JP4049110B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker used in general households and the like.

  In general, this type of induction heating cooker has a large heating power and generally uses a temperature detection element such as a thermostat or a thermistor in order to detect an abnormal temperature rise of the heating coil. On the other hand, in order to satisfy cooking performance, a device having a strong heating power has been developed. When a high heating power heating coil began to rise abnormally, it quickly reached a high temperature, making it difficult to control the current instantaneously.

  In order to avoid the abnormal temperature rise state as described above, some conventional induction heating cookers have a thermostat on the lower surface of the heating coil to cut off the current at an abnormally high temperature (for example, see Patent Document 1).

The conventional induction heating cooker, the current to the heating coil is abnormally high temperature state since even heating coils until cut off thermostat detects was kept flowing the rated current.
JP-A-4-248290

However, the conventional induction heating cooker, the current to the heating coil even if an abnormally high temperature state heating coil to the thermostat is cut off by detecting were those continues to flow specified current. Further, since it is assumed that an abnormally high temperature is detected, the operation is difficult when the detection circuit fails.

  The present invention solves the above-described conventional problems, and reduces the current to the heating coil when the heating coil reaches an abnormally high temperature, thereby reducing the electromagnetic energy supplied to the object to be heated (generally a pan or the like). Thus, an object of the present invention is to provide an induction cooking device that prevents the spread of fire.

In order to solve the above conventional problems, the induction heating cooker of the present invention, flow and top plate made of a nonmagnetic material, and heating coils located in the top plate downward, the high-frequency current to the heating coil and a control circuit, the heating coil is an induction pressure thermal coil, supporting said induction heating coil to form a first holding member having a housing portion, a portion of the magnetic path of the induction coil Blow And the second holding member that engages with the first holding member, the induction heating coil is disposed above the heating coil, and the outer periphery of the second holding member on which the ferrite is placed the step portion engaged with the engaging portion provided on a bottom portion of the accommodating portion of the first holding member, wherein the ferrite is a structure that will be housed in the housing portion of the first holding member, the second the heat distortion temperature of the holding member at about 0.99 ° C., the first holding member In which the heat distortion temperature was formed at a lower thermoplastic resin.

  By having this second holding member, when the heating coil reaches an abnormally high temperature, the second holding member melts and drops off the ferrite due to the material properties of the second holding member, so that the heating coil is the object to be heated. Since the propagation efficiency of electromagnetic energy to a pan or the like is lowered, an abnormal temperature rise of an object to be heated can be prevented.

  In the induction heating cooker of the present invention, when the heating coil reaches an abnormally high temperature, the second holding member, which is a constituent member of the heating coil, melts to reduce propagation of electromagnetic energy to a heated object such as a pan. Thus, it is possible to provide an induction heating cooker that reduces the abnormally high temperature of the object to be heated.

The first invention includes a top plate formed of a non-magnetic material, and the heating coils located in the top plate downward, and a control circuit for supplying a high-frequency current to the heating coil, the heating coil induction pressure a heat coil, supporting said induction heating coil, a first holding member having a housing portion, and the ferrite that forms part of the magnetic path of the induction coil to lock said first holding member A second holding member , wherein the induction heating coil is disposed above the heating coil, and an outer peripheral step portion of the second holding member on which the ferrite is placed is accommodated in the first holding member. engages with the engaging portion provided on the bottom parts, in the ferrite said first and housed Ru configured in the receiving portion of the holding member, the thermal deformation temperature of the second holding member is about 0.99 ° C., Formed of a thermoplastic resin having a lower thermal deformation temperature than the first holding member; Further, when the heating coil reaches an abnormally high temperature, it is possible to provide an induction heating cooker that can reduce the propagation of electromagnetic energy to the object to be heated and reduce the abnormal temperature rise of the object to be heated. is there.

  In the second aspect of the invention, the temperature at which propagation of electromagnetic energy to the object to be heated is reduced by inducing the heat deformation temperature of the second holding member to be lower than the heat resistance temperature of the insulating coating of the induction heating coil. It is possible to provide an induction heating cooker that can reduce the propagation of electromagnetic energy to an object to be heated without breaking the insulation performance of the heating coil without breaking the insulation performance.

According to the third aspect of the present invention, the heating coil reaches an abnormally high temperature by including a magnetic detection device, detecting a change in magnetism with the magnetic detection device, and stopping the power supply to the heating coil by the control circuit. In this case, it is possible to stop the heating of the object to be heated at an abnormally high temperature by detecting the start of the fall of the ferrite as a magnetic change and cutting off the energization to the heating coil by the control circuit.

A fourth invention comprises a detection circuit for detecting a change in current through the induction heating coil, an abnormal increase in temperature of the heated object by stopping the supply of power to the heating coil to test known changes in the current An induction heating cooker that can be stopped can be provided.

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

(Embodiment 1)
FIG. 1 is an external view of an induction heating cooker according to Embodiment 1 of the present invention.

  FIG. 2 is a bird's eye view of the upper part of the induction heating cooker according to the first embodiment of the present invention.

  A top plate 2 made of heat-resistant glass is provided on the top surface of the substantially rectangular parallelepiped main body 1. A pair of heating coils 3 are arranged on the left and right under the top plate 2. The heating coil 3 is biased to the top plate 2 by a coil spring 4. A roaster unit 6 for grilling fish is stored and fixed at the lower left of the main body 1. A control board 7 that forms a control circuit that performs overall electrical control is housed in the lower right of the main body 1. Near the center of the rear of the main body 1, a radiant heater 9 is arranged that heats an object to be heated on the top 2 via the top 2 by heating with the heater 8. A cooling device 10 composed of a sirocco fan driven by a motor for cooling the control board 7 is arranged on the right rear side of the main body 1. From a suction / exhaust grill 11 provided at the rear portion of the top plate 2. Intake and exhaust are performed to cool the inside of the main body 1.

  The entire electric operation is performed on the entire surface of the main body 1 by the operation unit 12 which is used by popping out the rotation with the lower part as a shaft.

  FIG. 3 is a partial cross-sectional view of heating coil 3 according to Embodiment 1 of the present invention. The heating coil 3 has an induction heating coil 13 wound in a disk shape at the top, and a second holding member 16 provided at the bottom of the storage portion 14 on the first holding member 15 in which the storage portion 14 is arranged radially. The step 18 on the outer periphery of the holding member 17 is locked, and a rectangular parallelepiped ferrite 19 is placed on the second holding member 17 and stored in each storage portion 14. The upper portion of the storage portion 14 is formed of a thermosetting resin, covered with an insulating member 20 that electrically insulates the induction heating coil 13 and the ferrite 19, and the induction heating coil 13 is disposed above the insulating member 20.

  In the center of the heating coil 3, a temperature detecting element 21 is disposed so as to protrude upward. The temperature detection element 21 detects the temperature of the lower surface of the top plate 2 and transmits it to the control board 7. Since the spatial distance between the heating coil 3 and an object to be heated such as a pan is an important factor in electromagnetic induction heating, the buffer rubber 22 is used as a heating coil in order to keep the distance between the heating coil 3 and the top plate 2 constant. 3 are attached at three locations on the outer periphery, and the distance between the heating coil 3 and the top plate 2 is kept constant via the buffer rubber 22.

  A Hall element 23, which is a magnetic detection device, is fixed to the lower part of the first holding member 15. The Hall element 23 detects the magnetic strength in the vicinity of the lower surface of the heating coil 3.

  FIG. 4 illustrates a state in which the second holding member 17 of the heating coil 3 in the first embodiment of the present invention is melted at an abnormally high temperature.

When the heating coil 3 reaches an abnormally high temperature, the ferrite 19 is a sintered alloy and can withstand temperatures of several hundred degrees. The first holding member 15 has not yet reached the heat deformation temperature. When the second holding member 17 reaches its heat deformation temperature (about 150 degrees) via the ferrite 19 and the first holding member 15, the second holding member 17 starts to melt. At the same time the ferrite 19 on the second holding member 17 falls down began to fall off gradually by its own weight.

  About the induction heating cooking appliance comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  An object to be heated such as a pan is placed on the top plate 2 of the induction heating cooker, and the operation unit 12 is operated to supply electric power from the control board 7 to the heating coil 3. Normally, the temperature detection element 21 detects the temperature of the object to be heated via the top plate 2 and controls the power supply to the heating coil 3. The electric power of several tens of kilohertz supplied to the heating coil 3 is transmitted from the induction heating coil 13 to the object to be heated by electromagnetic induction. A part of the magnetic circuit is transmitted during propagation of electromagnetic energy from the induction heating coil 13 to the object to be heated. Ferrite 19 is formed on the surface.

  If an abnormality occurs in the control board 7 and power supply to the heating coil 3 cannot be controlled, or if the temperature detection element 21 is not normally controlled and power is continuously supplied to the heating coil 3, the temperature of the induction heating coil 13 is increased. As the temperature rises, the temperature of the second holding member 17 becomes higher than the heat deformation temperature. At this time, the heat of the induction heating coil 13 heats the second holding member 17 via the first holding member 15 and the ferrite 19.

  The second holding member 17 will eventually melt. As the second holding member 17 melts, the ferrite 19 falls off. Since the temperature of the induction heating coil 13 when the ferrite 19 falls off does not exceed the heat resistance temperature (for example, 180 degrees in the case of H type) of the insulating coating (not shown) of the induction heating coil 13, the second holding member 17. Insulation of the induction heating coil 13 is maintained even when the ferrite melts and the ferrite 19 falls off. This is because the heat resistance temperature of the insulating film of the induction heating coil 13 is higher than the heat deformation temperature of the second holding member 17.

  The ferrite 19 forms a magnetic circuit of the heating coil 3, and magnetism leaks out of the magnetic circuit when the position of the ferrite 19 changes. The Hall element 23 detects this leakage magnetism or the change in leakage magnetism. As the ferrite 19 falls off, the magnetic coupling between the induction heating coil 13 and the object to be heated becomes weak, and the supply of electromagnetic energy to the object to be heated decreases. The hall element 23 detects the magnetic change and stops the power supply to the heating coil 3 by the control board 7.

  Here, even when the Hall element 23 cannot be controlled, the second holding member 17 melts and the ferrite 19 is dropped, so that the magnetic energy supply to the object to be heated is reliably reduced.

  With the above configuration, even if the control board 7 cannot accurately detect the temperature of the temperature detection element 21 or the power supply to the heating coil 3 cannot be normally controlled and the heating coil 3 reaches an abnormally high temperature, the temperature of the heating coil 3 Since the second holding member 17 melts and drops the ferrite 19 as it rises, the magnetic resistance of the magnetic circuit changes, the magnetic coupling becomes weak, and the supply of electromagnetic energy to the object to be heated decreases. This has the effect of suppressing the temperature rise of the heated object.

  In addition, the Hall element 23 can stop the power supply to the heating coil 3 by the control board 7 by detecting a change in magnetism due to magnetism leaking from the magnetic circuit before the ferrite drops off. With the above configuration, when the power supply is stopped at the Hall element 23 or when the control board 7 receives damage that cannot be controlled, the second holding member 17 melts and the ferrite 19 is dropped to be heated. It is possible to provide an induction heating cooker that can reduce power supply to an object and suppress an abnormally high temperature state of the object to be heated.

(Embodiment 2)
FIG. 5 is a partial cross-sectional view of the heating coil showing the second embodiment. The new code has a new shape and function, and the same name and the same code are exactly the same.

  As shown in FIG. 5, an opening 31 is provided below the first holding member 30 to provide a storage portion 32. After setting the ferrite 19 from below, the opening 31 is closed by the second holding member 33, and an adhesive material is provided. At 34, the second holding member 33 and the first holding member 30 are bonded to store the ferrite 19 in the storage portion 32. The upper surface of the first holding member 30 has a resin wall 35 to ensure electrical insulation performance with the induction heating coil 13. A magnetic detection coil 36 that is a magnetic detection device is disposed near the lower portion of the heating coil 3. The magnetic detection coil 36 detects the drop of the ferrite 19 and the control board 7 stops the power supply to the heating coil 3. With this configuration, it is possible to provide an induction heating cooker that can reduce the insulating member 20.

  In addition, a detection circuit (not shown) that detects a change in the current flowing through the induction heating coil 13 is built in the control board 7 that supplies power to the heating coil 3, thereby detecting the current flowing through the heating coil 3. 3 is detected and the power supply to the heating coil 3 is stopped, whereby the second holding member 33 is melted and the ferrite 19 is dropped to reduce the power supply to the object to be heated. The induction heating cooking appliance which can suppress the abnormally high temperature state of a heating thing can be provided.

  As described above, since the induction heating cooker according to the present invention is configured to control power supply to the heating coil by self-destruction, for example, not only cooking equipment but also industrial induction heating devices and electromagnetic heating rice cookers It can be applied to other uses.

External view of induction heating cooker in Embodiment 1 of the present invention Exploded bird's-eye view of induction heating cooker in Embodiment 1 of the present invention The fragmentary sectional view of the heating coil of the induction heating cooking appliance in Embodiment 1 of this invention The fragmentary sectional view at the time of the abnormally high temperature of the heating coil of the induction heating cooking appliance in Embodiment 1 of this invention The fragmentary sectional view of the heating coil of the induction heating cooking appliance in Embodiment 2 of this invention

Explanation of symbols

2 Top plate 3 Heating coil 7 Control board (control circuit)
13 Induction Heating Coil 14 Storage Unit 15 First Holding Member 16 Locking Unit 17 Second Holding Member 19 Ferrite 23 Hall Element (Magnetic Detection Device)
30 First holding member 32 Storage portion 33 Second holding member 36 Magnetic detection coil (magnetic detection device)

Claims (4)

Includes a top plate formed of a non-magnetic material, and the heating coils located in the top plate downward, and a control circuit for supplying a high-frequency current to the heating coil,
The heating coil is an induction pressure heat coils, said supporting an induction heating coil, a first holding member having a housing portion, and the ferrite that forms part of the magnetic path of the induction coil, said first A second holding member that locks with the holding member ;
Placing the induction heating coil on top of the heating coil;
The outer peripheral step portion of the second holding member on which the ferrite is placed is locked to a locking portion provided at the bottom of the accommodating portion of the first holding member, and the ferrite is held in the first holding position. a configuration that will be housed in the housing portion of the member,
The induction heating cooker formed of a thermoplastic resin having a heat deformation temperature of about 150 ° C. and a heat deformation temperature lower than that of the first holding member. The induction heating cooker according to claim 1, wherein a heat deformation temperature of the second holding member is lower than a heat resistant temperature of the insulating film of the induction heating coil. The induction heating cooking appliance of any one of Claims 1-2 provided with a magnetic detection apparatus, detecting the change of magnetism with the said magnetic detection apparatus, and stopping the electric power supply to a heating coil by a control circuit . The induction heating cooker according to any one of claims 1 to 2 , further comprising a detection circuit that detects a change in a current flowing through the induction heating coil, and detects a change in the current to stop power supply to the heating coil .

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