JP6506934B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber.

  Some shock absorbers are provided with a rebound bumper to suppress abnormal noise and vibration generated when the piston rod moves to the extended side (see, for example, Patent Documents 1 and 2).

JP-A-2-283928 JP-A-2-283929

  There is a demand for downsizing and cost reduction of shock absorbers.

  An object of the present invention is to provide a shock absorber which can be miniaturized and reduced in cost.

  In order to achieve the above object, according to the present invention, a damping valve is provided in the first passage to suppress the flow of the working fluid generated by the movement of the piston to generate a damping force, and the piston rod is at the longest predetermined position. The maximum long side characteristic in which the expansion side damping force is in a soft state and the compression side damping force is in a hard state in a first predetermined range extended to the outside of the cylinder rather than the cylinder rod; The expansion-side damping force is in a hard state and the contraction-side damping force is in a soft state in a range where it enters into the inside of the cylinder rather than the position, so that at least the maximum long side characteristic is obtained. And a passage area adjusting mechanism for adjusting the passage area of the second passage according to the position of the piston rod, wherein the passage area adjusting mechanism is configured to adjust the piston rod in the first predetermined range. Further the second extension-side damping force in a predetermined range extending to the outside of the cylinder is configured to be a hard state than.

  According to the present invention, downsizing and cost reduction are possible.

It is a sectional view showing a shock absorber concerning one embodiment of the present invention. It is a partial expanded sectional view which shows one passage area adjustment mechanism periphery of the buffer which concerns on one Embodiment of this invention. It is a partial expanded sectional view which shows the piston periphery of the shock absorber which concerns on one Embodiment of this invention. It is a graph which shows the characteristic of the buffer concerning one embodiment of the present invention, and (a) shows the area of the variable orifice to the stroke position of a piston rod, and (b) shows the damping force to the stroke position of a piston rod. It is a thing. It is a graph which shows the characteristic of damping force to piston speed of shock absorbers etc. concerning one embodiment of the present invention. It is a characteristic diagram showing the relation between the frequency at the time of a rough road traveling of a vehicle equipped with the shock absorber according to one embodiment of the present invention and the sprung acceleration.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In the following description, the lower side of FIGS. 1 to 3 is defined as one side and the lower side, and the upper side of FIGS. 1 to 3 is defined as the other side and the upper side.

  The shock absorber 1 of the present embodiment is a position sensitive damping force adjustable shock absorber. The shock absorber 1 of this embodiment is a so-called double cylinder type hydraulic shock absorber as shown in FIG. 1 and has a cylinder 2 in which oil fluid as a working fluid is sealed. The cylinder 2 has a cylindrical inner cylinder 3, a bottomed cylindrical outer cylinder 4 concentrically provided so as to cover the inner cylinder 3 with a diameter larger than the inner cylinder 3, and an upper opening side of the outer cylinder 4. And a cover 5 covering the A reservoir chamber 6 is formed between the inner cylinder 3 and the outer cylinder 4.

  The outer cylinder 4 is provided at a substantially cylindrical body member 7, a bottom member 8 fitted and fixed to a lower portion of the body member 7 on one side and closing the body member 7, and an upper portion on the other side of the body member 7. It consists of a substantially cylindrical mouth member 9 to be fitted and fixed.

  The mouth member 9 is press-fitted and fixed to the body member 7 at the small diameter portion 10 formed on the outer peripheral portion of the lower portion, and the large diameter portion larger in diameter than the small diameter portion 10 above the small diameter portion 10 It is eleven. An external thread 12 is formed on the outer peripheral portion of the large diameter portion 11. The lower inner periphery of the mouth member 9 is a small diameter inner periphery 13 and the upper inner periphery is a large diameter inner periphery 14 having a larger diameter than the small diameter inner periphery 13. .

  The cover 5 has a cylindrical portion 15 and an inner flange portion 16 extending radially inward from the upper end side of the cylindrical portion 15, and a female screw 17 is formed on the inner peripheral portion of the cylindrical portion 15. It is done. The cover 5 is placed on the upper end opening of the mouth member 9 and is screwed and fixed to the male screw 12 of the mouth member 9 with a female screw 17 formed in the cylindrical portion 15.

  A piston 18 is slidably fitted in the inner cylinder 3. The piston 18 divides the inside of the inner cylinder 3 into two chambers, an upper chamber 19 and a lower chamber 20. In the upper chamber 19 and the lower chamber 20 in the inner cylinder 3, oil fluid as a working fluid is enclosed, and in the reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4, fluid and gas as a working fluid And are enclosed.

  One side of the piston rod 21 is inserted into the cylinder 2, and the other side of the piston rod 21 is extended to the outside of the cylinder 2. The piston 18 is connected to one end side of the piston rod 21 inside the cylinder 2. A rod guide 22 is fitted to the inner cylinder 3 and the mouth member 9 on the one end opening side of the outer cylinder 4, and the mouth member 9 is a seal member 23 further outside the cylinder 2 than the rod guide 22. Is attached. Further, the rod guide 22 is provided with a friction member 24 at a position on the inner side of the cylinder 2 with respect to the seal member 23. The rod guide 22, the seal member 23 and the friction member 24 are all annular, and the piston rod 21 is slidably inserted inside the rod guide 22, the friction member 24 and the seal member 23. It is extended to the outside of the cylinder 2.

  Here, the rod guide 22 supports the piston rod 21 so as to be axially movable while restricting its radial movement, and guides the movement of the piston rod 21. The seal member 23 is in sliding contact with the outer peripheral portion of the piston rod 21 moving in the axial direction at the inner peripheral portion, and the oil in the inner cylinder 3 and the high pressure gas and oil in the reservoir chamber 6 in the outer cylinder 4 Prevent the leakage to the outside. The friction member 24 is fitted and fixed to the rod guide 22, and the inner peripheral portion thereof is in sliding contact with the outer peripheral portion of the piston rod 21 to generate frictional resistance on the piston rod 21. The friction member 24 is not intended to seal.

  The outer periphery of the rod guide 22 has a step shape in which the upper portion has a larger diameter than the lower portion, and is fitted to the inner peripheral portion of the upper end of the inner cylinder 3 at the lower portion. Fit into the large diameter inner circumferential portion 14 of A base valve 25 is provided on the bottom member 8 of the outer cylinder 4 to define the lower chamber 20 in the inner cylinder 3 and the reservoir chamber 6, and the inner periphery of the lower end of the inner cylinder 3 is installed on the base valve 25. The parts are fitted. When the cover 5 is screwed with the male screw 12 of the outer cylinder 4 at the female screw 17, the cover 5 holds the seal member 23 with the rod guide 22 fitted to the inner cylinder 3 at the inner flange portion 16.

  The piston rod 21 is inserted into the rod guide 22, the friction member 24 and the seal member 23, and is integrally engaged with the rod main body 26 screwed to the rod main body 26 inside the cylinder 2. And a tip rod 27 connected thereto. An insertion hole 28 along the axial direction is formed at the radial center of the rod main body 26 from the tip rod 27 side to a halfway position near the opposite end. Further, a through hole 29 extending in the axial direction is formed at the center of the tip rod 27 in the radial direction. The insertion hole 28 and the through hole 29 constitute an insertion hole 30 formed at the radial center of the piston rod 21. Thus, the piston rod 21 has a hollow structure. A metering pin 31 is inserted into the insertion hole 30 of the piston rod 21. One end side of the metering pin 31 is fixed to a base valve 25 provided on the cylinder 2 side than this, and the other end side is inserted into the insertion hole 30 of the piston rod 21. An inter-rod passage 32 (second passage) through which oil can flow in the piston rod 21 is formed between the insertion hole 30 and the metering pin 31.

  On the outer peripheral side of the rod main body 26 of the piston rod 21, an annular piston side spring bearing 35 is provided on the side of the end rod 27 which is one side in the axial direction, and on the other side in the axial direction. Are provided respectively. The piston side spring bearing 35 and the rod guide side spring bearing 36 can slide along the rod body 26 by inserting the rod body 26 inside. A rebound spring 38 formed of a coil spring is interposed between the piston side spring bearing 35 and the rod guide side spring bearing 36 so as to allow the rod body 26 to pass therethrough. A buffer 39 made of an annular elastic material is provided on the opposite side of the axial rebound spring 38 of the rod guide side spring receiver 36. The buffer 39 is also slidable along the rod body 26 by inserting the rod body 26 inward.

  The shock absorber 1 is used for a suspension device of a vehicle such as an automobile or a railway vehicle, and for example, one side is supported by a vehicle body, and the other side is connected to a wheel side. Specifically, the shock absorber 1 is connected to the vehicle body side by the piston rod 21, and the side opposite to the projecting side of the piston rod 21 of the cylinder 2 is connected to the wheel side. Note that, contrary to the above, the other side of the shock absorber 1 may be supported by the vehicle body, and one side of the shock absorber 1 may be connected to the wheel side. In the shock absorber 1, the piston rod 21 extends from the cylinder 2 when the vehicle body rises with respect to the wheels, and conversely, the piston rod 21 enters the cylinder 2 when the vehicle body descends with respect to the wheels.

  When the wheel vibrates as it travels, the position of the cylinder 2 and the piston rod 21 relatively changes according to the vibration, but the above change is suppressed by the fluid resistance of the in-rod passage 32 formed in the piston rod 21. Be done. As described in detail below, the fluid resistance of the in-rod passage 32 formed in the piston rod 21 is made to differ depending on the speed and amplitude of the vibration, and the ride comfort is improved by suppressing the vibration. In addition to the vibration generated by the wheels, an inertial force or a centrifugal force generated on the vehicle body as the vehicle travels also acts between the cylinder 2 and the piston rod 21. For example, a centrifugal force is generated in the vehicle body when the traveling direction is changed by the steering wheel operation, and a force based on the centrifugal force acts between the cylinder 2 and the piston rod 21. As described below, the shock absorber 1 of the present embodiment has good characteristics against vibration based on the force generated on the vehicle body as the vehicle travels, and has high stability when the vehicle travels. can get.

  As shown in FIG. 2, a screw hole 43 having a diameter larger than that of the insertion hole 28 and communicating with the insertion hole 28 is formed at the end of the rod body 26 on the tip rod 27 side. The through hole 29 forming the in-rod passage 32 of the tip rod 27 has a diameter smaller than that of the main hole 47 forming the substantially whole of the main hole 47 and only the lower end as shown in FIG. It consists of a small diameter hole portion 48. A passage hole 49, a passage hole 50 shown in FIG. 3 and a passage hole 51 shown in FIG. 3 are formed in the tip rod 27 in the radial direction, sequentially from the side of the rod main body 26 shown in FIG. Each of the passage holes 49 to 51 is formed at the position of the main hole portion 47 in the axial direction of the tip rod 27, and both are orthogonal to the through hole 29.

  As shown in FIG. 2, the tip rod 27 includes, in order from the side of the rod main body 26 in the axial direction, a screw shaft 55 having a male screw 54 formed on the outer periphery, a flange 56, and a holding shaft 57. There is. The screw shaft 55 is screwed into the screw hole 43 of the rod body 26 at the male screw 54 when the tip rod 27 is integrated with the rod body 26. The flange portion 56 has an outer diameter larger than that of the screw shaft portion 55 and the rod body 26 in order to contact the rod body 26 at that time. The holding shaft portion 57 has a diameter smaller than that of the flange portion 56, and a male screw 61 shown in FIG. 3 is formed on the side opposite to the axial flange portion 56. The aforementioned passage holes 49 to 51 are formed on the side of the flange portion 56 shown in FIG. 2 with respect to the male screw 61 of the holding shaft portion 57.

  As shown in FIG. 2, the piston side spring bearing 35 includes a cylindrical portion 65, an intermediate body portion 66 extending radially outward from one axial end side of the cylindrical portion 65, and an outer peripheral portion of the intermediate body portion 66. And a cylindrical pressing portion 67 projecting on the opposite side to the cylindrical portion 65 in the axial direction. The piston-side spring receiver 35 contacts the axial end of the rebound spring 38 at the end face of the intermediate barrel 66 in the axial direction with the cylindrical portion 65 in a state where the cylindrical portion 65 is disposed inside the rebound spring 38. Contact. The piston side spring bearing 35 can be in contact with the flange portion 56 of the tip rod 27 at the end face of the intermediate barrel portion 66 in the axial direction on the pressing portion 67 side. The inner circumferential portion on the cylindrical portion 65 side in the axial direction of the intermediate body portion 66 has the same diameter as the inner diameter of the cylindrical portion 65, and the inner circumferential portion on the pressing portion 67 side in the axial direction of the intermediate body portion 66 The step portion 68 is larger in diameter than the inner diameter of the cylindrical portion 65. A sliding member 69 is fitted and fixed to the step portion 68, and the sliding member 69 slides on the outer peripheral surface of the rod body 26. The pressing portion 67 is formed with a plurality of through holes 70 penetrating in the radial direction.

  In the holding shaft portion 57 of the tip rod 27, in order from the flange portion 56 side, a plurality of disks 73, a single disk 74, a plurality of biasing disks 75, a single open / close disk 76, An intermediate disc 77, an intermediate disc 78, an abutting disc 79, and a passage forming member 80 are provided.

  Each of the plurality of disks 73 is in the form of a perforated disk, and has an outer diameter smaller than the inner diameter of the pressing portion 67 of the piston side spring receiver 35. The disc 74 is in the form of a perforated disc having an outer diameter smaller than that of the disc 73. Each of the plurality of biasing disks 75 is in the form of a perforated disk, and has an outer diameter substantially the same as the outer diameter of the tip of the pressing portion 67 of the piston side spring receiver 35.

  The open / close disc 76 is in the form of a perforated disc and has an outer diameter substantially equal to the outer diameter of the biasing disc 75. On the outer peripheral side of the open / close disc 76, an annular open / close portion 83 which is recessed downward from the upper surface and protrudes downward from the lower surface is formed.

  The intermediate disc 77 is in the form of a perforated disc, and has an outer diameter smaller than that of the open / close disc 76. The intermediate disc 78 is in the form of a perforated disc having an outer diameter equal to that of the intermediate disc 77. Further, on the outer peripheral side of the intermediate disk 78, a plurality of notches 78A are formed. The contact disc 79 is in the form of a perforated disc and has the same outer diameter as the open / close disc 76. A C-shaped through hole 79A is formed in the radial direction intermediate portion of the contact disc 79.

  The passage forming member 80 is in the form of a perforated disk and has an outer diameter smaller than that of the contact disk 79. A plurality of notches 80A are provided on the inner peripheral side of the passage forming member 80. The aforementioned notch 78A formed on the outer peripheral portion of the intermediate disk 78, the through hole 79A formed on the radial intermediate position of the abutting disk 79, and the above formed on the inner peripheral portion of the passage forming member 80 The notch 80A forms a passage 86. The passage 86 communicates the radially outer side, ie, the upper chamber 19 of the intermediate disk 78 with the passage hole 49.

  The plurality of biasing disks 75 have a flat shape in a state where they are not pressed by the piston side spring bearing 35, and the opening and closing portion 83 of the opening and closing disk 76 is separated from the contact disk 79. Here, the gap between the opening / closing portion 83 of the opening / closing disk 76 and the contact disk 79 and the passage 86 formed in the intermediate disk 78, the contact disk 79 and the passage forming member 80 constitute an orifice 88. The orifice 88 and the passage hole 49 of the tip rod 27 constitute a passage 89 (second passage) for communicating the upper chamber 19 with the passage 32 in the rod.

  The piston-side spring receiver 35 axially separates the intermediate barrel 66 from the flange 56 of the tip rod 27 mainly by the biasing force of the plurality of biasing disks 75. In this state, when the piston rod 21 moves to the extension side projecting upward from the cylinder 2, that is, to the upper side, the piston side spring bearing 35, the rebound spring 38, the rod guide side spring bearing 36 shown in FIG. At the same time, the buffer 39 abuts on the rod guide 22 at a predetermined position.

  When the piston rod 21 further moves in the projecting direction, after the shock absorbing body 39 is crushed, the shock absorbing body 39 and the rod guide side spring receiver 36 stop with respect to the cylinder 2, and as a result, the piston moves with the piston rod 21. The side spring bearing 35 causes the rebound spring 38 to contract. Then, the biasing force of the rebound spring 38 at that time serves as a resistance to the movement of the piston rod 21. Thus, the rebound spring 38 provided in the cylinder 2 elastically acts on the piston rod 21 to suppress the extension and contraction of the piston rod 21. In this way, the rebound spring 38 serves as a resistance against the extension of the piston rod 21, thereby suppressing the rising of the inner peripheral wheel when the mounted vehicle is turning and suppressing the roll amount of the vehicle body. .

  Here, when the piston rod 21 moves in the projecting direction and the shock absorbing body 39 abuts on the rod guide 22, the piston-side spring receiver 35, as described above, sets the rebound spring 38 between the piston guide 21 and the rod guide-side spring receiver 36. Before being shortened, the plurality of biasing disks 75 and the opening / closing disk 76 which are abutted at the pressing portion 67 shown in FIG. 2 are slightly moved toward the flange portion 56 in the axial direction by the biasing force of the rebound spring 38. The intermediate body 66 is brought into contact with the flange 56. As described above, when the biasing spring force of the rebound spring 38 causes the biasing spring 75 to deform the biasing disc 75 and the opening / closing disc 76 at the pressing portion 67, the opening / closing portion 83 of the opening / closing disc 76 abuts on the abutting disc 79. As a result, the orifice 88 is closed to shut off the communication between the upper chamber 19 and the passage 32 in the rod via the passage 89.

  The piston side spring bearing 35, the rebound spring 38, the rod guide side spring bearing 36 shown in FIG. 1 and the buffer 39 are provided in the cylinder 2 and one end thereof presses the opening / closing disc 76 via the biasing disc 75 shown in FIG. A spring mechanism 90 is constructed, which is possible and whose other end can abut on the rod guide 22 shown in FIG. 1 on the end side of the cylinder 2. The spring mechanism 90 deforms the biasing disc 75 and the opening and closing disc 76 in the valve closing direction against the biasing force of the biasing disc 75 and the opening and closing disc 76 shown in FIG. 2 by the spring force. The spring mechanism 90 and the open / close disc 76 and the contact disc 79 for opening and closing the orifice 88 are configured to have the passage area of the orifice 88, that is, the passage 89 according to the biasing force of the rebound spring 38 which changes with the position of the piston rod 21. A passage area adjusting mechanism 91 is configured to adjust. In other words, the orifice 88 is a variable orifice whose passage area is variable in response to the position of the piston rod 21.

  The passage area of the orifice 88 with respect to the stroke position of the piston rod 21 by the passage area adjusting mechanism 91 is a maximum constant value from the maximum contraction position to the contraction side predetermined position on the contraction side. When the spring mechanism 90 starts closing the opening / closing disc 76 against the urging force of the urging disc 75 at the predetermined position on the contraction side, the passage area of the orifice 88 becomes proportionally smaller toward the expansion side. The passage area of the orifice 88 is minimum at the extension side predetermined position on the extension side where the opening / closing portion 83 of the opening / closing disc 76 abuts against the abutment disc 79, and the neutral position (1G position The position at which the vehicle body stopped at the horizontal position is supported)) and the minimum fixed value is reached until the extended position. Here, when the pressure on the passage 89 side is higher than the pressure on the upper chamber 19 side, the oil on the passage 89 side pushes the orifice 88 while moving the piston side spring receiver 35 to move to the upper chamber 19 side. leak. The valve opening pressure at that time is changed by the urging force of the rebound spring 38, and the valve opening pressure also increases as the rebound spring 38 contracts and the urging force increases.

  As shown in FIG. 3, the piston 18 is made of a metal piston main body 95 supported by a tip rod 27 and an annular synthetic resin mounted on the outer peripheral surface of the piston main body 95 and sliding inside the inner cylinder 3. The sliding member 96 of FIG.

  In the piston main body 95, the upper chamber 19 and the lower chamber 20 are communicated with each other, and a plurality of fluid flows out from the upper chamber 19 toward the lower chamber 20 in the movement to the upper chamber 19 side of the piston 18, Then, in the movement toward the lower chamber 20 side of the passage 101 (first passage) and the piston 18 toward the lower chamber 20, that is, the hydraulic fluid flows from the lower chamber 20 to the upper chamber 19 in the contraction stroke. A plurality of passages 102 (first passages) are provided which flow out (only one of them is shown in cross section in FIG. 3). That is, the plurality of passages 101 and the plurality of passages 102 communicate with each other between the upper chamber 19 and the lower chamber 20 by the movement of the piston 18 so that the fluid as the working fluid flows.

  The passages 101 are formed at equal pitches with one passage 102 interposed therebetween in the circumferential direction, and one axial side (the upper side in FIG. 3) of the piston 18 is radially outward on the other side in the radial direction. The lower side of FIG. 3 opens radially inward. A damping force generating mechanism 104 for generating damping force is provided for the half of the passages 101. The damping force generation mechanism 104 is disposed on the lower chamber 20 side which is one end side of the piston 18 in the axial direction. The passage 101 constitutes an extension side passage through which the oil passes when the piston 18 moves to the extension side where the piston rod 21 extends out of the cylinder 2 and the damping force generation provided for these The mechanism 104 serves as an extension-side damping force generation mechanism that regulates the flow of oil in the extension-side passage 101 to generate a damping force.

  Further, the passages 102 constituting the other half are formed at equal pitches with one passage 101 interposed therebetween in the circumferential direction, and the other side of the piston 18 in the axial direction (the lower side in FIG. 3) However, one side in the radial direction (upper side in FIG. 3) opens radially inward. A damping force generation mechanism 105 for generating damping force is provided in the remaining half of the passages 102. The damping force generation mechanism 105 is disposed on the side of the upper chamber 19 in the axial direction, which is the other end side of the piston 18 in the axial direction. The passage 102 constitutes a compression side passage through which the oil passes when the piston 18 moves to the compression side where the piston rod 21 enters the cylinder 2, and a damping force generating mechanism 105 provided for these. Is a compression-side damping force generation mechanism that regulates the flow of oil in the compression-side passage 102 to generate a damping force.

  The piston main body 95 has a substantially disc shape, and an insertion hole 106 for penetrating the holding shaft portion 57 of the tip rod 27 described above is formed in the center thereof in the axial direction. At the end on the lower chamber 20 side of the piston main body 95, a seat portion 107 constituting the damping force generation mechanism 104 is formed in an annular shape outside the one end opening position of the passage 101 on the extension side. A seat portion 108 constituting the damping force generation mechanism 105 is formed in an annular shape at the end on the upper chamber 19 side of the piston main body 95 outside the one end opening position of the contraction side passage 102.

  In the piston main body 95, the side opposite to the insertion hole 106 of the seat portion 107 has a step shape whose height in the axial direction is lower than that of the seat portion 107, and the other end of the passage 102 on the compression side Is open. Similarly, in the piston main body 95, the side opposite to the insertion hole 106 of the seat portion 108 has a step shape whose height in the axial direction is lower than that of the seat portion 108. The other end of the passage 101 is open.

  The extension-side damping force generation mechanism 104 is a pressure-controlled valve mechanism, and includes, from the side of the piston 18 in the axial direction, a plurality of disks 111, a single contact disk 112, and a single valve member 113. , One disc 114, a plurality of discs 115, one disc 116, one disc 117, one pilot case 118, one disc 119, and one disc 120. A single disk 121, a plurality of disks 122, a single disk 123, a single disk 124, and a restriction member 125 are provided.

  The pilot case 118 is made of metal, and has a perforated disk-shaped bottom portion 131 extending in a direction perpendicular to the axial direction, a cylindrical inner cylindrical portion 132 formed on the inner peripheral side of the bottom portion 131 and a bottom portion 131. And a cylindrical outer cylindrical portion (cylindrical portion) 133 along the axial direction, which is formed on the outer peripheral side of the cylinder. The bottom portion 131 is offset to one side in the axial direction with respect to the inner cylindrical portion 132 and the outer cylindrical portion 133, and the bottom portion 131 is formed with a plurality of through holes 134 penetrating in the axial direction. Inside the inner cylindrical portion 132, a small diameter hole 135 for fitting the holding shaft 57 of the tip rod 27 is formed on the side of the bottom 131 in the axial direction, and a small diameter hole on the side opposite to the bottom 131 in the axial direction. A large diameter hole 136 having a diameter larger than that of the portion 135 is formed. An annular seat portion 137 is formed at the end of the outer cylindrical portion 133 of the pilot case 118 on the side of the bottom portion 131 in the axial direction, and the disc 119 is seated on the seat portion 137.

  A space on the opposite side to the axial bottom 131 surrounded by the bottom 131 of the pilot case 118, the inner cylindrical portion 132 and the outer cylindrical portion 133, and the through hole 134 of the pilot case 118 The pilot chamber 140 (second passage) applies pressure in the direction of The above-described passage hole 51 of the tip rod 27, the large-diameter hole portion 136 of the pilot case 118, and the orifice 151 (second passage) formed in the disks 116 and 117 described later A pilot chamber inlet passage 141 (second passage) is connected to the pilot chamber 140 and introduces a part of the oil flow from the upper chamber 19 and the lower chamber 20 to the pilot chamber 140 via the in-rod passage 32. doing.

  The plurality of disks 111 are made of metal, and have a perforated disk shape having an outer diameter smaller than that of the seat portion 107 of the piston 18. The contact disk 112 is made of metal and has an outer diameter larger than that of the seat portion 107 of the piston 18 and is in the form of a perforated disk that can be seated on the seat portion 107.

  The valve member 113 has a perforated disc-shaped metal disc 145 having an outer diameter substantially the same as the outer diameter of the abutting disc 112, and the outer peripheral portion on the back side opposite to the seat portion 107 of the disc 145. And an annular seal member 146 made of a rubber material and fixed by baking or the like. The abutting disc 112 and the disc 145 of the valve member 113 abut on the seat portion 107 of the piston 18 to be in a closed state, and constitute an expansion-side damping valve 147 which is separated from the seat portion 107 of the piston 18 and opened. doing. The damping valve 147 forms a pilot chamber 140 together with the pilot case 118, and is provided on the pilot chamber 140 side of the passage 101 provided in the piston 18, and the oil of the passage 101 generated by the movement of the piston 18 to the extension side. Suppress the flow of fluid to generate damping force. Therefore, the damping valve 147 is a disk valve. The damping valve 147 is inhibited from opening by the pressure in the pilot chamber 140. In the contact disc 112 and the disc 145, there is formed no axially penetrating portion other than the central hole through which the holding shaft portion 57 of the piston rod 21 is inserted.

  The seal member 146 of the valve member 113 is slidably and fluidly fitted on the inner circumferential surface of the outer cylindrical portion 133 of the pilot case 118 to seal the gap between the valve member 113 and the outer cylindrical portion 133. Therefore, the above-described pilot chamber 140 between the valve member 113 and the pilot case 118 is in contact with the damping valve 147 consisting of the abutment disc 112 and the disc 145 of the valve member 113 in the direction of the piston 18, that is, the seat portion 107. The internal pressure is applied in the valve closing direction in which the contact disc 112 is abutted. The damping valve 147 is a pilot type damping valve having a pilot chamber 140, and when the abutting disc 112 is separated from the seat portion 107 of the piston 18 and opened, the fluid from the passage 101 is transferred to the piston 18 and the pilot case 118. And flow into the lower chamber 20 via the radial passage 148 between them.

  The disk 114 is made of metal, and has a perforated disk shape having an outer diameter smaller than the outer diameter of the disk 145. The plurality of disks 115 are made of metal, and have a perforated disk shape having an outer diameter equal to that of the disks 111. The disk 116 is made of metal and has a perforated disk shape having an outer diameter equal to that of the disk 115, and a plurality of notches 116A are formed on the outer peripheral side. The disk 117 is made of metal and has a perforated disk shape having an outer diameter equal to the diameter of the disk 115, and a plurality of notches 117A are formed on the inner peripheral side. The notch 116A of the disk 116 and the notch 117A of the disk 117 communicate with each other to form an orifice 151, and as described above, the inside of the large diameter hole 136 of the pilot case 118 and the pilot chamber 140 It communicates.

  The disc 119 is made of metal, has an outer diameter larger than that of the seat portion 137 of the pilot case 118, and is in the form of a perforated disc that can be seated on the seat portion 137. A plurality of notches 119A are formed on the outer peripheral side of the disc 119, and a through hole 119B connected to the notches 119A is formed in the middle in the radial direction. The disk 120 is made of metal and has an outer diameter equal to the outer diameter of the disk 119. In the disc 120, a through hole 120A is formed at an intermediate portion in the radial direction. The disk 121 has an outer diameter equal to the outer diameter of the disk 119. The disk 121 is formed with a plurality of notches 121A on the outer peripheral side. Each of the plurality of disks 122 has an outer diameter equal to the outer diameter of the disk 119.

  The disks 119 to 122 and the seat portion 137 constitute a disk valve 153 which suppresses the flow of oil between the pilot chamber 140 and the lower chamber 20 provided in the pilot case 118. The notch 119A of the disk 119, the through hole 119B, the through hole 120A of the disk 120, and the notch 121A of the disk 121 allow the pilot chamber 140 to communicate with the lower chamber 20 even when the disk 119 is in contact with the seat portion 137. (The second passage) is formed. The disc valve 153 causes the pilot chamber 140 to communicate with the lower chamber 20 with a passage area larger than the orifice 154 when the disc 122 separates from the disc 121 or the disc 119 separates from the seat portion 137. The disc 124 is in contact with the rigid high regulating member 125, and is in contact with the disc 122 when the disc valve 153 is deformed in the opening direction, thereby regulating deformation of the disc valve 153 beyond the prescribed level.

  The compression side damping force generation mechanism 105 is also a pressure control type valve mechanism similar to the extension side, and a plurality of discs 161, a single abutment disc 162, and one disc are sequentially arranged from the piston 18 side in the axial direction. One valve member 163, one disk 164, a plurality of disks 165, one disk 166, one disk 167, one pilot case 168, one disk 169, A single disk 170, a single disk 171, a plurality of disks 172, a single disk 173, and a plurality of disks 174 are provided.

  The pilot case 168 is a common part to the above-described pilot case 118, and has a perforated disk-like bottom portion 181 along the direction orthogonal to the axial direction and a cylindrical inner cylinder along the axial direction formed on the inner peripheral side of the bottom portion 181. It has a bottomed cylindrical shape having a portion 182 and a cylindrical outer cylindrical portion (cylindrical portion) 183 along the axial direction formed on the outer peripheral side of the bottom portion 181. The bottom portion 181 is offset to one side in the axial direction with respect to the inner cylindrical portion 182 and the outer cylindrical portion 183, and the bottom portion 181 is formed with a plurality of through holes 184 penetrating in the axial direction. Inside the inner cylindrical portion 182, a small diameter hole 185 for fitting the holding shaft 57 of the tip rod 27 is formed on the bottom 181 side in the axial direction, and a small diameter hole on the opposite side to the bottom 181 in the axial direction. A large diameter hole 186 having a diameter larger than that of the portion 185 is formed. An annular seat portion 187 is formed at the end portion of the outer cylindrical portion 183 of the pilot case 168 on the side of the bottom portion 181 in the axial direction, and the disc 169 is seated on the seat portion 187.

  A space on the opposite side to the axial bottom portion 181 surrounded by the bottom portion 181 of the pilot case 168, the inner cylindrical portion 182 and the outer cylindrical portion 183, and the through hole 184 of the pilot case 168 The pilot chamber 190 (second passage) applies pressure in the direction of The above-described passage hole 50 of the tip rod 27, the large diameter hole portion 186 of the pilot case 168, and the orifice 201 (second passage) formed in the disks 166 and 167 described later, the in-rod passage 32 and the pilot chamber A pilot chamber inlet passage 191 (second passage) is connected to the pilot chamber 190 and introduces a part of the oil flow from the upper chamber 19 and the lower chamber 20 to the pilot chamber 190 via the in-rod passage 32. Configured.

  The plurality of disks 161 are made of metal and have a perforated disk shape having an outer diameter smaller than that of the seat portion 108 of the piston 18. The abutment disc 162 is a common component to the above-described abutment disc 112, and has a hole-like disc shape having an outer diameter larger than that of the seat portion 108 of the piston 18 and capable of being seated on the seat portion 108 .

  The valve member 163 is a common component to the valve member 163 described above, and is opposite to the perforated disk-like disk 195 having the same outer diameter as the contact disk 162 and the seat portion 108 of the disk 195 It comprises an annular seal member 196 made of a rubber material and fixed to the outer peripheral portion on the rear side of the side. The abutting disc 162 and the disc 195 of the valve member 163 abut on the seat portion 108 of the piston 18 to be in a closed state, and form a compression-side damping valve 197 which is separated from the seat portion 108 of the piston 18 and opened. doing. The damping valve 197 forms a pilot chamber 190 together with the pilot case 168, and is provided on the pilot chamber 190 side of the passage 102 provided in the piston 18, and the oil of the passage 102 generated by the movement of the piston 18 toward the compression side. Suppress the flow of fluid to generate damping force. Therefore, the damping valve 197 is a disk valve. The damping valve 197 is inhibited from being opened by the pressure in the pilot chamber 190. In the contact disc 162 and the disc 195, there is formed no axially penetrating portion other than the central hole through which the holding shaft portion 57 of the piston rod 21 is inserted.

  The seal member 196 of the valve member 163 is slidably and fluidly fitted on the inner peripheral surface of the outer cylindrical portion 183 of the pilot case 168 to seal the gap between the valve member 163 and the outer cylindrical portion 183. Therefore, the above-described pilot chamber 190 between the valve member 163 and the pilot case 168 is in contact with the damping valve 197 consisting of the contact disc 162 and the disc 195 of the valve member 163 in the direction of the piston 18, that is, the seat portion 108. The internal pressure is applied in the valve closing direction in which the contact disc 162 is abutted. The damping valve 197 is a pilot type damping valve having a pilot chamber 190, and when the abutting disc 162 is released from the seat portion 108 of the piston 18, the fluid from the passage 102 is transferred to the piston 18 and the pilot case 168. And flow into the upper chamber 19 via the radial passage 198 therebetween.

  The disk 164 is made of metal, and has a perforated disk shape having an outer diameter smaller than the outer diameter of the disk 195. The plurality of disks 165 is made of metal and has a perforated disk shape having an outer diameter equal to that of the disks 161. The disk 166 is made of metal and has a perforated disk shape having an outer diameter equal to that of the disk 165, and a plurality of notches 166A are formed on the outer peripheral side. The disk 167 is in the form of a perforated disk having an outer diameter equal to that of the disk 166, and a plurality of notches 167A are formed on the inner peripheral side. The notch 166A of the disk 166 and the notch 167A of the disk 167 communicate with each other to form an orifice 201, and as described above, the inside of the large diameter hole 186 of the pilot case 168 and the pilot chamber 190 It communicates.

  The disc 169 is made of metal, has an outer diameter larger than that of the seat portion 187 of the pilot case 168, and is in the form of a perforated disc that can be seated on the seat portion 187. In the disk 169, a plurality of notches 169A are formed on the outer peripheral side, and a through hole 169B connected to the notches 169A is formed in the intermediate portion in the radial direction. The disk 170 is made of metal and has an outer diameter equal to the outer diameter of the disk 169. In the disk 170, a through hole 170A is formed at an intermediate portion in the radial direction. The disk 171 is made of metal and has an outer diameter equal to the outer diameter of the disk 169. The disc 171 is formed with a plurality of notches 171A on the outer peripheral side. The plurality of disks 172 are made of metal, and each has an outer diameter equal to the outer diameter of the disk 169.

  The disks 169 to 172 and the seat portion 187 constitute a disk valve 203 for suppressing the flow of oil between the pilot chamber 190 provided in the pilot case 168 and the upper chamber 19. The notch 169A of the disk 169, the through hole 169B, the through hole 170A of the disk 170, and the notch 171A of the disk 171 make the pilot chamber 190 communicate with the upper chamber 19 even when the disk 169 is in contact with the seat portion 187. (The second passage) is formed. The disc valve 203 causes the pilot chamber 190 to communicate with the upper chamber 19 with a larger passage area than the orifice 204 by the disc 172 separating from the disc 171 or the disc 169 separating from the seat portion 187. The plurality of disks 174 abut against the disk 172 when the disks 169 to 172 are deformed in the opening direction, and the deformation of the disks 169 to 172 is restricted. The passage 89, the in-rod passage 32, the pilot chamber 140, 190, the pilot chamber inflow passage 141, 191, the orifices 151, 154, 201, 204 make the working fluid between the upper chamber 19 and the lower chamber 20 by the movement of the piston 18. It communicates so that the fluid which is is flowing.

  A nut 210 is screwed into the male screw 61 at the tip of the tip rod 27. The nut 210 is tightened to the male screw 61, whereby the plurality of discs 73, the discs 74, the plurality of biasing discs 75, the opening / closing disc 76, the intermediate disc 77, the intermediate disc 78, the abutment disc 79 shown in FIG. Aisle forming member 80, a plurality of disks 174, a disk 173, a plurality of disks 172, a disk 171, a disk 170, a disk 169, a pilot case 168 shown in FIG. 3, a disk 167, a disk 166, a plurality of disks 165, a disk 164, a valve member 163, an abutting disk 162, a plurality of disks 161, a piston 18, a plurality of disks 111, an abutting disk 112, a valve member 113, a disk 114, a plurality of disks 115, a disk 116, a disk 117, Pilot case 118 Disk 119, disk 120, disk 121, a plurality of discs 122, the disc 123, the disc 124 and the regulating member 125 is held between the flange portion 56 of the tip rod 27 shown in FIG.

  In this state, the damping valve 147 consisting of the disc 145 and the abutting disc 112 is clamped at the inner peripheral side by the disc 114 and the disc 111, and when the outer peripheral side is seated on the seat portion 107, the passage 101 is closed and the outer peripheral side is When the seat portion 107 is released, the passage 101 is opened. Similarly, the damping valve 197 consisting of the disc 195 and the abutting disc 162 is clamped at the inner peripheral side by the disc 164 and the disc 161, and when the outer peripheral side is seated on the seat portion 108, the passage 102 is closed and the outer peripheral side is the seat Away from the section 108, the passage 102 is opened.

  As shown in FIG. 1, the metering pin 31 has a support flange portion 220 supported by the base valve 25, and a first large diameter shaft having a diameter smaller than that of the support flange portion 220 and extending axially from the support flange portion 220. Portion 222, a first tapered shaft portion 223 extending in the axial direction from the opposite side to the support flange portion 220 of the first large diameter shaft portion 222, and a first large diameter shaft portion 222 of the first tapered shaft portion 223 Has an intermediate diameter shaft portion 224 extending in the axial direction from the opposite side. In addition, the metering pin 31 is an intermediate diameter shaft portion of the second tapered shaft portion 251 and a second tapered shaft portion 251 extending in the axial direction from the opposite side to the first tapered shaft portion 223 of the intermediate diameter shaft portion 224. A small diameter shaft portion 252 extending in the axial direction from the opposite side to 224, a third tapered shaft portion 253 extending in the axial direction from the opposite side to the second tapered shaft portion 251 of the small diameter shaft portion 252, and a third And a second large diameter shaft portion 254 extending in the axial direction from the opposite side to the small diameter shaft portion 252 of the tapered shaft portion 253.

  The first large diameter shaft portion 222 has a constant diameter, and the intermediate diameter shaft portion 224 has a constant diameter smaller than that of the first large diameter shaft portion 222. The first tapered shaft portion 223 continues these, and has a tapered shape in which the diameter decreases toward the intermediate diameter shaft portion 224 side. The small diameter shaft portion 252 has a constant diameter smaller than that of the intermediate diameter shaft portion 224. The second tapered shaft portion 251 connects the small diameter shaft portion 252 and the intermediate diameter shaft portion 224 continuously, and has a tapered shape in which the diameter decreases toward the small diameter shaft portion 252 side. The second large diameter shaft portion 254 is larger in diameter than the small diameter shaft portion 252 and the intermediate diameter shaft portion 224, and has a constant diameter equivalent to that of the first large diameter shaft portion 222. The third tapered shaft portion 253 connects the small diameter shaft portion 252 and the second large diameter shaft portion 254 continuously, and has a tapered shape in which the diameter increases toward the second large diameter shaft portion 254 side.

  The metering pin 31 is inserted into the insertion hole 30 of the piston rod 21. The metering pin 31 forms an in-rod passage 32 with the insertion hole 30 of the piston rod 21. As shown in FIG. 3, the gap between the small diameter hole 48 located at one end side of the piston rod 21 disposed in the cylinder 2 and the metering pin 31 communicates with the lower chamber 20 of the in-rod passage 32. It is an orifice 225.

  2. The passage 89 including the orifice 88 shown in FIG. 2 and the in-rod passage 32 including the orifice 225 shown in FIG. 3 communicate the working fluid between the upper chamber 19 and the lower chamber 20 by the movement of the piston 18 become.

  When the first large diameter shaft portion 222 and the second large diameter shaft portion 254 of the metering pin 31 shown in FIG. 1 are aligned with the small diameter hole portion 48 in the axial direction, the passage area becomes the narrowest. In addition, when the small diameter shaft portion 252 of the metering pin 31 is aligned with the small diameter hole portion 48 in the axial direction, the orifice 225 has the largest passage area. Further, when the middle diameter shaft portion 224 of the metering pin 31 is aligned with the small diameter hole portion 48 in the axial direction of the orifice 225, the passage area becomes the middle width described above. In the orifice 225, when the first tapered shaft 223 of the metering pin 31 aligns with the small diameter hole 48 in the axial direction, the small diameter hole 48 is positioned on the side of the intermediate diameter shaft 224 of the first tapered shaft 223. The passage area is gradually enlarged as it is done. Further, in the orifice 225, when the second tapered shaft portion 251 of the metering pin 31 is axially aligned with the small diameter hole portion 48, the small diameter hole portion 48 is positioned on the small diameter shaft portion 252 side of the second tapered shaft portion 251. The passage area is gradually increased. When the third tapered shaft portion 253 of the metering pin 31 aligns with the small diameter hole portion 48 in the axial direction, the small diameter hole portion 48 of the orifice 225 faces the second large diameter shaft portion 254 of the third tapered shaft portion 253. The passage area is gradually narrowed as it is located at. In other words, the orifice 225 is a variable orifice whose passage area is variable in response to the position of the piston rod 21.

  A small diameter hole portion 48 disposed in the cylinder 2 of the piston rod 21 and a metering pin 31 include an orifice 225 and adjust the passage area of the orifice 225 by the position of the piston rod 21 with respect to the cylinder 2 The area adjustment mechanism 227 is configured. In other words, the passage area adjusting mechanism 227 adjusts the passage area of the orifice 225 by the metering pin 31.

  The passage area of the orifice 225 with respect to the stroke position of the piston rod 21 by the passage area adjusting mechanism 227 is as shown in FIG. 4 (a). That is, the passage area of the orifice 225 is the smallest constant value because the small diameter hole portion 48 and the first large diameter shaft portion 222 are aligned in the axial direction on the contraction side from the first predetermined position S1 on the contraction side. Thus, from the first predetermined position S1 to the second predetermined position S2 on the extension side, the small diameter hole portion 48 and the first tapered shaft portion 223 align in the axial direction, and the larger the extension side becomes. The small diameter hole portion 48 and the intermediate diameter shaft portion from the second predetermined position S2 to the third predetermined position S3 on the extension side including the neutral position (position of 1 G (position supporting the vehicle stopped at the horizontal position)) The axial position of 224 is matched with the axial position and becomes an intermediate constant value, and from the third predetermined position S3 to the fourth predetermined position S4 on the extension side, the small diameter hole portion 48 and the second tapered shaft portion 251 extend in the axial direction It becomes to align the position and becomes larger as it extends. Further, from the fourth predetermined position S4 to the fifth predetermined position S5 on the extending side, the small diameter hole portion 48 and the small diameter shaft portion 252 align their axial positions, and the maximum fixed value is obtained. The fifth predetermined position From S5 to the sixth predetermined position S6 on the extension side, the small diameter hole portion 48 and the third tapered shaft portion 253 are aligned in the axial direction, and become smaller on the extension side. The small diameter hole portion 48 and the second large diameter shaft portion 254 are axially aligned on the extension side including the extension position from the sixth predetermined position S6, and the passage area of the orifice 225 is minimized. It becomes a fixed value. The first predetermined position S1 is set in the vicinity of the contraction side predetermined position and the elongation side predetermined position described above.

  As shown in FIG. 1, the base valve 25 described above is provided between the bottom member 8 of the outer cylinder 4 and the inner cylinder 3. The base valve 25 includes a base valve member 231 for dividing the lower chamber 20 and the reservoir chamber 6, a disk 232 provided on the lower side of the base valve member 231, that is, the reservoir chamber 6 side, and an upper side or lower of the base valve member 231. A disk 233 provided on the chamber 20 side, a mounting pin 234 for mounting the disk 232 and the disk 233 to the base valve member 231, a locking member 235 mounted on the outer peripheral side of the base valve member 231, and a support for the metering pin 31 And a support plate 236 for supporting the flange portion 220. The mounting pin 234 clamps the radial center sides of the disc 232 and the disc 233 with the base valve member 231.

  The base valve member 231 has an annular shape in which the mounting pin 234 is inserted at the center in the radial direction. In the base valve member 231, there are a plurality of passage holes 239 for allowing oil to flow between the lower chamber 20 and the reservoir chamber 6, and the lower chamber 20 and the reservoir chamber 6 outside the passage holes 239 in the radial direction. And a plurality of passage holes 240 through which the fluid flows. The disk 232 on the reservoir chamber 6 side allows the flow of oil from the lower chamber 20 to the reservoir chamber 6 via the inner passage hole 239 while the inner passage hole 239 from the reservoir chamber 6 to the lower chamber 20 is Restrict the flow of oil through the The disc 233 allows the flow of oil from the reservoir chamber 6 to the lower chamber 20 through the outer passage hole 240 while the oil from the lower chamber 20 to the reservoir chamber 6 through the outer passage hole 240 Regulate the flow of

  The disk 232, together with the base valve member 231, constitutes a compression-side damping valve 242 that opens in the compression stroke of the shock absorber 1 to flow oil from the lower chamber 20 to the reservoir chamber 6 and generates a damping force. There is. The disk 233, together with the base valve member 231, constitutes a suction valve 243 which is opened in the expansion stroke of the shock absorber 1 and causes the fluid to flow from the reservoir chamber 6 into the lower chamber 20. The suction valve 243 functions to flow the fluid from the reservoir chamber 6 to the lower chamber 20 substantially without generating a damping force so as to compensate for the shortage of the fluid generated mainly by the extension of the piston rod 21 from the cylinder 2 Play.

  The locking member 235 has a tubular shape, and the base valve member 231 is fitted inside thereof. The base valve member 231 is fitted to the inner peripheral portion of the lower end of the inner cylinder 3 via the locking member 235. A locking flange portion 245 extending radially inward is formed at an end of the locking member 235 on the piston 18 side. The outer peripheral portion of the support plate 236 is locked on the opposite side to the piston 18 of the locking flange portion 245, and the inner peripheral portion is locked on the piston 18 side of the support flange portion 220 of the metering pin 31. As a result, the locking member 235 and the support plate 236 hold the support flange portion 220 of the metering pin 31 in a state of abutting on the mounting pin 234.

  Next, the operation of the shock absorber 1 of the present embodiment will be described. The shock absorber 1 of the present embodiment is provided with the passage area adjusting mechanisms 91 and 227, and thus has a position sensitive function in which the damping force changes according to the stroke position of the piston rod 21.

  When the piston rod 21 is positioned within the minimum long side predetermined range which is to be entered into the cylinder 2 more than the minimum long side predetermined position near the first predetermined position S1 shown in FIG. 4A, the rebound spring 38 is contracted. Do not lengthen. Therefore, the passage area adjusting mechanism 91 shown in FIG. 2 separates the opening / closing disc 76 from the abutting disc 79 without being pressed by the spring mechanism 90 including the rebound spring 38, and maximizes the passage area of the orifice 88 of the passage 89. Do. Further, in the minimum length side predetermined range, the passage area adjusting mechanism 227 shown in FIG. 3 aligns the axial positions of the first large diameter shaft portion 222 of the metering pin 31 and the small diameter hole portion 48 of the piston rod 21 Make the passage area of 225 a minimum value. In this minimum length side predetermined range, the in-rod passage 32 communicates with the upper chamber 19 via the passage 89 shown in FIG. 2, and the pilot chambers 140 and 190 shown in FIG. Both communicate with the upper chamber 19.

  In the extension stroke in which the piston rod 21 is extended to the outside of the cylinder 2 within the minimum long side predetermined range, the piston 18 moves to the upper chamber 19 side, the pressure in the upper chamber 19 increases, and the pressure in the lower chamber 20 increases. Go down. Then, the pressure of the upper chamber 19 acts on the disc 145 and the abutment disc 112 of the damping valve 147 of the damping force generating mechanism 104 on the extension side via the passage 101 formed in the piston 18.

  At this time, the pilot chamber 140 which causes the pilot pressure in the direction of the seat portion 107 to act on the valve member 113 and the abutment disc 112 is the passage 89 shown in FIG. 2 and the in-rod passage 32 and the pilot chamber inflow passage 141 shown in FIG. The upper chamber 19 is in communication with the upper chamber 19, so that the pressure close to the upper chamber 19 is established, and the pilot pressure also increases with the pressure increase of the upper chamber 19.

  In this state, when the piston speed is low, the pressure increase in the pilot chamber 140 can follow the pressure increase in the upper chamber 19, so that the pressure difference received by the valve member 113 and the contact disc 112 becomes small. It will be difficult to leave. Therefore, the oil from the upper chamber 19 passes from the passage 89 shown in FIG. 2 and the passage 32 in the rod and the pilot chamber inflow passage 141 shown in FIG. 3 to the pilot chamber 140 and the orifice 154 of the disc valve 153. At 20, a damping force of orifice characteristics (the damping force is approximately proportional to the square of the piston speed) is generated. For this reason, as shown by the characteristic line Y1 in FIG. 5, the characteristic of the damping force with respect to the piston velocity has a relatively high rate of increase in damping force with respect to the increase in piston velocity.

  Further, even when the piston speed is higher than the above, the valve member 113 and the abutment disc 112 are not separated from the seat portion 107, and the fluid from the upper chamber 19 passes through the passage 89 shown in FIG. The pilot chamber inflow passage 141 shown in FIG. 3 passes through the pilot chamber 140, passes between the seat portion 137 and the disks 119 to 122, and flows to the lower chamber 20 while pushing the disc valve 153 open. A damping force is generated (the damping force is approximately proportional to the piston speed). For this reason, as shown by the characteristic line Y1 in FIG. 5, in the characteristics of the damping force with respect to the piston velocity, the rate of increase in the damping force decreases slightly with respect to the increase in the piston velocity. Here, in the minimum long side predetermined range, as shown by the characteristic line Y1 in FIG. 5, in the position-sensitive damping force adjustment formula indicated by the two-dot chain line O1, whether the elongation damping force is slow or fast It will be in a hard condition against the extension side damping force of a normal shock absorber.

  From the above, the damping force of the extension stroke is high in the minimum long side predetermined range, and the extension side damping force is in the hard state (the extension side damping force of the extension stroke of characteristic line Y1 of FIG. 5 and FIG. (Refer to the range on the left side of the first predetermined position S1).

  Further, in the contraction stroke in which the piston rod 21 enters the inside of the cylinder 2 in the minimum long side predetermined range, the piston 18 moves to the lower chamber 20 side and the pressure in the lower chamber 20 rises and the pressure in the upper chamber 19 Lower. Then, the hydraulic pressure of the lower chamber 20 acts on the disc 195 and the abutment disc 162 of the damping valve 197 of the compression side damping force generation mechanism 105 via the passage 102 formed in the piston 18.

  At this time, the pilot chamber 190 which causes a pilot pressure in the direction of the seat portion 108 to act on the damping valve 197 is the upper chamber through the passage 89 shown in FIG. 2, the passage 32 in the rod and the pilot chamber inflow passage 191 shown in FIG. Since it is in communication with 19, the pressure state close to the upper chamber 19 is achieved, and the pilot pressure is reduced. Thus, the valve member 163 and the abutment disc 162 receive a larger differential pressure and open relatively easily away from the seat 108, via the radial passage 198 between the piston 18 and the pilot case 168. The oil is allowed to flow to the upper chamber 19 side. Thereby, damping force of valve characteristics as shown by the characteristic line Y2 of FIG. 5 is generated. That is, in the minimum long side predetermined range, the contraction side damping force indicated by the characteristic line Y2 is in a soft state with respect to the compression side damping force of the ordinary shock absorber which is not the position sensitive damping force adjustment formula indicated by the two-dot chain line O2. Become. Moreover, in the minimum long side predetermined range, the contraction side damping force of the compression stroke becomes softer than the expansion side damping force of the extension stroke (characteristic lines Y1, Y2 of FIG. 5 and the first of FIG. 4 (b)). Refer to the range on the left side of the predetermined position S1).

  As described above, in the minimum long side predetermined range where the piston rod 21 enters the inside of the cylinder 2 from the minimum long side predetermined position in the vicinity of the first predetermined position S1, the expansion side damping force of the expansion stroke becomes a hard state. The compression side damping force of the stroke becomes the minimum long side characteristic that becomes softer than the extension side damping force.

  An intermediate predetermined range between the first intermediate predetermined position near the second predetermined position S2 shown in FIG. 4A and the second intermediate predetermined position near the third predetermined position S3 shown in FIG. 1, the shock absorber 39 shown in FIG. 1 abuts on the rod guide 22, and the spring mechanism 90 including the rebound spring 38 is contracted. As a result, in the passage area adjusting mechanism 91, the spring mechanism 90 brings the open / close disk 76 shown in FIG. 2 into contact with the contact disk 79 to close the passage 89. In the middle predetermined range, the biasing force of the rebound spring 38 increases as the piston rod 21 is positioned closer to the extension side, and the opening and closing disc 76 and the abutting disc 79 are less likely to separate and the passage 89 becomes difficult to open.

  Further, in this intermediate predetermined range, the passage area adjusting mechanism 227 shown in FIG. 3 aligns the axial position of the intermediate diameter shaft portion 224 of the metering pin 31 and the small diameter hole portion 48 of the piston rod 21 to minimize the orifice 225. The passage area is expanded to a middle predetermined value wider than the above-described minimum value than when the long side predetermined range is located. In the intermediate predetermined range, the pilot chambers 140 and 190 communicate with the lower chamber 20 at a passage area of an intermediate predetermined value through the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passages 141 and 191.

  In an extension stroke in which the piston rod 21 is extended to the outside of the cylinder 2 within this intermediate predetermined range, the piston 18 moves to the upper chamber 19 side, and the pressure in the upper chamber 19 increases and the pressure in the lower chamber 20 decreases. Then, the pressure of the upper chamber 19 acts on the disc 145 and the abutment disc 112 of the damping valve 147 of the damping force generating mechanism 104 on the extension side via the passage 101 formed in the piston 18.

  At this time, the pilot chamber 140 which causes a pilot pressure in the direction of the seat portion 107 to act on the damping valve 147 is a passage of an intermediate predetermined value in the lower chamber 20 via the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passage 141. Since they communicate with each other in area, the pressure tends to be close to that of the lower chamber 20, and the pilot pressure tends to be lower than in the minimum length side predetermined range. Therefore, the damping valve 147 receives a larger differential pressure than the minimum length side predetermined range, and opens so as to be easily separated from the seat portion 107 more than the minimum length side predetermined range, so that the pressure between the piston 18 and the pilot case 118 The oil is allowed to flow to the lower chamber 20 through the radial passage 148. Thereby, the damping force is lower than the predetermined range on the minimum length side. That is, in the intermediate predetermined range, the extension-side damping force becomes softer than the minimum-length-side predetermined range (the second predetermined position S2 and the third predetermined position S3 of the extension-side damping force of the extension stroke in FIG. See the range between and).

  Further, in a compression stroke in which the piston rod 21 enters the inside of the cylinder 2 in the intermediate predetermined range, the piston 18 moves to the lower chamber 20 side, the pressure in the lower chamber 20 rises, and the pressure in the upper chamber 19 increases. Go down. Then, the hydraulic pressure of the lower chamber 20 acts on the disc 195 and the abutment disc 162 of the damping valve 197 of the compression side damping force generation mechanism 105 via the passage 102 formed in the piston 18.

  At this time, the pilot chamber 190 which causes a pilot pressure in the direction of the seat portion 108 to act on the damping valve 197 is a passage of an intermediate predetermined value to the lower chamber 20 via the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passage 191. Since they communicate with each other in area, the pressure tends to be close to that of the lower chamber 20, and the pilot pressure is higher than the minimum long side predetermined range. Therefore, the damping valve 197 receives a smaller differential pressure, and discharges the fluid to the upper chamber 19 side away from the seat portion 108 via the passage 198, but is less likely to leave the seat portion 108 than the minimum length side predetermined range. become.

  At this time, the oil from the lower chamber 20 flows from the passage 89 to the upper chamber 19 while pushing the space between the opening / closing disk 76 of the passage area adjusting mechanism 91 and the contact disk 79 open. The side damping force is in a state of being harder than the minimum long side predetermined range. Moreover, in the intermediate predetermined range, the biasing force of the rebound spring 38 becomes higher as the piston rod 21 is positioned on the extension side, and the opening and closing disc 76 and the abutting disc 79 become difficult to separate and the passage 89 becomes difficult to open. The compression side damping force of the stroke is in a state of hard as the extension side position (refer to the range between the second predetermined position S2 and the third predetermined position S3 of the compression side damping force of the compression stroke in FIG. 4 (b) ).

  The piston rod 21 has a maximum first side predetermined position near the fourth predetermined position S4 shown in FIG. 4A and a maximum length side near the fifth predetermined position S5 near the position where the cylinder 2 is extended beyond this. A buffer 39 shown in FIG. 1 is in contact with the rod guide 22 when positioned within the first predetermined range (first predetermined range) between the second predetermined position and a spring mechanism 90 including a rebound spring 38. Is shrinking. Thus, in the passage area adjusting mechanism 91, the spring mechanism 90 causes the open / close disc 76 to abut on the abutting disc 79 to close the passage 89. In the maximum first side predetermined range, the biasing force of the rebound spring 38 becomes higher than that of the middle predetermined range, the opening and closing disc 76 and the abutting disc 79 are less likely to be separated, and the passage 89 is hardly opened. In addition, as the piston rod 21 is positioned closer to the extension side, the opening and closing disc 76 and the abutting disc 79 are less likely to be separated, and the passage 89 is more difficult to open.

  Further, in this first maximum long side predetermined range, the passage area adjusting mechanism 227 shown in FIG. 3 aligns the axial positions of the small diameter shaft portion 252 of the metering pin 31 and the small diameter hole portion 48 of the piston rod 21 As a result, the passage area 225 is made wider than the intermediate predetermined range to make the passage area a maximum value wider than the intermediate predetermined value described above. In this largest first side predetermined range, the pilot chamber 140, 190 has a passage area of maximum value in the lower chamber 20 through the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passage 141, 191. Communicate.

  In the extension stroke in which the piston rod 21 is extended to the outside of the cylinder 2 in this maximum first side predetermined range, the piston 18 moves to the upper chamber 19 side, the pressure in the upper chamber 19 increases, and the pressure in the lower chamber 20 increases. The pressure drops. Then, the pressure of the upper chamber 19 acts on the disc 145 and the abutment disc 112 of the damping valve 147 of the damping force generating mechanism 104 on the extension side via the passage 101 formed in the piston 18.

  At this time, the pilot chamber 140 which causes the pilot valve in the direction of the seat portion 107 to act on the damping valve 147 has a passage area of the maximum value to the lower chamber 20 via the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passage 141 Because the pressure is communicated with the pressure chamber, the pressure state closer to the lower chamber 20 than the intermediate predetermined range is easily obtained, and the pilot pressure is easily reduced.

  In this state, the damping valve 147 opens more easily from the seat portion 107 than in the middle predetermined range because the differential pressure received by the middle predetermined range is larger, and the diameter between the piston 18 and the pilot case 118 The oil is allowed to flow to the lower chamber 20 through the directional passage 148. Thus, the damping force is lower than the intermediate predetermined range. That is, in the maximum first side first predetermined range, the extension side damping force of the extension stroke becomes softer than the minimum long side predetermined range and the middle predetermined range (the extension side damping force of the extension stroke in FIG. Refer to the range between the fourth predetermined position S4 and the fifth predetermined position S5). In addition, in the maximum first side predetermined range, the extension-side damping force shown by the characteristic line Y3 shown in FIG. 5 is in a soft state with respect to the extension-side damping force of the ordinary shock absorber shown by the two-dot chain line O1.

  Further, in the contraction stroke in which the piston rod 21 enters the inside of the cylinder 2 in the maximum first side predetermined range, the piston 18 moves to the lower chamber 20 side, the pressure in the lower chamber 20 rises, and the upper chamber 19 pressure drops. Then, the hydraulic pressure of the lower chamber 20 acts on the disc 195 and the abutment disc 162 of the damping valve 197 of the compression side damping force generation mechanism 105 via the passage 102 formed in the piston 18.

  At this time, the pilot chamber 190 which causes the damping valve 197 to exert a pilot pressure in the direction of the seat portion 108 has a passage area of the maximum value to the lower chamber 20 via the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passage 191. Because the pressure chamber is in communication with each other, the pressure state closer to the lower chamber 20 than the intermediate predetermined range tends to be obtained, and the pilot pressure also increases with the pressure increase of the lower chamber 20. Therefore, the damping valve 197 receives a smaller differential pressure, and is separated from the seat portion 108 and discharged from the fluid to the upper chamber 19 via the passage 198, but is less likely to be separated from the seat portion 108 than the intermediate predetermined range. .

  At this time, the oil from the lower chamber 20 flows from the passage 89 to the upper chamber 19 while pushing the space between the opening / closing disk 76 of the passage area adjusting mechanism 91 and the contact disk 79 open. The side damping force is in a state of being harder than the intermediate predetermined range. Moreover, in the intermediate predetermined range, the biasing force of the rebound spring 38 becomes higher as the piston rod 21 is positioned on the extension side, and the opening and closing disc 76 and the abutting disc 79 become difficult to separate and the passage 89 becomes difficult to open. The compression side damping force of the stroke is in a state of hard as the extension side position (refer to the range between the fourth predetermined position S4 and the fifth predetermined position S5 of the compression side damping force of the compression stroke in FIG. 4 (b) ).

  Therefore, in the maximum first side first predetermined range, the contraction side damping force of the compression stroke becomes harder than the minimum first side predetermined range and the middle first predetermined range, and the expansion side damping of the first maximum extension side predetermined range It is in a state of hard rather than force. In addition, as shown by the characteristic line Y4 in FIG. 5, in the maximum first side predetermined range, the contraction side damping force is indicated by the two-dot chain line O2 regardless of whether the piston speed is low or high. It will be in the state of hard against the contraction side damping force.

  Even in the compression stroke on the maximum length side first predetermined range, the pressure in the pilot chamber 190 rises in the lower chamber 20 when the piston speed reaches a region of higher speed at the time of impact shock occurring due to a step on the road surface or the like. The pressure relationship of the differential pressure acting on the disc 195 and the abutment disc 162 of the damping valve 197 of the compression side damping force generation mechanism 105 can not follow the pressure rise of the compression side. The directional force is greater than the closing direction force applied from the pilot chamber 190. Thus, in this region, the damping valve 197 opens and moves away from the seat portion 108 as the piston speed increases, and in addition to the flow to the upper chamber 19 passing between the disks 169 to 172 and the seat portion 187 Since the fluid flows into the upper chamber 19 through the radial passage 198 between the pilot 18 and the pilot case 168, 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 rate at which the damping force increases with respect to the rise of the piston speed. Therefore, at the time of impact shock or the like generated by a step on the road surface, etc., where the piston speed is high and the frequency is relatively high, the shock is sufficiently absorbed by suppressing the increase of the damping force with respect to the increase of the piston speed as described above.

  As described above, in the first long-longest first predetermined range in which the piston rod 21 extends beyond the middle predetermined range to the outside of the cylinder 2, as shown in FIG. 4B, the elongating damping force in the elongating stroke is soft. In this state, the compression side damping force in the compression stroke becomes the first largest long side characteristic (maximum long side characteristic) in which the compression side damping force becomes harder than the extension side damping force. The maximum long side first characteristic is that the extension side damping force in the extension stroke is softer than the extension side damping force in the minimum long side characteristic, and the contraction side damping force in the compression stroke is the contraction side damping with the minimum long side characteristic. It is in a state of hardware rather than force.

  Maximum length second predetermined range (second predetermined range) in which the piston rod 21 extends to the outside of the cylinder 2 beyond the third maximum predetermined length near the sixth predetermined position S6 shown in FIG. 4A In this case, the buffer 39 shown in FIG. 1 is in contact with the rod guide 22 and the spring mechanism 90 including the rebound spring 38 is contracted. As a result, in the passage area adjusting mechanism 91, the spring mechanism 90 brings the open / close disk 76 shown in FIG. 2 into contact with the contact disk 79 to close the passage 89. At this time, the biasing force of the rebound spring 38 becomes larger than the maximum first side predetermined range, so that the opening / closing disc 76 and the abutting disc 79 hardly separate and the passage 89 becomes difficult to open. In the maximum second side predetermined range, the passage 89 is maintained in the closed state without the open / close disc 76 and the abutting disc 79 being separated.

  Further, in the second predetermined length range on the maximum length side, the passage area adjusting mechanism 227 shown in FIG. 3 positions the axial positions of the second large diameter shaft portion 254 of the metering pin 31 and the small diameter hole portion 48 of the piston rod 21. In addition, the orifice 225 is, of course, narrower than the middle predetermined range on the maximum long first predetermined range, and the passage area thereof is set to the minimum value equivalent to the above-described minimum long side predetermined range. In this largest second side predetermined range, pilot chamber 140, 190 has a passage area of the minimum value in lower chamber 20 via rod internal passage 32 including orifice 225 and pilot chamber inflow passage 141, 191. It communicates.

  In the extension stroke in which the piston rod 21 is extended to the outside of the cylinder 2 within this maximum long second predetermined range, the piston 18 moves to the upper chamber 19 side, the pressure in the upper chamber 19 increases, and the pressure in the lower chamber 20 increases. The pressure drops. Then, the pressure of the upper chamber 19 acts on the disc 145 and the abutment disc 112 of the damping valve 147 of the damping force generating mechanism 104 on the extension side via the passage 101 formed in the piston 18.

  At this time, the pilot chamber 140 which causes the pilot pressure in the direction of the seat portion 107 to act on the valve member 113 and the abutment disc 112 is the lower chamber via the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passage 191. Since the communication is performed with the passage area of the minimum value 20, the pressure drop of the lower chamber 20 can not be followed, and the high pressure state is maintained.

  In this state, the pressure in the pilot chamber 140 is unlikely to be reduced, so the high state is maintained, and the differential pressure received by the valve member 113 and the abutting disc 112 becomes smaller with respect to the pressure rise in the upper chamber 19. It becomes difficult to leave the unit 107. Therefore, the damping force of the extension stroke becomes high, and the extension-side damping force is in the hard state (see the range on the right side of the sixth predetermined position S6 of the extension-side damping force of the extension stroke in FIG. 4B).

  Further, in the contraction stroke in which the piston rod 21 enters the inside of the cylinder 2 in the maximum second side predetermined range, the piston 18 moves to the lower chamber 20 side, the pressure in the lower chamber 20 rises, and the upper chamber 19 pressure drops. Then, the hydraulic pressure of the lower chamber 20 acts on the disc 195 and the abutment disc 162 of the damping valve 197 of the compression side damping force generation mechanism 105 via the passage 102 formed in the piston 18.

  At this time, the pilot chamber 190 which causes the damping valve 197 to exert a pilot pressure in the direction of the seat portion 108 has a passage area of the minimum value to the lower chamber 20 via the in-rod passage 32 including the orifice 225 and the pilot chamber inflow passage 191. As described above, since the passage 89 is maintained in the closed state without the release disc 76 and the abutting disc 79 being separated by the biasing force of the rebound spring 38, the high pressure state is maintained. Ru.

  In this state, since the pressure in the pilot chamber 190 is hard to lower, even if the pressure in the lower chamber 20 increases, the damping valve 197 receives a small differential pressure, and it becomes difficult to separate from the seat portion 108. Therefore, the compression side damping force of the compression stroke also becomes hard (refer to the range on the right side of the sixth predetermined position S6 of the compression side damping force of the compression stroke in FIG. 4B).

  As described above, in the maximum second side predetermined length range, the expansion side damping force of the extension stroke is in the state of hardware equivalent to the minimum length side predetermined range and in the state of hardware more than the maximum length first predetermined range. In addition, although the contraction side damping force of the compression stroke is softer than the expansion side damping force in the maximum length side second predetermined range, it is hard to be equal to or higher than the contraction side damping force in the maximum length side first predetermined range. It will be in the state of

  As described above, in the maximum second side second predetermined range in which the piston rod 21 extends to the outside of the cylinder 2 more than the third maximum long side predetermined position in the vicinity of the sixth predetermined position S6, the expansion side damping force is larger than the compression side damping force. It becomes the maximum long side second characteristic that is in the state of hardware. In the maximum long side second characteristic, the extension side damping force is harder than the extension side damping force of the maximum long side first characteristic.

  The shock absorber 1 according to the present embodiment includes the passage area adjusting mechanisms 91 and 227, so that as shown in FIG. 4, the relationship between hardware and software in the minimum long side predetermined range and the maximum long side first predetermined range is obtained. An inversed reversal position sensitive damping force change characteristic is obtained.

  By obtaining the above-described maximum long side first characteristic and the minimum long side characteristic, it is possible to reduce (that is, soft) the force for vibrating the spring top and to increase (that is, hard) the force for damping the spring top You get a high quality ride like Skyhook control without electronic control. FIG. 6 shows the sprung mass acceleration (PSD) for explaining the effect of the riding comfort when the mounted vehicle travels on a rough road. According to the shock absorber 1 of the present embodiment having the function of position sensing shown by the solid line D1 in FIG. 6 compared to the case where there is no function of position sensing shown by the two-dot chain line D0 in FIG. It can be seen that the upper acceleration drops significantly. This indicates that the sprung movement has become smaller and the riding comfort when traveling on a rough road has been improved. Specifically, the sprung acceleration can be reduced by about 5 dB.

  In the shock absorber described in Patent Document 1 mentioned above, the rebound stopper is attached to the piston rod, the rebound bumper is fixed to the cylinder via the retainer, and the rebound stopper is moved when the piston rod moves to the extension end side Is supposed to collide with the rebound bumper. As a result, when the piston rod moves to the extended side, the rebound bumper is deformed to absorb the impact, thereby suppressing the generation of abnormal noise (collision noise) or vibration. Here, the movement of the piston rod to the extended side occurs when the vehicle travels on a large input road surface such as a wavy road or a speed bump, for example, when it is used for a suspension device of the vehicle. With such a structure, a relatively large shock absorbing member is required, and the size of the shock absorber is increased accordingly, resulting in an increase in cost and weight. In addition, in order to suppress abnormal noise and vibration when the piston rod is completely extended, it is also practiced to incorporate a dedicated hydraulic pressure stopper mechanism. Also in this case, the shock absorber is particularly enlarged in the axial direction, resulting in an increase in cost and weight.

  In the shock absorber 1 according to the present embodiment, the expansion side damping force is in a soft state and is contracted in the maximum first side first predetermined range in which the piston rod 21 extends to the outside of the cylinder 2 beyond the first maximum long side predetermined position. The maximum long-side characteristic in which the side damping force is in the hard state, and the extension-side damping force is in the hard state in the range where the piston rod 21 enters the inside of the cylinder 2 from the minimum long side predetermined position The passage area adjusting mechanisms 91 and 227 are provided to adjust the passage area of the orifices 88 and 225 depending on the position of the piston rod 21 so that the force becomes both characteristics of the minimum long side characteristic in which the force is soft. And, by means of the passage area adjusting mechanisms 91 and 227 for adjusting the damping force in a position sensitive manner as described above, the piston rod 21 is extended to the outside of the cylinder 2 further than the first predetermined range on the longest length side. The expansion side damping force is in a hard state in the second predetermined range. As described above, by using the passage area adjusting mechanisms 91 and 227 for positionally adjusting the damping force, abnormal noise and vibration when the piston rod 21 is completely extended are suppressed. As a result, the size is smaller than in the case where abnormal noise and vibration are suppressed only by the buffer 39, and a dedicated hydraulic pressure stopper is also unnecessary. Therefore, size reduction, cost reduction and weight reduction of the shock absorber 1 can be achieved.

  That is, the passage area adjusting mechanism 227 forms the small diameter hole 48 in the piston rod 21 so as to move along with the piston rod 21, and forms an orifice 225 by this and the metering pin 31 fixed on the cylinder 2 side. There is. The damping force is adjusted by changing the passage area of the orifice 225 by changing the outer diameter of the metering pin 31 depending on the axial position, and changing the amount of communication between the upper chamber 19 and the lower chamber 20. . When the piston rod 21 extends to the metering pin 31 of the passage area adjusting mechanism 227 as described above, the passage area of the orifice 225 is narrowed to reduce the amount of communication between the upper chamber 19 and the lower chamber 20. A large diameter shaft portion 254 is formed. As described above, by narrowing the passage area on the extension side of the orifice 225 where the flow passage area changes depending on the position of the piston rod 21, the extension side damping force is increased to function as a hydraulic pressure stopper. As a result, size reduction, cost reduction and weight reduction of the shock absorber 1 can be achieved.

  Moreover, when the shock absorber 1 is used in, for example, a suspension device of a vehicle, the extension side of the piston rod 21 is a range where a special damping performance is not required from the viewpoint of improving ride comfort and steering stability (passage Since adjustment of the passage area by the area adjustment mechanism 227 is essentially unnecessary), the degree of freedom in setting the damping force for improving the riding comfort and steering stability is limited even if the function of the hydraulic pressure stopper is given. There is no need to worry.

  In the above embodiment, although the case of having both the characteristics of the maximum long side first characteristic and the minimum long side characteristic has been described as an example, it is sufficient to have at least the maximum long side first characteristic.

Further, although the above embodiment shows an example in which the present invention is applied to a double cylinder type hydraulic shock absorber, the present invention is not limited to this but the outer cylinder 4 is eliminated and the opposite to the upper chamber 19 of the lower chamber 20 in the cylinder 2 It may be used for a mono-tube type hydraulic shock absorber which forms a gas chamber with a side slidable compartment, and can be used for any shock absorber.
In the above embodiment, a hydraulic shock absorber has been described as an example, but water or air can also be used as the fluid.

  The shock absorber according to this embodiment includes a cylinder in which a working fluid is enclosed, a piston slidably fitted in the cylinder, a piston defining the inside of the cylinder into two chambers, and the cylinder connected to the piston Provided in the first passage, a piston rod extending to the outside of the cylinder, a first passage and a second passage that communicate hydraulic fluid to flow between the two chambers by movement of the piston, and the piston A damping valve that suppresses the flow of the working fluid generated by the movement of the valve to generate a damping force, and an extension-side damping force in a first predetermined range in which the piston rod is extended to the outside of the cylinder beyond the maximum long side predetermined position Is in the soft state and the compression side damping force is in the hard state, and the piston rod is advanced into the cylinder from the minimum long side predetermined position. The second passage according to the position of the piston rod such that it has at least the maximum long side characteristic of the minimum long side characteristics in which the expansion side damping force is in the hard state and the compression side damping force is in the soft state in the range. A passage area adjusting mechanism for adjusting the passage area of the cylinder, and the passage area adjusting mechanism extends in a second predetermined range in which the piston rod extends further outside the cylinder than the first predetermined range It is characterized in that the side damping force is in a hard state. As described above, the shock absorber can be reduced in size, cost and weight to suppress abnormal noise and vibration when the piston rod is fully extended by using the passage area adjustment mechanism for position-sensitive adjustment of damping force. Can be

Reference Signs List 1 shock absorber 2 cylinder 18 piston 19 upper chamber 20 lower chamber 21 piston rod 32 passage in rod (second passage)
89 aisle (second aisle)
91, 227 passage area adjustment mechanism 101 passage (first passage)
102 aisle (first aisle)
140, 190 pilot room (second passage)
141, 191 Pilot room inflow passage (second passage)
147, 197 Damping valve 151, 154, 201, 204 Orifice (second passage)

Claims (1)

A cylinder in which the working fluid is sealed;
A piston slidably fitted in the cylinder to divide the inside of the cylinder into two chambers;
A piston rod connected to the piston and extended to the outside of the cylinder;
A first passage and a second passage in communication so that working fluid flows between the two chambers by movement of the piston;
A damping valve provided in the first passage to suppress the flow of the working fluid generated by the movement of the piston to generate a damping force;
A maximum long side characteristic in which the expansion side damping force is in a soft state and the compression side damping force is in a hard state in a first predetermined range in which the piston rod extends beyond the maximum long side predetermined position to the outside of the cylinder; And, in a range where the piston rod enters the inside of the cylinder from the predetermined position on the minimum length side, the extension side damping force becomes harder than the damping force of the maximum length side characteristic and the contraction side damping force is the maximum The minimum long side characteristic which becomes softer than the damping force of the long side characteristic, and the extension side damping force when the piston rod is between the maximum long side predetermined position and the minimum long side predetermined position, as with characteristics as a hard state than the damping force of the maximum length side characteristic soft than the damping force of the minimum length side characteristics, to adjust the passage area of the second passage by the position of the piston rod It includes a passage area control mechanism, and
The passage area adjusting mechanism is configured such that the expansion side damping force is harder than the damping force of the maximum long side characteristic in a second predetermined range in which the piston rod is further extended to the outside of the cylinder than the first predetermined range. A shock absorber characterized by being in the state of

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