Electric heating – Inductive heating – With heat exchange
Reexamination Certificate
1998-06-11
2001-01-23
Leung, Philip H. (Department: 3742)
Electric heating
Inductive heating
With heat exchange
C219S626000, C219S665000, C219S490000, C099S325000
Reexamination Certificate
active
06177659
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rice cooker having a microcomputer for general household or professional use.
BACKGROUND OF THE INVENTION
Recently, rice cookers for cooking rice with high power for enhancing the rice cooking performance have been developed and distributed widely. There are also rice cookers capable of cooking rice at different levels of softness by the same amount of water.
Conventionally, this kind of rice cooker was composed as shown in FIG.
12
. In
FIG. 12
, a body (rice cooker main body)
1
is a cylindrical structure having an open top, and inside of the body
1
is disposed a protective frame
2
which accommodates an inner pan
3
. The protective frame
2
is a cylindrical structure with a bottom made of nonmetallic material, and the upper end of the protective frame
2
is engaged with the inner circumference of the upper end of the body
1
.
The inner pan
3
has a flange
4
projecting outside at the opening of the upper end, and this inner pan
3
is disposed detachably in the protective frame
2
, by mounting the flange
4
on the top of an upper frame
5
in a suspended state. At the outside of the protective frame
2
, an induction coil
6
for heating the inner pan
3
is disposed, and this induction coil
6
is supported by a coil cover
7
formed of a heat resistant resin material in the lower part of the outer circumference of the protective frame
2
so that the distance to the outer circumference of-the inner pan
3
may be constant. In the center of the induction coil
6
, a pan sensor
8
for detecting the temperature of the inner pan
3
is disposed.
An outer lid
9
made of synthetic resin is rotatably supported on a hinge member
10
formed integrally on the top of the upper frame
5
through a pin
11
. An inner cover
12
is affixed at the inside of the outer lid
9
. A heat releasing plate
13
, being a heating element, is fixed to the inner cover
12
, and an induction coil
15
supported by a coil support stand
14
is positioned on the top of this heat releasing plate
13
. By the electromagnetic action of this induction coil
15
, the heat releasing plate
13
generates heat. To this heat releasing plate
13
, a lid sensor
16
for detecting the temperature of the heat releasing plate
13
is directly adhered with an aluminum tape, and the temperature of the heat releasing plate
13
is detected.
An engaging member
17
is positioned on the opposite side of the hinge member
10
and is formed integrally on the upper end of the protective frame
2
, and confronting to this engaging member
17
, an engaging lever
18
is rotatably supported on the outer lid
9
through a lever pin
19
. A pan packing
20
is to enclose the inner pan
3
by pressing to the flange
4
of the inner pan
3
when the outer lid
9
is closed. A steam tube
21
provided in the center of the outer lid
9
is to prevent rice gruel from boiling over to outside.
A control board
22
is to control power feed to the induction coils
6
,
12
, and also control input and output of signals from the pan sensor
8
and lid sensor
16
and signal of operation display unit
23
provided before the top of the body
1
. A cooling fan
24
is to cool the induction coil
6
and control board
22
. The control board
22
judges the amount of rice and water in the inner pan
3
in the rice cooking amount judging process while cooking rice by the temperature detection signal from the lid sensor
16
, and determines the power feed state to the induction coil
6
depending on the result of judging.
In the conventional rice cooker having such constitution, however, the size of the body
1
is large for the inner pan
3
of the rice cooker, and it is not convenient for carrying or installing, or owing to the recent increase in the number of cooking software, the number of operation keys increases and when large keys are used for the ease of handling, the size of the entire rice cooker further becomes larger.
On the other hand, when much water is used in cooking rice, it boils over, and the power supply in cooking is stopped before boiling over. However, unless power is supplied in cooking, the temperature rise of rice is not sufficient, and the taste may be sometimes slightly inferior.
Besides, when detaching or attaching the inner pan
3
, it is necessary to open or close the outer lid
9
, and particularly when closing the outer lid
9
, the front side of the body
1
on the top of the outer lid
9
must be held down, and if the operation display unit
23
is located on the top of the outer lid
9
in a range possibly held by hand, an operation key may be pressed by mistake.
Moreover, since the heat is high, to cook the rice soft, in particular, if more water is added than usual for cooking rice, it often causes boiling-over.
SUMMARY OF THE INVENTION
It is hence a first object of the invention to realize a rice cooker of compact structure which does not boil over.
It is a second object of the invention to realize a rice cooker constituted so as to prevent wrong operation if the operation unit is touched by mistake when closing the lid.
It is a third object of the invention to realize a rice cooker capable of preventing boiling-over, without lowering the rice cooking performance, by detecting rice gruel rising over the inner pan.
To achieve the objects, the rice cooker of the invention comprises a rice cooker main body (hereinafter called main body), an inner pan detachably accommodated in the main body, a lid to cover the upper opening of the main body, and rice gruel detecting means for detecting flow of rice gruel in cooking rice. Preferably, the rice gruel detecting means is composed of a float and a float detecting unit, and the rice gruel detecting means is preferably provided in the lid, or in a passage of rice gruel, that is, in the steam tube of the lid or in the upper part of the inner pan.
In this constitution, the entire rice cooker is made compact, and the convenience of installation and carrying is much improved, and since the steam tube can be easily detached from the lid and cleaned, so that an easy-to-clean and easy-to-handle rice cooker is presented. Still more, by adjusting the heating amount depending on the rising state of rice gruel, boiling-over can be prevented, and a favorable rice cooking performance is always obtained.
In the rice cooker of the invention, it is preferred to be constituted so as to supply electric power to the inner pan continuously until the rice gruel detecting means operates, to supply again when rice gruel is no longer possible to flow out of the rice cooker. In this constitution, when finishing cooking, sufficient heating can be applied to rice and water, and tasty rice is cooked, and the taste of the cooked rice is improved.
The rice cooker of the invention is preferred to comprise a bottom heating coil for induction heating of the inner pan, control means for controlling supply of high frequency power to the bottom heating coil, a steam tube disposed in the lid for exhausting the steam generated in the inner pan, and rice gruel detecting means disposed in the steam tube. By controlling the power supply amount to the bottom heating coil depending on the detecting state of the rice gruel detecting means, boiling-over of rice gruel can be effectively prevented in a compact steam tube size.
Preferably, the rice gruel detecting means is constituted so as to make use of the move of a float moving due to opening and closing of the lid and expansion and contraction of rice gruel generated in the inner pan. As a result, generation of rice gruel can be detected in a simple constitution. Preferably, the rice gruel detecting means comprises a float made of columnar or spherical ferrite disposed so as to roll over a slope provided in the bottom of the steam tube, and a float detecting unit composed of a lead switch for detecting the float. Moreover, preferably, the slope has a groove for flow of rice gruel, and also has a convex portion for the float to move along the groove. Therefore, the structure is also sui
Hamada Hironori
Korai Atsushi
Koyama Masahiro
Ukida Kazuhiro
Yagi Masatoshi
Leung Philip H.
Matsushita Electric Industrial Co. Ltd
Ratner & Prestia
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