JP2000257606A - Cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a dust cover, maintain performance and reduce the cost by providing a cylindrical dust cover with one end fitted to a cylinder body, the other end being reduced in diameter to be slidably in contact with a rod. SOLUTION: A dust cover 13 is shaped like a substantially conical bellows and formed of elastic resin. A minimum diameter part and an enlarged diameter part are formed on the other end of the dust cover 13. The minimum diameter part has the same diameter as the outside diameter of a piston rod 3, and it is in contact with the piston rod almost without interference. The end of the dust cover 13 is provided with an enlarged diameter part further outside the minimum diameter part, whereby the end of the dust cover 13 is prevented from being caught by the piston rod 3 to be involved in the inside. Thus, the normal amplitude range is covered with the dust cover 13, so that the length of the dust cover 13 can be decreased without lowering of durability and the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylinder device such as a hydraulic shock absorber.

[0002]

2. Description of the Related Art In a conventional cylinder device provided with a dust cover, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 56-93545, one end of a dust cover is fixed to an outer peripheral portion of a cylinder body and a piston rod is projected. A guide member for attaching a dust cover is provided at one end, and the dust cover is attached to the guide member by fixing the other end of the dust cover. Thus, the piston rod is shielded from the outside.

Further, another conventional structure is disclosed in
As shown in JP-A-4092, the dust cover is made larger than the outer diameter of the cylinder body, and the other end of the dust cover is attached to the guide member on the protruding end side of the piston rod in the same manner as in the above-mentioned conventional technology. Some cylinders extend to the outer peripheral portion of the cylinder body and are free with a gap from the cylinder body. In such a structure, dust is prevented from adhering to the piston rod by mounting the piston rod with the protruding end side facing upward.

[0004]

In the above two prior arts, all the rods are covered with a dust cover, and the dust cover needs to have a length corresponding to the maximum length and is costly. There was a point.

Further, when the cylinder device is used sideways, in the case where both ends are fixed, the intermediate portion of the dust cover is lowered by its own weight and is deformed, which is apt to be deteriorated. In the case of leakage, the oil liquid accumulates in the intermediate portion and is more deformed, which causes the dust cover to come into contact with the rod, thereby increasing the friction.

Further, in the case where one end of the dust cover is extended to the outer peripheral portion of the cylinder body and is not fixed, but is free, a large gap is formed between the cylinder body and one end of the dust cover. There is a problem that dust invades and does not serve as a dust cover.

[0007]

Means for Solving the Problems To solve the above problems, the present invention has the following features.

According to the present invention, there is provided a cylinder device comprising a cylinder body in which a fluid is sealed, and a rod having one end projecting from the cylinder body so as to extend and contract from the cylinder body. It is characterized by comprising a dust cover which is reduced in diameter and slidably contacts the rod.

Therefore, according to the present invention, the dust cover can be shortened, the performance can be reduced, and the cost can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic shock absorber 1 according to one embodiment of the present invention will be described with reference to FIG.

A piston rod 3 protrudes from one end of the outer cylinder 2 so as to be able to expand and contract.

One end of the piston rod 3 has an inner cylinder 4
The piston 5 is provided with a damping force generating mechanism 6 including a disk valve and an orifice.

At the other end of the outer cylinder 2 is provided a bottom valve 7 composed of a disk valve and an orifice, and a reservoir 8 formed between the outer cylinder 2 and the inner cylinder 4 via the bottom valve 7. And the inside of the inner cylinder 4 are communicated.

A large-diameter portion 2A is provided at an intermediate portion of the outer cylinder 2. Inside the large-diameter portion 2A, a bag 9 made of polyester and filled with a gas and having a C-shaped cross section is provided. Is provided. An enlarged view of the bag 9 is shown in FIG. The bag 9 compensates for erosion of the piston rod 3, temperature compensation, and oil leakage.

The outer diameter of the bag body 9 before being inserted into the reservoir chamber 8 is slightly larger than the inner diameter of the large diameter portion 2A of the outer cylinder 2.
The inner diameter is larger than the outer diameter of the inner cylinder 4.

A groove 9A extending in the axial direction is formed on a side surface of the bag body 9. When assembling this hydraulic shock absorber, the groove 9A is inserted into the outer cylinder 2 by reducing the diameter of the bag body 9 and mounting it on the large-diameter portion 2A. When this oil is added, if the outer diameter surface is flat as shown in the conventional Japanese Patent Application Laid-Open No. 6-147247, for example, between the outer diameter surface and the inner surface of the outer cylinder 1 or the bottom side of the bag body There was a fear that air could accumulate in the hydraulic shock absorber and gas could enter inside the hydraulic shock absorber after assembly.

However, by providing the groove 9A,
At the time of assembling, air between the outer diameter surface and the inner surface of the outer cylinder 2 and the bottom side of the bag body 9 escape through the groove 9A, so that there is no problem that gas enters the inside of the hydraulic shock absorber. .

The groove 9A may be a groove communicating with the vertical direction at the time of assembling, and may be spiral.

The protruding portion 9B of the bag 9 is a port for filling gas into the bag 9, and is a cylindrical port when the bag is formed. As a result, the mouth is closed, so that the shape is as shown in the figure.

A cap 10 is welded to one end of the outer cylinder 2, and a rod guide 11 and a seal mechanism 12 are provided therein to close one end of the outer cylinder 2.

One end of a dust cover 13 is fixed to the cap 10 by a fastening band 14 made of resin. FIG. 3 is an enlarged cross-sectional view of the dust cover 13, and FIG.
FIG. 4 shows an external view of the attached state.

The dust cover 13 has a substantially conical bellows shape and is made of an elastic resin. The other end of the dust cover 13 has a minimum diameter portion 13A and an enlarged diameter portion 13B.
Are formed. The minimum diameter portion 13A has the same diameter as the outer diameter of the piston rod 3 and is in contact with the piston rod 3 with almost no interference. Therefore, the friction of this portion is considerably smaller than the friction of the seal mechanism 12, and is negligible as a damping force characteristic of the hydraulic shock absorber 1.

The length of the dust cover 13 in the axial direction (left-right direction in the figure) is the length L between the minimum diameter portion 13A and the end of the seal mechanism 12, and the hydraulic shock absorber 1 is It is desirable that the length be slightly larger than a commonly used amplitude.

This is because a hydraulic shock absorber generally uses a part of the middle portion of a strokeable range (maximum length to minimum length) and uses it so that the maximum length and the minimum length rarely occur. Will be Therefore, if the dust cover 13 covers the commonly used portion of the piston rod 3, the effect can be sufficiently obtained.

A mounting ring 15 is provided at the protruding end of the piston rod 3, and a mounting ring 17 is provided at a bottom cap 16 that closes the outer cylinder 2.

In this embodiment, the outer cylinder 2, the cap 12, and the bottom cap 16 form the cylinder body of the present invention.

An example of use and operation of the above embodiment will be described.

First, as an example of use of the hydraulic shock absorber 1,
FIG. 5 shows a case where the device is used as a vibration damping device for a general wooden house.

Pillars 21 and 22 are erected on the foundation 20.
A beam 23 is provided at the upper end of the column. The lower panel 24 transmitting the horizontal movement of the foundation 20 to the foundation 20, and the upper panel 2 transmitting the horizontal movement of the beam 23 to the beam 23.
5 is fixed.

Between the lower panel 24 and the upper panel 25, the hydraulic shock absorber 1 is provided with mounting plates 26, 2
7 attached.

When an earthquake occurs, the basics 2
0 and the beam 23 move relative to each other in the horizontal direction, and the lower panel 24
And the upper panel 25 also move in the horizontal direction by substantially the same amount.
At this time, the outer cylinder 2 side is attached to the lower panel 24, and the piston rod 3 side is attached to the upper panel 25, so that the piston rod expands and contracts, and the damping force generation mechanisms 6, 7 are attached.
As a result, a damping force is generated. Damping by this damping force,
Suppresses the building from resonating and prevents the building from collapsing.

At the time of the expansion and contraction, the dust cover 13
Since the length L is slightly larger than the amplitude generated at the time of the seismic intensity 4 earthquake, the stroke is covered by the portion covered with the dust cover 13 until the earthquake of the seismic intensity 4 or so. Therefore, there is no fear that the dust damages the seal mechanism 12.

For a large earthquake having a seismic intensity of 5 or more, after the large dust adhered to the rod is removed by the minimum diameter portion 13A of the dust cover 13, the exposed portion of the piston rod 3 is attached to the seal mechanism 12. Therefore, the risk of damaging the seal mechanism 12 with dust can be reduced. The frequency of such a large amplitude is as low as about once every several years or several decades, and the durability of the seal mechanism 12 is sufficient even if the piston rod 3 to which dust adheres enters at such a frequency. There is no problem because it has the durability to withstand.

The end of the dust cover 13 is provided with the enlarged diameter portion 13B further outside the minimum diameter portion 13A, so that the end of the dust cover 13 is caught by the piston rod 3 and is caught in the inside. To prevent.

As described above, in the present embodiment, the normal amplitude range is covered with the dust cover 13, so that the length of the dust cover 13 can be shortened and the cost can be reduced without reducing the durability. .

Also, because of the conical shape, even when oil leaks from the inside of the hydraulic shock absorber, the oil collects on the cylinder body side and collects near the mounting portion side of the dust cover 13, so that the oil hardly leaks. Further, the dust cover is hardly deformed by the weight of the oil, and there is no possibility that the friction increases.

Although the above embodiment has been described with reference to a hydraulic shock absorber, a cylinder device such as a gas spring may be used.

In the above embodiment, the cap 10
Shows that the dust cover 13 is attached to the
However, the present invention is not limited to this, and may be attached to the outer cylinder 2, or a welding bracket or the like may be welded to the cap 10 and attached thereto.

In the above embodiment, the minimum diameter portion 13A of the dust cover 13 slides directly on the piston rod 3. However, a resin-coated sliding member may be provided on the inner circumference of the minimum diameter portion 13A. Good.

Furthermore, in the above-described embodiment, an example has been shown in which the dust cover 13 is fixed with a resin fastening band. However, the present invention is not limited to this, and a metal band may be used.
Instead of providing a fastening member, the dust cover 13 may be fixed by elasticity.

[0041]

As described above, according to the present invention, a cylindrical dust cover having one end attached to the cylinder body and the other end having a reduced diameter and slidably in contact with the rod is provided. Can be covered with the dust cover, and the length of the dust cover can be shortened and the cost can be reduced without reducing the durability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic shock absorber as one embodiment of a cylinder device according to the present invention.

FIG. 2 is a view showing a bag of the hydraulic shock absorber shown in FIG. 1;
Is a side view, and (b) is a front view.

FIG. 3 is an enlarged view of the dust cover 13 of FIG.

FIG. 4 is an external view of the vicinity of a dust cover 13 in FIG.

FIG. 5 is a diagram in which the cylinder device of the present invention is used as a vibration damping device.

[Explanation of symbols]

 2 outer cylinder (cylinder body) 3 piston rod (rod) 10 cap (cylinder body) 13A minimum diameter part 13 dust cover 16 bottom cap (cylinder body)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yukio Matsumoto 1116 Koizono, Ayase-shi, Kanagawa F-term in Sagami Plant of Tokiko Co., Ltd. 3H081 AA03 BB02 CC23 DD39 EE29 3J069 AA50 CC29 CC30 CC31 DD44

Claims (1)

[Claims] 1. A cylinder device comprising a cylinder body in which a fluid is sealed, and a rod having one end protruding from the cylinder body so as to be extendable and contractable, wherein one end of the cylinder is attached to the cylinder body, and the other end is reduced in diameter. And a dust cover slidably in contact with said rod.