JPH04194718A - Differential pressure measuring device - Google Patents

Abstract

PURPOSE:To enable damage of a liquid-isolating diaphragm to be detected easily by performing operation of a single of an electrostatic capacity electrode and that of a differential pressure sensor, a static pressure sensor, and a temperature detection sensor. CONSTITUTION:When a pressure from a high-pressure side is operated, pressure which operates on a liquid-isolating diaphragm 17 is transmitted to a silicon diaphragm 8 by an enclosed liquid 101. On the other hand, when pressure is operated from a low-pressure side, pressure which is operated on the liquid- isolating diaphragm 16 is transmitted to the diaphragm 8 through an enclosed liquid 102. Therefore, according to a pressure difference between the high- pressure side and the low-pressure side, the diaphragm 8 is distorted and an amount of distortion is taken out electrically by a strain gauge 9, thus enabling the differential pressure to be measured. Then, the electrostatic capacity electrode, the differential pressure sensor, the static-pressure detection sensor, and the temperature detection sensor are provided and operation is performed by a circuit which performs operation of signals of the differential pressure sensor, electrostatic detection sensor, and temperature detection sensor, thus enabling damage of the diaphragms 16 and 17 to be known.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention provides a method for measuring differential pressure that can easily detect a breakage of a liquid diaphragm that causes an outflow of the enclosed liquid or an inflow of the measured fluid into the enclosed liquid. It is related to the device.

<Prior Art> FIG. 3 is an explanatory diagram of the configuration of a conventional example that has been commonly used in the past, and is shown in, for example, Japanese Utility Model Application No. 181642/1983.

In the figure, reference numeral 1 denotes a housing, which is composed of a cylindrical neck IA and a block-shaped pressure receiving part IB welded and connected at an end outer peripheral edge IC of the neck IA.

A high pressure side flange 2 and a low pressure side flange 3 are fixed to both sides of the housing 1 by welding or the like.
3 is an inlet 4 for high-pressure fluid at the pressure PH to be measured;
An inlet 5 for low-pressure fluid having a pressure PL is provided.

A pressure measurement chamber 6 is formed within the housing 1, and a center diaphragm 7 and a silicon diaphragm 8 are provided within the pressure measurement chamber 6.

The center diaphragm 7 and the silicon diaphragm 8 are each separately fixed to the wall of the pressure measurement chamber 6, and both the center diaphragm 7 and the silicon diaphragm 8 divide the pressure measurement chamber 6 into two.

Back plates 6A and 6B are formed on the wall of the pressure measurement chamber 6 facing the center diaphragm 7.

The center diaphragm 7 is welded to the housing 1 at its peripheral edge.

The silicon diaphragm 8 is entirely formed from a single-crystal silicon substrate.

Four strain gauges 9 are formed by selectively diffusing impurities such as boron on one side of the silicon substrate, and the other side is machined, etched, and a concave diaphragm is formed as a whole.

The four strain gauges 9 are silicon diaphragms 8
When deflected under the differential pressure ΔP, two are in tension and two are in compression, and these are connected to a Wheatstone bridge circuit, and the change in resistance is detected as a change in the differential pressure ΔP.

A silicon diaphragm 8 divides the neck IA into two sensor chambers 11.12.

A silicon diaphragm 8 is adhesively fixed to the end surface of the support 13 on the side of the pressure measurement chamber 6 by a method such as low melting point glass connection.

A pressure introduction chamber 14.15 is formed between the housing 1, the high pressure side flange 2, and the low pressure side flange 3.

A liquid separation diaphragm 16,
A liquid separation diaphragm 16 is provided at t18 and 19 of the housing 1 facing the liquid separation diaphragm 16 and 17.
, 17 is formed with a back plate having a similar shape.

Liquid diaphragm 16, 17 and back plate 18.1
9 and the pressure measurement chamber 6 are connected to the communication hole 21
．． It is electrically connected via 22.

A sealing liquid 101, 102 such as silicone oil is filled between the liquid partition diaphragms 16, 17, and this sealing liquid reaches the upper and lower surfaces of the silicone diaphragm 8 through the communication holes 21, 22.

The sealed liquids 101 and 102 are divided into two by the center diaphragm 7 and the silicon diaphragm 8, and care is taken so that the amounts thereof are approximately equal.

In the above configuration, if pressure is applied from the high pressure side,
The pressure acting on the liquid diaphragm 16 is transmitted to the silicon diaphragm 8 by the sealed liquid 101.

On the other hand, when pressure is applied from the low pressure side, the pressure acting on the liquid partition diaphragm 17 is transmitted to the silicon diaphragm 8 by the sealed liquid 102.

As a result, the silicon diaphragm 8 is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and the amount of this distortion is electrically taken out by the strain gauge 9, and the differential pressure is measured.

<Problems to be Solved by the Invention> However, in such devices, the liquid separation diaphragms 16 and 17 are constantly in contact with the measuring fluid during use, so they are susceptible to corrosion, oxidation, and fatigue, and are not used for long periods of time. If you continue to use it, a hole will form in the deteriorated part, and the measured fluid may flow into the sealed liquid 101, 102 or the filled liquid 101, 102
may leak into the measurement fluid.

In order to solve these problems, improvements have been made in the selection of component materials, the method of joining parts, etc., but there is still no structure that is completely reliable against such problems. Not put into practical use.

Therefore, in the unlikely event that such a problem occurs, a function is required to promptly detect damage to the liquid separating diaphragm.

The present invention solves this problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a differential pressure measuring device that can easily detect a breakage of a liquid diaphragm that causes an outflow of a sealed liquid or an inflow of a measurement fluid into a sealed liquid.

Means for Solving the Problem> To achieve this object, the present invention provides a housing;
A differential pressure measuring device comprising: two liquid partition diaphragms provided on both sides of the housing and respectively forming partition chambers with the housing; and a differential pressure detection section for detecting a differential pressure between the two liquid partition chambers. an electrode provided on the body opposite to the liquid diaphragm and forming a capacitance electrode with the liquid diaphragm to detect displacement of the liquid diaphragm;
A static pressure detection sensor provided in the housing to detect static pressure, a temperature detection sensor provided in the housing to detect temperature, a signal of the capacitance electrode, a differential pressure sensor, a static pressure detection sensor, and a temperature detection sensor. and an arithmetic circuit for detecting damage to the separating liquid diaphragm by calculating the signal and the signal.

In the above configuration, when pressure is applied from the high pressure side,
The pressure acting on the liquid diaphragm is transmitted to the silicone tire diaphragm by the filling liquid, while if the pressure is applied from the low pressure side, the pressure acting on the liquid diaphragm is transmitted to the silicon diaphragm by the filling liquid.

Therefore, the silicon diaphragm is distorted depending on the pressure difference between the high pressure side and the low pressure side, and the amount of this distortion is electrically extracted by a strain gauge to measure the pressure difference.

Thus, a capacitance electrode, a differential pressure sensor, a static pressure detection sensor, and a temperature detection sensor are provided, and the capacitance 11 is connected to a pole signal, and a signal from the differential pressure sensor, static pressure detection sensor, and temperature detection sensor is provided. Since an arithmetic circuit is provided which calculates and detects damage to the liquid diaphragm, damage to the liquid diaphragm can be detected.

Hereinafter, a detailed explanation will be given based on examples.

<Embodiment> FIG. 1 is an explanatory diagram of the main part configuration of an embodiment of the present invention, and FIG. 2 is a detailed diagram of the main part of FIG. 1.

In the figure, structures with the same symbols as in FIG. 3 represent the same functions.

Hereinafter, only the differences from FIG. 3 will be explained.

31 is provided in the housing 1 opposite to the liquid diaphragm 17, as shown in FIG.
This is an electrode that constitutes a capacitance electrode and detects the displacement of the liquid partition tyrephragm 17.

The electrode 31 is provided on the housing 1 with a dielectric sealing material 32 interposed therebetween.

33 is a static pressure detection sensor provided in the housing 1 to detect static pressure.

34 is a temperature detection sensor provided in the housing 1 to detect temperature.

In this case, the static pressure detection sensor 33 and the temperature detection sensor 34 are provided on the silicon diaphragm 8, and semiconductor pressure/temperature sensing elements are used.

35 is a calculation circuit (not shown) that calculates the signals of the capacitance electrode, the differential pressure sensor 9, the static pressure detection sensor 33, and the temperature detection sensor 34 to detect damage to the liquid diaphragm. be.

In the above configuration, if pressure is applied from the high pressure side,
The pressure acting on the liquid diaphragm 16 is transmitted to the silicon diaphragm 8 by the sealed liquid 101.

On the other hand, when pressure is applied from the low pressure side, the pressure acting on the liquid separating diaphragm 17 is transmitted to the silicon diaphragm 8 by the sealed liquid 102.

Therefore, the silicon diaphragm 8 is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and the amount of this distortion is electrically extracted by the strain gauge 9 to measure the pressure difference.

Thus, a capacitance electrode, a differential pressure sensor, a static pressure detection sensor, and a temperature detection sensor are provided, and the signal of the capacitance electrode, the signal of the differential pressure sensor, the static pressure detection sensor, and the temperature detection sensor is Since an arithmetic circuit is provided which calculates and detects damage to the liquid diaphragm, damage to the liquid diaphragm can be detected.

As a result, even if the liquid separation diaphragms 16 and 17 are damaged and liquid leakage occurs, the abnormality can be quickly detected, making it possible to prevent accidents in plants and the like.

In addition, in the above-mentioned embodiment, the static pressure detection sensor 33,
Although the temperature detection sensor 34 has been described as being provided on the silicon diaphragm 8, it is not limited thereto, and in short, it may be provided at a location where static pressure and temperature can be detected.

<Effects of the Invention> As explained above, the present invention includes a housing, two liquid partition diaphragms provided on both sides of the housing and forming separate liquid chambers with the housing, and the two liquid partition diaphragms. A differential pressure measuring device comprising a differential pressure detection unit for detecting a differential pressure in a chamber, wherein the liquid diaphragm is provided in the body opposite to the liquid diaphragm and forms a capacitance electrode with the liquid diaphragm. an electrode that detects displacement of the housing; a static pressure detection sensor that is provided on the housing and detects static pressure;
Damage to the liquid diaphragm is detected by calculating a temperature detection sensor provided in the housing to detect temperature, a signal from the capacitance electrode, a differential pressure sensor, a static pressure detection sensor, and a temperature detection sensor. A differential pressure measuring device has been constructed, which is characterized by comprising an arithmetic circuit that performs the following steps.

As a result, even in the unlikely event that the liquid diaphragm is damaged and liquid leaks, the abnormality can be quickly detected, making it possible to prevent accidents in plants, etc.

Therefore, according to the present invention, it is possible to realize a differential pressure measuring device that can easily detect damage to the liquid separation diaphragm that causes outflow of the sealed liquid or inflow of the measurement fluid into the sealed liquid.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main part of an embodiment of the present invention, FIG. 2 is a detailed diagram of the main part of FIG. 1, and FIG. 3 is an explanatory diagram of the construction of a conventional example commonly used. 1...Housing, 2...High pressure side flange, 3...
・Low pressure side flange, 4.5...Inlet, 6...Pressure measurement chamber, 6A, 6B, 18.19...Back plate, 7...Center diaphragm, 8...Silicon diaphragm, 9 ...Strain gauge, 11.12...
・Sensor chamber, 13...Support, 14.15...Pressure introduction chamber, 16°17...Liquid diaphragm, 21.2
2... Communication hole, 31... Electrode, 32... Dielectric sealing material, 33... Static pressure detection sensor, 34... Temperature detection sensor. A□ Agent: Patent Attorney Nobusuke Ozawa No. 2 @

Claims (1)

[Scope of Claims] A housing; two liquid separation diaphragms provided on both sides of the housing and forming separate liquid chambers with the housing; and differential pressure detection for detecting a differential pressure between the two liquid chambers. A differential pressure measuring device comprising: an electrode provided on the body opposite to the liquid diaphragm and forming a capacitance electrode with the liquid diaphragm to detect displacement of the liquid diaphragm, and the housing. a static pressure detection sensor provided in the housing to detect static pressure; a temperature detection sensor provided in the housing to detect temperature; a signal of the capacitance electrode, a differential pressure sensor, a static pressure detection sensor, and a temperature detection sensor; 1. A differential pressure measuring device, comprising: a calculation circuit that calculates a signal and detects damage to the liquid separation diaphragm.