JP2018114207A - Cooking container, heat cooker, and method for manufacturing cooking container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooking container that increases a coefficient of heat transfer to an object to be heated and reduces uneven heating, and to provide a heat cooker and a method for manufacturing a cooking container.SOLUTION: In a cooking container 5 having a bottom part 5a and a side part 5c, a recess part 50 is formed at a top face of the bottom part, a first layer having hydrophilic property is formed at a surface of the recess part and a second layer having water-repellent property is formed in a region at the top face of the bottom part, where the recess part is not formed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a cooking container that accommodates an object to be heated, a heating cooker including the cooking container, and a method for manufacturing the cooking container.

  Inside a heating cooker such as a rice cooker or an electric water heater, a container for storing a heated object such as water and rice is provided. Conventionally, it is known to perform fluorine processing for preventing evaporation residue from adhering to the inner surface of a container. Moreover, in patent document 1, it is proposed to perform fluorine processing on the inner surface of the container of the electric water heater and to disperse the hydrophilic treatment agent thereon. By providing the hydrophilic treatment agent on the inner surface of the container, bubbles generated when water in the container boils are reduced. Therefore, the heat transfer from the container to the water is prevented from being hindered by the bubbles, and the heat transfer rate to the water is improved. Moreover, in patent document 1, the water temperature is indirectly detected by measuring the temperature of a container. In this case, by improving the heat transfer rate from the container to the water, the difference between the container temperature and the water temperature is reduced, and the temperature corresponding to the water temperature can be detected. As a result, temperature management can be performed appropriately, and overheating of only the container can be suppressed.

Japanese Patent Application Laid-Open No. 07-059657

  Here, in patent document 1, the hydrophilic processing surface by a hydrophilic processing agent is formed in the same position as a fluorine processing surface, or a position higher than a fluorine processing surface. When the hydrophilic treatment surface is formed on the same surface as the fluorine processed surface, fine bubbles generated on the hydrophilic treatment surface are absorbed by large bubbles generated on the fluorine processed surface. In addition, when the hydrophilic treatment surface is formed at a position higher than the fluorine-treated surface, the hydrophilic treatment surface has a lower temperature than the fluorine-treated surface, so that boiling bubbles are less likely to be generated from the hydrophilic treatment surface. Therefore, in any case, the convection in the container is formed mainly by large bubbles generated from the fluorine processing surface.

  Since the large bubbles generated from the fluorine-processed surface have a large adhesion force to the container, they move toward the side of the container while adhering to the inner surface of the container, and repeat the coalescence with other bubbles in the middle. And the bubble which became large by coalescence rises along the side part of a container. Thus, in the container, when air bubbles generated from the fluorine processing surface are mainly used, the air bubbles rising along the side portions increase, and the air bubbles passing through the object to be heated are reduced. In particular, when heating an object to be heated other than water, such as rice cooking, the number of bubbles passing through the object to be heated is reduced, so that the heat transfer rate to the object to be heated is reduced and uneven heating occurs. End up.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a cooking container, a heating cooker, and a method for manufacturing the cooking container that realizes an improvement in heat transfer coefficient to a heated object and a reduction in heating unevenness. .

  The cooking container according to the present invention is a cooking container having a bottom portion and a side portion, and a concave portion is formed on the top surface of the bottom portion, and a hydrophilic first layer is formed on the surface of the concave portion, and the top surface of the bottom portion. A second layer having water repellency is formed in a region where no recess is formed.

  Moreover, the manufacturing method of the cooking container which concerns on this invention is a manufacturing method of the cooking container which has a bottom part and a side part, Comprising: The process of forming a recessed part in the upper surface of a bottom part, and the 1st layer which has hydrophilicity on the surface of a recessed part And a step of forming a second layer having water repellency in a region where the concave portion on the upper surface of the bottom portion is not formed.

  According to the cooking container of the present invention, the first layer having hydrophilicity is formed in the concave portion provided on the upper surface of the bottom portion, and the second layer having water repellency is formed in the region where the concave portion is not formed on the upper surface of the bottom portion. Thus, it is possible to generate a violent upward flow starting from the recess during heating. Thereby, bubbles passing through the object to be heated can be increased, and as a result, an improvement in the heat transfer rate to the object to be heated and a reduction in unevenness of heating can be realized.

It is a cross-sectional schematic diagram which shows schematically an example of a structure of the rice cooker in Embodiment 1. FIG. It is a figure which shows the relationship between the rice cooking process of the rice cooker in Embodiment 1, and to-be-heated material temperature and cooking container temperature. It is a figure explaining the shape of the cooking container in Embodiment 1. FIG. 3 is an enlarged cross-sectional view of the bottom of the cooking container in Embodiment 1. FIG. It is a figure explaining the contact angle of a 1st layer and water. It is a figure explaining the contact angle of a 2nd layer and water. It is a figure explaining the manufacturing method of the cooking container in Embodiment 1. FIG. It is a figure explaining the manufacturing method of the cooking container in Embodiment 1. FIG. It is a figure explaining the manufacturing method of the cooking container in Embodiment 1. FIG. It is a cross-sectional schematic diagram of the cooking container in the rice cooking process in a prior art example. It is a cross-sectional schematic diagram of the cooking container after completion | finish of the rice cooking process in a prior art example. It is a cross-sectional schematic diagram of the cooking container in the rice cooking process in Embodiment 1. FIG. It is a cross-sectional schematic diagram of the cooking container in the rice cooking process in Embodiment 1. FIG. It is a cross-sectional schematic diagram of the cooking container in the rice cooking process in Embodiment 1. FIG. It is a cross-sectional schematic diagram of the cooking container after completion | finish of the rice cooking process in Embodiment 1. FIG. It is a figure explaining the behavior of the bubble in the cooking container of comparative example 1. It is a figure explaining the behavior of the bubble in the cooking container of comparative example 2. It is a figure explaining the behavior of the bubble in the cooking container of comparative example 3. It is a figure explaining the shape of the cooking container in Embodiment 2. FIG. It is a top view of the cooking container in a modification. It is a figure explaining the manufacturing method of the cooking container in the modification 1. FIG. It is a figure explaining the manufacturing method of the cooking container in the modification 1. FIG. It is a figure explaining the manufacturing method of the cooking container in the modification 1. FIG. It is a figure explaining the manufacturing method of the cooking container in the modification 2. It is a figure explaining the manufacturing method of the cooking container in the modification 2. It is a figure explaining the manufacturing method of the cooking container in the modification 2.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a cooking container according to the present invention is applied to a domestic IH (induction heating) rice cooker will be described with reference to the drawings. In addition, this invention is not limited by the form of this drawing. Moreover, in the following drawings, the relationship of the size of each component may be different from the actual one.

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

  The main body 1 is a rice cooker that drives and controls the container cover 2, the heating coil 3, the pan bottom temperature sensor 4, the hinge portion 6 that supports the lid body 10 so as to be freely opened and closed, the time measuring means 7, and each portion and each device. And a control means 8 for executing the process.

  The container cover 2 is formed in a bottomed cylindrical shape, and the cooking container 5 is detachably accommodated therein. In the center of the bottom of the container cover 2, a hole 2a into which the pan bottom temperature sensor 4 is inserted is provided.

  The heating coil 3 is a heating unit that is energized and controlled by the control means 8 and induction-heats the cooking vessel 5. In addition, you may provide electric heaters, such as a sheathed heater, instead of the heating coil 3 as a heating part. The arrangement of the heating coil 3 is not limited to that shown in the figure. For example, the heating coil 3 may be provided along the side surface of the cooking container 5 in addition to the vicinity of the bottom surface of the cooking container 5.

  The pan bottom temperature sensor 4 is composed of, for example, a thermistor, and detects the temperature of the cooking vessel 5. The pan bottom temperature sensor 4 of the present embodiment is biased upward by an elastic means such as a spring and contacts the bottom surface of the cooking container 5 accommodated in the container cover 2. Information regarding the temperature of the cooking container 5 detected by the pan bottom temperature sensor 4 is output to the control means 8. In addition, the specific structure of the pan bottom temperature sensor 4 is not limited to the thermistor. In addition to the contact-type temperature sensor that detects the temperature by contacting the cooking container 5, the temperature of the cooking container 5 such as an infrared sensor is detected without contact. A non-contact temperature sensor may be employed.

  The cooking vessel 5 is made of a material including a magnetic body that generates heat by induction heating, and has a bottomed cylindrical shape with an upper side opened. A flange portion 5 d is formed on the outer periphery of the upper end portion of the cooking container 5. The details of the cooking container 5 will be described later. The hinge portion 6 is provided on one end side (the left side in FIG. 1) of the upper portion of the main body 1 and supports the lid body 10 so that it can be opened and closed.

  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 supplied to the heating coil 3 based on the output from the pan bottom temperature sensor 4, the operation display unit 15 provided in the lid body 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 configured by hardware such as a circuit device that realizes the function, or an arithmetic device such as a microcomputer or a CPU (central processing unit), and software executed thereon.

  The lid 10 has an outer lid 11 and an inner lid 12. The outer lid 11 is provided with a cartridge 14 for discharging steam generated in the cooking container 5 to the outside of the main body 1, and an operation display section 15 is provided on the upper surface of the outer lid 11. The cartridge 14 is provided with a steam port (inflow side) 12b and a steam port (discharge side) 12c. The outer lid 11 constitutes an upper portion and a side portion of the lid body 10, and an inner lid 12 is detachably attached to a lower surface (a surface facing the cooking container 5) of the outer lid 11. The inner lid 12 is attached to the surface of the outer lid 11 on the main body 1 side via a locking member 13. A lid packing 9 that secures hermeticity with the flange portion 5 d of the cooking vessel 5 is attached to the peripheral portion of the inner lid 12. Further, the inner lid 12 is provided with a hole 12a for inserting the internal temperature sensor 16, and the outer lid 11 is provided with a packing for closing a gap on the outer periphery of the internal temperature sensor 16 inserted into the hole 12a of the inner lid 12. 11a is attached.

  The operation display unit 15 is provided on the upper surface of the outer lid 11. The operation display part 15 receives the operation input from a user, and displays the information regarding an operation input, and the operation state of the rice cooker 100. FIG. 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 cooking or reservation standby, the contents of the set rice cooking menu, the scheduled cooking time, the current time, the amount of rice to be cooked, etc. Is mentioned.

  The internal temperature sensor 16 is temperature detection means for detecting the temperature inside the cooking container 5 and is attached to the outer lid 11. The tip of the internal temperature sensor 16 is inserted into the hole 12 a of the inner lid 12 and detects the space temperature in the cooking container 5. The internal temperature sensor 16 can be composed of, for example, a thermistor. Information regarding the temperature in the cooking 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 in this Embodiment is demonstrated with reference to FIG. FIG. 2 is a diagram schematically showing the relationship between the rice cooking process of the rice cooker, the heated object temperature, and the cooking container temperature in the present embodiment. In the present embodiment, the temperature of the object to be heated, that is, the internal temperature of the cooking vessel 5 is detected based on the detection value of the internal temperature sensor 16. Further, the cooking container temperature, that is, the temperature of the cooking container 5 is detected based on the detection value of the pan bottom temperature sensor 4.

  As shown in FIG. 2, the rice cooking process includes a water absorption process, a temperature raising process, a boiling maintenance process, and a steaming process. The water absorption step is a step for promoting water absorption up to the inside of the rice 200 in the cooking container 5. The next temperature raising step is a step from the end of the water absorption step until the water 201 in the cooking vessel 5 boils. When the water 201 in the cooking vessel 5 boils, the control means 8 proceeds to the next boiling maintenance step. In this boiling maintenance process, it heats so that the temperature in the cooking container 5 may maintain a boiling temperature, and gelatinization of the starch of the rice 200 is accelerated | stimulated. The last steaming process is a process in which gelatinization proceeds to the center of the rice grain by steaming the rice 200 in the cooking vessel 5 and the moisture distribution in the rice grain is made uniform.

  Next, the cooking container 5 in this Embodiment is demonstrated with reference to FIG. 3 and FIG. FIG. 3 is a diagram illustrating the shape of the cooking container 5 in the present embodiment. FIG. 3 includes a cross-sectional view and a top view of the cooking vessel 5. As shown in FIG. 3, the cooking vessel 5 has a bottomed cylindrical shape including a bottom portion 5a, a curved portion 5b, a side portion 5c, and a flange portion 5d.

  Moreover, the some recessed part 50 is formed in the upper surface of the bottom part 5a of the cooking container 5 in this Embodiment. The plurality of recesses 50 each have a circular shape when viewed from above, and are arranged at intervals on the same circle centered on the center of the bottom 5a. Among the plurality of recesses 50, the interval between adjacent recesses 50 is 1 cm or less. Each of the plurality of recesses 50 has a diameter of 1 cm or more and 2 cm or less, and each of the plurality of recesses 50 has a depth of 3 mm or less. Furthermore, the distance P between the outermost peripheral portion of the bottom portion 5a of the cooking container 5, that is, the boundary position between the bottom portion 5a and the curved portion 5b, and the end points on the curved portion 5b side of the plurality of concave portions 50 is 1 cm or less. The bottom surface of the recess 50 is a flat surface.

  FIG. 4 is an enlarged cross-sectional view of the bottom 5a of the cooking vessel 5 in the present embodiment. As shown in FIG. 4, the first layer 51 is formed on the surface of the recess 50, and the second layer 52 is formed on the upper surface of the bottom 5a where the recess 50 is not formed. Although not shown, the second layer 52 is formed not only in the region where the concave portion 50 is not formed on the upper surface of the bottom portion 5a but also on the inner surfaces of the curved portion 5b and the side portion 5c.

  Moreover, the contact angle α between the first layer 51 and the water 201 is smaller than the contact angle β between the second layer 52 and the water 201. 5A is a diagram for explaining a contact angle α between the first layer 51 and the water 201, and FIG. 5B is a diagram for explaining a contact angle β between the second layer 52 and the water 201. As shown in FIG. 5A, the first layer 51 is a hydrophilic layer having a contact angle α with the water 201 of 90 ° or less. Further, as shown in FIG. 5B, the second layer 52 is a layer having a water repellency having a contact angle with the water 201 of greater than 90 °.

  6A, 6B, and 6C are diagrams illustrating a method for manufacturing cooking container 5 in the present embodiment. In FIG. 6A, FIG. 6B, and FIG. 6C, the process of the inner surface in the cooking vessel 5 is demonstrated using the expanded sectional view of the bottom part 5a. First, as shown to FIG. 6A, the 2nd layer 52 is formed in the whole inner surface of the cooking vessel 5 including the upper surface of the bottom part 5a. The second layer 52 is formed by applying a fluororesin such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane). Next, as shown in FIG. 6B, the recess 50 is formed by a shaving process or the like. Finally, a first layer 51 is formed in the recess 50 as shown in FIG. 6C. The first layer 51 is formed by applying a material containing a powder UV (ultraviolet) body such as silica having hydrophilicity to the surface of the recess 50, fixing the powder body by a process such as baking, and exposing the powder body to the surface. Is done. Thus, the adhesiveness of the first layer 51 is improved by directly applying the first layer 51 to the inner surface of the cooking vessel 5.

  Then, before explaining the effect in the present embodiment, the behavior of the bubbles and the cooked shape when the rice cooking process is performed using the conventional cooking container 500 will be described with reference to FIGS. 7A and 7B. To do. FIG. 7A is a schematic cross-sectional view of cooking container 500 during the rice cooking process in the conventional example, and FIG. 7B is a schematic cross-sectional view of cooking container 500 after the completion of the rice cooking process in the conventional example. In FIG. 7A, illustration of the rice 200 is omitted in order to explain the behavior of bubbles. As shown in FIGS. 7A and 7B, the bottom portion 5a of the cooking container 500 of the conventional example is not provided with the recess 50. In addition, a water repellent coating similar to that of the second layer 52 is provided on the inner surface of the cooking vessel 500.

  First, when the rice 200 and the water 201 are put into the cooking container 500 and heated, the generation of bubbles starts for a while. Since the inner surface of the cooking container 500 has water repellency, the adhesion of bubbles to the inner surface of the cooking container 500 is increased. For this reason, at the initial stage of bubble generation, that is, at a stage where the bubble size is small, the buoyancy is not sufficient for the bubbles to escape upward. In this case, the bubbles move toward the side portion 5 c while adhering to the upper surface of the bottom portion 5 a of the cooking container 500. At this time, the bubbles repeatedly merge and become larger.

  As shown in FIG. 7A, when the bubble moves through the bottom 5a and reaches the curved portion 5b, the bubble rises from the curved portion 5b along the side portion 5c while adhering to the inner surface of the curved portion 5b. That is, as the contact angle of the water 201 on the inner surface of the cooking container 500 increases, the number of bubbles rising from the curved portion 5b along the side portion 5c while adhering to the inner surface increases. When the bubbles rise along the side portions 5c, the bubbles do not pass through the rice 200, so that heat cannot be uniformly transmitted to the entire rice 200, and cooking unevenness occurs. Moreover, when the bubble which raises along the side part 5c increases, as shown to FIG. 7B, the surface of the rice after cooking will be in the shape where the side part 5c side rose, and the deliciousness of appearance will be impaired.

  Next, the behavior of bubbles when the rice cooking process is performed using the cooking container 5 in the present embodiment and the cooked shape will be described with reference to FIGS. 8A to 8D. 8A, 8B and 8C are schematic cross-sectional views of cooking vessel 5 during the rice cooking process in the present embodiment. Moreover, FIG. 8D is a cross-sectional schematic diagram of the cooking container 5 after completion of the rice cooking process in the present embodiment. In FIG. 8A, FIG. 8B, and FIG. 8C, illustration of the rice 200 is omitted in order to explain the behavior of bubbles.

  First, when rice 200 and water 201 are put into the cooking container 5 and heated, as shown in FIG. 8A, a plurality of recesses 50 formed in the bottom 5a and regions other than the recesses 50 on the upper surface of the bottom 5a (that is, recesses). The generation of bubbles begins in the region where 50 is not formed. Here, a first layer 51 is formed in each recess 50. Since the first layer 51 is hydrophilic and has a small contact angle with the water 201, the adhesive force of bubbles to the surface of the recess 50 is small. For this reason, the bubbles generated in the recess 50 are separated upward immediately after the generation. As shown in FIG. 8A, the fine bubbles are continuously detached from the plurality of recesses 50, thereby generating an upward flow starting from the plurality of recesses 50.

  Further, in the initial stage shown in FIG. 8A, while the upward flow starting from the concave portion 50 is generated, the bubbles generated in the region other than the concave portion 50 remain attached to the upper surface of the bottom portion 5a, and the concave portion 50 rises. It is attracted by the flow and approaches the recess 50. Then, as shown in FIG. 8B, the bubbles reach the end of the recess 50 and remain at the end of the recess 50. The bubbles staying at the end of the recess 50 grow together with other bubbles, and after obtaining sufficient buoyancy, rises along the upward flow starting from the recess 50.

  An upward flow due to fine bubbles is generated in the recess 50, and large bubbles attracted by the upward flow around the recess 50 rise along the upward flow. As a result, as shown in FIG. 8C, the fine bubbles generated in the recess 50 and the large bubbles attracted to the recess 50 are combined in the process of rising. Thereby, a violent upward flow is generated starting from the recess 50.

  Thus, by generating an upward flow from the recess 50, the ratio of bubbles passing through the rice 200 increases, improving the heat transfer rate to the heated object, and cooking rice without uneven cooking. Can do. Moreover, since the ratio of the bubble rising along the side part 5c decreases, as shown in FIG. 8D, the side part 5c side does not rise, resulting in flat cooking. Thereby, the taste of appearance is also improved.

  In order to generate a violent upward flow starting from the recess 50, (1) the recess 50 is formed, and (2) a hydrophilic first layer 51 is formed in the recess 50. It is essential to form the second layer 52 having water repellency in this area. The reason will be described below.

  FIG. 9 is a diagram illustrating the behavior of bubbles in the cooking container 500A of Comparative Example 1. In the cooking container 500A of Comparative Example 1, a plurality of concave portions 50 are formed on the upper surface of the bottom portion 5a as in the present embodiment. However, the second layer 52 having water repellency is formed on the entire inner surface of the cooking container 500 </ b> A, that is, on both the surface of the recess 50 and the region other than the recess 50.

  As shown in FIG. 9, in the cooking container 500 </ b> A, the frequency of separation of bubbles generated from the recess 50 is small, and no upward flow is generated from the recess 50. This is because the bubble generation cycle consists of three steps: “bubble generation”, “growth by bubble coalescence”, and “bubble separation”. The larger the contact angle, the longer the time required for “growth by bubble coalescence”. This is because the frequency of bubble separation is reduced.

  FIG. 10 is a diagram illustrating the behavior of bubbles in the cooking container 500B of Comparative Example 2. The cooking container 500B of Comparative Example 2 includes a plurality of recesses 50 on the upper surface of the bottom 5a, as in the present embodiment. However, the hydrophilic first layer 51 is formed on the entire inner surface of the cooking container 500B, that is, on both the surface of the recess 50 and the region other than the recess 50.

  As shown in FIG. 10, in the cooking container 500 </ b> B, the fine bubbles generated from the regions other than the recesses 50 and the recesses 50 leave upward immediately after the generation. That is, in Comparative Example 2, the bubbles generated from the region other than the recess 50 are separated upward before reaching the recess 50. Therefore, bubbles generated from regions other than the recesses 50 do not merge with the bubbles generated from the recesses 50, and a violent upward flow as in the present embodiment does not occur.

  FIG. 11 is a diagram illustrating the behavior of bubbles in the cooking container 500C of Comparative Example 3. The cooking container 500C of Comparative Example 3 does not include the recess 50 on the upper surface of the bottom 5a. Moreover, the 2nd layer 52 is formed in the whole inner surface of the cooking container 500C, and the 1st layer 51 is formed on the 2nd layer 52 in the upper surface of the bottom part 5a. That is, in Comparative Example 3, the first layer 51 is formed at a higher position than the second layer 52.

  In general, bubbles generated by boiling are preferentially generated from a low position. Therefore, when the first layer 51 is formed at a position higher than the second layer 52, almost no bubbles are generated from the first layer 51. On the other hand, the bubbles generated from the second layer 52 move toward the side portion 5c while adhering to the upper surface of the bottom portion 5a of the cooking vessel 500C, as in the conventional example shown in FIG. 7A, and from the curved portion 5b to the side portion. It rises along 5c. Therefore, in the case of the comparative example 3, the ratio of the bubble which rises along the side part 5c becomes high.

  As described above, (1) the recess 50 is formed, and (2) the hydrophilic first layer 51 is formed in the recess 50, and the water repellent second layer 52 is formed in a region other than the recess 50. If both are not provided, it is not possible to generate a violent upward flow through the object to be heated. In the present embodiment, by providing both the configurations (1) and (2), it is possible to improve the heat transfer coefficient and reduce heating unevenness.

  In the present embodiment, the distance P between the outermost peripheral portion of the bottom portion 5a of the cooking container 5 and the end points on the curved portion 5b side of the plurality of concave portions 50 is 1 cm or less, and the concave portion 50 is near the outermost peripheral portion of the bottom portion 5a. Provided. Thereby, it is possible to collect the bubbles in the vicinity of the outermost peripheral portion that normally rises along the side portion 5c in the recess 50, and as a result, to reduce the proportion of bubbles that rise along the side portion 5c. Can do. Moreover, since the ratio of the bubble which passes the inside of the rice 200 increases by decreasing the number of the bubbles rising along the side part 5c, the heat transfer rate is improved, and the rice without cooking unevenness is cooked. Can do.

  Furthermore, when the diameter of the recess 50 is less than 1 cm, the amount of fine bubbles generated from the recess 50 is small, and an upward flow starting from the recess 50 does not occur. In addition, when the diameter of the concave portion 50 is larger than 2 cm, the upward flow due to the fine bubbles is generated from a plurality of locations in the concave portion 50, and since the distance between them is too far, they cannot be merged and the intense upward flow is not generated. . Therefore, as in the present embodiment, by setting the diameter of the recess 50 to 1 cm or more and 2 cm or less, it is possible to generate a violent upward flow that passes through the object to be heated.

  Moreover, by making the space | interval of the adjacent recessed part 50 into 1 cm or less, it can suppress that a bubble slips through the space | interval of the recessed part 50, and can absorb a bubble to the recessed part 50. FIG. Moreover, the short diameter of the rice grain after cooking is about 3 mm. Therefore, the depth of the recessed part 50 shall be 3 mm or less, and it can suppress that the rice 200 is clogged in the recessed part 50, and the mold release property from the cooking container 5 of rice after cooking and the cleaning property improve. Furthermore, the first layer 51 having hydrophilicity is formed in the recess 50, and the second layer 52 having water repellency is formed in the other region of the inner surface of the cooking container 5, so that the cooking container 5 for cooked rice can be used. The mold releasability and cleanability are further improved.

Embodiment 2. FIG.
Next, Embodiment 2 will be described with reference to FIG. The cooking container 5A in the second embodiment is different from the first embodiment in the shape of the recess, and the other configurations are the same as those in the first embodiment.

  FIG. 12 is a diagram illustrating the shape of cooking container 5A in the present embodiment. FIG. 12 includes a cross-sectional view and a top view of cooking vessel 5A. In the present embodiment, a series of recesses 50A is formed on the upper surface of bottom 5a of cooking vessel 5A. As shown in FIG. 12, the recess 50A is a ring-shaped groove centered on the center of the bottom 5a in a top view. Further, the first layer 51 is formed on the surface of the recess 50A, and the second layer 52 is formed on the region where the recess 50A is not formed on the upper surface of the bottom 5a, and on the inner surfaces of the curved portion 5b and the side portion 5c. . The first layer 51 and the second layer 52 are the same as those in the first embodiment, and the first layer 51 is a hydrophilic layer having a contact angle α with the water 201 of 90 ° or less. Reference numeral 52 denotes a layer having water repellency with a contact angle with the water 201 being larger than 90 °.

  The width of the recess 50A is not less than 1 cm and not more than 2 cm, and the depth of the recess 50A is not more than 3 mm. Furthermore, the distance P between the outermost peripheral portion of the bottom portion 5a of the cooking container 5, that is, the boundary position between the bottom portion 5a and the curved portion 5b, and the outer periphery of the concave portion 50A is 1 cm or less. Thereby, also in the present embodiment, the number of bubbles rising along the side portion 5c is reduced, and the number of bubbles passing through the heated object is increased, so that the heat transfer rate to the heated object is improved and cooked. You can cook rice with no unevenness.

  Further, in the first embodiment, since the plurality of recesses 50 are arranged at intervals, air bubbles generated on the center side of the bottom portion 5a from the recesses 50 pass between the recesses 50 and enter the side portions 5c. May rise along. On the other hand, by providing the concave portion 50A formed of a ring-shaped groove as in the present embodiment, it is possible to more reliably hold the bubbles generated at the center side of the bottom portion 5a than the concave portion 50A at the concave portion 50A. . The number of bubbles rising along the side portion 5c can be further reduced by separating the retained bubbles together with the fine bubbles generated from the recess 50A.

  In addition, when the recess 50A is a ring-shaped groove, there is a demerit that positions where the upward flow is generated are dispersed. About this point, by providing the some recessed part 50 like Embodiment 1, the generation | occurrence | production position of an upward flow can be fixed and a stronger upward flow can be generated.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. It is possible to deform to. Further, the present invention includes all combinations of configurations that can be combined among the configurations shown in the following embodiments. For example, although the said embodiment demonstrated the case where the cooking container 5 was applied to the rice cooker 100, it is not limited to this, Other cooking cookers utilized for cooking other than rice cooking, such as a stew, are also carried out. A cooking vessel 5 can be applied.

  Further, the top view shape of the concave portion 50 is not limited to a circular shape, and may be a shape having corner portions such as a star shape and a polygonal shape. When the concave portion 50 has a shape having a corner portion, a flow of bubbles moving from the corner portion of the concave portion 50 along the central portion is generated, so that the bubbles are concentrated in the central portion of the concave portion 50 and a stronger upward flow is generated. Can be generated. The shape of the recess 50A may be a groove having a corner instead of a ring-shaped groove. The recess 50 may be a ring-shaped groove, and a plurality of the recesses 50 may be provided in the same or concentric circles.

  Further, the number and arrangement of the recesses 50 are not limited to the above embodiment. FIG. 13 is a top view of a cooking vessel 5B in a modified example. As shown in FIG. 13, in this modification, the plurality of recesses 50 are formed on concentric circles centered on the center of the bottom 5a. In this case, since the concave portion 50 is uniformly formed in the bottom portion 5a of the cooking container 5B, cooking unevenness can be reduced more than when a plurality of the concave portions 50 are formed on one circle as in the first embodiment. it can.

  Moreover, the formation method of the 1st layer 51 and the 2nd layer 52 in the cooking container 5 is not limited to the method of Embodiment 1 shown to FIG. 6A-FIG. 6C. 14A, 14B, and 14C are diagrams illustrating a method for manufacturing the cooking container 5 in the first modification. In the first modification, first, as shown in FIG. 14A, the recess 50 is formed on the upper surface of the bottom 5 a of the cooking container 5. Next, as shown in FIG. 14B, the second layer 52 is formed on the entire inner surface of the cooking vessel 5 including the surface of the recess 50. As in the first embodiment, the second layer 52 is formed by applying a fluororesin such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane).

  Finally, as shown in FIG. 14C, the first layer 51 is formed on the surface of the recess 50. The first layer 51 is formed by performing plasma treatment or UV (ultraviolet) treatment only on the surface of the recess 50 to generate a hydrophilic functional group (such as an amino group or a hydroxy group) on the surface. Alternatively, a powder having hydrophilicity may be sprayed on the surface of the recess 50, and the powder may be fixed by a process such as baking to expose the powder on the surface. According to this modification, since the concave portion 50 is formed before the first layer 51 and the second layer 52 are formed, the concave portion 50 can be formed by press working, and productivity is improved.

  15A, FIG. 15B, and FIG. 15C are diagrams illustrating a method for manufacturing the cooking container 5 in the second modification. In the present modification, a primer layer 53 for improving the adhesion between the first layer 51 and the second layer 52 is provided. First, as shown to FIG. 15A, a primer is apply | coated to the whole inner surface of the cooking container 5, the primer layer 53 is formed, and the 2nd layer 52 is formed on it. As in the first embodiment, the second layer 52 is formed by applying a fluororesin such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane).

  Next, as shown in FIG. 15B, a recess 50 is formed by a shaving process or the like. Here, the shaving process is performed to such a depth that the surface of the primer layer 53 is exposed on the bottom surface of the recess 50. Finally, as shown in FIG. 15C, the first layer 51 is formed in the recess 50 where the surface of the primer layer 53 is exposed. The first layer 51 is formed by performing plasma treatment or UV (ultraviolet) treatment on the primer layer exposed on the bottom surface of the recess 50 to generate hydrophilic functional groups (amino group, hydroxy group, etc.) on the surface. The Alternatively, a hydrophilic powder may be sprayed on the bottom surface of the recess 50, and the powder may be fixed by a process such as firing to expose the powder on the surface. In this modification, since the first layer 51 is formed on the primer layer 53, the adhesion of the first layer 51 is further improved as compared with the case where the first layer 51 is formed directly on the cooking vessel 5.

  As another modification, a recess 50 is formed in the bottom 5 a of the cooking container 5, and the second layer 52 is formed on the entire inner surface of the cooking container 5 after masking the recess 50. Then, the first layer 51 may be formed in the recess 50 by removing the masking. Alternatively, the first layer 51 may be formed on the entire inner surface of the cooking container 5, and the second layer 52 may be formed in a region other than the recess 50. In this case, the second layer 52 is formed by roughening the region other than the recess 50.

  DESCRIPTION OF SYMBOLS 1 Main body, 2 Container cover, 2a, 12a Hole part, 3 Heating coil, 4 Pan bottom temperature sensor 5, 5A, 5B, 500, 500A, 500B, 500C Cooking container, 5a Bottom part, 5b Curved part, 5c Side part, 5d Flange part, 6 hinge part, 7 time measuring means, 8 control means, 9 lid packing, 10 lid body, 11 outer lid, 11a packing, 12 inner lid, 13 locking material, 14 cartridge, 15 operation display part, 16 inside Temperature sensor, 50, 50A recess, 51 1st layer, 52 2nd layer, 53 primer layer, 100 rice cooker, 200 rice, 201 water.

Claims (15)

A cooking vessel having a bottom and sides,
A recess is formed on the upper surface of the bottom,
A first layer having hydrophilicity is formed on the surface of the recess,
A cooking container, wherein a second layer having water repellency is formed in a region where the concave portion is not formed on the upper surface of the bottom portion.   The said recessed part consists of a several recessed part arrange | positioned on the same circle, The cooking container of Claim 1 characterized by the above-mentioned.   The said recessed part consists of a several recessed part arrange | positioned on a concentric circle, The cooking container of Claim 1 characterized by the above-mentioned.   4. The cooking container according to claim 2, wherein each of the plurality of recesses is circular, star-shaped or polygonal when viewed from above.   The cooking container according to any one of claims 2 to 4, wherein an interval between adjacent recesses among the plurality of recesses is 1 cm or less.   The cooking container according to claim 1, wherein the recess is a ring-shaped groove in a top view. Having a curved portion between the bottom and the side,
The cooking container according to any one of claims 1 to 6, wherein a distance between a boundary position between the bottom portion and the curved portion and an end point of the concave portion on the curved portion side is 1 cm or less.   The cooking container according to any one of claims 1 to 7, wherein a width of the recess is 1 cm or more and 2 cm or less.   The depth of the said recessed part is 3 mm or less, The cooking container as described in any one of Claims 1-8 characterized by the above-mentioned.   The cooking container according to any one of claims 1 to 9, wherein the second layer is formed on a surface of the recess, and the first layer is formed thereon.   The cooking container according to any one of claims 1 to 10, wherein a primer layer is formed under the first layer. A cooking container according to any one of claims 1 to 11,
A main body having an upper surface opened therein and containing the cooking container;
A lid that opens and closes an opening on the upper surface of the main body;
And a heating unit for heating the cooking container. A method for producing a cooking container having a bottom and a side,
Forming a recess on the upper surface of the bottom,
Forming a hydrophilic first layer on the surface of the recess;
Forming a second layer having water repellency in a region where the concave portion is not formed on the upper surface of the bottom portion.   The method according to claim 13, wherein after the second layer is formed on the top surface of the bottom portion, the step of forming the concave portion on the top surface of the bottom portion and the step of forming the first layer on the surface of the concave portion are performed. The manufacturing method of the cooking container as described. Further including a step of forming a primer layer on the top surface of the bottom portion to improve the adhesion between the first layer and the second layer;
Forming the second layer on the primer layer;
The method for manufacturing a cooking container according to claim 13 or 14, wherein the recess is formed so that the primer layer is exposed to the surface.

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