WO2012129635A2

WO2012129635A2 - Improved adjustable primary air supply for wood burning device

Info

Publication number: WO2012129635A2
Application number: PCT/CA2011/000402
Authority: WO
Inventors: Emmanuel Marcakis
Original assignee: Emmanuel Marcakis
Priority date: 2011-04-01
Filing date: 2011-04-01
Publication date: 2012-10-04
Also published as: WO2012129635A3

Abstract

An improved adjustable primary air supply for wood burning device 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 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.

Description

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^th, 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.

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 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 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 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. [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. [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. 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 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 ). 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. [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. [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 roller 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 (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 (58) 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 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.

Claims

1. ) In an adjustable primary air supply for a wood burning device comprising a base plate having an opening from where primary air enters a firebox; a gate rotationally attached to said base plate by way of a mechanical fastener; a slider with guiding means sliding within an inclined slot; said slider comprised of a contact point which makes contact with said gate for adjustments; a first thermostatic bimetal blade reacting to heat by displacing said gate so that said gate closes said opening; and a means to move said slider and push said gate fully open; the improvement comprising a first stopper member located on said base plate adjacent said opening and adapted to stop the movement of said gate and thereby prevent said gate from completely covering said opening; and a second thermostatic bimetal blade attached to said gate and adapted to react to heat by displacing said gate from said base plate so that said gate can move over said first stopper member such that said gate can continue to cover said opening until said gate contacts said slider contact point.

2. ) The adjustable primary air supply improvement of claim 1 , further including a safety mechanism comprising a bracket member attached to a said first bimetal blade; a pivot rod attached between said base plate and said bracket member and adapted to allow said first bimetal blade to pivot there around; a second stopper member adapted to stop said bimetal blade from pivoting past a predetermined point; and a spring member attached at one end to said bracket member and at an opposite end to a point on said base plate at a distance therefrom and is adapted to hold said bracket against said second stopper member and to prevent said bimetal blade from deforming.

3. ) An adjustable primary air supply for a wood burning device as in claim , and having the following method of operation: when starting a fire, said gate is opened to bring in as much air as possible; said first bimetal blade bends as the temperature rises; said first bimetal blade pushes said gate partially over said opening until it hits said first stopper member; said second bimetal blade bends as the temperature continues to increase until the space created between said blade and said base plate is great enough to allow said gate to overpass said first stopper member and continue to further cover said opening until said blade contacts said slider contact point and stops; and when said first and second bimetal blades gets colder, they retract to their original configurations but said gate stays at the same position.

4. ) The adjustable primary air supply for a wood burning device as in claim 1 , wherein said means to move said slider and push said gate fully open includes a key; said key being turned to rotate a cog wheel which engages into a track which includes a plurality of holes.

5. ) The adjustable primary air supply for a wood burning device as in claim 1 , wherein the amount of said primary air is varied by the position of said slider.

6. ) The adjustable primary air supply for a wood burning device as in claim 3, wherein the method of operation further includes: at minimum burn rate, said gate being completely closed by said first thermostatic bimetal blade, but said gate being raised by said second thermostatic bimetal blade thereby allowing a small amount of primary air to still enter said firebox; by the end of the burning cycle, as the temperature drops, said second thermostatic bimetal blade returns to a bent shape which allows said gate to close said opening completely.

7. ) The adjustable primary air supply for a wood burning device as in claim 4, wherein said gate is adapted to be pushed by said key when said key is pushed inwardly.

8. ) The adjustable primary air supply for a wood burning device as in claim 1 , wherein said first stopper member is an angled tab formed and bent from the material of said base plate.

9. ) The adjustable primary air supply for a wood burning device as in claim 2, wherein said second stopper member is generally shaped as a hook member formed integrally with and bent perpendicular from said base plate.

10. ) The adjustable primary air supply for a wood burning device as in claim 2, wherein said point on said base plate includes a base spring bracket adapted to connect to said opposite end of said spring member.