JPH0754741B2 - Floor heating system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a floor heating apparatus in which an electric heater is built in a carpet or the like and an electronic circuit controls the heater.

2. Description of the Related Art Generally, electric carpets provide a heating function by controlling a cord-shaped heater built in the main body so that the temperature of the carpet main body is detected by a temperature sensor also built in the main body. As a configuration of the electric carpet, a two-wire type in which a heater and a temperature sensor are separately provided and a one-wire type in which a heat sensitive heater in which the heater and the temperature sensor according to the present invention are combined into one cord shape are used can be considered. Since the 1-wire type is more advantageous in terms of cost than the 2-wire type, the 1-wire type is generally adopted in the electric blanket having the same technical elements, but the electric power required for higher wattage is higher than that of the electric blanket. It is difficult to make fail-safe construction for carpets, and two-wire type is generally used, and no one-wire electric carpet satisfying fail-safe is provided.

In the one-wire type electric carpet, since the heater wire is used as the temperature sensor electrode, when the heater is turned on, a potential gradient occurs between the temperature sensor electrodes, and the detection sensitivity is biased depending on the location of the temperature sensor. Therefore, it is common to turn it off periodically to detect the temperature.In that case, the fail-safe configuration makes it impossible for the control unit to periodically stop energizing the heater, so that As a general method, a switch element detection unit, a timer unit, and a security unit that stop the system when power is continuously applied are redundantly provided for the control unit.

Problems to be Solved by the Invention When a one-wire temperature control system is adopted for an electric carpet, the temperature cannot basically be detected while the heater wire is energized, so that a failure occurs in the heater drive unit or control unit. However, even if the heater could not be turned off, the abnormal temperature rise could not be detected and it was difficult to stop the system. Therefore, in general, a safety unit is provided that stops the system if it is not turned off for a certain period of time. However, if the safety unit fails, the control will continue to operate normally and the electric carpet will continue to be used. In this state, if the control unit fails and it becomes impossible to control the energization of the heater, the system cannot be stopped. In other words, if the control unit fails and the safety unit must operate, it will not operate, and when the heater is turned on, it will be in an uncontrolled state and the heater energization must be surely stopped periodically. The composition was insufficient.

Means for Solving the Problems In order to solve the above problems, the present invention relates to a heat-sensitive heater including a first electrode functioning as a heater and a second electrode in which a polymer whose impedance changes with temperature is interposed. A main body of the floor heating device incorporating the heat sensitive heater; a bidirectional switch element connected in series to the heater to control energization of the heater; and a temperature connected in series to the heater and the bidirectional switch element. A fuse, a temperature detection unit that detects a change in impedance of the heat sensitive heater from the second electrode, a temperature setting unit that sets the temperature of the floor heating device body, and the temperature fuse that is thermally connected to the temperature fuse. A safety unit that heats the heater to shut off the power to the heater; a timer unit that drives the safety unit after a certain time has passed after the switch element is turned on; Immediately after the driving of Abe is detected, the bidirectional switch element is turned off, and after a certain delay, the signal of the temperature detecting unit and the signal of the temperature setting unit are compared to set the floor heating device main body temperature to the temperature setting unit. When the temperature becomes lower than the predetermined temperature, the bidirectional switch element is turned on, and when the drive of the safety section is not detected for a certain time or longer, the security section is driven and the bidirectional switch element is kept in the off state. And a switch element detection section that detects the OFF state of the bidirectional switch element, resets the timer section, and stops the driving of the security section before the temperature fuse is melted. is there.

Operation With the above configuration, the control unit operates the timer unit that is reset when the heater is de-energized, and the security unit driven by the timer unit stops the system after a certain period of time after the reset is released. Detected by and turn off the switch element and stop energizing the heater. As a result, the timer section is also reset at the same time and the drive of the security section is released, so that the system is maintained in the operating state. The control unit takes some delay time after turning off the power to the heater and detects the temperature through the temperature detection unit. When the temperature of the carpet body falls below the set temperature set in the temperature setting unit, the switch element is turned on and the heater is turned on. The temperature is controlled so that the temperature of the carpet main body is kept constant by turning on the electricity. If the safety unit is not driven for a certain period of time and does not try to stop the system, the control unit drives the safety unit, stops the system, and simultaneously turns off the switch element to cut off the power supply to the heater. By configuring the operations of the control unit, the switch element detection unit, the timer unit and the security unit in a loop like this, the control unit constantly monitors the switch unit detection unit, the timer unit and the security unit for abnormalities, and vice versa. It is possible to provide an electric carpet having a fail-safe level comparable to that of the two-wire system while utilizing the advantage of cost because the unit can monitor the abnormality of the control unit and the switch element.

Embodiment One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a functional block diagram of the present invention, in which an AC power source 3 is connected with a temperature fuse 29, a heater 10a and a switch element 11 in series. When the switch element 11 is off, the control unit 4 compares the temperature signal from the sensor 10b with the setting data from the temperature setting unit 6 via the temperature detecting unit 9 and indicates that the temperature signal is lower than the setting temperature. When the switch element 11 is turned on, power supply to the heater 10a is started, and at the same time, the control unit 4 activates the internal timer. When the switch element 11 is turned on, the switch element detection unit 13 detects it and activates the timer unit 14. After a certain period of time, the timer unit 14 counts up and drives the security unit 15. The control unit 4 instantaneously detects that the security unit 15 has been driven, resets the internal timer, and turns off the switch element 11. The switch element detection unit 13 detects that the switch element 11 is off and resets the timer unit 14. Then, the timer unit 14 releases the drive of the security unit 15. The temperature is controlled in a cycle in which the switch element 11 is turned off, a short delay is taken, temperature detection is performed again, and the switch element 11 is kept off until the temperature falls below a set temperature. As described above, the temperature control employs an OFF detection control method in which the temperature is detected while the power is being supplied to the heater 10a for a certain period of time and then the temperature is detected, and when the temperature reaches the set temperature, the power is supplied to the heater 10a again. Further, since the safety section 15 is driven and the series of operations for releasing the drive again is instantaneously performed, the temperature fuse 29
Does not melt down. The internal timer provided in the control unit 4 is set longer than the count-up time of the timer unit 14 and normally does not count up. However, for example, when the timer unit 14 malfunctions and stops counting up, The timer counts up and the control unit 4 outputs a drive output to the security unit 15 and turns off the switch element 11.

With such a configuration, when the control unit 4 fails and the switch element 11 cannot be turned off, when the switch element 11 itself has a short-circuit failure, the switch element detection unit 13 fails and the timer unit 14 cannot be reset. In this case, the timer unit 14 counts up and drives the security unit 15, blows the thermal fuse 29, and cuts off the power supply to the control circuit and the heater 10a. When the timer unit 14 fails and does not count up, and when the security unit 15 fails and the temperature fuse 29 cannot be heated, the internal timer of the control unit 4 counts up and drives the security unit 15. At the same time, it is possible to provide a temperature control circuit that works on the safe side even if any of the temperature control mechanisms fails, such as turning off the switch element 11.

Next, FIG. 2 is a circuit diagram of an embodiment of the present invention. The power supply circuit 1 supplies a direct current to the control circuit. The reset circuit 2 resets the microcomputer (control unit) 4 when the AC power supply 3 rises and falls. A buzzer circuit 5 is used for a tact sound when the tact switch of the switch circuit (temperature setting unit) 6 is pressed, and a warning sound when an abnormality occurs in the system. The switch circuit 6 includes a power switch, an UP switch, and a DOWN switch, and the temperature is set using the UP switch and the DOWN switch. The set temperature level is displayed on the display unit 7. Reference numeral 8 is an AC power supply synchronization detection circuit, 9 is a temperature detection circuit (temperature detection unit), 10 is a heat-sensitive heater composed of a heater 10a and a sensor 10b, and its impedance has temperature dependence between an electrode composed of a heater wire and a signal electrode. It has a structure in which the polymer it has is interposed. The temperature detection circuit 9 takes out this change in impedance as a phase shift from the AC power supply. FIG. 5 shows the characteristics of the heat sensitive heater. Reference numeral 11 is a relay (switch element) for controlling energization to the heater, and 12 is a relay drive circuit for turning on the transistor 16 by the output of P20 of the microcomputer 4 to drive the relay 11. 13 is a relay contact detection circuit (switch element detection part), the transistors 17 and 18 are turned on by the voltage between the contacts generated when the contact of the relay 11 is turned off, the output transistor 19 is turned on, and the reset signal is output to the timer circuit 14. To do. The timer circuit (timer unit) 14 outputs a count-up signal when the potential of the capacitor 20 exceeds the reference potential determined by the resistors 21 and 22, and during that time the capacitor 20 and the resistor 23
It depends on the time constant of. When the relay 11 is turned off, the reset signal from the relay contact detection circuit 13 turns on the transistor 24 to instantly discharge the electric charge accumulated in the capacitor 20 and release the count-up signal. As a matter of course, the resistor 25 is sufficiently smaller than the resistor 23, and the time constant with the capacitor 20 is set to several hundred milliseconds or less. Reference numeral 15 is a security circuit (security unit) which is activated by the count-up signal of the timer circuit 14 and the P22 output of the microcomputer 4. At startup, transistor 26 turns on and triac 27 turns on,
During the positive cycle of the AC power supply, a voltage of 100 V half wave is applied to the heating resistor 28. The heating resistor 28 is thermally connected to the thermal fuse 29, and when the heating resistor 28 is energized, the thermal fuse 28 takes about 10 seconds.
29 is configured to melt and cut off the power supply to the control circuit and the heater. The detection of the switch, the driving of the buzzer, the driving of the display unit and the temperature control described below are all performed by the microcomputer 4. FIG. 3 shows mainly the temperature control part of the microcomputer 4.

Next, the temperature control operation having the fail-safe function will be described with reference to FIG.

When the reset of the microcomputer 4 is released, the registers in RAM and the input / output terminals are initialized in S1, and the process goes to S2. In S2, processing such as switch detection, buzzer driving, and display is performed to determine the control mode, temperature set value, and the like. In the heater control mode, the process goes to S3, inputs the temperature signal from the temperature detection circuit 9, compares it with the AC synchronization signal from the AC power supply synchronization detection circuit 8, and obtains the phase shift t shown in FIG. 4 to obtain the temperature data. . In FIG. 4, a is an AC power supply waveform, b is an output waveform of the AC power supply synchronization detection circuit 8, and c is an output waveform of the temperature detection circuit 9. In S4, the temperature set value is compared with the temperature data, and if the temperature data shows a high temperature against the set value, the process returns to S2 and loops until the temperature data falls below the set value, and the heater energization is maintained in the off state. . If the temperature data indicates a temperature lower than the set value in S4, the relay 11 is turned on via the relay drive circuit 12 in S5 to start energizing the heater, and the timer circuit
When the relay 11 is turned on, 14 also operates by releasing the reset from the relay contact detection circuit 13. At the same time, in S6, the internal timer built in the microcomputer 4 is reset and started. In S7 to S10, the count-up of the internal timer and the external timer, that is, the timer circuit 14 is monitored while performing the same processing as S2. For example, the timer circuit 14 is set to count up in about 60 seconds, and the internal timer is set to count up in 120 seconds. Therefore, the timer circuit 14 normally counts up first.
Turn off relay 11 with S11. Since the timer circuit 14 is composed of a CR timer, it takes several hundred milliseconds until the reset signal is output from the relay contact detection circuit 13 and the timer circuit 14 is completely reset. Therefore, a delay of several seconds is taken in S12. . Regarding the detection of the count-up of the timer circuit 14, when the triac 27 is turned on, the electrodes of the heat-sensitive heater are short-circuited in the positive cycle of the AC power supply, and the phase shift in the positive cycle of the temperature signal disappears as shown in FIG. 4d.
The timer circuit count-up detection is performed by detecting the presence or absence of this positive cycle phase shift.

FIG. 6 shows a circuit diagram of another embodiment of the present invention in which two heat-sensitive heaters are provided in the carpet body and two zones are switched and used. The relay drive circuit, the relay, the heat-sensitive heater, the relay contact detection circuit, and the temperature detection circuit are respectively provided in two circuits, and the timer circuit has two inputs and is configured as an AND. Temperature signal uses high temperature zone data for temperature control and relay ON,
Turn off at the same time. In addition, two switches for zone switching are added to the switch circuit.

EFFECTS OF THE INVENTION As is apparent from the above, according to the present invention, the control unit always operates as the switch element detection unit and the timer unit by configuring the operations of the control unit, the switch element, the switch element detection unit, the timer unit and the security unit in a loop. It is possible to monitor the abnormality of the security section, and on the contrary, the security section can monitor the abnormality of the control section and the switch element, while taking advantage of the cost advantage, it has a fail-safe level comparable to the two-wire system. An electric carpet can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a temperature control mechanism of a floor heating apparatus according to an embodiment of the present invention, FIG. 2 is a circuit diagram thereof, and FIG. 3 is a part of software incorporated in the microcomputer mainly relating to temperature control. A flow chart, FIG. 4 is a time chart for explaining the temperature detection operation and the timer count-up detection operation, FIG. 5 is a characteristic diagram of the same thermal heater, and FIG. 6 is a floor heating in another embodiment of the present invention. FIG. 7 is a circuit diagram when the apparatus body is divided into two zones. 4 ... Microcomputer, 8 ... AC power supply synchronization detection circuit, 9 ... Temperature detection circuit, 10 ... Thermal heater, 11 ...
Relay, 12 …… Relay drive circuit, 13 …… Relay contact detection circuit, 14 …… Timer circuit, 15 …… Security circuit.

Claims (2)

[Claims] 1. A heat-sensitive heater comprising a first electrode and a second electrode, which function as a heater, and a polymer whose impedance changes with temperature, and a floor heating apparatus main body having the heat-sensitive heater built-in. A bidirectional switch element that is connected in series to the heater and controls energization of the heater, a temperature fuse that is connected in series to the heater and the bidirectional switch element, and an impedance of the heat-sensitive heater from the second electrode. A temperature detector for detecting changes,
A temperature setting unit that sets the temperature of the main body of the floor heating device, a safety unit that is thermally connected to the temperature fuse and heats the temperature fuse to cut off the power supply to the heater, and a constant from when the switch element is turned on. After a lapse of time, a timer unit that drives the safety unit, and a signal from the temperature detection unit and a signal from the temperature setting unit after detecting the drive of the safety unit and immediately turning off the bidirectional switch element after a certain delay. When the temperature of the main body of the floor heating device becomes lower than the temperature set in the temperature setting unit, the bidirectional switch element is turned on, and if the drive of the security unit is not detected for a certain time or more, the security A temperature control unit that drives the control unit and keeps the bidirectional switch element in the off state, and resets the timer unit by detecting the off state of the bidirectional switch element. Floor heating device composed of switching element detection unit over's to stop driving of the security unit before fusing. 2. The floor heating system according to claim 1, wherein the control unit is composed of a microcomputer.