JP4186824B2 - Differential pressure measuring device - Google Patents

Description

  The present invention relates to a pressure receiving portion of a differential pressure measuring device, and more particularly to a differential pressure measuring device that can be easily manufactured and can be manufactured at low cost.

  Prior art documents related to the differential pressure measuring device include the following.

JP 2003-214969 A

Due to intensifying competition internationally, cost reduction of differential pressure measuring devices is urgently needed.
Until now, in order to reduce the number of parts, methods such as one-piece machining and one-piece molding have been adopted. However, as the production base is moved to a low-cost country, “use easily available materials” and “strict even if it takes time and effort. It is required to adopt a construction method that does not require quality control.
The present invention relates to a pressure receiving portion of a differential pressure measuring device, and realizes a structure in which an easily available material can be used.

  The differential pressure measuring device 10 in the prior art has a structure including an overpressure preloading diaphragm that detects an overpressure when an overpressure is applied to the high pressure side and low pressure side diaphragm portions. As shown in FIG. 6, the pressure detection unit 11 converts the pressure from the pressure difference between the high pressure and the low pressure from the process into an electric signal, and an electric circuit that amplifies the signal generated by the pressure detection unit 11. It consists of an amplifying unit 12.

  The pressure detection unit 11 includes a high pressure side flange 13 that forms a high pressure introduction unit that introduces a high pressure, a low pressure side flange 14 that forms a low pressure introduction unit that introduces a low pressure, and the high pressure side flange 13, It comprises a pressure receiving portion 15 that detects a high pressure and a low pressure from the low pressure side flange 14 with a diaphragm, and the high pressure side and low pressure side flanges 13, 14 are engaged with a nut 16 and a bolt 17.

As shown in FIG. 7, the pressure receiving portion 15 includes a body 21 having an upper middle position formed in a narrow neck shape, a sensor portion 23 locked by a ring 22 at an upper central position of the body 21, The high pressure side diaphragm portion 24 and the low pressure side diaphragm portion 25 which are arranged at the lower position facing each other and facing outward, and inside the body 21, the sealed liquid from the high pressure side diaphragm portion 24 is detected by the sensor. The high pressure side sealed liquid transmission hole 26 for transmitting to the part 23 and the low pressure side sealed liquid transmission hole 27 for transmitting the sealed liquid from the low pressure side diaphragm part 25 to the sensor part 23 are configured.
Hereinafter, details of each component will be described.

  The sensor unit 23 has a sensor attached to a terminal 28, and a differential pressure sensor 29 that detects a differential pressure by applying a pressure on the high-pressure side from the top and a pressure on the low-pressure side from the bottom, and the differential pressure sensor 29 It consists of a pair of hermetic terminals 30a, 30b electrically connected by wire bonding. The pair of hermetic terminals 30a and 30b communicate with the amplifying unit 12 shown in FIG.

  The high pressure side diaphragm portion 24 has a high pressure side liquid contact portion 31 in which the side wall surface of the body 21 is formed in a concave curved surface shape, and a concave curved surface deeper than the concave curved surface, and is arranged in close contact with the concave curved surface of the body 21. The high pressure side overpressure preloading diaphragm 32 has a predetermined space with the high pressure side overpressure preloading diaphragm 32 and covers the high pressure side overpressure preloading diaphragm 32, and has a high pressure outside the outer peripheral end. A planar high pressure side provided with an inlet of a hole (high pressure side conduction hole) for transmitting the side sealing liquid 33 and disposed so as to face the outside so as to shield the concave curved high pressure side liquid contact portion 31 from the outside. The seal diaphragm 34 is composed of a high pressure side overfilling liquid 33 for filling the space between the high pressure side overpressure preloading diaphragm 32 and the high pressure side seal diaphragm 34.

  The low pressure side diaphragm portion 25 is formed on the side opposite to the high pressure side diaphragm portion 24, and has a low pressure side liquid contact portion 35 in which the side wall surface of the body 21 is formed in a concave curved surface shape, and a concave curved surface deeper than the concave curved surface, The low pressure side overpressure preloading diaphragm 36 disposed in close contact with the concave curved surface of the body 21 and the low pressure side overpressure preloading diaphragm 36 have a predetermined space and cover the low pressure side overpressure preloading diaphragm 36. In addition, an inlet of a hole (low-pressure side conduction hole) for transmitting the low-pressure side sealed liquid 37 is provided outside the outer peripheral end portion, and the concave-shaped low-pressure side liquid contact portion 35 is externally shielded from the outside. A low-pressure side seal diaphragm 38 having a planar shape disposed so as to face, and a low-pressure side seal for transmission filled in a space between the low-pressure side overpressure preloading diaphragm 36 and the low-pressure side seal diaphragm 38. Consisting of liquid 37..

  The high-pressure side sealed liquid transmission hole portion 26 includes a high-pressure side conduction hole 39 that communicates with the high-pressure side liquid contact portion 31 at an outer peripheral end portion of the high-pressure side overpressure preloading diaphragm 32, and the high-pressure side conduction hole 39. The high pressure side sensor conduction hole 40 for transmitting the high pressure side sealed liquid 33 to the sensor portion 23 and the high pressure side conduction hole 39 are communicated with each other, and the substantially central position of the low pressure side overpressure preloading diaphragm 36 is pushed from behind. The high-pressure side overpressure conduction hole 41 is arranged as described above.

The low-pressure-side sealed fluid transmission hole 27 includes a low-pressure side conduction hole 42 that communicates with the low-pressure-side liquid contact portion 35 at an outer peripheral end portion of the low-pressure side overpressure preloading diaphragm 36, and the low-pressure side conduction hole 42. The low pressure side sensor conduction hole 43 that transmits the low pressure side sealed liquid 37 to the sensor unit 23 and the low pressure side conduction hole 42 are also communicated, and the substantially central position of the high pressure side overpressure preloading diaphragm 32 is pushed from behind. The low pressure side overpressure conduction hole 44 is arranged as described above.

  In the above configuration, particularly in the pressure receiving portion 15, as shown in FIG. 8, for example, when the high pressure side seal diaphragm 34 receives pressure from the high pressure side process, the pressure is transmitted to the high pressure side sealing liquid 33, The transmitted pressure of the high-pressure side sealing liquid 33 passes through the high-pressure side conduction hole 39 and is supplied to the differential pressure sensor 29 of the sensor unit 23 via the high-pressure side sensor conduction hole 40.

At the same time, when the low-pressure side sealing diaphragm 38 receives pressure from the low-pressure side process, the pressure is transmitted to the low-pressure side sealing liquid 37, and the transmitted pressure passes through the low-pressure side conduction hole 42, and the low-pressure side sensor conduction hole. The differential pressure sensor 29 of the sensor unit 23 is supplied to the differential pressure sensor 29 through 43.
In this way, the pressure from the high pressure side and the low pressure side is transmitted by the sealing liquids 33 and 37, and the difference between them can be detected by the differential pressure sensor 29.

The overpressure preloading diaphragm is forcibly deformed from a concave surface shape in a natural state to a shallow concave surface by the body 21, and a load for returning to the natural state is provided by the elasticity of the overpressure preloading diaphragm. It is working.
Since the pressure from the process on the high-pressure side and the low-pressure side is within the permissible measurement range, even if the pressure transmitted through the high-pressure side overpressure conduction hole pushes the low-pressure side overpressure preloading diaphragm 36 from behind, the low-pressure side overpressure preloading The diaphragm 36 is not displaced by a load for returning to the natural state.

  In this way, by applying a load to the overpressure preloading diaphragm, the high pressure and low pressure side overpressure preloading diaphragms 32, 36 are not displaced, and the differential pressure between the high pressure and the low pressure from the process is detected. It can be done.

When an excessive pressure exceeding the allowable measurement range is applied to the high pressure side or the low pressure side, the overpressure transmitted from the back through the high pressure side overpressure conduction hole 41 or the low pressure side overpressure conduction hole 44 is the overpressure. Overcome the preloading diaphragm and displace the overpressure preloading diaphragm.
Due to this displacement, the liquid on the back side of the seal diaphragm moves, and the seal diaphragm comes into close contact with the overpressure preloading diaphragm.
When the seal diaphragm is in close contact with the overpressure preloading diaphragm, a larger overpressure is not transmitted to the sensor unit, and the sensor can be protected from the overpressure.

FIG. 9 shows a state when an excessive pressure is generated on the high pressure side, and it is assumed that a pressure exceeding an allowable range is applied to the high pressure side seal diaphragm 34 from the high pressure side process.
Then, the excessive pressure transmitted to the sealing liquid on the back side of the high pressure side seal diaphragm 34 pushes behind the low pressure side overpressure preloading diaphragm 36 through the high pressure side conduction hole 39 and the high pressure side overpressure conduction hole 41.
Since the overpressure is superior to the load applied to the low pressure side overpressure preloading diaphragm 36, the low pressure side overpressure preloading diaphragm 36 is displaced.
With this displacement, the high-pressure side sealed liquid 33 moves, the sealed liquid on the back side of the high-pressure side seal diaphragm 34 disappears, and the high-pressure side seal diaphragm 34 contacts the high-pressure side overpressure preloading diaphragm 32.
When the high-pressure side seal diaphragm 34 comes into contact with the high-pressure side overpressure pre-loading diaphragm, the filled liquid disappears on the back side of the high-pressure side seal diaphragm 34, so that no overpressure is transmitted to the sensor unit 23.

The overpressure when the high-pressure side seal diaphragm 34 is completely in contact with the high-pressure side overpressure preloading diaphragm 32 is designed to be equal to or lower than the breaking pressure of the sensor unit 23.
Further, the encapsulated liquids 33 and 37 are expanded and contracted depending on the temperature, but the seal diaphragms 34 and 38 and the overpressure preloading diaphragm 32 are below the breaking pressure of the sensor unit 23 in the entire operating temperature range of the differential pressure measuring device. , 36 is designed so that all of the sealed liquids 33 and 37 sealed between 36 and 36 move between the overpressure preloading diaphragms 32 and 36 and the liquid contact parts 31 and 35 of the body 21.
Thus, in the overpressure protection structure, the operation of the overpressure preloading diaphragms 32 and 36 is very important.

However, in such a device,
The diaphragm must be formed in advance in a concave shape having at least one corrugated shape (concave shape) in accordance with the concave shape on both side surfaces of the body, and the forming operation is difficult.
Both sides of the body have a concave shape, and if the diaphragm has a concave shape, a click operation is likely to occur as in the case of a disc spring, and an accurate operation is difficult to obtain.

  An object of the present invention is to solve the above-described problems, and an object thereof is to provide a differential pressure measuring device that is inexpensive and has stable characteristics.

In order to achieve such a problem, in the present invention, in the differential pressure measuring device of claim 1,
A high-pressure side and a low-pressure side seal diaphragm which are respectively provided to cover the back plate surface provided in the main body body and constitute a high-pressure side and a low-pressure side seal diaphragm chamber, and a high-pressure side conduction hole and a low pressure respectively communicated with the seal diaphragm chamber In the differential pressure measuring device having a side conduction hole,
A high pressure side and a low pressure side back plate surface that are convex outward, and the high pressure side back plate surface of the high pressure side seal diaphragm chamber is provided to constitute the high pressure side back plate surface and the low pressure side overpressure chamber, A flat high-pressure side pre-loading diaphragm pressed against the back plate surface and the low pressure side back plate surface of the low pressure side seal diaphragm chamber are provided to constitute the low pressure side back plate surface and the high pressure side overpressure chamber A flat low-pressure side pre-loading diaphragm pressed and attached to the back plate surface, a low-pressure side overpressure conduction hole provided in the main body body and communicating the low-pressure side overpressure chamber and the low-pressure side conduction hole; A high pressure side overpressure conduction hole provided in the main body body and communicating the high pressure side overpressure chamber and the high pressure side conduction hole; the high pressure side and the low pressure side preloading diaphragm; Differential pressure measuring device, characterized by comprising a provided a plate-shaped high-pressure side and the low-pressure side seal diaphragms respectively over the.

According to claim 2 of the present invention, in the differential pressure measuring device according to claim 1,
2. The differential pressure measuring device according to claim 1, wherein the pre-loading diaphragm is composed of a plurality of pre-loading diaphragms closely adhered to each other.

According to claim 3 of the present invention, in the differential pressure measuring device according to claim 2,
The pre-loading diaphragm is composed of a first pre-loading diaphragm and a second pre-loading diaphragm which are in close contact with each other.

As described above, according to the first aspect of the present invention, the following effects can be obtained.
Both the pre-loading diaphragm and the seal diaphragm are flat, eliminating the need for corrugation, resulting in a low-cost differential pressure measuring device that can be manufactured at low cost.
A symmetric structure can be easily obtained, and a differential pressure measuring device with stable characteristics can be obtained.
Since the preload diaphragm is flat, it is easy to match the shape with the back plate surface. When the input is within the measurement range, the preload diaphragm does not move in close contact with the body and the pressure transmission medium does not move. There can be obtained a differential pressure measuring device that can realize a high-speed response without a response delay due to resistance.

According to the second and third aspects of the present invention, the following effects can be obtained.
Since the preload diaphragm is composed of a plurality of preload diaphragms stacked in close contact with each other, the stress generated in each preload diaphragm can be reduced by a factor of several. Therefore, it is possible to manufacture an inexpensive differential pressure measuring device that can be manufactured with a commercially available low-cost material.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating the configuration of the main part of one embodiment of the present invention, and FIGS. 2 and 3 are diagrams illustrating the operation of FIG.
In the figure, the same symbol structure as in FIG. 7 represents the same function.
Only the differences from FIG. 7 will be described below.

The high-pressure side and the low-pressure side back plate surfaces 51 and 52 are convex outward.
The high-pressure side preloading diaphragm 53 is provided so as to cover the high-pressure side back plate surface 51 of the high-pressure side seal diaphragm chamber 54, and constitutes the high-pressure side back plate surface 51 and the low-pressure side overpressure chamber 55 and presses against the back plate surface 51. Mounted to form a flat plate.

The low-pressure side preloading diaphragm 56 is provided so as to cover the low-pressure side back plate surface 52 of the low-pressure side seal diaphragm chamber 57, and constitutes a low-pressure side back plate surface 52 and a high-pressure side overpressure chamber 58 and presses against the back plate surface 52. Mounted to form a flat plate.
The pre-loading diaphragms 53 and 54 have a flat plate shape before assembling, and have a convex shape by being pressed onto the back plate surfaces 51 and 52.

The low pressure side overpressure conduction hole 59 is provided in the main body 61 and communicates the low pressure side overpressure chamber 55 and the low pressure side conduction hole 42.
The high pressure side overpressure conduction hole 62 is provided in the main body 61 and communicates the high pressure side overpressure chamber 58 and the high pressure side conduction hole 39.
The high-pressure side and low-pressure side seal diaphragms 63 and 64 are provided so as to cover the high-pressure side and low-pressure side preloading diaphragms 53 and 56, respectively, and have a flat plate shape.

The high-pressure side seal diaphragm chamber 54 communicates with a high-pressure side conduction hole 39 provided in the body 61 just outside the high-pressure side preloading diaphragm 53, and a high-pressure side overpressure conduction hole provided inside the low-pressure side preloading diaphragm 56. 62 is connected to one of the differential pressure sensors 29.
A pressure transmission medium 101 is enclosed in a space formed by the high-pressure side seal diaphragm chamber 54, the high-pressure side conduction hole 39, and the high-pressure side overpressure conduction hole 62.

The low-pressure side seal diaphragm chamber 57 communicates with the low-pressure side conduction hole 42 provided in the body 61 just outside the low-pressure side preloading diaphragm 56, and the low-pressure side overpressure conduction hole provided inside the high-pressure side preloading diaphragm 53. 59 to the other end of the differential pressure sensor 29.
A pressure transmission medium 102 is enclosed in a space formed by the low pressure side seal diaphragm chamber 57, the low pressure side conduction hole 42, and the low pressure side overpressure conduction hole 59.
The two sets of passages do not cross each other.

In the above configuration, when pressure P is applied to the low pressure side, the pressure is transmitted to the pressure transmission medium 102 via the seal diaphragm 64, and the pressure P is transmitted to the differential pressure sensor 29 through the low pressure side conduction hole 42.
On the other hand, the low-pressure side pressure P pressurizes the high-pressure side preloading diaphragm 53 through the low-pressure side overpressure conduction hole 59.

Since the high pressure side preloading diaphragm 53 that is originally flat is deformed in a convex shape, the restoring force opposes the pressure P, and the high pressure side preloading diaphragm 53 is not displaced.
The convex shape is designed so that the restoring force of the preload diaphragms 53 and 56 corresponds to about twice the pressure Pmax of the maximum measurement range, and when the pressure of 2Pmax is applied, the preload diaphragms 53 and 56 start to be displaced.

Displacement of the high pressure side pre-loading diaphragm 53 moves the pressure transmission medium 101, and the low pressure side seal diaphragm 64 is also displaced.
When the pressure P exceeds 2Pmax and reaches about 3Pmax, the low-pressure side seal diaphragm 64 is seated on the low-pressure side preloading diaphragm 56 and is no longer displaced.

FIG. 2 shows a state where the low pressure side seal diaphragm 64 is seated on the low pressure side preloading diaphragm 56 and the high pressure side preloading diaphragm 53 is separated from the body 61.
Even if the pressure P exceeds about 3Pmax, the low-pressure side seal diaphragm 64 is in contact with the low-pressure side pre-loading diaphragm 56. Therefore, the pressure of the pressure transmission medium 101 does not rise above about 3Pmax, and the differential pressure sensor 29 is about 3Pmax. No more pressure.
The operation of the pre-weighted diaphragms 53 and 56 is represented in a graph as shown in FIG.

As a result,
Both the pre-loading diaphragms 53 and 56 and the seal diaphragms 63 and 64 are flat, so that no waveform forming is required, and a differential pressure measuring device that can be manufactured at low cost and can be realized at low cost is obtained.

A symmetric structure can be easily obtained, and a differential pressure measuring device with stable characteristics can be obtained.
Since the preload diaphragms 53 and 56 have a flat plate shape, the shape easily matches the shape of the back plate surfaces 51 and 52. When the input is within the measurement range, the preload diaphragms 53 and 56 do not move in close contact with the body 61. Since the pressure transmission media 101 and 102 do not move either, there is no response delay due to the pipe resistance, and a differential pressure measuring device capable of realizing a high-speed response is obtained.

FIG. 4 is an explanatory view showing the configuration of the main part of another embodiment of the present invention.
In the present embodiment, the high-pressure side pre-loading diaphragm 71 and the low-pressure side pre-loading diaphragm 72 are composed of a plurality of pre-loading diaphragms in close contact with each other.
In this case, the high-pressure side preloading diaphragm 71 includes a first preloading diaphragm 711 on the high-pressure side and a second preloading diaphragm 712 on the high-pressure side which are closely stacked.
The low-pressure side preloading diaphragm 72 includes a low-pressure side first preloading diaphragm 721 and a low-pressure side second preloading diaphragm 722 which are closely stacked.

In the above configuration, the preload diaphragms 53 and 56 of the embodiment of FIG. 1 are displaced away from the body 61 when a pressure exceeding 2Pmax is applied in this case. The stress σ1 generated in the diaphragms 53 and 56 is expressed by the following equation.
σ1 = (3/4) × E × r ² × 2Pmax ÷ t ²
Where, E: longitudinal elastic modulus of the pre-loaded diaphragm material,
r: radius,
t: thickness

Further, since the pressure at which the seal diaphragms 63 and 64 are seated on the preload diaphragms 53 and 56 is 3Pmax in this case, the stress σ2 generated in the preload diaphragms 53 and 56 at this time is σ2 = (3/4 ) × E × r ² × 3Pmax ÷ t ²
In order to withstand this stress, it is necessary to use a high-strength material for the pre-loaded diaphragms 53 and 56, which increases the cost.

In the embodiment of FIG. 4, since the pressure P is shared by the two diaphragms 711 and 712, the stress σ generated in the first pre-weighted diaphragms 711 and 721 is expressed by the following equation.
σ = (3/4) × E × r ² × (P / 2) ÷ t ²
The same stress is also generated in the second preloading diaphragms 721 and 722.
The stress σ3 when P = 2Pmax is
σ3 = (3/4) × E × r ² × (2Pmax / 2) ÷ t ²
As can be seen from the comparison with σ1, the generated stress is halved.

FIG. 5 shows a state where a pressure of 3Pmax is applied to the low pressure side, the seal diaphragm 64 on the low pressure side is seated on the second pre-loading diaphragm 722, and the first protective diaphragm 711 on the high pressure side is separated from the body 61. Yes.
Even when a pressure of 3 Pmax or more is applied to the low pressure side, the seal diaphragm 64 is in close contact with the second pre-loading diaphragm 722, so that no pressure exceeding 3 Pmax is transmitted to the differential pressure sensor 29, and the differential pressure sensor 29 Protected from excessive pressure.

As the pressure Pmax in the maximum measurement range of the differential pressure measuring device increases, the stress generated in the preload diaphragms 53 and 56 increases.
Stress σ = (3/4) × E × r ² × Pmax ÷ t ²
Where E: longitudinal elastic modulus,
r: Diaphragm radius,
t: thickness

In order to reduce the stress, it is sufficient to increase the thickness t of the preload diaphragms 53, 56. However, due to the restriction that the preload diaphragms 53, 56 must start to be displaced at 2Pmax, the thickness is increased unnecessarily. It is not possible.
For example, there is maraging steel having a tensile strength exceeding 1900 N / mm ² as a high-strength material, but the strength of a high-strength material is also limited and extremely expensive.

On the other hand, the tensile strength of SUS631 stainless steel, which is one of JIS standard materials, is 1100 N / mm ² , but it is highly marketable and inexpensive.
By using two or more pre-loading diaphragms, stress generated in the pre-loading diaphragm can be suppressed, and low-cost materials can be used.

  As a result, the preload diaphragm is composed of a plurality of preload diaphragms that are closely stacked, so that the stress generated in each preload diaphragm can be reduced by a factor of several, so that the preload diaphragm is increased. It can be manufactured with a commercially available low-cost material instead of a strength material, and an inexpensive differential pressure measuring device can be obtained.

  The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention. Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is principal part structure explanatory drawing of one Example of this invention. It is operation | movement explanatory drawing of FIG. It is operation | movement explanatory drawing of FIG. It is principal part structure explanatory drawing of the other Example of this invention. It is operation | movement explanatory drawing of FIG. It is principal part structure explanatory drawing of the prior art example generally used conventionally. It is principal part structure explanatory drawing of FIG. It is principal part structure explanatory drawing of FIG. It is operation | movement explanatory drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Differential pressure measuring apparatus 11 Pressure detection part 12 Amplification part 13 High pressure side flange 14 Low pressure side flange 15 Pressure receiving part 16 Nut 17 Bolt 21 Body 22 Ring 23 Sensor part 24 High pressure side diaphragm part 25 Low pressure side diaphragm part 26 High pressure side sealed liquid transmission Hole 27 Low-pressure side filled liquid transmission hole 28 Terminal 29 Differential pressure sensor 30a Hermetic terminal 30b Hermetic terminal 31 High-pressure side wetted part 32 High-pressure side overpressure pre-loading diaphragm 33 High-pressure side sealed liquid 34 High-pressure side seal diaphragm 35 Low-pressure side contact Liquid part 36 Low pressure side overpressure pre-loading diaphragm 37 Low pressure side filled liquid 38 Low pressure side sealing diaphragm 39 High pressure side conduction hole 40 High pressure side sensor conduction hole 41 High pressure side overpressure conduction hole 42 Low pressure side conduction hole 43 Low pressure side sensor conduction hole 44 Low pressure side overpressure conduction hole 51 High pressure Side backplate surface 52 Low pressure side backplate surface 53 High pressure side preloading diaphragm 54 High pressure side seal diaphragm chamber 55 Low pressure side overpressure chamber 56 Low pressure side preloading diaphragm 57 Low pressure side seal diaphragm chamber 58 High pressure side overpressure chamber 59 Low pressure side overpressure Pressure conduction hole 61 Main body body 62 High pressure side overpressure conduction hole 63 High pressure side seal diaphragm 64 Low pressure side seal diaphragm 71 High pressure side preload diaphragm 711 High pressure side first preload diaphragm 712 High pressure side second preload diaphragm 72 Low pressure side preloading diaphragm 721 Low pressure side first preloading diaphragm 722 Low pressure side second preloading diaphragm 101 Filling liquid 102 Filling liquid P Pressure

Claims (3)

A high-pressure side and a low-pressure side seal diaphragm which are respectively provided to cover the back plate surface provided in the main body body and constitute a high-pressure side and a low-pressure side seal diaphragm chamber, and a high-pressure side conduction hole and a low pressure respectively communicated with the seal diaphragm chamber In the differential pressure measuring device having a side conduction hole,
A high-pressure side and a low-pressure side back plate surface that are convex outward,
A flat high-pressure side pre-loading diaphragm which is provided so as to cover the high-pressure side back plate surface of the high-pressure side seal diaphragm chamber, constitutes the high-pressure side back plate surface and the low-pressure side overpressure chamber, and is pressed to the back plate surface. When,
A flat plate-like low-pressure side pre-loading diaphragm which is provided so as to cover the low-pressure side back plate surface of the low-pressure side seal diaphragm chamber, constitutes the low-pressure side back plate surface and the high-pressure side overpressure chamber, and is pressed to the back plate surface. When,
A low pressure side overpressure conduction hole provided in the main body body and communicating the low pressure side overpressure chamber and the low pressure side conduction hole;
A high-pressure side overpressure conduction hole provided in the main body body for communicating the high-pressure side overpressure chamber and the high-pressure side conduction hole; and a flat plate-like high-pressure side provided to cover the high-pressure side and the low-pressure side preloading diaphragm, respectively. And a low-pressure side seal diaphragm. The differential pressure measuring device according to claim 1, wherein the preloading diaphragm includes a plurality of preloading diaphragms that are closely stacked. The differential pressure measuring device according to claim 2, wherein the preloading diaphragm includes a first preloading diaphragm and a second preloading diaphragm which are closely stacked.

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