JPH08256906A - Rice cooker - Google Patents

Abstract

PURPOSE: To heat an inner oven by a lamp heater with high efficiency. CONSTITUTION: An inner oven 5 and an annular lamp heater 6 are interpolated in an inner pan 3 provided in a rice cooker main body 1, and a glass protector 7 is arranged between the inner oven 5 and the lamp heater 6. The lamp heater 6 is arranged in a center part for the bottom of the inner oven 5, and the diameter (d) of the ring of the lamp heater 6 is set at a value between 35-45% of the major diameter (D) of the bottom of the inner oven 5. The interval A between the inner pan 3 of the lamp heater 6 is set at a value between 15-20mm, and the interval B between the inner oven 5 at a value between 15-25mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker having a heat retaining function using a lamp heater which emits electromagnetic waves as a heating source.

[0002]

2. Description of the Related Art Conventional rice cookers generally use a sheathed heater as a heat source, but they have problems in uniform heating, rapid heating and cleaning. Therefore, there is provided a rice cooker that heats the inner pot of a magnetic material by electromagnetic induction by changing the magnetic flux of the induction coil. However, there are still problems in heating efficiency and cost.

Therefore, Japanese Patent Laid-Open No. 6-327552 proposes a rice cooker using a lamp heater having a low cost and a rapid heating property as a heat source. In this rice cooker,
As shown in FIG. 3, a pan for accommodating an aluminum pan 18 is provided in the main body C, an inner frame 20 having a lower diameter larger than the inner diameter of the upper part is provided, and a glass plate 21 closing the bottom thereof is fixed. A housing portion 19 is provided. A heater unit 26 covered with a heater cover 27 is provided on the lower surface side of the glass plate 21, and the heater unit 26 has a circular halogen lamp corresponding to the outer peripheral portion of the pot 18 in a heat insulating material 29 in the shape of a shallow circular container. The heater 30 is accommodated in the heat insulating material 29, and a conical convex portion 31 is integrally formed at the center of the heat insulating material 29.

[0004]

In the above rice cooker, the circular halogen lamp heater 30 corresponding to the outer peripheral portion of the pan 18 heats the pan, but this structure strongly heats the outer peripheral side of the bottom surface of the pan 18. As a result, heating is insufficient in the central portion, and uneven heating occurs without uniform heating. Therefore, by providing the conical convex portion 31 at the center of the upper surface of the heat insulating material 29, uniform heating property and heating efficiency are improved. However, such a reflecting member must be separately provided, and there remains a problem that the production cost becomes high. Further, since the lower side surface of the pot 18 is heated by radiant heat, a space for reflecting light is formed between the lower inner periphery of the inner frame 20 and the lower outer periphery of the pot 18.
Structure becomes complicated, leading to higher production costs.

In view of the above, it is an object of the present invention to provide a rice cooker having a simple structure and improved heating efficiency and uniform heating property.

[0006]

As shown in FIG. 1, a rice cooker main body 1 has a selective absorption film for absorbing electromagnetic waves on the outer surface thereof and a flat bottom surface. The inner pot 5, the lamp heater 6 bent in an annular shape, the protective body 7 arranged between the inner pot 5 and the lamp heater 6, and the inner pot 3 surrounding the inner pot 5 and the lamp heater 6 are internally provided. The lamp heater 6 is arranged centrally with respect to the bottom surface of the inner pot 5, and the diameter d of the ring in the lamp heater 6 is within the range of 35% to 45% of the outer diameter D of the inner pot 5. Is the inner pot 3
And the distance A between the inner pot 5 and the inner pot 5 is 15 mm or more and 25 mm or less. The protective body 7 has a thickness of 2 mm or more and 4.5 mm or less, and the lower surface thereof is covered with a resist 12 that transmits electromagnetic waves.

Further, as shown in FIG. 4, the outer peripheral portion of the lower surface of the inner pot 5 is a curved surface portion 13a having a sectional shape dimension of R50 mm to R80 mm or a taper 13b having a C50 mm to C80 mm, and the inner pot 3 and the outer peripheral portion of the inner pot 5 are connected. A space 14 for receiving an electromagnetic wave may be formed between them.

Further, as shown in FIG. 5, the annular lamp heater 6 is divided into a plurality of lamp heaters, and control is performed so that there is a time difference (about 1 second) between the energization start times of the respective heaters at the beginning of energization. Good.

[0009]

In the above means for solving the problem, when the rice cooking is started, the lamp heater 6 is turned on, and the electromagnetic wave from the lamp heater 6 permeates the protective body 7 to heat the inner pot 5. At this time, the lamp heater 6 is arranged centrally with respect to the flat bottom surface of the inner pot 5, and the ratio of the diameter d of the ring in the lamp heater 6 and the outer diameter D of the inner pot 5 is within the range of 35% to 45%. By setting to, the inner pot 5 can be heated with the maximum heating efficiency.

Since the lamp heater 6 is set to have a distance B from the inner pot 5 of 15 mm to 25 mm, the inner pot 5 can be heated uniformly. Moreover, since the inner pot 3 is set to have a distance A between the lamp heater 6 and the lamp heater 6 of 15 mm to 20 mm, electromagnetic waves from the lamp heater 6 can be efficiently reflected toward the inner pot 5. Further, since the protective body 7 has a thickness of 2 mm or more and 4.5 mm or less, the electromagnetic waves of the lamp heater 6 are efficiently transmitted.

Even if the rice cooker 5 is removed from the rice cooker main body 1 after the rice is cooked, the protector 7 prevents the infusion of broth or foreign matter into the inner pot 3, and water drops or broth can be removed from the lamp heater 6.
Will not adhere to. Moreover, since the inside of the rice cooker body 1 is masked by the resist 12, it cannot be seen.

A curved surface portion 13a is formed on the outer peripheral portion of the bottom surface of the inner pot 5.
Alternatively, by providing the taper 13b and forming the space 14 between the inner pot 5 and the inner pot 3, the inner pot 5 can be efficiently heated by utilizing the electromagnetic waves reflected from the inner pot 3, and the inner pot 5
The bottom surface of the can be heated widely and uniformly.

Further, by constructing the annular lamp heater 6 by a plurality of lamp heaters having the same total power consumption, the heating efficiency equivalent to that when a single annular lamp heater 6 is used is obtained. By providing a time difference at the beginning of the energization start, the breaker operation due to the rush current at the beginning of the energization start of the lamp heater 6 can be prevented.

[0014]

【Example】

(First Embodiment) As shown in FIG. 1, the rice cooker of this embodiment includes a rice cooker main body 1 having a short cylindrical shape with a bottom and an openable lid 2 for covering an upper opening of the rice cooker main body 1. Is provided with an inner pot 3 and an outer pot 4 with a gap so as to cover the inner pot 3. The inner pot 3 accommodates an inner pot 5 having a flat bottom so that it can be inserted and removed, and an annular lamp heater 6 as shown in FIG. And a protective body 7 is provided between the lamp heater 6 and the inner pot 5. The upper lid 2 is formed in a hollow shape, and an inner lid that covers the upper opening of the inner pot 5 so as to be openable and closable is attached to the lower surface so as to move slightly up and down. A heat retaining heater is mounted inside the hollow to perform a heat retaining function.

The inner pot 3 is a circular container made of aluminum or an aluminum alloy having a specular luster with a bright smooth surface finish having a high reflection efficiency on at least the inner surface, or a bright aluminum-plated steel plate, and the upper edge of which is cooked rice. It is attached to the container body 1. In addition, the inner surface, which has a mirror-like gloss, has durable heat-resistant and corrosion-resistant SiO 2.
₂ A transparent thin film coat of sol-gel paint is applied to a film thickness of about 1 to 10 μm to enhance the heat recovery effect.

Further, a step 8 is formed on the lower inner circumference of the inner pot 3 so that the protector 7 is placed on the lower inner circumference, which is slightly smaller than the upper inner circumference. Further, the inner surface below the protector 7 has a particularly good mirror finish to improve the reflection efficiency of electromagnetic waves.

The outer pot 4 plays the role of a partition plate that blocks outward radiation from the inner pot 3, and is made of stainless steel such as SUS430 having a heat-reflecting efficiency and heat-resistant mirror surface luster. Steel plates, aluminized steel plates and aluminum are suitable. The outer pot 4 is a container having a larger diameter than the inner pot 3 and is fixed to the rice cooker body 1. The gap between the outer pot 4 and the inner pot 3 serves as a heat insulating layer, and the rice cooker body 1
It prevents the outer surface of the machine from getting hot. By using a vacuum structure for the outer pot 4 and the inner pot 3 such that the void is not air but a vacuum, the heat insulating effect is enhanced and the heating efficiency of the inner pot 5 is improved, and the outside of the rice cooker body 1 is improved. The prevention of high temperature on the surface becomes even more remarkable. Below the outer pot 4, a cooling fan and a cord reel (not shown) are installed.

The inner pot 5 is made of a metal having high thermal conductivity, heat resistance and impact resistance, such as aluminum or aluminum alloy, as a base material, and has a flat bottom surface and above the protector 7. It is supported by the upper edge of the inner pot 3. A temperature detector 9 is provided through the protective body 7 so as to come into contact with the bottom surface of the inner pot 5. The detected temperature is transmitted to a control unit such as a microcomputer, so that the lamp heater 6 and the heat retaining heater are energized.

A fluororesin coating layer is formed on the inner surface of the inner pot 5 in order to improve cleaning performance.
As a result, the cooked rice attached to the inner pot 5 can be easily washed off, and the cooked rice can be stirred easily. A far-infrared radiation coating having excellent non-adhesiveness and heat radiation may be applied instead of the fluororesin coating layer. This is a powder coated with a heat-resistant fine powder of metal oxide, carbon black, a mica pigment and a fluorotetrafluoride resin as the main component, and a wavelength of 5.6 to 25 μm.
It is possible to radiate the electromagnetic wave and prevent the cooked food from sticking and improve the cleaning property.

On the outer surface of the inner pot 5, a wavelength of 0.3 to
A black selective absorption film having a characteristic of absorbing an electromagnetic wave of a far infrared ray from a visible ray of up to 5.6 μm and reflecting an electromagnetic wave of a wavelength of 5.6 to 25 μm is formed. The selective absorption film is formed by subjecting a thin semiconductor film of nickel oxide, copper oxide, chrome oxide, cobalt oxide, iron oxide or the like to a film thickness of 10 μm or less by secondary alumite electrolytic coloring or paint coating. The selective absorption film has a composition that can withstand a temperature of 300 ° C. or higher, which increases the efficiency of absorbing electromagnetic waves emitted from the lamp heater 6 to 90% or more, and the absorbed electromagnetic waves cause water in the inner pot 5 to absorb water. And heat rice efficiently.

By the way, in addition to the above-mentioned selective absorption film, a black film using a selective absorption paint, or a cobalt film or black chrome film selection treatment having a selective absorption performance when a metal other than aluminum is used as a base material. Etc. Also, black alumite, black heat resistant coating, or ceramic coating, which has no selective absorption but has excellent heat absorption, may be used.

The surface treatment of the inner pot 5 is performed as follows. That is, the inner surface of an aluminum inner pot molded product which is the base material of the inner pot 5 is subjected to a pretreatment for roughening by blasting or the like, and a fluororesin-based paint is applied onto the pretreatment layer to form a fluororesin. It forms a coating layer. In addition, the outer surface of the inner pot molded product is treated so as to have a glossy smooth surface, and after degreasing the pre-treatment of this smooth finished outer surface, the pickling surface is anodized. On the alumite-treated layer, a black electrolytic absorption film for secondary electrolytic coloring is formed with a salt such as nickel.

The lamp heater 6 is bent in an annular shape in which both ends are close to each other, and the center of the ring is on a perpendicular line passing through the center of the bottom surface of the inner pot 5 and is parallel to the inner pot 5. The terminal portion 10 is attached to the bottom of the inner pot 3 via a support or the like so that the terminal portion 10 projects to the outside of the inner pot 3. As a heater of a rice cooker, an electromagnetic wave having a wavelength in the visible to far infrared region, specifically, a wavelength of 0.3 to 5.6 is used.
It consists of a heating element that generates electromagnetic waves up to μm, and mainly consists of halogen heater, quartz glass tube heater, Kanthal Super (trade name of electric resistance heating element made by Kanthal Co., Ltd., molybdenum disilicide MoSi ₂ and glass phase. A dense cermet material composed of a ceramic component) that can generate instantaneous heat or relatively fast heat is suitable. When using a halogen heater, when the rice cooking capacity is 1.0l to 1.8l, AC100V 800W to 1200
It is common to use the one with W rating.

That is, since these instantaneous heating elements have a small heat capacity and generate heat quickly and store little heat when the power is turned off, they cool quickly and cool the inner pot 5 quickly. The fact that there is little heat effect on the rice will lead to a delicious ideal cooking process condition.

The protector 7 is a glass plate made of crystallized glass having a high thermal shock resistance that transmits electromagnetic waves, is a flat plate having substantially the same diameter as the inner pot 5, and has a small hole 11 formed in the center. The sensor portion of the temperature detector 9 penetrates from below. Further, the outer peripheral edge of the protector 7 is placed on the step 8 of the inner pot 3 and is detachable. As described above, by being located between the lamp heater 6 and the inner pot 5, the lamp heater 6 is prevented from being damaged by a foreign substance falling, and also water droplets or broth is prevented from adhering to the lamp heater 6.

The material of the protector 7 is required to be heat-resistant glass having a thermal shock resistance capable of withstanding a long temperature difference of 300 ° C. due to the temperature difference of cold heat shock. Therefore, it cannot be used unless it is crystallized glass. Actually, Pyrex glass, which is said to have heat resistance, was tested, but it cracked after being used 2-3 times. The reason is that even if annealing is performed to remove thermal strain before use, distortion occurs due to the temperature difference that occurs during use. On the other hand, the crystallized glass is completed by being subjected to crystallization heat treatment before molding before use, so that it has no distortion and the temperature difference due to thermoshock is 800 ° C., so that there is an advantage that no distortion occurs during use.

A heat-resistant resist 12 is formed on the lower surface of the protector 7 by printing a transparent transparent glaze. That is, a coating film material that is a print finish by silk screen printing that transmits electromagnetic waves, for example, a glass frit binder made into an ink is printed and fired. The reason why the printing is on the lower surface is to prevent foreign matter from falling and scratches caused by cleaning. This has the effect of forming a colorful pattern, making the lamp heater 6 less visible and improving the design. The color tone of the protector 7 may be transparent, but considering the design of the inside of the rice cooker, that is, the inside in which the inner pot 5 is removed, the lamp heater 6 and the inner pot 3 installed below the protector 7 are considered. It is recommended to use colored transparent glass such as red, brown, purple, and white in order to make the bottom part of the glass invisible.

In addition, the glass color of the protector 7 is changed to a transparent color, or heat-resistant frit color pattern printing, which has little influence on light transmission, and a color clear thin film containing glaze and a coloring pigment as main components. By performing the transparent printing, the electromagnetic waves emitted from the lamp heater 6 can be transmitted with a transmission efficiency of 90% or more.

In this embodiment, the lamp heater 6 for the inner pot 5 and the inner pot 3 is provided for uniform heating and improvement of heating efficiency.
And the relative positional relationship of the diameter of the ring in the lamp heater 6 and the outer diameter D of the inner pot 5, the distance A between the lamp heater 6 and the inner pot 3, and the distance B between the lamp heater 6 and the inner pot 5.
Is adjusted as a parameter so that the maximum heating efficiency can be obtained and uniform heating can be performed.

The distance B between the lamp heater 6 and the inner pot 5 is 1
It is set to 5 mm to 25 mm. The space in which the lamp heater 6 is housed is preferably as small as possible in order to reduce heat accumulation, and the space between the bottom surface of the inner pot 5 and the bottom surface of the inner pot 3 is also preferably as small as possible, but the space between the lamp heater 6 and the inner pot 5 is small. If B is too small (15 mm or less), the inner pot 5
Is heated locally and cannot be heated uniformly. Further, if the distance B is large, the thermal efficiency also decreases, and it is preferable that the distance is 25 mm or less for efficient heating.

The distance A between the lamp heater 6 and the inner pot 3 is 1
Within 5 mm to 20 mm. If the distance A is too small (15 mm or less), the bottom surface of the inner pot 3, which is also a reflector, is locally heated to deteriorate the reflection efficiency, and if it is too large, the heat efficiency also decreases. In order to reflect the light of the lamp heater 6 uniformly, the length is preferably 20 mm or less. However, the outer diameter of the quartz tube of the lamp heater 6 is 10 mm.

Further, the diameter d of the ring in the lamp heater 6 is within the range of 35% to 45% of the outer diameter D of the bottom surface of the inner pot 5. FIG. 3 is a graph showing the change in heating efficiency when the ratio of the diameter d of the ring in the lamp heater 6 to the outer diameter D of the inner pot 5 is changed. It can be seen that the heating efficiency is high at 35% to 45% of the outer diameter D of the inner pot 5. The size of the outer diameter D of the inner pot 5 may be changed by about 10% for various reasons, but even at that time, the ratio falls within such a value.

For example, when cooking five meals (rice cooking capacity 1.0 l), the outer diameter D of the inner pot 5 is 204 mm and the ring diameter d of the lamp heater 6 is 80 mm, and one bowl (rice cooking capacity 1.
8l), the outer diameter D of the inner pot 5 is 234 mm and the ring diameter d of the lamp heater 6 is 100 mm.

Further, the thinner the plate thickness of the protector 7 is, the more the heating efficiency is improved, but if the thickness is 1.9 mm or less, there is a problem that the strength is insufficient for use in a rice cooker. As shown in FIG. 3, with the plate thickness as a parameter, (a) 2 mm, (b) 3 mm,
(C) When the thickness is 4.5 mm, the heating efficiency decreases as the plate thickness increases. Therefore, the plate thickness of the protector 7 is 4.
When the thickness is 6 mm or more, the heating efficiency is remarkably reduced, the rice cooking ability is lowered, and it becomes difficult to cook delicious cooked rice. Further, when the above-mentioned printing finish is applied to the protective body 7 having a plate thickness of 2 mm, as is clear from the curve (D) in the figure, even if the printing finish is applied, the thermal efficiency is slightly reduced and the rice cooking performance is improved. Has almost no effect on

In the above construction, when the washed rice and water are put into the inner pot 5 and the rice cooking operation button on the operation panel is pushed, rice cooking is started and the lamp heater 6 heats the inner pot 5.
At this time, the electromagnetic waves emitted upward from the lamp heater 6 reach the protective body 7. Further, the electromagnetic waves emitted downward are reflected by the bottom surface of the inner pot 3 and reach the protective body 7. Then, on the lower surface of the protective body 7, the electromagnetic wave is transmitted through or slightly absorbed by the protective body 7, converted into heat, and radiated from the upper surface of the protective body 7. Then, the heat or the transmitted electromagnetic wave radiated from the upper surface is absorbed by the selective absorption film of the inner pot 5, and the heat is transmitted to the cooking water inside the inner pot 5.

The temperature of the inner pot 5 is detected by the temperature detector 9 and compared with the set temperature by the controller. Inner pot 5
When the temperature reaches the set temperature, all the lamp heaters 6 are cut off. Then, the outer surface of the inner pot 5 and the inner surface of the inner pot 3 which have become high in temperature during rice cooking are cooled. When the temperature of the inner pot 5 falls below a set temperature, the lamp heater 6 is energized to heat the inner pot 5, and the heat retaining heater heats the upper lid 2 to keep the cooked rice cooked at a constant heat retaining temperature. .

As described above, the ratio of the diameter d of the ring in the lamp heater 6 to the outer diameter D of the inner pot 5 is set so as to obtain the maximum heating efficiency, so that the speed of cooking rice can be increased. be able to. Also, the lamp heater 6 is 1
Since the inner pot 5 is heated at intervals of 5 mm to 25 mm, uniform rice heating can be performed and uneven cooking can be eliminated. Further, the distance D between the lamp heater 6 and the inner pot 3 is 15 mm to 2
Since it is set to 0 mm, the inner pot 3 efficiently reflects the electromagnetic wave from the lamp heater 6 toward the inner pot 5, and the inner pot 5 is efficiently heated.

From the above, the rise of temperature rise to the water absorption region during rice cooking is accelerated, and the rice can be sufficiently absorbed by uniforming the temperature in the water absorption region. Then, the rise in temperature rise to the rice cooking area is accelerated, the cooked rice is cooked by uniform heating, the starch is gelatinized, and the starch is completely gelatinized in the spotty area. Obtainable.

When the rice cooker 5 is removed from the rice cooker body 1 after the rice is cooked, the lamp heater 6 is turned on by the protector 7.
Is hidden and the infusion of broth and foreign matter into the inner pot 3 is prevented. Furthermore, water drops, broth, etc. will not adhere to the lamp heater 6. Therefore, it is possible to prevent the lamp heater 6 from being damaged or corroded and deteriorated due to the adhesion of foreign matter, and it is possible to improve durability and prolong the life. In addition, since the inside of the rice cooker body 1 is masked by the colorful resist 12, it is possible to provide a rice cooker having a good design with a clean design and a clean design. By making the protective body 7 detachable, cleaning can be facilitated, parts can be easily replaced, and product assemblability can be improved.

(Second Embodiment) In the rice cooker of the first embodiment,
Since the inner surface of the inner pot 3 is in close contact with the outer surface of the inner pot 5, electromagnetic waves do not illuminate the outer surface of the inner pot 5. That is, since the electromagnetic wave heats only the bottom surface of the inner pot 5, there is still room for improvement in uniform heating property.

Therefore, the rice cooker of the second embodiment is shown in FIG.
As shown in (a), a space 14 for receiving electromagnetic waves is formed between the inner pot 3 and the top surface of the bottom of the inner pot 3 by forming a curved surface portion 13a having a circular arc with a radius of R50 mm to R80 mm on the outer periphery of the bottom surface of the inner pot 5. It is provided. Alternatively, FIG.
As shown in (b), the space 14 may be provided by forming a taper 13b having a chamfering dimension of C50 mm to C80 mm on the outer periphery of the bottom surface of the inner pot 5. However, the curved surface portion 13a forming a circular arc whose cross section is R50 mm or less or the chamfered dimension is C50 m.
When the taper 13b of m or less is provided, the amount of electromagnetic waves received from the lower side surface of the inner pot 3 decreases and uniform heating cannot be performed. If the curved surface portion 13a having a circular arc with a cross section of R80 mm or more or the taper 13b with a chamfering dimension of C80 mm or more is provided, when the inner pot 5 is placed on a sink or the like, there arises a problem such as an unstable placement.

Further, as shown in FIG. 5A, the lamp heater 6 is composed of two lamp heaters 6 bent in a semicircular shape.
The combination of a and 6b is arranged in an annular shape. The lamp heaters 6a and 6b have linear portions left at both ends, and a terminal portion 10 is provided at the tip thereof. Terminal part 10
Has a short-cylindrical terminal cover and an electrode that is in contact with a heating element inside the lamp heater 6 and penetrates to the outside of the terminal cover. The lamp heaters 6a and 6b are held in the inner pot 3 by a supporting tool.

Furthermore, in order to suppress the rush current at the initial stage of the start of energization of the lamp heaters 6a, 6b,
As shown in FIG. 6, each lamp heater 6a, 6b is connected in parallel to the AC power supply 17, and each lamp heater 6a, 6b
Relays 15a and 15b are connected in series to 6b.
Each of the relays 15a and 15b is connected to the control unit 16, and the control unit 16 performs control such that there is a time difference (about 1 second) between the energization start times of the lamp heaters 6a and 6b at the beginning of energization. Is going.

That is, the two lamp heaters 6a, 6b
The power consumption is reduced to one half by using each of the lamps, and if a time difference of about 1 second is given to the input currents at the beginning of energization of the lamp heaters 6a and 6b, the power suppression circuit suppresses the rush current. Need not be provided to perform drive control, the electric circuit can be simplified, malfunctions and failures are reduced, and the life of the circuit and the lamp heater 6 is lengthened.
There is an advantage that the manufacturing cost of the electric circuit is reduced.

In the above structure, as shown in FIG. 7, when rice cooking heating is started, one relay 15 is controlled by the control unit 16.
a is turned on, and only the corresponding lamp heater 16a generates heat for 1 second. After 1 second, one relay 15a is turned off and the other relay 15b is turned on, and only the corresponding lamp heater 6b generates heat for 1 second. When one second has elapsed, one relay 15a is turned on again and 100% energization is performed.

During cooking, the electromagnetic wave transmitted through the protective body 7 reaches the inner pot 5 directly or is reflected by the inner surface of the inner pot 3 and passes through the space 14 to reach the curved surface portion 13a or the taper 13b of the inner pot 5. .

As described above, the curved surface portion 13a is formed on the bottom surface of the inner hook 5.
Alternatively, since the space 14 is formed by providing the taper 13b and the electromagnetic wave directed to the inner pot 3 is also effectively used,
The inner pot 5 can be efficiently heated, and since the lower part of the inner pot 5 is widely heated, uniform heating is possible, and delicious cooked rice without unevenness can be cooked. Furthermore, make sure that the total of power consumption is the same as that of one lamp heater.
By arranging the lamp heaters 6a and 6b in a ring shape,
While achieving the same heating efficiency as when using a single ring-shaped lamp heater, the rapid heating is enhanced, and the rush current at the beginning of energization of the lamp heater is suppressed, and the circuit breaker is simple to operate. Can be prevented.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention. For example, as shown in FIG. 5 (b), three lamp heaters 6c, 6d, 6e bent in an arc shape are arranged in an annular shape, and three relays corresponding to each lamp heater are provided. Control may be performed to suppress the rush current at the beginning of energization. Further, a plurality of lamp heaters having different ring diameters in the lamp heater may be concentrically arranged to form the lamp heater.

[0049]

As is apparent from the above description, claim 1
According to the inventions 1 and 2, the matching portion between the outer diameter of the inner pot and the ring of the lamp heater is found, and the ring of the lamp heater is set to the outer diameter of the bottom of the inner pot by 3
By setting it in the range of 5% to 45%, the maximum heating efficiency can be obtained, and the speedup of the cooking time can be achieved.

According to the third aspect of the present invention, by arranging the plurality of lamp heaters in a ring shape, the bottom surface of the inner pot can be heated uniformly, and the rush current at the initial stage of energization start can be suppressed by a simple circuit. Become.

According to the invention of claim 4, the lamp heater heats the inner pot at intervals of 15 mm to 25 mm, so that uniform cooking and heating can be performed. Further, since the lamp heater is spaced from the inner pot by 15 mm to 20 mm, the electromagnetic waves from the lamp heater can be efficiently reflected toward the inner pot, and the heating efficiency is improved.

According to the fifth aspect of the invention, the plate thickness of the protective body is made thin, that is, 2.0 mm or more and 4.5 mm or less within the range in which the strength that can be used in the rice cooker is maintained, so that the heating efficiency is improved. be able to. Furthermore, by coating the lower surface side of the protective body with a resist that transmits electromagnetic waves, the lamp heater is made hard to see and the design is improved.

According to the invention of claim 6, since the outer peripheral portion of the bottom surface of the inner pot is formed into a curved surface portion or a tapered shape to provide a space for receiving the electromagnetic wave, the electromagnetic wave traveling toward the inner pot is utilized to make it more uniform. It is possible to heat the rice, improve the heating efficiency, and cook evenly delicious rice.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a rice cooker according to a first embodiment.

FIG. 2 is a plan view of a lamp heater.

FIG. 3 is a diagram showing a change in heating efficiency with respect to a ratio of the diameter of the ring and the outer diameter of the inner pot in the lamp heater.

4A is a configuration diagram of a rice cooker having a curved surface portion on the bottom surface of the second embodiment, and FIG. 4B is a configuration diagram of a rice cooker similarly having a taper.

5A is a plan view of a lamp heater composed of two lamps, and FIG. 5B is a plan view of a lamp heater composed of three lamps.

FIG. 6 is an electric circuit diagram of a lamp heater.

FIG. 7 is a flowchart of lamp heater control at the beginning of energization.

FIG. 8: Configuration diagram of a conventional rice cooker

[Explanation of symbols]

 1 Rice cooker body 3 Inner pot 4 Outer pot 5 Inner pot 6 Lamp heater 7 Protective body 12 Resist 13a Curved part 13b Taper 14 Space A Distance between lamp heater and inner pot B Distance between lamp heater and inner pot d Lamp heater Ring diameter D Outer diameter of inner pot

Claims (6)

[Claims] 1. An inner pot provided in a rice cooker body, an inner pot, and a lamp heater arranged below the inner pot and bent in an annular shape are internally provided, and the lamp heater and the inner pot are provided. In a rice cooker in which a glass protector is provided between the lamp heater and the outer diameter of the inner pot, the ring diameter of the lamp heater is 35 mm.
% Or more and 45% or less, and the lamp heater is arranged centrally with respect to the bottom surface of the inner pot. 2. The rice cooker according to claim 1, wherein a bottom surface of the inner pot facing the lamp heater is formed in a flat shape. 3. An inner pot provided in the rice cooker body, an inner pot, and a lamp heater arranged below the inner pot and bent in an annular shape are internally provided, and the lamp heater and the inner pot are provided. A rice cooker in which a glass protective body is provided between the lamp heaters, wherein the lamp heaters are arranged in an annular shape by combining a plurality of arc-shaped lamp heaters. 4. The lamp heater has a space of 1 from the bottom of the inner pot.
The distance is 5 mm or more and 20 mm or less, and the distance from the bottom of the inner pot is 1
The rice cooker according to claim 1 or 3, wherein the rice cooker has a size of 5 mm or more and 25 mm or less. 5. The protective body has a thickness of 2 mm or more and 4.5 mm or more.
The rice cooker according to claim 1 or 3, wherein the lower surface of the rice cooker is coated with a resist that transmits electromagnetic waves. 6. The outer peripheral portion of the bottom surface of the inner pot is formed into a curved shape or a tapered shape, and a space for receiving an electromagnetic wave from a lamp heater is formed between the outer peripheral portion of the bottom surface of the inner pot and the inner pot. The rice cooker according to claim 1 or 3, characterized in that.