JPH10144457A - Planar electric heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of magnetism from a heating element and enable abnormal heating of a heating wire to be certainly detected by providing in order an insulator, a detecting wire an insulator, second heating wire, and an insulation cover on a first heating wire wound around a winding core. SOLUTION: In a heating element 30 of a planar electric heater, a first heating wire 22 is spirally wound around a winding core 21 and further covered with an insulator 23. A temperature detecting wire 24 is wound around this insulator 23, short-circuits with the heating wire 22 when the insulator 23 is fused with an excessive heat, and operates a safety device. This temperature detecting wire 24 is covered with an insulator 25, on which a second heating wire 26 is wound and further covered with an insulation sheath 27. A connection point between the heating wire 22 and the second heating wire 26 is connected to a control circuit with the point being a turning point, a current flows the first heating wire 22 and in return from the connection point when electricity is conducted, the current flows a second heating wire 26, and a current in the reverse direction always flows the first and second heating wires 22 and 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater having a linear heating element formed by winding a heating wire around a core member, and heating the heating wire by controlling the power supply to the heating wire. It relates to an electric heater.

[0002]

2. Description of the Related Art A conventional electric heater will be described in the context of an electric carpet. The electric carpet has a heating element on a backing made of felt or the like having good heat insulation properties. In the case where the heat sensing element for detecting the temperature is a separate line, the heating element and the heat sensing element are arranged in a meandering shape, and the tufted outer cloth is adhered and fixed to the back cloth to form the heater body. A controller is provided at the outer surface corner of the heater main body, and a control circuit is provided in the controller to control the energization of the heating wires to control the surface temperature of the heater main body to a set temperature.

FIG. 7 shows a heating element 40 used in the electric carpet as a first conventional example. In FIG. 7, a heating wire 42 made of a copper alloy is spirally wound around a winding core 41 made of polyester or the like, and insulation made of nylon or the like is melted when the heating wire 42 is overheated due to an abnormal temperature rise. A detection wire 44 for detecting that the insulator has melted is spirally wound around the insulator 43, and the detection wire 44 is covered with an insulating jacket 45 made of heat-resistant vinyl chloride or the like. Was formed. In the case of a heating element having a detection line for temperature detection integrated therewith, it is also used as control temperature detection.

However, in the case of an electric carpet using the heating element 40 as shown in FIG. 7, a magnetic field is generated by the current flowing through the heating wire 42. Japanese Unexamined Patent Publication No. 4-278125 discloses a device for suppressing the generation of a magnetic field by canceling out the magnetic fields generated from the heating wires. This is shown in FIG. 8 as a second conventional example. Will be explained.

[0005] In FIG. 8, a first heating wire 52 and a second heating wire 54 are provided on a heating element 60, and currents in opposite directions flow through the first heating wire 52 and the second heating wire 54. It is configured as follows. That is, a first heating element 52 made of a copper alloy is spirally wound around a core 51 made of polyester, and a heat-resistant insulator 53 having no pinhole such as polyimide is provided on the first heating wire 52. The second heating wire 5 is connected to the heat-resistant insulator 53.
4 is spirally wound, and an insulator 55 made of nylon or the like is provided on the second heating wire 54.
A detection wire 56 for temperature control is spirally wound, and the detection wire 56 is formed by being covered with an insulating jacket 57 made of heat-resistant vinyl chloride or the like.

FIG. 9 shows a third conventional example, in which a first heating wire 73 and a second heating wire 74 are spirally wound around parallel and parallel winding cores 71 and 72, respectively. The first heating wire 73 and the second heating wire 74 are respectively provided with insulators 7.
A detection wire 76 for detecting that the insulator 75 is melted is spirally wound around the insulator 75, and the detection wire 76 is made of an insulating jacket 77 made of heat-resistant vinyl chloride or the like.
It was covered and formed. Note that a heating element having an integral detection line for temperature detection is also used for control temperature detection.

[0007]

The above-mentioned drawbacks of the prior art will be specifically described. If it is an electric carpet using a heating element as shown in the second conventional example and the third conventional example,
The generation of the magnetic field can be suppressed by canceling out the magnetic fields generated from the first heating wire and the second heating wire. However, when the electric carpet cannot be controlled, or when the external heating or the heating wire is partially disconnected. If the heating element is abnormally overheated due to, for example, there is an unstable factor in the safety function that overheating cannot be detected properly.

[0008] The reason for this is that the original safety function operation is, in the case of the second conventional example, abnormal heating of the heating wire (around 170 ° C).
Then, the insulator 55 melts and the detection wire 56 comes into contact with the second heating wire 54, so that the originally insulated portion is connected to the circuit, and the safety function operates. However, the heat generated by the abnormal heating of the half-break of the first heating wire 52 is diffused, and the insulator 55 is not melted and the detection wire 5 is not melted.
6, it was difficult to detect abnormal heating.

In the case of the third conventional example, when the heating wire is abnormally overheated (around 170 ° C.), the insulator 75 is melted, and the detection wire 76 becomes the first heating wire 73 or the second heating wire. By contacting the heating wire 74, a portion that is originally insulated is connected to a circuit, and the safety function is activated. However, there is a possibility that the first heating wire 73 and the second heating wire 74 may be short-circuited before the detection wires come into contact with each other at the time of abnormal overheating.

An object of the present invention is to provide a planar electric heater capable of reducing the generation of magnetism from a heating element and reliably detecting abnormal overheating of a heating wire.

[0011]

SUMMARY OF THE INVENTION An electric heater according to the present invention solves the above-mentioned problems and relates to an improvement in the structure of a heating element provided in a heater main body. A first heating wire and a reverse current are applied to the heating element in parallel with the heating element for the purpose of suppressing generation of a magnetic field, and a second heating wire is provided to cancel out the magnetic field with each other. The structure is such that the operation does not lead to burnout or ignition.

The heating element according to the present invention has a structure shown in FIGS. 3 and 5. First, FIG. 3 shows a first heating wire 22 spirally wound around a core 21 made of polyester or the like. 22 is provided with an insulator 23 made of nylon or the like which melts when overheating occurs due to an abnormal temperature rise, and a detection wire 24 is spirally wound around the insulator 23.
Is provided with an insulator 25 of the same quality as the insulator 23, a second heating wire 26 is spirally wound around the insulator 25, and the second heating wire 26 is made of heat-resistant vinyl chloride or the like. Received 2
7 covered.

Therefore, in this heating element 30,
When the first heating wire 22 and the second heating wire 26 are abnormally overheated, the insulators 23 and 25 melt and the detection wires 24 are melted.
And the first heat generating wire 22 or the second heat generating wire 26 are surely in contact with each other.

FIG. 5 shows a first winding core 1 and a second winding core 2 which are made of polyester or the like and which are arranged close to and parallel to each other.
A first heating wire 3 and a second heating wire 4 are spirally wound around each of the first heating wire 3 and the second heating wire 4, and the first heating wire 3 and the second heating wire 4 are melted when overheating occurs due to an abnormal temperature rise. Insulators 5 and 6 made of nylon or the like are provided, and a temperature detection wire 7 is spirally wound around the insulator 5, and a conductor 8 made of a copper alloy or the like is spirally wound around the insulator 6. The wire 7 and the conductive wire 8 are covered with an insulating jacket 9 made of heat-resistant vinyl chloride or the like in a state where they are close to each other to be integrated.

Therefore, in the heating element 10,
When the first heating wire 3 and the second heating wire 4 are overheated due to abnormal temperature rise, respectively, the insulators 5 and 6 are melted, respectively, and the first heating wire 3 is provided with a temperature detecting wire. 7 is
The conducting wire 8 reliably contacts the second heating wire 4.

According to the above configuration, the planar electric heater of the present invention comprises a first heating line at one end of a heating element and a second heating line connected in series, and a first heating line at the other end. By supplying electricity to the first and second heating wires, the first heating wire and the second heating wire are energized to perform heating.

At this time, the current flowing through the first heating wire and the current flowing through the second heating wire have the same amount in opposite directions, and the heating wires are very close to each other. The applied magnetic fields have the same strength and opposite directions, and have the effect of canceling each other out. In addition, the first heating wire and the second heating wire each pass through an insulator made of nylon or the like that melts when overheating occurs due to an abnormal temperature rise.
A structure provided with a temperature detection line or a conducting wire for detecting the temperature abnormality ensures the safety function operation in the event of an abnormality.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the planar electric heater of the present invention will be described with reference to the drawings.

<First Embodiment> A first embodiment in which the electric heater of the present invention is used for an electric carpet will be described. As shown in FIGS. 1 and 2, the electric carpet of the present invention meanders a heating element 30 having a heating wire that generates heat when energized on a backing cloth 11 made of a material having good heat insulation (for example, a felt of polyester). The heating element 30
Cloth 12 made of hard knee bread or tufted fabric from above
Adhesively fixed. Further, a sewn portion 13 formed by overlock sewing is formed on the entire periphery of the back cloth 11 and the front cloth 12, thereby forming a carpet body 15. In addition, a controller 14 having a control circuit (shown in FIG. 4) for controlling energization of the heating wire by a temperature detection wire, which is a component of the heating element, is provided at a corner of the carpet body 15.

As shown in FIG. 3, in the heating element 30, a first heating wire 22 made of a copper alloy is spirally wound around a winding core 21 made of polyester or the like, and the first heating wire 22 is abnormally wound. It is covered with an insulator 23 made of nylon or the like, which melts (melts at around 170 ° C.) when overheating occurs due to an excessive temperature rise. Further, when the insulator 23 is melted in the insulator 23, the first heating wire 22 is short-circuited to activate the safety device, and the temperature detection line 2 also serves as a detection for controlling the temperature.
4 is spirally wound. Further, the temperature detecting wire 24 is covered with an insulator 25 of the same quality as the insulator 23,
Is formed by spirally winding a second heating wire 26, and covering the second heating wire 26 with an insulating jacket made of heat-resistant vinyl chloride or the like.

Then, one end 2 of the first heating wire 22
2 'is connected to the control circuit of the controller 14, the other end 22 of the first heating wire is connected to one end 26 of the second heating wire, and the other end 26' of the second heating wire is connected to the control circuit. Connected to Also, as shown in FIG.
Since the connection point between the second heating wire 26 and the second heating wire 26 is connected as a turning point, when power is supplied, a current flows through the first heating wire, returns from the connection point, flows into the second heating wire 26, and always flows. Currents in opposite directions flow through the first heating wire 22 and the second heating wire 26.

Next, the operation of the electric carpet having the above configuration will be described. The control circuit supplies power to the first heating wire 22 and the second heating wire 26, and the first heating wire 22 and the second
When the temperature rises due to the heat generated by the heat generation line 26, the temperature detection line 24 detects the temperature, and based on the detection signal from the temperature detection line 24, the automatic temperature controller SCR of the control circuit is used.
Is turned on and off to control the power supply to the first heating wire 22 and the second heating wire 26 connected in series to the automatic temperature controller SCR to perform heating at a desired temperature.

Next, abnormal conditions such as control circuit component failure (particularly failure of the automatic temperature controller SCR not to be turned off), external overheating, and partial disconnection of the heating wire occur. Before the smoke is generated, the safety function of the control circuit is activated.

The operation of the safety function will be described. If one of the first heating wires 22 becomes abnormally overheated (around 170 ° C.), the insulator 23 covering the first heating wire 22 at that location will be described. Is melted, and the originally insulated temperature detection wire 24 and the first heating wire 22 are short-circuited. Similarly, when the second heating wire 26 is overheated abnormally, the insulator 25 at that location is melted, and the temperature detection wire 24 and the second heating wire are short-circuited.

At this time, the flow of electricity is as shown in FIG. F → Resistor R21 (resistance integrated with thermal fuse TF) → Diode D6 → Temperature detection wire 24 → First heating wire 22 or Second heating wire 26
→ Current fuse I. It becomes F. Thus, the resistance R
21 does not flow, the resistor R21 is overheated, and the heat causes the temperature fuse T.T. By operating F, energization of the heating wire can be stopped to maintain safety.

<Second Embodiment> Next, a second embodiment of the present invention will be described.
An embodiment will be described. The detailed description of the same parts as those in the first embodiment will be omitted. Only the structure of the heating element is different from that of the first embodiment, and the structure shown in FIGS. 1 and 2 is the same.

As shown in FIG. 5, the heating element of the second embodiment is made of polyester or the like, and a first winding core 1 and a second winding core 2 which are arranged close to and parallel to each other. And the second heating wire 4 are spirally wound. Further, the first heating wire 3 and the second heating wire 4 are respectively provided with insulators 5 and 6 made of nylon or the like which melt when overheating occurs due to an abnormal temperature rise.

Then, the temperature detecting wire 7 is spirally wound around the insulator 5, and a conductor 8 made of a copper alloy or the like is spirally wound around the insulator 6, and the temperature detecting wire 7 and the conductor 8 are close to each other. In this state, it is covered with an insulating jacket 9 made of heat-resistant vinyl chloride or the like to be integrated. Then, one end 3 'of the first heating wire is connected to a control circuit of the controller 14, and the other end 3' of the first heating wire is connected.
Is connected to one end 4 of the second heating wire, and the other end 4 'of the second heating wire is connected to the control circuit.

Since the connection point between the first heating wire 3 and the second heating wire 4 is connected as a turning point, when power is supplied, current flows through the first heating wire and returns from the connection point. Thus, a current flows in the first heating line 3 and the second heating line 4 in the opposite direction at all times.

Next, the operation of the second embodiment will be described.
The control circuit energizes the first heating wire 3 and the second heating wire 4. When the first heating wire 3 and the second heating wire 4 generate heat and the temperature rises, the temperature is detected by the temperature detection wire 7. , And based on the detection signal from the temperature detection line 7, the automatic temperature controller SCR of the control circuit is turned on and off, and the first heating line connected in series to the automatic temperature controller SCR. Heating at a desired temperature is performed by controlling the power supply to the third and second heating wires 4.

The operation of the safety function at the time of abnormal temperature rise will be described. When the first heating wire 3 becomes abnormally overheated (around 170 ° C.), the insulator 5 covering the first heating wire 3 is melted and the temperature is raised. Short-circuit with the detection line 7. Similarly, the second heating wire 4 is abnormally overheated, and the insulator 6 is melted and short-circuited with the conductor 8. As shown in FIG. 6, this conductor is short-circuited at both ends 8, 8 'and is connected to one end 7 of the temperature detection line. Therefore, as described in the first embodiment, the first heating wire 3 Alternatively, even if one of the second heat generating wires 4 becomes abnormal, a current that does not flow through the resistor R21 flows, and the resistor R21 is overheated. F can be operated to maintain safety.

[0032]

Since the electric heater of the present invention has the above-described configuration, the first heating wire and the second heating wire reduce the magnetic field generated at the time of energization and prevent the generation of electromagnetic noise. In addition, even when the two heating wires are provided, the safety function operation can be reliably performed without short-circuiting the two heating wires when abnormal heating such as a half-break of the heating wire occurs.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a planar electric heater of the present invention.

FIG. 2 is a cross-sectional view of the planar electric heater main body of FIG.

FIG. 3 is an enlarged view of a main part of a heating element according to the first embodiment of the planar electric heater of the present invention.

FIG. 4 is a circuit diagram used in the first embodiment of the electric heater according to the present invention.

FIG. 5 is an enlarged view of a main part of a heating element according to a second embodiment of the planar electric heater of the present invention.

FIG. 6 is a circuit diagram of a heating element connecting portion used in a second embodiment of the electric heater according to the present invention.

FIG. 7 is an enlarged view of a main part of a heating element used in the first conventional example of the planar electric heater.

FIG. 8 is an enlarged view of a main part of a heating element used in a planar electric heater of a second conventional example.

FIG. 9 is an enlarged view of a main part of a heating element used for a third conventional planar electric heater.

[Explanation of symbols]

 1,2,21 Winding core 3,22 First heating wire 4,26 Second heating wire 5,6,23,25 Insulator 7,24 Temperature detection wire 8 Conducting wire 9,27 Insulating jacket 10,30 Heating element 15 Carpet body 11 Back cloth 12 Front cloth 13 Sewing part 14 Controller SCR Automatic temperature controller

Claims (6)

[Claims] 1. A planar electric heater in which a heating element is provided on a heater body in a planar manner and heating is performed by controlling energization of the heating element, wherein the heating element comprises: a core; A first heating wire wound around a core, a first insulator covering the first heating wire,
A conductor wound around the insulator, a second insulator covering the conductor, a second heating wire wound around the second insulator,
A planar electric heater comprising: an insulating jacket for covering the heating wires of the above, and passing a current in opposite directions to the first heating wires and the second heating wires. 2. The planar electric device according to claim 1, wherein the first heating wire and the second heating wire are connected in series with the heating element disposed in the heater body. heater. 3. The planar electric heater according to claim 1, wherein the conducting wire also serves as a temperature detecting wire. 4. A planar electric heater in which a heating element is disposed on a heater main body in a planar manner and heating is performed by controlling energization of the heating element, comprising: a first winding core; A first heating wire wound around the core,
A first heating wire composed of a first insulator covering the first heating wire, a first conductor wound around the first insulator, a second core, and a second core. A second heating wire wound around the core of
A second heat generating wire comprising a second insulator covering the second heat generating wire and a second conductive wire wound around the second heat generating wire; And disposing the two heating wires in parallel, covering both of them with an insulating jacket to form a heating element, and passing currents in opposite directions to the first heating wire and the second heating wire. A planar electric heater. 5. The planar state according to claim 4, wherein the first heating wire and the second heating wire are connected in series with the heating element disposed in the heater body. Electric heater. 6. The planar electric heater according to claim 4, wherein the first conductor or the second conductor also serves as a temperature detection line.