JP7050442B2 - Cooker - Google Patents

Description

The present invention relates to a cooking device.

Conventionally, a coating film layer made by blending PFA or PTFE and a filler more hydrophilic than PFA or PTFE is provided on the inner surface of the bottom wall of the container, and the mixing ratio of the filler in the coating film layer is 20% by mass. A heating container for cooking has been proposed in which the content is ~ 80% by mass and a part of the filler is exposed on the surface of the coating film layer (see, for example, Patent Document 1).

JP-A-2009-34378 (Claim 1)

In Patent Document 1, a filler that is more hydrophilic than PFA or PTFE is blended to provide a hydrophilic coating film layer, whereby the contact angle with water is reduced and bubbles are reduced. When small bubbles are generated, a plurality of fine convections are generated, the temperature inside the container is made uniform, and the food can be cooked evenly. Here, in Patent Document 1, the arrangement of the coating film layer is limited to the description that it is provided on the entire surface of the bottom wall or is provided on the bottom wall at intervals (for example, in a dot shape). The heat generation distribution of the container also affects the generation of air bubbles inside the container, but Patent Document 1 does not consider the heat generation distribution of the container.

The present invention has been made against the background of the above-mentioned problems, and provides a cooking device capable of improving the heat transfer efficiency to the object to be heated in the container.

The heating cooker according to the present invention includes a container having a bottom and a peripheral wall connected to the bottom, and a heating portion for heating the container, and the bottom is radially outward from the maximum heat generation point at the bottom. Only, a hydrophilic coating layer is provided, the contact angle of the coating layer with water is less than 70 °, and the bottom is only radially inside the maximum heat generation point at the bottom. , A convex portion protruding upward is provided .

According to the present invention, air bubbles generated during boiling can be separated from the bottom of the container starting from the hydrophilic coating film layer at the bottom of the container. As a result, the bubbles pass through the object to be heated, so that heat can be efficiently transferred to the object to be heated.

It is sectional drawing which shows typically an example of the structure of the rice cooker which concerns on Embodiment 1. FIG. It is a figure which shows roughly the relationship between the rice cooking process of the rice cooker which concerns on Embodiment 1, and the temperature of the object to be heated and the temperature of a container for cooking rice. It is sectional drawing of the container 5 which concerns on Embodiment 1. FIG. It is a figure explaining the maximum heating point 5X of the container 5 heated by one heating coil 3. It is a figure explaining the maximum heating point 5X of the container 5 heated by two heating coils. It is sectional drawing which explains the behavior of the bubble in the conventional container 500. It is sectional drawing which explains the state after cooking rice of the conventional container 500. It is sectional drawing which explains the behavior of the bubble | bubble in the container 5 which concerns on Embodiment 1. FIG. It is sectional drawing which explains the state after cooking rice of the container 5 which concerns on Embodiment 1. FIG. It is an enlarged sectional schematic diagram in the vicinity of the coating film layer 55 of the container 5 which concerns on Embodiment 1. FIG. It is sectional drawing of the container 5 which concerns on Embodiment 2. FIG. It is a schematic diagram which enlarged the part A of FIG. It is sectional drawing which explains the state after cooking rice of the container 5 which concerns on Embodiment 2. FIG. It is a figure explaining the structure of the container 5 which concerns on Embodiment 3. FIG. It is sectional drawing of the container 5 which concerns on Embodiment 4. FIG. It is sectional drawing which explains the state after cooking rice in the container 5 which concerns on Embodiment 4. FIG.

Hereinafter, embodiments when the heating cooker according to the present invention is applied to a household IH (induction heating) type rice cooker will be described with reference to the drawings. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention. In addition, the present invention includes all combinations of configurations that can be combined among the configurations shown in the following embodiments. Further, the rice cooker shown in the drawing shows an example of a device to which the heating cooker is applied, and the rice cooker shown in the drawing does not limit the device to which the present invention is applied. Further, in the following description, terms indicating directions (for example, "top", "bottom", "right", "left", "front", "rear", etc.) are appropriately used for ease of understanding. This is for illustration purposes only and these terms are not intended to limit the invention. Further, in each figure, those having the same reference numerals are the same or equivalent thereof, which are common to the whole text of the specification. In each drawing, the relative dimensional relationship or shape of each constituent member may differ from the actual one.

Embodiment 1.
FIG. 1 is a schematic cross-sectional view schematically showing an example of the configuration of the rice cooker 100 according to the first embodiment. Hereinafter, the rice cooker 100 will be described with reference to FIG. The rice cooker 100 cooks the heated object by heating the pot-shaped container 5 containing the heated object (rice 200 and water 201 in the present embodiment) with the heating coil 3. As shown in FIG. 1, the rice cooker 100 includes, for example, a main body 1 having a bottomed tubular appearance and a lid 10 attached to the main body 1 and opening and closing the upper opening of the main body 1.

The main body 1 is a container cover 2, a heating coil 3, a pot bottom temperature sensor 4, a hinge portion 6 that supports the lid 10 so as to be openable and closable, a time measuring means 7, and each portion and each device are driven and controlled to cook rice. It is provided with a control means 8 for executing the process.

The container cover 2 is formed in the shape of a bottomed cylinder, and the container 5 is detachably housed inside the container cover 2. A hole 2a into which the pot bottom temperature sensor 4 is inserted is provided in the center of the bottom of the container cover 2.

The heating coil 3 is a heating unit whose energization is controlled by the control means 8 to induce and heat the container 5. An electric heater such as a sheathed heater may be provided as the heating unit instead of the heating coil 3. The arrangement of the heating coil 3 is not limited to that shown in the drawing, and for example, the heating coil 3 may be provided along the side surface of the container 5 in addition to the vicinity of the bottom surface of the container 5.

The pot bottom temperature sensor 4 is composed of, for example, a thermistor, and detects the temperature of the container 5. The pot bottom temperature sensor 4 of the present embodiment is urged upward by an elastic means such as a spring, and comes into contact with the bottom surface of the container 5 housed in the container cover 2. Information about the temperature of the container 5 detected by the pot bottom temperature sensor 4 is output to the control means 8. The specific configuration of the pot bottom temperature sensor 4 is not limited to the thermistor, and in addition to the contact type temperature sensor that detects the temperature in contact with the container 5, for example, the temperature of the container 5 such as an infrared sensor is not detected in a non-contact manner. A contact temperature sensor may be adopted.

The container 5 is made of a material containing a magnetic material that generates heat by induction heating, and has a bottomed cylindrical shape with an open upper side. The hinge portion 6 is provided on one end side (left side of the paper surface in FIG. 1) of the upper portion of the main body 1 and supports the lid body 10 so as to be openable and closable.

The time measuring means 7 counts the elapsed time based on the instruction signal from the control means 8. The elapsed time counted by the time measuring means 7 is output to the control means 8. The control means 8 controls the high-frequency current energized in the heating coil 3 based on the outputs from the time measuring means 7, the pot bottom temperature sensor 4, the operation display unit 15 provided on the lid 10, and the internal temperature sensor 16. .. In addition, the control means 8 controls the overall operation of the rice cooker 100. The control means 8 is composed of hardware such as a circuit device that realizes the function, an arithmetic unit such as a microcomputer or a CPU (central processing unit), and software executed on the arithmetic unit.

The lid 10 has an outer lid 11 and an inner lid 12. The outer lid 11 constitutes the upper portion and the side portion of the lid body 10, and the inner lid 12 is detachably attached to the lower surface of the outer lid 11, that is, the surface facing the container 5. The inner lid 12 is attached to the surface of the outer lid 11 on the main body 1 side via the locking member 13. A ring-shaped lid packing 9 for ensuring airtightness with the container 5 is attached to the peripheral edge of the inner lid 12. Further, the inner lid 12 is provided with a first hole portion 12a into which the internal temperature sensor 16 is inserted, and the outer lid 11 is provided with an outer periphery of the internal temperature sensor 16 inserted into the first hole portion 12a of the inner lid 12. A packing 12b that closes the gap is attached.

The outer lid 11 is detachably provided with a cartridge 14 for discharging the steam generated in the container 5 to the outside of the main body 1. The cartridge 14 is formed with a steam inlet 14a and a steam outlet 14b, and a flow path through which steam passes is formed inside the cartridge 14. The inner lid 12 is formed with a second hole portion 12c that communicates with the steam inlet 14a of the cartridge 14. With the cartridge 14 attached to the outer lid 11, the steam in the container 5 flows into the cartridge 14 through the second hole portion 12c and the steam inlet 14a, and flows out from the steam outlet 14b to the outside.

The operation display unit 15 is provided on the upper surface of the outer lid 11. The operation display unit 15 receives the operation input from the user and displays the information on the operation input and the operating state of the rice cooker 100. Items that can be set for the operation display unit 15 include, for example, start and cancellation of rice cooking, rice cooking reservation, and rice cooking menu. Items displayed by the operation display unit 15 include, for example, the state of the rice cooker 100 during rice cooking or waiting for reservation, the contents of the set rice cooking menu, the scheduled time for cooking, the current time, the amount of rice to be cooked, and the like. Can be mentioned.

The internal temperature sensor 16 is a temperature detecting means for detecting the temperature inside the container 5, and is attached to the outer lid 11. The tip of the internal temperature sensor 16 is inserted into the first hole portion 12a of the inner lid 12, and detects the space temperature in the container 5. The internal temperature sensor 16 can be configured by, for example, a thermistor. Information about the temperature inside the container 5 detected by the internal temperature sensor 16 is output to the control means 8.

Next, the rice cooking process of the rice cooker 100 according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram schematically showing the relationship between the rice cooking process of the rice cooker according to the first embodiment, the temperature of the object to be heated, and the temperature of the rice cooking container. In the present embodiment, the temperature of the object to be heated, that is, the internal temperature of the container 5 is detected based on the detection value of the internal temperature sensor 16. Further, the temperature of the rice-cooking container, that is, the temperature of the container 5 is detected based on the detection value of the pot bottom temperature sensor 4.

As shown in FIG. 2, the rice cooking step includes a water absorption step, a temperature raising step, a boiling maintenance step, and a steaming step. The water absorption step is a step of promoting water absorption to the inside of the rice 200 in the container 5. The next temperature raising step is a step from the end of the water absorption step to the boiling of the water 201 in the container 5. When the water 201 in the container 5 boils, the control means 8 shifts to the next boiling maintenance step. In this boiling maintenance step, the temperature inside the container 5 is heated so as to maintain the boiling temperature, and the gelatinization of the starch of the rice 200 is promoted. The final steaming step is a step of steaming the rice 200 in the container 5 to promote gelatinization to the center of the rice grains and to make the distribution of water in the rice grains uniform. When the rice cooking process is completed, the process shifts to a heat insulating process of keeping the inside of the container 5 at a predetermined temperature.

Next, the configuration of the container 5 of the present embodiment will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view of the container 5 according to the first embodiment. As shown in FIG. 3, the container 5 has a bottomed cylindrical shape and has a bottom portion 51 constituting the bottom of the container 5. The bottom portion 51 includes a curved portion 52 having curved inner and outer surfaces, and a curved portion 52. A peripheral wall having a continuous side portion 53 is connected. The bottom 51 is circular in plan view. A flange portion 54 extending radially outward is provided at the upper end portion of the side portion 53. As the base material of the container 5, a material that generates heat by induction heating by a heating coil 3 that is a heating source, for example, a carbon material that is a magnetic material or a magnetic metal can also be used. In addition, as the base material of the container 5, a magnetic material can be used in combination with the outer surface of a non-magnetic material such as aluminum, an aluminum alloy, or non-magnetic stainless steel.

When a current flows through the heating coil 3, an eddy current is generated in the container 5 due to a change in the magnetic flux generated from the heating coil 3 and passing through the container 5. Joule heat is generated by this eddy current, and the container 5 generates heat. In the present embodiment, in the region of the bottom 51 of the container 5, the point where the heat generation amount of Joule heat becomes the maximum, that is, the point where the heat generation becomes the highest is set as the maximum heat generation point 5X.

The relationship between the arrangement of the heating coil 3 and the maximum heat generation point 5X of the container 5 will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram illustrating a maximum heat generation point 5X of the container 5 heated by one heating coil 3. FIG. 5 is a diagram illustrating a maximum heating point 5X of the container 5 heated by two heating coils. As shown in FIG. 4, when one ring-shaped heating coil 3 is provided on the bottom portion 51 of the container 5, the region directly above the heating coil 3, that is, the radial width of the heating coil 3 in a plan view. There is a maximum heat generation point 5X at any position in the region overlapping with. As shown in FIG. 5, when the heating coil 3 is composed of two coils, the maximum heating point 5X is located at any position in the middle of the two coils in the radial direction. The relationship between the heating coil 3 shown in FIGS. 4 and 5 and the maximum heating point 5X is an example, and the position of the maximum heating point 5X is determined according to the shape and output of the heating coil 3. Further, in the present embodiment, an example in which the heating coil 3 is used as the heating unit is shown, but even when another heating source such as an electric heater is used as the heating unit, the maximum heat generation point 5X exists.

As shown in FIG. 3, the bottom portion 51 is provided with a hydrophilic coating film layer 55. The region of the bottom 51 other than the coating film layer 55 is covered with a water-repellent material. Examples of the water-repellent material include fluororesins such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxy alkane), which are fluororesin paints. The coating film layer 55 is a region having a higher hydrophilicity than a region covered with a water-repellent material, that is, a region having a low contact angle with water. When PFA and PTFE are used as the water-repellent material, the contact angle thereof is 100 ° to 110 °. The contact angle of the hydrophilic coating film layer 55 with water is preferably less than 70 °.

The hydrophilic material constituting the coating film layer 55 contains a hydrophilic substance such as silica. In the present embodiment, the coating film layer 55 is composed of a coating film containing a hydrophilic substance applied to the surface of the container 5. The coating film layer 55 is arranged radially outside the maximum heat generation point 5X.

Next, the operation of the container 5 of the present embodiment will be described by taking as an example the case where rice is cooked using the container 5. Prior to the description, the operation when rice is cooked using the conventional container 500 will be described. FIG. 6 is a schematic cross-sectional view illustrating the behavior of air bubbles in the conventional container 500, and FIG. 7 is a schematic cross-sectional view illustrating the state of the conventional container 500 after cooking. In FIG. 6, in order to explain the behavior of the bubbles, the bubbles generated in the container 5 are conceptually shown by reference numeral 310, and the rice 200 is not shown. The container 500 has a water-repellent coating on the entire inner surface thereof, and does not have the coating film layer 55 as in the present embodiment.

When the container 500 is heated with the object to be heated in the container 500, as shown in FIG. 6, the generation of bubbles 310 starts from the latter half of the temperature raising step. The bubbles 310 are generated most from the maximum heat generation point 5X. Since the inner surface of the container 500 is water repellent, the adhesive force of the bubbles 310 to the inner surface of the container 500 is large. Therefore, the relatively small bubbles 310 generated in the bottom 51 do not have sufficient buoyancy to separate from the bottom 51. In this case, a part of the bubble 310 moves toward the curved portion 52 while adhering to the bottom 51 of the container 500, and in the process of movement, the bubble 310 is repeatedly combined with the other bubble 310 to become larger.

When the bubble 310 moves on the bottom portion 51 and reaches the curved portion 52, the bubble 310 rises from the curved portion 52 along the side portion 53 while adhering to the inner surface of the curved portion 52. Since the bubbles 310 rise along the curved portion 52 and the side portions 53 and do not pass through the rice 200, heat cannot be uniformly transferred to the entire rice 200, and uneven cooking occurs. Further, when the number of bubbles 310 rising along the curved portion 52 and the side portion 53 increases, the surface of the cooked rice 200 becomes a shape in which the side portion 53 side is raised, as shown in FIG. 7, and the appearance is delicious. It spoils the rice.

Next, the operation when rice is cooked using the container 5 of the present embodiment will be described. FIG. 8 is a schematic cross-sectional view illustrating the behavior of air bubbles in the container 5 according to the first embodiment, and FIG. 9 is a schematic cross-sectional view illustrating the state of the container 5 according to the first embodiment after cooking. In FIG. 8, in order to explain the behavior of the bubbles, the bubbles generated in the container 5 are conceptually shown by reference numeral 300, and the rice 200 is not shown.

When the container 5 is heated with the object to be heated in the container 5, the generation of bubbles 300 starts from the latter half of the temperature raising step as shown in FIG. The bubbles 300 are generated most from the maximum heat generation point 5X. A part of the generated bubbles 300 moves toward the curved portion 52 while adhering to the bottom portion 51 of the container 5, but when it reaches the hydrophilic coating film layer 55, it separates from the bottom portion 51 and rises. As a result, upward convection is formed in the container 5 starting from the hydrophilic coating film layer 55.

Since the bubbles 300 separated from the bottom 51 starting from the coating film layer 55 pass through the rice 200, heat can be efficiently transferred to the rice 200, and the rice can be cooked evenly. Further, in the conventional example, there are many bubbles rising along the curved portion 52 and the side portion 53, whereas in the present embodiment, the bubbles 300 pass through the rice 200. Therefore, as shown in FIG. 9, the surface of the cooked rice is suppressed from rising on the side 53 side, becomes a flat shape, and the appearance is improved. Further, the region covered with the hydrophilic coating film layer 55 is not the entire bottom portion 51 but a part of the region radially outside the maximum heat generation point 5X. As described above, according to the present embodiment, since the region of the coating film layer 55 is relatively small, it is possible to suppress the sticking of the object to be heated generated in the hydrophilic portion.

When the coating film layer 55 is arranged radially inside the maximum heat generation point 5X where the largest number of bubbles 300 are generated, the bubbles rising along the curved portion 52 and the side portion 53 increase, and the heat to the rice 200 is increased. The effect of promoting transmission and the effect of improving the shape of cooked rice cannot be obtained. Therefore, the coating film layer 55 is arranged radially outside the maximum heat generation point 5X.

Next, the reason why the bubbles separate from the bottom 51 when they reach the hydrophilic coating film layer 55 will be described with reference to FIG. FIG. 10 is an enlarged schematic cross-sectional view of the container 5 according to the first embodiment in the vicinity of the coating film layer 55. The bubbles adhere to the surface of the bottom 51 due to the surface tension acting between the bubbles and the container 5, and when the buoyancy of the bubbles becomes larger than the adhesive force, the bubbles leave the surface of the bottom 51 and separate upward. The lower the contact angle between the surface of the bottom 51 and the bubble, the smaller the surface tension acting between the bubble and the surface of the bottom 51, so that the bubble can be separated, that is, the small bubble can be separated with a small buoyancy.

In FIG. 10, D1 indicates the diameter of the minimum bubble 301 having the buoyancy required to separate from the bottom 51 on the water-repellent region other than the coating film layer 55 in the bottom 51. The diameter of the smallest bubble 302 having the buoyancy required for detachment on the hydrophilic coating film layer 55 is indicated by D2. D1 and D2 have a relationship of D1> D2. Among the bubbles generated radially inside the coating film layer 55, those having a diameter less than D1 cannot be separated from the bottom 51, the bubbles repeatedly coalesce and move, and a part of the bubbles become the curved portion 52. Move towards. If the diameter of the bubbles arriving at the coating film layer 55 is D2 or more, the bubbles have the buoyancy required to separate from the bottom 51 and can be separated from the bottom 51. That is, when the bubbles having a diameter of D2 or more reach the coating film layer 55, they are separated from the bottom portion 51.

The smaller the diameter D2 of the bubbles detached from the coating film layer 55, the larger the amount of bubbles detached upward on the coating film layer 55. Therefore, it is preferable that the contact angle of the coating film layer 55 is small, but in a general IH type cooking cooker, if the contact angle of the coating film layer 55 is less than 70 °, a sufficient bubble separation effect can be obtained. Can be done.

In the present embodiment in which the container 5 is applied to a rice cooker, the width Y of the coating film layer 55 in the radial direction of the bottom portion 51 is preferably less than 1 cm. Since the coating film layer 55 is hydrophilic, sticking of cooked food (for example, rice or rice cake) is likely to occur, but by making the width Y of the coating film layer 55 smaller than 1 cm, which is equivalent to the major axis of rice grains. , It is possible to suppress the sticking of rice grains to the coating film layer 55.

The shape of the coating film layer 55 in a plan view is preferably a ring shape centered on the center of the bottom portion 51. By forming the ring shape, all the bubbles generated radially inside the coating film layer 55 and heading toward the side portion 53 come into contact with the coating film layer 55, so that more bubbles are separated from the bottom portion 51. be able to.

Embodiment 2.
The container 5 according to the second embodiment is provided with a convex portion 56 in a region radially inside the coating film layer 55 of the bottom portion 51, and other configurations are the same as those of the first embodiment. In this embodiment, the differences from the first embodiment will be mainly described.

FIG. 11 is a schematic cross-sectional view of the container 5 according to the second embodiment. FIG. 12 is an enlarged schematic view of a portion A in FIG. FIG. 13 is a schematic cross-sectional view illustrating a state of the container 5 according to the second embodiment after cooking rice. In FIG. 11, in order to explain the behavior of the bubbles, the bubbles generated in the container 5 are conceptually shown by reference numerals 300 and 303, and the rice 200 is not shown.

As shown in FIG. 11, a convex portion 56 projecting upward is provided at a position centered on the center of the bottom portion 51 of the container 5. As shown in FIG. 12, the vertical cross-sectional shape of the convex portion 56 is trapezoidal, and the convex portion 56 has an inclined surface 56a and an upper surface 56b. The convex portion 56 has a truncated cone shape as a whole. The surface of the convex portion 56 is covered with a water-repellent material.

As shown in FIG. 11, when the container 5 is heated with the object to be heated in the container 5, a part of the bubbles generated radially inside the coating film layer 55 moves toward the center of the bottom portion 51. Then, it moves toward the center and upward along the inclined surface 56a. Therefore, in the container 5 of the present embodiment, in addition to the upward convection starting from the coating film layer 55, convection toward the center of the water 201 in the container 5 is generated along the inclined surface 56a. Since the bubbles 300 separated from the bottom 51 starting from the coating film layer 55 and the inclined surface 56a pass through the rice 200, heat can be efficiently transferred to the rice 200 and the rice can be cooked evenly.

The upward convection starting from the coating film layer 55 suppresses the swelling of the rice on the side portion 53 side of the container 5, and the convection toward the center along the inclined surface 56a raises the central portion of the rice. Therefore, as shown in FIG. 13, the surface of the cooked rice cooked using the container 5 of the present embodiment has a fluffy mountain shape, and the deliciousness of the appearance can be further improved.

The convex portion 56 may not be provided with the upper surface 56b, but in that case, the bubbles 303 rising along the inclined surface 56a are concentrated at one point in the center of the bottom portion 51. Then, excessively strong convection may occur in the center, and the concentration of the rice cooking liquid in the center may cause the rice in the central portion to become excessively moist, resulting in deterioration of the taste. Therefore, it is preferable to provide the upper surface 56b. More preferably, the diameter of the upper surface 56b is 4 cm or more.

Embodiment 3.
The container 5 according to the third embodiment is provided with a convex portion 56 in a region radially inside the coating film layer 55 of the bottom portion 51, and other configurations are the same as those of the first embodiment. In this embodiment, the differences from the first embodiment will be mainly described.

FIG. 14 is a diagram illustrating the structure of the container 5 according to the third embodiment. 14A is a schematic cross-sectional view of the container 5, and FIG. 14B is a plan view of the container 5. In FIG. 14, in order to explain the behavior of the bubbles, the bubbles generated in the container 5 are conceptually shown by reference numerals 300 and 304, and the rice 200 is not shown.

As shown in FIG. 14, a second coating film layer 57 is provided in a region radially inside the coating film layer 55 of the bottom portion 51. The second coating film layer 57 is hydrophilic like the coating film layer 55. As shown in FIG. 14B, the shape of the second coating film layer 57 in a plan view is preferably a ring shape centered on the center of the bottom portion 51. The second coating film layer 57 has a ring shape having a smaller diameter than the coating film layer 55.

When heated with the object to be heated in the container 5, some of the bubbles generated radially inside the coating film layer 55 move toward the center of the bottom portion 51. When the bubbles 304 that have moved toward the center reach the hydrophilic second coating film layer 57, they separate from the bottom 51 and rise. As a result, upward convection is formed near the center of the container 5 starting from the hydrophilic second coating film layer 57. Therefore, in the container 5 of the present embodiment, in addition to the upward convection starting from the coating film layer 55, the upward convection is formed starting from the second coating film layer 57. Since the bubbles 300 and 304 separated from the bottom 51 starting from the coating film layer 55 and the second coating film layer 57 pass through the rice 200, heat can be efficiently transferred to the rice 200, and the rice is cooked evenly. can.

The container 5 of the third embodiment can generate the same bubble behavior as that of the second embodiment in the container 5. According to the third embodiment, since the coating film layer 55 and the second coating film layer 57 can be formed at the same time or in the same process, there is an advantage that the manufacturing process is not complicated as compared with the second embodiment.

Further, by forming the second coating film layer 57 in a ring shape in a plan view, bubbles generated radially inside the coating film layer 55 and moving in the central direction come into contact with the second coating film layer 57. , More bubbles can be removed from the bottom 51.

The convex portion 56 of the second embodiment and the second coating film layer 57 of the third embodiment can also be combined. That is, the convex portion 56 can be provided radially inside the maximum heat generation point 5X of the container 5, and the second coating film layer 57 can be provided further radially inside or radially outside the convex portion 56. By doing so, it is possible to increase the number of places where bubbles are separated from the bottom portion 51, so that convection of the object to be heated can be further promoted.

Embodiment 4.
The container 5 according to the fourth embodiment is provided with a convex portion 58 instead of the coating film layer 55 in the first to third embodiments, and other configurations are the same as those of the first embodiment. In this embodiment, the differences from the first embodiment will be mainly described.

FIG. 15 is a schematic cross-sectional view of the container 5 according to the fourth embodiment. FIG. 16 is a schematic cross-sectional view illustrating a state after cooking rice in the container 5 according to the fourth embodiment. In FIG. 15, in order to explain the behavior of the bubbles, the bubbles generated in the container 5 are conceptually shown by reference numeral 305, and the rice 200 is not shown.

The bottom portion 51 is provided with a convex portion 58 radially outside the maximum heat generation point 5X. In the present embodiment, the convex portion 58 is provided on the radial outer side of the heating coil 3 provided so as to face the bottom portion 51. The planar shape of the convex portion 58 is preferably a ring shape. The surface shape of the vertical cross section of the convex portion 58 is preferably a curved surface as shown in FIG. 15, but may have some corners. The surface of the convex portion 58 is covered with a water repellent material like the other surfaces of the bottom portion 51.

When heated with the object to be heated in the container 5, a part of the generated bubbles 505 moves toward the curved portion 52 and the side portion 53 while adhering to the bottom portion 51 of the container 5. Then, when the bubble 505 reaches the convex portion 58, it rises along the surface of the convex portion 58 and separates from the convex portion 58. As a result, a convection that flows upward from the convex portion 58 is formed. Since the bubble 305 separated from the bottom 51 starting from the convex portion 58 passes through the rice 200, heat can be efficiently transferred to the rice 200, and the rice can be cooked evenly. In this embodiment, the bubbles 305 pass through the rice 200. Therefore, as shown in FIG. 16, the surface of the cooked rice is suppressed from rising on the side 53 side, becomes a flat shape, and the appearance is improved. Further, since the entire bottom portion 51 is covered with the water-repellent material, the sticking of the rice can be further suppressed.

In the first to fourth embodiments, the container 5 is applied to the rice cooker 100, which is a cooker dedicated to cooking rice, but the container 5 is not limited to the one dedicated to cooking rice, and the container 5 can be heated. The container 5 of the present embodiment can be applied to the rice cooker.

1 main body, 2 container cover, 2a hole, 3 heating coil, 4 pot bottom temperature sensor, 5 container, 5X maximum heat generation point, 6 hinge part, 7 hour measuring means, 8 control means, 9 lid packing, 10 lid, 11 Outer lid, 12 inner lid, 12a 1st hole, 12b packing, 12c 2nd hole, 13 locking material, 14 cartridge, 14a steam inlet, 14b steam outlet, 15 operation display, 16 internal temperature sensor, 51 bottom, 52 curved part, 53 side part, 54 flange part, 55 coating layer, 56 convex part, 56a inclined surface, 56b top surface, 57 second coating layer, 58 convex part, 100 rice cooker, 200 rice, 201 Water, 300-305, 310 bubbles, 500 containers.

Claims (3)

A container having a bottom and a peripheral wall connected to the bottom,
A heating unit for heating the container is provided.
The bottom portion is provided with a hydrophilic coating film layer only radially outside the maximum heat generation point at the bottom portion.
The contact angle of the coating film layer with water is less than 70 ° .
The cooking apparatus is characterized in that the bottom portion is provided with a convex portion protruding upward only radially inward from the maximum heat generation point at the bottom portion . The cooking device according to claim 1, wherein the coating film layer has a ring shape in a plan view. The cooking apparatus according to claim 1 or 2 , wherein the radial width of the coating film layer is less than 1 cm.

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