JPH03189433A - adjustable length gas spring - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a length-adjustable gas spring that is used in chairs, tables, etc. and whose height can be adjusted.

[Prior Art 1] Conventionally, various types of length-adjustable gas springs are known. Among them, for example, the one described in Japanese Utility Model Publication No. 55-4586 is made up of double cylinders, inside and outside, and a piston equipped with a piston rod is installed inside the inner cylinder, and the piston rod passes through the inside of the inner cylinder. It is divided into a first pressure chamber and a non-penetrating second pressure chamber, and both pressure chambers are communicated with a communication chamber formed between the inner and outer cylinders through a communication passage. By providing a valve capable of communicating or blocking the compartments in the communication path that communicates the second pressure chamber and the communication chamber, and establishing a communication state between the first pressure chamber and the second pressure chamber when the valve is open. The length of the gas spring can be adjusted.

[Problem to be Solved by the Invention 1] However, when such a conventional length-adjustable gas spring is used for a chair, etc., when adjusting its height, the above-mentioned valve is opened to apply both pressures. Since this is done by moving the piston rod in and out while the chambers are in communication, there is no problem when it is extended, but when it is shortened, the following problems occur.

In other words, since the volume of the inner and outer cylinders is constant and the gas sealed therein has a predetermined pressure, it is necessary to shorten the cylinder (by pushing the piston rod (and the amount of gas entering the piston rod). The volume will be reduced and the pressure will increase.

As a result, users who are light in weight cannot overcome the pressure caused by this pressure increase, and are ultimately unable to adjust the height.

SUMMARY OF THE INVENTION An object of the present invention is to provide a length-adjustable gas spring that solves the above-mentioned conventional problems and that can be easily adjusted by any user.

[Means for Solving the Problems 1] In order to achieve the above object, the present invention includes a piston equipped with a piston rod inside an inner cylinder, a first pressure chamber through which the piston rod penetrates, and a second pressure chamber through which the piston rod does not penetrate. In addition to the two pressure chambers, the gas spring has a first valve that can communicate with or shut off both the pressure chambers in a passage that communicates the first and second pressure chambers. A third pressure chamber is provided which communicates with one of the first and second pressure chambers through a communication path, and a second valve is provided in the communication path which can communicate or shut off communication with one of the first and second pressure chambers and the third pressure chamber. It is characterized by

[Function 1] According to the present invention, when adjusting the length, the piston rod may be moved in and out while the first and second pressure chambers are communicated with each other by the first valve as in the conventional case.

At this time, if the user is weak, if one of the first and second pressure chambers is communicated with the third pressure chamber by the second valve at the same time, the piston rod may be damaged when adjusting the shortening direction. The volume corresponding to the invasion of the first and second
It is absorbed by the third pressure chamber that is in communication with any of the pressure chambers, and the rise in gas pressure is suppressed.

Therefore, length adjustment work is easily performed.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention.

In the figure, l is an inner cylinder, and the piston 2 with the piston rod 3 passes through the first cylinder.
It is divided into a pressure chamber P and a second pressure chamber Px on the opposite side. A first outer cylinder 4 and a second outer cylinder 5 are provided concentrically in order on the outside of the inner cylinder 1, and a passage chamber Pa is provided between the inner cylinder 1 and the first outer cylinder 4.
and a third pressure chamber Ps between the first outer cylinder 4 and the second outer cylinder 5.
form. A cylindrical member 6 in which a communication passage 6A between the first pressure chamber P1 and the passage chamber P0 is formed is provided at one end of the inner cylinder 1, and outside the cylindrical member 6, a first outer cylinder 4 and a second outer cylinder 5 are further formed. A lid member 7 that closes one end is fitted. Note that the piston rod 3 passes through this lid member 7 and projects outward.

Furthermore, a lid member 8 is fitted to the other ends of the inner cylinder 1, the first outer cylinder 4, and the second outer cylinder 5 to close them, and both outer ends of the raincoat members 7 and 8 are connected to the second outer cylinder. It is caulked and fixed by the outer cylinder 5.

First and second stepped holes 9 and 10 are bored in the lid member 8 in parallel with the axis of the piston rod 3, and the first stepped hole 9
A first valve 11, which will be described later, is provided in the first stepped hole 9O, and a second valve 12 is provided in the first stepped hole 9O.

That is, the first valve 11 is for communicating or blocking the first pressure chamber P and the second pressure chamber P2, and the valve body 11A, which has an enlarged diameter part at the tip and a small diameter part in the middle, serves as the first valve 11. It is inserted into the single-stepped hole 9. The enlarged diameter portion of the valve body 11A abuts against a stopper IIB attached to the opening edge of the first stepped hole 9, and the rear end protrudes from the lid member 8. A sleeve IIc is attached to the large diameter portion of the first stepped hole 9 at a position corresponding to the small diameter portion of the valve body 11A.
Ic is provided with a radial through hole 11D. Further, facing the outer circumferential groove of the sleeve IIG, the lid member 8 has this outer circumferential groove and the aforementioned passage chamber P. A communication path 13 is provided to communicate with the.

In addition, there are O-rings II on both sides of the sleeve IIc.
E and IIE are installed to position and seal the sleeve IIc.

Next, the second valve 12 is connected to the passage chamber P. It is for communicating or blocking the first pressure chamber P and the third pressure chamber P via the three land portions 12Al.

12A, and a spool-shaped valve body 12 with 12A l.
A is inserted into the second stepped hole IO, and its rear end protrudes from the lid member 8. The lid member 8 has a first land portion 12A.
+ and the second land portion 12A, the first annular chamber 12B formed between the + and the third pressure chamber P, and the second land portion 12A and the third land portion 12.
A, a communication passage 15 is formed which communicates the second annular chamber 12B formed between the passage chambers P0 and the passage chamber P0. Note that the distance between the openings of the double-speed passages 14 and 15 to the second stepped hole 1O is smaller than the axial distance of the first annular chamber 12B+ (which is set), At this time, the two-speed passage holes 14 and 15 communicate with each other via the first annular chamber 12B+.In addition, each of the above-mentioned land portions 12Al.

On the outer periphery of t2A and 12A, there are O-rings IZcI, 12cm and HCs for sealing, respectively.
Further, a lug seal 16 is attached to the sliding portion between the piston rod 3 and the lid member 7, and a seal ring 17 is attached to each seal-required location.

In this embodiment having the above configuration, when adjusting the length of the gas spring, first the valve body 1 of the first valve 11
1A as shown in FIG.

Then, the first pressure chamber P1 is a communication passage 6A formed in the cylindrical member 6, and a passage chamber P between the inner cylinder 1 and the first outer cylinder 4. , communication path 13. Through hole LID% of sleeve IIC and valve body 11
It communicates with the second pressure chamber P2 via the small diameter portion of A. In this state where the first and second pressure chambers P1 and P2 are in communication, an external force F is applied to the piston rod 3, and the piston rod 3 is pushed in to adjust it to an arbitrary length. The reaction force acting on the piston rod 3 is equal to the volume expressed by the product of the cross-sectional area A6 and the penetration length of the piston rod 3, as shown by the characteristics in FIG.
, and increases due to a decrease in the volume of P2 (
. Therefore, if it is possible for the user to apply an external force F that overcomes this reaction force, the user can continue with the adjustment work and stop pressing down the first valve at a predetermined position, thereby increasing the pressure in both pressure chambers Pl and P8. All you have to do is block it.

By the way, in the case of a user who is unable to apply a sufficient external force F, the second valve 12 may be used as shown in FIG.
Press down. Then, the first pressure chamber P and the second pressure chamber P2
The passage chamber P0 communicates with the third pressure chamber P3 via the communication passage 15, the first annular chamber 12B+, and the communication passage 14. Even if the piston rod 3 is pushed in for the above-mentioned length adjustment in this communication state, the pressure in the first and second pressure chambers Pl and P2 will increase due to the increase in the volume of the third pressure chamber P. does not increase, and the rate of increase in reaction force is kept small, as shown by characteristic B in FIG. Therefore,
Even a user with a small weight (who can only apply a small external force F) can easily adjust the length.

In this embodiment, since the third pressure chamber P is formed between the first outer cylinder 4 and the second outer cylinder 5, that is, on the outermost side, the diameter of the second outer cylinder 5 is It is possible to secure a sufficient volume without making it that large.

[Effect of the Invention 1] As is clear from the above description, according to the present invention, a third pressure chamber is provided in addition to the first and second pressure chambers, and either one of the first and second pressure chambers and the third pressure chamber are provided. Since the second valve is provided which can communicate with or shut off the pressure chamber, it is possible to obtain a length-adjustable gas spring whose length can be easily adjusted by any user. .

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view showing the depressed (communicating) state of the first valve in the embodiment of the invention, and Fig. 3 is a sectional view of the embodiment of the invention. Pressing down the second valve (communication)
FIG. 4 is a characteristic diagram showing the relationship between the piston rod stroke and reaction force of the length-adjustable gas spring according to the embodiment of the present invention. P... Third pressure chamber, Po... Passage chamber. L... Inner cylinder, 2... Piston, 3... Piston rod, 4... First outer cylinder, 5... Second outer cylinder, 11... First valve, 12... Second valve, 13, 14.15... Communication path, Pl... First pressure chamber, P8... Second pressure chamber, gland

Claims (1)

[Claims] 1) A piston with a piston rod is housed in the inner cylinder, and the piston rod divides the piston into a first pressure chamber through which the piston rod penetrates and a second pressure chamber through which the piston rod does not penetrate, and the first and second pressure chambers communicate with each other. In a gas spring having a first valve in a passage that can communicate or shut off both pressure chambers, in addition to the two pressure chambers, a third pressure chamber is provided which communicates with either of the two pressure chambers by a communication passage, and the communication A length-adjustable gas spring characterized in that the passage is provided with a second valve that can communicate with or shut off one of the first and second pressure chambers and a third pressure chamber.