JPH048345Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Industrial application field) The present invention relates to a differential pressure measuring device.

More specifically, the invention relates to improvements in static pressure resistance or excessive pressure resistance.

(Prior Art) FIG. 2 is a diagram illustrating the configuration of a conventional example that has been commonly used.

In the figure, 1 is a block-shaped main body, and 11 is a chamber provided inside the main body 1. 21 is room 11
A measurement diaphragm that divides the measurement chamber into a first measurement chamber 12 and a second measurement chamber 13, and also functions as a moving electrode.
Fixed electrodes 22 and 23 are provided on the wall of the chamber 1 opposite the measurement diaphragm 2 via insulators 24 and 25. 31 is a ring-shaped housing into which the main body 1 is inserted and fixed. 4 is a casing in which a housing 31 is placed in an internal cavity 41.
A support spring 32 has one end fixed to the housing 31 and the other end fixed to the casing 4 so that the housing 31 is disposed in the internal space 41 with a gap. Seal diaphragms 51 and 52 are provided on both outer surfaces of the casing 4 and form seal chambers 53 and 54 with the casing 4. 55, 56
is a back up nest formed in the main body 1 opposite to the seal diaphragms 51 and 52. 1
4 and 15 are communication holes that communicate the seal chambers 53 and 54 with the first and second measurement chambers 12 and 13. 10
1 and 102 are the first and second measurement chambers 12 and 13, the internal space 41, the seal chambers 53 and 54, and the communication hole 14 and 1
It is an incompressible sealed liquid that is filled in two chambers consisting of 5 and 5, respectively.

In the above configuration, the measured pressure P _H from the left and right of the figure,
When P _L is applied, the seal diaphragms 51 and 52 are displaced in response to the differential pressure, and the sealed liquids 101 and 10 are
2, the measurement diaphragm 21 is displaced, the gap between it and the fixed electrodes 22 and 23 changes, and the capacitance between the electrodes changes differentially. This capacitance change makes it possible to obtain an electrical signal output corresponding to the differential pressure.

(Problems to be Solved by the Invention) In such a device, a portion for detecting a change in capacitance is suspended within the incompressible sealed liquids 101 and 102 by a support spring 32.
Thus, the detection portion is displaced in response to the differential pressure.

Therefore, special consideration is required to extract the capacitance change signal from the detection part, and a spring is usually used, making the structure complicated.
Lacking reliability.

The present invention solves this problem.

The purpose of this invention is to reduce span changes in measured differential pressure due to static pressure and hysteresis due to excessive pressure.
It is an object of the present invention to provide a differential pressure measuring device that is not affected by changes in the tightening force of a cover or changes in temperature, and in which leads can be easily taken out from a detection section.

(Means for solving the problem) In order to achieve this object, the present invention includes a block-shaped casing, a seal diaphragm provided on the outer surface of the casing and constituting a seal chamber, and a seal diaphragm facing the seal diaphragm. a backup nest provided in the casing; a cover covering the outer surface of the casing; an internal space provided in the casing; a main body provided in the internal space; a tube with one end connected to the main body and the other end connected to the casing so as to maintain a gap in the internal cavity; a chamber provided inside the main body;
A measurement diaphragm which is divided into a measurement chamber and also functions as a moving electrode, a fixed electrode provided on the chamber wall opposite the measurement diaphragm via an insulator, and an overrange chamber provided on the outer surface of the main body. an overrange diaphragm that communicates with the seal chamber and the first measurement chamber or the second measurement chamber through the tube, and a communication hole provided in the main body that communicates the communication hole with the overrange chamber. A sealed liquid filled in three chambers each consisting of a connection hole, the first and second measurement chambers, the internal cavity, the overrange chamber, the seal chamber, the communication hole, and the connection hole. This constitutes a differential pressure measuring device comprising:

(Function) In the above configuration, when measurement pressure is applied to the seal diaphragm, the seal diaphragm is displaced in response to the differential pressure, and the measurement diaphragm is displaced via the sealed liquid. When the measurement diaphragm is displaced, the gap with the fixed electrode changes, and the capacitance between the electrodes changes differentially. This capacitance change makes it possible to obtain an electrical signal output corresponding to the differential pressure.

When excessive pressure is applied, the seal diaphragm on the side to which the excessive pressure is applied is displaced until it hits the back up nest. After that, the pressure in the internal chamber does not increase. On the other hand, the enclosed liquid displaced by the sealing diaphragm is absorbed by the measuring diaphragm and mainly by the overrange diaphragm.

When high static pressure is applied, the pressures of all the filled liquids are the same and the body remains supported by the tube under static pressure.

Examples will be described below.

(Embodiment) FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, the same symbols as in FIG. 2 indicate the same functions.

Hereinafter, only the differences from FIG. 2 will be explained.

42 is a ring-shaped housing. 43,4
Reference numeral 4 designates a plate-shaped protective wall that covers both side surfaces of the housing 42 and forms an internal space 41 with the housing 42 . Housing 42 and protective walls 43, 44
A casing 4 is formed by this. 61,62
is a tube whose one end is connected to the main body 1 and the other end is connected to the casing 4 so as to support the main body 1 with a gap maintained in the internal cavity 41. 71 and 72 are provided on the outer surface of the main body 1, and an overrange chamber 71
1,721 is a donut-shaped and wavy overrange diaphragm. 16,17
are the seal chambers 53, 54 and the first and second measurement chambers 12,
This is a communication hole that communicates with 13. Reference numerals 18 and 19 are connection holes provided in the main body 1 and communicating the communication holes 16 and 17 with the overrange chambers 711 and 721.
103 indicates the seal chamber 53, the communication hole 16, and the connection hole 18.
and the sealed liquid filled in the overrange chamber 711 and the first measurement chamber 12. 104 is internal space 4
It is an enclosed liquid filled in 1. Reference numeral 105 is a sealed liquid filled in the second measurement chamber 13, the communication hole 17, the connection hole 19, the overrange chamber 721, and the seal chamber 54. 81, 82 cover the protective walls 43, 44 and apply pressure P _H . P _L are the covers to be introduced respectively.

In the above configuration, as shown in FIG. 1, the measured pressure P _H . _PL joins. Measured pressure P _H
When the pressure is higher than the measured pressure P _L , the seal diaphragm 52 is displaced to the left in the figure. The volume of the filled liquid 105 that is thereby moved causes the measurement diaphragm 21 to move to the left in the figure and the overrange diaphragm 72 to the right in the figure. Displacement of overrange diaphragm 72 displaces overrange diaphragm 71 by the same amount. The seal diaphragm 51 is displaced by an amount corresponding to the sum of the amount of movement of the sealed liquid 103 and the amount of movement of the measurement diaphragm 21 due to this. That is, the measuring diaphragm 21 is displaced in proportion to the differential pressure. Thus, the gap between the measurement diaphragm 21 and the fixed electrodes 22, 23 changes, and the capacitance between the electrodes changes differentially. This capacitance change makes it possible to obtain an electrical signal output corresponding to the differential pressure.

Next, a case where excessive pressure acts from the high pressure side will be explained. Seal diaphragm 52 is displaced until it hits backup nest 56. Thereafter, the pressure of the sealed liquid 105 does not increase. In this case, the sealed liquid 105 removed by the seal diaphragm 52
is absorbed by the measurement diaphragm 21 and the overrange diaphragm 72. Generally, the design is such that the sealing diaphragm 52 contacts the back-up nest 56 before the measuring diaphragm 21 contacts the wall of the first measuring chamber 12. However, even if the measurement diaphragm 21 contacts the wall of the first measurement chamber 12 first, the overrange diaphragm 72 is subsequently displaced. pressure is not very high. Therefore, bending deformation due to excessive pressure acting on the spherical walls of the measurement chambers 12 and 13 is reduced.

Next, a case where static pressure is applied will be explained.
When static pressure is applied, all internal chambers have approximately the same pressure. Focusing on the main body 1, since the main body 1 is suspended in static pressure, no change in tension occurs in the measuring diaphragm 21 that would change the measured differential pressure span.

Since the main body 1 is supported by the tubes 61 and 62, there is no influence due to changes in the tightening force of the covers 81 and 82 of the protective walls 43 and 44 or due to changes in ambient temperature. The deformation of the housing 61 and the protective walls 43 and 44 caused by this is all absorbed by the tubes 61 and 62, so that the influence of the deformation is not transmitted to the main body 1.

Also, overrange diaphragms 71, 72
Similar to the measurement diaphragm 21, the seal diaphragm 51, 52 can adopt a volume change rate that is about 1/100 smaller than that of the seal diaphragm 51, 52.
52 can absorb the effects of temperature changes, etc., allowing for a high degree of freedom in design.

As a result There is no span change in measurement difference due to static pressure.

Since there is little bending deformation of the main body 1 due to excessive pressure,
Hysteresis caused by excessive pressure is small, improving the reliability of the detection section.

Since the main body 1 is mechanically insulated by the tubes 61 and 62, the casing 4
Mechanical disturbances applied to the main body 1 are small due to the influence of tightening, the difference in temperature expansion coefficients, etc.

Since the main body 1 does not move in response to the differential pressure as in the conventional example shown in FIG. 2, the structure for extracting electrical signals from the detection section can be simplified.

(Effects of the Invention) As explained above, the present invention includes a block-shaped casing, a seal diaphragm provided on the outer surface of the casing and forming a seal chamber, and a seal diaphragm provided in the casing opposite to the seal diaphragm. a back up nest, a cover that covers an outer surface of the casing, an internal space provided in the casing, a main body provided in the internal space, and a gap between the main body and the internal space. a tube having one end connected to the main body and the other end connected to the casing so as to be supported by the main body, a chamber provided inside the main body, and the chamber divided into a first and second measurement chamber and used as a moving electrode. a fixed electrode provided on the chamber wall opposite the measurement diaphragm via an insulator; an overrange diaphragm provided on the outer surface of the main body and constituting an overrange chamber; a communication hole that communicates the seal chamber and the first measurement chamber or the second measurement chamber through the tube; a connection hole provided in the main body that communicates the communication hole and the overrange chamber; , comprising a sealed liquid filled in each of three chambers consisting of the second measurement chamber, the internal cavity, the overrange chamber, the seal chamber, the communication hole, and the connection hole. Since the pressure measuring device is configured, the main body is suspended in static pressure, so no change in tension occurs in the measuring diaphragm that would change the measured differential pressure span, and no span change occurs. When excessive pressure is applied, both the internal and external pressures of the main body are equal to the excessive pressure, and the bending deformation of the main body is small. Since the main body is insulated by the tube, mechanical disturbances are less likely to act on the main body. Since the main body does not move due to the differential pressure, the structure for extracting electrical signals can be simplified.

Therefore, according to the present invention, span changes in measured differential pressure due to static pressure, hysteresis due to excessive pressure,
It is possible to realize a differential pressure measuring device in which mechanical disturbances are less likely to act on the main body and leads can be easily taken out.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the configuration of one embodiment of the present invention;
The figure is an explanatory diagram of the configuration of a conventional example that has been commonly used. 1... Main body, 103, 104, 105... Enclosed liquid, 11... Chamber, 12... First measurement chamber, 13...
...Second measurement chamber, 16,17...Communication hole, 18,1
9... Connection hole, 21... Measurement diaphragm, 2
2, 23... fixed electrode, 24, 25... insulator,
4... Casing, 41... Internal void, 42...
Housing, 43, 44... Protection wall, 51, 52
... Seal diaphragm, 53, 54 ... Seal chamber, 55, 56 ... Backup nest, 61,
62...tube, 71,72...overrange diaphragm, 711,721...overrange chamber, 81,82...cover.

Claims (1)

[Scope of utility model registration request] A block-shaped casing, a seal diaphragm provided on the outer surface of the casing and forming a seal chamber, and a backup nest provided in the casing opposite to the seal diaphragm;
a cover that covers the outer surface of the casing; an internal space provided in the casing; a main body provided in the internal space; and a cover that supports the main body with a gap maintained in the internal space. A tube having one end connected to the main body and the other end connected to the casing, a chamber provided inside the main body, and a measurement diaphragm which divides the chamber into a first and second measurement chamber and also functions as a moving electrode. , a fixed electrode provided on the chamber wall opposite the measurement diaphragm via an insulator, and an overrange diaphragm provided on the outer surface of the main body and forming an overrange chamber;
a communication hole that communicates the seal chamber with the first measurement chamber or the second measurement chamber through the tube;
a connection hole provided in the main body and communicating the communication hole and the overrange chamber; the first and second measurement chambers, the internal cavity, the overrange chamber, the seal chamber, the communication hole, and the connection; A differential pressure measuring device comprising three chambers each consisting of a hole and a sealed liquid filled in each chamber.