JP5377438B2 - Sensor monitoring device - Google Patents

Description

  The present invention relates to a sensor monitoring device, and more particularly to a monitoring device that operates normally even in a high temperature environment.

2. Description of the Related Art Conventionally, a sensor monitoring device converts an output from a sensor into a voltage or converts it into a frequency with an oscillation circuit, and obtains a measured value of the sensor based on the voltage output or the frequency output.
The voltage conversion circuit and the oscillation circuit provided in such a monitoring apparatus are often configured by an IC (integrated circuit) configured by a silicon semiconductor. Patent Documents 1 and 2 are examples in which the oscillation circuit is formed of a silicon semiconductor or the like.

In the oscillation circuit of Patent Document 1, eight transistors are connected in combination with a constant voltage source and a low current source.
In the oscillation circuit of Patent Document 2, a Colpitts oscillation circuit, a crystal oscillation circuit, and a circuit changeover switch are provided inside the oscillator, and the frequency difference between the fundamental oscillation frequency and the harmonic has a substantially linear temperature coefficient. To determine the ambient temperature of the oscillator.

JP-A-62-147812 JP-T 8-500220

The monitoring device may be arranged at a very high temperature, and the temperature of the IC constituting the oscillation circuit in the monitoring device may exceed 200 ° C., and the IC may not operate normally. .
Therefore, by covering the monitoring device with a heat insulating material, it is necessary to devise measures to prevent the IC temperature from rising and operate the IC normally even in a high temperature environment where the monitoring device is placed at a temperature of 200 ° C. or higher. There is.

However, even if the monitoring device is covered with a heat insulating material, when the monitoring device is used for a long time in a high temperature environment, the temperature of the IC gradually approaches the same temperature as in the high temperature environment, and the IC becomes difficult to operate normally. There is.
In addition, when the environmental temperature at which the monitoring device is arranged becomes higher and the environmental temperature becomes 400 ° C. or higher, the IC temperature cannot be made lower than 200 ° C., and the IC operates normally even in a short time. It may not be possible to

  The present invention has been made in view of such circumstances, and in particular, an object of the present invention is to provide a sensor monitoring apparatus that can operate normally even in a high temperature environment and can accurately determine the measured value of the sensor. .

In order to achieve the above-described object, the present invention takes the following technical means.
The technical means of the present invention includes a sensor, an interface having an oscillator to which the sensor is connected and using a wide bandgap semiconductor, and an operation that is arranged separately from the interface and that processes an oscillation signal output from the interface And a device.

Preferably, the oscillator includes a first oscillator that outputs a reference oscillation signal and a second oscillator that outputs an oscillation signal based on the output of the sensor, and the first oscillator and the second oscillator The wide band gap semiconductor may be used in the circuit constituting the circuit.
The arithmetic unit may include an arithmetic unit that calculates a measurement value measured by the sensor based on an oscillation signal from the first oscillator and an oscillation signal from the second oscillator.

It is preferable that the first oscillator and the second oscillator include an LC oscillation circuit.
More preferably, the arithmetic device includes a database in which the frequency of the first oscillator that changes depending on the operating temperature, the frequency of the second oscillator that changes depending on the operating temperature and the output of the temperature sensor, and the measured value of the sensor are associated. The calculation unit may calculate the measured value of the sensor based on the frequency of the first oscillator, the frequency of the second oscillator, and the database.

The first oscillator and the second oscillator are configured by substantially the same oscillation circuit, and the frequency of the oscillation signal output from the first oscillator and the oscillation signal of the second oscillation signal when there is no output from the sensor. It is preferable that the frequency is set substantially the same.
The most preferable form of the sensor monitoring apparatus according to the present invention is a sensor, an interface including the oscillator to which the sensor is connected and using a wide bandgap semiconductor, and an output arranged from the interface and output from the interface. And an arithmetic unit that processes the generated oscillation signal, wherein the oscillator includes a first oscillator that outputs an oscillation signal as a reference, and a second oscillator that outputs an oscillation signal based on the output of the sensor The wide band gap semiconductor is used for the circuits constituting the first oscillator and the second oscillator.

  According to the present invention, the measured value of the sensor can be accurately obtained by operating normally even in a high temperature environment.

It is a whole lineblock diagram showing the whole sensor monitoring device. It is the figure which showed the example which installed the sensor and the interface in the high temperature environment. (A) It is a circuit diagram of a 1st oscillator, (b) It is a circuit diagram of a 2nd oscillator. It is the figure which showed the relationship between the operating temperature of an oscillation circuit, and an oscillation frequency. It is the figure which showed the relationship between the voltage of the bias of a constant voltage device, and frequency. (A) It is a circuit diagram of the 1st oscillator at the time of changing a transistor, (b) It is a circuit diagram of the 2nd oscillator at the time of changing a transistor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the sensor monitoring device 1 of the present invention is a device that operates normally even in a high temperature environment, and is arranged separately from the sensor 2, the interface 3 to which the sensor 2 is connected, and the interface 3. And an arithmetic unit 4.
In the following description, the environmental temperature is a temperature around a part where a part such as an interface is installed, and the operating temperature is a temperature of the part itself when the part is operating.

The sensor 2 includes a temperature sensor that measures the temperature of an object to be measured, a gas sensor that measures the concentration of gas, etc., and a pressure of fluid. In this embodiment, the temperature sensor 2 will be described as an example.
As shown in FIG. 2, the temperature sensor 2 measures the temperature of the outer wall surface 5 of a blast furnace or a converter that is a measurement object, or the outer wall surface 5 of a container (for example, a ladle) charged with molten metal. For example, it is composed of a thermocouple that generates an electromotive force according to the measured temperature.

The interface 3 is disposed near the temperature sensor 2 and is disposed under a high temperature condition of 200 ° C. or higher. For example, it is arranged near the outer wall surface of the blast furnace, the outer wall surface of the converter, and the outer wall surface of the ladle.
The interface 3 includes an oscillator 6. Specifically, the interface 3 includes a plurality of oscillators 6 and 6 (for example, two), one oscillator 6a (first oscillator) outputs a reference oscillation signal, and the other oscillator 6 b (second oscillator) outputs an oscillation signal based on the output of the sensor 2. The oscillation signal of the first oscillator 6 a and the oscillation signal of the second oscillator 6 b are transmitted to the arithmetic device 4 by a transmitter 7 such as a radio provided in the interface 3.

First, the first oscillator 6a and the second oscillator 6b will be described.
As shown in FIGS. 3A and 3B, the first oscillator 6a and the second oscillator 6b are composed of electronic components such as a coil, a capacitor, a transistor, a diode, and a resistance element, a substrate on which they are arranged, and the like. Yes. Since the interface 3 is disposed under a high temperature condition, components (coils, capacitors, transistors, diodes, resistance elements, wiring, substrates, etc.) of the first oscillator 6a and the second oscillator 6b must be capable of withstanding high temperatures. I use it.

  For example, in the first oscillator 6a and the second oscillator 6b, a ceramic capacitor is used as a capacitor, ceramic insulation is applied to a resistance element and a coil, and high-temperature solder having a melting point of 310 ° C. is used as solder. All parts use metals, ceramics, polytetrafluoroethylene, polyimide, etc. having heat resistance of 250 ° C. or higher, and materials having low heat resistance are not used.

  The power supply 8 of the first oscillator 6a and the second oscillator 6b is a high-temperature lithium battery placed in a heat insulation box and connected to an oscillation circuit by an enameled wire or the like. The first oscillator 6a, the second oscillator 6b, the transmitter 7 and the heat insulation box are housed in one case 9 (for example, a metal case), and the transmitting antenna 10 is connected to the outside of the metal case 9, thereby configuring the entire interface 3. doing. The transmitter 7 is also configured using heat-resistant parts.

As the power source 8, a thermoelectric element utilizing the heat of the hot wall or a sodium sulfur (NaS) battery may be used.
Here, when the temperature at which each electronic component operates (operating temperature) changes due to a change in the environmental temperature or the like where the interface 3 is disposed, the characteristics change and the frequency of the oscillation signal changes. It has been found.

  Therefore, as described later, the measurement value measured by the sensor 2 is obtained from the frequency of the oscillation signal due to the temperature dependence of the first oscillator 6a and the frequency of the oscillation signal according to the output of the sensor 2 of the second oscillator 6b. The temperature characteristics (temperature dependence) of the first oscillator 6a and the temperature characteristics of the second oscillator 6b (temperature dependence) so that correct measurement values can be measured even if the operating temperatures of the first oscillator 6a and the second oscillator 6b change. The temperature dependence is the same.

Specifically, the types of components, the arrangement of components (component orientation), the manufacturing lot of components, the number of components, and the like are made the same in a circuit portion common to the first oscillator 6a and the second oscillator 6b. Furthermore, the board deployment position, deployment direction, and the like in the heat insulation box are the same.
Now, since the oscillation signal output from the first oscillator 6a and the oscillation signal output from the second oscillator 6b are transmitted by the transmitter 7 such as a radio, it is necessary to reduce the size of the entire circuit and suppress power consumption. The frequency of the oscillation signal is preferably a high frequency. In the present invention, the oscillation circuit of the first oscillator 6a and the oscillation circuit of the second oscillator 6b include an LC oscillation circuit, and can output a high frequency of 100 MHz or more.

As shown in FIG. 3, the oscillation circuits of the first oscillator 6a and the second oscillator 6b are configured by providing a Colpitts type circuit on a ceramic circuit board having high heat dissipation.
An oscillation signal having a predetermined frequency is output from the output section of the first oscillator 6a. The second oscillator 6b is configured such that the variable capacitance diode 11 formed of a diamond substrate is attached to the oscillation circuit of the first oscillator 6a, and the frequency of the oscillation signal changes when the capacitance of the variable capacitance diode 11 changes. ing. The temperature sensor 2 is connected to the variable capacitance diode 11 so that the capacitance changes according to the input (electromotive force) from the temperature sensor 2.

Therefore, the oscillation circuit of the first oscillator 6a and the oscillation circuit of the second oscillator 6b differ only in whether or not the portion to which the temperature sensor 2 is connected (variable capacitance diode 11) is provided. The oscillation circuit of the second oscillator and the oscillation circuit of the second oscillator 6b have substantially the same configuration.
Therefore, when there is no output from the temperature sensor 2, the frequency of the oscillation signal output from the first oscillator 6a and the frequency of the oscillation signal of the second oscillation signal are the same.

  More specifically, in the present invention, as described above, the configuration of the oscillation circuit is made common so that the temperature dependency of the oscillation circuit of the first oscillator 6a and the oscillation circuit of the second oscillator 6b are the same. When the input from the sensor 2 is ignored, if the temperature is the same (the operating temperature is the same), the oscillation frequency from the first oscillator 6a and the oscillation frequency from the second oscillator 6b are made equal. Yes.

The oscillation circuits of the first oscillator 6a and the second oscillator 6b may be a Hartley type, a clap type, a crystal oscillator, a ceramic oscillator, or the like, or a multivibrator type. However, the frequency of the oscillation circuit is preferably 100 MHz as described above.
In configuring the oscillation circuit, it is preferable that the frequency change due to the temperature change, that is, the temperature characteristic of the frequency change linearly, and the number of parts is preferably reduced. For example, in the case where an oscillation circuit is configured using a plurality of transistors, each element of the transistor has different frequency characteristics and temperature characteristics, and there are individual differences, so that the temperature characteristics may be complicated. From this point of view, the Colpitts type or the Hartley type, in which the oscillation circuit can be configured with one transistor, is most desirable.

Here, the transistor 12 used in the first oscillator 6a and the second oscillator 6b will be described.
In the conventional Si transistor, when the operating temperature is 200 ° C. or higher, the leakage current increases, that is, the power consumption increases. When the operating temperature is 250 ° C. or higher, it cannot operate normally. In the present invention, a semiconductor having a large band gap, that is, a wide band gap semiconductor is used as a semiconductor (for example, the transistor 12) constituting at least the circuit in the interface 3 in order to operate normally even under high temperature conditions. Yes. The transistor 12 is preferably made of a wide band semiconductor having a band gap of 2.5 eV or more.

  Specifically, the transistor 12 is a MISFET type in which a p-i-p structure is constructed on a diamond substrate (band gap≈5 eV). Further, the transistor 12 is of a normally-off type in which no channel exists and no drain current flows when no gate voltage is applied, thereby reducing power consumption. The type of the transistor 12 used for the first oscillator 6a and the second oscillator 6b is not limited as long as it has a large band gap and operates reliably at high temperatures. A MESFET type or a MOSFET type with lower power consumption may be used.

The above-described variable capacitance diode 11 is also a wide band gap semiconductor which is formed of a diamond substrate and has a large band gap.
Therefore, since wide band gap semiconductors are used for the first oscillator 6a and the second oscillator 6b, for example, the first oscillator 6a and the second oscillator can be used even in a high temperature environment where the ambient temperature (ambient temperature) is 200 ° C. or higher. 6b can be operated normally.

  In the interface 3 composed of the first oscillator 6a and the second oscillator 6b, when the temperature is measured by the temperature sensor 2, the oscillation frequency of the oscillation signal of the second oscillator 6b changes according to the output of the temperature sensor 2. become. The oscillation signal whose frequency changes in accordance with the output of the temperature sensor 2 is transmitted to the arithmetic device 4 via the transmitter 7, and the oscillation signal of the first oscillator 6 a is also transmitted to the arithmetic device 4 via the transmitter 7. Sent. The calculation value of the temperature sensor 2 is obtained by the arithmetic device 4.

  Now, the frequency in the oscillation signal of the second oscillator 6b changes according to the output of the temperature sensor 2, but even if the output of the temperature sensor 2 is the same, the oscillation frequency depends on the operating temperature of the second oscillator 6b. May be different. In such a case, if the oscillation frequency of the second oscillator 6b is replaced with the measured value as it is, it cannot be accurately obtained by the temperature sensor 2, so in the present invention, the first oscillator having the same temperature characteristics as the second oscillator 6b is used. By using the oscillation frequency 6a, correction (calibration) by temperature change is performed to obtain an accurate measurement value.

Next, a calculation method for obtaining the temperature of the temperature sensor 2 will be described in accordance with the configuration description of the calculation device 4.
The arithmetic device 4 is composed of, for example, a computer. This computing device 4 is different from the installation location of the interface 3 and is arranged at a different location, and is arranged at a location that is not under a high temperature environment such as the interface 3 where the environmental temperature is 200 ° C. or higher. . For example, the arithmetic device 4 is disposed at a place where the ambient temperature is normal temperature.

This computing device 4 includes a database 14 in which data for obtaining the temperature measured by the temperature sensor 2 is stored, and a computing unit 15 for obtaining the temperature measured by the temperature sensor 2. Note that the spectrum analyzer 13 may be connected to the arithmetic unit 4 to display the frequency of the oscillation signal of the first oscillator 6a and the frequency of the oscillation signal of the second oscillator 6b.
The database 14 stores the frequency of the transmission signal transmitted from the first oscillator 6a, the frequency of the transmission signal transmitted from the second oscillator 6b, and the measured value of the temperature sensor 2 in association with each other.

More specifically, as shown in FIG. 1, when the operating temperature of the first oscillator 6a changes, the oscillation frequency (frequency 1) in the first oscillator 6a also changes. Further, when the operating temperature of the second oscillator 6b changes, the oscillation frequency (frequency 2) in the second oscillator 6b also changes.
Here, the temperature characteristics of the first oscillator 6a and the second oscillator 6b are the same, and the first oscillator 6a and the second oscillator 6b are considered to be isothermal in the interface 3; If the oscillation frequency of the oscillator 6a and the oscillation frequency of the second oscillator 6b are known, a frequency corresponding to the output of only the temperature sensor 2 in the second oscillator 6b can be extracted.

  As described above, the oscillation frequency of the first oscillator 6 a that varies depending on the operating temperature, the oscillation frequency of the second oscillator 6 b that varies depending on the operating temperature and the output of the temperature sensor 2, and the actually measured temperature (temperature sensor). A data group in which the relationship with (value) is organized is stored in the database 14. That is, the database 14 stores data in which the oscillation frequency of the first oscillator 6a, the oscillation frequency of the second oscillator 6b, and the temperature of the temperature sensor 2 are associated.

Therefore, according to the database 14, for example, when the oscillation frequency of the first oscillator 6a is 319.1 MHz and the oscillation frequency of the second oscillator 6b is 317.9 MHz, the measured value of the temperature sensor 2 is 1398 ° C. You can understand that.
There are various methods for creating the database 14 described above. In the present embodiment, the database 14 is created by the following method.

  First, in order to create the database 14, the input terminal of the variable capacitance diode 11 of the second oscillator 6b is short-circuited, and the oscillation frequency of the second oscillator 6b is received by the arithmetic unit 4 side via the transmitter 7. Thereafter, the oscillation frequency of the second oscillator 6 b was measured using the spectrum analyzer 13. Then, the circuits in the respective oscillators 6a and 6b were tuned so that the oscillation frequency of the second oscillator 6b and the oscillation frequency of the first oscillator 6a were the same. For example, the oscillation circuit is adjusted so that the oscillation frequency of the second oscillator 6b and the oscillation frequency of the first oscillator 6a are 317 MHz. The oscillation frequency of the second oscillator 6b (the oscillation frequency of the first oscillator 6a) is not limited to 317 MHz.

  Next, the interface 3 (metal case 9) is placed on a heating device (for example, a hot plate) to simulate exposure to a high temperature environment, and as shown in FIG. 4, the oscillation frequency of the second oscillator 6b. The temperature characteristics of were measured. In order to simulate the input from the temperature sensor 2, a variable voltage source was connected to the variable capacitance diode 11, and the temperature of the metal case 9 was stabilized at 250 ° C.

Thereafter, as shown in FIG. 5, the voltage of the constant voltage source is changed within a range in which an electromotive force can be generated from the temperature sensor 2, and the correlation between this voltage and the oscillation frequency from the second oscillator 2b is recorded. did.
Then, the database 14 was created using the temperature characteristics of the oscillation frequency shown in FIG. 4 and the oscillation frequency and bias voltage (voltage of the constant voltage source) shown in FIG.

On the other hand, the calculation unit 15 provided in the calculation device 4 calculates a measurement value measured by the temperature sensor 2 based on the database 14 created as described above.
Specifically, the arithmetic unit 15 first receives the oscillation signal of the first oscillator 6a transmitted from the interface 3, and extracts the oscillation frequency of the first oscillator 6a. The oscillation signal of the second oscillator 6 b transmitted from the interface 3 is received, and the oscillation frequency of the second oscillator 6 b corresponding to the output from the temperature sensor 2 is extracted.

Then, the oscillation frequency of the first oscillator 6a and the oscillation frequency of the second oscillator 6b are referred to the database 14, and the values in the database 14 corresponding to both these two frequencies are measured by the temperature sensor 2 (estimated value). ).
As described above, the sensor monitoring apparatus 1 according to the present invention can operate normally even if the sensor 2 and the interface 3 are installed in a place with a high temperature. In addition, in the arithmetic device 4 arranged separately from the interface 3, the measured value of the temperature sensor 2 is estimated using the database 14 subjected to temperature calibration. Therefore, the sensor monitoring device 1 can accurately determine the measured value of the sensor even in a high temperature environment even if the temperature changes.

The present invention is not limited to the above-described embodiments, and the shape, structure, combination, and the like of each member 2 can be appropriately changed without changing the essence of the invention.
For example, when the transistor 12 for the oscillation circuit is configured to operate in a depletion mode (such as an n-channel depletion mode FET made of SiC), the circuits of the first oscillator 6a and the second oscillator 6b are used. 6 (a) and 6 (b) are preferable.

In addition, since the interface 3 is disposed in a high temperature environment, it is preferable to use not only a semiconductor used for an oscillator and a transmitter as described above but also a wide band gap semiconductor having a large band gap as a semiconductor used for the interface 3.
Further, in the arithmetic device 4, the difference between the frequency of the first oscillator 6 a and the frequency of the second oscillator 6 b is obtained, and the relationship between the obtained difference frequency and the voltage (actual measurement value) of the temperature sensor 2 is made into a database or a function. Thus, an actual measurement value by the temperature sensor 2 can be obtained.

  In this embodiment, it has been described that the interface 3 can be used in a high temperature environment by using a wide band gap semiconductor for the oscillator 6 or the like. However, the interface 3 can also be used in a strong radiation environment having a high radiation intensity.

DESCRIPTION OF SYMBOLS 1 Monitoring apparatus 2 Sensor 3 Interface 4 Arithmetic apparatus 5 Outer wall surface 6 Oscillator 6a 1st oscillator 6b 2nd oscillator 7 Transmitter 8 Power supply 9 Metal case 10 Transmitting antenna 11 Variable capacity diode 12 Transistor 13 Spectrum analyzer 14 Database 15 Calculation part

Claims (5)

A sensor, an interface including an oscillator to which the sensor is connected and using a wide bandgap semiconductor, and an arithmetic unit arranged separately from the interface and processing an oscillation signal output from the interface ,
The oscillator includes a first oscillator that outputs a reference oscillation signal and a second oscillator that outputs an oscillation signal based on the output of the sensor, and constitutes the first oscillator and the second oscillator. A sensor monitoring apparatus , wherein the circuit uses the wide band gap semiconductor . The arithmetic device according to claim 1, based on an oscillation signal from the oscillation signal and the second oscillator from said first oscillator, characterized in that it comprises a calculation unit for calculating a measured value measured by the sensor The sensor monitoring device according to 1. The sensor monitoring device according to claim 1, wherein the first oscillator and the second oscillator include an LC oscillation circuit. The computing device includes a database in which the frequency of the first oscillator that changes depending on the operating temperature, the frequency of the second oscillator that changes depending on the operating temperature and the output of the temperature sensor, and the measured value of the sensor are associated with each other.
The arithmetic unit includes a frequency of the frequency and a second oscillator of the first oscillator, the based on the database, the sensor according to any of claims 1 to 3, characterized in that to calculate the measurement value of the sensor Monitoring device. The first oscillator and the second oscillator are configured by substantially the same oscillation circuit, and the frequency of the oscillation signal output from the first oscillator and the frequency of the oscillation signal of the second oscillation signal when there is no output from the sensor. The sensor monitoring device according to claim 1 , wherein the sensor monitoring device is set to be substantially the same.

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