JPH09428A - Induction heating type rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating type rice cooker for which an induction coil is easily and efficiently manufactured and handling for the transportation and storage, etc., of the induction coil and that when a rice cooker is assembled in an inner frame are facilitated. SOLUTION: A nearly flat induction coil 6 for pan induction heating confronting with only the outer bottom of a pan 12 is provided on the bottom of the inner frame 3 in which the pan 12 is housed and an insulating plate 5 provided with electrical insulation arranged by keeping a prescribed gap between the bottom of the pan 12 is provided on the upper side of the induction coil 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating type rice cooker for cooking rice by heating rice and water contained in a pot.

[0002]

2. Description of the Related Art Generally, a rice cooker includes a rice cooker main body and a pot removably housed in the rice cooker main body. Is to cook rice by heating. Usually, a heater is used as the heating means.

On the other hand, in recent years, a rice cooker in which a pot is formed of a magnetic material, or a magnetic material is attached to the pot, and rice and water in the pot are heated by an induction heating method using an induction coil. Has been proposed.

As this type of rice cooker, Japanese Patent Laid-Open No. 1-218 has been proposed.
No. 412 discloses its structure. In this induction heating type rice cooker, an induction coil is provided at a lower portion of an inner frame for accommodating the pot so as to face a portion extending from a bottom portion of the pot to a lower portion of a side surface.

[0005]

However, if the induction coil has a structure facing the part extending from the bottom to the lower portion of the side surface of the pan, the induction coil has a three-dimensional structure having a certain height, and as a result, The manufacturing of the induction coil is troublesome and costly, and the handling of the induction coil after its manufacture, such as transportation and storage, and the handling when incorporating the induction coil into the inner frame of the rice cooker are troublesome.

The present invention has been made by paying attention to such a point, and an object thereof is to easily manufacture an induction coil efficiently and to handle the induction coil such as transportation and storage. Another object of the present invention is to provide an induction heating type rice cooker that can be easily handled when incorporated into the inner frame of the rice cooker.

[0007]

In order to achieve such an object, the present invention is for induction heating of a pan having a substantially flat shape at the bottom of an inner frame for accommodating the pan and facing only the outer bottom surface of the pan. The above induction coil is provided, and a protective member having an electrical insulation property is provided above the induction coil with a predetermined gap between the induction coil and the outer bottom surface of the pot.

In such a structure, the induction coil is formed in a substantially flat shape so as to face only the outer bottom surface of the pan. Therefore, the induction coil is easier, more efficient, and less expensive than the conventional induction coil having a three-dimensional structure. Can be manufactured.
Further, since the induction coil is substantially flat, it is easy to handle such as transportation and storage after manufacturing the induction coil, and handling when incorporating the induction coil into the inner frame of the rice cooker.

A protective member which is arranged on the induction coil and covers the induction coil is provided so as to open a predetermined gap between the outer bottom surface of the pot and the outer bottom surface of the pot without contacting the outer bottom surface. Therefore, the heat of the pan does not directly transfer to the protective member, which suppresses the temperature rise of the protective member.For example, when the pan heats up abnormally due to a failure of the control circuit that controls the induction coil. Even if there is, it is possible to prevent softening or melting of the protective member and avoid the risk of insulation deterioration of the induction coil.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is a rice cooker body,
An annular frame 2 is attached to an opening edge of the upper end of the rice cooker main body 1. Inside the rice cooker body 1, an inner frame 3 made of a material having excellent heat conductivity such as aluminum is provided. The inner frame 3 has a flange 4 integrally with an opening edge at an upper end, and the flange 4 is an annular frame. 2 is locked to the inner peripheral edge.

At the bottom of the inner frame 3, an insulating plate 5 made of a material having heat resistance and electric insulation such as heat resistant glass, ceramics or PPS resin is provided as a protective member. On the lower surface of the insulating plate 5, there is provided an induction coil 6 formed in a substantially planar shape by a litho wire or the like. The induction coil 6 is provided by a coil cover 7 made of a heat-resistant FR-PET resin or the like. The whole is covered and supported.

The peripheral edge of the coil cover 7 extends substantially horizontally to the outside of the inner frame 3, and the coil cover 7 defines a ventilation path 8 in the lower portion of the rice cooker body 1.
A plurality of ferrite rods 9 are attached to the lower surface of the coil cover 7 corresponding to the induction coil 6 with an adhesive, and the ferrite rods 9 are obtained by sintering a material having a high magnetic permeability using iron oxide as a main raw material. In order to prevent the leakage magnetic flux of the induction coil 6, it is provided.

A pot 12 is removably housed in the inner frame 3, and the pot 12 is composed of an inner container 13 and an outer container 14 in a double wall structure. The periphery of the upper end of 14 is airtightly bonded and fixed by Tig welding, and the inside thereof is decompressed to form a vacuum layer 15.

As shown in FIG. 2, the inner container 13 is made by bonding a magnetic material 13b such as ferritic stainless steel (SUS430) to the outer surface of a high thermal conductive material 13a such as aluminum, and the outer container 14 is an austenitic material. It is made of non-magnetic material such as stainless steel (SUS304). Further, a non-adhesive layer 13c made of a fluororesin coating is provided on the inner surface of the inner container 13. For example, the thickness of the high thermal conductive material 13a constituting the inner container 13 is 1.7 mm, the thickness of the magnetic material 13b is 0.3 mm, and the thickness of the outer container 14 made of a non-magnetic material is 0.5 mm.

The opening at the upper end of the pot 12 thus constructed expands in a tapered shape, and the tapered surface on the outer periphery of this opening abuts against the opening edge at the upper end of the inner frame 3, and by this abutment. The pot 12 is supported with a slight gap between the inner surface of the inner frame 3 and the upper surface of the insulating plate 5, and the space between the outer surface of the pot 12 and the inner surface of the inner frame 3 and the upper surface of the insulating plate 5 is It is an air layer 17. The induction coil 6 is formed in a substantially flat shape facing only the outer bottom surface of the pot 12 with the insulating plate 5 interposed therebetween. The opening at the upper end of the pan 12 may have a shape that expands in a curved shape.

On the outer peripheral surface of the inner frame 3, the glass fiber core is made of Ni.
A —Cr heating wire or the like is wound, and an electrothermal drum heater 18 whose outer circumference is electrically insulated by heat resistant silicone or the like is wound around and fixed by an adhesive. The body heater 18 is wound around the inner frame 3 so as to gradually increase the heating density toward the lower part of the inner frame 3. Further, a temperature detector 19 having a built-in temperature sensor such as a thermistor and a temperature fuse 20 are attached to the upper portion of the outer peripheral surface of the inner frame 3.

A hinge shaft 2 is provided on the top of the rice cooker body 1.
2, the lid 23 is rotatably supported in a vertically rotatable manner,
The lid 23 is elastically urged in the upward rotation direction via a spring 24 mounted on the hinge shaft 22. A clamp mechanism 2 is provided at the upper part on the front side of the rice cooker body 1.
5 is provided, and the edge on the free end side of the lid 23 is detachably locked by the clamp mechanism 25, and the lid closes the upper surface of the rice cooker main body 1 by this locking, and the locking is performed. Is released, the lid 23 is automatically rotated upward by the urging force of the spring 24, and the upper surface of the rice cooker main body 1 is opened.

An inner surface plate 27 made of aluminum or the like is attached to the inner surface of the lid body 23, and an inner lid 29 is detachably attached to the lower surface side of the inner surface plate 27 via a stud 28. The opening portion of the pot 12 is closed with, and a plurality of small holes 30 are formed in the inner lid 29.
A temperature detector 31 having a built-in temperature sensor such as a thermistor,
A lid heater 32 having the same structure as that described above is attached. Further, the lid 23 is provided with a packing 33 for sealing the opening of the pot 12 and a steam port 34 for releasing the steam to the outside when the steam pressure in the pot 12 rises above a certain level.

A control circuit section 36 including a circuit for applying AC power to the induction coil 6 is provided in the ventilation passage 8 formed in the lower portion of the rice cooker body 1. An electric fan 37 is provided on one end side. At the bottom of the rice cooker main body 1, a plurality of intake ports 38 are formed facing the electric fan 37, and an exhaust port 39 is formed on the opposite side.

A cylindrical heat shield plate 41 formed of a steel plate or the like is provided on the outer peripheral side of the inner frame 3, and a micro heat shield plate 41 is provided outside the heat shield plate 41 and inside the front side of the rice cooker body 1. A control circuit unit 42 including a computer and the like is provided.
43 is an operation display board, 44 is an operation display panel, 4
Reference numeral 5 denotes a cord reel device for winding a power cord (not shown).

Next, the operation will be described. When cooking rice, the lid 23 is opened, the pot 12 is taken out from the inner frame 3, and the washed rice and water are stored in the pot 12. Then, the pot 12 is housed in the inner frame 3, the lid 23 is closed, and a start switch (not shown) is turned on. In response, the control circuit units 36 and 42, the body heater 18, the lid heater 32, and the electric fan 37 are driven.
Then, a high-frequency current flows through the induction coil 6 under the control of the control circuit unit 36 to generate an alternating magnetic field, which causes an eddy current to flow in the pot 12, and the magnetic material 13b of the inner container 13 mainly causes Joule heat due to the eddy current. Fever. Then, the heat is conducted to the entire inner container 13 through the high heat conductive material 13a of the inner container 13, whereby the rice and water in the pan 12 are almost uniformly heated, and the rice cook gradually proceeds by this heating.

On the other hand, the electric fan 37 is rotated by driving the electric fan 37, and this rotation causes the rice cooker body 1 to rotate.
The cold air outside is sequentially sucked into the ventilation path 8 through the intake port 38, and the cold air flows through the ventilation path 8 and is sequentially discharged from the exhaust port 39. Then, the control circuit section 36 and the induction coil 6 are cooled by the cool air flowing through the ventilation path 8, and the temperature rise is suppressed.

When a predetermined time elapses after the pot 12 heats up, the rice cooking is completed, the operation of the induction coil 6 is stopped accordingly, and the process proceeds to the heat retaining step. Between the inner container 13 of the pan 12 and the outer container 14, a vacuum layer 1 exhibiting good heat insulating properties
5, the heat of the inner container 13 and the heat of the rice in the inner container 13 is cut off by the vacuum layer 15, and the heat dissipation to the outer container 14 side is greatly suppressed. Therefore, the rice in the inner container 13 is sufficiently kept warm, and is satisfactorily eaten, resulting in delicious rice.

The body heater 1 during and after the purging process
8 and the lid heater 32 continue to be energized, and the heat generated by the body heater 18 and the lid heater 32 keeps the rice properly warm even after the rice is uneven.

By the way, the induction coil 6 in this rice cooker is formed in a substantially flat shape so as to face only the outer bottom surface of the pot 12, so that it is easier and more efficient than the induction coil having the conventional three-dimensional structure. And it can be manufactured at low cost. Since the induction coil 6 has a substantially flat shape, it is easy to handle the induction coil 6 after its manufacture, such as transportation and storage, and when incorporating the induction coil 6 into the inner frame 3 of the rice cooker.

Further, the insulating plate 5 covering the induction coil 6
Is provided so as not to come into contact with the outer bottom surface of the pan 12 and to leave a predetermined gap between the outer bottom surface and the outer bottom surface.
There is no case where the heat of No. 2 is directly conducted to the insulating plate 5, and therefore the temperature rise of the insulating plate 5 is suppressed, and for example, the pan 12 abnormally heats up due to a failure of the control circuit unit 36. Also, the insulating plate 5 can be prevented from softening and melting, and the risk of insulation deterioration of the induction coil 6 can be avoided.

If an austenitic stainless non-magnetic material is used for the outer container 14 of the pot 12, there is an advantage that it is resistant to corrosion. Further, in the above embodiment,
The inner container 13 of the pan 12 is made of a high heat conductive material 13a and a magnetic material 13b.
However, the inner container 13 may be formed only of a magnetic material.

Further, as in the present invention, means for heating a container having a double-wall structure and having a vacuum layer between the walls by using an induction coil is not limited to a rice cooker, but may be an electric pot, a hot plate, or a kettle pot. It is also possible to apply to such as.

[0029]

As described above, according to the present invention, the induction coil can be easily and efficiently manufactured, and the induction coil can be handled for transportation and storage, and can be incorporated in the inner frame of the rice cooker. The handling of the induction coil is easy, and the temperature rise of the material covering the induction coil is suppressed. Even when the pan heats up abnormally, the protection member is prevented from softening and melting and insulation of the induction coil is reduced. You can avoid the danger of.

[Brief description of drawings]

FIG. 1 is a sectional view of a rice cooker showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a part of the pot of the rice cooker.

[Explanation of symbols]

 1 ... Rice cooker body 3 ... Inner frame 5 ... Insulation plate (protective member) 6 ... Induction coil 12 ... Pot

Claims (1)

[Claims] 1. An induction coil for pan induction heating, which is substantially flat and faces only the outer bottom surface of the pan, is provided at the bottom of an inner frame for accommodating the pan, and the outer bottom surface of the pan is provided above the induction coil. An induction heating type rice cooker characterized in that a protective member having an electric insulation property is provided between the rice cooker and the rice cooker with a predetermined gap.