JPS631527B2 - - 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 magnetic pressure transducer that uses the magnetostrictive effect and uses a small core can be embedded in materials such as thermoset plastics and prestressed concrete, and then measure the internal stress generated in such materials as they harden. It is already known that it can be done. These internal stress measurements are made without significant side effects due to the presence of a core embedded in the material. Furthermore, the additional internal stresses that occur 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
1 shows a schematic diagram of a circuit diagram illustrating how a microtransducer with a core 10 excited by a signal generator 2 connected via a primary coil, and an output winding 12 secondary coil is used for stress measurements; FIG.

Excitation winding 11 (primary coil) and output winding 1
Although the number of turns of the second coil (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 canceling noise associated with the output signal. In a typical application, the pressure transducer 1 is embedded in an epoxy resin and the internal stresses generated in the epoxy resin during curing induce an output signal in an output winding 12 (secondary coil) spread around a core 10. Observed by monitoring. The output signal is fed to an amplifier 3 and displayed on a conventional electrometer 4.

Such an application example is used to analyze the internal stress caused by curing shrinkage during the process of changing the resin of cast insulators from a liquid state to a solid state during casting, and during the process of cooling from high temperature to room temperature. 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.
Therefore, when the equipment stops operating, a temperature distribution occurs within the insulating layer, and thermal stress is generated due to the difference in coefficient of thermal expansion and modulus of elasticity between the resin and the implant. 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, and 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 installed independently near the pressure transducer 1 as shown in Fig. 1, but the configuration was complicated, and errors may occur during measurement, making it impractical. It wasn't something.

In view of the above points, an object of the present invention is to provide a pressure transducer having a simplified structure and having a pressure detection function and a temperature detection function.

The present invention comprises a core made of a magnetostrictive material, an excitation winding and a thermocouple wire wound around the core, and an output winding having a joint portion thereof near the core, and a signal connected to the excitation winding. a generator, a temperature detection unit comprising an electrometer connected to the output winding via a first changeover switch and a DC amplifier, a second changeover switch connected in parallel with the temperature detection unit to the output winding, and an AC Through an amplifier, the pressure detection unit is operated in response to the output from a pressure detection unit including an electrometer provided and the signal generator, and the temperature detection is performed when the output from the signal generator is in a zero state. This pressure transducer is equipped with a reference signal generator for operating the pressure transducer.

That is, in the present invention, by configuring the output winding with a thermocouple wire and providing the joint portion of the thermocouple wire near the core, pressure detection and temperature detection can be made accurate. In addition, there are only two output lines from the pressure transducer, simplifying the configuration, and the temperature detection section and pressure detection section are controlled by the reference signal generator, making continuous measurement possible and more accurate. It is now possible to make measurements. In other words, the pressure detection signal is an AC signal, and the temperature detection signal is a DC signal, so as shown in Figure 2, when the input signal from the signal generator is "0" (OFF state), The input signal to the first changeover switch is turned ON to operate only the temperature detection section, and when the input signal is "1" (ON state), the input signal to the second changeover switch is turned ON to operate the pressure detection section. operate only.

The present invention will be explained in detail below with reference to Examples. FIG. 3 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 composed of a thermocouple wire made of, for example, a copper wire 13 and a constantan wire 14, and a joint portion 15 thereof is provided near the core 10. This output winding 12 is connected to the first changeover switch 31
It is connected via a DC amplifier 41 to a temperature detection section 1 comprising an electrometer 51 which is to measure the detected temperature. Further, a pressure sensing section is connected to the output winding in parallel with the temperature sensing section. This pressure detection section is composed of a second changeover switch 32 and an electrometer 52 that measures the detected pressure via an AC amplifier 42. Note that the first changeover switch 31 and the second changeover switch 32 are controlled by a reference signal generator synchronized with the signal generator 2. In other words, as shown in FIG. 2, when the input signal from the signal generator 2 is "0" (OFF state), the reference signal generator 21
The input signal to the first changeover switch 31 is turned on, and the input signal to the second changeover switch 32 is turned off by the output from the switch. As a result, a DC signal output from the output winding 12 of the pressure transducer 16 is supplied to the temperature detection section, and the electrometer 51 can accurately detect the temperature without noise. Also, when the input signal from the signal generator 2 is "1" (ON state), the output from the reference signal generator 21 turns the input signal to the first changeover switch 31 into the ON state, and the input signal to the second changeover switch 32 is turned ON. The input signal of is turned off.
As a result, an alternating current signal output from the output winding 12 of the pressure transducer 16 is supplied to the pressure sensing section, allowing the electrometer 52 to accurately detect pressure. Note that the pressure detection and temperature detection described above do not need to measure all "0" and "1" states of the input signal from the signal generator shown in Figure 2, and it is possible to set an appropriate measurement time interval as necessary. can.

In addition, in the above embodiment, the copper wire and constantan wire were used as the thermocouple wire because the temperature range (-50 to 300
℃) and the temperature range during curing of the resin, and the thermocouple wire and magnetostrictive material can be selected as appropriate depending on the specifications.

As the first and second changeover switches, one having mechanical operation such as a relay, one having semiconductor operation such as an analog switch, etc. can be selected as appropriate.

Here, if a multi-vibrator (FF), for example, is used as the reference signal generator 21, the DC output and AC output generated in the output winding (secondary coil) can be taken out alternately. The cycle time of the reference signal generator 21 needs to be sufficiently lower than the frequency of the signal generator 2'. For example, if the frequency of the signal generator 2' is 10KHz, the frequency of the reference signal generator 21 is 100 to 500Hz. The condition is good. It has been found that it is possible to extract a temperature detection output and a pressure conversion output from the output winding (secondary coil) of the core 10 configured as described above.

Furthermore, since the output of the pressure transducer is an intermittent signal, industrially it is necessary to use a DC amplifier 31 and an AC amplifier 3.
2 is monitored by an electrometer or the like via appropriate signal processing. That is, a sample-and-hold circuit, for example, is often provided to hold the intermittent signal for a certain period of time.

FIG. 4 shows an example of characteristics when the state of internal stress generated in a thermosetting resin with respect to temperature change is measured using the pressure transducer according to the present invention.

As described above, by using the present invention, it becomes possible to accurately detect pressure and temperature with a pressure transducer having a simplified structure, and it can be said to be of great practical value.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional pressure converter, FIG. 2 is a diagram showing the operation of a reference signal generator and first and second changeover switches in the present invention, and FIG. 3 is a pressure converter according to the present invention. Schematic diagram showing the device. 2... Signal generator, 10... Core, 11... Excitation winding, 12... Output winding, 21... Reference signal generator, 31... First changeover switch, 41... DC amplifier, 32... Second changeover switch, 42...
...AC amplifier, 51, 52...electrometer. FIG. 4 is a curve diagram showing an example of characteristics when using the pressure transducer according to the present invention.

Claims (1)

[Claims] 1. A core made of a magnetostrictive material, an output winding comprising an excitation winding and a thermocouple wire wound around the core, the joint of which is provided near the core, and connected to the excitation winding. a temperature sensing section comprising an electrometer connected to the output winding via a first changeover switch and a DC amplifier; and a second switching section connected in parallel with the temperature sensing section to the output winding. a pressure detection section consisting of an electrometer provided via a switch and an AC amplifier; and the pressure detection section is operated in response to the output from the signal generator, so that the output from the signal generator is zero.
1. A pressure transducer comprising: a reference signal generator that operates the temperature detecting section when the temperature detecting section is in the above state.