JPS63293301A - Piston type accumulator - Google Patents

Abstract

PURPOSE:To accurately detect a gas leak in the case of any change in the ambient temperature by detecting the amount of gas leak on the basis of the position of a piston in a cylinder and the temperature in the vicinity of the cylinder. CONSTITUTION:A position detector 13 composed of a coil spring 14, a stress detector 15 as a physical amount detector, and a position computing unit 16 is provided in a cylinder 2. A temperature detector 19 is provided in the vicinity of the cylinder 2, while a pressure detector 18 is connected to a hydraulic pressure line, then outputs from respective detectors 13, 18, 19 are input to a computing unit 20. The position of a piston 3 under no gas leak is computed on the basis of the detected temperature and pressure values in the computing unit 20, and the amount of gas leak is then detected after comparing this computed value with an output from the position detector 13. Even if the ambient atmospheric temperature varies, the amount of gas leak can be accurately detected in this manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a piston-type accumulator (pressure accumulator) equipped with a gas leak detection function.

[Conventional technology]

FIG. 3 is a sectional view showing the structure of a conventional piston-type accumulator equipped with a gas leak detection function, as disclosed in, for example, Japanese Patent Publication No. 54-33366. In the figure, (1
) is a piston-shaped accumulator, 012) is a cylindrical cylinder with both ends closed, and (3) is a cylinder (2) whose inner chamber is divided into an oil chamber (4) and a gas chamber (5). The piston is fitted into the cylinder (2) so that it can move freely within the cylinder (2). (6) is a hydraulic pipe line, into which pressure oil is introduced from a hydraulic circuit (not shown). For example, nitrogen gas is sealed in the gas chamber (5). (7) is a bisto cylinder, which is attached to the outer periphery of the piston (3) and seals between the oil chamber (4) and the gas chamber (5). O (8) is a cylindrical stopper; ) is provided along the inner wall and limits the movement of the piston (3). (9).

(kl)! -! : Pressure switches for outputting the EE force 46 are connected to the oil chamber (4) and the gas chamber (5), respectively. αD is a control circuit that generates a gas leak alarm upon receiving the signal from the pressure switch (9) and αl. This system stores high-pressure oil in the cylinder and supplies it to the hydraulic circuit (not shown) through the pipe line (6) as needed. , the piston (3) is in the position (3) shown by the solid line in the figure. Now, assuming that the pressure in the oil chamber (4) is Pls and the pressure in the gas chamber (5) is P2, when the piston (3) does not hit the stopper (8) and can move freely, the pressure is p1 = p2. . At this time, both the pressure switch (9) and α1 do not operate because the detected pressure is equal to the set pressure value.Now, when the gas in the gas chamber (5) leaks, the piston (3) moves in the direction of the arrow υ. While moving 0, p1=P2 is always satisfied. When the amount of gas leakage reaches a certain value, the piston (3) moves to position (3A) lit indicated by the broken line in the figure, and the stopper (
8). Until this moment, Pl=P3, but if the gas leak continues, the piston (3) cannot move any further, and the pressure balance collapses and Pi>P2. As a result, the detected pressure deviates from the set pressure value, the pressure switch (11) is activated, and by supplying this signal to the control circuit (b), the control circuit (b) detects the limit amount for gas leakage. The stopper (8) is positioned so that it will come into contact with the piston (3) when the gas leak reaches the limit amount.

[Problem that the invention seeks to solve]

In a conventional piston-type accumulator like the one above,
When the gas in the gas chamber (5) expands due to an increase in ambient temperature, the piston (3) moves to the position (3) in the figure, for example!
Move to position 6 (3B). Therefore, at this time, the amount of gas leaking at the point a (3A) t when gas leaks occurs and the piston (3) hits the stopper (8) is the gas leak limit amount that should be detected before the ambient temperature rises. will exceed the value of On the other hand, if the ambient temperature is low, the piston (3) will quickly hit the stopper (81r) even if the gas leakage limit amount to be detected has not been reached, causing an unnecessary gas leakage alarm to be issued. As described above, since the conventional piston-type accumulator (1) uses a stopper (8) whose length does not change, there was a problem that gas leakage could not be detected correctly depending on changes in the ambient temperature. .

This invention was made to solve one of the above problems, and the object is to obtain a piston-type accumulator that can detect gas leakage even if the surrounding wet layer changes.

[Failure to solve the problem]

The piston type accumulator according to the present invention includes a pressure detector for detecting the pressure inside the cylinder, a temperature detector for detecting the temperature near the cylinder, a position detector for detecting the position of the piston in the cylinder, and each of the above-mentioned components. This system is equipped with a calculation device that outputs the amount of gas leakage from the output of the detector.

(Operation) In this invention, the position detector detects the position of the piston in the cylinder and outputs it to the calculation device, and the pressure detector and the temperature detector detect the pressure and temperature in the cylinder, respectively, and output it to the calculation device. The calculation device calculates the position of the piston in a state without gas leakage from the detected temperature and pressure values, compares this value with the value output from the position detector, Detects the amount of gas leakage.

〔Example〕

FIG. 1 is a cross-sectional view showing the structure of a piston-type accumulator tl) showing an embodiment of the present invention, and shows (1) to (
7), 03 is the same as the conventional device, o/13 is a position detector for the piston (3), a coil spring Q→ which is held by an elastic body, and a stress detector a and a physical quantity detector. A zero coil spring Q4) consisting of a position calculation device αe is installed in the gas chamber (5) and is connected to the piston (3), and expands and contracts with the movement of the piston (3).
) causes a stress change depending on the displacement. Stress detector (g)
A coil spring (b) is also installed inside the gas chamber (5).
The stress generated by the coil spring α rod is detected. The detected stress signal is sent to the position calculation device αQ via the sealed terminal αη. The position calculation device αQ is installed outside the cylinder (2) and calculates the position of the piston (3) based on the stress signal. The length of the coil spring a4 is such that the stress detector (to) continuously detects the coil spring α in the entire movement range of the piston (3) corresponding to the entire temperature and pressure range assumed during operation of the hydraulic circuit (not shown). →
Set so that the stress can be detected. (G) is a pressure detector that is connected to the oil chamber (4) via the hydraulic pipe line (6) and measures the pressure inside the oil chamber (4). Q9 is a temperature detector placed near the cylinder (2) and measures the temperature around the cylinder (2).0 (1) is a calculation device installed outside the cylinder (2), including a position calculation device fQG,
The piston type accumulator configured as above (
In 1), if gas leaks from the gas chamber (5),
The piston (3) moves in the direction of the arrow @, and the coil spring α
◆ is compressed to generate compressive stress in the coil spring α→ according to the displacement of the piston (3). The stress detector (to) continuously detects this stress and sends a detection signal to the position calculation device α. For example, the position calculation device αQ compares the value of the detection signal with the value in the comparison table based on a stress-displacement comparison table created in advance, and continuously calculates the displacement of the piston (3) and therefore the current position. is detected and output to the arithmetic unit W (e). The stress detector (c) is set to detect only the stress generated in the coil spring Q→, without being affected by pressure changes within the gas chamber (5). The computing device, on the other hand, receives continuous output signals from the pressure detector (to) and the temperature detector Q'J, and learns the temperature and pressure inside the cylinder (2). From these values, the position of the piston (3) in a state where there is no gas leakage is continuously calculated, and by comparing the calculated value with the value of the output position signal of the position calculation device αQ, the position of the piston (3) is continuously calculated. Then, calculate the amount of gas leakage at that point. Therefore, even if the ambient temperature of the cylinder (2) changes and the position of the piston (3) changes, the amount of gas leakage can be accurately and continuously detected.

In the above embodiment, the coil spring α◆, which is an elastic body constituting the position detector (to), and the stress detector (to), which is a physical quantity detector, were placed in the gas chamber (5). may be provided in the oil chamber (4). FIG. 2 is a cross-sectional view showing the structure of the piston-type accumulator (1) in the case of a cylindrical case. In the case of this embodiment, when a gas leak occurs in the gas pipe (5), the piston (3) moves in the direction of the arrow (to), the coil spring Q4J stretches, and is detected by the stress detector (2). The rest is the same as in the embodiment of FIG. 1, with the only difference being that the stress is reduced.

In addition, in the embodiments shown in Figs. 1 and 2, the stress of the coil spring α◆ is detected by a stress detector (to) that is provided separately from the spring (b), but a strain gauge or the like is not connected to the spring (b). ) It is also possible to detect stress by directly attaching it to the surface. or,
It is also possible to use a rod-shaped resin or the like as the elastic body instead of the coil spring (b).

Further, although the stress detector (g) is used as the physical quantity detector constituting the position detector α frame of the piston (3), it may be a book that detects physical quantities other than stress.

For example, it may be possible to measure the amount of electromagnetism generated and changed depending on the displacement of the expandable body, the generated sound, etc.

Furthermore, as a position detector (to), an electromagnetic wave such as X-rays is irradiated from outside the cylinder (2) to obtain a transmitted image of the piston (3), without using the expandable body α→ etc. (3) may be used to detect the position, or a similar effect may be achieved by using a transparent cylinder (2) and a scale.

〔Effect of the invention〕

As explained above, the present invention includes a pressure detector for detecting the pressure inside the cylinder, a temperature detector for detecting the temperature near the cylinder, a position detector for detecting the position of the piston in the cylinder, and the above-mentioned pressure detector. and an arithmetic device that receives the output of the temperature sensor, calculates the position of the piston in a state with no gas leakage, and compares the calculated value with the output signal of the position sensor, so that the ambient temperature is Even if the amount changes, the amount of dust leakage can be accurately detected.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a piston-type accumulator according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the structure of another embodiment, and FIG. 3 is a cross-sectional view showing the structure of a conventional device. It is a diagram. In the figure, (1) is the accumulator, (2) is the cylinder, (3) is the piston, (4) is the oil chamber, (5) is the gas chamber, 0 is the position detector, (to) is the pressure detector u, Q9 is a temperature detector, and the handle is a calculation! [1 is shown. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A piston that moves freely within the cylinder and divides the cylinder into a gas chamber and an oil chamber, a pressure detector that detects the pressure inside the cylinder, and a temperature sensor that detects the temperature near the cylinder. and a position detector that detects the position of the piston, and calculates the position of the piston without gas leakage from the output signals of the pressure detector and temperature sensor, and the calculated position signal and the position detector A piston-type accumulator characterized by comprising an arithmetic device that compares the output signal with the output signal of the piston-type accumulator. (2) The position detector detects a telescoping body that expands and contracts according to the movement of the piston and a physical quantity according to the displacement of this telescoping body,
The piston type accumulator according to claim 1, further comprising a physical quantity detector for calculating the position of the piston. (3) Claim 2, characterized in that the physical quantity detector measures changes in stress occurring in the expandable body.
Piston type accumulator as described in section.