JP3521322B2 - Differential pressure measuring device - Google Patents

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 avoiding variation in characteristics due to assembly, facilitating assembly, and reducing costs.

[0002]

2. Description of the Related Art FIG. 2 is an explanatory view 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. Neck 1
In this case, A and the pressure receiving portion 1B are made of a stainless material.

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

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 are separately provided.
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, and the other surface is machined and etched to form a diaphragm having an overall concave shape.

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 has a neck portion 1A of 2
It is divided into individual sensor rooms 81 and 82. A silicon diaphragm 8 is adhesively fixed to the end surface of the support 9 on the pressure measurement chamber 6 side by a method such as low-melting glass connection.

Housing 1 and high-pressure side cover flange 2,
And between the low pressure side cover flange 3 and the pressure introducing chamber 1
0 and 11 are formed. This pressure introducing chamber 10, 11
The diaphragms 12 and 13 are provided inside, and the wall 10 of the housing 1 facing the diaphragms 12 and 13 is provided.
A back plate having a shape similar to that of the diaphragms 12 and 13 is formed on each of A and 11A.

The diaphragms 12 and 13 have a pressure receiving portion 1.
The peripheral portion is welded to B by the liquid separating rings 121 and 131. In this case, the diaphragms 12, 13
The separator rings 121 and 131 are made of stainless steel.

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.

Filling liquid 101, 102 such as silicone oil is filled between the diaphragms 12, 13.
The enclosed liquid reaches the upper and lower surfaces of the silicon diaphragm 8 through the communication holes 16 and 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 cover 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 diaphragm 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 diaphragm diaphragm 13 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102.

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.

FIG. 3 is an explanatory view of the structure of another conventional example which is generally used in the past, in the case where the measurement fluid is a highly corrosive fluid.

When the fluid to be measured is a highly corrosive fluid, the first diaphragms 12 and 13 and the first diaphragm ring 12 are used.
The second diaphragm 2 for covering 1, 131 and made of a highly corrosion-resistant material such as tantalum or Hastelloy material.
1, 22 and second separating rings 211, 221 are used.

In this case, since the second diaphragms 21 and 22 made of tantalum or Hastelloy are difficult to be welded and fixed to the pressure receiving portion 1B made of stainless steel, for example, via the intervening material rings 23 and 24 made of nickel. It is fixed by welding.

As shown in FIG. 3, between the first diaphragms 12 and 13, the first diaphragm rings 121 and 131 and the pressure receiving portion 1B, the second diaphragms 21 and 22 and the second diaphragms 22 and 22.
Between the liquid separating rings 211 and 221 and the interstitial rings 23 and 24, and between the interstitial rings 23 and 24 and the pressure receiving portion 1B,
A welded portion D is provided. ,

In this case, Tig welding is performed. Electron beam welding E is performed between the second diaphragms 21 and 22 and the second diaphragm rings 211 and 221.

[0023]

However, in such a highly corrosive device, (1) the cover flanges 2 and 3 have the pressure introducing chambers 10 and 11.
In order to ensure the withstand pressure of, the liquid separating rings 121 and 131 are strongly pressed and tightened by using, for example, a through bolt and a nut.

Clamping surface and diaphragms 12, 13, 2
Since the surfaces of the diaphragms 1 and 22 are on the same surface, the initial tension of the diaphragms 12, 13, 21 and 22 is affected and the characteristics of the device vary.

(2) Second diaphragm diaphragms 21,2
2, second separator ring 21 1 , 22 1 and interstitial ring 2
Since 3, 24 are required, the number of welding points and the number of parts are increased, resulting in a significant increase in cost.

The present invention solves this problem. An object of the present invention is to provide a differential pressure measuring device which can avoid characteristic fluctuations due to assembly, can be easily assembled, and can reduce costs.

[0027]

In order to achieve this object, the present invention provides: (1) a diaphragm having a block-shaped pressure receiving portion whose peripheral edge is fixed by welding, and the diaphragm. In a differential pressure measuring device comprising a cover flange that press-seals the peripheral edge of the other surface of the outer resistance welding portion formed by resistance welding the peripheral edge of the diaphragm to the pressure receiving portion in a ring shape, An inner resistance weld portion formed inside the outer resistance weld portion by resistance welding the periphery of the diaphragm to the pressure receiving portion in a ring shape, and the inner resistance weld portion and the outer resistance weld portion. A stepped stepped portion provided in the pressure receiving portion in a ring shape between the deep diaphragm portion which is provided in the diaphragm diaphragm and bends corresponding to the stepped stepped portion, and the other of the diaphragm diaphragm. This of face A differential pressure measuring device, comprising: a cover flange for pressing and sealing the peripheral side of the deep drawing part. (2) The differential pressure measuring device according to claim 1, wherein seam welding is used as the resistance welding. Is configured.

[0028]

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the 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 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.

In order to assemble the diaphragm of the pressure receiving portion, the deep diaphragm portion of the diaphragm is attached to the step of the pressure receiving portion. Next, the inner resistance weld portion and the outer resistance weld portion are formed by seam welding. Hereinafter, detailed description will be given based on examples.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the essential parts of an embodiment of the present invention. In the figure, the same symbols as those in FIG. 2 represent the same functions. Only parts different from FIG. 2 will be described below.

The outer resistance welding portions 31, 32 are formed by seam-welding the peripheral edges of the liquid diaphragms 33, 34 to the pressure receiving portion 1B in a ring shape. Separation diaphragm 33, 34
In this case, tantalum or hastelloy materials are used.

The inner resistance welds 35 and 36 are provided inside the outer resistance welds 31 and 32, and are formed by seam-welding the peripheral portions of the diaphragms 33 and 34 to the pressure receiving portion 1B in a ring shape. .

The stepped portions 37 and 38 are provided in the pressure receiving portion 1B in a ring shape between the inner resistance welding portions 35 and 36 and the outer resistance welding portions 31 and 32. Stepped step 3
Deep drawing portions 39 and 41 that bend corresponding to 7 and 38 are provided on the diaphragms 33 and 34.

The cover flanges 2 and 3 press and seal the peripheral sides of the diaphragm diaphragms 33 and 34 with respect to the deep drawn portion 39.

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the diaphragm 33 is
It 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 diaphragm 34 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102.

Accordingly, 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, the liquid diaphragm 3 is attached to the pressure receiving portion 1B.
To assemble 3, 34, diaphragm diaphragms 33, 3
4 deep drawing parts 39, 41 to the step parts 37, 3 of the pressure receiving part 1B.
Attach to 8.

Next, the inner resistance welds 35, 36 and the outer resistance welds 31, 32 are formed by seam welding.

As a result, (1) the cover flanges 2 and 3 have the pressure introducing chambers 10 and 11
Separation ring 12 to ensure the pressure resistance of
Press 1,131 strongly and tighten.

If the tightening surface and the surfaces of the diaphragms 33 and 34 are on the same surface, the initial tension of the diaphragms 33 and 34 may be affected and the characteristics of the device may vary.

However, in the present invention, the deep drawing portion 3
Since 9 and 41 are provided, the pressing force by the cover flanges 2 and 3 is absorbed by the deep drawn portions 39 and 41, the initial tension of the diaphragms 33 and 34 is not affected, and the characteristics of the device may vary. Thus, a differential pressure measuring device can be obtained.

(2) Since the resistance welding is used, the diaphragms 33, 34 can be directly welded to the pressure receiving portion 1B, and the second diaphragm 21, 21 as shown in FIG.
22, second separator rings 21 and 22, and interstitial rings 23,
I no longer need 24.

Therefore, the number of welding points and the number of parts can be reduced, the cost can be greatly reduced, and an inexpensive differential pressure measuring device can be obtained.

(3) The step portions 37, 38 are provided with deep drawing portions 39,
By arranging 41, it is possible to easily perform centering and fixing at the time of welding without using an assembling jig or the like, so that the welding work can be easily performed, and the welding processing cost can be significantly reduced, and an inexpensive differential pressure can be obtained. A measuring device is obtained.

(4) Since the outer resistance welded portions are formed on the peripheral edges of the diaphragms 33 and 34, the corrosion resistant portion is widely formed, and the differential pressure measuring device with improved corrosion resistance can be obtained.

(5) If seam welding is used as the resistance welding 31, 32, 35, 36, the material of the welded portion other than the highly resistant material of the diaphragm may be eluted on the outer surface of the welded portion. Since the welding is continuous and has no gap, a reliable differential pressure measuring device with a highly reliable seal of the welded portions 31, 32, 35, 36 can be obtained.

In the above-described embodiment, the resistance weldings 31, 32, 35 and 36 are seam weldings 31 and 3.
Although it has been described that 2, 35, 36 are used, the present invention is not limited to this, and spot welding may be used, for example.

In short, the material of the welded portion other than the highly resistant material of the diaphragm is not likely to be eluted on the outer surface of the welded portion.

[0050]

As described above, according to the first aspect of the present invention.
According to (1), the cover flange strongly presses and tightens the partition ring in order to ensure the pressure resistance of the pressure introducing chamber.

If the clamping surface and the surface of the diaphragm are on the same surface, the initial tension of the diaphragm is affected,
The device characteristics may vary.

However, in the present invention, since the deep drawing portion is provided, the pressing force by the cover flange is absorbed in the deep drawing portion, the initial tension of the diaphragm is not affected, and the characteristics of the device vary. A differential pressure measuring device without fear is obtained.

(2) Since resistance welding is adopted, the diaphragm diaphragm can be directly welded to the pressure receiving portion, and the second diaphragm diaphragm, the second separator ring, and the spacer ring are required as in the conventional example. lost.

Therefore, the number of welding points and the number of parts can be reduced, the cost can be greatly reduced, and an inexpensive differential pressure measuring device can be obtained.

(3) By arranging the deep-drawing portion in the step portion, it is possible to easily perform centering and fixing at the time of welding without needing an assembling jig, so that the welding work can be easily performed and the welding process cost can be improved. Can be significantly reduced, and an inexpensive differential pressure measuring device can be obtained.

(4) Since the outer resistance welding portion is formed on the peripheral edge of the diaphragm, the corrosion resistant portion is formed widely,
A differential pressure measuring device having improved corrosion resistance is obtained.

According to the second aspect of the present invention, since the seam welding is used as the resistance welding, the material of the welded portion other than the highly resistant material of the diaphragm is likely to be eluted on the outer surface of the welded portion. Since there is no welding and the welding is continuous, it is possible to obtain a reliable differential pressure measuring device with a highly reliable seal at the welded portion.

Therefore, according to the present invention, it is possible to realize the differential pressure measuring device which can avoid the variation of the characteristics due to the assembling, can be easily assembled, and can reduce the cost.

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

FIG. 3 is a structural explanatory view of another conventional example that is generally used in the past.

[Explanation of symbols]

1 housing 1A neck 1B Pressure receiving part 1C weld 2 High-pressure side cover flange 3 Low pressure side cover flange 4 entrance 5 entrance 6 Pressure measurement chamber 6A back plate 6B back plate 7 Center diaphragm 8 Silicon diaphragm 9 Support 10 Pressure introduction chamber 10A back plate 11 Pressure introduction chamber 11A back plate 14 communication holes 15 communication holes 16 communication holes 17 communication holes 18 O-ring 31 Outer resistance weld 32 Outside resistance weld 33 diaphragm diaphragm 34 Diaphragm diaphragm 35 Inner resistance weld 36 Inner resistance weld 37 steps 38 steps 39 Deep drawing part 41 Deep drawing 80 strain gauge 81 Sensor room 82 Sensor room 101 Filled liquid 102 Filled liquid

Claims (2)

(57) [Claims] 1. A differential pressure differential comprising a diaphragm having a peripheral edge of one surface welded and fixed to a block-shaped pressure receiving portion, and a cover flange for pressing and sealing the peripheral edge of the other surface of the diaphragm. In the measuring device, an outer resistance welding portion formed by resistance welding the periphery of the diaphragm to the pressure receiving portion in a ring shape, and a peripheral portion of the diaphragm which is provided inside the outer resistance welding portion, An inner resistance welding portion formed by resistance welding in a ring shape on the pressure receiving portion, and a stepped step portion provided in the pressure receiving portion in a ring shape between the inner resistance welding portion and the outer resistance welding portion. , ingredients and deep-drawing portion bends in response to the stepped portion of the stepped provided in the隔液diaphragm, and a cover flange for pressing sealing the peripheral side of the deep drawn portion of the other surface of the隔液diaphragm Differential pressure measuring device, characterized in that the. 2. The differential pressure measuring device according to claim 1, wherein seam welding is used as the resistance welding.