JPS631528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure converter, and more particularly to a pressure converter having a pressure detection function and a temperature detection function.

A pressure transducer using a small core is a magnetic pressure transducer that utilizes the magnetostrictive effect, and can be embedded in materials such as thermoset plastics and prestressed concrete.
It is known that it is possible to measure the internal stresses that occur in such materials as they solidify. These internal stress measurements are made without significant side effects due to the presence of a core embedded in the material. Additionally, additional internal stresses in these materials due to irradiation, expansion and contraction of the materials, etc. can readily be measured using these cores.

FIG. 1 is an example of a known magnetic pressure transducer,
Excitation winding 11 sown around a core 10 made of magnetostrictive material
A core 10 excited by a signal generator 2 connected via (primary coil) and an output winding 12
1 shows a schematic diagram of a circuit diagram illustrating how a microtransducer with (secondary coil) is used for stress measurements; FIG. Excitation winding 11 (primary coil) and output winding 12
Although the number of turns of the secondary coil can be selected as appropriate, for example, a larger output can be obtained by increasing the number of turns of the secondary coil. In certain applications,
This has the advantage of eliminating noise associated with the output signal.In a typical application, the pressure transducer 1 is embedded within the epoxy resin and the internal stresses generated within the epoxy resin during curing are transferred to the core 10. This is observed by monitoring the output signal induced in the winding 12 (secondary coil). The output signal is fed to an amplifier 3 and a conventional electrometer 4
Display in .

Such an application example is used to analyze the internal stress caused by curing shrinkage in the process of changing from a liquid state to a solid state and in the process of cooling from a high temperature to room temperature during resin casting of a cast insulator.

On the other hand, these cast-molded insulators often have a structure in which coils, conductors, iron cores, etc. are embedded and integrated with resin. For this reason, temperature distribution occurs within the insulating layer as the equipment starts and stops, and thermal stress is generated due to the difference in coefficient of thermal expansion and modulus of elasticity between the resin and the embedded material. If the magnitude of such internal stress or thermal stress exceeds the strength of the insulator, peeling or cracking will occur in the insulating layer.Therefore, measurement and analysis of the internal stress that occurs in resin castings as described above is necessary. At the same time, it is necessary to measure the temperature inside the resin casting. Furthermore, it is desirable that this temperature be measured as close as possible to the pressure transducer. Therefore, in the past, a temperature detection means such as a thermocouple was provided independently near the pressure transducer 1 shown in FIG. 1, but the structure was complicated and
Furthermore, it is not practical as it may cause errors during measurement.

The present invention has a simplified configuration in view of the above points,
The object of the present invention is to provide a pressure converter having a pressure detection function and a temperature detection function.

The present invention provides a pressure sensor in which a core made of magnetostrictive material is provided with an excitation winding and an output winding, in which the output winding is constituted by a thermocouple wire, a joint of the thermocouple wire is provided near the core, and the output of the output winding is This is a pressure transducer that obtains a detection signal and a temperature detection signal.

In other words, in the present invention, the output winding is composed of a thermocouple wire, and the junction of the thermocouple wire is provided near the core, so that pressure detection can be performed by obtaining a pressure detection signal and a temperature detection signal from the output of the output winding. Temperature detection can be performed simultaneously and accurately.

The present invention will be explained in detail below with reference to Examples. FIG. 2 shows a schematic diagram of a pressure transducer according to the invention.

A core 10 made of a magnetostrictive material such as ferrite is provided with, for example, a four-turn excitation winding 11 and an eight-turn output winding 12 . This excitation winding 11 is connected to a signal generator 2. Further, the output winding 12 is constituted by a thermocouple wire consisting of a copper wire 13 and a constantan wire 14, for example, and a joint portion 15 thereof is provided in the vicinity of the core 10. Copper wire 13 and constantan wire 14 constituting this output winding 12 are connected to an electrometer 41 via an AC amplifier 31 to detect a pressure detection signal. Further, an electrometer 42 for displaying a temperature detection signal is connected to the copper wire 13 and the constantan wire 14 in parallel with the AC amplifier 31 via a low-pass filter 5 and a DC amplifier 32. That is, since the temperature detection signal included in the output of the output winding 12 is a DC signal, the low-pass filter 5 is provided to remove the AC component. It has also been found that by using an active filter using an operational amplifier or the like as the low-pass filter 5, it is possible to pass only the DC voltage. In other words, since the output signal of the signal generator 2 generally uses an alternating current signal of several KHz to several hundred KHz, the alternating current signal induced in the secondary coil 12 is filtered by the low pass filter 5 by keeping the turnover frequency of the low pass filter 5 as low as possible. can be sufficiently removed.

In the above example, the copper wire and constantan wire were used as the thermocouple wires within the normal operating temperature range of the ferrite that constitutes the core (-50 to
300°C) and the temperature range during curing of the resin, thermocouple wires and magnetostrictive materials can be selected as appropriate depending on specifications, etc.

Further, FIG. 3 shows an example of characteristics when the generation state of internal stress with respect to temperature change of a thermosetting resin is measured using the pressure transducer according to the present invention.

As described above, by using the pressure transducer according to the present invention, pressure measurement and temperature measurement can be performed simultaneously and accurately.

Further, the pressure transducer 61 itself embedded in the object to be measured has an extremely simplified structure, and only needs to be provided with two output lines 13 and 14, so it can be said to be of great practical value.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional magnetic pressure transducer;
FIG. 2 is a schematic diagram showing a pressure conversion device according to the present invention. 1, 61... Pressure transducer, 32... DC amplifier, 10... Core, 2... Signal generator, 3... Amplifier, 4, 41, 42... Electrometer, 5
...Low pass filter, 31...AC amplifier. FIG. 3 is a curve diagram showing an example of characteristics when using the pressure transducer according to the present invention.

Claims (1)

[Claims] 1. In a pressure sensor in which a core made of magnetostrictive material is provided with an excitation winding and an output winding, the output winding is constituted by a thermocouple wire, and a joint part of the thermocouple wire is provided near the core, and a pressure detection signal and a pressure detection signal are obtained from the output of the output winding. A pressure conversion device characterized by obtaining a temperature detection signal.