JPH0377939B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method for manufacturing a differential pressure transmitter suitable for use in measuring a pressure difference between two points, which is a process variable.

[Conventional technology]

Conventionally, this type of differential pressure transmitter applies each measurement pressure to the pressure-receiving diaphragms on the high-pressure side and the low-pressure side, and the movement of the pressure-transmitting liquid due to this pressure is converted into an electrical output by the distortion of a semiconductor sensor installed by partitioning an enclosed circuit. configured to be removed.

FIG. 1 shows a conventionally well-known differential pressure transmitter, which is also disclosed in Japanese Patent Application Laid-Open No. 56-87194, etc., and this will be briefly explained using the same figure.
Reference numeral 1 denotes a split detector body consisting of a large-diameter high-pressure side body 1a and a small-diameter low-pressure side body 1b, and a high-pressure side barrier diaphragm 2 and a low-pressure side barrier diaphragm 3 formed in a wave-shaped cross section on both sides. It is installed. A deep fit 5 is provided on the high pressure side body 1a in order to secure a space for attaching the neck member 4. The low pressure side body 1b is fitted into this fit 5, and both members 1
a and 1b are welded at the part indicated by A in the figure.
The barrier diaphragms 2 and 3 have high and low pressures caused by fluid flowing in from holes 8 and 9 between the detector body 1 and the covers 7 and 7 on both sides, which are fixed by bolts 6 through the detector body 1. are applied respectively. Further, a sensor capsule 10 is provided above the detector body 1 via a neck member 4, and a semiconductor sensor 11 is held on a sensor stand 12 and arranged in a sensor chamber 10a within this sensor capsule 10. has been done.

Reference numeral 13 denotes a center diaphragm having a wave-shaped cross section, and its periphery is attached to the detector body 1 so that the inner chamber provided at the central joint of the detector body 1 defines an inner chamber 14 on the high pressure side and an inner chamber 15 on the low pressure side. part is fixed. Reference numeral 16 designates a high-pressure side capillary tube for pressure transmission, which communicates with the high-pressure side inner chamber 14 and the lower side of the semiconductor sensor 11, and is provided in the high-pressure side body 1a and the neck member 4. Reference numeral 17 denotes a low-pressure side capillary tube having the same function as the high-pressure side capillary tube 16, which communicates with the low-pressure side inner chamber 15 and the upper side of the semiconductor sensor 11, and is connected to the low-pressure side body 1b,
It is provided within the high pressure side body 1a and the neck member 4.

Further, the inner chambers 14 and 15 are communicated with gaps 18 and 19 formed between the barrier diaphragms 2 and 3 and the detector body 1 through liquid passages 20 and 21, respectively. And the gaps 18, 19
A pressure transmitting liquid 22 such as silicone oil is sealed between the liquid passages 20, 21, the inner chambers 14, 15, and the capillary tubes 16, 17 to the lower and upper sides of the semiconductor sensor 11. In addition, 2
3 and 24 are liquid filling holes.

[Problem to be solved by the invention]

By the way, in the conventional differential pressure transmitter having the above-mentioned configuration, internal pressure is applied to the inner circumferential surface of the fit margin 5 during measurement as shown by the arrow in the figure, and pressure during welding is transmitted. Furthermore, since the fastening force is applied when the cover 7 is fixed to the detector body 1 with the through bolts 6, it is necessary to form the fit margin 5 with a thickness sufficient to withstand these external forces. Become. That is, if the fitting margin 5 is distorted, it will affect the output of the transmitter, making it impossible to perform a good differential pressure measurement. Furthermore, it is necessary to interpose a sealing member between the fit margin 5 and the cover 7, which increases not only the outer diameter of the detector body 1 but also the cover 7, resulting in a large device, contrary to recent demands for miniaturization. As it became more popular, it had its own shortcomings.

Further, in the case of both bodies 1a and 1b, a capillary tube 16 having directionality inside thereof,
17 and liquid filling holes 23 and 24, it is necessary to ensure the alignment of both bodies 1a and 1b before joining them, which makes the manufacturing work of the transmitter complicated. However, it is desired to eliminate these problems.

In particular, when manufacturing the above-mentioned differential pressure transmitter, the detector bodies are integrated by welding with a center diaphragm interposed between them, the sensor section is attached to the outer periphery of the sensor body, and a cover is attached to the outside of both bodies. It is necessary to integrate the whole by attaching it,
It is necessary to take some measures to improve the ease of assembly and manufacturing workability. Furthermore, when taking such measures, what is desired is to reduce the size of the entire transmitter, and such points must also be taken into consideration.

[Means to solve the problem]

In order to meet such demands, the method for manufacturing a differential pressure transmitter according to the present invention is to provide a method for manufacturing a differential pressure transmitter in which the opposite A notch is formed in a portion corresponding to a through-bolt insertion hole formed in a cover to be assembled to the end of the center diaphragm, with an outwardly directed arc-shaped portion extending along the opening edge of the through-bolt insertion hole. a step of forming and preparing the notch in advance and aligning both the detector bodies with the center diaphragm interposed therebetween; a step of welding the detector bodies; a step of forming a stepped pedestal having an axis perpendicular to the axes of both the detector bodies; a step of welding the cylindrical member to both the detector bodies after placing a cylindrical member with a built-in pressure sensor therein, and a step of fixing the cover to the anti-center diaphragm end of both the detector bodies with through bolts, respectively. The configuration includes the following.

[Effect]

According to the present invention, a detector body that is welded with a center diaphragm interposed therebetween is skillfully formed with an outward arcuate portion formed in correspondence with the insertion portion of a through bolt for attaching a cover attached to the outside thereof. By using a jig or the like to align these parts, it is extremely easy to perform, improve assembly, and facilitate manufacturing work, while also minimizing the outer circumferential shape of the detector body. , it is also possible to downsize the entire transmitter.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

2 and 3 show an embodiment of a differential pressure transmitter to which the present invention is applied. Here, the second
The figure is a sectional view of a main part of a differential pressure transmitter manufactured according to the present invention, and FIG. 3 is a side view of the differential pressure transmitter with the cover removed.

In these figures, 31 and 32 are two disc-shaped detector bodies joined by welding from the radial direction, and both of these bodies 31 and 32 are formed with the same diameter dimension and have a high-pressure side inner diameter. Two chambers, a chamber 33 and a low-pressure side inner chamber 34, are opposed to each other via a center diaphragm 35. Further, a high-pressure side barrier diaphragm 36 and a low-pressure side barrier diaphragm, which are formed in a wave-shaped cross section, are attached to the anti-center diaphragm ends of both the detector bodies 31 and 32, and the outer sides of these barrier diaphragms 36 and 37 are , through bolt 3
8, the covers 39 and 40 are fixed.

Reference numeral 41 denotes a positioning notch formed in the outer circumferential surface of both the detector bodies 31 and 32 and having an outward arc shape, and a through-bolt insertion hole 42 formed in the covers 39 and 40. has an arcuate portion extending along the opening edge of both detector bodies 3.
They are formed at predetermined locations (four locations as shown in FIG. 3) on the outer circumferential surfaces of Nos. 1 and 32.

Reference numeral 43 denotes a stepped pedestal, which is attached to both the detector bodies 3.
It has an axis in a direction perpendicular to the axes of detector bodies 31 and 32, and is formed over a part of the central outer peripheral surface of both detector bodies 31 and 32. Reference numerals 44 and 45 are two large and small cylindrical members having different outer diameters, and the pedestal 43 is erected by welding to a lower pedestal 43a and an upper pedestal 43b, respectively. A pressure sensor (not shown) is built in the small diameter cylinder member 45 of these cylinder members 44, 45, and a pressure sensor (not shown) is placed between the cylinder member 45 and the large diameter cylinder member 44 above the pressure sensor. An annular passage 46 is formed to guide the flow. Reference numerals 47 and 48 denote first and second pressure transmission passages communicating with the inner chambers 33 and 34, respectively, which open into the annular passage 46 inside the small-diameter cylindrical member 45, that is, below the pressure sensor, and which are connected to the detector body. 31 and 32. In addition, each of the barrier diaphragms 3
Spaces 49, 50 formed between the detector bodies 31, 32 and the inner chambers 33, 34 are communicated by liquid passages 51, 52. and,
From the spaces 49 and 50 to the liquid passages 51 and 52 and the inner chamber 3
3, 34 and pressure transmission passages 47, 48, a pressure transmission liquid 53 such as silicone oil is sealed between the lower side and the upper side of the pressure sensor. Note that 54 and 55 are holes for liquid sealing.

In a differential pressure transmitter with such a configuration,
When high pressure and low pressure from the process are respectively applied to the barrier diaphragms 36 and 37, the barrier diaphragms 36 and 37 are recessed and the pressure transmission liquid 53 moves by the amount of compression, and the pressure transmission liquid 53 is reduced due to the pressure difference on both sides. A pressure sensor detects the difference in the amount of movement and transmits this as an electrical signal, thereby measuring the differential pressure.

According to the differential pressure transmitter having such a configuration, the two disc-shaped detector bodies 31 and 32 having the same diameter are integrated by welding with the center diaphragm 35 interposed, and both detector bodies are welded together. Assemble the covers 39 and 40 to the anti-center diaphragm ends of 31 and 32, respectively, and tighten the through bolts 3.
8, when integrating the whole body, the cover 3 is
A notch 41 having an arc-shaped portion extending along the opening edge of the through-bolt insertion hole 42 is provided at a corresponding portion of the through-bolt insertion hole 42 bored in the holes 9 and 40.
is prepared in advance and a jig (not shown) is attached using this notch 41 as a reference, and then both detector bodies 31 and 32 are aligned with the center diaphragm 35 interposed therebetween. Therefore, there is an advantage that alignment of both the detector bodies 31 and 32 and welding of the joints thereof can be easily performed.

That is, by welding the two disk-shaped detector bodies 31 and 32 facing each other via the center diaphragm 35 in the above-mentioned aligned state, this work can be performed appropriately, reliably, and easily. After this welding, a step-shaped pedestal 43 having an axis perpendicular to the axes of both detector bodies 31, 32 is attached to a part of the outer circumferential surface of both detector bodies 31, 32 to remove the bead formed by the welding. By machining including the raised portion, the two cylindrical members 44 and 45, a large and small cylindrical member, which are formed astride between both detector bodies 31 and 32 and have a built-in pressure sensor in this pedestal 43, can be stabilized. After placing it in the condition,
These cylindrical members 44 and 45 are connected to both detector bodies 3.
By welding to the detector bodies 1 and 32, the sensor section can be simply and appropriately directly welded and fixed to the detector bodies 31 and 32. And after that,
Attach the cover 3 to the anti-center diaphragm ends of both detector bodies 31 and 32 with through bolts 38, respectively.
By fixing 9 and 40, a differential pressure transmitter can be easily manufactured.

〔Effect of the invention〕

As explained above, according to the method of manufacturing a differential pressure transmitter according to the present invention, the anti-center point of two disc-shaped detector bodies having the same diameter size that are integrated with a center diaphragm interposed is A notch having an outwardly directed arcuate portion extending along the opening edge of the through-bolt insertion hole is formed in advance at a portion corresponding to the through-bolt insertion hole drilled in the cover to be assembled to the diaphragm end. and aligning both the detector bodies with the center diaphragm interposed therebetween, using the notch as a reference, and two disc-shaped detector bodies facing each other with the center diaphragm in between. a step of forming a stepped pedestal having an axis perpendicular to the axes of both detector bodies over a part of the outer peripheral surface of both of the detector bodies; and a step of welding a pressure sensor to the pedestal. after placing a cylindrical member containing a built-in cylindrical member, the cylindrical member is welded to both of the detector bodies, and the cover is fixed to each end of the detector body opposite to the center diaphragm with a through bolt. Despite the simple structure, the detector body has the same diameter and is welded with the center diaphragm interposed, and the through bolts for attaching the cover attached to the outside of the detector body can be welded to the same diameter. By skillfully utilizing the formed outward arc-shaped portion, these parts can be aligned extremely easily using a jig, etc., and is excellent in terms of ease of assembly.This makes welding work between the bodies easier. It has various excellent effects, such as being extremely easy and reliable, and greatly improving the workability of manufacturing the transmitter. In particular, by forming the notch on the body side as described above, it is possible to provide the through-bolt insertion hole closer to the center of the cover than in the past. The outer circumferential shape of can be formed to the minimum required size,
As a result, there is an advantage that the entire transmitter can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a differential pressure transmitter for explaining the prior art, FIG. 2 is a schematic cross-sectional view of a differential pressure transmitter manufactured according to the present invention, and FIG. FIG. 3 is a schematic side view showing a state with the cover removed. 31, 32...detector body, 35...center diaphragm, 38...through bolt, 39,40
... Cover, 41 ... Notch formed by arc-shaped part, 4
2... Through bolt insertion hole, 43... Pedestal, 4
4, 45... Cylindrical member.

Claims (1)

[Claims] 1. Integrate two disc-shaped detector bodies with the same diameter with a center diaphragm interposed, and assemble a cover on each end of both detector bodies opposite to the center diaphragm and integrate the whole body with a through bolt. A method for manufacturing a differential pressure transmitter, wherein the method comprises: applying a needle to a portion corresponding to a through-bolt insertion hole formed in the cover on the outer circumferential surface of both detector bodies, along an opening edge of the through-bolt insertion hole; a step of preparing a cutout having an outwardly extending circular arc portion in advance and aligning both of the detector bodies with the center diaphragm interposed therebetween using the cutout as a reference; A step of welding two disc-shaped detector bodies facing each other via a diaphragm from the outer diameter direction, and a step-shaped pedestal having an axis perpendicular to the axis of both detector bodies. a step of forming the cylindrical member that straddles a part of the outer circumferential surface of the pressure sensor; a step of placing a cylindrical member containing a built-in pressure sensor on the pedestal, and then welding the cylindrical member to both of the detector bodies; A method of manufacturing a differential pressure transmitter, comprising the step of fixing a cover to the opposite end of the center diaphragm with through bolts.