JPH05248650A - Controller of electric carpet - Google Patents

Abstract

PURPOSE:To immediately detect troubles of a safety circuit and a relay without permitting set temperature to be varied even with varied power supply voltage, and prevent an electric carpet from being erroneously operated even if it is heated, in the intreruption of power supply to heaters, by another heater. CONSTITUTION:There are provided a safety circuit 24 including a heater 2, a temperature fuse 3, a heat sensitive member 5, a relay contact 9, a temperature fuse heater 4, and a thyristor 6 all connected in series, monitor means 30 parallely connected with the thyristor 6, and a control part 40. The control part 40 issues a check signal VG for switching the thyristor 6 on and off in a predetermined pattern to the thyristor 6, and causes the monitor means 30 to generate a DC voltage signal VE which is in turn fed back to the control part 40.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a control device for an electric carpet.

[0002]

2. Description of the Related Art A conventional controller for an electric carpet (hereinafter referred to as "conventional device") will be described below with reference to the drawings. FIG. 6 is an electric circuit diagram of a conventional device.

In the conventional device, a heating element 2 provided in an electric carpet body 1 (hereinafter referred to as "main body 1"), a temperature fuse 3 connected in series to the heating element 2, and a temperature fuse for heating and melting the temperature fuse 3 are used. It includes a heating element 4, a heat sensitive element 5 arranged in the vicinity of the heating element 2 and made of a negative characteristic thermistor for detecting the temperature of the heating element 2, a thyristor 6 as a second switching element, and a control section 7. There is. Each of the temperature fuses 3 and a power source 8 connected in series to the temperature fuse 3 is composed of four branch circuits connected in parallel.

In the first branch circuit 21, a relay contact 9 as a first switching element is connected in series to the heating element 2. In the second branch circuit 22, a voltage dividing resistor 19 is connected in series to the heat sensitive body 5. The controller 7 is connected to the third branch circuit 23. A thermal fuse heater 4 is provided in the fourth branch circuit.
And the thyristor 6 are connected in series, and these constitute the safety circuit 24.

The thermal fuse heater 4 is integrally formed with the thermal fuse 3 by molding or the like and is thermally coupled to the thermal fuse 3, and the thermal fuse 3 is constructed so that the thermal fuse 3 is blown by the heat generated by the thermal fuse heater 4. ..

The control unit 7 is composed of a microcomputer including an A / D input / output unit, and a DC voltage divided by a voltage dividing resistor 10 and smoothed by a capacitor 14 via a diode 13 is used as an input voltage signal VA.
Has been entered as. Further, the control unit 7 is configured to output a relay operation signal for operating the relay solenoid 12 via the transistor 11 and a gate signal for opening / closing the gate G of the thyristor 6.

Next, the operation of the conventional device will be described.
The temperature of the heating element 2 is converted into a voltage signal by the heat sensitive element 5 and is monitored by the control section 7 as the input voltage signal VA. When the input voltage signal VA is smaller than the reference voltage signal VB preset by the controller 7, the transistor 11
Is turned on to energize the relay solenoid 12, the relay contact 9 is turned on to energize the heating element 2, and the temperature of the main body 1 rises.

When the temperature of the heating element 2 rises, the temperature of the heat sensitive body 5 also rises accordingly. As a result, the impedance of the heat sensitive body 5 decreases and the input voltage signal VA increases. When the input voltage signal VA exceeds the above described voltage signal VB, the control unit 7 turns off the transistor 11. As a result, the relay solenoid 12 is turned off, the relay contact 9 is opened, and the power supply to the heating element 2 is stopped. As a result, the temperature of the main body 1 is lowered and the temperature of the heat sensitive body 5 is also lowered.
When the impedance of the heat sensitive body 5 increases and the input voltage signal VA decreases and becomes smaller than the reference voltage signal VB, the transistor 11 is turned on again and the heat generating element 2 is energized. By repeating the above, the main body 1 is maintained in a constant temperature range.

Further, in order to prevent the heating element 2 from being continuously energized and overheated when a failure occurs such as the transistor 11 being short-circuited or the relay contact 9 not being opened, the voltage is higher than the reference voltage signal VB. The second reference voltage signal VC is set. Then, when the input voltage signal VA becomes larger than the second reference voltage signal VC, the control unit 7 gives a gate signal to the thyristor 6 to turn on the thyristor 6 to energize the thermal fuse heating body 4 to generate heat, thereby causing the thermal fuse. 3 is heated and melted, and the heating element 2 is de-energized. In this way, the safety circuit 24 prevents the heating element 2 from overheating.

[0010]

However, the conventional device has a problem that the set temperature of the main body 1 changes due to the fluctuation of the power supply voltage VD. That is, when the power supply voltage VD becomes higher than in the normal state, the input voltage signal VA also becomes higher. On the other hand, the reference voltage signal VB is the power supply voltage V
It is kept constant regardless of the height of D. Therefore, the time required for the input voltage signal VA to reach the reference voltage signal VB becomes faster than in the normal time, and the energization time of the heating element 2 also becomes shorter. Therefore, the temperature of the main body 1 also becomes lower than the set temperature at the normal time.

On the other hand, when the power supply voltage VD becomes smaller than that at the normal time, the input voltage signal VA also becomes lower and the reference voltage signal V
The time to reach B becomes slower than in the normal state, and the energization time of the heating element 2 also becomes longer. Therefore, the temperature of the main body 1 also becomes higher than the set temperature at the normal time.

The safety circuit 24 also has the following problems. One of them is that if either the thyristor 6 or the thermal fuse heater 7 fails, the failure cannot be found from the external appearance. Therefore, when an abnormality occurs in the main body 1, the thermal fuse 3 cannot be blown, and there is a risk of causing a fire or the like. In addition, the other one is that, when another heater such as Yagura Kotatsu is used on the main body 1, the temperature of the heat sensitive body 5 rises even though the heating element 2 is de-energized by the heat thereof. .. Then, the impedance of the heat sensitive body 5 decreases, the input voltage signal VA increases, and the second
When the reference voltage signal VC is exceeded, the thyristor 6 is energized and the thermal fuse heating body 4 is energized to generate heat, which causes an erroneous operation in which the thermal fuse 3 is heated and melted.

The present invention has been devised in view of the above circumstances, and makes it possible to immediately detect a failure in the safety circuit and the relay without changing the set temperature even if the power supply voltage changes, and to make the heating element It is an object of the present invention to provide a control device for an electric carpet that does not malfunction even if it is heated by another heating body while the energization is stopped.

[0014]

According to a first aspect of the present invention, there is provided a control device for an electric carpet in which a heating element provided in an electric carpet body, a temperature fuse connected in series with the heating element, and a temperature fuse connected in series. Further, a heat sensitive body which is arranged in the vicinity of the heat generating body and detects the temperature of the heat generating body, a first switching element which is connected in series to the heat generating body and controls energization of the heat generating body, and a temperature fuse which heats and melts the temperature fuse A safety circuit formed by connecting in series a heating body and a second switching element for turning on / off the power supply to the thermal fuse heating body, and a second switching element which is connected in parallel with the second switching element and is turned on. It is provided with a monitor means for detecting OFF and a control section, and the control section turns on the second switching element in a predetermined pattern.
A check signal for turning off is given to the second switching element to generate a direct current voltage signal in the monitor means, and the direct current voltage signal is fed back for input.
And the reference voltage signal preset according to the DC voltage signal that changes due to fluctuations in the power supply voltage is increased or decreased, and the energization of the heating element is turned off based on the increased or decreased reference voltage signal, depending on the presence or absence of the DC voltage signal. It is designed to turn on / off the power supply to the heating element by judging the failure of the safety circuit.

According to a second aspect of the present invention, there is provided a control device for an electric carpet in which a heating element provided in the main body of the electric carpet, a temperature fuse connected in series with the heating element, and a heating element connected in series with the temperature fuse. A heat sensitive element that is arranged in the vicinity of the heat sensing element for detecting the temperature of the heat generating element, and a first switching element that is connected to the heat generating element in series and that controls energization of the heat generating plate
A safety circuit formed by serially connecting a thermal fuse heating body that heats and melts the thermal fuse and a second switching element that controls energization of the thermal fuse heating body, and is connected in parallel to the second switching element. Monitor means and a control part, and the monitor means divides the divided voltage of the second switching element into a first voltage through a diode.
Is configured to monitor the operating states of the first switching element and the second switching element at the same time by inputting the check signal to the second switching element in a predetermined pattern. Is supplied to the second switching element to generate a DC voltage signal in the monitor means, the DC voltage signal is fed back and input, and is preset according to the DC voltage signal that changes according to fluctuations in the power supply voltage. The generated reference voltage signal is increased / decreased, the energization of the heating element is controlled on the basis of the increased / decreased reference voltage signal, and the failure of the safety circuit and the first switching element is determined by the presence / absence of the DC voltage signal. Power is turned off.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electric carpet control device according to claim 1 (hereinafter referred to as "device of the present invention") with reference to the drawings.
An example will be described.

FIG. 1 is an electric circuit portion of the device of the present invention according to claim 1, FIG. 2 is a check signal waveform diagram, and FIG. 3 is a DC voltage signal waveform diagram. It should be noted that substantially the same parts as those of the conventional one will be denoted by the same reference numerals and will be described.

The device of the present invention comprises a heating element 2 and a thermal fuse 3.
It includes a temperature fuse heating body 4, a heat sensitive body 5, a thyristor 6, a monitor means 30, and a control section 40. Monitor means
Parts other than 30 are electrically connected in the same manner as the conventional device, and the branch circuit 21 is connected in series with the heating element 2 and the relay contact 9 as the first switching element.
A thyristor 6 as a second switching element and a temperature fuse heating element 4 are connected in series to 24 to form a safety circuit 24.

The monitor means 30 includes a voltage dividing resistor 31 and a voltage dividing resistor 32.
And a fifth branch circuit 33 in which the limiting resistor 34 and the contact 35 are connected in series, and a fifth branch circuit 33
It includes a diode 37 connecting the intermediate connection points of the branch circuits 33 and 36. The fifth branch circuit 33 is connected between the anode and the cathode AK of the thyristor 6, and the sixth branch circuit 36 is connected in parallel to the control unit 40.

The half-wave voltage generated between A and K of the thyristor 6 is divided by the voltage dividing resistors 31 and 32, rectified and smoothed by the diode 37 and the capacitor 35 and converted into a DC voltage signal VE, which is then sent to the control unit 40. It is configured to be input as feedback.

The control section 40 is adapted to increase or decrease the reference voltage signal VB according to the value of the DC voltage signal VE. In addition, as shown in FIG. 2, the control unit 40 outputs a check signal V having a pattern of a period of time T1 and a pulse width T2.
G is given to the gate G of the thyristor 6, and the thyristor 6 has a time T corresponding to the pulse width of the check signal VG.
Only 2 is turned on.

When the thyristor 6 is turned on, the monitor means
The voltage applied to 30 is bypassed to zero and the controller
As shown in FIG. 3, the DC voltage signal VE is not input to 40. Then, after the lapse of time T2, the thyristor 6 is turned off, and the DC voltage signal VE is input to the control unit 40 again.

The time T2 is set so that the thyristor 6 is turned on so that the thermal fuse 3 does not melt even if the thermal fuse heater 4 is heated.

Next, the operation of the device of the present invention according to claim 1 for the fluctuation of the power supply voltage, which is the first function, will be described. When the power supply voltage VD is normal, the temperature of the heating element 2 is input as the input voltage signal VA from the heat sensitive element 5 to the control unit 40 as in the conventional device. Further, the DC voltage signal VE is inputted from the monitor means 30 to the control section 40. The controller 40 compares the DC voltage signal VE with the reference voltage signal VB, turns on / off the transistor 11 according to the magnitude of the DC voltage signal VE, and opens / closes the relay capacitor 9 to keep the temperature of the heating element 2 constant.

When the power supply voltage VD fluctuates and becomes higher than normal, the voltage between AK of the thyristor 6 also becomes high,
The DC voltage signal VE becomes large. In response to this, the reference voltage signal VB also increases. Therefore, it takes a long time for the input voltage signal VA to reach the reference voltage signal VB. That is, the energization time of the heating element 2 becomes longer, and the temperature of the main body 1 is raised to be corrected to the normal set temperature. When the power supply voltage VD becomes lower than normal, the reference voltage signal V
B also becomes smaller, and operates in reverse.

Next, the failure detection operation of the safety circuit, which is the second function of the device of the present invention, will be described. In the normal state, as shown in FIG. 3, the control unit 40 receives the DC voltage signal VE which is turned on for T1 time and turned off for T2 time, and operates as described in the above item.

If the temperature fuse heater 4 fails for some reason, no voltage is applied between the AK of the thyristor 6. Therefore, the DC voltage signal VE becomes zero.

When the thyristor 6 fails, the thyristor 6 does not turn on even when the check signal VG is given from the control unit 40. Therefore, from the monitor means 30, the DC voltage signal VE
Remains to be input to the control unit 40. That is, the state is not turned off for the time T2.

The control unit 40 determines the failure of the safety circuit based on the presence or absence of the DC voltage signal VE, turns off the transistor 11 and opens the relay contact 9.

Next, an embodiment of the device of the present invention according to claim 2 will be described with reference to the drawings. FIG. 4 is an electric circuit diagram of one embodiment, FIG. 5 (A) is an example waveform diagram of a DC voltage signal fed back to a control unit, and FIG. 5 (B) is an example of a DC voltage signal accompanying ON / OFF of a relay contact. It is a waveform diagram.

The present invention device according to claim 2 is the device according to claim 1, wherein an intermediate connection point between the resistor 31 and the resistor 32 and the relay contact 9 are electrically connected via a transistor 38. Therefore, the monitoring means 30 is configured to be able to simultaneously monitor the on / off operation states of the relay contact 9 and the thyristor 6. Since the first function and the second mechanism of the device of the present invention are the same as those of the device of the present invention according to claim 1, the description thereof will be omitted.

Next, the failure detecting operation of the relay contact, which is the third function of the device of the present invention, will be described. In the above-mentioned state, as shown in FIG. 5B, when the relay contact 9 is turned on for T3 time, the voltage generated across the resistor 32 is bypassed through the diode 38,
The potential of the DC voltage signal VE becomes low. On the contrary, when the relay contact 9 is turned off for T4 time, a voltage is generated across the resistor 32 and the potential of the DC voltage signal VE becomes high. That is, the ON / OFF operation state of the relay contact 9 can be detected by the potential of the DC voltage signal VE.

If the relay contact 9 is short-circuited or opened due to some cause and thus does not operate, the control unit
The potential of the DC voltage signal VE does not change even though the transistor 40 outputs an ON or OFF signal to the transistor 11. As a result, the control unit 40 causes the relay contact 9
Detect the failure of.

In this case, if the safety circuit 24 is operated via the control unit 40 only when the relay contact 9 fails, the control unit 40 causes the first and second safety circuits to operate.
Since it can be distinguished from the operation that is the function of, it is very convenient because it does not malfunction in the following cases. That is, when a heater such as Yagura Kotatsu is used on the main body 1, the temperature of the heat sensitive body 5 rises and the input voltage V increases even though the heating element 2 is de-energized by the heat of the heater.
It is possible to prevent a situation in which A exceeds the second reference voltage VC, the thyristor 6 is turned on, the thermal fuse heating body 4 is heated to generate heat, and finally the thermal fuse 3 is blown.

If the change or presence / absence of the DC voltage signal VE is displayed by a display means (not shown),
This is very convenient because the user can immediately know the failure of the safety circuit and relay contact. The configuration of the monitor means is not limited to this embodiment, and any device that operates similarly can be used.

[0036]

As described above, the invention device according to the first aspect comprises the heat sensitive body, the temperature fuse, the temperature fuse heating body, the first and second switching elements, the monitor means, and the control section. ing. Then, the control section gives a check signal for turning on / off the second switching element to the second switching element in a predetermined pattern to generate a direct current voltage signal in the monitor means, and feeds back the direct current voltage signal for input. I am letting you.

Then, the reference voltage signal is increased / decreased based on the one DC voltage signal to turn on / off the energization of the heating element, and the failure of the safety circuit is detected by the presence / absence of the DC voltage signal. .. Therefore, the fluctuation of the set temperature is suppressed by the fluctuation of the power supply voltage, which is very convenient. Further, since the failure of the safety circuit can be detected promptly, there is no danger of fire and the like, and the reliability can be improved.

In the invention device according to the second aspect, since the on / off operation of the first switching element is also monitored by the monitoring means, the failure of the relay contact can be quickly detected. Further, it is very convenient because it is possible to prevent the thermal fuse from being blown out due to heating from the outside due to the combined use with other heaters, even though the heating element is de-energized.

[Brief description of drawings]

FIG. 1 is a drawing according to claim 1 of the present invention, and is an electric circuit diagram of the device of the present invention.

FIG. 2 is a diagram according to claim 1 of the present invention, and is a check signal waveform diagram.

FIG. 3 is a diagram according to claim 1 of the present invention, and is a DC voltage signal waveform diagram.

FIG. 4 is a drawing according to claim 2 of the present invention and is an electric circuit diagram of the device of the present invention.

FIG. 5 is a drawing according to claim 2 of the present invention,
(A) is an exemplary waveform diagram of a DC voltage signal fed back to a control unit, and (B) is an exemplary waveform diagram of a DC voltage signal accompanying ON / OFF of a relay contact.

FIG. 6 is an electric circuit diagram of a conventional device.

[Explanation of symbols]

 1 Main body 2 Heating element 3 Thermal fuse 4 Thermal fuse heating element 5 Thermal element 6 Thyristor 9 Relay contact 11 Transistor 12 Relay solenoid 30 Monitoring means 31,32 Voltage dividing resistance 35 Capacitor 37,38 Diode 40 Control section VA Input voltage signal VB standard Voltage signal VE DC voltage signal VG check signal

Claims (2)

[Claims] 1. A heating element provided on an electric carpet body,
A thermal fuse connected in series with the heating element, a heat sensitive element connected in series with the thermal fuse and arranged in the vicinity of the heating element to detect the temperature of the heating element, and connected in series with the heating element to energize the heating element. A safety circuit in which a first switching element to be controlled, a thermal fuse heating body for heating and melting the thermal fuse, and a second switching element for turning on / off energization to the thermal fuse heating body are connected in series. A monitoring unit that is connected in parallel to the second switching element and detects ON / OFF of the second switching element; and a control unit, the control unit including the second switching element in a predetermined pattern. A check signal for turning on and off is given to the second switching element to generate a direct current voltage signal in the monitor means and the direct current voltage signal is fed. The reference voltage signal that has been input back and changes according to the DC voltage signal that changes due to fluctuations in the power supply voltage is increased or decreased, and the heating element is turned on or off based on the increased or decreased reference voltage signal. In addition, the control device for the electric carpet is characterized in that a failure of the safety circuit is judged depending on the presence or absence of the DC voltage signal to turn off the heating element. 2. A heating element provided in the electric carpet body,
A thermal fuse connected in series with the heating element, a heat sensitive element connected in series with the thermal fuse and arranged in the vicinity of the heating element to detect the temperature of the heating element, and connected in series with the heating element to energize the heating element. A first switching element for controlling, a temperature fuse heating body for heating and melting the temperature fuse, and a second for controlling energization of the temperature fuse heating body
A safety circuit consisting of a switching element connected in series,
The monitoring means is connected in parallel to the second switching element and the control section, and the monitoring means inputs the partial pressure of the second switching element to the first switching element via a diode. Is configured to simultaneously monitor the operating states of the first switching element and the second switching element, and the control unit sends a check signal for controlling the second switching element in a predetermined pattern to the second switching element. To generate a direct current voltage signal in the monitoring means, feed back the direct current voltage signal and input a reference voltage signal preset according to the direct current voltage signal that changes due to fluctuations in the power supply voltage. Increase or decrease, while controlling the energization of the heating element based on the increased or decreased reference voltage signal, the DC voltage signal Determining a failure of the safety circuit and the first switching element by the non-control device of an electric carpet, characterized in that so as to turn off the energization of the heating element.