JPS6237266B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas-filled stay damper attached to a back door of an automobile, and more particularly to a holding device at the damper extended position.

In a gas-filled stay damper that supports the back door of an automobile, a device for restraining the piston rod to prevent the door from contracting due to the weight of the back door and falling when the pressure of the filled gas decreases has been disclosed in Japanese Patent Application Laid-Open No. 1972- It is disclosed in Publication No. 52081.

As shown in FIG. 1, the piston rod 3 of the piston Z, which can freely slide in the cylinder 1, penetrates the partition wall (free piston) 4 and protrudes to the outside. When the pressure of the sealed gas decreases, the tapered sleeve 6 restrains the gas.

The tapered sleeve 6 is pressed against the upper surface of the partition wall 4 by a compression disc spring 7, and the cylinder 1
It is inserted through a hollow disk 8 fixed to the upper end of the .

The taper sleeve 6 has a plurality of slits 9 formed in the axial direction, and when it moves downward from the state shown in the figure and the taper outer circumferential surface contracts, the piston rod 3 inserted freely inside is tightened to prevent its movement. In other words, the piston rod 3 is fixed.

The partition wall 4 is displaced according to the pressure balance between the pressure in the oil chamber 5 and the compression disk spring 7. Therefore, when the gas pressure that pressurizes the oil chamber 5 is sufficiently high, the partition wall 4 compresses the compression disc spring 7 and is positioned upward, and the tapered sleeve 6 is protruded to the outside, so that the piston rod The piston 2 pushes up the back door of the automobile to the fully open position in response to gas pressure without tightening the outer periphery of the piston 3.

On the other hand, if the pressure decreases due to a leak of the filled gas, there is a risk that the piston rod 3 will contract because it cannot support the weight of the back door, etc.; The elastic force of the spring 7 pushes it downward, and the hollow disk 8 tightens the outer periphery of the tapered sleeve 6, so that the piston rod 3 is completely fixed in that position by a wedge effect.

Therefore, this device senses a drop in the pressure of the filled gas and automatically locks the door, so even if you let go of the back door before it is fully open, the weight of the back door will prevent the door from falling suddenly. It is possible to prevent this from happening.

However, in this device, when a lateral load is applied to the piston rod 3, the piston rod 3 is supported by the partition wall 4, so the operability (sliding) of the partition wall 4 gradually deteriorates, and the internal gas Even if the pressure decreases, it will no longer be able to follow this and the piston rod 3
It becomes difficult to securely restrain the tapered sleeve 6, and furthermore, dust and the like enter and accumulate on the compression disk spring side inside the hollow disk 8 through the slit 9 for facilitating the diameter reduction of the tapered sleeve 6. There was a problem in that the deflection characteristics of the disc spring 7 and the operability of the partition wall 4 were deteriorated, making it impossible to perform a smooth holding function.

The present invention has been proposed to solve such problems, and embodiments will be described below based on the drawings.

In FIGS. 2 and 3 A and B, 20 is a cylinder, 21 is a piston that can freely slide in this cylinder 20, 22 is a piston rod connected to piston 21, 23 is a free piston inserted in the lower part of piston 21, and 24A and 24B are oil chambers, and 25 is a gas chamber filled with gas at a predetermined pressure.

The hydraulic oil in the oil chambers 24A and 24B is pressurized to a pressure corresponding to the sealing pressure in the gas chamber 25, and constantly presses the piston 21 toward the expansion side with a pressure corresponding to the difference in pressure receiving area.

An annular guide bearing 26 is fixed to the upper end (the most extreme end) of the cylinder 20, and an annular stopper 27 is fixed below this bearing 26.

These guide bearings 26 and stopper 27
A free piston 28 which is oil-sealed between the outer circumference of the piston rod and the inner circumference of the cylinder.
is interposed, and on the upper surface of this free piston 28,
A movable locking member 31 consisting of a tapered sleeve 29 having a wedge action that tightens the piston rod 22 when the gas pressure decreases and a supporting cylinder 30 integral with the tapered sleeve 29 is provided.

A compression spring (disc spring) is installed between the upper end 32 of the support cylinder 30 and the lower end of the guide bearing 26.
33 are interposed. An annular locking ring 34 that wraps around the compression spring 33 and the movable locking member 31 and engages with the tapered sleeve 29 through its tapered surface 34A when the gas pressure decreases is fixed at a predetermined position on the inner wall of the cylinder. There is.

As is clear from FIGS. 4A and 4B, the tapered sleeve 29 is formed with a slit 35 that extends in the axial direction to the support tube 30, and these movable locking members 31 are made of an elastic material (for example, Teflon, hard rubber, plastic, etc.). ).

The inner diameter of the stopper 27 is set to be slightly larger than the outer diameter of the piston rod 22 so that its upper and lower surfaces communicate with each other.

Next, the effect will be explained.

When the pressure of the gas sealed in the stay damper is sufficiently high, the hydraulic oil in the oil chambers 24A and 24B is also pressurized by this gas pressure, and the free piston 28 is compressed by this hydraulic oil pressure through the gap between the stopper 27 and the piston rod 22. It is pressed upward against the spring 33.

Therefore, the tapered sleeve 29 of the movable locking member 31 is separated from the tapered surface 34A of the locking ring 34,
The piston rod 22 is allowed to freely expand and contract without being restrained (see FIG. 3A). On the other hand, if the sealed gas leaks and the gas pressure drops, the free piston 28 is pressed downward by the elastic force of the compression spring 33, and the movable locking member 31 taper sleeve 29 is drawn inward while slidingly contacting the tapered surface 34A of the locking ring 34, and tightens and holds the piston rod 22 (see FIG. 3B).

In this manner, when the gas pressure in the stay damper decreases, the movement of the piston rod 22 is reliably restrained by the wedge action.

On the other hand, when a lateral load is applied to the piston 22 during normal use, this load is effectively borne by the guide bearing 26 provided at the tip end of the cylinder 20, so that the free piston There is no possibility that an overload acts on the piston 28 and obstructs its movement, and good movement of the free piston 28 can be ensured at all times.

Furthermore, in order to prevent dust from entering through the slit 9 of the tapered sleeve 6 that protrudes upward, which was a problem in the past, the guide bearing 26 seals the lower stopper mechanism from the outside. can be reliably prevented.

Furthermore, since the locking ring 34 is separated from the guide bearing 26 and is disposed so as to wrap around the outside of the compression spring 33 and the movable locking member 31, the members 33, 31 can be easily assembled from the outside in the axial direction. ,
The ease of assembly is improved, and the tapered surface 34A can be fixed to the cylinder 20 after gas is filled.
The positional accuracy when assembling the tapered sleeve 29 and the tapered sleeve 29 is improved.

Note that the guide bearing 26 may be screwed to the inner surface of the cylinder 20 as shown in FIG.

In this way, by displacing the guide bearing 26 in the axial direction, it becomes possible to adjust the starting pressure (locking pressure) depending on the purpose.

As described above, according to the present invention, it is possible to always exhibit stable operating characteristics (locking function) even under usage conditions where lateral loads are frequently applied to the piston rod, and it also prevents dust from entering the piston rod. This has the effect of being able to reliably prevent this, while also improving the ease of assembly.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional device, Fig. 2 is a sectional view showing an embodiment of the present invention, Figs. 3A and B are sectional views showing its operating state, and Figs. A cross-sectional view and a bottom view of the stop member, and FIG. 5 is a cross-sectional view of another embodiment. 20...Cylinder, 21...Piston, 24A, 2
4B... Oil chamber, 22... Piston rod, 28... Free piston, 33... Compression spring, 29... Taper sleeve, 30... Support tube, 31... Movable locking member, 35
...slit, 26...guide bearing, 34...locking ring.

Claims (1)

[Scope of Claims] 1. A piston is housed in a cylinder so that it can slide freely to partition an oil chamber, and a part of the oil chamber is filled with gas at a predetermined pressure, while the outer periphery of the piston rod and the inner periphery of the cylinder are oil-tight. An annular free piston is provided which is in sliding contact with the gas pressure, and the free piston is made to slide depending on the balance between the gas pressure and the compression spring.
Furthermore, in a gas-filled stay damper in which a movable locking member having a contractible taper sleeve is disposed around the outer circumference of the piston rod in order to move together with the free piston and restrain the movement of the piston rod when the gas pressure decreases, the movable locking member is slit. and a support cylinder for receiving one end of the compression spring, a guide bearing for the piston rod is disposed at the most distal end of the cylinder, and its inner end supports the other end of the compression spring; A gas-filled stay damper characterized in that a locking ring located between the guide bearing and the free piston and engaging with the tapered sleeve is fixed so as to enclose a compression spring and a movable locking member therein. 2. The gas-filled stay damper according to claim 1, wherein the guide bearing is screwed to the inner surface of the cylinder and is movable in the axial direction.