JP3192878B2 - 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 a rice cooker improved so as to improve the quality of cooked rice.

[0002]

2. Description of the Related Art FIGS. 9 to 11 show a conventional example. In FIG. 9, the pot 1 is formed in a cylindrical shape with a bottom wall having a substantially vertical peripheral wall, and the pot 1 is made of a magnetic material. Then, the two induction heating coils 2 and 3 are placed in the pan 1
The induction heating coils 2 and 3 are provided with a high-frequency current through the induction heating coils 2 and 3 to generate an induction current in the pan 1 and generate heat by resistance loss, thereby heating the pan 1 itself. It is something to do.

[0003] However, when cooking rice, usually,
As shown in FIG. 11 (b), the process includes a cooking process, a rice cooking process, and a cooking process. The repetition process is a predetermined time,
For example, the temperature is controlled in the vicinity of 45 to 55 ° C. so that water is soaked in the rice. In the rice cooking process, the induction heating coils 2 and 3 are fully energized so that the cooking proceeds and the water in the pan 1 evaporates. Is detected by a sensor or the like (not shown) (time t2), after a predetermined time has passed from that time (time t2 ′), the induction heating coils 2 and
3 to prevent the spill from the inside of the pan 1
Energize so as to keep the temperature close to 0 ° C. When the temperature in the bottom of the pot 1 exceeds 100 ° C. due to the absence of water in the pot 1, when a so-called dry-up is detected based on a temperature sensor (not shown) (time t3), the process shifts to the spotting process.

[0004]

However, in the above-mentioned conventional configuration, there is a problem that the temperature unevenness in the pot 1 is large and the cooked rice is slightly poor. That is, pot 1
This is because convection as shown in FIG. 9 occurs due to the substantially vertical cylindrical shape of the peripheral wall portion. More specifically, when the lower portion of the peripheral wall portion is heated by the induction heating coil 2, the water heated in that portion rises through arbitrary portions such as between rice and between the rice and the pot 1 peripheral wall portion. At the upper part of the peripheral wall of the pan 1, heat escapes from the surface of the pan 1, so that the pan 1 cools down and convection is downward at the upper part of the peripheral wall. Therefore, the water to be heated passes through the rice distant from the peripheral wall portion, and such convection occurs.

[0005] Since the convection in the pan 1 is not good as described above, a temperature difference is observed in each part in the pan 1 as shown in Table 1. In Table 1, the temperatures of the upper part PS1, the middle part PS2, and the bottom part PS3 near the peripheral wall inside the pot 1, the temperature of the upper part PM1, the middle part PM2, and the lower part PM3 of the middle part inside the pot 1 are the same. Upper part P in the center of the interior
C1, the temperature of the middle PC2 and the temperature of the bottom PC3. In this case, the upper PC1 in the center of the pot 1 is 90
The temperature of each part at the time of ° C. is shown, and the parenthesis in the table shows the temperature difference from this point PC1. in this case,
Top PS1, middle PS2 and bottom PS3 near the peripheral wall
, The temperature difference between the upper part PM1, the middle part PM2, and the bottom part PM3 in the middle part of the pot 1 is as large as 6.4 ° C. as shown by the equation (1). 10 (a), (b),
As shown in (c), there are variations in the temperature change in each part. In particular, it can be seen that the temperature difference is large in the central part even after the rice cooking process.

[0006]

[Table 1]

(Equation 1)

[0007] If the state of convection in the pot 1 is poor and the temperature of each part varies widely, even if one part reaches 100 ° C, it does not reach 100 ° C in many other parts. Α
Is not enough. In this state, if the function of detecting the evaporation of water and the function of preventing the spillover to reduce the heating power is activated (time point t2 '), there is a problem that the rice is not more and more pre-gelatinized.

Further, rice absorbs water when the temperature of the water does not reach 100.degree. C., and the rice is heated in a state of insufficient water absorption and dried up. For this reason, the rice cooking process ends before the rice is sufficiently converted to α. This can be understood from FIG. That is, in the rice cooking process, as the water temperature rises, the rice absorbs water and swells, so that the rice surface position LR and the water level LW rise, but when the LR and LW coincide, the water is almost absorbed by the rice. (Almost at time t2 '). However, at this point in time t2 ', as can be seen from FIGS. 10 (a), (b), and (c), the amount of water that has reached 100 ° C. is small, and the conditions for α-formation of heating at 100 ° C. in a sufficiently water-absorbed state are almost completely eliminated. not filled. In such a situation, the heating power reduction control is performed by the blow-off prevention function, so that the alpha conversion is not further promoted.

Such a problem can be similarly applied to a heating method using a general electric heater 4 as shown in FIG. Further, as the shape of the pot, there is a shape in which the curvature of the corner portion between the bottom wall portion and the peripheral wall portion is slightly increased like the pan 5 shown in FIG. A downward flow occurs in the portion, and there is the same problem as described above.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to improve the convection of water in a pot, eliminate a temperature difference, and obtain a good cooked state. To provide a rice cooker.

[0011]

The first means comprises a pot, heating means for heating the pot, and spill-prevention means for preventing spillage from the pot, wherein the pot is mounted on a peripheral wall thereof. A conical portion that extends upward at an angle of approximately 60 ° from the bottom wall peripheral edge, and the area of the peripheral side surface of the conical portion is larger than the area of the bottom wall portion, The invention is characterized in that the heating means is disposed from the periphery of the bottom wall of the pan to the conical portion, and a non-heating area is provided inside the periphery of the bottom wall of the pan (the invention of claim 1). .

The second means is characterized in that, in the first means, the conical portion is formed so as to be thicker than other portions (the invention of claim 2). The third means is characterized in that, in the first means, the conical portion of the pot is configured to incline above a prescribed maximum water level line (the invention of claim 3).

A fourth means is that, in the first means, the heating means has an electric heater, and the non-heating area is set to a range indicated by a diameter substantially equal to or more than half the diameter of the bottom wall of the pot. Features (the invention of claim 4). Fifth
In the first means, the heating means has a configuration in which the heating means has an electric heater and a heat transfer portion having a shape substantially matching from the periphery of the pot peripheral wall portion to the outer surface of the conical portion, and the heat transfer portion has a conical shape. The present invention is characterized in that it is provided so as to be in surface contact with the outer surface of the shaped part (the invention of claim 5).

A sixth means is the first means, wherein an auxiliary heating means is provided with a non-heating area inside the heating means,
The invention is characterized in that the heating means and the auxiliary heating means are constituted by induction heating coils, and the pot has an induction heating portion at a portion corresponding to the heating means and the auxiliary heating means (the invention of claim 6). . The seventh means is characterized in that in the sixth means, the input power of the heating means is set to be larger than the input power of the auxiliary heating means (the invention of claim 7).

[0015]

In the first means, when the pot is heated by the heating means, the conical portion is mainly heated. At this time, since the area of the peripheral side surface of the conical portion is larger than the area of the bottom wall portion, the heating region in the pan peripheral wall portion is large, and the conical portion is approximately 60 ° from the peripheral edge of the bottom wall portion. Since the shape of the conical portion is widened upward, an ascending flow of the heated water is continuously generated along the inner surface (inclined surface) of the peripheral side surface of the conical portion, and the peripheral edge of the bottom wall portion of the pot is formed. The presence of the non-heating area inside makes the water in the upper part descend well at the center of the pot, so that the water to be heated rises on the inner surface side of the peripheral wall inside the pot and descends at the center side Good convection occurs.

As a result, the temperature unevenness inside the pot is reduced, and the water in each part in the pot is almost uniformly at 100 ° C., and the α-form is promoted. Even if the heating power is reduced due to the function of the spill prevention function, most rice is kept at 100 ° C.
It is cooked in a state, and the gelatinization is further promoted. This makes it possible to obtain a good cook.

In the second means, since the conical portion is formed so as to be thicker than the other portions, the amount of heat transferred from the peripheral wall of the pot to the inside increases, and good convection is generated. More effective. In the third means, since the conical portion of the pot is configured to incline above the prescribed maximum water level line, it can more effectively contribute to the generation of favorable convection. In the fourth means, the heating means has a configuration having an electric heater, and the non-heating area is set to a range indicated by a diameter of substantially half or more of the diameter of the pan bottom wall portion.
Good convection can be generated by heating with the radiant heat of the electric heater.

In the fifth means, the heating means has an electric heater and a heat transfer portion having a shape substantially matching from the periphery of the pot peripheral wall portion to the outer surface of the conical portion, and the heat transfer portion has a conical shape. Since it is provided so as to be in surface contact with the outer surface of the conical portion, the heat of the electric heater can be directly transmitted to the conical portion, and the entire conical portion can be heated, and good convection It can further contribute to the occurrence.

In the sixth means, an auxiliary heating means is provided inside the heating means with a non-heating area, and the heating means and the auxiliary heating means are constituted by induction heating coils. Since the induction heating portion is provided at a portion corresponding to the auxiliary heating means, good convection can be generated by the induction heating, and the temperature can be made more uniform by providing the auxiliary heating means.
In the seventh means, since the input power of the heating means is set to be larger than the input power of the auxiliary heating means, the efficiency of temperature rise can be increased without hindering the generation of favorable convection. The temperature can be made uniform.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. In FIG. 2 showing the overall configuration, a rice cooker main body 11 made of resin is provided with a lid 12 at an upper portion thereof, which can be opened and closed by a hinge 13. Inside the rice cooker main body 11, an outer tank portion 15 that can accommodate the pot 14 is provided.
Are formed.

The pot 14 is formed by using a technique called melt forging, and comprises an induction heating section 16 made of a magnetic material such as a magnetic stainless steel or a steel plate and a heat conduction section 17 made of, for example, aluminum. ing. In this technique called molten metal forging, a magnetic material serving as an induction heating portion 16 is placed in a mold, and aluminum in a molten state serving as a heat conducting portion 17 is injected into the mold and pressurized to a predetermined shape. Is formed.

As shown in FIG. 1, in this pot 14,
Around the peripheral wall portion 14a, approximately 60 ° from the peripheral edge of the bottom wall portion 14b.
A conical portion 18 is formed which widens upward at an angle. The area of the peripheral side surface of the conical portion 18 is
It is configured to be larger than the area of b. Further, the conical portion 18 is formed so as to be thicker than the other portions (particularly, the thickness of the heat conducting portion 17 in the conical portion 18). Further, the conical portion 18 of the pot 14 has a configuration in which the angle gradually increases to the upper end of the pot 14 but is inclined.

An induction heating coil 19 serving as a heating means is provided on the outer bottom surface of the outer tank portion 15 at the bottom wall portion 14b of the pot 14 at the peripheral edge 14c.
The auxiliary heating coil 20 is provided inside the induction heating coil 19 and has an unheated area HK as an auxiliary heating means. The induction heating section 16 has a relationship corresponding to these heating coils 19 and 20. In this case, the input power of the induction heating coil 19 is set to 600 [W], and the input power of the auxiliary induction heating coil 20 is set to 400 [W].

As shown in FIG. 2, a ferrite 21 for forming a magnetic circuit is provided below each of the heating coils 19 and 20. When the lid 12 is closed, the top opening of the pan 14 is closed by an inner lid 12a provided inside the lid 12, and
A lid heater 22 for heating the inside of the pot 14 via the inner lid 12a is provided inside the lid portion 12, and a temperature sensor 24 constituting a part of the spill prevention means 23 is provided. .

In the center of the bottom of the outer tank 15, a pan 14
A temperature sensor 25 is provided so as to be in contact with the bottom surface of the pan 14 so as to detect the temperature of the pan 14. In addition, an inverter circuit section 26 for generating a high-frequency current and a cooling fan 27 are provided at the inner bottom of the rice cooker main body 11. A control circuit section 28 and an operation section 29 are provided on the front side in the rice cooker main body 11. The operation unit 29 is provided with operation switches and a display so as to be exposed outside the front surface of the rice cooker main body 11. A body heater 30 for heating and maintaining the temperature of the pot 14 is disposed inside the rice cooker main body 11 via a side wall of the outer tub 15.

FIG. 3 shows an electrical configuration. The control circuit section 28 includes a control circuit such as a microcomputer and stores a control program for cooking rice in advance. The control circuit section 28 is connected to receive an operation signal from the operation section 29, and outputs a control signal to the inverter circuit section 26 in accordance with the operation signal from the operation section 29 when the control program is executed. I have. The inverter circuit 26 generates a high-frequency current of a predetermined frequency in accordance with the given control signal.
Then, the heat is supplied to the auxiliary induction heating coil 20 to cause the pan 14 to perform the heat generation operation.

The output terminals of the temperature sensors 24 and 25 are connected to a control circuit section 28, and provide a temperature detection signal of the pan 14 to the control circuit section 28. Further, the cooling fan 27, the lid heater 22, and the body heater 30 are respectively provided in the control circuit unit 2
The power supply is controlled by a drive control signal given from the controller 8.

In the above configuration, the control circuit 28 executes the above-described control program to perform the rice cooking operation, and functions as the spillover prevention means 23 in cooperation with the temperature sensor 24. In other words, rice cooking driving
As shown in FIG. 4 (b), the soaking process, the rice cooking process,
It consists of an instruc- tion process. In the soaking process, water is soaked in the rice by controlling the temperature for a predetermined time, for example, around 45 to 55 ° C., and in the rice cooking process, the induction heating coil 19 is used.
The auxiliary induction heating coil 20 is fully energized, and the temperature sensor 24 detects that the heating has progressed and the water in the pot 14 evaporates and reaches 100 ° C. (time t2). (Time point t21) In order to prevent a spill, the power supply by the induction heating coil 19 and the auxiliary heating coil 20 is reduced to prevent the spill from the inside of the pot 14. Energize to keep it at a high temperature. When the temperature in the bottom of the pot 14 exceeds 100 ° C. due to the absence of water in the pan 14, when a so-called dry-up is detected based on the temperature sensor 19 (time t3), the process shifts to the spotting process.

Now, the induction heating section 1 is induced by the induction heating by the induction heating coil 19 and the auxiliary induction heating coil 20.
6 generates heat, and the pot 14 itself is heated. At this time, pan 1
In 4, good convection with little temperature unevenness can be obtained. That is, the induction heating coil 1 having a particularly large input
9 heats the conical portion 18. At this time, since the area of the peripheral side surface of the conical portion 18 is larger than the area of the bottom wall portion 14b, the heating area in the peripheral wall portion 14a of the pot 14 is large, and the conical portion 18 is 14
(b) Since the shape is such that the shape is widened at an angle of about 60 ° from the peripheral edge, the ascending flow of the heated water is continuously generated along the inner surface (inclined surface) of the conical portion 18, and 1
The presence of the non-heating region HK inside the periphery of the bottom wall portion 14b of the base 4 makes it possible for the water in the upper part to descend satisfactorily on the center side of the pot 14, so that the water to be heated is distributed around the peripheral wall portion 14a inside the pot 14. Good convection, such as rising on the inner surface and falling on the center, is generated. In particular, induction heating coil 1
9, the auxiliary induction heating coil 20 is provided with the non-heating area HK, so that the temperature at the center of the pot 14 where the temperature is slightly lowered and which tends to be increased can be appropriately increased.
The internal temperature can be made uniform.

Here, the convection forming action by the conical portion 18 will be described in detail. As shown in FIG. 6, the conical portion 18 forming an angle of 60 ° extends from the peripheral edge of the bottom wall portion 14b to the conical portion 18. When heated by the arranged induction heating coil 19 (when induced heat is generated), the water A near the inner surface of the conical portion 18 is heated to generate buoyancy Ff. However, the adhesive force Fn due to the inner surface of the conical portion 18 against the water A
Which acts in a direction perpendicular to the inner surface of the conical portion 18.

At this time, the conical portion 18 has an angle of 60 °.
The above-mentioned balance between the buoyancy and the adhesive force acts properly, and a movement vector Fv along the inner surface of the conical portion 18 is generated.
The water A heated in each part of the inner surface of 8 gradually moves along the inner surface. This movement phenomenon is observed at least up to the portion where the heating effect of the induction heating coil 19 is exerted.
A strong upward flow is formed along the inner surface of the conical portion 18, and a convection with a relatively high circulation speed and small temperature unevenness, that is, a convection suitable for rice cooking is obtained. In addition, if the angle is small, the heated water rises from the inner surface of the peripheral wall, and if the angle is too large, the bottom wall 14b is in a widened form and the number of flat portions increases,
Eventually, the heated water will rise directly above, and
In the peripheral wall portion 14a, the floating on the water is reduced, and good convection cannot be obtained.

On the other hand, as shown in FIG. 13, even if the peripheral wall 51a of the pot 51 is not conical but cylindrical, the induction heating coil 52 (only the right half is shown) is connected to the bottom wall 51b of the pot 51.
It is considered that the same convection as described above can be obtained if the convection is provided from to the peripheral wall portion 51a. However, in this case, it is difficult to obtain a stable convection as in the present embodiment. That is, it is considered that buoyancy acts on the heated water on the inner surface of the peripheral wall portion 51a of the pot 51 to cause an upward flow along the inner surface, but since the water is also heated on the bottom wall portion 51b, Water rises directly from the bottom wall portion 51b, which branches off at the upper layer portion as shown by the solid line in the figure, and disturbs the upward flow along the inner surface of the peripheral wall portion 51a. It is difficult to obtain such stable convection.

As shown in FIG. 14, the pot 61 has a configuration in which the corner from the bottom wall portion 61a to the peripheral wall portion 61b has a considerably large curvature, and the induction heating coil 62 (right side) is formed on the periphery of the bottom wall portion 61a. If only half of the convection is provided, convection (see the solid line) similar to the convection obtained in the present embodiment is obtained to some extent. Because the water is located below, the water in this part is hardly heated,
Therefore, the convection obtained in this embodiment is extremely small, and hardly contributes to eliminating temperature unevenness.

As an improvement measure of FIG. 14, FIG.
It is conceivable that the induction heating coil 62 is extended to the lowest point at the center of the bottom wall 61a of the pan 61 as described above. In this case, however, the induction heating coil 62 is required in a wide range, and the power density is small. The heating power is weak, and the formed convection is also very loose, which is unsuitable for rice cooking.

Table 2 shows that the pot 14 in this embodiment is
Shows the internal temperature of the upper PS near the peripheral wall.
1, the temperature of the middle part PS2 and the bottom part PS3, also the upper part PM1, the middle part PM2 and the bottom part PM of the middle part inside the pot 1
3 shows the temperature of the upper part PC1, the middle part PC2, and the bottom part PC3 in the central part of the inside of the pan 1, and in this case, the temperature of each part when the upper part PC1 of the central part inside the pan 14 is 90 ° C. , And the parentheses in the table indicate the temperature difference from this point PC1. In this case, the temperatures of the upper part PS1, the middle part PS2 and the bottom part PS3 near the peripheral wall,
Similarly, the difference between the temperatures of the upper part PM1, the middle part PM2, and the bottom part PM3 in the middle part of the inside of the pot 1 is 2.9 as shown in Expression 2.
It is considerably smaller than ° C. In addition, as shown in FIGS. 5A, 5B and 5C, the temperatures at the respective parts finally reach 100 ° C. without variation.

[0036]

[Table 2]

(Equation 2)

As can be seen from Table 2 above, the temperature of the peripheral wall in the upper and middle parts is higher than the temperature in the middle and central parts, which indicates that good convection is occurring. it can.

FIG. 4B shows how the rice surface position LR and the water level LW in the pot 14 change. As can be seen from the time point t21 in the figure, the water in each part has already reached 100 ° C. in a state where the water has not been completely absorbed by the rice, in other words, in a state where the water remains, and the rice is water boiling at 100 ° C. Will be cooked enough. The time point t21 is a time point at which the heating power is reduced by the function of the spillover prevention means 23. Most of the rice is cooked at 100 ° C., and the gelatinization is further promoted. Then, after the rice is cooked at a sufficiently high temperature, the water absorption of the rice is completed, and the rice is dried up (time t3), so that a good cook can be obtained.

In particular, according to this embodiment, the conical portion 18 is
Since it is formed so as to be thicker than the other portions, the amount of heat transferred from the peripheral wall portion 14a of the pot 14 to the inside increases, and the convection is more effectively generated.

According to the present embodiment, the input power of the induction heating coil 19 is set to be larger than the input power of the auxiliary induction heating coil 20. In addition, the efficiency of temperature rise can be increased and the temperature can be made uniform.

Further, since the pot 14 is configured to be inclined from the conical portion 18 to the upper end of the wall 14, the upward flow is effectively generated by the inclination, which can more effectively contribute to the generation of good convection. Note that this inclination may be from the conical portion 18 to a point above the specified maximum water level line KL. The specified maximum water level line KL is a water level corresponding to the maximum specified rice amount specified by the rice cooker.

FIG. 7 shows a second embodiment of the present invention. This embodiment differs from the first embodiment in the following points. That is, a heater 33 having a configuration in which the electric heater 31 is attached to the heat transfer plate 32 is provided as heating means. Inside the heater 33, there is an unheated area HK, which is at least half the diameter DT of the bottom wall 14b of the pot 14 (the diameter in this case is denoted by DH). Is set in the range indicated by.

Also in this embodiment, good convection is formed by the radiant heat of the heater 33 as shown by the broken line in FIG. In addition, HK is a non-heating area,
When the heater 33 is set to a range indicated by a diameter that is substantially less than half of the bottom wall portion 14b of the pot 14, in other words, when the heater 33 is provided to extend to the center of the bottom wall portion 1b, two points are shown in FIG. Convection as shown by a chain line may occur, which is disadvantageous for temperature uniformity. However, such a problem does not occur in the second embodiment.

FIG. 8 shows a third embodiment of the present invention. This embodiment differs from the first embodiment in the following points. That is, as the heating means, the electric heater 41 is used.
And the conical portion 1 from the peripheral edge 14c of the bottom wall portion 14b of the pan 14
8 is provided with a heater 43 having a configuration having a heat transfer portion 42 having a shape substantially matching the outer surface of the heater 8. The electric heater 41 is molded in the heat transfer section 42. The heat transfer section 42 is attached to the outer tub section 15 via a fixture 44, and when the pot 14 is stored in the rice cooker main body 11, the outer surface of the conical section 18 is attached to the heat transfer section 42. It is designed to be able to make surface contact. The heat of the electric heater 41 can be directly transmitted to the conical portion 18, and the entire conical portion 18 can be heated, thereby further contributing to good convection generation.

[0045]

As apparent from the above description, the present invention has the following effects. According to the invention of claim 1, the pot is placed on the peripheral wall of the pan at approximately 60 ° from the peripheral edge of the bottom wall.
And the area of the peripheral side surface of the conical part is larger than the area of the bottom wall part, and the heating means comprises a bottom wall of the pan. Since the non-heating area is provided inside the peripheral edge of the bottom wall of the pot, the heated water rises on the inner side of the peripheral wall inside the pot, descends at the center side, and circulates. It can generate good convection where the speed is relatively fast, can reduce the temperature unevenness inside the pot, and even if the heating power is reduced due to the function of preventing the spillage, most rice can be kept at 100 ° C. It can be cooked, so that the α-form can be promoted and a good cook can be obtained.

According to the second means, since the conical portion is formed so as to be thicker than the other portions, the amount of heat transfer from the peripheral wall of the pot to the inside is increased, so that a favorable condition is obtained. It is more effective by generating convection. According to the third means, since the conical portion of the pot is configured to be inclined above the prescribed maximum water level line, it can more effectively contribute to the generation of favorable convection.

According to the fourth means, the heating means has a structure having an electric heater, and the non-heating area is set in a range indicated by a diameter which is substantially half or more of the diameter of the bottom wall of the pot. Good convection can be generated by the heating by the radiant heat.

According to the fifth means, the heating means is configured to have an electric heater and a heat transfer portion having a shape substantially matching from the peripheral edge of the pot peripheral wall portion to the outer surface of the conical portion, and the heat transfer portion is provided. Since it is provided so as to be in surface contact with the outer surface of the conical portion, the heat of the electric heater can be directly transmitted to the conical portion, and the entire conical portion can be heated, and good convection can be achieved. It can further contribute to the occurrence.

According to the sixth means, an auxiliary heating means is provided inside the heating means with a non-heating area, and the heating means and the auxiliary heating means are constituted by induction heating coils.
Since the induction heating portion is provided at a portion corresponding to the heating means and the auxiliary heating means, good convection can be generated by induction heating, and the temperature can be made more uniform by providing the auxiliary heating means. be able to.

According to the seventh means, the input power of the heating means is set to be larger than the input power of the auxiliary heating means. High efficiency and uniform temperature can be achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a main part showing a first embodiment of the present invention.

FIG. 2 is an overall vertical side view.

FIG. 3 is a diagram showing an electrical configuration.

FIG. 4 is a diagram showing changes in rice surface position LR and water level LW, and changes in temperature.

FIG. 5 is a diagram showing a temperature change of each part in the pot.

FIG. 6 is a schematic longitudinal side view for explaining a state of occurrence of convection.

FIG. 7 is a diagram corresponding to FIG. 2, showing a second embodiment of the present invention;

FIG. 8 is a view corresponding to FIG. 2, showing a third embodiment of the present invention.

FIG. 9 is a diagram corresponding to FIG. 1 showing a conventional example.

FIG. 10 is a diagram corresponding to FIG. 5;

FIG. 11 is a diagram corresponding to FIG. 4;

FIG. 12 is a diagram corresponding to FIG. 2, showing a different conventional example.

FIG. 13 is a schematic longitudinal sectional side view for explaining a state of generation of convection in the reference example.

FIG. 14 is a schematic longitudinal sectional side view for explaining a state of convection generation in another reference example.

FIG. 15 is a schematic longitudinal side view for explaining a state of convection generation in still another reference example.

[Explanation of symbols]

11 is a rice cooker body, 14 is a pan, 16 is an induction heating section, 17
Denotes a heat conducting section, 18 denotes a conical section, 19 denotes an induction heating coil (heating means), 20 denotes an auxiliary induction heating coil (auxiliary heating means), and 23 denotes a spillover prevention means.

Continuation of the front page (56) References JP-A-3-212224 (JP, A) Japanese Utility Model Application No. Sho 62-318 (JP, U) Japanese Utility Model Application No. Sho 62-116391 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) A47J 27/00

Claims (7)

(57) [Claims] 1. A pan, a heating means for heating the pan, and a spill prevention means for preventing spillage from the pan, wherein the pan is provided on its peripheral wall at an angle of approximately 60 ° from the periphery of the bottom wall. A conical portion that expands upward at an angle, and that the area of the peripheral side surface of the conical portion is larger than the area of the bottom wall portion; A rice cooker which is arranged from a peripheral edge to the conical portion, and a non-heating area is provided inside a peripheral edge of a bottom wall of the pan. 2. The rice cooker according to claim 1, wherein the conical portion is formed so as to be thicker than other portions. 3. The rice cooker according to claim 1, wherein the conical portion of the pot is configured to incline above a specified maximum water level line. 4. The heating means includes an electric heater, and the non-heating area is set in a range indicated by a diameter of substantially half or more of a diameter of a bottom wall of the pot. The described rice cooker. 5. The heating means includes an electric heater and a heat transfer portion having a shape substantially matching from the periphery of the pot bottom wall to the outer surface of the conical portion, and the heat transfer portion is formed of a conical portion. The rice cooker according to claim 1, wherein the rice cooker is provided so as to be in surface contact with an outer surface. 6. An auxiliary heating means is provided with a non-heating area inside the heating means, wherein the heating means and the auxiliary heating means comprise an induction heating coil, and a pot corresponds to the heating means and the auxiliary heating means. The rice cooker according to claim 1, wherein the rice cooker has a configuration in which an induction heating portion is provided at a portion where the rice is heated. 7. The rice cooker according to claim 6, wherein the input power of the heating means is set to be larger than the input power of the auxiliary heating means.