JPH06160216A - Pressure gauge - Google Patents

Abstract

PURPOSE:To eliminate Hall effect by taking out voltage in the direction which is in the same relationship as two directions which are the direction vertical to a strain-generating body surface and are the direction of current flowing to a pattern. CONSTITUTION:Current is fed to two strain gauge pairs of strain gauges 1 and 2 and strain gauges 3 and 4 from a current source 7 and voltage between terminals 5 and 6 is output as voltage output. The zero-point fluctuation of the title gauge is generated by the Hall effect in the pattern of the title gauge and the Hall effect is mainly generated on the pattern connecting between the strain gauges 1 and 4. Voltage is taken out in a directions which is in the same relationship as two directions which are the direction vertical to a strain-generating body surface and the direction of current flowing to the pattern, thus enabling the directions to be the same even if the Hall effect is generated at the terminals 5 and 6 and the Hall effect to be canceled at a voltage measuring part 8 without affecting an error.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Recently, the use of high magnetic fields has been increasing in various fields, and the technical establishment of superconducting magnets is the most important as the technical background for making it possible. While this superconducting magnet has the advantage that it has an electric resistance of 0 and can flow an electric current, it requires cooling to a cryogenic temperature. Liquid helium and a helium refrigerator are used as the refrigerant for this cooling, and pressurized helium gas or liquid helium is used for them. The present pressure measuring device can measure the pressure of these fluids used at extremely low temperatures even in a magnetic field, and can improve the energy saving and safety of low temperature driving of the superconducting magnet.

[0002]

2. Description of the Related Art Pressure measurement at extremely low temperatures (several K) is essential for reliable operation of a cooling system, including pressure measurement of liquefied gas used as a refrigerant. But,
Since there is no reliable pressure measuring device at cryogenic temperature, in most cases, pressure is transmitted from a cryogenic temperature to a room temperature portion through a thin tube and pressure is measured with a pressure gauge at room temperature.

[0003]

Due to the presence of this thin tube, there is a time delay until the pressure measurement reaches the measuring system from the cryogenic temperature to the room temperature, and the responsiveness deteriorates. Moreover, when pressure measurement of a system that performs compression / expansion at cryogenic temperature is performed, the volume of the thin tube exerts a difficult influence on the original compression volume, making reliable measurement impossible. In addition, it can be pointed out that, in general, heat flow from the room temperature part to the cryogenic part along the narrow tube gives an excessive heat load to the refrigerator system.

All of these problems are solved if the pressure measuring device is arranged at a low temperature and the pressure can be measured in-situ. In this case, the condition imposed on the pressure measuring device is, of course, that it operates at a low temperature, and it is necessary that the pressure measuring device be small and generate little heat during measurement.

For this purpose, there are commercially available integrated pressure measuring instruments using semiconductor strain gauges, but they are not intended to be measured in a magnetic field, and the influence of the magnetic field is not considered. It cannot be used because there is a problem that the instructions will be different depending on the situation.

[0006]

[Means for Solving the Problems] As a measure for accurately using a pressure measuring instrument in a magnetic field, when a commercially available pressure measuring instrument is used in a magnetic field, zero-point fluctuations at cryogenic temperatures are generated in the magnetic field as shown in FIG. Note that the results changed with the first-order relationship. Since this phenomenon is reproduced by a plurality of pressure measuring instruments, it can be inferred that the cause is that the well-known Hall effect in semiconductors or the like occurs in the pressure measuring instrument pattern.

In particular, the pressure measuring device pattern is composed of a plurality of strain gauges formed on the surface of the strain-generating body. From the detailed examination of the pattern, the Hall effect is mainly due to the pattern portion connecting the strain gauges. It has become clear what is happening.

The present invention presents a pattern design for canceling the Hall effect appearing as an influence of a magnetic field in a pattern composed of a plurality of strain gauges. That is, even if there is a Hall effect, the voltage is taken out in the same direction as the two directions, that is, the direction perpendicular to the strain body surface and the direction of the current flowing in the pattern, with respect to the pattern portion connecting the strain gauges. Point out that the pattern to do is suitable for use in a magnetic field. By using this method, the Hall effect occurs at 5 and 6 in FIG. 3, but the directions thereof are the same, and the voltage measurement unit 8 cancels it and does not affect the error.

[0009]

FIG. 2 shows an embodiment of the invention. An electric current is applied from the current source 7 to the two strain gauge pairs of the strain gauges 1 to 2 and the strain gauges 3 to 4, and a voltage between 5 and 6 is output as a voltage output. The Hall effect due to the influence of the magnetic field can be eliminated by forming the voltage terminals 5 and 6 in a pattern as shown in FIG.

[0010]

According to the pattern of the present invention, it is possible in principle to reduce the zero point variation of about 1% in the conventional magnetic field to zero, and the reliability of pressure measurement in the magnetic field is improved. Be improved

[0011]

[Brief description of drawings]

FIG. 1 is a measurement example of zero-point fluctuation due to magnetic fields of commercially available pressure measuring instruments A, B, and C.

FIG. 2 is a usage example of a pressure measuring device using the present invention.

FIG. 3 is a pattern example of a pressure measuring device pattern in FIG.

FIG. 4 is an example in which the pattern of FIG. 3 is arranged on a flexure surface.

[Explanation of symbols]

 1 Strain gauge 2 Strain gauge 3 Strain gauge 4 Strain gauge 5 Voltage terminal 6 Voltage terminal 7 Current source 8 Voltmeter 9 Current direction 10 Direction perpendicular to strain body surface (from back to front of paper) 11 Voltage terminal mounting direction 12 Pressure application direction 13 Strain element

Claims (1)

[Claims] 1. A pressure measuring device comprising a plurality of strain gauges, wherein a pattern portion connecting between the strain gauges comprises:
A pressure measuring instrument having a pattern for extracting a voltage in a direction that has the same relationship as the direction perpendicular to the plane of the strain-generating body and the direction of the current flowing in the pattern.