Steam exhaust system of an electric pressurizing rice cooker

Details Steam exhaust system of an electric pressurizing rice cooker Steam exhaust system of an electric pressurizing rice cooker

2001-02-22

2001-09-04

Simone, Timothy F. (Department: 1761)

Foods and beverages: apparatus

Cooking

Intercontrol or safety control

C099S333000, C099S338000, C099S342000, C099S403000, C219S435000, C219S441000, C219S492000, C219S494000

Reexamination Certificate

active

06283015

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electric pressurizing rice cooker, and more particularly to a steam exhaust system of an electric pressurizing rice cooker, which can control the pressure in a cooking vessel and simultaneously can prevent the pressure in the cooking vessel from excessively elevating during the cooking process.
2. Description of the Related Art
An electric rice cooker is an appliance for cooking rice which utilizes electricity as a heating source. Especially in an electric pressurizing rice cooker, the interior of a cooking vessel is maintained at a relatively high pressure, higher than that of the atmosphere, so that the cooking in the cooking vessel can be rapidly performed.
As shown in
FIG. 1
, a conventional electric pressurizing rice cooker includes a cooking vessel
10
, a cooker housing
12
in which the cooking vessel
10
is accommodated, a lid
14
for opening and closing the cooker housing
12
, an electric system for heating/warming the cooking vessel
10
, and a steam exhaust system for controlling the pressure in the cooking vessel
10
during the course of cooking.
Referring to
FIG. 2
, the electric system includes a working coil
16
and a heater
18
disposed in the cooker housing
12
. The working coil
16
generates induced currents for cooking, and the heater
18
functions to generate relatively less heat for warming rice in a so-called warming mode.
Meanwhile, the steam exhaust system includes a solenoid valve
20
and a poise valve
30
. The solenoid valve
20
is automatically opened to lower the pressure in the cooking vessel
10
when a predetermined amount of time has passed after the cooking is initiated. The poise valve
30
is opened when the pressure in the cooking vessel
10
exceeds a predetermined value during the course of cooking to prevent the pressure in the cooking vessel from excessively elevating, and simultaneously to maintain the pressure constant.
As shown in
FIG. 3
, the solenoid valve
20
is disposed at a top plate
141
of the lid
14
, and includes a first steam exhaust pipe
22
interconnected to the exterior of a top cover
142
, a diaphragm
24
for opening and closing a steam hole
22
a
in the first steam exhaust pipe
22
, a plunger
26
assembled with the diaphragm
24
, and a solenoid coil
28
for actuating the plunger
26
.
The poise valve
30
as described above includes a second steam exhaust pipe
32
penetrating through the lid
14
, and a pressurizing weight
34
disposed at the upper end of the second steam exhaust pipe
32
outside of the lid
14
.
The pressurizing weight
34
supports a valve pin
35
received through the top of the pressurizing weight
34
, in such a manner that the valve pin
35
can open and close the upper end of a steam exhaust channel
32
a
of the second steam exhaust pipe
32
. The pressurizing weight
34
has an exhaust port
34
a
formed through the bottom of the pressurizing weight
34
, through which steam can be exhausted.
Hereinafter, will be described the cooking operation by the electric pressurizing rice cooker having the construction as described above.
At first, the working coil
16
induces eddy current at the cooking vessel
10
, which slowly heats the cooking vessel
10
, so as to promote a so-called soaking process during which water is absorbed in each grain of rice. After the soaking process is performed for a predetermined period, the cooking vessel is heated at a high temperature, so that the temperature of the water in which the rice is immersed is rapidly elevated to the boiling point.
In this case, the upper end of the cooking vessel
10
is firmly coupled to the lower surface of the top plate
141
by an assembling device (not shown), and the solenoid valve
20
and the poise valve
30
, which are parts of the steam exhaust device, are maintained in a closed position. Accordingly, when the boiling process is initiated and the water begins to boil, steam is generated to make the pressure in the cooking vessel
10
higher than that in the atmosphere.
Due to the increase of the pressure in the cooking vessel
10
, the temperature in the cooking vessel
10
elevates beyond the boiling point of 100° C. at the normal atmospheric pressure, so that the rice is cooked faster than at normal atmospheric pressure.
When the boiling process during a predetermined period is completed, a steaming process is initiated in the state where the heating is stopped. In the steaming process, the rice is steamed, without being separately heated, by the steam remaining in the cooking vessel after the boiling process, usually after the water is completely boiled away.
After the steaming process is completed for a predetermined amount of time, the steam in the cooking vessel
10
is exhausted by the operation of the solenoid valve
20
, so that the pressure in the cooking vessel
10
is lowered. In this state, a warming process is initiated in which the cooking vessel
10
is heated by a relatively low degree of heat, at a relatively low, constant temperature by means by the heater
18
.
In this case, when the solenoid valve
20
is operated, electric power is first applied to the solenoid coil
28
by a control section (not shown). Then, magnetic force generated by the solenoid coil
28
actuates the plunger
26
, which elastically deforms the diaphragm
24
to open the steam hole
22
a
. Then, the steam in the cooking vessel
10
is exhausted through the opened steam hole
22
a
and steam channel of the first steam exhaust pipe
22
interconnected to the steam hole
22
a.
Further, when the pressure in the cooking vessel
10
becomes higher than a predetermined reference value during the course of the cooking operation, the poise valve
30
is operated to exhaust a desired amount of steam in the cooking vessel
10
, thereby preventing an excessive elevation of pressure.
Hereinafter will be described, in detail, the operation of the poise valve
30
as described above.
First, before the pressure in the cooking vessel
10
reaches a predetermined reference value, the steam exhaust channel
32
a
of the second steam exhaust pipe
32
is maintained closed by the valve pin
35
. This is because the valve pin
35
is forced downward due to the weight of the pressurizing weight
34
so as to block off the steam exhaust channel
32
a
. When the pressure in the cooking vessel
10
exceeds the reference value, that is, the weight of the pressurizing weight
34
, the valve pin
35
is pushed upward causing the pressurizing weight
34
to vibrate and become cooked. The steam exhaust channel
32
a
is then opened, whereby the steam in the cooking vessel
10
is exhausted through the exhaust port
34
a
of the pressurizing weight
34
. The pressure in the cooking vessel
10
is then lowered below the reference value.
When the pressure in the cooking vessel
10
is lowered below the reference value, the pressurizing weight
34
recovers its balance due to its construction, so that the valve pin
35
again blocks off the steam exhaust channel
32
a
, thereby preventing an excessive pressure reduction. The repetition of the above process maintains the pressure in the cooking vessel
10
in a predetermined range during the cooking process.
In the conventional electric pressurizing rice cooker as described above, effective cooking is achieved through the safe operation of and the pressure control of the steam exhaust system.
However, according to the conventional technique as described above, since the poise valve
30
maintains the pressure in the cooking vessel
10
at a predetermined level by means of the operation of the pressurizing weight
34
during the cooking operation, only pressurized cooking at a single predetermined pressure can be performed. Accordingly, there is a restriction in the conventional electric pressurizing rice cooker, in that it is impossible to cook food into various states according to the user's tastes by controlling the pressure in the cooking vessel
10
.
Further, the conventional electric pressu

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