Capacitive pressure sensor capable of reducing surface pollution of pressure sensing diaphragm

Abstract

The invention relates to a capacitive pressure sensor capable of reducing surface pollution of a pressure sensing diaphragm. The capacitive pressure sensor comprises a spiral cylinder; the spiral column body is detachably mounted in the air inlet of the measuring cavity; and a spiral air inlet channel is formed between the air inlet of the measuring cavity and the spiral cylinder. According to the capacitive pressure sensor, the spiral column body is arranged in the gas inlet of the measuring cavity, and measured gas enters the measuring cavity body after rotating along the spiral column body and then is in contact with the pressure sensing diaphragm, so that the measured gas firstly passes through the spiral column body and is in contact with the surface of the spiral column body, and particles are attached to and condensed on the surface of the spiral column body; therefore, the defect that a large amount of pollutants are condensed on the surface of the pressure sensing diaphragm when a traditional capacitive pressure sensor measures condensable volatile gas is overcome, the measuring and metering characteristics of the capacitive pressure sensor are remarkably improved, and the service life is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum measurement, and in particular relates to a capacitive pressure sensor capable of reducing surface contamination of a pressure-sensitive diaphragm. Background Art

[0002] Capacitance film vacuum gauge is an instrument that uses the displacement of elastic diaphragm under the action of pressure difference to cause the change of distance between electrode and diaphragm, resulting in change of capacitance. It can measure vacuum degree by measuring the change of capacitance. It has many advantages such as high measurement accuracy, good linearity, good output repeatability and long-term stability, ability to measure the total pressure of gas and steam, and measurement results are independent of gas composition and type. It is widely used in vacuum measurement, microelectronics industry, surface treatment, plasma measurement, aerospace, high energy physics, controlled thermonuclear fusion and other fields.

[0003] The capacitive pressure sensor is the physical unit of the capacitive film vacuum gauge. The pressure sensing unit is the core component of the capacitive pressure sensor to sense the pressure of the measured gas. The pressure sensing unit needs to be equipped with relevant measurement circuits and circuit connectors to transmit electrical signals to the control unit. Figure 1 and Figure 2 As shown, traditional capacitive pressure sensors generally do not have an anti-pollution structure for the pressure-sensitive diaphragm. The measured gas directly reaches the surface of the pressure-sensitive diaphragm through the intake pipe and has no anti-pollution function. After the surface of the pressure-sensitive diaphragm is contaminated for a long time, it will inevitably cause changes in its mechanical properties and elasticity, resulting in changes in the measurement characteristics of the capacitive pressure sensor and reducing its service life. Summary of the invention

[0004] The present invention provides a capacitive pressure sensor for reducing surface contamination of a pressure-sensitive diaphragm. The capacitive pressure sensor places a spiral cylinder in the air inlet of a measuring cavity, so that the measured gas rotates through the spiral cylinder structure into the measuring cavity and then contacts the pressure-sensitive diaphragm, so that condensable volatiles and particles in the measured gas adhere to and condense on the surface of the spiral cylinder, thereby reducing the condensable volatiles and particles in the measured gas from adhering to and condensing on the surface of the pressure-sensitive diaphragm.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A capacitive pressure sensor for reducing surface contamination of a pressure-sensitive diaphragm, the capacitive pressure sensor comprising a measuring chamber and a measuring chamber air inlet communicating with the measuring chamber, and also comprising a spiral column;

[0007] The spiral cylinder is detachably installed in the air inlet of the measuring cavity; a spiral air inlet channel is formed between the air inlet of the measuring cavity and the spiral cylinder.

[0008] Furthermore, the spiral cylinder is made of metal material.

[0009] Furthermore, the metal material is aluminum alloy or stainless steel.

[0010] Furthermore, the spiral cylinder is made of non-metallic material.

[0011] Furthermore, the non-metallic material is ceramic or nylon.

[0012] Furthermore, the spiral cylinder is installed in the air inlet of the measuring cavity by means of screws.

[0013] Furthermore, it also includes a bottom plate, a diaphragm frame, a pressure-sensitive diaphragm, a measuring cavity cover plate, a reference cavity, an extraction electrode, and a fixed electrode;

[0014] The measuring cavity cover plate and the diaphragm frame are both hollow cylinders with cylindrical cavities; the bottom plate, the diaphragm frame, the pressure-sensitive diaphragm and the measuring cavity cover plate are coaxially fixedly connected in sequence; the pressure-sensitive diaphragm separates the measuring cavity cover plate from the cavity of the diaphragm frame, forms the reference cavity between the pressure-sensitive diaphragm and the bottom plate, and forms the measuring cavity between the pressure-sensitive diaphragm and the measuring cavity cover plate; the fixed electrode is fixedly installed in the reference cavity; one end of the lead-out electrode is electrically connected to the fixed electrode, and the other end extends out of the bottom plate.

[0015] Furthermore, the pressure-sensitive diaphragm is welded and connected between the measuring cavity cover plate and the diaphragm frame.

[0016] Furthermore, it also includes a sleeve;

[0017] The sleeve is abutted between the bottom plate and the fixed electrode.

[0018] Furthermore, an air intake pipe is included;

[0019] The measuring cavity cover plate is provided with a central through hole;

[0020] The air inlet pipe is coaxially connected to the measuring cavity cover plate, one end of which is inserted into the central through hole and the other end of which extends out of the measuring cavity cover plate;

[0021] The air inlet of the measuring cavity is formed in the air inlet pipe.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The capacitive pressure sensor of the present invention includes a spiral cylinder detachably installed in the air inlet of the measuring chamber, and a spiral air inlet channel is formed between the air inlet of the measuring chamber and the spiral cylinder, so that the measured gas rotates along the spiral air inlet channel into the measuring chamber and then contacts the pressure-sensitive diaphragm. The measured gas first passes through the spiral cylinder and then acts on the pressure-sensitive diaphragm. When passing through the spiral air inlet channel, the gas first contacts the surface of the spiral air inlet channel and particles adhere and condense on the surface of the spiral cylinder. Therefore, the disadvantage of the traditional capacitive pressure sensor that a large amount of pollutants condense on the surface of the pressure-sensitive diaphragm when measuring gases with condensable volatiles is reduced, the measurement and metering characteristics of the capacitive pressure sensor are significantly improved, and the service life is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of a capacitive pressure sensor in the prior art;

[0025] Figure 2 for Figure 1 A cross-sectional view of a medium capacitance pressure sensor;

[0026] Figure 3 It is a schematic diagram of the three-dimensional structure of the capacitive pressure sensor of the present invention;

[0027] Figure 4 for Figure 3 Cross-sectional view of a medium capacitance pressure sensor.

[0028] Reference numerals:

[0029] 1-base plate, 2-diaphragm frame, 3-pressure-sensitive diaphragm, 4-measuring chamber cover, 5-reference chamber, 6-measuring chamber, 7-lead-out electrode, 8-fixed electrode, 9-measuring chamber air inlet, 10-spiral cylinder, 11-air inlet pipe, 12-sleeve. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The embodiment of the present invention provides a capacitive pressure sensor that reduces surface contamination of a pressure-sensitive diaphragm, such as Figure 3 and Figure 4 As shown, the capacitive pressure sensor includes a base plate 1, a diaphragm frame 2, a pressure-sensitive diaphragm 3, a measuring chamber cover plate 4, a reference chamber 5, a measuring chamber 6, an extraction electrode 7, a fixed electrode 8 and a spiral cylinder 10; wherein:

[0032] The measuring cavity cover plate 4 and the diaphragm frame 2 are both hollow cylinders with cylindrical cavities; Figure 4 As shown, from top to bottom, the bottom plate 1, the diaphragm frame 2, the pressure-sensitive diaphragm 3 and the measuring cavity cover 4 are coaxially fixedly connected in sequence; the bottom plate 1, the diaphragm frame 2 and the measuring cavity cover surround to form a cavity; the pressure-sensitive diaphragm 3 separates the measuring cavity cover 4 from the cavity of the diaphragm frame 2, and the pressure-sensitive diaphragm 3 separates the cavity surrounded by the bottom plate 1, the diaphragm frame 2 and the measuring cavity cover into a reference chamber 5 and a measuring chamber 6; a reference chamber 5 is formed between the pressure-sensitive diaphragm 3 and the bottom plate 1, and a measuring chamber 6 is formed between the pressure-sensitive diaphragm 3 and the measuring cavity cover 4; the pressure-sensitive diaphragm 3 can be connected between the measuring cavity cover 4 and the diaphragm frame 2 by welding; the fixed electrode 8 is fixedly installed in the reference chamber 5, and the fixed electrode 8 is arranged parallel to the pressure-sensitive diaphragm 3; one end of the lead-out electrode 7 is electrically connected to the fixed electrode 8, and the other end extends out of the bottom plate 1.

[0033] like Figure 3 and Figure 4 As shown, the measuring chamber 6 is provided with a connected measuring chamber air inlet 9, which is used to introduce the measured gas through the measuring chamber air inlet 9; the spiral cylinder 10 is detachably installed in the measuring chamber air inlet 9, so that the spiral cylinder 10 can be disassembled and replaced when a lot of pollutants adhere to it after being used for a period of time; a spiral air inlet channel is formed between the measuring chamber air inlet 9 and the spiral cylinder 10, so that the measured gas forms a spiral airflow before entering the measuring chamber 6, increasing the flow time of the measured gas in the measuring chamber air inlet 9 and the contact area with the spiral cylinder 10, so that the pollutants in the measured gas can be adsorbed on the surface of the spiral cylinder 10 as much as possible. The spiral cylinder 10 can be fixedly installed in the measuring chamber air inlet 9 by screws, and the screws are used to facilitate the disassembly of the spiral cylinder 10. At the same time, the spiral column 10 can also be installed in the measuring chamber air inlet 9 through a clamp, such as a clamp or a retaining ring is installed on the upper and lower sides of the measuring chamber air inlet 9, so that the spiral column 10 is limited between the two clamps or retaining rings, and the spiral column 10 can be disassembled or replaced by removing the clamp or retaining ring.

[0034] The spiral column 10 is made of metal material or non-metal material; the metal material is aluminum alloy (2A12, 6061, etc.) or stainless steel (304, 316, etc.); the non-metal material can be ceramic or nylon.

[0035] The capacitive pressure sensor further comprises a sleeve 12 and an air inlet pipe 11; the sleeve 12 is abutted between the bottom plate 1 and the fixed electrode 8, and a limiting step is provided on the inner surface of the diaphragm frame 2, the bottom surface of the fixed electrode 8 is supported on the limiting step, and the top surface is limited by the sleeve 12 abutting against the bottom surface of the bottom plate 1, so as to realize the positioning and installation of the fixed electrode 8. The measuring cavity cover plate 4 is provided with a central through hole; the air inlet pipe 11 is coaxially connected with the measuring cavity cover plate 4, one end of which is inserted into the central through hole, and the other end extends out of the measuring cavity cover plate 4; the air inlet pipe 11 is sealed with the inner wall of the central through hole of the measuring cavity cover plate 4; the measuring cavity air inlet 9 is formed in the air inlet pipe 11, and the spiral cylinder 10 is detachably installed in the air inlet pipe 11.

[0036] The above-mentioned capacitive pressure sensor includes a spiral cylinder 10 detachably installed in the air inlet 9 of the measuring chamber, and a spiral air inlet channel is formed between the air inlet 9 of the measuring chamber and the spiral cylinder 10, so that the measured gas rotates along the spiral air inlet channel into the measuring chamber 6 and then contacts the pressure-sensitive diaphragm 3. The spiral cylinder 10 makes the measured gas first pass through the spiral cylinder and then act on the pressure-sensitive diaphragm 3. When passing through the spiral air inlet channel, the gas first contacts the surface of the spiral air inlet channel and particles adhere and condense on the surface of the spiral cylinder 10. Therefore, the disadvantage of the traditional capacitive pressure sensor that a large amount of pollutants condense on the surface of the pressure-sensitive diaphragm 3 when measuring gases with condensable volatiles is reduced, the measurement and metering characteristics of the capacitive pressure sensor are significantly improved, and the service life is extended.

[0037] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A capacitive pressure sensor for reducing surface contamination of a pressure-sensitive diaphragm, comprising a measuring chamber and a measuring chamber air inlet connected to the measuring chamber; characterized in that: Also included is a spiral column; The spiral cylinder is detachably installed in the air inlet of the measuring cavity; a spiral air inlet channel is formed between the air inlet of the measuring cavity and the spiral cylinder.

2. The capacitive pressure sensor according to claim 1, characterized in that: The spiral column is made of metal material.

3. The capacitive pressure sensor according to claim 2, characterized in that: The metal material is aluminum alloy or stainless steel.

4. The capacitive pressure sensor according to claim 1, characterized in that: The spiral column is made of non-metallic material.

5. The capacitive pressure sensor according to claim 4, characterized in that: The non-metallic material is ceramic or nylon.

6. The capacitive pressure sensor according to claim 1, characterized in that: The spiral cylinder is installed in the air inlet of the measuring cavity by means of screws.

7. The capacitive pressure sensor according to claim 1, characterized in that: It also includes a base plate, a diaphragm frame, a pressure-sensitive diaphragm, a measuring cavity cover plate, a reference cavity, an extraction electrode, and a fixed electrode; The measuring cavity cover plate and the diaphragm frame are both hollow cylinders with cylindrical cavities; the bottom plate, the diaphragm frame, the pressure-sensitive diaphragm and the measuring cavity cover plate are coaxially fixedly connected in sequence; the pressure-sensitive diaphragm separates the measuring cavity cover plate from the cavity of the diaphragm frame, forms the reference cavity between the pressure-sensitive diaphragm and the bottom plate, and forms the measuring cavity between the pressure-sensitive diaphragm and the measuring cavity cover plate; the fixed electrode is fixedly installed in the reference cavity; one end of the lead-out electrode is electrically connected to the fixed electrode, and the other end extends out of the bottom plate.

8. The capacitive pressure sensor according to claim 7, characterized in that: The pressure-sensitive diaphragm is welded and connected between the measuring cavity cover plate and the diaphragm frame.

9. The capacitive pressure sensor according to claim 7, characterized in that: Also includes a sleeve; The sleeve is abutted between the bottom plate and the fixed electrode.

10. The capacitive pressure sensor according to claim 7, characterized in that: Also includes the intake duct; The measuring cavity cover plate is provided with a central through hole; The air inlet pipe is coaxially connected to the measuring cavity cover plate, one end of which is inserted into the central through hole and the other end of which extends out of the measuring cavity cover plate; The air inlet of the measuring cavity is formed in the air inlet pipe.

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