JPH064152A - Temperature controller - Google Patents

Abstract

PURPOSE:To provide a temperature controller which shares plural circuits for detection of the fault of a temperature sensor line, the detection of temperature, the generation of pulses, etc., for reduction of a necessary space and controls the temperatures of such electrical heating apparatuses as an electrical carpet, an electrical branket, etc. CONSTITUTION:A temperature controller contains a heater 1, a heater driving part 53, a temperature sensor line 2, a temperature detecting part 16, a pulse generating part 35, a temperature setting part 17, a deciding part 40, a contact state detecting part 46, a control part 30, and a security output part 52. In such a constitution, the output signals of the part 46 are detected at least for a period of 1/2 AC power supply cycle or longer at and after the fall or the rise of the pulse generated by the part 35. Then the drive output is applied to the part 52 so that an AC power supply and the heater 1 are cut off to both part 40 and 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for electric heating appliances such as electric carpets, electric stoves, and electric blankets.

[0002]

2. Description of the Related Art A conventional temperature control device of this type will be described with reference to FIGS. FIG. 5 is a plan view of an electric carpet using this type of temperature control device showing a conventional example. 1
Is a heater for heating and 2 is a temperature detection line for detecting the temperature of the heater 1, which is arranged substantially parallel to the main body 3 of the electric carpet. Reference numeral 4 is a controller for controlling the energization state of the carpet, and 5 is a cord with a plug for supplying power to the controller 4. Then, the temperature of the heater 1 is detected by the temperature detection line 2, and an electronic circuit built in the controller 4 controls the electric carpet to a desired temperature by the signal thereof.

FIG. 6 is a circuit diagram of an electric carpet using this type of temperature control device as a conventional example. The temperature detection line 2 is composed of a polymer temperature sensitive body 6 and an electrode wire 7 of which the resistance component and the capacitance component, that is, the impedance changes with temperature. When the temperature of the temperature detection line 2 is low, the impedance of the polymer temperature sensor 6 is high, and when the temperature is high, the impedance is low. FIG. 7 shows the temperature-impedance characteristic of the polymer temperature sensor 6 (temperature detection line 2). Therefore, when the temperature of the temperature detection line 6 is high, the temperature signal voltage V _T is high, and when the temperature is low, the temperature signal voltage V _T is low. The temperature-voltage characteristics of the polymer temperature sensor 6 (temperature detection line 2) are shown in FIG.

The polymer temperature sensor 6 has a drawback that its characteristics are deteriorated unless an AC voltage is applied, so that a negative cycle current path by the diode 10 is required. Therefore, current limiting resistor 8, capacitor 9, diode 1
0 connected in series with 0 and the negative cycle current I of the AC power supply 11
_- constitute a path to flow.

Diode 12, capacitor 13, resistor 1
The temperature detector 16 is configured by 4.15. AC power supply 1
The temperature signal voltage V _T is obtained by converting the current I ₊ flowing through the polymer temperature sensor 6 of the temperature detection line 2 into a voltage in the positive cycle of 1 and smoothing it.

The temperature setting unit 17 includes a volume 18 and a resistor 1.
9 and obtains the voltage (temperature setting voltage V _S ) at the connection point between the volume 18 and the resistor 19. The temperature setting voltage V _S is input to the voltage comparator 20.

The temperature setting voltage V _S and the temperature signal voltage V _T
When the temperature of the temperature detection line 2 is lower than the desired set temperature by comparing
_T <V _S ), the output of the determination unit 40 is made high, and a base current is supplied from the DC power supply V _CC to the transistor 22 through the resistor 21 to turn on the transistor 22. And
A current is passed through the coil of the relay 23 connected to the collector of the transistor 22 to turn on the contact of the relay 23 to energize the heater 1.

Reference numeral 24 is a diode for producing a power source for driving the relay 23, 25 is a smoothing capacitor, and 26 is a diode for absorbing a back electromotive force generated in the coil of the relay 23. The heater driving unit 53 includes the relay 23 to the diode 26.

Here, the current I ₊ flowing through the temperature detection line 2
If the path of the open circuit fails (for example, diode 1
2 has an open failure), V _T = 0, V _T <V _S regardless of the temperature of the temperature detection line 2, and the heater 1 is always energized, so that the heater 1 is abnormally heated and is in a dangerous state.
Therefore, by supplying the voltage at the connection point between the resistors 14 and 15 to the base of the transistor 27,
When is off, a current is supplied from the DC voltage V _CC to the base of the transistor 29 through the resistor 28 to turn on the transistor 29 and turn off the transistor 22. Therefore, at this time, the relay 23 is turned off regardless of the output of the voltage comparator 20, and the power supply to the heater 1 is stopped. Transistor 2
When 7 is on, the transistor 29 is off and the output of the voltage comparator 20 controls the energization of the heater 1 to prevent abnormal heating of the heater 1. The control unit 30 uses the voltage comparator 20.
~ It is composed of a transistor 29.

Further, in the negative cycle of the AC power supply 11, the temperature
Current I flowing through the degree detection line 2_-Diode out of the path
Even if 10 has an open failure, I₊
= I _-, I_-= 0 to I₊= 0 and V_T= 0.
Therefore I₊Open the path of the
Prevents abnormal overheating of switch 1.

31 and 33 are resistors, 32 is a diode, 3
Reference numeral 4 is a transistor, which constitutes a pulse generator 35. FIG. 9 shows the waveform of the AC power supply 11 and the output waveform V _P of the pulse generator 35, and V _P is a pulse synchronized with the AC power supply 11.

Resistors 43, 45, 47 and transistor 44
The contact state detector 46 is configured by. When the contact of the relay 23 is closed, the transistor 44 is turned on via the resistor 45, and the output V _ST of the contact state detection unit 46 becomes a pulse. The resistor 47 is a base-emitter resistor of the transistor 44. When the contact of the relay 23 is open, the transistor 44 is turned off and _VST becomes high, so that it is no longer a pulse. That is, by inputting the presence or absence of the pulse output of the output V _ST of the contact state detection unit 46 to the determination unit 40, the relay 2
The open / closed state of the contact 3 can be determined. The logic is inverted depending on the circuit configuration of the contact state detection unit 46 and the configuration of the contact between the heater 1 and the relay 23. When the contact of the relay 23 is open, a pulse is generated and the contact of the relay 23 is closed. When it is present, the pulse disappears, and the determination unit 40 can detect the state of the contact of the relay 23.

The detection of the open / closed state of the contact of the relay 23 is carried out after a lapse of a fixed time from the fall of the pulse of the pulse generator 35 (when the pulse of the pulse generator 35 changes from high to low). When the output V _ST of 46 is detected and the state of the contact of the relay 23 is high when it is high, it is considered that the state of the contact of the relay 23 is open, and when the low is detected, the contact of the relay 23 is considered to be closed. Further, the AC power supply waveform of FIG. 9, the output waveform V _P of the pulse generator 35 and the output waveform V of the contact state detector 46
_As can be seen from the characteristic diagram of _ST , the state of the contact of the relay 23 can be determined by the output signal of the contact state detection unit 46.

Further, since the pulse generator 35 is provided for detecting the open / closed state of the contact of the relay 23, the circuit configuration is increased.

[0015]

In such a conventional configuration, there are provided a plurality of circuits such as a circuit for detecting an open failure of the temperature detecting line 2, the temperature detecting section 16 and the pulse generating section 35. This is a very important issue in the present day when small size is required and cost competition is fierce.

It is an object of the present invention to provide a temperature control device which realizes inexpensive and small-sized space-saving mounting by reducing the circuit configuration while maintaining the conventional functions, and which does not cause unsafe operation. Is.

[0017]

In order to achieve the above object, the present invention is directed to a heater, a heater driving unit for driving the heater, and a polymer sensor whose impedance changes according to the temperature thermally coupled to the heater. Synchronized with an AC power supply by a temperature detection line composed of a warm body, a temperature detection unit that converts a current flowing in a negative cycle of an AC power supply into the temperature detection line into a voltage, and a current flowing in a positive cycle of the AC power supply in the temperature detection line A pulse generator that generates a pulse, a temperature setting unit that sets the heater to a desired temperature, and the detected temperature is higher than the set temperature by comparing the set temperature of the temperature setting unit and the detected temperature of the temperature detecting unit. A determination unit that turns on the heater driving unit when the temperature is low, and a contact state detection unit that generates a pulse in which one of ON and OFF of the heater driving unit generates a pulse synchronized with an AC power source, The output signal of the contact state detection unit is detected for at least ½ of the AC power supply cycle from the falling or rising of the pulse generated from the pulse generation unit, and the signal of the determination unit and the contact state detection unit are detected. It is composed of a control unit that outputs a drive from a signal to a safety output unit that shuts off the AC power source and the heater.

[0018]

According to the present invention, the output V _ST of the contact state detection unit is detected from the trailing edge of the pulse of the pulse generation unit for a period of ½ or more of the AC power supply cycle, and when the output does not become low within this period. The state of the relay contact is considered to be open, and when a low is detected within this period, the relay contact is considered to be closed. With this, the state of the relay contact can be detected, and if there is a difference from the output signal of the judgment unit, the control unit outputs a drive output to the safety output unit and unsafe operation such as abnormal heat generation / ignition caused by temperature control failure To avoid.

[0019]

1 is a circuit block diagram of an electric carpet using a temperature control device according to an embodiment of the present invention. Figure 2
3 are the same as those in FIG. 3, and therefore the description thereof is omitted.

The temperature detecting section 16 includes a transistor 36 and a resistor.
37 and a capacitor 38. And the exchange
During the negative cycle of current source 11, AC power source 11 →
Base of transistor 36 → emitter of transistor 36 → resistance
Anti-8 → temperature detection line 2 → current I in the path of AC power supply 11_-But
Flowing. The base of the collector of the transistor 36
Since the same current as the flowing current flows, I_-But
Flowing. Then, the capacitor 38 smooths this and voltage
Convert to. Polymer temperature sensor constituting the temperature detection line 2
6 is low impedance at high temperature and high at low temperature according to temperature
At high temperature to show impedance I_-Is large and low at low temperature
Sai. I corresponding to the temperature of the temperature detection line 2 _-Can change
The current flowing from and to the resistor 37, that is, I_-Smoothed electric
Pressure V_rIs the temperature signal voltage corresponding to the temperature of the temperature detection line 2
Become.

The temperature setting unit 17 is a volume, and the temperature setting voltage V _S set by the volume 17 is input to the A / D converter 39.

The temperature signal voltage V _T output from the temperature detector 16 is input to the A / D converter 39, and the temperature set value (the value obtained by A / D converting the temperature set voltage V _S by the A / D converter 39). )
And the temperature detection value (value obtained by A / D converting the temperature setting voltage V _T by the A / D converter 39) are compared in the judging section 40, and when the detection temperature is lower than the desired setting temperature (V _T > V _S ). The transistor 22 is turned on and the relay 23 is turned on to energize the heater 1. The control unit 30 includes the A / D converter 39 and the determination unit 4
It consists of zero.

The pulse generator 35 comprises a resistor 41 and a transistor 42. In the positive cycle of the AC power supply 11, a current flows through the path of the AC power supply 11 → temperature detection line 2 → resistor 8 → base of the transistor 42 → emitter of the transistor 42 → AC power supply 11 to turn on the transistor 42. In the negative cycle, the transistor 42 is turned off.
Therefore, the pulse output V _P is generated.

When a failure such as an open current path in the positive cycle of the temperature detection line 2 occurs, the output V _P of the pulse generator 35 becomes high and the pulse is no longer a pulse. That is, by inputting the presence / absence of the pulse output of the output V _P of the pulse generator 35 to the determiner 40, the failure of the current path can be determined,
At that time, the transistor 2 is used regardless of the relationship between V _T and V _S.
2 is turned off to stop energizing the heater 1.

The contact state detector 46 is composed of resistors 43 and 45 and a transistor 44. When the setting of the relay 23 is closed, the transistor 44 is turned on via the resistor 48 through the resistor 45, and the output V _ST of the contact state detection unit 46 becomes a pulse. The resistor 47 is a base-emitter resistor of the transistor 44. When the contact of the relay 23 is open / closed, the transistor 44 is turned off and _VST becomes high, so that it is no longer a pulse. That is, the open / closed state of the contact of the relay 23 can be determined by inputting the presence / absence of the pulse output of the output V _ST of the contact state detection unit 46 into the determination unit 40. It is also possible to reverse the logic of the open / closed state of the contacts of the relay 23 by the circuit configuration similar to the above.

The safety output section 52 is composed of a resistor 48, a thyristor 49, a capacitor 50 for preventing noise of the thyristor 49, and a resistor 51. In the current path in the positive cycle from the AC power supply 11, when a low is output from the determination unit 40, no current flows to the gate of the thyristor 49, and the AC power supply 11 → contact of the relay 23 → resistor 48 → resistor 45 → A current flows through the path from the resistor 47 to the AC power supply 11.
In addition, when a high output is made from the determination unit 40, a current flows to the gate of the thyristor 49 and the thyristor 49 is turned on. Therefore, the current is the AC power supply 11 → the resistor 48 → the anode of the thyristor 49 → the cathode of the thyristor 49 → the AC power supply. It flows on the route of 11. At this time, the resistance 48 is changed to the resistance 45.4.
If it is made sufficiently smaller than 7, the current flowing through the resistor 48 becomes large and heat is generated, and the thermal fuse 54 is melted and blown off.
Disconnect the circuit from.

FIG. 2 shows the temperature-voltage characteristics of the polymer temperature sensor 6 (temperature detection line 2) of the embodiment. In the present embodiment, since the temperature signal voltage is changed by using the negative cycle current of the AC power supply, the characteristic is that the voltage is high at low temperature and low at high temperature, contrary to the conventional example. The temperature-impedance characteristics of the polymer temperature sensor (temperature detection line) are the same as those in FIG.

FIG. 3 shows the AC power supply waveform and the output waveforms of the pulse generator and the contact state detector of this embodiment. This indicates that the current flowing through the temperature detection line 2 constitutes the pulse generating section, and therefore the phase of the AC power supply deviates due to the capacitance of the temperature detection line 2 (polymer temperature sensor 6). Pulse generator 3
5 and the phase difference of AC power supply is 1 / of the maximum AC power supply cycle
It is 2 or less. Output V _ST of the contact state detector is AC power supply 1
The pulse is synchronized with 1.

When the presence / absence of a pulse of the output V _ST of the contact state detecting unit 46 for detecting the state of the contact of the relay 23 is detected by the judging unit 40, the output V _P of the pulse generating unit 42 and the contact state detecting unit 46 are detected. since the outside phase of the output V _ST, going pulse edge of the pulse generator 35 of the AC power supply period of the output V _ST of (pulse generator 35 of the pulse high → when a row) from the contact state detector 46 1 / When two or more periods are detected, and the state of the contact of the relay 23 is not open within this period, it is considered that the contact of the relay 23 is open, and when the low is detected within this period, the contact of the relay 23 is considered open. FIG. 4 shows characteristics of the output V _ST of the contact state detector 46 and the state of the contact of the relay 23.

The temperature detection unit 16 and the temperature setting unit 17 are A / D
When the state of the contact of the relay 23 by the contact state detection unit 46 differs from the result of the comparison determination of the determination unit 40 after A / D conversion by the converter 39, that is, the detected temperature> the set temperature ( _VT <
When the contact of the relay 23 is open at V _S ), or when the contact of the relay 23 is closed at the detected temperature <set temperature (V _T > V _S ), welding failure of the contact of the relay 23,
Alternatively, the contact is broken due to the disconnection of the coil of the relay 23, and the temperature control is not based on the temperature comparison. Therefore, a high output is output from the determination unit 40, the thyristor 49 is turned on, and the temperature fuse 54 is melted through the resistor 48 to cause the AC power supply 11
Disconnect the circuit from.

[0031]

As is apparent from the above embodiments, the structure of the present invention has the following effects. (1) More space-saving mounting can be realized by sharing a plurality of circuits such as a circuit that detects an open failure of the temperature detection line, the temperature detection unit, and the pulse generation unit. (2) The contact state of the relay can be detected even when there is a phase shift between the AC power supply and the pulse generator in the above configuration by detecting the state of the contact of the relay for a period of 1/2 or more of the AC power supply cycle. It is possible to avoid unsafe operation such as abnormal heat generation and ignition due to temperature control failure due to contact opening / welding.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an electric carpet using a temperature control device according to an embodiment of the present invention.

FIG. 2 is a temperature-voltage characteristic diagram of a polymer temperature sensor (temperature detection line) in the temperature control device.

FIG. 3 is a diagram of an AC voltage waveform, a pulse output waveform of a pulse generator and an output waveform of a contact state detector in the temperature control device.

FIG. 4 is an AC voltage waveform, a pulse output waveform of a pulse generator, and an output waveform of a contact state detector when the relay contact is opened / closed in the temperature control device.

FIG. 5 is a plan view of an electric carpet using a conventional temperature control device.

FIG. 6 is a circuit block diagram of an electric carpet using a conventional temperature control device.

FIG. 7: Temperature-impedance characteristic diagram of polymer temperature sensor (temperature detection line)

FIG. 8 is a temperature-voltage characteristic diagram of a polymer temperature sensor (temperature detection line) in a conventional temperature control device.

FIG. 9 is a pulse output waveform diagram of an AC voltage waveform and a pulse generator in a conventional temperature control device.

[Explanation of symbols]

 1 Heater 2 Temperature Detection Line 11 AC Power Supply 16 Temperature Detection Section 17 Temperature Setting Section 30 Control Section 35 Pulse Generation Section 39 A / D Converter 40 Judgment Section 46 Contact Status Detection Section 52 Safety Output Section 53 Heater Drive Section 54 Thermal Fuse

Claims (1)

[Claims] 1. A heater, a heater driving unit for driving the heater, a temperature detection line made of a polymer temperature sensor whose impedance changes according to a temperature thermally coupled to the heater, and an alternating current to the temperature detection line. A temperature detecting unit for converting a current flowing in a negative cycle of a power supply into a voltage, a pulse generating unit for generating a pulse in the temperature detection line in synchronization with an AC power supply by a current flowing in a positive cycle of an AC power supply, and the heater as desired. A temperature setting unit that sets the temperature, a determination unit that compares the set temperature of the temperature setting unit and the detected temperature of the temperature detection unit, and turns on the heater driving unit when the detected temperature is lower than the set temperature; A contact state detection unit that generates a pulse in which either one of the heater driving unit is turned on or off is synchronized with the AC power supply, and the trailing edge of the pulse generated from the pulse generation unit. Security for detecting the output signal of the contact state detection unit for at least ½ of the AC power supply cycle from the rise, and disconnecting the AC power supply and the heater from the signal of the determination unit and the signal of the contact state detection unit A temperature control device comprising a control unit for performing drive output to an output unit.