JPH04289683A - Abnormality detection device for heating equipment - Google Patents

Abstract

PURPOSE:To provide an abnormality detecting device of a heating equipment having safety and reliability able to detect not only a short-circuit current but also abnormal temperature by detecting a leakage current and having high safety and reliability able to correctly detect this abnormal temperature in the heating equipment having a facial heater and a conductive sheet for detecting a short circuit. CONSTITUTION:In a heating equipment provided with a facial heater H, a conductive sheet ES and a temperature detecting means 6, a leakage current detecting means P detecting a leakage current while being connected to the conductive sheet ES and a control means 7 connected to the output of this leakage current detecting means P, the temperature detecting means 6 and a conduction control means SR are provided. This control means 7 outputs a conduction control signal to the conduction control means SR by a temperature signal from the temperature detecting means 6 while opening a switch S2 for emergency when a detection signal of the leakage current detecting means P is obtained. Further, the leakage current detecting means P is provided with a thermistor Th for temperature correction for making correct detection.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device using a planar heater, and more particularly to an abnormality detection device for a heating device that detects abnormal conditions.

0002

2. Description of the Related Art A conventional abnormality detection device for a sheet heating element, as shown in Japanese Utility Model Publication No. 52-40447, has a main body in which a temperature sensing electrode is provided on a sheet heater through a heat-sensitive member. A short-circuit current detection electrode plate (conductive sheet) is provided on a planar heater via a heat-sensitive member.

[0003]The level discrimination circuit (control means) detects the temperature near the heater from the resistance value of the heat-sensitive member from the sheet heater, and controls the supply of electricity to the sheet heater. Further, the level discrimination circuit (control means) is configured to stop energizing the planar heater when a short circuit current is detected from the short circuit current detection electrode plate (conductive sheet).

[0004] Furthermore, since the adjustment means (resistance) for detecting the short circuit current and the adjustment means (resistance) for controlling the energization to the sheet heater are configured separately, it is possible to detect even minute values of the short circuit current. It is something.

[0005]

[Problems to be Solved by the Invention] However, with conventional abnormality detection devices, if a problem such as a poor contact occurs in the temperature detection part during normal use, and an abnormal temperature rise occurs in the sheet heater, the heat-sensitive member The resistance value decreases as the temperature rises, but this resistance value is at a different level from the resistance value in a short circuit state when a pin etc. is inserted. Otherwise, it cannot be determined that the current is abnormal. In other words, the short circuit current detection electrode plate (
The structure of the conductive sheet (conductive sheet) part is such that it can only detect a current value level that is about the same as a short-circuit current, so there was a problem that the sheet heater would not operate at abnormal temperatures unless it generated heat to the extent that it would cause burns.

[0006] In particular, with regard to this abnormal temperature, a highly safe abnormality detection device is desired.

The present invention has been made in view of these points, and even if a malfunction such as poor contact occurs in the temperature sensing part, the short circuit current sensing electrode plate (conductive sheet) will not only prevent short circuit current but also abnormal temperature. It is an object of the present invention to provide a highly safe and reliable abnormality detection device for heating equipment that can also detect abnormal temperatures.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the heating equipment abnormality detection device of the present invention includes a sheet heater connected to a power source via a power switch, an emergency switch, and an energization control means. , a conductive sheet disposed parallel to the sheet heater via an insulating member, a temperature detection means for detecting the temperature near the sheet heater, and a temperature detection means connected to the conductive sheet for detecting leakage current. and a control means connected to the output of the leakage current detection means, the temperature detection means, and the energization control means, and this control means responds to the temperature signal from the temperature detection means. Then, an energization control signal is output to the energization control means to control the temperature of the sheet heater, and the emergency switch is opened when a detection signal from the sheet leakage current detection means is obtained.

Furthermore, a thermistor for temperature correction is connected to the leakage current detection means of the temperature detection means of the heating device.

0010

According to the above structure, in normal use, the control means controls the temperature of the planar heater in response to the temperature signal detected by the temperature detection means. In addition, if an abnormal temperature rise occurs in the sheet heater due to a poor contact of the temperature detection means, etc., the control means will control the leakage current between the conductive sheet and the sheet heater detected by the leakage current detection means at the abnormal temperature. Open the emergency switch in response.

Furthermore, since the current detected by the leakage current detection means varies depending on the room temperature, the temperature detected by the leakage current detection means is kept constant by providing a thermistor whose resistance value changes in response to this change.

0012

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

First, in FIG. 2, reference numeral 4 denotes a rectangular heating device main body, to which a controller 2 housing control means, leakage current detection means, etc., which will be described later, is connected via a connector 3. 1 is a power plug for supplying commercial AC power.

The structure of the heating device main body 4 is rectangular as shown in the sectional view taken along line AA in FIG. 2 shown in FIG.
A planar heater H having approximately the same area as the planar heater H, and a conductive sheet ES made of aluminum foil, for example, having the same shape and approximately the same area as the planar heater H, are each wrapped with vinyl chloride 5, which is an insulating member. The thermosensitive wire 6, which serves as a temperature detection means, is adhered in a meandering manner from the back side. Although not shown, the heat-sensitive wire 6 may be covered with a heat insulating material.

Here, the heat-sensitive wire 6 has a core wire W in the center, a first electrode E1 is wound around the core wire W, and a resistance is changed around the first electrode E1 depending on the temperature. A heat-sensitive layer X whose value changes is provided, a second electrode E2 is wound around this heat-sensitive layer X, and it is further covered with a jacket K of vinyl chloride or the like.

Next, the circuit configuration will be explained.

In FIG. 1, AC is a commercial AC power supply, and this commercial AC power supply AC is equipped with a temperature fuse TF and a power switch S.
1. A planar heater H is connected via an emergency switch S2 and a bidirectional three-terminal thyristor SR, which is a means for controlling energization.

7 is a control means, and this control means 7
has a configuration in which approximately 5V power is supplied to input ports P1 and P2 from between power switch S1 and emergency switch S2 via varistor VR for overvoltage prevention, capacitor C for noise prevention, and transformer T. It has become. Note that the control means 7 has a built-in rectifier circuit.

The heat sensitive wire 6 is connected in parallel with a correction resistor R1, further connected to a voltage dividing resistor R2, and connected to a port P7 of the control means 7. Note that port P10 is connected to ground.

Further, the port P3 is connected to the gate of the bidirectional three-terminal thyristor SR, and the bidirectional three-terminal thyristor SR controls the energization to the sheet heater H by the trigger output of the port P3. be.

Further, port P6 is connected to a 100V power supply line via heat generating resistor R3, and when an abnormality is detected, port P6 outputs an output, causing heat generating resistor R3 to generate heat and blowing out thermal fuse TF. It becomes.

The commercial AC power supply AC includes diodes D1 and D2 with cathodes facing each other, and a resistor R4 provided between them.
A rectifier circuit consisting of R5 is connected to this output, and the light emitting diode side of the photocoupler P, which is a leakage current detection means, is connected to this output.
A resistor R6 for shunting and a thermistor Th for temperature correction based on temperature are connected in parallel, and further connected to the conductive sheet ES via a resistor R7 for current adjustment. The output side of the photocoupler P is connected to ports P4 and P5 of the control means 7.

Note that 8 is a relay coil connected to port P8 and port P9, and when an abnormality is detected, a signal is output from port P8 and port P9, and the relay coil 8 is energized to control the opening of emergency switch S2. The configuration is as follows.

[0024] The operation of the above structure will be explained.

First, in normal operation, the power switch S1
When the set temperature is set using a switch (not shown), the control means 7 energizes the planar heater H and closes the port P.
The temperature detection signal from the heat-sensitive wire 6 input to 7 triggers output from port P3 to bring the temperature near the planar heater H to the set temperature, and turns on the bidirectional three-terminal thyristor SR.
Control off.

Here, the planar heater H and the conductive sheet ES
have substantially the same shape, and are insulated with vinyl chloride 5. Therefore, the configuration is equivalent to a capacitor having structural capacitance.

As shown in FIG. 4, the leakage current characteristics of the planar heater H and the conductive sheet ES with respect to temperature are approximately 0.01 mA at 20° C. and approximately 0.1 mA at 80° C. The resulting characteristic curve is In addition, the operating current of the photocoupler P is 0.1mA-0.9V as shown in Figure 5.
Since the operation starts from
In the range of 50°C to 50°C, the operating current does not reach 0.1 mA and the device does not operate.

[0028] Here, the heat-sensitive wire 6 causes poor contact, etc.
If a failure occurs such that an appropriate detection signal is not sent to the control means 7, the control means 7 determines that the set temperature has not been reached and continues to energize the sheet heater H, causing the temperature to reach an abnormally high temperature. I end up.

However, as shown in FIG. 4, when the temperature between the sheet heater H and the conductive sheet ES reaches 80° C., a leakage current of about 0.1 mA occurs, and the operating current (0
．． 1 mA), photocoupler P operates and current flows to ports P4 and P5. Then, the control means 7 determines that the planar heater H is at an abnormal temperature, and the port P
Bidirectional three-terminal thyristor SR turns off the trigger output of 3.
At the same time as stopping the power supply control of port P8 and port P
9 opens the emergency switch S2 by energizing the relay coil 8.

For example, if the emergency switch S2 or the like is malfunctioning and continues to be energized even though it is in an abnormal state, the control means 7 may cause the control means 7 to ``turn off the energization to the relay coil 8 from ports P8 and P9. Since the "output" and "leakage current status" are compared, if it is determined that a leakage current is detected even though the output is being made to the relay coil 8, the leakage current is transferred from the port P6 to the heating resistor R3. Since the thermal fuse TF is blown by outputting the following, it is extremely safe.

Furthermore, with this configuration, not only an abnormal temperature but also a short circuit caused by a pin or the like being stuck in the sheet heater can be immediately detected and the energization can be stopped. In addition, it can detect short-circuit currents as low as 0.1mA, so if a pin or similar object is inserted into the sheet heater, the current will immediately stop flowing, so there is no risk of electric shock, making it an extremely safe heating device. It is possible to provide an abnormality detection device.

By the way, the photocoupler P has the characteristics shown in FIG. 5 when the room temperature is constant at, for example, 25° C. However, for example, when the room temperature is low, the operating current increases, and when the room temperature is high, the operating current decreases. , the leakage current is a predetermined value (
Errors occur due to changes in room temperature, such as not operating even when a current value equivalent to 80° C. is reached, or operating before a predetermined value.

This error is corrected using a thermistor Th having a negative characteristic for temperature correction. In other words, the current flowing through the photocoupler P is adjusted by increasing the resistance value when the indoor temperature is low and decreasing the resistance value when the indoor temperature is high, so that the temperature of the planar heater H is kept constant at, for example, 80°C. It is designed to always work.

Therefore, the photocoupler P is not affected by changes in room temperature, and the planar heater H always operates at a predetermined temperature, resulting in higher safety.

It should be noted that the present invention is not limited to the above-mentioned embodiment; the control means may be an electronic circuit or a microcomputer, and the leakage current detection means may be not only a photocoupler but also a device having the function of performing low current switching. Furthermore, even if the sheet heater has meandering wiring, there is a current of about 0.1 mA between the conductive sheet and the sheet heater (
Any structure may be used as long as it forms a capacitance that generates a leakage current (at abnormal temperatures), and may be modified as appropriate without departing from the spirit of the invention.

[0036]

[Effects of the Invention] Abnormal conditions are detected based on changes in leakage current between the conductive sheet and the sheet heater due to temperature, and the current supply is stopped, making it possible to detect not only short-circuit currents but also abnormal temperatures. It is possible to provide a highly safe and reliable abnormality detection device for heating equipment that can accurately detect.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of the heating device of the present invention.

FIG. 3 is a sectional view taken along line AA of the heating device shown in FIG. 2 of the present invention.

FIG. 4 is a temperature characteristic diagram of leakage current in the heating device of the present invention.

FIG. 5 is a characteristic diagram of operating current in the leakage current detection means of the present invention.

[Explanation of symbols]

S1 Power switch S2 Emergency switch SR Current control means H Planar heater 5 Insulating member (vinyl chloride) ES Conductive sheet 6 Temperature detection means (thermal wire) P Leakage current detection means (photocoupler) 7
Control means Th thermistor

Claims (2)

[Claims] [Claim 1] A planar heater connected to a power source via a power switch, an emergency switch, and energization control means;
A conductive sheet disposed parallel to the sheet heater via an insulating member, a temperature detection means for detecting the temperature near the sheet heater, and a means for detecting leakage current connected to the conductive sheet. a leakage current detection means, an output of the leakage current detection means, a control means connected to the temperature detection means and the energization control means, and this control means responds to the temperature signal from the temperature detection means. The heating system is characterized in that the temperature of the sheet heater is controlled by outputting an energization control signal to the energization control means, and the emergency switch is opened when a detection signal from the sheet leakage current detection means is obtained. Equipment abnormality detection device. 2. The abnormality detection device for a warming device according to claim 1, wherein a thermistor for temperature correction is connected to the leakage current detection means.