JPH11135250A - Coil device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop power supply to a coil intermediately during burning of the coil by arranging a thermal means consisting of thermally soluble member melting at a temperature more than a given value and a conductor arranged on the both sides through it on the surface of the coil so that it crosses the winding direction of the coil. SOLUTION: A short wire 5 adhered on the surface of a secondary coil 23 is equipped with a first wire 51, an insulation film 53 covering the first wire 51, and a second wire 52 wound around the insulation film 53, and the insulation film 53 is made of nylon or others melting at a given temperature. Because the short wire 5 is arranged so that it crosses the winding direction of the secondary coil 23, even if burning occurs at any part of the secondary coil 23 the short wire always has a part bringing into contact with a burning part, where the insulation film 53 intermediately melts and the first wire 51 conducts to the second wire 52. This conduction causes current flowing through the second wire 52 to be entered into a microcomputer 62 of a detecting circuit 6. The microcomputer 62 controls a switching circuit 8 to be released and breaks power supply to a primary coil 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil device used for a step-up transformer of a high-frequency heating device.

[0002]

2. Description of the Related Art A fuse is conventionally provided as a safety device in a coil device used for a transformer such as a high-frequency heating device in order to prevent an accident due to abnormal heating of the coil device.

In general, two types of fuses of this type are often used. One is a thermal fuse that blows due to the temperature due to abnormal heat generation of the coil device and cuts off the power supply from the power supply. And an overcurrent fuse for interrupting power supply from a power supply.

In general, an electronic device is provided with an overcurrent fuse on a power supply side of a circuit. For example, in the case of a microwave oven, as shown in FIG. 7, an overcurrent fuse 96 is provided between a high voltage circuit 95 including a step-up transformer 91 and a power supply.

Here, in the coil wound around the step-up transformer 91, if the insulation between the respective windings of the coil decreases due to scratches, aging, etc., the windings are short-circuited, and the short-circuited windings are short-circuited. May be burned out.

For example, as shown in FIG. 4A, it is assumed that the secondary coil 93 of the step-up transformer 91 has a flaw 94. The scratches 94 gradually increase due to aging as shown in FIG. Eventually, the winding of the secondary coil 93 burns as shown in FIG. If a part of the coil winding is burned, it is usually 1
Burns over the circumference.

In the overcurrent fuse 96, FIG.
In the case of slight burnout of the winding as shown in (c), since the leak current is small, burnout of the winding cannot be detected.
As shown in FIG. 4D, power supply to the coil could be cut off only after the winding was burned to some extent.

On the other hand, as shown in FIG. 8, it has been attempted to separately attach a temperature fuse 97 to the core 92 for a transformer such as a microwave oven which has a possibility of generating heat.

In this case, if the winding of the coil is burnt, it takes time for heat to be transferred from the burnt portion to the portion where the thermal fuse 97 is attached, during which burnout proceeds. There was a risk of it.

[0010]

In any of the fuses, there is no problem if only safety is taken into consideration. However, smoke or the like that increases due to the progress of coil burnout gives the user a sense of fear or discomfort. There was a problem.

The present invention has been made in view of the above problems, and has as its object to provide a coil device that can immediately cut off power supply to a coil when the coil is burnt.

[0012]

According to the present invention, there is provided a coil device comprising:
A heat-sensitive means comprising a heat-soluble member that melts at a predetermined temperature or higher and conductors disposed on both sides via the heat-soluble member is disposed on the coil surface so as to intersect the winding direction of the coil. In such a configuration, when the coil is burnt, the heat-sensitive means near the burnt coil immediately melts, and the conduction between the conductors changes.

[0013] Further, there is provided a shutoff means which is connected to the heat sensitive means and cuts off the power supply to the coil based on a change in the conduction state between the conductors. Thereby, the power supply to the coil is cut off based on the change in the conduction state between the conductors.

In the heat sensing means, one of the conductors is connected to an electric circuit, and the other is connected to a detection circuit for detecting a change in the conduction state between the conductors. In such a configuration,
When the coil is burnt, the heat-soluble member near the burnt coil melts, and the conduction between the conductors changes.

The heat-sensitive means comprises a first conductive wire and a second conductive wire disposed close to each other via an insulating film as a heat-soluble member, and one of the first conductive wire and the second conductive wire supplies power to the coil. And the other is connected to a detection circuit that detects a short circuit between the first conductor and the second conductor. In such a configuration, when the coil is burned, the insulating film near the burned coil is melted, and conduction between the first conductor and the second conductor is performed, so that the power supply circuit passes through the first conductor and the second conductor. Current flows through the detection circuit.

The heat-sensitive means comprises a first conductive wire and a second conductive wire connected via a heat fusing wire as a heat-soluble member, and one of the first conductive wire and the second conductive wire supplies power to the coil. And the other is connected to a detection circuit for detecting a disconnection between the first conductor and the second conductor. In such a configuration, when the coil is burned, the heat fusing wire near the burned coil melts and the conduction between the first conductor and the second conductor is cut off. The current flowing to the detection circuit via the two conductors stops flowing.

Further, the shut-off means comprises a switching circuit arranged between the power supply circuit and the coil and operated by detection of the detection circuit. Thus, the power supply from the power supply to the coil is cut off by opening the switching circuit.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. (First Embodiment) In the case where the coil device according to the present embodiment is applied to a step-up transformer of a microwave oven,
This will be described below.

As shown in FIG. 1, the microwave oven includes a step-up transformer 2 connected to a commercial power supply 1 as a power supply circuit,
A rectifier circuit 3 connected to the step-up transformer 2;
, A short-circuit line 5 as a heat-sensitive means attached to the booster circuit, and a detection circuit 6 connected to the short-circuit line 5.
, An overcurrent fuse 7 is inserted, and a switching circuit 8 is inserted between the overcurrent fuse 7 and the step-up transformer 2.

The step-up transformer 2 includes a core 21, a primary coil 22, a secondary coil 23 and a heater coil 24 wound around the core 21. In the microwave oven having such a configuration, when a voltage supplied from the commercial power supply 1 is applied to the primary coil 22, the voltage is stepped up by the step-up transformer 2 and a high voltage is generated in the secondary coil 23. Further, this voltage is half-wave rectified by a rectifier circuit 3 including a capacitor 31 and a diode 32 and applied to the magnetron 4.

On the other hand, the voltage generated in the heater wire heats the cathode of the magnetron 4 to excite electrons. As a result, the magnetron 4 generates a microwave, and the food or the like is induction-heated.

The short-circuit wire 5 attached to the surface of the secondary coil 23 of the step-up transformer 2 is arranged so as to cross the winding direction of the secondary coil 23 as shown in FIG.
As shown in FIG. 3, the short-circuit line 5 includes a first conductor 51, an insulating film 53 covering the first conductor 51, and an insulating film 53.
And a second conductor 52 spirally wound around the second conductor 52.
A protective film 54 that covers the entirety including the conductive wire 52;
The insulating film 53 is made of nylon or the like that melts at a predetermined temperature.

The first conductor 51 is connected to the commercial power source 1 to 1
While being connected to the electrical path that supplies power to the next coil 22,
The second conductor 52 is connected to the detection circuit 6. The secondary coil 23 of the step-up transformer 2 having such a configuration includes:
It is assumed that the winding is burned as shown in FIG.

Since the short-circuit wire 5 is disposed so as to cross the winding direction of the secondary coil 23, no matter what part of the secondary coil 23 is burned, the short-circuit wire 5 always comes into contact with the burned winding. There are parts. Therefore, of the short-circuit lines 5,
The portion of the insulating film 53 that is in contact with the burnt winding is immediately melted, and the first conductor 51 and the second conductor 52 are conducted.

When the conduction between the first conductor 51 and the second conductor 52 is conducted, the current flowing through the second conductor 52 is rectified and smoothed by the rectification / smoothing circuit 61 of the detection circuit 6 and transmitted to the microcomputer 62. Is entered.

The microcomputer 62 that has received this signal switches the switching circuit 8
, The power supply from the commercial power supply 1 to the primary coil 22 is cut off. According to the present embodiment, the short-circuit wire 5 provided as the heat-sensitive means
Is arranged so as to intersect with the winding direction, the burnout occurring in the secondary coil 23 can be reliably and immediately detected, and the power supply can be cut off. Therefore, the secondary coil 23
Even if the burnout occurs, the user does not feel scared by smoke or the like, and the reliability can be improved. (Second Embodiment) In the first embodiment, the case where the short-circuit wire 5 is used as the heat-sensitive means has been described. For example, as shown in FIG. 5, the first conductor 55 and the second conductor 55 are used. 56 are connected via a thermal fusing wire 57 made of silver, tin, or the like, and the thermal fusing wire 57 is attached so as to intersect with the winding direction of the secondary coil as in the first embodiment. Is also good.

In this case, as in the first embodiment, the first conductor 55 is connected to an electric circuit for supplying power from the commercial power supply 1 to the primary coil 22, while the second conductor 56 is connected to the detection circuit. 6, the detection circuit 6 includes a rectifying / smoothing circuit 61.
And a microcomputer 62.

Therefore, normally, a current flows from the commercial power supply 1 to the detection circuit 6 via the first conducting wire 55, the heat fusing wire 57, and the second conducting wire 56. Then, when the secondary coil 23 of the step-up transformer 2 is burned, the contact portion between the burnt winding and the heat fusing wire 57 is immediately melted, and the state between the first conducting wire 55 and the second conducting wire 56 is broken. .

When the first conductor 55 and the second conductor 56 are disconnected, the current flowing from the commercial power supply 1 to the detection circuit stops flowing. Thereby, the microcomputer 6 of the detection circuit 6
2 opens the switching circuit 8, and the power supply from the commercial power supply 1 to the primary coil 22 is cut off.

According to the present embodiment, since the thermal fusing line 57 provided as a heat sensing means is disposed so as to intersect with the winding direction of the secondary coil 23, the burning generated in the secondary coil 23 can be reliably prevented. In addition, the power supply can be immediately detected and the power supply can be cut off. Therefore, even when the secondary coil 23 is burned, the user does not feel fear due to smoke or the like, and the reliability can be improved.

In the first and second embodiments, the short-circuit line 5 or the thermal fusing line 57 as the heat-sensitive means is used.
Is arranged so as to intersect with the winding direction of the secondary coil 23, but is not limited thereto. For example, as shown in FIG. 23 may be arranged in a wave shape reciprocating between the ends.
In this case, the short-circuit wire 5 or the heat fusing wire 57 and the secondary coil 2
Since the number of contact portions with the coil 3 increases, burnout of the coil can be detected more reliably.

In the first and second embodiments, the short-circuit line 5 or the heat-fusion line 57 as the heat-sensitive means is used.
Are arranged in the secondary coil 23, but may be arranged in the primary coil 22. Further, the primary coil 22 and the secondary coil 2
3 may be arranged.

[0033]

According to the present invention, since the heat sensing means is arranged on the coil surface so as to intersect with the winding direction of the coil, it is possible to reliably and immediately detect the burnout occurring in the secondary coil. , The power supply can be cut off. Therefore, even if the secondary coil is burned, the user does not feel fear or discomfort due to smoke or the like, and the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a circuit configuration of a microwave oven according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating an arrangement of short-circuit lines in FIG.

FIG. 3 is a partially cutaway side view illustrating a configuration of a short-circuit line.

FIG. 4 is an explanatory diagram illustrating a process in which a coil leads to burnout.

FIG. 5 is a perspective view illustrating an arrangement of a thermal fusion line in a second embodiment.

FIG. 6 is a perspective view showing another arrangement of the heat sensing means.

FIG. 7 is a block diagram illustrating a circuit configuration of a general microwave oven.

FIG. 8 is a perspective view showing an arrangement of a conventional thermal fuse.

[Explanation of symbols]

 2: Step-up transformer 22: Primary coil 23: Secondary coil 5: Short-circuit line 51: First conductor 52: Second conductor 53: Insulating film 8: Switching circuit

Claims (6)

[Claims] 1. A heat-sensitive means comprising a heat-soluble member that melts at a predetermined temperature or higher and conductors disposed on both sides via the heat-soluble member is disposed on the coil surface so as to intersect the winding direction of the coil. A coil device characterized in that: 2. The coil device according to claim 1, further comprising: a cut-off unit connected to the heat-sensitive unit and configured to cut off power supply to the coil based on a change in a conduction state between the conductors. 3. The heat sensing means according to claim 1, wherein one of the conductors is connected to an electric circuit, and the other is connected to a detection circuit for detecting a change in a conduction state between the conductors. Or the coil device according to 2. 4. The heat-sensitive means comprises a first conductor and a second conductor which are disposed close to each other via an insulating film as a heat-soluble member, and one of the first conductor and the second conductor supplies electric power to the coil. 4. The coil device according to claim 3, wherein the coil device is connected to a power supply circuit to be supplied, and the other is connected to a detection circuit that detects a short circuit between the first conductor and the second conductor. 5. The heat-sensitive means comprises a first conductor and a second conductor connected via a heat fusing wire as a heat-soluble member, and one of the first conductor and the second conductor supplies electric power to the coil. And the other is connected to the first power supply circuit.
The coil device according to claim 3, wherein the coil device is connected to a detection circuit that detects a disconnection between the conductor and the second conductor. 6. The circuit according to claim 3, wherein the cut-off means is provided between the power supply circuit and the coil, and includes a switching circuit that is operated by detection of the detection circuit. The coil device as described.