Note: Descriptions are shown in the official language in which they were submitted.
CA 02638177 2010-02-23
ABSTRACT OF THE SPECIFICATION
Charcoal /Air BBQ Combustion Chamber Assembly
Device comprising a funnel shaped perforated combustion chamber within an
annular
air plenum comprising a cooking zone and a fire grate / ash exit into the
lower ash
storage container.
Common problems to resolve
(1) Slow start up / flame spread. (2) No clean convenient ash disposal.
(3) No practical temperature control. (4) No flare up control.
Device Solutions
A variable speed blower supplying air into the combustion chamber, from plenum
through perforations. (1) Faster air velocity = faster bum rate and start up.
(2) Air
stimulation of ash bed thereby assisting gravitational effect and wall slope
to precipitate
unstable ash downwardly through said ash exit / fire grate into ash storage
container.
(3) Said air also enabling variable temperature control. (4) A secondary
variable speed
blower is affixed to the ash container and coupled by duct to the 360 degree
peripheral
slot Lateral Air Sheet Diffuser disposed on the central vertical axis medially
between
grill and heat source. Said diffuser projecting a horizontal air sheet and
instantly
blowing flare-ups out of the cooking zone.
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CA 02638177 2010-02-23
Charcoal / Air BBQ Combustion chamber assembly
Field of the Invention / Prior Art
This invention relates to Outdoor BBQ grills, particularly those fuelled by
charcoal.
Repeated surveys confirm that over 70% of the population that use a BBQ prefer
the
taste of foods cooked over an open fire fuelled by natural charcoal. However,
despite
this overwhelming preference, the majority of BBQs purchased are fuelled by
gas.
Charcoal units have not been significantly developed or modernised for 20 to
30 years.
They still produce lots of messy ash that requires manual removal which can be
difficult
to clean up. Ignition is still frequently achieved by pouring a volatile fuel
over charcoal
to ignite said fuel / charcoal. Flame development and spread throughout the
charcoal
bed is very slow. Temperature control frequently includes the opening and
closing of
the BBQ lid. In the case of excessively high temperatures it is not unusual to
reduce the
temperature by spraying water on the fuel bed.
Flare-ups / fires frequently occur when meat fats drip onto hot Charcoal
embers. Said
fats instantly vaporise and then ignite, sometimes violently. These Flare-ups
can burn
and carbonise foods / meats. This carbonisation has become of real concern in
the past
few years as more credible research, links burnt / carbonised meats to
production of
carcinogens. There has been no effective Flare-up elimination system / device
to date.
In all records searched, lack of significant innovation in this field is
conspicuous by its
absence. There have been no serious efforts to solve the long standing real
problems that
could have helped to ensure the viability of the charcoal BBQ.
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CA 02638177 2010-02-23
CANADIAN CLASSES SEARCHED:
126/104 1248/34 1126/62
U.S. CLASSES SEARCHED:
99/339, 340, 352-355, 357, 389, 400, 401, 421 H, 421 HH, 444-450, 481, 482
1126/121, 242,
25A, 25AA, 25C, 25R, 276, 290, 299D, 41 R, 51 R 1 21 9/400 1248/509 1270/300
INTERNATIONAL CLASSES SEARCHED:
A47J 37/06, 37/07 1 F24B 1/00, 1/20, 1/182 1 F23B 60/00, 60/02, 70/00
4/788/905. VON KUHORN. FAN.
3/266/478. BOOTH. FAN.
3/159/119. HOTTENROTH. FAN.
3/324/788. LA. FRANCE. FAN.
3/326/201. MURRAY. FAN.
5/168/860. KIBOURIAN. FAN.
3/327/697. BERLANT. FAN.
4/850/353. DELLRUD. FAN.
KR20030049623 YONG SUB. CHARCOAL COOKING OVEN.
4/287/870. JOHNSON. BLOWER. MULTI USE HYBRID ADD-ON.
Meaningful efforts to improve operator convenience have been virtually
restricted to
reducing the time required to fully ignite a bed of charcoal using a small fan
/ blower.
Currently there are few viable alternatives to gas powered BBQs as these have
also not
been significantly updated other than having the ability to control the gas
burners and
utilize IR emitters. Lack of messy charcoal ash is substituted by gas heated /
vaporised
fats and grease which deposits everywhere and which requires considerable
clean up.
Flare-up fires are frequent with no effective control other than closing the
lid. Attempts
to simulate / duplicate the real charcoal taste have been abandoned and the
feel good
feature of a real fire has never existed.
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CA 02638177 2010-02-23
SUMMARY OF THE INVENTION
Considering the situation regarding the types of BBQ devices currently
available,
the present invention introduces innovative and practical concepts into
charcoal bbq
combustion chamber design. Said innovations substantially resolving known
limitations, disadvantages and problems inherent in previous art. This has
resulted in a
device not anticipated / made obvious or implied by any known prior art. This
original
design includes simple air systems that permit control over all aspects of the
combustion
process. The combustion chamber assembly is designed to preclude random
ambient air
from said assembly, this is achieved by the heat radiated from combustion
chamber,
utilizing upward convection currents from heating zone. All air required for
combustion
is supplied from the plenum into the combustion chamber through said
perforations as
previously described. Said primary combustion air is supplied in metered
amounts by a
variable speed electric blower mounted to the plenum and controlled by
potentiometer.
This enables improved control of the ignition process / burn rate and
temperature
requirements. Suppression of Flare-ups is achieved by projecting a Lateral Air
Sheet
between the grill and the cooking zone from a 360 degree air diffuser head
supplied by a
secondary variable speed electric blower affixed to the Ash Storage Container
and
controlled by a potentiometer.
DESCRIPTION
It is the object of the device to resolve the following major areas of
operator
inconvenience
(1) Unsafe ignition using volatile liquids, and slow flame spread throughout
fuel
charge.
(2) Poor cooking temperature control, usually assisted by opening or closing
BBQ
cover / lid. Or, when too hot by spraying with water to cool.
(3) Flare-up fires. These occur frequently as fats drip off meat onto the hot
cooking
surface where it vaporises ignites and burns foods
(4) Manual ash clean up. Very dirty messy chore.
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CA 02638177 2010-02-23
(1) FAST SAFE START UP / EVEN FLAME SPREAD
Initial combustion commences by placing adequate food grade fire starters on
the fire
grate and loosely covering said igniters to a reasonable depth with short
pieces of
charcoal Using a propane torch, the fire starters are ignited through spaces
that have
been left in the charcoal. When it is evident that combustion is established,
combustion
air is introduced through the perforations at low initial velocity into the
combustion
chamber from the plenum.
Note. As air velocity is progressively increased, burn rate and flame spread
increases
very rapidly. Do not leave controls unattended. Charcoal should be added until
fire bed
is satisfactory. Note use a quality temperature gauge with long probe.
(2) TEMPERATURE CONTROL
It should be noted that temperatures can increase very rapidly, however it
takes longer
for hot coals to cool down. Heat should be increased slowly without
overshooting the
required temperature when possible. When overshooting occurs, reduce
temperature by
reducing air supply until desired temperature is reached. It is also possible
to reduce the
heat from below the cooking grill by operating the Lateral Air Sheet Diffuser
which
projects cooling air throughout the cooking zone below said grill. This may
not assist in
extreme cases. Move food to higher grill.
(3) FIRES AND FLARE-UP CONTROL
Effective reduction of smoke / fumes and flare-ups may be achieved by
activating the
Lateral Air Sheet Diffuser system. Said system projecting a variable velocity
360 degree
Lateral Air Sheet from the peripheral slot diffuser located on the central
vertical axis,
medially between the grill and the cooking zone, thereby controlling flare-ups
that
occur, this prevents the burning / carbonisation of meats etc., which as
previously
mentioned can result in serious health complications.
CA 02638177 2010-02-23
(4) AUTOMATIC ASH / REMOVAL / STORAGE
It will be noted that the fire bed slowly drops as numerous air jets through
the
combustion chamber wall perforations agitates ash in the fuel bed and on the
combustion chamber sloped wall. This continuous agitation of ash on the 45
degree
sloped wall, combined with the inevitable effect of gravity, results in ash
moving
downwardly through the fire grate and into the Ash Storage Container for later
disposal
through an opening door / port in its base. Ash flow can be assisted by
increasing air
velocity from the combustion chamber air variable speed electric blower.
DETAILED DESCRIPTION
BBQ COMBUSTION CHAMBER ASSEMBLY
Please note enclosed drawing Figure 2b, this illustrates a cross sectional
view of the
combustion chamber assembly as described in this section. Components described
are
like numbered in relative text and on drawing for clarity.
The device consists of two components. The first component being a large
diameter
Annular Air Plenum (14) having a right angled triangular cross section. The
inner
sloped wall (36) of the triangle (14) defining therein a funnel shaped
combustion
chamber (8) having a large diameter (40) open top cooking zone, and a smaller
diameter
(66) open bottom which functions as an ash exit. Said ash exit also locating a
fire grate
(38) which supports the fuel charge.
It will be noted that the sloped wall (36) separates the inner combustion
chamber (8)
from the outer annular / air plenum (14). The wall has a plurality of
perforations (12)
spaced radially through 360 degrees on several evenly spaced lateral
concentric circles,
commencing upwardly from the fire grate (38) towards the cooking surface.
Said perforations (12) enabling air to pass at pre-selected speeds from the
plenum (14)
through said dividing wall into the combustion chamber (8), thereby
controlling
combustion. Said perforations are inclined upwardly towards the central axis
(46) at
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CA 02638177 2010-02-23
approx 45 degrees providing optimum flame spread throughout the chamber (8).
Combustion air is supplied to the plenum by a coupling duct (52) operative
between
plenum and variable speed electric blower (32) controlled by a potentiometer.
Said
blower affixed externally to the outer plenum wall. This airflow enabling a
satisfactory
degree of control over the combustion process. Finally solving the problem of
long slow
start ups and temperature control.
The second component consists of a cylindrical container of smaller diameter
which
serves as an ash storage container (6). Said container aligns with and is
removably
attached by bolts (18) over the smaller diameter ash exit hole (66) in the
base of the
combustion chamber assembly, thereby enabling ash to pass freely from said
combustion chamber (8) into the ash storage container (6), which has a close
fit sliding
door / port (68) secured by screw clamps (72) in its base. Ash is quickly
cleanly and
easily dumped when cool into any suitable container for disposal. This solving
the
problems of messy ash clean up. When operable said ash storage system
precludes
ambient air.
The ash container (6) houses a supply duct (10) disposed on the central
vertical axis of
said combustion chamber assembly (2). Said duct supplying air to the 360
degree
Lateral Air Sheet Diffuser head (46) from a variable speed electric blower
(34)
controlled by a potentiometer mounted externally on the ash container (6).
Said diffuser
operable medially between grill and heating zone.
The 360 degree peripheral slot diffuser (46) projects a horizontal air sheet
across the
cooking zone, instantly blowing any flames out of said cooking zone before any
food is
carbonised / burnt. This finally solved the problem of how to prevent food
being burnt /
carbonised,
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