JP2006132620A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of a shock absorber having a rebound member which does not produce uncomfortable noises and shocks when a piston rod extends to a far end. <P>SOLUTION: The shock absorber comprises a cylinder 3, the piston rod 5 movably inserting into a cylinder 3 via a piston 4, and the rebound member 8 which is arranged between an extended restriction member 6 arranged on the cylinder 3 and a stopper member 7 arranged on the piston rod 5 and relieves shocks produced when the piston rod extends to the far end. In the hydraulic shock absorber in which the rebound member 8 provides a compressive coil spring 22 so as to make axially adjacent coil sections 35 bring into contact with each other when the piston rod extends to the far end, connecting sections 25 and 26 which connect the adjacent coil sections 35 at the time of their contact are arranged in the coil spring 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Conventionally, as a hydraulic shock absorber provided with a rebound member that alleviates an impact when the piston rod is fully extended, the one shown in Patent Document 1 can be exemplified.

  This hydraulic shock absorber has both ends between a rod guide as an extension regulating member that seals the cylinder end and pivotally supports the piston rod, and a flange member as a stopper member provided on the base end side of the piston rod. A rebound member made of a coil spring fitted with a guide is interposed.

In this hydraulic shock absorber, the coil spring is compressed when the piston rod is fully extended, so that the impact when the piston rod is fully extended is alleviated.
Japanese Patent Laid-Open No. 7-238980 (FIG. 1)

  However, in the hydraulic shock absorber configured as described above, the following problems can be considered.

  That is, when the piston rod is fully extended, the coil spring is also in the most compressed state, so that the coil portions constituting the coil spring are closely in close contact with each other in the axial direction.

  At this time, as shown in FIG. 7, in the coil spring 41 having the conventional structure, the wire constituting the coil spring 41 is formed in a circular cross section. Point contact with each other.

  However, the process of reaching the above-mentioned fully extended state varies depending on the usage conditions of the hydraulic shock absorber.For example, if the piston speed is slow and it may reach the fully extended state, the piston speed is high and the fully extended state is reached. You may be greeted.

  Therefore, for example, when adjacent coil portions 42 come into contact with each other at a high piston speed, the coil portions 42 slide due to a small contact resistance between them, and some of the coil portions 43 are pistons as shown in FIG. It is assumed that the rod 45 protrudes toward the outer peripheral side of the rod 45 or the inner peripheral side of the cylinder.

  In this case, it is conceivable that the outer or inner end of the protruding coil portion 43 contacts the inner periphery of the cylinder or the outer periphery of the piston rod 45 to generate an unpleasant sound or impact.

  Accordingly, the present invention was devised to solve the above-described problems, and its purpose is to provide a shock absorber provided with a rebound member that does not generate unpleasant noise or impact when the piston rod is fully extended. Is to provide a structure.

  In order to achieve the above object, the present invention provides a cylinder, a piston rod movably inserted into the cylinder via a piston, an extension regulating member provided on the cylinder, and a stopper member provided on the piston rod. A rebound member that relieves an impact when fully extended, and the rebound member includes a compressible coil spring so that adjacent coil portions contact each other in the axial direction when fully extended. The coil spring is provided with an engaging portion for engaging adjacent coil portions at the time of contact.

  According to the present invention, when the rebound member interposed between the extension restriction member and the stopper member is extended to make the coil spring in a compressed state, the coil portions are connected to each other by the engaging portion provided on the coil spring. Since they are connected, slippage in the radial direction between the coil portions can be prevented.

  Therefore, as in the prior art, some coil portions protrude toward the outer peripheral side of the piston rod or the inner peripheral side of the cylinder, and the outer or inner end of the protruding coil portion contacts the inner periphery of the cylinder or the outer periphery of the piston rod. Therefore, it is possible to reliably prevent the possibility of generating unpleasant sounds and impacts.

  Hereinafter, an embodiment in which the present invention is embodied in a strut type hydraulic shock absorber for use in an automobile suspension device 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 rod 5 inserted into the inner cylinder 3 through a piston 4 so as to be freely retractable. , A rod guide 6 serving 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 the rod guide 6 And a rebound member 8 interposed therebetween.

  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 piston 4 is inserted into the proximal end portion of the piston rod 5 and fixed by a nut 15, and the inner cylinder 3 is partitioned into a rod chamber R and a piston chamber P by the piston 4.

  Further, a pressure side valve 16 is provided on the side surface of the rod chamber R of the piston 4 so as to open and close a pressure side port (not shown). A side valve 18 is provided.

  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 4 serving as the base end side of the piston rod 5 by welding or the like.

  And the rebound member 8 which is the most characteristic configuration of the present invention interposed between the flange portion 21 of the stopper member 7 and the rod guide 6 is fitted to the coil spring 22 and both ends thereof. The upper and lower holders 23 and 24 are made of synthetic resin.

  As shown in FIG. 2, the coil spring 22 includes a plurality of coil portions 35 adjacent to each other in the axial direction formed by coiling a wire 34 having a substantially square cross section. A groove-like concave portion 25 and a convex portion 26 having an inverted cross-sectional shape facing the concave portion 25 are formed on the lower surface.

  The concave portion 25 and the convex portion 26 may be formed continuously along the axis of the wire 34 or may be partially spaced.

  Therefore, in the compressed state of the coil spring 22 when fully extended, the coil portions 35 adjacent to each other in the vertical direction are in contact with each other, and as shown in FIG. The respective coil portions 35 are connected to each other by the engagement of the provided concave portion 25 and convex portion 26.

  In addition, the coil part 35 in this invention shows all the circumference parts which can be obtained by coiling the wire 34, and shall use it as a concept containing all the circumference parts which comprise what is called an end winding part and a pitch part.

  The upper holder 23 and the lower holder 24 are provided with insertion holes 23 a and 24 a for inserting the piston rod 5. The lower holder 24 is press-fitted and fixed to the piston rod 5 on the inner surface of the insertion hole 24 a of the lower holder 24. A rib (not shown) is formed.

  The upper holder 23 includes a cylindrical holder main body 28, a fitting portion 29 having an outer diameter smaller than that of the holder main body 28, and a tapered portion 30 extending from the fitting portion 29. The upper end portion of the coil spring 22 is guided by the taper portion 30 and is fitted into the fitting portion 29.

  In addition, a plurality of protrusions 27 as silencing members having a mountain-shaped cross section are arranged on the upper surface of the upper holder 23 at a predetermined interval, and when the upper holder 23 comes into contact with the rod guide 6 when fully extended. , The buffering action is exhibited so that no abnormal noise or the like is generated.

  In the present embodiment, the same synthetic resin as that of the upper holder 23 is used as an elastic material that constitutes the protrusion 27, whereby the protrusion 27 is formed integrally with the formation of the upper holder 23.

  The lower holder 24 includes a cylindrical holder main body 28, a fitting portion 29 having an outer diameter smaller than that of the holder main body 28, and a tapered portion 30 extending from the fitting portion 29. The lower end portion of the coil spring 22 is guided by the taper portion 30 and is fitted to the fitting portion 29.

  In the figure, 31 is a spring seat welded and fixed to the outer periphery of the outer cylinder, and 32 is a bump stopper fitted to the end of the outer cylinder.

  In the hydraulic shock absorber configured as described above, when the piston rod 5 is fully extended, the pressurized hydraulic oil in the rod chamber R pushes the expansion side valve 18 through the expansion side port 17 and opens the piston chamber P. At the same time, it generates a damping force on the extension side.

  Simultaneously with the generation of the extension side damping force, the rebound member 8 interposed between the stopper member 7 and the rod guide 6 comes into contact with the rod guide 6 to bring the coil spring 22 into the most compressed state. Reduces the impact when fully extended.

  At this time, as shown in FIG. 3, the coil spring 22 is engaged with the concave portions 25 and the convex portions 26 provided on the upper surface and the lower surface of the respective coil portions 35, so that the respective coil portions 35 are connected to each other. The sliding of the coil portions 35 in the radial direction is prevented.

  Therefore, as in the prior art, a part of the coil part 35 jumps out toward the outer peripheral side of the piston rod 45 or the inner peripheral side of the inner cylinder 3, and the outer or inner end of the protruding coil part 35 is the inner peripheral side of the inner cylinder 3. In addition, it is possible to prevent the possibility of generating unpleasant noises or impacts by contacting the outer periphery of the piston rod 5.

  In addition, since the cross-sectional shapes of the concave portion 25 and the convex portion 26 are V-groove shape and mountain shape, even if the axial centers of the coil portions 35 are slightly deviated from each other, they can be reliably engaged by the alignment function.

  Further, by forming the concave portion 25 and the convex portion 26 with planes having the same shape, the coil portions 35 can always be brought into surface contact with each other, so that the contact resistance can be always increased, and the above-described engagement state is ensured. Can be maintained.

  Further, in the present embodiment, the coil member 35 having the concave portion 25 and the convex portion 26 formed on the upper surface and the lower surface is formed by coiling the wire 34 having a substantially square cross section as described above. The coil spring 22 itself can be manufactured easily and inexpensively compared to the formation of the protrusions 25 and the convex portions 26.

  In addition, the upper and lower holders 23 and 24 are fitted to both ends of the coil spring 22, and the piston rod 5 is inserted through the insertion holes 23a and 23b provided in the holders 23 and 24. The piston rod 5 can be always stably disposed at a predetermined position on the outer periphery of the piston rod 5.

  Therefore, the movement of the coil spring 22 itself in the outer circumference or inner circumference direction can be restricted, and the movement of the coil spring 22 itself causes the coil spring 22 to come into contact with the outer circumference of the piston rod 5 or the inner circumference of the inner cylinder 3 to generate sound or the like. It can prevent more reliably.

  Further, since the protrusions 27 having a mountain-shaped cross section are formed on the upper surface of the upper holder 23, the entire upper holder 23 does not contact the rod guide 6 suddenly when fully extended, but the rod guides are elastically deformed after the protrusions 27 are elastically deformed. 6 can be contacted.

  Therefore, even if the upper holder 23 abruptly abuts against the rod guide 6, it is possible to prevent abnormal noise or the like from being generated by the buffering action of the protrusion 27.

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

  1) The cross-sectional shape of the concave portion 25 and the convex portion 26 provided on the upper surface and the lower surface of the coil spring 22 is a mountain shape in the present embodiment, but is not limited to this. For example, FIG. A coil spring 36 having a concave portion 25a and a convex portion 26a having a semicircular cross section as shown in FIG. 5, a coil spring 37 having a concave portion 25b having a rectangular groove shape and a convex portion 26b having a rectangular shape as shown in FIG. It is good also as the coil spring 38 which has the recessed part 25c and convex part 26c of trapezoidal cross section as shown in FIG.

  In addition to this shape, any shape can be adopted as long as the upper and lower surfaces are engaged.

  2) In the present embodiment, the concave portion 25 is provided on the upper surface of the coil portion 35 and the convex portion 26 is provided on the lower surface to be engaged. However, the present invention is not limited thereto, and the concave portion 25 is provided on the lower surface and the convex portion 26 is provided on the upper surface. May be provided.

  3) In the present embodiment, the concave portion 25 and the convex portion 26 have the same shape. However, the present invention is not limited to this, and the cross-sectional shapes of the concave portion 25 and the convex portion 26 are different as long as they can be engaged. May be.

  4) Both the upper and lower holders 23 and 24 are not necessarily required, and either one or both may be omitted.

  5) In the present embodiment, the multi-cylinder strut type hydraulic shock absorber 1 is embodied. However, it may be embodied not only in the strut type but also in a single cylinder type hydraulic shock absorber.

It is a principal part fracture front view of the hydraulic shock absorber which shows one embodiment of the present invention. It is a perspective view which shows the wire which forms a coil spring. It is sectional drawing which shows the most compressed state of a coil spring. It is sectional drawing which shows another example of a coil spring. It is sectional drawing which similarly shows another example of a coil spring. It is sectional drawing which similarly shows another example of a coil spring. It is sectional drawing which shows the most compressed state of the conventional coil spring. It is sectional drawing which shows the state which the coil parts of the coil spring of FIG. 7 slipped.

Explanation of symbols

3 Inner cylinder (cylinder)
4 Piston 5 Piston rod 6 Rod guide (extending member)
7 Stopper member 8 Rebound member 22 Coil spring 23 Upper holder 23a Insertion hole (for upper holder)
24 Lower holder 24a Insertion hole (for lower holder)
25 25a, 25b, 25c Recess (engagement part)
26 26a, 26b, 26c Convex part (engagement part)
34 Wire 35 Coil 36 Coil Spring 37 Coil Spring 38 Coil Spring

Claims (4)

It is interposed between the cylinder, the piston rod that is movably inserted into the cylinder via the piston, and the expansion limit restricting member provided on the cylinder and the stopper member provided on the piston rod to alleviate the impact when fully extended. A rebound member, and the rebound member includes a compressible coil spring so that adjacent coil portions in the axial direction come into contact with each other when fully extended. The hydraulic shock absorber characterized by the above-mentioned. The engaging part for engaging parts is provided. The hydraulic shock absorber according to claim 1, wherein the rebound member is constituted by a coil spring and upper and lower holders fitted to both ends thereof, and an insertion hole through which a piston rod is inserted is formed in the upper and lower holders. A convex portion is provided on the contact surface of one of the adjacent coil portions when the coil portions are in contact with each other, and a concave portion that engages with this convex portion is provided on the contact surface of the other coil portion to form the engaging portion. The hydraulic shock absorber according to claim 1 or 2. 4. The hydraulic shock absorber according to claim 1, 2 or 3, wherein the coil spring is formed by coiling a wire having a substantially quadrangular cross section having a concave portion on the upper surface and a convex portion engaging with the concave portion on the lower surface.

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