JP2011231794A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid response delay of pressure side damping force in a hydraulic shock absorber in which a piston is slid on an inner peripheral surface of an inner tube.SOLUTION: In this hydraulic shock absorber 10, a check valve 70 for preventing flow into a hollow part 61 of a piston rod 40 from an oil reservoir chamber 22 is arranged surrounding a small hole 63 which is formed through an outer periphery of the piston rod 40 and communicates with the oil reservoir chamber 22.

Description

  The present invention relates to a hydraulic shock absorber used for a motorcycle front fork or the like.

  As a hydraulic shock absorber, a damper cylinder is provided inside the outer tube and the inner tube, and in order to reduce the number of parts compared to the case where a piston is slidably contacted with the inner periphery of the damper cylinder, the number of components is described in Patent Document 1. As described above, there is one in which a piston is slidably contacted with an inner periphery of an inner tube without providing a damper cylinder.

  In this conventional hydraulic shock absorber, the inner tube is slidably inserted into the outer tube through bushes fixed to the inner circumferential opening of the outer tube and the outer circumferential tip of the inner tube. An annular oil chamber surrounded by the inner periphery of the outer tube, the outer periphery of the inner tube, and the two bushes is partitioned, a partition member is provided on the inner periphery of the inner tube, and an oil chamber is partitioned in the lower portion, An oil reservoir chamber is defined in the upper part, a piston rod attached to the outer tube is slidably inserted into the partition member, and is slidably contacted with the inner periphery of the inner tube at the tip of the piston rod inserted into the inner tube. A piston is provided, and the oil chamber is partitioned into a piston rod side oil chamber in which the piston rod is accommodated and a piston side oil chamber in which the piston rod is not accommodated. It communicates with the piston rod side oil chamber of the oil chamber through the oil hole provided in the inner tube.

  And a check valve for forming a cross-sectional area S1 of the annular oil chamber to be equal to or larger than a cross-sectional area S2 of the piston rod and preventing flow from the oil chamber to the oil reservoir chamber during the extension side stroke of the partition member. And the oil discharged from the annular oil chamber and the piston rod side oil chamber in the extension side stroke passes only through the communication path provided in the piston rod.

  Furthermore, the communication path is provided in the piston rod and opens to the piston-side oil chamber; a small hole provided in the piston rod that communicates the hollow portion with the piston rod-side oil chamber; Provided on the piston rod, the hollow portion is composed of a small hole communicating with the oil reservoir chamber.

  As a result, when the piston rod enters the inner tube in the pressure side stroke, the oil in the piston side oil chamber compressed by the piston flows out into the oil reservoir chamber through the hollow portion and small hole of the communication path. The compression side damping force is generated by the aperture resistance of the small hole. At the same time, the oil in the oil reservoir is supplied to the piston rod side oil chamber expanded by the piston via the check valve.

  In this pressure side stroke, the oil corresponding to the volume of the piston rod entering the inner tube is transferred from the piston rod side oil chamber of the inner tube to the annular oil chamber through the oil hole of the inner tube. At this time, since the volume increase ΔS1 (replenishment amount) of the annular oil chamber becomes equal to or greater than the volume increase ΔS2 of the piston rod, the shortage of (ΔS1−ΔS2) of the required oil replenishment amount to the annular oil chamber is oil. The piston rod side oil chamber, and thus the annular oil chamber, is replenished from the reservoir chamber via a check valve.

  In addition, when the piston rod retracts from the inner tube during the extension side stroke, the oil in the piston rod side oil chamber compressed by the piston does not flow into the oil reservoir chamber due to the presence of the check valve, and the small hole ( And the hollow portion) and flows into the piston side oil chamber, and the expansion side damping force is generated by the restriction resistance of the small hole.

  In this extension side stroke, the oil corresponding to the retracted volume of the piston rod that retreats from the inner tube is transferred from the annular oil chamber to the piston rod side oil chamber of the inner tube and eventually to the piston side oil chamber through the oil hole of the inner tube. . At this time, since the volume decrease ΔS1 (discharge amount) of the annular oil chamber becomes equal to or greater than the volume decrease ΔS2 of the piston rod, the excess amount (ΔS1−ΔS2) of the oil discharge amount from the annular oil chamber is the piston. The oil is discharged from the rod side oil chamber to the oil reservoir chamber through a small hole, a hollow portion and a small hole in the communication path.

JP2010-38172

  In the hydraulic shock absorber described in Patent Document 1, the oil in the piston side oil chamber compressed by the piston flows upward through the hollow portion of the piston rod and flows out into the oil reservoir chamber in the compression side stroke, and in the extension side stroke. Of the oil discharge amount ΔS1 in the annular oil chamber, an excess amount (ΔS1−ΔS2) of the piston rod volume decrease ΔS2 flows upward through the hollow portion of the piston rod and flows out into the oil reservoir chamber. Therefore, in a normal operation state of the hydraulic shock absorber, an upward flow of oil always occurs in the hollow portion of the piston rod, and the hollow portion of the piston rod is filled with oil. The oil in the hollow portion of the piston rod becomes a head pressure on the lower oil chamber and the annular oil chamber of the inner tube.

  At this time, if the sealing performance of the partition member sealing the lower oil chamber of the inner tube with respect to the oil reservoir and the bushing sealing the annular oil chamber with respect to the oil reservoir is not perfect, Via a small hole communicating with the oil reservoir chamber of the rod, the air in the oil reservoir chamber enters the hollow portion of the piston rod, and the head pressure of the oil in the hollow portion of the piston rod causes the oil chamber or the annular oil chamber to Let the oil leak into the sump chamber. As a result, the oil level of the hollow portion of the piston rod is lowered below the small hole communicating with the oil reservoir chamber (the oil level of the hollow portion can be lowered until the oil level of the oil reservoir chamber becomes the same level. ).

  When the oil level of the hollow portion of the piston rod is lowered below the small hole communicating with the oil reservoir, the oil level of the hollow portion rises in the pressure side stroke until the oil fills the hollow portion. The oil in the piston-side oil chamber compressed by the piston does not pass through the small hole, and no compression-side damping force is generated due to the restriction resistance of the small hole. Causes response delay of compression side damping force.

  An object of the present invention is to avoid a response delay of a compression side damping force in a hydraulic shock absorber in which a piston is slidably contacted with an inner periphery of an inner tube.

  The invention according to claim 1 slidably inserts the inner tube into the outer tube through bushes fixed to the inner peripheral opening of the outer tube and the outer peripheral tip of the inner tube, An annular oil chamber surrounded by the inner periphery of the outer tube, the outer periphery of the inner tube, and the two bushes is partitioned, a partition member is provided on the inner periphery of the inner tube, and an oil chamber is partitioned in the lower portion, An oil reservoir chamber is defined in the upper part, a piston rod attached to the outer tube is slidably inserted into the partition member, and is slidably contacted with the inner periphery of the inner tube at the tip of the piston rod inserted into the inner tube. A piston is provided, and the oil chamber is divided into a piston rod side oil chamber in which the piston rod is accommodated and a piston side oil chamber in which the piston rod is not accommodated, and the annular An oil chamber is communicated with the piston rod side oil chamber through an oil hole provided in the inner tube, a cross-sectional area of the annular oil chamber is formed to be greater than a cross-sectional area of the piston rod, and the partition member A check valve is provided to prevent the flow from the oil chamber to the oil reservoir chamber during the extension stroke, and oil discharged from the annular oil chamber and the piston rod side oil chamber during the extension stroke is supplied to the piston rod. It is configured to pass through only the connecting path provided, and the connecting path is provided in the piston rod and opens to the piston-side oil chamber, and the piston rod is provided with the hollow part as the piston rod. In a hydraulic shock absorber comprising a small hole communicating with a side oil chamber and a small hole provided in the piston rod and communicating the hollow portion with the oil reservoir chamber, the outer periphery of the piston rod A check valve for preventing a flow from the oil reservoir chamber to the hollow portion of the piston rod is provided around the small hole provided in the piston rod and communicating with the oil reservoir chamber. is there.

  According to a second aspect of the present invention, in the first aspect of the present invention, the small hole provided in the piston rod and communicating with the oil reservoir chamber is configured as a throttle that generates a damping force of the compression side stroke. Is.

  The invention according to claim 3 is the invention according to claim 1 or 2, further comprising: a check valve provided around the small hole provided in the piston rod and communicating with the oil reservoir chamber; This is a damping valve that generates noise.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, further comprising: a check valve provided around the small hole provided in the piston rod and communicating with the oil reservoir chamber. This is a stopper rubber that regulates the maximum compression stroke of the tube.

(Claims 1 and 2)
(a) An outer periphery of the piston rod, which is provided on the piston rod and around the small hole communicating with the oil reservoir chamber, prevents flow from the oil reservoir chamber to the hollow portion of the piston rod. A check valve is provided. Therefore, even when the sealing performance of the partition member sealing the lower oil chamber of the inner tube to the oil reservoir and the bushing sealing the annular oil chamber to the oil reservoir is not perfect, The air in the oil reservoir chamber does not enter the hollow portion of the piston rod via the small hole communicating with the oil reservoir chamber of the piston rod. As a result, the head pressure of the oil in the hollow portion of the piston rod is The oil in the oil chamber or the annular oil chamber is not leaked to the oil reservoir chamber.

  As a result, the hollow portion of the piston rod and the small hole are surrounded by the check valve and are always filled with oil, and the oil in the piston side oil chamber compressed by the piston in the pressure side stroke passes through the small hole in the oil. It flows into the reservoir and generates a compression side damping force due to the throttle resistance of the small hole without a response delay.

(Claim 3)
(b) In the pressure side stroke, the oil flowing out through the small hole of the above (a) to the oil reservoir chamber pushes and opens the check valve, and the pressure side damping force can be obtained by the opening resistance of the check valve.

(Claim 4)
(c) The check valve can be made of an elastic body. This check valve made of an elastic body can also be used as a stopper rubber that restricts the maximum compression stroke of the inner tube, and the number of parts can be reduced.

FIG. 1 is a sectional view showing the entire hydraulic shock absorber. FIG. 2 is a lower cross-sectional view of FIG. FIG. 3 is a top sectional view of FIG. FIG. 4 is an enlarged cross-sectional view of the main part of FIG. FIG. 5 is a sectional view showing a fastening structure of the fork bolt, the piston rod, and the mounting bolt.

  As shown in FIGS. 1 to 4, the hydraulic shock absorber (front fork for a motorcycle) 10 is fixed to the outer periphery of the inner end of the lower end opening of the outer tube 11 and the outer periphery of the upper end opening of the inner tube 12. The inner tube 12 is slidably inserted into the outer tube 11 through the bush 12A. An oil seal 11C and a dust seal 11D are stored in a seal case 11B connected to the lower end opening of the outer tube 11. A fork bolt 13 is screwed into the upper end opening of the outer tube 11 in a sealed state. A bottom piece 15 is inserted in a sealed state at the lower end opening of the inner tube 12 and is prevented from coming off by a retaining ring 16 attached to the inner periphery of the inner tube 12, and a bottom bracket 17 is provided at the outer periphery of the lower end of the inner tube 12. The bolt 18 inserted and inserted into the through hole in the bottom portion of the bottom bracket 17 from the outside is screwed to the bottom piece 15 to draw the bottom piece 15, and the bottom bracket 17 is provided at the lower end portion of the inner tube 12.

  The hydraulic shock absorber 10 defines an annular oil chamber 20 surrounded by the inner circumference of the outer tube 11, the outer circumference of the inner tube 12, and the two bushes 11A and 12A.

  The hydraulic shock absorber 10 has a collar 31 with a lower annular plate (provided with a lower annular plate 32), an upper annular plate 33, a long collar 34, a washer on the inner periphery of the inner tube 12 whose inner diameter is increased stepwise. 35 are inserted in order, and these are caulked and held by the upper caulking portion 12B of the inner tube 12. The collar 31 with the lower annular plate and the upper annular plate 33 constitute a partition member 30 provided on the inner periphery of the inner tube 12. The oil chamber 21 is partitioned below the partition member 30 and the oil reservoir 22 is partitioned above. To do. In the oil reservoir chamber 22, the lower region is an oil chamber 22A, and the upper region is an air chamber 22B.

  In the hydraulic shock absorber 10, the fork bolt 13 is sealed and screwed into the screw hole 37 of the upper end opening of the outer tube 11 via an O-ring 37 </ b> A, and the outer peripheral flange 13 </ b> A of the fork bolt 13 is connected to the upper end surface of the outer tube 11. Lock it against. The upper end portion of the piston rod 40 is screwed into the screw hole 38 provided on the central axis of the fork bolt 13 from one side of the fork bolt 13 (inside the shock absorber), and the upper end surface of the piston rod 40 is connected to the screw hole 38. Lock against the top surface. The tip screw portion of the mounting bolt 19 that is inserted from the stepped bolt hole 39 provided on the other side of the fork bolt 13 (outside of the shock absorber) and engages in the axial direction is the top screw portion of the hollow portion 61 of the piston rod 40. Screwed to 61A. The mounting bolt 19 locks the head 19 </ b> A against the stepped surfaces of the large diameter hole and the small diameter hole of the stepped bolt hole 39, and an O-ring 39 </ b> A between the small diameter hole of the bolt hole 39 and the upper end surface of the piston rod 40. It is sealed through. Thereby, the piston rod 40 is attached to the fork bolt 13. The fastening structure of the fork bolt 13, the mounting bolt 19, and the piston rod 40 will be described later.

  The hydraulic shock absorber 10 slidably inserts a piston rod 40 attached to the fork bolt 13 of the outer tube 11 from the partition member 30 into the inner tube 12. A piston 41 that slides on the inner periphery of the inner tube 12 is provided at the tip of the piston rod 40 inserted into the inner tube 12. A piston ring 41 </ b> A is provided on the outer periphery of the piston 41. The piston 41 of the piston rod 40 divides the oil chamber 21 inside the inner tube 12 into a piston rod side oil chamber 21A in which the piston rod 40 is accommodated and a piston side oil chamber 21B in which the piston rod 40 is not accommodated.

  The hydraulic shock absorber 10 communicates the annular oil chamber 20 to the piston rod side oil chamber 21 </ b> A through an oil hole 20 </ b> A provided in the inner tube 12.

  In the inner tube 12, the hydraulic shock absorber 10 has a suspension spring 42 interposed between a lower end surface of the piston 41 facing the piston-side oil chamber 21B and an upper end surface of the bottom piece 15 facing the piston-side oil chamber 21B. ing. The hydraulic shock absorber 10 absorbs the impact force received from the road surface during traveling of the vehicle by the expansion and contraction of the suspension spring 42.

  In the hydraulic shock absorber 10, a stopper rubber 43 that contacts the lower surface of the fork bolt 13 is arranged around the outer periphery of the upper end of the piston rod 40, and a washer 45 that is backed up by a retaining ring 44 that is engaged with the outer periphery of the upper end of the piston rod 40 is stopped. Press against the lower surface of the rubber 43. When the hydraulic shock absorber 10 is most compressed, the upper end crimped portion 12B of the inner tube 12 abuts against the stopper rubber 43 via the washer 45, thereby restricting the maximum compression stroke.

  The hydraulic shock absorber 10 supports a rebound spring 46 disposed around the outer periphery of the lower end of the piston rod 40 on the upper surface of the piston 41. When the hydraulic shock absorber 10 is fully extended, the partition member 30 abuts on the rebound spring 46 to restrict the maximum extension stroke.

  However, in the hydraulic shock absorber 10, as shown in FIG. 4, the sectional area S 1 of the annular oil chamber 20 formed by the annular gap between the outer tube 11 and the inner tube 12 is changed to the sectional area (outer diameter) of the piston rod 40. Surrounding area) S2 or more.

  Further, in the partition member 30, the flow of oil from the piston rod side oil chamber 21 </ b> A to the oil reservoir chamber 22 is prevented in the extension stroke, and the oil flow from the oil reservoir chamber 22 to the piston rod side oil chamber 21 </ b> A in the compression stroke. Is provided with a partition check valve 50 that allows a replenishment amount to be supplied to the annular oil chamber 20 due to a difference ΔS between the sectional area S1 of the annular oil chamber 20 and the sectional area S2 of the piston rod 40. The partition check valve 50 is housed between the lower annular plate 32 and the upper annular plate 33 of the partition member 30, is shorter than the interval between the lower annular plate 32 and the upper annular plate 33, and is smaller in outer diameter than the inner diameter of the short collar 31. A cylindrical shape that slides up and down in contact with the outer periphery of the piston rod 40 is formed, and a lateral groove 51 is formed on the lower end surface. The partition check valve 50 is interposed between the lower annular plate 32 and a valve spring 52 made of a compression coil spring, and is biased toward the upper annular plate 33. In the pressure side stroke, the partition check valve 50 moves along with the piston rod 40 entering the inner tube 12 and moves downward, abuts on the lower annular plate 32, and forms a gap with the upper annular plate 33. The oil in the oil reservoir chamber 22 can be introduced from the lateral groove 51 into the piston rod side oil chamber 21A via its outer periphery. In the extension stroke, the partition check valve 50 moves along with the piston rod 40 that retreats from the inner tube 12, moves upward, abuts the upper annular plate 33, and closes the gap between the upper annular plate 33, The oil in the piston rod side oil chamber 21 </ b> A is prevented from being discharged into the oil reservoir chamber 22.

  The hydraulic shock absorber 10 is configured such that oil discharged from the annular oil chamber 20 and the piston rod side oil chamber 21 </ b> A passes through only the communication path 60 provided in the piston rod 40 in the extension side stroke. The communication path 60 of the present embodiment is provided in the piston rod 40 (including the piston 41) and opens to the piston-side oil chamber 21B, and the piston rod 40 is provided in the piston rod-side oil 61B. The small hole 62 communicates directly with the chamber 21 </ b> A and the small hole 63 provided in the piston rod 40 directly communicates the hollow portion 61 with the air chamber 22 </ b> B of the oil reservoir chamber 22.

  In the communication path 60 of the present embodiment, the hollow portion 61 and the small hole 63 serve as a throttle that generates a damping force in the compression side stroke, and the small hole 62 serves as a throttle that generates a damping force in the expansion side stroke.

  The small holes 62 of the communication path 60 are not limited to those in which the hollow portion 61 communicates directly with the piston rod side oil chamber 21A, but are provided in the piston 41 of the piston rod 40 so that the piston rod side oil chamber 21A is connected to the piston side. By communicating with the oil chamber 21B, the hollow portion 61 may be communicated with the piston rod side oil chamber 21A via the piston side oil chamber 21B.

  However, in the hydraulic shock absorber 10, the oil reservoir chamber 22 is disposed around the small hole 63 provided on the piston rod 40 and communicating with the air chamber 22 </ b> B of the oil reservoir chamber 22 on the outer periphery of the piston rod 40. A check valve 70 for preventing the flow from the air chamber 22B to the hollow portion 61 of the piston rod 40 is provided.

  The check valve 70 can be constituted by an elastic body such as rubber, or can be constituted by other materials and mechanisms. In this embodiment, the check valve 70 is shared with the stopper rubber 43 that regulates the maximum compression stroke of the inner tube 12, and is sandwiched between the inner surface of the fork bolt 13 and the washer 45 around the piston rod 40. It is set.

  The check valve 70 of this embodiment is formed of an annular body that surrounds the outer periphery of the piston rod 40 around the small hole 63. An annular space 70 </ b> A (FIG. 5) defined between the lower portion of the main body 71 of the check valve 70 and the outer periphery around the small hole 63 of the piston rod 40 is defined by an annular lip 72 provided on the upper inner periphery of the main body 71. The oil communicates with the hollow portion 61 and the oil chamber 21 of the piston rod 40 through the hole 63 and is always filled with the oil in the oil chamber 21 and the hollow portion 61. The oil flowing out from the annular space 70 </ b> A to the oil reservoir 22 pushes and opens the lip 72 of the check valve 70, rotates around the outer periphery of the lateral groove 73 provided in the upper portion of the main body 71 and the main body 71, and the oil chamber of the oil reservoir 22. Drop to 22A.

  The check valve 70 also constitutes a damping valve that generates a damping force in the compression side stroke.

The hydraulic shock absorber 10 operates as follows.
(Pressure side stroke)
In the compression side stroke, an oil flow indicated by a solid arrow in FIG. 4 is generated. That is, when the piston rod 40 enters the inner tube 12, the oil in the piston-side oil chamber 21 </ b> B compressed by the piston 41 passes through the hollow portion 61 and the small hole 63 of the communication path 60 and pushes the check valve 70 to open the oil. It flows into the reservoir chamber 22 and generates a compression side damping force by the throttle resistance of the hollow portion 61 and the small hole 63. At the same time, the oil in the oil reservoir 22 is supplied through the check valve 50 to the piston rod side oil chamber 21 </ b> A expanded by the piston 41.

  In this pressure side stroke, the oil corresponding to the volume of the piston rod 40 entering the inner tube 12 is transferred from the piston rod side oil chamber 21A of the inner tube 12 to the annular oil chamber 20 via the oil hole 20A of the inner tube 12. . At this time, since the volume increase ΔS1 (replenishment amount) of the annular oil chamber 20 becomes equal to or greater than the volume increase ΔS2 of the piston rod 40, the shortage of (ΔS1−ΔS2) in the required oil replenishment amount to the annular oil chamber 20 is insufficient. The oil is supplied from the oil reservoir 22 through the check valve 50 to the piston rod side oil chamber 21A and then to the annular oil chamber 20.

(Extension process)
In the extension side stroke, an oil flow indicated by a one-dot chain line arrow in FIG. 4 is generated. That is, when the piston rod 40 retreats from the inner tube 12, the oil in the piston rod side oil chamber 21 </ b> A compressed by the piston 41 does not flow into the oil reservoir chamber 22 due to the presence of the check valve 50, and the communication path 60 is small. It flows into the piston side oil chamber 21 </ b> B through the hole 62 (and the hollow portion 61), and the expansion side damping force is generated by the restriction resistance of the small hole 62.

  In this extension side stroke, the oil corresponding to the retraction volume of the piston rod 40 retreating from the inner tube 12 passes through the oil hole 20A of the inner tube 12 from the annular oil chamber 20 and the piston rod side oil chamber 21A of the inner tube 12 and eventually the piston. It is transferred to the side oil chamber 21B. At this time, since the volume decrease ΔS1 (discharge amount) of the annular oil chamber 20 becomes equal to or greater than the volume decrease ΔS2 of the piston rod 40, the excess (ΔS1−ΔS2) of the oil discharge amount from the annular oil chamber 20 The portion passes from the piston rod side oil chamber 21 </ b> A through the small hole 62, the hollow portion 61 and the small hole 63 of the communication path 60, pushes the check valve 70 open, and is discharged to the oil reservoir chamber 22.

Therefore, according to the present Example, there exist the following effects.
(a) On the outer periphery of the piston rod 40, around the small hole 63 provided on the piston rod 40 and communicating with the oil reservoir 22, the hollow of the piston rod 40 from the oil reservoir 22 A check valve 70 for blocking the flow to the portion 61 is provided. Accordingly, the partition member 30 that seals the lower oil chamber 21 of the inner tube 12 to the oil reservoir 22 and the sealability of the bush that seals the annular oil chamber 20 to the oil reservoir 22 are improved. Even if it is not complete, the air in the oil reservoir 22 does not enter the hollow portion 61 of the piston rod 40 via the small hole 63 communicating with the oil reservoir 22 of the piston rod 40. As a result, the piston The oil head pressure in the hollow portion 61 of the rod 40 does not cause the oil in the oil chamber 21 or the annular oil chamber 20 to leak into the oil reservoir chamber 22.

  Accordingly, the hollow portion 61 of the piston rod 40 and the small hole 63 are surrounded by the check valve 70 and are always filled with oil, and the oil in the piston-side oil chamber 21B compressed by the piston 41 in the pressure side stroke is contained in the oil. It flows into the oil reservoir chamber 22 through the small hole 63, and the compression side damping force due to the throttle resistance of the small hole 63 is generated without a response delay.

  (b) In the pressure side stroke, the oil flowing out through the small hole 63 of the above (a) to the oil reservoir chamber 22 pushes open the check valve 70 and obtains a pressure side damping force by the valve opening resistance of the check valve 70. Can do.

  (c) The check valve 70 can be formed of an elastic body. The check valve 70 made of this elastic body can also be used as the stopper rubber 43 that regulates the maximum compression stroke of the inner tube 12, and the number of parts can be reduced.

  Next, the fastening structure of the fork bolt 13, the mounting bolt 19, and the piston rod 40 in the hydraulic shock absorber 10 will be described. In the hydraulic shock absorber 10, as described above, the fork bolt 13 is sealed to the upper end portion of the outer tube 11, and the piston rod 40 is screwed to the fork bolt 13 from one side of the fork bolt 13 (inside the shock absorber). The mounting bolt 19 engaged from the other side of the fork bolt 13 (outside of the shock absorber) was screwed to the piston rod 40. At this time, the screw A (see FIG. 5) for screwing the piston rod 40 to the fork bolt 13 and the screw B (see FIG. 5) for screwing the mounting bolt 19 to the piston rod 40 were reversed to each other. That is, A is a left-hand thread and B is a right-hand thread. Or, A is a right-hand thread and B is a left-hand thread.

  The piston rod 40 is composed of a hollow rod having a hollow portion 61 communicating with the annular oil chamber 20, the oil chamber 21, and the oil reservoir chamber 22 as described above. The mounting bolt 19 is screwed to the upper end threaded portion 61 </ b> A of the hollow portion 61 of the piston rod 40.

The assembly procedure of the hydraulic shock absorber 10 is as follows.
(1) The piston rod 40 inserted from the lower end opening of the inner tube 12 is inserted into the partition member 30 attached to the upper end of the inner tube 12.

  (2) The bottom piece 15 is inserted into the lower end opening of the inner tube 12, and the bottom bracket 17 is provided at the lower end of the inner tube 12.

  (3) Insert the inner tube 12 into the outer tube 11.

  (4) The upper end of the piston rod 40 is temporarily fixed to the screw hole 38 of the fork bolt 13, and the fork bolt 13 is sealed in the screw hole 37 of the upper end opening of the outer tube 11 via an O-ring 37A and screwed. To wear.

  Using the stepped bolt hole 39 opened to the outside of the fork bolt 13 and the external opening end of the hollow portion 61 of the piston rod 40, the pressure test of the hydraulic shock absorber 10, the annular oil chamber 20, the oil chamber 21, the oil Oil is injected into the reservoir 22.

  (5) The mounting bolt 19 is passed through the stepped bolt hole 39 of the fork bolt 13, and this mounting bolt 19 is fastened to the upper end threaded portion 61A of the hollow portion 61 of the piston rod 40. As a result, the upper end portion of the piston rod 40 is The fork bolt 13 is permanently fixed to the screw hole 38.

Therefore, according to the present Example, there exist the following effects.
(a) In the hydraulic shock absorber 10, the fork bolt 13 is sealed to the upper end portion of the outer tube 11, and the piston rod 40 is screwed to the fork bolt 13 from one side of the fork bolt 13. A mounting bolt 19 engaged from the other side of the fork bolt 13 is screwed to the piston rod 40, a screw A for screwing the piston rod 40 to the fork bolt 13, and the piston rod 40 to the piston rod 40. The screws B to which the mounting bolts 19 are screwed are mutually reverse screws. Accordingly, when the piston rod 40 is assembled into the outer tube 11, the piston rod 40 is temporarily fixed to the fork bolt 13, the fork bolt 13 is fastened to the upper end portion of the outer tube 11, and then the mounting bolt 19 is attached to the piston rod 40. By fastening, the piston rod 40 is fastened to the fork bolt 13 and finally stopped. That is, in the process of fastening the mounting bolt 19 to the piston rod 40, for example, in the left-handed direction, when the piston rod 40 is rotated with the rotation of the mounting bolt 19, the piston rod 40 is fastened to the fork bolt 13 in the right-handed direction. It will be stopped. Accordingly, the piston rod 40 can be fastened to the fork bolt 13 by fastening the fork bolt 13 to the fork bolt 13 in a state where the fork bolt 13 is sealed to the upper end portion of the outer tube 11 in advance. Can be improved.

  (b) When a pressure test of the hydraulic shock absorber 10 is performed, a piston in which the mounting bolt 19 is not screwed in a state in which the fork bolt 13 to which the piston rod 40 is temporarily fixed is sealed to the upper end portion of the outer tube 11. The inspection compressed air is sent from the external opening end of the hollow portion 61 of the rod 40 to the oil chamber 21 and the oil reservoir chamber 22 for inspection. In the assembled state in which the fork bolt 13 is screwed, a pressure (pressure leakage) inspection can be performed.

  After the pressurization test, the mounting bolt 19 is fastened to the piston rod 40 according to the above-described (a), whereby the piston rod 40 is fastened to the fork bolt 13 and is finally fixed.

  (c) The external opening end of the hollow portion 61 of the piston rod 40 to which the mounting bolt 19 of the above (b) is not screwed can be used as an oil inlet to the oil chamber 21 and the oil reservoir chamber 22. This also makes it easy for the user to change the oil.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

  According to the present invention, an inner tube is slidably inserted into an outer tube through bushes fixed to the inner peripheral opening of the outer tube and the outer peripheral tip of the inner tube. An annular oil chamber surrounded by the circumference, the outer periphery of the inner tube, and the two bushes is defined, a partition member is provided on the inner periphery of the inner tube, an oil chamber is defined at the lower portion, and an oil reservoir is disposed at the upper portion. A chamber is defined, a piston rod attached to the outer tube is slidably inserted into the partition member, and a piston slidingly contacts the inner periphery of the inner tube at the tip of the piston rod inserted into the inner tube, The oil chamber is divided into a piston rod side oil chamber in which the piston rod is accommodated and a piston side oil chamber in which the piston rod is not accommodated, and the annular oil chamber is It communicates with the piston rod side oil chamber through an oil hole provided in the inner tube, and the cross-sectional area of the annular oil chamber is formed to be larger than the cross-sectional area of the piston rod. A check valve is provided to prevent the flow from the oil chamber to the oil reservoir chamber, and the oil discharged from the annular oil chamber and the piston rod side oil chamber in the extension side stroke is only the communication path provided in the piston rod. And the communication path is provided in the piston rod and is open to the piston-side oil chamber, and is provided in the piston rod and communicates the hollow portion with the piston rod-side oil chamber. And a small hole provided in the piston rod for communicating the hollow portion with the oil reservoir, the outer periphery of the piston rod, and the piston Around the small holes provided in the head communicates with the oil reservoir chamber, provided with a check valve that prevents flow to the hollow portion of the piston rod from the oil reservoir chamber. Thereby, in the hydraulic shock absorber in which the piston is slidably contacted with the inner periphery of the inner tube, a response delay of the compression side damping force can be avoided.

DESCRIPTION OF SYMBOLS 10 Hydraulic buffer 11 Outer tube 11A Bush 12 Inner tube 12A Bush 20 Annular oil chamber 20A Oil hole 21 Oil chamber 21A Piston rod side oil chamber 21B Piston side oil chamber 22 Oil reservoir chamber 30 Partition member 40 Piston rod 41 Piston 43 Stopper rubber 50 Check valve 60 Communication path 61 Hollow part 62, 63 Small hole 70 Check valve

Claims (4)

The inner tube is slidably inserted into the outer tube through bushes fixed to the inner peripheral opening of the outer tube and the outer peripheral tip of the inner tube,
An annular oil chamber surrounded by the inner periphery of the outer tube, the outer periphery of the inner tube, and the two bushes;
A partition member is provided on the inner periphery of the inner tube, and an oil chamber is defined in the lower portion, and an oil reservoir chamber is defined in the upper portion,
A piston rod attached to the outer tube is slidably inserted into the partition member,
A piston rod that is slidably contacted with the inner periphery of the inner tube is provided at the tip of the piston rod that is inserted into the inner tube, and the oil chamber includes a piston rod side oil chamber in which the piston rod is accommodated and a piston side in which the piston rod is not accommodated. Partition into an oil chamber,
The annular oil chamber communicates with the piston rod side oil chamber through an oil hole provided in the inner tube,
A cross-sectional area of the annular oil chamber is formed to be equal to or larger than a cross-sectional area of the piston rod, and a check valve is provided on the partition member to prevent the flow from the oil chamber to the oil reservoir chamber during an extension stroke. The oil discharged from the annular oil chamber and the piston rod side oil chamber in the extension side stroke is configured to pass only through the communication path provided in the piston rod,
A hollow portion provided in the piston rod and opened to the piston-side oil chamber; a small hole provided in the piston rod that communicates the hollow portion with the piston rod-side oil chamber; and the piston In the hydraulic shock absorber comprising a small hole provided in the rod and communicating with the hollow portion to the oil reservoir,
A check valve for preventing a flow from the oil reservoir chamber to the hollow portion of the piston rod around the small hole provided on the piston rod and communicating with the oil reservoir chamber on the outer periphery of the piston rod And a hydraulic shock absorber.   The hydraulic shock absorber according to claim 1, wherein the small hole provided in the piston rod and communicating with the oil reservoir chamber serves as a throttle that generates a damping force in a compression side stroke.   3. The hydraulic shock absorber according to claim 1, wherein a check valve provided on the piston rod and provided around the small hole communicating with the oil reservoir is a damping valve that generates a damping force in a compression side stroke.   The check valve provided in the periphery of the small hole provided in the piston rod and communicating with the oil reservoir chamber serves as a stopper rubber that regulates the maximum compression stroke of the inner tube. Hydraulic shock absorber.

Images