JP2001304321A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide accumulator structure relatively simple in structure, without requiring troublesome degassing work or the like and applicable to a wide range of hydraulic shock absorbers from a small-sized one to a large-sized one. SOLUTION: In this hydraulic shock absorber, a piston rod 2 is inserted in a cylinder 1, and an accumulator 11, allowing the in-and-out of operating oil equivalent to the introducing volume of the piston rod 2 into the cylinder 1, is communicated with an oil chamber R1 formed in the cylinder 1. The accumulator 11 is provided with an elastic body chamber 12, in which an elastic body 9 is housed, and a gas chamber 13 partitioned by the elastic body 9. The gas chamber 13 is communicated with the oil chamber R1 via the elastic body chamber 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an accumulator provided in a hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, there is the following structure of an accumulator provided in a hydraulic shock absorber. A structure in which a predetermined amount of gas is sealed together with hydraulic oil in the cylinder, and there is no free piston that partitions the gas chamber. A structure in which a predetermined amount of gas is enclosed in a cylinder together with hydraulic oil, and a free piston is used to partition the gas chamber. A structure in which an elastic body such as a closed-cell sponge is interposed in a cylinder.

In either structure, when the piston rod enters the cylinder and the pressure in the cylinder rises, the gas or the elastic body contracts, thereby absorbing the working oil corresponding to the penetration volume of the piston rod. .

[0004]

Since the structure of the present invention does not include a free piston, the structure can be simplified, and a troublesome degassing operation is not required in the manufacturing process. However, when this structure is applied to a single-cylinder cylinder, hydraulic oil squirts into the gas as the piston moves,
There is a problem that the gas is mixed into the hydraulic oil and the desired damping characteristics cannot be obtained. For this reason, it is necessary to apply the oil chamber partitioned by the piston and the gas chamber filled with gas to a multi-cylinder cylinder or the like that defines the inside and outside of the cylinder, respectively, which causes an increase in the size of the shock absorber.

The structure described above prevents gas from being mixed into the working oil via the free piston, and can be applied to a single cylinder type cylinder. However, the provision of the free piston not only complicates the structure and raises the cost of the product, but also causes a problem that the friction increases due to the movement of the free piston and the operability deteriorates. further,
Since it is necessary to fill the cylinder only with hydraulic oil so that gas (air) does not enter the cylinder, a step of removing gas from the cylinder is required, and there is a problem that productivity is poor.

In the structure of (1), no gas is sealed in the cylinder, so that the gas does not mix with the working oil, and there is no need to provide a free piston, so that the structure can be simplified. However, also in this case, since it is necessary to fill only the working oil so that the gas does not enter the cylinder, a step of removing the gas from the cylinder is required, and there is a problem that productivity is poor.

The present invention has been made in view of the above problems, and has a relatively simple structure, does not require complicated operations such as degassing, and can be applied to a wide range of hydraulic shock absorbers from small to large. An object of the present invention is to provide an accumulator structure.

[0008]

According to a first aspect of the present invention, there is provided an oil chamber in which a piston rod is inserted into a cylinder, and an accumulator is formed in the cylinder, the accumulator allowing a volume of hydraulic oil into and out of the cylinder. In the hydraulic shock absorber connected to the, the accumulator includes an elastic body chamber in which the elastic body is housed, and a gas chamber partitioned by the elastic body,
The gas chamber is connected to the oil chamber via the elastic body chamber.

According to a second aspect, in the first aspect, a bearing member for slidably supporting a piston rod is interposed in the cylinder, and an elastic body chamber and a gas chamber are defined between the bearing member and the cylinder. And a cylindrical elastic body interposed between the bearing member and the cylinder.

According to a third aspect, in the first or second aspect, a bush made of an elastic material is attached to a tip of a piston rod extending from the cylinder.

[0011]

According to the first aspect of the present invention, the accumulator is constituted by the elastic body chamber in which the elastic body is housed and the gas chamber partitioned by the elastic body, and eliminates the free piston that partitions the gas chamber. In addition, the operability of the shock absorber can be enhanced by reducing the friction caused by the movement of the free piston, and the structure can be simplified.

[0012] Even if gas (air) enters the cylinder in the manufacturing process, the gas mixed in the cylinder is collected in the gas chamber via the elastic body by the expansion and contraction operation of the hydraulic shock absorber. The gas once collected in the gas chamber is stopped from returning to the oil chamber due to differences in the moving speed of the working oil, the pressure change, the contraction speed of the elastic body, and the like.

Since the gas that has entered the cylinder is confined in the gas chamber in this manner, the desired damping characteristics can be obtained, and a step of removing the gas from the cylinder is not required, thereby increasing the productivity and reducing the cost of the product. .

According to the second aspect of the present invention, since the elastic body chamber and the gas chamber are defined between the bearing member and the cylinder, the bearing member can be made longer by utilizing the space in which the accumulator is provided. Sufficient support rigidity of the rod can be secured.

According to the third aspect of the present invention, when the piston rod abuts on the other side via the bush, the bush is elastically deformed in the axial direction, thereby alleviating the shock and preventing the generation of loud noise and vibration. You.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The hydraulic shock absorber 10 shown in FIG. 1 has a cylindrical cylinder 1 and an inside of the cylinder 1 with an extension oil chamber R1 and a compression oil chamber R.
2, a piston rod 2 extending from the cylinder 1 in conjunction with the piston 3, and an accumulator 11 for permitting hydraulic oil corresponding to the volume of the piston rod 2 to enter and exit the cylinder 1.

The cylinder 1 has a cylindrical cylinder portion 1a for slidably receiving the piston 3 and a bottom portion 1b, and these are integrally formed by molding a resin. The outer peripheral surface of the cylinder portion 1a is formed in a tapered shape so as to become gradually thinner from the opening end to the bottom portion 1b, so that the cylinder 1 can be easily inserted into a mounting hole (not shown).

At the open end of the cylinder 1 is a plug 15 made of resin.
Are fitted, an annular oil seal 4 is interposed between the plug 15 and the piston rod 2, and the oil seal 4 prevents leakage of hydraulic oil.

The cylinder 1 may be integrally formed of metal, and may have a structure in which an open end thereof is bent inward and an annular oil seal or the like is fixed by caulking.

The piston rod 2 is supported on the cylinder 1 via a resin bearing member 5 so as to be slidable in the axial direction. The bobbin-shaped bearing member 5 has flange portions 5a and 5
b. The flange 5a is fitted to the plug 15, and the flange 5b is fitted to the cylinder 1.

A ring 6 is fitted to the end of the piston rod 2. When the ring 6 comes into contact with the end face of the bearing member 5, the piston rod 2 is prevented from coming off.

The piston rod 2 and the piston 3 are separately provided without being connected to each other. A spring 8 for pressing the piston 3 against the piston rod 2 is provided, and the piston 3 follows the piston rod 2 by the urging force of the spring 8. The coiled spring 8 is interposed between the piston rod 2 and the bottom 1b of the cylinder 1 in a compressed state.

The piston 3 is provided with an extension oil chamber R1 and a compression oil chamber R2.
And a pressure-side check valve 14 that opens for the flow of hydraulic oil from the expansion-side oil chamber R1 to the compression-side oil chamber R2. This allows
The damping force at the time of the compression side operation in which the piston rod 2 enters the cylinder 1 is higher than the damping force at the time of the extension side operation in which the piston rod 2 extends from the cylinder 1.

The accumulator 11 has an elastic body chamber 12 in which the elastic body 9 is accommodated, and a gas chamber 13 partitioned by the elastic body 9. The gas chamber 13 is connected to the oil chamber R through the elastic body chamber 12.
Communicate with 1.

The elastic body chamber 12 is defined between the cylinder 1 and the bearing member 5 and communicates with the extension-side oil chamber R1 via a communication passage 5c formed by cutting out a flange portion 5b of the bearing member 5.

The elastic body 9 is formed, for example, by molding a nitrile rubber foam into a cylindrical shape. The foam (closed cell sponge) has a large number of independent voids (bubbles) as a whole, and expands and contracts by the pressure guided to the elastic body chamber 12.

An annular step 5d is formed in the middle of the bearing member 5, and the elastic body 9 is interposed between the annular step 5d and the flange 5b.

The gas chamber 13 is defined as a cylindrical space between the cylinder 1, the bearing member 5, and the plug 15, and communicates with the extension oil chamber R1 via the elastic body chamber 12 and the communication passage 5c.

At the time of assembling the hydraulic shock absorber 10, after the cylinder 1 is filled with a predetermined amount of hydraulic oil (for example, silicon oil), the cylinder 1 and the plug 15 together with the piston rod 2 are filled.
By assembling, a predetermined amount of gas (air) is sealed in the cylinder 1.

The hydraulic shock absorber 10 is mounted such that the position of the gas chamber 13 is not lower than that of the elastic body chamber 12, and the gas in the cylinder 1 is guided to the gas chamber 13 by its buoyancy. In the present embodiment, the hydraulic shock absorber 10 is attached so as to extend substantially horizontally.

A bush 22 made of a soft resin as an elastic material is attached to the tip of the piston rod 2.
The bush 22 having a cylindrical shape with a bottom is a hard resin cap 2
1 and the cap 21 is pressed into the tip of the piston rod 2. The bush 22 has a bellows shape having three annular concave portions 22a on its outer periphery. When the piston rod 2 comes into contact with the other side through the bush 22, the bush 2
By elastically deforming the shaft 2 in the axial direction, the shock is alleviated, and generation of loud noise and vibration is prevented.

The operation is described below, with the above configuration.

When the piston rod 2 is pushed into the cylinder 1, the check valve 14 is closed, and the hydraulic oil in the pressure oil chamber R2 passes through the orifice 3c to extend the oil chamber R1.
Flows into. In this way, the orifice 3c
The damping force is generated by the resistance given by the hydraulic shock absorber 1
0 contracts slowly. At this time, the working oil corresponding to the intrusion volume of the piston rod 2 flows into the elastic body chamber 12 and the gas chamber 13 from the pressure side oil chamber R2 through the communication passage 5c.

When the piston rod 2 extends from the cylinder 1, the check valve 14 opens, and the hydraulic oil in the extension oil chamber R1 flows into the compression oil chamber R2 through the check valve 14 and the orifice 3c. I do. In this way, the damping force is hardly generated due to the increase in the flow path area, and the hydraulic shock absorber 10 is quickly extended. At this time, the operating oil corresponding to the intrusion volume of the piston rod 2 is
3 and return to the pressure side oil chamber R2 through the communication passage 5c from the elastic body chamber 12.

Even if gas (air) is mixed into the hydraulic oil of each of the oil chambers R1 and R2 of the hydraulic shock absorber 10 in the manufacturing process, if the hydraulic shock absorber 10 is attached and expanded and contracted several times, the time of the pressure side operation is Since the pressure change speed in the cylinder 1 and the expansion / contraction speed of the elastic body 9 are different during the extension side operation, the gas in the cylinder 1 enters the gas chamber 13 via the elastic body chamber 12,
The elastic body 9 stops the gas that has entered the gas chamber 13 from returning to the pressure side oil chamber R2.

More specifically, during operation on the compression side, the piston rod 2 slowly enters the cylinder 1 due to the damping force.
Hydraulic oil corresponding to the intrusion volume of the piston rod 2 flows into the elastic body chamber 12 together with the gas from the pressure side oil chamber R2 through the communication passage 5c while contracting the elastic body 9, and the gas flowing into the elastic body chamber 12 is a gas. It flows into the chamber 13. On the other hand, since the piston rod 2 immediately extends from the cylinder 1 during the extension side operation, only the hydraulic oil passes from the elastic chamber 12 through the communication passage 5c while the gas remains in the gas chamber 13, and the compression side oil chamber R2 The gas in the gas chamber 13 is confined via the elastic body 9.

In this way, the gas in the cylinder 1 is
And escapes from the expansion-side oil chamber R1 and the compression-side oil chamber R2, so that the flow of the hydraulic oil passing through the orifice 3c is not affected by the gas, and the desired damping characteristics can be obtained.

Since the accumulator 11 is composed of the elastic body chamber 12 in which the elastic body 9 is accommodated and the gas chamber 13 partitioned by the elastic body 9, the accumulator 11 defines the gas chamber via a free piston sliding on the cylinder. The structure can be simplified as compared with the conventional structure to be formed.

At the time of assembling the hydraulic shock absorber 10, after the cylinder 1 is filled with a predetermined amount of hydraulic oil, the plug 1
5 is assembled and a predetermined amount of gas is sealed in the cylinder 1. Therefore, a step of removing gas from the cylinder 1 at the time of assembling the hydraulic shock absorber 10 is not required.
The process of wiping out the hydraulic oil overflowing from inside becomes unnecessary, and the productivity can be increased.

The elastic chamber 1 is provided between the bearing member 5 and the cylinder 1.
Due to the structure that defines the gas chamber 2 and the gas chamber 13, the bearing member 5 can be lengthened by utilizing the space in which the accumulator 11 is provided, and the support rigidity of the piston rod 2 can be sufficiently ensured.

As a result, the piston rod 2 is connected to the piston 3
It is possible to provide a structure that is not coupled to
High machining accuracy is not required for the piston rod 2 or the piston 3, and the piston rod 2 can be formed in a simple columnar shape, thereby improving productivity.

It is obvious that the present invention is not limited to the above-described embodiment, and that various changes can be made within the scope of the technical idea.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic shock absorber according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston rod 3 Piston 3c Orifice 5 Bearing member 8 Spring 9 Elastic body 10 Hydraulic shock absorber 11 Accumulator 12 Elastic body chamber 13 Gas chamber 14 Check valve R1 Extension oil chamber R2 Pressure oil chamber

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Miyazawa 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd. (72) Inventor Nobumasa Ogino 616-1 Wakaho Kawada, Nagano City, Nagano Prefecture Inside Nagano Jeco Co., Ltd. (72) Inventor Norimichi Miyazawa 616-1 Wakaho Kawada, Nagano City, Nagano Prefecture F-term in Nagano Jeco Co., Ltd. 3J069 AA51 DD33 DD38 EE05 EE28

Claims (3)

[Claims] 1. A hydraulic shock absorber in which a piston rod is inserted into a cylinder, and an accumulator for permitting the flow of hydraulic oil in and out of the volume of the piston rod into and from the cylinder communicates with an oil chamber formed in the cylinder. The accumulator includes an elastic body chamber in which an elastic body is housed, and a gas chamber partitioned by the elastic body, wherein the gas chamber communicates with the oil chamber via the elastic body chamber. Hydraulic shock absorber. 2. A cylinder having a bearing member for slidably supporting the piston rod, wherein the elastic body chamber and the gas chamber are defined between the bearing member and the cylinder. The hydraulic shock absorber according to claim 1, wherein the elastic body is interposed between the bearing member and the cylinder. 3. The hydraulic shock absorber according to claim 1, wherein a bush made of an elastic material is attached to a tip of the piston rod extending from the cylinder.