower chamber 20 and the upper chamber 19 is greater in the normal speed region where the piston speed is the fourth predetermined value or higher than in the low speed region. By opening the main valve 71 , the oil can flow at a large flow rate through the first passage 72 . As a result, the flow rate through the sub-valve 171 is reduced, so that the valve rigidity of the sub-valve 171 can be reduced. Therefore, the damping force can be reduced when the piston speed is in the normal speed region, and the degree of freedom in design can be expanded.

At this time (when the piston speed is high), although the differential pressure between the lower chamber 20 and the upper chamber 19 increases, the second passage 172 is narrowed by the orifice 175 so that it communicates with the upper chamber 19 through the orifice 175. Since the pressure in the cap chamber 146 becomes the pressure between the lower chamber 20 and the upper chamber 19, it is possible to suppress the differential pressure with the lower chamber 20 from becoming too large. This and the opening of the main valve 71 allows a large amount of oil to flow through the first passage 72 , thereby suppressing deformation of the sub-valve 171 .

At this time, pressures are applied to the sub-valve 181 in the closed state from the lower chamber 20 and the cap chamber 146 in opposite directions. and the cap chamber 146 are communicated with each other by opening the sub-valve 171, and since an orifice 175 is provided between the cap chamber 146 and the upper chamber 19 on the downstream side of the sub-valve 181, the inside of the cap chamber 146 An excessive decrease in pressure can be suppressed, and the pressure in the cap chamber 146 can be increased in accordance with the pressure increase in the lower chamber 20 . Therefore, the differential pressure generated between the upstream and downstream surfaces of the sub-valve 181 is small, and it is possible to suppress the application of a large back pressure to the sub-valve 181 from the lower chamber 20 side toward the cap chamber 146 side.

In the shock absorber 1 described above, the first passage 72 and the second passage 172 are arranged in parallel to flow the oil from the lower chamber 20 to the upper chamber 19 in the compression stroke, and the main valve 71 and the sub-valve 171 are arranged in parallel. are provided. Also, the orifice 175 is connected in series with the sub-valve 171 in the second passage 172 .

In the extension stroke, the differential pressure between the upper chamber 19 and the lower chamber 20 increases in the normal speed region where the piston speed is equal to or higher than the second predetermined value. Since an increase in pressure can be suppressed, deformation of the sub-valve 171 due to back pressure can be suppressed. In the compression stroke, the differential pressure between the lower chamber 20 and the upper chamber 19 is greater in the normal speed region where the piston speed is the fourth predetermined value or higher than in the low speed region. Deformation of the sub-valve 171 can be suppressed by allowing the fluid to flow and restricting the downstream side of the second passage 172 from the sub-valve 171 by the orifice 175 . Therefore, the durability of the sub-valve 171 can be improved.

In the extension stroke, the differential pressure between the upper chamber 19 and the lower chamber 20 is greater in the normal speed region where the piston speed is equal to or higher than the second predetermined value, but the oil is allowed to flow through the first passage 92 at a large flow rate. , and by narrowing the second passage 182 with the orifice 175, deformation of the sub-valve 181 can be suppressed. In the compression stroke, the pressure difference between the lower chamber 20 and the upper chamber 19 increases in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value. Moreover, the cap chamber 146 and the upper chamber 19 are throttled by the orifice 175 provided between the cap chamber 146 and the upper chamber 19 . Therefore, the differential pressure between the lower chamber 20 and the cap chamber 146 is small, and deformation due to the back pressure of the sub-valve 181 can be suppressed. Therefore, durability of the sub-valve 181 can be improved.

Since the second damping force generating mechanisms 173 and 183 are provided independently for the contraction stroke and extension stroke, the degree of freedom in setting damping force characteristics is increased.

Patent Documents 1 and 2 described above describe those having two valves that open in the same stroke. By adopting a structure having two valves that open in the same stroke in this way, one valve is opened in a region where the piston speed is lower than the other valve, and both valves are opened in a region where the piston speed is higher than this. A valve can be opened. In such a structure, it is required to improve the durability of the low-speed side valve in particular.

On the other hand, in the shock absorber 1 of the first embodiment, the second damping mechanism of the second passages 172, 182 parallel to the first passages 72, 92 of the piston 18 in which the first damping force generating mechanisms 41, 42 are provided. The sub-valves 181 and 171 of the force generating mechanisms 173 , 183 are provided on the valve seat member 109 arranged in the lower chamber 20 . At the same time, a cylindrical cap member 101 with a bottom is provided between the piston 18 and the valve seat member 109 in the second passages 172 and 182, with the valve seat member 109 arranged inside. At this time, the sub-valve 181 is provided on the lower chamber 20 side, and the sub-valve 171 is provided in the cap chamber 146 between the bottom portion 122 of the cap member 101 and the valve seat member 109 . The orifice 175 is arranged on the upstream side of the flow during the extension stroke when the sub-valve 181 of the second passage 182 opens. As a result, the orifice 175 restricts the flow of oil from the lower chamber 20 into the cap chamber 146 and into the upper chamber 19 by opening the sub-valve 171 during the contraction stroke. As a result, the differential pressure between the cap chamber 146 and the lower chamber 20 becomes small, and the sub-valve 181 in the closed state, which receives back pressure from the lower chamber 20, receives the same pressure as the lower chamber 20 from the cap chamber 146. , the back pressure (differential pressure) received is suppressed. Therefore, durability of the sub-valve 181 can be improved.

In addition, the first passage portions 151 and 152 have the upstream end and the downstream end of the flow of the hydraulic fluid, which is the working fluid, deviated in the radial direction of the valve seat member 109 . The downstream end of the flow of oil in the second passage portion 152 is arranged radially inward of the valve seat member 109 relative to the upstream end, or the downstream end of the oil flow of the second passage portion 152 is arranged radially inward of the valve seat member 109 relative to the upstream end. It can be placed inside. Therefore, for example, both the diameter of the valve seat portion 139 on which the sub-valve 181 of the valve seat member 109 is seated and the diameter of the valve seat portion 135 on which the sub-valve 171 is seated can be increased. As a result, the valve rigidity of the sub-valve 181 on the extension side and the sub-valve 171 on the compression side can be reduced, and in both the extension and compression strokes, the damping force characteristic of the valve is generated from the region where the piston speed is low. It is possible to expand the tuning adjustment range of the damping force characteristics.

In addition, since the expansion-side first passage portion 151 and the contraction-side second passage portion 152 provided in the valve seat member 109 are independent, the passage area of the orifice 175 is increased, and the contraction-side passage hole 143 and Separate characteristics can be obtained by individually setting the passage hole 141 on the extension side to a flow area equal to or smaller than the orifice 175 .

Further, since the piston rod 21 is inserted into the piston 18, the cap member 101 and the valve seat member 109, the piston 18, the cap member 101 and the valve seat member 109 can be arranged compactly.

Since the orifice 175 is formed by notching the disk 82 of the extension-side first damping force generating mechanism 41 that contacts the piston 18, the orifice 175 can be easily formed.

Since each of the second passages 172, 182 is partially formed by notching the piston rod 21, the second passages 172, 182 can be easily formed.

Since the differential pressure between the cap chamber 146 and the lower chamber 20 does not increase during both the expansion and contraction strokes, the cap member 101 can be made of a pressed thin plate. Therefore, it is advantageous in manufacturability and weight reduction.

Since it has a spring member 105 that applies a preload to the disk 107 and a spring member 112 that applies a preload to the disk 110, the damping force can be adjusted by changing the preload of each of these spring members 105 and 112. can do.

[Second embodiment]
Next, the second embodiment will be described mainly based on FIG. 5, focusing on the differences from the first embodiment. Parts common to those of the first embodiment are denoted by the same designations and the same reference numerals.

As shown in FIG. 5, in the shock absorber 1A of the second embodiment, the spring member 105 and the disk 104 of the first embodiment that apply a preload to the disk 107 and the spring member 112 that applies a preload to the disk 110 are used. lost. The discs 103 and 106 are brought into contact with each other, and the discs 111 and 113 are brought into contact with each other.

Therefore, the shock absorber 1A of the second embodiment has a second damping force generating mechanism 173A that differs from the second damping force generating mechanism 173 of the first embodiment in that the spring member 105 and the disk 104 are not provided. It has a second damping force generating mechanism 183A which differs from the second damping force generating mechanism 183 of the first embodiment in that the spring member 112 is not provided. In the second damping force generating mechanism 173A, only the disk 107 constitutes the sub-valve on the compression side, and in the second damping force generating mechanism 183A, only the disk 110 constitutes the sub-valve on the extension side. .

In the second embodiment as described above, since there is no component that applies a preload to the discs 107, 110, the discs 107, 110 are more easily opened. Therefore, it is possible to generate a damping force with valve characteristics from a lower piston speed.

[Third Embodiment]
Next, the second embodiment will be described mainly based on FIGS. 6 and 7, focusing on differences from the first embodiment. Parts common to those of the first embodiment are denoted by the same designations and the same reference numerals.

As shown in FIG. 6, the shock absorber 1B of the third embodiment uses a piston rod 21B that is partially different from the piston rod 21 of the first embodiment. The piston rod 21B has a mounting shaft portion 28B that is partially different from the mounting shaft portion 28. The mounting shaft portion 28B is positioned on the main shaft portion 27 side with respect to the passage cutout portion 30 in the axial direction of the piston rod 21B. A passage cutout portion 30B is formed that differs in that it is displaced from the

Further, in the shock absorber 1B of the third embodiment, a piston 18B that is partially different from the piston 18 of the first embodiment is used. The piston 18B has a piston body 36B that is partially different from the piston body 36. As shown in FIG. The piston body 36B has an insertion hole 44B formed in the center in the radial direction, which is different from the insertion hole 44. A small diameter hole portion 45B similar to the small diameter hole portion 45B is formed on the inner seat portion 47 side in the axial direction and a large diameter hole. A large-diameter hole portion 46B similar to the portion 46 is provided on the inner seat portion 49 side in the axial direction. The piston 18B is attached to the piston rod 21B so that the large-diameter hole portion 46B is located on the shaft step portion 29 side.

In addition, in the shock absorber 1B of the third embodiment, as shown in FIG. 7, a disk 113, a spring member 112, and a disk 111 are placed between the annular member 69 and the disk 68 in order from the annular member 69 side. , disk 110, valve seat member 109 provided with O-ring 108, disk 107, disk 106, spring member 105, disk 103, disk 102, and cap member 101 are attached to piston rod 21B. A shaft portion 28B is fitted inside each of them. At this time, the valve seat member 109 is oriented such that the small-diameter hole portion 136, the inner seat portion 138, and the valve seat portion 139 are positioned on the shaft step portion 29 side. Also, the cap member 101 is oriented so that the cylindrical portion 124 is located on the shaft step portion 29 side, and the bottom portion 122 of the cap member 101 contacts the disk 68 .

6, on the opposite side of the disk 89 to the piston 18B, the disk 201 and the annular member 114 are fitted with the mounting shaft portion 28B of the piston rod 21B in order from the disk 89 side. are provided together. The disk 201 is a component similar to the disk 68 and has an outer diameter smaller than the outer diameter of the main valve 91 and larger than the outer diameter of the annular member 114 . Disk 201 is thinner and less rigid than annular member 114 .

Therefore, the valve seat member 109 is arranged in the upper chamber 19 which is one of the upper chamber 19 and the lower chamber 20 , and the valve seat portion 139 is arranged facing the upper chamber 19 . A valve seat member 109 provided with an O-ring 108 separates the cap chamber 146 and the upper chamber 19 and is provided facing both the cap chamber 146 and the upper chamber 19 . The second passage portions 152 inside the plurality of passage holes 143 and the annular groove 144 always communicate with the upper chamber 19 .

Further, in the shock absorber 1B of the third embodiment, instead of the plurality of discs 62, a disc 82 having a notch 90 is provided between the piston 18B and the disc 63. In place of the disks 82 and 83, a plurality of disks 62 without notches are provided. The notch 90 of the disk 82 allows passages in the plurality of passage holes 39 on the contraction side and in the annular groove 56 to be divided into passages in the passage notch 30B of the piston rod 21B, passages in the large diameter hole 46B of the piston 18B and It always communicates with the passage in the large-diameter hole portion 137 of the valve seat member 109 .

A cap chamber 146 formed between the cap member 101, the O-ring 108, and the valve seat member 109 passes through the passage in the cutout portion 30B of the piston rod 21B via the passage in the cutout portion 153 of the disc 103, the valve It always communicates with the passage in the large-diameter hole portion 137 of the seat member 109 and the passage in the large-diameter hole portion 46B of the piston 18B. Therefore, the cap chamber 146 includes a passage in the notch 153 of the disc 103, a passage in the passage notch 30B of the piston rod 21B, a passage in the large diameter hole 137 of the valve seat member 109, and a large diameter hole of the piston 18B. It is in constant communication with the lower chamber 20 via passages in the portion 46B, passages in the cutout portion 90 of the disc 82, and passages in the annular groove 56 and the plurality of passage holes 39 of the piston 18B.

In the third embodiment, the sub-valve 171 is separated from the valve seat portion 135 in the cap chamber 146 so that the second passage portion 152 and the second passage portion 152 in the plurality of passage holes 143 and the annular groove 144 of the valve seat member 109 are separated. It communicates with the cap chamber 146 , and communicates the upper chamber 19 with the lower chamber 20 . The second passage portion 152 of the valve seat member 109, the passage between the sub-valve 171 and the valve seat portion 135 appearing when the valve is opened, the cap chamber 146, the passage in the notch portion 153 of the disc 103, and the piston rod 21B. The passage in the passage notch 30B, the passage in the large diameter hole 137 of the valve seat member 109, the passage in the large diameter hole 46B of the piston 18B, the passage in the notch 90 of the disc 82, and the ring of the piston 18B. When the piston 18B moves toward the upper chamber 19 side, oil flows from the upper chamber 19 on the upstream side in the cylinder 2 to the lower chamber 20 on the downstream side. It constitutes the extension-side second passage 172 . A notch 90 in the disc 82 forms an orifice 175 in the second passage 172 and is located downstream of the sub-valve 171 for the flow of working fluid when the sub-valve 171 opens.

A sub-valve 171, a valve seat portion 135, discs 102 and 103, and a cap member 101 are provided in a second passage 172 on the extension side to open and close the second passage 172. A second damping force generating mechanism 173 on the elongation side that suppresses the flow of oil to 20 and generates a damping force is configured. The sub-valve 171 that constitutes the extension-side second damping force generating mechanism 173 is an extension-side sub-valve.

The extension-side second passage 172, which communicates between the upper chamber 19 and the lower chamber 20, is parallel to the extension-side first passage 92, which likewise communicates between the upper chamber 19 and the lower chamber 20. A first damping force generating mechanism 41 and a second damping force generating mechanism 173 are provided in the first passage 92 and the second passage 172, respectively. Therefore, both the first damping force generating mechanism 41 and the second damping force generating mechanism 173 on the rebound side are arranged in parallel.

In the third embodiment, the sub-valve 181 is provided in the upper chamber 19 , and is separated from the valve seat portion 139 to allow the passage holes 141 of the valve seat member 109 and the annular groove 142 to flow through the sub-valve 181 . The first passage portion 151 and the upper chamber 19 are communicated, and the lower chamber 20 is communicated with the upper chamber 19 . Passages in the plurality of passage holes 39 and the annular groove 56 of the piston 18B, passages in the notch 90 of the disc 82, passages in the passage notch 30B of the piston rod 21B, and the large diameter hole 46B of the piston 18B. and the passage in the large diameter hole portion 137 of the valve seat member 109, the passage in the cutout portion 153 of the disk 103, the cap chamber 146, the plurality of passage holes 141 of the valve seat member 109 and the annular groove 142. and the passage between the sub-valve 181 and the valve seat portion 139 appearing when the valve is opened are moved from the lower chamber 20, which is upstream in the cylinder 2 by the movement of the piston 18B toward the lower chamber 20 side. A contraction-side second passage 182 through which oil flows into the upper chamber 19 on the downstream side is formed. A notch 90 in the disc 82 forms an orifice 175 in the second passage 182 and is positioned upstream of the sub-valve 181 for the flow of working fluid when the sub-valve 181 opens.

A sub-valve 181, a valve seat portion 139, a disc 113, and an annular member 69 are provided in a second passage 182 on the contraction side to open and close the second passage 182, and from the second passage 182 to the upper chamber 19. A second damping force generating mechanism 183 on the compression side that generates a damping force by suppressing the flow of the oil liquid. The sub-valve 181 that constitutes the compression-side second damping force generating mechanism 183 is a compression-side sub-valve.

The second passage 182 on the contraction side that allows communication between the upper chamber 19 and the lower chamber 20 is composed of the first passage 72 that is the passage on the contraction side that similarly allows communication between the upper chamber 19 and the lower chamber 20, and the lower chamber 20 side. The first damping force generating mechanism 42 is connected to the first passage 72 and the second damping force is connected to the second passage 182 in the parallel portions except for passages in the annular groove 56 and the plurality of passage holes 39 . A generating mechanism 183 is provided respectively. Therefore, both the first damping force generating mechanism 42 and the second damping force generating mechanism 183 on the compression side are arranged in parallel.

Also in the third embodiment, the second damping force generating mechanisms 173 and 183 are provided with the valve seat member 109 and one side of the valve seat member passage portion 150 which is the portion provided in the valve seat member 109 of the second passages 172 and 182 . A sub-valve 181 provided in the sub-valve 171 provided on the other side of the valve seat member passage portion 150, and a bottomed cylindrical cap member 101 provided between the piston 18 and the valve seat member 109 in the second passages 172, 182 and has. The valve seat member 109 is provided inside the cap member 101 , the sub-valve 181 is provided on the upper chamber 19 side of the valve seat member 109 , and the sub-valve 171 is provided between the bottom portion 122 of the cap member 101 and the valve seat member 109 . is provided in the cap chamber 146 of the.

Of the first damping force generating mechanism 41 and the second damping force generating mechanism 173, both of which are on the rebound side, the main valve 91 of the first damping force generating mechanism 41 has higher rigidity than the sub valve 171 of the second damping force generating mechanism 173. High valve opening pressure. Therefore, in the extension stroke, the second damping force generating mechanism 173 is opened while the first damping force generating mechanism 41 is closed in an extremely low speed region in which the piston speed is lower than a predetermined value. Also, in the normal speed range where the piston speed is equal to or higher than this predetermined value, both the first damping force generating mechanism 41 and the second damping force generating mechanism 173 are opened. The sub-valve 171 is a very low speed valve that opens in a region where the piston speed is very low to generate a damping force.

That is, in the extension stroke, as the piston 18 moves toward the upper chamber 19, the pressure in the upper chamber 19 increases and the pressure in the lower chamber 20 decreases. In a very low speed region (v1 or more and less than v2), which is a region of higher speed than the first predetermined value v1 in which the valve opens and is lower than the second predetermined value v2 that is higher than the first predetermined value v1, the first damping force The second damping force generating mechanism 173 opens while the generating mechanism 41 is closed.

That is, the sub-valve 171 is separated from the valve seat portion 135, and the upper chamber 19 and the lower chamber 20 are communicated with each other through the second passage 172 on the expansion side. Therefore, the oil in the upper chamber 19 flows through the second passage portion 152 in the plurality of passage holes 143 and the annular groove 144 of the valve seat member 109, the passage between the sub-valve 171 and the valve seat portion 135, and the cap chamber 146. , a passage in the cutout portion 153 of the disc 103, a passage in the cutout portion 30B of the piston rod 21B, a passage in the large diameter hole portion 137 of the valve seat member 109, and a passage in the large diameter hole portion 46B of the piston 18B. , and flows into the lower chamber 20 via the orifice 175 and passages in the annular groove 56 and the plurality of passage holes 39 of the piston 18B. As a result, a damping force with valve characteristics (a characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in an extremely low speed region (v1 or more and less than v2) where the piston speed is lower than the second predetermined value v2.

Further, in the extension stroke, in the normal speed range where the piston speed is equal to or higher than the second predetermined value v2, the first damping force generating mechanism 41 opens while the second damping force generating mechanism 173 remains open. That is, the sub-valve 171 is separated from the valve seat portion 135, and oil flows from the upper chamber 19 to the lower chamber 20 through the second passage 172 on the extension side. The orifice 175 provided on the downstream side restricts the flow of the oil liquid, so that the pressure applied to the main valve 91 provided in the first passage 92 increases and the differential pressure increases, and the main valve 91 moves to the valve seat. Leaving the portion 48, oil flows from the upper chamber 19 to the lower chamber 20 through the first passage 92 on the extension side. Therefore, the oil in the upper chamber 19 flows into the lower chamber 20 through passages in the plurality of passage holes 38 and the annular groove 55 and passages between the main valve 91 and the valve seat portion 48 . As a result, even in the normal speed region where the piston speed is equal to or higher than the second predetermined value, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) can be obtained. The increase rate of the rebound damping force with respect to the increase in the piston speed in the normal speed region is lower than the increase rate of the rebound damping force with respect to the increase in the piston speed in the extremely low speed region. In other words, the slope of the increase rate of the damping force on the extension side with respect to the increase in the piston speed in the normal speed region can be flatter than in the extremely low speed region.

Here, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the second predetermined value v2, the differential pressure between the upper chamber 19 and the lower chamber 20 is in the low speed region equal to or higher than the first predetermined value v1 and less than the second predetermined value v2. However, since the first passage 92 is not throttled by an orifice, the oil can flow through the first passage 92 at a large flow rate by opening the main valve 91 . By this and by narrowing the second passage 172 with the orifice 175, deformation of the sub-valve 171 can be suppressed.

Also, at this time, pressures in opposite directions are applied to the closed sub-valve 181 from the upper chamber 19 and the cap chamber 146 . Even if the differential pressure between the upper chamber 19 and the lower chamber 20 increases, the sub-valve 171 is opened so that the cap chamber 146 and the upper chamber 19 are communicated with each other. Since the orifice 175 is formed in the cap chamber 146, the pressure in the cap chamber 146 does not drop abruptly, and an increase in the pressure difference with the upper chamber 19 is suppressed. Therefore, it is possible to suppress an increase in the pressure difference between the upper chamber 19 and the cap chamber 146 that the sub-valve 181 in the closed state receives, and prevent a large back pressure from being applied to the sub-valve 181 from the upper chamber 19 side toward the cap chamber 146 side. can be suppressed.

The shock absorber 1B has a first passage 92 and a second passage 172 parallel to each other, and a main valve 91 and a sub-valve 171 are arranged in parallel. there is Also, the orifice 175 is connected in series with the sub-valve 171 .

As described above, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the second predetermined value v2, the main valve 91 opens to allow a large amount of oil to flow through the first passage 92. . As a result, the flow rate through the passage between the sub-valve 171 and the valve seat portion 135 is reduced. Therefore, the valve rigidity of the sub-valve 171 can be lowered. Therefore, for example, when the piston speed is in the normal speed region (v2 or higher), it is possible to reduce the increase rate of the damping force with respect to the increase in the piston speed. In other words, the slope of the rate of increase of the damping force on the extension side with respect to the increase in piston speed in the normal speed region (v2 or more) can be made flatter than in the extremely low speed region (less than v2). Thereby, the degree of freedom in design can be expanded.

Of the first damping force generating mechanism 42 and the second damping force generating mechanism 183 on the compression side, the main valve 71 of the first damping force generating mechanism 42 has higher rigidity than the sub valve 181 of the second damping force generating mechanism 183. High valve opening pressure. Therefore, in the compression stroke, when the piston speed is lower than the predetermined value, the second damping force generating mechanism 183 is opened while the first damping force generating mechanism 42 is closed, and the piston speed is reduced to this predetermined value. In the above normal speed range, both the first damping force generating mechanism 42 and the second damping force generating mechanism 183 are opened. The sub-valve 181 is a very low speed valve that opens in a region where the piston speed is very low to generate a damping force.

That is, in the compression stroke, as the piston 18 moves toward the lower chamber 20, the pressure in the lower chamber 20 increases and the pressure in the upper chamber 19 decreases. In a region where the speed is higher than the third predetermined value in which the valve opens, and in a very low speed region where the speed is lower than the fourth predetermined value that is higher than the third predetermined value, the first damping force generating mechanism 42 is closed. The second damping force generating mechanism 183 opens.

That is, the sub-valve 181 is separated from the valve seat portion 139, and the lower chamber 20 and the upper chamber 19 are communicated with each other through the second passage 182 on the contraction side. Therefore, the oil in the lower chamber 20 flows through passages in the plurality of passage holes 39 and the annular groove 56 of the piston 18B, the orifice 175, passages in the passage cutout 30B of the piston rod 21B, and the large diameter hole of the piston 18B. passages in the portion 46B, passages in the large-diameter hole portion 137 of the valve seat member 109, passages in the notch portion 153 of the disk 103, a cap chamber 146, a plurality of passage holes 141 and annular grooves 142. It flows into the upper chamber 19 via the 1 passage portion 151 and the passage between the sub-valve 181 and the valve seat portion 139 . As a result, even in an extremely low speed region in which the piston speed is lower than the fourth predetermined value, a damping force with a valve characteristic (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained.

In the compression stroke, the first damping force generating mechanism 42 opens while the second damping force generating mechanism 183 remains open in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value. In other words, the sub-valve 181 is separated from the valve seat portion 139, and oil flows from the lower chamber 20 to the upper chamber 19 through the second passage 182 on the contraction side. Since the flow rate of the oil is restricted at , the differential pressure generated in the main valve 71 provided in the first passage 72 increases, the main valve 71 is separated from the valve seat portion 50, and the contraction-side first 1 passage 72 allows oil to flow from the lower chamber 20 to the upper chamber 19 . Therefore, the oil in the lower chamber 20 flows through passages in the plurality of passage holes 39 and the annular groove 56 and passages between the main valve 71 and the valve seat portion 50 . As a result, even in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) can be obtained. The increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region is lower than the increase rate of the compression damping force with respect to the increase in piston speed in the extremely low speed region. In other words, the slope of the increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region can be flatter than in the extremely low speed region.

In the compression stroke, the differential pressure between the lower chamber 20 and the upper chamber 19 is greater in the normal speed region where the piston speed is the fourth predetermined value or higher than in the low speed region. By opening the main valve 71 , the oil can flow at a large flow rate through the first passage 72 . As a result, the flow rate through the sub-valve 181 is reduced, so that the valve rigidity of the sub-valve 181 can be reduced. Therefore, the damping force can be reduced when the piston speed is in the normal speed region, and the degree of freedom in design can be expanded.

At this time (when the piston speed is high), although the differential pressure between the lower chamber 20 and the upper chamber 19 increases, the second passage 182 is constricted by the orifice 175 so that the lower chamber 20 is communicated with the orifice 175. Since the pressure in the cap chamber 146 becomes the pressure between the lower chamber 20 and the upper chamber 19, it is possible to suppress the differential pressure with the upper chamber 19 from becoming too large. This and the opening of the main valve 71 allows a large amount of oil to flow through the first passage 72 , thereby suppressing deformation of the sub-valve 181 .

At this time, pressures are applied to the closed sub-valve 171 from the upper chamber 19 and the cap chamber 146 in opposite directions. and the cap chamber 146 are communicated with each other by opening the sub-valve 181, and since an orifice 175 is provided between the cap chamber 146 and the lower chamber 20 on the upstream side of the sub-valve 171, the inside of the cap chamber 146 It is possible to suppress the pressure from rising too much. Therefore, the differential pressure generated between the upstream and downstream surfaces of the sub-valve 171 is small, and the application of a large back pressure from the cap chamber 146 side to the upper chamber 19 side to the sub-valve 171 can be suppressed.

In the shock absorber 1 described above, the flow path for flowing oil from the lower chamber 20 to the upper chamber 19 in the compression stroke is provided in parallel with the first passage 72 and the second passage 182, and the main valve 71 and the sub valve 181 are arranged in parallel. are provided. Also, the orifice 175 is connected in series with the sub-valve 181 in the second passage 182 .

In the extension stroke, the differential pressure between the upper chamber 19 and the lower chamber 20 becomes larger in the normal speed region where the piston speed is the second predetermined value or more than in the low speed region. , and the pressure drop in the cap chamber 146 can be suppressed by the orifice 175 formed downstream of the cap chamber 146 , so deformation of the sub-valve 181 due to back pressure can be suppressed. In the compression stroke, the differential pressure between the lower chamber 20 and the upper chamber 19 is greater in the normal speed region where the piston speed is the fourth predetermined value or higher than in the low speed region. Deformation of the sub-valve 181 can be suppressed by allowing the fluid to flow and restricting the upstream side of the second passage 182 from the sub-valve 181 by the orifice 175 . Therefore, durability of the sub-valve 181 can be improved.

In the extension stroke, the differential pressure between the upper chamber 19 and the lower chamber 20 is greater in the normal speed region where the piston speed is equal to or higher than the second predetermined value, but the oil is allowed to flow through the first passage 92 at a large flow rate. and by narrowing the second passage 172 with the orifice 175, the deformation of the sub-valve 171 can be suppressed. In the compression stroke, the pressure difference between the lower chamber 20 and the upper chamber 19 is greater in the normal speed region where the piston speed is the fourth predetermined value or higher than in the low speed region. The cap chamber 146 communicates with the chamber 146 , and the orifice 175 provided between the cap chamber 146 and the lower chamber 20 restricts the flow of oil from the lower chamber 20 . Therefore, the differential pressure between the upper chamber 19 and the cap chamber 146 is small, and deformation due to the back pressure of the sub-valve 171 can be suppressed. Therefore, the durability of the sub-valve 171 can be improved.

Although the above-described first to third embodiments show examples in which the present invention is applied to a monotube hydraulic shock absorber, the present invention is not limited to this, and the cylinder is composed of an outer cylinder and an inner cylinder. It may be used for a double-cylinder hydraulic shock absorber that forms a reservoir chamber between itself and the cylinder, and can be used for any shock absorber including a pressure control valve that uses a packing valve having a structure in which a disc is provided with a seal member. .

A first aspect of the above-described embodiments includes a cylinder in which a working fluid is enclosed, a piston slidably provided in the cylinder and partitioning the inside of the cylinder into two chambers, and a piston connected to the piston. a piston rod that extends outside the cylinder, a first passage and a second passage through which the working fluid flows from the chamber on the upstream side in the cylinder to the chamber on the downstream side due to the movement of the piston; A first damping force generating mechanism that is provided in the first passage formed in the piston and generates a damping force; a second damping force generating mechanism provided in the second passage parallel to the first passage to generate a damping force, the second damping force generating mechanism being the valve seat member of the second passage; A first sub-valve provided on one side and a second sub-valve provided on the other side of a valve seat member passage portion provided in the second passage, and a bottomed cylindrical shape provided between the piston and the valve seat member in the second passage wherein the valve seat member is in the cap member, the first sub-valve is in the one chamber, and the second sub-valve is a cap between the bottom of the cap member and the valve seat member The second passage is provided with an orifice on the upstream side or the downstream side of the flow of the working fluid when the first sub-valve is opened. The second damping force generating mechanism is opened while the damping force generating mechanism is closed, and both the first damping force generating mechanism and the second damping force generating mechanism are open in a speed range in which the piston speed is higher than the low speed. In the valve seat member passage portion, the upstream end and the downstream end of the working fluid flow are offset in the radial direction of the valve seat member. This makes it possible to improve the durability of the valve.

According to a second aspect, in the first aspect, the valve seat member passage portion is arranged such that the downstream end of the flow of the working fluid is arranged radially inward of the valve seat member relative to the upstream end.

In a third aspect based on the second aspect, the valve seat member passage portion has a first passage portion that is opened and closed by the first sub-valve and a second passage portion that is opened and closed by the second sub-valve, and The first passage portion has an end on the first sub-valve side disposed radially inward of the valve seat member with respect to an end portion on the cap chamber side, and the second passage portion has an end portion on the side of the second sub-valve. The end portion is arranged radially inward of the valve seat member relative to the end portion on the one chamber side.

In a fourth aspect based on the third aspect, the first sub-valve is seated on the first sub-valve side of the valve seat member outside the first passage portion in the radial direction of the valve seat member. A second seat portion is formed on the second sub-valve side of the valve seat member. is formed, and the first sheet portion and the second sheet portion have the same diameter.

1, 1A, 1B shock absorber 2 cylinder 18, 18B piston 19 upper chamber 20 lower chamber 21, 21B piston rod 41, 42 first damping force generating mechanism 72, 92 first passage 101 cap member 109 valve seat member 122 bottom 135 valve Seat (Second seat)
139 valve seat (first seat)
146 cap chamber 151 first passage portion 152 second passage portion 171 sub-valve (second sub-valve)
172, 182 Second passage 173, 173B Second damping force generating mechanism 175 Orifice 181 Sub valve (first sub valve)
183, 183B Second damping force generating mechanism

Claims (4)

a cylinder in which the working fluid is sealed;
a piston slidably provided in the cylinder and partitioning the inside of the cylinder into two chambers;
a piston rod connected to the piston and extending outside the cylinder;
a first passage and a second passage through which the working fluid flows from the chamber on the upstream side in the cylinder to the chamber on the downstream side by movement of the piston;
a first damping force generating mechanism provided in the first passage formed in the piston and generating a damping force;
A second valve seat member provided in an annular valve seat member arranged in one of the two chambers, and provided in the parallel second passage branching from at least a part of the first passage to generate a damping force. a damping force generating mechanism;
has
The second damping force generating mechanism is
a first sub-valve provided on one side of a valve seat member passage portion provided in the valve seat member of the second passage and a second sub-valve provided on the other side;
a bottomed cylindrical cap member provided between the piston and the valve seat member in the second passage;
with
The valve seat member is provided in the cap member, the first sub-valve is provided in the one chamber, and the second sub-valve is provided in the cap chamber between the bottom of the cap member and the valve seat member,
The second passage is provided with an orifice formed by a notch provided in a disk on the upstream side or the downstream side of the flow of the working fluid when the first sub-valve is opened,
In a region where the piston speed is low, the first damping force generating mechanism is closed and the second damping force generating mechanism is opened,
In a speed region where the piston speed is higher than the low speed, both the first damping force generating mechanism and the second damping force generating mechanism are opened,
A shock absorber, wherein an upstream end and a downstream end of the valve seat member passage portion for the flow of the working fluid are shifted in a radial direction of the valve seat member. 2. The shock absorber according to claim 1, wherein the valve seat member passage portion has a downstream end for the flow of the working fluid arranged radially inward of the valve seat member relative to an upstream end. The valve seat member passage portion has a first passage portion that is opened and closed by the first sub-valve and a second passage portion that is opened and closed by the second sub-valve,
The first passage portion has an end portion on the first sub-valve side disposed radially inward of the valve seat member relative to an end portion on the cap chamber side,
3. The second passage portion according to claim 2, wherein the end portion on the side of the second sub-valve is arranged inside the end portion on the side of the one chamber in the radial direction of the valve seat member. buffer. A first seat portion on which the first sub-valve is seated is formed outside the first passage portion in the radial direction of the valve seat member on the first sub-valve side of the valve seat member,
A second seat portion on which the second sub-valve is seated is formed outside the second passage portion in the radial direction of the valve seat member on the second sub-valve side of the valve seat member,
4. The shock absorber according to claim 3, wherein said first seat portion and said second seat portion have the same diameter.

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