JP6010496B2 - Shock absorber - Google Patents

Description

  It is related with improvement of a shock absorber.

  In general, the shock absorber attenuates vibrations of a vehicle, equipment, structure, or the like. For example, in a shock absorber used in a straddle-type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle, a liquid chamber filled with a working fluid is formed inside, and an annular shape is fixed to the cylinder and closes one side of the liquid chamber. A rod guide, a piston rod that passes through the rod guide and enters and exits the cylinder as the shock absorber body expands and contracts; a piston that is held at the tip of the piston rod and divides the liquid chamber into a rod side chamber and a piston side chamber; A piston passage formed in the piston that communicates the rod side chamber and the piston side chamber; a damping valve that provides resistance to the hydraulic fluid passing through the piston passage; and a sliding contact with the inner peripheral surface of the cylinder on the side opposite to the piston rod. A free piston for closing the other side, an urging means for urging the free piston toward the liquid chamber, and the free piston against the urging force of the urging means. When the amount retreated releasing the hydraulic fluid in the cylinder out of the cylinder it is those and a (relief to) the relief means.

  In the above shock absorber, the hydraulic fluid in one chamber, which is pressurized by the piston when the shock absorber expands and contracts as the piston rod enters and exits the cylinder, moves to the other chamber through the piston passage. A damping force can be generated. Further, since the liquid chamber is pressurized by the urging means, the responsiveness of the generation of the damping force can be improved, and even if the hydraulic fluid in the cylinder increases or expands, the relief means can An excessive increase in internal pressure can be suppressed (for example, Patent Documents 1 to 3).

JP 2005-30534 A JP 2010-270832 A JP 2011-117533 A

  Here, the gas remaining in the liquid chamber at the time of injecting the hydraulic fluid and the bubbles formed by the deposition of the gas dissolved in the hydraulic fluid move upward in the liquid chamber and gather at the upper end of the liquid chamber. Is generally set upside down, and the relief means is arranged on the upper side so that the gas collected at the upper end of the liquid chamber during the relief can be discharged out of the cylinder together with the working fluid.

  On the other hand, when the shock absorber is set upright, gas collects in the rod side chamber located above the liquid chamber, so that the rod guide and piston rod can be discharged from the rod guide side. A relief means for forming a gap between the seal member and the piston rod is formed along the axial direction on the outer periphery of the piston rod, and the gas in the rod side chamber is combined with the working fluid from the gap within a predetermined stroke range. There is a proposal that allows discharge (relief) out of the cylinder. According to the proposed shock absorber, even if the shock absorber is set upright, the gas can be discharged out of the cylinder together with the working fluid during the relief, so the extension side damping force due to the gas accumulating in the rod side chamber Generation delay can be suppressed. However, in the predetermined stroke range, the rod side chamber communicates with the outside of the cylinder and the rod side chamber is not pressurized, so that there is a possibility that the extension side damping force is insufficient.

  Therefore, an object of the present invention is to provide a shock absorber capable of suppressing the extension side damping force from being insufficient even when the hydraulic fluid in the rod side chamber is relieved from the rod guide side to the outside of the cylinder. .

  Means for solving the above-mentioned problems include a shock absorber body comprising an outer tube and an inner tube entering and exiting the outer tube and interposed between the vehicle body and the wheel, and the shock absorber body connected to the wheel side. A cylinder standing in the axial center of the cylinder, a liquid chamber formed in the cylinder and filled with hydraulic fluid, an annular rod guide fixed to the cylinder and closing the vehicle body side of the liquid chamber, and a vehicle body side A piston rod that is coupled and penetrates the axial center of the rod guide and enters and exits the cylinder; a piston that is held at the tip of the piston rod and divides the liquid chamber into a rod side chamber and a piston side chamber; A shock absorber comprising a rebound member that absorbs impact at the time, and is held in the inner periphery of the rod guide and is in an annular shape that is in sliding contact with the outer peripheral surface of the piston rod. A ring member, an annular stopper held on the liquid chamber side of the rod guide, and an axially formed outer periphery of the piston rod between the piston rod and the seal member within a predetermined stroke range. And a relief means for forming a gap in the coil rod, wherein the rebound member is supported by a sheet member fixed to the outer periphery of the piston rod and is disposed on the outer periphery of the piston rod, and the rod of the coil spring And an annular spring guide that is fitted to the guide side end and slidably contacts the outer peripheral surface of the piston rod. The spring guide is in contact with the stopper within the predetermined stroke range.

  According to the shock absorber of the present invention, even if the hydraulic fluid in the rod side chamber is relieved from the rod guide side to the outside of the cylinder, it is possible to suppress the shortage of the extension side damping force.

It is the front view which notched and showed the buffer which concerns on one embodiment of this invention partially. It is the figure which expanded and showed the principal part of FIG. The example of the change of the spring guide in the buffer which concerns on one embodiment of this invention is shown, It is the figure which cut | disconnected and expanded the left half of the changed spring guide.

  A shock absorber according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  As shown in FIG. 1, the shock absorber D according to the present embodiment includes a shock absorber body T that includes an outer tube 1 and an inner tube 2 that enters and exits the outer tube 1 and is interposed between a vehicle body and a wheel. A cylinder 3 that is connected to the wheel side and stands on the axial center of the shock absorber body T, a liquid chamber P that is formed in the cylinder 3 and is filled with hydraulic fluid, and is fixed to the cylinder 3. An annular rod guide 30 that closes the vehicle body side of the liquid chamber P, a piston rod 4 that is connected to the vehicle body side and penetrates the axial center of the rod guide 30 and enters and exits the cylinder 3, and the piston rod 4 A piston 6 that is held at the tip and divides the liquid chamber P into a rod-side chamber p1 and a piston-side chamber p2 and a rebound member (not shown) that absorbs an impact at the time of maximum extension are provided.

  Further, the shock absorber D includes an annular seal member C1 that is held on the inner periphery of the rod guide 30 and is in sliding contact with the outer peripheral surface of the piston rod 4, and an annular seal member that is held on the liquid chamber side of the rod guide 30. A stopper 33 and a relief means A1 formed along the axial direction on the outer periphery of the piston rod 4 to form a gap a (FIG. 2) between the piston rod 4 and the seal member C1 within a predetermined stroke range; It has. The rebound member is supported by a sheet member 4h (FIG. 2) fixed to the outer periphery of the piston rod 4 and is disposed on the outer periphery of the piston rod 4, and the rod guide side of the coil spring S4. An annular spring guide 41 which is fitted to the end portion and slidably contacts the outer peripheral surface of the piston rod 4 is provided, and the spring guide 41 contacts the stopper 33 within the predetermined stroke range.

  The shock absorber D is used for a front fork that suspends a front wheel in a straddle-type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle. Since the structure of this front fork is well known, it is not shown in detail, but a pair of shock absorbers standing on both sides of the front wheel (only one shock absorber D is shown and the other shock absorber is not shown), A vehicle body side bracket that connects these shock absorbers and is connected to a vehicle body frame that is a skeleton of the vehicle body, and a wheel side bracket 20 that connects each shock absorber to the front axle. In the present embodiment, the present invention is embodied in one or both of a pair of shock absorbers constituting the front fork. The shock absorber D according to the present invention may be used other than the front fork, and may be used for a rear cushion for suspending a rear wheel in a saddle type vehicle or a vehicle other than the saddle type vehicle. .

  Hereinafter, one shock absorber D in which the present invention is embodied will be described in detail. The shock absorber D includes a telescopic shock absorber main body T composed of an outer tube 1 and an inner tube 2, a cylinder 3 standing on an axial center portion of the shock absorber main body T, and a vehicle body side opening end 3 a of the cylinder 3. An annular rod guide 30 that is attached to the piston rod 4, a piston rod 4 that is supported by the rod guide 30 and enters and exits the cylinder 3, is held at the tip of the piston rod 4 and is in sliding contact with the inner peripheral surface of the cylinder 3. A piston 6 that can move in the axial direction, a base rod 7 that stands on the axial center of the cylinder 3 on the side opposite to the piston rod, and a base member 8 that is held at the tip of the base rod 7 are formed in an annular shape. A free piston 5 slidably in contact with the outer peripheral surface of the base rod 7 and the inner peripheral surface of the cylinder 3 and movable in the axial direction in the cylinder 3 is shown in FIG. And a biasing means S1 for biasing the side.

  A reservoir R is formed between the shock absorber main body T and the cylinder 3. In the reservoir R, working fluid is stored, and gas is accommodated on the upper side through the liquid surface of the working fluid. Since the communication hole 2a is formed in the inner tube 2, the working fluid can freely move between the cylindrical gap t1 formed between the outer tube 1 and the inner tube 2 and the reservoir R. It has become.

  On the other hand, in the cylinder 3, a liquid chamber P partitioned from the reservoir R by the rod guide 30 and a back chamber Q partitioned from the liquid chamber P by the free piston 5 and accommodating the biasing means S1 are formed. The liquid chamber P and the back chamber Q are filled with hydraulic fluid. The liquid chamber P includes an upper rod side chamber p1 and a lower piston side chamber p2 defined by the piston 6, and a liquid reservoir chamber p3 defined by the base member 8 and the piston side chamber p2.

  The shock absorber main body T constitutes the outer shell of the shock absorber D. Since the vehicle body side bracket is fixed to the outer tube 1 and the wheel side bracket 20 is fixed to the inner tube 2, an impact caused by road surface unevenness is applied to the wheel. The inner tube 2 can go in and out of the outer tube 1 to be expanded and contracted. The upper opening of the shock absorber body T is closed by a cap member 10 that is screwed to the inner periphery of the upper end portion of the outer tube 1, and the lower opening of the shock absorber body T is a wheel that is screwed to the outer periphery of the lower end portion of the inner tube 2. The lower opening of the cylindrical gap t1 that is closed by the side bracket 20 and formed between the overlapping portions of the outer tube 1 and the inner tube 2 is held on the inner periphery of the outer tube 1 and is the outer periphery of the inner tube 2 The seal members C2 and C3 are made of an annular dust seal and an oil seal that are in sliding contact with each other. For this reason, the liquid and gas accommodated in the shock absorber main body T are prevented from leaking to the outside air side. In the present embodiment, the outer tube 1 is connected to the vehicle body side and the inner tube 2 is connected to the wheel side so that the front fork is set upside down, but the outer tube 1 is connected to the wheel side. In addition, the inner tube 2 may be connected to the vehicle body side so that the front fork is set upright.

  A suspension spring S2 made of a coil spring is accommodated in the shock absorber main body T, and the shock absorber main body T is urged in the extending direction to elastically support the vehicle body. In the present embodiment, the suspension spring S <b> 2 is supported at the lower end by a cylindrical oil lock case 34 standing on the rod guide 30, and supported at the upper end by the cylindrical spring receiver 11. Since the spring receiver 11 can be driven up and down in FIG. 1 by the adjuster 12 for adjusting the reaction force attached to the cap member 10, the reaction force of the suspension spring S2 can be adjusted. In the present embodiment, the suspension spring S2 is formed of a coil spring. However, the suspension spring S2 may be formed of an air spring, and the suspension spring S2 may not be accommodated in the shock absorber body T.

  Further, in the shock absorber main body T, a pair of bushes B1 for supporting the inner tube 2 so as to freely enter and exit the outer tube 1 is formed in a cylindrical gap t1 formed between the overlapping portions of the outer tube 1 and the inner tube 2. B2 is arranged. Further, since the hydraulic fluid is stored in the cylindrical gap t1 and the hydraulic fluid is supplied from the communication hole 2a formed in the inner tube 2, the sliding surfaces of both the bushes B1 and B2 are lubricated with the hydraulic fluid. can do.

  The cylinder 3 standing at the axial center of the shock absorber body T is connected to the wheel side. Specifically, the wheel side bracket 20 includes a connecting portion 20a connected to the axle, and a cylindrical portion 20b that stands up from the connecting portion 20a, and the cylinder 3 is disposed on the inner periphery of the cylindrical portion 20b. It is screwed into the inner periphery of the bottomed cylindrical bottom member 32 positioned on the formed step surface 20c. Further, since the bottom member 32 is pressed against the step surface 20c at the tip of the inner tube 2 screwed into the inner periphery of the cylindrical portion 20b and is fixed to the vehicle body side bracket 20, the cylinder 3 includes the bottom member 32 and It is connected to the wheel side via the wheel side bracket 20 and stands up at the axial center portion of the inner tube 2. Further, a large inner diameter portion 3b having an inner diameter larger than that of other portions is formed in the lower portion of the cylinder 3, and a communication hole penetrating the thickness of the large inner diameter portion 3b. 3c is formed.

  An annular rod guide 30 attached to the opening 3a on the vehicle body side of the cylinder 3 closes the vehicle body side of the liquid chamber P, and is inserted into the cylinder 3 and on the inner periphery of the cylinder 3 as shown in FIG. There are provided an insertion portion 30a to be screwed, a projection portion 30b which is connected to the insertion portion 30a and protrudes from the cylinder 3, and an annular flange portion 30c which projects from the projection portion 30b to the outer periphery. The projecting portion 30b is formed with a lateral hole 30d penetrating in the radial direction above the flange portion 30c, and an annular bush B3 is fitted on the inner periphery of the rod guide 30 above the lateral hole 30d. The annular seal member C1 and the stopper 33 are held vertically side by side below the horizontal hole 30d.

  The stopper 33 is disposed on the liquid chamber side of the seal member C1 so that a spring guide 41 constituting a rebound member described later can come into contact therewith. Further, the inner diameter of the stopper 33 is formed larger than the outer diameter of a large-diameter portion 4 c of the piston rod 4 described later, so that the stopper 33 does not interfere with the piston rod 4.

  Further, a cylindrical oil lock case 34 stands on the upper side of the projecting portion 30b, and the oil lock case 34, together with an oil lock piece 40 (FIG. 1) attached to the outer periphery of the piston rod 4, is an oil lock mechanism. The shock at the time of the most compression of the shock absorber D is mitigated.

  The piston rod 4 supported by the rod guide 30 and going into and out of the cylinder 3 is held in a state of being suspended from the cap member 10 and is connected to the vehicle body via the cap member 10, the outer tube 1 and the vehicle body side bracket. The lower side penetrates the shaft center portion of the rod guide 30 and is supported by the rod guide 30 via the bush B3 so as to be movable in the axial direction. The piston rod 4 includes a cylindrical shaft member 4a supported by a rod guide 30 and an annular center rod 4b that holds the piston 6. As shown in FIG. 2, the shaft member 4a slides on the bush B3. A cylindrical large-diameter portion 4c in contact with it, a conical slope portion 4d connected to the lower side of the large-diameter portion 4c in FIG. 2 and gradually reduced in diameter from the large-diameter portion 4c, and the slope portion 4d in FIG. A cylindrical small-diameter portion 4e that is connected to the lower side and has an outer diameter smaller than the large-diameter portion 4c, and a screw portion that is connected to the lower side of the small-diameter portion 4e in FIG. 4f. On the other hand, the center rod 4b is connected to the nut portion 4g that is screwed into the screw portion 4f, the sheet member 4h that protrudes from the nut portion 4g to the outer periphery, and the lower portion of the nut portion 4g in FIG. 4i (FIG. 1).

  When the seal member C1 held by the rod guide 30 is opposed to the large-diameter portion 4c of the piston rod 4, the seal member C1 is in sliding contact with the large-diameter portion 4c so that there is no gap on the inner periphery of the seal member C1. However, when the seal member C1 reaches the slope portion 4d, a gap a is formed on the inner periphery of the seal member C1. The piston rod 4 can be stroked until the seal member C1 faces the small diameter portion 4e. However, even when the seal member C1 faces the small diameter portion 4e, a gap a is formed on the inner periphery of the seal member C1. That is, in the present embodiment, the slope portion 4c and the small diameter portion 4e constitute the relief means A1, and when the piston rod 4 is retracted from the cylinder 3 by a predetermined amount and the slope portion 4c reaches the seal member C1. A gap a is formed between the seal member C1 and the piston rod 4 in a predetermined stroke range (hereinafter referred to as a relief stroke range) until the piston rod 4 is most retracted from the cylinder 3. The hydraulic fluid in the rod side chamber p1 is allowed to escape to the reservoir R through a and the lateral hole 30d, that is, can be relieved. Note that the configuration of the relief means A1 is not limited to the above, and can be changed as appropriate. For example, even if the relief means A1 includes only the slope portion 4d, grooves and cuts formed on the outer periphery of the piston rod 4 can be used. It may consist of a notch. Further, the rod guide 30 may be relieved through the sliding gap between the bush B3 and the piston rod 4 without providing the horizontal hole 30d.

  Further, in the piston rod 4, a push rod 14 driven in the axial direction by an adjuster 13 for adjusting a damping force attached to the cap member 10 is inserted into a cylindrical shaft member 4 a. Further, as shown in FIG. 1, the center rod 4b is provided with a bypass passage 4j that connects the rod side chamber p1 and the piston side chamber p2, and a needle valve 15 that throttles the bypass passage 4j, and a needle valve 15 An urging spring S3 urging to the push rod side is accommodated. When the adjuster 13 for adjusting the damping force is operated to drive the push rod 14 and the needle valve 15 is pushed into the bypass path 4j, the bypass path 4j On the contrary, when the needle valve 15 is withdrawn from the bypass passage 4j, the passage area of the bypass passage 4j can be increased.

  Further, a rebound member that is compressed with the stopper 33 when the shock absorber D is fully extended is provided on the outer periphery of the piston rod 4. As shown in FIG. 2, the rebound member has a lower end fitted to the outer periphery of the nut portion 4g of the center rod 4b and supported by the seat member 4h, and a coil spring S4 disposed on the outer periphery of the piston rod 4. And an annular spring guide 41 which is fitted to the rod guide side end portion which is the upper end portion of the coil spring S4 and which is attached to the outer periphery of the piston rod 4 so as to be movable in the axial direction. That is, since the rebound member is supported on the lower side by the seat member 4 h fixed to the piston rod 4, the piston rod 4 approaches the rod guide 30 as the piston rod 4 is retracted, and the piston rod 4 is retracted from the cylinder 3 by a predetermined amount. When this occurs, the spring guide 41 contacts the stopper 33. When the piston rod 4 is further retracted from the cylinder 3, the coil spring S4 is compressed to generate a predetermined reaction force so that the shock at the time of the maximum extension of the shock absorber D can be absorbed. Further, since the spring guide 41 is in sliding contact with the outer peripheral surface of the small diameter portion 4e of the piston rod 4, if the spring guide 41 is brought into contact with the stopper 33 within the relief stroke range, the stopper 33 and the piston Since the space between the rods 4 can be simply sealed with the spring guide 41, the movement of the hydraulic fluid from the rod side chamber p1 to the reservoir R can be suppressed and the pressure of the rod side chamber p1 can be increased.

  The piston 6 held at the tip of the piston rod 4 is formed in an annular shape, and is fixed to the outer periphery of the holding portion 4i of the center rod 4b with a nut 60 as shown in FIG. The piston 6 is formed with an extension side and pressure side piston passage 6a (only the extension side piston passage 6a is shown, and the pressure side piston passage is not shown) communicating the rod side chamber p1 and the piston side chamber p2. The outlet of the piston passage 6a on the extension side is closed so that it can be opened and closed, and only the flow of the hydraulic fluid that moves the piston passage 6a on the extension side from the rod side chamber p1 to the piston side chamber p2 is allowed and the flow in the opposite direction is blocked. The opening of the side damping valve 61 and the pressure side piston passage (not shown) is closed so that it can be opened and closed, and only the flow of hydraulic fluid that moves the pressure side piston passage from the piston side chamber p2 to the rod side chamber p1 is allowed and the flow in the opposite direction is blocked. A pressure side check valve 62 is stacked.

  The base rod 7 standing on the axial center portion of the cylinder 3 on the side opposite to the piston rod is held upright on the bottom member 32 screwed to the outer periphery of the large inner diameter portion 3b of the cylinder 3, and the base member 8 is The rod 7 is fixed to the tip of the rod 7 with a nut 80. The base member 8 is formed with an extension-side and pressure-side base passage 8a (only the extension-side base passage 8a is shown, and the pressure-side base passage is not shown) communicating the piston-side chamber p2 and the liquid reservoir chamber p3. In addition, the outlet of the extension-side base passage 8a is closed so that it can be opened and closed, and only the flow of hydraulic fluid that moves the extension-side base passage 8a from the liquid reservoir chamber p3 to the piston-side chamber p2 is allowed. The expansion side check valve 81 to be blocked and the outlet of the pressure side base passage (not shown) are closed so as to be openable and closed, and only the flow of hydraulic fluid that moves the pressure side base passage from the piston side chamber p2 to the liquid storage chamber p3 is allowed. A compression side damping valve 82 for blocking the flow in the opposite direction is stacked.

  The free piston 5 that is formed in an annular shape and slidably contacts the outer peripheral surface of the base rod 7 and the inner peripheral surface of the cylinder 3 and moves in the cylinder 3 in the axial direction is formed from an annular O-ring that slidably contacts the outer peripheral surface of the base rod 7. An inner peripheral seal 5a and an outer peripheral seal 5b made of an annular O-ring that is slidably in contact with the inner peripheral surface of the cylinder 3. The wheel side of the liquid chamber P is closed and the liquid reservoir chamber p3 is partitioned from the rear chamber Q. doing. However, when the free piston 5 moves downward in FIG. 1 by a predetermined amount and the outer peripheral seal 5b reaches the large inner diameter portion 3b of the cylinder 3, a gap is generated between the outer peripheral seal 5b and the cylinder 3, and the liquid storage chamber p3. The hydraulic fluid can be released to the reservoir R through the gap and the communication hole 3c of the cylinder 3. That is, in the present embodiment, the large inner diameter portion 3c of the cylinder 3 also functions as a relief means A2 that releases the hydraulic fluid in the cylinder 3 to the outside of the cylinder 3, and the shock absorber D according to the present embodiment is connected to the piston rod 4. The relief means A1 formed and the relief means A2 formed in the cylinder 3 are provided. Hereinafter, in order to distinguish these relief means, the relief means A1 formed on the piston rod 4 is referred to as an upper relief means A1, and the relief means A2 formed on the cylinder 3 is referred to as a lower relief means A2.

  The biasing means S1 for biasing the free piston 5 upward in FIG. 1 is formed of a coil spring in the present embodiment, and is accommodated in the back chamber Q and is compressed between the bottom member 32 and the free piston 5. While being intervened. The urging means S1 pressurizes the liquid chamber P via the free piston 5 to improve the response of the damping force generation in the shock absorber D.

  Hereinafter, the operation of the shock absorber D in the present embodiment will be described.

  When the shock absorber D in which the inner tube 2 retreats from the outer tube 1 and the piston rod 4 retreats from the cylinder 3, the seal member C1 of the rod guide 30 faces the large-diameter portion 4c of the piston rod 4, and the relief is performed. When it is outside the stroke range, the hydraulic fluid in the rod side chamber p1 pressurized by the piston 6 passes through the extension side piston passage 6a and the bypass passage 4j and moves to the piston side chamber p2, and the piston rod retreated from the cylinder 3 Since the volume of hydraulic fluid passes through the extension-side base passage 8a and moves from the liquid storage chamber p3 to the piston-side chamber p2, the shock absorber D has the extension-side damping valve 61, the needle valve 15, and the extension-side check valve 81. The extension side damping force is generated due to the resistance. Since the valve opening pressure of the extension side check valve 81 is set low, the extension side damping force is mainly due to the resistance of the extension side damping valve 61 and the needle valve 15. The resistance by the needle valve 15 can be adjusted by the adjuster 13 for adjusting the damping force, so that the extension side damping force can be adjusted by the adjuster 13. Further, in this case, the free piston 5 moves upward in FIG. 1 to reduce the liquid reservoir chamber p3 and expand the rear chamber Q, so that the hydraulic fluid in the reservoir R passes through the communication hole 3c of the cylinder 3 to the rear surface. Move to room Q.

  Further, when the shock absorber D is extended, when the piston rod 4 is retracted from the cylinder 3 by a predetermined amount and enters the relief stroke range, the seal member C1 faces the upper relief means A1, so that the piston rod 4 and the seal member C1 A gap a is generated between the two and the hydraulic fluid in the rod side chamber p1 moves to the reservoir R through the gap a and the lateral hole 30d of the rod guide 30. The gas remaining in the liquid chamber P at the time of injecting the hydraulic fluid and the bubbles formed by the deposition of the gas dissolved in the hydraulic fluid are moved upward in the liquid chamber P to the rod side chamber p1 that is the upper end of the liquid chamber P. Since they collect, this gas can be discharged (relieved) out of the cylinder 3 together with the hydraulic fluid from the gap a and the lateral hole 30d. Further, within this relief stroke range, the spring guide 41 comes into contact with the stopper 33, so that the coil spring S4 is compressed to generate a predetermined reaction force with the withdrawal of the piston rod 4, and the rod side chamber The movement of the hydraulic fluid from p1 to the reservoir R is suppressed. Therefore, it is possible to increase the pressure of the rod side chamber p1, and to suppress the shortage of the extension side damping force. Moreover, according to the said structure, the expansion side damping force can be supplemented with the reaction force of coil spring S4.

  On the contrary, when the shock absorber D in which the inner tube 2 enters the outer tube 1 and the piston rod 4 enters the cylinder 3, the hydraulic fluid in the piston side chamber p <b> 2 pressurized by the piston 6 is compressed side (not shown). The piston fluid passes through the piston passage and the bypass passage 4j and moves to the rod side chamber p1, and the hydraulic fluid for the piston rod volume that has entered the cylinder 3 passes through the pressure side base passage (not shown) from the piston side chamber p2 to the liquid storage chamber p3. In order to move, the shock absorber D generates a pressure-side damping force due to the resistance of the pressure-side check valve 62, the needle valve 15, and the pressure-side damping valve 82. Since the valve opening pressure of the pressure side check valve 62 is set low, the pressure side damping force is mainly due to the resistance of the pressure side damping valve 82. In this case, the free piston 5 moves downward in FIG. 1 to enlarge the liquid storage chamber p3 and reduce the back chamber Q, so that the working fluid in the back chamber Q passes through the communication hole 3c of the cylinder 3 and is stored in the reservoir 3 Move to R.

  In addition, when the piston rod 4 enters, the hydraulic fluid is repeatedly drawn into the cylinder 3 so that the hydraulic fluid in the cylinder 3 increases or the volume of the hydraulic fluid expands due to a temperature rise. When the amount of entry of the rod 4 increases, the free piston 5 moves greatly downward in FIG. 1 and the outer peripheral seal 5b of the free piston 5 faces the lower relief means A2, so that the outer peripheral seal 5b and the cylinder 3 A gap is formed between the reservoir 3 and the hydraulic fluid in the liquid storage chamber p3 moves to the reservoir R through the gap and the communication hole 3c of the cylinder 3. Therefore, it is possible to suppress an excessive increase in the cylinder internal pressure by the lower relief means A2.

  It continues and demonstrates the effect of the buffer D in this Embodiment.

  In the present embodiment, the shock absorber D is composed of an outer tube 1 and an inner tube 2 that enters and exits the outer tube 1 and is connected to the shock absorber body T interposed between the vehicle body and the wheel, and the wheel side. A cylinder 3 standing at the axial center of the shock absorber body T, a liquid chamber P formed in the cylinder 3 and filled with hydraulic fluid, and fixed to the cylinder 3 on the vehicle body side of the liquid chamber P An annular rod guide 30 that closes the body, a piston rod 4 that is connected to the vehicle body side, passes through the axial center of the rod guide 30 and enters and exits the cylinder 3, and is held by the tip of the piston rod 4 and is A piston 6 that divides the liquid chamber P into a rod side chamber p1 and a piston side chamber p2 and a rebound member (not shown) that absorbs an impact at the time of maximum extension are provided.

  Further, the shock absorber D includes an annular seal member C1 that is held on the inner periphery of the rod guide 30 and is in sliding contact with the outer peripheral surface of the piston rod 4, and an annular seal member that is held on the liquid chamber side of the rod guide 30. An upper relief formed on the outer periphery of the stopper 33 and the piston rod 4 along the axial direction to form a gap a between the piston rod 4 and the seal member C1 within a relief stroke range (predetermined stroke range). Means A1. The rebound member is supported by a seat member 4h fixed to the outer periphery of the piston rod 4 and is arranged on the outer periphery of the piston rod 4, and the upper side of the coil spring S4 in FIGS. And an annular spring guide 41 that is slidably contacted with the outer peripheral surface of the piston rod 4 and is fitted within the relief stroke range (predetermined stroke range). It comes into contact with the stopper 33.

  According to the above configuration, even if the hydraulic fluid in the rod side chamber p1 is relieved from the rod guide side to the outside of the cylinder 3 by the upper relief means A1, if the spring guide 41 comes into contact with the stopper 33, the rod side chamber p1 to the cylinder 3 Since the flow of the working fluid moving to the outside is suppressed, it is possible to increase the pressure of the rod side chamber p1, and to suppress the shortage of the extension side damping force.

  In this embodiment, the spring guide 41 is brought into direct contact with the stopper 33. However, the spring guide side surface, which is the lower surface of the stopper 33 in FIGS. A rubber sheet may be attached to either one or both of the upper stopper side surfaces. In this case, the generation of abnormal noise when the stopper 33 and the spring guide 41 come into contact with each other is suppressed, and the stopper 33 and the spring guide 41 are in close contact with each other via the rubber sheet. Can be further suppressed.

  In the present embodiment, the spring guide 41 is directly slidably contacted with the outer periphery of the piston rod 4, but an annular bush B4 is fitted to the inner peripheral surface of the spring guide 41 as shown in FIG. The spring guide 41 may be in sliding contact with the outer peripheral surface of the piston rod 4 via the bush B4. In this case, the sliding gap can be made narrower than in the case where the spring guide 41 is directly slidably contacted with the outer periphery of the piston rod. In this case as well, the hydraulic fluid from the rod side chamber p1 to the outside of the cylinder 3 is removed. The movement can be further suppressed.

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

a Clearance A1 Relieving means B4 Bushing C1 Seal member D Buffer P Liquid chamber p1 Rod side chamber p2 Piston side chamber S1 Energizing means S4 Coil spring T Buffer body 1 Outer tube 2 Inner tube 3 Cylinder 4 Piston rod 4h Seat member 5 Free piston 6 Piston 30 Rod guide 33 Stopper 41 Spring guide

Claims (4)

A shock absorber body comprising an outer tube and an inner tube entering and exiting the outer tube and interposed between the vehicle body and the wheel; a cylinder connected to the wheel side and standing at the axial center of the shock absorber body; A liquid chamber formed in the cylinder and filled with hydraulic fluid, an annular rod guide fixed to the cylinder and closing the vehicle body side of the liquid chamber, and an axis center of the rod guide connected to the vehicle body side A piston rod that penetrates the part and enters and exits the cylinder, a piston that is held at the tip of the piston rod and divides the liquid chamber into a rod side chamber and a piston side chamber, and a rebound member that absorbs shock at the time of maximum extension. In the shock absorber provided,
An annular seal member that is held on the inner periphery of the rod guide and is in sliding contact with the outer peripheral surface of the piston rod, an annular stopper that is held on the liquid chamber side of the rod guide, and an outer periphery of the piston rod in the axial direction Relief means for forming a gap between the piston rod and the seal member within a predetermined stroke range.
The rebound member is supported by a seat member fixed to the outer periphery of the piston rod and is disposed on the outer periphery of the piston rod. A shock absorber, comprising: an annular spring guide slidably contacting the surface, wherein the spring guide contacts the stopper within the predetermined stroke range.   The shock absorber according to claim 1, wherein a rubber sheet is attached to one or both of the spring guide side surface of the stopper and the stopper side surface of the spring guide.   The shock absorber according to claim 1 or 2, wherein the spring guide is in sliding contact with the outer peripheral surface of the piston rod via a bush fitted to the inner periphery thereof.   A free piston that slides in contact with the inner peripheral surface of the cylinder on the side opposite to the piston rod and closes the wheel side of the liquid chamber, and a biasing means that biases the free piston toward the liquid chamber. The shock absorber according to any one of claims 1 to 3.

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