JP2705082B2 - Electric rice cooker - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rice cooker used in ordinary 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 using resistance heating, for example, a pan is detachably mounted on a hot plate having an electric heater, and the heat of the electric heater is transferred to the hot plate. And a method of transmitting rice to the bottom of the pot to cook rice, and a sheathing heater in which a space for heating is provided around the outer periphery of the pot and insulated with magnesia powder at a predetermined interval from the pot in this space. There has been a system in which a pan is heated through the space by the sheath heater.

Also, as a conventional example of cooking an object to be cooked in a pan by an induction heating source, Japanese Utility Model Application Laid-Open No. 53-164964 is known.
This will be described with reference to FIG.

In FIG. 4, reference numeral 101 denotes an outer case whose upper and lower surfaces are open. A bottom plate 103 having support legs 102 is fixed to the lower surface of the outer case 101 by screwing. 104 is a pot storage portion formed of, for example, heat-resistant plastic, and a flange portion 104a provided at an upper end portion of the pan storage portion 104.
Is fixed to the upper surface of the outer case 101 by screwing. Reference numeral 105 denotes a first induction coil embedded in the side surface portion 104b of the pan storage portion 104 by integral molding, and reference numeral 106 denotes a second induction coil embedded in the bottom surface portion 104c of the pan storage portion 104 by integral molding. Reference numeral 107 denotes a pan made of a magnetic material, for example, an iron, and the pan 107 is detachably mounted on the bottom surface portion 104c of the pan storage unit 104. Numeral 108 denotes, for example, a magnetic thermostat fixed through a support plate 109 in a through hole 104d provided substantially at the center of the bottom of the pan storage portion 104, and the thermosensitive portion 108a of the thermostat 108 is moved upward by a spring (not shown). And is in close contact with the bottom portion 107b of the pot 107. Reference numeral 110 denotes a temperature detection switch having a heat-sensitive portion 110a formed of, for example, a thermistor for detecting the temperature of the side surface portion 107a of the pan 107. It is inserted into the hole 111 and is constantly urged in the direction of the pot 107 by a spring 112 so that the tip of the heat-sensitive part 110a is pressed against the side face 107a of the pot 107. Reference numeral 113 denotes a lid having a knob 114, which is detachably mounted on the flange 114a of the pan storage unit 104. 115 is a control board fixed to the upper surface of the bottom plate 103,
The control board 115 is provided with a part of an electric circuit.

Problems to be Solved by the Invention However, in the configuration of the above-mentioned conventional electric rice cooker, if the bottom of the pot containing a large amount of rice and water comes into contact with a protective frame made of ceramic or the like, which is vulnerable to impact, the impact at the time of placement causes There was a problem that the protective frame was easily broken.

In addition, since the side peripheral surface of the pot is exposed, the heat of the pot escapes and the heat efficiency is poor, and a part of the pot is intensively heated to be locally heated, so that the rice can be sufficiently and uniformly heated from the entire periphery. And it was difficult to cook rice plumply.

In view of the above problems, the present invention can maintain the required distance between the pan and the induction coil without abutting the bottom of the pan on the protective frame, and wrap the whole pan in the presence of space. It is an object of the present invention to provide a rice cooker that can cook rice plumply by uniformly and efficiently heating the surroundings.

According to the present invention, an induction coil is provided in a bottom portion of a body formed by an outer case and a protection frame, and a pot that generates heat by an alternating magnetic field is housed in the protection frame of the body and faces the induction coil through the protection frame. The pan is supported on the body by placing the upper edge of the pan on the shoulder of the body, and the support forms a space between the side circumference and the bottom of the pot and the protective frame. Then, a temperature detecting element holding a temperature detecting element is provided at the bottom of the container, and this temperature detecting element is exposed from the protective frame into the space, and the inside of the protective frame is in contact with the supported pan. It is characterized in that it is higher than the bottom surface.

Means for Solving the Problems In order to solve the above problems, the present invention provides an induction coil in a bottom portion of a body formed by an outer case and a protection frame, and generates heat by an alternating magnetic field in the protection frame of the body. The pan is stored and opposed to the induction coil via a protective frame, and the upper edge of the pan is placed on the shoulder of the main body to support the pan in the main body. Forming a space between the periphery and the bottom and the protection frame, providing a temperature detector holding a temperature detection element at the bottom of the container, facing this temperature detector from the protection frame into the space, It is characterized in that it is higher than the inner bottom surface of the protection frame in a state of contact with the supported pot.

Operation According to the above configuration, since the induction heating is used, the pot directly generates heat. Rice and water are contained in the pot, and the heat generated in the pot is efficiently transferred to the rice and water. Because it is transmitted, the temperature of the heated part does not greatly exceed 100 ° C. As a result, the heat-insulating structure is significantly reduced, so that it is possible to cook rice with increased rice cooking power. In addition, by increasing the rice cooking power, the rice can be cooked with sufficient heat at the time of cooking, so that it is possible to cook savory and delicious rice quickly. In addition, since it is not necessary to bring the induction coil and the pot into close contact with each other, it is possible to cook stable rice without requiring strict dimensional accuracy.

In addition, since the induction coil is not exposed on the inner surface of the protection frame, the inner surface of the protection frame is clean and easy to clean. Furthermore, since the outer surface and the 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 fall on the protective frame, and as a result, the protective frame can be thinned, Even if the food is caught between the pot and the protective frame, the position of the pot does not change due to the presence of the air layer, and stable cooking is possible. And the thermal efficiency is also improved.

Further, the temperature detector faces the space from the protection frame,
Since the height is higher than the inner bottom surface of the protective frame in a state in which the protective frame is in contact with the pot, it is possible to avoid a detection failure due to the protective frame and the pan forming a space and being largely separated from each other at the bottom. .

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings. In FIGS. 1 and 2, reference numeral 1 denotes a bottomed cylindrical main body having an open upper surface. Inside the main body 1, a protective frame 3 is disposed as a pot storage section via a heat insulating material 2, and The protective frame 3 is formed in a bottomed cylindrical shape from a heat-resistant resin material such as PPS, and the upper end of the protective frame 3 is fitted around the upper end of the main body 1.

Reference numeral 4 denotes a pot having a flange 5 protruding outward at an upper end opening. The pot 4 is formed of a 1.5 mm thick aluminum plate, and has a magnetic material of 0.5 mm thick ferritic stainless steel SUS430 at its outer bottom. The metal material layer 4a is pressed. As a method of pressure bonding, cold pressure bonding, hot rolling pressure bonding, diffusion pressure bonding by hot pressing or the like, pressure bonding by forging, and the like are known. The pan 4 is detachably disposed in the protective frame 3 by mounting the flange 5 on the upper surface of the protective frame 3 in a suspended state. Since the height H and the outer diameter D of the pan 4 are set to be smaller than those of the protective frame 3, when the pan 4 is disposed in the protective frame 3, the outer periphery of the pan 4 is surrounded by the protective frame 3.
Thus, a closed air layer 6 is formed. Since the air layer 6 continuously faces the outer bottom surface and the outer side surface of the pot 4, it is possible to prevent the weight of the pot 4 from being directly applied to the bottom of the protective frame 3, and to enhance heat insulation. it can.
Reference numeral 7 denotes an induction coil using a litz wire.
A coil cover 8 made of a heat-resistant resin material is formed on the lower part of the outer periphery of the protective frame 3 so that the innermost and outermost turns are dense and the outer peripheral surface of the induction coil 7 and the outer periphery of the pan 4 are at a fixed distance. , The ventilation of the induction coil 7 is improved, and the cooling of the induction coil 7 is facilitated. Reference numeral 9 denotes a ferrite rod made of iron oxide as a main material and sintered with 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. I have.

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

Reference numeral 17 denotes an outer cover made of synthetic resin. The outer cover 17 is rotatably supported via a pin 19 on a hinge member 18 integrally formed on the upper portion of the protective frame 3 and has a handle portion for carrying on the upper surface. 20 are screwed. 21 is an inner cover, and this inner cover 21
Is fixed to the inner surface of the outer lid 17 via a heat insulating material 22. twenty three
Is 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. An engaging lever 24 is provided on the outer lid 17 via a pin 25 so as to face the engaging member 23. It is supported rotatably. When the outer cover 17 is closed, the engaging portion 23a provided at the distal end of the engaging member 23 is
It is designed to engage with the fourth engaging portion 24a. The engagement lever 24 is biased by a spring 26 in a direction in which the engagement portion 24a is always engaged with the engagement portion 23a of the engagement member 23. Reference numeral 27 denotes an inner lid, which is vertically movably supported by a support pin 28 provided on the lower surface of the inner cover 21 so as to protrude downward, and is constantly urged downward by a packing 29. When the outer lid 17 is closed, the pan 4 is closed by pressing against the flange 5 of the pan 4.

FIG. 3 is an electric circuit diagram of an electric rice cooker according to an embodiment of the present invention. In FIG. 3, 33 is 4
The input terminals 34 and 35 of the full-wave rectifier circuit 33 are connected to an AC power supply 36. Smoothing capacitors 37 and 38 and choke coil 39
Denotes a π-type smoothing circuit, and a positive terminal 40 and a negative terminal 41 of DC output terminals are connected to both ends of a smoothing capacitor 37. Reference numeral 42 denotes an oscillation circuit that oscillates at a predetermined frequency, and the driving circuit 43 is controlled by the oscillation circuit 42. 44 is a temperature detection circuit that converts a change in the temperature detection element 14 into an electric signal, and 45 is a temperature detection circuit 44
A power control circuit for controlling the drive circuit 43 in response to a signal from the NPN transistor 46; an NPN transistor 46 controlled by the drive circuit 43;
Is connected to one end of an induction coil and a capacitor 48, the emitter 51 is connected to the negative terminal 41 of the DC output terminal, and the base 49 is connected to the drive circuit 43. The other ends of the induction coil and the capacitor 48 are connected to the choke coil 39. 50 is a diode for releasing the back electromotive force applied to the transistor 46.

Next, the operation of the present embodiment thus configured will be described.
The object 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 17, the operation is started by the operation 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 operates, and the output terminal 43 of the drive circuit 43 is activated.
a is switched between a high potential and a low potential in accordance with 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.
Charged to 48. When the output terminal 43a of the driver circuit 43 is at a low potential, the transistor 46 is turned off.
The electric charge charged in the capacitor 48 is discharged via the induction coil 7. In this way, the current controlled by the oscillation frequency of the oscillation circuit 43 flows through the induction coil 7 and an alternating magnetic field is generated. As a result, the pan 7 is induced by Joule heat due to the eddy current. The object is cooked by being heated. In this case, cooking is performed according to the cooking pattern input in advance to the power control circuit 45 based on the temperature of the temperature detecting element 14.

In the above embodiment, the magnetic metal material layer pressed on the outer bottom of the pan 4 to improve the heat generation efficiency of the pan 4
Although 4a is formed of ferritic stainless steel SUS430, the present invention is not limited to this, and any magnetic metal material may be used.

As described above, according to the present invention, the peripheral edge of the upper end of the pan is placed on the shoulder of the body formed by the outer case and the protective frame and is supported in the body, and the induction coil is protected. Since it is not exposed on the inner surface of the frame, the inner surface of the protective frame is clean and easy to clean. In addition, because the outer surface and the outer bottom surface of the pot are continuously opposed to the protective frame via the air layer,
The weight of the pot does not directly fall on the protective frame, and as a result,
The protective frame can be made thinner, and even if the food is sandwiched between the pot and the protective frame, the position of the pan does not change due to the presence of the air layer, enabling stable cooking. Protection is also improved.

Further, the temperature detector faces the space from the protection frame,
Since the height is higher than the inner bottom surface of the protective frame in a state in which the pan is in contact with the supported pan, it is possible to avoid a detection failure caused by the protective frame and the pan forming a space and the bottoms being largely separated from each other. .

[Brief description of the drawings]

FIG. 1 is a sectional view of an electric rice cooker showing one embodiment of the present invention,
FIG. 2 is a perspective view of an induction coil in the electric rice cooker, FIG. 3 is an electric circuit diagram of the electric rice cooker, and FIG. 4 is a cross-sectional view of the conventional electric rice cooker. 3 ... Protection frame, 4 ... Pot, 4a ... Magnetic metal material layer, 6 ...
... air layer, 7 ... induction coil, 16 ... circuit board.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References Real opening 58-138515 (JP, U) Real opening 57-192689 (JP, U) Real opening 61-83293 (JP, U) Real opening 60 24086 (JP, U)

Claims (1)

(57) [Claims] 1. An induction coil is provided in a bottom of a body formed by an outer case and a protection frame, and a pot that generates heat by an alternating magnetic field is housed in the protection frame of the body, and the induction coil is connected to the induction coil through the protection frame. The pan is supported inside the body by placing the peripheral edge of the top of the pot on the shoulder of the body, and the space between the side circumference and the bottom of the pot and the protective frame is provided by this support. Is formed, and a temperature detecting element holding a temperature detecting element is provided at the bottom of the container, and the temperature detecting element faces the space from the protective frame, and the protective frame is in contact with the supported pot. An electric rice cooker characterized by being higher than the inner bottom surface of the rice cooker.