JP2013007471A - Buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a buffer for generating a desired damping force even when a member is used for inhibiting a piston rod from being fully stretched.SOLUTION: The buffer includes: an elastic member 32 for inhibiting the piston rod 16 from being fully stretched; a first passage 60 in which a movement of a piston 11 causes working fluid to flow out from one chamber 12 in the cylinder 10; a damping valve 104 that is disposed in the first passage 60 and regulates a flow of the working fluid generated by a slide of the piston 11 to generate damping force; a back pressure chamber 94 for causing an internal pressure to act on the damping valve 104 in a valve closing direction; and a second passage 140 for introducing the working fluid to the back pressure chamber 94 from the one chamber 12 in the cylinder 10. The second passage 140 has a variable orifice 142 whose area is adjusted by the elastic member 32 when the piston rod 16 moves in a stretching direction.

Description

  The present invention relates to a shock absorber.

  In some shock absorbers, when the piston rod extends to the vicinity of the stroke end, the internal spring contracts to suppress the collision of the piston (for example, see Patent Document 1).

JP 2006-177531 A

  By the way, when a member that suppresses the expansion and contraction of the piston rod, for example, a spring as shown in Patent Document 1, is used in the shock absorber, when the spring is contracted, the spring constant increases with respect to the natural state. I noticed that the damping performance of the vehicle body may be insufficient, that is, the damping force of the shock absorber may be insufficient.

  Accordingly, an object of the present invention is to provide a shock absorber that generates a desired damping force even when a member that suppresses the extension of the piston rod is used.

  In order to achieve the above object, the present invention provides an elastic member provided in a cylinder and elastically acting on the piston rod to restrain the piston rod from extending and contracting, and one of the cylinders in the cylinder by the movement of the piston. A first passage through which the working fluid flows out of the chamber; a damping valve provided in the first passage for regulating the flow of the working fluid generated by sliding of the piston to generate a damping force; and the damping valve closed. A back pressure chamber for applying an internal pressure in the valve direction; and a second passage for introducing the working fluid into the back pressure chamber from one of the chambers in the cylinder. It has a variable orifice whose area is adjusted by the elastic member when moved in the extending direction.

  According to the present invention, a desired damping force can be generated even when a member that suppresses the expansion and contraction of the piston rod is used.

It is sectional drawing which shows the buffer of 1st Embodiment which concerns on this invention. It is sectional drawing which shows the principal part of the buffer of 1st Embodiment which concerns on this invention. It is sectional drawing which shows the variable orifice periphery at the time of rebound spring contraction of the buffer of 1st Embodiment which concerns on this invention. It is a characteristic diagram which shows the relationship between the stroke position in a shock absorber, and a spring reaction force. 1 is a hydraulic circuit diagram of a shock absorber according to a first embodiment of the present invention. It is a characteristic line figure which shows the relationship between piston speed and damping force, such as a buffer of 1st Embodiment concerning this invention. It is sectional drawing which shows the principal part of the buffer of 2nd Embodiment which concerns on this invention. It is sectional drawing which shows the variable orifice periphery at the time of rebound spring contraction of the buffer of 2nd Embodiment which concerns on this invention. It is a hydraulic-circuit figure of the buffer of 2nd Embodiment which concerns on this invention. It is a characteristic diagram which shows the relationship between the piston speed and damping force of the buffer of 2nd Embodiment which concerns on this invention. It is sectional drawing which shows the principal part of the buffer of 3rd Embodiment which concerns on this invention. It is sectional drawing which shows the variable orifice periphery at the time of rebound spring contraction of the buffer of 3rd Embodiment which concerns on this invention. It is a characteristic diagram which shows the relationship between the piston speed and damping force of the buffer of 3rd Embodiment which concerns on this invention. It is a hydraulic circuit figure of the buffer of a 3rd embodiment concerning the present invention.

  Hereinafter, each embodiment according to the present invention will be described with reference to the drawings.

“First Embodiment”
1st Embodiment which concerns on this invention is described based on FIGS. In the following description, in order to help understanding, the lower side of the figure is defined as one side and the upper side of the figure is defined as the other side.

  As shown in FIG. 1, the shock absorber according to the first embodiment is a so-called monotube hydraulic shock absorber, and has a bottomed cylindrical cylinder 10 in which an oil liquid as a working fluid is sealed. A piston 11 is slidably fitted in the cylinder 10, and the inside of the cylinder 10 is partitioned into two chambers, an upper chamber 12 and a lower chamber 13, by the piston 11. The piston 11 includes a piston main body 14 and an annular sliding member 15 attached to the outer peripheral surface thereof.

  The piston 11 is connected to one end portion of the piston rod 16, and the other end side of the piston rod 16 is inserted into a rod guide 17 and an oil seal 18 mounted on the opening side of the cylinder 10, and the outside of the cylinder 10. It is extended to. The opening side of the cylinder 10 is crimped inward, thereby locking the oil seal 18 and the rod guide 17.

  The piston rod 16 is formed with an attachment shaft portion 20 to which the piston 11 is attached on the distal end side of insertion into the cylinder 10, and the other portion is a main shaft portion 21 having a larger diameter than the attachment shaft portion 20. . A male screw 19 is formed on the mounting shaft portion 20 on the outer peripheral side opposite to the main shaft portion 21. A locking groove 22 is formed at a position in the vicinity of the mounting shaft portion 20 of the main shaft portion 21, and an inner peripheral portion of a retainer 23 that extends radially outward from the main shaft portion 21 is added to the locking groove 22. It is fixed by tightening.

  An annular spring receiver 24 is disposed opposite to the piston 11 of the retainer 23, and an auxiliary spring 26 made of a coil spring is disposed opposite to the retainer 23 of the spring receiver 24. An annular intermediate stopper 28 is disposed opposite to the spring receiver 24 of the auxiliary spring 26, and a rebound spring main body 29 formed of a coil spring is disposed opposite to the auxiliary spring 26 of the intermediate stopper 28. . Further, an annular spring receiver 30 is disposed opposite to the intermediate stopper 28 of the rebound spring body 29, and a buffer body 31 made of an annular elastic material opposite to the rebound spring body 29 of the spring receiver 30. Is provided. The spring receiver 24, the auxiliary spring 26, the intermediate stopper 28, the rebound spring main body 29, the spring receiver 30, and the buffer body 31 are provided so as to be movable in the axial direction with respect to the piston rod 16.

  Here, when the piston rod 16 moves in a direction protruding from the cylinder 10, the spring receiver 24, the auxiliary spring 26, the intermediate stopper 28, the rebound spring main body 29, the spring receiver 30, and the buffer body together with the retainer 23 fixed to the piston rod 16. 31 moves to the rod guide 17 side, and the buffer 31 comes into contact with the rod guide 17 at a predetermined position. When the piston rod 16 further moves in the protruding direction, the buffer body 31 and the spring receiver 30 are stopped with respect to the cylinder 10, and as a result, the moving retainer 23 and the spring receiver 30 come close to each other. As a result, the spring receiver 30 and the intermediate stopper 28 contract the rebound spring main body 29 therebetween, and the intermediate stopper 28 and the spring receiver 24 contract the auxiliary spring 26 therebetween. Become. In this way, the rebound spring main body 29 and the auxiliary spring 26 provided in the cylinder 10 act on the piston rod 16 elastically and suppress the expansion of the piston rod 16. The rebound spring (elastic member) 32 which suppresses the expansion | extension of this is comprised. In this way, the rebound spring 32 becomes the resistance of the piston rod 16 to extend completely, so that the lifting of the inner peripheral wheel during turning of the vehicle is suppressed and the roll amount of the vehicle body is suppressed. When the intermediate stopper 28 is moved to the retainer 23 side as much as possible, the intermediate stopper 28 comes into contact with a spring receiver 24 locked to the retainer 23 or comes into close contact with the auxiliary spring 26 and stops with respect to the piston rod 16.

  A partition 33 for defining the lower chamber 13 is slidably provided in the cylinder 10 on the bottom side of the cylinder 10 with respect to the piston 11. Oil is sealed in the upper chamber 12 and the lower chamber 13 in the cylinder 10, and a high-pressure gas (about 20 to 30 atm) is contained in the chamber 34 defined as the lower chamber 13 by the partition 33. It is enclosed.

  For example, one side of the shock absorber described above is supported by the vehicle body, and the wheel side is fixed to the other side of the shock absorber. Specifically, it is connected to the vehicle body side by a piston rod 16 and is connected to the wheel side by a mounting eye 36 attached to the bottom of the cylinder 10 opposite to the protruding side of the piston rod 16. At this time, a suspension spring (not shown) is interposed between the spring receiver 37 fixed to the protruding side of the piston rod 16 of the cylinder 10 and the vehicle body. In contrast to the above, the other side of the shock absorber may be supported by the vehicle body and the wheel side may be fixed to one side of the shock absorber.

  When the wheels vibrate as the vehicle travels, the positions of the cylinder 10 and the piston rod 16 change relatively with the vibrations, but the change is suppressed by the fluid resistance of the flow path formed in the piston 11. As will be described in detail below, the fluid resistance of the flow path formed in the piston 11 is made different depending on the speed and amplitude of vibration, and the ride comfort is improved by suppressing the vibration. Between the cylinder 10 and the piston rod 16, in addition to vibration generated by the wheels, inertial force and centrifugal force generated in the vehicle body as the vehicle travels also act. For example, a centrifugal force is generated in the vehicle body when the traveling direction is changed by a steering operation, and a force based on the centrifugal force acts between the cylinder 10 and the piston rod 16. As will be described below, the shock absorber according to the present embodiment has good characteristics with respect to vibration based on the force generated in the vehicle body as the vehicle travels, and high stability in vehicle travel is obtained.

  As shown in FIG. 2, the spring receiver 24 has a substantially cylindrical cylindrical portion 40 and an annular flange portion 41 protruding radially outward from one axial end side of the cylindrical portion 40. Yes. A plurality of grooves 43 extending in the axial direction are formed on the inner peripheral surface of the cylindrical portion 40 at intervals in the circumferential direction. In the spring receiver 24, the flange portion 41 is disposed on the retainer 23 side, and the main shaft portion 21 of the piston rod 16 is inserted into the inner peripheral side of the cylindrical portion 40. Thereby, the spring receiver 24 is slidably supported by the main shaft portion 21 of the piston rod 16. The spring receiver 24 abuts the retainer 23 at the flange portion 41 and the cylindrical portion 40, and abuts one end portion of the auxiliary spring 26 on the opposite side of the flange portion 41 from the retainer 23.

  The intermediate stopper 28 has a substantially cylindrical cylindrical portion 46 and an annular flange portion 47 that protrudes radially outward from the axial center position of the cylindrical portion 46. Further, on the inner peripheral surface of the cylindrical portion 46, an annular groove 48 is formed in an annular shape so as to be recessed radially outward at a central position in the axial direction. A seal ring 49 is disposed in the annular groove 48, and the main shaft portion 21 of the piston rod 16 is inserted into the cylindrical portion 46 of the intermediate stopper 28 and the inner peripheral side of the seal ring 49. Thus, the intermediate stopper 28 is slidably supported on the main shaft portion 21 of the piston rod 16. The intermediate stopper 28 causes the other end portion of the auxiliary spring 26 to abut one end surface of the flange portion 47 in the axial direction. The intermediate stopper 28 abuts one end portion of the rebound spring main body 29 against the other end surface of the flange portion 47 in the axial direction.

  Here, a locking groove 50 is formed at a predetermined intermediate position of the main shaft portion 21 of the piston rod 16, and the locking groove 50 moves the intermediate stopper 28 to the side opposite to the spring receiver 24. The stopper ring 51 to be controlled is locked.

  As shown in FIG. 1, the spring receiver 30 includes a tapered tubular portion 52 and an annular flange portion 53 that protrudes radially outward from the large diameter side of the tubular portion 52. The spring receiver 30 is disposed with the flange portion 53 opposite to the rebound spring main body 29, and the main shaft portion 21 of the piston rod 16 is inserted inside the cylindrical portion 52. Thereby, the spring receiver 30 is slidably supported by the main shaft portion 21 of the piston rod 16. The spring receiver 30 abuts the other end portion of the rebound spring main body 29 against the flange portion 53.

  As shown in FIG. 2, the upper chamber 12 and the lower chamber 13 are communicated with the piston main body 14, and the oil moves from the upper chamber 12 toward the lower chamber 13 during the movement of the piston 11 toward the upper chamber 12, that is, the extension stroke. A plurality of passages (first passages are shown in FIG. 2 because of the cross section in FIG. 2) 60 and the movement of the piston 11 to the lower chamber 13 side, that is, the contraction stroke, from the lower chamber 13 to the upper chamber 12. A plurality of passages 61 (only one place is shown in FIG. 2 because of the cross section) are provided. Half of these passages 60 are formed at an equal pitch in the circumferential direction with one passage 61 between them, and one side of the piston 11 in the axial direction (upper side in FIG. 1) has a diameter. The other side in the axial direction (the lower side in FIG. 1) is open radially inward on the outer side in the direction.

  A damping force generating mechanism 62 that generates a damping force is provided for the half of the passages 60. The damping force generation mechanism 62 is disposed on the lower chamber 13 side that is one end side of the piston 11 in the axial direction. The passage 60 constitutes an extension-side passage through which oil liquid passes when the piston 11 moves to the extension side where the piston rod 16 extends out of the cylinder 10, and a damping force generation mechanism provided for these passages. Reference numeral 62 denotes an extension-side damping force generation mechanism that generates a damping force by regulating the flow of the oil liquid in the extension-side passage 60.

  Further, the passages 61 constituting the remaining half are formed at an equal pitch in the circumferential direction with one passage 60 interposed therebetween, and the other side in the axial direction of the piston 11 (the lower side in FIG. 1). Is open radially outward and one side in the axial direction (upper side in FIG. 1) is open radially inward.

  A damping valve 63 that generates a damping force is provided in the remaining half of the passages 61. The damping valve 63 is arranged on the upper chamber 12 side in the axial direction, which is the other end side of the piston 11 in the axial direction. The passage 61 constitutes a contraction-side passage through which the oil liquid passes when the piston 11 moves to the contraction side where the piston rod 16 enters the cylinder 10, and a damping valve 63 provided for these passages includes: This is a contraction-side damping valve that restricts the flow of the oil liquid in the contraction-side passage 61 and generates a damping force.

  The piston main body 14 has a substantially disk shape, and an insertion hole 68 is formed in the center of the piston main body 14 so as to penetrate the mounting shaft portion 20 of the piston rod 16 described above.

  At the end of the piston body 14 on the lower chamber 13 side, a seat portion 70 constituting the damping force generating mechanism 62 is formed in an annular shape outside the position of one end opening of the extension-side passage 60. At the end of the piston main body 14 on the upper chamber 12 side, a seat portion 71 that forms the damping valve 63 is formed in an annular shape outside the position of one end opening of the passage 61 on the contraction side.

  In the piston main body 14, the side opposite to the insertion hole 68 of the seat part 70 has a stepped shape whose axial direction height is lower than that of the seat part 70, and the other end of the passage 61 on the contraction side is formed in this stepped part. Is open. Similarly, in the piston main body 14, the side opposite to the insertion hole 68 of the seat portion 71 has a stepped shape whose axial height is lower than that of the seat portion 71, and this stepped portion has an extended side. The other end of the passage 60 is open.

  The extension-side damping force generation mechanism 62 is a pressure control type valve mechanism, and in order from the axial upper chamber 12 side, that is, the piston 11 side, a plurality of disks 80, a damping valve body 81, and a valve regulating member 82. A seat member 83, a small-diameter valve main body 84, a large-diameter valve main body 85, and a valve restricting member 86.

  The sheet member 83 includes a perforated disk-shaped bottom 90 along the direction perpendicular to the axis, a cylindrical inner cylindrical portion 91 along the axial direction formed on the inner peripheral side of the bottom 90, and an outer peripheral side of the bottom 90. And a cylindrical outer cylindrical portion 92 formed along the axial direction. A plurality of through holes 93 penetrating in the axial direction are formed in the bottom 90. A space on the damping valve body 81 side between the inner cylindrical portion 91 and the outer cylindrical portion 92 of the seat member 83 is a back pressure chamber 94 that applies pressure to the damping valve body 81 in the direction of the piston 11. In the disk 80 and the damping valve main body 81, a back pressure chamber inflow oil passage (not shown) for introducing the oil liquid from the upper chamber 12 to the back pressure chamber 94 is formed. The back pressure chamber 94 and the through hole 93 of the seat member 83 communicate with the passage 60 of the piston 11 so that the upper chamber 12 and the lower chamber 13 can communicate with each other. A passage (first passage) 95 through which the oil liquid flows from the upper chamber 12 toward the lower chamber 13 by movement is formed. A plurality of passage grooves 96 penetrating in the radial direction are formed in the inner cylindrical portion 91.

  An annular outer seat portion 98 is formed on the outer cylindrical portion 92 on the side opposite to the piston 11, and the large-diameter valve body 85 is seated on the outer seat portion 98. Further, an annular inner seat portion 99 having a smaller diameter and a lower axial height than the outer seat portion 98 is formed on the bottom portion 90 on the side opposite to the piston 11, and a small diameter valve is formed on the inner seat portion 99. The main body 84 is seated. A chamber 100 is formed between the inner sheet portion 99 and the outer sheet portion 98. The through hole 93 is formed on the radially inner side with respect to the inner sheet portion 99 of the sheet member 83.

  The disk 80 has a perforated disk shape having an outer diameter smaller than that of the seat portion 70 of the piston 11.

  The damping valve body 81 includes a perforated disc-like disk 102 that can be seated on the seat portion 70 of the piston 11 and an annular sealing member made of a rubber material fixed to the outer peripheral side of the disk 102 opposite to the piston 11. 103. The damping valve main body 81 and the seat portion 70 of the piston 11 are provided between the passage 60 provided in the piston 11 and the passage 95 provided in the seat member 83, and the flow of oil produced by sliding of the piston 11 The damping valve 104 is configured to generate a damping force by regulating the above. The damping valve 104 is a disk valve.

  Although not shown, the disk 102 is formed with a through-hole penetrating in the axial direction radially inward of the seal member 103. The seal member 103 contacts the inner peripheral surface of the outer cylindrical portion 92 of the seat member 83 and seals the gap between the damping valve main body 81 and the outer cylindrical portion 92 of the seat member 83. Therefore, the back pressure chamber 94 between the damping valve body 81 and the seat member 83 applies an internal pressure to the damping valve body 81 of the damping valve 104 in the direction of the piston 11, that is, the valve closing direction in contact with the seat portion 70. . When the damping valve main body 81 is opened away from the seat portion 70 of the piston 11, the damping valve 104 allows the oil from the passage 60 to pass through the radial flow path 105 between the piston 11 and the seat member 83. Flow into lower chamber 13.

  The valve restricting member 82 has a smaller diameter than the disk 102 and restricts deformation beyond the regulation in the direction opposite to the seat portion 70 of the damping valve main body 81, that is, in the opening direction.

  The small-diameter valve main body 84 has an annular shape that can be seated on the inner seat portion 99 of the seat member 83, and is configured by overlapping a plurality of annular discs. The small diameter valve main body 84 and the inner seat portion 99 have a small diameter that restricts the flow of oil between the passage 95 provided in the seat member 83 and the chamber 100 between the seat member 83 and the large diameter valve main body 85. A disk valve 107 is configured. The small-diameter disk valve 107 has a fixed orifice 108 that allows the passage 95 to communicate with the chamber 100 even when the small-diameter valve main body 84 and the inner seat 99 are in contact with each other. It is formed by an opening formed in the main body 84. The small-diameter disk valve 107 communicates the passage 95 with the chamber 100 with a wider flow path area than the fixed orifice 108 by the small-diameter valve body 84 being separated from the inner seat portion 99.

  The large-diameter valve body 85 has an annular shape that can be seated on the outer seat portion 98 of the seat member 83, and is configured by overlapping a plurality of annular disks. The large-diameter valve body 85 and the outer seat portion 98 constitute a large-diameter disk valve 110 that restricts the flow of oil between the chamber 100 and the lower chamber 13 between the seat member 83 and the large-diameter valve body 85. is doing. The large-diameter disk valve 110 is provided with a fixed orifice 111 that allows the chamber 100 to communicate with the lower chamber 13 even when the large-diameter valve body 85 and the outer seat portion 98 are in contact with each other. Alternatively, it is formed by an opening formed in the large diameter valve body 85. The large-diameter disk valve 110 allows the chamber 100 to communicate with the lower chamber 13 with a wider flow path area than the fixed orifice 111 by separating the large-diameter valve body 85 from the outer seat portion 98.

  The valve regulating member 86 has a smaller diameter than the large-diameter valve body 85 and regulates deformation beyond the regulation in the opening direction of the large-diameter valve body 85.

  The compression-side damping valve 63 includes the above-described seat portion 71 and an annular damping valve main body 115 that can be seated simultaneously on the entire seat portion 71, and is a disc valve. The damping valve main body 115 is also configured by stacking a plurality of annular single disks. A disk 117 having a smaller diameter than the damping valve body 115 is disposed between the damping valve body 115 and the piston 11. An annular valve regulating member 116 having a smaller diameter than that of the damping valve body 115 is disposed on the opposite side of the damping valve body 115 from the piston 11. The valve restricting member 116 restricts deformation of the damping valve main body 115 beyond the regulation in the opening direction. The valve regulating member 116 is in contact with the shaft step portion 118 at the end of the main shaft portion 21 of the piston rod 16 on the mounting shaft portion 20 side.

  The damping valve 63 has a fixed orifice 120 that allows the passage 61 to communicate with the upper chamber 12 even when the seat portion 71 and the damping valve main body 115 are in contact with each other, or a groove formed in the seat portion 71 or the damping valve main body 115. It is formed by the opening formed. The damping valve main body 115 communicates the passage 61 with the upper chamber 12 with a larger flow area than the fixed orifice 120 by being separated from the seat portion 71. The valve restricting member 116 restricts deformation of the damping valve main body 115 beyond the regulation in the opening direction. As described above, the damping valve 63 is provided in the passage 61 and generates a damping force by suppressing the flow of the oil liquid caused by the sliding of the piston 11.

  A nut 121 is screwed into the male screw 19 at the tip of the piston rod 16, and this nut 121 comes into contact with the valve restricting member 86, so that the valve restricting member 86, the large diameter valve main body 85, the small diameter valve main body 84, The seat member 83, the valve regulating member 82, the damping valve main body 81, the disk 80, the piston 11, the disk 117, the damping valve main body 115 and the valve regulating member 116 are sandwiched between the shaft step portion 118.

  Here, an example in which the damping valve 104 and the damping valve 63 are disc valves with inner circumference clamps is shown. However, the present invention is not limited to this, and any mechanism that generates damping force may be used. For example, the disc valve may be a coil spring. It may be a lift type valve that is energized or may be a poppet valve.

  The intermediate stopper 28 comes into contact with the stopper ring 51 at a predetermined distance from the spring receiver 24 that comes into contact with the retainer 23 by the biasing force of the auxiliary spring 26 in the set state, and the intermediate stopper 28 comes into contact with the main shaft portion 21 of the piston rod 16. Is formed with a passage hole 125 along the radial direction at a position closed by the intermediate stopper 28 in this state. The passage hole 125 is formed at a position between the seal ring 49 and the stopper ring 51 of the intermediate stopper 28 that contacts the stopper ring 51. Further, a passage hole 126 along the radial direction is formed in the mounting shaft portion 20 of the piston rod 16 so as to be aligned with the passage groove 96 of the seat member 83 in the axial direction. Furthermore, a passage hole 127 communicating with both the passage hole 125 and the passage hole 126 is formed in the piston rod 16 from the mounting shaft portion 20 to the main shaft portion 21 along the axial direction. The passage hole 125 and the passage hole 126 have substantially the same diameter, and the passage hole 127 has a larger diameter than the passage hole 125 and the passage hole 126.

  A plug 130 that closes the passage hole 127 is screwed and fixed to the opening of the passage hole 127. The plug 130 has a shaft portion 131 and a flange portion 132, a male thread 133 is formed on the flange portion 132 side of the shaft portion 131, and a seal groove 134 is formed at an intermediate position in the axial direction of the shaft portion 131. ing. An O-ring 136 is fitted in the seal groove 134. A female screw 137 for screwing the male screw 133 is formed in the opening of the passage hole 127. The plug 130 is fitted into the passage hole 127 in the shaft portion 131, is screwed into the female screw 137 in the male screw 133, and comes into contact with the end surface of the mounting shaft portion 20 in the flange portion 132. In this state, the O-ring 136 seals the gap between the shaft portion 131 and the passage hole 127. Thus, the passage hole 127 whose opening is closed by the plug 130 and the O-ring 136, the passage hole 125, and the passage hole 126 serve as an in-rod passage (second passage) 140 formed in the piston rod 16. The rod inner passage 140 introduces the oil into the back pressure chamber 94 through the passage groove 96 from one upper chamber 12 in the cylinder 10 when the passage hole 125 is opened.

  The intermediate stopper 28 is movable on the piston rod 16 so as to approach and separate from the spring receiver 24 while expanding and contracting the auxiliary spring 26. The intermediate stopper 28 opens the passage hole 125 so that the opening amount increases as it approaches the spring receiver 24 side by approaching the spring receiver 24. As shown in FIG. 3, the intermediate stopper 28 can be fully opened by moving to the spring receiver 24 side. When the intermediate stopper 28 is closest to the spring receiver 24, the intermediate stopper 28 comes into contact with the spring receiver 24, and as a result, the intermediate stopper 28 is stopped with respect to the piston rod 16. The intermediate stopper 28 and the passage hole 125 are provided in the in-rod passage 140, and constitute a variable orifice 142 whose passage area is adjusted by the rebound spring 32 when the piston rod 16 moves in the extending direction.

  Here, when the rebound spring 32 does not contract during the extension stroke in which the piston rod 16 moves to the extension side, the intermediate stopper 28 closes the passage hole 125, that is, the rod inner passage 140. The upper chamber 12 and the back pressure chamber 94 do not communicate with each other.

  In this state, when the piston speed is low, the oil from the upper chamber 12 causes the passage 60, a not-shown through hole of the damping valve main body 81, the passage 95 including the back pressure chamber 94, and the small-diameter disk valve 107. A fixed orifice 108 formed between the inner seat 99 and the small diameter valve body 84, a fixed orifice formed between the chamber 100, the outer sheet 98 of the large diameter disk valve 110 and the large diameter valve body 85. 111 flows into the lower chamber 13 through 111, and a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated. For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force becomes relatively high as the piston speed increases.

  When the piston speed is increased, the oil from the upper chamber 12 opens the small-diameter valve body 84 of the small-diameter disk valve 107 and the large-diameter valve body 85 of the large-diameter disk valve 110 via the passage 60 and the passage 95. However, it flows between the inner seat portion 99 and the small-diameter valve main body 84 and between the outer seat portion 98 and the large-diameter valve main body 85 and flows into the lower chamber 13, and the valve characteristics (damping force is the piston speed). A damping force that is approximately proportional to For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force is slightly lowered with respect to the increase of the piston speed.

  Further, when the piston speed is further increased, the relationship between the force (hydraulic pressure) acting on the damping valve body 81 of the damping valve 104 is that the force in the opening direction applied from the passage 60 is the force in the closing direction applied from the back pressure chamber 94. Bigger than. Therefore, in this region, as the piston speed increases, the damping valve 104 opens and the damping valve body 81 moves away from the seat portion 70, and between the inner seat portion 99 of the small diameter disc valve 107 and the small diameter valve body 84, In addition to the flow to the lower chamber 13 passing between the outer seat portion 98 of the large-diameter disk valve 110 and the large-diameter valve body 85, the lower chamber 13 is connected via the flow path 105 between the piston 11 and the seat member 83. Since the oil liquid is allowed to flow through, the increase in damping force is suppressed. The characteristic of the damping force with respect to the piston speed at this time is that there is almost no increase rate of the damping force with respect to the increase in the piston speed. Therefore, when an impact shock occurs due to a high piston speed and a relatively high frequency, such as a road surface step, the shock is sufficiently absorbed by suppressing an increase in damping force with respect to an increase in piston speed as described above.

  In addition, after the impact shock occurs, the amplitude becomes smaller and the piston speed becomes slower at the same frequency as that at the time of occurrence, and the relationship of the force acting on the damping valve body 81 of the damping valve 104 is in the opening direction applied from the passage 60. The force becomes smaller than the force in the closing direction applied from the back pressure chamber 94, and the damping valve body 81 moves in the valve closing direction. Therefore, the flow from the upper chamber 12 to the lower chamber 13 due to the opening of the damping valve main body 81 of the damping valve 104 is reduced, and between the inner seat portion 99 of the small diameter disc valve 107 and the small diameter valve main body 84 and the large diameter. Since the flow to the lower chamber 13 passing between the outer seat portion 98 of the diameter disc valve 110 and the large diameter valve main body 85 is mainly, the rate of increase of the damping force with respect to the increase of the piston speed is increased. As a result, the unsprung variation after the impact shock occurs is suppressed.

  In the contraction stroke in which the piston rod 16 moves to the contraction side in a state where the rebound spring 32 does not contract, when the piston speed is low, the oil liquid from the lower chamber 13 passes through the passage 61 and the damping valve body 115 of the damping valve 63. And a fixed orifice 120 formed between the sheet portion 71 and the upper chamber 12 flows to generate a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed). For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force becomes relatively high as the piston speed increases.

  Further, when the piston speed increases, the oil introduced into the passage 61 from the lower chamber 13 basically passes between the damping valve body 115 and the seat portion 71 while opening the damping valve body 115 of the damping valve 63. It flows into the upper chamber 12, and a damping force having a valve characteristic (a damping force is approximately proportional to the piston speed) is generated. For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force is slightly lowered with respect to the increase of the piston speed.

  Here, as described above, the rebound spring 32 has an effect of suppressing the amount of roll of the vehicle body by suppressing the lifting of the inner peripheral side wheel when the vehicle turns. FIG. 4 shows the relationship between the spring reaction force of the unillustrated suspension spring and the rebound spring interposed between the spring receiver 37 and the vehicle body with respect to the stroke position of the shock absorber having the rebound spring. As shown in FIG. 4, the spring reaction force is the highest at the full bottom position Pfb, which is the limit position on the contraction side, and the bound stroke Sb from the full bottom Pfb position to the 1G position (position where the vehicle body is horizontal) P0. The buffer clearance BC from the position P0 of 1G to the predetermined position P1 on the expansion side where the rebound spring of the rebound stroke Sr on the contraction side starts to act is interposed between the spring receiver 37 and the vehicle body. The proportional relationship is based on a spring constant Ks of a suspension spring (not shown).

  Further, in the rebound stroke Sr, the rebound spring operating range R from the predetermined position P1 on the expansion side where the rebound spring acts to the full rebound position Pfr that is the limit position on the expansion side is the suspension spring and the rebound spring in parallel. Therefore, a proportional relationship is established by a spring constant Ks + Kr obtained by adding the spring constant Ks of the suspension spring and the spring constant Kr of the rebound spring. For this reason, in the rebound spring operating range R, although the roll amount of the vehicle body can be kept small, the spring constant increases by the amount of the rebound spring, thereby reducing the damping force in the shock absorber. As a result, the vibration damping performance on the spring of the vehicle is insufficient, and the riding comfort performance during steering in the rebound spring operating range R is reduced.

  On the other hand, in this embodiment, the intermediate stopper 28 in which the opening to the upper chamber 12 of the passage hole 125 of the in-rod passage 140 in the piston rod 16 is in contact with the stopper ring 51 by the auxiliary spring 26. The passage hole 125 and the intermediate stopper 28 constitute a variable orifice 142 that makes the passage area of the rod inner passage 140 variable. Thereby, for example, the piston rod 16 of the shock absorber included in the suspension on the inner side of the turn is moved to the extension side by the roll of the vehicle body when the vehicle is turning, and the piston rod 16 is moved to the extension side by a predetermined amount in this extension stroke. When the buffer body 31 is brought into contact with the rod guide 17 and enters the rebound spring operating range R after moving as described above, the spring receiver 30 slides on the piston rod 16 while the rebound spring main body 29 is brought into contact with the intermediate stopper 28. Accordingly, the auxiliary spring 26 is contracted between the intermediate stopper 28, the spring receiver 24 and the retainer 23, and the intermediate stopper 28 is moved in the direction of the spring receiver 24, so that the passage hole 125, that is, the passage in the rod. 140 is opened.

  At this time, the rebound spring main body 29 and the auxiliary spring 26 constituting the rebound spring 32 are elastically deformed simultaneously, and the intermediate stopper 28 is moved by the amount of contraction of the rebound spring main body 29 and the auxiliary spring 26 (the piston rod 16 of the piston rod 16). As the amount of projection from the cylinder 10 increases, the opening amount of the passage hole 125 is increased, and the passage hole 125 is moved in a range from a predetermined position near the full rebound to the full rebound position. That is, the opening area (flow path area) of the variable orifice 142 is adjusted by the rebound spring 32 including the rebound spring body 29 and the auxiliary spring 26 when the piston rod 16 moves in the extending direction. Specifically, the opening area is adjusted by the rebound spring 32 when the piston rod 16 moves in the extending direction.

  As a result, when the piston rod 16 extends toward full rebound in the extension stroke, oil flows from the upper chamber 12 through the rod inner passage 140 toward the back pressure chamber 94 of the extension-side damping force generation mechanism 62. The liquid increases according to the amount of extension of the piston rod 16 from the cylinder 10 by the intermediate stopper 28, the valve opening pressure of the damping valve 104 of the damping force generating mechanism 62 becomes high, and the damping valve body 81 is seated. The pressure separating from the portion 70 increases. As a result, the oil liquid flowing from the upper chamber 12 to the lower chamber 13 through the passage 60 of the piston 11 becomes difficult to flow according to the amount of extension of the piston rod 16 from the cylinder 10. Therefore, the damping force of the shock absorber increases in accordance with the amount of extension of the piston rod 16 from the cylinder 10 in the rebound spring operating range R.

  The hydraulic circuit diagram of the first embodiment having the above configuration is as shown in FIG. That is, an extension-side damping force generation mechanism 62 and a contraction-side damping valve 63 are provided in parallel between the upper chamber 12 and the lower chamber 13, and the back pressure chamber 94 of the damping force generation mechanism 62 is a rebound spring. It is connected to the upper chamber 12 side through a variable orifice 142 controlled by 32.

  According to the first embodiment, the cylinder is provided in the back pressure chamber 94 that applies an internal pressure in the valve closing direction to the damping valve 104 provided in the passage 60 through which the oil liquid flows out from the upper chamber 12 in the cylinder 10. 11 is provided with an in-rod passage 140 through which oil is introduced from the upper chamber 12 and a variable orifice 142 whose area is adjusted by the rebound spring 32 when the piston rod 16 moves in the extending direction. It was. For this reason, the damping force by the damping valve 104 can be increased by increasing the pressure of the back pressure chamber 94 via the in-rod passage 140 and suppressing the opening of the damping valve 104 in the rebound spring operating range R.

  In other words, the variable orifice 142 is closed and the pressure in the back pressure chamber 94 cannot be increased via the in-rod passage 140, as compared with the damping force in the bounding stroke Sb on the extension side and the buffer clearance BC shown by the broken line in FIG. By opening the variable orifice 142 and increasing the pressure in the back pressure chamber 94 via the rod inner passage 140, it is possible to increase the damping force in the rebound spring operating range R on the extension side indicated by the solid line in FIG. Note that the one-dot chain line in FIG. 6 shows a constant damping force characteristic by the damping valve 63 on the contraction side without the back pressure chamber and the variable orifice.

  As described above, when the vehicle on which the rebound spring 32 does not operate is traveling straight, the damping force is lowered to improve the ride comfort. On the other hand, when the rebound spring 32 is operated, the damping force is increased to increase the damping force. In addition to improving the responsiveness, it is possible to improve the sprung mass damping performance with respect to a large input from the road surface or steering to improve the steering stability, and to prevent the sprung mass damping performance from deteriorating due to an increase in the spring constant. Therefore, even when the rebound spring 32 that suppresses the expansion and contraction of the piston rod 16 is used, a desired damping force can be generated. In addition, by increasing the damping force on the rebound spring 32, it is possible to suppress the hitting sound generated by the close contact of the rebound spring 32 or the contact between the intermediate stopper 28 and the spring receiver 24 when fully extended.

“Second Embodiment”
Next, the second embodiment will be described mainly with reference to FIGS. 7 to 10 focusing on the differences from the first embodiment. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

  As shown in FIG. 7, in the second embodiment, the spring receiver 24 is provided not between the retainer 23 and the intermediate stopper 28 but between the retainer 23 and the piston 11. It comes into contact with the retainer 23. The spring receiver 24 is formed with an annular valve pressing portion 150 that protrudes from the outer peripheral edge of the flange portion 41 toward the piston 11. The spring receiver 24 comes into contact with the damping valve body 115 of the compression side damping valve 63 (second damping valve) from the side opposite to the piston 11, and the damping valve body 115 is interposed via the spring receiver 24. The rebound spring 32 and the like are opened while being pushed. Therefore, the spring receiver 24 presses the damping valve 63 with the urging force of the rebound spring 32 when the rebound spring 32 is contracted, including when the piston rod 16 is fully extended.

  In the second embodiment having the above-described configuration, when the damping valve 63 is opened during the contracting stroke in which the piston rod 16 moves to the contracting side, the damping valve main body 115 that contacts the valve pressing portion 150 of the spring receiver 24 is It is necessary to press the spring receiver 24 and move it relative to the piston rod 16. Since the rebound spring 32 is not contracted outside the rebound spring operating range R, the spring receiver 24 basically does not receive the urging force of the rebound spring 32, and opens the passage 61 while opening the damping valve body 115 of the damping valve 63. The oil liquid flowing from the lower chamber 13 to the upper chamber 12 through the air easily flows, and thus the damping force decreases.

  On the other hand, in the rebound spring operating range R, the rebound that constitutes the rebound spring 32 while the intermediate stopper 28 is brought close to the retainer 23 as shown in FIG. 8 in the contraction stroke in which the piston rod 16 moves to the contraction side. The spring body 29 and the auxiliary spring 26 are contracted, and these urging forces are applied to the damping valve body 115 of the damping valve 63 from the valve pressing portion 150 of the spring receiver 24. For this reason, the oil liquid flowing from the lower chamber 13 to the upper chamber 12 through the passage 61 while opening the damping valve body 115 of the damping valve 63 is difficult to flow, and hence the damping force is increased. In addition, as the piston rod 16 is positioned on the extended side, the urging force of the damping valve 63 to the damping valve body 115 by the rebound spring body 29 and the auxiliary spring 26 increases, and thus the damping force increases.

  The hydraulic circuit diagram of the second embodiment having the above configuration is as shown in FIG. 9, and the rebound spring 32 controls the contraction-side damping valve 63 in addition to the variable orifice 142.

  As described above, according to the second embodiment, the damping valve 63 disposed on the other end side of the piston 11 is configured to be pressed by the rebound spring 32 when the piston rod 16 is fully extended. In the rebound spring operating range R, in the same manner as in the first embodiment, the hydraulic pressure of the upper chamber 12 is introduced into the back pressure chamber 94 of the extension-side damping force generation mechanism 62 to increase the extension stroke damping force. 10, the damping force of the compression side damping valve 63 can be increased as compared with the damping force other than the rebound spring operating range R indicated by the one-dot chain line in FIG. Therefore, the sprung mass damping performance can be increased more effectively than in the second embodiment, and the steering stability and the ride comfort can be further improved.

  In the second embodiment, a seat portion having an axial height lower than that of the seat portion 71 is provided between the seat portion 71 on the contraction side and the passage 61, and the radial direction of the damping valve body 115 is set by the valve pressing portion 150. You may make it press the position of this sheet | seat part. When the rebound spring 32 is not contracted, the seat portion and the damping valve main body 115 serve as a communication passage that secures a sufficient passage area. When the rebound spring 32 contracts, the urging force causes the damping valve main body 115 to move. The communication path is closed or the flow path area is reduced by pressing the sheet portion. Thereby, the damping force on the contraction side can be further increased.

“Third Embodiment”
Next, a third embodiment will be described mainly based on FIGS. 11 to 14 with a focus on differences from the first and second embodiments. In addition, about the site | part which is common in 1st, 2nd embodiment, it represents with the same name and the same code | symbol.

  In the third embodiment, the locking grooves 22 and 50 of the first and second embodiments are not formed in the piston rod 16, and the retainer 23, the intermediate stopper 28, and the stopper ring 51 of the first and second embodiments are not formed. Is not provided. And the rebound spring 155 which consists of one coil spring is interposed between the spring receiver 30 (refer FIG. 1) and the spring receiver 24. FIG.

  In the spring receiver 24 of the third embodiment, a cylindrical locking portion 156 having a smaller diameter than the flange portion 41 is formed on the opposite side of the flange portion 41 from the axial cylindrical portion 40.

  In the third embodiment, the flow of the oil in the passage 61 on the contraction side is regulated and attenuated on the upper chamber 12 side in the axial direction of the piston 11 instead of the damping valve 63 of the first and second embodiments. A contraction-side damping force generation mechanism 160 that generates a force is provided.

  The compression force generation mechanism 160 on the contraction side is a pressure control type valve mechanism, and is damped in order from the lower chamber 13 side in the axial direction, that is, the piston 11 side, between the plurality of discs 117 and the valve regulating member 116. It has a valve main body 162, a valve regulating member 163, a seat member 164, a valve main body 165, a pressure ring 166 and a passage member 167, and a disk 168.

  The sheet member 164 includes a perforated disk-shaped bottom portion 175 along the axis orthogonal direction, a cylindrical inner cylindrical portion 176 along the axial direction formed on the inner peripheral side of the bottom portion 175, and an outer peripheral side of the bottom portion 175. And a cylindrical outer cylindrical portion 177 formed along the axial direction. A plurality of through holes 178 penetrating in the axial direction are formed in the bottom portion 175. A space between the inner cylindrical portion 176 and the outer cylindrical portion 177 of the seat member 164 is a back pressure chamber 179 that applies pressure to the damping valve main body 162 in the direction of the piston 11. The back pressure chamber 179 and the through hole 178 of the seat member 164 communicate with the passage 61 of the piston 11 so that the lower chamber 13 and the upper chamber 12 can communicate with each other. A communication passage 180 through which the oil liquid flows from the lower chamber 13 toward the upper chamber 12 by movement is formed.

  An annular outer seat portion 184 is formed on the outer cylindrical portion 177 on the side opposite to the piston 11, and the valve body 165 is seated on the outer seat portion 184. Further, an annular inner seat portion 185 having a smaller diameter and a lower axial height than the outer seat portion 184 is formed on the bottom portion 175 on the side opposite to the piston 11, and the inner seat portion 185 also has a valve. The main body 165 can be seated. The through hole 178 is formed on the radially inner side of the inner sheet portion 185 of the sheet member 164.

  The damping valve main body 162 includes a perforated disk-shaped disk 188 that can be seated on the seat portion 71 of the piston 11, and an annular sealing member made of a rubber material fixed to the outer peripheral side of the disk 188 opposite to the piston 11. 189. The damping valve main body 162 and the seat portion 71 of the piston 11 are provided in a passage 61 provided in the seat member 164, and the damping valve 190 that generates a damping force by regulating the flow of the oil liquid generated by the sliding of the piston 11. Is configured. The damping valve 190 is a disk valve.

  Although not shown, the disk 188 is formed with a through-hole penetrating in the axial direction radially inward of the seal member 189. The seal member 189 contacts the inner peripheral surface of the outer cylindrical portion 177 of the seat member 164 and seals the gap between the damping valve main body 162 and the outer cylindrical portion 177 of the seat member 164. Therefore, the back pressure chamber 179 described above between the damping valve main body 162 and the seat member 164 applies an internal pressure to the damping valve main body 162 of the damping valve 190 in the direction of the piston 11, that is, the valve closing direction in contact with the seat portion 71. . When the damping valve main body 162 is opened away from the seat portion 71 of the piston 11, the damping valve 190 causes the oil from the passage 61 to pass through the radial flow path 192 between the piston 11 and the seat member 164. Pour into upper chamber 12.

  The valve restricting member 163 has a smaller diameter than the disk 188 and restricts deformation beyond the regulation in the direction opposite to the seat portion 71 of the damping valve main body 162, that is, in the opening direction.

  The valve main body 165 has an annular shape that can be seated on the outer seat portion 184 and the inner seat portion 185 of the seat member 164, and is configured by overlapping a plurality of annular discs. The valve main body 165 and the inner seat portion 185 constitute an open / close valve 194 that regulates the flow of oil in the communication passage 180 provided in the seat member 164. In the normal state in which the valve body 165 is not deformed, the opening / closing valve 194 has a sufficient passage area in the portion of the communication passage 180 constituting the opening / closing valve 194. The opening / closing valve 194 restricts or blocks communication of the communication path 180 by approaching or abutting against the inner seat portion 185 when the valve main body 165 is deformed to the seat member 164 side.

  The valve main body 165 constitutes a disk valve 195 that regulates the flow of fluid between the communication chamber 180 between the valve main body 165 and the seat member 164 and the upper chamber 12 with the outer seat portion 184. ing. The disk valve 195 has a fixed orifice 196 that allows the communication passage 180 to communicate with the upper chamber 12 even when the valve main body 165 and the outer seat portion 184 are in contact with each other. It is formed by the opening formed in 165. The disk valve 195 causes the communication passage 180 to communicate with the upper chamber 12 with a wider flow path area than the fixed orifice 196 by the valve body 165 being separated from the outer seat portion 184.

  The pressure ring 166 includes a perforated disk-shaped base portion 200, a substantially cylindrical tubular portion 201 protruding from the outer peripheral side of the base portion 200 toward the axial direction, and a cylindrical shape from the inner peripheral side of the base portion 200. An annular sheet portion 202 protruding to the same side as the portion 201, and an annular pressing portion 203 protruding from the intermediate position in the radial direction of the base portion 200 to the opposite side of the cylindrical portion 201 and the sheet portion 202. ing. A plurality of passage grooves 204 penetrating in the radial direction are formed in the cylindrical portion 201 at intervals in the circumferential direction. The pressure ring 166 is integrated with the spring receiver 24 so that the cylindrical locking portion 156 is fitted inside the cylindrical portion 201 and the flange portion 41 is brought into contact with the distal end surface of the cylindrical portion 201. . The pressing portion 203 is in contact with the inner seat portion 185 in the radial direction of the valve main body 165 of the opening / closing valve 194 from the opposite side of the inner seat portion 185 in the axial direction.

  The passage member 167 has an annular shape, and a passage groove 208 penetrating in the radial direction is formed on the side opposite to the piston 11. The passage groove 208 is aligned with the passage hole 125 in the axial direction of the piston rod 16.

  The disc 168 has an annular shape that can be seated on the seat portion 202 of the pressure ring 166, and the disc 168 and the seat portion 202 constitute a variable orifice 211 whose opening area is adjusted. The variable orifice 211 is provided in the passage groove 208 of the passage member 167 communicating with the in-rod passage 140, the passage groove 204 of the pressure ring 166, and a passage (second passage) 210 formed between these. The variable orifice 211 is closed in a normal state where the pressure ring 166 does not move to the piston 11 side, and opens so that the flow path area increases according to the amount of movement when the pressure ring 166 moves to the piston 11 side. The valve restricting member 116 restricts deformation of the disc 168 beyond the regulation in the opening direction.

  A nut 121 screwed into the male screw 19 of the piston rod 16 contacts the valve restricting member 86, and the valve restricting member 86, large diameter valve main body 85, small diameter valve main body 84, seat member 83, valve restricting member 82, damping The valve body 81, the disk 80, the piston 11, the disk 117, the damping valve body 162, the valve restricting member 163, the seat member 164, the valve body 165, the passage member 167, the disk 168, and the valve restricting member 116 are connected to the shaft step portion 118. Pinch.

  In the third embodiment, the upper pressure in the cylinder 11 is set in the back pressure chamber 94 that applies the internal pressure in the valve closing direction to the damping valve 104 provided in the passage 60 from which the oil liquid flows out from the upper chamber 12 in the cylinder 10. A passage 210 for introducing the oil liquid from the chamber 12 and an in-rod passage 140 are provided, and a variable orifice 211 whose area is adjusted by the rebound spring 32 when the piston rod 16 moves in the extending direction is provided in the passage 210. When the rebound spring 155 is not contracted and is in the set state, the variable orifice 211 closes the passage 210 by bringing the disk 168 into contact with the seat portion 202 and enters the back pressure chamber 94 via the rod inner passage 140. Oil from the upper chamber 12 is not introduced.

  On the other hand, when the rebound spring 155 contracts, the spring receiver 24 and the pressure ring 166 are brought close to the piston 11 by the urging force of the rebound spring 155, and the variable orifice 211 separates the seat portion 202 from the disk 168 and passes the passage 210. Therefore, the oil liquid from the upper chamber 12 is introduced into the back pressure chamber 94 through the rod inner passage 140. Therefore, the extension stroke operates in substantially the same manner as in the first embodiment both in the rebound spring operating range and in other areas. In the third embodiment, as shown by the solid line in FIG. 13, the rising speed of the damping force in the very low speed region of the rebound spring operating range R is faster than that in the first embodiment, and the damping force is almost linear. Ascend in shape.

  In the contraction stroke in which the piston rod 16 moves to the contraction side, when the rebound spring 155 is not contracted, when the piston speed is low, the oil from the lower chamber 13 flows into the passage 61 and the damping valve main body 162. And a communication passage 180 including a back pressure chamber 179, and a fixed orifice 196 formed between the outer seat portion 184 of the disk valve 195 and the valve body 165. A damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated. For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force becomes relatively high as the piston speed increases.

  Further, when the piston speed increases, the oil from the lower chamber 13 passes between the outer seat portion 184 and the valve main body 165 while opening the valve main body 165 of the disc valve 195 via the passage 61 and the communication passage 180. Through the flow, it flows to the upper chamber 12, and a damping force having a valve characteristic (a damping force is approximately proportional to the piston speed) is generated. For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force is slightly lowered with respect to the increase of the piston speed.

  When the piston speed is further increased, the relationship between the force (hydraulic pressure) acting on the damping valve main body 162 of the damping valve 190 is that the force in the opening direction applied from the passage 61 is the force in the closing direction applied from the back pressure chamber 179. Bigger than. Therefore, in this region, the damping valve body 162 of the damping valve 190 opens away from the seat portion 71 as the piston speed increases, and passes between the valve body 165 of the disc valve 195 and the outer seat portion 184. In addition to the flow to the upper chamber 12, the oil liquid flows through the upper chamber 12 via the flow path 192 between the piston 11 and the seat member 164, so that an increase in damping force is suppressed. The characteristic of the damping force with respect to the piston speed at this time is that there is almost no increase rate of the damping force with respect to the increase in the piston speed.

  If the rebound spring 155 is contracted in the contraction stroke in which the piston rod 16 moves to the contraction side, the spring receiver 24 and the pressure ring 166 are brought close to the piston 11 by the urging force of the rebound spring 155, and the pressing portion 203 presses the valve main body 165 of the opening / closing valve 194 so as to approach or contact the inner seat portion 185, and the closed valve 194 restricts or blocks the communication path 180 to the disk valve 195. Thereby, compared with the case where the rebound spring 155 shown with the dashed-dotted line of FIG. 13 is not contracted, damping force becomes high as shown with the dashed-two dotted line in FIG. In addition, the rising speed of the damping force in the very low speed region of the rebound spring operation range R is faster than that in the second embodiment, and the damping force increases in a form close to linear.

  A hydraulic circuit diagram of the third embodiment having the above-described configuration is as shown in FIG. That is, an extension-side damping force generation mechanism 62 and a contraction-side damping force generation mechanism 160 are provided in parallel between the upper chamber 12 and the lower chamber 13, and the rebound spring 155 serves as an extension-side damping force generation mechanism. In addition to the variable orifice 142 provided for the 62 back pressure chamber 94, the disc valve 195 and the variable orifice 211 of the damping force generating mechanism 160 on the contraction side are controlled.

In each of the above embodiments, an example in which the present invention is used for a monotube type hydraulic shock absorber is shown. However, the present invention is not limited to this, and an outer cylinder is provided on the outer periphery of the cylinder, and a reservoir is provided between the outer cylinder and the cylinder. It may be used for a double cylinder type hydraulic shock absorber, and can be used for any shock absorber.
In the above embodiment, the hydraulic shock absorber is shown as an example, but water or air may be used as the fluid.
Moreover, although the example which used the coil spring as an elastic member was shown in the said embodiment, you may use other elastic members, such as rubber | gum.

10 cylinder 11 piston 12 upper chamber (chamber)
13 Lower room (room)
16 Piston rod 32,155 Rebound spring (elastic member)
60 passage (first passage)
63,109 Damping valve (second damping valve)
94 Back pressure chamber 104 Damping valve 140 Rod internal passage (second passage)
142, 211 Variable orifice 210 passage (second passage)

Claims (2)

A cylinder filled with a working fluid;
A piston slidably fitted in the cylinder and dividing the cylinder into two chambers;
A piston rod connected to the piston and extending outside the cylinder;
An elastic member provided in the cylinder and elastically acting on the piston rod to restrain the piston rod from being fully extended;
A first passage through which working fluid flows from one chamber in the cylinder by movement of the piston;
A damping valve provided in the first passage for regulating the flow of the working fluid generated by sliding of the piston and generating a damping force;
A back pressure chamber that applies an internal pressure to the damping valve in the valve closing direction; and
A second passage for introducing the working fluid from one chamber in the cylinder into the back pressure chamber,
The shock absorber according to claim 2, wherein the second passage has a variable orifice whose area is adjusted by the elastic member when the piston rod moves in the extending direction. The damping valve is arranged on one end side of the piston,
A second damping valve is arranged on the other end side of the piston,
The shock absorber according to claim 1, wherein the second damping valve is configured to be pressed by the elastic member when the piston rod is fully extended.

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