JPH01142428A - Electrostatic type differential pressure measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a compact electrostatic capacitor type differential pressure measuring apparatus characterized by small hysteresis, by providing a symmetrical structure for the entire constitution, making the volume of a center diaphragm small, and reducing sealed liquid. CONSTITUTION:When the differential pressure between measured pressures P1 and P2 is within a specified measuring range, a measuring diaphragm 63 is displaced in correspondence with the differential pressure through sealed liquids 101, 102 and 103 when sealed diaphragms 31 and 32 receive measuring pressure. Therefore, the electrostatic capacitance between the measuring diaphragm 63 and the fixed electrode 64 is changed. Thus, an electric signal corresponding to the differential pressure of the measured pressures is obtained. The pressure of a central diaphragm chamber 13 becomes a pressure equal to about (P1+P2)/2. Therefore, the differential pressure of (P1-P2)/2 is applied to central diaphragms 11 and 12. The measured pressure P1 is applied to a measuring chamber 631, and the measured pressure P2 is applied to a measuring chamber 632. The pressure of (P1+P2)/2 is applied to an inner cavity 51. Therefore, static pressure is not applied to a disk 61 and a ring 62. Only 1/2 of the differential pressure between the measured pressures P1 and P2 is applied, therefore, there exists no static pressure span shift due to deformation.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a capacitive layer differential pressure measuring device.

More specifically, the present invention relates to a capacitive layer differential pressure measuring device that can be miniaturized without causing changes in the span of measured pressure due to static pressure.

<Prior Art> FIG. 6 is a diagram illustrating the configuration of a conventional example that has been commonly used.

In the figure, this device mainly includes a differential pressure sensing section 10a,
First cover flange lla and second cover flange 12
It is composed of a.

First cover flange lla and second cover flange 12
a are the first pressure chamber 15a and the second pressure chamber 16a, respectively.
A first measurement fluid having a pressure P is introduced into the first pressure chamber 15a through the first pressure introduction hole 13a, and a first measurement fluid having a pressure P is introduced into the second pressure chamber 16a through the second pressure introduction hole 14a. A second measuring piece of driftwood having a pressure P2 is introduced.

First cover flange lla and second cover flange 12
a is attached to the differential pressure sensing section 10a via an O-ring.

The differential pressure sensing section 10a mainly includes a first casing 19a.
, a second casing 20a and a differential pressure transmitter 26a.

A cavity 21a is formed in the first casing 19a, and a first seal diaphragm 22a is formed on the opposite side of the cavity 21a.
is provided. The first seal diaphragm 22a forms a first seal chamber 24a together with the first casing 19a, and is affected by the pressure P introduced into the first pressure chamber 15a. Furthermore, a communication passage 30a is formed in the first casing 19a to communicate the cavity 21a and the first seal chamber 24a.

Further, a differential pressure transmitter 26a is welded to the second casing 20a, and a second seal diaphragm 23a is provided on the opposite side of the differential pressure transmitter 26a. The second seal diaphragm 23a forms a second seal M25a together with the second gauging 20a and is subjected to the action of the pressure P2 introduced into the second pressure chamber 16a.

This second gauging 20a includes a differential pressure transmitter 2 which will be described later.
A communication path 33a is formed that communicates the second measurement chamber 6a with the second seal chamber 25a. The first casing 19a and the second casing 20a are arranged so that the differential pressure transmitter 26a welded to the second gauging 20a is arranged in the cavity 21a of the first casing 19a, and at that time, the differential pressure transmitter 26a and the One casing 19a is welded so that a space 29a is formed between the two casings 19a and 19a.

In this way, the differential pressure transmitter 26a is fixedly arranged within the space formed by the first casing 19a and the second gauging 20a.

As shown in an enlarged sectional view in FIG. 6, the differential pressure transmitter 26a includes a first housing 27a and a second housing 28a.
has.

A cavity is formed in each of the housings 27a, 28a, and the cavity is filled with insulators 35a, 36a. Fixed poles 37a and 38a are provided on opposing surfaces of the insulators 35a and 36a.

A measuring diaphragm 34a is arranged between the first housing 27a and the second housing 28a, and the circumferential surface of the measuring diaphragm is welded to the first housing 27a and the second housing 28a.

The insulator 35a and the measurement diaphragm 34a constitute a first measurement chamber 42a, and the insulator 36a and the measurement diaphragm 34a constitute a second measurement chamber 43a.

Furthermore, a communication passage 31a for communicating the first measurement chamber 42a and the first sealing chamber 24a via the communication passage 30a is formed in the first housing 27a, and the communication passage 31a and the space 2
9a is provided.

Further, a communication passage 32a is formed in the second housing 28a to communicate the second measurement chamber 43a and the second seal chamber 25a via a communication passage 33a.

Thus, the second housing 28a of the differential pressure transmitter is welded to the second gauging 20a.

First seal chamber 24a, second seal chamber 25a, communication path 30
Two chambers constituted by a, 31a, 32a, 33a, a first measurement chamber 42a, a second measurement chamber 43a, and a space 29a are filled with sealed liquids 101a and 102a.

In the above configuration, when the differential pressure between the measured pressures PI and P2 is within a predetermined measurement range, the seal diaphragm 22
When a and 23a receive measurement pressures PI and P2, the measurement diaphragm 34a is displaced in response to the differential pressure via the sealed liquids 101a and 102a, and the electrostatic capacitance between the measurement diaphragm 34a and the fixed type w 37 a + 38a changes. Change.

As a result, an electrical signal corresponding to the differential pressure between the measured pressures Pl and P2 is obtained.

Next, when excessive pressure is applied to the first pressure chamber 15a (or the second pressure chamber 16a), the measuring diaphragm 34a is moved to the second housing 28a (d or the first housing 27a).
Protection against overpressure is provided by the close contact with the

The differential pressure transmitter 26a is disposed in a space 29a formed in the cavity 21a of the first casing 19a by the first casing 19a and the second casing 20a.

Therefore, the outside and inside of the differential pressure transmitter 26a, that is, the space 2
9a, the first measurement chamber 42a, and the second measurement chamber 43a have almost the same pressure via the valve 41a.

Therefore, even if the measured pressures P, , P, are high static pressures, the first housing 27a and the second housing 28a will not swell from the inside to the outside.

Therefore, the measuring diaphragm 34a is not subjected to a tensile force in its radial direction due to the static pressure, and the span of the measured differential pressure does not change due to the static pressure.

<Problems to be solved by the invention> However, in such a product, the filling liquid 10
1a is also sealed in the space 29a, the filled liquid becomes unbalanced, and in order to correct this, it is necessary to fill the filled liquid 1.
It is necessary to increase the amount of 02a to maintain balance. As a result, the amount of sealed liquid increases as a whole, and as a result of the increase in filled liquid, the change in pressure in the filling chamber increases when the temperature changes, and due to the difference in volume change of the seal diaphragms on both sides, the zero temperature change becomes large. This results in deterioration of temperature characteristics, etc.

Furthermore, if excessive pressure is applied to the second pressure chamber side, the excessive pressure cannot be effectively prevented.

The present invention solves this problem.

It is an object of the present invention to make the overall structure symmetrical, eliminate error factors such as temperature errors, and obtain good characteristics.The purpose of the present invention is to reduce the volume of the center diaphragm chamber and reduce the amount of sealed liquid. It is an object of the present invention to provide a capacitance type differential pressure measuring device that is less affected by expansion and contraction, has small hysteresis, and can be made compact.

Means for Solving the Problem> In order to achieve this object, the present invention provides two center diaphragms having ring-shaped grooves on their peripheral edges and arranged in close parallel to each other; a center diaphragm chamber consisting of a center diaphragm, a block-shaped body having a peripheral portion attached to the center diaphragm and forming a center chamber with the center diaphragm, and a seal chamber provided on the outer surface of the body with the body and a seal chamber. a seal diaphragm constituting a seal diaphragm, a back up nest provided on the body opposite to the seal diaphragm, a communication passage communicating the seal chamber and the center chamber, and a cover flange covering an outer surface of the body; A main body comprising a housing having an internal cavity, a disc made of an insulating material provided in the internal cavity, and a ring made of a metal material attached to the circumferential surface of the disc, and a chamber provided in the disc. , the word sentence is divided into two measurement chambers, a measurement diaphragm functioning as a moving electrode, a fixed electrode provided on the wall of the measurement chamber opposite to the measurement diaphragm, and the main body kept in the internal space with a gap. a tube that is connected at one end to the main body so as to be supported, has a middle portion fixed to the housing, and has the other end connected to the body to communicate the measurement chamber and the center chamber, and the inner cavity and the center diaphragm. A sealed liquid is sealed in each of three chambers consisting of a connecting tube that communicates with the chamber, the seal chamber, a communicating path, a center chamber, a center diaphragm chamber, a connecting tube, a tube, an internal space, and a measurement chamber. This constitutes a capacitance type differential pressure measuring device characterized by comprising:

In the above configuration, when the differential pressure of the measured pressure is within a predetermined measurement range, when the seal diaphragm receives the measured pressure, the measuring diaphragm is displaced in response to the differential pressure via the sealed liquid. , the capacitance between the measuring diaphragm and the fixed electrode changes.

As a result, an electrical signal corresponding to the differential pressure between the measured pressures is obtained.

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

<Example> FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, 11.12 is a ring-shaped groove 11 on the periphery.
1, 121, two center diaphragms arranged closely parallel to each other.

A center diaphragm chamber 13 is composed of two center diaphragms 11 and 12.

Reference numerals 21 and 22 designate block-shaped bodies whose peripheral portions are attached to the center diaphragms 11 and 12, respectively, and constitute center chambers 23 and 24, respectively.

Seal diaphragms 31 and 32 are provided on the outer surfaces of the bodies 21 and 22 and constitute seal chambers 311 and 321 with the bodies 21 and 22. Reference numerals 312 and 322 are back ap nests provided on the body 21.22 opposite the seal diaphragms 311.321.

Reference numerals 33 and 34 denote communication passages that communicate the seal chambers 321, 221, and 321 with the center chamber 23 and 24.

4 is a cover flange that covers the outer surface of the body 21, 22.

5 is a housing having an internal cavity 51.

Reference numeral 6 denotes a main body provided in the internal cavity 51 and consisting of a disk 61 made of an insulating material and a ring 62 made of a metal material and not attached to the circumferential surface of the disk 61.

As shown in FIG. 2, 611 is a chamber provided within the disk 61. As shown in FIG.

63 is a measurement diaphragm which divides the chamber 611 into two measurement chambers 631 and 632 and functions as a moving To&.

64 is a measurement chamber 631 facing the measurement diaphragm 63.
, 632 are fixed electrodes provided on the walls.

65 is connected to the main body 6 at one end and fixed to the housing 5 in the middle so as to support the main body 6 with a gap maintained in the internal space 51, fl! ! The ends are connected to the bodies 21 and 22 and the measuring chamber 6
31, 632 and the center chamber 23.24.

Reference numeral 66 is a connecting pipe that communicates the internal cavity 51 and the center diaphragm chamber 24.

101.102.103 are seal chambers 311, 321, communication passages 33.34. Center chamber 23, 24° Center diaphragm chamber 24. Connecting pipe 66, tube 65. Internal space 51
This is a sealed liquid that is sealed in three chambers, each consisting of a measurement chamber 631 and a measurement chamber 631, and a measurement chamber 632.

In the above configuration, when the differential pressure between the measured pressures p, p2 is within a predetermined measurement range, the seal diaphragm 31
, 32 receive the measured pressure, the sealed liquid 101, 102
, 103, the measuring diaphragm 63 is displaced in response to the differential pressure, and the measuring diaphragm 63 and the fixed type 'If! 64
The capacitance between the two changes.

Therefore, an electrical signal corresponding to the differential pressure between the measured pressures can be obtained.

Moreover, the pressure in the center diaphragm chamber 13 is
The pressure is equal to ±P2)/2. Therefore, a differential pressure of (Pl-P2)/2 is applied to the center diaphragms 11 and 12.

Also, measurement pressure P+ is applied to the measurement chamber 631, measurement pressure P2 is applied to the measurement chamber 632, and (P, +P2)/
Since a pressure of 2 is applied, no static pressure is applied to the disk 61 and ring 62, and 1/2 of the differential pressure of the measured pressure P I +22
There is no static pressure span shift due to deformation.

As a result, (1) Since the overall configuration was made symmetrical, the filled liquid 101.1
The amount of 02 is balanced and good temperature characteristics etc. can be obtained.

(2) The differential pressure applied to the center diaphragms 11 and 12 is 1/2 compared to the case of two center diaphragms, which is advantageous in terms of stress.

(3) Since the two center diaphragms 11 and 12 are arranged closely together, the amount of filled liquid 103 can be reduced less than when they are arranged apart, as shown in FIG.
The stress on the center diaphragm can be reduced and the size can be reduced.

(4) Only 1/2 of the differential pressure of the measurement pressure is applied to the ring 62, and the filled liquid 101 or 10 on one side is applied to the internal space 51.
This is advantageous compared to the case where 2 is introduced.

(5) Since the center diaphragms 11 and 12 can be welded to separate bodies 21 and 22, the characteristics of each can be checked after welding, and the capacitance change of the center diaphragms 11 and 12 can be checked. The pressure-receiving portion of an integral body can be constructed by combining and welding materials that have f properties, and can be assembled at a high yield and manufactured at low cost.

Furthermore, since a jig that suppresses deformation during welding can be used, a product can be obtained at low cost and with good properties.

(6) In the center diaphragms 11 and 12, the outer periphery of the ring-shaped grooves 111 and 121 provided on the periphery of the body 2
1.22 are fixed by welding 112, 122, the influence of welding 112.122 is on the center diaphragm 11, 1.
2, the center diaphragm 11.12
A product with less hysteresis can be obtained.

(7)? 1! Since the fulcrum position of the center diaphragm 11.12 is clearly defined by the portions 111 and 121,
A product with less hysteresis can be obtained.

(8) When the center diaphragm is expanded to the body outer diameter of the pressure-receiving portion and the outer periphery is welded, there is a problem that the zero span changes due to the tightening of the cover flange 4 and that the welding point becomes the fulcrum of the center diaphragm.

However, by using the center diaphragm 11, 12 with grooves 111, 121 of the present invention, these effects can be prevented and the effective diameters of the center diaphragms 11, 12 can be increased. That is, the pressure receiving section can be made smaller.

FIG. 4 is an explanatory diagram of the main part configuration of another embodiment of the present invention.

In this embodiment, grooves 111 and 121 are alternately provided on both sides of the center diaphragm 11 and 12.

In this way, it is possible to further reduce the bending moment of the support portion.

<Effects of the Invention> As explained above, the present invention comprises two center diaphragms having ring-shaped grooves on their peripheral edges and arranged close to each other in parallel, and the two center diaphragms. a block-shaped body having a peripheral portion attached to the center diaphragm and forming a center chamber with the center diaphragm, and a seal diaphragm provided on an outer surface of the body and forming a seal chamber with the body. , a pack-up nest provided in the body opposite to the seal diaphragm, a communication passage communicating the seal chamber and the center chamber, a cover flange covering an outer surface of the body, and a housing having an internal cavity. a main body comprising a disk made of an insulating material provided in the internal cavity and a ring made of a metal material attached to the circumferential surface of the disk; a chamber provided within the disk; and two chambers. A measurement diaphragm functioning as a movable electrode L1, a fixed electrode provided on the wall of the measurement chamber opposite to the measurement diaphragm, and a main body supported with a gap maintained in the internal space. A tube having one end connected to the main body, a midway fixed to the housing, and the other end connected to the body, communicating the J1 constant chamber and the center chamber, and communicating the internal cavity and the center diaphragm chamber. It is equipped with a connecting pipe, and a liquid sealed in each of three chambers, which are composed of the seal chamber, the communication passage, the center chamber, the center diaphragm chamber, the connecting pipe, the tube, the internal cavity, and the measurement chamber. Since we have constructed a capacitance type differential pressure measuring device characterized by: (1) the overall configuration is symmetrical
Because of the structure, the amount of sealed liquid is balanced and good temperature characteristics etc. can be obtained.

(2) The differential pressure applied to the center diaphragm is 1/2 compared to the case of one center diaphragm, which is advantageous in terms of stress.

(3) Since the two center diaphragms are placed closely together, the amount of sealed liquid can be reduced compared to when they are placed apart, reducing stress on the center diaphragm and making it more compact. Can be done.

(4) Only 1/2 of the differential pressure of the measured pressure is applied to the ring, which is advantageous compared to the case where one side of the sealed liquid is introduced into the internal cavity.

(5) Since the center diaphragms can be welded to separate bodies, the characteristics of each can be checked at the post-welding stage. - The pressure-receiving part of the wooden body can be constructed, and it can be assembled with a high yield and can be manufactured at low cost. Moreover, since a jig that suppresses deformation during welding can be used, a product can be obtained at low cost and with good properties.

(6) The center diaphragm has a ring-shaped groove provided on its periphery, and the outer periphery of the ring-shaped groove is welded and fixed to the body.
Welding does not affect the main body of the center diaphragm,
A center diaphragm with less hysteresis can be obtained.

(7) Since the fulcrum position of the center diaphragm becomes clear due to the groove, a device with less hysteresis can be obtained.

(8) When the center diaphragm is expanded to the body outer diameter of the pressure-receiving portion and the outer periphery is welded, there is a problem that the zero span changes due to the tightening of the cover flange 4 and that the welding point becomes the fulcrum of the center diaphragm.

However, by using the grooved center diaphragm of the present invention, these effects can be prevented and the effective diameter of the center diaphragm can be increased. That is, the pressure receiving section can be made smaller.

Therefore, according to the present invention, the overall structure is made symmetrical, error factors such as temperature errors are eliminated, good characteristics are obtained, and the volume of the center diaphragm chamber is made small, the amount of sealed liquid is reduced, and the sealed Reduces the influence of liquid swelling and contraction,
It is possible to realize an inexpensive capacitance type differential pressure measuring device with good characteristics and small hysteresis.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of one embodiment of the present invention, a second illustration of the effect, Fig. 4 is an explanatory diagram of the main part configuration of another embodiment of the invention, and Fig. 5 is a diagram commonly used in the past. FIG. 6 is an explanatory diagram of the configuration of the conventional example, and FIG. 6 is an explanatory diagram of the main part configuration of FIG. 5. 11.12... Center diaphragm, ]3... Center diaphragm chamber, 101, 102, 103... Filled liquid, 111.121... Groove, 112, 122...
Welding, 21.22...Body, 23.24...Center chamber, 31.32...Seal diaphragm, 311°321...Seal chamber, 312.322...Pack-up nest, 33.34 ...Communication path, 4...Cover flange, 5...Housing, 51...Internal cavity,
6... Main body, 61... Disk, 611... Chamber,
62...Ring, 63...Measuring diaphragm, 63
1,632...Measurement chamber, 64...Fixed Th f! ,
65...Tube, 66...Connecting pipe. Figure S Figure G

Claims (1)

[Claims] two center diaphragms having ring-shaped grooves on their peripheries and arranged close to each other in parallel; a center diaphragm chamber composed of the two center diaphragms;
A block-shaped body having a peripheral portion attached to the center diaphragm and forming a center chamber with the center diaphragm, a seal diaphragm provided on an outer surface of the body and forming a seal chamber with the body, and facing the seal diaphragm. a backup nest provided in the body, a communication path communicating the seal chamber and the center chamber, and a cover flange covering an outer surface of the body;
A main body comprising a housing having an internal cavity, a disc made of an insulating material provided in the internal cavity, and a ring made of a metal material attached to the circumferential surface of the disc, and a chamber provided in the disc. , the chamber is divided into two measurement chambers, a measurement diaphragm functioning as a moving electrode, a fixed electrode provided on the wall of the measurement chamber opposite to the measurement diaphragm, and a gap between the main body and the inner cavity. a tube having one end connected to the main body so as to be supported by the main body, a tube having a midway fixed to the housing and the other end connecting the measurement chamber and the center chamber, and the inner cavity and the center diaphragm chamber. a connecting tube that communicates with the liquid, and a sealed liquid that is sealed in each of the three chambers consisting of the seal chamber, the communication path, the center chamber, the center diaphragm chamber, the connecting tube, the tube, the internal space, and the measurement chamber. A capacitance type differential pressure measuring device characterized by comprising: