JPS5825895B2 - gas spring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas spring whose gas spring characteristics can be freely changed.

The gas spring characteristics of conventional gas springs are determined by the gas pressure at the time of initial sealing, and therefore the range of use is extremely limited.

The present invention solves the above-mentioned problems and is characterized in that the gas spring characteristics can be easily changed by changing the volume of a chamber filled with gas from the outside.

Next, a conventional gas spring and an embodiment of the present invention will be described with reference to the drawings.

The first rotation and FIG. 2 show the structure and gas spring characteristics of a conventional gas spring.

One end of the tube 1 is tightly closed with a lid 2, a rod guide 3 is fixed to the other end, and the inside is divided into two chambers A and B by free histones 4.

This compartment is kept airtight by an O-ring 5 provided on the free piston 4.

This chamber A is filled with compressed gas having a predetermined pressure, and the chamber B is filled with an incompressible liquid.

Furthermore, a piston 6 is slidably fitted into the B chamber.
A rod 7 of the piston 6 is slidably supported by the rod guide 3 and protrudes to the outside.

Further, the inside of the tube 1 is sealed from the outside by a lid 2 and a seal 8.

The piston 6 is provided with an orifice 9 that communicates between chambers formed on both sides of the piston 6.

Now, in the structure of such a gas spring, AR:
Cross-sectional area S of rod 7: Amount of movement of piston 6 (or rod 7) from its maximum extension PO: Gas pressure in chamber A when S=O vA: Volume Ps in chamber A when S=O: Piston 6 If the gas pressure in chamber A when (or rod 7) moves by S from the maximum extension is, then, and if the force pushing out rod 7 at this time (hereinafter referred to as gas reaction force) is Fs, then Fs. S = ARX P S
(2) becomes.

From these two equations, the relationship between S and FS (this is called the gas spring characteristic) is shown in a graph as shown in FIG.

In this way, the gas spring characteristics of conventional gas springs are
The characteristics shown in the figure are limited, and therefore, the range of use is also very limited.

The present invention aims to improve this drawback, and one embodiment will be described with reference to FIGS. 3 to 5.

Here, the same reference numerals as in FIG. 1 indicate the same components.

In this embodiment, as shown in FIG. 3, a fixed wall 10 is fitted and fixed by a circumferential protrusion provided on the inner surface of the tube 1 at any appropriate location in the A room. 10 has a valve seat 10' in its center, and has a valve seat 10' in the A chamber.
It is divided into two rooms, D.

A seal member 11 seals between the inner surface of the circumferential protrusion of the tube 1 and the outer surface of the fixed wall 10 .

Compressed gas is sealed in chambers C and D, and oil liquid is filled in chambers C and B.

A push pin 12 is attached to the rod 7 through the fixed wall 10 and the lid 13.
A valve portion 12a is provided at the end of the push pin 12 that protrudes to the opposite side and faces into the C chamber.
When seated on the valve seat 10', the chamber C and the chamber D are completely separated.

Therefore, the inside of the tube 1 is controlled by the valve portion 12a.
When the chamber and D chamber are separated, the rod 7 indirectly faces the D chamber via the oil, and the C chamber becomes a gas chamber with which the rod 7 is completely unrelated.

14 is a seal that maintains airtightness.

In addition, a force is always applied to this push pin 12 in the direction of protrusion due to the gas pressure in chamber A. Therefore, when no external force is applied to the push pin 12, the valve portion 12a of the push pin 12 is fixed. It is seated on a valve seat 10' on the wall 10, and the C chamber and D chamber are always separated.

In a gas spring having such a structure, if a pushing force is applied from the outside to the push pin 12 in the direction of the arrow in FIG. , the internal pressures of chamber C and chamber D are the same.

It is assumed that the gas spring characteristics in this state are as shown by the solid line ■ in FIG.

Now, as shown in FIG. 3, when the gas spring is fully extended, the pushing force of the push pin 12 is removed and chambers C and D are completely closed, the gas spring characteristics are as described in (1) above. This is because it can be replaced with V □ −+ V D in equation (2).

However, Vc: Volume of chamber C when S=0 vD: Volume of chamber D when s=o VA=VC+VD Ps: D when histone 6 (or rod 7) moves by S at its maximum extension If the gas pressure in the chamber is increased and the gas reaction force of rod 7 at this time is FS', then Es = ARXPs' (
4).

Here, since VA>VD, PS<PS', and therefore FS<F's' holds true.

If this is represented in a graph, the gas spring characteristics indicated by the two-dot chain line ■ in FIG. 5 can be obtained.

Similarly, as shown in Fig. 4, the piston 6 is 81
The gas spring characteristics when chamber C and chamber D are separated at the time of movement are as shown by the chain line ■ in FIG.

Also, when the piston 6 is moved by Sn from the maximum extension, C
If the chamber and D chamber are separated, the gas spring characteristics will be as shown by the line ■ in FIG.

In this way, by separating the C chamber and the D chamber when the piston 6 moves an arbitrary amount, arbitrary gas spring characteristics can be obtained.

In the gas spring shown in FIG. 3, when the rod 7 is used in an upright position with the rod 7 facing downward, the free piston 4 is not required.

FIG. 6 shows another embodiment of the present invention, in which both chambers A1B are filled with compressed gas.

In this figure, the same parts as in FIG. 3 are given the same reference numerals.

Even in this embodiment, gas spring characteristics are changed by cutting off communication between chambers A and B.

In each embodiment, the push pin 12 is used to cut off the communication, but the communication may be cut off by rotation.
In short, any valve mechanism may be used as long as it is capable of shutting off communication by external operation. Since the structure is as described above, the present invention has the following effects.

(1) A single product can be used in a wider range of applications, allowing the product to be used more effectively.

(2) Gas spring characteristics can be changed with simple external operation.
Good workability.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the conventional product, Figure 2 is a gas spring characteristic diagram of the gas spring in Figure 1, Figures 3, 4, and 6.
The figure is a sectional view of the gas spring of the present invention, and FIG. 5 is a gas spring characteristic diagram of the gas spring of the present invention. 1... Chu 7.4... Free piston, 10...
・Fixed wall, 1σ... Valve seat, 12a... Valve part, 13.
...Lid, A. C2 D...room.

Claims (1)

[Claims] 1 A chamber filled with compressed gas in a tube is kept airtight with a fixed wall and divided into two chambers, a rod is exposed to one of the chambers so that it can be entered and exited from the outside, and communication between the two chambers is cut off by the fixed wall. What is claimed is: 1. A gas spring characterized in that a valve mechanism is provided, and the valve mechanism can be operated from the outside.