JPH041388Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention consists of a cylindrical cylinder filled with high-pressure gas, a piston disposed slidably in the axial direction within the cylinder, and one end of the piston. The present invention relates to a gas spring mechanism including a gas spring consisting of a piston rod that is fixed and whose other end extends outside the cylinder, and more particularly to a gas spring mechanism that includes means for detecting a decrease in the reaction force of the gas spring.

(Prior Art) A gas spring is configured to generate a reaction force by pushing a piston rod into a cylinder, and the reaction force is expressed as the cross-sectional area of the piston rod multiplied by the internal pressure of the cylinder. Since the cross-sectional area of the piston rod is small, it has the advantages of being able to obtain a small spring constant with a large initial load compared to metal springs, being small and lightweight, and being able to set the spring characteristics as desired. , widely used in various fields.

By the way, in such a gas spring, if the gas sealed in the cylinder leaks, the reaction force generated will decrease.

Such a decrease in the reaction force of the gas spring may cause the object to fall, causing a serious accident, for example, in a balance mechanism that uses the reaction force of the gas spring to support an object.

(Problems to be Solved by the Invention) Therefore, it has been proposed to detect gas leakage from the cylinder by monitoring the internal pressure of the cylinder using, for example, a pressure sensor or a pressure gauge. However, pressure sensors are expensive and impractical, and pressure gauges have the disadvantage that it is difficult to extract signals to the outside.

The present invention was developed in view of the above-mentioned problems.The purpose of this invention is to have a relatively simple structure, detect a decrease in the reaction force generated by a gas spring, and send the result to the outside. The goal is to realize a high-performance gas spring mechanism.

(Means for Solving the Problems) The present invention that achieves this object consists of a cylindrical cylinder filled with high-pressure gas, a piston disposed slidably in the axial direction within the cylinder, and one end of the piston. a gas spring consisting of a piston rod to which is fixed and whose other end extends outside the cylinder; a spring that receives the reaction force of the gas spring from the piston rod or cylinder and expands and contracts to generate an elastic force that balances the reaction force; The device is characterized by comprising a limit switch that sends out a detection signal when the internal pressure of the cylinder decreases and the amount of expansion and contraction of the spring exceeds a predetermined value.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial sectional view showing an embodiment of the present invention;
FIG. 2 is a view taken along arrow A in FIG. In these figures, reference numeral 1 denotes a cylindrical cylinder in which high pressure gas and oil are sealed, and a piston 2 is fitted inside the cylinder 1 so as to be slidable in the axial direction. The piston 2 has a communication hole 3 formed therein. Further, the other end of a piston rod 4, one end of which extends outside the cylinder 1, is fixed to the piston 2. A housing 5 supports the end of the piston rod 4 outside the cylinder so as to be movable in the axial direction. In the housing 5, between the end of the piston rod 4 and the bottom surface of the housing 5, there is a compression coil spring 6 which contracts a certain amount in response to the reaction force of the gas spring and generates an elastic force that balances the reaction force. It is arranged. 7 is a limit switch, which is attached to the outer wall of the housing 5. Reference numeral 8 denotes a lever attached to the piston rod 4 to drive the limit switch 7. When there is no gas leakage and the gas spring is generating a normal reaction force, the lever 8 is attached to the piston rod 4 and is designed to have a gap between it and the operating part of the limit switch 7. in position.

In the case of such a configured mechanism, cylinder 1
is attached to one member that moves relatively, and the housing 5 is attached to the other member that moves relatively. The operation of the above mechanism will now be explained.

First, when there is no gas leakage and the gas spring is generating a normal reaction force, the coil spring 6 is in a sufficiently compressed state in balance with this reaction force as described above, and the control section of the limit switch 7 and the lever are There is a gap between the limit switch 7 and the limit switch 8, so the limit switch 7 is not driven. On the other hand, when the reaction force of the gas spring decreases, the balance between the reaction force of the gas spring and the elastic force of the coil spring 6 at the normal compression amount is lost, and the amount of contraction of the coil spring 6 decreases. The piston rod 4 is displaced away from the housing 5. As a result, the lever 8 drives the operating section of the limit switch 7, and the limit switch 7 sends out a detection signal indicating that the reaction force of the gas spring has decreased.

With this configuration, a decrease in the reaction force of the gas spring can be detected by a combination of inexpensive parts, and the safety of the gas spring mechanism can be improved.

In the above embodiment, the compression coil spring 6 is used as the spring, but it may be a plate spring or a spiral spring, for example. Furthermore, although an example has been shown in which the limit switch is activated when the gas spring becomes abnormal, it may be configured such that it is activated when the gas spring is normal but not activated when it is abnormal. Further, in the above embodiment, an example was shown in which the abnormality detection mechanism was provided at the end of the piston rod, but it may also be provided at the end of the cylinder. Further, the limit switch is not limited to a mechanical switch, and an optical element such as a photo sensor may also be used.

(Effect of the invention) Abnormality As explained, the invention has a relatively simple configuration, and can detect a decrease in the reaction force of the gas spring and send the result to the outside.
A highly safe gas spring mechanism can be realized.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the present invention;
FIG. 2 is a view taken along arrow A in FIG. 1... Cylinder, 2... Piston, 3... Communication hole, 4... Piston rod, 5... Housing,
6...Coil spring (spring), 7...Limit switch, 8...Lever.

Claims (1)

[Claims for Utility Model Registration] A cylindrical cylinder filled with high-pressure gas, a piston disposed slidably in the axial direction within the cylinder, and one end fixed to the piston and the other end extending outside the cylinder. a gas spring consisting of an extended piston rod; a spring that expands and contracts upon receiving the reaction force of the gas spring from the piston rod or cylinder and generates an elastic force that balances the reaction force; and a spring that expands and contracts as the internal pressure of the cylinder decreases. A gas spring mechanism characterized by comprising a limit switch that sends a detection signal when the amount exceeds a predetermined value.