JPS629773B2 - - 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 inexpensive and provides a check valve function to a reversing spring (disc spring) provided in the piston section so as to lock the oil at the fully extended position of the piston rod. The object of the present invention is to provide a highly reliable gas spring locking device.

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 oil, 2 is a piston that separates the inside of the cylinder 1 into oil chambers A and B, and 3 is a piston 2. a piston rod having one end fixed to the cylinder and the other end protruding outside the cylinder 1;
5 is a piston rod guide provided with a sealing member;
6 is a cushion rubber that protects the rod guide portion 4 etc. from shocks when the gas spring is fully extended, and 6 is a stopper that supports the cushion rubber 5 in the vicinity of the rod guide portion 4.

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 fixed to the piston rod pilot part 3a via a valve stopper 7 with a fastening nut 8, and a spacer 9 having a smaller diameter than the piston 2 is further interposed between the piston 2 and the valve stopper 7.

Inside the piston 2, there is a spacer 9 from the oil chamber B.
a through hole 10A leading to the oil chamber A through the outer periphery of the
A plurality of through holes 10B communicating with the through hole 11 formed inside the spacer 9 and communicating with the oil chamber A are formed with opening positions shifted in the radial direction.

An annular non-return valve 12 is provided on the lower surface of the piston 2 on the through hole 10A side, and opens with almost no resistance to oil flow from oil chamber A to oil chamber B, and vice versa. The oil flow at A is designed to be blocked.

On the other hand, the non-return valve 13 is on the through hole 10B side.
is provided on the upper surface of the spacer 9, and contrary to the above, it allows oil flow from oil chamber B to oil chamber A, and A→
The oil flow at B is designed to be blocked.

A ring-shaped spring (disc spring) 14 is provided between the valve stopper 7 and the spacer 9 and can be reversed by relative movement between the cylinder 1 and the piston 2.

That is, the reversing spring 14 has a skirt-like cross section as shown in FIG. While being fixed, the outer circumferential surface 14b is formed to be slightly smaller than the inner diameter of the cylinder 1, and is configured to be turned upside down in the figure by climbing over an annular protrusion 1a formed on the inner surface of the cylinder 1.

Moreover, in order to facilitate reversal, the outer peripheral surface 14b is
As shown in FIG. 2B, the width in the radial direction is small at four locations A, B, C, and D to form relief when engaged with the inner periphery of the annular protrusion 1a of the cylinder 1.

The formation of this relief is as shown in Figure 3A.
Locations A, B, and C may be used, or the projections 1 may be formed all around the circumference as shown in FIG.
4b' may be used.

The annular protrusion 1a of the cylinder 1
Above the cushion rubber 5 (stopper 6)
It is formed by caulking etc. at a position close to the.

Then, just before the extended position of the piston rod 3, the reversing spring 14 is activated by the annular protrusion 1a.
By overcoming this, it is reversed downward in the figure, and the non-return valve 13 is set to be biased toward the closing side. In other words, in this state, the oil chamber A is locked with oil.

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),
Piston 2 and piston rod 3 as shown in Figure 4.
begins to move in the direction of extension due to the gas pressure in the gas chamber.

At this time, the hydraulic oil in the oil chamber A that contracts is transferred to the through hole 10A.
It flows to oil chamber B via. (However, since the pressure-receiving area of the lower surface of the piston is larger than the upper surface by the cross-sectional area of the rod, the piston 2 is urged upward.) When the length of the piston rod 3 protruding outward is close to its maximum length, as shown in the figure. The outer circumferential surface 14b of the reversing spring 14 that has been previously reversed upward
several places contact the annular protrusion 1a of the cylinder 1,
It is reversed downward by the stretching force caused by the gas pressure, and eventually the valve stopper 7 comes into pressure contact with the cushion rubber 5 (stopper 6) due to the load of the gas spring, and the stretching operation is completed.

In this state, the reversing spring 14 causes
The non-return valve 13, which is supposed to open freely on the rod contraction side, is energized to the closing side.

Here, if a load greater than the set load of the gas spring acts on the backdoor, the oil chamber A will be in a sealed state, so-called oil lock state, so negative pressure will be applied in response to the downward force of the piston 2 etc. (However, the load of the reversing spring 14 The following) occurs, and 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 holes 10B and 11, but the non-return valve 13 is closed by the reversing spring 14. Therefore, a force sufficient to overcome the set load of the reversing spring 14 is required, and therefore, as shown in Fig. 5B, the operating force on the retracting side near the extended position increases significantly compared to the normal stroke range. . Incidentally, FIG. 5A is an operating force diagram of a gas spring without a locking mechanism.

Therefore, in order to release this lock state,
By applying a force exceeding the maximum operating force shown in FIG. 5B from the outside, the non-return valve 13 is opened slightly upward against the reversing spring 14, so that the oil lock in the oil chamber A is disabled. It is completely released, and the piston rod 3 begins to descend.

Then, when the reversing spring 14 comes into contact with the annular protrusion 1a in the same manner as described above and is reversed upward, the oil chamber A
The oil lock is completely released, and the operating force returns to the normal stroke shown in FIG. 5B.

In this way, since the gas spring is locked by negative pressure (oil lock), its locking force is constant and does not vary depending on conditions, compared to the case of conventional mechanical means.

Further, the size of this lock can be easily selected by changing the spring force of the reversing spring 14, the pressure of the sealed gas, etc.

6A and 6B show another embodiment of the present invention, in which the reversing spring 14 and non-return valve 13 of the previous embodiment are functionally integrated, that is, the reversing spring 14 doubles as a single valve. ', and the annular protrusion 1a formed on the cylinder 1 is changed to a point-like protrusion 1a'.

According to this, the oil lock mechanism can be maintained as in the previous embodiment, and the reversing spring 14' can be made into a standard dish-shaped spring instead of having a shape with a relief as in the previous embodiment.

In addition, in the above embodiment, the piston 2 and the spacer 9
Although the piston 2 is shown as being separated, it goes without saying that the piston 2 may be formed integrally with the piston 2, for example, by forming the piston 2 into a stepped shape.

As explained above, according to the present invention, a ring-shaped spring that can be reversed by relative movement with the cylinder is provided in the piston portion, and this spring is provided with a check valve function that opens and closes the oil passage of the piston. Since the gas spring is held in place by an oil lock at the piston rod's fully extended position, it is possible to obtain more reliable and stable holding force, as well as reduce the number of parts and costs. .

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, Figs. 2A and B are sectional and front views of a reversing spring, and Figs. 3 A and B are front views of modified examples of the reversing spring. Figure 4 is a sectional view showing the operating state, Figures 5A and B are explanatory diagrams showing the relationship between the operating force and stroke of the gas spring, and Figure 6A is a diagram showing another embodiment of the present invention. The sectional view shown in FIG. 6B is a schematic sectional view taken along the - line. 1...Cylinder, 3...Piston rod, 2...
...Piston, A, B...Oil chamber, 10A, 10B,
11... Oil passage, 14... Reversing spring, 1a
...Annular protrusion.

Claims (1)

[Claims] 1. In a gas spring whose cylinder is filled with gas to constantly urge the piston rod toward the expansion side, an oil passage is formed in the piston that connects the oil chambers on both sides of the piston, and an annular spring with a skirt-shaped cross section is arranged. At the same time, a protrusion that contacts the outer peripheral surface of the spring is formed at a predetermined position on the inner surface of the cylinder, so that the spring rides over the protrusion near the piston rod extension position and reverses, thereby blocking the oil passage of the piston. A gas spring locking device characterized by the following configuration.