JP2007218553A - Sheet heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve safety by detecting short-circuiting of a heating element in a sheet heating device and surely stopping the device. <P>SOLUTION: This sheet heating device is provided with an unbalanced electric current detecting means 22 detecting an unbalanced state of input/output electric current of a first heating wire 15 or a second heating wire 16, and is stopped by forcibly opening an electric current breaking means 18, by determining generation of short-circuiting between two heating wires 15, 16 when the unbalance is generated in inflow/outflow electric current. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric carpet, an electric blanket, and a panel heater. Specifically, even if a heating element composed of a first heating wire and a second heating wire is short-circuited at an unspecified part, the current detection means causes a short-circuit. The present invention relates to a planar heating device that can detect and enhance safety against abnormal heat generation and ignition of the heating device.

  In a conventional sheet heating device such as an electric carpet, a magnetic field having a commercial frequency is generated by a current flowing through a heating element. Therefore, the heating element is divided into a first heating line and a second heating line, currents in opposite phases are passed through the heating lines, and both the first heating line and the second heating line are brought close to each other. There is known a configuration in which leakage of a magnetic field to the outside is prevented by canceling out a magnetic field generated by.

  In the above configuration, when adjacent heating wires are short-circuited, a configuration in which the current fuse provided in the device is used and the current fuse is blown by an overcurrent generated at the time of the short-circuit is common. However, when a short circuit occurs at an unspecified part of the heating wire and the device current does not reach the fusing point of the current fuse at the time of the short circuit, for example, in the case of an electric carpet, the heating wire reaches several tens of meters, so the short circuiting part Depending on the case, it is conceivable that the heating wires are short-circuited while leaving a certain resistance value. In this case, the current fuse is not blown. If the current fuse is held without being blown, there is a risk that the power cord may generate heat due to heat generation of the power cord or abnormal heating of the heating wire itself.

Therefore, as a countermeasure, a configuration shown in FIG. According to this document, a heating element composed of a first heating wire 1 and a second heating wire 2 is arranged in the heating device body, and the heating element is energized and heated by the commercial power source 3 and is blown to the commercial power source 3 by an overcurrent. The current fuse 4, the first heating wire 1, the current breaker 5 that opens and closes according to the temperature of the heating element, and the second heating wire 2 and the temperature fuse 6 that blows when heated from the outside are connected in series. A heat generating resistor 7 that heats and melts the temperature fuse 6 and a switching element (triac) 8 that turns on and off the heat generating resistor 7 are connected in series between both ends of the temperature fuse 6, and the first heat generating wire is connected. When the current breaker 5 is used as a turning point so that current flows through the first and second heating wires 2 in opposite directions, and the heating element is short-circuited at an unspecified location, the temperature fuse 6 is blown to heat the circuit components and the like.・ Safety against ignition It can Mel possible.
JP 2004-293932 A

  However, the conventional configuration does not directly detect a short circuit between the first and second heating wires. That is, when the temperature of the heating wire is controlled by opening / closing the current breaker 5, the heating resistor 7 is energized through the triac 8 because the heating wire is short-circuited when the current breaker 5 is open, and the temperature fuse 6 is melted and the short circuit state is not maintained, so that when the current breaker 5 is closed, the short circuit is detected and the device cannot be stopped. For this reason, there is a problem that a delay occurs in detection of a short circuit, and heat generation / ignition cannot be completely prevented.

  The present invention solves the above-mentioned conventional problems, and dramatically improves safety against heat generation and ignition by detecting a short circuit between heating wires in an unspecified part and immediately cutting off the current supply to the heating element. An object of the present invention is to provide a sheet heating device.

  In order to solve the above-mentioned conventional problems, the planar heating device of the present invention includes first and second current detection means so as to detect currents at one end and the other end of the first or second heating wire. And when the difference between the detected current values of the first and second current detection means exceeds a predetermined value by the comparator, the current interruption means interrupts the current supply to the heating wire.

  Thus, when the heating wires are short-circuited, a short-circuit current path is formed between the first heating wire and the second heating wire at the short-circuit point, and the difference between the current value at one end and the current value at the other end of the heating wire is established. Occurs. For this reason, a difference occurs in the detected current values of the first and second current detecting means provided in the first or second heating wire, and the control unit detects a short circuit of the heating wire by the difference in the detected current value. Can do.

  Further, current unbalance detection means for detecting a current unbalance at both ends of one of the first and second heating lines is provided.

  As a result, the unbalanced current detection means can detect that the current at the terminal portion of the heating wire is unequal due to a short circuit at the unspecified part of the heating wire, so that the control section outputs the output signal of the current unbalance detection means. Can detect a short circuit of the heating wire.

  According to the planar heating device of the present invention, it is detected by the current detection means that the first heating wire and the second heating wire are short-circuited at an unspecified part, and the current interrupting device is opened to the heating element. Therefore, the apparatus can be stopped immediately when the heating wire is short-circuited.

  According to a first aspect of the present invention, there is provided a heating element composed of a first heating line and a second heating line connected in series to be energized and heated by a commercial power source, and a current interrupting means that opens and closes the commercial power source by a control unit. And an unbalanced current detecting means for outputting when the current of the input terminal portion of the heating element becomes unbalanced, and when the unbalanced current detecting means outputs, the control section Has a configuration in which the current interrupting means is opened and the current supply to the heating element is interrupted, and a lead wire portion that does not generate heat when energized is provided in a part of the first heating wire or the second heating wire, By connecting the lead wire portion to the unbalanced current detecting means to detect the unbalanced current, it is ensured that the heating wires of any heating element are short-circuited by the unbalanced current detecting means. It is possible to output, it is possible to significantly improve the security against overheating, fire.

  The second invention has a plurality of heating elements each composed of a pair of heating lines, particularly in the planar heating device of the first invention, and the unbalanced current detecting means is configured to detect at least one heating element of the plurality of heating elements. By adopting a configuration that detects the balanced current, it is possible to reliably detect that the heating wires of any of the heating elements are short-circuited by the unbalanced current detection means, thus dramatically improving the safety against heat generation and ignition. It becomes possible to do.

  According to a third aspect of the present invention, there is provided a configuration in which a control board is provided in the planar heating device of the first or second invention, and an unbalanced current detecting means is connected to a connection portion from a commercial power source to a heating element on the control board. By doing so, it is possible to reliably detect a short circuit between the heating wires by the unbalanced current detection means, and it is possible to dramatically improve the safety against heat generation and ignition.

In the fourth aspect of the invention, in particular, the unbalanced current detecting means of the planar heating device of the first or second aspect of the invention is provided at the connecting portion between the first heating line and the second heating line, thereby providing an unbalanced state. Since it is possible to reliably detect that the heating wires of any of the heating elements are short-circuited by the current detection means, it is possible to dramatically improve the safety against heat generation and ignition.

  According to a fifth aspect of the present invention, the unbalanced current detecting means of the planar heating device of the first or second aspect of the invention comprises an annular magnetic body and a detection winding wound around the magnetic body. By providing a conductor pattern connected to the heating element and a through hole adjacent to the conductor pattern and detecting the unbalanced current by passing the annular magnetic body through the through hole, the unbalanced current detection is performed. Since it is possible to reliably detect a short circuit between the heating wires by means, it is possible to dramatically improve the safety against heat generation and ignition.

  In the sixth aspect of the invention, the annular magnetic body of the surface heating device of the fifth aspect of the invention is a combination of U-shaped magnetic bodies divided into two, and the annular magnetic body has a lower height direction. In this way, the short circuit between the heating wires can be reliably detected by the unbalanced current detection means, so that the safety against heat generation and ignition can be drastically improved and at the same time height Since the unbalanced current detecting means is flat with respect to the direction, the height of the control board can be reduced and the control board can be miniaturized.

  In the seventh aspect of the invention, in particular, the detection winding is wound around one of the divided magnetic bodies of the planar heating device of the sixth aspect of the invention, so that the unbalanced current detecting means can reliably short-circuit the heating wires. Therefore, it is possible to drastically improve the safety against heat generation and ignition, and at the same time, the height of the control board is lowered because the unbalanced current detection means is flat in the height direction. The control board can be downsized.

  In the eighth invention, the lead wire or the conductor pattern on the substrate for detecting the unbalanced current by the unbalanced current detecting means of the planar heating device of the first to seventh inventions is fixed to the unbalanced current detecting means. With this configuration, it is possible to reliably detect a short circuit between heating wires by the unbalanced current detection means, so it is possible to dramatically improve the safety against heat generation and ignition, and at the same time, winding by vibration, etc. Since the positional relationship between the magnetic material and the magnetic material does not change, it is possible to prevent the unbalanced current detecting means from malfunctioning due to vibration and improve the sensing accuracy of the unbalanced current detecting means.

  In the ninth aspect of the invention, in particular, the hollow portion in the closed magnetic circuit of the unbalanced current detecting means of the planar heating device of the eighth aspect of the invention is filled with resin and unbalanced by the unbalanced current detecting means and the unbalanced current detecting means. Since the lead wire for detecting the current or the conductor pattern on the substrate is fixed to the unbalanced current detecting means, the unbalanced current detecting means can reliably detect a short circuit between the heating wires.・ It is possible to dramatically improve the safety against ignition, and at the same time, the positional relationship between the winding and the magnetic body does not change due to vibration, etc., so that the unbalanced current detection means can be prevented from malfunctioning due to vibration. The sensing accuracy of the detection means can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to the drawings as an application example to an electric carpet. FIG. 1 is a schematic external view of an electric carpet according to the present invention.

The carpet body has a heating element 11 that generates heat when energized on a backing cloth 10 made of a material having excellent heat insulation properties (for example, a polyester felt cloth). The outer fabric 12 is bonded and fixed. Further, the outer peripheral portion is formed by overlock sewing. A controller 13 having a temperature adjustment function and a safety protection function is connected to the peripheral edge of the carpet body to control the amount of electricity supplied to the heating element 11, and a plug 14 for supplying power from the commercial power supply 3 is connected to the controller 13. It is connected.

  In the heating element 11, a first heating wire 15 made of a copper alloy is spirally wound around a core material, the first heating wire 15 is covered with a heat-resistant insulator such as polyester or polyamide, and the outer periphery thereof is further covered. A second heating wire 16 similar to the first heating wire 15 is spirally wound, and the first heating wire 15 and the second heating wire 16 are arranged on the same axis that is covered with a heat-resistant insulator again. The first heating wire 15 made of a copper alloy is spirally wound around a structure in which both heating wires are arranged adjacent to each other or the core material, and the first heating wire 15 is heat-resistant such as polyester or polyamide. The configuration is such that the second heating wire 16 having the same configuration is disposed adjacently and in parallel with each other, or is disposed adjacently by twisting both heating wires. The magnetic field generated mutually can be canceled by supplying currents in opposite directions to the respective heating lines.

  FIG. 2 is a circuit diagram of a main part of the electric carpet according to the present invention. As shown here, the first heating wire 15 and the second heating wire 16 are connected in series to the commercial power source 3, and the current interrupting means 20 is connected between the heating wire and the commercial power source. The unbalanced current detecting means 22 for detecting the unbalanced current of the first heating wire 15 or the second heating wire 16 simultaneously detects the current flowing from the commercial power source into one heating wire and the current flowing out from the heating wire simultaneously. The configuration is such that an imbalance between the two currents is detected. When the unbalanced current detecting means 22 detects an unbalanced state, the current interrupting means 20 cuts off the supply of current to the heating wire and the heating wire 11 (here, a pair of the first heating element 15 and the second heating element 16). The heating stops.

  The unbalanced current detecting means 22 that functions in this way can be realized by the configuration shown in FIG. A detection winding 221 is wound around the annular magnetic core 220, and current lines 222 and 223 for detecting current are passed through the annular core 220. At this time, the directions of current flow in the current lines 222 and 223 must be opposite to each other. With this configuration, current flows in the direction of current lines 222 and 223 as shown in the figure, and when I1 = I2, the magnetic fields generated by the current lines cancel each other, so that magnetic flux is generated in the magnetic core 220. do not do. For this reason, the output of the detection winding 221 is zero. However, when I1 ≠ I2, a magnetic flux is generated in the magnetic core 220, and a voltage is output to the detection winding 221. When an output voltage is generated in the detection winding 221, the control unit 21 forcibly interrupts the current interrupting means 20 and stops the device.

  The resistance value between A and E of the first heating line 15 is R1, the resistance value between E and B is R2, and the resistance value between C and F of the second heating line 16 is between R3 and FD. When the resistance value is R4, the current value I1 on the A terminal side and the current value I2 on the B terminal side can be expressed by equations (3) and (4), respectively.

I1 = V / (R1 + R2) + V / (R1 + R3) (3)
I2 = V / (R1 + R2) + V / (R2 + R4) (4)
V: Voltage of the commercial power supply 3 Since there is no second term in each equation in a state where no short circuit has occurred, the equation I1 = I2 is always established, and the current imbalance detection means 22 does not generate an output signal. However, when a short circuit occurs between EF, the second term of each equation is generated, and I1 ≠ I2, and the current becomes unbalanced. At this time, the current imbalance detection means 22 emits an output signal and can detect a mutual short circuit between the heating wires 15 and 16. In this equation, when R1 + R3 = R2 + R4, there is no difference between the current at the A terminal and the current at the B terminal, but the potential difference between the short-circuit points EF is always zero when this condition is satisfied. Therefore, even if a short circuit occurs at this point, no current flows through the short circuit point, and the heating wire does not generate heat abnormally.

  As described above, in the planar heating device according to the present embodiment, even if any part of the heating wire is short-circuited with each other, an unbalance between the current value on one terminal side and the current value on the other end side is reliably detected. Because it is possible to detect a short circuit in the heating element in a short time and cut off the current supply from the commercial power supply, the heating element will not become abnormally hot and the safety of the electric carpet can be improved It becomes possible. In this embodiment, the resistance values of the first and second heating lines 15 and 16 are not limited at all. For example, when the two heating lines have substantially the same resistance value, the resistance values of the two heating lines are the same. Needless to say, the effect of the present embodiment can be exhibited even when the balance is unbalanced.

  The first heating wire 15 is provided with lead wire portions 23A and 23B that do not generate heat when energized, and the lead wire portions 23A and 23B are passed through the magnetic core 220 constituting the unbalanced current detecting means 22. A stable operation can be performed without the unbalanced current detection means 22 receiving heat generated by the heating element 11.

  FIG. 4 is a waveform diagram showing current waveforms of the first and second heating lines 15 and 16. Until time T1 when both the first heating line 15 and the second heating line 16 are operating in a normal state, a predetermined current value determined by the resistance value of each heating line is observed. For example, when the heating wires are short-circuited between A1 and A2 in FIG. 1 at time T1, the resistance value of the heating element 11 viewed from the commercial power source 3 side is reduced, so that an overcurrent is generated. The peak value rises to I2. This is because, for example, the heating wires 15 and 16 are partially heated due to some abnormality, and the insulation interposed between the heating wires melts or the user accidentally penetrates the push pin or the like into the electric carpet. This is a phenomenon that may occur when the heating wires are accidentally short-circuited. Usually, as a protective measure against overcurrent, a current fuse (not shown) is connected to the heating element 11 in series, but in the case of an electric carpet, the entire length of the heating element 11 reaches several tens of meters. Depending on the part that is short-circuited, the fusing current of the current fuse may not be reached. In this case, since the short circuit state of the heating wire is maintained indefinitely by the protection by the current fuse, there is a problem in safety, but the unbalanced current detection means for detecting the short circuit in the heating wire 11 as in the present embodiment. By providing 22, an abnormality can be detected even in a short-circuit state that does not reach the fusing current of the current fuse, so that the overheating of the heating element 11 can be prevented.

  Moreover, it can detect similarly about the structure provided with two or more heat generating bodies. FIG. 5 is a principal circuit diagram in the case where, for example, three heating elements are provided.

  The current imbalance of one of the heating lines constituting the first to third heating elements 24, 25, and 26 (150, 151, and 152 in FIG. 5) is detected by one current imbalance detection means 22. It is the composition to do.

  As a specific configuration, in the current imbalance detection means 22 shown in FIG. 3, the magnetic core 220 may be penetrated with lead wires connected to the respective heating wires. Therefore, in this case, six current lines penetrate the magnetic core 220.

When no short circuit occurs in any of the heating elements, the currents flowing in the current imbalance detection means 22 are I10 = I20, I11 = I21, and I12 = I22, respectively, so that the current imbalance detection means 22 does not generate an output signal. Here, assuming that a short circuit occurs in the heating element A, since I10 ≠ I20, an output signal is generated in the current imbalance detection means 22. This is the same when a short circuit occurs in the heating lines B and C. At this time, since I11 ≠ I21 and I12 ≠ I22, the current imbalance detection means 22 generates an output signal. As a result, even a planar heating device having a plurality of heating elements can be detected by one current imbalance detection means 22. Also in this configuration, the heating wire is provided with a lead wire portion that does not generate heat when energized, and this lead wire portion is used as the magnetic core 22 constituting the unbalanced current detection means 22.
By allowing the heat to be generated by the plurality of heating elements, the unbalanced current detecting means 22 can receive a stable operation by passing through 0.

  For this reason, the effect that it becomes possible to comprise the controller which equips the control part 21, the electric current imbalance detection means 22, etc. with a small size and lightweight can be exhibited.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a view showing a mounting state of the unbalanced current detecting means 22 of the hot carpet according to the present invention. Since the main circuit configuration is the same as that of the above-described embodiment, a detailed description is omitted here. A current interrupting means 20 and an unbalanced current detecting means 22 are installed on a controller board 30 built in the controller 13 so as to receive power supply from the commercial power supply 3 from the input power supply line 27. The connection of each component is as shown in the main circuit diagram of FIG. 7. In this embodiment, the current unbalance of the first heating wire 15 is detected by the unbalanced current detecting means 22. ing.

  With this configuration, when a short circuit occurs between the first heating wire 15 and the second heating wire 16 as in the above-described embodiment, the short circuit can be detected by the unbalanced current detection means 22. . Further, since the unbalanced current detecting means 22 is configured to detect the unbalanced current via the lead wire portion 23, the influence of the heat generated by the first and second heating wires 15 and 16 can be detected. A stable operation can be performed without the means 22 receiving. Further, since the amount of heat generated by the unbalanced current detecting means 22 is small, the arrangement in the sealed controller can be freely performed, so that the component arrangement can be optimized and the controller 13 itself can be designed to be small.

(Embodiment 3)
A third embodiment of the present invention will be described with reference to FIG. FIG. 8 shows a cross-sectional view of the unbalanced current detecting means 22 of the present invention when mounted. A pair of through-holes 28 and 29 are formed on a board which is built in the controller 13 and on which a component is placed, and a conductor pattern connected from the commercial power source 3 to the heating element 11 is formed. 220 is divided into two parts and sandwiched through the through holes. With this configuration, current can flow through the hollow portion of the magnetic core 220. When an unbalanced state of current occurs between the two conductor patterns, the unbalanced state is detected by the detection winding 221. A short circuit in the heating wire 11 can be detected. As in the above-described embodiment, when a short circuit in the heating element 11 is detected by the unbalanced current detection means 22, the current interrupting means 18 cuts off the supply of current to the heating wire, and the heating wire 11 (here, the first heating element). The heating of the pair 15 and the second heating element 16 is stopped.

  The divided magnetic body core 220 has a flat configuration and suppresses the height from the control substrate 28 as much as possible, and the control unit 13 itself can be designed to be very thin.

  In addition, the hollow portion of the magnetic core 220 is filled with resin and fixed to the control board 30 so as not to be displaced due to vibration. The detection sensitivity of the unbalanced current detection means 22 is very high, and a signal is generated in the detection winding 221 even if an unbalanced current is generated about 10 mA. Therefore, the vibration is transmitted to the unbalanced current detecting means 22 during energization, and a signal is erroneously generated even if the relative positional relationship between the magnetic core 220 and the detection winding 221 or the energized conductor pattern is shifted. However, as in the present embodiment, the hollow portion of the magnetic core 220 is filled with resin and fixed to the control substrate 28, so that positional displacement due to vibration is eliminated, and a signal is erroneously generated even when vibration is applied. In addition, it is possible to reliably detect a short circuit with high detection sensitivity at the time of a short circuit.

  As described above, the planar heating device according to the present invention can reliably detect the short circuit between the heating wires, and therefore can be applied to the detection of a short circuit of a device to which other heating wire heating is applied.

1 is an external view of an electric carpet according to a first embodiment of the present invention. Main circuit diagram of the electric carpet Specific configuration diagram of unbalanced current detection means of the electric carpet The figure which shows the electric current waveform of the heating wire of the electric current detection means of the electric carpet Main part circuit diagram when multiple heating elements are arranged in the same electric carpet The figure which shows an example of component arrangement | positioning on the controller board of the electric carpet in the 2nd Embodiment of this invention Main circuit diagram of the electric carpet Installation sectional view of unbalanced current detection means in the third embodiment of the present invention Main circuit diagram of a conventional surface heating device

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Commercial power supply 15 1st heating wire 16 2nd heating wire 19 Control part 20 Current interruption | blocking means 22 Unbalanced current detection means 23 Lead wire part 24 1st heating element 25 2nd heating element 26 3rd heating element 28, 29 Through hole 30 Control board

Claims (9)

A heating element composed of a first heating wire and a second heating wire connected in series with a commercial power source and heated, current interrupting means that opens and closes with respect to the commercial power source by a control unit, and the heating element In addition to connecting in series, there is provided unbalanced current detecting means for outputting when the current at the input terminal portion of the heating element becomes unbalanced, and when the unbalanced current detecting means outputs, the control unit turns on the current interrupting means. A lead wire portion that does not generate heat when energized is provided in a part of the first heat generating wire or the second heat generating wire, and the lead wire portion is not A planar heating device configured to detect an unbalanced current by connecting to a balanced current detecting means. 2. The sheet heating apparatus according to claim 1, wherein the heating element includes a plurality of heating elements each composed of a pair of heating lines, and the unbalanced current detection unit detects an unbalanced current of at least one heating element of the plurality of heating elements. . The planar heating device according to claim 1 or 2, wherein a control board is provided, and an unbalanced current detecting means is connected to a connection portion from a commercial power source to a heating element on the control board. The planar heating device according to claim 1 or 2, wherein the unbalanced current detecting means is provided at a connection portion between the first heating wire and the second heating wire. The unbalanced current detection means comprises an annular magnetic body and a detection winding wound around the magnetic body, and a conductor pattern connected from a commercial power source to a heating element on the control board and a through hole adjacent to the conductor pattern are provided. The planar heating device according to claim 1, wherein an unbalanced current is detected by passing the annular magnetic body through the through hole. 6. The planar heating device according to claim 5, wherein the annular magnetic body is formed by combining a U-shaped magnetic body divided into two, and the annular magnetic body is configured to be flat so that the height direction is lowered. The planar heating device according to claim 6, wherein the detection winding is wound around one of the divided magnetic bodies. The planar heating device according to any one of claims 1 to 7, wherein a lead wire for detecting an unbalanced current by the unbalanced current detecting means or a conductor pattern on the substrate is fixed to the unbalanced current detecting means. The hollow portion in the closed magnetic circuit of the unbalanced current detecting means is filled with resin, and the lead wire or the conductor pattern on the substrate for detecting the unbalanced current by the unbalanced current detecting means and the unbalanced current detecting means is the unbalanced current. The sheet heating apparatus according to claim 8, wherein the sheet heating apparatus is fixed to the detection means.

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