JPH0516426Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a hydraulic shock absorber, and in particular to a hydraulic shock absorber that is optimal for use in small hydraulic shock absorbers called mini-buffers or micro-buffers. Regarding improvements.

[Conventional technology]

In a small hydraulic shock absorber, generally called a mini-buffer or micro-buffer, it is necessary to increase the shock-absorbing efficiency according to its stroke and to achieve a smooth stop. As a proposal for this purpose, for example, there is a general hydraulic shock absorber as shown in FIG.

That is, the hydraulic shock absorber shown in FIG. 3A is of a so-called multi-hole type, and has a double cylinder structure in which an outer tube 3 is disposed outside a cylinder 2 on which a piston portion 1 slides. , the cylinder 2 on which the piston part 1 slides has a number of holes 2a whose positions are shifted so as to correspond to the stroke of the piston part 1,
2b...2n are formed. As the piston portion 1 enters into the cylinder, the large number of holes 2a, 2b, . . . are sequentially closed to generate a high damping force.

The hydraulic shock absorber shown in Fig. 3B is a so-called orifice rod type shock absorber with a single cylinder structure. A needle portion 1a with a tapered outer circumferential surface is protruded from the tip of a piston portion 1 that slides in a cylinder 2, and a partition wall 4 is formed in the cylinder 2 so as to partition an oil chamber in the cylinder. The tip of the needle portion 1a is disposed so as to appear and disappear in a central through hole 4a of the partition wall 4. As the piston portion 1 advances into the cylinder 2, the amount of oil passing through the annular orifice formed in the through hole 4a is restricted, so that a high damping force is generated.

[Problem that the invention attempts to solve]

However, the so-called porous type shown in Fig. 3A has a double cylinder structure, which has the disadvantage of complicating the overall structure, making it difficult to use in small hydraulic shock absorbers. It is inconvenient for In addition, the so-called orifice rod type shown in Figure 3B has the disadvantage of requiring high precision control in machining the tapered surface of the needle portion 1a, making it difficult to use in small hydraulic shock absorbers. There is a disadvantage that it becomes easier.

Therefore, in the case of a small hydraulic shock absorber, it is necessary to install a fixed orifice 1b with a constant area in the piston part 1 that slides inside the cylinder 2, as shown in FIG. Currently, a so-called fixed orifice type is used.

Therefore, in view of the above-mentioned circumstances, the present invention, in particular,
The purpose of this invention is to provide a new hydraulic shock absorber that is optimal for use in small hydraulic shock absorbers called mini buffers or micro buffers.

[Means for solving problems]

In order to solve the above-mentioned problems, the structure of the hydraulic shock absorber according to the present invention is such that an oil passage is provided in the piston rod to enable communication between the rod side chamber and the piston side chamber defined in the cylinder by the piston part. A rod guide is provided in which a passage is opened and communicated with the oil passage on the outer periphery of the shaft of the piston rod, and a plurality of through holes of different diameters are bored on the outer periphery of the shaft of the piston rod to enable communication with the passage. Sliding contact,
Further, an accumulator made of a closed cell sponge is fixed to the outer periphery of the rod guide to allow oil to flow from the piston side chamber into the rod side chamber through the oil passage, passage and through hole.

〔Example〕

Hereinafter, the present invention will be explained based on a preferred embodiment shown in the drawings.

As shown in FIG. 1, the hydraulic shock absorber according to the present invention has a piston portion 12 at the tip of a piston rod 11 inserted into a cylinder 10, and the inside of the cylinder 10 is controlled by the piston portion 12. The piston rod 11 is divided into a rod side chamber A and a piston side chamber B, and an oil passage 13 is provided in the piston rod 11 to allow communication between the rod side chamber A and the piston side chamber B.

The outer peripheral surface of the cylinder 10 has a threaded portion 10a.
is formed, and a nut 10b that enables connection to other parts of the cylinder 10, such as a fixed part, is screwed into the threaded part 10a. Inside the end of the cylinder 10 on the insertion side of the piston rod 11 is a packing 1 as an oil seal.
0c is interposed, and a fixing tool 10e is screwed through a washer 10d to fix the packing 10c in a predetermined position.

The piston rod 11 is formed so as to closely fit and pass through the center of the gasket 10c serving as the oil seal.
A piston portion 12 is connected to the tip, which is the inner end. A resin cap 11a is fitted to the base end of the piston rod 11, which is the outer end of the cylinder 10, to allow contact with other parts, such as a movable part.

The piston portion 12 has a piston ring 12a on its outer periphery that slides into contact with the inner peripheral surface of the cylinder 10, and the piston ring 12a divides the inside of the cylinder 10 into a rod side chamber A and a piston side chamber B. It is something that exists.

Oil passage 1 bored in the piston rod 11
3 is a vertical hole 13a bored with an appropriate length from the center of the tip of the piston rod 11 to the center of the base end.
and a horizontal hole 13b (see FIG. 2) that is bored in the diametrical direction of the piston rod 12 at the proximal end of the vertical hole 13a and communicates with it.
The end of the rod side chamber A side of the piston rod 1
It opens into three passages 11b (see FIG. 2) consisting of, for example, wide annular grooves formed on the outer peripheral surface of the tube.
The vertical hole 13a has a large diameter from the middle to the end on the piston side chamber B side, and opens into the piston side chamber A with the large diameter.

A rod guide 14 is in sliding contact with the outer peripheral surface of the piston rod 11 on the rod side chamber A side.
The rod guide 14 is connected to the piston rod 1.
The rod guide 14 is formed so as to close the passage 11b from the outer circumferential side within the range of one effective stroke, and in this embodiment, the rod guide 14 is provided with a so-called bearing function. is formed. And the above rod guide 1
The intermediate outer circumferential portion of No. 4 is formed in a concave shape, and the accumulator 15 is housed in the concave portion. In addition, a plurality of through holes 14a, 14 are provided in the thick wall portion of the rod guide 14 that accommodates the accumulator 15 and faces the outer periphery of the piston rod 11.
b, 14c are bored so that the plurality of through holes 14a, 14b, 14c all face the passage 11b when the piston rod 11 is raised to the highest level, that is, when the hydraulic shock absorber is fully extended. is formed.

Note that the plurality of through holes 14a, 14b, 14c
is positioned and formed such that when the piston rod 11 is at its lowest point, that is, when the hydraulic shock absorber is at its maximum compression, the opposite side to the passage 11b is completely cut off, and in this embodiment, the piston rod 11
They are formed with different diameters so that higher damping force is generated as the stroke of It is formed like this.

The accumulator 15 housed in the recessed portion of the rod guide 14 is formed to allow oil to flow into the rod side chamber A as the piston rod 11 strokes. In this embodiment, it is made of closed cell sponge. The accumulator 15 made of the closed cell sponge is
A part of its inner circumferential surface is fixed to the outer circumferential surface of the recessed portion of the rod guide 14 with a suitable adhesive.

As shown in FIG. 2, the accumulator 15 has a groove 15a that allows oil to flow in, and the oil from the piston side chamber B flows through the oil passage 13 and the through hole 14a of the rod guide 14. It is formed so that it can easily flow into the rod side chamber A via 14c.

The operation of the hydraulic shock absorber according to the present invention formed as described above will be briefly explained.

When the cylinder 10 is fixed to the fixed part,
Resin cap 11a at the base end of piston rod 11
The movable part comes into contact with. Piston part 1
2 moves to the right in Fig. 1 and enters the piston side chamber B.
High pressure inside. The high pressure oil is supplied to the oil passage 13 inside the piston rod 11, the passage 11b on the outer circumference of the shaft portion of the piston rod 11, and the through hole 1 of the rod guide 14.
4a, 14b, and 14c into the rod side chamber A. At this time, the through holes 14a, 14b, 1
A desired compression damping force is generated by the fluid resistance when passing through 4c. Further, as the piston portion 12 enters the cylinder 10, the oil equivalent to the rod volume contracts the closed cell sponge, which is the accumulator 15 fixed to the outer periphery of the rod guide 14, and is transferred to the rod side chamber. It will also flow into A.

On the other hand, the damping force on the compression side becomes higher as the stroke of the piston portion 12 becomes larger. That is,
As the piston part 12 moves, the piston rod 11
moves, and the passage 11b and each through hole 14 on the outer peripheral surface thereof move.
This is because the opposition to a, 14b, and 14c is sequentially resolved from above. When the piston part 12 is so-called bottomed, communication between the rod side chamber A and the piston side chamber B via the piston rod internal oil passage 13 is cut off, and only oil leakage from the piston ring 12a in the piston part 12 is allowed. It will be done.

Although the hydraulic shock absorber according to the present invention has been proposed as being ideal for small-sized devices called mini-buffers or micro-buffers, it is of course not impeded to use it in hydraulic shock absorbers of general size. be.

[Effect of idea]

As described above, according to the present invention, since it has a so-called single cylinder structure, there is no fear of overall complication.
Also, since it does not have a needle part that requires tapered surface processing, high precision control is not required.
It has the advantage of being most suitable for use in small hydraulic shock absorbers called mini-buffers or micro-buffers.

In addition, when using a closed-cell sponge as an accumulator, compared to using bellows, etc., there is no inconvenience such as fatigue of the rubber membrane or air leakage due to poor installation, and it is expected that the durability of the hydraulic shock absorber will be improved. At the same time, there is also the advantage that the workability in manufacturing the hydraulic shock absorber is improved.

According to this invention, a plurality of through holes having different diameters, which essentially constitute the damping force adjustment section, are bored in the rod guide which is in sliding contact with the outer periphery of the shaft portion of the piston rod. Compared to the case where the through hole is drilled in the piston rod, there is an advantage that the strength of the piston rod is not reduced, and the opening operation is also easier.

Furthermore, a passage consisting of an annular groove or the like that enables communication between the oil passage on the piston rod side and the through hole on the rod guide side is formed on the outer circumference of the piston rod, compared to a case where the passage is formed on the inner circumference of the rod guide. This has the advantage of making the forming work easier.

[Brief explanation of the drawing]

Fig. 1 is a front cross-sectional view showing a hydraulic shock absorber according to an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view indicated by the middle line - in Fig. 1, and Fig. 3 A to Fig. 3 C are conventional hydraulic shock absorbers. It is a sectional view showing a shock absorber. 10...Cylinder, 11...Piston rod,
11b... passage, 12... piston part, 13...
Oil passage, 14... Rod guide, 14a, 14b,
14c...Through hole, 15...Accumulator, A...
...Rod side chamber, B...Piston side chamber.

Claims (1)

[Claims for Utility Model Registration] (1) An oil passage is opened in the piston rod to enable communication between the rod side chamber defined by the piston part in the cylinder and the piston side chamber, and A rod guide that forms a passage communicating with the oil passage and has a plurality of through holes with different diameters formed on the outer periphery of the shaft of the piston rod to enable communication with the passage is slidably connected to the outer periphery of the rod guide. A hydraulic shock absorber (2) comprising an accumulator made of a closed-cell sponge that allows oil to flow from the piston side chamber into the rod side chamber through the oil passages, passages, and through holes (2). The hydraulic shock absorber according to claim 1, wherein the hydraulic shock absorber is biased in the extension direction by being brought into contact with the other end of a spring whose one end is fixed to the inner bottom of the cylinder.