JP3175319U - Thermal conductivity type vacuum pressure gauge - Google Patents

Abstract

[PROBLEMS] A heat conduction type that is strong against vibration and impact, can measure pressure range from vacuum to atmospheric pressure, has little influence of ambient temperature, shields electrical noise, and can measure dynamic pressure in narrow space. A vacuum pressure gauge is provided.
A temperature-controlled heat sink 2 is provided to surround a pressure detection filament so as to maintain a constant temperature with an opening 3 for circulation of a measurement gas and a heater 4, and pure platinum is used as the pressure detection filament. Using (Pt), the pressure detection filament is miniaturized as a fine winding structure, a metal mesh 6 is attached to the opening, oil mist and dust are prevented from being attached, and electrical noise is shielded.
[Selection] Figure 1

Description

The present invention relates to a heat conduction type vacuum pressure gauge used for pressure measurement from a vacuum region to a pressurization region near atmospheric pressure by utilizing heat conduction of gas.

A conventional heat conduction type vacuum gauge represented by the Pirani vacuum gauge heats a metal filament stretched in a vacuum, detects a temperature change corresponding to the amount of heat taken away from the hot filament as a change in electrical resistance, Furthermore, the pressure of the gas is measured by converting the change in electric resistance into a pressure value. A sensor of a general Pirani vacuum gauge is composed of a cylindrical tube in which an alloy wire of tungsten (W) or platinum (Pt) is stretched between electrodes as a filament and an opening for measuring gas flow is provided on one side. ing.

A thin filament with a wire diameter of several tens of μm and a wire length of several tens of millimeters is used for the filament of a commercially available sensor, but in order to prevent the influence of the vibration of the filament due to gas flow in the viscous flow region on the measurement, It is stretched under tension. For this reason, it may be easily damaged by vibrations or shocks received from the device to which the sensor is attached, and needs to be frequently replaced. In addition, since the wire length is long, it is affected by gas convection in the intermediate flow and viscous flow regions, so that not only the measurement is affected by the mounting direction but also the upper limit of the measurement pressure.
Furthermore, since heat radiation from the filament is affected by the temperature of the surrounding body cylinder, temperature correction is required for accurate pressure measurement, but due to the size of the commercially available Pirani vacuum gauge sensor, Since it can only be mounted, accurate sensor temperature measurement and temperature compensation are not performed. In production processes, it is essential to measure the dynamic pressure in the narrow space required in the vacuum system. However, it is almost impossible with current measurement technologies such as sensor size and response speed constraints. It is only based on calculation knowledge and experience based on, and accurate pressure measurement is not possible.

Japanese Patent No. 3188852 Japanese Patent Laid-Open No. 5-281073 JP-A-7-120339

Heat conduction type vacuum pressure gauge that is strong against vibration and shock, can measure pressure range from vacuum to atmospheric pressure, has little influence of ambient temperature, shields electrical noise, and can measure dynamic pressure in narrow space The purpose is to provide.

A temperature-controlled heat sink is provided to maintain a constant temperature with an opening for circulating the measurement gas and a heater to surround the pressure detection filament, and accurate temperature compensation and measurement pressure range are expanded. A heat conduction type vacuum pressure gauge.

A heat conduction type vacuum pressure gauge using pure platinum (Pt) as a pressure detection filament.

A heat-conducting vacuum pressure gauge characterized in that the pressure sensing filament is miniaturized with a small winding structure.

A heat-conducting vacuum pressure gauge with a metal mesh attached to the opening to prevent oil mist and dust from adhering and to shield electrical noise generated from plasma used in processing.

According to the heat conduction type vacuum pressure gauge of the present invention, it is possible to measure a wide area from 10 ⁻² Pa to 2 atm or more with one type of vacuum pressure gauge, and stable measurement by a highly accurate temperature compensation function. Is possible. Further, by reducing the size of the filament, the replacement of the heat conduction type vacuum pressure gauge due to the breakage of the filament can be greatly reduced, and dynamic pressure measurement in a necessary narrow space such as in the vacuum apparatus container can be performed. In addition, the metal mesh prevents contamination of the heat-conducting vacuum pressure gauge, shields electrical noise, etc., and even if fine foreign matter adheres, the filament is cleaned by regular heating of the filament and stable. Can measure.

It is a figure which shows the whole structure of a heat conductive type vacuum pressure gauge. (A) The Example in case the shape of a heat sink is a rectangular parallelepiped is shown. (B) An example in which the shape of the heat sink is cylindrical is shown. (C) An example in which the shape of the heat sink is spherical is shown. The example of an internal structure of the heat conductive type vacuum pressure gauge which removed the heat sink is shown. The measurement control circuit diagram of a heat conduction type vacuum pressure gauge is shown. (A) A pressure measurement measurement circuit is shown. (B) A heat control temperature control circuit is shown.

A heat-conducting vacuum pressure gauge is provided with a heat-sink precisely controlled by a heater around the pressure-sensing filament and with accurate temperature compensation and expanded measurement pressure range.

FIG. 1 shows the overall structure of the heat conduction type vacuum pressure gauge of the present invention.
The heat conduction type vacuum pressure gauge 1 includes a pressure detection filament 9, a heat sink 2, and a filament fixing base 8. The heat sink 2 is made of metal, has a heater 4, has a structure surrounding the filament to protect the filament, and has an opening 3 for circulating the measurement gas.
A metal mesh 6 is attached to the opening so that it can be replaced according to the measurement conditions. The heat conduction type vacuum pressure gauge may be changed according to the use and accuracy, such as (a) rectangular parallelepiped, (b) cylindrical shape, (c) spherical shape, etc. in FIG. In the case of a spherical shape, since the distance between the pressure detection filament 9 and the heat sink 2 is substantially uniform, the pressure detection filament 9 is not affected by the temperature of the heat sink, and high-precision measurement can be expected.

FIG. 2 shows the internal structure of the heat conduction type vacuum pressure gauge with the heat sink removed. The heat conduction type vacuum pressure gauge has a structure in which the pressure detection filament 9 is stretched between the filament terminals 7 supported by the filament fixing base 8 in a minute winding shape. The filament terminal 7 is connected to the filament terminal 7 through the filament fixing base 8 and is temperature-controlled so as to reach a constant temperature by the bridge circuit of FIG. 3A and measures the current and voltage flowing therethrough. To measure the corresponding pressure.

The pressure detection filament 9 is formed by winding pure platinum (Pt) having a resistance temperature coefficient (TCR: 3500 ppm or more) larger than that of a general filament material. In the embodiment, the pressure detection filament 9 has a wire diameter of 15 μm and a winding number of 7 times. The filament is adopted. You may change the dimension and shape of a filament according to measurement conditions.

By reducing the filament diameter and winding it, the filament size, volume and weight are reduced, which not only increases the mechanical strength but also reduces the heat capacity, thereby increasing the response speed and dynamic pressure. Changes can be measured. Further, the sensitivity is increased by using a pure platinum (Pt) material having a high temperature coefficient of resistance (TCR) as a filament material. In addition, by making the filament microminiaturized, it is less susceptible to convection due to the mounting direction of the heat-conducting vacuum pressure gauge, enabling stable measurement in the pressure range above atmospheric pressure and expanding the measurement pressure range. it can. By miniaturizing the filament, the size of the heat-conducting vacuum pressure gauge can be reduced. As a result, it can be installed in any narrow space such as a vacuum application processing device, which is necessary for production processes. Dynamic pressure measurement at the location is possible.

FIG. 3 shows a measurement control circuit of a heat conduction type vacuum pressure gauge. 3A shows a pressure measurement control circuit, and FIG. 3B shows a heat sink temperature control circuit.
FIG. 3A is a circuit for measuring the temperature change of the pressure detection filament 9 as a change in resistance value. The measurement method is a constant temperature control method in which the bridge voltage is adjusted so that the temperature of the pressure detection filament 9 is constant. Depending on the pressure of the gas, the amount of heat is deprived from the pressure detection filament 9 and the temperature changes. However, control that is always constant is automatically performed, and the control value is converted into a pressure value.
FIG. 3B is a constant temperature control system circuit that adjusts the bridge voltage so that the temperature of the heater 4 becomes constant. Depending on the pressure of the gas, the amount of heat is deprived from the heater 4 and the temperature changes, but control that is always constant is automatically performed. Therefore, the entire surface of the heat sink 2 is maintained at a constant temperature by the heater 4 integrated with a thin film temperature sensor such as nickel (Ni) regardless of the gas pressure. In addition, since the heat sink adjacent to the pressure detection filament is controlled at a constant temperature, accurate temperature compensation is realized without being affected by changes in the ambient temperature, and highly accurate and stable pressure control is possible.

A metal mesh 6 having a removable size of 100 mesh or more is attached to the opening 3 of the heat sink 2 to prevent adhesion of oil mist and dust generated in an exhaust pump, a piping system or a vacuum device container, and used for processing. Electric noise generated from plasma or the like can be shielded. The shape and size of the metal mesh 6 may be changed according to the application and purpose. The metal mesh may be covered so as to cover not only the opening but also the entire heat sink in consideration of an electromagnetic shield or the like.

Provided is a heat conduction type vacuum pressure gauge excellent in environmental resistance capable of measuring a pressure in a wide region from 10 ⁻² Pa to 2 atm and capable of dynamic pressure measurement in a narrow space.

DESCRIPTION OF SYMBOLS 1 Heat conduction type vacuum pressure gauge 2 Heat sink 3 Opening 4 Heater 5 Heater terminal 6 Metal mesh 7 Filament terminal 8 Filament fixed base 9 Pressure detection filament

Claims (4)

A temperature-controlled heat sink is provided to maintain a constant temperature with an opening for circulating the measurement gas and a heater to surround the pressure detection filament, and accurate temperature compensation and measurement pressure range are expanded. A heat conduction type vacuum pressure gauge. 2. The heat conduction type vacuum pressure gauge according to claim 1, wherein pure platinum (Pt) is used as the pressure detection filament. 3. The heat conduction type vacuum pressure gauge according to claim 1, wherein the pressure detection filament has a minute winding structure. 2. The heat conduction type vacuum pressure gauge according to claim 1, wherein a metal mesh is attached to the opening to prevent oil mist and dust from adhering and to shield electric noise generated from plasma used for processing.

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