JPS63238436A - Active type temperature sensor - Google Patents

Abstract

PURPOSE:To measure temp. to transmit the same without using an external power source, by using an element efficiently generating power at the time of the measurement of temp. and converting said power to a temp. signal and the power source of a transmitter. CONSTITUTION:This sensor is constituted of a thermoelectric converter element 1, an electrode 2, cooling fins 3 and a transmitter 4. The thermoelectric converter element 1 is constituted of a structure having a solid elements capable of directly converting heat to electricity, that is, a pair of an N-type semiconductor and a P-type semiconductor and generating potential difference on both high and low temp. sides. The generated voltage is shown by the product of the coefficient (Seebeck coefficient) determined by the characteristics of the N-type and P-type semiconductors and the temp. difference between the upper and lower surfaces of the sensor. As mentioned above, by using the element capable of directly and efficiently converting heat to electricity and transmitting temp. data by converting the quantity of the generated electricity to a temp. signal and the power source of the transmitter and providing a receiver capable of collectively receiving the signals from a large number of sensors to the outside, the wireless transmission and reception of temp. become possible without supplying a power source from the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to instrumentation of various plants, and particularly to an active temperature measurement and transmission system suitable for measuring and transmitting temperature.

[Conventional technology]

There are various methods for temperature measurement depending on the purpose, as detailed in, for example, Industrial Measurement Handbook published by Shokusen Shoten, 1980, 2nd edition, pages 249 to 257. In addition, thermocouples, which are one of the measurement methods mentioned above, are used in nuclear power generation, which is one of the high-temperature plants.
There are approximately 1,500 cables in 1, and the cables are routed from the measurement point to the central control room, totaling approximately 60,000 km.

Thermometers using thermocouples are the most common and have a good track record, but they require a cable to be routed from the measurement point to the measuring device. It also sends signals wirelessly.

[Problem that the invention seeks to solve]

The temperature measurement method using a thermocouple described above is the most common and has a rich track record, but it requires a cable to be routed from the measurement point to the measuring device. Additionally, transmitting temperature signals wirelessly requires an external power source to operate the transmitter.

Therefore, a high-temperature plant with many measurement points requires an enormous amount of wiring and its work cost.

An object of the present invention is to provide an active sensor that can measure and transmit temperature without an external power source, to make it wireless, and to reduce wiring and the amount of work involved.

[Means for solving problems]

The above object is achieved by using an element that efficiently generates electric power during temperature measurement and converting the electric power into a temperature signal and a power source for the transmitter.

[Effect]

The temperature sensor uses an element that can efficiently convert heat directly into electricity, and the generated electricity is used as a temperature signal and power source for the transmitter to transmit temperature data, and an external receiver that can receive signals from multiple sensors at once is installed. By providing this, wireless temperature transmission and reception is possible without an external power supply.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Active sensors are thermoelectric conversion elements1. Electrode 2゜Cooling fin 39
It consists of a transmitter 4. The thermoelectric conversion element 1 is a solid-state element that can directly convert heat into electricity, that is, an N-type semiconductor and a P-type semiconductor.
Pair the type semiconductors.

It consists of something that creates a potential difference between the high temperature and low temperature ends. The generated voltage is expressed as the product of a coefficient (Seebeck coefficient) determined by the characteristics of the N-type and P-type semiconductors and the temperature difference between the upper and lower surfaces. The characteristics of this thermoelectric conversion element 1 are shown in FIG. 2, and the schematic circuit diagram of the oscillator is shown in FIG.

The transmitter 4 converts the power generated by the thermoelectric conversion element into radio waves.

In the six application examples of converting into light or laser and transmitting, an example of converting into radio waves is shown. Amplitude modulation (
Possible methods include AM) and frequency modulation (FM).

Here, an example of a PWM-FM radio wave circuit that transmits signals using pulse width modulation (PWM) L and FM is shown. The transmitter 4 has a reference resistor 7. Constant voltage power supply generator8. Sawtooth wave generator6. It consists of a comparator 9 and a frequency modulator 10.

As shown in FIG. 2, the open circuit voltage Ex of the thermoelectric conversion element 1 increases to Ex, Ex, Ea, .

By connecting a reference resistor 7 and a constant voltage power supply generator 8 to this, the open circuit current changes. The Zener diode of the constant voltage power supply generator 8 is connected to the sawtooth wave generator 6 and the frequency modulator 1.
The current flowing through the reference resistor 7, which works to keep the operating voltage Eo at 0 constant, is (E--Eo)/R, and is It and It, respectively.

Engineering 3... The value of engineering. This current value was converted into a voltage V, which was used as a modulation signal for the comparator 9. The comparator 9 operates a sawtooth wave generator using the power supplied from the constant voltage power supply generator 8, receives the sawtooth wave, compares it with a modulation signal, and modulates it into a pulse width. The PWM signal modulated into a pulse width was guided to a frequency modulator 10 operated by a power source supplied from a constant voltage power source generator 8, similar to the sawtooth wave generator 6, and was transmitted as an FM wave.

The transmitted FM wave was received by a receiver (not shown) and inversely converted into a voltage V. The open circuit voltage E'x is the known Eo and vl
This value was converted into the temperature difference of the thermoelectric conversion element 1, and the temperature of the object was determined by adding the temperature of the atmosphere.

Next, an example will be shown in which an Fe-5i semiconductor is applied to the thermoelectric conversion element 1 shown in FIG. Twenty pairs of semiconductor chips each having a length of 2 mm+, a width of 2 nm, and a thickness of 1 mm were connected in series to form a thermoelectric conversion element 1 having external dimensions of 15×10×2++n+. Copper was used for the electrode 2, and AΩ was used for the cooling fin 3. The length of the cooling fins 3 was set to 100 nn, and the structure was such that the upper surface of the thermoelectric conversion element 1 could be sufficiently cooled. When a temperature difference of 200°C is applied between the upper and lower surfaces of the thermoelectric conversion element 1, an open circuit voltage of 2V and a current of about 2A are obtained.If the operating voltage of the transmitter is 1V, it is possible to transmit from a temperature difference of 100'C. . The temperature of the object to be measured can be measured from 130°C by correcting the room temperature of 30°C.

As described above, according to the present invention, measured temperature data can be transmitted wirelessly, and the cost of external power supply and wiring work can be reduced.

Next, we will show an example in which this sensor is actually applied to a high-temperature plant. A heat insulator 11 is applied to the surface of the object to be measured 10 in a high-temperature plant to prevent heat radiation. A part of this insulation is peeled off and a good thermal conductor 12, such as silicon carbide (S) is removed.
iC), thermally anisotropic carbon, or the like is attached to the object to be measured 10, and the active sensor of the present invention is attached thereon.

On the other hand, in the case of a high-temperature plant, on the receiving side, a bulkhead is often provided to ensure safety, so an antenna 14 is installed inside the bulkhead 13 to receive radio waves transmitted from a large number of active sensors. A receiver 15 is installed outside the partition wall 13. The receiver 15 is connected to a transmission circuit 16 because it is necessary to transmit measurement data to the central control room of the high-temperature plant.

The transmission circuit 16 is provided with one thermocouple 17 that measures the atmospheric temperature within the partition wall 13 and serves as a reference for the active sensor. Here, when a large number of sensors are installed, sensor discrimination becomes a problem. Therefore, as shown in Figure 5, we adopted multiplex transmission in which the frequency band was changed when transmitting FM waves, making it possible to discriminate between sensors.

As described above, when the present invention is applied to multiple temperature measurements in a high-temperature plant, there is no need for cables inside the walls, and only one cable is required to penetrate the partitions, which improves safety. Particularly when applied to the primary cooling system of a nuclear power plant, the bulkhead has the role of a radiation shield, so it is effective in reducing the number of through cables and preventing external contamination with radioactivity.

〔Effect of the invention〕

According to the present invention, since wireless temperature measurement is possible, there are effects such as eliminating the amount of wiring and significantly reducing wiring work costs.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of an active sensor according to an embodiment of the present invention, FIG. 2 is a schematic diagram of the characteristics of the thermoelectric power conversion element shown in FIG.
The figure is a circuit configuration diagram of Figure 1, Figure 4 is a system configuration diagram when the active sensor of the present invention is applied to a plant, and Figure 5 is a diagram of the system configuration when the active sensor of the present invention is applied to a plant.
The figure shows an example of data transmission in FIG. 4. DESCRIPTION OF SYMBOLS 1... Thermoelectric conversion element, 2... Electrode, 3... Cooling fin, 4... Transmitter, 6... Sawtooth wave generator, 7
...Reference resistance, 8...Constant voltage power supply generator, 9...
Comparator, LhT3 I, L r#I trace t8e (I)

Claims (1)

[Claims] 1. A temperature measurement unit comprising a temperature measurement unit that converts the temperature of an object into a thermoelectromotive force and outputs it, and a transmitter that converts the thermoelectromotive force into an electrical signal or an optical signal and transmits the same, An active temperature sensor characterized by the ability to transmit signals wirelessly. 2. The performance temperature sensor according to claim 1, wherein a semiconductor solid-state element is used in the temperature measurement section, and the generated thermoelectromotive force is used as a temperature signal and a power supply for a transmitter.