JPH0749397Y2 - Differential pressure transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a capacitance type differential pressure measuring device.

(Prior Art) Next, a conventional example will be described with reference to the drawings. FIG. 2 is a sectional configuration diagram of a main part of a conventional differential pressure transmitter.

In the figure, 1 is a sensor housing and 2 is an alumina block provided in the sensor housing 1 and having a third chamber 3 formed therein. A differential pressure sensor 4 is provided in the third chamber 3.
Is provided.

The differential pressure sensor 4 is composed of a main diaphragm 5 acting as a moving electrode, and fixed electrodes 6 and 7 provided on both sides of the main diaphragm.

Reference numeral 8 is a pressure receiving body that is connected to the sensor housing 1. A first chamber 10 and a second chamber 11 partitioned by a center diaphragm 9 are formed in the pressure receiving body 8. A first backup nest 12 is provided on the corrugated open surface of the first chamber 10, and a second backup nest 13 is provided on the corrugated open surface of the second chamber 11. ing. And backup nest 12,1
A first seal diaphragm 14 and a second seal diaphragm 15 are provided so as to be opposed to 3.

Further, first and second annular diaphragms 16 and 17 are provided on the outer edges of the first and second seal diaphragms 14 and 15, respectively.

Reference numeral 18 is a first communication hole provided so as to communicate with the differential pressure sensor 4 from the first chamber 10, and 19 is a second communication hole provided so as to communicate with the differential pressure sensor 4 from the second chamber 11. is there. 20 is the first
Of the annular diaphragm 16 and the pressure-receiving body 8 and a third communication hole for communicating the third chamber 3 with each other, and 21 is a second communication hole.
Is a fourth communication hole that communicates the gap formed by the annular diaphragm 17 and the pressure-receiving body 8 with the third chamber 3.

Then, the first to third chambers 10, 11, 3 and the first to fourth communication holes 18, 19, 20, 21 are filled with a filling liquid (for example, silicone oil) 22.

Reference numeral 23 is a flange attached to the pressure receiving body 8 via a packing 24.

Next, the operation of the above configuration will be described. Seal diaphragm
The pressure applied to 14, 15 is transmitted to the differential pressure sensor 4 via the first and second communication holes 18, 19. Then, the main diaphragm 5 of the differential pressure sensor 4 is displaced. A displacement proportional to the pressure difference is detected as a change in capacitance between the measurement diaphragm 5 and the fixed electrodes 6 and 7, and converted into an electric signal.

When a high static measurement pressure is applied, high static pressure is applied to the seal diaphragms 14 and 15, and high static pressure is also applied to the annular diaphragms 16 and 17, so that the third and fourth communication holes 2
Since the static pressure is applied to the third chamber 3 via 0, 21, the differential pressure sensor 4 is kept in static pressure, and the main diaphragm 5 is not distorted due to static pressure. No span variation due to pressure occurs.

On the other hand, when an excessive pressure is applied, the center diaphragm 9 is deformed and absorbs the moving amount of the high pressure side filled liquid 22. And the seal diaphragm 14 or 15 is the backup nest 12 or
By being seated at 13, the enclosed liquid 22 will no longer move and the main diaphragm 5 will not be overpressured and will therefore be protected from overpressure.

(Problems to be Solved by the Invention) In the conventional example having the above configuration, the seal diaphragms 14, 15
The annular diaphragms 16 and 17 are provided on the outer edge of the. Therefore, there is a problem that the seal diaphragms 16 and 17 are not effectively used. That is, when the diameters of the seal diaphragms 14 and 15 that receive the measurement pressure are small, the volume change constant of the diaphragm is small and the spring constant is large. Therefore,
Seal diaphragm 14, 15 by tightening flange 23
The zero-point span change due to the deformation becomes large, and the drift of the differential pressure sensor 4 becomes large. Further, since the volume change constant of the diaphragm is small, the temperature error caused by the imbalance of the left and right enclosed liquids 22 becomes large. Further, the temperature error and the static pressure error due to the deformation of the center diaphragm 9 also become large.

The present invention has been made in view of the above problems, and an object thereof is to provide a differential pressure transmitter that effectively uses a seal diaphragm and is less affected by disturbance.

(Means for Solving the Problems) In the present invention for solving the above problems, a third chamber provided in a sensor housing, a differential pressure sensor provided in the third chamber, and the sensor housing are connected to the sensor housing. And a first chamber and a second chamber partitioned by a center diaphragm provided in the pressure-receiving body, and first and second chambers provided on the respective open surfaces of the first and second chambers. Two
And the first and second sealing diaphragms, which are provided on the respective open surfaces of the first and second chambers so as to cover the annular diaphragm and receive a measurement pressure, and the first chamber and the differential chamber. A first communication hole provided so as to communicate with the pressure sensor, a second communication hole provided so as to communicate with the differential pressure sensor from the second chamber, the first annular diaphragm and the pressure receiving portion. A third communication hole that communicates the gap formed by the body and the third chamber, and a fourth communication that communicates the gap formed by the second annular diaphragm and the pressure receiving body with the third chamber. And a filling liquid filling the first to third chambers and the first to fourth communication holes.

(Operation) In the differential pressure transmitter of the present invention, since the seal diaphragm that receives the measurement pressure is provided so as to cover the annular diaphragm, the diameter of the seal diaphragm increases.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional configuration diagram illustrating an embodiment of the present invention.

In this figure, 31 is a sensor housing, and 32 is an alumina block provided in the sensor housing 31 and having a third chamber 33 formed therein. In this third chamber 33, the differential pressure sena
34 are provided.

The differential pressure sensor 34 is composed of a main diaphragm 35 acting as a moving electrode, and fixed electrodes 36, 37 provided on both sides of the main diaphragm.

Reference numeral 38 is a pressure receiving body that is connected to the sensor housing 31. A first chamber 40 and a second chamber 41 partitioned by a center diaphragm 39 are formed in the pressure receiving body 38. A first backup nest 42 is provided on the corrugated open surface of the first chamber 40, and a second backup nest 43 is provided on the corrugated open surface of the second chamber 41. ing. Then, the first and second chambers 40 and 41
First and second annular diaphragms 44, 45 are provided in the vicinity of the outer periphery of the open surface. Then, first and second sealing diaphragms 46, 47 are provided so as to cover these annular diaphragms 44, 45.

Reference numeral 48 is a first communication hole provided so as to communicate with the differential pressure sensor 34 from the first chamber 40, and 49 is a second communication hole provided so as to communicate with the differential pressure sensor 34 from the second chamber 41. . Reference numeral 50 is a third communication hole that communicates the gap formed by the first annular diaphragm 46 and the pressure receiving body 38 with the third chamber 33, and 51 is formed by the second annular diaphragm 47 and the pressure receiving body 38. It is a fourth communication hole that communicates the gap with the third chamber 33.

The first to third chambers 40, 41, 33 and the first to fourth communication holes 48, 49, 50, 51 are filled with a filling liquid (for example, silicone oil) 52.

Further, 53 is a flange attached to the pressure receiving portion body 38 via the packing 54.

Next, the operation of the above configuration will be described. Seal diaphragm
The respective pressures applied to 46 and 47 are transmitted to the differential pressure sensor 34 via the first and second communication holes 48 and 49. Then, the main diaphragm 35 of the differential pressure sensor 34 is displaced. Diaphragm for measuring displacement proportional to the differential pressure of measured pressure
Detected as a change in capacitance between 35 and fixed electrodes 36, 37,
Convert to electrical signal.

When a high static pressure is applied, a high static pressure is applied to the seal diaphragms 46 and 47 and a high static pressure is applied to the annular diaphragms 44 and 45, so that the third and fourth communication holes 5
Since a static pressure is applied to the third chamber 33 via 0, 51, the differential pressure sensor
34 is to be placed under static pressure, the main diaphragm
No strain due to static pressure is generated in 35, so that span fluctuation due to static pressure does not occur.

On the other hand, when an excessive pressure is applied, the center diaphragm 39 is deformed and absorbs the movement amount of the high-pressure side enclosed liquid 52. The seal diaphragm 46 or 47 is replaced by the backup nest 42 or
By sitting on 43, the enclosed liquid 52 will no longer move and the main diaphragm 35 will not be overpressured and will therefore be protected from overpressure.

According to the above configuration, since the seal diaphragms 46, 47 that receive the measurement pressure are provided so as to cover the annular diaphragms 44, 45, the diameter of the seal diaphragms is expanded and the seal diaphragms 46, 47 are effectively used. . Therefore,
The volume change constant of the diaphragm is large and the spring constant is small. The volume change constant of the diaphragm increases in proportion to the sixth power of the diameter, and the spring constant is inversely proportional to the fourth power of the diameter.

Therefore, the zero point span change due to the deformation of the seal diaphragms 46 and 47 due to the tightening of the flange 53 is small,
The drift of the differential pressure sensor 34 is reduced. Further, since the diaphragm has a large volume change constant, the temperature error caused by the imbalance of the left and right enclosed liquids 52 is reduced. Further, the temperature error and the static pressure error due to the deformation of the center diaphragm 39 are also reduced.

(Effects of the Invention) As described above, according to the present invention, the seal diaphragm that receives the measurement pressure is provided so as to cover the annular diaphragm, so that the seal diaphragm can be effectively used.
It is possible to realize a differential pressure transmitter that is less affected by disturbance.

[Brief description of drawings]

FIG. 1 is a sectional configuration diagram for explaining an embodiment of the present invention, and FIG. 2 is a sectional configuration diagram of a main part of a conventional differential pressure transmitter. In these drawings, 1,31 ... Sensor housing 3,33 ... Third chamber, 4,34 ... Differential pressure sensor 5,35 ... Main diaphragm 8,38 ... Pressure receiving body 9,39 ... Center diaphragm 10, 40 ... 1st chamber, 11, 41 ... 2nd chamber 12,42 ... First backup nest 13,43 ... Second backup nest 14,46 ... First seal diaphragm 15,47 ... Second seal diaphragm 16,44 ... 1st annular diaphragm 17,45 ... 2nd annular diaphragm 18,48 ... 1st communicating hole 19,49 ... 2nd communicating hole 20,50 ... 3rd communicating hole 21,51 ... 4th communicating hole , 22,52 ... Filled liquid

Claims (1)

[Scope of utility model registration request] 1. A third chamber (33) provided in the sensor housing (31), a differential pressure sensor (34) provided in the third chamber (33), and the sensor housing (31). A first chamber (40) and a second chamber (4) partitioned by a pressure receiving body (38) that is continuously provided and a center diaphragm (39) provided in the pressure receiving body (38).
1) and the first and second annular diaphragms (44, 4) provided on the open surfaces of the first and second chambers (40, 41), respectively.
5) and the first and second sealing diaphragms, which are provided on the open surfaces of the first and second chambers (41, 40) so as to cover the annular diaphragms (44, 45) and receive the measurement pressure. (46, 47), a first communication hole (48) provided so as to communicate with the differential pressure sensor (34) from the first chamber (40), and the differential chamber from the second chamber (41). A second communication hole (49) provided so as to communicate with the pressure sensor (34), the first annular diaphragm (44) and the pressure receiving body (3).
A third communication hole (50) for communicating the gap formed by 8) with the third chamber (33), the second annular diaphragm (45) and the pressure receiving body (3).
A fourth communication hole (51) that communicates the gap formed by 8) with the third chamber (33), the first to third chambers (40, 41, 33) and the first to fourth chambers. A differential pressure transmitter, comprising: a filling liquid (52) filling the communication holes (48, 49, 50, 51) of.