JP2701645B2 - Electric rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rice cooker for inducing heating of a pot by generating an alternating magnetic field in an induction coil.

[0002]

2. Description of the Related Art An electric rice cooker having a structure disclosed in Japanese Utility Model Application Laid-Open No. 53-164964 is known as a conventional electric rice cooker of an induction heating system. That is, as shown in FIG. 6, a bottom plate 103 having support legs 102 is fixed to the lower surface of the outer case 101 whose upper and lower surfaces are open by screws.
Reference numeral 104 denotes a pot storage portion formed of, for example, plastic having heat resistance, and a flange portion 104 a at an upper end portion of the pot storage portion 104 is fixed to the upper surface of the outer case 101 by screwing. 105 is a side portion 104 of the pan storage portion 104
b is an induction coil buried in the pan storage unit 106
4 is an induction coil buried in the bottom surface portion 104c. 1
Reference numeral 07 denotes a pan made of a magnetic material, for example, an iron, and the pan 107 is detachably mounted on the bottom surface 104 c 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 portion 104c of the pan storage portion 104. The thermosensitive portion 108a of the thermostat 108 is a spring (not shown). And the bottom portion 107b of the pot 107
It comes to adhere to. Reference numeral 110 denotes a temperature detection switch having a heat-sensitive portion 110a made of, for example, a thermistor for detecting the temperature of the side surface portion 107a of the pot 107. The heat-sensitive portion 110a has a base end at the side surface portion 104 of the pan storage portion 104.
b, is always urged in the direction of the pot 107 by a spring 112, so that the tip of the heat-sensitive portion 110 a is pressed against the side surface 107 a of the pot 107. Has become. Reference numeral 113 denotes a lid having a knob 114, which is a flange 1 of the pan storage unit 104.
It is removably mounted on 04a . 115 is the bottom plate 103
A part of an electric circuit is arranged on the control board 115.

A part of the electric circuit provided on the control board 115 includes a rectifier for converting alternating current of commercial current into direct current in order to supply high frequency current to the induction coils 105 and 106, and further converts the converted direct current into high frequency. It is equipped with a transistor for converting to AC. Then, the power supply to the induction coils 105 and 106 is controlled in accordance with the temperature of the heat-sensitive portion 110a for detecting the temperature of the side portion 107a of the pan 107, and the pan 107 is induction-heated. Part 1
The thermostat 108 in close contact with 07b operates to cut off the power supply to the electric circuit and finish the rice cooking.

[0004]

However, in the above-described conventional configuration, the heat from the pot 107, which is induction-heated by the induction coils 105 and 106, is transferred to the induction coil 1 via the pot storage portion 104.
05, 106, the induction coils 105, 106 cannot be cooled effectively. Moreover, since the pan 107 is a single-layer pan made of iron, even if the outer peripheral surface side of the pan 107 is induction-heated by an alternating magnetic field from the induction coils 105 and 106, the heat generated on the outer peripheral surface side is transferred to the inner periphery of the pan. There is a problem that heat cannot be efficiently transmitted to the surface side (the side of the object to be cooked), and the heat generated on the outer peripheral surface side of the pan 107 is transmitted to the pan storage section 104, thereby heating the induction coils 105 and 106. I was

The present invention has been made in view of the above problems, and provides an electric rice cooker capable of efficiently cooling an induction coil.
The purpose is to ensure rice cooking performance without waste .

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a pot for accommodating an object to be cooked and adapted for induction heating, and a detachable housing of the pot and at least a lower portion made of a non-metallic material. And the center of the bottom of the pot and
And the outer periphery of the protective frame.
To the induction coil provided along the
An electric circuit for controlling the supply of high-frequency power, an air layer is formed between the outer periphery of the pot and the inner periphery of the protective frame, at least a lower portion of the outside of the pot is a stainless steel layer, and It is formed of an aluminum layer.

[0007]

According to the above construction, the heat from the pan, which is induction-heated by the induction coil, is blocked by the air layer provided between the outer periphery of the pan and the inner periphery of the protective frame. The heat from the pan does not directly heat the air layer, and the temperature rise of the air layer around the induction coil can be suppressed low. In addition, at least the lower part of the outside of the pot is a stainless steel layer,
Since the inner side is formed with an aluminum layer, the outer stainless steel layer is induction-heated, and the heat generated by this stainless steel layer is efficiently transmitted to the high thermal conductivity aluminum layer side (to-be-cooked side) and the outer periphery of the stainless steel layer Since the heat radiation to the air layer on the side is suppressed and the heat from the pot is not transmitted to the air layer outside the protective frame, the temperature rise of the air layer around the induction coil arranged outside the protective frame Can be further reduced. In addition, the induction coil
Because it is located near the center of the surface and facing the corners
When cooking rice, the pot is effective from the outer circumference to the inner circumference.
Can generate convection of fruity rice and water and cook
Can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a bottomed cylindrical body having an open upper surface. Inside the body 1, a protective frame 3 serving as a pan storage portion is provided via a heat insulating material 2, and the protective frame 3 is provided. Reference numeral 3 denotes a bottomed cylindrical shape made of a non-metallic material such as heat-resistant resin such as PPS, and the upper end of the protective frame 3 is fitted around the upper end of the main body 1.

Numeral 4 designates a pot having an outwardly projecting flange 5 formed at the upper end opening. As shown in FIG. 2, the pot has an aluminum layer 4a having a thickness of 1.5 mm and having a high thermal conductivity;
0.3 mm thick located on the outer surface of this aluminum layer 4a
And a clad ferrite stainless steel layer 4b, and a fluorine coating layer 4c on the inner surface of the aluminum layer 4a. In addition, the pan 4 is mounted by suspending the flange 5 on the upper surface of the protective frame 3.
The protective frame 3 is detachably provided in the protective frame 3. And hot pot 4
Since the height H and the outer diameter D are set smaller than the protection frame 3, an air layer 6 is formed between the outer circumference of the pot 4 and the inner circumference of the protection frame 3. The air layer 6 acts as the heat from the pot 4 induced heating is a thermal barrier from being transferred to the air layer 51 outside the protective frame 3, the protective frame 3 of the outer air layer 51
Is heated to keep the temperature from rising. Outside this
The induction coil 7 arranged outside the protective frame 3 so as to be exposed to the air layer 51 has a denser innermost and outermost winding. Further, the induction coil 7 is supported by a coil cover 8 formed of a heat-resistant resin material on a lower portion of the outer periphery of the protective frame 3 so that a distance to an outer peripheral surface of the pan 4 is constant.
The induction coil 7 is mounted on the air layer 51 outside the protection frame 3 in an exposed state, that is, in a state where air permeability is improved, so that the cooling performance of the induction coil 7 is improved. A ferrite rod 9 made of iron oxide as a main raw material and sintered with a material having a high magnetic permeability is located below the induction coil 7. The ferrite rod 9 is adhered to the lower surface of the coil cover 8. 7
The generated magnetic flux is prevented from leaking downward.

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 Guide tube 11 and thermo case 10
Are always urged upward by a compression coil spring 12 disposed between the two. Reference numeral 13 denotes a contact made of a metal material of aluminum having a high thermal conductivity. The contact 13 is fitted on the upper part of the thermo case 10 via a temperature detecting element 14 composed of a negative temperature coefficient thermistor and a heat sensitive case 15. Is pressed against the outer bottom surface of the pan 4. Reference numeral 16 denotes a circuit board through which a current for generating an alternating magnetic field in the induction coil 7 flows.
Is mounted in a space below the protection frame 3, and more specifically, is mounted in an air layer 51 outside the protection frame 3 in an exposed state.

Reference numeral 17 denotes an outer cover made of a synthetic resin.
Is rotatably supported via a pin 19 on a hinge member 18 integrally formed on the upper portion of the protection frame 3, and a carrying handle 20 is screwed on the upper surface. Reference numeral 21 denotes an inner cover, and the inner cover 21 is
7 is fixed to the inner surface. An engagement member 23 is located on the opposite side of the hinge member 18 and is integrally formed on the upper end of the protection frame 3. An engagement lever 24 connects the pin 25 to the outer lid 17 so as to face the engagement member 23. It is supported rotatably through the. When the outer cover 17 is closed, the engaging portion 23a provided at the distal end of the engaging member 23
Is engaged with the engaging portion 24a. The engaging lever 24 is urged by a spring 26 in a direction in which the engaging portion 24a always engages with the engaging portion 23a of the engaging 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 always urged downward by a packing 29. When the outer lid 17 is closed, the pan 4 is pressed against the flange 5 of the pan 4 to hermetically close the pan 4.

FIG. 4 is an electric circuit diagram of an electric rice cooker according to an embodiment of the present invention. In the figure, reference numeral 33 denotes 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 π-type smoothing circuits,
7, a positive terminal 40 and a negative terminal 41 of DC output terminals
Are connected. 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. Reference numeral 44 denotes a temperature detection circuit for converting a change in the temperature detection element 14 into an electric signal. Reference numeral 45 denotes a power control circuit for controlling the drive circuit 43 based on a signal from the temperature detection circuit 44.
Reference numeral 6 denotes an NPN transistor controlled by the control of the drive circuit 43. The transistor 46 has a collector 4
7 is connected to one end of the induction coil 7 and the capacitor 48 , the emitter 49b 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 7 and the capacitor 48 are
It is connected to a choke coil 39. Reference numeral 50 denotes a diode for releasing the back electromotive force applied to the transistor 46.

Next, the operation of the embodiment constructed as described above 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. After the outer lid 17 is closed, the operation is started by operating means (not shown). By starting this operation, the oscillation circuit 42 and the driving circuit 4
3. The temperature detection circuit 44 and the power control circuit 45 switch the operation terminal and the output terminal 43a of the drive circuit 43 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, and as a result,
A current flows through the induction coil 7 from the choke coil 39 side to the transistor 46 side, and a capacitor 48
Is charged. When the output terminal 43 a of the drive circuit 43 is at a low potential, the transistor 46 is turned off, so that the electric charge charged in the capacitor 48 is discharged via the induction coil 7. Thus, the induction coil 7
The current controlled by the oscillating frequency of the oscillation circuit 43 flows through the coil 4 to generate an alternating magnetic field. As a result, an eddy current flows through the pan 4, and the Joule heat caused by the eddy current causes
The pot 4 is induction-heated, and the object is cooked. In this case, cooking is performed based on the temperature of the temperature detecting element 14 in accordance with the cooking pattern that has been input to the power control circuit 45 in advance.

The pot 4 is induction-heated by the induction coil 7 and heat is radiated to the outside from the pot 4. However, the pot 4 is insulated by the air layer formed between the outer periphery of the pot 4 and the inner periphery of the protective frame 3.
Transmission of heat from the pan 4 to the induction coil 7 disposed outside the protection frame 3 is suppressed to a low level. Therefore, the temperature rise of the air layer 51 outside the protection frame 3 due to the influence of heat from the pan 4 can be minimized, and the induction coil 7 mounted in a state exposed to the outside air layer 51 can be suppressed. Cooling efficiency can be increased. In addition, the circuit board 16 on which heat-generating components such as the transistor 46 are arranged is placed in the air layer 51 outside the protection frame 3. However, since the outside air layer 51 has a low thermal effect from the pan 4, The components on the circuit board 16 can also be efficiently cooled. Further, since the heat from the pan 4 is shielded by the air layer 6, it is not necessary to newly wind a heat insulating material as a separate member around the entire outer periphery of the pan 4, so that the heat shielding effect can be obtained with a simple configuration. Can be Furthermore, at least the lower part of the outside of the pan 4
Was a stainless steel layer 4b, since the inner aluminum layer 4a, the heat generated in the stainless steel layer 4b side is transmitted efficiently to the aluminum layer 4a side of the high thermal conductivity, pot 4
In addition to efficiently heating the food inside, the heat transmitted to the air layer 6 on the outer peripheral side of the stainless steel layer 4b is suppressed low, the heat shielding effect of the air layer 6 is further enhanced, and
The cooling effect of the arranged induction coil 7 is further enhanced.

Next, FIG. 5 shows another embodiment of the pot used in the electric rice cooker of the present invention. In the drawing, reference numeral 4a denotes an aluminum layer having a thickness of 1.5 mm and having a high thermal conductivity. The inner surface of this aluminum layer 4a is coated with a fluoric coating layer 4c, and the outer surface of the aluminum layer 4a is coated with SUS30.
4, an austenitic stainless steel layer 4d having a thickness of 0.15 mm, a ferrite stainless steel layer 4e having a thickness of 0.3 mm, and an austenitic stainless steel layer 4f having a thickness of 0.15 mm are sequentially laminated and clad. . In this material configuration, compared with the pot structure of the aluminum layer and the stainless steel layer shown in FIG.
4f, the material has good elongation, and as a result,
Deep drawing becomes easier. In addition, the outer surface of the pot 4 is resistant to corrosion because of the presence of the austenitic stainless steel layer 4f.

[0017]

As is clear from the above description of the embodiments,
According to the present invention, since the air layer is formed between the outer periphery of the pot and the inner periphery of the protective frame, heat from the induction-heated pot is shielded by the heat insulating effect of the air layer, and Heat protection
The rise in air layer temperature outside the guard frame can be kept low.
You.

Further, since at least the lower portion of the outside of the pot is made of a stainless steel layer and the inside of the pot is made of an aluminum layer, heat generated in the stainless steel layer can be efficiently transmitted to the aluminum layer having a high thermal conductivity. The object can be efficiently heated, and the heat radiation to the air layer on the outer side of the stainless steel layer is also kept low, and the temperature rise around the induction coil placed outside the protection frame is further reduced with the heat shielding effect of the air layer. be able to. Also, induction coil
Was placed near the center and the corner of the bottom of the pot
By this, when cooking rice, from the outer periphery of the pot to the inner periphery
To generate effective convection of rice and water.
And the occurrence of uneven cooking can be prevented.

[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 an enlarged sectional view of a part A in FIG.

FIG. 3 is a perspective view of an induction coil in the electric rice cooker.

FIG. 4 is an electric circuit diagram of the electric rice cooker.

FIG. 5 is a sectional view showing another embodiment of the pot structure in the electric rice cooker.

FIG. 6 is a sectional view of an electric rice cooker showing a conventional example.

[Explanation of symbols]

 Reference Signs List 3 Protective frame 4 Pot 4a Aluminum layer 4b Stainless layer 6 Air layer 7 Induction coil 51 Outside air layer

Continuation of front page (56) References JP-A-51-60036 (JP, A) JP-A-62-109523 (JP, A) JP-A-62-136790 (JP, A) JP-A-62-270118 (JP) , A) Japanese Utility Model Showa Sho 53-164964 (JP, U) Japanese Utility Model Showa Sho 59-144795 (JP, U)

Claims (1)

(57) [Claims] 1. A and pot corresponding to the induction heating accommodating the foods, and a protective frame at least lower detachably accommodating the pot is constituted by a non-metallic material, near the center and co of the pot bottom
And the outer periphery of the protective frame.
To the induction coil provided along the
An electric circuit for controlling the supply of high-frequency power, an air layer is formed between the outer periphery of the pot and the inner periphery of the protective frame, at least a lower portion of the outside of the pot is a stainless steel layer, and Electric rice cooker made of aluminum layer.