JPH05281064A - Pressure transducer - Google Patents

Abstract

PURPOSE:To provide a pressure transducer which can detect the pressure of corrosive fluid under superhigh pressure. CONSTITUTION:A pressure transducer, which leads fluid inside the pressure detecting chamber 39 of a main body 31, and causes strain in the main body 31 by the pressure of the led fluid, and detects the pressure on the quantity of the strain, integrally has a bag-shaped bellows 60 which has a shape suiting to the internal shape of a pressure detecting chamber 39 and can be displaced by the pressure of fluid. The fluid is led inside the bellows 60, by which the inside of the main body 31 is isolated from the fluid, and sealing liquid is filled up in the outside of the bellows 60, by which the main body 31 is protected from the corrosive fluid. The filling up quantity of the sealing liquid is extremely lessened by the built-in bellows 60 to make the quantity of its contraction slight even if the sealing liquid is made to contract under superhigh pressure. Thus the bellows 60 is protected from damage caused by a large displacement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure transducer, which can be used as a pressure transmitter for detecting the pressure of a corrosive liquid pressurized to an ultrahigh pressure.

[0002]

2. Description of the Related Art Conventionally, various types of pressure transducers have been used when measuring the fluid pressure in a pipeline or a container. As such a pressure converter, a fluid inlet is provided in the body which is a sealed container to introduce the pressure of the fluid into the inside, and the pressure of the fluid causes strain in the body of the transducer. There is one that detects pressure.

In such a strain detection type pressure converter, by adopting a structure and material capable of sufficiently withstanding an ultrahigh pressure, the main body into which the fluid is introduced can be applied to an ultrahigh pressure (about 10,000 kgf / cm ² ) fluid. The pressure of can be detected.

[0004]

However, the material forming the main body of the pressure transducer must withstand ultra-high pressure and
There is no excellent corrosion resistance, and it is impossible to introduce corrosive ultra-high pressure fluid into the main body. Therefore, the conventional pressure converter has a problem that the pressure of the corrosive fluid cannot be detected at an ultrahigh pressure.

In order to detect the pressure of the corrosive fluid, it may be considered to employ a diaphragm type pressure converter having a sealing member such as a diaphragm inside. However, in the conventional diaphragm type pressure transducer, an encapsulant for transmitting pressure is filled between the main body and the seal member, and the volume of the encapsulant contracts due to the pressure of the fluid under ultrahigh pressure. Due to the volume contraction, the seal member is displaced more than necessary, and the seal member is largely deformed and damaged. Therefore, the diaphragm type cannot solve the above-mentioned problem.

An object of the present invention is to provide a pressure transducer capable of detecting the pressure of corrosive fluids at ultrahigh pressure.

[0007]

According to the present invention, a fluid is introduced into a bag-shaped body, the pressure of the fluid causes a strain in the body, and the pressure is controlled by an appropriate signal based on the strain amount. In the pressure transducer for converting into a body, a bag-shaped seal member having a shape corresponding to the inner shape of the main body and displaceable by the pressure of the liquid is built in, and the fluid is introduced into the inside of the seal member. The sealant is filled with an encapsulant on the outside.

Here, as the seal member, it is desirable to employ a bellows which can be displaced along the axial direction of the cylindrical main body of the pressure converter.

[0009]

According to the present invention as described above, a part of the fluid whose pressure is to be detected is introduced into the inside of the seal member, the pressure of the fluid is transmitted to the encapsulant through the seal member, and the encapsulant is used for the main body. A strain is generated, and the pressure of the fluid is detected based on the strain amount.

The pressure of the corrosive fluid can be detected by separating the main body of the pressure transducer from the fluid to be detected by the seal member and using a seal member having excellent corrosion resistance.

Here, since the seal member having a shape corresponding to the internal shape is built in the cavity of the main body, the volume of the encapsulant filled in the space between the main body and the body can be made extremely small. For this reason, the influence of the volume compression of the encapsulant can be made small, the contraction of the encapsulant is extremely small even when subjected to an ultrahigh pressure, and the seal member is not largely deformed even at an ultrahigh pressure. It becomes possible to avoid inconveniences such as breakage of the above, and these can achieve the above object.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a pressure transmitter 1 according to the present embodiment. The transmitter 1 has a cylindrical case 10 in which a measuring circuit unit 20, a pressure converter 30 and the like are housed.

The case 10 has a cylindrical shape with one end open and the other end closed. A through hole 11 is provided in an upper surface portion of the case 10, and a cylindrical terminal portion 12 accommodating an external wiring terminal is fitted and fixed in the through hole 11. The terminal section 12 enables the internal measurement circuit section 20 to be electrically connected to an external measurement device or the like.

The measuring circuit section 20 is one in which various electric elements are arranged on the substrate 21, and the electric signal obtained by the pressure converter 30 is adjusted into an electric signal of a predetermined standard.

The pressure converter 30 is provided with a cylindrical main body 31 which is distorted by the pressure introduced therein, and a strain gauge 32 for detecting the amount of strain of the main body 31.

The main body 31 has a shape in which two cylinders, each of which has a thin neck portion 33 and a thick body portion 34 having different diameters, are stacked in two stages. An insertion passage 35 is formed. Here, one end of the insertion passage 35 on the neck portion 33 side is closed, and the other end on the body portion 34 side is open.

The neck portion 33 has a side wall 36 for causing a strain due to an ultrahigh pressure introduced therein. The strain gauge 32 is attached to the surface of the side wall 36. To protect this strain gauge 32, neck 33
A cover 40 is placed over the cover. This cover 40 is the main body
It is welded to 31, and is filled with an inert gas such as nitrogen gas.

On the upper surface of the cover 40, the above-mentioned measurement circuit section 20
Is fixed and an insertion hole 41 is provided. The insertion hole 41 is closed by a hermetic seal 42 so that the inert gas sealed inside does not leak outside.
The hermetic seal 42 is provided with an electrode 43 penetrating itself. The electrodes 43 electrically connect the strain gauge 32 inside and outside the cover 40 and the measurement circuit unit 20.

The body portion 34 has an insertion passage on a surface facing downward in the drawing.
A connection port 37 in which the diameter of 35 is enlarged is provided.

A thread groove is provided on the inner surface of the connection port 37. On the inner upper surface of the connection port 37, a mortar-shaped inclined portion 38 formed by cutting out the peripheral edge of the entrance to the insertion passage 35 and chamfering is provided. In this connection port 37,
Fittings for connecting to pressure vessels, pressure piping, pressure guiding piping, etc.
50 can be screwed.

The joint 50 is provided with a fluid introduction passage 51 at its central portion so as to penetrate the entire length in the longitudinal direction. Fitting
As a material of 50, a material having good corrosion resistance, such as stainless steel, can be adopted.

An engaging portion 52 having a hexagonal cross section is provided at the center of the joint 50. Screw shaft portions 53 and 54 are provided on both sides of the engaging portion 52, respectively. A mortar-shaped inclined portion 55 is formed in the center of the upper surface of the joint 50 in the drawing. A slender cylindrical tube portion 56 extending upward is provided on the top of the inclined portion 55.

The joint 50 is fixed to the main body 31 by screwing with the main body 31 in a state where the pipe portion 56 is inserted into the insertion passage 35 of the main body 31. As a result, the inclined portion 55 of the joint 50 and the inclined portion of the main body 31
38 and 38 are in close contact with each other, and the inlet portion of the insertion passage 35 can be sealed with a joint 50.

The tube portion 56 has a length that reaches a predetermined intermediate position in the insertion passage 35. As shown in FIG. 2, a ring-shaped collar member 57 is attached to the tip of the pipe portion 56 by hair leak welding. Here, the portion of the insertion passage 35 above the collar member 57 in the drawing is located inside the side wall 36 of the neck 33 and serves as a pressure detection chamber 39 which is a cavity for detecting pressure. Inside the pressure detection chamber 39, a bellows 60 as a bag-shaped seal member is built.

The bellows 60 is formed in a substantially cylindrical shape according to the internal shape of the pressure detection chamber 39. As a material of the bellows 60, a material having excellent corrosion resistance, such as stainless steel, can be adopted. The open base end of the bellows 60 is fixed to the front end of the collar member 57 by electron beam welding, and the fluid that has passed through the fluid introduction path 51 is not covered by the bellows 60.
It is supposed to be introduced inside. This bellows 60
The pressure detection chamber 39 is isolated from the fluid whose pressure is detected by. In the middle part of the bellows 60,
A bellows portion 61 is provided. As a result, the closed tip portion of the bellows 60 expands (extends) toward the end portion of the pressure detection chamber 39 as the fluid pressure increases.

Outside the bellows 60 in the pressure detection chamber 39,
Filled with mounting medium. As the encapsulant, a liquid having good incompressibility even under ultrahigh pressure, such as glycerin or mercury, can be adopted.

In this embodiment as described above, the pressure transmitter 1 is mounted by connecting the joint 50 to a pressure vessel or the like containing an ultrahigh pressure fluid whose pressure is to be detected, and the above-mentioned structure is provided inside the bellows 60. Introduce fluid. Then, the bellows 60 is expanded according to the pressure of the fluid, the expanded bellows 60 compresses the encapsulant in the pressure detection chamber 39, and the side wall 36 of the pressure detection chamber 39 is distorted by the compression force of this encapsulant. Let The pressure of the fluid is detected as the amount of strain generated on the side wall 36 and converted into an electric signal by the strain gauge 32. This electric signal is converted into an electric signal proportional to the pressure by the measuring circuit section 20, and is output to an external measuring device or the like via the terminal section 12.

According to this embodiment as described above, the following effects can be obtained. That is, since the body 31 of the converter 30 is isolated from the fluid whose pressure is to be detected by the bellows 60 having excellent corrosion resistance, the body 31 can be prevented from being corroded even if the fluid is corrosive.

Further, since the bellows 60 having a shape corresponding to the internal shape of the main body 31 of the converter 30 is incorporated, the volume of the bellows 60 is increased so that the volume of the main body 31 is not reduced and the filling of the encapsulant is performed. The amount can be made very small, and the shrinkage of the encapsulant due to ultrahigh pressure can be made extremely small accordingly. Therefore, a large displacement or vibration of the bellows 60 due to a steady pressure fluctuation can be suppressed, and the bellows 60 can be prevented from being damaged even under an extremely high pressure.

Therefore, the corrosion of the main body 31 and the breakage of the bellows 60 at an ultrahigh pressure can be prevented, so that the pressure of the ultrahigh pressure corrosive fluid can be detected.

Further, the body 31 is attached to a thin neck portion 33 having a different diameter.
Since the two cylinders composed of the thick body portion 34 and the thick body portion 34 are formed in a two-tiered cylindrical shape, the pressure can be detected by the relatively thin side wall 36 of the neck portion 33, so that the detection sensitivity of the pressure transducer 30 is improved. In addition to being able to improve the durability, it is possible to secure the strength against ultra-high pressure with the thick-walled body portion 34, so that the durability of the pressure transducer 30 can be improved.

Further, since the slender pipe portion 56 of the joint 50 is inserted into the bag-shaped insertion passage 35, the bellows 60 and the like can be attached to the pipe portion 56 in advance, and upside down. The encapsulant can be injected into the insertion passage 35 of the main body 31. Therefore, after injecting the encapsulant into the insertion passage 35, the pressure transducer 30 can be assembled only by screwing the joint 50 with the bellows 60 and the like attached thereto into the main body 31, and the pressure transducer 30 can be assembled. Very easy to assemble.

The present invention is not limited to the above-mentioned embodiment, but includes the following modifications. That is, the shape of the cavity formed in the main body of the pressure converter is not limited to the one having a circular cross section, and may be a flat cylinder, a hexahedron, a square tube or a sphere.

Further, the shape of the seal member is not limited to the elongated cylindrical shape like the bellows 60, but may be, for example, a flat cylindrical shape, a hexahedral shape, a rectangular tube shape, or a spherical shape. It only has to correspond to the internal shape.

Further, the deforming structure of the seal member is not limited to the bellows type like the bellows 60, but a structure utilizing elastic deformation of the material itself, for example, a simple cylindrical form can be adopted. The material of the sealing member is not limited to stainless steel, and may be, for example, another metal having corrosion resistance or a synthetic resin material, that is, a material that can sufficiently withstand ultra-high pressure and corrosive fluid. I wish I had it.

Further, the body of the pressure transducer is not limited to the body 31 having a complicated shape having the thin neck portion 33 and the thick body portion 34, and may be, for example, a simple cylinder shape, a flat drum shape, a rectangular tube shape, or a spherical shape. It may be formed on. At this time, a ring-shaped member or the like may be separately provided around the main body, and this member may reinforce the main body against internal pressure.

Further, the encapsulating agent is not limited to glycerin or mercury, but may be, for example, another oil or fat having excellent incompressibility, and a fluid having incompressibility depending on the specific structure and material of the main body side. The body may be appropriately selected.

[0038]

As described above, according to the present invention, the pressure can be accurately detected even in an ultrahigh pressure corrosive fluid by the isolation by the seal member and the volume of the encapsulant is reduced, and the durability thereof is improved. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a pressure transmitter according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of the embodiment.

[Explanation of symbols]

 30 Pressure transducer 31 Main body 39 Pressure detection chamber as cavity 60 Bellows as seal member

Claims (2)

[Claims] 1. A pressure converter for introducing a fluid into a cavity of a main body, causing a strain in the main body by the pressure of the fluid, and converting the pressure into an appropriate signal based on the strain amount, A bag-shaped seal member having a shape corresponding to the internal shape of the cavity and capable of being displaced by the pressure is built in, the fluid is introduced inside the seal member, and an encapsulant is placed outside the seal member. A pressure transducer characterized by being filled with. 2. The pressure transducer according to claim 1, wherein the seal member is a bellows which is displaceable along the longitudinal direction of the cavity.