JP2019184032A - Shock absorber - Google Patents

Abstract

To provide a shock absorber which enables improvement of damping force generation responsiveness at the start of operation even if the shock absorber includes an air-bleeding passage for bleeding air in a gap formed between a cylinder and a case.SOLUTION: A shock absorber includes: a cylindrical case 5 which is attached to an annular lod guide 3, which is attached to an upper end part of a cylinder 1 and slidably supports a piston rod 20, and provided at an inner periphery of the cylinder 1; a ring member 6 which is attached to an outer periphery of the piston rod 20 and may be inserted into the case 5; and an air-bleeding passage 7 which allows an upper end of a case outer peripheral gap G formed between the cylinder 1 and the case 5 to communicate with the inner side of the case 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an improved shock absorber.

  Conventionally, some shock absorbers utilize a hydraulic rebound stopper to alleviate the impact at the time of maximum extension.

  Specifically, such a shock absorber includes a cylinder, a piston inserted into the cylinder so as to be movable in the axial direction, a piston rod connected to the piston and protruding outside the cylinder, and an axial direction of the cylinder. An annular rod guide that is attached to one end and slidably supports the piston rod is provided, and a hydraulic rebound stopper is provided between the rod guide and the piston (for example, Patent Document 1).

  The rod guide includes an annular socket portion, and includes a cylindrical case in which a hydraulic rebound stopper is fitted to the socket portion, and a ring member that is attached to the outer periphery of the piston rod and can be inserted into the case. Configured. Then, when the shock absorber extends and the stroke amount to the extension side of the piston becomes a predetermined amount or more, the ring member is inserted into the case.

  In this way, when the ring member is inserted into the case and enters the back side of the case as the shock absorber extends, the liquid in the case passes through the narrowing gap formed between the ring member and the case. It flows out of the case. A predetermined resistance is applied to the liquid flow. For this reason, when the piston is in a predetermined stroke region on the stroke end side on the expansion side, a position-dependent damping force due to the resistance of the throttle gap is generated, and the shock at the time of maximum expansion of the shock absorber can be mitigated.

JP2015-108404A

  In the conventional shock absorber, the case is fitted to the inner periphery of the annular socket portion provided in the rod guide, and the cylinder is fitted to the outer periphery of the socket portion. There is a gap.

  The gap between the cylinder and the case is not limited to the case where the case and the cylinder are fitted to the inner and outer circumferences of the socket part, but there is a case where there is a gap between the cylinder and the case. When the case is located on the inner periphery of the upper end of the cylinder, air may accumulate in the gap. The air accumulated between the cylinder and the case in this way causes a decrease in damping force generation response.

  For this reason, in the conventional shock absorber, a groove is formed in the outer periphery of the socket portion along the axial direction, and a gap formed between the socket portion and the cylinder by the groove is formed between the case and the cylinder. And an air vent passage communicating with the outer peripheral side of the cylinder.

  According to the above configuration, when the pressure in the extension side chamber formed on the rod guide side when viewed from the piston rises when the shock absorber expands and contracts, the liquid in the extension side chamber is placed between the case and the cylinder and through the air vent passage. Leak into. At this time, since the air accumulated between the case and the cylinder is pushed out of the cylinder, according to the above configuration, the air accumulated between the case and the cylinder by the operation of the shock absorber can be discharged out of the cylinder.

  However, in the above configuration, when the shock absorber is left for a long time with its operation stopped, air may flow backward through the air vent passage and be sucked between the case and the cylinder from outside the cylinder. The air is discharged out of the cylinder along with the expansion / contraction operation of the shock absorber, but causes a decrease in the damping force generation response at the start of the shock absorber operation.

  Therefore, the present invention was devised in order to solve such a problem, and even when it is provided with an air vent passage that vents air in a gap formed between the cylinder and the case, at the start of operation. An object of the present invention is to provide a shock absorber that can improve the damping force generation response.

  A shock absorber that solves the above problems is an annular rod guide that is attached to the upper end of the cylinder and slidably supports the piston rod, and a cylindrical case that is attached to the rod guide and provided on the inner periphery of the cylinder; A ring member that is attached to the outer periphery of the piston rod and can be inserted into the case, and an air vent passage that communicates the upper end of a gap formed between the cylinder and the case to the inside of the case.

  According to the above configuration, since the upper end of the gap formed between the cylinder and the case of the air vent passage communicates with the inside of the case, the air accumulated in the gap moves into the case through the air vent passage, Passes between the piston rod and the rod guide and comes out of the cylinder from the case.

  Moreover, since the case is filled with liquid, even if the shock absorber is left standing for a long time with its operation stopped, air will not be sucked between the cylinder and the case from the air vent passage. . Therefore, even if an air vent passage for venting air between the cylinder and the case is provided, the damping force generation response at the start of operation can be improved.

  In the shock absorber, the rod guide includes an annular socket portion into which the case fits and a facing portion facing the upper end of the case, and an air vent passage is formed between the upper end of the case and the facing portion. It is good to have a radial direction passage and an axial direction passage formed between a case and a socket part. According to this configuration, since the air vent passage can be formed without drilling, the air vent passage can be easily formed.

  Moreover, in the said buffer, it is good for the case to be fitted by the outer periphery of the socket part. According to this configuration, when the pressure in the case increases, the case tension decreases and the case shifts downward from the initial position, the flow area of the radial passage increases, and the pressure in the case is vented. Run away from the passage. Then, further downward movement of the case is prevented and the case is prevented from being removed. Thus, according to the above configuration, the air vent passage also functions as a pressure relief passage, so that the pressure in the case can be prevented from becoming excessive and the case can be prevented from falling off.

  In the shock absorber, the case may be fitted to the inner periphery of the socket portion. According to this configuration, even if the pressure in the case rises and the case tries to expand its diameter, the expansion of the case is suppressed by the socket portion, so that the case can be prevented from falling off.

  Further, in the shock absorber, a lateral groove is formed along the radial direction at the upper end or the facing portion of the case, and in the state where the upper end of the case is in contact with the facing portion, a radial passage is formed by the lateral groove, It is preferable that a longitudinal groove is formed along the axial direction in the case or the socket portion, and an axial passage is formed by the longitudinal groove. Since grooves such as horizontal grooves and vertical grooves can be easily set in width, depth, and the like, according to the above configuration, radial passages and axial passages having a predetermined flow passage area can be easily formed.

  In the shock absorber, the cross-sectional area of the longitudinal groove in the short direction may be set larger than the cross-sectional area of the transverse groove in the short direction. According to the said structure, when making an air vent passage function as a pressure relief passage, the moving amount | distance of the case which deviates from an initial position to the down side can be made small.

  In the shock absorber, both the horizontal groove and the vertical groove may be formed in the rod guide. According to this configuration, the lateral groove for forming the radial passage and the vertical groove for forming the axial passage are both formed in the rod guide, so that the radial passage and the axial passage are communicated with each other. The positioning of the rod guide and the case in the circumferential direction is not necessary, and the assembly work of the shock absorber can be facilitated.

  According to the shock absorber of the present invention, the damping force generation responsiveness at the start of the operation can be improved even when the air vent passage for removing the air in the gap formed between the cylinder and the case is provided.

It is the longitudinal cross-sectional view which showed the buffer which concerns on one embodiment of this invention. FIG. 2 is an enlarged vertical sectional view showing a part of FIG. 1 in an enlarged manner. It is the elements on larger scale which showed the state which looked at a part of rod guide of Drawing 2 from the lower part. It is the elements on larger scale which showed the state which looked at a part of rod guide of Drawing 2 from the slanting lower part. FIG. 3 is a partially enlarged side view showing a part of the rod guide of FIG. 2 with the start end of the transverse groove and the longitudinal groove facing the front, (a) showing a state where the case is in the initial position, and (b) showing the case being The state which shifted | deviated from the initial position to the lower side is shown. It is the elements on larger scale which showed the 1st modification of the buffer which concerns on one embodiment of this invention, and expanded and showed the change part. It is the elements on larger scale which showed the 2nd modification of the buffer which concerns on one embodiment of this invention, and expanded and showed the change part.

  Embodiments 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, a shock absorber D according to an embodiment of the present invention is an upright double-tube shock absorber and is mounted on a vehicle such as an automobile. Hereinafter, unless there is a special description, the upper and lower sides of the shock absorber D according to the present embodiment in a state of being attached to the vehicle are simply referred to as “upper” and “lower” of the shock absorber D.

  In the mounted state, the shock absorber D includes a cylinder 1 arranged with one end in the axial direction facing upward and the other end facing downward, and a bottomed cylindrical outer cylinder 10 provided on the outer periphery of the cylinder 1. The piston 2 is slidably inserted into the cylinder 1 and the piston rod 20 has a lower end connected to the piston 2 and an upper end protruding outside the cylinder 1.

  Although not shown, a vehicle body side bracket is connected to the upper end of the piston rod 20 protruding outside the cylinder 1, and the piston rod 20 is connected to the vehicle body of the vehicle via the vehicle body side bracket. Although not shown, a wheel side bracket is connected to the lower side of the bottom cap 11 which is the bottom of the outer cylinder 10, and the outer cylinder 10 is connected to the axle of the vehicle via the wheel side bracket. Since the cylinder 1 is fixed in the outer cylinder 10, it can be said that the cylinder 1 is also connected to the axle like the outer cylinder 10.

  Thus, the shock absorber D is interposed between the vehicle body and the axle. When the vehicle vibrates up and down with respect to the vehicle body, for example, when the vehicle travels on an uneven road surface, the piston rod 20 enters and exits the cylinder 1, the shock absorber D expands and contracts, and the piston 2 moves up and down in the cylinder 1. Move in the axial direction.

  The shock absorber D includes an annular rod guide 3 that is fitted to the upper end of the cylinder 1 and slidably supports the piston rod 20, and an annular seal member 30 that is stacked above the rod guide 3. . An annular bush 31 is fitted to the inner periphery of the rod guide 3, and the inner periphery of the bush 31 is brought into sliding contact with the outer periphery of the piston rod 20.

  Thus, in the present embodiment, the rod guide 3 supports the piston rod 20 via the bush 31 so as to be slidable, and closes the upper end of the cylinder 1. Further, an outer peripheral portion (a large-diameter portion 3b (FIG. 2) described later) of the rod guide 3 protruding upward from the cylinder 1 protrudes toward the outer cylinder 10, and the upper end of the outer cylinder 10 is also blocked by the rod guide 3. .

  The seal member 30 laminated on the rod guide 3 has an annular lip portion 30a that is in sliding contact with the outer periphery of the piston rod 20, and an annular outer periphery seal portion 30b that is in close contact with the inner periphery of the outer cylinder 10, and the piston rod The outer periphery of 20 and the inner periphery of the outer cylinder 10 are sealed in a liquid-tight manner.

  As described above, the upper ends of the cylinder 1 and the outer cylinder 10 are liquid-tightly closed by the rod guide 3 and the seal member 30, while the lower ends of the outer cylinder 10 are liquid-tightly closed by the aforementioned bottom cap 11. The inner side of the outer cylinder 10 including the inner side of the cylinder 1 is partitioned from the outside air. A liquid and a gas are sealed inside the outer cylinder 10.

  Note that the configurations of the rod guide 3 and the seal member 30 can be changed as appropriate. For example, the bush 31 may be eliminated and the piston rod 20 may be directly supported by the rod guide 3. Alternatively, the lip portion 30a and the outer peripheral seal portion 30b may be formed separately and attached to the rod guide 3.

  Subsequently, the shock absorber D includes a valve case 4 that is fitted to the lower end of the cylinder 1 and fixed between the cylinder 1 and the bottom cap 11. If the cylinder 1 is located on the inner peripheral side of the cylinder 1 and between the rod guide 3 and the valve case 4, the cylinder 1 is filled with a liquid such as hydraulic oil.

  The cylinder 1 is partitioned by the piston 2 into an extension side chamber R1 and a pressure side chamber R2. The extension side chamber R <b> 1 is a chamber in the traveling direction of the piston 2 when the shock absorber D is extended, out of the two chambers partitioned by the piston 2. In the present embodiment, the extension side chamber R1 is positioned on the upper side of the piston 2, and the piston rod 20 penetrates through the center portion thereof. On the other hand, the pressure side chamber R2 is a chamber in the traveling direction of the piston 2 when the shock absorber D contracts out of the two chambers partitioned by the piston 2. In the present embodiment, the compression side chamber R2 is located below the piston 2.

  The piston 2 is formed with an extension side passage 2a and a pressure side passage 2b communicating the extension side chamber R1 and the pressure side chamber R2. Further, on the lower side of the piston 2, an extension valve V1 for opening and closing the outlet of the extension side passage 2a is stacked, and on the upper side of the piston 2, a pressure side valve V2 for opening and closing the outlet of the pressure side passage 2b is stacked. ing.

  The expansion side valve V1 is an expansion side damping element, which opens when the shock absorber D is extended to give resistance to the flow of the liquid from the expansion side passage 2a toward the compression side chamber R2 from the expansion side chamber R1 and closes when contracting and vice versa. Block the flow of On the other hand, the pressure side valve V2 is a check valve, which opens when the shock absorber D contracts and allows the flow of the liquid from the pressure side chamber 2b toward the expansion side chamber R1 from the pressure side chamber R2, but closes when expanding and flows in the opposite direction. To prevent.

  Subsequently, a liquid storage chamber R <b> 3 is formed in a cylindrical gap between the cylinder 1 and the outer cylinder 10. The liquid reservoir R3 stores the same liquid as the liquid in the cylinder 1, and a gas such as air or nitrogen gas is sealed above the liquid surface. A cutout 4 a is formed in the valve case 4 fitted to the lower end of the cylinder 1, and the liquid in the liquid storage chamber R <b> 3 turns to the lower side of the valve case 4 by the cutout 4 a.

  Further, the valve case 4 is formed with a suction passage 4b and a discharge passage 4c for communicating the pressure side chamber R2 and the liquid reservoir chamber R3. Further, a suction valve V3 for opening and closing the outlet of the suction passage 4b is laminated on the upper side of the valve case 4, and a damping valve V4 for opening and closing the outlet of the discharge passage 4c is laminated on the lower side of the valve case 4. ing.

  The suction valve V3 is a check valve that opens when the shock absorber D extends to allow the flow of the liquid from the liquid reservoir chamber R3 to the pressure side chamber R2 through the suction passage 4b, but closes when contracted and flows in the opposite direction. Stop. On the other hand, the damping valve V4 is a pressure-side damping element, which opens when the shock absorber D contracts to provide resistance to the flow of liquid from the pressure-side chamber R2 to the liquid reservoir chamber R3 and closes when the buffer D extends. Prevent reverse flow.

  According to the above configuration, when the shock absorber D is extended so that the piston rod 20 retracts from the cylinder 1, the piston 2 moves upward in the cylinder 1 and compresses the expansion side chamber R1. When the shock absorber D is extended, the liquid in the extension side chamber R1 pushes open the extension side valve V1, and moves to the compression side chamber R2 through the extension side passage 2a. Resistance is given to the flow of the liquid by the expansion side valve V1. For this reason, when the shock absorber D extends, the pressure in the expansion side chamber R1 rises, and the shock absorber D exhibits a main expansion side damping force that prevents the expansion operation.

  Further, when the shock absorber D is extended, the suction valve V3 is opened, and the liquid corresponding to 20 volumes of the piston rod retreated from the cylinder 1 is supplied from the liquid reservoir chamber R3 to the pressure side chamber R2 through the suction passage 4b. Therefore, even if the internal volume of the cylinder 1 is increased by the amount that the piston rod 20 is retracted from the cylinder 1 when the shock absorber D is extended, the volume change is compensated by the liquid reservoir R3.

  On the other hand, when the shock absorber D is retracted as the piston rod 20 enters the cylinder 1, the piston 2 moves downward in the cylinder 1 and compresses the compression side chamber R2. When the shock absorber D contracts, the pressure side valve V2 is opened, and the liquid in the pressure side chamber R2 moves to the expansion side chamber R1 through the pressure side passage 2b. As described above, since the pressure side valve V2 is a check valve, the pressures in the extension side chamber R1 and the pressure side chamber R2 become substantially equal when the shock absorber D contracts.

  Further, when the shock absorber D contracts, the liquid in the pressure side chamber R2 pushes open the damping valve V4, and the liquid corresponding to 20 volumes of the piston rod that has entered the cylinder 1 passes through the discharge passage 4c from the pressure side chamber R2 to the liquid reservoir chamber R3. Is discharged. Resistance is given to the flow of the liquid by the damping valve V4. For this reason, when the shock absorber D contracts, the pressure in the cylinder 1 rises, and the shock absorber D exhibits a main compression side damping force that prevents the contraction operation. Further, even if the internal volume of the cylinder 1 is reduced by the amount that the piston rod 20 enters the cylinder 1 when the shock absorber D is contracted, the change in the volume is compensated by the liquid storage chamber R3.

  Thus, in the present embodiment, the expansion side valve V1 functions as an expansion side damping element for exerting the expansion side damping force, and the damping valve V4 functions as a compression side damping element for exhibiting the compression side damping force. . And since the channel | path which provided each damping element is made into one way, the expansion side damping force and the compression side damping force can be set separately. However, the configuration of the attenuation element and the configuration of the passage in which the attenuation element is provided can be changed as appropriate.

  For example, in the present embodiment, each damping element is a leaf valve, but may be a poppet valve or the like, and may be an orifice or a choke passage that allows bidirectional flow. Further, the pressure side valve V2 may be replaced with a pressure side damping element, and resistance may be given to the flow of the liquid from the pressure side chamber R2 toward the extension side chamber R1 in the pressure side passage 2b.

  Further, in the present embodiment, the shock absorber D is a single rod / double cylinder type, and the liquid reservoir chamber R3 functions as a reservoir chamber for volume compensation of the piston rod 20 that enters and exits the cylinder 1. The cylinder 1 and the outer cylinder 10 constitute a reservoir tank for forming the reservoir chamber. However, the mode of the shock absorber D can be changed as appropriate.

  For example, the outer cylinder 10 may be eliminated and a separate reservoir tank from the cylinder 1 may be provided. Further, the outer cylinder 10 may be eliminated to provide an air chamber that can be expanded and contracted in the cylinder 1, and volume compensation of the piston rod 20 that enters and exits the cylinder 1 may be performed in this air chamber. In this case, the shock absorber can be a single cylinder type. Further, the shock absorber may be a double rod type by projecting the piston rod 20 from both sides of the piston 2 to the outside of the cylinder 1. In this case, volume compensation of the piston rod entering and exiting the cylinder can be made unnecessary.

  Subsequently, the shock absorber D includes a hydraulic rebound stopper S provided between the piston 2 and the rod guide 3. And the impact at the time of the maximum expansion | extension of the buffer D is relieved by the hydraulic pressure rebound stopper S.

  Specifically, the hydraulic pressure rebound stopper S is attached to the rod guide 3 and provided on the inner periphery of the upper end portion of the cylinder 1 and attached to the outer periphery of the piston rod 20 and can be inserted into the case 5. And an annular ring member 6. Further, an air vent passage 7 is formed in a fitting portion between the case 5 and the rod guide 3, and a gap formed between the cylinder 1 and the case 5 by the air vent passage 7 is formed inside the case 5. Communicated.

  More specifically, as shown in FIG. 2, the rod guide 3 includes a fitting portion 3a on which the cylinder 1 is fitted on the outer periphery, and protrudes upward from the fitting portion 3a and has an outer diameter outside the fitting portion 3a. A large-diameter portion 3b larger than the diameter and a socket portion 3c that protrudes downward from the fitting portion 3a and whose outer diameter is smaller than the outer diameter of the fitting portion 3a are included. The fitting part 3a, the large diameter part 3b, and the socket part 3c are each annularly arranged on the same axis.

  And the annular step part 3d exists in the boundary of the outer peripheral side of the large diameter part 3b and the fitting part 3a, and the upper end of the cylinder 1 fitted to the outer periphery of the fitting part 3a hits the step part 3d. There is also an annular step 3e at the outer peripheral side boundary between the fitting portion 3a and the socket portion 3c. The case 5 is fitted to the outer periphery of the socket portion 3c, and the upper end of the case 5 abuts against the step portion 3e in the initial state immediately after assembly.

  Thus, in the present embodiment, the lower step portion 3e formed at the boundary between the fitting portion 3a and the socket portion 3c is a facing portion facing the upper end of the case 5. Moreover, the outer diameter of the fitting part 3a is larger than the outer diameter of the case 5, and between the case 5 fitted to the outer periphery of the socket part 3c and the cylinder 1 fitted to the outer periphery of the fitting part 3a. An annular gap is created. Hereinafter, this gap is referred to as a case outer circumferential gap G.

  As shown in FIG. 2, the lower end portion of the case 5 is provided with a tapered portion 5 a whose inner diameter gradually increases toward the lower end. In FIG. 2, as indicated by the two-dot chain line, the ring member 6 inserted inside the case 5 is inserted deeper than the tapered portion 5 a, and the outer periphery of the ring member 6 is the case 5. It comes in sliding contact with the inner circumference.

  The ring member 6 is attached to the outer periphery of the piston rod 20 via the holder 21. The holder 21 includes a cylindrical portion 21a that is fixed to the outer periphery of the piston rod 20 so as not to move in the axial direction with respect to the piston rod 20, and an annular seat portion 21b that projects radially outward from the lower end of the cylindrical portion 21a. And an annular retaining portion 21c projecting radially outward from the upper end of the tubular portion 21a.

  And the ring member 6 is attached to the outer periphery of the cylinder part 21a so that it can move up and down (in the axial direction). When the ring member 6 moves downward with respect to the cylinder part 21a and is seated on the seat part 21b, The downward movement of the ring member 6 is prevented. On the other hand, when the ring member 6 moves upward with respect to the cylinder portion 21a and hits the retaining portion 21c, further upward movement of the ring member 6 is prevented. In this way, the ring member 6 is prevented from being detached from the holder 21.

  A check passage 8 is formed between the ring member 6 and the cylindrical portion 21a. Further, a notch 6a is formed at the upper end portion of the ring member 6. One end of the notch 6a opens into the check passage 8 and the other end is on the outer peripheral side from the outer peripheral end of the retaining portion 21c in the axial direction. Is located. For this reason, when the ring member 6 is separated from the seat portion 21b, the check passage 8 is maintained in an open state. On the other hand, when the ring member 6 is seated on the seat portion 21b, the check passage 8 is closed by the seat portion 21b.

  According to the above configuration, when the shock absorber D in which the piston 2 moves upward in the cylinder 1 is extended and the stroke amount to the upper side (extension side) of the piston 2 becomes a predetermined amount or more, the ring member 6 becomes the case. It is inserted into 5 and penetrates into the back side. Thus, when the ring member 6 inserted into the case 5 enters the back side (upper side) of the case 5, the ring member 6 sits on the seat portion 21 b and closes the check passage 8.

  For this reason, the liquid in the case 5 moves out of the case 5 through a constriction gap (not shown) formed between the ring member 6 and the case 5, and resistance is given to the flow of the liquid. Is done. Therefore, when the ring member 6 enters the back side of the case 5, the pressure in the case 5 rises, and a position-dependent damping force that prevents the buffer D from being extended is generated.

  That is, when the piston 2 is in a predetermined stroke region on the extended stroke end side where the stroke amount to the extended side of the piston 2 is greater than or equal to a predetermined value, the position by the hydraulic pressure rebound stopper S caused by the resistance of the throttle gap Dependent damping force is generated.

  As described above, when the shock absorber D is extended, the main extension side damping force is generated due to the resistance of the extension side valve (extension side damping element) V1. For this reason, when the shock absorber D exhibits an extension operation when the piston 2 is in a predetermined stroke region on the extension stroke end side, a position-dependent damping force by the hydraulic rebound stopper S is added to the main extension side damping force. In addition, the damping force of the entire shock absorber D increases. Since the extension speed of the shock absorber D can be decelerated and stopped by the large damping force, the shock at the time of the maximum extension of the shock absorber D can be mitigated.

  Further, the case 5 is provided with a tapered portion 5a. For this reason, as the ring member 6 positioned inside the taper portion 5a advances toward the back side of the case 5, the narrowing gap formed on the outer periphery of the ring member 6 gradually narrows, and the flow of liquid from the inside of the case 5 to the outside is reduced. Since the applied resistance gradually increases, the position-dependent damping force gradually increases.

  Further, when the piston 2 approaches the stroke end on the extension side, the ring member 6 advances further to the back side than the tapered portion 5a, and the ring member 6 comes into sliding contact with the inner periphery of the case 5. For this reason, when the piston 2 is close to the stroke end on the extension side, the narrowing gap formed on the outer periphery of the ring member 6 becomes a sliding gap and becomes very narrow, and the liquid flowing from the inside of the case 5 to the outside is reduced. A large position-dependent damping force can be exerted by applying a large resistance to the flow.

  Therefore, when the piston 2 approaches the extension stroke end, the extension speed of the shock absorber D can be reliably decelerated by the large position-dependent damping force exhibited by the hydraulic pressure rebound stopper S. On the other hand, since the position-dependent damping force when the ring member 6 is at a shallow position in the case 5 can be reduced, a sudden change in the damping force at the boundary of the ring member 6 being inserted into the case 5 is suppressed. In addition, the generation of abnormal noise can be prevented and the ride comfort of the vehicle can be improved.

  On the contrary, when the shock absorber D contracts and the ring member 6 inserted into the case 5 retreats from the case 5, the ring member 6 leaves the seat portion 21b and opens the check passage 8. For this reason, the liquid outside the case 5 quickly flows into the case 5 through the check passage 8.

  Therefore, even when the piston 2 is in the predetermined stroke region on the stroke end side on the expansion side, the position-dependent damping force by the hydraulic pressure rebound stopper S hardly occurs when the shock absorber D contracts, and the hydraulic pressure rebound stopper S does not interfere with the contraction operation of the shock absorber D. Thus, the hydraulic pressure rebound stopper S is one-sided.

  In addition, when the piston 2 is outside a predetermined stroke region on the stroke end side on the expansion side and the ring member 6 is positioned outside the case 5, liquid can freely flow between the ring member 6 and the cylinder 1. Can move. For this reason, when the piston 2 is outside a predetermined stroke region on the extension stroke end side, no position-dependent damping force is generated by the hydraulic pressure rebound stopper S, and the damping force generated by the shock absorber D is the main damping force. It becomes the damping force.

  Note that the configurations of the ring member 6 and the holder 21 can be changed as appropriate. For example, the notch 6a of the ring member 6 is eliminated, a notch or a hole is formed in the retaining portion 21c, and when the ring member 6 retreats from the case 5, the communication between the check passage 8 and the inside of the case 5 is notched. Or you may maintain with a hole.

  The shape of the ring member 6 may be a C shape having a split in a part of the circumferential direction or an O shape having no split. When the ring member 6 is C-shaped, the ring member 6 may be slidably contacted with the inner periphery of the tapered portion 5a, and the split may be closed on the back side of the tapered portion 5a. Further, the ring member 6 does not necessarily have to be brought into sliding contact with the inner periphery of the case 5 in a state where the ring member 6 has advanced from the taper portion 5a. For example, only when the piston speed is in a high speed range, the ring member 6 The member 6 may be expanded and brought into sliding contact with the case 5.

  Next, as shown in FIGS. 3 and 4, a lateral groove 3f is formed along the radial direction in the lower step portion 3e facing the upper end of the case 5 fitted to the outer periphery of the socket portion 3c. In this lateral groove 3f, the end located on the outer peripheral side of the lower step portion 3e is defined as a start end 3fa, and the opposite end is defined as a termination 3fb. Then, as shown in FIG. 3, the start end 3 fa of the lateral groove 3 f is located on the outer peripheral side with respect to the upper end outer periphery of the case 5 in the axial view. On the other hand, the terminal end 3fb of the lateral groove 3f is located on the inner peripheral side of the upper end inner periphery of the case 5 as viewed in the axial direction.

  A longitudinal groove 3g is formed along the axial direction on the outer periphery of the socket portion 3c facing the inner periphery of the case 5. The vertical groove 3g is continuously formed from the upper end to the lower end of the socket portion 3c (FIG. 4). The horizontal groove 3f extends to the inside of the vertical groove 3g, and the terminal end 3fb of the horizontal groove 3f is positioned inside the vertical groove 3g as viewed in the axial direction (FIG. 3).

  For this reason, as shown in FIG. 2, in the initial state where the case 5 is fitted to the outer periphery of the socket portion 3c and the upper end of the case 5 is abutted against the lower step portion 3e, the upper end and the lower side of the case 5 are A laterally long gap is formed in the radial direction between the stepped portion 3e and the lateral groove 3f, and a radial passage 70 is formed by the laterally long gap. Also, a longitudinally long gap is formed in the axial direction between the inner periphery of the case 5 and the outer periphery of the socket portion 3c by the longitudinal groove 3g, and an axial passage 71 communicating with the radial passage 70 is formed by this longitudinally spaced gap. Is done.

  And, as described above, the start end 3fa of the lateral groove 3f formed in the lower step portion 3e facing the upper end of the case 5 is located on the outer peripheral side with respect to the upper end outer periphery of the case 5 in the axial direction view. The radial passage 70 is connected to the upper end of the case outer circumferential gap G. On the other hand, since the lower end of the vertical groove 3g is located at the lower end of the socket portion 3c, the axial passage 71 is connected to the inside of the case 5.

  For this reason, even when the shock absorber D is assembled, air accumulates in the case outer circumferential gap G, or even if the air dissolved in the liquid becomes bubbles and accumulates in the case outer circumferential gap G when the shock absorber D is used. Moves through the radial passage 70 and the axial passage 71 into the case 5 and naturally escapes from the inside of the case 5 to the outside of the cylinder 1 through the sliding gap between the piston rod 20 and the bush 31. . As described above, in this embodiment, the air passage 7 is constituted by the radial passage 70 and the axial passage 71.

  Further, as described above, in the initial state where the upper end of the case 5 hits the lower stepped portion 3e, the radial passage 70 is formed by a horizontally long gap formed inside the lateral groove 3f. As shown in FIG. 4, the cross-sectional area A (FIG. 4) of the transverse groove 3 f in the short direction is set smaller than the cross-sectional area B of the longitudinal groove 3 g in the short direction. The direction passage 70 portion functions as a diaphragm.

  For this reason, when the ring member 6 inserted into the case 5 advances to the back side of the case 5, the liquid in the case 5 leaks out of the case 5 through the air vent passage 7, but the flow of the liquid is reduced. The inside of the case 5 can be boosted. For this reason, even if the inside and outside of the case 5 communicate with each other through the air vent passage 7, the position-dependent damping force generated by the hydraulic pressure rebound stopper S is not hindered.

  Moreover, in this Embodiment, the socket part 3c is press-fit inside the case 5, these are connected, and the case 5 is hold | maintained at the socket part 3c by fastening the socket part 3c with predetermined | prescribed tight force. . And since the pressure in case 5 acts in the direction which expands diameter of case 5, if the pressure in case 5 becomes high pressure, tightness will fall.

  Therefore, when the pressure in the case 5 is increased and the case 5 is pushed and spread by the pressure and the tightening force is reduced, the case 5 is shifted downward from the initial position (initial position) shown in FIG. . Then, as shown in FIG. 5B, an annular gap is formed along the circumferential direction between the lower step 3 e and the upper end 5 b of the case 5, and this annular gap is formed between the radial passage 70 and the annular gap 70. Become.

  Thus, when the upper end 5b of the case 5 is separated from the lower stepped portion 3e, the flow area of the radial passage 70 increases. Then, the pressure in the case 5 escapes and the pressure increase in the case 5 can be suppressed, so that the pressure in the case 5 does not become excessive. In addition, if the pressure increase in the case 5 is suppressed, it is possible to suppress a decrease in the tightening force of the case 5, so that it is possible to prevent the case 5 from shifting further downward and to prevent the case 5 from dropping from the socket portion 3c. .

  That is, the air vent passage 7 of the present embodiment also functions as a pressure relief passage 9 that is opened by the movement of the case 5 and contributes to prevention of the case 5 from falling off. Even if the radial passage 70 is widened at the time of depressurization, the radial passage 70 functions as a throttle so that the pressure in the case 5 can be increased, and a sufficient position-dependent damping force can be obtained. Of course.

  Furthermore, in the present embodiment, the cross-sectional area B of the longitudinal groove 3g is set larger than the cross-sectional area A of the lateral groove 3f (FIG. 4), and the flow area of the axial passage 71 is larger than the flow area of the radial passage 70. is doing. Further, when the case 5 is shifted downward from the initial position, the radial passage 70 extends along the circumferential direction between the upper end of the case 5 and the lower stepped portion 3e through a horizontally long gap formed inside the lateral groove 3f. It becomes an annular gap that can be made, and the area of the flow path is greatly increased.

  For this reason, a sufficient flow rate can be secured even if the case 5 is slightly displaced from the initial position. That is, even when the pressure release passage 9 is opened by the movement of the case 5 and the pressure is released, the movement amount from the initial position of the case 5 at the time of the pressure release can be reduced, so that the hydraulic pressure rebound stopper S operates. Almost no change in stroke area.

  Hereinafter, the operational effects of the shock absorber D according to the present embodiment will be described.

  The shock absorber D according to the present embodiment includes a cylinder 1 that is disposed with one end in the axial direction facing upward, a piston 2 that is movably inserted into the cylinder 1 in the axial direction, and is coupled to the piston 2. And a piston rod 20 protruding upward from the cylinder 1. That is, in the present embodiment, the other end of the cylinder 1 in the axial direction faces downward.

  Furthermore, the shock absorber D according to the present embodiment includes an annular rod guide 3 that is attached to the upper end portion of the cylinder 1 and slidably supports the piston rod 20, and is attached to the rod guide 3 to A cylindrical case 5 provided on the periphery, a ring member 6 that is attached to the outer periphery of the piston rod 20 and can be inserted into the case 5, and a case outer peripheral gap (a gap formed between the cylinder 1 and the case 5) An air vent passage 7 that communicates the upper end of G to the inside of the case 5 is provided.

  According to the above configuration, when the ring member 6 advances through the case 5 to the back side, resistance is applied to the flow of liquid from the case 5 to the outside thereof, and a position-dependent damping force is generated. The case 5 is attached to the rod guide 3, and the ring member 6 advances to the back side in the case 5 because the piston 2 is in a predetermined stroke region on the stroke end side on the expansion side and the shock absorber D. This is a case where

  For this reason, when the shock absorber D is extended and the piston 2 is in a predetermined stroke region on the expansion stroke end side, the position-dependent damping force is generated, and the shock at the time of the maximum expansion of the shock absorber D is generated. Can be relaxed. Thus, according to the above configuration, the case 5 and the ring member 6 form a hydraulic pressure rebound stopper S, and the hydraulic pressure rebound stopper S can alleviate an impact when the shock absorber D is extended to the maximum.

  Further, according to the above configuration, the air vent passage 7 communicates the upper end of the case outer peripheral gap G to the inside of the case 5. For this reason, even if air accumulates in the case outer peripheral gap G, the air moves into the case 5 through the air vent passage 7 and passes between the piston rod 20 and the rod guide 3 from inside the case 5. Pull out of cylinder 1. Therefore, according to the said structure, the case outer periphery clearance gap G can be ventilated and the damping force generation | occurrence | production responsiveness of the buffer D can be made favorable.

  In addition, when the air vent passage is open to the outside of the cylinder as in the past, the air outside the cylinder flows backward through the air vent passage when the shock absorber is left standing for a long time. Then, it is sucked into the outer peripheral gap of the case, which may cause a decrease in damping force generation response at the start of operation.

  On the other hand, according to the above configuration, since the case 5 is filled with the liquid, even if the shock absorber D is left standing for a long time with its operation stopped, the case outer peripheral gap G is removed from the air vent passage 7. Air will not be sucked into. Therefore, according to the shock absorber D of the present embodiment, the damping force generation responsiveness at the start of the operation can be improved even if the air vent passage 7 through which the case outer circumferential gap G is vented is provided.

  Further, when the air vent passage communicates with the outside of the cylinder as in the prior art, the liquid in the extension side chamber leaks out of the cylinder from the air vent passage when the shock absorber is activated. For this reason, in the conventional shock absorber, it is necessary to set the main damping force in consideration of the air vent passage, and the setting of the damping force is complicated.

  On the other hand, in the present embodiment, the inside of the case 5 communicated with the case outer peripheral gap G by the air vent passage 7 is in the extension side chamber R1, and the liquid may leak out of the cylinder 1 through the air vent passage 7. Absent. For this reason, it is easy to set the main damping force in the shock absorber D of the present embodiment.

  Further, as in the conventional case, when the air vent passage communicates with the outside of the cylinder and liquid leaks from the air vent passage to the outside of the cylinder during operation, it is necessary to form a chamber such as a liquid reservoir chamber on the outer periphery of the cylinder. . Therefore, the conventional shock absorber must be a double cylinder type, and the type of shock absorber is limited.

  On the other hand, in this embodiment, the liquid does not leak out of the cylinder 1 through the air vent passage 7 as described above. Therefore, the outer cylinder 10 is not necessarily provided on the outer periphery of the cylinder 1. That is, the air vent passage 7 of the present embodiment can be applied not only to a double cylinder type shock absorber but also to a single cylinder type shock absorber, and thus has high versatility.

  As described above, the state where one end of the cylinder 1 in the axial direction is directed upward is not necessarily limited to the case where the cylinder 1 is upright and the one end and the other end of the cylinder 1 are arranged on the vertical line. Including a state where is inclined with respect to the vertical line. In other words, the state in which one end in the axial direction of the cylinder 1 is directed upward may be such that one end and the other end in the axial direction of the cylinder 1 are arranged with a height difference, and the one end is higher than the other end.

  The upper end of the case outer circumferential gap G is a portion where the liquid surface is located when the case outer circumferential gap G is filled with liquid, and has a predetermined area. Specifically, in the present embodiment, the end surface facing the lower end surface of the rod guide 3 in the case outer peripheral gap G is the upper end of the case outer peripheral gap G. When it is assumed that the upper end of the case outer peripheral gap G is an object having a mass, the inlet of the air vent path 7 (on the case outer peripheral gap G side) so that the air vent path 7 and the case outer peripheral gap G communicate with each other. If the edge of the opening is in contact with the upper end of the case outer peripheral gap G, the air vent passage 7 is connected to the upper end of the case outer peripheral gap G.

  Here, for example, when the lower end surface of the rod guide 3 facing the case outer circumferential gap G is vertically uneven, or when the cylinder 1 is inclined with respect to the vertical line as described above, the case outer circumferential gap G There is also a difference in height at the top of itself. In order to remove air from the case outer circumferential gap G, the air vent passage 7 is preferably connected to the highest position (uppermost end) of the upper ends of the case outer circumferential gap G. However, the connection position between the air vent passage 7 and the case outer peripheral gap G may be slightly deviated from the uppermost end of the case outer peripheral gap G.

  In the present embodiment, the rod guide 3 includes an annular socket portion 3c into which the case 5 is fitted, and a lower step portion (opposing portion) 3e facing the upper end (upper end) 5b of the case 5. including. A radial passage 70 is formed between the upper end 5b of the case 5 and the lower step portion 3e, and an axial passage 71 is formed between the case 5 and the socket portion 3c. It is comprised.

  According to the above configuration, it is easier to form the air vent passage 7 as compared to the case where the air vent passage 7 is formed by drilling the rod guide 3 or the case 5. This is because the air vent passage for extracting air is generally a very narrow passage, and it may be difficult to form such a thin passage by drilling, whereas the gap between the two members This is because if used, a narrow passage can be easily formed.

  Further, in the present embodiment, the radial passage 70 is formed between the upper end (upper end) 5b of the case 5 and the lower stepped portion (opposing portion) 3e, and the axial passage 71 is formed between the case 5 and the socket. The case 5 is fitted to the outer periphery of the socket portion 3c.

  According to the above configuration, when the case 5 is shifted downward from the socket portion 3c, the flow path area of the radial passage 70 is increased. Further, even when the case 5 is displaced downward from the socket portion 3c in this way, the communication between the radial passage 70 and the axial passage 71 is maintained. For this reason, according to the said structure, while the air vent path 7 functions also as the pressure vent path 9, it can prevent that the pressure in the case 5 becomes excessive and can prevent the case 5 from falling off.

  Here, for example, the shock absorber described in JP-T-2015-500970 has the characteristics described in the background art described above, and in this shock absorber, the case of the hydraulic rebound stopper is provided on the rod guide. The outer periphery of the annular socket is fitted. And in the shock absorber, a claw formed on the outer periphery of the socket part is hooked on the step formed on the inner periphery of the cylinder (see Japanese Patent Publication No. 2015-500970, FIG. 1) or on the outer periphery of the socket part. Is hooked in a groove provided on the inner periphery of the upper end of the case (FIG. 4) to prevent the case from falling off. However, in this case, the shape of the cylinder or socket and the case becomes complicated, and these processes are complicated and costly, and it is impossible to prevent the pressure in the case from becoming excessive.

  On the other hand, according to the shock absorber D of the present embodiment, the case 5 can be prevented from falling off without complicating the shapes of the cylinder 1, the socket portion 3c, and the case 5, and the pressure in the case 5 can be reduced. It can be prevented from becoming excessive.

  In this embodiment, since the pressure release passage 9 also functions as the air release passage 7, the pressure release passage 9 and the case outer peripheral gap G are communicated even when the case 5 is in the initial position. I am letting. However, if only the function as the pressure release passage 9 is considered, the lateral groove 3f may be eliminated and the radial passage 70 may be completely closed when the case 5 is in the initial position. It does not need to be connected to the upper end of the case outer peripheral gap G.

  Furthermore, if only the function as the pressure release passage 9 is considered, a hole is formed in the upper end portion of the case 5, and when the case 5 is in the initial position, the hole is closed, and the case 5 is moved downward from the initial position. The hole may be opened when it slips. Thus, the rod guide 3 includes an annular socket portion 3c in which the case 5 is fitted to the outer periphery, and a lower step portion (opposing portion) 3e facing the upper end (upper end) 5b of the case 5, If a passage is provided that communicates the inside and outside of the case 5 when the case 5 is displaced downward from the initial position, this passage can be used as the pressure relief passage 9.

  In the present embodiment, a lateral groove 3f is formed along the radial direction in the lower stepped portion (opposing portion) 3e, and the upper end (upper end) 5b of the case 5 is formed in the lower stepped portion (opposing) In the state of abutting against the part 3e, a radial passage 70 is formed by the lateral groove 3f. On the other hand, a longitudinal groove 3g is formed along the axial direction on the outer periphery of the socket portion 3c, and an axial passage 71 is formed by the longitudinal groove 3g.

  According to the above configuration, the lateral groove 3 f and the longitudinal groove 3 g for forming the radial passage 70 and the axial passage 71 are both formed in the rod guide 3. For this reason, it is not necessary to align the rod guide 3 and the case 5 in the circumferential direction in order to allow the radial passage 70 and the axial passage 71 to communicate with each other, and the assembly work of the shock absorber D can be facilitated.

  Further, according to the above configuration, the radial passage 70 and the axial passage 71 are formed by the lateral groove 3f and the longitudinal groove 3g, respectively. Since the groove such as the horizontal groove 3f and the vertical groove 3g can be freely set in width, depth and the like, it is easy to set the radial passage 70 and the axial passage 71 to an arbitrary flow passage area. Further, although it is difficult to form a thin hole with a mold, if it is a thin groove, it is easy to form with a mold. Therefore, according to the above configuration, it is formed even if the radial passage 70 or the axial passage 71 is a thin passage. Cheap.

  In the present embodiment, the cross-sectional area B in the short direction of the vertical groove 3g is larger than the cross-sectional area A in the short direction of the lateral groove 3f. According to this configuration, when the air vent path 7 functions as the pressure vent path 9, it is possible to secure the flow rate of the axial path 71 and reduce the amount of movement of the case 5 that shifts downward from the initial position. However, the configurations of the air vent passage 7 and the pressure vent passage 9 are not limited to the above, and can be changed as appropriate.

  For example, in addition to the vertical groove 3g formed so as to overlap the horizontal groove 3f in the radial direction as shown in FIG. 5, the vertical groove 3g may be formed at a position shifted in the circumferential direction from the horizontal groove 3f. In this way, when the vertical grooves 3g are provided more than the horizontal grooves 3f, the flow rate of the axial passage 71 can be secured and maintained even if the cross-sectional area B of the vertical grooves 3g is not larger than the cross-sectional area A of the horizontal grooves 3f. The amount of movement of the case 5 that deviates from the position can be reduced.

  Thus, the number of the horizontal grooves 3f and the vertical grooves 3g may be one or more, and may not be the same. Further, as shown in FIG. 6, a lateral groove 5 c is formed along the radial direction at the upper end of the case 5 in place of the lateral groove 3 f and the longitudinal groove 3 g of the embodiment, and along the inner periphery of the case 5 along the axial direction. The vertical grooves 5d may be formed, and the radial grooves 70 and the axial paths 71 may be formed by the horizontal grooves 5c and the vertical grooves 5d. However, when the thickness of the case 5 is small, it may be difficult to form the horizontal groove 5c or the vertical groove 5d in the case 5. For this reason, the versatility can be improved by forming the lateral grooves 3f and the longitudinal grooves 3g in the rod guide 3.

  Further, as shown in FIG. 7, the case 5 may be fitted to the inner periphery of the socket portion 3c. According to the said structure, when the case 5 tries to expand the diameter by the pressure in the case 5, since the diameter expansion of the case 5 can be suppressed by the socket part 3c, drop-off of the case 5 can be prevented.

  In FIG. 7, in the rod guide 3, a lateral groove 3 h is formed along the radial direction at a facing portion (not shown) facing the upper end (upper end) of the case 5 fitted to the inner periphery of the socket portion 3 c. In addition, a longitudinal groove 3i is formed along the axial direction on the inner periphery of the socket portion 3c. A radial passage 70 is formed by a laterally long gap formed between the upper end of the case 5 and the opposing portion of the rod guide 3 by the lateral groove 3h. On the other hand, an axial passage 71 communicating with the radial passage 70 is formed by a longitudinal gap formed between the outer periphery of the case 5 and the inner periphery of the socket portion 3c by the vertical groove 3i.

  However, although not shown, even when the case 5 is fitted to the inner periphery of the socket portion 3c, the lateral groove and the longitudinal groove are formed in the case 5 in place of the lateral groove 3h and the longitudinal groove 3i formed in the rod guide 3. Of course, these may form the radial passage 70 and the axial passage 71.

  Further, if both the lateral groove and the longitudinal groove are formed in one of the rod guide 3 and the case 5, the alignment of the rod guide 3 and the case 5 in the circumferential direction becomes unnecessary, so that the assembly work of the shock absorber D can be facilitated. . However, you may utilize combining the horizontal groove formed in one of the rod guide 3 and the case 5, and the vertical groove formed in the other.

  Further, the radial passage 70 and the axial passage 71 may be formed, for example, using holes formed in the rod guide 3 or the case 5 or may be formed by a combination of grooves and holes. Further, when the case 5 is in the initial position, the upper end (upper end) 5b of the case 5 may be set so as to be separated from the lower stepped portion (opposing portion) 3e over the entire circumference. In some cases, the lateral groove 5c can be omitted. These changes are possible even when the case 5 is fitted to either the outer periphery or the inner periphery of the socket portion 3c.

  The preferred embodiments of the present invention have been described above in detail, but modifications, changes and modifications can be made without departing from the scope of the claims.

A: Cross-sectional area in the short direction of the lateral groove, B: Cross-sectional area in the short direction of the vertical groove, D: Shock absorber, G: Case outer circumferential clearance (formed between the cylinder and the case) 1) Cylinder, 2 ... Piston, 3 ... Rod guide, 3c ... Socket part, 3e ... Lower step (opposite part), 3f, 5c,. · Horizontal groove, 3g, 5d · · · vertical groove, 5 · · · case, 5b · · · the upper end of the case, 6 · · · ring member, 7 · · · air vent passage, 20 · · · piston rod, 70 · ..Radial passage, 71 ... Axial passage

Claims (7)

A cylinder arranged with one axial end facing upward,
A piston inserted in the cylinder so as to be movable in the axial direction;
A piston rod connected to the piston and projecting upward from the cylinder;
An annular rod guide mounted on the upper end of the cylinder and slidably supporting the piston rod;
A cylindrical case attached to the rod guide and provided on the inner periphery of the cylinder;
A ring member attached to the outer periphery of the piston rod and insertable into the case;
A shock absorber, comprising: an air vent passage communicating an upper end of a gap formed between the cylinder and the case to the inside of the case. The rod guide includes an annular socket portion into which the case is fitted, and a facing portion facing the upper end of the case,
The air vent passage includes a radial passage formed between an upper end of the case and the facing portion, and an axial passage formed between the case and the socket portion. The shock absorber according to claim 1, wherein: The shock absorber according to claim 2, wherein the case is fitted to an outer periphery of the socket portion. The shock absorber according to claim 2, wherein the case is fitted to an inner periphery of the socket portion. A lateral groove is formed along the radial direction in the upper end of the case or the facing portion, and the radial passage is formed by the lateral groove in a state where the upper end of the case is in contact with the facing portion,
The case or the socket part has a longitudinal groove formed along an axial direction, and the axial passage is formed by the longitudinal groove. The shock absorber described in 1. The shock absorber according to claim 5, wherein a cross-sectional area of the longitudinal groove in the short direction is larger than a cross-sectional area of the transverse groove in the short direction. The shock absorber according to claim 5 or 6, wherein both the horizontal groove and the vertical groove are formed in the rod guide.

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