JP2006177493A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber optimally used to a damper-incorporated front-fork in which an oil lock is not caused, enabling a continuous compression operation even in the state in which a bellows is contracted to the utmost point where further contraction is impossible. <P>SOLUTION: In the hydraulic shock absorber, a reserver R is provided between an outer tube 1 and a damper cylinder 2, and an accumulator A is provided in the damper cylinder 2. It is characterized that the accumulator A is constituted of a connecting rod 5 connected to a cap 6, the bellows 20 fixed to the outside of a guide 4, gas chambers demarcated respectively in the inside of the bellows 20 and in the hollow of the cap 6 so as to be allowed to communicate with each other, and an oil chamber 8 demarcated in the outside of the bellows 20. A return spring 10 is provided between the cap 6 and the guide 4. Further, a through hole 19 is made in a damper cylinder 2 which allows the reserver R and the oil chamber 8 to communicate with each other, or cut off the communication. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic shock absorber suitable for use with 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 two-wheeled vehicle, and more particularly, an accumulator incorporated in a damper cylinder. The present invention relates to an improved hydraulic shock absorber.

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

  That is, this accumulator generally generates a stable predetermined damping force 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 coupled to the vehicle body side, an inner tube inserted into the outer tube 41, and a damper cylinder inserted into each tube, as shown in the embodiment of FIG. 42 and an accumulator A1 provided at the upper part in the damper cylinder 42.

  The accumulator A1 includes a bellows 46 having both ends coupled to a connecting rod 44 and a guide 45 coupled to the cap 43 side, a gas chamber 47 defined in the bellows 46, and an oil provided outside the bellows 46. Chamber 48.

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

  However, looking at the structure of the accumulator A1 having the bellows 46 described above, when the damper expands and contracts, the hydraulic fluid in the reservoir may enter the damper via 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 is deteriorated. It will be. In addition, the oil seal 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 rod in which a cap having a hollow portion is coupled to the end of the cylinder and an accumulator is coupled to the cap; a guide inserted slidably along the outer periphery of the connecting rod, the inner periphery of the damper cylinder, and the inner periphery of the hollow portion of the cap; A bellows fixed to the outside of the guide, a gas chamber defined inside the bellows and in the hollow portion of the cap and communicating with each other, and an oil chamber defined outside the bellows, and the cap and guide A return spring is interposed between the reservoir and the oil chamber. Is characterized in that a through hole for communicating or blocking is accompanied to the guide slide is formed in the damper cylinder.

  According to the invention of each claim, the hydraulic oil in the oil chamber in the accumulator is thermally expanded or the hydraulic oil flows into the damper, and the hydraulic oil amount increases. The guide moves against the reband spring even when it contracts the most, and the accumulator side oil chamber communicates with the reservoir side through the through hole, so excess hydraulic oil in the oil chamber is discharged to the reservoir side, and the damping force Is stable, there is no abnormally large operating resistance during compression, and it is possible to prevent an excessive load from being applied to the hydraulic shock absorber itself. As a result, it is possible to prevent damage to members such as the internal seal, The leakage of hydraulic oil can be prevented.

  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 has a damper cylinder 2 inserted into an outer tube 1 as shown in FIG. The reservoir R is provided between the outer tube 1 and the damper cylinder 2, and the accumulator A is provided in the damper cylinder 2.

  In the present invention, the cap 6 having a hollow portion is coupled to the end of the damper cylinder 2, and the accumulator A has an oil chamber 8 and gas chambers 7 and 9.

  That is, the accumulator A includes a connecting rod 5 coupled to the cap 6, a guide 4 inserted slidably along the outer periphery of the connecting rod 5, the inner periphery of the end of the damper cylinder 2, and the inner periphery of the hollow portion of the cap 6, and the guide 4 Bellows 20 which is an elastic partition member made of rubber, synthetic resin or the like fixed outside, gas chambers 7 and 9 which are respectively defined inside the bellows 20 and inside the hollow portion of the cap 6 and communicate with each other, and outside the bellows 20 And an oil chamber 8 defined in

  A return spring 10 is interposed between the main body of the cap 6 and the guide 4, and a through hole 19 is formed in the damper cylinder 2 for communicating or blocking the reservoir R and the oil chamber 8 with the slide of the guide 4. is doing.

  In this case, the piston 4C is provided at the end of the guide 4, and the cap 6 and the inner periphery of the damper cylinder 2 are slidably contacted with the seals D1 and D2 provided on the outer periphery of the piston 4C. 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 FIG. 2 show one embodiment of the present invention, and FIG. 3 shows another embodiment. The hydraulic shock absorber according to each embodiment is for motorcycles. It is applied as a damper built-in 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 these tubes. 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 pressure side damping valve 16.

  The accumulator A includes a connecting rod 5 provided at the end of the damper cylinder 2, a cylindrical guide 4 slidably inserted on the outer periphery of the connecting rod 5, a bellows 20 fixed to the outside of the guide 4, and a bellows 20 A gas chamber 7 defined inside the gas chamber 9, a gas chamber 9 defined in the hollow portion of the cap 6 and communicating with the gas chamber 7, and an oil chamber 8 defined outside the bellows 20. Has been.

  The upper end portion of the damper cylinder 2 is screwed inside the upper end portion of the outer tube 1, and a cap 6 having a hollow portion is screwed inside the upper end portion of the damper cylinder 2, and a connecting rod is provided at the center of the main body of the cap 6. The guide 4 is slidably inserted on 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 4C is in sliding contact with the inner periphery of the damper cylinder 2 and the inner periphery of the cap 6 via seals D1 and D2.

  A return spring 10 is interposed between the upper surface of the main body of the cap 6 and the inner peripheral step portion of the piston portion 4 </ b> C of the guide 4, and a stopper that is always formed on the connecting rod 5 by the reaction force of the return spring 10. It is made to contact | abut to the part 5a.

  A gas chamber 9 is defined in the hollow portion of the cap 6 and in the hollow portion of the piston portion 4 </ b> C, and the gas chamber 9 communicates with the gas chamber 7 inside the bellows 20 through the communication path 23.

  A plurality of radial through holes 19 are formed in the upper end portion of the damper cylinder 2, and the through holes 19 communicate with a reservoir R defined between the outer tube 1 and the damper cylinder 2, and The oil chamber 8 of the accumulator A is connected to the reservoir 3 when the biston part 4C moves left in the figure.

  That is, seals D1 and D2 are provided on the outer periphery of the piston portion 4C of the guide 4, and an oil passage 18 communicating from the bottom to the seals D1 and D2 is formed in the mounting groove of one seal D2. Normally, the oil passage 18 is closed with a seal D2.

Then, when the guide 4 slides to the left in the figure and the seal D2 faces the inside of the end diameter enlarged portion 2a of the damper cylinder 2, the seal D2 is moved in the outer diameter direction by the pressing force of the oil chamber 8 pressure or the self-restoring force. By expanding the diameter, the oil passage 18 is opened and communicates with the reservoir 3 through the through hole 19. According to the front fork, the outer tube 1 and the damper cylinder 2 are shown in FIG. When the oil chamber 12 contracts and the hydraulic oil corresponding to the piston rod intrusion volume enters the oil chamber 8 of the accumulator A through the compression side damping valve 16, a compression side damping force is generated. 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. 12, the bellows 20 is pressed by the internal pressure of the gas chamber 7 to expand, and at this time, an expansion side damping force is generated by a damping valve (not shown) provided on the piston coupled to the piston rod. .

  In the expansion / 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 bellows 20.

    However, when hydraulic oil enters the damper 11 from the reservoir R 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 increases. When the resistance of the return spring 10 or more is reached, the guide 4 slides along the inner periphery of the hollow portion of the cap 6 and the inner periphery of the damper cylinder 2 via the piston portion 4C, and moves leftward in the drawing along the connecting 5 rod.

  At this time, when the seal D2 moves to a position facing the enlarged diameter portion 2a, the seal D2 is enlarged in the outer diameter direction, the oil passage 18 is opened and the reservoir 19 is opened through the through hole 19, as shown in FIG. Excess hydraulic fluid is collected in the reservoir R in communication with R.

  That is, even if hydraulic oil enters the damper 11 from the reservoir R and the amount of hydraulic oil in the oil chamber 8 increases, excess hydraulic oil is discharged to the reservoir 3 side by the slide of the guide 4. It can be prevented that the compression resistance of the front fork increases due to the increase in the internal pressure in the oil chamber 8 and the riding comfort is deteriorated.

  FIG. 3 relates to another embodiment of the present invention, which is a modification of the front fork of FIG. 1, whereas the partition wall member 27 shown in FIG. 1 is fixed to the inner periphery of the damper cylinder 2. This partition member 27 is coupled to the connecting rod 5. The other structure is the same as that of the embodiment of FIG. Accordingly, the same structure as in FIG.

  That is, the front fork is provided with an accumulator A in the damper cylinder 2 in the same manner as the front fork of FIG. The inserted cylindrical guide 4, a bellows 20 made of a bellows fixed to the outside of the guide 4, a gas chamber 7 defined inside the bellows 20, and an oil chamber 8 defined outside the bellows 20. Is.

  In this embodiment, a partition member 27 that defines the oil chamber 8 and the oil chamber 12 in the damper cylinder 2 is provided at the end of the connecting rod 5, and the two oil chambers 8, 12 are provided in the partition member 27. The expansion side oil passage 13, the pressure side oil passage 14, and the throttle passage 24 that communicate with each other are provided. Furthermore, an extension side check valve 15 and a pressure side damping valve 16 are provided in the extension side oil passage 13 and the pressure side oil passage 14 so as to be freely opened and closed.

  In this embodiment, the structural member of the accumulator A and the partition member 27 are assembled in a cartridge manner, and disassembly is possible, and a desired damping force can be adjusted remotely via the variable throttle 25. Other functions and effects are the same as those of the embodiment of FIG.

  Further, in the embodiment of FIGS. 1 and 3, as described above, the guide 4 is formed with a communication passage that communicates the inner gas chamber 7 of the bellows 20 and the gas chamber 7 in the cap 6. The number, length, and inner diameter of 23 are set so that the squeezing effect is produced or is not produced, the bellows 20 is formed of a material with reduced rigidity and weight, or the gas chamber 7 in the bellows 206 is formed. It is also possible to adjust the desired damping force each time by setting the volume of the gas to zero or almost zero at the time of compression, or by adjusting the supply amount to the gas chambers 7 and 9 supplied from the valve 26. it can.

  In the above embodiment, the outer tube 1 is connected to the vehicle body side and the inner tube is connected to the wheel side. However, when the outer tube 1 is connected to the wheel side and the inner tube is connected to the vehicle body side. Even if it exists, this invention is applicable.

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 6 Cap 8 Oil chamber 10 Return spring 20 Bellows

Claims (5)

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 cap having a hollow portion is connected to the end of the damper cylinder. A connecting rod in which the accumulator is coupled to the cap, a guide inserted slidably along the outer periphery of the connecting rod, the inner periphery of the damper cylinder, and the inner periphery of the hollow portion of the cap, a bellows fixed to the outside of the guide, A gas chamber defined in the hollow portion of the cap and communicating with each other and an oil chamber defined outside the bellows, a return spring interposed between the cap and the guide, and the reservoir and the above described The oil chamber is communicated with or disconnected from the guide slide. Hydraulic shock absorber, wherein a through hole formed in the damper cylinder that. 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 an inner periphery of the hollow portion of the cap and an inner periphery of the damper cylinder while providing a seal on the outer periphery of the piston portion. 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. A partition member that defines an oil chamber and an oil chamber in the damper cylinder is provided at an end of the connecting rod, and an extension side oil passage, a pressure side oil passage, and a throttle passage that communicate the two oil chambers with the partition member. An extension side check valve and a pressure side damping valve are provided in the extension side oil passage and the pressure side oil passage so as to be openable and closable, respectively, and a variable throttle is provided in the throttle channel so as to be openable and closable. 3 hydraulic shock absorbers. The communication passage is formed in the guide to communicate the inner gas chamber of the bellows and the gas chamber in the hollow portion of the cap, and the number, length, and inner diameter of the communication passage are set so as to produce a throttling effect. 2, 3 or 4 hydraulic shock absorbers.

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