JPS5858521B2 - Piston backlash accumulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston-type accumulator that facilitates the detection of gas leaks.

The interior of the cylinder is divided into an oil chamber and a gas chamber by a floating piston that moves freely within the cylinder, and this gas chamber is filled with, for example, nitrogen gas, and pressure oil from a hydraulic circuit is introduced into the oil chamber. is known as a so-called piston type accumulator.

By the way, due to the nature of the gas in this accumulator, a small amount of leakage cannot be avoided, and if the amount of leakage exceeds a certain limit, the pressure accumulation function required in the hydraulic circuit in which this accumulator is used cannot be satisfied.

The basic method of detecting this gas leak is to remove the pressure oil from the accumulator, expand the gas to the full cylinder capacity, and compare the gas pressure in this state with the pressure when the gas was initially filled. However, in order to do so, the hydraulic circuit must be stopped.

Pressure oil is introduced into the residue 1. In order to detect gas leaks, when gas leaks and the amount of gas in the accumulator decreases, the piston position under a constant oil pressure (this is equal to the gas pressure) shifts to the gas side. Therefore, it is desirable to detect gas leaks based on changes in the piston position, but as a solution to this, it is possible to provide a shaft that indicates the piston position and pull it out of the cylinder from the gas chamber through the shaft seal. On the contrary, the chances of gas leakage increase and the structure is not good.

This is because the shaft seal portion tends to wear out the packing as the shaft slides.

In order to avoid this drawback, there is a method of indirectly detecting the piston position, in which when the amount of gas in the accumulator decreases, the volume in the adjacent oil chamber increases and the amount of oil fed by the pump also increases, so the pressure remains constant. Methods of detecting gas leaks based on the operating time of the pump or the degree of drop in the oil level in the oil storage tank at a constant pressure have also been adopted, but there are complaints that the detection accuracy is not good.

This invention was made under these circumstances, and it is possible to achieve high accuracy by mechanically capturing the position of the floating piston during operation toward a constant pressure in the hydraulic circuit with simple interception that does not require a shaft seal. It is an object of the present invention to provide a piston-type accumulator with means for detecting gas leakage.

The present invention will be explained below with reference to illustrated embodiments.

In the figure, an accumulator 1 consists of a cylindrical cylinder 2 and a floating piston 3, and the piston 3 is designed to be able to move freely within the cylinder while dividing the cylinder interior into an oil chamber 4 and a gas chamber 5. It is fitted and fitted into the cylinder.

Pressure oil is introduced into the oil chamber 4 through a pipe 6 connected to a hydraulic circuit (not shown), and the gas chamber 5 is filled with nitrogen gas, for example.

A gasket 7 is attached to the outer periphery of the piston 3 to provide a seal between the chambers 4 and 5.

Based on the present invention, a rod 8 is attached to the gas chamber 5 side of the piston 3 on the axial center line of the piston 3, and a stop valve 9 is provided on the end wall of the cylinder on the gas chamber 5 side.

The length of the rod 8 is selected so that the rod 8 does not touch the end face of the valve body 10 of the stop valve 9 while the gas amount is normal.

The valve body 10 of the stop valve 9 is biased by a spring 11 and is sealed against the gas chamber 5 by a packing 12 unless pressed by the rod 8.

A hole 13 is bored in the valve body 10 to allow gas to flow when the rod 8 presses the valve body 10 .

Note that the smaller the diameter of the rod 8 and the seal diameter of the packing 12, the more compact the entire structure can be.

A pressure switch 14 is provided outside the accurator, and a cylinder 15 in the pressure switch 14 is provided.
is connected to the stop valve 9 by a gas flow conduit 16, and the piston 17 is moved by the gas flow.

This movement of the piston 17 opens and closes a contact 19 connected to an alarm circuit having an alarm 18.

It is assumed that when the oil pressure in the housing and oil chamber 4 is at the normal working pressure and the gas chamber 5 is filled with a specified amount of gas, the piston 3 is located near the position shown in the figure.

At this time, the tip of the rod 8 attached to the piston 3 does not touch the end face of the valve body 10, so gas does not flow into the pressure switch 14 from the stop valve 9 and the pressure switch 1
Contact point 19 of No. 4 is in an open state.

Now, as the gas in the gas chamber 5 leaks into the oil chamber 4 or outside, the piston 3 moves toward the gas chamber 5 under constant hydraulic pressure.

When the amount of gas in the gas chamber 5 decreases to a certain value 1, the tip of the rod 8 hits the end face of the valve body 10, and if gas leakage continues, the valve body 10 opens under pressure from the rod 8.

Therefore, the gas in the gas chamber 5 flows into the cylinder 15 through the hole 13 and the pipe line 16, and the piston 17 moves to the contact point 1.
Move in the direction of 9.

As a result, the contact 19 closes and the alarm 18 issues an alarm.

In place of or in addition to the alarm in the above-described embodiments, a locking device that can stop the oil supply to the accumulator by operating a pressure switch may be used.

As described above, the present invention provides a stop valve on the end wall of the cylinder on the gas chamber side that is pressed by the piston via the rod and opens when the piston advances beyond a certain level toward the gas chamber, and the flow of water flows through the stop valve. The pressure switch is equipped with a pressure switch whose contacts are operated by the gas being released.Although the configuration is simple, it can be detected at any time during the operation of the hydraulic circuit, and gas leaks can be detected mechanically based on the position of the piston. The detection accuracy is also high.

Further, according to the configuration based on the present invention, the stop valve and the pressure switch can be connected in a gas-tight manner to the outside.

In this case, there is an advantage that even if a gas leak should occur in the gasket of the stop valve, it will be detected by this detection device.

Another advantage is that the pressure switch, which is a detection element, can be provided at any location away from the accumulator, such as in a control box.

[Brief explanation of drawings]

The figure is a sectional view showing a schematic configuration of an accumulator according to the present invention together with a pressure switch. 1...Accumulator, 2...Cylinder, 3...
Floating piston, 4... gas chamber, 5... oil chamber, 8...
・Rod, 9...Stop valve, 14...Pressure switch.

Claims (1)

[Claims] 1 The interior of the cylinder is divided into an oil chamber and a gas chamber by a floating piston that moves freely within the cylinder, gas is sealed in this gas chamber, and pressurized oil is introduced into the oil chamber. , a stop valve is provided on the end wall of the cylinder on the gas chamber side, which opens when the floating piston moves beyond a certain level toward the gas chamber by being pressed by the piston via a link provided in the gas chamber; A piston-type accumulator characterized by guiding gas flowing out through the pressure switch to a pressure switch.