JP2005016632A - Hydraulic buffer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the structure of a buffer equipped with a rebound member prevented from generating uncomfortable noises and shock during extension to its full length of a piston rod. <P>SOLUTION: The hydraulic buffer is provided with a cylinder 3, a piston rod 5 movably inserted in the cylinder 3 through a piston 4, and the rebound member 8 located between an extension-to-full-length regulating member 6 mounted on the cylinder 3 and a stopper member 7 situated at a piston rod and relaxing shock during extension to full length. In the buffer, the rebound member 8 is equipped with a coil spring 22 provided on each coil wire element 25 with a plane structure 26 so that the adjoining coil wire elements 25 are brought into surface contact with each other during the maximum compression. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic shock absorber provided with a rebound member for alleviating an impact when the piston rod is fully extended.
[0002]
[Prior art]
Conventionally, as a hydraulic shock absorber 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.
[0003]
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 up of a coil spring fitted with a guide is interposed.
[0004]
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.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-238980 (FIG. 1)
[0006]
[Problems to be solved by the invention]
However, the following problems can be considered in the hydraulic shock absorber configured as described above.
[0007]
That is, when the piston rod is fully extended, the coil spring is also in the most compressed state, so that the adjacent coil wire bodies constituting the coil spring are in close contact with each other.
[0008]
At this time, as shown in FIG. 4, in the coil spring 41 having the conventional structure, the wire constituting the coil spring 41 is formed in a circular cross section. They are in point contact with each other.
[0009]
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.
[0010]
Therefore, for example, when the adjacent coil wire bodies 42 come into contact with each other at a high piston speed, the coil wire bodies 42 slip due to a small contact resistance between them, and some coil wires are shown in FIG. It is assumed that the body part 43 jumps out toward the inner peripheral side or the outer peripheral side of the piston rod 45.
[0011]
In this case, it is conceivable that the outer or inner end portion of the protruding coil wire body portion contacts the inner periphery of the cylinder or the outer periphery of the piston rod 45 to generate unpleasant noise or impact.
[0012]
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.
[0013]
[Means for Solving the Problems]
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. In the hydraulic shock absorber provided with a rebound member that relieves an impact when fully extended, the rebound member is flat on each coil wire portion so that adjacent coil wire portions are in surface contact with each other at the time of the most compression. A coil spring having a portion is provided.
[0014]
In this case, it is preferable that the coil spring is formed by coiling a wire having a square cross section, and this one side is a flat portion.
[0015]
Further, the rebound member may be constituted by a coil spring and upper and lower holders fitted to both ends thereof, and an insertion hole through which the piston rod is inserted may be formed in the upper and lower holders.
[0016]
At this time, the upper holder may be provided with a sound deadening member made of an elastic body at a contact portion with the extension restricting member.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a strut type hydraulic shock absorber used in a suspension device for an automobile will be described with reference to the drawings.
[0018]
As shown in FIG. 1, the hydraulic shock absorber 1 includes an inner cylinder 3 that is a cylinder inserted into the outer cylinder 2, a piston rod 5 that is inserted into the inner cylinder 3 via a piston 4, and can be moved in and out. 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; a stopper member 7 and a rod guide 6; And a rebound member 8 interposed therebetween.
[0019]
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.
[0020]
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.
[0021]
The piston 4 is inserted into the base 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.
[0022]
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.
[0023]
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.
[0024]
The coil spring 22 is formed by coiling a wire having a square cross section, and one side located on the upper surface and the lower surface of each coil wire body portion 25 so that adjacent coil wire body portions 25 are in surface contact with each other in the most compressed state. Is the plane portion 26.
[0025]
In addition, the coil wire body part in this invention shows all the circumference parts which can be obtained by coiling a wire, and shall use it as a concept including all the circumference parts which comprise what is called an end winding part and a pitch part.
[0026]
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.
[0027]
The upper holder 23 is suspended from the holder body 28 having a cylindrical shape, a fitting part 29 having an outer diameter smaller than that of the holder body 28, and a tapered part 30 extending from the fitting part 29. The upper end portion of the coil spring 22 is guided by the taper portion 30 and is fitted to the fitting portion 29.
[0028]
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.
[0029]
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.
[0030]
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.
[0031]
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.
[0032]
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.
[0033]
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.
[0034]
At this time, since the flat portions 26 are formed on the upper and lower surfaces of each coil wire body portion 25 so that the coil wire body portions 25 are in surface contact with each other, as shown in FIG. 2, adjacent coil wire body portions. 25 is in a surface contact state, and the contact resistance is always in a large state.
[0035]
For this reason, even when the piston speed reached when fully extended and the adjacent coil wire bodies 25 collide with each other to reach the most compressed state, the coil wire body parts 25 as shown in the conventional example are It is possible to remarkably reduce the possibility of sliding and part of the coil wire body portion 25 jumping out toward the inner peripheral side or the outer peripheral side of the piston rod 5.
[0036]
Accordingly, it is possible to reliably prevent the end of the protruding coil wire body portion 25 from coming into contact with the outer periphery of the piston rod 5 or the inner periphery of the inner cylinder 3 to generate unpleasant noise or impact.
[0037]
Further, in the present embodiment, by coiling a wire having a square cross section, one side of the wire is used as a flat portion 26 in which the adjacent coil wire body portions 25 are in surface contact with each other. It can be manufactured at low cost.
[0038]
Further, the upper and lower holders 23, 24 are fitted to both ends of the coil spring 22, and the piston rod 5 is inserted through the insertion holes 23a, 23b provided in the holders 23, 24. The piston rod 5 can be always stably disposed at a predetermined position on the outer periphery of the piston rod 5.
[0039]
Accordingly, 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.
[0040]
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.
[0041]
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.
[0042]
In addition, this invention is not limited to said embodiment, For example, it can also be changed and actualized as follows.
[0043]
1) Although the cross-sectional shape of the coil spring 22 is a square in the present embodiment, for example, as shown in FIG. In this way, there is an effect that even if the coil spring 22 is in sliding contact with the outer periphery of the piston rod 5 or the inner periphery of the inner cylinder 3, it is difficult to generate sound or the like.
[0044]
In addition to this shape, of course, it may be a rectangle such as a rectangle or a trapezoid, or a polygon, and any other shape may be used as long as the upper surface and the lower surface are flat portions.
[0045]
2) Both the upper and lower holders 23 and 24 are not necessarily required, and either one or both may be omitted.
[0046]
3) In the embodiment, the multi-cylinder strut type hydraulic shock absorber 1 is embodied. However, the embodiment is not limited to the strut type, and may be embodied in a single cylinder type hydraulic shock absorber.
[0047]
【The invention's effect】
The present invention has the following effects.
[0048]
1) According to the invention of claim 1, since the coil spring that is in the most compressed state when the piston rod is fully extended, the flat portions are formed in the coil wire bodies so that the coil wire bodies are in surface contact with each other. The contact resistance between the coil wire bodies can be increased.
[0049]
Therefore, for example, even when the piston speed that reaches when fully extended and the adjacent coil wire bodies collide and reach the most compressed state, the coil wire bodies as shown in the conventional example slip, The possibility that some coil wire parts jump out toward the inner or outer periphery of the piston rod and make contact with the outer periphery of the piston rod or the inner periphery of the cylinder to cause unpleasant noise or impact, etc. it can.
[0050]
2) According to the invention of claim 2, by coiling a wire having a square cross section, one side of the wire is made into a flat surface where adjacent coil wire bodies are in surface contact with each other. It can be manufactured at low cost.
[0051]
3) According to the invention of claim 3, the upper and lower holders are fitted to both ends of the coil spring, and the piston rod is inserted through the insertion holes provided in both holders. It can always be stably arranged at a predetermined position on the outer periphery.
[0052]
Therefore, the movement of the coil spring itself in the outer circumference or inner circumference direction can be restricted, and the movement of the coil spring itself can more reliably prevent the coil spring from coming into contact with the outer circumference of the piston rod or the inner circumference of the cylinder and generating sound or the like. Can be prevented.
[0053]
4) According to the invention of claim 4, since the silencer member made of an elastic body is provided on the upper surface of the upper holder, the entire upper holder does not stretch and abruptly contact the restricting member when fully extended. After being deformed, it stretches and contacts the restricting member. Therefore, for example, even if the upper holder is suddenly brought into contact with the expansion restricting member, it is possible to reliably prevent the generation of abnormal noise or the like due to the buffering action of the sound deadening member.
[Brief description of the drawings]
FIG. 1 is a front view, broken away, of a main part of a hydraulic shock absorber according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a most compressed state of a coil spring.
FIG. 3 is a cross-sectional view showing another example of a coil spring.
FIG. 4 is a cross-sectional view showing a most compressed state of a conventional coil spring.
5 is a cross-sectional view showing a state in which coil wire bodies of the coil spring of FIG. 4 have slipped.
[Explanation of symbols]
3 Inner cylinder (cylinder)
4 Piston 5 Piston rod 6 Rod guide (extension control member)
7 Stopper member 8 Rebound member 22 Coil spring 22 Upper holder 23a Insertion hole (for upper holder)
24 Lower holder 24a Insertion hole (for lower holder)
25 Coil wire body part 26 Plane part 27 Projection part (silencer member)

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, so that the impact at the time of extension is alleviated. In the hydraulic shock absorber provided with the rebound member, the rebound member includes a coil spring having a flat portion in each coil wire body portion so that adjacent coil wire body portions are in surface contact with each other at the time of the most compression. Hydraulic shock absorber. 2. The hydraulic shock absorber according to claim 1, wherein a coil spring is formed by coiling a wire having a square cross section, and one side of the coil spring is a flat portion. The hydraulic shock absorber according to claim 1 or 2, wherein a 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. 4. The hydraulic shock absorber according to claim 3, wherein the upper holder is provided with a sound deadening member made of an elastic body at a contact portion with the extension restricting member.

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