JP2006105354A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of a hydraulic shock absorber comprising a rebound member for not only preventing generation of noise but also improving durability in steering upon maximum extension of a piston rod. <P>SOLUTION: In this hydraulic shock absorber comprising a cylinder 3, a piston rod 5 movably inserted into the cylinder 3 through a piston, and a rebound member 8 mounted between an extension limit member 6 mounted on the cylinder 3 and a stopper member 7 mounted on the piston rod 5 for relieving shock in maximum extension of the piston rod 5, and formed into an approximately cylindrical elastic body where the rebound member 8 is inserted into the piston rod, an oil film discontinuation preventing means 15 is provided on an inner peripheral face 14 forming a contact portion of the rebound member 8 with the piston rod 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic shock absorber provided with a rebound member for alleviating an impact when a piston rod is fully extended.

  Conventionally, as a hydraulic shock absorber used for a vehicle or the like among hydraulic shock absorbers provided with a rebound member that relieves an impact when the piston rod is fully extended, the one shown in Patent Document 1 can be exemplified.

  This hydraulic shock absorber is a strut type hydraulic shock absorber, and as shown in FIG. 4, a rod guide 53 serving as an extension regulating member that seals the end of the cylinder 51 and pivotally supports the piston rod 52, and a piston Rebound as a rebound member in which a low-hardness rubber such as NBR or synthetic rubber is formed in a cylindrical shape on the upper surface of the flange member 54 between the flange member 54 as a stopper member provided on the base end side of the rod 52 A cushion 55 is placed.

In the hydraulic shock absorber, when the piston rod 52 is fully extended, as shown in FIG. 5, the rebound cushion 55 is restricted between the rod guide 53 and the flange member 54 while restricting the upper and lower surfaces thereof. By elastically deforming outward in the radial direction on the inner peripheral surface side of 51, the impact at the time of full extension is mitigated.
Japanese Patent Laid-Open No. 9-14328 (FIG. 3)

  The strut-type hydraulic shock absorber configured as described above is attached to the steering wheel side or the drive wheel side of the vehicle. When the strut type hydraulic shock absorber is attached to the steering wheel side, due to the suspension structure, the steering wheel of the driver is used. The entire hydraulic shock absorber needs to be steered about the axis of the piston rod 52 as the center of rotation.

  For this reason, conventionally, a structure in which the entire hydraulic shock absorber rotates with respect to the vehicle body is interposed between the hydraulic shock absorber and the vehicle body. May be fixed.

  In this case, as the steering wheel is steered, the cylinder 51 to which the rod guide 53 is fixed rotates about the piston rod 52, but the rebound cushion 55 is normally slidably inserted into the piston rod 52. In addition, since the outer peripheral surface 55a and the inner peripheral surface of the cylinder 51 are in a non-contact state, the piston rod 52 is fixed.

  However, for example, when the piston rod 52 lifts the vehicle body for vehicle maintenance or the like, as shown in FIG. 5, the upper and lower surfaces of the rebound cushion 55 are restricted and become the inner peripheral surface side of the cylinder 51. Since it is elastically deformed radially outward, the following problems may occur depending on the deformation state.

  That is, since the rebound cushion 55 is restricted from being freely deformed radially outward by the cylinder 51 disposed on the outer periphery of the rebound cushion 55, the outer peripheral surface 55a of the cylinder 51 is deformed when elastically deforming radially outward. And the inner peripheral surface 55b of the rebound cushion 55 are in pressure contact with the outer peripheral surface of the piston rod 52, respectively.

  For this reason, depending on the above-mentioned pressure contact condition, for example, the working oil at the contact portion between the inner peripheral surface 55b of the rebound cushion 55 and the outer peripheral surface of the piston rod 52 is scraped off, which may cause a so-called oil film breakage. Conceivable.

  Therefore, in this state, the above-mentioned handle operation is performed, and the rebound cushion 55 whose upper and lower surfaces and outer peripheral surface are regulated rotates integrally with the cylinder 51, and between the inner peripheral surface 55b and the outer peripheral surface of the piston rod 52. In the case of relative rotation, the outer peripheral surface of the piston rod 52 and the inner peripheral surface 55b of the rebound cushion 55 rotate relative to each other when the oil film runs out. There is concern about a decrease in durability of the cushion 55 itself.

  Therefore, the present invention was devised to solve the above problems, and its purpose is not only to prevent the generation of abnormal noise in the steered state when the piston rod is fully extended, The object of the present invention is to provide a structure of a hydraulic shock absorber provided with a rebound member that also improves durability.

  In order to achieve the above object, the present invention provides a cylinder, a piston rod movably inserted in the cylinder via a piston, an extension regulating member provided in the cylinder, and a stopper member provided in the piston rod. A rebound member that relieves an impact when the piston rod is fully extended, and is formed of a substantially cylindrical elastic body that inserts the rebound member into the piston rod. An oil film breakage preventing portion is provided on the inner peripheral surface serving as a contact portion.

According to the present invention, when the piston rod is fully extended, the hydraulic shock absorber itself is steered and the rebound member is subjected to turning power about the piston rod as a rotation center,
In some cases, the rebound member rotates integrally with the cylinder and relatively rotates between the inner peripheral surface of the rebound member and the outer peripheral surface of the piston rod.

  In this case, since the oil shortage preventing portion is provided on the inner peripheral surface that is a contact portion with the piston rod of the rebound member, the contact portion can be prevented from running out of oil. Such a contact portion between the inner peripheral surface of the rebound member and the outer peripheral surface of the piston rod can be prevented from rotating relative to each other when the oil film is cut.

  Therefore, it is possible to reliably wipe out the occurrence of abnormal noise due to this oil film breakage and the possibility of reducing the durability of the rebound member itself.

  Hereinafter, an embodiment in which the present invention is embodied in a strut type hydraulic shock absorber used in a suspension device on the side of a steering wheel of an automobile will be described with reference to the drawings.

  As shown in FIG. 1, the hydraulic shock absorber 1 includes an inner cylinder 3 as a cylinder inserted into the outer cylinder 2, and a piston inserted into the inner cylinder 3 via a piston (not shown). The rod 5, a rod guide 6 as an extension regulating member that seals the end of the inner cylinder 3 and pivotally supports the piston rod 5, a stopper member 7 provided on the proximal end side of the piston rod 5, and the stopper member 7 And a rebound cushion 8 as a cylindrical rebound member placed on the upper surface of the.

  Hereinafter, in detail, the outer cylinder 2 and the inner cylinder 3 are arranged concentrically, and the rod guide 6 is fitted over the inner periphery of the end of the outer cylinder 2 and the end of the inner cylinder 3. A guide hole 11 for guiding the piston rod 5 is provided at the center of the rod guide 6, and the piston rod 5 is slidably supported via an annular bearing member 12 fitted in the guide hole 11.

  A seal member 13 for sealing a gap with the piston rod 5 is disposed on the upper surface of the rod guide 6, and the rod guide 6 and the seal member 13 are attached to the outer cylinder by bending the end of the outer cylinder 2 inward and crimping. 2 and the inner cylinder 3 are fixed.

  The stopper member 7 is formed in a cylindrical shape having a flange portion 21 at an upper portion, and is inserted into the piston rod 5 and fixed to the upper portion of the piston which becomes the base end side of the piston rod 5 by welding or the like.

  The rebound cushion 8 which is the most characteristic configuration of the present invention placed on the flange portion 21 of the stopper member 7 is formed in a cylindrical shape from natural rubber, synthetic rubber or synthetic resin, and has an inner circumference. The surface 14 is slidably inserted with respect to the piston rod 5.

  In addition, four longitudinal grooves 15 whose both ends are open on both the upper and lower surfaces are provided on the inner peripheral surface 14 of the rebound cushion 8 at a predetermined interval, thereby constituting the oil film breakage preventing portion of the present invention. .

  These vertical grooves 15 are formed to have the same width and the same depth. As shown in FIG. 2, the vertical grooves 15 are formed on both sides of the grooves 15 by positively guiding the hydraulic oil into the vertical grooves 15. Further, the oil easily enters the contact portion between the inner peripheral surface 14 of the rebound cushion 8 and the outer peripheral surface of the piston rod 5 so that the oil does not run out.

  The hydraulic shock absorber 1 is attached via a rotation mechanism (not shown) so that the hydraulic shock absorber 1 is steered with the piston rod 5 fixed to the vehicle body.

  In the hydraulic shock absorber 1 configured as described above, when the piston rod 5 is fully extended, the rebound action 8 regulates the upper and lower surfaces between the rod guide 6 and the stopper member 7 as shown in FIG. While being elastically deformed outward in the radial direction on the inner peripheral surface side of the inner cylinder 3, the impact at the time of extension is alleviated.

  When the driver steers the steering wheel in this state, the hydraulic shock absorber 1 itself is steered, and the inner cylinder 3 rotates around the piston rod 5 as a rotation center.

  At this time, the rebound cushion 8 whose upper and lower surfaces and the outer peripheral surface are regulated may rotate integrally with the inner cylinder 3, and may rotate relatively between the inner peripheral surface 14 and the outer peripheral surface of the piston rod 5.

  However, four vertical grooves 15 are formed on the inner peripheral surface 14 of the rebound cushion 8 serving as a contact portion with the outer peripheral surface of the piston rod 5 as the oil film breakage preventing portion of the present invention. By actively guiding the oil into 15, the oil easily enters the contact portion between the inner peripheral surface 14 of the rebound cushion 8 formed on both sides of the longitudinal groove 15 and the outer peripheral surface of the piston rod 5, As a result, the aforementioned oil film breakage is prevented.

  Therefore, it is possible to surely wipe out the occurrence of abnormal noise due to this oil film breakage and the possibility of reducing the durability of the rebound cushion 8 itself.

  In the present embodiment, since the four vertical grooves 15 are provided on the inner peripheral surface 14 of the rebound cushion 8, the contact area with the outer peripheral surface of the piston rod 5 can be reduced, and the frictional resistance between them can be reduced. Can be reduced.

  In addition, this invention is not limited to said embodiment, For example, it can also be changed and actualized as follows.

  1) In the present embodiment, a plurality of vertical grooves 15 whose both end portions are open on both the upper and lower surfaces are provided on the inner peripheral surface 14 of the rebound cushion 8 to form the oil film breakage preventing portion of the present invention. Instead of the above, the oil film breakage preventing portion may be formed by forming a longitudinal groove 15 whose both ends are not open on both the upper and lower surfaces.

  Further, a plurality of minute irregularities may be provided on the inner peripheral surface 14 of the rebound cushion 8 to form the oil film breakage preventing portion.

  2) In the present embodiment, the vertical grooves 15 provided on the inner peripheral surface 14 of the rebound cushion 8 have the same width and the same depth. However, the present invention is not limited to this, and the width and depth are arbitrarily changed. The vertical groove 15 may be used.

  3) In the present embodiment, the double cylinder type strut type hydraulic shock absorber 1 is embodied, but it may be embodied as a single cylinder type hydraulic shock absorber.

  4) In the present embodiment, the present invention is embodied in the hydraulic shock absorber 1 for automobiles, but may be embodied in other hydraulic shock absorbers.

It is principal part sectional drawing of the hydraulic shock absorber which shows one embodiment of this invention. It is a top view which shows the rebound cushion part of FIG. It is principal part sectional drawing which shows the extended state of FIG. It is a partially broken sectional view showing a conventional example of the present invention. It is a partially broken sectional view which shows the extended state of FIG.

Explanation of symbols

1 Hydraulic shock absorber 3 Inner cylinder (cylinder)
5 Piston rod 6 Rod guide (extension control member)
7 Stopper member 8 Rebound cushion (Rebound member)
14 Inner peripheral surface 15 Longitudinal groove (oil film breakage prevention member)

Claims (3)

Impact between the cylinder, the piston rod movably inserted into the cylinder via the piston, the extension regulating member provided on the cylinder, and the stopper member provided on the piston rod, when the piston rod is extended. And a rebound member that is formed of a substantially cylindrical elastic body that inserts the rebound member into the piston rod. An oil film is formed on the inner peripheral surface of the rebound member that is in contact with the piston rod. A hydraulic shock absorber provided with a cut prevention portion. The rebound member is formed of a natural rubber, a synthetic rubber, or a synthetic resin into a cylindrical shape, and a plurality of vertical grooves whose both end portions are open on both the upper and lower sides are provided on the inner peripheral surface of the rebound member as the oil film breakage preventing portion. Item 1. The hydraulic shock absorber according to Item 1. 2. The hydraulic shock absorber according to claim 1, wherein the rebound member is formed of a natural rubber, a synthetic rubber, or a synthetic resin into a cylindrical shape, and a plurality of minute irregularities are provided on an inner peripheral surface thereof to form the oil film breakage preventing portion. .

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