Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Improved adjustable primary air supply for wood burning device
FIELD OF THE INVENTION
[001] The present invention relates generally to wood burning appliances but
more particularly to an adjustable control that provides variable air
intake resulting in efficient and clean burning.
BACKGROUND OF THE INVENTION
[002] This invention is an improvement over Applicant's own US patent
7,325,541, issued February 5'h, 2008, by solving issues only partially
resolved before by Applicant or by other prior art.
[003] A problem would arise with the original invention. Even as the burn rate
was reduced, the thermostatic bimetal blade would continue closing the
gate due to the ambient and surface temperature and would choke the
fire and cause an unclean burn as a result.
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SUMMARY OF THE INVENTION
[004] In view of the foregoing disadvantages inherent in the known devices
now present in the prior art, the present invention, which will be
described subsequently in greater detail, is to provide objects and
advantages which are:
[005] To provide for an improved mechanical system to adjust air entry for
efficient and clean burning.
[006] To provide for an improved safety mechanism has been implemented in
the new design of the [[PA]] primary air (PA) control to prevent damage
to the thermostatic bimetal blade.
[007] To attain these ends, the present invention generally comprises a base
plate having an opening from where primary air enters a firebox. A gate
rotationally attached to the base plate by way of a mechanical fastener;
a slider with guiding means sliding within an inclined slot; the slider
comprised of a contact point which makes contact with the gate for
adjustments. A first thermostatic bimetal blade reacting to heat by
displacing the gate so that the gate closes the opening; and a means to
move the slider and push the gate fully open. The improvement
comprising a first stopper member located on the base plate adjacent
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the opening and adapted to stop the movement of the gate and thereby
prevent the gate from completely covering the opening, and a second
thermostatic bimetal blade attached to the gate and adapted to react to
heat by displacing the gate from the base plate so that the gate can
move over the first stopper member such that the gate can continue to
cover the opening until the gate contacts the slider contact point.
=
[008] The adjustable primary air supply improvement further including a safety
mechanism comprising a bracket member attached to the first bimetal
blade. A pivot rod attached between the base plate and the bracket
member and adapted to allow the first bimetal blade to pivot there
around. A second stopper member adapted to stop the bimetal blade
from pivoting past a predetermined point; and a spring member attached
at one end to the bracket member and at an opposite end to a point on
the base plate at a distance therefrom and is adapted to hold the
bracket against the second stopper member and to prevent the bimetal
blade from deforming. ,
[009] The adjustable primary air supply for a wood burning device having the
following method of operation: When starting a fire, the gate is opened
to bring in as much air as possible; the first bimetal blade bends as the
temperature rises; the first bimetal blade pushes the gate partially over
the opening until it hits the first stopper member; the second bimetal
blade bends as the temperature continues to increase until the space
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created between the blade and the base plate is great enough to allow
the gate to overpass the first stopper member and continue to further
cover the opening until the blade contacts the slider contact point and
stops; and when the first and second bimetal blades gets colder, they
retract to their original configurations but the gate stays at the same
position.
[0010] The adjustable primary air supply for a wood burning device has the
means to move the slider and push the gate fully open include a key.
The key being turned to rotate a cog wheel which engages into a track
which includes a plurality of holes.
[0011] The amount of the primary air is varied by the position of the slider.
[0012] The method of operation further includes: at minimum burn rate, the
gate being completely closed by the first thermostatic bimetal blade, but
the gate being raised by the second thermostatic bimetal blade thereby
allowing a small amount of ,primary air to still enter the firebox. By the
end of the burning cycle, as the temperature drops, the second
thermostatic bimetal blade returns to a bent shape which allows the gate
to close the opening completely.
[0013] The gate is adapted to be pushed by the key when the key is pushed
inwardly.
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[0014] The first stopper member is an angled tab formed and bent from the
material of the base plate.
[0015] The second stopper member is generally shaped as a hook member
formed integrally with and bent perpendicular from the base plate.
,
[0016] The point on the base plate includes a base spring bracket adapted to
connect to the opposite end of the spring member.
[0017] There has thus been outlined, rather broadly, the more important
features of the invention in order that the detailed description thereof
that follows may be better understood, and in order that the present
contribution to the art may be better appreciated. There are additional
features of the invention that will be described hereinafter and which will
form the subject matter of the claims appended hereto.
[0018] In this respect, before explaining at least one embodiment of the
invention in detail, it is to be understood that the invention is not limited
in its application to the details of construction and to the arrangements
of the components set forth in the following description or illustrated in
the drawings. The invention is capable of other embodiments and of
being practiced and carried out in various ways. Also, it is to be
understood that the phraseology and terminology employed herein are
for the purpose of description and should not be regarded as limiting.
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[0019] As such, those skilled in the art will appreciate that the conception,
upon
which this disclosure is based, may readily be utilized as a basis for the
designing of other structures, methods and systems for carrying out the
several purposes of the present invention. It is important, therefore, that
the claims be regarded as including such equivalent constructions
insofar as they do not depart from the spirit and scope of the present
invention.
[0020] Further, the purpose of the foregoing abstract is to enable the U.S.
Patent and Trademark Office and the public generally, and especially
the scientists, engineers and practitioners in the art who are not familiar
with patent or legal terms or phraseology, to determine quickly from a
cursory inspection the nature and essence of the technical disclosure of
the application. The abstract is neither intended to define the invention
of the application, which is measured by the claims, nor is it intended to
be limiting as to the scope of the invention in any way.
[0021] These together with other objects of the invention, along with the
various
features of novelty which characterize the invention, are pointed out with
particularity in the claims annexed to and forming a part of this
disclosure. For a better understanding of the invention, its operating
advantages and the specific objects attained by its uses, reference
should be made to the accompanying drawings and descriptive matter
which contains illustrated preferred embodiments of the invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Fig. 1 Perspective view of the device.
[0023] Figs. 2a-c Top views of the device with the PA open, partially closed,
and closed.
[0024] Figs. 3a-c Top view, side view, and cutaway, along line EE, gate
partially closed.
[0025] Figs. 4a-c Top view, side view, and cutaway, along line UU, gate
partially closed.
[0026] Figs. 5a-c Top view, side view, and side view detail "T" of the gate
fully
closed.
[0027] Figs. 6a-c Isometric view and details "H" and "J" of the gate fully
closed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] An adjustable primary air supply for wood burning device (10) has a
base plate (12) into which is an opening (14) from where PA enters a
firebox (not shown). An "L" shaped gate (16) is rotationally attached to
the base plate (12) by way of a mechanical fastener (18) which holds
,
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the gate (16) somewhat loosely in order to allow for easy rotation but
also for another reason which Will be described later. A slider (20) slides,
as guided within an angled slot (22) by guiding means (23) generally in
the form of shoulder screws, rivets or short pegs. The slider (20) is
comprised of a roller contact point (21) which makes contact with the
gate (16) in order to limit displacement range of the gate (16) as may be
required. A first thermostatic bimetal blade (28) reacts to heat by
bending in a plane parallel to the base (12). The first thermostatic
bimetal blade (28) is rotationally attached to the base plate (12) by way
of a pivot rod (11).
[0029] Fig. 2a illustrates the configuration when starting a fire, at which
point
the PA is open to bring in as much air as possible. In order to fully open
the PA, the gate (16) is pushed by a means, in the form of a key (30) in
this figure, being pushed inwardly in the direction of arrow (17). As the
firebox gets warmer, The first thermostatic bimetal blade (28) begins to
bend as per fig 2b, this pushes the gate (16) which closes the opening
(14), this will also push the key (30) outwardly. In fig 2b, the gate (16)
only partially blocks the opening (14) because the slider (20) is so
positioned so as to block any further displacement of the gate (16). In
fig. 2c we see that by moving the slider (20) along the inclined slot (22),
the gate (16) is allowed to fully close the opening (14) as long as there is
enough heat to bend the first thermostatic bimetal blade (28) to do so.
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[0030] In order to vary the position of the slider (20), the key (30) is
turned to
rotate a cog wheel (32) which engages into a track (34) composed of a
plurality of slits (36). For design purposes, the handle part (38) of the
key (30) can be made into a knob for easier handling by a user.
[0031] The amount of the PA varies depending on the position of the slider
(20). It is possible for the user to establish the optimum position of the
slider (20) depending on the heating requirements. When the first
bimetal blade (28) gets colder, it retracts to its original configuration but
the gate (16) stays at the same position. That way, the PA is reduced to
, =
the minimum amount required for minimum burn rate.
[0032] The main feature of the device (10) is that it can provide maximum air
to
start the fire and it can reduce the burn rate to the user setting
automatically. The device (10) also prevents the user to reduce the burn
rate unless proper burning has been established. Only the action of the
first thermostatic bimetal blade (28) can reduce the burn rate. When the
desired burn rate is established and set by the user, the device will
regulate the burn rate automatically and consistently. The only action
required by the user is to activate the control by pushing the control key
(30) inwards when starting the fire or when adding a new load of wood.
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[0033] A second thermostatic bimetal blade (40) extending from the gate (16),
to which it is mechanically attached, raises the gate (16) slightly as per
figs. 4a-c. Since, as mentioned earlier, mechanical fastener (18) holds
gate (16) somewhat loosely, downward pressure exerted by the second
thermostatic bimetal blade (40) pushes the gate (16) upward so that it
can continue its course beyond a second stopper member (52) which
normally stops the gate (16), as seen in fig 2b, when it is not lifted by the
second bimetal blade (40). By no longer being stopped by the second
stopper member (52), the gate (16) can move further over the opening
(14) until stopped by the roiler'contact point (21) which is at a location
adjusted by the key (30). But, in this configuration, which occurs at the
minimum burn rate, the gate (16) is slightly raised by the second bimetal
blade (40) allowing a small amount of PA to enter the firebox, which is
sufficient to maintain proper combustion. By the end of the burning
cycle, as the temperature drops, the second bimetal blade (40) returns
to a bent shape which allows the gate (16) to close completely.
[0034] As the temperature increases, the thermostatic bimetal blade (28) would
continue to bend and press against the gate (16) even after it had
reached the preset setting. This constriction of movement of the
thermostatic bimetal blade (28) after the gate had been closed to the
preset setting made the thermostatic bimetal blade (28) bend in the
opposite direction and deform, preventing the thermostatic bimetal blade
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(28) to perform as it was intended to. In order to remedy that problem, a
safety mechanism consists of a first stopper member (50), a bracket
member (54), a spring (56) and a pivot rod (11).
[0035] The first stopper member (50) is located on the base (12) at the foot
of
the bracket member (54) and determines the rest position of the
thermostatic bimetal blade (28). The spring (56) is attached to the
bracket member (54) at one of its end and runs over and across the
base (12) to attach its opposite end to a spring bracket (60) which
extends perpendicularly from the base (12).
[0036] The spring (56) pulls the thermostatic bimetal blade (28) against the
first
stopper member (50) to its rest position. This allows for the thermostatic
bimetal blade (28) to pivot around the pivot rod 11 when it gets
overheated and prevents it from deforming.
[0037] While the fire burns reasonably hot and the gate (16) has been closed
to
the preset setting, the burn rate can be altered by rotating the key (30).
At this point, the thermostatic bimetal blade (28) pushes the gate (16)
against the roller contact point (21) and the amount of combustion air is
determined by the position of the slider (20). it must be noted that this
control prevents the user from reducing the burn rate and consequently
inducing unclean burning. Only when proper burning has been
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established, the thermostatic bimetal blade (28) will bend and reduce
the burn rate to the user's preset setting,
[0038] As to a further discussion of the manner of usage and operation of the
present invention, the same should be apparent from the above
description. Accordingly, no further discussion relating to the manner of
usage and operation will be provided.
[0039] With respect to the above description then, it is to be realized that
the
optimum dimensional relationships for the parts of the invention, to
include variations in size, materials, shape, form, function and manner of
operation, assembly and use, are deemed readily apparent and obvious
to one skilled in the art, and all equivalent relationships to those
illustrated in the drawings and described in the specification are
intended to be encompassed by the present invention.
[0040] Therefore, the foregoing is considered as illustrative only of the
principles of the invention. Further, since numerous modifications and
changes will readily occur to those skilled in the art, it is not desired to
limit the invention to the exact construction and operation shown and
described, and accordingly, all suitable modifications and equivalents
may be resorted to, falling within the scope of the invention.
