JPH063212A - Differential measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a differential pressure measuring device in which the welding yield is improved together with the welding yield and the face-to-face distance can be configured to have substantially the same dimensions as the standard product. [Structure] A diaphragm having an outer peripheral portion fixed to a housing and nickel whose one surface is welded and fixed to a side surface of the housing at a distance from the outer peripheral fixed portion of the diaphragm to an outer peripheral fixed portion of the diaphragm. A ring-shaped main body ring made of nickel alloy, a liquid contact diaphragm made of tantalum, which is provided to cover the liquid diaphragm and is welded and fixed to the other surface of the main body ring so that no intermetallic compound is generated, and the housing and the main body ring. And a chamber formed by the liquid contact diaphragm and the liquid diaphragm, a sealing port provided in the housing, and a communication hole that has one end opened in the interval portion and connects the sealing port and the chamber. This is a differential pressure measuring device.

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 in which the welding yield is improved together with the welding yield, and the face-to-face distance can be configured to be approximately the same as that of a standard product.

[0002]

2. Description of the Related Art FIG. 8 is an explanatory view of the configuration of a conventional example which has been generally used, for example, in the actual construction of Sho 63-87536.
No. In the figure, a flange 2 and a flange 3 are detachably attached to both sides of a housing 1 by screwing. Both flanges 2 and 3 are provided with an inlet 5 for a high-pressure fluid having a pressure PH to be measured and an inlet 4 for a low-pressure fluid having a pressure PL. A pressure measuring chamber 6 is formed in the housing 1, and a center diaphragm 7 and a silicon diaphragm 8 are provided in the pressure measuring chamber 6.

The center diaphragm 7 and the silicon diaphragm 8 are individually fixed to the wall of the pressure measuring chamber 6, and the center diaphragm 7 and the silicon diaphragm 8 are separately fixed.
The pressure measuring chamber 6 is divided into two parts by both. Back plates 6A and 6B are formed on the wall of the pressure measuring chamber 6 facing the center diaphragm 7. The center diaphragm 7 has a peripheral edge portion welded to the housing 1. The silicon diaphragm 8 is entirely formed of a single crystal silicon substrate.

Impurities such as boron are selectively diffused on one surface of the silicon substrate to form four strain gauges 80.
The other side is machined and etched to form a generally concave diaphragm. The four strain gauges 80 are
When the silicon diaphragm 8 bends under the pressure difference ΔP,
Two are pulled and two are compressed,
These are connected to a Wheatstone bridge circuit, and a resistance change is detected as a change in the differential pressure ΔP.

The support 9 is provided with a hermetic terminal, and the silicon diaphragm 8 is adhesively fixed to the end face of the support 9 on the pressure measurement chamber 6 side by a method such as low-melting glass connection. Separating diaphragms 12, on both sides of the housing 1,
13 are provided. This diaphragm 12 and 1
A back plate having a shape similar to that of the diaphragms 12 and 13 is formed on the walls 10A and 11A of the housing 1 which face the housing 3.

The space formed by the diaphragms 12 and 13 and the back plates 10A and 11A and the pressure measuring chamber 6 are in communication with each other through communication holes 14 and 15. The filled liquids 101 and 102 such as silicone oil are filled between the diaphragms 12 and 13, and the filled liquids reach the upper and lower surfaces of the silicon diaphragm 8 through the communication holes 16 and 17. Although 102 is divided into two by the center diaphragm 7 and the silicon diaphragm 8, it is taken into consideration that the amounts are substantially equal.

Numerals 21 and 22 are liquid contact diaphragms whose peripheral portions are welded and fixed to the flanges 2 and 3 and on which the fluid pressures PH and PL on the measurement fluid side act. Wetted diaphragm 21,22
Is formed of a material having the corrosion resistance of tantalum. 103 and 104 are the diaphragms 12 and 13,
It is a sealed liquid sealed between the liquid contact diaphragms 21 and 22. Reference numerals 23 and 24 denote introduction passages for filling the filled liquids 103 and 104, the open ends of which are balls 25 and screws 2.
It is sealed by 6.

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the liquid contact diaphragm 22 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102. On the other hand, when pressure acts from the low pressure side, the pressure acting on the liquid contact diaphragm 21 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101. As a result, the silicon diaphragm 8 is distorted according to the pressure difference between the high pressure side and the low pressure side.

This strain amount is electrically taken out by the strain gauge 80, and the differential pressure is measured. Thus, in such a configuration, a standard product from the past can be used, and the flanges 2 and 3 having the liquid contact diaphragms 21 and 22 can be simply attached as side units. It is possible to obtain a differential pressure measuring device which can be commonly used and has excellent corrosion resistance.

[0010]

However, in such a device, (1) generally, the housing 1 and the flanges 2 and 3 are made of stainless steel. Tantalum is used for the liquid contact diaphragms 21 and 22 in order to improve the corrosion resistance, but the weldability between stainless steel and tantalum is not good. However, in order to cope with the highly corrosive measurement fluid, the current situation is that welding is performed with the preparation that the yield is not good. It is also conceivable to weld tantalum to stainless steel via nickel, but if tantalum and nickel are made to have the same melt penetration amount, a brittle intermetallic compound is produced, and the welding strength is reduced.

(2) The coefficient of thermal expansion of stainless steel is about 16 ×
10 ^-6 mm / mm ° C, coefficient of thermal expansion of tantalum is about 6 × 1
It was 0 ⁻⁶ mm / mm ° C., and the temperature variation was large due to the difference in the coefficient of thermal expansion, and the temperature characteristics of the differential pressure measuring device were poor.

(3) Since the side unit becomes thicker, the distance between the mounting surfaces of the differential pressure measuring device becomes large, and the distance between the mounting surfaces of the standard non-corrosion resistant product does not match. If configured, a special device such as an adapter is required separately. The present invention solves this problem. An object of the present invention is to provide a differential pressure measuring device in which the welding yield is improved together with the welding yield, and the face-to-face distance can be configured to have substantially the same dimensions as the standard product.

[0013]

In order to achieve this object, the present invention relates to a diaphragm which is provided on both side surfaces of a housing made of stainless steel and whose outer peripheral portion is fixed to the housing, and to the diaphragm. In a differential pressure measuring device comprising a detection element for detecting the applied differential pressure via the filled liquid,

A diaphragm having an outer peripheral portion fixed to the housing, and one surface fixed to the side surface of the housing by welding at an outer side of the outer peripheral fixing portion of the liquid diaphragm, with a gap between the outer peripheral fixing portion of the diaphragm. A ring-shaped body ring made of nickel or a nickel alloy, a liquid contact diaphragm made of tantalum, which is provided so as to cover the liquid diaphragm and has a peripheral edge welded and fixed to the other surface of the main body ring, and a peripheral portion of the liquid contact diaphragm as a main body. A liquid contact ring made of tantalum that is pressed against a ring and fixed by welding, and a melt-off cut of a ring-shaped melt that is provided at a fixed joint between the body ring, the liquid contact diaphragm, and the liquid contact ring and is orthogonal to the ring surface. The area ratio of the main body ring made of nickel and the wetted diaphragm and the solid solution of the wetted ring are A welded portion formed within a range of a melted cross-sectional area ratio of a limit capable of maintaining a welded fixed state of the main body ring, the liquid-contacting diaphragm and the liquid-contacted ring from a maximum melted cross-sectional area ratio that does not precipitate an intermetallic compound. A chamber formed by the housing, the main body ring, the liquid contact diaphragm and the diaphragm diaphragm, a sealing port provided in the housing, and one end opening at the gap portion and the sealing port and the chamber. A differential pressure measuring device comprising: a communication hole that communicates with each other; and a filled liquid filled in the communication hole, the chamber, and the filling port.

[0015]

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the liquid contact diaphragm 34 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102.
On the other hand, when pressure acts from the low pressure side, the pressure acting on the liquid contact diaphragm 33 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101. As a result, the silicon diaphragm 8 is distorted according to the pressure difference between the high pressure side and the low pressure side,
This strain amount is electrically taken out by the strain gauge 80, and the differential pressure is measured.

A ring-shaped body ring made of nickel or nickel alloy, one surface of which is welded and fixed to the side surface of the stainless steel housing, and a peripheral edge of the body ring, which is provided to cover the diaphragm of the diaphragm, is welded and fixed to the other surface of the body ring. Since the liquid contact diaphragm made of tantalum is formed, the housing and the body ring, and the body ring and the liquid contact diaphragm are easily welded.

Further, provided in the fixed joint portion of the body ring, the liquid contact diaphragm, and the liquid contact ring, the range of the ratio of cross-sectional area of penetration of the ring-shaped melt perpendicular to the ring surface is the body ring made of nickel. The solid solution of the liquid contact diaphragm and liquid contact ring made of tantalum does not precipitate intermetallic compounds.The maximum melted cross-sectional area ratio allows the weld cutoff to the extent that the welding fixing state between the body ring, the liquid contact diaphragm and the liquid contact ring can be maintained. Since the welded part is constructed within the range of the area ratio, the welded part becomes a solid solution of the body ring made of nickel and the liquid contact diaphragm made of tantalum and the liquid contact ring, and there is no fragile intermetallic compound. Is improved, the yield against welding leakage is improved, and stable and highly reliable welding can be performed.

Further, the body ring has an intermediate coefficient of thermal expansion between the housing and the liquid contact diaphragm, and since the liquid contact diaphragm made of tantalum is not directly welded and fixed to the stainless steel housing, it is relatively fixed. There is little difference in thermal expansion coefficient. Hereinafter, detailed description will be given based on examples.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the essential structure of an embodiment of the present invention,
2 is a sectional view taken along line AA of FIG. In the figure, the same symbols as those in FIG. 8 indicate the same functions. Only the parts different from FIG. 8 will be described below. Reference numerals 31 and 32 are liquid diaphragms whose outer peripheral portions are fixed to the housing 1.

33 and 34 are the diaphragms 31 and 3 of the liquid separator.
2. Separating diaphragms 31 and 32 outside the outer peripheral fixed portion
Is a ring-shaped main body ring made of nickel or a nickel alloy, one surface of which is welded and fixed to the side surface of the housing 1 while keeping the gaps 35 and 36 from the outer peripheral fixed portion. 37, 38
Is a liquid contact diaphragm made of tantalum, which is provided so as to cover the liquid diaphragms 31 and 32 and whose peripheral edge is welded and fixed to the other surface of the body rings 33 and 34.

41 and 42 are chambers formed by the housing 1, the body rings 33 and 34, the liquid contact diaphragms 37 and 38, and the liquid diaphragms 31 and 32. 43,44
Is a sealing port provided in the housing 1. 45,4
6, one end is opened in the gaps 35 and 36 and the sealing port 43,
44 is a communication hole that connects the chambers 41 and 42 with each other.

47 and 48 are communication holes 45 and 46 and the chamber 4
1, 42 and the sealing ports 43, 44. 51 and 52 are liquid separating rings that press the peripheral portions of the liquid separating diaphragms 31 and 32 against the housing 1 to fix them by welding. Reference numerals 53 and 54 are liquid contact rings made of tantalum, which are fixed by welding by pressing the peripheral portions of the liquid contact diaphragms 37 and 38 to the body rings 33 and 34.

Reference numerals 61 and 62 are provided at fixed joint portions of the body rings 33 and 34, the liquid contact diaphragms 37 and 38, and the liquid contact rings 53 and 54, and are ring-shaped melt penetration cross-sectional areas orthogonal to the ring surfaces. The ratio of the main body ring 33, 34 made of nickel, the liquid contact diaphragms 37, 38 made of tantalum and the solid solution of the liquid contact rings 53, 54 does not cause precipitation of intermetallic compounds. This is a welded portion formed within the range of the melted cross-sectional area ratio of the limit that can maintain the welded fixed state of 33, 34, the liquid contact diaphragms 37, 38, and the liquid contact rings 53, 54.

In this case, as shown in FIG. 3, the liquid contact diaphragms 37, 38 and the liquid contact ring 5 made of tantalum.
The cross-section area ratio A: B = 1: 3 of 3,54 and the main body rings 33, 34 made of nickel. Figure 3
3A shows a state before welding and FIG. 3B shows a state after welding. Here, the maximum penetration cross-sectional area ratio at which the solid solution does not precipitate the intermetallic compound can be obtained from the metal phase diagram of nickel-tantalum. Here, the sectional area ratio of penetration A: B = 1:
It is considered to be around 3.

The metal phase diagram of nickel-tantalum is described, for example, in the title: "CONSTITUTION OF BIN.
ARY ALLOYS "Page 1046 Author: Dr. p
hil. Max Hansen Published by: McGRAW-
HILL BOOK COMPANY Published: 1958
Is shown in.

On the other hand, the melted cross-sectional area ratio at which the welded fixed state of the body rings 33, 34 and the liquid contact diaphragms 37, 38 and the liquid contact rings 53, 54 can be maintained is, for example, A: B = 1: 5 Is considered the limit. The welding is not limited to electron beam welding (EBW), TIG welding, and the like, and any welding may be used as long as it can be welded.

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the liquid contact diaphragm 38 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102. On the other hand, when pressure acts from the low pressure side, the pressure acting on the liquid contact diaphragm 37 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101. As a result, the silicon diaphragm 8 is distorted according to the pressure difference between the high pressure side and the low pressure side, and the strain amount is electrically taken out by the strain gauge 80, and the differential pressure is measured.

Then, ring-shaped main body rings 33, 34 made of nickel or nickel alloy, one surface of which is welded and fixed to the side surface of the stainless steel housing 1, and the main body ring 33 provided so as to cover the diaphragms 31, 32. , 3
Since the liquid contact diaphragms 33 and 34 made of tantalum and having their peripheral edges welded and fixed to the other surface of the housing 4,
The main body rings 33 and 34, and the main body rings 33 and 34 and the liquid contact diaphragms 33 and 34 are easily welded.

Further, it is provided at a fixed joint portion of the body rings 33, 34, the liquid contact diaphragms 33, 34, and the liquid contact rings 53, 54, and the ratio of the cross-sectional area of penetration of the ring-shaped penetration perpendicular to the ring surface is The range is from the maximum penetration cross-sectional area ratio at which the solid solution of the body rings 33, 34 made of nickel, the liquid contact diaphragms 33, 34 made of tantalum, and the liquid contact rings 53, 54 does not precipitate intermetallic compounds. Since the welded portion constituted within the range of the melted cross-sectional area ratio of the limit capable of holding the welded fixed state between the liquid-contacting diaphragms 33, 34 and the liquid-contacting rings 53, 54 made of 34 and tanru, the welded portion is It becomes a solid solution of the body rings 33 and 34 made of nickel, the liquid contact diaphragms 33 and 34 made of tanru, and the liquid contact rings 53 and 54, and is fragile. Since intermetallic compounds is eliminated, is improved weld strength, improved yield with respect to the weld leakage becomes as can be performed stable and reliable welding.

The body rings 33 and 34 have a coefficient of thermal expansion intermediate between those of the housing 1 and the liquid contact diaphragms 37 and 38, and the stainless steel housing 1 has the liquid contact diaphragms 37 and 38 made of tanru. Since it is not directly welded and fixed, the relative difference in thermal expansion coefficient is small.

As a result, (1) the weldability of the liquid-contacting diaphragms 37, 38 is improved, and all of them are welded well. Since the ring-shaped body rings 33 and 34 made of nickel or nickel alloy are adopted, the liquid contact diaphragm 3 made of tantalum which is a difficult welding material.
No. 7,38 makes welding easier, the welding yield is improved, and the total number is good.

As an example, the yield is 80 in the conventional example.
%, The present invention improved to 100%. In addition, a ring-shaped body ring 3 made of nickel or a nickel alloy
3 and 34 are easily welded to the housing 1 made of stainless steel.

Since tantalum partially forms a solid solution with nickel, it can be welded to nickel or a nickel alloy under certain conditions. Further, since nickel has a high viscosity at the time of welding and is difficult to melt, it can be melted to the same extent as tantalum, which is a high melting point material, and further facilitates welding.
Due to the formation of many brittle intermetallic compounds with stainless steel, and the melting point difference, tantalum does not melt and much stainless steel melts, making welding difficult.

(2) Welding strength is improved. Body ring 3
3, 34, wetted diaphragms 33, 34, and wetted ring 5
A ring-shaped melt penetration cross-sectional area ratio orthogonal to the ring surface is provided in a fixed joint portion with the main body rings 33 and 34 made of nickel and the liquid contact diaphragms 33 and 34 made of tanru. And wetted ring 5
From the maximum penetration cross-sectional area ratio at which the solid solution of 3, 54 does not precipitate the intermetallic compound, it is possible to maintain the welding fixed state of the body rings 33, 34, the liquid contact diaphragms 33, 34 and the liquid contact rings 53, 54 by the maximum. Since the welded part was formed within the range of the cross-sectional area ratio of penetration, the welded part can be composed of a solid solution, and the fragile intermetallic compound does not exist, so the welding strength is improved and the yield against welding leakage is improved. , Stable and reliable welding can be performed.

(3) The temperature characteristics are improved. The coefficient of thermal expansion of nickel is approximately 12 × 10 ⁻⁶ mm / mm ° C. and it has an intermediate coefficient of thermal expansion between stainless steel and tantalum, and unlike the conventional example, stainless steel and tantalum are not directly welded. , Relative difference in thermal expansion coefficient is small, and temperature error is small.

(4) The surface distance can be made substantially the same as the standard size. Since tantalum is a high melting point material, if the body rings 33, 34 are made of stainless steel, the body rings 33, 34 will melt to a large extent when the tantalum is welded, so the body rings 33, 34 must be thick. I have to.

On the other hand, nickel is a material that has a poor flow of molten metal and is hard to melt, so that it can be made thin.
Thus, if the enclosure ports 43 and 44 for the enclosure liquids 47 and 48 are provided in the body rings 33 and 34, there is a limit to how thin it is as shown in the conventional example. As in the present invention, the interval 3
5 and 36 are used to fill the filling ports 43 and 48 of the filling liquids 47 and 48,
Since 44 is provided on the housing 1 side, it can be made thinner because there is no sealing port, and the distance between the mounting surfaces of the differential pressure measuring device can be kept within the error size of the standard product size, which makes it easy to use. .

FIG. 4 is an explanatory view of the essential structure of another embodiment of the present invention. In this embodiment, the separator rings 51 and 52 are
The mounting surfaces of the main body rings 33 and 34 are substantially the same. FIG. 5 is an explanatory view of the essential parts of another embodiment of the present invention, showing a state after welding. 6 (A) and 6 (B) are explanatory views of a main part configuration of another embodiment of the present invention. FIG. 6 (A) is before welding and FIG.
Indicates the state after welding. 7 (A) and 7 (B) are explanatory views of the main configuration of another embodiment of the present invention. FIG. 7 (A) shows a state before welding and FIG. 7 (B) shows a state after welding.

[0039]

As described above, according to the present invention, a diaphragm which is provided on each side surface of a housing made of stainless steel and has an outer peripheral portion fixed to the housing, and a differential pressure applied to the diaphragm are filled with a sealed liquid. In a differential pressure measuring device comprising a detection element for detecting via

A liquid diaphragm whose outer peripheral portion is fixed to the housing, and one surface of which is welded and fixed to the side surface of the housing at a distance from the outer peripheral fixed portion of the liquid diaphragm to the outer peripheral fixed portion of the liquid diaphragm. A ring-shaped body ring made of nickel or a nickel alloy, a liquid contact diaphragm made of tantalum, which is provided so as to cover the liquid diaphragm and has a peripheral edge welded and fixed to the other surface of the main body ring, and a peripheral portion of the liquid contact diaphragm as a main body. A liquid contact ring consisting of a tanru that is pressed against the ring and fixed by welding, and a melt-off cut of a ring-shaped melt that is provided at the fixed joint between the body ring, the liquid contact diaphragm and the liquid contact ring and is orthogonal to the ring surface. The area ratio of the main body ring made of nickel and the wetted diaphragm and the solid solution of the wetted ring are gold. A welded portion formed within a range of a melted cross-sectional area ratio of a limit capable of maintaining a welded fixed state of the main body ring, the liquid-contacting diaphragm and the liquid-contacted ring from a maximum melted-out surface area ratio that does not precipitate intermetallic compounds; ,
A chamber formed by the housing, the main body ring, the liquid contact diaphragm and the liquid separating diaphragm, a sealing port provided in the housing, and one end opening at the spacing portion to connect the sealing port and the chamber. A differential pressure measuring device comprising: a communication hole communicating with the communication hole; and a filling liquid filled in the communication hole, the chamber, and the filling port.

As a result, (1) the wettability of the liquid contact diaphragm is improved, and the total number of welded diaphragms is good. Since the ring-shaped main body ring made of nickel or nickel alloy is adopted, it becomes easy to weld with the liquid contact diaphragm made of tantalum which is a difficult welding material, the welding yield is improved, and the total number of welding is good. Further, the ring-shaped main body ring made of nickel or nickel alloy is easily welded to the housing made of stainless steel.

Since tantalum partially forms a solid solution with nickel, it can be welded to nickel or a nickel alloy under constant conditions. Further, nickel is a material that has a high viscosity at the time of welding and is difficult to melt, and since it can be melted to the same extent as tantalum which is a high melting point material, welding is further facilitated. Due to the formation of many brittle intermetallic compounds with stainless steel, and the melting point difference, tantalum does not melt and much stainless steel melts, making welding difficult.

(2) Welding strength is improved. It is provided at the fixed joint between the main body ring, the liquid contact diaphragm and the liquid contact ring, and the range of the sectional area of penetration of the ring-shaped melt that is orthogonal to the ring surface is such that the body ring made of nickel and the liquid contact diaphragm and the contact surface. The solid solution of the liquid ring is configured to fall within the range of the maximum fusion sectional area ratio that does not precipitate intermetallic compounds, and the limit of the fusion sectional area ratio that can maintain the weld fixed state of the body ring, the liquid contact diaphragm and the liquid contact ring. Since the welded part is configured, the welded part can be composed of a solid solution, and the brittle intermetallic compound does not exist, so the welding strength is improved, the yield against welding leakage is improved, and stable and reliable welding can be performed. .

(3) The temperature characteristics are improved. The coefficient of thermal expansion of nickel is approximately 12 × 10 ⁻⁶ mm / mm ° C. and it has an intermediate coefficient of thermal expansion between stainless steel and tantalum, and unlike the conventional example, stainless steel and tantalum are not directly welded. , Relative difference in thermal expansion coefficient is small, and temperature error is small.

(4) The face-to-face distance can be made substantially the same as the standard size. Tantalum is a high melting point material, so if the body ring is made of stainless steel, when welding tantalum,
Since the body ring part melts greatly, the body ring must be thick. On the other hand, nickel is a material that does not flow easily and does not easily melt, so it can be made thin. Thus, if the main body ring is provided with the filling port for the filling liquid, there is a limit to the reduction in thickness as shown in the conventional example. As in the present invention, the space is used to provide the sealing port for the sealing liquid on the housing side, so that it can be made thinner because there is no sealing port, and the distance between the mounting surfaces of the differential pressure measuring device is the standard size. It is possible to make it within the margin of error and it is easy to use.

Therefore, according to the present invention, it is possible to realize the differential pressure measuring device in which the welding yield is improved together with the welding yield and the face-to-face distance can be configured to have substantially the same dimensions as the standard product.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a detailed view of a main part of FIG.

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 main part configuration of another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 7 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 8 is an explanatory diagram of a configuration of a conventional example that is generally used in the past.

[Explanation of symbols]

 1 ... Housing 2 ... Flange 3 ... Flange 4 ... Inlet port 5 ... Inlet port 6 ... Pressure measuring chamber 6A ... Back plate 6B ... Back plate 7 ... Center diaphragm 8 ... Silicon diaphragm 9 ... Support 10A ... Back plate -TO 11A ... Back plate 14 ... Communication hole 15 ... Communication hole 16 ... Communication hole 17 ... Communication hole 31 ... Separation diaphragm 32 ... Separation diaphragm 33 ... Main body ring 34 ... Main body ring 35 ... Interval 36 ... Interval 37 ... Liquid contact diaphragm 38 ... Liquid contact diaphragm 41 ... Chamber 42 ... Chamber 43 ... Encapsulation port 44 ... Encapsulation port 45 ... Communication hole 46 ... Communication hole 47 ... Encapsulation liquid 48 ... Encapsulation liquid 51 ... Separation ring 53 ... Separation ring 53 ... Liquid contact ring 54 ... Liquid contact ring 61 ... Welded portion 62 ... Welded portion

Claims (1)

[Claims] 1. A diaphragm comprising a housing made of stainless steel, which is provided on each side of the housing and has an outer peripheral portion fixed to the housing, and a detection element for detecting a differential pressure applied to the diaphragm via an enclosed liquid. In the differential pressure measuring device, the outer peripheral portion of the diaphragm is fixed to the housing, and the outer peripheral fixed portion of the liquid diaphragm is located outside the outer peripheral fixed portion of the diaphragm, and one surface is formed on the side surface of the housing. A ring-shaped body ring made of nickel or a nickel alloy, which is welded and fixed, and a liquid contact diaphragm made of tantalum, which is provided so as to cover the liquid diaphragm and has a peripheral edge welded and fixed to the other surface of the body ring, and a liquid contact diaphragm of the liquid contact diaphragm. A liquid contact ring made of tantalum for pressing and fixing a peripheral edge portion to the body ring by welding; The main body ring, which is provided at the fixed joint portion between the liquid contact diaphragm and the liquid contact ring, and has a range of the sectional area of penetration of the ring-shaped melt which is orthogonal to the ring surface, is composed of the nickel, the liquid contact diaphragm, and the liquid contact ring. The solid solution of No. 1 does not precipitate an intermetallic compound, and is configured within the range of the melted cross-sectional area ratio of the limit capable of maintaining the weld fixed state of the main body ring, the wetted diaphragm and the wetted ring from the maximum melted cross-sectional area ratio. A welded portion, a chamber formed by the housing, the main body ring, the liquid contact diaphragm and the liquid diaphragm, a sealing port provided in the housing, and one end opened in the gap portion and the seal. A differential pressure measurement, comprising: a communication hole that communicates the inlet with the chamber; and a filling liquid filled in the communication hole, the chamber, and the filling port. Apparatus.