JPS6224657B2 - - 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.

This gas spring has a locking device that lightly fixes the gas spring at the fully extended position in order to hold the back door stationary in an open state.

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 disadvantages of increasing the number of parts due to retaining rings, etc., and increasing the number of processing steps due to the complicated shapes of the bushings, which naturally lead to increased costs, and in addition, the structure becomes complicated and the device lacks reliability. Ta.

The present invention has been proposed in view of the above, and is configured to bias the extension side check valve provided at the upper part of the piston toward the closing side by the compression reaction force of the spring member during full extension. The purpose is to solve shortcomings.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a sectional view showing a first embodiment of the present invention.
1 is a cylinder filled with hydraulic oil, 2 is a piston that separates the inside of cylinder 1 into oil chambers A and B, 3 is a piston rod with one end fixed to piston 2 and the other end protruding outside cylinder 1, and 4 A piston rod guide section equipped with a sealing member, 5 a cushion rubber that protects the rod guide section 4 etc. from shocks when the gas spring is fully extended, and 6 a stopper that supports the cushion rubber 5 near the rod guide section 4. be.

A free piston (not shown) that separates a gas chamber from the oil chambers A and B in the cylinder 1 is housed below the piston 2 in a freely sliding manner, and this gas pressure pushes the piston 2 upward. It's energizing.

The piston 2 is fastened to the piston rod spigot part 3a with a nut 7, and there are through holes 8A and 8B inside thereof that communicate the oil chamber A and the oil chamber B.
intersect each other (that is, the upper and lower opening positions of the piston 2 are symmetrically shifted in the radial direction),
Multiple holes are drilled.

An annular non-return valve (check valve) 9 is provided on the lower surface of the piston 2 on the through hole 8A side, and opens with almost no resistance to oil flow from oil chamber A to oil chamber B. Conversely, the oil flow from oil chamber B to A is blocked.

On the one-way through hole 8B side, a non-return valve (check valve) 10 is provided located on the upper surface of the piston 2, and contrary to the above, it does not allow oil flow from oil chamber B to oil chamber A during normal stroke. , the oil flow from oil chamber A to B is blocked.

Further, in the pilot part (stepped part) 3b of the piston rod 3, cylindrical spring guides 11A and 11B with flanges are fitted to be able to freely slide between the cushion rubber 5 and the piston 2. A coil-shaped spring 12 is interposed between the guides 11A and 11B to seal the oil chamber A when the piston rod 3 is extended or released, which will be described later.

That is, when the spring 12 is located at a location other than the vicinity of the fully extended position of the piston 2, the spring guides 11A and 11B are separated from each other (stepped portion 3b
It extends to the free length (by the length of the spring) and is set in a state where no spring reaction force is generated.

On the other hand, when the piston 2 approaches the fully extended position, when the spring guide 11A comes into contact with the cushion rubber 5, the spring 12 starts to be compressed, and this continues until the other spring guide 11B comes into contact with the spring guide 11A. Continuing,
Eventually, the spring guide 11 will move with a predetermined set load.
The non-return valve 10 is biased toward the closing side through the flange portion B.

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 are actuated in the extending direction by the gas pressure in the gas chamber, and at this time, the hydraulic oil in the oil chamber A that contracts flows into the oil chamber B through the through hole 8A (however, if the pressure receiving area of the lower surface of the piston is (The piston 2 is urged upward because it is larger than the upper surface by the cross-sectional area of the rod.)

When the outward protrusion length of the piston rod 3 approaches the maximum length, the spring guide 11A comes into contact with the cushion rubber 5 as described above.
After this, the spring 12 is compressed by the load of the gas spring, and eventually the spring guide 11B comes into contact with the spring guide 11A, and the extension operation is completed.

In this state, due to the compression reaction force of the spring 12, the non-return valve 10, which should be freely opened in the direction toward the rod compression side, is held closed.

Here, if a load greater than the set load of the gas spring acts on the back door, since the oil chamber A is in a sealed state, negative pressure (but less than the load of the spring 12) will be generated in response to the downward force of the piston 2, etc. ,
This negative pressure prevents the piston rod 3 from descending.

In other words, in order to contract the gas spring, oil needs to flow from oil chamber B to oil chamber A through the through hole 8B, but the non-return valve 10 is closed by the compression reaction force of the spring 12. Therefore, a force sufficient to overcome the set load of the spring 12 is required. Therefore, as shown by the solid line in Fig. 2, a force is required near the extension position (distance S).
The operating force on the contraction side increases significantly compared to the normal stroke range.

Therefore, in order to release this lock state,
By applying a force exceeding the maximum operating force shown in Fig. 2 from the outside, the piston rod 3 descends against the load of the gas spring, and at the same time the compression reaction force of the spring 12, which is decreasing due to this descent, is reduced. Non-return valve 10 against
is opened slightly upward, the sealing of the oil chamber A is gradually released, and eventually as the piston rod 3 descends, the spring 12 becomes free length and the compression reaction force becomes 0, resulting in the normal stroke shown in Fig. 2. Return to operating power.

Since the gas spring is thus held in the fully extended position by negative pressure, its holding force is constant and does not vary depending on the conditions, compared to when using conventional mechanical means.

Further, the size of this lock can be easily selected by changing the spring force of the spring 12, the pressure of the sealed gas, etc.

Next, FIGS. 3A, B, and C show other embodiments of the present invention. FIG. 3A shows a disc spring 12' instead of the coil spring 12 in the previous embodiment.
This has the advantage that the spring guide 11B on the side of the non-return valve 10 is not required, and that the longitudinal dimension can be reduced and the initial reaction force can be increased.

3B and 3C, the shape of the rubber stopper 6' (FIG. 3B) or cushion rubber 5' (FIG. 3C) containing the reinforcing material 14 is changed, and the compression stroke is made by utilizing its elasticity. By making the springs 12 and 12' longer, the same effect can be obtained in place of the springs 12 and 12' of the previous embodiment.
In the figure, reference numeral 15 denotes a washer for uniformly pressing the non-return valve 10 against the piston 2 without deformation by receiving the reaction force of the rubber stopper 6' or the cushion rubber 5'.

As explained above, according to the present invention, the extension side check valve provided at the upper part of the piston is configured to be biased toward the closing side by the compression reaction force of the spring member when the piston rod is fully extended. Since the gas spring is held by sealing the oil chamber, a more reliable and stable 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 sectional view of a gas spring having a locking device of the present invention, Fig. 2 is an explanatory diagram showing the relationship between the operating force and stroke of the gas spring, and Figs. FIG. 3 is a cross-sectional view showing an example. 1...Cylinder, 3...Piston rod, 2...
...Piston, A, B...Oil chamber, 8A, 8B...Through hole, 9, 10...Non-return valve, 12...
spring.

Claims (1)

[Claims] 1. In a gas spring whose cylinder is filled with gas to constantly urge the piston rod toward the expansion side, a plurality of oil passages are formed in the piston that connect the oil chambers on both sides of the piston, and each oil passage has a constant flow direction. A compression side check valve and a rebound check valve are arranged to provide resistance to the piston and prevent the flow in the opposite direction, while a spring member is provided above the piston to bias the rebound check valve toward the closing side when the piston is in the fully extended position. Gas spring locking device.