JPH06307961A - Differential pressure measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a differential pressure measuring device capable of improving the manufacturing yield of the seal diaphragm and increasing the manufacturing cost. In a differential pressure measuring device in which a peripheral edge of a seal diaphragm is fixed by a seal ring to both side surfaces of a block-shaped pressure receiving portion, a flow hole through which a measurement fluid flows and a pressure receiving portion provided at the peripheral edge of the flow hole together with the pressure receiving portion. A cylinder in which one end is fixed to a flat bottom including a metal seal portion for metal-sealing the peripheral edge of the seal diaphragm and one end is fixed to the peripheral edge of the bottom and the inner peripheral surface is screwed and fixed to the pressure receiving portion or press-fitted. A differential pressure measuring device comprising a seal ring having a section.

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 capable of improving the manufacturing yield and the assembling yield of a seal diaphragm.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of the configuration of a conventional example which has been generally used.
No. 42 is shown.

In the figure, reference numeral 1 denotes a housing, which is composed of a columnar neck portion 1A and a block-shaped pressure receiving portion 1B welded and connected at an outer peripheral edge portion 1C of the end portion of the neck portion 1A.

On both sides of the housing 1, high pressure side flanges 2,
The low-pressure side flange 3 is fixed by welding or the like, and both flanges 2 and 3 are provided with an inlet 4 for a high-pressure fluid having a pressure P _H to be measured and an inlet 5 for a low-pressure fluid having a pressure P _L. .

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 separately fixed to the wall of the pressure measuring chamber 6, and the center diaphragm 7 and the silicon diaphragm 8 both divide the pressure measuring chamber 6 into two parts. 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, and the other surface is machined,
Etch to form a generally concave diaphragm.

The four strain gages 80 are designed so that when the silicon diaphragm 8 is deflected by the differential pressure ΔP, two strain gages are pulled and two are compressed, and these strain gages form a Wheatstone bridge circuit. The change in resistance is detected as a change in the differential pressure ΔP. The silicon diaphragm 8 divides the neck portion 1A into two sensor chambers 81 and 82.

A silicon diaphragm 8 is adhesively fixed to the end surface of the support 9 on the pressure measuring chamber 6 side by a method such as low-melting glass connection. Pressure introducing chambers 10 and 11 are formed between the housing 1 and the high-pressure side flange 2 and the low-pressure side flange 3.

Seal diaphragms 12 and 13 are provided in the pressure introducing chambers 10 and 11, and the seal diaphragm 1 is provided.
Back plates having a shape similar to that of the seal diaphragms 12 and 13 are formed on the walls 10A and 11A of the housing 1 that face the reference numerals 2 and 13, respectively. Seal diaphragm 12, 1
No. 3 has a peripheral edge welded to the pressure receiving portion 1B by seal rings 121 and 131.

The space formed by the seal 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. Filling liquid 101, 102 such as silicone oil is filled between the seal diaphragms 12, 13, and the filling liquid reaches the upper and lower surfaces of the silicon diaphragm 8 through the communication holes 16, 17.

The enclosed liquids 101 and 102 are divided into two parts by the center diaphragm 7 and the silicon diaphragm 8, but the amounts are considered to be almost equal. Reference numeral 18 denotes a gasket provided between the pressure receiving portion 1B and the flanges 2 and 3, and in this case, an O ring is used.

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the seal diaphragm 12 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101. On the other hand, when the pressure acts from the low pressure side, the pressure acting on the seal diaphragm 13 is transmitted to the silicon diaphragm 8 by the filled liquid 102.

As a result, the silicon diaphragm 8 is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and the strain gauge 80 is electrically taken out by the strain gauge 80 to measure the differential pressure.

[0014]

However, in such an apparatus, when measuring a highly corrosive measuring fluid or the like, a corrosion-resistant metal is used for a part such as a seal diaphragm which is in contact with the measuring fluid. For example, titanium, tantalum, monet, etc. are used. These metals have good corrosion resistance, but have a drawback of poor weldability. Unless the welding conditions and the like are carefully controlled, welding defects are likely to occur and the yield due to welding is likely to decrease. Further, in some cases, it is impossible to directly weld to the main body, and welding is performed through another metal, which leads to an increase in manufacturing cost.

The present invention solves this problem. An object of the present invention is to provide a differential pressure measuring device which can improve the yield of assembly of the seal diaphragm and the manufacturing cost.

[0016]

In order to achieve this object, the present invention provides a differential pressure measuring device in which a peripheral edge portion of a seal diaphragm is fixed to both side surfaces of a block-shaped pressure receiving portion by a seal ring. A flat bottom consisting of a circulation hole through which the fluid flows and a metal seal portion provided on the peripheral edge of the circulation hole for metal-sealing the peripheral edge portion of the seal diaphragm together with the pressure receiving portion, and one end fixed to the peripheral edge of the bottom portion. A differential pressure measuring device comprising a seal ring having a cylindrical portion whose surface is screwed and fixed to the pressure receiving portion or fixed by press fitting.

[0017]

In the above construction, when pressure is applied from the high pressure side, the pressure acting on the seal diaphragm is transmitted to the silicon diaphragm by the enclosed liquid. On the other hand, when pressure acts from the low pressure side, the pressure acting on the seal diaphragm is transmitted to the silicon diaphragm by the enclosed liquid. Therefore, the silicon diaphragm 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, and the differential pressure is measured.

The seal diaphragm is sandwiched between the pressure receiving portion and the seal ring, and the tubular portion of the seal ring is fixed to the pressure receiving portion, so that the seal diaphragm and the seal ring, and the seal diaphragm and the pressure receiving portion. The space is metal-sealed. 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. In the figure, the same symbols as those in FIG. 4 represent the same functions. Only parts different from FIG. 4 will be described below. 20 is
The seal ring is composed of a bottom portion 21 and a tubular portion 22. The bottom portion 21 is a planar bottom portion that is provided with a circulation hole 211 through which the measurement fluid circulates, and a metal seal portion 212 that is provided on the periphery of the circulation hole 211 and that seals the periphery of the pressure receiving portion 1B and the seal diaphragms 12 and 13 with a metal. Is. Tubular part 22
Has one end fixed to the peripheral edge of the bottom portion 21, and the inner peripheral surface 221 is screwed and fixed to the pressure receiving portion 1B.

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the seal diaphragm 12 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101. On the other hand, when the pressure acts from the low pressure side, the pressure acting on the seal diaphragm 13 is transmitted to the silicon diaphragm 8 by the filled liquid 102. Therefore, 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.

Thus, as shown in FIG. 2, the seal diaphragms 12 and 13 include the pressure receiving portion 1B and the seal ring 121,
It is sandwiched between 131 and 131, and the cylindrical portion 22 of the seal ring 20 is fixed to the pressure receiving portion 1B, so that a metal seal is provided between the seal diaphragms 12 and 13 and the seal ring 20, and between the seal diaphragms 12 and 13 and the pressure receiving portion 1B. To be done. In this case, the seal ring 20 is screwed into the pressure receiving portion 1B so that the surface pressure required for the metal seal is generated in the portions A and B. It should be noted that projections or the like may be provided on the A and B portions so that sufficient surface pressure can be generated with a small tightening torque. As a result, (1) the welding structure of the seal rings 121 and 131 having a poor yield is abolished, and the pressure receiving portion 1 of the seal diaphragms 12 and 13 is formed by a metal seal as a screw-in type or a press-fit type.
Since the seal for B is secured, the assembly yield of the seal diaphragms 12 and 13 is about 100%, and the manufacturing cost can be reduced. (2) In the case of the seal diaphragms 12 and 13 made of a metal that cannot be directly welded to the pressure receiving portion 1B, the pressure receiving portion 1B is welded and fixed through another metal, but the metal serving as the medium is unnecessary. Therefore, the manufacturing cost can be reduced.

FIG. 3 is an explanatory view of the essential structure of another embodiment of the present invention. In this embodiment, the cylindrical portion 31 of the seal ring 30 is press-fitted and fixed to the pressure receiving portion 1B via the seal diaphragms 12 and 13. It is possible to obtain a reliable metal seal between the seal diaphragms 12 and 13 and the pressure receiving portion 1B.

[0023]

As described above, according to the present invention, in the differential pressure measuring device in which the peripheral portions of the seal diaphragm are fixed by the seal rings on both side surfaces of the block-shaped pressure receiving portion,
One end is fixed to a flat bottom portion composed of a flow hole through which the measurement fluid flows and a metal seal portion provided on the peripheral edge of the flow hole and for metal-sealing the peripheral edge portion of the seal diaphragm together with the pressure receiving portion, and the peripheral edge of the bottom portion. A differential pressure measuring device comprising a seal ring having an inner peripheral surface that is fixed to the pressure receiving portion by screwing or is fixed by press fitting.

As a result, (1) the welding structure of the seal ring with poor yield is abolished,
As a screw-in type or a press-fit type, a metal seal is used to secure a seal for the pressure receiving portion of the seal diaphragm, so that the assembly yield of the seal diaphragm is approximately 100%, and the manufacturing cost can be reduced. (2) In the case of a seal diaphragm made of a metal that cannot be welded directly to the pressure receiving portion, it was welded and fixed to the pressure receiving portion via another metal, but the metal serving as this medium is unnecessary and the manufacturing cost is high. Can be reduced.

Therefore, according to the present invention, it is possible to realize the differential pressure measuring device which can improve the yield of the assembly of the seal diaphragm and the manufacturing cost.

[Brief description of drawings]

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

2 is an assembly explanatory diagram of FIG. 1. FIG.

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

FIG. 4 is an explanatory diagram of a configuration of a conventional example that is generally used in the past.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 1A ... Neck 1B ... Pressure receiving part 1C ... Welding part 2 ... High pressure side flange 3 ... Low pressure side 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 10 ... Pressure introducing chamber 10A ... Back plate 11 ... Pressure introducing chamber 11A ... Back plate 14 ... Communication hole 15 ... Communication hole 16 ... Communication hole 17 ... Communication hole 20 ... Seal ring 21 ... Bottom part 211 ... Circulation hole 212 ... Metal seal part 22 ... Cylindrical part 221 ... Inner peripheral surface 30 ... Seal ring 31 ... Cylindrical part 80 ... Strain gauge 81 ... Sensor chamber 82 ... Sensor chamber 101 ... Filled liquid 102 ... Filled liquid

Claims (1)

[Claims] 1. A differential pressure measuring device in which a peripheral edge of a seal diaphragm is fixed to both side surfaces of a block-shaped pressure receiving portion by a seal ring, and a flow hole through which a measurement fluid flows and a peripheral portion of the flow hole. Part and a metal seal part for metal-sealing the peripheral edge of the seal diaphragm, one end is fixed to the peripheral edge of the bottom part, and the inner peripheral surface is screwed to the pressure receiving part and fixed or press-fitted. A differential pressure measuring device, comprising: a seal ring having a tubular portion.