Title:
OVENS, BURNER TUBE ASSEMBLIES, AND METHODS FOR DELIVERING AIR TO A GAS POWER BURNER
Kind Code:
A1


Abstract:
Ovens for heat treating products may include a gas power burner having a burner tube assembly, a venturi tube assembly, and a blower mount. The burner tube assembly has a plurality of air inlet holes extending from an outer surface to an inner surface of the burner tube. The blower mount has an opening spaced from the outer surface of the burner tube for receiving a flow of combustion air directed in a first direction toward the burner tube. The opening of the blower mount is disposed out of axial alignment with the plurality of air inlet holes such that a portion of the burner tube and the blower mount form an air manifold for redirecting the flow of combustion air from the first direction around the burner tube and towards the air inlet holes. Methods for delivering air to a gas power burner are also disclosed.



Inventors:
Bramhall, Marcus E. (Dallas, NC, US)
Application Number:
12/111490
Publication Date:
10/30/2008
Filing Date:
04/29/2008
Primary Class:
Other Classes:
431/8
International Classes:
F24C3/00
View Patent Images:
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Primary Examiner:
PEREIRO, JORGE ANDRES
Attorney, Agent or Firm:
HESLIN ROTHENBERG FARLEY & MESITI PC (ALBANY, NY, US)
Claims:
1. A burner tube assembly for a gas power burner, said burner tube assembly comprising: a burner tube having a first end, a second end, a longitudinal axis extending from said first end to said second end, and a plurality of air inlet holes extending from an outer surface to an inner surface of said burner tube adjacent to said second end; a venturi tube assembly disposed longitudinally in said burner tube and having an inlet portion disposed adjacent to said second end and a burner head portion disposed adjacent to said first end; a blower mount having an opening spaced from said outer surface of said burner tube for receiving a flow of combustion air directed in a first direction toward said burner tube, said opening of said blower mount disposed out of axial alignment with said plurality of air inlet holes; and wherein a portion of said burner tube and said blower mount form an air manifold for redirecting the flow of combustion air from the first direction around said burner tube and towards said plurality of air inlet holes.

2. The burner tube assembly of claim 1 wherein said plurality of air inlets holes are obscured from view through said opening of said blower mount.

3. The burner tube assembly of claim 1 wherein plurality of air inlets holes direct the flow of combustion air in a plurality of generally radial directions towards said longitudinal axis of said burner tube.

4. The burner tube assembly of claim 1 wherein said plurality of air inlet holes is generally evenly spaced around said burner tube.

5. The burner tube assembly of claim 1 wherein said plurality of air inlet holes comprises four air inlet holes.

6. The burner tube assembly of claim 1 wherein said burner tube comprises a cylindrical tube.

7. The burner tube assembly of claim 1 further comprising a flame spreader disposed adjacent to said second end.

8. The burner tube assembly of claim 1 wherein said flame spreader comprises a center portion defining a cone, and a plurality of outwardly extending angled fins.

9. An impingement oven comprising: a housing having a chamber therein for receiving and heating a heat treatable product; and gas power burner comprising a burner tube assembly of claim 1 for supplying heat to said chamber.

10. The impingement oven of claim 9 further comprising a movable conveyor.

11. The impingement oven of claim 9 wherein said gas power burner further comprises a modulating gas valve for regulating the supply of gas to the gas power burner between 0-percent and 100-percent.

12. A method for delivering air to a gas power burner, the method comprising: providing a flow of combustion air along an axis in a first direction toward an outer surface of a burner tube; redirecting the flow of combustion air around at least a portion of the outer surface of the burner tube; and transferring the flow of the redirected combustion air from an outer surface of said burner tube to an inner surface of said burner tube in a direction different from the first direction.

13. The method of claim 12 further comprising obstructing the flow of combustion air along the axis with a portion of the outer surface of the burner tube.

14. The method of claim 12 wherein the transferring comprises transferring the flow of redirected combustion air through a plurality of air inlets holes spaced from the axis.

15. The method of claim 12 wherein the transferring comprises transferring the flow of redirected combustion air through four air inlet holes spaced from the axis.

16. The method of claim 12 wherein the transferring comprises transferring the flow of redirected combustion air in a plurality of generally radial directions toward a longitudinal axis of said burner tube.

17. The method of claim 12 wherein the transferring comprises transferring the flow of redirected combustion air generally evenly toward a longitudinal axis of said burner tube.

18. The method of claim 12 further comprising regulating the supply of gas between 0-percent and 100-percent to the gas power burner.

19. The method of claim 12 further comprising providing a flow of gas to a venturi tube disposed in the burner tube, and spreading a flame generally radially from the burner tube.

Description:

CLAIM TO PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/915,012, filed Apr. 30, 2007, entitled “Ovens, And Burner Tube Assemblies, Cold Air Return Baffles, Finger Ducts, And Removable Wheels Therefor”, which is hereby incorporated in its entirety herein by reference.

This application is related to commonly owned, and co-filed U.S. patent application Ser. No. ______, entitled “Ovens Having A Cold Air Return Baffle And Methods For Circulating Air In An Oven,” by Bramhall, (Docket No. 2869.015B); U.S. patent application Ser. No. ______, entitled “Ovens, Finger Ducts Therefor, And Methods For Distributing Air in A Finger Duct” by Bramhall, (Docket No. 2869.015C); and U.S. patent application Ser. No. ______, entitled “Methods For Moving Ovens, And Ovens Having Means For Releasably Attaching To A Plurality Of Casters,” by Bramhall, (Docket No. 2869.015D), which are hereby incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

This invention relates generally to ovens, and more specifically, to burner assemblies and methods for delivering air to a gas power burner.

BACKGROUND OF THE INVENTION

Ovens for heat-treating products oftentimes employ a burner for combusting a fuel such as gas for heating the oven.

Food preparation ovens such as food preparation ovens for preparing pizza and other types of food products employ jets of hot gaseous fluid such as hot air for baking or cooking the food product.

U.S. Pat. No. 4,846,143 issued to Csadenyi discloses a gas power burner for a food preparation oven. The gas power burner has a burner tube having an air aperture in the side thereof located concentrically with respect to a cylindrical tube of an air blower adaptor. The air aperture is also located along the burner tube at a position which is intermediate an air inlet apertures of a mouth portion and a burner head portion.

U.S. Pat. No. 4,045,160 issued to Michels discloses a fuel gas burner having a nozzle element having radially extending circumferential vanes. A resulting fuel-air mixture, which has a swirling motion imparted by the slots, is ignited and propelled radially outward against the frusto-conical surface of the combustion block to produce a generally flat-flame. This produces a relatively large expanse of heat radiation directed toward the area to be heated.

U.S. Pat. No. 4,457,291 issued to Henke discloses a power burner system having a circular-shaped flame spreader positioned in the path of a gas-air mixture exiting a burner tube. The flame spreader serves to shape a substantially elongated teardrop heat source into a substantially spherical heat source within a heating chamber. Also disclosed is a mechanical modulating valve coupled to a gas supply line between an electrical on-off valve and a gas power burner for varying the flow rate of gas to the gas power burner.

U.S. Pat. No. 6,481,433 issued to Schjerven, Sr. et al. disclose a modulator which regulates the amount of gas flowing to the burner to maintain a uniform temperature in the oven in response to thermocouple sensors in a cavity control.

There is a need for further ovens and burner tube assemblies therefor.

SUMMARY OF THE INVENTION

The present invention, in a first aspect, is directed to a burner tube assembly for a gas power burner. The burner tube assembly generally includes a burner tube, a venturi tube assembly, and a blower mount. The burner tube includes a first end, a second end, a longitudinal axis extending from the first end to the second end, and a plurality of air inlet holes extending from an outer surface to an inner surface of the burner tube adjacent to the second end. The venturi tube assembly is disposed longitudinally in the burner tube and has an inlet portion disposed adjacent to the second end and a burner head portion disposed adjacent to the first end. The blower mount has an opening spaced from the outer surface of the burner tube for receiving a flow of combustion air directed in a first direction towards the burner tube. The opening of the blower mount is disposed out of axial alignment with the plurality of air inlet holes so that a portion of the burner tube and the blower mount form an air manifold for redirecting the flow of combustion air from the first direction around the burner tube and towards the plurality of air inlet holes.

The present invention, in a second aspect, is directed to an impingement oven which includes a housing having a chamber for receiving and heating a heat treatable product, and a gas power burner having a burner tube assembly as described above for supplying heat to said chamber.

The present invention, in a third aspect, is directed to a method for delivering air to a gas power burner. The method includes, providing a flow of combustion air along an axis in a first direction toward an outer surface of a burner tube, redirecting the flow of combustion air around at least a portion of the outer surface of the burner tube, and transferring the flow of the redirected combustion air from an outer surface of said burner tube to an inner surface of said burner tube in a direction different from the first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, may best be understood by reference to the following detailed description of various embodiments and the accompanying drawings in which:

FIG. 1 is a schematic illustration of one embodiment of a gas power burner in accordance with the present invention for use in an oven;

FIG. 2 is a perspective view of a portion of a burner tube assembly of FIG. 1;

FIG. 3 is a side elevational view of one embodiment of a venturi tube assembly which is receivable in the burner tube of FIG. 2;

FIG. 4 is a perspective view of the flame spreader of FIG. 2;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is a cross-sectional view of the blower mount and the burner tube of FIG. 2 illustrating the inlet holes;

FIG. 7 is an exploded perspective view of two halves forming the blower mount of FIG. 2;

FIG. 8 is a flowchart of a method for delivering air to a gas power burner;

FIG. 9 is a side elevational view of an end of a prior art gas power burner illustrating the shape of a flame emitted therefrom;

FIG. 10 is a side elevational view of the end of the gas power burner of FIG. 1 illustrating the shape of a flame emitted therefrom due to the flame spreader;

FIG. 11 is an end elevational view of the gas power burner of FIG. 9 illustrating the break up of the flame into multiple portions emitted therefrom due to the flame spreader;

FIG. 12 is a front perspective view of one embodiment of an oven employing the gas power burner of FIG. 1; and

FIG. 13 is another embodiment of a venture tube assembly which is receivable in the burner tube of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to ovens for heat treating products and may include food preparation ovens that use a gas power burner that meters combustible gas at a rate of about 75,000 BTU/hr.

In a one aspect, the present invention is directed to a burner tube assembly for a gas power burner for use in an oven for heat treating products and may include ovens for preparing pizza and similar types of food products. For example, the gas power burner may be used in an impingement oven having a conveyor wherein food products are baked or cooked by means of jets of hot gaseous fluid such as hot air and wherein the hot air jets are impinged directly upon localized areas of the food product. The gas power burner may also be used in ovens which do not include a conveyor. The burner tube assembly may employ a draft induction air manifold that utilizes, for example, a plurality of equally and circumferentially spaced air apertures formed in the burner tube to ventilate a burner tube to evenly introduce the air with gas for combustion as explained below.

With reference to FIG. 1, a gas power burner 10, in accordance with the present invention is schematically illustrated, which includes a burner tube assembly 12, an air blower 14, and a modulating gas regulator 16 attachable to a gas safety valve 18 which attaches to a gas valve 19.

As shown in FIG. 2, burner tube assembly 12 generally includes a burner tube 20, a blower mount 30, a mounting flange 40, a flame spreader 50, and a venture tube assembly (shown in FIG. 3) which is receivable in burner tube 20.

Burner tube 20 may include a hollow cylindrical metal tube having a first or front end 22, a second or rear end 24, a longitudinal axis L extending from first end 22 to second end 24, and a plurality of air inlet holes 28 (only one of which is shown in FIG. 2) extending from an outer surface to an inner surface of burner tube 20 adjacent to second end 24. Adjacent to first end 22 of burner tube 20 may be mounting flange 40 which may include holes so that the burner tube assembly may be secured to a wall of an oven. The first end may protrude into a combustion chamber of the oven. Flame spreader 50 is disposed and may be attached at the end of first end 22 of burner tube 20 using screws.

As shown in FIG. 3, a venturi tube assembly 60 includes a venturi tube 62 having an inlet portion 64 and a burner head portion 66. Between inlet portion 64 and burner head portion 66, venturi tube 60 has a constricted throat portion 68. Venturi tube 62 expands in diameter from the throat portion toward the burner head portion. The inlet portion may include four air inlet apertures 70 in the sides thereof. The end of inlet portion 64 is attached to a burner cap 80. Disposed within burner head portion 66 may be an annular corrugated flame retention ring which provides a multitude of longitudinal slots between a ring and the venturi tube to cause a flame to burn on the end of the burner head portion and to be evenly distributed about the circumference thereof. Disposed within inlet portion 64 and extending through burner cap 70 is gas orifice for receiving metered pressurized gas. The pressurized gas is mixed with air as described below. The venture tube may be disposed longitudinally and concentrically within burner tube 20 (FIG. 2) with inlet portion 64 disposed adjacent to second end 24 of burner tube 20 and burner head portion 66 disposed adjacent to first end 22 of burner tube 20. FIG. 13 illustrates another embodiment of a venture tube assembly.

As shown in FIGS. 4 and 5, flame spreader 50 may have a twisted fin design. For example, flame spreader 50 may include a plurality of legs 52 which attach to the sides of the end of the burner tube. Between adjacent legs are a plurality of fins 55. The fins and legs may be formed when the flame spreader is cut out. The fins desirably do not extend past the outer legs so that the entire assembly (burner tube, venturi tube assembly, and flame spreader) may be inserted or pushed though a circular ring mounted on the side of the oven. The fins may extend outward about ⅜ inch (9 mm) and are bent or angled to have a 45 degree pitch. The center of the flame spreader is also indented to form a cone 57 (FIG. 5). The cone and the fins result in a swirling of the mixed gas and air for combustion.

With reference again to FIG. 1, the modulating gas valve allows regulating the supply of gas to the gas power burner from 0-percent to 100-percent. For example, the supply of gas may be regulated at intervals, e.g., at 10-percent intervals, or may be variably and continuously regulatable between 0-percent and 100-percent. The modulating gas valve provides a greater degree of regulation of the consumption of the gas compared to a conventional solenoid valve regulator which either turns on or off the supply of gas to the gas power burner. A conventional solenoid valve regulator results in inefficiencies in the heating of the oven due to the peaks and the valleys in the heating cycle. A suitable modulating gas valve is available from Maxitrol of Southfield, Mich. The modulating gas valve may be controlled by a conditioning board which receives inputs from a temperature controller attached to a thermal coupler in the oven.

With reference again to FIG. 2, burner tube 20 and blower mount 30 form a draft induction air manifold which evenly distributes and introduces air toward and around the inlet portion of the venturi tube assembly (FIG. 3) in burner tube 20.

For example, as shown in FIG. 6, blower mount 30 forms a housing which surrounds a portion of second end 24 of burner tube 20. Air from a blower is received in the opening 26 which may be disposed on one side of the blower mount. Opening 26 is spaced from the outer surface of burner tube 20 for receiving a flow of combustion air in a first direction toward burner tube 20.

As described above, burner tube 20 has a plurality of relatively small inlet holes 28 extending therethrough spaced around the circumference of the burner tube for receiving air from blower mount 30 and introducing the air towards the four inlets in inlet portion 64 of the venturi tube assembly as illustrated by the arrows in FIG. 6. The plurality of air inlet holes 28 may be generally evenly spaced around burner tube 20. The plurality of inlet holes may further be disposed so as to be out of alignment from or not in alignment with the inlet from the blower or an axis A1 which corresponds to the direction of the flow of air from the blower. For example, the plurality of air inlets holes 28 may be obscured or hidden from view when viewed through opening 26 of blower mount 30. A portion of burner tube 20 and blower mount 30 form an air manifold for redirecting the flow of combustion air in the first direction around burner tube 20 and toward the plurality of air inlet holes 28. For example, the plurality of air inlets holes may direct the flow of combustion air in a plurality of generally radial directions toward the longitudinal axis of burner tube 20.

Blower mount 30 may be fabricated from two halves 32 and 34 as shown in FIG. 7. From the present description, it will be appreciated that other numbers of air inlet holes, e.g., 2, 3, or more than 4 air inlet holes may be provided. The air inlet holes may be balanced, i.e., each air inlet hole may have an air inlet hole disposed directly across a diameter of the burner tube. Further, from the present description, the blower mount need not have a cube-shaped configuration but may employ other suitable configurations, e.g., a larger sized diameter tube may be employed and disposed around the outside of the burner tube.

FIG. 8 illustrate a flowchart of a method 100 for delivering air to a gas power burner. The method includes at 110, providing a flow of combustion air along an axis in a first direction toward an outer surface of a burner tube, then at 120, redirecting the flow of combustion air around at least a portion of the outer surface of the burner tube, and at 130, transferring the flow of the redirected combustion air from an outer surface of said burner tube to an inner surface of said burner tube in a direction different from the first direction.

Compared to conventional gas power burners which employ a single relatively large hole in the burner tube spaced from the inlet portion of the venturi assembly for receiving all the air directly from the air blower and wherein the relatively large hole in the burner tube is aligned with the axis of the tube from the blower, the present invention by employing a plurality of relatively smaller sized holes and offsetting the holes from the axis of and flow direction from the blower may result in several benefits over conventional gas power burners. For example, the present invention may provide a more evenly distributed air flow towards the base of the venturi tube assembly, a more even pressure around the base of the venturi tube assembly, and an increase the efficiency of the combustion of the gas for a higher yield in performance.

The burner tube may be about 9 inches (230 mm) long and have a diameter of about 3 inches (76 mm). The inlet holes may be about 5/16 inch (4-8 mm) in diameter. The inlet holes may be disposed about ½ inch (14 mm) from the end of the burner tube. The burner tube is desirably capable of withstanding temperatures in the range of about 1,450 degrees Fahrenheit (about 788 degrees Celsius).

In operation of the gas power burner, the flame spreader provides a turbine effect to “throw” the flame from the end of the gas power burner. FIG. 9 illustrates the shape of the flame emitted from a prior art gas power burner 200. As shown in FIG. 10, a flame from gas power burner 10 of the present invention is projected generally radial outwardly or on a slight diagonal from the end of flame spreader 50. In addition, as shown in FIG. 11, fins 55 of flame spreader 50 also break up the flame into multiple sections or portions which results in an increased surface area for the flame resulting in a more efficient combustion and heat effect.

FIG. 12 illustrates an oven 300 for heat treating products and which incorporates gas power burner 10 (FIG. 1) of the present invention for supplying heat. Such oven may include an oven for preparing pizza and similar types of food products. For example, the gas power burner may be used in an impingement oven having a housing 310 having a chamber therein, and a conveyor 320 wherein food products are baked or cooked by means of jets of hot gaseous fluid such as hot air and wherein the hot air jets are impinged directly upon localized areas of the food product. It will be appreciated that a plurality of such ovens may be employed in a stacked configuration.

Thus, while various embodiments of the present invention have been illustrated and described, it will be appreciated to those skilled in the art that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.