JPH0789980B2 - Electric rice cooker - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rice cooker used in general households, and more particularly to an electric rice cooker having improved heating characteristics by an electric heater.

2. Description of the Related Art A conventional electric rice cooker uses an electric heater that uses resistance heating, and for example, a pot is detachably placed on an upper portion of a hot plate having an electric heater, and heat of the heater is removed from the hot plate. And a system for cooking rice by transmitting to the bottom of the pot, and a space for heating around the outer periphery of the pot, and a seed heater insulated with magnesia powder at a predetermined interval from the pot in this space,
There has been a system in which the pan is heated through the space by the sheath heater.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, when rice is cooked with the above-described conventional electric rice cooker, in the former electric rice cooker equipped with a hot plate type heater, the rice cooks in the vicinity of the heater. There is a problem that unevenness occurs and the taste is deteriorated as a whole. In addition, strict dimensional accuracy is required so that the hot plate and the pan come into close contact with each other, and if the contact surfaces of both are deformed or corroded during use, heat transfer becomes uneven and uneven cooking is more likely to occur. It had the problem of increasing the number.

In addition, in the latter method of heating the pot via the space, as the sheath heater, an annular sheath heater slightly smaller than the outer diameter of the pot is often used, but in this case,
There was a problem that the outer peripheral portion close to the sheathed heater was messy and the inner peripheral portion far from the sheathed heater was unevenly cooked, resulting in poor taste. In order to improve this, when the sheathed heater is formed in a spiral shape, there are many variations in the process due to corrections to obtain flatness of the sheathed heater.

In addition, in both types of rice cooking, there is a problem that uneven cooking is more likely to occur when a large amount of rice is cooked, and burns are likely to occur near the heater during the additional cooking process.

Further, in both types of rice cooking methods, the temperature of the electric heater increases during rice cooking, so that the heat shield structure of the heater becomes large, and thus the applied power to the rice cooking is also limited.

In general rice cooking, at the stage of cooking after the inundation process,
It is said that it is better to cook with strong heat, but with conventional electric heaters, there was little heat and it was not possible to cook well-mixed koban.

Also, in the conventional electric rice cooker, the electric heater is exposed on the inner surface of the protective frame, so it is difficult to clean, and especially when rice etc. enters the protective frame, the rice is carbonized and the electric heater and the protective rice cooker are protected. Sticking to the frame made it more difficult to clean.

The present invention is to solve the above-mentioned conventional problems, with a simple configuration, without requiring strict dimensional accuracy, cook deliciously,
Moreover, the first is to provide an electric rice cooker that is easy to clean.
The purpose of.

A second object is to provide an electric rice cooker in which the additional cooking is improved with one induction coil and the taste is improved.

Further, a third object is to provide an electric rice cooker in which convection is caused from both the center part of the pan and the side part of the pan to improve the unevenness of cooking.

A fourth object is to provide an electric rice cooker in which unevenness of cooking is improved by balancing convection from both the central portion of the pot and the side surface of the pot.

Further, a fifth object is to provide an electric rice cooker with improved uneven cooking in large-capacity rice cooking.

Means for Solving the Problems In order to solve the first problem described above, the present invention relates to a pan for accommodating an object to be cooked, a protective frame for accommodating the pan and at least a lower part of which is made of non-metal, and this protection. The pan is suspended on the upper surface of the protective frame, which is equipped with an induction coil serving as a heating source for the pan disposed on the non-metal outer peripheral portion of the frame, and an electric circuit for applying a current for generating an alternating magnetic field to the induction coil. The pot is placed in a state and the outer surface and the outer bottom surface of the pot are continuously opposed to the protective frame through an air layer.

Further, in order to solve the second problem, the present invention includes an induction coil in which a densely wound inner coil and a densely wound outer coil provided on an outer peripheral portion of the inner coil are configured in series. It is a thing.

In order to solve the above-mentioned third problem, the present invention particularly provides an induction coil in which the distance between the outer circumference of the inner coil and the inner circumference of the outer coil is substantially equal to or greater than the winding width of the inner coil or the winding width of the outer coil. It is equipped with.

In order to solve the fourth problem, the present invention particularly includes an induction coil in which the winding ratios of the inner coil and the outer coil are substantially equal.

Furthermore, in order to solve the above-mentioned fifth problem, the present invention particularly arranges an inner coil and an outer coil constituting an induction coil on the outer bottom portion of the protective frame and the outer surface portion of the protective frame.

Effect According to the above configuration, since induction heating is used, the pot directly generates heat. Rice and water are contained in the pot, and the heat generated by the pot is efficiently converted to rice and water. Since it is transmitted, the temperature of the heated part does not exceed 100 ℃. As a result, since the heat shield structure portion is significantly reduced, it is possible to cook rice by increasing the rice cooking power. In addition, by raising the rice cooking power, it is possible to cook rice with sufficient heat at the time of cooking, so it is possible to quickly cook delicious rice with a strain. Moreover, since it is not necessary to closely attach the induction coil and the pan, stable rice can be cooked without requiring strict dimensional accuracy.

Also, since the induction coil is not exposed on the inner surface of the protective frame,
The inner surface of the protective frame is neat and easy to clean. Furthermore, since the outer surface and outer bottom surface of the pan are continuously opposed to the protective frame via the air layer, the weight of the pan does not directly affect the protective frame, and as a result, the protective frame can be made thinner, Even if the food is sandwiched between the pan and the protective frame, the position of the pan does not change due to the presence of the air layer, stable cooking is possible, and this air layer also serves as a heat insulating layer, so the heat is kept well. And the thermal efficiency is improved.

Also, in order to raise the temperature of the cooked food uniformly, it is necessary to create a stagnation-free convection in the whole pan and heat the whole uniformly, but it is effective to divide the induction coil into two parts. It is possible to balance the convection of the water in the pan facing each coil by making the winding ratio of the inner coil and the outer coil approximately equal, and further reduce the uneven cooking. it can.

In addition, by disposing the inner coil on the outer bottom of the protective frame and the outer coil on the outer side of the protective frame, water that rises in temperature especially from the side of the bottom of the pot is transmitted along the side of the pot, so that convection is further promoted and large capacity Even when cooking rice, it is possible to suppress uneven cooking.

Example Hereinafter, one example of the present invention will be described with reference to the accompanying drawings. In FIG. 1 and FIG. 2, reference numeral 1 denotes a bottomed cylindrical main body having an open top surface, and a protective frame 3 is disposed inside the main body 1 via a heat insulating material 2 as a pot storage portion, and the protection is performed. The frame 3 is formed of a heat-resistant resin material such as PPS into a bottomed cylindrical shape, and the upper end of the protective frame 3 is fitted around the inside of the upper end of the main body 1.

Reference numeral 4 denotes a pot having an outwardly projecting flange 5 formed at the upper end opening. The pot 4 is detachably arranged in the protective frame 3 by placing the flange 5 on the upper surface of the protective frame 3 in a suspended state. It is set up. Since the height H and the outer diameter D of the pan 4 are set smaller than the protective frame 3, the pan 4 is protected by the protective frame 3
In the state where it is installed in the
A closed air layer 6 is formed. Since the air layer 6 continuously faces the outer bottom surface and the outer surface of the pan 4, it is possible to prevent the weight of the pan 4 from being directly applied to the bottom portion of the protective frame 3 and to improve the heat retaining property. it can.
Reference numeral 7 denotes an inner coil 7A tightly wound with an induction coil wound with a litz wire, and an outer coil 7B located close to and tightly wound on the outer circumference of the inner coil 7A connected in series. The distance between the outer coil 7B and the inner circumference of the outer coil 7B is made wider than the winding width of the inner coil 7A or the outer coil 7B. In addition, the winding ratios of the inner coil A and the outer coil 7B are made approximately the same, and
The inner coil 7A is disposed on the outer bottom portion of the protective frame 3, and the outer coil 7B is disposed on the outer bottom side surface portion of the protective frame 3.

In addition, the induction coil 7 and the pan 4 are supported by a coil cover 8 formed of a heat-resistant resin material on the lower outer periphery of the protective frame 3 so that the outer peripheral surface of the pan 4 has a constant distance to improve ventilation of the induction coil 7. The cooling of the induction coil 7 is facilitated.
Reference numeral 9 is a ferrite rod obtained by sintering iron oxide as a main raw material and having a high magnetic permeability. The ferrite rod 9 is adhered to the outer surface of the coil cover 8 to prevent leakage magnetic flux generated by the induction coil 7. is doing.

10 is a thermo case formed of heat-resistant resin. The thermo case 10 is supported by a guide tube 11 integrally formed on the outer bottom portion of the protective frame 3 so as to be vertically movable by a pin (not shown),
Further, the compression coil spring 12 arranged between the guide cylinder 11 and the thermo case 10 is constantly biased upward. Reference numeral 13 denotes a contact made of an aluminum metal material having high thermal conductivity. The contact 13 is attached to the upper part of the thermo case 10 via a temperature detecting element 14 composed of a negative characteristic thermistor and a heat sensitive case 15, and the contact 13 The upper surface of is pressed against the outer bottom surface of the pan 4. Reference numeral 16 is a circuit board for applying AC power to the induction coil 7. The circuit board 16 is provided with a part of an electric circuit described later.

Reference numeral 17 denotes an outer lid made of synthetic resin. The outer lid 17 is rotatably supported by a hinge member 18 integrally formed on the upper portion of the protective frame 3 via a pin 19, and is a handle portion for carrying on the upper surface. 20 is screwed. Reference numeral 21 denotes an inner cover, and the inner cover 21 is fixed to the inner surface of the outer lid 17 via a heat insulating material 22. Reference numeral 23 denotes an engaging member which is located on the opposite side of the hinge member 18 and is integrally formed on the upper end of the protective frame 3, and the engaging lever 24 attaches the pin 25 to the outer lid 17 so as to face the engaging member 23. It is rotatably supported via. Further, the engaging portion 23a provided at the tip of the engaging member 23 has an engaging lever 24a when the outer lid 17 is closed.
It engages with the engaging portion 24a. Further, the engaging lever 24 is urged by a spring 26 to rotate so that the engaging portion 24a is always engaged with the engaging portion 23a of the engaging member 23. 27 is an inner lid, and the inner lid 27 is supported by a support pin 28 provided on the lower surface of the inner cover 21 so as to project downward, and is constantly urged downward by a packing 29. When the outer lid 17 is closed, it is pressed against the flange 5 of the pan 4 to close the pan 4.

FIG. 3 is an electric circuit diagram of an electric rice cooker showing an embodiment of the present invention. In FIG. 3, reference numeral 33 is a full-wave rectifier circuit composed of four diodes, and AC input terminals 34 and 35 of the full-wave rectifier circuit 33 are connected to an AC power supply 36. The smoothing capacitors 37 and 38 and the choke coil 39 are a π-type smoothing circuit, and the positive terminal 40 and the negative terminal 41 of the DC output terminal are connected to both ends of the smoothing capacitor 37. An oscillating circuit 42 oscillates at a predetermined frequency, and the oscillating circuit 42 controls the drive circuit 43. 44 is a temperature detection circuit that changes the change of the temperature detection element 14 into an electric signal, 45 is a power control circuit for controlling the drive circuit 43 by the signal from the temperature detection circuit 44, and 46 is controlled by the drive circuit 43. This transistor 46 is an NPN type transistor in which the collector 47 is connected to the induction coil 7 and one end of the capacitor 47, and the emitter 49a is connected to the negative terminal 41 of the DC output terminal, and the base 49 is connected to the drive circuit 43. It is connected. The other ends of the induction coil 7 and the capacitor 48 are connected to the choke coil 39. 50 is a diode for releasing the counter electromotive force applied to the transistor 46.

Next, the operation of this embodiment configured as described above will be described. The food to be cooked is stored in the pan 4 and placed on the upper surface of the protective frame 3 in a suspended state. Then, after closing the outer lid 23, the operation is started by operating means (not shown). By starting this operation, the oscillation circuit 42, the drive circuit 43, the temperature detection circuit 44
And the power control circuit is activated, and the output terminal 43 of the drive circuit 43
A is switched between a high potential and a low potential according to the frequency of the oscillation circuit 42. That is, when the output terminal 43a of the drive circuit 43 is at a high potential, the transistor 46 is turned on. As a result, a current flows through the induction coil 7 from the choke coil 39 side to the transistor 46 side, and the capacitor 48
Will be charged. Further, when the output terminal 43a of the drive circuit 43 has a low potential, the transistor 46 is turned off, so that the electric charge charged in the capacitor 48 is discharged through the induction coil 7. In this way, an electric current controlled by the oscillation frequency of the oscillation circuit 42 flows in the induction coil 7 to generate an alternating magnetic field, which causes an eddy current to flow in the pan 7 and Joule heat generated by the eddy current. Then, the pan 7 is induction-heated to cook the food. In this case, the cooking is performed according to the cooking pattern previously input to the power control circuit 45 according to the temperature of the temperature detecting element 14.

EFFECTS OF THE INVENTION As described above, according to the present invention, at least the lower portion of the protective frame that detachably accommodates the pot is made of a non-metallic material, and the outer periphery of the non-metallic portion of the protective frame serves as a heating source for the pot. Since an induction coil is provided and an electric circuit for applying a current for generating an alternating magnetic field to the induction coil is provided, the pan can be induction-heated by generating an alternating magnetic field in the induction coil, As a result, the rice can be cooked with sufficient heat power, so that delicious rice with a strain can be cooked quickly.

Also, since the induction coil is not exposed on the inner surface of the protective frame,
The inner surface of the protective frame is neat and easy to clean. Furthermore, since the outer surface and outer bottom surface of the pan are continuously opposed to the protective frame via the air layer, the weight of the pan does not directly affect the protective frame, and as a result, the protective frame is thin and organic resin is used. It is possible to use materials with low heat resistance such as etc., and it is possible to reduce the size and weight, and even if the food is sandwiched between the pan and the protective frame, the position of the pan does not change due to the presence of the air layer. , Stable cooking becomes possible, and since this air layer also serves as a heat insulating layer, the heat retention is improved.

In addition, the induction coil is composed of a tightly wound inner coil and an outer coil which is located on the outer periphery of the tightly wound outer coil and is tightly wound, and the inner coil and the outer coil are connected in series to reheat the induction coil. In the process, it is possible to add a strong additional cook without burning a part of the rice, and the taste of the rice can be improved.

Further, by setting the distance between the outer circumference of the inner coil and the inner circumference of the outer coil to be substantially equal to or greater than the winding width of the inner coil or the winding width of the outer coil, it is possible to reduce uneven cooking.

Further, by making the winding ratios of the inner coil and the outer coil substantially equal, the convection of water in the pot facing the inner coil and the outer coil is balanced, and thus the uneven cooking is further reduced.

Further, by arranging the inner coil on the outer bottom portion of the protective frame and the outer coil on the outer surface portion of the protective frame, uneven cooking can be reduced even with a large amount of rice.

As is clear from the above description, ideal cooking and heating of rice can be realized by the coil configuration, and the rice cooking performance can be greatly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an electric rice cooker showing an embodiment of the present invention,
FIG. 2 is a perspective view of an induction coil in the electric rice cooker, and FIG. 3 is an electric circuit diagram of the electric rice cooker. 3 ... Protective frame, 4 ... Pan, 6 ... Air layer, 7 ... Induction coil, 16 ... Circuit board, 7A ... Inner coil, 7B ... Outer coil.

Continuation of the front page (56) Bibliography Shou 53-164964 (JP, U) Seki 52-67662 (JP, U) Seki 51-72244 (JP, U) Sugi 57-20088 (JP , Y1)

Claims (5)

[Claims] 1. A pot for accommodating an object to be cooked, a protective frame for accommodating the pot, at least a lower portion of which is made of a non-metallic material,
The protection frame is provided with an induction coil serving as a heating source of the pan arranged on the outer periphery of the non-metal part of the protection frame, and an electric circuit for applying a current for generating an alternating magnetic field to the induction coil. An electric rice cooker which is placed in a suspended state on the upper surface of a frame and in which the outer side surface and the outer bottom surface of the pot are continuously opposed to the protective frame via an air layer. 2. The electric rice cooker according to claim 1, further comprising an induction coil configured by connecting a densely wound inner coil and a densely wound outer coil provided in an outer peripheral portion thereof in series. . 3. An induction coil, wherein the distance between the outer circumference of the inner coil and the inner circumference of the outer coil is substantially equal to or greater than the winding width of the inner coil or the winding width of the outer coil. The listed electric rice cooker. 4. The electric rice cooker according to claim 1, comprising an induction coil in which the winding ratios of the inner coil and the outer coil are substantially equal. 5. The electric rice cooker according to any one of claims 1 to 4, wherein an inner coil and an outer coil that form an induction coil are provided on the outer bottom of the protective frame and the outer lateral side of the protective frame, respectively.