JPH0444221B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a capacitive differential pressure measuring device.

More specifically, the present invention relates to a capacitive differential pressure measuring device in which the span of measured pressure does not change 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 consists of a differential pressure sensing section 10a, a first cover flange 11a, and a second cover flange 12a. First cover flange 11a and second cover flange 12a
are the first pressure chamber 15a and the second pressure chamber 16, respectively.
a, a first measurement fluid having a pressure P ₁ is introduced into the first pressure chamber 15a through the first pressure introduction hole 13a, and a second pressure introduction hole 14a is introduced into the second pressure chamber 16a. A second measuring fluid with pressure P ₂ is led through. The first cover flange 11a and the second cover flange 12a are attached to the differential pressure sensing portion 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 oscillating section 26a. A cavity 21a is formed in the first casing 19a, and a first seal diaphragm 22a is provided on the opposite side of the cavity 21a. The first seal diaphragm 22a forms a first seal chamber 24a together with the first casing 19a, and is subjected to the action of the pressure _P1 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 oscillating section 26a is welded to the second casing 20a, and a second seal diaphragm 23a is provided on the opposite side of the differential pressure oscillating section 26a. The second seal diaphragm 23a forms a second seal chamber 25a together with the second casing 20a, and is subjected to the action of the pressure _P2 introduced into the second pressure chamber 16a. A communication passage 33a is formed in the second casing 20a, which communicates a second measurement chamber of a differential pressure oscillation section 26a, which will be described later, with a second seal chamber 25a. First casing 19a
and the second casing 20a are the second casing 2
The differential pressure oscillator 26a welded to the first casing 19a is placed in the space 21a of the first casing 19a, and at this time, a space 29a is formed between the differential pressure oscillator 26a and the first casing 19a. Welded.
In this way, the differential pressure oscillator 26a is fixedly arranged within the space formed by the first casing 19a and the second casing 20a.

The differential pressure oscillator 26a has a first housing 27a and a second housing 28a, as shown in an enlarged sectional view in FIG.
A space is formed in each space a, and this space is filled with insulators 35a and 36a. Insulator 3
A fixed electrode 3 is provided on the mutually opposing surfaces of 5a and 36a.
7a and 38a are provided. 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. Therefore, the insulator 35
a 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, the first housing 27a includes:
A communication path 31a is formed to communicate the first measurement chamber 42a and the first seal chamber 24a via a communication path 30a, and a groove 41a is provided to communicate the communication path 31a and the space 29a. 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 oscillator is welded to the second casing 20a. First seal chamber 24a, second seal chamber 25a, communication passages 30a, 31a, 32a, 33
a, the two chambers consisting of the first measurement chamber 42a, the second measurement chamber 43a and the space 29a contain the sealed liquid 101.
a, 102a are satisfied.

In the above configuration, when the differential pressure between the measured pressures P ₁ and P ₂ is within a predetermined measurement range, when the seal diaphragms 22a and 23a receive the measured pressures P ₁ and P ₂ , the sealed liquids 101a and 102a are The measuring diaphragm 34a is displaced in response to the differential pressure through the
Measuring diaphragm 34a and fixed electrodes 37a, 38
The capacitance between a changes.

As a result, an electrical signal corresponding to the differential pressure between the measured pressures P ₁ and P ₂ is obtained.

Next, the first pressure chamber 15a (or the second pressure chamber 1
6a), protection against the overpressure is provided by the close contact of the measuring diaphragm 34a with the second housing 28a (or the first housing 27a).

The differential pressure oscillator 26a is arranged 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 oscillator 26a, that is, the space 29a, the first measurement chamber 42a, and the second measurement chamber 43a have approximately the same pressure via the groove 41a. Therefore, even if the measured pressures P ₁ and P ₂ are high static pressures, the first housing 27a and the second housing 28
A never tries to expand from the inside to the outside.

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

<Problems to be Solved by the Invention> However, in such a device, since the filled liquid 101a is also sealed in the space 29a, the filled liquid becomes unbalanced, and in order to correct this, it is necessary to change the filled liquid It is necessary to increase the amount of 102a 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.

The purpose of the present invention is to make the entire configuration 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 liquid filled in it, so that the expansion and contraction of the filled liquid is reduced. An object of the present invention is to provide a capacitance type differential pressure measuring device that reduces the influence of.

<Means for Solving the Problem> In order to achieve this object, the present invention includes a block-shaped body, an internal chamber provided inside the body, and a center chamber that divides the internal chamber into two center chambers. a center diaphragm unit comprising two center diaphragms and a center diaphragm chamber formed by the two center diaphragms; a seal diaphragm provided on the outer surface of the body and forming a seal chamber with the body; a back up nest provided in the body to face each other, a communication path communicating the seal chamber and the center chamber, a cover flange covering an outer surface of the body, a housing having an internal cavity, and a housing having an internal cavity; A main body consisting of a disk made of an insulating material provided at a location, a ring made of a metal material attached to the circumferential surface of the disk, a chamber provided within the disk, and the chamber divided into two measurement chambers. a measuring diaphragm functioning as a moving electrode; a fixed electrode provided on the wall of the measuring chamber opposite to the measuring diaphragm; and one end connected to the main body so as to support the main body with a gap maintained in the internal cavity. a tube whose middle part is fixed to the housing and whose other end is connected to the body and communicates between the measurement chamber and the center chamber; a connecting tube which communicates between the internal cavity and the center diaphragm chamber; and the seal chamber. , a capacitor comprising a liquid sealed in each of three chambers consisting of a communication passage, a center chamber, a center diaphragm chamber, a connecting pipe, a tube, an internal cavity, and a measurement chamber. This is a type of differential pressure measuring device.

<Function> In the above configuration, when the differential pressure of the measured pressure is within the predetermined measurement range, when the seal diaphragm receives the measured pressure, the measuring diaphragm is displaced via the sealed liquid in response to the differential pressure. However, the capacitance between the measurement 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 a configuration of an example of the present invention.

In the figure, 1 is a block-shaped body.
11 is an internal chamber provided inside the body 1.
2 is a center diaphragm unit that divides the internal chamber 11 into two center chambers 12 and 13. As shown in FIG. 2, the center diaphragm unit 2 includes two center diaphragms 21 and 22, a ring-shaped spacer 23, and a center diaphragm chamber 24 formed by the center diaphragms 21 and 22 and the spacer 23. It is a sender diaphragm unit. 31 and 32 are provided on the outer surface of the body 1 and are connected to the body 1 and the seal chambers 311 and 3.
21 is a seal diaphragm. 31
2,322 is a seal diaphragm 311,321
This is a back up nest provided in the body 1 opposite to the back up nest. 33 and 34 are seal chambers 311 and 32
1 and the center chambers 12 and 13. 4 is a cover flange that covers the outer surface of the body 1. 5 is a housing having an internal cavity 51. Reference numeral 6 denotes a main body consisting of a disk 61 made of an insulating material and provided in the internal cavity 51, and a ring 62 made of a metal material attached to the circumferential surface of the disk 61. As shown in FIG. 3, 611 is a disk 61.
It is a room set up inside. 63 is a measurement diaphragm which divides the chamber 611 into two measurement chambers 631 and 632 and functions as a moving electrode. 64 is a fixed electrode provided on the wall of the measurement chambers 631, 632 facing the measurement diaphragm 63. Reference numeral 65 is connected to the main body 6 at one end so as to support the main body 6 with a gap maintained in the internal space 51, is fixed to the housing 5 in the middle, and is connected to the body 1 at the other end, and has measurement chambers 631, 63.
2 and the center chambers 12 and 13. Reference numeral 66 is a connecting pipe that communicates the internal space 51 and the center diaphragm chamber 24. 101,10
2, 103 are seal chambers 311, 321, communication passage 3
3, 34, center chambers 12, 13, center diaphragm chamber 24, connecting pipe 66, tube 65, internal space 51, and measurement chambers 631, 632.
This is a liquid that is sealed in each individual chamber.

In the above configuration, when the differential pressure between the measurement pressures P ₁ and P ₂ is within a predetermined measurement range, when the seal diaphragms 31 and 32 receive the measurement pressure, the measurement is performed via the sealed liquids 101, 102, and 103. The diaphragm 63 is displaced in response to the differential pressure, and the capacitance between the measurement diaphragm 63 and the fixed electrode 64 changes.

Therefore, an electrical signal corresponding to the pressure difference between the measured pressures is obtained.

Further, the pressure in the center diaphragm chamber 24 is approximately equal to (P ₁ +P ₂ )/2. Therefore,
The center diaphragms 21 and 22 have (P ₁ −
A differential pressure of P ₂ )/2 is applied.

In addition, the measurement pressure P ₁ is applied to the measurement chamber 631, and the measurement pressure P 1 is applied to the measurement chamber 631.
Measurement pressure P ₂ is applied to 32, and (P ₁
Since a pressure of +P ₂ )/2 is applied, the disk 61,
No static pressure is applied to the ring 62, and the measured pressures P ₁ and P ₂
Only 1/2 of the differential pressure is applied, and there is no static pressure span shift due to deformation.

As a result, (1) Since the overall structure is symmetrical, the filled liquid 10
The amount of 1,102 is balanced and good temperature characteristics etc. can be obtained.

(2) The differential pressure applied to the center diaphragms 21 and 22 is 1/1 compared to when there is only one center diaphragm.
2, which is advantageous in terms of stress.

(3) Since the two center diaphragms 21 and 22 are arranged closely together, the amount of filled liquid 103 is lower than when they are arranged apart, as shown in FIG.
The amount of stress on the center diaphragm can be reduced, and the center diaphragm can be made smaller.

(4) Only 1/2 of the differential pressure of the measurement pressure is applied to the ring 62, and the filled liquid 10 on one side is applied to the internal space 51.
1 or 102.

FIG. 5 is an explanatory diagram of the configuration of another embodiment of the present invention.

In this embodiment, the diaphragm unit 2 is disposed within a body 7, and the body 7 is disposed within the body 1 with a gap 71 maintained therebetween.

In this way, the adverse effects when the body 1 is tightened by the cover flange 4 etc. can be prevented from being applied to the diaphragm unit 2, and a device with less zero point and span fluctuations can be obtained.

<Effects of the Invention> As explained above, the present invention includes a block-shaped body, an internal chamber provided inside the body,
A center diaphragm unit which divides the internal chamber into two center chambers and includes two center diaphragms and a center diaphragm chamber formed by the two center diaphragms, and a center diaphragm unit provided on the outer surface of the body and sealed with the body. a seal diaphragm forming a chamber; a back up nest provided in the body opposite to the seal diaphragm;
A communication path communicating the seal chamber and the center chamber, a cover flange covering the outer surface of the body, a housing having an internal cavity, a disk made of an insulating material provided in the internal cavity, and a periphery of the disk. A main body consisting of a ring made of a metal material attached to a surface, a chamber provided in the disk, a measuring diaphragm that divides the chamber into two measuring chambers and functions as a moving electrode, and a measuring diaphragm facing the measuring diaphragm. and a fixed electrode provided on the wall of the measurement chamber, and one end connected to the main body so as to support the main body with a gap maintained in the internal space, a middle part fixed to the housing, and the other end connected to the body. a tube that is connected and communicates the measurement chamber and the center chamber, a connection tube that communicates the internal cavity and the center diaphragm chamber, the seal chamber, the communication passage, the center chamber, the center diaphragm chamber, the connection tube; Since we have constructed a capacitance type differential pressure measuring device characterized by having three chambers consisting of a tube, an internal cavity, and a measurement chamber each containing a sealed liquid, (1) Overall Since the configuration is symmetrical, 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 that of a single 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. I can do it.

(4) Only 1/2 of the differential pressure of the measured pressure is applied to the ring, which is advantageous compared to introducing the filled liquid from one side into the internal cavity.

Therefore, according to the present invention, the overall structure is made symmetrical, error factors such as temperature errors are eliminated to obtain good characteristics, and the volume of the center diaphragm chamber is reduced, the amount of sealed liquid is reduced, and the sealed liquid is reduced. It is possible to realize a capacitance type differential pressure measurement device that reduces the influence of expansion and contraction of the capacitance type.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of one embodiment of the present invention, and FIG.
3 is an explanatory diagram of the main part configuration of FIG. 1, FIG. 4 is an explanatory diagram of the effect of FIG. 1, FIG. 5 is an explanatory diagram of the configuration of another embodiment of the present invention, and FIG. 6 is a conventional FIG. 7 is an explanatory diagram of the configuration of a conventional example commonly used, and FIG. 7 is an explanatory diagram of the main part configuration of FIG. 6. 1... Body, 101, 102, 103... Filled liquid, 11... Internal chamber, 12, 13... Center chamber, 2...
Diaphragm unit, 21, 22... Center diaphragm, 23... Spacer, 24... Center diaphragm chamber, 31, 32... Seal diaphragm, 3
DESCRIPTION OF SYMBOLS 11, 321... Seal chamber, 312, 322... Backup 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, 631, 63
2...Measurement chamber, 64...Fixed electrode, 65...Tube,
66...Connecting pipe, 7...Body, 71...Gap.

Claims (1)

[Claims] 1 A block-shaped body, an internal chamber provided inside the body, the internal chamber divided into two center chambers, two center diaphragms, and a center diaphragm chamber formed by the two center diaphragms. a seal diaphragm provided on the outer surface of the body and forming a seal chamber with the body; a back up nest provided on the body opposite to the seal diaphragm; and a seal chamber and the center. a housing having a communication path that communicates the chambers, a cover flange that covers the outer surface of the body, an internal cavity, a disk made of an insulating material provided in the internal cavity, and a metal attached to the circumferential surface of the disk. a main body consisting of a ring made of material, a chamber provided in the disk, a measurement diaphragm that divides the chamber into two measurement chambers and functions as a moving electrode, and a wall of the measurement chamber opposite to the measurement diaphragm. a fixed electrode provided in the inner cavity, one end connected to the main body so as to support the main body with a gap maintained in the internal cavity, a middle part fixed to the housing, the other end connected to the body, and the measuring chamber. a tube that communicates with the center chamber, a connecting tube that communicates the internal space with the center diaphragm chamber, and the seal chamber;
A capacitance type characterized by having a liquid sealed in each of three chambers consisting of a communication passage, a center chamber, a center diaphragm chamber, a connecting pipe, a tube, an internal cavity, and a measurement chamber. Differential pressure measuring device.