JPS6115295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas spring locking device used for opening and closing the back door of an automobile or the like.

Generally, gas springs are used to reduce the weight load when opening and closing the back door of an automobile or the like. In order to hold the back door in the open position, this gas spring has a locking device that prevents the gas spring from operating in the direction of contraction after being expanded.

Conventionally, this type of device was developed in Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent Application Laid-open No. 54775 and Japanese Patent Application Laid-Open No. 1987-19277, most of the methods used were mechanical means.

That is, the engagement between the retaining ring fitted in the sleeve on the cylinder side and the annular groove formed in the bush on the piston rod side (according to JP-A-50-54775, but also in JP-A-49-19277). ), etc., the gas spring is locked.

However, these locking devices have the disadvantage of increasing the number of parts due to the retaining ring, etc., and increasing the number of processing steps due to the complicated shape of the bushings, which naturally leads to an increase in costs.In addition, the structure becomes complicated and the device lacks reliability. It was hot.

The present invention has been proposed in view of this point, and by effectively utilizing the cushion rubber normally provided near the end inside the cylinder to hold the cylinder in the extended position, the present invention does not increase the number of parts. It is an object of the present invention to provide a locking device for a gas spring that simplifies the device and reduces costs.

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

FIG. 1 is a longitudinal sectional view of a gas spring having a locking device according to the present invention, in which 1 is a cylinder filled with hydraulic fluid, 2 is a piston that separates the inside of the cylinder 1 into oil chambers A and B, and 3 is a cylinder filled with hydraulic fluid. a piston rod 4 whose one end is fixed to the piston 2 and whose other end protrudes outside the cylinder 1;
5 is a piston rod guide provided with a sealing member;
is a free piston that further defines a gas chamber C within the cylinder 1.

An annular cushion rubber 6 is fixed in the cylinder 1 at a position close to the rod guide portion 4 by caulking or the like.

This cushion rubber 6 is provided not only to protect the rod guide portion 4 and the like from impact when the gas spring is fully extended, but also constitutes a part of the locking device for the gas spring.

That is, an annular tongue piece 7 is integrally formed at the end of the inner peripheral surface of the cushion rubber 6 on the piston rod guide portion 4 side.

The tip of the tongue 7 contacts the outer peripheral surface of the piston rod 3 and is elastically deformable as the piston rod 3 moves.

The cushion rubber 6 is further formed with an oil release hole 8 that passes through the interior of the cushion rubber 6 vertically in the figure. As a result, no oil lock occurs in the upper chamber 11 of the cushion rubber 6 when the gas spring is expanded, and dangers such as oil leakage from the piston rod guide portion 4 and the like can be prevented.

On the other hand, a tapered sleeve 9 is fitted onto the piston rod 3, which is inserted into the cushion rubber 6 when the piston rod is extended, and which together with the tongue piece 7 forms a sealed space D around the piston rod 3 for a certain period of time.

This taper sleeve 9 is connected to the shoulder 3a of the piston pilot part of the piston rod 3 and the valve stopper 10.
The valve stopper 10 or the like may be fixed by the valve stopper 10 or the like, or may be press-fitted into the piston rod 3 and positioned by the end face of the valve stopper 10 or the like. A liquid sealant or the like is used to prevent oil leakage between the inner circumference of the tapered sleeve 9 and the piston rod 3.

The outer diameter and taper angle of the tapered sleeve 9 are set so as to seal the inner circumferential end of the cushion rubber 6 over its entire circumference after being inserted into the cushion rubber 6.

Next, the operation of the present invention configured as described above will be explained.

When the gas spring is released from the compressed state (i.e., the state in which the back door, etc. is closed),
The piston 2 and the piston rod 3 begin to move in the extension direction due to the gas pressure in the gas chamber C.

When the external protrusion length of the piston rod 3 approaches the maximum length, the tip of the tapered sleeve 9 is slid into the cushion rubber 6, and when it eventually balances the load of the gas spring, the stopper 10 and The ends of the cushion rubber 6 are brought into pressure contact and the extension operation is completed.

During this time, the pressure in the space D tends to rise due to the entry of the tapered sleeve 9, but due to the upward deformation of the tongue piece 7 in the figure, the pressure oil is transferred to the cushion rubber 6.
It can escape into the upper chamber 11, keeping the pressure the same as the others. The pressure oil in the upper chamber 11 of the cushion rubber 6 is returned to the oil chamber A through the oil relief hole 8.

Here, when a force is applied to contract the gas spring due to the weight of the back door, etc., the taper sleeve 9 begins to descend slightly together with the piston rod 3, but in this direction, the space D is closed by the action of the tongue piece 7. Since it can be kept in a sealed state, negative pressure is generated in response to the withdrawal of the taper sleeve 9, and this negative pressure prevents the piston rod 3 from descending.

In order to release this locked state, when a force that overcomes the negative pressure and the contact friction force of the sleeve 9 is applied from the outside, the tongue piece 7 is rolled downward as shown in FIG. so that
Alternatively, if the tongue piece 7 has sufficient strength to overcome the negative pressure, the negative pressure state in the space D is eliminated without being caught, and the locked state is released.

In this way, gas springs are locked by negative pressure, so compared to conventional mechanical means, the locking force is constant, and the locking force does not vary depending on conditions. There isn't.

As described above, according to the present invention, a sealed space is formed around the piston rod by the tongue piece integrally formed on the cushion rubber and the tapered sleeve inserted into the cushion rubber.
Since the gas spring is configured to be locked by the negative pressure generated in this space, a more reliable holding force can be obtained, and the number of parts can be reduced, resulting in cost reduction.
There is also the advantage that the entire device is simplified and the reliability of the device is improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a gas spring having a locking device of the present invention, and FIG. 2 is a sectional view of a main part showing its operating state. 1...Cylinder, 6...Cushion rubber, 3
... Piston rod, 7... Tongue piece, D... Space,
9... Taper sleeve.

Claims (1)

[Claims] 1. In a gas spring in which an annular cushion rubber is provided in a cylinder to absorb the impact of the piston rod at its most extended position, the cushion rubber is fixed to the cylinder, and the inner circumferential end of the cushion rubber is fixed to the cylinder. The piston rod is characterized by forming an annular tongue piece that is free to elastically deform, and fixing to the piston rod a tapered sleeve that is inserted into the cushion rubber when the piston rod is in an extended position and forms a sealed space around the piston rod together with the tongue piece. Gas spring locking device.