JP3386000B2 - Electric rice cooker - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rice cooker, and more particularly to a structure of a lid of the electric rice cooker.

[0002]

2. Description of the Related Art A lid of an electric rice cooker, which is well known in the related art, has a synthetic resin upper plate and a lower plate joined to each other by high-frequency welding or the like at an outer peripheral portion thereof. The heat insulating lid has a structure in which a heat insulating material is arranged in the space formed in the above.

[0003]

In the case of the lid having the above-mentioned structure, the heat insulating effect is insufficient, and since it can be washed completely but cannot be disassembled, it is a sanitary problem when water or the like enters the inside. There is.

By the way, in recent years, a lid has been developed which comprises a synthetic resin upper plate forming an upper surface and a vacuum double structure forming a lower surface to improve the heat insulating effect. However, even in this case, cleaning the inside of the lid is a problem.

The present invention has been made in view of the above points, and by using a removable vacuum double structure as a component of the lid, the heat insulating effect is improved and disassembly and cleaning are facilitated. The purpose is to be able to.

[0006]

According to a first aspect of the present invention, as means for solving the above-mentioned problems, a rice cooker main body configured to be capable of accommodating a rice cooker in a freely removable manner, and a rice cooker main body of the rice cooker main body. In an electric rice cooker including a lid, the lid is
A vacuum double structure in which a vacuum space is formed between a synthetic resin upper plate that forms an upper surface and two upper and lower metal plates that are detachably supported by the upper plate and that have at least their outer peripheral portions joined to each other. It is composed by the body. With the above-described configuration, the heat insulating effect of the lid is improved, and cleaning is possible with the vacuum double structure removed, and the inside of the lid can be always kept clean.

As in the invention of claim 2, claim 1
In the electric rice cooker described, when the lower metal plate of the vacuum double structure constitutes the lower surface of the lid, the lower metal plate of the vacuum double structure can also serve as the lower metal plate of the vacuum double structure. The number of body parts can be reduced.

As in the invention of claim 3, claim 1
In the electric rice cooker according to any one of 1 and 2, when a heat sink that seals the opening of the rice cooker when the lid is closed is detachably attached to the lower surface of the lid, It is possible to suppress the growth of oneeba that occurs during rice cooking by radiating heat.

As in the invention of claim 4, claim 3
In the electric rice cooker described above, when a rice cooker lid facing the opening of the rice cooker is detachably attached to the lower surface of the heat sink, heat dissipation from the heat sink is moderated by interposing the rice cooker lid during heat retention. Therefore, it is possible to prevent the rice from drying and browning (that is, a phenomenon of turning brown). Also,
The heat retention effect is also improved.

[0010] As in the invention of claim 5, in the electric rice cooker according to any one of claims 1, 2, 3 and 4, the upper plate is a screw cylinder having a steam passage and an external screw. On the other hand, the screw cylinder is inserted into the vacuum double structure, and a through hole having an inner peripheral side joint portion of the two metal plates as an edge is formed, and the screw is inserted into the through hole. When the vacuum double structure is attached to the lid by tightening the inner peripheral side joint part with the screw ring screwed from below into the screw cylinder with the cylinder inserted, The vacuum double structure can be easily removed by screwing. Therefore, the lid can be washed in the state of being disassembled into the upper plate and the vacuum double structure, and the inside of the lid can be kept clean at all times. Moreover, since the screw cylinder has a structure that also serves as a steam passage, it is not necessary to specially form the steam passage.

As in the invention of claim 6, claim 5
In the electric rice cooker according to the description, the inner peripheral side joint portion of the vacuum double structure is covered with a seal member that secures a sealing property between the screw cylinder and the screw ring,
When the R portion is formed by polishing on the outer peripheral side joint portion of the vacuum double structure, when the vacuum double structure is removed and washed, fingers are placed on the inner peripheral side and the outer peripheral side of the vacuum double structure. There is no danger of damaging your fingers even if you touch it, improving safety.

As in the invention of claim 7, claim 5
In the electric rice cooker according to the description, the inner peripheral side joint portion of the vacuum double structure is covered with a seal member that secures a sealing property between the screw cylinder and the screw ring,
In the outer peripheral side joint portion of the vacuum double structure, when a curl-shaped portion that curves the outer end of one metal plate to cover the outer end of the other metal plate is formed, the vacuum double structure is formed. When detached and washed, there is no danger of the fingers being injured even if they touch the inner and outer peripheral sides of the vacuum double structure, and safety is improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

First Embodiment FIGS. 1 to 4 show an electric rice cooker according to a first embodiment of the present invention.

As shown in FIG. 1, this electric rice cooker is made of a synthetic resin which constitutes an outer case 4 forming an outer peripheral surface and an inner peripheral surface and is capable of accommodating a rice cooker 5 made of a magnetic material. Rice cooker main body 1 constituted by a protective frame 6 made of rice, a lid 2 of the rice cooker main body, and an electromagnetic wave located on the outer peripheral side of the protective frame 6 and serving as a heating means for heating the rice cooker 5. The induction coil 3 is provided.

The outer case 4 has a body portion 4a serving as a side peripheral surface of the rice cooker body 1 and a shoulder portion 4b serving as a connecting portion with an upper edge of the protective frame 6, and a bottom portion of the rice cooker body 1. In the present embodiment, the body portion 4a and the shoulder portion 4b are integrally formed by synthetic resin, and the bottom portion 4c is a separate structure. In some cases, the body portion 4a and the bottom portion 4c may be integrally formed of synthetic resin, and the shoulder portion 4b may be separately formed.

The upper portion of the outer case 4 on the front side of the body portion 4a is gently inclined, and an operation panel portion 7 is provided at that portion. Therefore, a relatively large front space portion 8 is formed below the operation panel portion 7 between the outer case 4 and the protection frame 5. The operation panel section 7 is provided with various operation switches and a liquid crystal display section for displaying a setting state set by the various operation switches. The operation board 9 is provided inside the operation panel unit 7.
Is provided. The operation board 9 is fixed to the outer case body 4a with screws 14 in a tilted state so as to be substantially parallel to the operation panel section 15 with a board holder 15
Supported by.

The protective frame 6 has a bottomed cylindrical shape, and has a gentle curved surface 6c from the side peripheral surface 6a to the bottom surface 6b thereof.

Annular electromagnetic induction coils 3 and 3 are provided on the bottom surface 6b and the back surface of the curved surface 6c of the protective frame 6, respectively. The electromagnetic induction coils 3 and 3 are coupled to each other on the lower surface of the central portion of the bottom surface 6b of the protective frame and extend radially along the protective frame 6 with the coil die 10 and protective frame 6.
It is positioned so as to be sandwiched between and. That is, the electromagnetic induction coils 3 and 3 have a shape that follows the shape of the outer peripheral surface of the protective frame 6. Reference numeral 11 is a ferrite core that is supported by the lower surface of the central portion of the coil die 10 and extends radially, and acts to block downward magnetism. Reference numeral 12 is a center sensor which functions as a temperature detecting means for detecting the temperature of the rice cooker 5, and 13 is a heat retaining heater.

A shoulder ring 16 made of synthetic resin is attached to the inner peripheral edge of the shoulder portion 4b of the outer case 4 by force fitting, and the upper surface of the shoulder ring 16 is made of metal having a shoulder heater 17. The heater ring 18 is attached. As will be described later, the outer peripheral edge of the heat dissipation plate 57 attached to the lower surface of the lid 2 is pressed against the upper surface of the heater ring 18 when the lid 2 is closed.

On the inner peripheral portion of the shoulder ring 16, a hanging wall 16a is integrally formed so as to extend down to the upper edge of the protective frame 6, and the hanging wall 16a and the upper edge of the protective frame 6 are integrally formed. An air passage 19 is formed between the edge and the edge. The air passage 19 is communicated with a gap S formed between the protective frame 6 and the rice cooker 5 via a vent 20 formed in the hanging wall 16a.

A fan 22 for cooling a rice cooker is arranged at the center of a rear space 21 formed between the back side of the outer case 4 and the back side of the protective frame 6. Cooling air from the cooling fan 22 is supplied to the air passage 19 via the duct 23 and is supplied to the gap S from the vent 20 to cool the outer peripheral surface of the rice cooker 5. The cooling of the rice cooker 5 is performed, for example, from the completion of cooking to the transition to the target heat retention temperature or at a predetermined time determined to be necessary during the heat retention step.

At a position below the operation panel portion 7 in a front space portion 8 formed between the outer case 4 and the protective frame 6, a power supply board 24 having various electronic parts is arranged vertically. It is arranged in a posture. The power supply board 24
Is attached to the shoulder portion 4b of the outer case 4 by a screw (not shown) in a vertical posture, and is attached to the substrate holder 25.

A heat sink 26 for promoting heat dissipation from the power source board 24 and a cooling fan 27 for cooling the heat sink 26 are integrally attached to the power source board 24. In this way, the power supply board 24
Further, since the heat sink 26 and the cooling fan 27 are integrated, the height of the product can be made compact. Reference numeral 28 is a hollow portion that houses the lower portion of the cooling fan 27.

On the other hand, the lid 2 is openably and closably attached to the rear portion of the outer case shoulder portion 4b (that is, the opposite side of the operation panel portion 7) via a hinge unit 29 so as to be detachable. It is made up of a synthetic resin upper plate 30 forming an upper surface and a vacuum double structure 31 forming a lower surface.

As shown in FIGS. 2 and 3, an opening 32 into which a pressure adjusting cap 46, which will be described later, is removably inserted is formed at a substantially central portion of the upper plate 30, and the opening 32 is formed.
A screw cylinder 33 having an outer screw 33a on the outer periphery is integrally attached to the rim of the device by high frequency welding. Also,
A cavity 34 is formed in the upper plate 30 by gas injection for the purpose of reducing the weight and improving the heat retention performance, and the gas injection port 35 to the cavity 34 is closed by a closing member 36. . With this configuration, even when the lower surface of the upper plate 30 is exposed, the gas injection port 35
Disappears and looks good.

The vacuum double structure 31 is constructed by forming a vacuum space 39 between two upper and lower doughnut-shaped metal plates 37 and 38 whose inner and outer peripheral portions are joined to each other. Inner peripheral side joint portion 31a of the vacuum double structure 31
Is covered with a seal member 40 and is fitted into the outer circumference of the screw cylinder 33. On the other hand, at the outer end of the outer peripheral side joint portion 31b of the vacuum double structure 31,
The R portion 41 is formed by polishing. Further, a donut-shaped flat portion 37a having a step with respect to the inner peripheral side portion is formed on the outer peripheral side portion of the upper metal plate 37 constituting the vacuum double structure 31 in order to secure strength. There is.
A vacuum exhaust hole 42 sealed with a brazing material after vacuum exhaust is formed in the flat surface portion 37a. On the other hand, the seal packing 6 to be described later secures strength at a position from the outer periphery of the lower metal plate 38 constituting the vacuum double structure 31.
A vertical wall portion 38a that serves as an abutting portion of 7 is formed. Reference numeral 43 is a getter.

In the vacuum double structure 31, the screw ring 33 having an inner screw 44a is screwed onto the screw cylinder 33 while the screw cylinder 33 is fitted in the inner peripheral joint 31a. It is installed by. That is, the vacuum double structure 31 can be attached to and detached from the upper plate 30 by screwing the screw ring 44.

Further, in the screw cylinder 33, a pressure adjusting cylinder 45 is provided.
Is detachably attached, and the upper side of the pressure regulating cylinder 45 is covered with a pressure regulating cap 46 which is removably fitted in the opening 32. The pressure adjusting cap 46 includes a cap body 47 having a tubular portion 47 a that is fitted into the opening 32, and a cover member 48 attached so as to cover the upper surface of the cap body 47. An aluminum thin plate 49 processed by Sumiflon is attached to the upper surface of the. Reference numeral 50 is a steam inlet to the pressure adjusting cylinder 45, 51 is a steam outlet from the pressure adjusting cylinder 45, 52 is a steam outlet in the pressure adjusting cap 46, 53 is a ball valve, 54
Is a seal packing attached to the outer periphery of the pressure adjusting cylinder 45,
Reference numeral 55 denotes a seal packing attached to the outer circumference of the cylinder portion 47a of the cap body 47 of the pressure adjusting cap 46, and 56 is provided on the inner circumference of the screw cylinder 33 so as to lock the seal packing 55 of the pressure adjusting cylinder 45. It is an annular protrusion. By doing so, even if oneeva or the like overflows from the steam outlet 51 of the pressure regulating cylinder 45, it will be returned downward without overflowing from the steam outlet 52 of the pressure regulating cap 46.
It can give a high-class feeling. Further, since the upper surface of the pressure adjusting cap 46 is covered with the aluminum thin plate 49 that has been subjected to the Sumiflon process, the maintenance is easy.

At the lower end of the pressure adjusting cylinder 45, a heat radiating plate 57 whose outer peripheral edge is pressed against the upper surface of the heater ring 18 when the lid 2 is closed is attached by three rivets 58, 58, 58. ing. The heat radiating plate 57 is made of a heat conductive metal and is heated by heat conduction from the shoulder heater 17 attached to the heater ring 18. As shown in FIG. 4, the rivets 58, 58, 58 are arranged on a virtual circle at equal intervals. Further, projections 59.59, 59 located between the rivets 58, 58, 58 and penetrating the heat dissipation plate 57 are integrally provided at the lower end of the pressure adjusting cylinder 45. The projections 59, 59, 59 are to be brought into contact with the upper surface of the rice cooker lid when swinging the rice cooker lid, which will be described later.

A rising portion 60 that is bent upward is formed at a position near the outer periphery of the heat dissipation plate 57, and an upper end of the rising portion 60 is provided at an outer peripheral end so as to contact the heater ring 18. An abutting portion 61 extending toward is integrally provided. The rising portion 60 is integrally formed with a locking projection 62 formed by protruding the upper and lower intermediate portions outward. The inside of the locking projection 62 is a locking recess 63.

A seal packing 64 for sealing the opening of the rice cooker 5 when the cover 2 is closed is attached to the locking projection 62 by a packing ring 65. Also,
The locking recess 63 is pressed against the vertical wall portion 37a of the lower metal plate 37 of the vacuum double structure 31 to be pressed against the heat dissipation plate 5.
A mounting ring 66 for mounting a seal packing 67 that seals the gap between the outer ring 7 and the outer ring 7 is fixed by force fitting. That is, the rice cooker 5 with the rising portion 60 sandwiched therebetween.
Seal packing 65 for sealing between the vacuum double structure 31 and the seal packing 6
7 and 7 are attached. Reference numeral 68 is a steam port formed in the heat dissipation plate 57.

A support rod 69 is provided at the center of the heat dissipation plate 57, and the rice cooker lid 7 is attached to the support rod 69.
0 is detachably attached via a seal packing 71. The rice cooker lid 70 is made of a heat-conductive metal having a diameter slightly smaller than the opening diameter of the rice cooker 5, and is positioned below the opening edge of the rice cooker 5 when the lid 2 is closed. Has become. By doing so, the heat from the shoulder heater 17 is transferred to the heat radiating plate 57 via the heater ring 18, and the radiant heat from the heat radiating plate 57 is indirectly transmitted via the space between the rice cooker lid 70. It is transmitted to the rice cooker lid 70, and is further radiated from the rice cooker lid 70 to the cooked rice in the rice cooker 5. Therefore, the cooked rice is uniformly and softly heated, and proper heat retention that does not cause browning or the like can be performed. Reference numeral 72 is a steam port formed in the rice cooker lid 70.

In FIG. 1, reference numeral 73 is a handle for carrying, 74 is a lock mechanism for holding the closed state of the lid body 7,
5 is a heat insulating material.

In the electric rice cooker configured as described above, the following operational effects can be obtained.

After removing the lid body 2 of this electric rice cooker from the rice cooker body 1, as shown in FIG. 3, the heat sink 57 is removed from the lid body 2 and the screw ring 44 is unscrewed from the screw cylinder 33. The vacuum double structure 31 is removed from the plate 30. Further, the rice cooker lid 70 is also removed from the heat dissipation plate 57, and the pressure adjustment cap 46 is also removed from the upper plate 30. Therefore, the lid 2 includes the upper plate 30 and the vacuum double structure 3
In addition to being disassembled into 1, the heat dissipation plate 57, the rice cooker lid 70, and the pressure adjusting cap 46 can also be separated, and the inside can be washed at the time of washing. That is, the inside of the lid 2 can be always kept clean.

Further, the inner peripheral side joint portion 31a of the vacuum double structure 31 is covered with a seal member 40 for ensuring a sealing property between the screw cylinder 33 and the screw ring 44, while the vacuum double structure 31 is provided. Outer peripheral side joint portion 31 in
Since the R portion 41 is formed on b by polishing, when the vacuum double structure 31 is removed and washed, even if the fingers touch the inner peripheral side and the outer peripheral side of the vacuum double structure 31, the fingers cannot be touched. There is no risk of damage and safety is improved.

Further, the heat radiation plate 57 is attached to the vacuum double structure 31.
Since the seal packing 67 for sealing between the upper plate 3 and the heat dissipation plate 57 and the vacuum double structure 31 is provided,
It is possible to prevent hot air and steam from escaping to the 0 side.

By the way, when the lid 2 is opened and closed, the rice cooker lid 70 is opened.
Swings around the seal packing 71, and the rice cooker lid 70
There is a possibility that the outer peripheral end of the container will come into contact with the heat dissipation plate 57 to generate a metallic sound, but in the case of the present embodiment, the projection 59 projecting from the pressure regulating cylinder 45 is first contacted with the rice cooker lid 70. Therefore, the outer peripheral edge of the rice cooker lid 70 does not come into contact with the heat dissipation plate 57.

Second Embodiment FIG. 5 shows a lid of an electric rice cooker according to a second embodiment of the present invention.

In this case, the vacuum double structure 31 and the heat sink 5
The seal packing 67 for sealing the gap between the seal packing 67 and the seal 7 is provided at the lower end of the seal packing 67 with the projection 7 penetrating the heat dissipation plate 57.
6 is integrally projected. The protrusion 76 serves as a support portion for attaching the seal packing 67 to the heat dissipation plate 57, and when the rice cooker lid 70 swings around the seal packing 71 when the lid 2 is opened and closed, the rice cooker lid 70 is covered. Before the outer peripheral edge contacts the heat sink 57, the outer peripheral edge of the rice cooker lid 70 is prevented from coming into contact with the heat sink 57 and coming into contact with the rice cooker lid 70. Therefore, the mounting ring 65 in the first embodiment is omitted. Further, one metal plate (that is,
A curled portion 77 is formed by curving the outer end of the lower metal plate 38) and covering the outer end of the other metal plate (that is, the upper metal plate 37). The curled portion 77 may be formed on the outer end of the upper metal plate 37. In this way, when the vacuum double structure 31 is removed and washed, there is no risk of damaging the finger even if the finger touches the outer peripheral side of the vacuum double structure 31, and safety is improved. Other configurations and effects are the same as those in the first embodiment, and the description thereof will be omitted.

Third Embodiment FIG. 6 shows a lid of an electric rice cooker according to a third embodiment of the present invention.

In this case, the outer peripheral joint portion 31b of the vacuum double structure 31 is covered with a seal packing 78 for sealing the gap with the heat dissipation plate 57. Therefore, the seal packing 67 in the first embodiment is omitted. In this way, the heat dissipation plate 57 and the vacuum double structure 3
It is possible to prevent the escape of hot air or steam from between 1 and the upper plate 30 side, and when removing and cleaning the vacuum double structure 31, a finger is placed on the outer peripheral side of the vacuum double structure 31. There is no danger of damaging your fingers even if you touch it, improving safety. Other configurations and effects are the same as those in the first embodiment, and the description thereof will be omitted.

In the present embodiment, the electromagnetic induction coil is used as the heating means, but the present invention is of course applicable to the electric heater used as the heating means.

[0045]

According to the invention of claim 1, in an electric rice cooker comprising a rice cooker main body configured to be able to store the rice cooker freely and a lid of the rice cooker main body, A lid body is formed with a vacuum space between a synthetic resin upper plate forming an upper surface and two upper and lower metal plates that are detachably supported on the upper plate and have at least outer peripheral portions joined to each other. Since it is composed of a vacuum double structure, the heat insulation effect in the lid is improved, and it becomes possible to wash with the vacuum double structure removed, and it is possible to keep the inside of the lid clean at all times. The effect is that you can do it.

As in the invention of claim 2, claim 1
In the electric rice cooker described, when the lower metal plate of the vacuum double structure constitutes the lower surface of the lid, the lower metal plate of the vacuum double structure can also serve as the lower metal plate of the vacuum double structure. The number of body parts can be reduced.

As in the invention of claim 3, claim 1
In the electric rice cooker according to any one of 1 and 2, when a heat sink that seals the opening of the rice cooker when the lid is closed is detachably attached to the lower surface of the lid, It is possible to suppress the growth of oneeba that occurs during rice cooking by radiating heat.

As in the invention of claim 4, claim 3
In the electric rice cooker described above, when a rice cooker lid facing the opening of the rice cooker is detachably attached to the lower surface of the heat sink, heat dissipation from the heat sink is moderated by interposing the rice cooker lid during heat retention. Therefore, it is possible to prevent the rice from drying and browning (that is, a phenomenon of turning brown). Also,
The heat retention effect is also improved.

[0049] As in the invention of claim 5, in the electric rice cooker according to any one of claims 1, 2, 3 and 4, the upper plate is a screw cylinder having a steam passage and an external screw. On the other hand, the screw cylinder is inserted into the vacuum double structure, and a through hole having an inner peripheral side joint portion of the two metal plates as an edge is formed, and the screw is inserted into the through hole. When the vacuum double structure is attached to the lid by tightening the inner peripheral side joint part with the screw ring screwed from below into the screw cylinder with the cylinder inserted, The vacuum double structure can be easily removed by screwing. Therefore, the lid can be washed in the state of being disassembled into the upper plate and the vacuum double structure, and the inside of the lid can be kept clean at all times. Moreover, since the screw cylinder has a structure that also serves as a steam passage, it is not necessary to specially form the steam passage.

As in the invention of claim 6, claim 5
In the electric rice cooker according to the description, the inner peripheral side joint portion of the vacuum double structure is covered with a seal member that secures a sealing property between the screw cylinder and the screw ring,
When the R portion is formed by polishing on the outer peripheral side joint portion of the vacuum double structure, when the vacuum double structure is removed and washed, fingers are placed on the inner peripheral side and the outer peripheral side of the vacuum double structure. There is no danger of damaging your fingers even if you touch it, improving safety.

As in the invention of claim 7, claim 5
In the electric rice cooker according to the description, the inner peripheral side joint portion of the vacuum double structure is covered with a seal member that secures a sealing property between the screw cylinder and the screw ring,
In the outer peripheral side joint portion of the vacuum double structure, when a curl-shaped portion that curves the outer end of one metal plate to cover the outer end of the other metal plate is formed, the vacuum double structure is formed. When detached and washed, there is no danger of the fingers being injured even if they touch the inner and outer peripheral sides of the vacuum double structure, and safety is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electric rice cooker according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a lid body in the electric rice cooker according to the first embodiment of the present invention.

FIG. 3 is an exploded cross-sectional view of a lid of the electric rice cooker according to the first embodiment of the present invention.

FIG. 4 is a bottom view showing the main part of the heat dissipation plate in the electric rice cooker according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view of a lid body in an electric rice cooker according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a lid of an electric rice cooker according to a third embodiment of the present invention.

[Explanation of symbols]

1 is a rice cooker main body, 2 is a lid, 5 is a rice cooker, 30 is a top plate, 3
1 is a vacuum double structure, 31a is an inner peripheral side joint portion, 31b is an outer peripheral side joint portion, 33 is a screw cylinder, 33a is an outer screw, 37,
38 is a metal plate, 39 is a vacuum space, 40 is a sealing member, 4
Reference numeral 1 is an R portion, 44 is a screw ring, 57 is a heat radiating plate, 67 is a seal packing, 77 is a curled portion, and 78 is a seal packing.

Claims (7)

(57) [Claims] 1. An electric rice cooker comprising a rice cooker main body configured to be able to store the rice cooker freely and a lid body of the rice cooker main body, wherein the lid body forms an upper surface. A synthetic resin upper plate, and a vacuum double structure in which a vacuum space is formed between two upper and lower metal plates that are detachably supported by the upper plate and that have at least their outer peripheral portions joined to each other. An electric rice cooker characterized by being configured. 2. The electric rice cooker according to claim 1, wherein a lower metal plate of the vacuum double structure constitutes a lower surface of the lid. 3. A heat-dissipating plate for detachably mounting an opening of the rice cooker when the lid is closed, is detachably attached to the lower surface of the lid. The electric rice cooker described in paragraph 1. 4. The electric rice cooker according to claim 3, wherein a rice cooker lid facing the opening of the rice cooker is detachably attached to the lower surface of the heat dissipation plate. 5. The upper plate is formed with a screw cylinder that also serves as a vapor passage and has an external screw, while the vacuum double structure has the screw cylinder inserted therein and the two metal plates. While forming a through hole with the inner peripheral side joint part of the as the rim,
The vacuum double structure is attached to the lid by tightening the inner peripheral side joint portion with a screw ring screwed from below into the screw cylinder in a state where the screw cylinder is inserted into the through hole. The electric rice cooker according to any one of claims 1, 2, 3 and 4, which is provided. 6. The inner peripheral joint portion of the vacuum double structure is covered with a seal member for ensuring sealing performance between the screw cylinder and the screw ring, while the outer periphery of the vacuum double structure is covered. The electric rice cooker according to claim 5, wherein an R portion is formed on the side joint portion by polishing. 7. The inner peripheral joint portion of the vacuum double structure is covered with a seal member for ensuring a sealing property between the screw cylinder and the screw ring, while the outer periphery of the vacuum double structure is covered. The electric rice cooker according to claim 5, wherein the side joint portion is formed with a curl-shaped portion that curves the outer end portion of one metal plate and covers the outer end portion of the other metal plate.