JP2554655Y2 - air conditioner - 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 control circuit (regulator) used for controlling the temperature of an electric carpet, an electric heating mat or the like.

[0002]

2. Description of the Related Art Conventionally, there are various types of temperature controllers used for temperature control of electric carpets and the like. For example, there is a temperature controller as shown in FIG. This temperature controller utilizes a temperature sensor (plastic thermistor) A whose resistance value fluctuates in accordance with the surrounding temperature. Several volts to several tens of volts are applied to the plastic thermistor A arranged near the heater wire B of the electric carpet. And a half-wave rectifier circuit C from the AC current flowing through the thermistor A.
To extract the positive or negative branch current, and compare the voltage of the positive or negative branch current with the reference voltage of the temperature setting output circuit E by the voltage comparator D. For example, when the voltage of the branch current is higher than the reference voltage ( When the temperature of the heater wire B is in an excessively high temperature state), an off signal is output from the voltage comparator D to the heater load ON / OFF device F, and the switch G of the heater wire B in the ON state is turned off. And the current stops flowing through the heater wire B, and the temperature of the carpet decreases. When the temperature drops to some extent, the resistance value of the plastic thermistor A rises and the current flowing through it decreases, and when the voltage input to the voltage comparator D becomes lower than the reference voltage, the heater load is turned on based on the output from the comparator D. /
A signal for turning on the switch G is output from the OFF device F, and the heater wire B resumes heating. This keeps the carpet at a constant temperature.

The temperature controller shown in FIG.
There is also an overheating prevention function for preventing the heater wire B from staying ON due to a failure of the N / OFF device F and abnormally increasing the temperature. This is because the voltage of the branch current obtained by the half-wave rectifier circuit C is compared in another voltage comparator I with the reference voltage of the overheat discrimination output circuit H, and the heater wire B is set to a predetermined upper limit temperature. The voltage of the branch current
When the reference voltage is reached, a signal is output from the voltage comparator I to the fuse interrupting device J, and the power fuse K is interrupted by the interrupting device J.

[0004]

However, in the temperature controller of FIG. 3, when a half-wave rectifier circuit C is attached to the plastic thermistor A to obtain a positive or negative branch current, the half-wave rectifier circuit C is used for the thermistor A. Current in the positive direction current I ₊
> Negative current I _-, and the plastic thermistor ends V _1, the voltage waveform applied to the V ₂ becomes asymmetric as shown in FIG. 4, the positive applied voltage and a negative voltage applied to the difference V _a -V applied to the thermistor A _b = _Vc occurs. The difference V _c becomes a DC component voltage. When this DC voltage is applied to the plastic thermistor A, polarization occurs in the ion conductive thermosensitive polymer of the thermistor A, and the ion carrier in the polymer is ionized. Is generated in the DC electrode, and the distribution of ions near the center of each electrode becomes very small. As shown by the dotted line in FIG. 5, the impedance of the thermosensitive polymer is lower than that in the normal state (shown by the solid line). It becomes big. As a result, degradation of the plastic thermistor A is promoted, also deviation occurs in the control temperature of the temperature controller to raise the control temperature from T ₁ to T _2.

An object of the present invention is to provide a temperature controller which can prevent deterioration of a temperature sensor (plastic thermistor) and excessive rise of a heater.

[0006]

The temperature controller according to the present invention comprises:
As shown in FIGS. 1 and 2, an AC voltage is applied to a temperature sensor 1 whose electric resistance varies according to the temperature, and the AC flowing through the temperature sensor 1 is converted into a positive or negative branch current by a half-wave rectifier circuit. In a temperature controller for detecting the temperature based on the branch current and controlling the temperature of the heater 2, a first half-wave rectifier circuit 3 for obtaining a positive branch current is connected to one terminal of the temperature sensor 1. On the terminal side, a second half-wave rectifier circuit 4 that is electrically equivalent to the first half-wave rectifier circuit 3 and obtains a negative branch current is provided.

[0007]

In the temperature controller according to the present invention, the AC applied to the temperature sensor 1 obtains a positive branch current. The first half-wave rectifier circuit 3 is electrically equivalent to the first half-wave rectifier circuit 3 and has a negative polarity. Since the current flows through the second half-wave rectifier circuit 4 that obtains the branch current, the positive current I ₊ and the negative current I _{− in} the temperature sensor 1 become equal, and the positive voltage applied to the temperature sensor 1 becomes negative. Become equal. As a result, the DC component of the voltage applied to the temperature sensor 1 becomes substantially zero, and no polarization phenomenon occurs in the ion-conductive thermosensitive polymer of the temperature sensor 1, so that deterioration of the temperature sensor 1 can be prevented.

[0008]

FIG. 1 shows an embodiment of the temperature controller of the present invention. This is an electric heating device such as an electric carpet that generates heat by applying an AC voltage of the AC power supply 10 to the heater 2. A temperature sensor (plastic thermistor) arranged near the heater 2 applies two AC voltages from the AC power supply 10 to the heater 2. Resistor R
_The voltage is reduced to several volts to several tens of volts according to 1.

The resistor R ₁ has a first half-wave rectifier circuit 3 for obtaining a positive branch current from an alternating current flowing through the plastic thermistor 1 and a first half-wave rectifier circuit for obtaining a negative branch current. A circuit 3 and a second half-wave rectifier circuit 4 which is electrically equivalent to each other are mounted.

The positive branch current obtained from the first half-wave rectifier circuit 3 is sent to a voltage comparator 12, where it is compared with a reference voltage output from a temperature setting output circuit 13, and is output from the plastic thermistor 1. It can be determined whether the temperature is higher or lower than the set temperature. The voltage of the negative branch current obtained by the other second half-wave rectifier circuit 4 is equal to the voltage of the voltage comparator 1.
4 and compared with the second reference voltage output from the over-temperature rise determination output circuit 15 to determine whether the temperature of the plastic thermistor 1 exceeds a predetermined upper limit temperature.

When the voltage comparator 12 determines that the temperature detected by the plastic thermistor 1 is high, it turns on the heater load.
An off signal is output to the / OFF circuit 16, and the switch 17 of the heater 2 in the ON state is turned off to stop the heat generation of the heater 2. Then, when the heat generation of the heater 2 stops and the temperature detected by the plastic thermistor 1 decreases, the first
When the voltage of the branch current of the half-wave rectifier circuit 3 drops and the voltage drops below the reference voltage of the temperature setting output circuit 13, the voltage comparator 12 outputs an ON signal to the heater load ON / OFF circuit 16 and the switch 17 Turn ON. Further, when determining that the temperature detected by the plastic thermistor 1 has reached the upper limit temperature, the voltage comparator 14 outputs a cutoff signal to the fuse cutoff device 18 and cuts off the power supply fuse 19.

As shown in FIG. 2, a sensor disconnection determination output circuit 20 for detecting disconnection of the plastic thermistor 1 is provided in place of the over-temperature rise determination output circuit 15, and a half-wave rectification is performed from the circuit 20 when the sensor is disconnected. By causing the voltage comparator 14 to determine the disconnection of the plastic thermistor 1 by outputting a reference voltage having a level as output from the circuit 4, the ON signal output from the voltage comparator 14 in a normal state or output when the disconnection occurs. An off signal output from the voltage comparator 12 and an on signal normally output from the voltage comparator 12 or an off signal output when the heater excessively rises are input to a logic discrimination circuit 21. The logic discrimination circuit 21 turns the heater load on / off. The switch 16 may be turned ON / OFF by controlling the circuit 16.

Incidentally, diodes D, resistors R ₂ , capacitors C and the like have the same characteristics so that the first half-wave rectifier circuit 3 and the second half-wave rectifier circuit 4 are electrically equivalent circuits. doing.

[0014]

According to the temperature controller of the present invention, the DC component of the AC applied voltage to the temperature sensor 1 becomes almost zero, and the electrochemical change of the ion-conductive thermosensitive polymer of the temperature sensor 1 occurs. And the life is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a temperature controller according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the temperature controller of the present invention.

FIG. 3 is a block diagram showing an example of a conventional temperature controller.

4 is an explanatory diagram showing voltage waveforms at both ends of a temperature sensor in the temperature controller of FIG.

FIG. 5 is an explanatory diagram showing a polarization state of a temperature sensor in the temperature controller of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temperature sensor 2 Heater 3 1st half-wave rectifier circuit 4 2nd half-wave rectifier circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. An AC voltage is applied to a temperature sensor 1 whose electric resistance varies according to temperature, and an alternating current flowing through the temperature sensor 1 is converted into a positive or negative branch current by a half-wave rectifier circuit. In the temperature controller for detecting the temperature of the heater 2 and controlling the temperature of the heater 2, a first half-wave rectifier circuit 3 for obtaining a positive branch current is provided on one terminal side of the temperature sensor 1 and on the other terminal side. A temperature controller comprising a second half-wave rectifier circuit 4 that is electrically equivalent to the first half-wave rectifier circuit 3 and obtains a negative branch current.