JP2005127373A - Hydraulic shock-absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock-absorber by which micro-vibrations are surely damped by friction means without increasing a parts count, and the degree of freedom is increased in tuning the damping-force of the friction means. <P>SOLUTION: The hydraulic shock-absorber is constituted so that a rebound rubber 10 controlling the stretch stroke of the piston rod 6 is mounted on the piston rod 6. A projection 12 is provided on the outside periphery of the rebound rubber 10, and the tip end of the projection 12 is brought into slide-contact with the inside peripheral surface of the cylinder 2. The slide-contact part of the cylinder 2 and the projection 12 serve as a friction means for damping the micro-vibration. Thus, the rebound rubber 10 is used also as friction means, so the parts-count can be reduced. Further, the inside diameter of the cylinder 2 to which the projection 12 is brought into slide-contact is large, and consequently the degree of freedom in tuning the damping-force is raised. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The invention of this application relates to a hydraulic shock absorber used for a vehicle suspension, and more particularly, to a hydraulic shock absorber provided with friction means for attenuating a wide range of fine vibrations including high-frequency vibrations in addition to the hydraulic damping means.

  A hydraulic shock absorber for a vehicle suspension has a damping valve (hydraulic pressure attenuating means) provided on a piston or the like housed in a cylinder, and the damping force is reduced by the flow resistance when the liquid in the cylinder passes through the damping valve. Occur.

  In recent years, in order to more effectively absorb micro-vibration such as when a vehicle passes through unevenness on the road surface, a frictional unit for micro-vibration attenuation has been devised in addition to the hydraulic pressure attenuation unit. (See Patent Document 1).

  This hydraulic shock absorber is attached to a rod guide that slidably supports the piston rod on one end of the cylinder, and a rubber friction material that elastically contacts the outer peripheral surface of the piston rod with a predetermined frictional resistance, and pushes it up from the road surface. A slight vibration caused by the above is attenuated by a frictional resistance between the friction material and the piston rod.

In this hydraulic shock absorber, a rubber friction material and a piston rod constitute the friction means. The friction material is not only a special rubber elastic body attached to the rod guide but also attached to the lower end of the rod guide. A rebound rubber that restricts the extension stroke of the piston rod has also been devised.
JP 2001-330074 A

  In the case of the hydraulic shock absorber adopting this latter, since the inner peripheral surface of the rebound rubber is used as the friction material, the number of parts can be reduced compared with the case where a separate friction material is provided, but the rebound rubber Since the available area between the piston rod and the piston rod is limited, the degree of freedom in tuning the frictional damping force is low, and a wide range of fine vibrations, especially high-frequency vibrations, can be reliably damped as intended. Is difficult.

  Therefore, the invention of this application can reliably attenuate a wide range of fine vibrations including high-frequency vibrations by the friction means without increasing the number of parts, and further increases the degree of freedom in tuning the damping force of the friction means. It is an object of the present invention to provide a hydraulic shock absorber that can be used.

  As a means for solving the above-mentioned problems, the invention of this application is such that a rebound rubber that abuts on a cylinder side member and regulates the extension stroke of the piston rod is attached to the piston rod, and the rebound rubber is attached to the inner peripheral surface of the cylinder. The sliding contact portion of the rebound rubber and the cylinder was used as a friction means for fine vibration attenuation.

  In the case of this invention, when a slight vibration is input between the piston rod and the cylinder, the rebound rubber slides against the inner peripheral surface of the cylinder, and the friction damping force generated at this time reliably absorbs the slight vibration. .

  It is desirable that a protrusion that is in sliding contact with the inner peripheral surface of the cylinder is provided on the outer peripheral surface of the rebound rubber, and the protrusion and the sliding contact portion of the cylinder serve as the friction means.

  In this case, since the rebound rubber is in sliding contact with the inner peripheral surface of the cylinder at the protrusion, the liquid in the cylinder can freely flow around the rebound rubber through the portion without the protrusion. Further, the generated damping force can be easily tuned by appropriately increasing or decreasing the number of protrusions.

  In the invention of this application, the rebound rubber attached to the piston rod is slidably contacted with the inner peripheral surface of the cylinder capable of ensuring a wide contactable area, and the sliding contact portion is a friction which attenuates a wide range of micro vibrations including high frequency vibrations. Therefore, the effect of reducing the number of parts by using the rebound rubber can be obtained, and the degree of freedom in tuning the friction damping force can be increased. Therefore, according to the invention of this application, a wide range of micro vibrations including high frequency vibrations can be reliably damped without causing an increase in manufacturing cost.

  Next, each embodiment of the invention of this application will be described with reference to the drawings.

  First, the first embodiment shown in FIGS. 1 to 3 will be described.

  The hydraulic shock absorber according to this embodiment has a so-called twin tube structure in which an outer tube 3 is arranged on the outer peripheral side of a cylinder 2 that houses a piston 1, and the upper ends of the cylinder 2 and the outer tube 3 are connected to a rod guide 4 and a packing. The piston rod 6 connected to the piston 1 passes through the rod guide 4 and the packing 5 and protrudes from the one end side of the cylinder 2 to the outside.

  The cylinder 2 and the outer tube 3 communicate with each other through a base valve (not shown) on the bottom side of both, and the inside of both is filled with liquid. Both the extension side and pressure side damping valves 7 and 8 are attached to the piston 1, and the outer tube 3 is filled with a predetermined amount of gas for allowing the liquid to enter and exit through the base valve.

  The rod guide 4 is formed into a substantially bottomed cylindrical shape by press molding, and is caulked and fixed to the upper end portion of the cylinder 2 together with the core portion 5 a of the packing 5. The rod guide 4 has an inner cylindrical portion 4a that rises upward from the bottom surface 4b, and a sliding member 9 for slidably supporting the piston rod 6 is held on the inner cylindrical portion 4a.

  Further, a rebound rubber 10 for restricting the extending stroke of the rod 6 is attached to a position of the piston rod 6 close to the piston 1. The rebound rubber 10 is formed in a thick annular shape, and the lower surface side thereof is vulcanized and bonded to the upper flange 11a of the metal cylindrical bracket 11, and the lower end of the cylindrical bracket 11 is welded, caulked, etc. It is being fixed to the outer peripheral surface. The upper surface of the rebound rubber 10 abuts against the bottom surface 4b of the rod guide 4 during the maximum stroke of the extending side of the piston rod 6, thereby restricting excessive displacement of the piston rod 6 with an elastic action.

  As shown in FIG. 2, the rebound rubber 10 has a plurality of protrusions 12 formed at equal intervals on the outer peripheral surface, and the tips of these protrusions 12 are in sliding contact with the inner peripheral surface of the cylinder 2. The tip of the protrusion 12 and the sliding contact portion of the cylinder 2 constitute a friction means in the invention of this application. When a slight vibration is input between the piston rod 6 and the cylinder 2, the rebound rubber 10 moves against the cylinder 2. Elasticity acts in the radial direction and viscoelasticity acts in the axial direction, and the sliding friction between them and the internal friction of the rubber material attenuates and absorbs the slight vibration. In the case of this hydraulic shock absorber, since the fine vibration between the piston rod 6 and the cylinder 2 needs to be attenuated mainly at the sliding contact portion between the rebound rubber 10 and the cylinder 2, the rebound rubber 10 is a packing that is in sliding contact with the piston rod 6. 5 and a material having a larger coefficient of friction than the outer peripheral surface of the piston 1 that is in sliding contact with the cylinder 2 are used. Specifically, for example, it is desirable to use an elastic material such as nitrile rubber.

  Further, in the case of this embodiment, the tip end of the protrusion 12 of the rebound rubber 10 is not formed in the entire axial direction along the inner surface of the cylinder 2, but as shown in FIG. It is formed to be inclined in a tapered shape so as to protrude to the side.

  Although the outer peripheral surface of the rebound rubber 10 is in sliding contact with the inner peripheral surface of the cylinder 2, a groove 13 is formed between the adjacent projections 12, 12, so that the liquid in the cylinder 2 passes through the groove 13 to rebound rubber. The upper and lower space portions can be freely distributed.

  Since the hydraulic shock absorber is configured as described above, the normal vibration input between the piston rod 6 and the cylinder 2 is damped by the hydraulic pressure damping action of the damping valves 7 and 8 of the piston 1 and the base valve. Fine vibrations such as push-up vibrations from the road surface are mainly damped by sliding friction between the rebound rubber 10 and the cylinder 2.

  In the case of this hydraulic shock absorber, the rebound rubber 10 is used to constitute the friction means for fine vibration damping, so that the number of parts does not increase, and the protrusions on the outer periphery of the rebound rubber 10 12 is slidably contacted with the inner peripheral surface of the cylinder 2 that can ensure a wide contactable area, so that there is an advantage that the degree of freedom in tuning for damping micro vibrations is high.

  That is, since the contact friction between the rebound rubber 10 and the cylinder 2 has a relatively large inner diameter, the number of the protrusions 12 and the shape of the contact portion can be freely changed. The optimum friction damping force that meets the needs of the vessel can be easily obtained.

Specifically, for example, in the above embodiment, the number of protrusions 12 of the rebound rubber 10 is set to six, but the number of protrusions 12 is set to three as in the second embodiment shown in FIG. May be set. Of course, the number of the protrusions 12 is not limited to this, and is arbitrary including one. In the above embodiment, the tip of the protrusion 12 of the reband rubber 10 is brought into contact with the inner peripheral surface of the cylinder 2 at a point a in the axial direction. However, as in the third embodiment shown in FIG. A plurality of points a ₁ and a ₂ may be brought into contact with the inner peripheral surface of the cylinder 2. Furthermore, the shape of the contact portion of the rebound rubber 10 with respect to the cylinder 2 is not limited to the edge shape, and may be a curved surface shape.

  FIG. 6 shows a fourth embodiment of the invention of this application. Hereinafter, although this embodiment is described, the same reference numerals are given to the same portions as those of the first embodiment shown in FIGS. 1 to 3, and the descriptions of the overlapping portions are omitted.

  This hydraulic shock absorber is substantially the same as that of the first embodiment, but the attachment structure of the rebound rubber 10 with respect to the piston rod 6 is different from that of the first embodiment.

  That is, the rebound rubber 10 is integrally vulcanized and bonded to the cylindrical bracket 111 as in the first embodiment. However, the cylindrical bracket 111 is attached to the rubber 10 from the lower surface side (piston 1 side) of the rebound rubber 10. The lower flange 111a is vulcanized and bonded to the lower surface of the rebound rubber 10 through the inside upward. A step portion 15 (stopper portion) that functions as a stopper is formed at a predetermined position on the outer periphery of the piston rod 6, and a male screw 16 is cut below the step portion 15 of the piston rod 6. The cylindrical bracket 111 to which the rebound rubber 10 is integrally attached is fitted to the piston rod 6 so that the upper end thereof is in contact with the stepped portion 15, and the nut 17 is screwed to the male thread 16 of the piston rod 6. The nut 17 and the step portion 15 are clamped and fixed.

  In this hydraulic shock absorber, the protrusion 12 on the outer periphery of the rebound rubber 10 is slidably contacted with the inner peripheral surface of the cylinder 2 as in the first embodiment, so that the number of parts can be reduced. At the same time, the degree of freedom in tuning the damping force increases. And in the case of this embodiment, in addition to being able to obtain such a basic effect, it is possible to replace the other main parts only by replacing the cylindrical bracket 111 with one having a different axial length. There is an advantage that a plurality of hydraulic shock absorbers having different extending strokes can be easily made.

  That is, in this embodiment, the step portion 15 and the male screw 16 are formed on the piston rod 6, and the cylindrical bracket 11 is sandwiched and fixed between the nut 17 and the step portion 15 that are screwed to the male screw 16. Therefore, if a plurality of cylindrical brackets 11 (rebound rubber 10 vulcanized and bonded) having different axial lengths are manufactured in advance, the rebound rubber 10 can be removed from the step portion 15 by replacing the cylindrical bracket 11. Those having different distances to the abutment surface (those having different extension strokes) can be easily made.

  Next, inventions other than the invention described in the above claims that can be grasped from the description of the embodiment described above will be described together with the effects thereof.

  (A) While providing a stopper portion on the piston rod, a rebound rubber is integrally attached to the cylindrical bracket, the cylindrical bracket is fitted to the piston rod so that one end is in contact with the stopper portion, and a nut is attached to the piston rod. The hydraulic shock absorber according to claim 1 or 2, wherein the cylindrical bracket is clamped and fixed by a nut and the stopper portion by screwing.

  In this case, the rebound rubber is attached to the piston rod by sandwiching and fixing the cylindrical bracket with a nut and a stopper, so that the hydraulic bracket with a different extension stroke can be obtained by replacing the cylindrical bracket with one having a different axial length. You can easily make a container.

BRIEF DESCRIPTION OF THE DRAWINGS The longitudinal cross-sectional view which shows 1st Embodiment of invention of this application. The cross-sectional view of the rebound rubber of the same embodiment. The expanded sectional view corresponding to the AA section of Drawing 2 of the rebound rubber of the embodiment. The cross-sectional view corresponding to FIG. 2 which shows 2nd Embodiment of invention of this application. The cross-sectional view corresponding to FIG. 3 which shows 3rd Embodiment of invention of this application. The longitudinal cross-sectional view corresponding to FIG. 1 which shows 4th Embodiment of invention of this application.

Explanation of symbols

1 ... Piston 2 ... Cylinder (friction means)
6 ... Piston rod 10 ... Rebound rubber 12 ... Projection (friction means)

Claims (2)

A piston is slidably accommodated in a cylinder filled with liquid, and a piston rod connected to the piston penetrates one end of the cylinder and protrudes outside the cylinder, and the liquid moves at the relative stroke between the piston rod and the cylinder. A hydraulic shock absorber that generates a damping force associated with the flow of, and is provided with friction means for damping fine vibrations,
A rebound rubber that abuts on the cylinder side member and regulates the extension stroke of the piston rod is attached to the piston rod, and the rebound rubber is brought into sliding contact with the inner peripheral surface of the cylinder, and the rebound rubber and the sliding contact portion of the cylinder are in contact with the friction. A hydraulic shock absorber characterized in that it is a means. 2. The hydraulic shock absorber according to claim 1, wherein a protrusion that slides on the inner peripheral surface of the cylinder is provided on an outer peripheral surface of the rebound rubber, and the protrusion and the sliding contact portion of the cylinder serve as the friction means. .

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