JPH05141678A - Abnormal temperature controller for room heater - Google Patents

Abstract

PURPOSE:To secure the safety by stopping supply of power to a heat generator if a sensed temperature signal from a temperature sensor becomes a temperature set reference signal or more. CONSTITUTION:A comparator 18 compares a temperature signal Vd responsive to a sensed temperature of a temperature sensor 13 with a set temperature signal Vset of a temperature setter 16, and a controller 17 controls a normal power supply amount to heat generators 6, 7 in response to its temperature difference. Here, if a temperature of a room heater body locally rises to become an abnormal temperature of a predetermined value or higher (e.g. 80-120 deg.C), i.e., if the signal Vd of the sensor 13 becomes the reference signal or more, the controller 17 receives the temperature difference from the comparator 18, and stops supplying power to the generators 6, 7. Thus the safety can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal temperature control device for heating appliances such as electric carpets.

[0002]

2. Description of the Related Art An electric carpet is provided with a heating element on a carpet body, a temperature detection line, and a controller for controlling the amount of electric power supplied to the heating element. Of these, the controller compares the set temperature with the temperature of the carpet main body detected by the temperature detection line, and controls on / off of the relay connected to the heating element according to the temperature difference.

By the way, the structure of the temperature detecting wire is such that the primary conductor is wound around the outer periphery of the central core yarn, the secondary conductor is wound around the winding of the primary conductor through the temperature sensitive layer, and the outer coat is further covered. It has been given. Then, the resistance value of the temperature sensitive layer of the temperature detection line changes according to the detected temperature. This allows
The temperature detection line is wired over the entire carpet body to show a resistance value according to the average temperature of the entire carpet body.

Therefore, even if a futon or the like is placed on the carpet body and the temperature in this portion locally rises, the resistance of the temperature detection line has a value corresponding to the average temperature of the entire carpet body.

[0005]

Therefore, the temperature rise in the local portion of the carpet body cannot be detected, and the temperature of the local portion rises abnormally.

Further, a short-circuit detection line is wired around the heating element via the temperature-sensitive layer, but the temperature-sensitive layer is melted by the temperature rise and the heating element and the short-circuit detection line come into contact with each other, resulting in a short-circuit current. Flows. This short-circuit current causes the fuse to melt, cutting off the power supply to the heating element. This makes it impossible to resume normal operation. In addition, the outer fabric of the carpet body is discolored due to the abnormal temperature rise of the carpet body.
Therefore, it is an object of the present invention to provide an abnormal temperature control device for a heating appliance that can detect a temperature rise in a local portion to ensure safety and can resume normal operation.

[0007]

According to the present invention, a temperature-sensitive layer is interposed between a primary conductor and a secondary conductor in a heating appliance abnormal temperature control device for detecting an abnormal temperature in a heating main body in which a heating element is wired. If the resistance value of the temperature sensitive layer changes according to the temperature of the heating main body and the temperature of the heating main body becomes an abnormal temperature above a predetermined temperature, either or both of the resistance value of the primary conductor or the secondary conductor A temperature detection line having a characteristic of rapidly increasing, and a comparison circuit for comparing a temperature signal according to the detected temperature of the temperature detection line with a set temperature signal,
The control circuit controls the normal power supply amount to the heating element according to the temperature difference from the comparison circuit, and stops the power supply to the heating element when the temperature signal becomes equal to or higher than the temperature setting reference signal. It is an abnormal temperature control device for a heating appliance that achieves the above object.

[0008]

By providing such means, the resistance value of the temperature sensitive layer of the temperature detection line changes according to the temperature of the heating main body,
The temperature detection signal corresponding to the detected temperature of the temperature detection line and the set temperature signal are compared by the comparison circuit, and the control circuit controls the normal power supply amount to the heating element according to the temperature difference. When the temperature of the heating main body locally rises to an abnormal temperature above a predetermined temperature in this state, the resistance value of either or both of the primary conductor and the secondary conductor in the temperature detection line suddenly increases. At this time, the control circuit receives the temperature difference from the comparison circuit, and stops the power supply to the heating element when the detected temperature signal becomes equal to or higher than the temperature setting reference signal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an abnormal temperature control device for an electric carpet. A thermal fuse 3 is connected to the AC power source 1 via a power switch 2, and a power line L is connected to the thermal fuse 3. The heating elements 6, 7 are connected to the power line L via the contacts 4a, 5a of the relays 4, 5, respectively.
Are connected in parallel. These heating elements 6 and 7 are wired to the carpet body, and the temperature sensitive layers 8 and 9 are provided around them.
The short circuit detection lines 10 and 11 are wired via the. These short-circuit detection lines 10 and 11 are commonly connected to generate a heating resistance R.
It is connected to 1. The heat generating resistor R1 transfers the heat to the thermal fuse 3. The rectifying diodes D1 and D2 are connected to the heating resistor R1.

A relay drive circuit 1 is provided for each of the relays 4 and 5.
2 is connected. In addition to the function of turning on / off each of the relays 4 and 5, the relay drive circuit 12 selects one or both of the heating elements 6 and 7 to select a heating surface in the carpet body. There is a selection switch for changing over.

A temperature detection circuit 13 is connected to the power supply line L. The temperature detection circuit 13 has a function of outputting a temperature signal vd according to the temperature of the carpet body. FIG. 2 is a specific configuration diagram of the temperature detection circuit 13. The temperature detection line 14 is connected to the power line L via the resistor R2.
Are connected.

As shown in FIG. 3, the temperature detecting wire 14 has a structure in which a primary conductor S is wound around the center core yarn 15a, and the primary conductor S is wound around the temperature sensing layer 15b. The next conductor E is wound and the outer cover 15c is further applied. Of these, the primary conductor S and the secondary conductor E are formed of a metal or a semiconductor and have a predetermined temperature or higher,
For example, when the temperature is 80 to 120 ° C. or higher, the resistance value suddenly increases as shown in FIG. 4, and has a characteristic of changing to several tens Ω to several MΩ.

Therefore, the temperature detecting line 14 detects the temperature of the carpet body, and the temperature sensitive layer 15 is detected in accordance with the detected temperature.
When the resistance value of b changes and the temperature of the carpet body rises above 80 to 120 ° C., for example, the resistance values of the primary conductor S and the secondary conductor E change abruptly. The temperature detection line 14 connects the primary conductor S to the resistor R2,
Further, the secondary conductor E is connected via the resistors R3 and R4.

A peak hold circuit PF is connected to the connection point between the resistors R3 and R4. This peak hold circuit PF includes an operational amplifier 15 via a resistor R5.
“−” Input terminal is connected, and the diode D3 is connected to the output terminal of the operational amplifier 15. Furthermore, the "-" input terminal is connected to the cathode of the diode D3 via the feedback resistor R6. Further, a diode D4 is provided between the "-" input terminal and the "+" input terminal of the operational amplifier 15.
And a diode D5 is connected to the "-" input terminal. Furthermore, a capacitor C1 and a resistor R7 are connected in parallel to the output terminal of the operational amplifier 15 via a diode D3.

On the other hand, a temperature setting circuit 16 is connected to each of the short circuit detection lines 10 and 11. The temperature setting circuit 16 has a function of setting the temperature of the carpet body to a desired temperature, and specifically has the configuration shown in FIG. A resistor R12 is connected to a connection point of the voltage dividing resistors R10 and R11 connected to the short circuit detection line 10. Also, the relay drive circuit 1
The base of the transistor Q1 is connected to the resistor R13 for inputting the heating surface switching signal k of 2, the resistor R12 is connected to the collector of the transistor Q1, and the resistor R14 is connected between the base and the emitter. This transistor Q1
The base of the transistor Q2 is connected to the collector of the transistor via a resistor R15, and the resistor R16 is connected between the base and the emitter of the transistor Q2.

Further, a smoothing condenser C2 is connected to the connection point of each of the voltage dividing resistors R17 and R18 connected to the short circuit detection line 11. This smoothing capacitor C2 has a transistor Q
The emitter of the transistor Q3 is connected, the resistor R19 is connected to the collector of the transistor Q3, the resistor R20 is connected to the emitter, and the resistors R19 and R20 are commonly connected. A variable resistor V is connected to a common connection point of these resistors R19 and R20.
R and the resistor R21 are connected in parallel, and the resistors R22 and R23 are connected to the variable resistor VR and the resistor R21 to form a voltage dividing circuit. The collector of the transistor Q4 is connected to the voltage dividing circuit via the resistor R24. The base of the transistor Q4 is connected to the resistor R25 via the resistor R25.
A resistor R26 is connected between the base and the emitter. Here, the connection point between the variable resistor VR and the resistor R21 is output as the temperature setting signal Vset.

The base of the transistor Q5 is connected to the resistor R27 connected to the control circuit 17, and the collector of the transistor Q5 is connected to the transistor R5 via the resistor R28.
6 bases are connected. The collector of the transistor Q6 is connected to the base of the transistor Q3 via the resistor R29.

The comparison circuit 18 inputs the temperature signal vd and the temperature setting signal Vset, and outputs the temperature detection signal Va which is the difference between the temperature signal vd and the temperature setting signal Vset.
As shown in FIG. 6, the temperature signal vd is input to the “+” input terminal of the operational amplifier 19, the temperature setting signal Vset is input to the “−” input terminal, and each voltage dividing resistor R30 is input from the output terminal of the operational amplifier 19. , R31, the temperature detection signal Va is output. in this case,

(A) If the temperature signal vd <the temperature setting signal Vset, the output of the operational amplifier 19 is constant at "0" level. (b) If the temperature setting signal Vset <temperature signal vd <secondary conductor disconnection detection voltage Vcut, the output of the operational amplifier 19 repeatedly outputs the levels of "0" and "1". (c) If the secondary conductor disconnection detection voltage Vcut <temperature signal vd, the output of the operational amplifier 19 is constant at "0" level.

The control circuit 17 is composed of a microcomputer, and has a function of receiving the temperature detection signal Va from the comparison circuit 18 and sending a relay drive signal H to the relay drive circuit 12 according to the temperature detection signal Va. have. The function of the control circuit 17 will be described in detail. When the temperature detection signal Va is received and the temperature detection signal Va is (x) "0" level constant, the relays 4 and 5 are turned off at "0" level. The relay drive signal H of (1), and if (0) is a repetition of "0" and "1", the relay drive signal H of "1" level for turning on each relay 4, 5 is provided. Have.

The control circuit 17 has an abnormality indicator lamp 1
9 is connected and has a function of turning on the abnormality display lamp 19 when the secondary conductor disconnection detection voltage Vcut <temperature signal vd. Reference numeral 20 is a clock generation circuit. or,
A power supply circuit 21 is connected to the power supply line L, and DC power is supplied from the power supply circuit 21 to the temperature detection circuit 13 and the control circuit 17.
Have been supplied to. Next, the operation of the device configured as described above will be described. (1) When there is no cushion on the carpet body

When the power switch 2 is turned on and the relays 4 and 5 are turned on, the AC power is supplied to the heating elements 6 and 7 through the relay contacts 4a and 5a. These heating elements 6 and 7 generate heat and the temperature of the carpet body rises.

In this state, the temperature sensing layer 15b of the temperature detecting wire 14
Indicates the resistance value according to the temperature of the carpet body. However, when the AC voltage is supplied to the temperature detection line 14, the AC voltage is divided by the resistance R2, the resistances R3 and R4, and the resistance of the temperature sensitive layer 15b between the primary conductor S and the secondary conductor E. It Of these, the voltage appearing between the resistors R3 and R4 is shown in FIG.
As the temperature detection voltage Vs shown in FIG.
Is supplied to the "-" input terminal of the operational amplifier 15. The peak hold circuit PF rectifies and smoothes the temperature detection voltage Vs to generate a temperature signal vd.

On the other hand, a half-wave voltage is supplied to each of the short circuit detection lines 10 and 11 through each of the diodes D1 and D2 and the resistor R1. Of these, the half-wave voltage VGB from the one short-circuit detection line 11 is divided by the resistors R17 and R18 and smoothed by the capacitor C2 to become the temperature setting reference voltage Vf as shown in FIG. The temperature setting reference voltage Vf is the disconnection detection voltage Vcut of the secondary conductor E in the temperature detection line 14.
Also used as.

The half-wave voltage VGA from the other short-circuit detection line 10 is divided by the resistors R10 and R11, and the resistors R12 and R12 are divided.
It is supplied to each transistor Q2 through R15 and to the transistor Q4 through a resistor R25. As a result, the transistors Q2 and Q4 are turned on / off.

When the transistors Q2 and Q4 are both turned on, the resistors R19 and R20, the variable resistor VR, and the resistors R
Of the voltage divided by 21, R22 and R23, each resistor R1
The voltage appearing between R20 and the variable resistor VR is output as the temperature setting voltage Vset as shown in FIG. This temperature setting voltage Vset becomes a value according to the desired carpet body temperature due to the resistance change of the variable resistor VR, and changes in the range of W.

The temperature setting voltage Vset is corrected by turning on / off the heating surface selection switch in the relay drive circuit 12. That is, when the selection switch is selected, the ON heating surface switching signal k is input to the base of the transistor Q1 and the transistor Q1 is turned on. When the transistor Q1 turns on, the transistor Q2 turns off and only the transistor Q4 turns on. Therefore, the resistor R24 is connected to the voltage dividing circuit and the temperature setting voltage Vset is corrected.

On the other hand, when the transistors Q2 and Q4 are both turned off, the temperature setting voltage Vset becomes the temperature setting reference voltage Vf.
And in this case, the secondary conductor disconnection detection voltage Vcut
Becomes

However, the temperature signal vd from the temperature detection circuit 13 and the temperature setting signal Vset from the temperature setting circuit 16
Is sent to the comparison circuit 18. As shown in FIG. 10, the operational amplifier 19 in the comparison circuit 18 includes (a) the temperature signal v
If d <temperature setting signal Vset, the temperature detection signal Va having a constant “0” level is output, and (b) temperature setting signal Vset <
If the temperature signal vd <secondary conductor disconnection detection voltage Vcut,
Temperature detection signal Va that repeats the levels of "0" and "1"
(C) If the secondary conductor disconnection detection voltage Vcut <temperature signal vd, the temperature detection signal Va having a constant "0" level is output.

The control circuit 17 receives the temperature detection signal Va,
If the temperature detection signal Va is constant at "0" level, the relay drive signal H of "0" level for turning off the relays 4 and 5 is sent out, and the temperature detection signal Va is repeated between "0" and "1". If it is a return, turn on each relay 4, 5 "1"
The level relay drive signal H is transmitted.

By the way, when the relay drive signal H of "1" level is transmitted and each of the relays 4 and 5 is turned on, the relay drive signal H of "1" level at this time is supplied to the temperature setting circuit 16
Is supplied to the base of the transistor Q5, and this transistor Q5 is turned on.
Turns off and the resistor R19 is disconnected from the voltage dividing circuit. Therefore, the temperature setting signal Vset is corrected (Vset ') in the direction in which the temperature of the carpet main body is raised, that is, in the direction in which the relays 4 and 5 are hard to turn off, as shown in FIG.

Conversely, when each relay 4, 5 is turned off, "1"
The level relay drive signal H is supplied to the base of the transistor Q5, which turns off. Along with this, the transistors Q6 and Q3 are turned on, and the resistor R19 is connected to the voltage dividing circuit. Therefore, the temperature setting signal Vset is corrected in the direction in which the temperature of the carpet main body is lowered, that is, in the direction in which the relays 4 and 5 are difficult to turn on, as shown in FIG. By this correction, the temperature setting signal Vset has hysteresis, and it is possible to prevent the relays 4 and 5 from being repeatedly turned on and off in a short time. Thus, by the above operation, the relays 4 and 5 are turned on and off, and the amount of electric power supplied to the heating elements 6 and 7 is controlled. (2) When a cushion etc. is placed on the carpet body

When a futon or the like is placed on the carpet body, the temperature of this portion locally rises. Then, when the temperature of this portion becomes, for example, 80 ° C. or higher, the resistance values of the primary conductor S and the secondary conductor E in the temperature detection line 14 rapidly increase as shown in FIG. These primary conductors S
Also, the level of the temperature signal vd increases due to the resistance change of the secondary conductor E, and the secondary conductor disconnection detection voltage Vcut <temperature signal v
The state becomes d. As a result, the control circuit 17 continues to send the relay drive signal H of "0" level, and the relays 4, 5
Turn off. Therefore, the power supply to the heating elements 6 and 7 is cut off, and the temperature of the carpet body is lowered. Further, the control circuit 17 controls the secondary conductor disconnection detection voltage Vcut <temperature signal v
The state of d is judged and the indicator lamp 19 is turned on to notify the occurrence of abnormality.

As described above, according to the above-described embodiment, when the temperature of the carpet main body locally rises and becomes equal to or higher than the predetermined temperature, the primary conductor S and the secondary conductor E in the temperature detection wire 14 are provided.
Since the resistance of the carpet suddenly increases and the power supply to the heating elements 6 and 7 is stopped, even if the temperature rises locally in the carpet body, this temperature rise is detected and the temperature rise in the local area is detected. Can be prevented. Therefore, the temperature sensitive layers 8 and 9 are not melted, the heating elements 6 and 7 and the short-circuit detection lines 10 and 11 are not in contact with each other, and the power supply to the heating elements 6 and 7 is not interrupted.
When the temperature of the carpet body is reduced to normal, the heating operation can be restarted. Further, the surface texture of the carpet body does not change color due to the abnormal temperature rise of the carpet body.

The present invention is not limited to the above-mentioned embodiment, but may be modified within the scope of the invention. For example, the temperature detection circuit 13 and the temperature setting circuit 16 may have other circuit configurations. Further, the present invention can be applied not only to electric carpets but also to other heating appliances such as electric blankets.

On the other hand, the temperature detection line 14 is designed to rapidly increase the resistance of both the primary conductor S and the secondary conductor E at a predetermined temperature, but the resistance of either one of the primary conductor S or the secondary conductor E is set to a predetermined value. It may increase rapidly with temperature.

[0038]

As described above in detail, according to the present invention, it is possible to provide an abnormal temperature control device for a heating appliance which can detect a temperature rise in a local portion to ensure safety and can resume normal operation. ..

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an abnormal temperature control device for a heating appliance according to the present invention.

FIG. 2 is a specific configuration diagram of a temperature detection circuit in the same device.

FIG. 3 is a structural diagram of a temperature detection line in the same device.

FIG. 4 is a characteristic diagram showing resistance changes of the primary conductor and the secondary conductor in the temperature detection line.

FIG. 5 is a specific configuration diagram of a temperature setting circuit in the same device.

FIG. 6 is a specific configuration diagram of a comparison circuit in the device.

FIG. 7 is a waveform diagram of a temperature detection voltage and a temperature signal in the same device.

FIG. 8 is a waveform diagram of a temperature setting reference voltage in the same device.

FIG. 9 is a waveform diagram of a temperature setting voltage in the same device.

FIG. 10 is a waveform diagram of a temperature setting voltage and a temperature signal in the same device.

FIG. 11 is a waveform diagram of a temperature setting voltage and a temperature signal in the same device.

[Explanation of symbols]

 4, 5 ... Relay, 4a, 5a ... Relay contact, 6, 7 ... Heating element, 12 ... Relay drive circuit, 13 ... Temperature detection circuit, 14 ... Temperature detection line, S ... Primary conductor, E ... Secondary conductor, 15b ... temperature sensitive layer, 16 ... temperature setting circuit, 17 ... control circuit, 18 ... comparison circuit.

Claims (1)

[Claims] 1. An abnormal temperature control device for a heating appliance for detecting an abnormal temperature in a heating main body to which a heating element is wired, wherein a temperature-sensitive layer is formed between a primary conductor and a secondary conductor, and the heating main body is formed. When the resistance value of the temperature-sensitive layer changes according to the temperature of the heating body and the temperature of the heating body becomes an abnormal temperature of a predetermined temperature or higher, the resistance value of either or both of the primary conductor and the secondary conductor increases sharply. A temperature detection line having the following characteristics, a comparison circuit for comparing a temperature signal corresponding to the detected temperature of the temperature detection line and a set temperature signal, and normal power to the heating element according to the temperature difference from the comparison circuit. An abnormal temperature control device for a heating appliance, comprising: a control circuit that controls a supply amount and stops power supply to the heating element when the temperature signal becomes equal to or higher than a temperature setting reference signal.