JPH09262174A - Rice cooker and manufacture of undersurface member of it's lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a rice cooker which manages the intended operation with no provision of inner lid, ensures an enhanced strength of the undersurface plate of lid, is constructed light in the weight, and enables uniform lid heating. SOLUTION: The upper opening 13 of a deep pan 5 is directly enclosed with a lid 41, and therefore, the cooker is easy to handle owing to omission of inner lid. The undersurface plate 44 of the lid has varying material thickness such that the material thickness C1 at the periphery is larger than the thickness C2 of the central part, to ensure an enhanced strength of the undersurface plate 44 at its periphery liable to have an inferior strength. The undersurface plate 44 is provided with a recess 47 and projection 47A as mating with a cord heater 48, and thereby the surface area of the plate 44 is enlarged so that the lid heating with the cord heater 48 can be made uniformly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker without an inner lid at the bottom of a lid, and more particularly to a rice cooker having an improved lower surface member for covering an upper opening of a pot and a lid of the rice cooker. The present invention relates to a method for manufacturing a lower surface member.

[0002]

Conventionally, as a rice cooker of this type, for example, in Japanese Unexamined Patent Publication No. 7-204086, a so-called lid bottom plate which forms a lower portion of the lid directly covers the upper opening of the pan. A structure without an inner lid (without an inner lid) has been proposed. The rice cooker with such a structure is easy to use because there is no trouble of attaching and detaching the inner lid, and there is no need to clean the inner lid. On the other hand, a lid that is soiled due to the adhesion of rice (starch-dissolved water) during cooking. It is necessary to wipe the lower surface of the body. For this reason, when the lid is deformed or squeezed when it is wiped off, it becomes difficult to wipe the lid, so that it is necessary to secure sufficient strength of the lid.

As a method of solving such a problem, there is a method of increasing the material thickness of the lower surface of the lid to improve the strength of the lid. However, with this method, the weight of the lid as a whole becomes too heavy, and when the lid is opened by a hinge spring such as a torsion coil spring provided in the hinge portion, if the elastic force of the hinge spring is increased, the lid is automatically opened. Can't open. Also, when the lid is opened, the impact force applied to the hinge becomes stronger, so when the weight of the rice cooker body is light, such as when the rice cooker body does not contain a pan, the rice cooker body jumps backward. There is a problem, and for this reason, there is a problem in that the hinge portion must be additionally provided with a damper mechanism or the like for suppressing the lid opening operation force during the lid opening operation.

As a countermeasure for such an improvement, a concavo-convex shape is formed by press molding on the surface of a metal plate material having a relatively thin material thickness of about 0.7 mm to 2.0 mm as a lower surface member provided on the lid. There is a method of improving strength by work hardening by working. However, in the case of this method, if the upper surface of the lower surface member also has irregularities, when a lid heater for heating the lower surface of the lid is provided on this upper surface, the adhesion between the lid heater and the upper surface of the lower surface member deteriorates, and the efficiency is improved. There is a problem that the lower surface member cannot be heated well. Further, in the case where the lid heater is a cord-shaped heater and is covered with an aluminum foil and is adhered with an adhesive material, there is a problem that the adhering area is reduced, the adherability is deteriorated, and peeling easily occurs.

Further, conventionally, the lid is heated during rice cooking, and the cooked food is heated from above by radiant heat from the lower surface of the lid,
The rice cooking method that reduces the moisture on the top not only reduces uneven cooking, but also reduces the adhesion of steam during rice cooking so that when the lid is opened at the end of even rice cooking, the soup does not run down along the bottom surface of the lid. What we have done is well known. Further, it is well known that the lid is heated during heat retention to prevent the steam of rice from adhering to the lower surface of the lid to form dew soup and drop on the rice due to a large amount of this soup.

However, if there is uneven temperature distribution in the heating of the lid body, the function of heating the lid, on the contrary, increases the temperature difference between the high temperature portion and the low temperature portion, so that the original purpose cannot be fully achieved.

It is also well known that a conventional non-adhesive plastic coating such as a fluororesin coat is formed on the lower surface of the lid so that the stick does not stick during rice cooking.

However, when a control element such as a triac for controlling the heating of the lid fails, and the lid is heated continuously, the plastic coating melts and peels off, and after repairing the failure, the lower surface of the lid is replaced. There was a problem of need.

In view of the above problems, the present invention takes advantage of the elimination of the inner lid, improves the wiping property of the underside of the lid, and suppresses the uneven heating during rice cooking and heat retention. The purpose is to provide. Another object of the present invention is to provide a rice cooker which is less damaged and has good repairability when the lid heating device fails. Further, the present invention provides a method for manufacturing a lower surface member of a lid of a rice cooker, which can improve the wiping property of the bottom of the lid and suppress uneven heating during rice cooking and heat retention. The purpose is to do.

[0010]

In order to achieve the above-mentioned object, the rice cooker according to the first aspect of the present invention comprises a lower surface member of a lid for covering an upper opening of a pot, which is made of metal whose material thickness is partially different. In addition to being formed of a material, the pot facing surface of the lower surface member facing the pot and the inner surface facing the inside of the lid are formed to have different surface shapes, and the thickness of the material of the portion that is apt to be weak in strength. Can be increased.

Further, in addition to the structure of claim 1, the rice cooker of the invention of claim 2 has a plurality of concave and convex portions formed on the surface of the lower surface member facing the pot, and the concave and convex portions are formed corresponding to the concave and convex portions. By providing the lid heating device on the inner surface of the lower surface member, the surface area of the pan facing surface can be increased and the pan facing surface can be heated uniformly when the lid body is heated.

Further, in the rice cooker of the third aspect of the invention, in addition to the structure of the first aspect, a non-adhesive plastic coating is provided on the pot facing surface, and a lid heating device is provided on the inner surface. Since the melting temperature of the plastic coating is higher than the temperature of the lower surface member when the lower surface member is continuously heated by the lid heating device, the lid heating device becomes high temperature due to a failure or the like. However, peeling of the plastic coating can be prevented.

In the method of manufacturing the lower surface member of the lid of the rice cooker according to the present invention, the lower surface member of the lid which covers the upper opening of the pot is formed of a metal material having a partially different material thickness. A method of manufacturing a lower surface member of a lid of a rice cooker, comprising:
Since the molten metal is configured to be solidified and molded in a mold having a predetermined shape, it is possible to manufacture a lower surface member made of metal from a lower surface member having a partially different predetermined material thickness.

Further, in the method for manufacturing the lower surface member of the lid of the rice cooker according to the fifth aspect of the invention, the lower surface member of the lid which covers the upper opening of the pan is made of a metal material having a partially different material thickness. A method of manufacturing a lower surface member of a lid of a rice cooker, comprising: forming a uniform plate-shaped metal material by press molding; Can be manufactured.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described with reference to FIGS. 1 and 2. Reference numeral 1 denotes a container body, which is a bottomed cylindrical inner frame 2 having an open upper surface, and an outer frame 3 having the inner frame 2 inside to form an outer shell of the container body 1,
The bottom plate 4 covers the bottom side of the outer frame 3. The inner frame 2 which is a container housing portion is made of glass fiber-containing PET resin, and is formed in a shape substantially similar to the outer surface shape of the pan 5 which is detachably housed in the inner frame 2.

The shape of the pan 5 for containing rice, which is rice to be cooked, and water is a bottomed cylinder having an open top.
At the top of the outer surface of the pot 5, a flange-shaped handle 6 projecting horizontally outward is formed. The pan 5 is supported in a hung state by the handle portion 6 being placed on the upper end surface of the outer frame 3, and between the inner frame 2 and the pan 5 housed therein.
Except for the handle 6, a predetermined gap 7 of 1 to 4 mm is formed. The pot 5 is provided with a pot main body 8 mainly composed of, for example, an A3004 type aluminum material having excellent heat conductivity and corrosion resistance, and is provided from the outer bottom surface to the lower side of the pot main body 8. The heat generating layer 9 is made of a magnetic metal material.

Further, the overall shape of the pot 5 will be described in detail. Pot 5
The outer surface of the curve is connected to the lowermost portion 11 of the outer bottom surface of the pot 5 with a decreasing rate of the diameter increasing as the height decreases from a height h approximately at the middle of the total height H or about 1/3 of the total height H. When the pot 5 is placed on a flat table surface or the like, the lowermost portion 11 of the pot 5 comes into contact with the table surface or the like. The outermost peripheral portion 12 of the inner bottom surface facing the outermost peripheral portion of the lowermost portion 11 of the pan 5 has a diameter A2 of 25% to 75% (1/1) of the diameter A1 of the upper opening 13 of the pan 5.
4 to 3/4). The inner surface of the pan 5 has a vertical cross-sectional shape substantially along the outer surface of the pan 5, and faces the lowermost portion 11 from a side position approximately at the middle of the total height H or about １ ／ of the total height H. It is formed in the shape of a curved surface over the bottom surface to be formed. In addition, the side surface here refers to a portion from the upper surface opening 13 including the handle portion 6 to the outermost peripheral portion of the lowermost portion 11 (a portion located at the outermost peripheral portion 12) that contacts the table surface, etc. The curved surface portion 14 having the above-mentioned curved inner surface is formed from the bottom to the bottom surface. The heat generating layer 9, which is a heat generating portion of the pot 5, is formed on the outer surface of the curved portion 14 of the pot 5.

Reference numeral 21 is a heating coil provided outside the inner frame 2 and corresponding to a pan heating device for heating the heat generating layer 9 of the pan 5 by electromagnetic induction. The heating coil 21 is spirally wound and fixed on the outer surface of the inner frame 2 at a position facing the heat generating layer 9 of the curved surface portion 14 from the lower side surface to the bottom surface of the pan 5. The heating coil 21 may be provided in a portion other than this portion. However, the heating coil 21 is placed at a position facing the curved surface portion 14 of the pot 5 at least so that heat convection of water in the pot 5 is easily generated at the time of cooking rice. Preferably, 21 is provided. On the outside of the heating coil 21, a coil cover 22 having an insulating property, in which a high-permeability material powder mainly composed of iron oxide or the like is mixed with a plastic material, is provided.
It is fixed to a cylindrical portion 22A protruding upward in the central portion of the above, and is configured to prevent leakage of magnetic flux and efficiently heat the heat generating layer 9 by electromagnetic induction. By forming the coil cover 22 with the insulating plastic mixed with the high-permeability material powder in this way, both the fixing of the heating coil 21 and the leakage prevention of the magnetic flux are performed by one functional component, and the structure is simplified. It is composed. Further, 23 is a pan temperature sensor which is provided near the heating layer 9 of the pan 5 and has a negative characteristic thermistor inside, and 24 is located near the heating layer 9 and the heating coil 21 and The thermal fuse is provided on the outer surface of the frame 2.

Reference numeral 26 is a heating board provided with an inverter circuit component 27 for supplying a predetermined high frequency current to the heating coil 21. The heating substrate 26 is disposed between the bottom plate 4 at the bottom of the container body 1 and the support 28 together with the cooling fan 30 provided with the motor 29 by the support 28 provided inside the container body 1. An intake port 31 is provided at the bottom of the bottom plate 4 facing the cooling fan 30, and an exhaust port 32 is provided at a side surface of the bottom plate 4 facing one side of the heating substrate 26. Support 28
Is provided upright on one side of the heating substrate 26. Between the support 28 and the front surface of the main body 1, an LCD 33 and an LED forming an operation panel 33 as display operation means are provided.
A display operation component 36 having 34 and various switches 35;
A power supply circuit component 37 other than the inverter circuit component 27 is
It is provided in a state of being mounted on. When the cooling fan 30 is rotated by energizing the motor 29, the air taken in from the intake port 31 is sent out from the heating substrate 26 to the exhaust port 32 through the substrate 38, and the air flows between the support 28 and the bottom plate 4. Each part in the space surrounded by is forcibly cooled. 39 is a power cord 40 provided on the lower rear side of the outer frame 3.
Is a code reel that winds up.

Reference numeral 41 is a lid that covers the upper opening 13 of the pan 5 so that it can be opened and closed. The lid body 41 is attached to the outer lid 42, an outer lid cover 43 provided along the outer periphery of the lower side of the outer lid 42, and a space below the outer lid 42 to form a space. As a member, a lid lower surface plate 44 made of an aluminum material for directly covering the upper opening 13 of the pot 5 is used. The outer lid 42 is formed of a plastic such as polypropylene by injection molding so as to have a three-dimensional appearance with excellent design and can be freely colored, so that the degree of freedom of design can be improved. . Reference numeral 45 denotes a lid packing held between the outer lid cover 43 and the lid lower surface plate 44. A hinge shaft 46 is pivotally supported on the upper rear surface of the container body 1, and a lid 41 on the opposite side of the hinge shaft 46 is provided.
Alternatively, a clamp button 46A for locking the lid 41 and the container body 1 is provided on the front side of the container body 1. Although not shown, inside the hinge shaft 46, an elastic member such as a torsion coil spring that biases the lid 41 in the direction of always opening is provided, and by pressing the clamp button 46A, The lid 41 can be opened with the hinge shaft 46 as the center of rotation.

A concave portion 47 and a convex portion 47A are provided on the pot facing surface 44A of the lid lower surface plate 44 facing the pot 5 to improve the strength by work hardening. If the depth of the concave portion 47 is large, the effect of improving the strength is high, but the surface may be difficult to wipe off. Therefore, it is preferable that the depth B is formed within about 1 mm. The shapes of the concave portion 47 and the convex portion 47A are not particularly limited, and are formed in consideration of design properties such as a circle, an ellipse, a triangle, and a turtle pattern. On the other hand, the inner surface 44B of the lid lower surface plate 44 that faces the inside of the lid 41 is flat or has a convex shape with a small protruding height that is small enough to allow a lid heater to be bonded as described later.

Next, a concave portion 47 is formed in the pot facing surface 44A of the lid lower surface plate 44,
A method for manufacturing the lid lower surface plate 44 in which the pot facing surface 44A and the inner surface 44B have different surface shapes by providing the convex portion 47A and making the inner surface 44B flat or substantially flat will be described. The first manufacturing method is based on a melt forging method.
In this melt forging method, aluminum heated in a molten state is poured into a lower mold, tightened by an upper mold, pressurized and solidified from above, molded and formed, and a recess 47 and the like are formed by a mold composed of a lower mold and an upper mold. A lid lower plate 44 having a predetermined shape is formed. The second manufacturing method is based on an aluminum die casting method. In this aluminum die casting method, a molten aluminum is poured into an upper and lower mold, solidified and formed, and a lower surface plate 44 having a predetermined shape in which a concave portion 47 and the like are formed by a metal mold is formed. According to such a melt forging manufacturing method and an aluminum die casting manufacturing method, the thickness C1 of the material on the outer peripheral side of the lid lower surface plate 44 is formed thick to about 3 to 6 mm, and the thickness C2 on the center side is set to the thickness C1 of the material. It can be formed to a thinner thickness of about 1.5 to 3 mm, and can be formed into a plate shape in which the pot facing surface 44A and the inner surface 44B have non-similar shapes and the material thickness is uneven. Further, a third manufacturing method is a press molding manufacturing method. In this press molding method, as shown in FIG. 3, a concave portion 47 is stamped and formed on an aluminum plate having a material thickness of about 1 to 3 mm by press working, and then press-molded into a predetermined shape. Is to form a concave stamp only on the surface corresponding to the pot facing surface 44A.

Lid bottom plate formed by such a manufacturing method
44 is alumite treated to prevent corrosion, and then the blasted pot facing surface 44A is coated with PFA resin and dried, and then PFA resin is coated again from above and fluorine resin is applied with 2 coats and 2 bake. To form a two-layer plastic coating 53 having a melting temperature of about 240 degrees Celsius.

The inner surface 44B of the lid bottom plate 44 has a lid bottom plate 44
A code heater 48 serving as a lid heating means for heating the is provided at a position corresponding to the concave portion 47 and the convex portion 47A. This cord heater 48 is about 20 to 100W,
The surface temperature of the pan facing surface 44A is configured to be 200 degrees Celsius or less when the ambient room temperature is 35 degrees Celsius and the voltage is 110V for continuous energization. The cord heater 48 is electrically connected in parallel with a side heater 49 such as a cord heater for keeping the inner frame 2 warm. And cord heater 48
The side heater 49 is connected by a series circuit to a switching control element such as a triac which is a control means of a lid heating device (not shown). Further, a lid temperature sensor 50 composed of a negative characteristic thermistor for detecting the temperature of the lower surface of the lid body 41 is provided on the inner surface 44B side of the lid lower surface plate 44, and a predetermined value is set according to the temperature detected by the lid temperature sensor 50. The temperature of the lid lower surface plate 44 is controlled according to the temperature. Code heater 48 and lid temperature sensor 50
The upper surface of each of the aluminum foil 51 is covered with an aluminum foil 51. The upper surface of the aluminum foil 51 forms a predetermined space, and together with the outer lid cover 43 and the lid lower surface plate 44, the heat insulating plate 52.
Is fixed. 50A is a sensor retainer for holding the lid temperature sensor 50 on the upper surface of the lid lower surface plate 44. The cord heater 48 and the side heater 49 may be heated by controlling the predetermined energizing time to heat the lid lower surface plate 44 during rice cooking and heat retention.

Reference numeral 61 is a steam penetration hole provided substantially at the center of the lid lower plate 44 and the pan 5, and this steam penetration hole is shown.
The steam enters the steam port 62 from 61. Steam mouth
The structure around 62 is described in detail.
A recess 63 is provided for mounting the
A steam port cover 65 having a steam discharge port 64 formed on the upper surface exposed to the outside of the lid 41, and a bottomed cylindrical bucket 66 provided inside the steam port cover 65 so as to be vertically movable. Assembled and configured. The bucket 66 is made of a metal material made of aluminum or stainless steel, or a plastic material such as polypropylene, and a bulging portion 67 corresponding to the bottom of the steam port 62 formed below the bucket 66 has a steam port cover 65.
Are provided so as to protrude from the lower surface opening 68. On the outer upper part of the steam port cover 65, a projection 70 is formed to be locked to the locked piece 69 of the outer lid 42. The engagement and disengagement of the locked piece 69 and the projection 70 The steam port 62 can be further attached and detached.

Reference numeral 71 is a steam port packing that seals between the lower end of the recess 63 and the lid lower surface plate 44. This steam port packing 71
Is for preventing the invasion of steam into the lid 41, and when the steam port 62 is mounted in the recess 63, the steam port cover 65
The bent part 72 formed at the lower part of the outer periphery of the
A configuration in which the bottom surface of the bulging portion 67 of the bucket 66 is placed on the upper surface of the lid lower plate 44 exposed to the inner bottom surface of the concave portion 63 and closes the vapor intrusion hole 61 of the lid lower plate 44 while being in close contact with the inner end of the bucket 71. It has become. In addition, the bucket 66
A partition plate 74 having a plurality of communication holes 73 communicating the inside and the outside of the device is provided. At the center of the bulging portion 67 of the bucket 66, there is provided a return hole 75 through which the lumps collected inside the bucket 66 during rice cooking flow. The return hole 75 is a check valve made of an elastic member such as silicone rubber. It is in a state of being closed by the tongue piece 77 of 76. Therefore, the steam generated during the rice cooking enters through the steam entry hole 61 and abuts against the bottom surface of the bucket 66,
At this time, the pressure of the steam pushes the bucket 66 upward from the lid lower surface plate 44 and passes through a steam passage hole 78 formed between the outer surface of the bucket 66 and the inner surface of the steam port cover 65 to pass through the steam port cover. The steam is discharged to the outside of the lid 41 from the steam discharge port 64 on the upper surface of the cap 65. Thereafter, when the rice cooking is completed, the heating is stopped, and the process shifts to spots, the inside of the pot 5 becomes negative pressure, so that the check valve 76 moves toward the pot 5 and forms a lower portion of the check valve 76. From between the tongue piece 77 and the return hole 74, the bucket 66
The tonnage that has accumulated inside the container returns to the pot 5 side.

Further, when the temperature is kept warm, the pressure of the steam in the pan 5 is lowered, so that the bucket 66 is attached to the bottom plate of the lid by its own weight.
It is placed on the upper surface of 44 and closes the vapor entry hole 61 of the lid lower plate 44. The cord heater 48 is arranged so as to surround the steam inlet 62 in the vicinity of the steam entrance hole 61, that is, within a range of about 30 mm around the steam inlet packing 71. When the lower surface plate 44 is heated, the vapor penetration hole 61 in the vicinity thereof is heated, and
The bucket 66 in contact with the lid lower surface plate 44 is heated by heat conduction.

In the above structure, when a high frequency current is supplied to the heating coil 21 from the inverter circuit mounted on the heating substrate 26, an alternating magnetic field is generated in the heating coil 21 and the heating layer of the pan 5 located in the magnetic field. An eddy current is generated in 9 and the eddy current is converted into Joule heat, whereby the heat generating layer 9 generates heat to heat the cooked rice in the pot 5.

As described above, the jar type rice cooker of this embodiment has a structure in which the upper opening 13 of the pan 5 is covered by the lid lower surface plate 44 of the lid 41, not by the inner lid. It is easy to put on and take off, and the inner lid does not need to be cleaned, so it is practically easy to use. Further, since the lid lower surface plate 44 is made to have a partially different material thickness so that the outer peripheral side material thickness C1 is thicker than the central portion side thickness C2, the lid lower surface plate 44 is apt to be weakened in strength. The strength on the outer peripheral side can be improved. Further, by providing a plurality of concave portions 47 and convex portions 47A on the pan facing surface 44A, work hardening occurs and the strength can be further improved. By improving the strength of the lid lower surface plate 44 in this manner, only the portion of the lid lower surface plate 44 necessary to secure the strength can be made thicker, so that it is possible to improve the strength and the weight. Can be reduced. As a result, when wiping off the bean on the pot facing surface 44A, the lid bottom plate
There is no fear that the 44 will be deformed, it can be wiped off with peace of mind, and the cleanability can be improved. Further, since it is possible to reduce the weight, it is not necessary to excessively increase the elastic force of the elastic member such as the torsion coil spring that always urges the lid body 41 in the opening direction. The impact force applied is reduced, and when the weight of the container body 1 side is light, such as when the pan 5 is not housed in the container body 1, it is possible to eliminate the risk of the container body 1 side jumping backward. Further, unlike the surface shape of the pan facing surface 44A, by making the inner surface 44B flat or almost flat without any convex portion, the adhesion between the inner surface 44B and the code heater 48 can be improved, and the lid lower surface plate 44 can be efficiently attached. Can be heated. Particularly, when the lid heating means is the code heater 48 and the code heater 48 is covered with the aluminum foil 51 and is adhered with the adhesive material, the adhesion area can be secured and peeling is difficult.

Also, a cord heater 48 as a lid heating means
Is provided on the inner surface 44B corresponding to the concave portion 47 and the convex portion 47A, so that the pan facing surface 44 thermally corresponding to the cord heater 48 is provided.
The surface area of A increases. Therefore, the local heating of the pot facing surface 44A is suppressed, the temperature unevenness of the lid heating is reduced, the temperature difference between the high temperature portion and the low temperature portion is eliminated, and the upper space of the pot 5 is uniformly heated during rice cooking to prevent uneven cooking. In addition to reducing the amount, it is possible to reliably prevent dew condensation on the lid lower surface plate 44 during heat retention.

Further, the plastic coating 53 provided on the pan-opposing surface 44A of the lid lower surface plate 44 is made of a fluororesin such as PFA resin so as to prevent the stick from sticking during rice cooking, and its melting temperature is continuous with the cord heater 48. Since the temperature is about 240 degrees Celsius, which is higher than the temperature of the lid lower surface plate 44 when the lid is heated, the temperature is about 240 degrees Celsius. Therefore, for example, when a control element such as a triac for controlling lid heating fails, or the lid temperature sensor.
Even if the lid is continuously heated by the cord heater 48 such as when the wire 50 is disconnected and cannot be normally detected, the plastic coating 53 is prevented from melting and peeling. For this reason, the inconvenience of having to replace the lid lower surface plate 44 at the same time after repairing the cause of the failure is eliminated and the repairability can be improved.

Further, the lid lower surface plate 44 is manufactured by the above-mentioned melt forging manufacturing method in which molten aluminum is poured and molded, or the aluminum die casting manufacturing method, thereby thickening a portion such as the outer peripheral side necessary to secure the strength. It is possible to manufacture the lid lower surface plate 44 which can be freely and easily molded, and which can improve strength and reduce weight as described above.

Further, as shown in FIG. 3, a lid 47 is formed by a press molding method in which a concave portion 47 is formed on one surface of a flat aluminum plate by press working to form a pot facing surface 44A, while an inner surface 44B is formed flat. By manufacturing the lower surface plate 44, it is possible to manufacture the lid lower surface plate 44 that can be improved in strength by work hardening and can be improved in strength and weight as described above, even without special equipment.

The present invention is not limited to the above embodiment, but various modifications can be made within the scope of the present invention. For example, although the electromagnetic induction heating type rice cooker is shown in the embodiment, other heating type rice cookers in which a pan is heated by a sheath heater or the like may be used.

[0035]

According to the rice cooker of the first aspect of the present invention, the lower surface member of the lid that covers the upper opening of the pan is made of a metal material having a partially different material thickness, and the lower surface member is the pan. By forming the inner surface of the lid facing the pan and the inner surface facing the inside of the lid with different surface shapes, while improving the strength of the lower surface member of the lid while taking advantage of eliminating the inner lid. You can wipe off things such as those with a sense of security and improve the cleaning performance. In addition, the weight of the lower surface member, and hence the lid body, is not excessively heavy so that the container body is prevented from being lifted when the lid body is opened, and the usability can be improved.

Further, in addition to the structure of claim 1, the rice cooker of the invention of claim 2 has a plurality of concave and convex portions formed on the surface of the lower surface member facing the pot, and the lower surface corresponding to the concave and convex portions. Since the lid heating device is provided on the inner surface of the member, not only the function and effect of claim 1 but also the surface area of the pot facing surface can be increased and the heating unevenness of the pot facing surface due to the lid heating device can be reduced. The upper space of the pan can be heated uniformly and the uneven cooking can be reduced. Further, it is possible to prevent dew condensation on the lower surface member during heat retention and prevent the soup from dripping on the rice.

Further, in addition to the structure of claim 1, the rice cooker of the invention of claim 3 further comprises a non-adhesive plastic coating on the surface facing the pan and a lid heating device on the inner surface. The function and effect of claim 1 and the lid are not limited by the fact that the melting temperature of the plastic coating is higher than the temperature of the lower surface member when the lower surface member is continuously heated by the lid heating device. Even if there is a failure in the control means of the heating device, the plastic coating does not peel off and repairability can be improved.

Further, in the method of manufacturing the lid lower surface member of the rice cooker according to the invention of claim 4, the lid lower surface member for covering the upper opening of the pot is formed of a metal material having a partially different material thickness. A method for manufacturing a lower surface member of a lid of a rice cooker, which comprises a molten metal solidified in a mold of a predetermined shape to form a lower surface member capable of freely improving the strength at a predetermined location. It can be manufactured.

Further, in the method for manufacturing the lid lower surface member of the rice cooker according to the fifth aspect of the present invention, the lid lower surface member for covering the upper opening of the pan is made of a metal material having a partially different material thickness. A method of manufacturing a lower surface member of a lid of a rice cooker, which is configured so that a uniform plate-shaped metal material is press-molded, so that the strength can be improved by work hardening and even without special equipment. It can be manufactured.

[Brief description of drawings]

FIG. 1 is an overall cross-sectional view of a rice cooker showing an embodiment of the present invention.

FIG. 2 is a sectional view of a lid lower surface plate showing an embodiment of the present invention.

FIG. 3 is a sectional view of a cover lower plate showing another embodiment of the present invention.

[Explanation of symbols]

 5 Pan 13 Upper opening 41 Lid 44 Lid bottom plate (bottom surface member) 44A Pan facing surface 44B Inner surface 47 Recess 47A Convex 48 Code heater (lid heating means) 53 Plastic coating

Claims (5)

[Claims] 1. A lower surface member of a lid that covers an upper opening of the pan is formed of a metal material having a partially different material thickness, and the lower surface member faces the pan facing the pan and the lid. The rice cooker is characterized in that the inner surface facing the inside of the rice cooker has a different surface shape. 2. A lid heating device is provided on the inner surface of the lower surface member, wherein a plurality of concave and convex portions are formed on a surface of the lower surface member facing the pot. The listed rice cooker. 3. A lower surface member when a plastic coating having non-adhesiveness is provided on the surface facing the pan and a lid heating device is provided on the inner surface, and the lower surface member is continuously heated by the lid heating device. The rice cooker according to claim 1, wherein the melting temperature of the plastic coating is set higher than the temperature of. 4. A method for manufacturing a lower surface member of a lid of a rice cooker, wherein the lower surface member of the lid covering the upper opening of the pot is formed of a metal material having a partially different material thickness. A method for manufacturing a lower surface member of a lid of a rice cooker, characterized in that it is configured to be solidified and molded in a mold having a predetermined shape. 5. A method for producing a lower surface member of a lid of a rice cooker, wherein the lower surface member of the lid covering the upper opening of the pan is formed of a metal material having partially different material thicknesses. A method for manufacturing a lower surface member of a lid of a rice cooker, characterized in that the plate-shaped metal material is press-molded.