JPH03216984A - Electric heater - Google Patents

Abstract

PURPOSE:To prevent the noise generated by a heater wire caused by phase control from being leaked to the outside and prevent an adverse effect on an acoustic apparatus by providing a damping circuit to damp the noise generated by the heater wire caused by AC phase control, and connecting one end of a heater abnormal temperature sensor wire to the damping circuit. CONSTITUTION:A heater wire 22 is wound on a heater core 21, its periphery is covered with an insulating layer 23 made of a fused material, a heater abnormal temperature sensor wire 24 is wound on the insulating layer 23, and its periphery is covered with an outer film 25 made of an insulator to constitute a cord-shaped heating element 2. A damping circuit 14 to damp the noise generated by the heater wire 22 caused by AC phase control is provided, and one end of the heat abnormal temperature sensor wire 24 is connected to the damping circuit 14. The noise generated by the heater wire 22 caused by phase control can be prevented from being leaked to the outside, and an adverse effect on an acoustic apparatus can be prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to electric heaters such as electric carpets and electric blankets, and particularly relates to a method for controlling the phase of alternating current supplied to a cord-shaped heating element. This invention relates to an electric heater that adjusts the temperature by adjusting the temperature.

(Prior Art) Generally, this type of electric heater is formed by laying cord-shaped heating elements having heater wires distributed over almost the entire surface of a flat heater body.

It is known that the temperature is adjusted by controlling the phase of the alternating current supplied to the cord-shaped heating element. Specifically, a heater wire is connected to an AC power source via a three-terminal bidirectional thyristor, and a temperature control 1c (integrated circuit) controls the conduction time of the thyristor to vary the amount of current to the heater wire. By doing so, the temperature is regulated.

However, in this case, noise is generated from the heater wire when the thyristor is turned on, and this heater wire becomes a noise generation source that has an adverse effect on audio equipment such as radios and televisions mounted on the main body of the heater.

(Division to be solved by the invention) As mentioned above, in an electric heater that adjusts the temperature by controlling the phase of alternating current supplied to the cord-shaped heating element, the heater wire generates noise due to the phase control. Become a source,
This was having a negative effect on the audio equipment on the heater itself.

The present invention has been made based on the above circumstances, and provides an electric heater that can prevent noise generated from the heater wire due to phase control from leaking to the outside, and can eliminate adverse effects on audio equipment, etc. This is what we are trying to provide.

[Structure of the Invention] (Means for Solving the Problems) The electric heater of the present invention includes a cord-shaped heating element between a heater wire and a heater abnormal temperature sensor wire wrapped around the outside of the heater wire. It is constructed by interposing an insulating layer made of molten material,
In addition, a damping circuit is provided for damping noise generated from the heater wire by AC phase control, and one end of the heater abnormal temperature sensor wire is connected to the damping circuit.

(Function) By taking such measures, the noise generated from the heater wire due to AC phase control is received by the heater abnormal temperature sensor wire wrapped outside the theta wire, and the noise generated from the heater wire is received by the heater abnormal temperature sensor wire wrapped outside the theta wire. It is led through the line to an attenuation circuit where it is attenuated.

(Example) Hereinafter, an example in which the present invention is applied to an electric car bed will be described with reference to the drawings.

FIG. 2 is a conceptual diagram of an electric carpet, in which a cord-shaped heating element 2 and a sensor wire 3 are attached distributed over almost the entire surface of a flat-plate-shaped carpet body 1. Further, in one corner of the car bed body 1, there is provided a controller 4 which is equipped with operation parts such as an operation switch and a temperature setting volume, and which is connected to the cord-shaped heating element 2 and sensor wire 3 to perform temperature control. There is. Above controller 4
A commercial power plug 5 is connected via a cable 6 to.

As shown in FIG. 3, the cord-shaped heating element 2 is constructed by winding a heater wire 22 around a heater core 21 and covering the periphery with an insulating layer 23 made of a molten material. The abnormal temperature sensor wire 24 is wound around the heater abnormal temperature sensor wire 24, and the periphery thereof is covered with an outer skin 25 made of an insulating material.

The sensor wire 3 is made of an insulator whose impedance changes depending on the temperature, and the controller 4 can detect the heating temperature of the carpet body 1 based on the output signal from the sensor wire 3.

FIG. 1 is an electric circuit diagram of the electric carpet, in which an AC power source 10, an operation switch 11, a fuse 12 for preventing excessive temperature rise, a heater wire 22 constituting the cord-shaped heating element 2, and both three terminals are shown. The facing thyristor 13 is coiled,
A closed circuit is formed by sequentially connecting switches 11' in series that turn on/off in conjunction with the operation switch 11.

In addition, the heater wire 22 and the three-terminal bidirectional thyristor 13
A capacitor C1 and a series circuit of capacitors C2 and C3 are connected in parallel to the series circuit of the inductor L. Therefore, each of the above capacitors C
I, C2, C3 and the coil L, the AC power source 1
A damping circuit 14 is configured to damp noise generated from the heater wire 22 by controlling the phase of alternating current from zero. That is, each capacitor CI. C2. The capacitance and inductance of C3 and coil L are adjusted to the harmonic frequency value of the high frequency component to be attenuated.

Reference numeral 15 in FIG. 1 indicates a control ICl constituting the main body of the control section.
(product circuit) and is built into the controller 4.

A signal from the sensor wire 3 is input to this control IC 15. Further, a temperature setting volume 16 and a fuse blowing resistor 17 are respectively connected. Furthermore, a signal for phase control is outputted to the gate G of the three-terminal bidirectional thyristor 13.

On the other hand, one end of the heater abnormal temperature sensor wire 24 constituting the cord-shaped heating element 2 is connected to the control ICl5, and the capacitor C2 constituting the attenuation circuit 14
and a common connection point between the capacitor C3 and the capacitor C3.

In the electric carpet having such a configuration, the power plug 5 is connected to a commercial power outlet and the operation switch 11 is turned on.
By turning on, the AC power source 10 is connected to the heater wire 22, the heater wire 22 is heated, and heating is performed. At this time, the temperature of the carpet body 1 is detected by the sensor wire 3 and electrically input to the control IC 15. The control IC 15 compares the temperature detected by the sensor wire 15 with the set temperature electrically set by the temperature setting volume 16, and outputs a gate signal to the three-terminal bidirectional thyristor 13 according to the comparison result. controlled. As a result, the optimum time of the three-terminal bidirectional thyristor 13 is varied, the phase of the alternating current is controlled, and the temperature of the heater wire 22 and, in turn, the carpet body 1 is adjusted.

In this state, the heater l! 22 is abnormally heated to a high temperature, the insulating layer 23 made of a molten material coated on the heater wire 22 melts, and the heater clamp 22 comes into contact with the heater abnormal temperature sensor wire 24 wrapped around the outside. As a result, an abnormality signal is input from the sensor 24 to the control IC 15, and the control IC 15 energizes the resistor 17 and blows the fuse 12. Thus, the AC power source 10 is cut off from the heater wire 22, and heating of the heater #s22 is stopped.

On the other hand, noise is generated from the heater wire 22 due to AC phase control through conduction control of the three-terminal bidirectional thyristor 13, but the noise generated by the heater [22] is caused by the noise generated by the heater fIA22. It is received by the heater abnormal temperature sensor wire 24. The output of this sensor 24 is then led to the attenuation circuit 14, and the high frequency component is cut off by the action of this attenuation circuit 14.

Therefore, noise generated from the heater wire 22 due to AC phase control through conduction control of the three-terminal bidirectional thyristor 13 is absorbed by the heater abnormal temperature sensor wire 24 and attenuated by the attenuation circuit 14 without leaking to the outside. As a result, even if audio equipment such as a radio or television is installed on an electric carpet whose temperature is adjusted by alternating current phase control, the adverse effects of noise caused by phase control can be prevented.

Note that the present invention is not limited to electric carpets, but can be applied to electric heaters such as electric blankets and futons in which cord-shaped heating elements are distributed over almost the entire surface of a flat heater body. Of course.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to prevent noise generated from the heater wire due to phase control from leaking to the outside, and to eliminate adverse effects on audio equipment, etc. You can provide an electric heater.

[Brief explanation of drawings]

The figures show an example in which the present invention is applied to an electric carpet. Fig. 1 is a circuit diagram of the electric carpet, Fig. 2 is a conceptual diagram of the electric carpet, and Fig. 3 is a cord-shaped heating element. It is a structural diagram. 1... Car bed main body, 2... Cord-shaped heating element, 3
...Sensor wire, 4...Controller, 0...
AC power supply, 11... Operation switch, 3... 3-terminal bidirectional thyristor, 14... Attenuation circuit, 5... Control IC (integrated circuit), 6... Temperature setting volume, 22...・Heater wire,
3... Insulating layer, 24... Heater abnormal temperature sensor wire.

Claims (1)

[Scope of Claims] An electric heater that adjusts the temperature by controlling the phase of alternating current supplied to cord-shaped heating elements distributed over almost the entire surface of a flat heater body, comprising: The heating element has an insulating layer made of a molten material interposed between the heater wire and a heater abnormal temperature sensor wire wrapped around the outside of the heater wire, and the heater wire is heated by controlling the phase of the alternating current. An electric heater characterized in that an attenuation circuit for attenuating generated noise is provided, and one end of the heater abnormal temperature sensor wire is connected to the attenuation circuit.