JPH0570776B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pressure receiving diaphragm protection device suitable for application to a differential pressure transmitter, etc. that measures a pressure difference between two points, which is a process variable, and a method for manufacturing the same. .

[Conventional technology]

Conventionally, when measuring the flow rate of fluid in a pipe using a differential pressure transmitter, an orifice plate was installed inside the pipe to create fluid resistance, and the pressure difference upstream and downstream of this resistance was measured to derive the flow rate based on a predetermined calculation formula. is being carried out. Therefore, as seen in Japanese Utility Model Publication No. 59-30444, this type of differential pressure transmitter generally applies each measurement pressure to two pressure-receiving diaphragms, and controls the movement of the sealed liquid within the body through a sealed circuit. It is configured to take out electrical output based on the distortion of a semiconductor sensor provided in a partitioned manner. In order to transmit pressure accurately, the pressure receiving diaphragm is usually made of a very thin metal plate and is formed into a corrugated shape. Conventionally, when the pressure received by the pressure receiving diaphragm becomes excessive, the diaphragm is protected by being received by the pressure receiving side of the body main body and prevented from moving. At this time, in order to prevent the waveform of the pressure-receiving diaphragm from being distorted or damaged, that is, to prevent excessive force from being applied, the pressure-receiving side surface of the body main body is formed into a waveform similar to that of the pressure-receiving diaphragm.

[Problem that the invention seeks to solve]

However, forming the surface of the body body into a highly accurate waveform surface by machining has the major drawbacks of being troublesome and time consuming, and significantly increasing manufacturing costs. In addition, when excessive pressure is applied to the pressure receiving diaphragm, if part of the pressure receiving diaphragm does not match the shape of the pressure receiving side of the body main body due to variations in the shape of the diaphragm, variations in the surface finish of the body, etc. The stress is applied, causing permanent strain on the diaphragm, and after that, even though the pressure on the pressure-receiving diaphragm is within the measurement range, the diaphragm comes into contact with the surface of the body, making it difficult to make high-precision measurements. make it difficult.

Therefore, the present invention solves the above-mentioned conventional drawbacks and reliably protects the pressure-receiving diaphragm from excessive pressure without making the pressure-receiving side of the body into a corrugated shape, thereby preventing its plastic deformation, breakage, etc. It is an object of the present invention to provide a pressure-receiving diaphragm protection device and a method for manufacturing the same.

[Means for solving problems]

In order to achieve the above object, the pressure receiving diaphragm protection device according to the present invention is a device in which a corrugated pressure receiving diaphragm is disposed on the pressure receiving side of a body main body that seals a sealed fluid for pressure transmission. A backup plate is formed on a flat surface, and is disposed on the side of the pressure-transmitting sealed liquid of the pressure-receiving diaphragm, and has a similar shape to the pressure-receiving diaphragm and faces the pressure-receiving diaphragm at a predetermined distance. It has a flow hole through which the sealed liquid for transmission can flow, and the top of the liquid on the sealed side of the corrugated surface is in contact with the pressure-receiving side surface.

Further, in the method for manufacturing a pressure receiving diaphragm protection device according to the present invention, the backup plate is formed by overlapping the pressure receiving diaphragm at the same time when the pressure receiving diaphragm is press-molded.

[Effect]

In the pressure receiving diaphragm protection device according to the present invention, when excessive pressure acts, the backup plate receives the pressure receiving diaphragm and prevents its deformation.
Prevent damage etc.

Further, in the method for manufacturing a pressure receiving diaphragm protection device according to the present invention, the pressure receiving diaphragm and the backup plate can be formed into similar shapes with high precision.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of a differential pressure transmitter equipped with a pressure receiving diaphragm protection device according to the present invention;
FIG. 2 is an enlarged sectional view of the main part. In these figures, the reference numeral 1 indicates the internal sealing fluid 2 for pressure transmission.
This body body 1 is made by enclosing
Pressure-receiving diaphragms 3 and 4 formed in a corrugated manner are arranged on both the left and right side surfaces, that is, each pressure-receiving side surface 1a and 1b, with their peripheral edges welded and fixed, respectively, and so as to cover these pressure-receiving diaphragms 3 and 4. Covers 5 and 6 are fixed to.

The material for each of the pressure receiving diaphragms 3 and 4 varies depending on the fluid to be measured, but stainless steel, titanium, tantalum, monel, etc. with excellent corrosion resistance are usually used, and the plate thickness is about 0.05 to 0.06 mm. Ru. In the figure, the pressure P _{H of the fluid to be measured on the upstream side of the orifice is introduced from the hole 7 of the cover 5 to the outer surface of the pressure receiving diaphragm 3 on the left side, and the pressure P H} on the upstream side of the orifice of the fluid to be measured is introduced from the hole 8 of the cover 6 to the outer surface of the pressure receiving diaphragm 3 on the right side. The pressure P _L of the fluid to be measured on the downstream side of the orifice is guided.

Further, each pressure-receiving side surface 1a, 1 of the body main body 1
Back-up plates 9 and 10, which serve as a pressure-receiving diaphragm protection device that characterizes the present invention, are arranged between the pressure-receiving diaphragms 3 and 4, and the peripheral edges thereof are arranged between the pressure-receiving diaphragms 3 and 4.
4 and the respective pressure-receiving side surfaces 1a, 1b.
Welded and fixed to the periphery of the These back-up plates 9, 10 are formed in a similar waveform to the respective pressure-receiving diaphragms 3, 4, and are disposed so as to face the diaphragms 3, 4 with a predetermined distance therebetween. At least one flow hole 11 through which the sealed liquid 2 can flow is formed. This is to guide the sealed liquid 2 into the gap between each backup plate 9, 10 and the pressure receiving diaphragm 3, 4, and to prevent a pressure difference from occurring between the front and back surfaces of the plates 9, 10. These backup plates 9 and 10 are made of stainless steel, Hastelloy, etc., and their thickness is set to be sufficiently larger than that of the pressure receiving diaphragms 3 and 4 (for example, 0.4
mm or more).

In this case, each pressure-receiving side surface 1a, 1 of the body main body 1
b does not have the protective function of the pressure receiving diaphragms 3 and 4, and is therefore formed as a flat surface. Also,
The back-up plates 9 and 10 do not need to be displaced by the pressures P _H and _PL of the fluid to be measured, and therefore, not only the peripheral portions but also the top portions of the corrugated surfaces facing the pressure-receiving sides 1 a and 1 b a may be fixed to the pressure-receiving sides 1a and 1b by spot welding or the like.

In the body main body 1, two sealed circuits 13,
14 are formed, and these encapsulated circuits 13,
The upper end of 14 is provided at the upper part of the main body 1,
Each of them communicates with an upper chamber 16 sealed by a hermetic seal 15, and the lower end thereof is opened at each of the pressure-receiving side surfaces 1a and 1b. The upper chamber 16
The liquid 2 is sealed in the housing 2, and a semiconductor sensor 20 is disposed therein. As shown in FIG. 3, the semiconductor sensor 20 includes a silicon base 21 disposed on the bottom surface 16a of the upper chamber 16, and a cup-shaped silicon wafer 22 disposed on the silicon base 21. A strain gauge 24 connected by a bridge due to diffusivity or the like is formed on the upper surface strain-generating portion of the semiconductor diaphragm 2.
3. Then, pressure is applied to the upper side of the semiconductor diaphragm 23 via the sealed circuit 13.
A pressure P _L is applied to the lower side through the encapsulation circuit 14 and the through hole 25 of the silicon base 21 _.
is given.

Next, a method of manufacturing the pressure receiving diaphragms 3, 4 and backup plates 9, 10 will be explained.
These are press-molded at the same time using the same mold. In that case, manufacturing is possible using two forming methods: draw forming shown in FIG. 4 and hydraulic forming shown in FIG. 5.

That is, the drawing method shown in FIG. 4 uses a die 30 and a punch 31 whose mating surfaces facing each other are formed into corrugated surfaces, and between these two there is a material 2 for the pressure-receiving diaphragm and the back-up plate. Molded material 3 made of thin metal plates
2 and 33 are placed one on top of the other, and these molded materials 32,
33 is pressed against the die 30 with a punch 31, a corrugated pressure receiving diaphragm and a back-up plate are simultaneously formed. At this time, a wrinkle presser is placed on the circumferential surface of the punch 31 to prevent wrinkles from forming in the molded materials 32 and 33 during narrowing.
6 is installed. This is to sandwich and fix the molded materials 32 and 33 between the die 30 and the die 30 before pressing, and to prevent the molded materials 32 and 33 from being drawn inside (to the center of the die) during pressing. .

Further, if an annular protrusion 37 and a recess 38 are formed correspondingly on the periphery of the mating surfaces of the die 30 and the punch 31, and an annular protrusion is provided on the periphery of the pressure receiving diaphragm and the back-up plate, it is possible to This has the advantage that it is easy to align the pressure receiving diaphragm and the backup plate at the time of use, and that mutual misalignment can be prevented.

On the other hand, the hydroforming method shown in FIG. 5 uses a die 30 and a cup-shaped cover member 39, and the peripheral edge of the two molded materials 32 and 33 is formed by the tip end surface of the peripheral wall of the cover member 39. is pressed against the peripheral edge of the molding surface of the die 30 via an O-ring 40, and a liquid such as oil or water pressurized to a predetermined pressure is injected into the space between the cover member 39 and the molding material 32. The molded materials 32 and 33 are plastically deformed by hydraulic pressure to form a corrugated pressure receiving diaphragm and a back-up plate at the same time. In this case, since uniform pressure is applied to the entire surface of the molding materials 32 and 33, good molding can be achieved without uneven elongation of the molding materials 32 and 33.

In the differential pressure transmitter configured as described above, during normal pressure measurement, a force corresponding to the differential pressure P _H - P _L is applied to the pressure receiving diaphragms 3 and 4 via the sealed liquid 2 as shown in Fig. 1. This force is applied to the semiconductor sensor 20 in the upper chamber 16 through the enclosed circuits 13 and 14. Therefore, the semiconductor diaphragm 23 is deformed _downward as shown by the two-dot chain line in _FIG . After being amplified, it is displayed on a meter or transmitted remotely.

Next, for example, when excessive pressure is generated on the upstream side of the orifice, the pressure receiving diaphragm 3 is deflected significantly to the right, and the back-up plate 9 receives this deflection, thereby preventing the pressure receiving diaphragm 3 from being damaged or deformed. In this case, as described above, the pressure receiving diaphragm 3 and the backup plate 9 are formed at the same time using the same mold and are formed into similar shapes with high precision, so that almost the entire surface of the pressure receiving diaphragm 3 is covered with the backup plate 9, and is not subjected to local stress, so that no permanent deformation occurs.

Similarly, when excessive pressure is generated on the downstream side of the orifice, the pressure receiving diaphragm 4 is deflected significantly to the left, and the back-up plate 10 receives this deflection to prevent the diaphragm 4 from becoming ink-shaped or being damaged.
Furthermore, the pressure receiving diaphragm 4 and the backup plate 10 are formed simultaneously using the same mold, similar to the above-mentioned pressure receiving diaphragm 3 and the backup plate 9, so that they have highly accurate similar shapes. Close pressure receiving diaphragm 4
No local stress is generated in this case, so no permanent deformation occurs in this case either. Therefore, good and highly accurate differential pressure measurement can be performed. In addition, since the back-up plates 9 and 10 are formed at the same time as the pressure-receiving diaphragms 3 and 4 are press-molded, they are extremely easy to manufacture, and are much easier to manufacture than forming the pressure-receiving sides 1a and 1b of the body body 1 into a wave shape. It is inexpensive and can significantly reduce manufacturing costs.

Further, each of the enclosed circuits 13 and 14 is normally provided with a throttle to prevent damage to the semiconductor sensor 20 due to excessive pressure, but the role of this throttle is played by the flow holes 11 formed in the respective backup plates 9 and 10.
is used instead, so there is no need to form the aperture.

[Effects of the Invention] As explained above, the pressure-receiving diaphragm protection device according to the present invention includes a back-up plate that has a similar shape to the diaphragm and faces the diaphragm with a predetermined distance between the pressure-receiving side surface of the body main body and the pressure-receiving diaphragm. Since the plate is configured to receive the pressure receiving diaphragm when excessive pressure occurs, it is possible to reliably prevent deformation or damage of the pressure receiving diaphragm, and the pressure receiving side of the body main body can be made in the same shape as the diaphragm. There is no need for processing and forming, and the body main body can be easily manufactured and provided at low cost.

Further, in the method of manufacturing a pressure receiving diaphragm protection device according to the present invention, the pressure receiving diaphragm and the backup plate are simultaneously formed by press molding, so that similar shapes with high precision can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a differential pressure transmitter equipped with a pressure receiving diaphragm protection device according to the present invention;
Fig. 2 is an enlarged sectional view of the main parts, Fig. 3 is an enlarged sectional view of the semiconductor sensor, Fig. 4 is a sectional view showing the method of forming the pressure receiving diaphragm and the backup plate, and Fig. 5 is an enlarged sectional view of the main part.
The figure is a sectional view showing another method of forming the pressure receiving diaphragm and the back-up plate. 1... Body main body, 1a, 1b... Pressure receiving side,
2...Pressure transmission sealed liquid, 3, 4...Pressure receiving diaphragm, 9, 10...Backup plate, 1
1... Distribution hole, 13, 14... Enclosed circuit, 20...
...Semiconductor sensor, 30...Dice, 31...Punch.

Claims (1)

[Scope of Claims] 1. In a device in which a corrugated pressure receiving diaphragm is disposed on the pressure receiving side of a body main body containing sealed liquid for pressure transmission, the pressure receiving diaphragm of the body main body is formed into a flat surface, and the pressure receiving diaphragm is A back-up plate having a similar shape to the pressure receiving diaphragm and facing at a predetermined distance is disposed on the side of the pressure-transmitting sealed liquid, and this back-up plate has a flow hole through which the pressure-transmitting sealed liquid can flow. A pressure receiving diaphragm protection device characterized in that the top portion of the corrugated surface on the sealed liquid side is in contact with the pressure receiving side surface. 2. A pressure-receiving diaphragm, which is disposed on the pressure-receiving side of the body main body that seals the pressure-transmitting liquid, has a pressure-receiving diaphragm that is disposed opposite to the side of the pressure-transmitting liquid with a similar shape to the diaphragm and with a predetermined spacing therebetween. 1. A method for manufacturing a pressure receiving diaphragm protection device, characterized in that a backup plate is overlapped and molded at the same time as the pressure receiving diaphragm is press-molded.