JPH06332546A - Temperature controller - Google Patents

Abstract

PURPOSE:To provide a temperature controller of a simple constitution which can control the temperature with high accuracy and high stability without receiving any effect of the voltage variance of an AC power supply and regardless of the dimentional accuracy of the heat-sensitive layer of a temperature measuring element and furthermore can stop the energization of a heater when the temperature measuring element and the parts have the faults. CONSTITUTION:The voltage of an AC power supply 1 is divided and applied to a transistor TR 7, and the phase difference between the AC voltage applied to a temperature measuring element and the current flowing to this element is calculated as the output of the TR 7 in each cycle of the power supply 1. Then, the output of the TR 7 is used as a temperature measuring signal and a temperature control means of the following stage controls the temperature of a heater regardless of the voltage variance of the power supply 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the phase difference of a temperature measuring element to control the temperature.

[0002]

2. Description of the Related Art As an example of an apparatus for detecting a phase difference between a voltage applied to a temperature measuring element and a current flowing through the temperature measuring element as a temperature signal and controlling a heater temperature, Japanese Patent Application Laid-Open No. 3-77036 and Japanese Patent Application Laid-Open No. 3-77036 are disclosed. The technique disclosed in Japanese Patent Laid-Open No. 4-190581 is known.

[0003]

SUMMARY OF THE INVENTION In the above conventional technique,
The zero point of the voltage applied to the temperature measuring element and the zero point of the current flowing through it are detected, and the temperature of these two zero points is measured to obtain the temperature measurement signal and control the heater temperature. Therefore, the drawback that the configuration is complicated as a whole,
There is a problem that safety measures have not been taken against failures such as disconnection and short circuit of component parts.

The present invention provides a device capable of controlling the temperature with high accuracy regardless of the dimensional accuracy of the thermosensitive layer of the temperature measuring element with an extremely simple structure, and further stops energizing the heater when the temperature measuring element is broken or short-circuited. The purpose is to provide a device.

Another object of the present invention is to detect the phase difference of the temperature measuring element for each cycle of the AC power supply and use this as a temperature measuring signal to stabilize the heater temperature without being affected by the voltage fluctuation of the AC power supply. The purpose of the present invention is to provide a device that can be controlled.

Still another object of the present invention is to provide a device for stopping the energization of the heater when a component or the like constituting the device fails.

[0007]

In order to achieve the above-mentioned object, the present invention divides the voltage of an AC power supply and applies the voltage to a transistor to determine the level of the AC voltage applied to the temperature measuring element and the current flowing through it. The phase difference is obtained as a temperature measurement signal from the collector of the transistor, the temperature measurement signal is used as an anode input of a PUT (programmable unijunction transistor, hereinafter abbreviated), and the gate voltage of the PUT divides the voltage applied to the transistor. It is assumed that the pressure is applied, and the energization to the heater is controlled by the control means that operates corresponding to the cathode output of the PUT.

The control means drives the relay by the on / off operation of the thyristor which operates by the cathode output of the PUT, the relay is not turned on due to the disconnection or short circuit failure of the preceding component of the thyristor, and the temperature measuring element is In the case of a heat-sensitive wire, even if any part of the inner and outer conductors of the heat-sensitive wire is broken or short-circuited, the heater is de-energized, and a detection conductor is provided on the heater through a melting layer, and the detection conductor contacts the heater. Then, the circuit configuration is such that the power supply to the heater is cut off.

[0009]

When a positive half-wave current flows through the temperature measuring element, a base current flows through the transistor, and when a negative half wave is applied to the temperature measuring element, a voltage equivalent to the AC power source is applied to the collector of the transistor. A time width corresponding to the phase difference corresponding to the temperature of the temperature measuring element is obtained for each cycle on the collector side of the transistor regardless of the dimensional accuracy of the heat sensitive layer. When the temperature measuring element is broken, the base of the transistor does not conduct, and when the temperature measuring element is short-circuited, the phase difference becomes zero and the collector output of the transistor cannot be obtained. Do not close the heater circuit.

The voltage fluctuation of the AC power supply causes the collector voltage of the transistor, that is, the anode input of the PUT, but the gate voltage of the PUT also changes corresponding to the voltage fluctuation of the AC power supply, so that the PUT output is kept constant. The heater temperature stabilizes. Further, if any of the components in the preceding stage of the thyristor fails and the thyristor does not repeatedly turn on and off, the relay that opens and closes the heater circuit will not turn on, and the power supply to the heater will stop.

[0011]

1 shows a basic circuit diagram of the device of the present invention, in which a temperature fuse 2, a heater 3 and a thyristor 4 are connected in series to an AC power source 1 to form a heater circuit. The heater 3 is provided with a conductor 6 via a heat sensitive layer 5 whose phase angle changes according to temperature, and the conductor 6 is connected to the base of a transistor 7. Further, resistors 8 and 9 are connected in series to the power source 1, the emitter of the transistor 7 is connected to the connection portion of the resistance heaters 8 and 9, and the base of the transistor 7
A diode 10 is connected in parallel with the opposite polarity between the emitters.

A diode 11, a resistor 12, a variable resistor 13 and a resistor 14 are provided on the collector of the transistor 7 and the power source 1b side.
However, the resistor 1 is connected to the connection of the resistors 8 and 9 and the power source 1b side.
5 and the diode 16 are respectively connected in series. The slider of the variable resistor 13 is connected to the capacitor 18 in series with the PUT 22.
Of the diode 1 is connected to the anode side of the
9 and the resistor 20 are cascade-connected. PUT22
The gate of is connected to the cathode side of the diode 16 via a resistor 23 connected in series, and the cathode of the PUT 22 is connected to the resistor 24 connected in cascade and the gate of the thyristor 4. Further, a heating resistor 25 and a diode 26 connected in series are connected in parallel to the heater 3, and the resistor 25 is in contact with the thermal fuse 2.

FIG. 3 shows the voltage v applied across the heat-sensitive layer 5.
And a waveform of a current i flowing through it (indicated by a sine wave for explanation), the current i is a positive half-wave (time t1 to t3, t5 to t5).
During t7), a base current flows through the transistor 7 in the circuit of the conductor 6 to the base of the transistor 7 to the emitter to the resistor 9 while the voltage v is a negative half wave (time ... t2, t4).
(Between t6 and t6), the diode 11 is turned on and a negative voltage is applied to the collector of the transistor 7, and the collector current IC of the transistor 7 becomes zero between the zero point t1 of the current i and the voltage v, as shown in FIG. Between zero points t2 (similarly, the next time t
Flows between 5 and t6). The section in which the collector current IC flows corresponds to the phase difference φ between the voltage applied to the heat sensitive layer 5 and the flowing current in a ratio of 1: 1, and the detection of the phase difference φ changes according to the temperature. Corresponds to the phase angle φ of.

This collector current IC is supplied to the power source 1b side to the diode 19 to the capacitor 18 to the variable resistor 13 to the resistor 1.
2-diode 11-transistor 7-resistor 8-power supply 1
It flows through the path on the side a, and the capacitor 18 is charged with the polarity shown in FIG. When the voltage v becomes a positive half-wave, the collector current stops flowing, and the electric charge charged in the capacitor 18 is discharged via the resistors 20 to 14 to the variable resistor 13.

At this time, the charging voltage VA of the capacitor 18
Is higher than the gate voltage vg of PUT, the cathode of PUT 22 becomes conductive (output VK shown in FIG. 6), and capacitor 1
The electric charge of 8 is discharged through the path of PUT22-thyristor 4-resistor 14-variable resistor 13 to trigger thyristor 4,
A half wave of the AC power supply 1 is applied to the heater 3. The voltage charged in the capacitor 18 is the temperature of the heat sensitive layer 5 and the variable resistor 13
The temperature of the heater 3 can be maintained at a predetermined temperature by adjusting the temperature of the heater 3.

Under the influence of the voltage fluctuation of the power source 1, the PUT 2
Although the anode voltage VA of 2 is not stable, the voltage of the power source 1 is divided by the resistors 8 and 9 and the voltage smoothed by the capacitor 17 is P.
Since it is applied to the gate of UT22, PUT2
The cathode output of 2 is stable regardless of the fluctuation of the voltage of the power supply 1.

When the conductor 6 comes into contact with the heater 3 due to melting of the heat-sensitive layer 5 due to an abnormally high temperature, the phase difference φ becomes zero, the capacitor 18 is not charged, and the PUT 22 to the thyristor 4 are connected.
Is kept off and the heater 3 is not energized. At this time, the charging voltage of the capacitor 17 rises at the same time, so P
The operating point of the UT22 also rises, and the operation of the PUT22 shifts to a safer side.

When the conductor 6 and the transistor 7 are disconnected and the temperature signal of the thermosensitive layer 5 is not transmitted, the transistor 7 does not conduct and the capacitor 18 is not charged.
Similarly to the above, the heater 3 is not energized. When the thyristor 4 fails to turn on, a half wave of the power source 1 flows from the diode 26 to the heat-generating resistor 25 to generate heat in the resistor 25, which causes the thermal fuse 2 to be disconnected and the heater 3 to be energized. cut off.

When the phase angle φ of the heat sensitive layer 5 becomes small on the high temperature side as shown in FIG. 7, the PUT 22 to the thyristor 4 are provided.
Since the capacitor 18 is not charged with a necessary amount of electric charge for triggering, the heater 3 cannot be set to a high temperature. Therefore, if the present device is applied to, for example, an electric blanket or the like, the temperature does not rise to a level that poses a danger to the body.

In FIG. 2, a thermosensitive wire 27 is used as a temperature measuring element in the vicinity of the heater 3, a detection conductor 29 is arranged in the heater 3 through a melting layer 28, and a relay 30 is provided as a control element of the heater 3 circuit. The relay 30 is connected in series with the power source 1 together with the diode 31, the resistor 32, and the capacitor 33, and the capacitor 34 is connected in parallel with the relay 30, and the anode side of the thyristor 4 is the diode 31. Connected to the cathode side of. still,
A heat sensitive sheet may be used instead of the heat sensitive wire 27.

The resistor 8 connected to the power source 1a side in FIG.
In FIG. 2, the heat-sensitive wire 27 is connected to one end of the primary conductor 5a, and the other end of the primary conductor 5a is connected to the power supply 1a side. Also,
One end of the secondary conductor 5b of the heat-sensitive wire 27 is connected to the base of the transistor 7, and the other end of the secondary conductor 5b is connected in series with the diode 35 to the resistor 8
It is connected to the other end. An emitter-base of another transistor 36 is interposed between the other end of the resistor 8 and the diode 10, and a diode 37 and two resistors 38 and 39 are connected in series on the collector of the transistor 36 and the power source 1a side. There is. A heat generating resistor 40 connected in series and another thyristor 41 are connected to the power source 1, and the gate of the thyristor 41 is connected between the resistors 38 and 39. The heating resistor 40 is brought into contact with the thermal fuse 2.

Further, the power supply 1 has two diodes 42, 4
3 is connected in reverse polarity, and a short-circuit detection circuit 44 is provided between the connection portion of the diodes 42 and 43 and the detection conductor 29. The circuit 44 comprises a series-connected photocoupler projecting side 45, a resistor 47 and a capacitor 48 connected in parallel, and a photocoupler receiving side 46 is connected between the emitter and collector of the transistor 36.

In the structure shown in FIG. 2, first, the relay 30
The operation of the parts will be described in detail. When the power supply 1 is applied, the capacitor 34, the relay 30, the diode 31 and the resistor 3 are negative half-waves.
A current flows through the route 2 to charge the capacitor 33, and after the charging, no current flows and the relay 30 is turned off.
When the thyristor 4 conducts every positive half-wave, the capacitor 3
The electric charge of 3 is discharged each time, and a current flows through the same path as above in the next negative half wave, so that the relay 30 is turned on, the relay contact 30a is closed, and the heater 3 generates heat.

Unless the thyristor 4 is repeatedly turned on and off, the electric charge of the capacitor 33 is not discharged, so the relay 30
Does not turn on. Therefore, when any of the parts preceding the thyristor 4 is broken or short-circuited, the thyristor does not turn on / off and the relay 30 does not turn on. When the thyristor 4 or the diode 31 is short-circuited, the capacitor 33 and / or the capacitor 34 is damaged and the relay 30 is not turned on. When the resistor 32 is short-circuited, the balance of the power supply for the relay is lost, the relay 30 flickers, the thyristor 4 is damaged, and the relay 30 does not turn on.

Explaining the disconnection of the heat-sensitive wire 27 in detail, when the primary conductor 5a is disconnected, the resistor 8 is disconnected from the power supply 1a, the transistor 7 does not operate, and the thyristor 4 does not turn on. When the secondary conductor 5b is normal, the threshold voltage of the diode 35 is lower than the sum of the emitter-base threshold voltage of the transistor 36 and the threshold voltage of the diode 10, so that the transistor 36 does not turn on, but the secondary conductor 5b. 2 is disconnected in the upper part of FIG. 2, the cathode side of the diode 35 is disconnected and the transistor 3
6 is turned on, a current flows through the thyristor 41, the resistor 40 generates heat, and the thermal fuse 2 is melted and the power supply to the heater 3 is cut off. When the secondary conductor 5b is broken in the lower part of FIG. 2, the absolute value of the impedance of the remaining part becomes large, so that a base current sufficient to operate the transistor 7 does not flow and the thyristor 4 does not turn on.

Further, when the melting layer 28 is melted due to abnormal overheating of the heater 3 and the heater 3 comes into contact with the detection conductor 29, the capacitor 48 is charged and the photocouplers 45 to 46 operate, and the thyristor 41 causes the negative voltage of the power source 1. Conducting with a half wave, a current flows through the resistor 40, and the power supply to the heater 3 is cut off as described above.

[0027]

As described above, according to the present invention, the phase difference of the temperature measuring element is detected as a temperature measuring signal, and the temperature is controlled by using this signal. Since the temperature control can be performed without using it, and the phase difference detection and control are performed by applying a low voltage by dividing the AC power supply, the entire apparatus can be provided at a small size and at low cost. Further, when the temperature measuring element is disconnected or short-circuited or the component is broken, the heater is de-energized so that the heater is not overheated and can be used with confidence. Further, since the phase difference of the temperature measuring element is detected for each cycle of the power source and the operation of the control element is compensated for in response to the voltage fluctuation of the power source, the temperature control of the heater becomes stable.

[Brief description of drawings]

FIG. 1 is a basic circuit diagram of a temperature control device according to the present invention.

FIG. 2 is a circuit diagram of a temperature control device according to another embodiment of the present invention.

FIG. 3 is a waveform diagram of a voltage applied to the temperature measuring element and a current flowing through the temperature measuring element.

FIG. 4 is a waveform diagram of a collector current of a transistor 7.

5 is a voltage waveform diagram at a point VA in FIG.

FIG. 6 is a voltage waveform diagram at a VK point in FIG.

FIG. 7 is an example diagram of temperature-phase angle characteristics of a temperature measuring element.

[Explanation of symbols]

1 AC Power Supply 2 Temperature Fuse 3 Heater 4 Thyristor 5 Thermosensitive Layer 6 Conductor 7 Transistor 8, 9, 12, 14, 15, 20, 21, 23, 24
Resistance 10, 11, 16, 19, 26 Diode 17, 18 Capacitor 22 PUT 25 Heat generation resistance

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[Procedure amendment]

[Submission date] August 3, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

Another object of the present invention is to detect the phase difference of the temperature measuring element for each cycle of the AC power source and use this as a temperature measuring signal to stabilize the heater temperature without being affected by the voltage fluctuation of the AC power source. It is the provision of a device that can be controlled .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Still another object of the present invention is to provide a device for stopping the power supply to the heater when a component or the like constituting the device fails .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

Embodiment FIG. 1 shows a basic circuit diagram of the device of the present invention,
The AC power source 1 has a temperature fuse 2, a heater 3, and a thyristor 4.
Are connected in series to form a heater circuit. Heater 3
Is provided with a conductor 6 via a thermosensitive layer 5 whose phase angle changes according to temperature, and the conductor 6 is connected to the base of a transistor 7. Further, resistors 8 and 9 are connected in series to the power source 1, and the emitter of the transistor 7 has both resistors 8 and 9.
A diode 10 is connected in reverse polarity between the base and the emitter of the transistor 7 in parallel.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

A diode 11, a resistor 12, a variable resistor 13, and a resistor 1 are provided on the collector side of the transistor 7 and the power source 1b side.
4 are connected in series, also connection and the power source 1b resistance to side 15 of the resistor 8 and 9, the diode 16, the capacitor 1
7 are connected in series . The mover of the variable resistor 13 is connected to the anode of PUT22 in series with a capacitor 18, to the anode side diode 19 and the resistor 20 are connected in cascade. The gate of the PUT 22 is connected to the cathode side of the diode 16 via the series-connected resistor 23, and the cathode of the PUT 22 is connected to the cascade-connected resistor 24 and the gate of the thyristor 4. Further, a heating resistor 25 and a diode 26 connected in series are connected in parallel to the heater 3, and the resistor 25 is in contact with the thermal fuse 2.

Claims (4)

[Claims] 1. A voltage of an AC power source is divided and applied to a transistor, and a phase difference between an AC voltage applied to a temperature measuring element and a current flowing therein is obtained from a collector of the transistor as a temperature measuring signal. The temperature signal is used as the anode input of the PUT, the gate voltage of the PUT is obtained by dividing the voltage applied to the transistor, and the energization of the heater is controlled by the control means that operates corresponding to the cathode output of the PUT. The temperature control device characterized in that 2. The temperature control device according to claim 1, wherein the control means drives the relay by an on / off operation of the thyristor, and the relay is not turned on due to a disconnection or a short circuit failure of a preceding component of the thyristor. 3. The temperature control device according to claim 1, wherein the temperature measuring element is a heat-sensitive wire, and the heater is energized no matter where each conductor of the heat-sensitive wire is broken or short-circuited. 4. The temperature control device according to claim 1, wherein the heater is provided with a detection conductor via a melting layer, and when the detection conductor comes into contact with the heater, the power supply to the heater is cut off.