JP3058734B2 - Heating device abnormal temperature control device - Google Patents

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 a heating device such as an electric carpet.

[0002]

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

[0003] By the way, the structure of the temperature detecting wire is such that a primary conductor is wound around the outer periphery of a center core yarn, a secondary conductor is wound around the wound primary conductor via a temperature-sensitive layer, and a jacket is further provided. It has been given. 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, and thus exhibits a resistance value according to the average temperature of the entire carpet body.

[0004] 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 becomes a value corresponding to the average temperature of the entire carpet body.

[0005]

For this reason, it is impossible to detect a rise in the temperature of a local portion of the carpet body, and the temperature of the local portion abnormally rises.

A short-circuit detection line is wired around the heating element via a temperature-sensitive layer. However, the temperature-sensitive layer melts due to a rise in temperature, and the heating element comes into contact with the short-circuit detection line. Flows. The fuse is blown by this short-circuit current, and the power supply to the heating element is cut off. This makes it impossible to resume the normal operation. In addition, the surface cloth of the carpet body is discolored due to an abnormal rise in the temperature of the carpet body.
Therefore, an object of the present invention is to provide an abnormal temperature control device for a heating appliance which can secure safety by detecting a temperature rise in a local portion and can resume normal operation.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an abnormal temperature control device for a heating appliance for detecting an abnormal temperature in a heating body to which a heating element is wired, wherein a temperature-sensitive layer is interposed between a primary conductor and a secondary conductor. When the resistance 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 equal to or higher than a predetermined temperature, the resistance value of one or both of the primary conductor and the secondary conductor is formed. A temperature detection line having a characteristic that the temperature detection line rapidly increases, a comparison circuit that compares a temperature signal according to the detection temperature of the temperature detection line with a set temperature signal,
A control circuit that controls a normal power supply amount to the heating element according to a temperature difference from the comparison circuit and stops power supply to the heating element when the temperature signal becomes equal to or higher than a temperature setting reference signal. An abnormal temperature control device for a heating appliance that achieves the above object.

[0008]

With the provision of such means, the resistance value of the temperature-sensitive layer of the temperature detection line changes according to the temperature of the heating body,
A temperature detection signal corresponding to the detected temperature of the temperature detection line and a set temperature signal are compared by a comparison circuit, and a control circuit controls a normal power supply amount to the heating element according to the temperature difference. In this state, when the temperature of the heating body locally rises and becomes an abnormal temperature equal to or higher than a predetermined temperature, the resistance value of one or both of the primary conductor and the secondary conductor in the temperature detection line rapidly 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]

An embodiment of the present invention will be described below with reference to the drawings.

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

Each of the relays 4 and 5 has a relay drive circuit 1
2 are connected. In addition to the function of turning on and off 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. Is provided.

Further, a temperature detecting 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.
Is connected.

As shown in FIG. 3, the structure of the temperature detecting wire 14 is such that a primary conductor S is wound around the outer periphery of a center core yarn 15a, and the primary conductor S is wound around the primary conductor S via a temperature-sensitive layer 15b. The next conductor E is wound, and a jacket 15c is further provided. Among them, the primary conductor S and the secondary conductor E are formed of a metal or a semiconductor, and a predetermined temperature or more,
For example, when the temperature is 80 to 120 ° C. or higher, the resistance value rapidly increases as shown in FIG.

Accordingly, the temperature detection line 14 detects the temperature of the carpet body, and according to the detected temperature, the temperature-sensitive layer 15
When the resistance value of b changes and the temperature of the carpet body becomes 80 to 120 ° C. or higher as described above, the resistance values of the primary conductor S and the secondary conductor E sharply change. The temperature detection line 14 connects the primary conductor S to the resistor R2,
Further, the secondary conductor E is connected via the respective resistors R3 and R4.

A peak hold circuit PF is connected to a connection point between each of the resistors R3 and R4. This peak hold circuit PF is connected to the operational amplifier 15 via the resistor R5.
Of the operational amplifier 15 is connected to a diode D3. Further, a "-" input terminal is connected to the cathode of the diode D3 via a feedback resistor R6. A diode D4 is connected between the "-" input terminal and the "+" input terminal of the operational amplifier 15.
And the diode D5 is connected to the "-" input terminal. Further, 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 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 has a specific configuration shown in FIG. A resistor R12 is connected to a connection point between 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 to which the heating surface switching signal k is input, and the collector of the transistor Q1 is connected to the resistor R12 and the resistor R14 is connected between the base and the emitter. This transistor Q1
Is connected to the base of a transistor Q2 via a resistor R15, and a resistor R16 is connected between the base and the emitter of the transistor Q2.

Further, a smoothing capacitor C2 is connected to a connection point of each of the voltage dividing resistors R17 and R18 connected to the short detection line 11. The smoothing capacitor C2 includes a transistor Q
The emitter of the transistor Q3 is connected to the collector of the transistor Q3, the resistor R19 is connected to the emitter, the emitter is connected to the resistor R20, 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.
An R and a 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 this transistor Q4 is connected to a resistor R via a resistor R25.
10 and 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 a 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 collector of the transistor Q5 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 receives the temperature signal vd and the temperature setting signal Vset, and outputs a temperature detection signal Va indicating a difference between the temperature signal vd and the temperature setting signal Vset.
As shown in FIG. 6, the temperature signal vd is inputted to the "+" input terminal of the operational amplifier 19, the temperature setting signal Vset is inputted to the "-" input terminal, and each voltage dividing resistor R30 is inputted from the output terminal of the operational amplifier 19. , R31, a 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 kept at the "0" level. (b) If the temperature setting signal Vset <the temperature signal vd <the secondary conductor disconnection detection voltage Vcut, the output of the operational amplifier 19 repeatedly outputs “0” and “1” levels. (c) If the secondary conductor disconnection detection voltage Vcut <the temperature signal vd, the output of the operational amplifier 19 is kept at the “0” level.

The control circuit 17 comprises a microcomputer, and has a function of receiving a temperature detection signal Va from a comparison circuit 18 and transmitting a relay drive signal H to the relay drive circuit 12 in accordance with the temperature detection signal Va. have. Specifically, the function of the control circuit 17 will be described. When the temperature detection signal Va is received and the temperature detection signal Va is (x) "0" level constant, the "0" level which turns off the relays 4 and 5 is set. (Y) If "0" and "1" are repeated, a function of transmitting a "1" level relay drive signal H for turning on each of the relays 4 and 5 is provided. Have.

The control circuit 17 has an abnormality display lamp 1
9 is connected, and has a function of turning on the abnormality indicator lamp 19 when the secondary conductor disconnection detection voltage Vcut <temperature signal vd. 20 is a clock generation circuit. or,
A power supply circuit 21 is connected to the power supply line L. DC power is supplied from the power supply circuit 21 to the temperature detection circuit 13 and the control
And so on. Next, the operation of the apparatus 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 on, 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-sensitive layer 15b of the temperature detection line 14
Indicates a resistance value according to the temperature of the carpet body. However, when an AC voltage is supplied to the temperature detection line 14, the AC voltage is divided by the resistor R2, the resistors R3, R4, and the resistance of the temperature sensing layer 15b between the primary conductor S and the secondary conductor E. You. The voltage appearing between the resistors R3 and R4 is shown in FIG.
The peak hold circuit PF 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 the short-circuit detection lines 10 and 11 through the diodes D 1 and D 2 and the resistor R 1. The half-wave voltage VGB from one of the short-circuit detection lines 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 a 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,
It is supplied to each transistor Q2 through R15 and to transistor Q4 through a resistor R25. As a result, the transistors Q2 and Q4 are turned on and off.

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

The temperature setting voltage Vset is corrected by turning on / off a heating surface selection switch in the relay drive circuit 12. That is, when the selection switch is selected, an 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
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) a temperature signal v
If d <temperature setting signal Vset, a temperature detection signal Va with a constant “0” level is output, and (b) temperature setting signal Vset <
If the temperature signal vd <the 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, a 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, a relay drive signal H of "0" level for turning off each of the relays 4 and 5 is sent out, and the temperature detection signal Va repeats "0" and "1". If returning, turn on relays 4 and 5 "1"
The level relay drive signal H is transmitted.

When the relay drive signal H at the "1" level is transmitted and the relays 4 and 5 are turned on, the relay drive signal H at the "1" level is supplied to the temperature setting circuit 16 at this time.
Is supplied to the base of the transistor Q5, and the transistor Q5 is turned on, so that the transistors Q6 and Q3
Is turned off, and the resistor R19 is disconnected from the voltage dividing circuit. Therefore, the temperature setting signal Vset is corrected (Vset ') in the direction of increasing the temperature of the carpet body, that is, the direction in which the relays 4 and 5 are hard to be turned off, as shown in FIG.

On the contrary, when each of the relays 4 and 5 is turned off, "1" is set.
The level relay drive signal H is supplied to the base of the transistor Q5, which turns off. Accordingly, 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 a direction to lower the temperature of the carpet body, that is, in a direction in which the relays 4 and 5 are hard to be turned on, as shown in FIG. With this correction, the temperature setting signal Vset has a hysteresis, so that it is possible to prevent the relays 4 and 5 from repeatedly turning on and off in a short time. Thus, the relays 4 and 5 are turned on and off by the above operation, and the amount of electric power supplied to each of the heating elements 6 and 7 is controlled. (2) When a cushion 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 more, the resistance values of the primary conductor S and the secondary conductor E in the temperature detection line 14 become
As shown in FIG . These primary conductors S
And 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 transmit the “0” level relay drive signal H, and the relays 4, 5,
Turns off. Accordingly, the power supply to each of the heating elements 6 and 7 is cut off, and the temperature of the carpet body decreases. In addition, the control circuit 17 controls the secondary conductor disconnection detection voltage Vcut <temperature signal v
The state of d is determined, and the display lamp 19 is turned on to notify the occurrence of an abnormality.

As described above, according to the embodiment, when the temperature of the carpet 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 line 14 are detected.
The resistance value of the heating element suddenly increases, and the power supply to each of the heating elements 6 and 7 is stopped. Therefore, even if the temperature rises locally in the carpet body, the temperature rise is detected and the local temperature rise is detected. Can be prevented. Therefore, the heat-sensitive layers 8, 9 are not melted and the heating elements 6, 7 and the short-circuit detection lines 10, 11 are brought into contact with each other, so that the power supply to the heating elements 6, 7 is not cut off.
When the temperature of the carpet body drops to normal, the heating operation can be resumed. Then, the surface material of the carpet body does not discolor due to the abnormal temperature rise of the carpet body.

The present invention is not limited to the above 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 another circuit configuration. Further, the present invention can be applied to not only the electric carpet but also other heating appliances, for example, an electric blanket.

On the other hand, the temperature detection line 14 is designed to sharply increase the resistance of both the primary conductor S and the secondary conductor E at a predetermined temperature. It may increase sharply 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 secure safety by detecting a temperature rise in a local portion and can resume normal operation. .

[Brief description of the 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 device.

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

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

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

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

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

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

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

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

FIG. 11 is a waveform chart 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.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F24D 13/02 H05B 3/00 365

Claims (1)

(57) [Claims] 1. An abnormal temperature control device for a heating appliance for detecting an abnormal temperature in a heating body to which a heating element is wired, wherein a heating layer is formed between a primary conductor and a secondary conductor. When the resistance value of the temperature-sensitive layer changes according to the temperature and the temperature of the heating body becomes an abnormal temperature equal to or higher than a predetermined temperature, the resistance value of one or both of the primary conductor and the secondary conductor rapidly increases. 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 with a set temperature signal; and a normal power supply to the heating element according to a temperature difference from the comparison circuit. A control circuit for controlling a supply amount and for stopping power supply to the heating element when the temperature signal becomes equal to or higher than a temperature setting reference signal.