JP2006189085A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber suitable for application to a damper built-in type front fork which can maintain pressure in a damper at a designated pressure level, even though working oil enters the damper from a reservoir. <P>SOLUTION: The hydraulic shock absorber comprises a connecting rod 5 which combines a hollow cap 6 on an end of a damper cylinder 2 and also combines an accumulator A on the cap 6, a guide 4 slidably inserted along an outer periphery of the connecting rod 5 and an inner periphery of the cap 6, an elastic partition member 20 fixed on the outside of the guide 4, gaseous chambers respectively formed in the inside of the elastic partition member 20 and the cap 6, and an oil chamber 8 formed on the outside of the elastic partition member 20. A return spring 10 is sandwiched between the cap 6 and guide 4, and a through-hole which allows and blocks communication between a reservoir R and the oil chamber 8 in response to a slide of the guide is formed on the cap 6 and damper cylinder 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic shock absorber suitable for the use of a front fork that also serves as a fork and a shock absorber that is interposed between a vehicle body and an axle of a motorcycle to attenuate vibrations from a road surface, and is particularly incorporated in a damper cylinder. The present invention relates to a hydraulic shock absorber having an improved accumulator.

  In general, as a hydraulic shock absorber such as a motorcycle built-in front fork for a motorcycle, for example, as shown in Patent Document 1, an accumulator is provided in a damper cylinder to compensate an internal pressure in the damper.

  In other words, this accumulator is generally configured so that a stable damping force can be generated without generating a negative pressure in the damper during expansion by appropriately setting the gas pressure in the gas chamber.

  The hydraulic shock absorber shown in Patent Document 1 includes an outer tube 41, an inner tube inserted into the outer tube 41, a damper cylinder 42 inserted into each tube, and a damper cylinder, as shown in the embodiment of FIG. The accumulator A1 provided in the upper part in 42 is provided.

  The accumulator A1 includes an elastic partition member 46 made of a bladder or the like coupled to both the connecting 44 and the guide 45 coupled to the cap 43 side, a gas chamber 47 defined in the elastic partition member 46, The oil chamber 48 is provided outside the prada 46.

Therefore, by appropriately setting the internal pressure in the gas chamber 47, the internal pressure in the damper is not negative even when the damper built-in front fork as the hydraulic shock absorber is in the fully extended state. From the beginning of the contraction operation from the state, a predetermined compression side damping force can be generated by the damper.
Japanese Utility Model Publication 4-525D2 (Utility Model Registration Request (2), (4))

  However, when looking at the structure of the accumulator A1 having the elastic partition wall member 46, when the damper expands and contracts, the hydraulic fluid in the reservoir may enter the damper through the piston rod sliding portion or the like.

  For this reason, when the amount of hydraulic oil in the damper increases, the pressure in the damper rises, and when the amount of hydraulic oil increases significantly, the resistance at the time of contraction operation of the front fork increases and the riding comfort deteriorates. In addition, the oil seal and the like in the damper may be damaged by the high pressure action.

  The present invention has been developed in view of such a current situation, and an object of the present invention is to maintain the pressure in the damper at a desired pressure even when hydraulic oil enters the damper from the reservoir. It is an object of the present invention to provide a hydraulic shock absorber that is optimal for use in a damper built-in front fork.

  In order to achieve the above object, the means of the present invention is a hydraulic shock absorber in which a damper cylinder is coupled in an outer tube, a reservoir is provided between the outer tube and the damper cylinder, and an accumulator is provided in the damper cylinder. A connecting cap with a hollow cap connected to the end of the cylinder and an accumulator connected to the cap, a guide inserted slidably along the outer periphery of the connecting rod and the inner periphery of the cap, and an elastic partition member fixed to the outside of the guide A gas chamber defined inside and inside the cap and communicating with each other, and an oil chamber defined outside the elastic partition member, and a return spring between the cap and the guide. In addition, the reservoir and the oil chamber communicate with each other as the guide slides. It is characterized in that the formation of the hole to be cut off in the damper cylinder.

  According to the invention of each claim, the hydraulic oil in the oil chamber in the accumulator thermally expands or the hydraulic oil in the damper flows in, and the amount of hydraulic oil increases. The guide moves against the return spring even when the member contracts to the maximum, and the oil chamber on the accumulator side is connected to the reservoir side via the communication hole, so that the hydraulic oil in the oil chamber is discharged to the reservoir side and the damping force It is possible to prevent the hydraulic shock absorber itself from being overloaded, and as a result, damage to internal seals and other components can be prevented. This prevents the leakage of hydraulic oil.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A damper built-in front fork as a hydraulic shock absorber according to the present invention includes a damper cylinder 2 inserted into an outer tube 1 as shown in FIG. The reservoir R is connected between the outer tube 1 and the damper cylinder 2, and the accumulator A is provided in the damper cylinder 2.

  And in this invention, the hollow cap 6 is couple | bonded with the edge part of the damper cylinder 2, and the connecting rod 5 which couple | bonded the accumulator A with the cap 6 is inserted along the outer periphery of the connecting rod 5, and the inner periphery of the cap 6 so that sliding is possible. The guide 4, the elastic partition member 20 fixed to the outside of the guide 4, the gas chambers 7 and 9 defined in the inside of the elastic partition member 20 and the cap 6 and communicating with each other, and the outside of the elastic partition member 20 And an oil chamber 8 defined in

  Further, a return spring 10 is interposed between the cap 6 and the guide 4, and further, through holes 18A, 18B, 18C for communicating or blocking the reservoir R and the oil chamber 8 with the slide of the guide 4, and Through holes 19 are formed in the cap 6 and the damper cylinder 2, respectively.

  In the above case, the piston 4C is provided at the end of the guide 4, and the piston 4C is brought into sliding contact with the inner periphery of the cap 6 via the seals D1 and D2 provided on the inner periphery of the cap 6.

  A seal D3 is provided between the inner periphery of the cylindrical body 4B of the guide 4 and the outer periphery of the connecting rod 5.

  1 and 2 show one embodiment of the present invention, and FIG. 3 shows another embodiment. The hydraulic shock absorber according to each embodiment is a motorcycle. It is applied as a damper built-in type front fork.

  As shown in FIG. 1, this front fork has an inner tube (not shown) as a wheel side tube slidably inserted into an outer tube 1 as a vehicle body side tube, and a damper 11 is built in each tube. An accumulator A is provided above the damper 11.

  The damper 11 includes a damper cylinder 2, a piston rod (not shown) inserted through the piston into the damper cylinder 2, an oil chamber 12 defined by the piston and the partition member 27, The accumulator A defined above, the expansion side oil passage 13 and the pressure side oil passage 14 which are provided in the partition wall member 27 and connect the accumulator A and the oil chamber 12, and can be opened and closed in the middle of the oil passages 13 and 14, respectively. Are provided with an extension side check valve 15 and a damping valve 16.

  The accumulator A is composed of a connecting rod 5 provided at an end of the damper cylinder 2, a cylindrical guide 4 slidably inserted on the outer periphery of the connecting rod 5, an elastic partition wall made of a bladder fixed to the outside of the guide 4, and the like. A member 20, a gas chamber 7 defined inside the elastic partition member 20, and an oil chamber 8 defined outside the elastic partition member 20 are configured.

  The upper end of the damper cylinder 2 is screwed inside the upper end of the outer tube 1, and a hollow cap 6 is screwed inside the upper end of the damper cylinder 2. A connecting rod 5 is coupled to the center of the cap 6. The guide 4 is slidably inserted into the outer periphery of the connecting rod 5.

  The guide 4 is formed in a cylindrical body 4B, thick bases 4A and 4D at both ends of the main body 4B, a piston part 4C connected to the upper thick base 4A, and an upper thick base 4A. The piston portion 4 </ b> C is in sliding contact with the inner periphery of the cap 6 through seals D <b> 1 and D <b> 2 provided on the inner periphery of the cap 6.

  A return spring 10 is interposed between the upper surface of the cap 6 and the inner peripheral step of the guide 4 and a gas chamber 9 is defined. The gas chamber 9 is connected to the accumulator A via the communication path 23. It communicates with the gas chamber 7 on the side.

  The guide 4 is always in contact with a stopper portion 5 a formed on the connecting rod 5 by the reaction force of the return spring 10.

  A radial through hole 19 is formed in the upper end portion of the damper cylinder 2, and other through holes 18 A, 18 B, 18 C are formed in the cylindrical portion of the cap 6, and these through holes 18 A, 18 B, 18 C and 19 are formed. Is communicated with a reservoir R defined between the outer tube 1 and the damper cylinder 2, and when the piston portion 4C of the guide 4 moves leftward in the figure, the upper annular groove 4E of the guide 4 faces the through hole 18A. As a result, the oil chamber 8 of the accumulator A is connected to the reservoir R.

  That is, a through hole 18A located between the seals D1 and D2 is formed in the cylindrical portion of the cap 6, the guide 4 slides to the left in the figure, and when the annular groove 4E faces the seal D2, the pressure of the oil chamber 8 is increased. The seal D <b> 2 is expanded in the outer diameter direction by a pressing force or a self-restoring force so that the oil passage is opened and communicates with the reservoir R through the through hole 19.

  According to the front fork described above, in the compression operation, the outer tube 1 and the damper cylinder 2 move rightward in the drawing, the oil chamber 12 contracts, and the hydraulic oil for the piston rod intrusion volume flows through the compression side damping valve 16. The pressure side damping force is generated by entering the oil chamber 8 of A, and at this time, the elastic partition member 20 contracts.

  During the extension operation, the outer tube 1 and the damper cylinder 2 move leftward in the figure, and at this time, the oil chamber 12 expands, and the hydraulic oil corresponding to the piston rod retreats from the oil chamber 8 of the accumulator A through the check valve 15. At this time, the elastic partition wall member 20 is pressed by the internal pressure of the gas chamber 7 to expand, and at this time, the expansion side damping force is applied by a damping valve (not shown) provided on the piston coupled to the piston rod. appear.

  In the expansion and contraction operation in which the hydraulic oil does not enter the damper 11 from the reservoir R, the change in the oil amount corresponding to the piston rod intrusion volume generated on the oil chamber 12 side is compensated by the contraction and expansion of the elastic partition wall member 20.

  However, when the hydraulic oil enters the damper 11 from the reservoir R due to the leaked oil and the hydraulic oil in the damper 11 increases, the internal pressure in the oil chamber 8 increases during the compression operation, and the thrust in the left direction in the figure with respect to the guide 4 is increased. When it becomes larger and exceeds the drag force of the return spring 10, the guide 4 slides along the inner periphery of the cap 6 through the piston portion 4C and moves left along the connecting 5 rod.

  At this time, when the annular groove 4E moves to a position facing the seal D2, as shown in FIG. 2, the diameter of the seal D2 increases in the outer diameter direction, and an oil passage as a gap between the seal D2 and the annular groove 4E is formed. The oil chamber 8 communicates with the reservoir R through the through holes 18A, 18B, 18C and the through hole 19, and excess hydraulic oil is collected in the reservoir R.

  That is, even if the hydraulic oil expands thermally or leaks from the reservoir R into the damper 11 due to leakage and the amount of hydraulic oil in the oil chamber 8 increases, the excess hydraulic oil is slid by the slide of the guide 4. Is discharged to the reservoir R side, so that it is possible to prevent the compression resistance of the front fork from increasing due to the increase of the internal pressure in the oil chamber 8 and the ride comfort.

  FIG. 3 relates to another embodiment of the present invention, which is a modification of the front fork of FIG. 1, in which the piston portion 4C of the guide 4 is formed thick and a seal D1 is formed on the outer periphery of the piston portion 4C. , D2 is provided, and the other structural effects are the same as those of the embodiment of FIG. 1. Therefore, the same structure as that of FIG.

  In the embodiment shown in FIGS. 1 and 3, as described above, the guide 4 is formed with a communication path that connects the inner gas chamber 7 of the elastic partition wall member 20 and the gas chamber 7 in the cap 6. The number, the length, and the inner diameter of 23 are set so that the drawing effect is produced or not produced, and the elastic partition member 20 is formed of a material with reduced rigidity and weight, or the gas in the cap 6 A desired damping force is adjusted each time by setting the volume of the chamber 7 to zero or almost zero at the time of maximum compression, or by adjusting the supply amount to the gas chambers 7 and 9 supplied from the valve 26. You can also.

1 is a partially longitudinal front view of a front fork according to an embodiment of the present invention. It is sectional drawing at the time of the most compression of FIG. It is a partially longitudinal front view of a front fork according to another embodiment. It is a partial longitudinal front view of the conventional front fork.

Explanation of symbols

A accumulator R reservoir 1 outer tube 2 damper cylinder 4 guide 5 connecting rod 5 cap 8 oil chamber 10 return spring 18A, 18B, 18C through hole 19 through hole 20 elastic partition member

Claims (4)

In a hydraulic shock absorber in which a damper cylinder is connected in the outer tube, a reservoir is provided between the outer tube and the damper cylinder, and an accumulator is provided in the damper cylinder, a hollow cap is connected to the end of the damper cylinder, and the accumulator A connecting rod coupled to the cap, a guide inserted slidably along the outer periphery of the connecting rod and the inner periphery of the cap, an elastic partition member fixed to the outside of the guide, an inner side of the elastic partition member, and an inner portion of the cap. The gas chamber communicated with each other and an oil chamber defined outside the elastic partition wall member, a return spring is interposed between the cap and the guide, and the reservoir and the oil chamber are connected to the guide. The through-hole that communicates or shuts off with the slide of the cap and the damper sill Hydraulic shock absorber, characterized in that formed on. 2. The hydraulic shock absorber according to claim 1, wherein a piston portion is provided at an end of the guide, and the piston portion is slidably contacted with the inner periphery of the cap while a seal is provided on the outer periphery of the piston portion or the inner periphery of the cap. The hydraulic shock absorber according to claim 1 or 2, wherein a seal is provided between the inner periphery of the guide and the outer periphery of the connecting rod. The communication passage is formed in the guide so as to communicate the inner gas chamber of the elastic partition member and the gas chamber in the cap, and the number, length, and inner diameter of the communication passage are set so as to produce a throttling effect. 2 or 3 hydraulic shock absorbers.

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