Thin Profile Multi-Manifold Multi-Tube Burner for Gas Grills
A barbecue grill and a burner assembly are disclosed, the burner assembly having a venturi tube for conveying gas to the burner, a burner tube having front and back manifolds, with the venturi tube connected to the front and back manifolds and having flow restrictors at the connection interface to at least partially inhibit entry of gas into the front manifold.
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This application claims the benefit of U.S. provisional patent application Ser. No. 61/772,828, filed Mar. 5, 2013, which is incorporated herein by reference in its entirety.
BACKGROUNDIn the present art, most gas grills have very bulky fireboxes with several drawbacks: 1) they are heavy to handle and install, and the weight makes them expensive for shipping and handling, 2) they are expensive to make due to more materials, and 3) they are thermally inefficient because of the large volume of the firebox. When several types of present market grills were studied it was understood why the fireboxes were made so bulky. The main reason was the burner design. In the majority of the cases, a single tube burner was used under an average 150 sq. in. (17″L×8½″W) cooking area, although, in some cases, two tube burners with single control valves were used under a 200 to 240 sq. in. cooking area. These conventional burner designs require a large fire box to achieve sufficient heat for cooking and to pass combustion tests required for safe use.
SUMMARYThe problem to be solved was how to make a firebox as thin as possible for a gas grill. To make a thinner firebox, the burner tube needs to be located closer to the cooking grate. The main challenge associated with this approach is the failure of the combustion test that is required for product certification. The limited number of ports on a single tube burner burns the gas with taller and stronger flames which impinge on the cooking grate or radiant element and fails the combustion test. To solve this issue, the burner needs to be designed with multiple tubes so that more burner ports can be accommodated to make flames shorter and weaker to avoid flame impingement. An additional venturi tube or tubes are added, to communicate with multiple manifolds, such as a front and rear manifold. Other adjustments are also made to equalize gas pressure in the form of flow restrictors and the like.
Referring now more specifically to the drawings and to
It can be seen in the cut-away version that the burner 12 is formed in a grid like arrangement having generally parallel longitudinal members 15 that are connected at each end thereof by semi-circular conduits 16. The longitudinal members 15 can be formed continuously with the semi-circular conduits sections 16 or they can be separately formed and assembled into a gas manifold in the center, as shown in FIG. 2. Gas is admitted to the burner tubes by methods known to the art and illustrated in
Ignition of the gas in the burner tubes may be accomplished by use of a spark generator arcing across an electrode (not shown), suitably placed in proximity to the burner 12, a hot surface igniter similarly placed, and other known methods.
As shown in
Prior art constructions would result in relatively strong flames in the front burner tubes and relatively weaker flames in the rear burner tubes. Thus, even heating would be and is, difficult to achieve, with concomitant variations in evenness of cooking, hot spots, and generally inefficient performance. With the restriction holes in the front manifold supply interface 41 and no restriction in the rear manifold supply interface 43, gas is evenly distributed and the flames are of substantially equal height tall in the front and back.
Referencing again Detail A in
Looking at the detail of
Depending on the size of the burners, the desired flow rate, and the type of gas, variation of the area ratio may be necessary and can be changed by varying the number and size of the holes in the front and by introduction of the feature shown in
Given these possible variations, the ratio of areas of inlet to the front manifold to the areas of inlet to the back manifold could be from 50% to 70%. Or they could range from 40% to 75%. The object is to balance the pressure and flow in the front and rear manifolds to avoid the undesirable effects outlined previously.
An alternate embodiment is shown in
While the flow restrictors are shown and described as apertures, other means for restricting the gas flow are contemplated, such as slits, gates, valves, and other means known in the art may be utilized.
Another embodiment exhibits a construction wherein the port sizes in the burner tubes are varied to equalize the gas pressure. In this design, the burner ports nearer or at the center of the tubes are larger than those closer to the ends. This also accomplishes pressure equalization.
The burners 30 and 60, shown in the appended figures, are shown with a central elongated venturi tube. This is not meant to be limiting and the additional one or more front-rear connecting venturi tubes can be located in a different position or positions, i.e. off-center, left, right, etc. The venturi tube/manifold conduit may be formed as a single fabrication or it may be separate pieces formed and connected in a fluid-tight manner.
After having successful results with the combustion tests, the system was tested thoroughly and had some unexpected results:
1) Burner heats up the grate very evenly. Delta-T of this system was within 5 degree Fahrenheit versus the conventional systems which have that number from 25 to 50 degrees.
2) System is very energy efficient. With minimum volume of the firebox, wastage of energy is reduced significantly and also as the cooking grate is very close to the burner flame, with a 3500 degree F. temperature, it gets a substantial amount of infrared energy directly from the flames. A conventional system is about 20% to 35% thermally efficient but the present system goes over 40% efficient, depending on the cooking grate used.
3) Preheat time is significantly reduced. A conventional grill takes 10 to 15 minutes to preheat, but the present system takes only 2 minutes to preheat. It literally heats up the grate instantly.
4) By virtue of the food being closer to the heat source, it receives a higher percentage of IR heat which keeps the food juicier.
5) With the present burner system, hot spots are eliminated and with the proper cooking grate system, flare-ups are eliminated as well.
Thus, the optimum design was achieved to have a thin firebox system. While it depends on the size of the system, on a conventional cooking size of 150 sq. in. (17″L×8½″W) the depth of the firebox 80, (from under the cooking grate to the bottom of the firebox) is usually 4 inches, (reference dimension A in
An alternate embodiment of the present burner is shown in
The flammable gas/air mixture is supplied to the burner through lower and upper elongated venturi tubes 110 and 112, respectively. As shown in Detail view A, the front venturi tube/front manifold interface has relatively small flow restrictors or baffles 114. As shown in Detail view B, the rear venturi tube/rear manifold interface has relatively larger flow restrictors or baffles 116. Similar to the designs shown in
The structures shown in
As can be seen in
As with the operational description above, relative to the burner shown in
While an embodiment of a thin profile, multi-manifold multi-tube burner for gas grills and modifications thereof have been shown and described in detail herein, various additional changes and modifications may be made without departing from the scope of the present disclosure or the appended claims.
Claims
1. A burner assembly for a gas barbeque grill having a gas supply comprising at least one burner tube with a front end, a back end and a plurality of gas outlet parts formed therein, a front manifold connected to said front end and a back manifold connected to said back end, both of said manifolds being in fluid communication with said burner tube to allow entry of a flammable gas/air mixture, a venturi tube connected to said front and back manifolds and to the gas supply for transferring gas to the burner assembly, and said venturi tube including flow restriction means at the venturi tube/front manifold interface, to at least partially inhibit the entry of the gas/air mixture.
2. A burner assembly as defined in claim 1 in which said venturi tube includes flow restriction means at the venturi tube/back manifold interface to at least partially inhibit the entry of the gas/air mixture.
3. A burner assembly as defined in claim 1 including a plurality of burner tubes corrected to said front and back manifolds.
4. A burner assembly as defined in claim 1 including at least one additional burner tube with a front end, a back end, and a plurality of gas outlet ports formed therein, an additional front manifold connected to said front end and an additional back manifold connected to said back end, both of said additional manifolds being in fluid communication with said additional burner tube to allow entry of a flammable gas/air mixture, an additional venturi tube connected to said additional front and back manifolds and to the gas supply for transferring gas to the burner assembly, and said additional venturi tube including flow restriction means at the venturi tube/front manifold interface to at least partially inhibit the entry of the gas air mixture.
5. A burner assembly as defined in claim 4 in which said additional venturi tube includes flow restriction means at the venturi tube/back manifold interface to at least partially inhibit the entry of the gas/air mixture.
6. A burner assembly as defined in claim 4 including a plurality of additional burner tubes connected to said additional front and back manifolds.
7. A burner assembly for a gas barbeque grill having a gas supply comprising at least one burner tube with a front end, a back end and a plurality of gas outlet ports formed therein, a front manifold connected to said front end and a back manifold connected to said back end, both of said manifolds being in fluid communication with said burner tube to allow entry of a flammable gas/air mixture, a venturi tube connected to said front and back manifolds and to the gas supply for transferring gas to the burner assembly, and said front manifold including flow restriction means to at least partially inhibit the entry of the gas/air mixture.
8. A burner assembly as defined in claim 1 in which said back manifold includes flow restriction means to at least partially inhibit the entry of the gas/air mixture.
9. A burner assembly as defined in claim 1 including a plurality of burner tubes corrected to said front and back manifolds.
10. A burner assembly as defined in claim 1 including at least one additional burner tube with a front end, a back end, and a plurality of gas outlet ports formed therein, an additional front manifold connected to said front end and an additional back manifold connected to said back end, both of said additional manifolds being in fluid communication with said additional burner tube to allow entry of a flammable gas/air mixture, an additional venturi tube connected to said additional front and back manifolds and to the gas supply for transferring gas to the burner assembly, and said additional front manifold including flow restriction means to at least partially inhibit the entry of the gas air mixture.
11. A burner assembly as defined in claim 4 in which said additional back manifold includes flow restriction means to at least partially inhibit the entry of the gas/air mixture.
12. A burner assembly as defined in claim 4 including a plurality of additional burner tubes connected to said additional front and back manifolds.
13. A gas barbeque grill comprising a firebox with a burner assembly mounted therein, a cooking grid mounted above said burner assembly, and a gas supply connected to said burner assembly, said burner assembly including at least one burner tube with a front end, a back end and a plurality of gas outlet ports formed therein, a front manifold connected to said front end and a back manifold connected to said back end, both of said manifolds being in fluid communication with said burner tube to allow entry of a flammable gas/air mixture, a venturi tube connected to said front manifold and to the gas supply for transferring gas to the burner assembly, and said venturi tube including flow restriction means at the venturi tube/front manifold interface to at least partially inhibit the entry of the gas/air mixture.
14. A gas barbeque grill as define in claim 13 in which said venturi tube includes flow restriction means at the venturi tube/back manifold interface to at least partially inhibit the entry of the gas/air mixture.
15. A gas barbeque grill as defined in claim 14 in which the flow restriction means at the venturi tube/front manifold interface are smaller than the flow restriction means at the venturi tube/back manifold interface.
Type: Application
Filed: Mar 5, 2014
Publication Date: Sep 11, 2014
Applicant: Char-Broil, LLC (Columbus, GA)
Inventor: Mallik R. Ahmed (Columbus, GA)
Application Number: 14/198,176
International Classification: A47J 37/07 (20060101); F23D 23/00 (20060101); F23D 14/10 (20060101);