JP2006120495A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect temperature of an electric conductor with accuracy with an electric conductor temperature detecting means irrespective of rotation speed of a cooling fan. <P>SOLUTION: By fitting the electric conductor temperature detecting means 19 under the electric conductor 17 through a heat insulator 18, and setting up a windbreak rib 15a at a heating coil supporting member 15 on a periphery part of the temperature detecting means 19, an adverse effect of wind due to changes of rotation speed of the cooling fan or the like is hardly given, so that temperature of the electric conductor can be accurately transmitted to the electric conductor temperature detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an induction heating cooker that cooks using a pan made of a material having low magnetic permeability and high electrical conductivity such as aluminum or copper as an object to be heated.

  An induction heating cooker that generates a high-frequency magnetic field with an induction heating coil and heats an object to be heated such as a pan with eddy current by electromagnetic induction has been proposed (for example, a patent) Reference 1).

  FIG. 2 is a cross-sectional view of a conventional induction heating cooker. As shown in the figure, a main body 1 constituting the outline of the induction heating cooker, a top plate 2 made of an insulator such as a ceramic material or crystal glass having a thickness of 4 mm provided on the upper portion of the main body 1, and a top plate 2 is composed of a heated object 3 such as a pan placed on 2 and a heating coil support member 5 that supports the heating coil 4. The heating coil 4 is supplied with a high-frequency current from a drive circuit 6 having an inverter to generate a high-frequency magnetic field, and applies a high-frequency magnetic field to the object to be heated 3 to perform induction heating.

  In such a conventional induction heating cooker, a repulsive force is generated at the bottom of the article 3 to be heated away from the heating coil 4. When the object to be heated 3 is made of a high magnetic permeability material such as iron having a certain degree of resistivity, the repulsive force is relatively small because the current value required to obtain a desired heating output may be small. . In addition, since iron or the like is absorbed by the article to be heated 3, a magnetic attraction works and there is no fear that the article to be heated 3 will be lifted or displaced.

  On the other hand, when the object to be heated 3 is made of a material having a low magnetic permeability and high electrical conductivity such as aluminum or copper, the current to be supplied to the heating coil 4 is increased to obtain a desired heating output. It is necessary to induce a large current in the object 3. As a result, the resilience increases. Further, since the magnetic attraction force does not act on the aluminum heated object 3 as in the case of a high permeability material such as iron, the heated object 3 is heated by the action of the magnetic field of the heating coil 4 and the magnetic field of the induced current. A great force away from the coil 4 works. This force acts as buoyancy on the article 3 to be heated. When the weight of the object to be heated 3 is light, the object to be heated 3 may be lifted and moved from the mounting surface of the top plate 2 by this buoyancy. This tendency is conspicuous in the case of an object to be heated using aluminum having a specific gravity smaller than that of copper.

  FIG. 3A is a view of the direction of the current flowing through the heating coil 4 as viewed from the side of the object to be heated 3, and FIG. 3B is an induction to the object to be heated 3 based on the current flowing through the heating coil 4. It is the figure which looked at the eddy current which arises and is seen from the same direction as Fig.3 (a). As shown in FIG. 3, the eddy current flowing through the article to be heated 3 has a loop shape opposite to that of the current flowing through the heating coil 4 and having substantially the same shape. Therefore, the two annular currents are in the same state as two permanent magnets having substantially the same cross-sectional area as the area of the heating coil 4 placed with the same type of poles, for example, N and N poles facing each other. Become. As a result, a large repulsive force is generated between the heated object 3 and the heating coil 4.

  This phenomenon is remarkable when the material of the article to be heated 3 is a substance having high electrical conductivity such as aluminum or copper. On the other hand, even with the same low magnetic permeability material, nonmagnetic SUS is a material having a lower electrical conductivity than aluminum or copper, so that sufficient heat generation can be obtained even with a small amount of current flowing through the heating coil 4. Therefore, the eddy current flowing through the object to be heated 3 is also small, and therefore the magnetic field induced in the object to be heated 3 is small.

  In order to ensure heating with sufficient input power without floating even when the above-described aluminum object to be heated is light, an object having an electric conductor between the heating coil 4 and the plate 2 has been proposed. (For example, refer to Patent Document 2).

Further, since the electric conductor itself is slightly heated by induction heating, some electric conductor temperature detecting means for detecting the temperature of the electric conductor is provided (for example, see Patent Document 3).
JP 2002-75620 A JP 2004-79287 A JP 2004-171929 A

  However, in the conventional configuration, if the air volume changes depending on the rotation speed of the cooling fan, the cooling performance of the electric conductor temperature detecting means also changes, and it becomes difficult for the electric conductor temperature detecting means to accurately detect the temperature of the electric conductor. . When the temperature of the electric conductor temperature detecting means for detecting the temperature of the electric conductor exceeds a predetermined temperature, the output of the drive circuit that supplies the high-frequency current to the heating coil is reduced, so the predetermined temperature must be set low. I had a problem that I had to do.

  The present invention solves the above-described conventional problems, and can provide an induction heating cooker that can transmit the temperature of the electric conductor to the electric conductor temperature detecting means with high accuracy, can increase the set temperature for lowering the output, and is easy to use. The purpose is to provide.

  In order to solve the above-described conventional problems, an induction heating cooker according to the present invention has a main body, a top plate provided on the upper part of the main body, and a lower electric conductivity such as aluminum provided on the lower side of the top plate. A heating coil capable of inductively heating an object to be heated made of a low magnetic permeability material, a heating coil support member for holding the heating coil, and a magnetic field generated by the heating coil provided between the heating coil and the top plate An electric conductor having a function of reducing buoyancy given to the object to be heated, a heat insulating material provided between the electric conductor and the heating coil, and an electric conductor temperature detecting means for detecting the temperature of the electric conductor. A windproof structure is provided in the vicinity of the electric conductor temperature detecting means.

  Thus, the temperature of the electric conductor can be accurately transmitted to the electric conductor temperature detecting means, the set temperature for lowering the output can be increased, and an easy-to-use cooker can be provided.

  The induction heating cooker of the present invention can accurately transmit the temperature of the electric conductor to the electric conductor temperature detecting means, and can increase the set temperature for reducing the output.

  1st invention is the heating which can carry out induction heating of the to-be-heated object which consists of a low magnetic permeability material which has a main body, the top plate provided in the upper part of the main body, and was provided under the top plate and has high electrical conductivity, such as aluminum. A coil, a heating coil support member that holds the heating coil, an electric conductor that is provided between the heating coil and the top plate, and has a function of reducing buoyancy imparted to an object to be heated by a magnetic field generated by the heating coil; By providing a heat insulating material provided between the conductor and the heating coil and an electric conductor temperature detecting means for detecting the temperature of the electric conductor and providing a windproof structure in the vicinity of the electric conductor temperature detecting means, Since it can be made difficult to be affected by wind due to a change in rotational speed, the temperature of the electric conductor can be accurately transmitted to the electric conductor temperature detecting means. For this reason, when the temperature of the electrical conductor exceeds a predetermined temperature, the output of the drive circuit that supplies the high-frequency current to the heating coil is reduced. Therefore, the set temperature can be increased, and the output reduction is minimized. It can be suppressed, making it an easy-to-use cooker.

  Also, since the insulation distance between the electric conductor temperature detecting means and the heating coil is secured by adopting the windproof structure, the electric conductor temperature detecting means can be brought closer to the center side of the heating coil, and the electric conductor temperature detecting means The sensitivity performance can be improved, or the heating coil unit can be downsized.

  In the second invention, in particular, the windproof structure of the first invention is configured to be provided with windproof ribs from the heating coil support member, so that it is less likely to be affected by wind due to a change in the rotational speed of the cooling fan. Therefore, the temperature of the electric conductor can be accurately transmitted to the electric conductor temperature detecting means at low cost. Also, since the insulation distance between the electric conductor temperature detecting means and the heating coil is secured by adopting the windproof structure, the electric conductor temperature detecting means can be brought closer to the center side of the heating coil, and the electric conductor temperature detecting means The sensitivity performance can be improved, or the heating coil unit can be downsized.

  The third invention is particularly the first or second invention, in which a windproof member is provided around the electric conductor temperature detecting means, so that the influence of wind due to a change in the rotational speed of the cooling fan or the like. Since the temperature of the electric conductor can be transmitted to the electric conductor temperature detecting means with high accuracy. Also, since the insulation distance between the electric conductor temperature detecting means and the heating coil is secured by adopting the windproof structure, the electric conductor temperature detecting means can be brought closer to the center side of the heating coil, and the electric conductor temperature detecting means The sensitivity performance can be improved, or the heating coil unit can be downsized.

  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 shows a cross-sectional view of an induction heating cooker according to the first embodiment of the present invention.

  In FIG. 1, a main body 11 that forms an outline of an induction heating cooker, a top plate 12 made of an insulator such as a ceramic material or crystal glass having a thickness of 4 mm provided on the top of the main body 11, and the top plate 12 It is comprised from the to-be-heated object 13, such as a pan | bowl mounted in the top, the heating coil 14 provided in the lower part of the top plate 12, and the heating coil support member 15 which supports the heating coil 14. As shown in FIG.

  The heating coil 14 is supplied with a high-frequency current from a drive circuit 16 having an inverter to generate a high-frequency magnetic field, and applies a high-frequency magnetic field to the object to be heated 13 to perform induction heating. The object to be heated is a material having high electrical conductivity and low magnetic permeability, such as aluminum, aluminum alloy, copper, and copper alloy. The electric conductor 17 is disposed on the lower surface of the top plate 12 so as to face the heating coil 14. Further, the electric conductor 17 is made of a material having a high electric conductivity and a low magnetic permeability such as aluminum, an aluminum alloy, copper, a copper alloy, or carbon, like the object to be heated 13. In this embodiment, aluminum having a thickness of 1 mm is used. The electric conductor 17 is interposed between the heating coil 14 and a heat insulating material 18. A thermistor as an electric conductor temperature detecting means 19 is attached to the lower surface of the heat insulating material 18. Winding ribs 15 a are provided on the heating coil support member 15 at the periphery of the electric conductor temperature detection means 19.

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

  When the object to be heated 13 is placed on the top plate 12 and the power is turned on, the object to be heated 13 is induction-heated by the magnetic flux from the heating coil 14. At this time, the magnetic flux from the heating coil 14 is linked to the electric conductor 17, and an induced current is also generated in the electric conductor 17.

  The induced current induced in the object to be heated 13 is linked to the object to be heated 13 by the magnetic field distribution generated by superimposing the magnetic field distribution generated by the heating coil 14 and the magnetic field distribution generated by the current induced in the electric conductor 17. It is what happens. Thus, since the current distribution generated by the electric conductor 17 is added, the equivalent direct current resistance of the heating coil 14 is increased.

  When the equivalent DC resistance is increased, the amount of heat generated in the object to be heated 13 is increased even with the same heating coil current. Therefore, the heating coil current can be reduced when the same power consumption is to be obtained, and the buoyancy is reduced accordingly. can do.

  With this configuration, in the present embodiment, it is possible to reduce the influence of wind due to a change in the rotation speed of the cooling fan. I can tell you well.

  For this reason, when the temperature of the electrical conductor exceeds a predetermined temperature, the output of the drive circuit that supplies the high-frequency current to the heating coil is reduced. Therefore, the set temperature can be increased, and the output reduction is minimized. It can be suppressed, making it an easy-to-use cooker.

  Also, since the insulation distance between the electric conductor temperature detecting means and the heating coil is secured by adopting the windproof structure, the electric conductor temperature detecting means can be brought closer to the center side of the heating coil, and the electric conductor temperature detecting means The sensitivity performance can be improved, or the heating coil unit can be downsized.

  Further, the windproof structure may be the entire circumference of the electric conductor temperature detecting means or a part where the wind directly hits.

  Moreover, you may comprise a windproof rib with another members with heat insulating materials, such as glass wool.

  As described above, the induction heating cooker according to the present invention can be applied to all uses for induction heating of an object to be heated made of a material having a high electrical conductivity and a low magnetic permeability such as aluminum, thereby improving usability.

Sectional drawing of the induction heating cooking appliance in the 1st Embodiment of this invention Cross-sectional view of a conventional induction heating cooker (A) The figure which shows the electric current which flows into the heating coil of the conventional induction heating cooking appliance (b) The figure which shows the electric current which flows into the to-be-heated object of the conventional induction heating cooking appliance

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Main body 12 Top plate 13 To-be-heated object 14 Heating coil 15 Heating coil support member 15a Windproof rib 17 Electric conductor 18 Heat insulating material 19 Electric conductor temperature detection means

Claims (3)

A main body, a top plate provided on the upper portion of the main body, a heating coil provided below the top plate and capable of induction-heating an object to be heated made of a low magnetic permeability material having high electrical conductivity such as aluminum, A heating coil support member that holds the heating coil, an electric conductor that is provided between the heating coil and the top plate, and has a function of reducing buoyancy imparted to the object to be heated by the magnetic field generated by the heating coil; An induction provided with a heat insulating material provided between the electric conductor and the heating coil, an electric conductor temperature detecting means for detecting the temperature of the electric conductor, and a windproof structure provided in the vicinity of the electric conductor temperature detecting means Cooking cooker. The induction heating cooker according to claim 1, wherein the windproof structure is constituted by windproof ribs from a heating coil support member. The induction heating cooker according to claim 1 or 2, wherein a windproof member is provided on a peripheral portion of the electric conductor temperature detecting means.

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