JP2012031900A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of reducing a hitting sound.SOLUTION: This shock absorber includes a housing 55 forming a flow passage of at least a part of passages 90 and 91 for making a working fluid flow out of one chamber 12 in a cylinder 10 by the movement of a piston 11, a free piston 57 movably arranged in the housing 55 and defining the second passages 90 and 91 into the upstream side and the downstream side, and spring members 58 and 59 for holding the free piston 57 in a neutral position in the housing 55. An elastic member 60 having elasticity in a construction material itself, is arranged in the axial direction between the free piston 57 and the housing 55.

Description

  The present invention relates to a shock absorber.

  Among the shock absorbers, there is a shock absorber whose damping force characteristics are variable according to the vibration state (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 7-19642 (FIG. 4)

  The above-described shock absorber is provided with a free piston that moves in the housing, and the free piston is held at a neutral position in the housing by a spring member. With such a structure, a hitting sound may be generated when the free piston moves to the moving end.

  Therefore, an object of this invention is to provide the buffer which can reduce a hit sound.

  In order to achieve the above object, according to the present invention, an elastic member having elasticity in the material itself is disposed between the axial direction of the free piston and the housing.

  According to the present invention, the hitting sound can be reduced.

It is sectional drawing which shows the buffer of 1st Embodiment which concerns on this invention. It is sectional drawing of the principal part which shows the buffer of 1st Embodiment which concerns on this invention. It is sectional drawing of the principal part which shows the buffer of 2nd Embodiment which concerns on this invention. It is sectional drawing of the principal part which shows the buffer of 3rd Embodiment which concerns on this invention. It is sectional drawing of the principal part which shows the buffer of 4th Embodiment which concerns on this invention.

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

“First Embodiment”
1st Embodiment which concerns on this invention is described based on FIG. 1 and FIG.

  As shown in FIG. 1, the shock absorber according to the first embodiment is a so-called monotube hydraulic shock absorber, and has a bottomed cylindrical cylinder 10 in which an oil liquid as a working fluid is sealed. A piston 11 is slidably fitted in the cylinder 10, and the inside of the cylinder 10 is partitioned into two chambers, an upper chamber 12 and a lower chamber 13, by the piston 11. The piston 11 includes a piston main body 14, an annular sliding member 15 attached to the outer peripheral surface thereof, and a portion through which the piston rod 16 connected to the piston main body 14 is inserted into the piston main body 14.

  The piston main body 14 is connected to one end of a piston rod 16, and the other end of the piston rod 16 is inserted through a rod guide 17 and an oil seal 18 mounted on the opening side of the cylinder 10, so that the cylinder 10 It is extended to the outside.

  The piston rod 16 is made of metal, and has a main shaft portion 20 and an attachment shaft portion 21 on one end side to which the piston main body 14 is attached with a smaller diameter. The piston rod 16 is provided with a rebound stopper 24 and a buffer body 25 by inserting the piston rod 16 inside the main shaft portion 20 between the piston 11 and the rod guide 17. A partition body 26 for defining the lower chamber 13 on the piston 11 side is slidably provided in the cylinder 10 on the bottom side of the cylinder 10 with respect to the piston 11. Oil liquid is sealed in the upper chamber 12 and the lower chamber 13 in the cylinder 10, and a high-pressure (about 20 to 30 atmospheres) gas is sealed in a chamber 27 defined by the partition body 26 as the lower chamber 13. Has been.

  As shown in FIG. 2, the upper chamber 12 and the lower chamber 13 are communicated with the piston body 14, and the piston 11 moves from the upper chamber 12 toward the lower chamber 13 in the movement toward the upper chamber 12, that is, in the extension stroke. A plurality of passages (first passages 30a are shown in FIG. 2 because of the cross-section in FIG. 2) and movement of the piston 11 to the lower chamber 13 side, that is, in the contraction process, from the lower chamber 13 to the upper chamber. A plurality of passages (first passages) 30 b (only one place is shown in FIG. 2 because of the cross-section in FIG. 2) from which the oil liquid flows toward 12 are provided. Half of these passages 30a are formed at an equal pitch in the circumferential direction with one passage 30b interposed therebetween, and one side in the axial direction of piston 11 (upper side in FIG. 2) has a diameter. The other side in the axial direction (the lower side in FIG. 2) is open radially inward on the outer side in the direction.

  A damping force generating mechanism 32a that generates a damping force is provided in the half of the passages 30a. The damping force generation mechanism 32 a is disposed on the lower chamber 13 side in the axial direction of the piston 11 and is attached to the attachment shaft portion 21 of the piston rod 16. The passage 30a constitutes an extension-side passage through which oil liquid passes when the piston 11 moves to the extension side where the piston rod 16 extends out of the cylinder 10, and a damping force generating mechanism provided for these passages. 32a constitutes an extension-side damping force generation mechanism that generates a damping force by controlling the flow of the oil liquid in the extension-side passage 30a.

  The remaining half of the passages 30b are formed at an equal pitch in the circumferential direction with one passage 30a interposed therebetween, and the other side in the axial direction of the piston 11 (lower side in FIG. 2). Is open radially outward and one side in the axial direction (upper side in FIG. 2) is open radially inward.

  A damping force generation mechanism 32b that generates a damping force is provided in the remaining half of the passages 30b. The damping force generation mechanism 32 b is disposed on the upper chamber 12 side in the axial direction of the piston 11 and is attached to the attachment shaft portion 21 of the piston rod 16. The passage 30b constitutes a contraction-side passage through which oil liquid passes when the piston 11 moves to the contraction side where the piston rod 16 enters the cylinder 10, and a damping force generation mechanism 32b provided for these passages. Constitutes a contraction-side damping force generation mechanism that generates a damping force by controlling the flow of oil in the contraction-side passage 30b.

  A damping force variable mechanism 35 is attached to the piston rod 16 further on the end side than the piston 11 of the attachment shaft portion 21.

  The piston main body 14 has a substantially disc shape, and an insertion hole 38 is formed in the center of the piston main body 14 so as to penetrate the mounting shaft portion 21 of the piston rod 16 through the axial direction.

  At the end of the piston main body 14 on the lower chamber 13 side, a seat portion 41a constituting the damping force generating mechanism 32a is formed in an annular shape at an opening position of one end of the extension-side passage 30a. At the end of the piston body 14 on the upper chamber 12 side, a seat portion 41b constituting the damping force generating mechanism 32b is formed in an annular shape at the opening position of one end of the contraction side passage 30b.

  In the piston main body 14, the side opposite to the insertion hole 38 of the seat portion 41a is an annular step portion 42b whose axial direction height is lower than that of the seat portion 41a, and a contraction-side passage at the position of the step portion 42b. The other end of 30b is open. Further, passage grooves (orifices) 43a that are recessed in the axial direction are formed in the seat portion 41a so as to extend outward from the passage 30a in the radial direction of the piston 11 and to be stepped out to the stepped portion 42b. Similarly, in the piston body 14, the opposite side of the seat portion 41b from the insertion hole 38 is an annular step portion 42a having a lower axial height than the seat portion 41b, and extends to the position of the step portion 42a. The other end of the side passage 30a is open. In addition, although not shown in the drawings, the seat portion 41b is also formed with passage grooves (orifices) that are recessed in the axial direction so as to extend outward from the passage 30b in the radial direction of the piston 11 and exit to the step portion 42a. Yes.

  The damping force generation mechanism 32a includes an annular disk valve 45a that can be seated simultaneously on the entire seat portion 41a, and an annular disk that has a smaller diameter than the disk valve 45a and is disposed on the opposite side of the piston body 14 of the disk valve 45a. The spacer 46a has an annular valve restricting member 47a that has a larger diameter than the spacer 46a and is disposed on the opposite side of the spacer 46a from the piston body 14. The disc valve 45a is configured by overlapping a plurality of annular discs, and opens the passage 30a by separating from the seat portion 41a. Further, the valve restricting member 47a restricts deformation beyond the regulation in the opening direction of the disc valve 45a.

  Similarly, the damping force generating mechanism 32b is disposed on the opposite side of the disk body 45b of the annular disk valve 45b that can be seated simultaneously on the entire seat portion 41b, and having a smaller diameter than the disk valve 45b. An annular spacer 46b, and an annular valve restricting member 47b that is larger in diameter than the spacer 46b and is disposed on the opposite side of the piston 46 from the spacer 46b. The valve restricting member 47 b is in contact with the shaft step portion 48 at the end of the main shaft portion 20 of the piston rod 16 on the mounting shaft portion 21 side. The disc valve 45b is also configured by overlapping a plurality of annular discs, and the passage 30b is opened by separating from the seat portion 41b. Further, the valve restricting member 47b restricts deformation beyond the regulation in the opening direction of the disc valve 45b.

  In the present embodiment, the damping force generating mechanisms 32a and 32b are examples of the disc valve of the inner periphery clamp. However, the present invention is not limited to this, and any mechanism that generates a damping force may be used. For example, the disc valve is attached with a coil spring. It may be a lift type valve, or may be a poppet valve.

  A male screw 50 is formed at the tip of the piston rod 16, and a damping force variable mechanism 35 is screwed to the male screw 50. The damping force varying mechanism 35 includes a metal lid member 53 formed with a female screw 52 that is screwed into the male screw 50 of the piston rod 16 and a bottomed cylinder attached to the lid member 53 so that the opening side thereof is closed. A housing 55 composed of a metal-shaped housing body 54, a metal free piston 57 that is slidably inserted into the housing 55, and a space between the free piston 57 and the lid member 53 of the housing 55. A metal coil spring (spring member) 58 that is compressed and deformed when the free piston 57 moves to one side in the axial direction, and the free piston 57 is interposed between the free piston 57 and the housing main body 54 of the housing 55. A metal coil spring (spring member) 59 that is compressed and deformed when 57 moves to the other side in the axial direction and the free piston 57 is baked. And an elastic member 60 made of beam.

  The lid member 53 is formed mainly by cutting, and has a substantially cylindrical lid cylinder portion 62 and a disk-like lid extending radially outward from the axial end of the lid cylinder portion 62. And a flange portion 63. The female screw 52 described above is formed on the inner peripheral portion of the lid cylinder portion 62.

  The housing main body 54 is formed mainly by cutting, and has a substantially cylindrical housing tube portion 65 and a housing bottom portion 66 that closes an end portion of the housing tube portion 65 in the axial direction. Although the housing is described as a cylinder, the inner peripheral surface is preferably circular in cross section, but the outer peripheral surface may be noncircular in cross section such as a polygon.

  Here, the lid member 53 is inserted into the housing main body 54 from the opening side with the lid tube portion 62 being the front side, and in this state, the end portion on the opening side of the housing tube portion 65 is added to the inside. By being fastened, the lid member 53 is fixed and integrated with the housing main body 54 to constitute the housing 55. A communication hole (orifice) 67 penetrating in the axial direction is formed in the center of the housing bottom 66.

  The free piston 57 is formed by pressing from a plate material, and includes a substantially cylindrical piston cylinder portion 71, a piston bottom portion 72 that closes one end portion in the axial direction of the piston cylinder portion 71, and a piston cylinder portion 71. And an annular piston flange portion 73 protruding radially outward from the other axial end portion.

  The elastic member 60 is formed so as to cover the piston cylinder part 71 side in the radial direction of the piston bottom part 72 of the free piston 57, the entire piston cylinder part 71, and the entire piston flange part 73. The elastic member 60 may be formed of a gel or the like contained in a bag in addition to rubber as long as the elastic member 60 is made of a material having elasticity in the material itself other than the coil spring or the leaf spring.

  Specifically, the elastic member 60 includes an annular plate-like portion 75 that covers the piston cylinder portion 71 side in the axial direction of the piston bottom portion 72, and an inner peripheral surface of the piston cylinder portion 71 that is continuous with the annular plate-like portion 75. A cylindrical portion 76 that covers the annular thick portion 77 that is continuous with the cylindrical portion 76 and covers the opposite side of the piston flange portion 73 in the piston flange portion 73 in the axial direction. A cylindrical portion 78 that covers the outer peripheral surface of the piston flange portion 73, an annular plate-like portion 79 that continues to the cylindrical portion 78 and covers the piston cylindrical portion 71 side in the axial direction of the piston flange portion 73, and an annular plate A cylindrical portion 80 that covers the outer peripheral surface of the piston cylindrical portion 71 continuously to the cylindrical portion 79, and an annular thickness that covers the opposite side of the piston bottom portion 72 in the axial direction from the piston bottom portion 72 continuously to the cylindrical portion 80. It consists of a meat part 81.

  The inner circumferential surface of the annular thick wall portion 77 has a larger diameter as it moves away from the free piston 57 in the axial direction, and slidably contacts the housing tube portion 65 of the housing body 54 on the outer circumferential surface.

  The inner circumferential surface of the annular thick part 81 has a larger diameter as it moves away from the free piston 57 in the axial direction, and its outer circumferential surface becomes smaller as it moves away from the free piston 57 in the axial direction. A through groove 82 penetrating in the radial direction is formed at the tip of the annular thick portion 81 opposite to the free piston 57 in the axial direction.

  The coil spring 58 is interposed between the lid flange portion 63 of the lid member 53 and the piston bottom portion 72 of the free piston 57, and one end side is in contact with the lid flange portion 63 and the other end side is fixed to the piston bottom portion 72. The elastic member 60 is in contact with the annular plate-like portion 75.

  The coil spring 59 is interposed between the housing bottom portion 66 of the housing main body 54 and the piston flange portion 73 of the free piston 57, and one end side is in contact with the housing bottom portion 66 and the other end side is fixed to the piston flange portion 73. The elastic member 60 is in contact with the annular plate-shaped portion 79 of the elastic member 60.

  The coil springs 58 and 59 are urged from both sides in the axial direction so as to hold the free piston 57 in the neutral position in the housing 55. When the free piston 57 moves from the neutral position in the direction in which the coil spring 58 is contracted, the annular thick portion 77 of the elastic member 60 is positioned on the lid flange portion of the lid member 53 before the coil spring 58 is contracted to the minimum length. 63 abuts. Further, when the free piston 57 moves from the neutral position in the direction in which the coil spring 59 is contracted, the annular thick portion 81 of the elastic member 60 is positioned at the bottom of the housing body 54 before the coil spring 59 is contracted to the minimum length. 66 abuts against 66.

  The damping force variable mechanism 35 is attached by screwing the female screw 52 of the housing 55 to the male screw 50 of the mounting shaft portion 21 of the piston rod 16 in a pre-assembled state. The lid flange portion 63 comes into contact with the valve regulating member 47a of the damping force generation mechanism 32a, and the damping force generation mechanism 32a, the piston main body 14, and the damping force generation mechanism 32b are sandwiched between the shaft step portion 48 of the piston rod 16. It will be. Note that the outer diameter of the damping force variable mechanism 35, that is, the outer diameter of the housing main body 54 is set to be smaller than the inner diameter of the cylinder 10 so as not to cause flow path resistance.

  In the piston rod 16, a passage hole 85 is formed along the radial direction at an end position of the main shaft portion 20 on the attachment shaft portion 21 side. A passage hole 86 communicating with the passage hole 85 is formed in the attachment shaft portion 21. Are formed along the axial direction. Therefore, the upper chamber 12 communicates with the inside of the housing 55 of the variable damping force mechanism 35 by these passage holes 85 and 86, and specifically, is defined by the housing 55, the elastic member 60, and the free piston 57. It communicates with the upper chamber communication chamber 87. The lower chamber 13 communicates with the inside of the housing 55 through a communication hole 67 formed in the housing bottom 66 of the housing 55. Specifically, the lower chamber 13 is defined by the housing 55, the elastic member 60, and the free piston 57. It communicates with the lower chamber communication chamber 88. The elastic member 60 disposed between the housing main body 54 and the free piston 57 is disposed so as to always seal between the housing 55 and the free piston 57, and the upper chamber communication chamber 87 and the lower chamber communication chamber 88. Always block communication with.

  The passage holes 85 and 86 and the upper chamber communication chamber 87 constitute a passage (second passage) 90 through which oil flows out from one upper chamber 12 in the cylinder 10 by the movement of the piston 11 toward the upper chamber 12. The communication hole 67 and the lower chamber communication chamber 88 constitute a passage (second passage) 91 through which oil flows from one lower chamber 13 in the cylinder 10 by the movement of the piston 11 toward the lower chamber 13. Therefore, a part of the passage 90 is formed in the housing 55, and the entire passage 91 is formed in the housing 55. The free piston 57 is movably provided in the housing 55 and defines passages 90 and 91 upstream and downstream. The passages 30 a and 30 b and the passage 90 are provided in the piston 11 including a part of the piston rod 16.

  Here, in the extension stroke in which the piston rod 16 moves to the extension side, the oil liquid flows from the upper chamber 12 to the lower chamber 13 via the passage 30a. However, when the piston speed is in a very low speed range, The oil liquid introduced into the passage 30 a from 12 basically enters the lower chamber 13 through a constant orifice defined by a passage groove 43 a formed in the piston 11 and a disk valve 45 a contacting the seat portion 41 a. In the flow, a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated. When the piston speed increases and reaches a low speed region, the oil introduced into the passage 30a from the upper chamber 12 basically passes between the disc valve 45a and the seat portion 41a while opening the disc valve 45a. It will flow into the lower chamber 13. For this reason, a damping force having a valve characteristic (a damping force is substantially proportional to the piston speed) is generated.

  In the contraction process in which the piston rod 16 moves to the contraction side, the oil liquid flows from the lower chamber 13 through the passage 30b to the upper chamber 12, but when the piston speed is in a very low speed region, the passage from the lower chamber 13 The oil introduced into 30b basically flows into the upper chamber 12 through a constant orifice defined by a passage groove (not shown) formed in the piston 11 and a disk valve 45 that abuts the seat portion 41b. In this case, a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated. When the piston speed increases and reaches a low speed region, the oil introduced into the passage 30b from the lower chamber 13 basically passes between the disc valve 45b and the seat portion 41b while opening the disc valve 45b. It will flow into the upper chamber 12. For this reason, a damping force having a valve characteristic (a damping force is substantially proportional to the piston speed) is generated.

  Here, when the piston speed is low, that is, the region where the frequency in the very low speed region (for example, 0.05 m / s) is relatively high (for example, 7 Hz or more) is, for example, vibration caused by unevenness on the fine surface of the road surface. In such a situation, it is preferable to reduce the damping force. Similarly, even when the piston speed is low, the region where the frequency is relatively low (for example, 2 Hz or less) is vibration such as wobbling caused by the roll of the vehicle body. In such a situation, the damping force Is preferable.

  Correspondingly, the damping force variable mechanism 35 described above makes the damping force variable according to the frequency even when the piston speed is low as well. That is, when the piston speed is low and the frequency of the reciprocating motion of the piston 11 is increased, the pressure in the upper chamber 12 is increased in the extension stroke, and the damping force variable mechanism via the passage holes 85 and 86 of the piston rod 16. The lower chamber 13 is introduced into the upper chamber communication chamber 87 from the upper chamber 12 through the communication hole 67 constituting the downstream orifice in the passage 91 from the lower chamber communication chamber 88 of the damping force variable mechanism 35. The free piston 57 moves toward the lower chamber 13 in the axial direction against the urging force of the coil spring 59 on the lower chamber 13 in the axial direction. When the free piston 57 moves to the lower chamber 13 side in the axial direction in this way, the oil liquid is introduced from the upper chamber 12 into the upper chamber communication chamber 87, and is introduced from the upper chamber 12 into the passage 30a and the damping force. The flow rate of the oil liquid flowing through the generating mechanism 32a and flowing into the lower chamber 13 is reduced. Thereby, a damping force falls.

  In the subsequent contraction stroke, the pressure in the lower chamber 13 increases, so that oil is introduced from the lower chamber 13 into the lower chamber communication chamber 88 of the damping force varying mechanism 35 through the communication hole 67 that forms the upstream orifice in the passage. The free piston 57 that has been moved to the lower chamber 13 side in the axial direction until the oil liquid is discharged from the upper chamber communication chamber 87 to the upper chamber 12 through the passage holes 85 and 86 of the piston rod 16 is It moves to the upper chamber 12 side in the axial direction against the biasing force of the coil spring 58 on the upper chamber 12 side in the direction. Thus, when the free piston 57 moves to the upper chamber 12 side in the axial direction, the oil liquid is introduced into the lower chamber communication chamber 88 from the lower chamber 13, and is introduced into the passage 30b from the lower chamber 13 and the damping force. The flow rate of the oil liquid flowing through the generating mechanism 32b and flowing into the upper chamber 12 is reduced. Thereby, a damping force falls.

  In the region where the frequency of the piston 11 is high, the frequency of the movement of the free piston 57 also increases, and as a result, oil liquid flows from the upper chamber 12 to the upper chamber communication chamber 87 each time the above-described extension stroke occurs. In each contraction stroke, the oil liquid flows from the lower chamber 13 to the lower chamber communication chamber 88, so that the damping force is maintained in a reduced state as described above.

  On the other hand, when the piston speed is low when the piston speed is low, the frequency of movement of the free piston 57 also follows and decreases, so the oil liquid is transferred from the upper chamber 12 to the upper chamber communication chamber 87 at the beginning of the extension stroke. However, after that, the free piston 57 compresses the coil spring 59 and stops on the lower chamber 13 side in the axial direction, and the oil liquid does not flow from the upper chamber 12 to the upper chamber communication chamber 87. Thus, the flow rate of the oil liquid flowing through the lower chamber 13 through the damping force generating mechanism 32a is not reduced, and the damping force is increased.

  Even in the subsequent contraction stroke, oil liquid flows from the lower chamber 13 to the lower chamber communication chamber 88 in the initial stage, but thereafter the free piston 57 compresses the coil spring 58 and stops on the upper chamber 12 side in the axial direction. Since the oil liquid does not flow from the lower chamber 13 to the lower chamber communication chamber 88, the flow rate of the oil liquid that is introduced from the lower chamber 13 into the passage 30b and flows through the damping force generation mechanism 32b to the upper chamber 12 does not decrease. Becomes higher.

  In the first embodiment, the annular thick portions 77 and 81 of the elastic member 60 having elasticity in the material itself are disposed between the free piston 57 and the housing 55 in the axial direction. Even if the free piston 57 moves greatly in the axial direction, the annular thick portions 77 and 81 first come into contact with the housing 55 to compress and deform to absorb the moving energy of the free piston 57, and the free piston 57 directly The contact with the housing 55 or the piston rod 16 and the contraction of the coil springs 58 and 59 to the minimum length are restricted. Therefore, it is possible to reduce the hitting sound generated when the free piston 57 directly collides with the housing 55 or the piston rod 16 and the hitting sound generated when the coil springs 58 and 59 contract to the minimum length. Thereby, the abnormal noise which generate | occur | produces from a buffer can be reduced.

  In addition, since the speed of the free piston 57 can be reduced from the position before the moving end using the elastic member 60, it is possible to improve a transient characteristic in which the damping force is switched from soft to hard.

  Moreover, since the elastic member 60 is baked and provided on the free piston 57, these can be handled as one component. Therefore, assembly work man-hours and management costs can be reduced.

“Second Embodiment”
Next, the second embodiment will be described mainly on the basis of FIG. 3 with a focus on differences from the first embodiment. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

  In the second embodiment, the damping force variable mechanism 35 is partially different from the first embodiment. That is, first, a lid member 53 that is partially different from the first embodiment is used. The lid member 53 has a configuration in which a cylindrical portion 101 is provided on the outer peripheral side of the lid flange portion 63. A tip surface 101a opposite to the lid flange portion 63 in the axial direction of the cylindrical portion 101 is along the direction orthogonal to the axis.

  Further, in the second embodiment, a housing body 54 that is partially different from the first embodiment is used. That is, an annular inner annular protrusion 102 that protrudes radially inward from the housing cylinder 65 is formed at the boundary position between the housing cylinder 65 and the housing bottom 66. The side opposite to the housing bottom 66 in the axial direction of the inner annular protrusion 102 is an inclined surface 102 a that becomes larger in diameter as the distance from the housing bottom 66 increases.

  Furthermore, in 2nd Embodiment, the free piston 105 different from 1st Embodiment is used. The free piston 105 of the second embodiment includes a cylindrical piston cylinder portion 106, a piston bottom portion 107 that closes the piston cylinder portion 106 at its axial center position, and an outer peripheral side of the axial center position of the piston cylinder portion 106. And a piston flange portion 108 that extends outward from the front end. The both sides in the axial direction of the piston flange portion 108 are inclined surfaces 108a and 108b that similarly become smaller in diameter as they are separated from each other in the axial direction. Although this free piston 105 is made of metal, it is formed mainly by cutting.

  A coil spring 58 is disposed between the lid flange portion 63 of the lid member 53 and the piston bottom portion 107 of the free piston 105 facing the lid flange portion 63, and the housing bottom portion 66 of the housing main body 54 and the piston bottom portion of the free piston 105 facing the same. A coil spring 59 is arranged between the coil 107 and the coil spring 59.

  In the second embodiment, the elastic member 110 made of a rubber O-ring is disposed between the inclined surface 108 a of the piston flange portion 108 of the free piston 105 and the tip surface 101 a of the cylindrical portion 101 of the lid member 53. An elastic member 111 that is disposed and made of a rubber O-ring is disposed between the inclined surface 108 b of the piston flange portion 108 of the free piston 105 and the inclined surface 102 a of the inner annular protrusion 102 of the housing body 54. That is, the elastic members 110 and 111 are arranged between the free piston 105 and the housing 55 in the axial direction. The elastic members 110 and 111 seal the gap between the housing cylinder portion 65 of the housing main body 54 and the free piston 105.

  The coil springs 58 and 59 are urged from both sides in the axial direction so as to hold the free piston 105 in the neutral position in the housing 55. When the free piston 105 moves from the neutral position in the direction of contracting the coil spring 58, the elastic member 110 is pushed by the tip surface 101a of the cylindrical portion 101 of the lid member 53 and the inclined surface 108a of the piston flange portion 108 of the free piston 105. The free piston 105 is stopped before the free piston 105 comes into contact with the lid flange portion 63 and before the coil spring 58 is contracted to the minimum length. Further, when the free piston 105 moves from the neutral position in the direction in which the coil spring 59 is contracted, the elastic member 111 has an inclined surface 102a of the inner annular protrusion 102 of the housing body 54 and an inclined surface 108b of the piston flange portion 108 of the free piston 105. The free piston 105 is stopped before the free piston 105 abuts against the housing bottom 66 before the coil spring 59 is shortened to the minimum length.

  According to the second embodiment described above, since the elastic members 110 and 111 having elasticity in the material itself are arranged between the free piston 105 and the housing 55 in the axial direction, the same as in the first embodiment. In addition, since the O-rings are used as the elastic members 110 and 111, the component cost can be reduced.

“Third Embodiment”
Next, the third embodiment will be described mainly based on FIG. 4 with a focus on differences from the first embodiment. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

  In the third embodiment, the damping force variable mechanism 35 is partially different from the first embodiment. That is, first, a lid member 53 that is partially different from the first embodiment is used. The lid member 53 is formed with an annular lid step 120 that protrudes radially outward from the lid cylinder portion 62 at a boundary position between the lid cylinder portion 62 and the lid flange portion 63.

  In the third embodiment, a housing body 54 that is partially different from the first embodiment is used. In other words, the housing main body 54 is formed with an annular housing step 121 that protrudes radially inward from the housing cylinder 65 at a boundary position between the housing cylinder 65 and the housing bottom 66.

  Furthermore, in 3rd Embodiment, the free piston 124 different from 1st Embodiment is used. The free piston 124 of the third embodiment is formed mainly by cutting, and has a substantially cylindrical piston cylinder part 125, and a piston bottom part 126 that closes one axial end of the piston cylinder part 125, It has an annular piston flange portion 127 that protrudes radially outward from the other axial end portion of the piston tube portion 125.

  The piston bottom portion 126 is formed with a chamfered portion 130 having a smaller diameter as it is farther from the piston tube portion 125 on the side opposite to the piston tube portion 125 in the axial direction on the outer peripheral side. A recess 131 that is recessed in the axial direction is formed on the side opposite to the portion 125. The piston flange 127 is formed with a radially inwardly-sealed seal groove 133 at an intermediate position in the axial direction of the outer peripheral portion thereof, and the piston cylinder portion 125 in the axial direction of the inner peripheral side thereof. On the opposite side, a chamfered portion 134 having a larger diameter as the distance from the piston cylindrical portion 125 increases is formed. In the seal groove 133, a seal ring 135 made of an O-ring that seals the gap between the housing cylinder portion 65 of the housing main body 54 and the free piston 124 is disposed.

  The coil spring 58 is interposed between the lid step portion 120 of the lid member 53 and the piston bottom portion 126 of the free piston 124, and the coil spring 59 is connected to the housing step portion 121 of the housing main body 54. The free piston 124 is interposed between and in contact with the piston flange portion 127.

  In the third embodiment, the elastic member 110 made of a rubber O-ring is fitted to the outside of the lid step portion 120 with a tightening margin in a state where the elastic member 110 is in contact with the lid flange portion 63 of the lid member 53. ing. In addition, an elastic member 111 made of a rubber O-ring is fitted to the inner side of the housing stepped portion 121 of the housing main body 54 with an allowance while being in contact with the housing bottom 66 of the housing main body 54. These elastic members 110 and 111 are also arranged between the free piston 124 and the housing 55 in the axial direction.

  The coil springs 58 and 59 are urged from both sides in the axial direction so as to hold the free piston 124 in the neutral position in the housing 55. When the free piston 124 moves from the neutral position in the direction in which the coil spring 58 is contracted, the elastic member 110 comes into contact with the chamfered portion 134 of the piston flange portion 127 of the free piston 124, and is elastically deformed to be coil spring. The contraction to the minimum length of 58 and the contact of the free piston 124 with the lid member 53 are restricted. In addition, when the free piston 124 moves from the neutral position in the direction in which the coil spring 59 is contracted, the elastic member 111 comes into contact with the chamfered portion 130 of the free piston 105, elastically deforms, and the minimum length of the coil spring 59 is reached. And the contact of the free piston 124 with the housing main body 54 is restricted.

  According to the third embodiment described above, since the elastic members 110 and 111 having elasticity in the material itself are arranged between the free piston 124 and the housing 55 in the axial direction, the same as in the first embodiment. In addition, since the O-rings are used as the elastic members 110 and 111, the component cost can be reduced.

  In the second and third embodiments, the elastic members 110 and 111 can be put in a bag in addition to rubber as long as the elastic members 110 and 111 are made of a material having elasticity in the material itself other than the coil spring and the leaf spring. Alternatively, it may be formed of a gel.

“Fourth Embodiment”
Next, the fourth embodiment will be described mainly with reference to FIG. 5 with a focus on differences from the first embodiment. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

  In the fourth embodiment, the extension-side damping force generation mechanism 32a is different from the first embodiment. The damping force generation mechanism 32a of the fourth embodiment includes a disc 200, an intermediate disc 201, a relief valve 202, a valve member 203, a disc valve (attenuation) in order from the axial upper chamber 12 side, that is, the piston main body 14 side. Valve) 205, spacer 206, and valve regulating member 207.

  The valve member 203 includes a perforated disk-shaped bottom portion 210 extending in the direction perpendicular to the axis, a cylindrical inner cylindrical portion 211 formed on the inner peripheral side of the bottom portion 210, and an outer peripheral side of the bottom portion 210. And a cylindrical outer cylindrical portion 212 formed along the axial direction. A plurality of through holes 213 penetrating in the axial direction are formed in the bottom portion 210. The space between the inner cylindrical portion 211 and the outer cylindrical portion 212 of the valve member 203 including the plurality of through holes 213 communicates with the passage 30a of the piston main body 14 so that the upper chamber 12 and the lower chamber 13 And a passage (first passage) 215 from which the oil liquid flows from the upper chamber 12 toward the lower chamber 13 by moving the piston 11 toward the upper chamber 12 side. The outer cylindrical portion 212 is formed with an annular sheet portion 216 on the side of the lower chamber 13 in the axial direction. Although not shown, the sheet portion 216 has a passage groove penetrating in the radial direction. Is formed. The passage may be formed by providing a notch on the outer peripheral side of the disk valve 215 in contact with the seat portion 216 instead of the passage groove formed in the seat portion 216.

  The disc 200 has a disk shape with a smaller diameter than the seat portion 41a of the piston main body 14. The intermediate disk 201 has the same diameter as the disk 200, and a plurality of notches 220 are formed on the outer peripheral side thereof.

  The damping valve 202 is provided between the passage 30a of the piston main body 14 and the passage 215 of the valve member 203, and controls the flow of oil liquid generated by sliding of the piston 11 to generate a damping force. A perforated disc-like disc 222 that can be seated on the seat portion 41a of the main body 14 and an annular seal member 223 made of a rubber material fixed to the outer peripheral side opposite to the piston main body 14 of the disc 222. Yes. A through hole 224 that penetrates in the axial direction is formed in the disk 222 radially inward of the seal member 223. The damping valve 202 is positioned in the radial direction so that the through-hole 224 is positioned on the inner side of the seat portion 41a and can communicate with the cutout portion 220 of the intermediate disk 201. The seal member 223 contacts the inner peripheral surface of the outer cylindrical portion 212 of the valve member 203 to seal the gap between the damping valve 202 and the outer cylindrical portion 212 of the valve member 203. The space between the outer cylindrical portion 212, the bottom portion 210 and the inner cylindrical portion 211 of the valve member 203 and the damping valve 202 causes the inner pressure to act on the damping valve 202 in the valve closing direction in contact with the seat portion 41a. A back pressure chamber 225 is provided. In addition, an oil passage formed by the damping valve 202 including the through hole 224 of the damping valve 202 and the notch 220 of the intermediate disk 201 and the intermediate disk 201 is transferred to the back pressure chamber 225 from the upper chamber 12 in the cylinder 10. It is a back pressure chamber inlet oil passage 226 for introducing the liquid. When the damping valve 202 is opened away from the seat portion 41 a of the piston body 14, the fluid from the passage 30 a passes through the lower chamber 13 via the radial flow path 227 between the piston body 14 and the valve member 203. Shed.

  The disc valve 205 has an annular shape that can be seated on the seat portion 216 of the valve member 203. The disc valve 205 opens the back pressure chamber 225 by being separated from the seat portion 216, and is configured by overlapping a plurality of annular discs. The spacer 206 has an annular shape with a smaller diameter than the disk valve 205, and the valve regulating member 207 has an annular shape with a larger diameter than the spacer 206. The valve restricting member 207 restricts deformation of the disc valve 205 beyond the regulation in the opening direction. The disk valve 205 is provided in the back pressure chamber 225, and causes the oil in the back pressure chamber 225 to flow downstream when the valve is opened.

  When the damping force generation mechanism 32a different from the first embodiment is provided, when only the damping force generation mechanism 32a acts in the extension stroke in which the piston rod 16 moves to the extension side, the piston speed is low. The fluid from the upper chamber 12 includes a passage 30a, a passage 215 including a back pressure chamber inlet oil passage 226 and a back pressure chamber 225, a passage groove and a disk (not shown) formed in the seat portion 216 of the valve member 203. It flows into the lower chamber 13 through the discharge orifice formed by the valve 205, and a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated. For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force becomes relatively high as the piston speed increases. Further, when the piston speed increases, the oil from the upper chamber 12 passes between the disc valve 205 and the seat portion 216 while opening the disc valve 205 via the passage 30a and the passage 215, and passes through the lower chamber. 13, the damping force of the valve characteristic (the damping force is approximately proportional to the piston speed) is generated. For this reason, as for the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force is slightly lowered with respect to the increase of the piston speed.

  When the piston speed is further increased, the relationship between the force (hydraulic pressure) acting on the relief valve 202 is larger than the closing force applied from the back pressure chamber 225 by the opening force applied from the passage 30a. Therefore, in this region, the relief valve 202 opens as the piston speed increases, and in addition to the flow to the lower chamber 13 passing between the disc valve 205 and the seat portion 216, the piston body 14 and the valve member 203 Since the oil liquid flows into the lower chamber 13 via the flow path 227 between the two, the increase in the damping force is suppressed. The characteristic of the damping force with respect to the piston speed at this time is that there is almost no increase rate of the damping force with respect to the increase of the piston speed. When an impact shock occurs due to a road surface step or the like having a high piston speed and a relatively high frequency, the shock is sufficiently absorbed by suppressing an increase in damping force with respect to an increase in piston speed as described above.

  Further, after the impact shock occurs, when the amplitude is reduced and the piston speed is reduced at the same frequency as that at the time of occurrence, the force acting on the relief valve 202 is such that the force in the opening direction applied from the passage 30a is the back pressure chamber. The force in the closing direction applied from 225 is smaller, and the relief valve 202 moves in the closing direction. Accordingly, the flow from the upper chamber 12 to the lower chamber 13 due to the opening of the relief valve 202 is reduced, and the flow to the lower chamber 13 passing between the disc valve 205 and the seat portion 216 is mainly performed. The rate of increase of the damping force with respect to the increase in speed will increase. As a result, the unsprung variation after the impact shock occurs is suppressed.

  In the fourth embodiment, the damping force variable mechanism 250 is different from the first embodiment.

  The variable damping force mechanism 250 according to the fourth embodiment includes a housing 253 having a substantially cylindrical housing body 251 and a bottom lid member 252 attached to one end side of the housing body 251 in the axial direction. The housing body 251 has a female screw 255 into which the bottom cover member 252 is screwed, a storage hole portion 256 having a smaller diameter than the female screw 255, and a smaller diameter than the storage hole portion 256 in the center from the attachment side of the bottom cover member 252. A taper hole 257, a female screw 258 screwed into the male screw 50 of the piston rod 16, and a mounting hole 259 having a larger diameter than the female screw 258 are formed in the axial direction to form a cylinder. The bottom cover member 252 has a male screw 261 that is screwed into the female screw 255 on the outer peripheral surface, and a communication hole 262 that penetrates along the axial direction at the center.

  The housing 253 is disposed in the housing hole portion 256 of the housing body 251 and is paired with a bottomed cylindrical retainer 265 disposed so as to contact the bottom surface of the housing hole portion 256 and the inner surface of the bottom lid member 252. 266, a pair of spacers 267, 268 disposed inside each of the retainers 265, 266, and a pair of disk-shaped members disposed on the opposite side of the retainers 265, 266 in the axial direction of the spacers 267, 268. Base plates 269, 270, elastic members 271, 272 made of a pair of sheet-like rubbers disposed on the opposite side of the base plates 269, 270 in the axial direction, and these elastic members 271, 271 270, which is provided between the base plates 269 and 270 and is provided between the base plates 269 and 270. And a Jo guide member 273.

  In the retainers 265 and 266, through holes 275 and 276 are formed in the center of the bottom portion along the axial direction. Further, the side portion extending from the bottom portion of the retainers 265 and 266 into the radial gap between the guide member 273 and the housing main body 251 extends in the radial direction and then extends in the axial direction to the side opposite to the bottom portion. Slits 265A and 266A are formed. In addition, through holes (orifices) 277 and 278 are formed in the center of the base plates 269 and 270 along the axial direction. The spacers 267 and 268 are sandwiched between the through holes 275 and 276 of the retainers 265 and 266 and the through holes 275 and 276 of the base plates 269 and 270 so that they can always communicate with each other. The through holes 277 and 278 have a smaller diameter than the through holes 275 and 276.

  The guide member 273 is formed with an annular projecting portion 280 projecting outward at a predetermined position in the middle in the axial direction. A seal ring 281 that seals a gap with the housing body 251 is formed on the outer periphery of the projecting portion 280. An annular holding groove 282 is formed. Further, the guide member 273 is formed with a plurality of through holes 283 and a plurality of through holes 284 penetrating in the radial direction on both outer sides in the axial direction of the protruding portion 280.

  In addition, the damping force variable mechanism 250 is disposed between the free piston 287 slidably fitted in the guide member 269 along the axial direction thereof, and between the free piston 287 and the base plates 269 and 270. And a pair of coil springs 288 and 289 that hold the free piston 287 in a neutral position and generate a resistance force against the displacement. In the free piston 287, a pair of spring holding holes 291 and 292 for holding the coil springs 288 and 289 are formed in the axial direction on both sides in the axial direction, and radially in a predetermined range in the axial direction of the outer peripheral surface. A recessed annular groove 293 is formed. The groove portion 293 is switched between communicating and blocking with the through holes 283 and 284 according to the position of the free piston 287 with respect to the guide member 273.

  The coil springs 288 and 289 are urged from both sides in the axial direction so as to hold the free piston 287 in the neutral position in the housing 253. When the free piston 287 moves from the neutral position in the direction in which the coil spring 288 is contracted, the elastic member 271 contacts one end surface of the free piston 287 in the axial direction, so that the coil spring 288 is contracted to the minimum length. The contact of the free piston 287 to the base plate 269 is restricted. Further, when the free piston 287 moves from the neutral position in the direction in which the coil spring 289 is contracted, the elastic member 272 contacts the other end surface of the free piston 287 in the axial direction, so that the coil spring 289 is contracted to the minimum length. Further, the contact of the free piston 287 with the base plate 270 is restricted.

  The damping force variable mechanism 250 of the fourth embodiment includes the passage holes 105 and 106 of the piston rod 16 and the piston rod 16 side between the guide member 273, the free piston 287, and the base plate 269 on the piston rod 16 side. An upper chamber communication chamber 295 communicating with the upper chamber 12 is formed through the through hole 275 of the retainer 265 and the through hole 277 of the base plate 269 on the piston rod 16 side. Further, a through hole 278 in the base plate 270 and a through hole 276 in the retainer 266 opposite to the piston rod 16 are provided between the guide member 273, the free piston 287, and the base plate 270 on the opposite side to the piston rod 16. A lower chamber communication chamber 296 communicating with the lower chamber 13 through the communication hole 262 of the bottom cover member 252 is formed.

  In the damping force variable mechanism 250 of the fourth embodiment, in the neutral position of the free piston 287, the groove portion 293 of the free piston 287 has all the through holes 283, 284 of the guide member 273 and the slits 265A, 266A of the retainers 265, 266. For example, when the free piston 287 moves from the neutral position to the lower chamber 13 side in the axial direction with respect to the housing 253 during the extension stroke, the coil spring 288 on the upper chamber 12 side in the axial direction is extended while lowering in the axial direction. The chamber side coil spring 289 is contracted, and the upper chamber 12 side oil is introduced into the upper chamber communication chamber 295. At this time, in the free piston 287, the groove 293 closes the through hole 283 on the upper chamber 12 side in the axial direction, and communicates with only the through hole 284 on the lower chamber 13 side in the axial direction.

  When the free piston 287 moves to the upper chamber 12 side in the axial direction in the subsequent contraction stroke, the coil spring 288 on the upper chamber 12 side in the axial direction is contracted while the coil spring 289 on the lower chamber side in the axial direction is extended, and the lower chamber communication The oil solution on the lower chamber 13 side is introduced into the chamber 296. At this time, the free piston 287 passes through the state in which the groove portion 293 communicates with the through holes 283 and 284 on both sides in the axial direction, closes the through hole 284 on the lower chamber side in the axial direction, and passes through the upper chamber 12 side in the axial direction. It will be in the state which communicates only with the hole 283. FIG.

  When the free piston 287 moves toward the lower chamber 13 in the axial direction with respect to the housing 253 in the subsequent extension stroke, the coil spring 289 on the lower chamber 13 side in the axial direction is contracted while the coil spring 288 on the upper chamber 12 side in the axial direction is extended. In other words, the free piston 287 operates in the same manner as described above after passing through the neutral position where the groove portion 293 communicates with the through holes 283 and 284 on both sides in the axial direction.

  According to the fourth embodiment described above, since the elastic members 271 and 272 having elasticity are disposed between the free piston 287 and the housing 253 in the axial direction, the same as in the first embodiment. Since the sheet-like rubber material is used as the elastic members 271 and 272, the component cost can be reduced.

  Also in the fourth embodiment, the elastic members 271 and 272 are made of a material having elasticity in the material itself other than the coil spring and the leaf spring, in addition to rubber, a gel put in a bag, etc. May be formed.

10 cylinder 11 piston 12 upper chamber (chamber)
13 Lower room (room)
16 piston rod 30a, 30b passage (first passage)
90, 91 passage (second passage)
32a, 32b Damping force generating mechanism 55, 253 Housing 57, 105, 124, 287 Free piston 58, 59 Coil spring (spring member)
60,110,111,271,272 Elastic member

Claims (2)

A cylinder filled with a working fluid;
A piston that is slidably fitted in the cylinder and divides the cylinder into two chambers;
A piston rod connected to the piston and extending outside the cylinder;
A first passage and a second passage through which working fluid flows from one chamber in the cylinder by the movement of the piston;
A damping force generating mechanism that is provided in the first passage and generates a damping force;
A housing in which at least a part of the flow path of the second passage is formed;
A free piston movably provided in the housing and defining the second passage upstream and downstream;
A spring member for holding the free piston in a neutral position in the housing;
Consists of
The shock absorber according to claim 1, wherein an elastic member having elasticity is disposed between the free piston and the housing in an axial direction.   The shock absorber according to claim 1, wherein the elastic member is provided by being baked on the free piston.

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