JP3047503B2 - Differential pressure measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure measuring device. More specifically, the present invention relates to a differential pressure measuring device which has improved temperature characteristics due to a reduction in the amount of a filled liquid, can be miniaturized, and is less affected by a cover flange tightening force.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view of the structure of a conventional example generally used in the prior art.
No. 1 "Capacitance type differential pressure measuring device" is disclosed in the application filed on June 18, 1987.

In the drawing, 1a is a block-shaped body,
Reference numeral 11a denotes an inner chamber provided inside the body 1a, and 2a denotes a center diaphragm which divides the inner chamber 11 into two center chambers 21a and 22a. 31a and 32a are provided at the center of the outer surface of the body 1a, and the body 1a and the seal chamber 311 are provided.
a, 321a. 3
12a and 322a are seal diaphragms 31a and 32a.
This is a back-up nest provided on the body 1a so as to face the front side.

[0004] 33a and 34a are seal diaphragms 31.
a, 32a are ring-shaped annular diaphragms provided concentrically on the outer peripheral portion of the outer surface of the body 1a and constituting the body 1a and the annular chambers 331a, 341a. 332a,
342a is a backup nest provided on the body 1a to face the diaphragms 33a and 34a. 12a
Are center rooms 21a and 22a and seal rooms 311a and 321
and a communication hole communicating with a.

[0005] Reference numeral 4a denotes a housing having an internal space 41a. 42a is a main body provided in the internal space 41a. 43a has one end connected to the main body 42a so as to support the main body 42a in the internal space 41a with a gap therebetween, the other end being fixed to the housing 4a, the other end being connected to the body 1a, and communicating with the center chambers 21a and 22a, respectively. Chu
It is.

[0006] 421a is a chamber provided inside the main body 42a. 422 denotes a chamber 421 a for two measurement chambers 42.
This is a measurement diaphragm which is divided into 3a and 424a and functions as a moving electrode. Reference numerals 425a and 426a denote fixed electrodes provided on the walls of the measurement chambers 423a and 424a via the insulators 427a and 428a so as to face the measurement diaphragm 422a.

Reference numeral 44a denotes an inner space 41a and an annular chamber 331.
a and 341a. 51a,
52a, 53a are seal chambers 311a, 321a, communication holes 12a, center chambers 21a, 22a, annular chambers 331a,
341a, connecting pipe 44a, tube 43a, internal space 4
This is an incompressible sealed liquid which is respectively sealed in three chambers composed of 1a and measurement chambers 423a and 424a.
In this case, silicone oil is used.

In the above configuration, the differential pressure applied to the seal diaphragms 31a and 32a is transmitted to the internal chamber 11a via the communication hole 12a. Further, the measuring diaphragm 422a is displaced through the tube 43a into the measuring chambers 423a and 424a. Displacement proportional to this differential pressure is
Measurement diaphragm 422a and fixed electrodes 425a, 426
The change is detected as a change in capacitance between a and converted into an electric signal.

When a high static pressure is applied, a high static pressure is applied to the measuring chambers 423a and 424a, and a high static pressure is applied to the diaphragms 33a and 34a. Since static pressure is applied to 41a,
The main body 42a is placed in a static pressure, and no distortion is caused in the measurement diaphragm 422a due to the static pressure, so that no span variation occurs due to the static pressure.

On the other hand, when an overpressure is applied, all the sealed liquids 51a and 52a in the seal chamber 311a or 321a on the side to which the overpressure is applied are discharged. This sealed liquid 51
a or 52a is absorbed by the displacement of the center diaphragm 2a. Thus, the seal diaphragm 33
a and 34a are the backup nest 312a or 32
2a, the liquid 51a or 52a no longer moves, and the measurement diaphragm 422a
Is not overpressured and is thus protected from overpressure.

When an excessive pressure is applied, the annular diaphragm 3
The excessive pressure application side of 3a or 34a is seated on the backup nest 332a or 342a, but the annular diaphragm on the side to which no excessive pressure is applied expands, so that the pressure increase in the internal space 41a is negligibly small. .

The filled liquid 53a in the internal space 41a is
31a, 341a, and the tubular diaphragm 33a,
Since the sealing liquid 34a is separated from the seal diaphragms 31a and 32a, the sealed liquid 53a does not participate in the measurement.
Therefore, the characteristics of the tubular diaphragms 33a and 34a do not directly affect the measurement of the differential pressure, so that a large degree of design freedom is obtained.

As a result, (1) prevention of occurrence of excessive pressure hysteresis. When excessive pressure is applied, the seal diaphragms 31a, 32a
However, the amount of movement of the sealed liquids 51a and 52a until the seats are seated on the back-up nests 312a and 322a is absorbed by the displacement of the center diaphragm 2a. Diaphragm 422a is protected from overpressure. Therefore, it is possible to reduce the occurrence of hysteresis of the measurement diaphragm due to the excessive pressure.

(2) Prevention of error due to tightening of the cover flange 5a. Since the sensor main body that is sensitive to mechanical disturbance is separately provided from the pressure receiving portion and supported by the tube 43a, it is possible to prevent the occurrence of an error due to the fastening of the cover flange 5a to the main body 1a. .

(3) Prevention of occurrence of temperature error. Since the sensor body and the pressure receiving portion are separately provided and supported by the tube 43a, it is possible to prevent the occurrence of a temperature error due to a difference in the thermal expansion coefficient between the pressure receiving portion and the sensor body.

[0016]

However, in such an apparatus, (1) since the pressure receiving section is separated from the pressure sensor section, the amount of the sealed liquid increases, and the temperature characteristics deteriorate. (2) Since the pressure receiving unit and the pressure sensor unit are separated, the size of the device is increased, and it is difficult to reduce the size. (3) Zero, due to the effect of the cover flange tightening force
Span fluctuation is likely to occur.

The present invention solves this problem. SUMMARY OF THE INVENTION It is an object of the present invention to provide a differential pressure measuring device which can improve the temperature characteristics by reducing the amount of the filled liquid, can be downsized, and is less affected by the cover flange tightening force.

[0018]

In order to achieve the above object, according to the present invention, in the first aspect, a block-shaped first body having a concave portion, and a concave portion and a center chamber fixed to the concave portion are formed. The second body and the center chamber are first and second
A center diaphragm provided on one side of the first body, and a first diaphragm and a second
A seal diaphragm constituting a seal chamber, a backup nest provided on the first body opposite to the seal diaphragm, and a first nest provided on the first body.
A first communication hole communicating the seal chamber with the first center chamber, a second communication hole provided in the first body and communicating the second seal chamber with the second center chamber; A cover flange covering one surface of the first body, a measurement chamber provided in the second body, a main body provided in the measurement chamber, and first and second measurement chambers provided in the main body. A measurement diaphragm divided into measurement chambers, a third communication hole provided in the second body for communicating the first measurement chamber with the first center chamber, a detection sensor for detecting displacement or distortion of the measurement diaphragm, One end is connected to the main body so as to support the main body in the measurement chamber with a gap therebetween, and communicates with the first measurement chamber.
And a support pipe provided on the first body and having the other end connected to the second body and having the other end connected to the first body and communicating the other end of the support pipe with the second seal chamber. A fourth communication hole, the first and second seal chambers, first to fourth
A differential pressure measuring device is provided, which comprises two chambers each comprising a communication hole, a center chamber, a measurement chamber, and a support pipe, and a sealed liquid respectively sealed therein. According to claim 2, which is constituted of the differential pressure measuring device in the range preceding claim claims, characterized by comprising a center diaphragm having a large becomes thermal expansion coefficient than the thermal expansion coefficient of the body.

[0019]

In the above construction, the differential pressure applied to the seal diaphragm is transmitted to the measurement chamber via the communication hole, and displaces the measurement diaphragm. The displacement of the measurement diaphragm, which is proportional to the differential pressure, is detected by a detection sensor and converted into an electric signal.

When an overpressure is applied, the overpressure protection mechanism (center diaphragm) moves, the seal diaphragm sits on the first body, and an overpressure exceeding a certain level is not applied to the measurement diaphragm. Further, in the present invention, since the center diaphragm having the thermal expansion coefficient larger than the thermal expansion coefficient of the body is provided, the volume change constant of the center diaphragm changes according to the expansion and contraction due to the temperature of the filling liquid, and the measurement diaphragm is changed. The overpressure applied to 21 can be made substantially constant. Hereinafter, a detailed description will be given based on embodiments.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a main part configuration of an embodiment of the present invention. Reference numeral 1 denotes a block-shaped first body having a concave portion 2. Reference numeral 3 denotes a second body fixed to the concave portion 2 and forming the center chamber 4 with the concave portion 2. Reference numeral 5 denotes a center diaphragm that divides the center chamber 4 into first and second center chambers 6 and 7, and functions as an overpressure protection element.

Reference numerals 8 and 9 are provided on one surface side of the first body 1 and the first body 1 and the first and second seal chambers 11 and 1 respectively.
2 is a seal diaphragm. 13,14
The first body 1 faces the seal diaphragms 8 and 9.
This is a backup nest provided in. 15 is the first
The first communication hole is provided in the body 1 and communicates the first seal chamber 11 with the first center chamber 6. Reference numeral 16 denotes a second communication hole provided in the first body 1 and communicating the second seal chamber 12 and the second center chamber 7.

Reference numeral 17 denotes a cover flange that covers one surface of the first body 1. Reference numeral 18 denotes a measurement chamber provided in the second body 3. 19 is a main body provided in the measurement chamber 18. Reference numeral 21 denotes a measurement diaphragm provided in the main body 19 and dividing the measurement chamber 18 into first and second measurement chambers 22 and 23.

Reference numeral 24 denotes a third communication hole which is provided in the second body 3 and communicates the first measurement chamber 22 and the first center chamber 6. Reference numeral 25 denotes a detection sensor for detecting displacement or distortion of the measurement diaphragm 21 as shown in FIG. In this case, a semiconductor piezoresistive element is used. 26 is
To support the main body 19 in the measurement chamber 18 with a gap,
One end is connected to the main body 19, the middle is fixed to the second body 3, the other end is connected to the first body 1, and one end is a support pipe communicating with the first measurement chamber 22. Reference numeral 27 denotes a fourth communication hole provided in the first body 1 and communicating the other end of the support pipe 26 with the second seal chamber 12.

Reference numerals 101 and 102 denote sealing chambers 11 and 12,
It is a liquid filled in each of two chambers including the communication holes 15, 16, 24, 27, the center chambers 6, 7, the measurement chambers 22, 23, and the support pipe 26. Reference numeral 31 denotes a printed board provided on the second body 3, and a lead of the detection sensor 25.
To connect the terminal to the hermetic terminal 32. In this case, it is made of ceramics.

Reference numeral 33 denotes a protection plate made of ceramics provided in contact with the printed board 31 for protecting the printed board 31 and the center diaphragm 5 when an excessive pressure is applied to the center diaphragm 5. . 34
Is an O-ring for sealing the first body 1 and the cover flange 17.

In the above configuration, the differential pressure applied to the seal diaphragms 8, 9 is transmitted to the measurement chamber 18 via the communication holes 15, 24, 27, and displaces the measurement diaphragm 21. The displacement or strain of the measurement diaphragm, which is proportional to the differential pressure, is detected by a detection sensor and converted into an electric signal.

When an overpressure is applied, the overpressure protection mechanism (center diaphragm 5) moves, the seal diaphragm sits on the first body 1, and no overpressure exceeding a certain level is applied to the measurement diaphragm 21.

As a result, (1) two seal diaphragms 8 and 9 are provided on one surface side of the first body 1, and the seal diaphragms 8 and 9 are provided from the other surface side of the first body 1. Since the detection sensor portion is provided close to the pressure sensor portion, the pressure receiving portion and the pressure sensor portion can be arranged close to each other, the amount of the filled liquids 101 and 102 can be reduced, and the one having good temperature characteristics can be obtained. can get.

(2) Since the pressure receiving portion and the pressure sensor portion can be arranged close to each other, it is easy to reduce the size. (3) Cover flange 1 only on one side of first body 1
7, the influence of the tightening force of the cover flange is less than in the case where the cover flange is tightened from both sides of the main body, and zero and span fluctuations hardly occur.

(4) When the cover flanges are tightened from both sides, the cover tightening force for tightening the main body fluctuates due to the high static pressure of the measurement fluid, and zero and span fluctuations occur. In the present invention, only on one surface side of the first body 1,
Since the cover flange 17 is mounted, the cover flange 17 is only loosened by the high static pressure of the measurement fluid.
There is no effect on the main body, and zero and span fluctuations do not occur.

FIG. 3 is an explanatory diagram of a main part configuration of another embodiment of the present invention. In the present embodiment, electrodes 43 and 44 are provided on the main body substrate 41 and the measurement diaphragm 42, and are of an electrostatic capacitance type that detects displacement of the measurement diaphragm 42 as a change in capacitance. FIG. 4 is an explanatory diagram of a main part configuration of another embodiment of the present invention. In the present embodiment, reference numeral 51 denotes a center diaphragm having a thermal expansion coefficient larger than that of the bodies 1 and 3. Generally, when the temperature rises, the filling liquids 101 and 102 expand. In this case, the seal diaphragms 8 and 9 are seated on the body 1 when an excessive pressure is applied, and the pressure of the filling liquids 101 and 102 increases. To prevent this, the center diaphragm 5 must be displaced (the volume change constant is larger) than at room temperature.

In this embodiment, the coefficient of thermal expansion of the center diaphragm 51 is set to be larger than the coefficient of thermal expansion of the bodies 1 and 3. Therefore, when the temperature rises, the difference in the coefficient of thermal expansion between the center diaphragm 51 decreases. The volume change constant increases. As a result, the overpressure applied to the measurement diaphragm at a high temperature is not so large as at a normal temperature, and the overpressure protection mechanism works effectively even at a high temperature.

In the above-described embodiment, the detection sensor 25 has been described as a resistance detection type or a capacitance type. However, the present invention is not limited to this.
A vibration method may be used. In short, any method may be used as long as the displacement or strain of the measurement diaphragm 21 can be detected.

[0035]

As described above, according to the first aspect of the present invention, a block-shaped first body having a concave portion is provided.
A second body constituting a fixed recess and the center chamber in the recess, first the center chamber, and a center diaphragm separating the second center chamber, respectively the body is provided on one side of the first body Seal diaphragms forming first and second seal chambers, a backup nest provided on the first body facing the seal diaphragm, and the first seal provided on the first body. A first communication hole communicating the seal chamber with the first center chamber, a second communication hole provided in the first body and communicating the second seal chamber with the second center chamber; Cover that covers one side of the first body
A flange, a measurement chamber provided in the second body, a main body provided in the measurement chamber, a measurement diaphragm provided in the main body and dividing the measurement chamber into first and second measurement chambers, A third communication hole provided in the body for communicating the first measurement chamber with the first center chamber, a detection sensor for detecting displacement or distortion of the measurement diaphragm, and a main body which is separated from the measurement chamber by a gap. a support pipe middle one end to the body is connected in communication with the first measuring chamber other end is fixed to the second body connected to the first body so as to support, provided in the first body A fourth communication hole for communicating the other end of the support pipe with the second seal chamber ;
The second sheet - le chamber, fourth communication hole from a first, center chamber, measuring chamber, differential pressure, characterized by comprising a sealed liquid encapsulated respective two chambers constituted by the support pipe A measuring device was configured.

According to a second aspect of the present invention , there is provided a differential pressure measuring apparatus according to the first aspect, further comprising a center diaphragm having a thermal expansion coefficient larger than a thermal expansion coefficient of the body.

As a result, (1) two seal diaphragms are provided on one surface side of the first body, and a detection sensor portion is provided from the other surface side of the first body in proximity to the seal diaphragm. As a result, the pressure receiving portion and the pressure sensor portion can be arranged close to each other, the amount of the sealed liquid can be reduced, and a good temperature characteristic can be obtained.

(2) Since the pressure receiving portion and the pressure sensor portion can be arranged close to each other, the size can be easily reduced. (3) Since the cover flange is mounted only on one side of the first body, the influence of the tightening force of the cover flange is smaller than in the case where the cover flange is tightened from both sides of the body, and zero and span Fluctuation is unlikely to occur.

(4) When the cover flanges are tightened from both sides, the cover tightening force for tightening the main body fluctuates due to the high static pressure of the measuring fluid, and zero and span fluctuations occur. In the present invention, since the cover flange is mounted only on one surface side of the first body, the cover flange is only loosened by the high static pressure of the measurement fluid, and the main body is not affected. No span fluctuation occurs.

Further, according to the second aspect, the coefficient of thermal expansion of the center diaphragm is set to be larger than the coefficient of thermal expansion of the body. Therefore, when the temperature rises, the difference in the coefficient of thermal expansion between the center diaphragm decreases and the volume change of the center diaphragm decreases. The constant increases. As a result, the overpressure applied to the measurement diaphragm at a high temperature is not so large as at a normal temperature, and the overpressure protection mechanism works effectively even at a high temperature.

Therefore, according to the present invention, it is possible to realize a differential pressure measuring device in which the temperature characteristics are improved by reducing the amount of the filled liquid, the size is reduced, and the influence of the cover flange tightening force is small.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of parts shown in FIG. 1;

FIG. 3 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

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

FIG. 5 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st body 2 ... recessed part 3 ... 1st body 4 ... Center room 5 ... Center diaphragm 6 ... 1st center room 7 ... 1st center room 8, 9 ... Seal diaphragm 11 ... 1st seal room 12 ... Second seal chambers 13,14 ... Backup nest 15 ... First communication hole 16 ... Second communication hole 17 ... Cover flange 18 ... Measurement chamber 19 ... Main body 21 ... Measurement diaphragm 22 ... First measurement chamber 23 ... First 2 measurement chamber 24 ... third communication hole 25 ... detection sensor 26 ... support pipe 27 ... fourth communication hole 31 ... printed board 32 ... hermetic terminal 33 ... protection plate 34 ... O-ring 41 ... body substrate 42 ... measurement diaphragm 43 , 44 ... Electrode 51 ... Center diaphragm 101, 102 ... Filled liquid.

Claims (2)

(57) [Claims] 1. A and the block-shaped first body having a recess, and a second body constituting a fixed recess and the center chamber in the recess, the center diaphragm separating the center chamber to the first, second center chamber When, the body and the first respectively provided on one surface side of the first body, a second sheet - and Le diaphragm,該Shi - - sheet constituting the Le chamber is opposite the Le diaphragm provided in the first body A backup nest; a first seal chamber provided in the first body;
A first communication hole communicating with a center chamber; a second seal chamber provided in the first body;
A second communication hole communicating with the center chamber; a cover flange covering one surface of the first body; a measurement chamber provided in the second body; a main body provided in the measurement chamber; A measurement diaphragm provided in the second body for dividing the measurement chamber into first and second measurement chambers; a third communication hole provided in the second body for communicating the first measurement chamber with the first center chamber; a detection sensor for detecting the displacement or strain of the diaphragm, the body communicating with the way the second body to the first measuring chamber at one end is connected to the body as to support keeping a clearance to the measurement chamber a support pipe which other end is fixed is connected to the first body, the other end of the support pipe and the second sheet is provided on the first body - and the fourth communication hole for communicating the Le chamber, said first 1, second sheet - le chamber, fourth communication hole from a first, center chamber Measuring chamber, a differential pressure measuring device, characterized by comprising a sealed liquid encapsulated respective two chambers constituted by the support pipe. 2. The differential pressure measuring device according to claim 1, further comprising a center diaphragm having a thermal expansion coefficient larger than a thermal expansion coefficient of said body.