JP2001318017A - Differential pressure and pressure transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily carry out attaching and detaching work for a cover in an atmospheric pressure side by simple structure, and to make dust, an insect and the like easily removed even when they come into an inside of the cover. SOLUTION: The disklike cover 27 is composed of a cover body 27A having a size substantially same to a sideface 8 in the atmospheric pressure side of a detector body 24, and for covering a seal diaphragm 9, and four supporting parts 27B foldedly formed in an outer circumference of the cover body 27A with equal spacing. The cover body 27A is separated from the detector body 24 to form a proper gap G, by fixing the supporting parts 27B onto the body 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure / pressure transmitter for measuring a pressure in a process fluid or a tank using atmospheric pressure as a reference pressure, and more particularly to a structure for mounting a cover for covering the atmospheric pressure side.

[0002]

2. Description of the Related Art As a method of using such a type of differential pressure / pressure transmitter used for measuring the pressure or the like of various process fluids, there are a method of utilizing a pressure difference between two points of a process fluid, A method of measuring with a vacuum pressure as a reference pressure,
There are three types of methods for measuring with atmospheric pressure as a reference pressure, and the present invention particularly relates to a differential pressure / pressure transmitter for measuring with atmospheric pressure as a reference pressure.

When the atmospheric pressure is measured as a reference pressure, one of two seal diaphragms attached to the transmitter body is opened to the atmospheric pressure, and the measurement is performed by introducing the process fluid pressure to the other. In a closed tank such as a high-temperature reaction tower in a petroleum refining plant, the liquid level and the tank internal pressure are measured by detecting the tank internal pressure from the pressure difference from the atmospheric pressure.

FIG. 5 is a front view showing a part of a conventional differential pressure / pressure transmitter of the atmospheric pressure standard type.
The differential pressure / pressure transmitter 1 is constituted by the header 3 and the covers 6 and 7 on the atmospheric pressure side and the measurement pressure side, which are fixed together on both sides of the transmitter main body 2 by a plurality of bolts 4 and nuts 5. I have. The transmitter main body 2 is formed in a thick disk shape, and an atmospheric pressure side seal diaphragm 9 is disposed on the atmospheric pressure side surface 8 by welding an outer peripheral portion thereof. Protected. Atmospheric pressure side cover 6
An atmospheric pressure chamber 10 is formed between the seal diaphragm 9 and the atmospheric pressure chamber 10, and the atmospheric pressure chamber 10 is communicated with the outside by an atmosphere opening groove 11 formed in the cover 6. Therefore, the atmospheric pressure Po is applied to the atmospheric pressure side seal diaphragm 9.

On the other hand, the side surface 12 of the transmitter body 2 on the measurement pressure side
The measurement pressure side seal diaphragm 13 is also provided by welding the outer peripheral portion, and is covered by the measurement pressure side cover 7. A pipe 15 for guiding a process fluid 14 to the measurement pressure side seal diaphragm 13 is connected to the measurement pressure side cover 7.

Atmospheric pressure P is applied to the atmospheric pressure side seal diaphragm 9.
When o is applied and the process fluid pressure P1 is led to the measurement pressure side seal diaphragm 13, both diaphragms 9, 13 are displaced in accordance with the pressure, and this displacement is caused by the filling liquids 16a, 16b.
Through a pressure sensor (not shown) such as a semiconductor pressure sensor, and the differential pressure (P1-Po) is detected.

[0007]

In the above-mentioned conventional atmospheric pressure reference type differential pressure / pressure transmitter 1, a cover for protecting the seal diaphragm 9 on the atmospheric pressure side from damage, adhesion of dust, insects and the like is provided. Covered by 6. However, since the conventional cover 6 is mounted close to the seal diaphragm 9, the gap 17 opened to the atmosphere is very narrow, and small dust enters the gap 17 or insects enter the nest. If it is made, the atmospheric pressure chamber 10 is closed, and there is a problem that a measurement error occurs. When the gap is clogged, to remove the clogged one, the bolt 4 is removed and the cover 6 is removed from the transmitter main body 2 or the nut 5 is loosened to remove the cover 6 from the transmitter main body 2.
There is no other choice but to remove the clogged object by separating from it, and there is a problem that the operation is troublesome. In particular, after removing the clogging, tighten the nut 5 to cover
Is fixed, the sealing performance between the transmitter body 2 and the cover 7 is reduced if the tightening is loose.
4 may leak.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to easily attach and remove an atmospheric pressure side cover with a simple structure. Another object of the present invention is to provide a differential pressure / pressure transmitter capable of easily removing dust and insects even if they enter the inside of the cover.

In order to achieve the above object, a first invention is to provide
In the differential pressure / pressure transmitter in which the atmospheric pressure side seal diaphragm of the transmitter body is covered with a cover, the cover is fixed to the transmitter body and the cover body covering the atmospheric pressure side seal diaphragm. And a supporting portion that is separated from the transmitter main body and supported.

According to a second aspect, in the first aspect, at least a part of the cover body has a mesh structure.

According to a third aspect, in the first aspect, a gap between the cover main body and the transmitter main body is covered with a mesh structure.

In the present invention, since an appropriate gap is formed between the cover main body and the transmitter main body, small dust drops from this gap and does not stay inside. In the case of insects, it is easy to get in and out and it is difficult to create a nest inside. Further, even if dust or insects enter the inside, the dust or insects can be removed from the gap without removing the cover. As the fixing structure by the support portion, engagement between the engagement portion and the engagement portion, a set screw, or the like can be considered. The mesh structure makes it easy to see the inside of the cover, and can easily check whether dust or insects have entered. In addition, intrusion of dust, insects, and the like from around the cover body can be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a sectional view showing an embodiment in which the present invention is applied to an atmospheric pressure reference type differential pressure / pressure transmitter provided with a pressure receiving adapter, and FIG. 2 is a perspective view of a reference pressure side cover. Note that the same components as those described in the related art are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

Depending on the nature of the process fluid, problems such as corrosion may occur with standard diaphragms. In order to solve this, a differential pressure / pressure transmitter is attached to the process fluid container, piping, etc. via an adapter, and the process fluid pressure is received by the corrosion resistant wetted diaphragm provided on this adapter, and the displacement is applied to the pressure. The signal is transmitted to the seal diaphragm of the transmitter via the transmission medium. In addition, an adapter having a similar structure is used to protect the transmitter from a particularly high-temperature process fluid. In the present invention, such an adapter is referred to as a pressure receiving adapter.

In FIG. 1, a differential pressure / pressure transmitter 20 is
The transmitter body 2 and an adapter mounting member 22 are provided, and a pressure receiving adapter 23 is detachably mounted on the adapter mounting member 22. The transmitter body 2 includes a detector body 24 and a header 3. The adapter mounting member 22 is attached to the side surface 12 on the measurement pressure side and the side surface 8 on the atmospheric pressure side of the detector body 24.
And a cover 27 are respectively attached.

The detector body 24 is formed by integrally joining two disk-shaped bodies 24a and 24b by electron beam welding or the like.
The seal diaphragms 9 and 13 are disposed on the outer peripheral portion 12 by welding the outer peripheral portions. The seal diaphragms 9 and 13 are generally formed in a disk shape by plastically processing a thin metal plate such as phosphor bronze or beryllium copper. At the time of forming the work, the part receiving the pressure in the inner part from the outer peripheral fixing part, that is, by applying a wavy fold in the radial direction to the pressure receiving part concentrically, to increase the compliance of the diaphragm, in other words, to soften the diaphragm,
The linear range that satisfies the load-displacement equation is widened. The portions of both sides 8 and 12 of the detector body 24 facing the pressure-receiving portions of the seal diaphragms 9 and 13 are attached by forming wavy folds of the same shape as these diaphragms concentrically in the radial direction. The bottom portions 8a and 12a are formed. This prevents the seal diaphragms 9 and 13 from being plastically deformed or damaged by causing the seal diaphragms to land on the bottom portions 8a and 12a when an excessive pressure equal to or more than a predetermined pressure acts on the seal diaphragms 9 and 13. This is to prevent pressure exceeding a predetermined value from being applied to the pressure sensor 30.

At the center of the inside of the detector body 24,
A center diaphragm 32 that partitions the inner chamber 31 provided on the joint surface between the bodies 24a and 24b into two body inner chambers 31a and 31b is provided by welding the outer peripheral edges. Diaphragm chambers 33a and 33b are formed between the back surfaces of the seal diaphragms 9 and 13 and the side faces 8 and 12 of the detector body 24, and these diaphragm chambers 33a and 33b and the body inner chamber 31a are formed. , 31
b is communicated with each other by the sealing circuits 34a and 34b. A portion inside the outer peripheral fixed portion of the center diaphragm 32 forms a pressure receiving portion. In this pressure receiving portion, corrugated folds are formed concentrically in the radial direction similarly to the seal diaphragms 9 and 13. The body inner chamber 31a,
Also on the inner wall surface of 31b, corrugated folds having the same shape as the center diaphragm 32 are formed concentrically in the radial direction. The sealing circuits 34a and 34b are provided with holes 35 for sealing liquid.
Filled liquids 16a and 16b such as propylene glycol and silicone oil, which are pressure transmission media, are filled from a and 35b, respectively. The filled liquid filling holes 35a and 35b are
Each ball is sealed by a ball 36,
Is prevented by a set screw 37.

The header 3 is integrally joined to the outer peripheral surface of the detector body 24, and incorporates the semiconductor pressure sensor 30 and a signal processing circuit inside. The semiconductor pressure sensor 30 has a semiconductor diaphragm 30a,
On the front and back surfaces, the filling liquids 16a and 16b are filled with a filling circuit 34.
c, 34d.

The adapter mounting member 22 is formed in a cylindrical body of different diameter having a communication hole 40 formed of a through hole, and a back surface of the large diameter portion 22A forms a joint surface.
Is fixed to the side surface on the measurement pressure side by welding to cover the seal diaphragm 13. The communication hole 40 communicates with a chamber on the front surface of the seal diaphragm 13, that is, a front side chamber 41 formed between the seal diaphragm 13 and the adapter mounting member 22 by opening one end to the back side, and the seal diaphragm 13 is opened. And is facing. On the other hand, the other end is opened at the distal end surface of the adapter mounting member 22 to form an open end on the atmosphere opening side.
Further, a cleaning hole 44 used for cleaning the adapter mounting member 22 is formed inside the large-diameter portion 22A, and the cleaning hole 44 is formed by a sealing means 47 comprising a ball 45 and a set screw 46. Sealing. The small diameter portion 22B of the adapter mounting member 22 forms a mounting portion for the pressure receiving adapter 23. An external thread 48 is formed on the outer periphery, and the pressure receiving adapter 23 is screwed via a seal member 49.

The pressure receiving adapter 23 is formed in a cylindrical body integrally having a flange 51 on the outer peripheral surface on the distal end side, and the flange 51 is closely attached to the pipe 15 of the process fluid 14 via a sealing member 52, and is clamped by a clamp device 53. Fixed. A liquid contacting diaphragm 55 made of a material having excellent corrosion resistance such as stainless steel is attached to the joint surface of the pressure receiving adapter 23 with the pipe 15 by welding the outer peripheral portion. Wetted diaphragm 55
A pressure receiving portion is formed on the inner side of the outer peripheral fixed portion of the, and a corrugated fold is formed concentrically in the radial direction on the pressure receiving portion. Also, the same-shaped corrugated folds are formed concentrically in the radial direction on the joint surface of the pressure-receiving adapter 23 facing the pressure-receiving portion to form the bottoming portion 54.

The pressure receiving adapter 23 has a screw hole 56 which is opened on the back side and into which the male screw 48 of the adapter mounting member 22 is screwed. A pressure guiding path 57 and a sealing hole 58 are formed inside. I have. One end of the pressure guide path 57 communicates with a diaphragm chamber 60 formed between the back surface of the liquid contacting diaphragm 55 and the pressure receiving adapter 23, and the other end is opened to the screw hole 56 so that the adapter mounting member is formed. It communicates with 22 communication holes 40. And, in the pressure guiding path 57,
A filling liquid 61 is filled from the filling hole 58. The filled liquid 61 is filled in the diaphragm chamber 60 and the communication hole 40.
Also, it is sealed in the front side chamber 41. In addition, 62 is a ball and 63 is a set screw.

In FIG. 1 and FIG.
Is formed by pressing a thin metal plate, and has a disk-shaped cover main body 27A having substantially the same size as the atmospheric pressure side surface of the detector body 24 and covering the seal diaphragm 9. And four support portions 27B bent at equal intervals on the outer periphery of the cover main body 27A. The support portion 27B separates the cover main body 27A from the seal diaphragm 9 and the detector body 24 by being fixed to the detector body 24. As a fixing structure of the support portion 27B, for example, the support portion 27B is formed in a plate shape having an appropriate width and elasticity, and an engagement portion 66 having a triangular cross section is protruded from an inner surface thereof. If it is detachably fixed by engaging with a locking portion formed on the detector body 24 side, or if the support portion 27B is formed in an L-shape and its tip is fixed to the detector body 24 with a set screw. Good. Therefore, the work of attaching and detaching the cover 27 is easy, and
With A, the sealing diaphragm 9 can be reliably protected. Also, between the side surface on the atmospheric pressure side of the detector body 24 and the cover main body 27A, there are formed appropriate gaps G separated by the support portion 27B and opened in four directions, up, down, left, and right, so that dust is formed. Even if it invades, it does not accumulate inside, it is difficult for insects to form nests, and even if dust or insects enter the inside of the cover 27, it can be easily removed without removing the cover 27.

FIGS. 3 and 4 show another embodiment of the cover. FIG. 3 shows an example in which the cover main body 27A 'is formed in a ring shape and the central opening 67 is covered with a wire mesh 68 to form a mesh structure. FIG. 4 shows an example in which a mesh structure is formed by similarly covering between adjacent support portions 27B with a wire mesh 68. In the case of such a mesh structure, particularly the mesh structure shown in FIG. 3, the inside of the cover can be seen,
Whether or not dust or insects have invaded can be easily visually recognized, and when the mesh structure shown in FIG. 4 is employed, intrusion of dust or insects can be reliably prevented.

The differential pressure / pressure transmitter 2 having the above structure
At 0, when the atmospheric pressure Po and the pressure P1 of the process fluid 14 are respectively applied to the seal diaphragm 9 and the liquid contact diaphragm 55, these diaphragms 9, 55 are displaced in accordance with the pressure. The displacement of the seal diaphragm 9 is
It is transmitted to the center diaphragm 32 via the filling liquid 16a. On the other hand, the displacement of the liquid contact diaphragm 55 is transmitted to the seal diaphragm 13 via the filling liquid 61. Therefore, the seal diaphragm 13 is also displaced, and the displacement of the seal diaphragm 13 is further transmitted to the center diaphragm 32 via the filling liquid 16b. As a result, the center diaphragm 32 is displaced according to the differential pressure (P1−Po), and this displacement is transmitted to the semiconductor diaphragm 30a of the semiconductor pressure sensor 30 via the sealed liquids 16a and 16b. Therefore, the semiconductor diaphragm 30a is distorted in accordance with the differential pressure (P1-Po), and the amount of the distortion is converted into an electric signal and taken out, thereby obtaining the process fluid 14a.
, The tank internal pressure, etc. can be measured.

In the above-described embodiment, an example is shown in which the present invention is applied to a differential pressure / pressure transmitter provided with the pressure receiving adapter 23. However, the present invention is not limited to this. The present invention can also be applied to an open-to-atmosphere type differential pressure / pressure transmitter in which covers on the atmospheric pressure side and the measurement pressure side are attached to both sides.

[0026]

As described above, according to the present invention, the differential pressure
The pressure transmitter has a cover on the atmospheric pressure side composed of a cover body that covers the seal diaphragm on the atmospheric pressure side and a support portion that supports the cover body, and the support portion is fixed to the transmitter body to transmit the signal to the cover body. The cover is simple and inexpensive because it is designed to form a required gap between the container and the main unit.It is easy to install and remove. It is difficult, and even if accumulated, it can be easily removed without removing the cover. Further, according to the present invention, since a part of the cover has a mesh structure, it is possible to easily confirm whether dust or insects are invading, and in particular, a gap between the cover main body and the transmitter main body is meshed. Covering with a structure can surely prevent intrusion of dust and insects.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which the present invention is applied to an atmospheric pressure reference type differential pressure / pressure transmitter having a pressure receiving adapter.

FIG. 2 is a perspective view of a reference pressure side cover.

FIG. 3 is a perspective view showing another embodiment of the cover.

FIG. 4 is a perspective view showing still another embodiment of the cover.

FIG. 5 is a partially cutaway front view of a conventional differential pressure / pressure transmitter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Differential pressure / pressure transmitter, 2 ... Transmitter main body, 3 ... Header, 6 ... Atmospheric pressure side cover, 7 ... Measurement pressure side cover, 8 ... Atmospheric pressure side side, 9 ... Atmospheric pressure side seal diaphragm, 13
... Measurement pressure side seal diaphragm, 27 ... Cover, 27
A, 27 ': cover body, 27B: support, 68: wire mesh.

Claims (3)

[Claims] 1. A differential pressure / pressure transmitter in which an atmospheric pressure side seal diaphragm of a transmitter main body is covered with a cover, wherein the cover is fixed to the cover main body covering the atmospheric pressure side seal diaphragm and the transmitter main body. A differential pressure / pressure transmitter, wherein the cover main body is configured to be separated from the transmitter main body and supported. 2. The differential pressure / pressure transmitter according to claim 1, wherein at least a part of the cover main body has a mesh structure. 3. The differential pressure / pressure transmitter according to claim 1, wherein a gap between the cover main body and the transmitter main body is covered with a mesh structure.