JPS6086436A - Waveguide type temperature distribution meter - Google Patents

Abstract

PURPOSE:To measure the temperatures of plural positions only by one waveguide by measuring the temperatures of plural magnet setting parts in accordance with the level of a magnetostriction signal. CONSTITUTION:When pulse current is applied to a core in the magnetostriction waveguide 1, magnetostriction is generated by Wiedemann effect of magnets M1-Mn to their magnetic fields, transmitted through the waveguide 1 and reaches to a signal processing circuit part 2. The magnetostriction signal 27 from the waveguide 1 is inputted to a synchronization detecting part 26 in a processing circuit 2 and a storage part 20. A detecting part 26 detects signals S1, S2 and outputs the signals at the time Ts. The storage part 20 stores the magnetostriction signal only for the period Ts. After the completion of the storage, the peaks of the magnetostriction signals S1-Sn are detected by an arithmetic circuit 21 to find out the temperatures. The found temperatures are stored in a storage device 23 and the waveforms are smoothed to find out the temperature distribution along the waveguide 1. Thus, the temperatures of plural positions can be measured only by one waveguide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a waveguide that utilizes the magnetostrictive phenomenon, and particularly to means for measuring temperature using a magnetostrictive signal.

[Background of the invention]

When a current is passed through a cylindrical ferromagnetic material, torsional strain occurs in the area where a parallel magnetic field exists, a phenomenon known as the Wiebmann effect. A method has been proposed that utilizes this phenomenon to measure the position of an object to which a magnet is attached, but it does not have a configuration or purpose for measuring the temperature of the magnet installation part.

There is also a method of measuring the temperature of a waveguide material by utilizing the phenomenon that the propagation speed of ultrasonic waves changes when the temperature of an object changes. In this method, a plurality of notches are provided in a waveguide material to reflect ultrasonic waves, and the average temperature between the notches is calculated from the propagation time of the ultrasonic waves reflected from each notch. Since the sound velocity change in the waveguide material is as small as about 10-'/l:', it is not possible to expect a significant improvement in measurement accuracy.

[Object of the invention].

An object of the present invention is to provide a device that simultaneously measures temperatures at multiple locations using a single waveguide.

[Summary of the invention]

The present invention actively utilizes the fact that the magnetostrictive effect in a magnetostrictive waveguide changes with temperature.

As the temperature increases, the magnetostrictive effect becomes smaller, and when the temperature rises above one Curie temperature, the magnetostriction becomes zero, so it can be used to measure temperatures below one Curie temperature. In this case, if the strength of the magnetic field changes with temperature, the magnetostrictive effect also changes, so it is desirable that the Curie temperature of the magnet installed outside the waveguide be as high as possible.

Additionally, the relationship between temperature and magnetostriction effect is generally nonlinear;
The accuracy is improved by correction.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows the configuration of the waveguide type temperature distribution meter of the present invention, in which 1 is a magnetostrictive waveguide having a core wire inside, 2 is a means for applying a pulse current to the core wire, and a means for detecting a magnetostrictive signal. Circuit section that calculates temperature distribution.

M1* Mx + M3 *...M a -1
1M 11 is a magnet installed outside the waveguide.

When a pulse current is applied to the core wire inside the magnetostrictive waveguide, the magnet M
Magnetostriction is generated due to the Wiebmann effect with the magnetic field of l, r..., which propagates through the waveguide to the signal processing circuit section 2.
reach. The magnetostrictive signal detected by the signal processing circuit is the second
As shown in the figure, signals Ss, 82...Sn corresponding to the magnets Ms, k...M are obtained.

When the pulse current to the core wire is repeated every time T8, a magnetostrictive signal of 8'1*8'2...S'a is also generated.

As the temperature of the magnetostrictive waveguide increases, the magnitude of magnetostriction changes as shown in FIG. Figure 3 shows the relationship between temperature and magnetostriction of nickel, for example, but it is not possible to experimentally determine the temperature and magnetostriction of iron, cobalt, and their alloys in addition to nickel. can. Since the magnitude of magnetostriction becomes 0 above the Curie temperature, the method shown in FIG. 3 can be used at temperatures lower than the Curie temperature.

FIG. 4 is a block diagram of the signal processing circuit section 2. As shown in FIG.

The magnetostrictive signal 27 from the magnetostrictive waveguide 1 is input to the synchronization detection section 26 and the storage section 20. The synchronization detection section receives the signal S1 in Fig. 2.
．． 81' is detected and a signal at time T is output to 28.

The storage unit 20 stores the magnetostrictive signal for a time T1. When the storage is completed, the peak of the magnetostrictive signal Ss, 8x...S is detected at 21, and the temperature is measured at 22. The function No. 22 is set as the inverse function shown in FIG. Magnetostrictive signal SX, 8
m... After storing the twisted temperature at 23, the temperature distribution along the magnetostrictive waveguide is determined by smoothing the waveform. The temperature distribution is output to the display section 25 or to an external circuit via 30. This operation is performed at time Ts in Figure 2.
It is repeated every time. Therefore, it is natural that TIl is set longer than the processing time in FIG. 4.

Now, if the temperature around the magnets M2 and M3 rises, the signals of St and Sg become smaller as shown in FIG. 2B.

Since the magnitude of the magnetostrictive signal is approximately proportional to the product of the magnetic field from the magnet and the pulse current of the core wire,
If the magnetic force of M becomes weaker due to a rise in temperature, this will cause an error. Therefore, the higher the Curie temperature of the magnet is, the more desirable it is, and in order to use it as a temperature distribution meter, the Curie temperature of the waveguide must be lower than the Curie temperature of the magnet.

Furthermore, the magnetostrictive signal is obtained by converting the energy of the pulsed current in the core wire into energy that distorts the waveguide, and it can be considered that the conversion efficiency changes depending on the temperature. Therefore 1, quantities related to magnetostrictive energy, e.g. amplitude,
Temperature can be calculated by detecting duration, root mean square, etc.

Although the present invention has been described above with reference to specific embodiments thereof, it is understood that the present invention is not limited to the described embodiments and that various applications are possible within the scope of the present invention. It is clear to the trader.

For example, the Curie temperature can be varied by changing the material of the magnetostrictive waveguide for each location, and the temperature measurement range can be expanded by utilizing the high sensitivity range with the characteristics shown in FIG. Furthermore, there is a method of shortening the interval between the magnets M1, M2, . . . in FIG. 1 to make the waveforms 8*, St, . . . group continuous, thereby improving the measurement accuracy of the temperature distribution. Furthermore, it is a matter of course that the calculation shown in FIG. 1 can be realized by a microcomputer.

〔Effect of the invention〕

According to the present invention, there are the following effects.

(1) Temperatures at multiple locations can be measured simultaneously with a single waveguide.

(2) Due to the effect of (11) above, the number of wires for temperature measurement can be reduced. For example, when measuring three-dimensional temperature distribution in a large tank, the number of wires is lower than that of the conventional thermocouple method. In comparison, it becomes 1710 or less.

(3) The magnetostriction generating part can be made entirely of metal, and can be used as a high temperature sensor.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of the waveguide type temperature distribution meter of the present invention, Figure 2
The figure is a magnetostriction signal diagram for explaining the present invention in detail, FIG. 3 is a relationship diagram between temperature and the magnitude of magnetostriction, and FIG. 4 is a block diagram for explaining the signal processing method of the present invention. 1... Magnetostrictive waveguide, 2... Signal processing section %M1~MI
l...Floor 1 Figure ■ 12 Figure St S2 S3'4 5n Sl 52 5354-
STI rate 3 figure scolding 4- figure

Claims (1)

[Claims] 1. A means for applying a pulse current to a ferromagnetic waveguide, a core wire provided inside the waveguide, a plurality of magnets provided outside the waveguide, and a plurality of core wires; In a magnetostrictive waveguide having a means for detecting magnetostriction generated by the magnetic field of the magnet and the pulse current of the core wire, a waveguide temperature waveguide is characterized in that the temperature of a plurality of magnet installation parts is measured based on the level of the magnetostrictive signal. Distribution meter. 2. A waveguide type temperature distribution meter according to claim 1, characterized in that the Curie temperature of the waveguide is lower than the Curie temperature of a magnet provided outside the waveguide. 3. A waveguide temperature distribution meter according to claim 1, wherein the level of the magnetostrictive signal is an amount related to magnetostrictive energy.