JPH10247579A - Electric heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive electric blanket (electric heater) which reduces its leaking magnetic field and does not decrease accuracy of temperature detection for controlling heat generation of a heating wire. SOLUTION: A heating element 15 to be built in a blanket 1 is formed using first and second heater cables 2, 3 which have first and second heating wires respectively and are arranged in parallel with and close to each other. The both heating wires are connected electrically in parallel, the both heater cables 2, 3 are set so that directions of currents through the heating wires are opposite each other, and amount of currents through the heating wires is set to be same each other. To the first heater cable 2, a heater cable is applied which consists of a first heating wire, a temperature sensitive layer which covers the heating wire and passes leak current which flows due to change of electric resistance depending on temperature change, a temperature sensitive conductor which is placed on the layer's outer periphery and detects the leak current, and a insulating cover covering the temperature sensitive conductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric carpet, an electric blanket, and an electric carpet for heating by utilizing the resistance heat of a heating wire.
The present invention relates to an electric heater used for an electric heater such as an electric blanket or a heating device for performing floor heating or wall heating, and more particularly to an electric heater having a reduced leakage magnetic field.

[0002]

2. Description of the Related Art For example, when an electric blanket is used, a magnetic field is generated around a heating wire by an electric current flowing through the heating wire inside the blanket. There is no clear confirmation that the human body will continue to be exposed to such magnetic fields for long periods of time, but recently there has been concern that it may adversely affect human health. It is desirable that the generated magnetic field be as small as possible.

[0003] Under such circumstances, the concentrically arranged 2
With the configuration in which one end of each of the heating wires is short-circuited and current is supplied from the other end, the directions of the currents flowing through the two heating wires are opposite to each other, and the magnetic fields generated around the two heating wires are canceled to leak to the outside. Techniques for reducing the magnetic field are known from JP-A-4-278125, JP-A-5-15429, JP-A-5-21145, and the like.

[0004] Also, Japanese Patent Application Laid-Open No. Hei 5-15429 discloses that
The same technology as described above, in which two heating wires are wired in parallel rather than concentrically and short-circuited at one end and energized from the other end to reduce the leakage magnetic field to the outside, is also described. I have.

Further, a coaxial structure lead wire also having a concentrically arranged center conductor and an outer conductor is provided at both ends of a coaxial structure cable having a center conductor and an outer conductor arranged concentrically. Japanese Patent Laid-Open Publication No. Hei 7-35359 discloses a technique in which currents flow in opposite directions to the center conductor and the outer conductor of the cable to reduce leakage magnetic fields to the outside.
No. 1993, which is hereby incorporated by reference.

Although not related to reducing the leakage magnetic field, there is a technology in which a heating wire and a temperature sensing wire for controlling the amount of current supplied to the heating wire are made not a two-wire system but a one-wire system. It is known from JP-A-3-226988. This technology is
A heat-sensitive layer is provided between the heat-generating wire and the temperature-sensitive conductor as a temperature-sensitive conductor disposed outside the heat-generating wire, and heat is generated by utilizing the fact that the electric resistance of the heat-sensitive layer changes with temperature. A change in the leakage current leaking from the line to the temperature sensing line is detected, whereby the amount of heat generated by the heating line can be controlled.

[0007]

Incidentally, in an electric heater such as an electric blanket, a heating line is generated based on temperature detection described in JP-A-3-226988 to obtain a desired heating temperature. Controlling is essential. Under these circumstances, in order to control the amount of current to the heating wire while reducing the leakage magnetic field, a temperature-sensitive (temperature detection) structure described in Japanese Patent Application Laid-Open No. 3-226988 and the like are disclosed in Japanese Patent Application Laid-Open No. 4-27881.
No. 25, JP-A-5-15429, JP-A-5-
What is necessary is just to apply to an electric heater, such as 21145 gazette.

In this application, the temperature detection technique is applied to one of two heating wires connected in series with one end short-circuited, but the total length of the two heating wires connected in series is determined. Therefore, the voltage applied to the heating line for detecting the temperature every half cycle of the AC becomes smaller in accordance with the voltage drop of the heating line for which the temperature is not detected.
As a result, the leakage current in each half cycle of the AC is reduced based on such a voltage drop, and the change is reduced, which may cause a problem that the temperature detection accuracy is deteriorated.

Such a problem is caused by the fact that the temperature-sensitive structure is disclosed in
Although this does not occur when applied to -35359, the technique described in this publication has a problem that the cost is high because a coaxial structure wire is used for the lead wire.

Therefore, the first problem to be solved by the present invention is that the leakage magnetic field can be reduced, and that the temperature detection accuracy for controlling the heat generation of the heat generating wire is not reduced, and that the cost can be reduced. It is to provide an electric heater that can. A second problem to be solved by the present invention is to obtain an electric heater that can secure the safety against abnormal overheating while solving the first problem.

[0011]

According to the present invention, there is provided an electric heater which has a heating element having a heating wire built in a heater body used in a planar shape, and which controls heating of the heating wire by a controller. A heater is assumed.

In order to solve the first problem, the invention according to claim 1 is characterized in that the heat generation is performed by first and second heater cables which have the heating wires individually and are arranged close to and parallel to each other. A body is formed, and at least one of the first and second heater cables has the heating wire, a temperature-sensitive conductor provided along the heating wire for detecting a leakage current, and an electric resistance according to a temperature change. A heater cable made of a variable material and having a temperature-sensitive layer interposed between the heating wire and the temperature-sensitive conductor and passing the leakage current from the heating wire to the temperature-sensitive conductor, The heating wires of the first and second heater cables are electrically connected in parallel, and the heating cables are provided so that the directions of currents flowing through the heating wires are opposite to each other. The amount of current flowing through the wire It is characterized in that the.

According to the first aspect of the present invention, since the same amount of current flowing through both the heating wires of the first and second heater cables arranged close to and parallel to each other is opposite to each other, the respective heating wires are The directions of magnetic fields of similar strength generated around them are reversed, and these magnetic fields cancel each other out.

[0014] At least one of the heater cables employs a temperature-sensitive structure cable that detects a leakage current from the heat-generating wire to the temperature-sensitive conductor to enable temperature detection of the heater body. The desired heating temperature can be obtained by controlling the energization of the heating wire by the controller based on the knowledge detection information. Moreover, since the respective heating wires of the first and second heater cables are electrically connected in parallel, the accuracy of temperature detection by the heater cable of the temperature-sensitive structure in the temperature control is lower than that of the other heater cable. It is not affected by the voltage drop according to the length of the heating wire.

Further, since the heating wires individually provided by both heater cables are electrically connected in parallel as described above, it is not necessary to use a coaxial lead wire to supply current to these heating wires. .

In order to solve the second problem,
The invention according to claim 2 subordinates to the invention according to claim 1,
The heater cable is made of a first heating wire, a temperature-sensitive conductor provided along the first heating wire and detecting a leakage current, and a material whose electric resistance changes according to a temperature change. And a temperature sensing layer interposed between the temperature sensing conductor and passing the leakage current from the first heating wire to the temperature sensing conductor. A heating wire, a short-circuit conductor provided along the second heating wire, and a material that is melted at a predetermined temperature, and is interposed between the second heating wire and the short-circuit conductor; It is characterized by having a short-circuit layer for short-circuiting the heating wire and the short-circuit conductor.

Since the invention of claim 2 is dependent on the invention of claim 1, in addition to being able to solve the first problem, the structure of the second heater cable has raised the temperature of the cable to a predetermined temperature or higher. In this case, the short-circuit layer is melted, and the second heating wire and the short-circuit conductor are short-circuited, whereby an abnormal temperature can be detected. Based on the detected temperature, safety measures such as stopping power supply can be taken. for that reason,
Even when a local abnormal temperature, that is, a so-called heat spot, is generated in the heater main body, it can be detected to ensure safety in use.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electric blanket according to a first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view schematically showing a wiring structure of a heater cable in an electric blanket. In FIG. 1, reference numeral 1 denotes a blanket body as a heater body used in a planar shape.

In the blanket body 1, flexible first and second heater cables 2 and 3 are provided so as to meander over the entire area of the blanket body 1, and the ends of these cables 2 and 3 are respectively connected to the blanket body. It is connected to a controller 4 attached to one edge as described later. In FIG. 1, the first heater cable 2 is drawn by a solid line, and the second heater cable 3 is drawn by a dotted line for the sake of simplicity in distinguishing the two heater cables 1 and 2. At the time of use, the controller 4 is connected to a commercial AC power supply (not shown) via a power cord, whereby the cables 2 and 3 are each heated to provide heating.

The controller 4 is connected to the controller 4 via a flexible connection cable (not shown) extending between the controller 4 and the edge of the blanket body 1 without directly attaching the controller to the blanket body 1 so as to improve usability. You may.

As the first heater cable 2, a temperature-sensitive heating wire whose cross section is shown in FIG. 2 is used. In detail, reference numeral 5 in FIG. 2 denotes a core material formed by twisting an electrically insulating yarn, and a first heat generating wire 6 as a primary conductor that generates resistance heat is wound around the core material. These are arranged at the center of the first heater cable 2. The first heating wire 6 is covered with an electrically insulating temperature-sensitive layer 7. The temperature-sensitive layer 7 includes a temperature-sensitive conductor described below and a first temperature-sensitive conductor.
It has a thermistor characteristic in which the electrical resistance (impedance) changes in accordance with a change in temperature between the heating wire 6 and allows a leakage current from the first heating wire 6 to flow, and is made of, for example, polyvinyl chloride. A temperature sensing line as a second conductor, that is, a temperature sensing conductor 8 is provided on the outer circumference of the temperature sensing layer 7, and is wound around the outer circumference of the temperature sensing layer 7. The temperature-sensitive conductor 8 is covered with an insulating sheath 9 as a sheath layer made of an electrically insulating synthetic resin.

In the first heater cable 2 having such a coaxial structure, the first heating wire 6 generates heat by the current supplied thereto to heat the blanket main body 1 and, at that time, the first heating wire 6. A leak current leaking from the wire 6 to the temperature-sensitive conductor 8 via the temperature-sensitive layer 7 is detected by the temperature-sensitive conductor 8. Then, based on such temperature detection, the controller 4
The amount of current supplied to the first heating wire 6 of the first heater cable 2 is controlled, whereby the heating value of the first heating wire 6 is adjusted to maintain the temperature of the blanket body 1 at a desired temperature. ing.

As the second heater cable 3, a short-circuit heating wire whose cross section is shown in FIG. 3 is used. For details, see 10 in FIG.
Is a core material formed by twisting an electrically insulating yarn, and a second heat generating wire 11 as a primary conductor that generates resistance heat is wound around the core material. These are arranged at the center of the second heater cable 3. The second heating wire 11 is an electrically insulating short-circuit layer 1
2 coated. The short-circuit layer 12 melts when the temperature becomes higher than a predetermined temperature (for example, 120 ° C.) due to a change in temperature between the short-circuit conductor and the second heating wire 11 described below. Become. A short-circuit detection line as a second conductor, that is, a short-circuit conductor 13 is provided on the outer periphery of the short-circuit layer 12, and is wound around the short-circuit layer 12. The short-circuit conductor 13 is covered with an insulating sheath 14 as a sheath layer made of an electrically insulating synthetic resin.

In the second heater cable 3 having such a coaxial structure, the second heating wire 10 generates heat by the current supplied thereto, and heats the blanket body 1. When the temperature of the blanket main body 1 rises and the temperature of the short-circuit layer 12 becomes higher than a predetermined temperature (abnormal temperature), the short-circuit layer 12 is melted. 12 is short-circuited. Based on the detection of such a short circuit, the controller 4 performs a control operation of stopping the power supply to both of the heater cables 2 and 3, whereby the blanket body 1 is
Is prevented from being abnormally raised and overheated.

The first and second heater cables 2 and 3 having the above-mentioned construction are substantially the same length, and are arranged close to and parallel to each other, and a heating element 1 for heating the blanket body 1 from the inside thereof.
5 are formed. The proximity distance between the heating wires 6 and 11 of the two cables 2 and 3 is set to 10 cm or less. Setting such a close distance is desirable in that a magnetic field canceling function described later can be obtained sufficiently reliably in practical use, and it is difficult to obtain a magnetic field canceling action as expected at a distance longer than this.

The first and second heater cables 2 and 3 electrically connect the two heating wires 6 and 11 in parallel, and the directions of the currents flowing through the heating wires 6 and 11 are opposite to each other. It is built into the blanket body 1 as shown. To do so, both cables 2 and 3 are connected to the controller 4
Are connected to a pair of common terminals 4a and 4b as follows.

That is, as shown in FIG. 1, one end 2a of the first heater cable 2 and the other end 3b of the second heater cable 3 are connected to one common terminal 4a, respectively, and short-circuited. Furthermore, the other end 2b of the first heater cable 2 and one end 3a of the second heater cable 3 are connected to the other common terminal 4b, respectively, and short-circuited. Therefore, the two heater cables 2 and 3 are electrically connected in parallel. Then, one of the heater cables 2 and 3 (for example, the first heater cable 2 in FIG. 1) and the other (for example, the second heater cable 3 in FIG. 1) have a crossing and form a loop. After being twisted as described above, it is arranged in parallel with the one heater cable. Thereby,
The directions of the currents flowing through the heating wires 6 and 11 of these cables 2 and 3 are reversed.

Since the controller 4 has a pair of common terminals 4a and 4b as described above, the amount of current flowing through the heating wires 6 and 11 of the heater cables 2 and 3 via the controller 4 is equal. It has become. The controller 4 includes a well-known temperature controller (not shown), a power switch, a pilot lamp, and the like, which can arbitrarily set the temperature from the outside.

In the electric blanket having the above-described configuration, a current flows through the heating wire 6 of the first heater cable 2 in a direction indicated by a solid arrow in FIG. Second heater cable 3
Current flows in the direction indicated by the dotted arrow in FIG. 1 to generate heat in the heating lines 6 and 11 respectively, thereby heating the entire blanket main body 1 and realizing heating for the user.

In such heating, both heating wires 6, 11
Are the same, the respective heating wires 6, 1
A magnetic field of the same strength is generated around 1 in accordance with Fleming's left hand rule, but since the current directions to the heating wires 6 and 11 are opposite as described above, the two magnetic fields are canceled by each other. , So as not to leak outside. Therefore, the electric blanket having the above configuration can be used in a state in which the leakage magnetic field is extremely small, so that the concern that the electric blanket may have a bad influence on human health can be solved.

In order to enable use in such a very low magnetic field, the heating wires 6 and 11 of the two heater cables 2 and 3 are electrically connected in parallel as described above. There is no need to use coaxial lead wires for supplying current to the heating wires 6 and 11 in opposite directions. The terminals of the heating wires 6 and 11 are connected to a pair of common terminals 4a and 4b of the controller 4. This can be achieved by: Therefore, since it is not necessary to use expensive coaxial cable leads, it can be manufactured at low cost.

In the above-mentioned use condition, the first heater cable 2 detects a leak current leaking from the first heating wire 6 through the temperature sensing layer 7 to the temperature sensing conductor 8. Accordingly, the first heating wire 6 is controlled by the controller 4.
The desired heating temperature can be obtained by controlling the amount of current supplied to the heater.

Then, the electric blanket having the above-mentioned structure is provided with the respective heating wires 6, 1,
1 are electrically connected in parallel, so that the temperature control of the blanket body 1 can be improved in the temperature detection accuracy.
That is, the heating wire 6 of the first heater cable 2 electrically connected in parallel with the heating wire 11 of the second heater cable 3.
In this case, only a voltage drop corresponding to the length of the wire 6 is caused from one end to the other end, and the voltage drop of the second heating wire 11 does not affect the voltage drop.

As described above, in the temperature control, the accuracy of detecting the temperature of the first heater cable 2 having the temperature-sensitive structure is not affected by the voltage drop corresponding to the length of the heating wire 11 of the second heater cable 3. In addition, the degree of reduction of the leakage current due to the voltage drop is reduced, and the error between the temperature and the actual temperature from the leakage current is reduced. Therefore, the temperature detection accuracy of the first heater cable 2 can be improved, and the temperature of the blanket main body 1 can be reliably controlled.

Further, a second heater cable 3 of an electric blanket
Is a short-circuit heating wire having a short-circuit layer 12 that short-circuits at a predetermined temperature or higher. Therefore, when the cable 3 reaches a predetermined temperature or higher, the short-circuit layer 12 melts, and the second heat-generating wire 11 and the outside of the second heat generating wire 11 An abnormal temperature of the blanket main body 1 can be detected by short-circuiting the short-circuit conductor 13. Therefore, based on this detection, the controller 4 operates so as to cut off the current supply to the first and second heater cables 2 and 3, thereby causing a local abnormal temperature, that is, a so-called heat spot, in the blanket body 1. In such a case, it is possible to detect this and secure the safety in use.

FIG. 4 shows a configuration of an electric carpet according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in the following points. The heater body is formed of a carpet body 21 corresponding to a blanket body. A first heating element 15a including the first and second heater cables 2 and 3 is disposed in a first heating area A of the carpet body 21 and a second heating element adjacent to the area A is provided. In the area B, a first heating element 15b including the first and second heater cables 2 and 3 is provided. Terminal portions of both heating elements 15a and 15b individually arranged in these areas A and B are connected to the controller 4, respectively.

In this connection, one common terminal 4a is connected to one end 2a of the first heater cable (temperature-sensitive heating wire) 2 and the other end 3b of the second heater cable (short-circuit heating wire) 3 in the first heating element 15a. Are connected and short-circuited, and one end 2a of the first heater cable (temperature-sensitive heating wire) 2 and the other end 3b of the second heater cable (short-circuit heating wire) 3 in the second heating element 15b are connected. Each is connected and short-circuited. Similarly, the other end 2b of the first heater cable 2 and one end 3a of the second heater cable 3 in the first heating element 15a are short-circuited to the other common terminal 4b. The other end 2b of the first heater cable 2 and the one end 3a of the second heater cable 3 in the two heating elements 15b are connected and short-circuited. Thus, the first and second heating elements 15a and 15b are also provided electrically in parallel. Then, for example, the second heater cable 3 is disposed along the first heater cable 2 in parallel with the first heater cable 2 after being twisted so as to form a loop with an intersection, thereby forming a loop. The directions of the currents flowing through the heating wires 6 and 11 of the cables 2 and 3 are reversed.

The controller 4 also has a changeover switch (not shown), so that at least one of the first and second heating elements 15a and 15b can be selected and used by the changeover operation. Since the configuration other than the points described above is the same as the configuration of the electric blanket according to the first embodiment, the same components are denoted by the same reference numerals as those in the first embodiment. Description is omitted.

In the electric carpet according to the second embodiment, the first heating element 1 for heating the first heating area A is also provided.
5a and the second heating element 15b for heating the second heating area B are the same as the heating elements used in the electric blanket according to the first embodiment, and have the same connection structure to the controller 4. Therefore, the same effect as that of the electric blanket according to the first embodiment can be obtained to solve the problem of the present invention.

Although each of the above embodiments has been configured as described above, the present invention is not limited to these embodiments. For example, when the present invention is implemented from the viewpoint of solving only the first problem, a temperature-sensitive heating wire with a temperature sensing function having a heat-sensitive layer on one of the first and second heater cables 2 and 3 is provided. It is also possible to employ a heater cable composed of the following, and use a similar heater cable or a heater cable having only a heating function as the other cable. Further, the first and second heater cables 2 and 3 are wound with a temperature-sensitive conductor 8 or 13 around the outer periphery of the core material 1 or 10, and these are covered with a temperature-sensitive layer 7 or 12.
The heat-generating wire 6 or 11 may be wound around the outer periphery of the temperature-sensitive layer 7 or 12 and may be covered with an insulating coating 9 or 14.

[0041]

The present invention is embodied in the form described above and has the following effects. According to the invention described in claim 1, since the magnetic fields generated by both the heating wires of the first and second heater cables arranged close to and parallel to each other can be canceled out, the leakage magnetic field can be reduced and used. it can. In addition, since it is not necessary to use a coaxial structure lead wire for both the heating wires to cancel the generated magnetic field, it is possible to obtain the heating wires at low cost. In addition, since the respective heating wires of the first and second heater cables are electrically connected in parallel, a leak current from the heating wire to the temperature-sensitive conductor is detected to obtain a desired heating temperature. The temperature detection accuracy of the heater cable of the temperature-sensitive structure that enables the temperature detection of the heater body is not affected by the voltage drop of the heating wire of the other heater cable, and the heat generation of the heating wire is controlled. Reliable temperature control can be performed without lowering the temperature detection accuracy.

According to the second aspect of the invention, which is dependent on the first aspect, in addition to the effect of the first aspect, a short-circuit layer is provided when the heater body reaches an abnormal temperature. Since the controller secures the safety based on the detection of the abnormal temperature by the heater cable, it is possible to provide an electric heater that can also secure the safety against abnormal overheating.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a wiring structure of a heater cable in an electric blanket according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a first heater cable used in the electric blanket according to the first embodiment.

FIG. 3 is a sectional view showing a configuration of a second heater cable used in the electric blanket according to the first embodiment.

FIG. 4 is a plan view schematically showing a wiring structure of a heater cable in an electric carpet according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Blanket main body (heater main body), 2 ... 1st heater cable, 3 ... 2nd heater cable, 2a, 3a ... One end of heater cables 2, 3 2b, 3b ... The other end of heater cables 2, 3 ... Controller 4a ... One common terminal of the controller 4b ... Other common terminal of the controller 6 ... First heating wire 7 ... Temperature sensing layer 8 ... Temperature sensing conductor 11 ... Second heating wire 12 ... Short circuit layer , 13 ... short-circuit conductor, 15, 15a, 15b ... heating element, 21 ... carpet body (heater body).

Claims (2)

[Claims] 1. An electric heater in which a heating element having a heating wire is incorporated in a heater body used in a planar shape, and heating is performed by controlling energization of the heating wire by a controller. The heating element is formed by first and second heater cables which are individually provided and arranged close to each other and parallel to each other. At least one of the first and second heater cables includes the heating wire and the heating element. A temperature-sensitive conductor that is provided along a line and detects a leakage current, and is made of a material whose electric resistance changes according to a temperature change, and is interposed between the heat-generating wire and the temperature-sensitive conductor, and A heater cable having a temperature-sensitive conductor and a temperature-sensitive layer through which the leakage current passes is adopted, and both heat-generating wires of the first and second heater cables are electrically connected in parallel. Direction of the current flowing through Electric heater for the two heater cable such that the opposite is provided, and is characterized in that in the same manner the amount of current flowing between the heating wire to. 2. The first heater cable according to claim 1, wherein said first heating cable is provided along said first heating wire, a temperature-sensitive conductor for detecting a leakage current is provided along said first heating wire, and an electric resistance changes according to a temperature change. A temperature-sensitive layer interposed between the first heating wire and the temperature-sensitive conductor and configured to pass the leakage current from the first heating wire to the temperature-sensitive conductor; A heater cable is formed between the second heating wire, the short-circuit conductor provided along the second heating wire, and a material that melts at a predetermined temperature, and is interposed between the second heating wire and the short-circuit conductor. 2. The electric heater according to claim 1, further comprising a short-circuit layer that short-circuits the second heating wire and the short-circuit conductor when melted. 3.