JP3135987B2 - Temperature detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device used for measuring the temperature of a device having an electrically insulating portion or a rotating body. More specifically, the present invention relates to a temperature detecting device using an insulating transformer, particularly a rotary transformer.

[0002]

2. Description of the Related Art Rotating members such as a rotating roll for magnetic tape, a rotating roll for embossing, and a rotating roll for calendar include:
Some are heated and used, and accurate temperature detection and temperature control may be required. In order to measure the temperature of a device or a rotating body having such an electrically insulating portion, it is necessary to cut a part of the temperature detection line (wire) and take out the temperature detection signal in an electrically non-contact state.

Conventionally, a rotary transformer used for measuring the temperature of a rotating body detects a change in electric resistance value due to a temperature change through the rotary transformer. This will be described below with reference to the drawings. FIG. 4 is an example of a conventional example. In FIG. 2, 1B is a resistance temperature detector (thermistor), 2 is a rotary transformer, 3 is a rotating part, 4 is a fixed part, 5 is a detection amplifier unit,
6 is an AC bridge, 7 is a differential amplifier, 8 is a synchronous rectifier,
9 is an AC reference voltage source, 10 is a voltage output, and 11 is a power supply input. Then, a rotary transformer 2 is inserted between the temperature measuring resistor 1 as a temperature sensor and the detection amplifier unit 5, and is used as a coupling transformer for transmitting a resistance value.

In such a configuration, the resistance thermometer 1
, The characteristics of the rotary transformer 2 are added. In other words, the winding resistance of the rotary transformer 2 and the leakage
The inductance enters the resistance in series, and the primary inductance and the eddy current of the core become parallel. The combined resistance becomes the input of the detection amplifier unit 5.

[0005]

However, the temperature detecting device of the prior art described above becomes a combined resistance of the resistance of the transformer and the resistance of the sensor (hereinafter referred to as "combined resistance") and requires a thermistor having a large resistance change. there were. That is, the types of sensors that can be used are limited by the characteristics of the rotary transformer 2, and a thermistor having a large resistance change due to temperature is mainly used as a temperature sensor.
Specifically, the temperature was measured using a resistance of several KΩ because of the combined resistance.

Therefore, it is difficult to obtain the linearity of the voltage output 10 detected corresponding to the temperature, and there is a problem that a temperature error is high. Therefore, individual temperature correction was required for each unit. Further, the characteristics of the rotary transformers differ one by one also depending on the mechanical accuracy (for example, clearance or the like) of the rotary transformer itself, and it is necessary to correct each one by the detection amplifier unit 5. Further, since such correction is necessary, it is necessary to use a specific rotary transformer and a specific detection amplifier unit device which has been subjected to temperature correction in a pair, and there is a problem that there is no alternative.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, in which the temperature can be measured accurately, the error is small, and even if it is attached to a heating device, the temperature of each rotating transformer does not need to be corrected one by one. It is an object to provide a detection device.

[0008]

In order to achieve the above-mentioned object, a temperature detecting device of the present invention is a temperature detecting device for an object having an electrically insulating portion, wherein the temperature measuring device converts a temperature into a resistance value. Body, a bridge circuit and an amplifier circuit for converting the resistance value to a voltage, a voltage / frequency conversion circuit for converting the voltage to a frequency signal having a pulse waveform, and the other side of the frequency signal having the pulse waveform in an electrical insulating portion. And a frequency / voltage conversion circuit for converting the transmitted frequency signal into a voltage, and a DC current supplied from a DC power supply for transmitting power from the other side of the transformer section to one side. Each transistor is turned on and off alternately for common
At least a switching circuit having a pair of switching transistors flowing to a load is provided, and the transmitted pulse waveform signal is separated from the DC current and detected.

In the above configuration, the resistance temperature detector, the bridge circuit, the amplifier circuit, and the voltage / frequency conversion circuit are incorporated in the rotating body, and the frequency / voltage conversion circuit and the switch are connected.
It is preferable that the switching circuit is incorporated in the fixed portion and the electrical insulating portion is a rotating transformer because the temperature of the rotating device can be accurately measured.

Further, in the above configuration, the switching circuit is connected as a common load between a pair of switching transistors to the switching circuit between the rotating transformer section on the fixed section side and the frequency / voltage conversion circuit. Providing a current shunt for detecting the received pulse waveform signal and a comparator for separating only the pulse waveform signal from the DC current and the pulse waveform signal detected by the current shunt, for accurate processing of the electric signal. preferable.

In the above configuration, it is preferable that the temperature detecting end is a platinum-based resistor because a temperature change can be converted into an electric signal in a linear relationship, and the temperature can be accurately measured.

[0012]

According to the configuration of the present invention described above, a temperature measuring resistor for converting a temperature to a resistance value, a bridge circuit and an amplifier circuit for converting the resistance value to a voltage, and converting the voltage to a frequency signal having a pulse waveform. A voltage / frequency conversion circuit for converting, a transformer section for transmitting the frequency signal of the pulse waveform to the other side by an electrical insulating section, a frequency / voltage conversion circuit for converting the transmitted frequency signal to a voltage, and the transformer In order to transmit power from the other side of the unit to one side, each transistor alternately conducts and blocks the DC current supplied from the DC power supply.
A pair of switching transistors that cut off and flow to a common load
A switching circuit having at least a switching circuit, and by detecting the transmitted pulse waveform signal separately from the DC current, the temperature can be accurately measured, the error is small,
Even when the temperature detecting device is attached to the heating device, it is possible to provide a temperature detecting device that does not require temperature correction for each device.

Further, a resistance temperature detector, a bridge circuit, an amplifier circuit, and a voltage / frequency conversion circuit are incorporated in a rotator unit, a frequency / voltage conversion circuit and a switching circuit are incorporated in a fixed unit, and an electrical insulation unit is provided. According to the preferred configuration of the rotating transformer, the temperature can be accurately measured when the present invention is applied to a rotating device.

A pair of switching circuits is provided between the rotating body transformer on the fixed part side and the frequency / voltage conversion circuit .
A shunt connected as a common load of a switching transistor and detecting the DC current and the received pulse waveform signal, and a comparator for separating only the pulse waveform signal from the DC current and the pulse waveform signal detected by the shunt Is provided, a more accurate electric signal corresponding to a change in temperature can be obtained.

Further, according to a preferred configuration in which the temperature detecting end is a platinum-based resistor, a temperature change can be converted into an electrical signal in a linear relationship, and the temperature can be accurately measured.

[0016]

The present invention will be described more specifically with reference to the following examples. The present invention is not construed as being limited to the following examples.

FIG. 1 shows an embodiment of the present invention. 3 denote the same members, and a description thereof will not be repeated. In this example, a platinum resistor is used for the temperature measuring resistor 1 in order to cope with the precise measurement of temperature, and 0-10 proportional to the temperature is used.
A voltage output of 10 V and a current output of 4 to 20 mA were obtained.

The resistance change of the resistance temperature detector 1A due to the temperature is as follows.
The voltage is directly converted into a voltage by a detection amplifier composed of a DC bridge 12 and a differential amplifier 7 in the same manner as a general non-rotating fixed body temperature measurement. This voltage is converted into a pulse having a frequency proportional to the voltage by a voltage frequency converter 13. The transistor 14 is turned on by this pulse, and a pulse current flows through the load 15.

At this time, on the primary side of the rotary transformer 2, the load on the secondary side becomes heavy only while the transistor 14 is conducting, so that the primary current increases. The increased primary current is detected by the shunt 19. This allows the fixed side 4 to receive a pulse transmitted by the rotating unit and having a frequency proportional to the measured value.

For this reason, the current converted into the voltage by the shunt 19 is detected only by the comparator 20 as a signal.
The waveform is shaped by the vibrator 21 and output to the converter unit 23 as a pulse current.

The pulse current input to the converter unit 23 is received by the photocoupler 24 and demodulated into a voltage by the frequency-voltage converter 25. This voltage is preferably set to 0 by the voltage amplifier 27 in accordance with the specifications of the controller and the like after the converter unit 23.
It is output as a signal proportional to the temperature of 4-20 mA by the -10 V, voltage-current converter 26.

On the other hand, the DC bridge 1 in the rotating side 3
2, the differential amplifier 7, a voltage-frequency converter 13, for supplying current to the DC reference voltage source 18, by providing the switching regulator IC22 the fixed side 4, the rotary transformer 2, rectifier 16, with the smoothing circuit 17, DC-D
It constitutes a C converter. The current from the power supply also flows through the shunt 19, but is separated from the signal by the comparator 20 described above.

Next, an example in which the temperature detecting device according to one embodiment of the present invention is attached to a rotating body will be described with reference to FIG. FIG. 2 is a sectional view in which a temperature detecting device is attached to a rotating roll.
In FIG. 2, 50 indicates the entire roll device, 51 is a metal roll main body, 52 is a temperature sensor insertion portion opened in the metal roll main body 51, 53 is a protective flange, 54 is a machine base, 55 is a bearing, and 56 is A hollow central shaft, 57 is a housing of the temperature detecting device, 58 is a fixed support, 59 is a bearing, 6
Reference numeral 0 denotes a coil portion having a core in the center and a coil wound therearound, and reference numeral 61 denotes an electric wire for supplying power to the coil portion 60. Reference numeral 62 denotes a measuring wire taken out of the fixing portion of the temperature detecting device.

The operation of the roll device 50 thus configured will be described below. The coil part 60 is integrated with the central shaft 56 and is fixed by a fixing support 58. The center shaft 56, the metal roll main body 51 and the protective flange 53 are rotatably supported by bearings 59. Therefore, the metal roll body 51 and the protective flange 53
Is rotated by an external power source.
0 and the central axis 56 are fixed. Further, the pressing force applied to the metal roll main body 51 is equal to the protection flange 53 and the machine base 5.
4 and is received by the machine base 54 via a bearing 55 between them. The AC power of, for example, 50 Hz or 60 Hz supplied from the power supply line 62
0, and an electromagnetic force is generated in the iron core in the coil unit 60. This electromagnetic force flows into the metal roll main body 51 and directly generates Joule heat in the metal roll main body itself, and at the same time, a low voltage and large current flows in the circumferential direction of the metal roll main body 51 due to the electromagnetic force. Joule heat is generated in the roll body itself.

The temperature sensing resistor 1A of FIG. 1 is inserted into the temperature sensor insertion portion 52. Then, the rotating side portion 3 and the fixed side portion 4 after the DC bridge circuit 12 are provided in the housing portion 57 of the temperature detecting device.

Next, the internal structure of the housing portion 57 of the temperature detecting device will be described with reference to FIG. In FIG. 3, reference numeral 31 denotes a connecting portion connected to the roll body. The connection may be made directly by using bolts or the like, or may be made by interposing a heat insulating material. A preferable connecting means is connected through a heat insulating material in order to shield an electronic circuit inside the temperature detecting device from heat. Next, 32 is a detection wire connected to the temperature sensor. The detection electric wire 32 is connected to a rotation-side electric circuit section 33, and the rotation-side electric circuit section 33 is connected to a rotation coil 35 wound around a rotation core 34. The electromagnetic force generated by the rotating core 34 is
The signal is received by the fixed core 37 and is extracted by the fixed coil 36 as an electric signal. Then, the electric signal is sent to the fixed-side electronic circuit unit 38, subjected to a predetermined process, and taken out of the measuring wire 62.

As described above, according to the present embodiment, there is provided an apparatus for detecting the temperature of an object having an electrically insulating portion (for example, the rotary transformer 2), wherein the bridge circuit (1, 12) for converting the temperature into a resistance value. ), An amplifier circuit (7, 18) for converting the resistance value into a voltage, and a voltage / frequency conversion circuit (13, 1) for converting the voltage into a frequency signal having a pulse waveform.
4, 15, 16, 17), a transformer section (2) for transmitting the electric signal to the other side through an electrical insulating section, and a frequency / voltage conversion circuit (19, 20, 21 and 22).

According to the above embodiment, the following effects can be obtained. (1) Since the rotating body has a power source, the sensor can be directly connected to the detection amplifier without using a rotating transformer.
Therefore, various sensors can be used by mounting a detection amplifier corresponding to the sensor. In this embodiment, since a platinum resistor can be used for the temperature sensor, the linearity of the electrical output signal (voltage) corresponding to the temperature is improved even if the temperature range is wider than that of the thermistor. Specifically, the conventional thermistor method generally has a temperature error of about ± 4 ° C. in a span of 100 ° C., but the method of the present embodiment has an accuracy of about ± 0.3 ° C. or less. Temperature can be detected. (2) The measured data enters the rotary transformer after being converted to a frequency, so that the rotary transformer only needs to be able to perform pulse transmission, and no temperature error is added by the rotary transformer. In addition, the number of turns of the coil winding is small, and the manufacture becomes easy. (3) By converting the measured value into a frequency, the signal sent to the converter unit becomes a pulse and is received by the photocoupler, so that it is resistant to noise and can be transmitted over a long distance. (4) Since the conversion accuracy of the temperature VS frequency input to the converter unit is high, correction in the converter unit is unnecessary. (5) Since the rotary transformer works as an insulating transformer, it has a function as an insulating amplifier for insulating the sensor side and the output side. For this reason, it is effective for measurement of a high voltage portion and noise resistance.

In the above embodiment, the temperature measurement is described using a platinum resistor. However, other temperature measuring resistors (eg, thermistors), thermocouples (K, R), temperature sensor ICs, semiconductors, and the like are used. However, it can be used by properly selecting a bridge circuit and an operation amplifier. Also,
Although the temperature measurement has been described in the above embodiment, the embodiment of the present invention is not limited to the temperature measurement, but may be any other measurement (for example, a measurement that can be taken out as an electric signal from a measurement sensor such as humidity, gas concentration, or detection of an object). ) Is also possible.

[0030]

As described above, according to the present invention,
A temperature measuring resistor for converting a temperature to a resistance value, a bridge circuit and an amplifier circuit for converting the resistance value to a voltage, a voltage / frequency conversion circuit for converting the voltage to a frequency signal of a pulse waveform, and By providing at least a transformer section for transmitting to the other side with an electrical insulating section, and a frequency / voltage conversion circuit for converting the transmitted frequency signal into a voltage, the temperature can be measured accurately, the error is small, and the heating device is provided. By using a temperature detector that does not require temperature correction for each unit, even if it is mounted on a heating unit, the temperature can be measured accurately and errors are small. A temperature detector that does not require correction can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram in which measured data according to one embodiment of the present invention is frequency-converted and then transmitted using a rotary transformer.

FIG. 2 is a cross-sectional view of an example in which the temperature detecting device according to one embodiment of the present invention is attached to a rotating body.

FIG. 3 is an enlarged partial cross-sectional view of an example in which the temperature detecting device according to one embodiment of the present invention is attached to a rotating body.

FIG. 4 is a block diagram showing an example in which a conventional rotary transformer is used as a coupling transformer of a sensor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1A, 1B RTD 2 Rotary transformer 3 Rotating side 4 Fixed side 5 Detection amplifier unit 6 AC bridge circuit 7 Differential amplifier 8 Synchronous rectifier 9 AC reference voltage source 10 Voltage output 11 Power input 12 DC bridge circuit 13 Voltage frequency conversion Unit 14 Transistor 15 Load 16 Rectifier 17 Smoothing circuit 18 DC reference voltage source 19 Current shunt 20 Comparator 21 Monostable multivibrator 22 Switching regulator IC 23 Converter unit 24 Photocoupler 25 Frequency voltage converter 26 Voltage current converter 27 Voltage amplifier 28 Current output

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01K 7/24 G08C 19/00

Claims (4)

(57) [Claims] 1. A temperature detecting device for an object having an electrically insulating portion, wherein the temperature measuring resistor converts a temperature into a resistance value.
A bridge circuit and an amplifier circuit for converting the resistance value to a voltage; a voltage / frequency conversion circuit for converting the voltage to a frequency signal of a pulse waveform; and transmitting the frequency signal of the pulse waveform to the other side by an electrical insulating unit. A transformer section, a frequency / voltage conversion circuit for converting the transmitted frequency signal into a voltage, and a DC current supplied from a DC power supply for transmitting power from the other side of the transformer section to one side .
A pair of transistors that alternately conduct and shut off and flow to a common load
A temperature detecting device comprising at least a switching circuit having the switching transistor of (1) , and detecting the transmitted pulse waveform signal separately from the DC current. 2. A temperature measuring resistor, a bridge circuit, an amplifier circuit, and a voltage / frequency conversion circuit are incorporated in a rotator unit, a frequency / voltage conversion circuit and a switching circuit are incorporated in a fixed unit, and an electrical insulation unit is provided. The temperature detecting device according to claim 1, wherein the temperature detecting device is a rotating transformer. 3. The rotating transformer section on the fixed section side and the frequency
A pair of switches is provided between the switching circuit and the voltage conversion circuit.
A shunt that is connected as a common load for the switching transistors and detects the DC current and the received pulse waveform signal, and a comparator that separates only the pulse waveform signal from the DC current and the pulse waveform signal detected by the shunt The temperature detection device according to claim 2, further comprising: 4. The temperature detecting device according to claim 1, wherein the temperature detecting end is a platinum-based resistor.