Note: Descriptions are shown in the official language in which they were submitted.
CA 02889658 2015-04-27
[Specification]
[Title of the invention]
Cooking appliance having thermal decomposition function
[Field of the invention]
The present invention relates to a combustion device that can remove odor-
producing
materials in the cooking cavity. Specifically, the present invention relates
to a heating means in
the cooking cavity that can cause thermal decomposition of odor-producing
materials, in addition
to cooking the food by radiation of its heat.
[Description of related arts]
When food is heated in a cooking device, steam and volatile fumes are
generated from the
food. These volatile fumes may contain carcinogenic formaldehyde and a variety
of toxic
materials which may be harmful to human health. To minimize the adverse
effects of using the
cooking device, these toxic contaminants should be prevented from spreading
into the living area
of the user. Although range hoods are installed in many homes to vent cooking
fumes, only a
portion of the cooking fumes are discharged outside and the rest may diffuse
into the kitchen and
other living areas.
A number of different ways for disposing cooking fumes such as adsorption
method using
activated carbon filters, a combustion method, a catalytic converter method,
an ionic
precipitation method, and a plasma discharging method are well known. Among
these, the
combustion method is highly effective in removing cooking fumes, which are
oxidized at high
temperature to yield harmless carbon dioxide and water. Also, the combustion
method is proven
to be economical and reliable enough to be used for the incineration of toxic
chemical and
biological wastes.
Some of the cooking ovens have self-cleaning functions to cause pyrolysis at
temperatures of
about 400 - 500 C in order to remove food contaminants accumulated on the
wall of the cooking
cavity. However, the above case adopts a method of re-heating the cooking
cavity after taking
out the food and cannot solve the problem of diffusing fumes during cooking.
Therefore, a
device for effectively removing contaminants generated during cooking is
desired.
To solve the above problems, the present invention provides cooking device for
effectively
removing cooking fumes in the cooking cavity. An object of the present
invention is to provide
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an energy efficient combustion device which includes a heating means adapted
to heat up food in
the cooking cavity and to provide a cleaning effect. Another object of the
present invention is to
keep the user safe from the harmful cooking fumes by removing the fumes
immediately as soon
as they are generated in the cooking cavity.
The following patents are known in the art and are incorporated by reference
herein: Korean
Pat. Nos. 10-0518444; 10-0555420, 10-1203444; and U.S. Pat. Nos. 6,316,749;
6,318,245;
7,878,185; 8,101,894.
SUMMARY OF THE INVENTION
The cooking device with pyrolysis function includes a cooking cavity
surrounded by cavity
walls and an oven door, a heating means located within the cooking cavity for
emitting heat
therefrom, a combustion tube having a hollow portion formed to surround the
heating means, the
combustion tube being heated by the heating means and radiating its heat to
the center of the
cooking cavity, a combustion space formed between the heating means and the
combustion tube
in which cooking fumes are decomposed by the heat from the heating means, a
fan adapted to
withdraw air in the cooking cavity and to transfer a part or all of the air
through the connection
tube into the combustion space, a connection tube for connecting fluid
communication between
the combustion tube and the fan, and a gas outlet for venting out the steam
and air in the
combustion space to the outside of the cooking device.
The heating means located on the upper portion of the cooking cavity comprises
any source
selected from flame generated by the oxidation of fuel or a heater connected
to power source.
The combustion tube has a hollow ',ube-type structure with a gas outlet formed
at one end of
the combustion tube and a combustion tube inlet formed at the opposite end
where the heating
means is connected. The heating means is enclosed by the combustion tube. A
combustion space
is formed between the heating means and the combustion tube. The combustion
space and the
combustion tube are heated by the heating means. When heated, the combustion
tube radiates its
heat to the center of the cooking cavity. The fumes generated during cooking
are introduced to
the combustion tube to be thermally decomposed. Therefore, high energy
efficiency is achieved
by the heating means which has the dual function of warming food via the
combustion tube,
which radiates its heat to the cooking cavity, as well as causing thermal
decomposition of
cooking fumes.
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The fan receives power generated from a motor and forcibly convects the air
within the
cooking cavity. The fan is connected to the combustion tube through the
connection tube and
introduces the air and cooking fumes into the combustion space. The fan
prevents the cooking
fumes from spreading out of the cooking cavity by maintaining a lower-than-the-
atmospheric
pressure within the cooking cavity.
The connection tube is installed between the combustion tube and the fan and
functions as a
passage for a part or all of the air inhaled by the fan into the combustion
space. It is desirable that
the connection tube is connected to the combustion tube near the connection
tube inlet,
maximizing the contacting distance of cooking fumes with the heating means to
improve the
efficiency of the pyrolysis process.
The gas outlet is formed at one end of the combustion tube and functions as a
passage for the
steam and mixed gas in the combustion tube to the outside of the cooking
device.
The cooking device further includes a temperature sensor for sensing the
operating
temperature of the cooking cavity, a bottom heating means adapted to warm the
bottom portion
of the cooking cavity, and an air supply adapted to accelerate the oxidation
of cooking fumes by
injecting air into the combustion space.
The combustion process of contaminants in the cooking cavity is as follows.
When a heat
source is supplied to the heating means to emit heat, the temperature of the
combustion space
and the combustion tube increases. As the food is warmed by the radiant heat
from the
combustion tube to the center of the cooking cavity, steam and fumes from the
food are
generated in the cooking cavity. The fan withdraws air and fumes in the
cooking cavity, and
transfer a part or all of the air and fumes through the connection tube into
the combustion space.
The cooking fumes undergo thermal decomposition (pyrolysis) in the combustion
space
maintained at 700 C or higher temperature, and become carbon dioxide and
water. The mixed
gas in the combustion space travels towards the gas outlet to be vented out of
the cooking device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view showing a cooking device 10 according to the present
invention.
FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1.
FIG. 3 is a side sectional view taken along the line 3-3 of FIG. 2.
FIG. 4 is a perspective view of some components showing a flow of air for
thermal
decomposition.
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DETAILED DESCRIPTION OF THE INVENTION
The objects and features of the present invention will be now made in detail
to the preferred
embodiments of the present invention with reference to the attached drawings.
FIG. 1 is a front view showing a cooking device 10 according to the present
invention. An
oven door 25 having a door knob 28 is rotatably attached to an oven body 20
forming the
outward appearance of the oven 10. The oven door 25 seals the front side of a
cooking cavity 30
to prevent volatile compounds or smells from escaping from the cooking cavity
30, to make
racks easily go in and out of the cooking cavity, and to allow a user to check
the progress of
cooking. A control panel 22 is disposed at one side of the front face of the
oven body 20. The
control panel 22 includes at least one controlling means for setting
temperature and time so that
the inside of the cooking cavity 30 can keep a preset temperature for an
appropriate period of
time.
FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 showing the
inside configuration
of the cooking cavity 30 and the oven body 20, and FIG. 3 is a sectional view
taken along the
line 3-3 of FIG. 2. Referring to the drawings, the present invention will be
described in detail as
follows. The cooking cavity 30 is surrounded by a cavity wall 35 and has an
open front face
with an interior cooking space. The cooking cavity 30 further includes a
heating means 50
mounted at the upper part of the cooking cavity 30 and a combustion tube 60
having a hollow
portion formed to surround the heating means 50. The "upper part" indicates
that the heating
means 50 and the combustion tube 60 are located at the higher position than
the center of the
cooking cavity 30.
The combustion tube 60 has a hollow tube-type structure with a gas outlet 90
formed at one
end of the combustion tube 60 and a combustion tube inlet 62 formed at the
opposite end where
the heating means 50 is connected. The heating means 50 comprises any heating
source selected
from a flame generated by the oxidatio n of fuel or a heater connected to a
heat source 100. A
combustion space 65 is formed between the heating means 50 and the combustion
tube 60. The
cooking fumes can undergo thermal decomposition (pyrolysis) in the combustion
space 65
maintained at 700 C or higher by the heating means 50.
As the combustion tube 60 is heated by the heating means 50, the radiant heat
of the
combustion tube 60 is applied to the center of the cooking cavity 30 to warm
the food. Therefore,
it is preferable that the combustion tube 60 is configured to extensively
circulate air in the upper
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portion of the cooking cavity 30 to effectively radiate its heat to the center
of the cooking cavity
30.
The combustion tube 60 is selected from a group consisting of ceramics, heat-
resisting metals,
and a combination of both in order to withstand the heat generated by the
heating means 50. It is
preferable that the combustion tube 60 made of ceramics be enclosed by a heat
resisting metallic
cover (not shown) in order to protect it from external physical impacts.
The cooking cavity 30 further includes a fan 70 driven by a motor for forcibly
convecting the
air within the cooking cavity 30. The fan 70 is a centrifugal fan and is
connected in fluid
communication to the combustion tube 60. The fan 70 withdraws air from the
cooking cavity
and discharges a part or all of the air into the combustion space 65. When a
part of the
withdrawn air is discharged back into the cooking cavity 30, the air is
forcibly convected around
the hot combustion tube 60 resulting in a rapid increase of temperature in the
cavity and cooking
speed.
The fan 70 also prevents the cooking fumes from spreading out of the cooking
cavity 30 by
maintaining a lower than atmospheric pressure within the cooking cavity 30. It
is possible that
the amount of air introduced into the combustion space 65 to be controlled by
the fan 70 to adjust
the pressure of the cooking cavity 30. The amount of cooking fumes to be
pyrolyzed can also be
controlled.
The connection tube 80 is installed between the combustion tube 60 and the fan
70 and
functions as a passage for a part or all of the air inhaled by the fan 70 into
the combustion space
65. It is desirable that the connection tube 80 is connected to the combustion
tube 60 near the
connection tube inlet 62, maximizing the contacting distance of cooking fumes
with the heating
means 50 to improve the efficiency of the pyrolysis process.
The gas outlet 90 is formed at one end of the combustion tube 60 and functions
as a passage
for the steam and mixed gas in the combustion space 65 to the outside of the
cooking device 10.
An air supply 68 and heat source 100 are installed at the connection tube
inlet 62. The air
supply 68 provides fresh air into the combustion space 65 to accelerate the
oxidation of cooking
fumes. The air supply 68 also provides fresh air required for the oxidation of
fuel in the case the
heating means 50 comprises a flame. The heat source 100 comprises any source
selected from
fossil fuel or a wire connected to a power source.
CA 02889658 2015-04-27
The cooking device 10 further includes a bottom heating means 55 adapted to
warm the
bottom portion of the cooking cavity 30 and expedite the cooking of the food.
The bottom
heating means 55 comprises any heating source selected from flame generated by
the oxidation
of fuel or a heater connected to power source. It is desirable that the bottom
heaing means 55 be
located outside of the cooking cavity 30 as illustrated in FIG. 3 if the
bottom heating means 55
comprises a flame. In the case the bottom heating means 55 comprises a heater,
it is preferred
that the bottom heating means 55 be installed inside of the cooking cavity 30.
The cooking device 10 further includes a temperature sensor 40 for sensing the
operating
temperature of the cooking cavity 30. Located at the cavity wall 35, the
temperature sensor 40
detects the changes of temperature in the cooking cavity 30 and may turn off
the operation of the
heating means 50 or the bottom heating means 55 in the case the cooking cavity
30 is
significantly above the preset temperature.
FIG. 4 is a perspective view of some components showing a flow of air for
thermal
decomposition. Referring to the drawings, the combustion process of
contaminants in the
cooking cavity will be described in detail as follows.
When the heat source 100 is supplied to the heating means 50 to emit heat, the
temperature of
the combustion space 65 and the combustion tube 60 increases. As the food is
warmed by the
radiant heat from the combustion tube 60 to the center of the cooking cavity
30, steam and fumes
from the food are generated in the cooking cavity 30. The fan 70 withdraws air
and fumes from
the cooking cavity 30 and discharges a part or all of the air and fumes
through the connection
tube 80 into the combustion space 65. The cooking fumes undergo thermal
decomposition
(pyrolysis) in the combustion space 65 maintained at 700 C or higher
temperature and become
carbon dioxide and water. The mixed gas in the combustion space 65 travels
towards the gas
outlet 90 to be vented out of the cooking device 10. During the preset cooking
time, the heating
means 50 and the fan 70 are turned on ,so as to thermally decompose the
contaminants generated
during cooking. The combustion cycle comes to an end when the heat source 100
to the heating
means 50 and electricity to the fan 70 is terminated.
As described above for the pyrolysis process of the cooking fumes, the cooking
device 10
according to the present invention is efficient in use of energy because the
heating means 50 has
the dual function of warming food via the combustion tube 60, which applies
its radiant heat to
the cooking cavity 30, as well as causing the thermal decomposition of the
cooking fumes.
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While the present invention has been particularly shown and described with
reference to
exemplary embodiments thereof, it will be understood by those of ordinary
skill in the art that
various changes in form and details may be made therein without departing from
the spirit and
scope of the present invention as defined by the following claims.
LIST OF NUMERALS
10: Cooking device 20: Oven body
22: Control means 25: Oyen door
28: Door knob 30: Cooking cavity
35: Cavity wall 40: Temperature sensor
50: Heating means 55: Bottom heating means
60: Combustion tube 62: Combustion tube inlet
65: Combustion space 68: Air supply
70: Fan 80: Connection tube
90: Gas outlet 100: Heat source
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