JPS58833Y2 - Electronic differential pressure transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an electronic differential pressure transmitter that measures the difference in pressure introduced through a pair of pressure receiving elements by converting it into a change in capacitance.

FIG. 1 is a longitudinal sectional view showing the conventional structure of a differential pressure transmitter that converts the difference in pressure received by a pair of pressure receiving elements into capacitance and measures it.

That is, a cylindrical hollow chamber is formed inside the main body 1 of the differential pressure transmitter, and a pair of pressure receiving elements 2a and 2b are fixed to the outside thereof.

Further, in the main body 1, a diaphragm 3 made of a conductive elastic material is fixed at the peripheral edge of the hollow chamber, and this diaphragm separates the hollow chamber into two pressure receiving chambers 4a and 4b. .

On both sides of the diaphragm 3, there are fixed members 6a, 6 made of an insulator, the surfaces facing the diaphragm are machined into a concave shape, and foil-shaped fixed electrodes 5a, 5b are formed on the surfaces.
b are arranged in the pressure receiving chambers 4 a and 4 b, respectively.

Furthermore, a through hole 7a is provided in the main body and the fixing member. 7b is formed, and a pressure transmission path from the pressure receiving element to the pressure receiving chamber is filled with a sealed liquid.

With this configuration, this differential pressure transmitter has a pressure receiving element 2 a
, 2b is guided to pressure receiving chambers 4a, 4b, and the diaphragm 3 is distorted according to the pressure difference, which is converted into a change in capacitance between the diaphragm 3 and the fixed electrodes 5a, 5b. Ru.

This change in capacitance makes it possible to measure the difference in pressure applied to the pressure receiving element.

However, since this capacitance change is proportional to the integral value of the displacement due to distortion of the fixed electrodes 5a, 5b and the diaphragm 3, there is a drawback that the effect on capacitance changes near the outer periphery is not sufficiently expressed. Ta.

The purpose of this invention is to realize a differential pressure transmitter with a configuration that effectively converts the displacement of the diaphragm into capacitance, in other words, a differential pressure transmitter with a configuration that increases the capacitance change per unit area of the diaphragm. be.

Another object of the present invention is to realize a differential pressure transmitter having a structure that also has a diaphragm protection mechanism when a pressure difference exceeding a measurement range is received.

An embodiment of the present invention will be described below based on the longitudinal cross-sectional view of FIG.

Reference numeral 11 denotes a main body of a differential pressure transmitter, on the outside of which a pair of pressure receiving elements 12a and 12b are fixed, and inside thereof a cylindrical hollow chamber is formed.

A notch groove 19 having a substantially V-shaped cross section is formed in the central inner circumferential wall of this hollow chamber, and the peripheral edge of a diaphragm 13 made of a piece of conductive elastic material is fixed at the bottom of this notch groove. ing.

Due to this diaphragm 13, the hollow chamber is divided into two pressure receiving chambers 14.
The diaphragm 13 is separated into two electrodes 18a and 14b, and on both sides of the diaphragm 13 are attached disk-shaped moving electrodes 18a and 18b made of a conductive material.

One surface of the movable electrodes 18a, 18b is a circular plane, and a surface parallel to the one surface and attached to the diaphragm 13 is formed near the center on the back surface of the movable electrodes 18a, 18b.
The periphery of each surface is processed into a flared curved surface.

Further, in the pressure receiving chambers 14 a and 14 b, there are fixed members 16 whose surfaces facing the movable electrodes are flat, and foil-shaped fixed electrodes 15 a and 15 b are formed on the flat surfaces.
a and 16b are arranged to face each other parallel to the surface of the moving electrode.

Furthermore, through holes 17a and 17b are formed in the main body 11 and the fixing members 16a and 16b, and a pressure transmission path from the pressure receiving element to the pressure receiving chamber is filled with a sealed liquid.

With this configuration, the pressure received by the pressure receiving elements 12 a and 12 b is guided to the pressure receiving chambers 14 a and 14 b, and the diaphragm 13 is distorted according to the pressure difference, and the moving electrode 18
a.

18b also moves.

At this time, since the mounting side back surfaces of the moving electrodes 18 a and 18 b have curved surfaces processed into a flared shape as described above,
The diaphragm 13 and the movable electrodes 18 a and 18 b move without touching each other.

Furthermore, if the pressure difference exceeds the measurement range, one of the movable electrodes should be corresponds to the fixed electrode.

The diaphragm is distorted along one surface of the V-shaped notch groove 19 formed in the peripheral wall of the hollow chamber and along the flared curved surface of one of the movable electrodes.

In this way distortion of the diaphragm 13 is limited and damage to the diaphragm due to excessive pressure differentials is protected.

Furthermore, the fixed electrodes 15a, 15b and the moving electrode 18
Since the opposing surfaces of a and 18b are parallel to each other, it is possible to increase the change in capacitance in response to minute movements of the diaphragm, making it possible to measure the pressure difference with high precision. .

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a conventional electronic differential pressure transmitter, Fig. 2 is a longitudinal sectional view of an electronic differential pressure transmitter according to the present invention-embodiment, and Fig. 3 is a longitudinal sectional view of an electronic differential pressure transmitter according to the present invention. A vertical cross-sectional view is shown when a pressure difference exceeding the measurement range of the pressure transmitter is applied. 11: Main body, 13: Diaphragm, 15a, 15b: Fixed electrode, 18a, 18b: Moving electrode, 19: ■-shaped notch groove.

Claims (1)

[Scope of utility model registration request] An electronic differential pressure transmitter that converts and measures the difference in pressure guided through a pair of pressure receiving elements into a change in capacitance, includes a main body having a cylindrical hollow chamber, and a central inner peripheral wall of the hollow chamber. A diaphragm made of a conductive elastic body whose peripheral edge is fixed to the bottom of the notched groove and separates the hollow chamber into two pressure-receiving chambers; A pair of through holes formed in the main body to guide the pressure into the pressure receiving chamber, conductive disk-shaped movable electrodes attached to both sides of the diaphragm and each having a flared back surface on the mounting side, and these movable electrodes. An electronic differential pressure transmitter comprising a pair of conductive fixed electrodes disposed in the pressure receiving chamber facing each other on the surface thereof, and a sealed liquid filled in a pressure transmission path from the pressure receiving element to the pressure receiving chamber.