JP5822879B2 - rice cooker - Google Patents

Description

  The present invention relates to a rice cooker that cooks rice by changing the convection inside the inner pot depending on the shape of the inner pot.

  In recent years, rice cookers have been mainly of the electromagnetic induction heating type. As the material of the inner pot, a magnetic material that is induction-heated by an induction heating coil is used on the outside, and the heat from the magnetic material generated by induction heating is stored inside. Use a material with good thermal conductivity so that it can be evenly transmitted to the rice inside the kettle. It is common to heat the inner pot itself with high efficiency and high power consumption by electromagnetic induction by the induction heating coil provided facing the bottom of the inner pot, thereby obtaining strong convection inside the inner pot and cooking it. .

  On the other hand, the convection inside the inner pot rises along the outer periphery of the inner pot that is strongly heated, and convects downward from the center near the upper water surface. There was a problem that the central part became a dished dish. For this reason, compared with the outer peripheral part, the rice in the central part has a problem that the grains are small and hard.

  In this type of conventional rice cooker, as shown in Patent Document 1, the stainless steel outside the bottom of the pot for the induction heating cooker (inner pot) facing the induction heating coil is provided with unevenness of a maximum depth of 0.4 mm. Some have a small convection caused by changing the temperature distribution.

  Also, as shown in Patent Document 2, a conical portion of approximately 60 ° from the bottom surface is provided in order to promote convection from the outer peripheral portion of the pan (inner pot) to the upper portion, and the conical portion away from the induction heating coil conducts heat conduction. Some have been made thicker than others for better performance.

Japanese Patent No. 3475955 Japanese Patent Laid-Open No. 8-33562

  In the above-mentioned Patent Document 1, a small unevenness is provided in the inner pot, causing fine and complicated convection, so that the rice is heated uniformly, rising from the outer periphery of the inner pot and downward from the central portion. There is no change in the large convection heading, and the dish is cooked with a recessed central part, which does not solve the problem of the present invention.

  Moreover, in patent document 2, since the convection from an inner pot outer peripheral part becomes stronger, it becomes the cooking which an outer periphery rises more and a center part dents, and obtains the effect contrary to the subject solution of this invention.

  Therefore, in Patent Documents 1 and 2, convection is performed along the outer periphery of the inner hook. This is because convection is caused along the side wall of the inner pot where resistance to convection is low because cooking is difficult and convection is difficult when rice is sticky. For this reason, the cooking is such that the outer peripheral part of the inner pot rises and the central part is recessed. Compared with the outer periphery, the rice in the center has the problem that the grains are smaller and harder, and the cooked surface is visually invisible.

  In addition, it is possible to convection from the inner pot central part to the upper part by moving the heating coil to the central part of the inner pot bottom, so that the rice in the central part is not recessed, but the heating of the central part is always strong. On the other hand, there is a problem that the central part becomes too soft, the inner peripheral part of the inner hook is hard, and the grains become small.

  As rice cooks as rice cooks, the convection from the center has a large resistance to rising water, and the convection is difficult, so the rice in the vicinity of the bottom of the center becomes a bowl-like problem. It was.

The present invention has been made to solve the above-mentioned problems. In claim 1, the main body, an inner hook that is detachably provided inside the main body and uses iron on the outside of the base material, In the rice cooker provided with a substantially planar annular heating coil that is provided at a position facing the bottom surface of the pot and that inductively heats the inner pot, and an outer lid that closes the main body and the upper surface opening of the inner pot. a peripheral side face up below the water level containing the rice and water when cooking the rice beneath or al 1 Go flange portion on the side of the inner hook, the heating coil in the bottom of the kiln is opposite faces into an inner central portion, in which a thick portion formed by thermal spraying of iron provided in the iron portion of the substrate.

  According to the present invention, it is possible to obtain a uniform boiled rice with the same hardness and grain size.

It is sectional drawing of the rice cooker which concerns on one Example. It is sectional drawing of the same inner hook. A partial cross-sectional enlarged view is drawn. It is a figure which shows the convection state in the initial stage of boiling in the sectional view of the inner pot. It is a figure which shows the convection state of the latter stage of boiling in the sectional view of the same inner pot.

  An embodiment of the present invention will be described below with reference to FIGS.

  1 and 2, reference numeral 1 denotes a main body of a rice cooker. A protective frame 3 having an upper surface is provided inside the main body 1 of the rice cooker, and an inner pot 2 is detachably stored in the protective frame 3. Has been.

  The inner hook 2 has a cylindrical shape with a top opening and a diameter that decreases toward the bottom 2a. A flange portion 2b is provided on the entire circumference of the upper opening, and is placed on the upper frame 1a of the main body 1 so that the position of the inner hook 2 is fixed and held on the main body 1.

  A heating coil 4 for induction heating the inner pot 2 is provided on the outer bottom surface of the protective frame 3. The heating coil 4 is based on a dozen or so turns of electric wire. For example, the heating coil 4 has a substantially flat ring shape with an inner diameter of 80 mm and an outer diameter of 160 mm. There is no electric wire in the center, and the outer shape is projected on the bottom 2 a of the inner pot 2. It is in a position in the plane.

  The main body 1 includes an outer lid 5 that covers the upper portion of the main body 1, and the outer lid 5 is attached to the inside, covers the upper opening of the inner hook 2, and keeps the inside of the inner hook 2 in a substantially sealed state. The outer lid 5 is provided on the main body 1 so as to be openable and closable.

  The main body 1 is provided with a control unit 7 and heats a portion of the inner pot 2 that is substantially opposed to the heating coil 4 by electromagnetic induction heating by flowing a high-frequency current through the heating coil 4 in a controlled manner.

  The control unit 7 is provided with an operation unit 7a and a display unit 7b. When the user operates the operation unit 7a while looking at the display unit 7b, an operation such as rice cooking is executed.

  The inner pot 2 uses a clad material obtained by clad joining aluminum 2c1 and iron 2c2 as a base material 2c, and is composed of, for example, aluminum 2c1 having a plate thickness of 1.8 mm and iron 2c2 having a plate thickness of 0.5 mm. The base material 2c which is the clad material is 2.3 mm. The inside is pressed into aluminum 2c1 and the outside is iron 2c2 in the shape of the inner pot 2. And it is comprised with the form which carried out the iron spraying 2d on the surface of the iron 2c2 used as the outer surface of the base material 2c.

  The inner hook 2 is provided with a circular central portion 2f on the bottom portion 2a and an annular flat portion 2e surrounding the outer portion of the central portion 2f and facing the heating coil 4, and a corner portion 2g surrounding the upper outer portion of the annular flat portion 2e. And an inclined portion 2h (also referred to as an inclined side surface portion) inclined in a conical shape on the upper outer side of the corner portion 2g, and an outer peripheral side surface portion 2r (also referred to as a vertical side surface portion) that rises on the upper outer side of the inclined portion 2h. . As is clear from the figure, the inclined portion 2h has a diameter at the lower end smaller than that at the upper end.

  The outer side is made of iron 2c2, which improves the adhesion with the iron spray 2d and eliminates the difference in expansion and contraction when the inner pot 2 is cooled and inhibits the adhesion between the iron 2c2 and the iron spray 2d surface. This is in order not to generate such stress.

  The iron spray 2d on the outside of the inner pot 2 changes the thickness of the sprayed iron depending on the portion. Thermal spraying is a manufacturing method in which fine particles of iron melted by electric discharge are driven into the substrate at high speed, and the layers of fine particles are laminated while joining the substrate with the thermal energy and kinetic energy of the iron fine particles. By adjusting the driving position and time, the amount of iron fine particles, that is, the thickness, can be arbitrarily changed depending on the portion of the inner pot 2.

  A change in the thickness of the inner hook 2 will be described.

  An example of the thickness is shown for the purpose of explaining the comparison of the thickness by the part, but the numerical value is not limited to this, and indicates which is thicker depending on the part.

  As for the base material 2c of the inner hook 2, from the above example, the aluminum 2c1 is 1.8 mm and the iron 2c2 is 0.5 mm, and the base material 2c is 2.3 mm in total.

  The bottom portion 2a of the inner hook 2 has a ring-shaped annular flat surface portion 2e at the opposing portion of the heating coil 4. The annular flat surface portion 2e is subjected to iron spraying 2d of about 1 mm, and the thickness T together with the base material 2c is configured to be about 3.3 mm.

  The iron spray 2d at the center 2f of the bottom 2a is thicker than the annular flat part 2e and is about 1.5 mm, and the wall thickness T together with the substrate 2c is about 3.8 mm. The wall thickness T varies smoothly from the center portion 2f to the annular flat surface portion 2e without any step.

  Since the center portion 2f is curved upward in accordance with the variation of the wall thickness T, the inner pot 2 is placed on a flat desk even when the wall portion T of the center portion 2f is thicker than the annular flat surface portion 2e. Sometimes the annular flat surface portion 2e comes into contact with the desk.

  The corner portion 2g is formed by spraying an iron spray 2d of about 0.5 mm, and has a thickness T of 2.8 mm together with the base material 2c.

  The inclined portion 2h is formed by spraying an iron spray 2d of about 0.5 mm and a thickness T of 2.8 mm together with the base material 2c.

  The corner portion 2g and the inclined portion 2h constitute a thin portion 2k that is thinner than the wall thickness T of the annular flat surface portion 2e. With respect to the wall thickness T of the annular flat surface portion 2e, the corner portion 2g and the inclined portion 2h are configured so that the wall thickness changes sharply.

  The outer peripheral side surface portion 2r is formed by spraying an iron spray 2d of about 1.5 mm, and the thickness T is 3.8 mm together with the base material 2c. The outer peripheral side surface portion 2r constitutes a thick portion 2n thicker than the thickness T of the annular flat surface portion 2e. The thick wall portion 2n, which is the outer peripheral side surface portion 2r, is configured up to the upper side surface, and the range thereof is approximately twice as wide as that of the annular flat surface portion 2e, so that the heat capacity of the base material 2c and the iron spray 2d is increased. .

  The range of the thick wall portion 2n which is the outer peripheral side surface portion 2r is the range from the upper side to just below the flange portion 2b, and the lower side to the lower side from the water level where rice and water are added when cooking one rice. It is connected to the inclined portion 2h described above from below.

  The upper side of the thick wall portion 2n, which is the outer peripheral side surface portion 2r, becomes thin immediately below the flange portion 2b. The flange portion 2b does not have the iron spray 2d, and the flange portion 2b is formed only from the base material 2c. This is to make it difficult for the heat of the thick-walled portion 2n to be conducted because it is a place where the user puts his / her finger on. The reason why the lower side is lower than the water level in which rice and water are added when cooking 1 go rice is to cope with the amount of cooked rice that is easily affected by convection of water depending on the amount of rice.

  Therefore, in the inner hook 2, the thickness t of the central portion 2f and the outer peripheral side surface portion 2r is thicker than the annular flat surface portion 2e, and the thickness t of the corner portion 2g and the inclined portion 2h is thinner than the annular flat surface portion 2e.

  The inner hook 2 is formed into an inner hook shape using a clad material having a substantially uniform plate thickness as a base material 2c, and iron spray 2d is applied to the outside of the base material 2c, and the thickness of the iron spray 2d is changed to change the thickness T. The center portion 2f, the annular flat surface portion 2e, the corner portion 2g, the inclined portion 2h, and the outer peripheral side surface portion 2r are configured.

  Next, the operation of the above configuration will be described with reference to FIGS.

  When cooking rice, the user puts rice and an appropriate amount of water into the inner pot 2, accommodates them in the main body 1, and closes the outer lid 5. The inner lid 6 is in contact with the flange portion 2b of the inner hook 2 so that the air tightness inside the inner hook 2 is maintained.

  Next, the display of the display part 7b is confirmed, the operation part 7a is operated, and rice cooking is started.

  When the said operation is input into the control part 7, rice cooking will start and it will enter a soaking process. The heating coil 4 is energized intermittently, the inside of the inner pot 2 is kept at about 50 ° C., and water is efficiently sucked into the rice. Since the dipping process requires less heating for an execution time of about 15 minutes, at the end, both the inside of the inner pot 2 and each part of the inner pot 2 are in a state of approximately 50 ° C.

  Next, when the dipping process is completed, the heating process is started. In the heating process, the first half of the heating process is heated until boiling starts in about 5 to 10 minutes, and the amount of heating is reduced so that it does not spill after boiling, and the boiling state is continued for about 5 minutes until the rice disappears by sucking water. Consisting of the latter half of the heating process.

  In the first half of the heating process, the heating coil 4 is energized to heat the inner pot 2 with high power. The annular flat surface portion 2e facing the heating coil 4 of the inner pot 2 generates heat by electromagnetic induction heating.

  3 and 4, the transmission of heat during heating will be described.

  From the state where the temperature of the inner pot 2 at the end of the dipping process is about 50 ° C., the annular flat surface portion 2e is heated to a state of about 100 ° C. at a stretch. This heat has a large thickness T of the base material 2c and the iron spray 2d, and heat is easily transmitted in the cross section, so that the central portion 2f is surrounded by the annular flat surface portion 2e. Heat is concentrated by the large heat conduction Nd through which heat is transmitted.

  The heat of the annular flat surface portion 2e is transmitted not only to the central portion 2f direction but also to the outer corner portion 2g. Further, it is transmitted through the inner hook 2 cross section to the inclined portion 2h and the outer peripheral side surface portion 2r. However, since the corner portion 2g and the inclined portion 2h are configured as the thin-walled portion 2k, it is difficult for heat to be transmitted through the cross section, and the wall thickness T is drastically reduced particularly in the section from the annular flat surface portion 2e to the corner portion 2g. Since heat is not easily transmitted in the direction of the corner portion 2g, it is transmitted by the small heat conduction Ns. Therefore, more heat is concentrated from the annular flat surface portion 2e in the central portion 2f direction than in the corner portion 2g direction.

  Further, in addition to the fact that heat is not easily transmitted to the outer peripheral side surface portion 2r which is the thick wall portion 2n via the corner portion 2g and the inclined portion 2h, the outer peripheral side surface portion 2r has a thick wall thickness T, a wide range and a large heat capacity. Therefore, it takes a quantity of heat to warm up, and is slower than the temperature rise in the central portion 2f. For this reason, when the annular flat surface portion 2e and the central portion 2f exceed 100 ° C., the outer peripheral side surface portion 2r is in a state where the temperature is as low as approximately 80 ° C.

  Convection during boiling will be described with reference to FIGS.

  The water warmed by the annular flat surface portion 2e and the central portion 2f slightly exceeding 100 ° C. convects upward. The upper part of rice inhibits convection of water due to the presence of rice, but there is little elution of sticky starch solution from the rice in the first half of the heating process, and there is much water. Convection through.

  As shown in FIG. 3, when the water immediately above the annular flat portion 2e and the central portion 2f reaches about 100 ° C., the medium convection Tn begins to boil violently and pushes the rice grains to create a hot water path on the central portion 2f. Happens. At this time, the outer peripheral side surface portion 2r, which is the thick portion 2n, has not yet exceeded 100 ° C. due to the slow heat conduction and the heat capacity, and therefore no convection occurs from the outer periphery of the side surface (the state shown in FIG. 3). .

  Due to the intense middle convection Tn from the central portion 2f, the control unit 7 switches to the latter half of the heating process. After about 1 minute, the temperature of the thick part 2n also rises to a temperature slightly exceeding 100 ° C. with a delay. Then, as shown in FIG. 4, when the thick part 2n and the thin part 2k exceed 100 ° C., the outer convection Ts which is the convection from the outer periphery along the inclined part 2h from the corner part 2g of the inner pot 2 is also generated (FIG. 4). 4).

  In the second half of the heating process, the starch eluted from the rice and the stickiness of the rice itself increase, and the water is also absorbed and reduced by the rice, so the resistance to convection is large and convection is difficult. However, the central portion 2f has a resistance to the outer convection Ts because the convection from the outer periphery follows the corner portion 2g and the inclined portion 2h of the inner pot 2 with less resistance due to the hot water passage already formed, and the convection from the outer periphery follows the corner portion 2g and the inclined portion 2h. Is decreasing. Therefore, the boiling state continues in a state where both the middle convection Tn and the outer convection Ts are generated in the center. By convection in this way, as shown in FIG. 4, the rice surface K also rises at the center.

  As shown in the present embodiment, there is no medium convection Tn and outer convection Ts, and only the convection from the outer periphery of the inner pot 2 toward the center causes the outer peripheral rice to rise, the central portion is recessed, and the outer peripheral rice having a high temperature is It is soft, large in size, hard at the center where the temperature is low, and small in size. In this embodiment, the central portion does not dent, the surface of the central portion swells smoothly, heat is made uniform by the convection between the center and the outer peripheral portion, and water is sucked in a state where the hardness and grain size are uniform.

  When there is no water in the inner pot 2, the control unit 7 stops the heating process and shifts to the steaming process. In the steaming step, the heating coil 4 is intermittently energized so as to sufficiently maintain the temperature at 100 ° C., thereby preventing the temperature from decreasing. If the heating coil 4 is heated a lot, the rice will be burnt, but the central portion 2f and the outer peripheral side surface portion 2r are difficult to cool because the thickness T is large and the heat capacity is large, and heating in the heating coil 4 is not increased. However, the bottom 2a and the side surface can be kept at a high temperature.

  The steaming process is completed in about 15 minutes, and the maintenance of 20 minutes at 100 ° C. necessary for changing rice into rice satisfies the boiling state in the latter half of the heating process and the time of the steaming process.

  As described above, according to this embodiment, the annular flat surface portion 2e of the inner hook 2 facing the heating coil 4 is heated by electromagnetic induction by the heating coil 4. This heat is conducted to the central portion 2f, which is thick and easy to transmit heat in the cross section. Since the central portion 2f is surrounded by the annular flat surface portion 2e, the heat is transmitted from the entire periphery and the heat is concentrated. The heat of the annular flat surface portion 2e is transmitted not only in the direction of the central portion 2f but also to the outer peripheral side surface portion 2r of the inner hook 2. However, since the thin portion 2k is present, the heat is not easily transmitted in the cross section. Therefore, a lot of heat is concentrated in the central portion 2f. The thin-walled portion 2k is difficult to transfer heat in the cross section, but can transfer heat to the upper thick-walled portion 2n. Since the outer peripheral side surface portion 2r is a thick portion 2n and has a large cross-sectional thickness T and a large heat capacity of the material iron, it takes time to increase the temperature.

  For this reason, convection rising from the annular flat surface portion 2e where the temperature rise is concentrated to the central portion 2f is generated vigorously at the beginning of the convection after boiling. At the beginning of boiling, the rice is less sticky, so that water can convection with little resistance even from the center to generate medium convection Tn. At this time, the rice grains on the hot water passage move, and a plurality of hole-like passages are formed. If left when cooked, it is called a crab hole. When about 1 minute has passed since the beginning of boiling, the temperature of the outer peripheral side surface 2r, which is the thick portion 2n, also rises with a delay. When the temperature of the outer peripheral side surface portion 2r and the thin wall portion 2k, which are the thick portion 2n, rises, the outer convection Ts along the outer periphery of the inner hook 2 is also generated.

  In the center, hot water has a medium convection Tn with less resistance due to the hot water passage formed in the early stage of boiling, and both hot water outer convection Ts along the outer periphery of the inner pot 2 where the convection resistance is originally low are generated. The boiling state continues.

  As described above, in this embodiment, by changing the wall thickness T and the heat capacity of each portion of the inner pot, the middle convection Tn convection from the inner pot central portion is generated at the beginning of boiling, and in the latter stage of boiling, A rice cooker that convects with medium convection Tn and outer convection Ts on the outer periphery of the inner pot can be realized. The size of can be obtained evenly cooked, and it can be solved that the center part of the surface is recessed and the grains are small and hard.

  As a result, the outer periphery of the inner pot 2 rises and the central part does not dent, the surface of the central part rises smoothly, the heat is made uniform by the convection between the central part and the outer peripheral part, and the hardness and grain size are evenly cooked. Can be obtained.

DESCRIPTION OF SYMBOLS 1 Main body 1a Top frame 2 Inner hook 2a Bottom part 2b Flange part 2c Base material 2c1 Aluminum 2c2 Iron 2d Iron spray 2e Annular plane part 2f Center part 2g Corner part 2h Inclined part 2i Thin part 2j Thick part 2r Outer side part 3 Protective frame 4 Heating coil 5 Outer cover 6 Inner cover 7 Control part 7a Operation part 7b Display part T Thickness

Claims (1)

The body,
An inner pot that is detachably provided inside the main body and uses iron on the outside of the substrate;
A substantially planar annular heating coil that is provided at a position facing the bottom surface of the inner hook and that induction heats the inner pot;
In the rice cooker comprising the main body and an outer lid that closes the upper surface opening of the inner pot,
A peripheral side face up below the water level containing the rice and water when cooking the rice beneath or al 1 Go flange portion on the side of the kiln, the plane in which the heating coil in the bottom of the inner pot is opposed A rice cooker characterized in that a thick part constituted by thermal spraying of iron is provided on the iron part of the base material at the inner center part of the base material.