JPS5815049B2 - Differential pressure measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a differential pressure measuring device that electrically measures the difference in pressure (differential pressure) between two different fluids to be measured.

When two insulators are placed facing each other with one measurement diaphragm in between, metal foil is provided on each side of the insulator facing the measurement diaphragm, and different pressures are applied to both sides of the measurement diaphragm. A differential pressure measuring device which detects the resulting change in capacitance between a measuring diaphragm and a metal foil and measures the difference in pressure acting on both sides of the measuring diaphragm based on this capacitance change has already been filed by the same applicant. .

FIG. 1 is a schematic diagram of a conventional differential pressure measuring device having an overpressure protection function in this type of differential pressure measuring device, and FIG. 2 is a sectional view of the main part thereof.

In FIGS. 1 and 2, the differential pressure measuring device mainly includes a differential pressure sensing section 1, a first lid 2, and a second lid 3.

The first lid body 1 and the second lid body 2 each have a first pressure chamber 4 and a second pressure chamber 5. A second fluid to be measured having a pressure P2 is introduced into the second pressure chamber 5 via a second pressure introduction hole 7.

The first fluid to be measured and the second fluid to be measured may be liquids or gases.

The first lid 1 and the second lid 2 are fixed to the differential pressure sensing section 1 by means not shown.

Note that 3.9.40 is an O-ring.

The differential pressure sensing section 1 mainly includes a differential pressure transmitting section 8, a first casing 9, and a second casing 10.

A first cavity 11 and a second cavity 12 are formed in the first casing 9 and the second casing 10, respectively, and a first pressure receiving diaphragm 13 and a second pressure receiving diaphragm 14 are respectively formed on the surface opposite to these cavities. is provided.

The first pressure receiving diaphragm 13 forms a first pressure receiving chamber 15 together with the first casing 9, and the pressure P guided to the first pressure receiving chamber 4 is
1 is affected.

Further, the second pressure receiving diaphragm 14 is connected to the second casing 10.
Together with this, a second pressure receiving chamber 16 is formed, and is subjected to the action of the pressure P2 introduced into the second pressure chamber 5.

The first casing 9 and the second casing 10 are each formed symmetrically in plane, and have a first communication connection between the first cavity 11 and the first pressure receiving chamber 15 and between the second cavity 12 and the second pressure receiving chamber 16. A hole 17 and a second communication hole 18 are provided, respectively.

The differential pressure transmitter 8 consists of an auxiliary chamber and a measuring chamber M, as shown in detail in FIG.

The auxiliary chamber includes the first housing 19 and the first housing 1.
9, and the surfaces of the first housing 19 and the second housing 20 that face each other are each formed into a truncated spherical shape.

An auxiliary diaphragm 21 is disposed between the first housing 19 and the second housing 20, and the second housing 20 and this auxiliary diaphragm 21 form a first auxiliary chamber 22.
This auxiliary diaphragm 21 and the first housing 19 constitute a second auxiliary chamber 23.

In addition, the second c. A first fluid passage 24 that communicates between the first communication hole 17 and the first auxiliary chamber 22 and a first groove 26 that communicates the first internal space 25 and the first fluid passage 24, which will be described later, are formed in the puffer fish 20. has been done.

Similarly, the measurement chamber M is connected to the first housing 19 and this first housing 19.
Ha.

Third housing 2 attached to the right side of Ujifugu 19
A cavity is formed in each of the surfaces of the first housing 19 and the third housing 26 facing each other, and each cavity is filled with an insulator 27, 28 made of glass, porcelain, or the like. ing.

The surfaces of the insulators 27 and 28 facing each other are formed in a spherical shape, and a metal foil 2 serving as a capacitor plate is placed on the spherical surface.
9.30 is provided.

A measuring diaphragm 31 is disposed between the first housing 19 and the third housing 26, the insulator 21 and the measuring diaphragm 31 constitute a first measuring chamber 32, and the insulator 28 and the measuring diaphragm 31 constitute a first measuring chamber 32. Two measurement chambers 33 are configured.

Note that the third housing 26 has a second communication hole 18 and a second communication hole 18 .
A second fluid path 34 communicating with the measurement chamber 33 and this second fluid path 34 communicate with the measurement chamber 33.
A second groove 36 is formed that communicates the fluid path 34 with a second internal space 35, which will be described later.

The first housing 19 includes a third fluid passage 3γ that communicates the first measurement chamber 32 and the first internal space 25, and a second auxiliary chamber 2.
3 and the second internal space 35 are formed.

The auxiliary diaphragm 21 is made of a material having a different rigidity than the measurement diaphragm 31.

Therefore, the auxiliary diaphragm 21 and the measuring diaphragm 31
When the same differential pressure is applied to both, the auxiliary diaphragm 21 is displaced more than the measuring diaphragm 31.

In that case, when an excessive pressure difference occurs, the auxiliary diaphragm 21 and the measuring diaphragm 31 are independently displaced to absorb the volume of the first pressure receiving chamber 15 or the second pressure receiving chamber 16, but this In the embodiment, the first pressure receiving diaphragm 13 or the second pressure receiving diaphragm 14 is brought into close contact with the first casing 9 or the second casing 10 before the measuring diaphragm 31 hits the insulator 28 or 27. The rigidity of the auxiliary diaphragm 21 is selected so that the volume of the first pressure receiving chamber 15 or the second pressure receiving chamber 16 can be absorbed mainly by displacement of the auxiliary diaphragm 21.

Thus, an auxiliary chamber is arranged in the first cavity 11 of the first casing 9, and a second cavity 12 of the second casing 10 is arranged.
a first casing 9, such that a measurement chamber M is disposed therein;
Crocodile part 36 of first housing 19 and second casing 1
0 is sandwich-bonded, a first internal space 25 is formed between the first casing 9 and the auxiliary chamber in the first cavity 11, and a first internal space 25 is formed between the second casing 10 and the auxiliary chamber in the second cavity 12. A second internal space 35 is defined between the chamber M and the chamber M.

Next, the functions of the above configuration will be explained.

Pressure P1. guided to the first pressure chamber 4 and the second pressure chamber 5.
When the differential pressure of P2 is within a predetermined measurement range, the measurement diaphragm 31 acts as a movable electrode and the metal foils 29 and 30 act as fixed electrodes, and the capacitance between them changes in proportion to the differential pressure. , is electrically extracted by means not shown.

Next, if the conduit or the like that leads the first fluid to be measured to the first pressure chamber 4 ruptures, the pressure P1 becomes zero, and the pressure P2 in the second pressure chamber 5 becomes excessive. In this case, the second pressure receiving diaphragm 14 comes into close contact with the second casing 10 before the measuring diaphragm 31 hits the insulator 27, and at that time, the sealed liquid corresponding to the volume of the second pressure receiving chamber 16 is filled with the fourth fluid. The auxiliary diaphragm 21 is displaced independently of the measuring diaphragm 31 so as to flow into the second auxiliary chamber 23 via the passage 38 .

Similarly, if a conduit or the like that leads the second fluid to be measured to the second pressure chamber 5 ruptures, the pressure P2 thereof becomes zero, and as a result, the pressure P1 in the first pressure chamber 4 becomes excessive. In this case, the first pressure-receiving diaphragm 13 comes into close contact with the first casing 9 before the measuring diaphragm 31 hits the insulator 28, and at that time, the sealed liquid corresponding to the volume of the first pressure-receiving chamber 15 reaches the first pressure-receiving chamber 15. The auxiliary diaphragm 21 is displaced independently of the measuring diaphragm 31 so as to flow into the first auxiliary chamber 22 via the fluid passage 24 .

In this way, depending on the rigidity of the auxiliary diaphragm 21, protection against excess pressure is provided by the first pressure receiving diaphragm 15 or the second pressure receiving diaphragm 16.

However, in the differential pressure measuring device having the above-mentioned differential pressure protection function, the measurement chamber M and the auxiliary chamber are formed to have approximately the same capacity.

Therefore, in order to select a desired rigidity of the auxiliary diaphragm 21 so that the displacement of the auxiliary diaphragm 21 can sufficiently absorb the capacity of the first pressure receiving chamber 15 or the second pressure receiving chamber 16 in the case of excessive pressure differential, Each time, a large number of experiments and a great deal of labor and expense are required.

Further, the first housing 19 is provided with a third fluid passage 37 and a fourth fluid passage 38.

This third fluid passage 37 is connected from the first measurement chamber 32 to the first
The holes from the diagonal direction from the peripheral edge of the first housing 19 located in the internal space 25 are formed by machining.

will be communicated.

Similarly, the fourth fluid passage 38 is connected from the second auxiliary chamber 23 to
The holes located in the second internal space 35 and extending from the peripheral edge of the first housing 19 in an oblique direction are communicated with each other by machining.

Moreover, such fluid passages 37 and 38 are long and difficult to manufacture.

In view of the above-mentioned points, the present invention eliminates the drawbacks of the prior art, provides a reliable protection function against differential pressure, and facilitates the selection of the rigidity of the auxiliary diaphragm that can maintain the characteristics of the measurement diaphragm. It is an object of the present invention to provide a differential pressure measuring device that is easy to manufacture.

According to the invention, such an object is achieved by providing a differential pressure transmitter having a measuring chamber and a measuring diaphragm which hermetically divides this measuring chamber into a first measuring chamber and a second measuring chamber, and an open internal space. an auxiliary chamber is formed between a first casing having an inner space in which the differential pressure transmitter is fixedly disposed, and the first casing attached to an opening side of the inner space of the first casing; a second casing; an auxiliary diaphragm that hermetically divides the auxiliary chamber into a first auxiliary chamber and a second auxiliary chamber; a second pressure receiving diaphragm which forms a second pressure receiving chamber on the outer surface of the casing and receives the pressure of the second measured fluid; and a second pressure receiving diaphragm which receives the pressure of the second measured fluid; A communication conduit that communicates a sealed liquid filled in a pressure receiving chamber and the second measurement chamber and a second auxiliary chamber, the first pressure receiving chamber, the internal space, the first auxiliary chamber, and the first measurement chamber, respectively. communicate,
and the second pressure receiving chamber and the second auxiliary chamber are communicated with each other, and the rigidity of the measuring diaphragm and the auxiliary diaphragm are selected as different from each other, and the change in volume of the auxiliary diaphragm is determined from the change in volume of the measuring diaphragm. This is achieved by making the pressure receiving diaphragm thick and protecting the pressure differential pressure by having each of the pressure receiving diaphragms come into close contact with the opposing walls.

Next, embodiments of the present invention will be described in detail based on the drawings.

FIG. 3 shows a schematic configuration diagram of an embodiment of the present invention.

In the figures, parts having the same functions as in FIGS. 1 and 2 are given the same reference numerals.

The differential pressure sensing section 41 mainly includes a differential pressure transmitting section 42, a first casing 43, and a second casing 44.

The first casing 43 has an open internal space 45 formed therein.

The differential pressure transmitter 42 is accommodated in this internal space 45 and is fixed to the first casing 43 by a mounting screw 47 of a presser plate 46 .

Note that the fixation is not limited to the presser plate 46, and may be fixed using screws or other means.

At this time, a cylindrical gap 48 is formed between the internal space 45 and the differential pressure transmitter 42.

Further, the first pressure receiving diaphragm 13 is provided on the surface opposite to the internal space 45 of the first casing 43, and forms the first pressure receiving chamber 15 between the first casing 43 and the first pressure receiving diaphragm 13.

The first pressure receiving chamber 15 and the gap 48 are communicated with each other through a communication hole 49 and a groove 50 .

Next, the second casing 44 is provided on the opening side of the internal space of the first casing 43, and is interposed between the second casing 44 and the first casing 43 to make the outside diameter equal. A second auxiliary chamber 53 is formed in a sealed manner on the side of the first auxiliary chamber 52 and the second casing 44 that communicate with the gap portion 48 .

Further, the second casing 44 is provided with a second pressure receiving diaphragm 14 on a surface opposite to the second auxiliary chamber 53, and forms a second pressure receiving chamber 16 between the second casing 44 and the second casing 44.

The pressure receiving chamber 16 and the second auxiliary chamber 53 are communicated with each other through a communication hole 54 .

The differential pressure transmitter 42 is composed of a first housing 55 and a second housing 56. A cavity is formed in each of the opposing surfaces of the first housing 55 and the second housing 56, and a cavity is formed in each of the cavities. It is filled with insulators 57 and 58 made of glass or porcelain.

The opposing surfaces of the insulators 57 and 58 are formed in a spherical shape, and a metal foil 29 serving as a capacitor plate is placed on the spherical surface.
．． 30 are provided.

Note that a measurement diaphragm 31 is arranged between the first housing 55 and the second housing 56, the insulator 51 and the measurement diaphragm 31 constitute a first measurement chamber 32, and the insulator 28 and the measurement diaphragm 31 constitute a first measurement chamber 32. A second measurement chamber 33 is configured.

Furthermore, the first housing 55 is formed with a communication hole 59 that communicates the internal space 45° and the first measurement chamber 32, and the second housing 56 is formed with a communication hole 59 that communicates the second auxiliary chamber 53 and the second measurement chamber 33. A communication hole 60 and a communication conduit 61 are formed.

One end of this communication conduit 61 is airtightly connected to the communication hole 60,
the other end.

It is airtightly connected to the auxiliary diaphragm 51 using a mounting bracket 62.

Note that, like the auxiliary diaphragm 21 in FIGS. 1 and 2 described above, the auxiliary diaphragm 51 is made of a material having a different rigidity from that of the measurement diaphragm 31.

Therefore, when differential pressure in the measurement range is applied, the auxiliary diaphragm 51 does not displace and the measurement diaphragm 3
1 and measure the pressure difference.

In that case, when an excessive pressure difference occurs, the auxiliary diaphragm 51 and the measuring diaphragm 31 are independently displaced to absorb the volume of the first pressure receiving chamber 15 or the second pressure receiving chamber 16, but the main In the embodiment, the measuring diaphragm 31 is connected to the insulator 5
7 or 58, the first pressure receiving diaphragm 13 or the second pressure receiving diaphragm 14 comes into close contact with the first casing 43 or the second casing 44, and therefore the first pressure receiving chamber 15 or the second pressure receiving chamber The volume of the chamber 16 is mainly the auxiliary diaphragm 5.
It is absorbed by a displacement of 1.

Note that spaces such as the first and second measurement chambers 32 and 33, the first and second auxiliary chambers 52 and 53, the gap 48, and the first and second pressure receiving chambers 15 and 16 are filled with silicone oil or the like. Filled with incompressible liquid, the communication hole 49 and the groove 5
0, the communication holes 59 and 60 and the communication conduit 61 are liquid passages for the sealed liquid.

Next, the functions of the above configuration will be explained.

Pressure P1. acting on the first and second pressure receiving diaphragms 13, 14. When the differential pressure at P2 is within a predetermined measurement range, the capacitance between the measuring diaphragm 31 and the metal foil 29, 30 increases the differential pressure, similar to the differential pressure measuring device in FIG. It changes proportionately and is taken out electrically.

Next, when the pressure P1 becomes zero and therefore the pressure P2 becomes excessive, the second pressure receiving diaphragm 14 comes into close contact with the second casing 44 before the measuring diaphragm 31 hits the insulator 57.

At this time, the auxiliary diaphragm 51 is displaced independently of the measurement diaphragm 31 so that the sealed liquid approximately equivalent to the volume of the second pressure receiving chamber 16 flows into the second auxiliary chamber 53 via the communication hole 54.

Similarly, if the pressure P2 becomes zero and therefore the pressure P1 becomes excessive, the first pressure-receiving diaphragm 13 contacts the first casing 43 before the measuring diaphragm 31 strikes the insulator 58. in close contact, and at that time, the first pressure receiving chamber 15
The sealed liquid approximately corresponds to the volume of the communication pipe 49 and the groove 50.
The auxiliary diaphragm 51 is connected to the measurement diaphragm 3 so as to flow into the first auxiliary chamber 52 through the gap 48.
It is displaced independently of 1.

In this way, the auxiliary diaphragm 51 is selected to have a much larger change in volume based on displacement with respect to pressure than the first and second pressure receiving diaphragms 13, 14 or the measuring diaphragm 31, so that when an excessive pressure difference occurs, the auxiliary diaphragm 51 is By a slight displacement of the auxiliary diaphragm 51, the volume of the enclosed liquid in the first or second pressure receiving chamber 15, 16 can be absorbed.

Therefore, selection of the rigidity of the auxiliary diaphragm 51 becomes easy.

Note that the communication holes 59 of the first and second housings 55 and 56
．． 60 is easily formed by machining to form a hole from its outer peripheral surface to the center, and by machining to form a hole from the spherical concave surfaces of the insulators 57 and 58 to the center.

Furthermore, as mentioned above, the auxiliary diaphragm 51 has a small displacement,
Since it has a protection function against excessive differential pressure, the function of the auxiliary diaphragm 51 is not affected even if the communication conduit 61 is airtightly fixed to the substantially peripheral edge of the auxiliary diaphragm 51 using the mounting bracket 62 by welding or other means. There are no problems.

Next, FIG. 4 shows a schematic configuration diagram of another embodiment of the present invention.

In the figure, parts having the same functions as in FIG. 3 are given the same reference numerals.

The differential pressure measuring device 70 includes a differential pressure transmitter 71 and a first casing 4.
3 and a second casing 44.

. The differential pressure transmitter 71 includes a first housing 72 made of a hollow metal cylinder, a fixing plate 73 provided on one side of the housing 72, and a measuring diaphragm 74 provided on the other side of the first housing γ2. , a second C provided on the outer surface of the measuring diaphragm 74.

It is composed of Uji Pufferfish 82.

Among these, the first housing 72 has an insulator 75 inside it.
is formed.

Both side surfaces 76 and γ1 of this insulator 15 are formed into round concave surfaces, and electrodes 78 made of metal foil are formed on the round concave surfaces.
79 are provided.

The metal fixing plate 73 connects this peripheral edge to the first housing γ.
A fixed chamber 80 is formed between the peripheral edge of one end surface of the insulator 2 and the side surface 76 of the insulator 15 in an airtight manner.

Next, the peripheral edge of the measuring diaphragm 74 is expanded into an annular shape, and this expanded peripheral edge is hermetically welded to the peripheral edge of the other end surface of the first housing 72 and is connected to the side surface 71 of the insulator 75. A first measurement chamber 81 is provided between the two.

Further, the outer peripheral edge of the measuring diaphragm 74 is hermetically welded to the peripheral edge of the second housing 82 and forms a second measuring chamber 83 therebetween.

In this way, the integrally configured differential pressure transmitter γ1 is housed in the internal space 45 of the first casing 43, and is mounted on the presser plate γ1.
4 and mounting screws 42, it is fixed within the first casing 43.

Next, the second casing 44 is provided so as to cover the internal space 45, and due to the auxiliary diaphragm 51 interposed between it and the first casing 43, the second casing 44 is placed on the first casing 43 side.
A second auxiliary chamber 53 is formed hermetically on the side of the first auxiliary chamber 52 and second casing 44 that communicate with the internal space 45 .

Furthermore, a communication hole 84 is provided in the insulator 75 between the fixed chamber 80 and the first measurement chamber 81 of the differential pressure transmitter T1, so that they communicate with each other.

The first pressure receiving chamber 15, the communication hole 49, the groove 50, the gap 48, the first auxiliary chamber 52, and the fixed chamber 80 of the first casing 43
A fixing plate 73 is provided between the communication hole 85 and the fixing plate 73 to communicate with each other.

Next, the second pressure receiving chamber 16 and the communication hole 5 of the second casing 44 are
A communication hole 86 provided in the second housing 82 and a communication conduit 61 are provided between the second measurement chamber 83 and the second auxiliary chamber 53 to communicate with each other.

This communication conduit 61 has one end hermetically fixed to the communication hole 86 and the other end hermetically fixed to the auxiliary diaphragm 51 with a fitting 62.

Furthermore, the fixed chamber 80, the first and second measurement chambers 81°83
, the first and second auxiliary chambers 52, 53, the first and second pressure receiving chambers 15, 16, and the gap 48 are each filled with an incompressible liquid such as silicone oil.
The communication holes 49, 54, 84°85.86, the groove 50 and the communication conduit 61 are liquid flow paths for the sealed liquid.

Next, the functions of the above configuration will be explained.

Pressure P1. acting on the first and second pressure receiving diaphragms 13, 14. The differential pressure at P2 provides a displacement to the measurement diaphragm 74 when it is within a predetermined measurement range.

This displacement causes a change in the capacitance C2 between the measuring diaphragm 74 and the metal foil T9.

On the other hand, the capacitance C1 between the metal foil 78 and the fixed plate 73 is constant and does not change.

This capacitance CI. By measuring the differential change in C2, the displacement of the measuring diaphragm 74 and thus the pressure P1. P
The differential pressure of 2 is measured.

Therefore, in the differential pressure measuring device 10 described above, just like the differential pressure measuring device 41 in FIG. Before hitting the housing 82 or the insulator 75, the first or second pressure receiving diaphragm 13, 14 contacts the first or second casing 43 or 4.
4, and at this time, the auxiliary diaphragm 51 is
is displaced independently of the measuring diaphragm 74.

In this way, the auxiliary diaphragm 51 is selected to have a much larger change in volume than the measurement diaphragm 74, making it easier to select a desired rigidity, and the first or second pressure receiving diaphragm 13, 14 allows The differential pressure measuring device 70 is protected from excessive pressure differentials.

According to the invention, as explained above, the volume change of the auxiliary diaphragm is selected to be large compared to the volume change of the measuring diaphragm.

Therefore, the desired rigidity of the auxiliary diaphragm can be easily selected, and the protection function against differential pressure can be reliably obtained, resulting in the effect that the characteristics of the measuring diaphragm can be maintained.

Incidentally, the special machining of the holes in the housing in the conventional example eliminates the need for special machining work and facilitates manufacturing.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a conventional differential pressure measuring device, FIG. 2 is a sectional view of the main part of FIG. 1, FIG. 3 is a schematic configuration diagram of an embodiment of the present invention, and FIG. It is a schematic block diagram of another implementation/example. 13...First pressure receiving diaphragm, 14...
...Second pressure receiving diaphragm, 31...Measuring diaphragm, 42.71...Differential pressure transmitter, 43.
...First casing, 44...Second casing, 45...Inner space, 48...
Gap part, 51...Auxiliary diaphragm, 52...
...First auxiliary room, 53...Second auxiliary room, 5
5゜72...First housing, 56.82...
...Second housing, 57, 58.75...
・Insulator, 61...Communication conduit, 73...
・Fixing plate, 74"...Measuring die; Yaphram, 78
,79... Electrode.

Claims (1)

[Claims] 1 A measurement chamber, a differential pressure transmitter having a measurement diaphragm that hermetically divides the measurement chamber into a first measurement chamber and a second measurement chamber, and an open internal space in which the differential pressure transmitter is installed. a first casing in which is fixedly disposed; a second casing that is attached to the opening side of the internal space of the first casing and forms an auxiliary chamber between the first casing; an auxiliary diaphragm that hermetically divides into an auxiliary chamber and a second auxiliary chamber; a first pressure receiving diaphragm that forms a first pressure receiving chamber on the outer surface of the first casing and receives the pressure of the first fluid to be measured; a second pressure receiving diaphragm that forms a second pressure receiving chamber on the outer surface of the second casing and receives the pressure of the second measured fluid; the measurement chamber, the auxiliary chamber;
The first pressure receiving chamber, the internal space, the first auxiliary chamber, and the first The measurement chambers are communicated with each other, and the second pressure receiving chamber and the second auxiliary chamber are communicated with each other, and the rigidity of the measurement diaphragm and the auxiliary diaphragm are different and selected as desired,
The differential pressure measuring device is characterized in that the volume change of the auxiliary diaphragm is made larger than the volume change of the measurement diaphragm, and the protection of excessive differential pressure is achieved by having each of the pressure receiving diaphragms in close contact with their opposing walls. .