JP2008048809A5 - - Google Patents

Description

rice cooker

  The present invention relates to a rice cooker that uses steam having a boiling point equal to or higher than the boiling point of water in order to improve rice cooking performance.

  In general rice cookers for home use, the pan heating means placed at the bottom of the pan to heat the rice and water in the pan is the main, and the heating means in the lid is the rice in the pan above the water. As a result of the space, auxiliary heating results. Therefore, the upper layer rice in the pan was insufficient in heating amount, and the rice and water in the pan could not be heated uniformly.

  Furthermore, in rice cooking, water is almost lost and fluidity of rice is lost. In the steaming process, which is the final process of rice cooking, it is delicious to continue heating until then and complete the gelatinization of rice starch. Although it is indispensable to cook rice, in this process, if the heating is continued, the rice near the bottom of the pot will be burnt, so the heating is often weakened.

  As a means for preventing insufficient gelatinization due to weakening of heating and improving rice cooking performance, a rice cooker that stores water in the lid in advance and generates steam from the water to promote heating of the upper part is proposed. ing.

  FIG. 6 shows the configuration of Patent Document 1. In FIG. 6, the rice cooker 1 has a bottomed cylindrical pot storage portion for storing the pot 2 in a detachable manner. A pan heating coil for inductively heating the pan 2 as a pan heating means 3 is provided at the bottom of the pan storage portion. Reference numeral 4 denotes a bottom temperature sensor configured to come into contact with the bottom surface of the pan 2. A pan side heating means 5 is provided with a pan side heating coil for induction heating the side surface of the pan 2. The control means 6 controls the operation of the rice cooker 1.

  In addition, a lid 7 that is pivotally supported by a hinge shaft (not shown) provided at the hinge portion at the rear of the rice cooker 1 and opens and closes the upper portion of the pan 2 is provided. The lid 7 is provided with a lid heating plate 8, and a lid heating coil for inductively heating the lid heating plate 8 is provided as the lid heating means 9. The lid heating plate 8 has a lid heating plate steam port 11, a lid steam port 12 is provided on the top surface of the lid 7, and the inside of the pan 2 communicates with the outside of the machine and is at atmospheric pressure. The steam opening packing 13 is sandwiched between the lid heating plate 8 and the lid 7, and the pan packing 14 is sandwiched between the lid heating plate 8 and the flange portion on the outer periphery of the upper edge of the pan 2 when the lid 7 is closed. ing.

  Further, on the lid heating plate 8, water is stored and the steam generator 10 that generates steam by being supplied with heat from the lid heating plate 8 by heating the lid heating means 9 includes the lid heating plate 8 and the lid heating plate 8. 7. A water supply container 15 that stores water that generates steam and a water supply container lid that opens and closes the upper portion of the water supply container 15 are disposed above the lid heating plate 8, particularly the steam generator 10.

Further, the steam generated in the steam generating section 10 moves on the surface of the lid heating plate 8 to the steam inlet 10b through the space area surrounded by the steam packing 10a and is put into the pot 2. The entire lid heating plate 8 is maintained at a predetermined high temperature. In particular, by setting the vapor passage portion to a high temperature, the vapor temperature is maintained at 100 ° C., and high-temperature vapor exceeding 100 ° C. is generated. be able to.
JP 2005-160917 A

  However, when steam is generated by the rice cooker having the above-described conventional configuration, the following problems occur. That is, the amount of heat required for evaporation of water is about 2257 J / g, but the constant pressure specific heat of steam is 1.9 J / g · ° C., and the amount of heat required to raise the steam temperature from 100 ° C. to 110 ° C. is 19 J / g. It becomes. In this configuration, when the lid heating plate is heated by energization of the lid heating means, and when vaporization of water and heating of the vaporized vapor are performed equally and simultaneously, input power of the lid heating means is applied to secure the amount of water evaporation. The amount of heat that raises the temperature of the steam is much smaller than the amount of heat that evaporates the water, so the heat distribution in the steam generating part of the heating plate and other parts of the heating plate vary greatly, causing the steam temperature to rise too much. Rice loses its taste because it evaporates water.

The present invention solves the above-described problem, and includes a steam generating means for generating steam, a steam heating means for heating the steam generated by the steam generating means, and a water supply means for supplying evaporated water to the steam generating means. provided, the detection and the cover heating means steam generator with improved heat density of the lid and the evaporation portion in which a recess-shaped evaporation section for storing the water evaporated, the presence or absence of evaporation water stored in the recessed evaporators And a lid sensor unit .

  According to the present invention, in a rice cooker that performs heating from above, which is insufficient in heating rice and water in a pot, and prevents the drying of the upper portion, by generating steam efficiently and with finer accuracy. The present invention provides a rice cooker that has a very good taste and realizes a small steam rice cooker.

1st invention covers the opening part of a rice cooker main body, a pan, the pan heating means which heats the said pan, the lid | cover provided above the said rice cooker main body, and the said lid | cover below the lid | cover. An inner lid; lid heating means for heating the inner lid; steam generating means for generating steam; steam heating means for heating the steam generated by the steam generating means; and supplying evaporating water to the steam generating means Water supply means, wherein the steam generating means is provided with the inner lid provided with a concave-shaped evaporation section for storing evaporated water, the lid heating means for increasing the heat generation density of the evaporation section, and the concave-shaped evaporation section. It has a lid sensor unit that detects the presence or absence of evaporated water stored in the tank , and the path from the generation of steam to the pot becomes compact, and hot steam is cooled in the path and thrown into the pot without condensation can do. Further, the steam generating means is provided with an inner lid provided with a concave-shaped evaporation section for storing the evaporated water, so that the evaporated water stored in the evaporation section is caused by the latent heat of the steam generated during rice cooking at the evaporation section of the inner lid. The heat is exchanged, and the boiling state is reached in the latter half of the cooking process. The energy for preheating the evaporated water is reduced, and the steam heating means can be shared with the lid heating means, so that the configuration can be greatly simplified. . Furthermore, by increasing the heat generation density of the evaporation section, it is possible to secure the evaporation amount of the evaporating water, and the portions other than the evaporation section can appropriately prevent the overheating of the inner lid by appropriately reducing the heat generation density. It becomes possible to add the heating steam of rice to rice, and the rice cooking performance can be ensured.

  According to a second aspect of the present invention, the steam heating unit includes a lid heating unit, an outer lid cover facing the inner lid, and a packing provided on the outer peripheral part of the inner lid, and the steam heating unit includes A steam outlet that allows steam to pass through and puts steam into the pan is located almost diagonally to the evaporation section, and the steam generated in the evaporating water can exchange heat using the entire inner lid, so stable heating steam Can be provided.

According to a third aspect of the present invention, the lid heating means is constituted by a lid coil, and the space distance between the lid coil and the inner lid evaporation portion is wider than the space distance between the inner lid evaporation portion and the lid coil. Inductive current is generated in the inner lid by the magnetic flux generated from, but if the spatial distance between the inner lid and the lid coil is increased, the induced current is reduced and the heat generation of the inner lid is small. In addition, if the spatial distance between the inner lid and the lid coil is short, the induced current increases and the inner lid generates a large amount of heat. Therefore, the amount of heat generated per unit area by appropriately changing the spatial distance between the lid coil and the inner lid. Can be controlled.

  According to a fourth aspect of the present invention, the lid heating means is constituted by a lid coil and ferrite, and the ferrite is concentrated on the evaporation portion on the surface facing the evaporation portion, and the magnetic flux generated from the lid coil is The magnetic flux on the surface facing the inner lid is used for inducing the induced current of the inner lid, but on the surface not facing the inner lid, it becomes a leakage flux that is not used for inducing the induced current of the inner lid. By providing ferrite at the location where leakage magnetic flux is generated, the leakage magnetic flux that is generated passes through the ferrite part with high permeability and returns to the lid coil, so that the leakage magnetic flux is reduced. As a result, the unit of the inner lid of the part where the ferrite is provided Since the amount of heat generated per area increases, the distribution of the amount of heat generated per unit area can be controlled by providing ferrite.

  According to a fifth aspect of the present invention, a lid reflector made of aluminum is provided in the opposite direction of the inner lid and the lid coil, and an induced current is generated in the lid reflector when the magnetic flux generated from the lid coil passes through the lid reflector. To do. Since the lid reflector is made of aluminum and has a small volume resistivity, heat generation is very small. The induced current generated in the lid reflecting plate generates a magnetic flux that cancels the magnetic flux generated from the lid coil, so that the magnetic flux supplied to the inner lid is reduced and the amount of heat generated per unit area is reduced. However, the leakage magnetic flux generated when ferrite is interposed between the lid coil and the lid reflection plate passes through the ferrite portion having a high magnetic permeability and returns to the lid coil. The magnetic flux that cancels out the magnetic flux generated from the lid coil is reduced, the magnetic flux supplied to the inner lid and the amount of decrease are reduced, and the amount of heat generated per unit area is reduced. Therefore, the distribution of the amount of heat generated per unit area can be controlled by partially interposing the ferrite between the lid reflector and the lid coil.

A sixth invention is the evaporation unit is 2 minutes by the convex portion, one obtained by contact with the lid sensor unit to the convex portion, stored in the evaporation of water is vaporized heated steam. During this time, since water is present in the evaporation part, the convex part that divides the evaporation part into two is also located in the vicinity of water, so the temperature of the convex part 31 is also around 100 ° C., which is the boiling point of water. Moreover, since the vapor | steam is filled with the vapor | steam from the water of the evaporation part, the detection temperature of a temperature detection means is also 100 degreeC. When energization is continued in the lid coil, water disappears, and when the temperature of the inner lid begins to rise, the temperature of the convex portion also begins to rise. It is determined that the temperature detected by the temperature detecting means has risen and the water 26 has disappeared, and the energization amount of the lid coil 34 is reduced to prevent overheating.

In the seventh invention, auxiliary heating means is provided in the vicinity of the lid sensor unit , and when there is no water from the beginning of rice cooking, the auxiliary coil is energized simultaneously with the energization of the lid coil. Since the contact portion with the contact is also heated quickly, the temperature of the lid thermistor rises quickly and it is judged that there is no water at an early stage, and it is possible to prevent overheating of the inner lid by controlling the energization of the lid coil. .

(Embodiment 1)
Embodiments of the present invention will be described with reference to FIGS. In order to simplify the drawing, lead wires for electrical connection, water supply paths, and the like are omitted. 21 is a main body of the rice cooker, and is equipped with a removable pot 22. Furthermore, the lid | cover 23 which covers the upper surface of the pan 22 is installed so that opening and closing is possible. Reference numeral 24 denotes a pot coil which is a pot heating means for heating the pot 22 and a pot temperature detecting means 25 for detecting the temperature of the pot 22 inside the main body 21.

A water supply tank 27 for storing water 26 is detachably attached to the lid 23, and the pump 28 is connected to the water supply tank 27, and the water 26 is located on the upper surface of the pan 22 below the lid 23 and is detachably provided. The stainless steel inner lid 29 is supplied. The water supply tank 27 and the pump 28 constitute water supply means.

  The inner lid 29 is provided with a concave-shaped evaporation section 30 for storing water 26. The evaporation part 30 is divided into two by a convex part 31. Further, the evaporator 30 is provided with an inclination of 5 ° so that the water is always stored at a predetermined position even when the rice cooker is placed at an inclination and the water 26 is reduced. Reference numeral 32 denotes a steam outlet for supplying water vapor into the pot 22 when the water 26 is heated and is provided at a position diagonal to the evaporator 30.

  Reference numeral 33 denotes a lid cover provided on the lower surface of the lid 23 so as to face the inner lid 29. Reference numeral 34 denotes a lid heating means, which is a lid coil provided in the lid cover. A winding having a center on top. The lid coil 34 also forms a concave shape in accordance with the concave shape of the evaporation portion 30 of the inner lid 29. An auxiliary coil 34 </ b> A is connected to the lid coil 34 in series with the lid coil 34, and is provided at a position for heating the top of the convex portion 31.

  The inner lid 29 provided with the evaporation unit 30 and the lid coil 34 constitute a steam generating means.

  Reference numeral 35 denotes ferrite, which is provided on the lid coil 34 and at the position of the evaporation unit 30 at the projection position. An aluminum lid reflector 36 is disposed on the lid coil 34 and the ferrite 35. Reference numeral 37 denotes a circuit board. A microcomputer (not shown) is mounted on the circuit board 37. The microcomputer controls the current for generating an alternating magnetic field in the pan coil 24 and the lid coil 34 by software.

  A lid sensor unit 38 is attached to the lid cover 33. In FIG. 3, the lid sensor unit 38 includes a lid thermistor 39 that changes its resistance value according to temperature, and a thermistor insulator 39 </ b> B penetrating through two thermistor lead wires 39 </ b> A protruding from the rear of the lid thermistor 39. It is welded. An insulating tube 39C is provided on the outer periphery of the thermistor lead wire 39A to prevent a short circuit between the thermistor lead wires 39A. A lid thermistor 39 is held on the outer periphery of the lid thermistor 39 and is housed in a contact 40 made of bottomed cylindrical aluminum or stainless steel. The front end of the lid thermistor 39 is in contact with the bottom surface of the contact 40 via an insulating film 41 made of a resin film such as a polyimide film. A resin holder 42 is provided on the outside of the side surface of the thermistor 39 to stabilize the posture of the thermistor 39 and increase the creepage distance between the contact 40 and the thermistor lead wire 39A to prevent static electricity from entering the contact 40 from a human or the like. The contact 40 is provided at a position where the inner lid 29 comes into contact with the convex portion 31 of the inner lid 29 and the central portion of the auxiliary coil 34 </ b> A when the inner lid 29 is attached to the lid 23, and detects the temperature of the convex portion 31 of the inner lid 29. 42 is a packing provided on the outer peripheral portion of the lid cover 33, and the inner lid 29, the lid cover 33 and the packing 42 constitute a steam heating unit 43 which is a steam heating means.

  The operation in the above configuration will be described. The rice to be cooked and the water corresponding to the amount of the rice are put in the pan 22 and the main body 21 is decorated in a predetermined state. Further, a predetermined amount of water 26 is placed in the water supply tank 27 and set in the main body 21. When the user operates a rice cooking start switch (not shown), the pump 28 is first driven to evaporate the water 26 in the water supply tank 27. After making it store in part 30, a rice cooking process is carried out. The rice cooking process proceeds in each process of soaking, cooking, and steaming. The water 26 stored in the evaporating unit 30 is heat-exchanged by the evaporating unit 30 of the inner lid 29 by the latent heat of steam generated during rice cooking, and is boiled in the latter half of the cooking process.

When the unevenness process is entered, the lid coil 34 is energized. When the lid coil 34 is energized, a part of the water 26 in a boiling state immediately evaporates and emits steam 26A. While this steam 26 </ b> A passes through the steam heating unit 43, the steam 26 </ b> A is heated from the inner lid 29, the steam temperature exceeds 100 ° C., and is discharged into the pot 22 through the steam outlet 32.

  Here, the water put in the pan at the start of cooking rice is absorbed and evaporated by the rice and almost disappears. However, a lot of moisture tends to remain at the bottom of the pot 22. In order to remove the excess moisture and promote gelatinization of the rice, the pan 2 is also heated in the steaming process. However, since there is little moisture, when it heats from the bottom of the pan 22, the rice near the surface to which the pan 22 is heated burns. Further, the rice on the upper surface of the pot 22 is easily dried because moisture is actively evaporated. Therefore, by heating with steam from the upper surface also in the steaming step, it is possible to prevent a local temperature rise in the heating of the entire pan and drying of the rice in the upper surface and the vicinity thereof.

  The steam discharged into the pot 22 is heated to high temperature steam by the inner lid 29 maintained at a high temperature by the steam heating unit 43 and heats the rice and water in the pot 2, so that it is fine according to the rice cooking process. Steam generation control more suitable for cooking rice can be performed, and delicious rice can be cooked.

  The following problems occur when the steam is generated. That is, the amount of heat required for evaporation of water is about 2257 J / g, but the constant pressure specific heat of steam is 1.9 J / g · ° C., and the amount of heat required to raise the steam temperature from 100 ° C. to 110 ° C. is 19 J / g. It becomes. In this configuration, when the inner lid 29 is heated by energization of the lid coil 34 and the water 26 is vaporized and the vaporized water 26 is heated uniformly and simultaneously, the input power of the lid coil 34 is ensured to ensure the evaporation amount of the water 26. The amount of heat that raises the temperature of the steam 26A than the amount of heat that evaporates the water 26 is much smaller, so the heat distribution in the evaporation part 30 of the inner lid 29 and the other parts greatly vary, and the temperature of the steam 26A changes. On the other hand, the rice on the upper surface of the pan 22 evaporates the water and deteriorates the taste.

  Therefore, in order to cook delicious rice, it is necessary to appropriately control the evaporation amount of the water 26 and the temperature at which the steam 26A is discharged into the pot 22 from the steam outlet 32. In order to achieve the above condition, the amount of heat generated per unit area of the evaporation unit 30 of the inner lid 29 needs to be larger than the amount of heat generated per unit area other than the evaporation unit 30.

  In order to solve the above problems, the present embodiment adopts the following three configurations.

  The first configuration will be described with reference to FIG. In the coil 34, the spatial distance Y between the inner lid 29 other than the evaporator 30 and the lid coil 34 is made wider than the spatial distance X between the inner lid 29 and the lid coil 34 in the evaporator 30 portion. In the present embodiment, the spatial distance X is set to 6.5 mm, and the spatial distance Y is set to 9.5 mm.

  The induced electromotive force of the inner lid 29 generated by the magnetic flux generated from the lid coil 34 is controlled by changing the spatial distance between the inner lid 29 and the lid coil 34 in the above configuration. With the above configuration, an induced current is generated in the inner lid 29 due to the magnetic flux generated from the lid coil 34. However, if the spatial distance between the inner lid 29 and the lid coil 34 is increased, the induced current is reduced, so that the inner lid 29 The heat generation is small. In addition, when the spatial distance between the inner lid 29 and the lid coil 34 is short, the induced current increases, so the heat generated in the inner lid 29 increases. Therefore, the unit area can be changed by appropriately changing the spatial distance between the lid coil 34 and the inner lid 29. The distribution of the amount of heat generated per hit can be controlled.

As a second configuration, the ferrite 35 is disposed on the upper surface of the lid coil 34 at a position facing the evaporation unit 30 provided on the inner lid 29. The magnetic flux generated from the lid coil 34 in the above configuration is used for inducing the induced current of the inner lid 29 while the magnetic flux on the surface facing the inner lid 29 is used. The leakage magnetic flux is not used for current induction. By providing the ferrite 35 at the place where the leakage magnetic flux is generated, the generated leakage magnetic flux passes through the ferrite portion 35 having a high magnetic permeability and returns to the lid coil 34, so that the leakage magnetic flux is reduced. As a result, the portion of the portion where the ferrite 35 is provided is reduced. Since the amount of heat generated per unit area of the inner lid 29 increases, the distribution of the amount of heat generated per unit area can be controlled by providing the ferrite 35.

  In the embodiment, Mn—Zn soft ferrite is used for the ferrite 35, but the same effect can be obtained with a material having high magnetic permeability, such as a silicon steel plate or permalloy.

  Further, in the present embodiment, the ferrite 35 is provided in the evaporation unit 30, but the ferrite 35 may be provided as needed other than the evaporation unit 30.

  As a third configuration, an aluminum lid reflecting plate 36 is disposed on the lid coil 34 and the ferrite 35. In the above configuration, when the magnetic flux generated from the lid coil 34 passes through the lid reflector 36, an induced current is generated in the lid reflector 36. Since the lid reflector 36 is made of aluminum and has a small volume resistivity, heat generation is very small. The induced current generated in the lid reflecting plate 36 generates a magnetic flux that cancels the magnetic flux generated from the lid coil 34, so that the magnetic flux supplied to the inner lid 29 is reduced and the amount of heat generated per unit area is reduced. However, the leakage magnetic flux generated when the ferrite 35 is interposed between the lid coil 34 and the lid reflection plate 36 passes through the ferrite portion 35 having a high magnetic permeability and returns to the lid coil 34, so that the leakage magnetic flux is reduced and is generated in the lid reflection plate. Since the electromotive current is reduced, the magnetic flux that cancels the magnetic flux generated from the lid coil 34 is reduced, the magnetic flux supplied to the inner lid 29 is reduced, and the amount of decrease in the amount of heat generated per unit area is also suppressed. . Therefore, the distribution of the amount of heat generated per unit area can be controlled by partially interposing the ferrite 35 between the lid reflector 36 and the lid coil 34.

  Further, even if the spatial distance between the lid coil 34 and the lid reflector 36 is changed, the same effect can be obtained. That is, when the spatial distance between the lid reflector 36 and the lid coil 34 is increased, the induced current is reduced. In addition, when the spatial distance between the lid reflector 36 and the lid coil 34 is short, the induced current increases, so the distribution of the amount of heat generated per unit area is controlled by appropriately changing the spatial distance between the lid coil 34 and the lid reflector 36. can do.

  Further, if the lid reflecting plate 36 is arranged so as not to partially face the lid coil 34, the magnetic flux generated from the lid coil 34 is not canceled, and the amount of heat generated per unit area of the inner lid 29 can be increased. .

  By combining the above-mentioned configurations, delicious rice is cooked by optimizing the balance between the amount of heat generated per unit area of the evaporation section 30 of the inner lid 29 and the amount of heat generated per unit area other than the evaporation section 30. It is something that can be done.

  In this way, the water 26 stored in the evaporation section 30 of the inner lid 29 is vaporized and becomes steam. During this time, since the water 26 is present in the evaporation part 30, the convex part 31 that divides the evaporation part into two is also located in the vicinity of the water 26, so the temperature of the convex part 31 is also around 100 ° C., which is the boiling point of the water 26. Moreover, since the vapor | steam is filled with the space from the evaporation part 30 from the water 26, the detection temperature of a lid | cover thermistor is also 100 degreeC. When energization of the lid coil 34 is continued, the water 26 disappears, and when the temperature of the inner lid 29 begins to rise, the temperature of the convex portion 31 also begins to rise. The temperature of the lid thermistor 39 also rises via the contact 40 and it is determined that the water 26 has disappeared, and the energization amount of the lid coil 34 is reduced to prevent overheating.

  When there is no water 26 from the beginning of rice cooking, the auxiliary coil 34A is energized simultaneously with the energization of the lid coil 33, so that the contact portion of the convex portion 31 with the contact 40 is also quickly heated. The temperature of the thermistor 39 rises quickly, and it is determined that there is no water 26 at an early stage. By controlling the energization of the lid coil 34, the inner lid 29 can be prevented from being overheated.

  By the said structure, it becomes a rice cooker which can provide delicious rice.

  The present invention can be widely applied to rice cookers regardless of home use or business use.

Sectional drawing of the rice cooker in embodiment of this invention The partial perspective view of the heating plate in embodiment of this invention Sectional drawing of the lid sensor in embodiment of this invention The top view of the cover coil in embodiment of this invention The positional relationship figure of the lid coil and a heating plate in embodiment of this invention Cross section of conventional rice cooker

DESCRIPTION OF SYMBOLS 21 Rice cooker main body 22 Pot 23 Lid 24 Pot heating means 27 Water supply tank 28 Pump 29 Inner lid 30 Evaporating part 31 Convex part 32 Steam outlet 33 Cover cover 34 Cover coil (lid heating means)
34A Auxiliary coil 35 Ferrite 36 Lid reflector 38 Lid sensor 42 Packing 43 Steam heating unit

Claims (7)

A rice cooker body, a pan, a pan heating means for heating the pan, a lid provided above the rice cooker body, an inner lid provided below the lid and covering an opening of the pan, and the inner A lid heating means for heating the lid; a steam generating means for generating steam; a steam heating means for heating the steam generated by the steam generating means; and a water supply means for supplying evaporated water to the steam generating means. , evaporated water the steam generating means, which is stored in the and the cover heating means, said recessed evaporators with increased heat density with the inner lid provided with a recess shaped evaporators the evaporating section for storing the water evaporated A rice cooker having a lid sensor unit for detecting the presence or absence of food. The steam heating unit includes a lid heating unit, an outer lid cover facing the inner lid, and a packing provided on the outer peripheral portion of the inner lid, and constitutes a steam heating unit. The rice cooker of Claim 1 which has arrange | positioned the steam outlet which throws into a pan into a substantially diagonal with the evaporation part. The rice cooker according to claim 1, wherein the lid heating means is constituted by a lid coil, and the space distance between the lid coil and the space other than the inner lid evaporation portion is wider than the space distance between the evaporation portion of the inner lid and the lid coil. 2. The rice cooker according to claim 1, wherein the lid heating means is constituted by a lid coil and ferrite, and the ferrite is concentrated and installed on the surface facing the evaporation portion. The rice cooker of Claim 3 or 4 which provided the lid | cover reflecting plate which consists of aluminum in the reverse direction of an inner cover and a cover coil. The rice cooker according to claim 2 , wherein the evaporating part is divided into two parts by a convex part, and a lid sensor unit is brought into contact with the convex part. The rice cooker according to claim 6, wherein auxiliary heating means is provided in the vicinity of the lid sensor unit .