JP3947389B2 - Corrosion-resistant pressure sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a corrosion-resistant pressure sensor that detects the gas pressure or liquid pressure of a chemical agent such as acid or alkali.
[0002]
[Prior art]
Some conventional pressure sensors detect the gas pressure or liquid pressure of chemical agents such as acids and alkalis.
[0003]
In this conventional pressure sensor, a fluororesin coating is applied to a metal diaphragm formed in a circular shape that receives the gas pressure or liquid pressure of the chemical agent in order to prevent the chemical agent from corroding. The coated metal diaphragm is fixed via an O-ring to the inside of the bottom of the body main body where the notch is formed.
[0004]
When the gas pressure or liquid pressure of the chemical agent is detected by the conventional pressure sensor, when the gas pressure or the liquid pressure is applied to the coated metal diaphragm through the notch, the coated metal diaphragm is bent under the pressure, The pressure change is detected by a strain detection element formed on a coated metal diaphragm.
[0005]
Some conventional pressure sensors include a fluororesin coating on a ceramic diaphragm that receives the gas pressure or liquid pressure of the chemical agent in order to prevent the chemical agent from corroding. The coated ceramic diaphragm is fixed via an O-ring to the inside of the bottom of the body main body where the notch is formed. This conventional pressure sensor detects the gas pressure or liquid pressure of a chemical agent as in the case of a coated metal diaphragm.
[0006]
Further, some conventional pressure sensors have a double diaphragm structure in which silicon oil is sealed inside using a fluororesin film diaphragm to prevent the chemical agent from eroding. When the gas pressure or liquid pressure of the chemical agent is detected by this conventional pressure sensor, when the gas pressure or liquid pressure is applied to the diaphragm of the fluororesin film, the pressure is transmitted to the enclosed silicon oil, and the silicon oil The pressure change is detected by the pressure detecting element.
[0007]
[Problems to be solved by the invention]
However, the conventional pressure sensor for detecting the gas pressure or liquid pressure of the chemical agent has the following problems.
[0008]
As described above, it is possible to prevent the chemical agent from corroding and detect the gas pressure or liquid pressure of the chemical agent by using the metal diaphragm coated with the fluororesin, but the fluororesin is coated so that the adhesive has low adhesion. There is a possibility that the adhesiveness between the layer and the metal diaphragm is low, and there is a possibility that the fluororesin layer may be peeled off. Further, since the thickness of the fluororesin layer needs to be reduced, there is a problem in durability and long-term reliability.
[0009]
Similarly, when a ceramic diaphragm coated with a fluororesin is used to prevent the chemical agent from corroding and the gas pressure or liquid pressure of the chemical agent is detected, there is also a problem in long-term reliability.
[0010]
Furthermore, the fluororesin membrane diaphragm with silicon oil sealed inside can prevent the chemical agent from corroding and detect the gas pressure or liquid pressure of the chemical agent. In order to effectively transmit pressure or liquid pressure, it is a thin plate, and it may break if gas pressure or liquid pressure is applied to the fluororesin membrane diaphragm for a long time, and there is a problem in long-term reliability, There has been a problem that silicon oil sealed in a gas or a liquid for detecting pressure leaks due to breakage of the diaphragm of the fluororesin film. In addition, the fluororesin film diaphragm may not be symmetrically distorted from the center, and has a problem in accuracy.
[0011]
The present invention has been made in view of the above, and an object of the present invention is to provide a corrosion-resistant pressure sensor that has long-term reliability and is free from the phenomenon of silicon oil leakage and capable of highly accurate pressure detection.
[0012]
[Means for Solving the Problems]
The corrosion-resistant pressure sensor of the present invention has a single-crystal sapphire diaphragm forming a pressure-sensitive resistance element, a cylindrical portion and a bottom portion, and a circular notch is formed in the bottom portion, and the single-crystal sapphire diaphragm Corrosion-resistant pressure sensor comprising a cup-shaped body main body provided on the inside and a cylindrical ceramic pedestal fixed inside the body main body, and an O-ring in the annular groove on the bottom The single crystalline sapphire diaphragm and the inner joint of the bottom are surface-treated, and the surface-treated single crystalline sapphire diaphragm and the inner joint of the bottom are combined to form the single crystalline sapphire the diaphragm is sandwiched between the inside of the joining portion of the bottom portion of the body main portion and the base is fixed with high adhesion, and the O- By being secured through the grayed, to form a double air-tight structure, it was decided to detect the pressure exerted on the monocrystalline sapphire diaphragm through the notch.
[0015]
Further, the body main body is formed of a fluororesin. Measurement is possible up to high temperature. The possibility of being eroded by the chemical agent is extremely low even outside the diaphragm portion.
[0016]
Further, the pressure sensitive resistance element is formed by laminating a silicon semiconductor epitaxially grown on the single crystalline sapphire diaphragm.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a cross-sectional view of a corrosion-resistant pressure sensor 10 according to an embodiment of the present invention.
[0019]
As shown in FIG. 1, the corrosion-resistant pressure sensor 10 has a single crystal sapphire diaphragm 17 in which a pressure-sensitive resistance element 21 (see FIG. 2) is laminated, a cylindrical portion 12, and a bottom portion 13. The body main body portion 11 is formed of a cup-shaped fluororesin in which a circular cutout portion 13A connected to the conduction hole 13B is formed and the monocrystalline sapphire diaphragm 17 is provided inside, and a screw formed in the body main body portion 11 12A and a cylindrical ceramic pedestal 16 fixed to the inside of the body main body 11 by a screw portion 16A, and pressure applied to the monocrystalline sapphire diaphragm 17 through the conduction hole 13B and the notch 13A. It is to detect.
[0020]
The monocrystalline sapphire diaphragm 17 is sandwiched between the pedestal 16 and the inside of the bottom 13 and fixed to the body main body 11. The single crystalline sapphire diaphragm 17 is not affected by the chemical environment, and the body main body 11 is notched with a conduction hole 13B in the center of the bottom 13 so that the single crystalline sapphire diaphragm 17 is directly subjected to pressure. The part 13A is formed.
[0021]
The body main body 11 is made of fluororesin so that it is not easily affected by chemicals. In addition, the fluororesin can be used in a temperature range up to 200 ° C. by selecting PTFE or PFA having high heat resistance. Can be used.
[0022]
The single-crystal sapphire diaphragm 17 and the inner side 23 of the bottom 13 are subjected to surface treatment such as polishing, and the surface-treated single-crystal sapphire diaphragm 17 and the inner side 23 of the bottom 13 are combined. The quality sapphire diaphragm 17 is fixed. For this reason, the single crystal sapphire diaphragm 17 and the inner surface 23 of the bottom 13 are fixed with high adhesion. Further, the bottom 13 can be provided with an O-ring 15 in the annular groove 13C to form a double airtight structure.
[0023]
When the gas pressure or liquid pressure of the chemical agent is detected by the corrosion-resistant pressure sensor 10, when the gas pressure or liquid pressure is applied to the single crystal sapphire diaphragm 17 through the conduction hole 13B and the cutout portion 13A as indicated by an arrow P. The single-crystal sapphire diaphragm 17 is bent inward, and the bending is detected by the pressure-sensitive resistance element 21 (see FIG. 2) laminated on the single-crystal sapphire diaphragm 17, and the pressure is detected with high accuracy. Is called.
[0024]
The corrosion-resistant pressure sensor 10 is not limited to a chemical agent, and can also detect the pressure of a gas or liquid flowing in the transport pipe or the pressure in the container.
[0025]
As described above, the corrosion-resistant pressure sensor 10 is not affected by the chemical environment even if a chemical agent is contained in the gas or liquid for detecting the pressure, and receives pressure from the single crystal sapphire diaphragm 17. There is no need to form a protective film such as a resin, and there is no problem of peeling, durability, or leakage of silicon oil, and long-term reliability and high-precision pressure detection can be performed.
[0026]
FIG. 2 is a cross-sectional view of the single crystalline sapphire diaphragm 17 in which the pressure sensitive resistance element 21 is formed.
[0027]
The pressure-sensitive resistance element 21 is formed by epitaxially growing on the single-crystal sapphire diaphragm 17 and stacking silicon semiconductors. A plurality of pressure-sensitive resistance elements 21 can be set at predetermined positions, and the single-crystal sapphire diaphragm 17 applies pressure. The resistance value is changed by changing the length and the cross-sectional area by receiving and bending, and the pressure signal can be detected by outputting a voltage signal corresponding to the pressure in the Wheatstone bridge circuit configuration.
[0028]
The pressure-sensitive resistance element 21 is protected by a coating of the protective oxide film 22 and, since a silicon semiconductor is laminated by applying a semiconductor manufacturing technique, stable characteristics up to 350 ° C. can be obtained.
[0029]
【The invention's effect】
The corrosion-resistant pressure sensor of the present invention includes a single-crystal sapphire diaphragm forming a pressure-sensitive resistance element, and a body main body provided with the single-crystal sapphire diaphragm inside a bottom portion having a circular notch, Since the pressure applied to the crystalline sapphire diaphragm through the notch is detected, the chemical agent is applied to the gas or liquid for detecting the pressure by using chemically stable single crystal sapphire for the diaphragm receiving the pressure. Even if it is contained, it is not affected by the chemical environment, and can detect pressure with high accuracy and long-term reliability.
[0030]
In addition, the single crystalline sapphire diaphragm is sandwiched between the base fixed inside the body main body and the inside of the bottom, and fixed to the body main body, so that the single crystalline sapphire diaphragm is securely attached. Can be fixed to.
[0031]
In addition, the single crystal sapphire diaphragm and the inside of the bottom are surface-treated, the surface-treated surfaces are combined, and the single crystal sapphire diaphragm is fixed to the bottom. Can be fixed with high adhesion.
[0032]
Further, since the body main body portion is formed of a fluororesin, it can be measured up to a high temperature state, and the possibility of being eroded by a chemical agent can be extremely low.
[0033]
Furthermore, since the pressure-sensitive resistor element is formed by stacking a silicon semiconductor epitaxially grown on the single-crystal sapphire diaphragm, the single-crystal sapphire diaphragm and the pressure-sensitive resistor element are atomically bonded. . Therefore, when the displacement due to strain uniformly deforms the notch and deforms symmetrically with respect to the center of the notch circle, the resistance of the pressure-sensitive resistor element of the single-crystal sapphire diaphragm supported by the joint The ratio is constant.
[0034]
Therefore, since the distortion with respect to the pressure is linear and the output voltage of the Wheatstone bridge that is output accompanying it is also a linear output, an excellent pressure-output voltage characteristic can be obtained. In addition, a stable pressure-output voltage characteristic can be obtained up to a high temperature state.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a corrosion-resistant pressure sensor according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a single crystalline sapphire diaphragm in which a pressure sensitive resistance element is formed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Corrosion-resistant pressure sensor 11 Body main body part 12 Cylindrical part 13 Bottom part 13A Notch part 13B Conduction hole 13C Annular groove 14 Joint part 15 O-ring 16 Base 17 Single crystalline sapphire diaphragm 21 Pressure sensitive resistance element 22 Protective oxide film

Claims (3)

A single crystalline sapphire diaphragm forming a pressure sensitive resistor element;
A cylindrical body and a bottom, wherein the bottom is formed with a circular cutout, and the single-crystal sapphire diaphragm is provided inside, a cup-shaped body body,
A cylindrical ceramic pedestal fixed inside the body body,
And in the corrosion-resistant pressure sensor in which an O-ring is provided in the annular groove at the bottom,
The single crystal sapphire diaphragm and the joint inside the bottom are surface-treated,
The surface-treated single crystalline sapphire diaphragm and the inner joint of the bottom are combined,
The single-crystal sapphire diaphragm is sandwiched between the base and the joint portion inside the bottom portion of the body main body, and is fixed with high adhesion , and is fixed through the O-ring. Forming a heavy airtight structure,
A corrosion-resistant pressure sensor that detects a pressure applied to the single crystalline sapphire diaphragm through the notch.   The corrosion-resistant pressure sensor according to claim 1, wherein the body main body is formed of a fluororesin.   3. The corrosion-resistant pressure sensor according to claim 1, wherein the pressure-sensitive resistance element is formed by laminating a silicon semiconductor epitaxially grown on the single crystal sapphire diaphragm. 4.

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