UNITARY IGNITER AND FLAME SENSOR

Abstract

An integral igniter and flame sensor for a furnace includes a mounting base installable in an access port to a burner in a furnace. An igniter extends from the mounting base toward at least one burner of the furnace, and a flame sensor extends from the same mounting base toward the at least one burner. A furnace includes a housing and a heat exchange portion located in the housing. The heat exchange portion includes a heat exchanger and a burner assembly located to heat the heat exchanger. The burner assembly includes at least one burner and an integral igniter and flame sensor. The integral igniter and flame sensor includes a mounting base installable in an access port to the at least one burner. An igniter extends from the mounting base toward the at least one burner and a flame sensor extends from the same mounting base toward the same burner.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional application, 61/604,937, filed Feb. 29, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to furnaces. More specifically, the subject matter disclosed herein relates to burners for furnaces.

In a typical gas-fired warm air furnace, the furnace includes multiple heat exchanger cells or tubes with a burner, typically an in-shot burner, dedicated to each heat exchanger cell. The burners are typically lit by a single igniter at an end burner, and the flame is carried to the other burners via carryovers extending between the burners. To ensure that the burners are all lit, a flame sensor is located at an end burner, at an opposite end from the igniter. Sensing flame in that location indicates that the flame has successfully carried over from the burner where the igniter is located.

Emissions requirements, such as those for NO_R, placed on gas-fired furnaces have led to the desire to utilize pre-mix burners in furnaces. Use of such burners results in lower NO emissions compared to in-shot burners, but replacing in-shot burners with pre-mix burners in a typical furnace structure results in excessively high temperatures in the vestibule and on the heat exchanger cell wall.

BRIEF DESCRIPTION OF THE INVENTION

An integral igniter and flame sensor for a furnace includes a mounting base installable on an access port to a burner in a furnace. An igniter extends from the mounting base toward the burner, and a flame sensor extends from the mounting base toward the same burner.

A burner assembly for a furnace includes at least one burner and an integral igniter and flame sensor. The integral igniter and flame sensor includes a mounting base installable on an access port to the burner. An igniter extends from the mounting base toward the burner, and a flame sensor extends from the mounting base toward the same burner.

A furnace includes a housing and a heat exchange portion located in the housing. The heat exchange portion includes a heat exchanger and a burner assembly located to heat the heat exchanger. The burner assembly includes at least one burner and at least one integral igniter and flame sensor. The integral igniter and flame sensor includes a mounting base installable to an access port to the burners in the furnace. An igniter extends from the mounting base toward the at least one burner and a flame sensor extends from the mounting base toward the same burner.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of an embodiment of a furnace assembly;

FIG. 2 is a schematic view of an embodiment of a burner assembly for a furnace;

FIG. 3 is a schematic view of an embodiment of an integral igniter and flame sensor for a furnace;

FIG. 4 is a schematic view of another embodiment of an integral igniter and flame sensor for a furnace;

FIG. 5 is a schematic view of another embodiment of an integral igniter and flame sensor for a furnace; and

FIG. 6 is a schematic view of yet another embodiment of an integral igniter and flame sensor.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Shown in FIG. 1 is an embodiment of a furnace assembly 10. The furnace assembly 10 comprises a housing 12. The housing 12 includes three primary chambers, a blower chamber 14 containing a blower 16, a heat exchange chamber 18 containing a heat exchanger 20, and a portion of a burner assembly 22, and a vestibule chamber 24, which also contains a portion of burner assembly 22. The burner assembly 22 heats the heat exchanger 20, and as the blower 16 blows an air flow 26 across the heat exchanger 20, thermal energy is transferred from the heat exchanger 20 to the air flow 26.

Referring to FIG. 2, the burner assembly 22 includes a plurality of burners 28, which in some embodiments are premix burners 28. The embodiment of FIG. 2 includes 3 burners 28, but it is to be appreciated that burner assemblies 22 with other quantities of burners 28 are contemplated within the present scope. Each burner 28 includes at least one orifice 30 for injecting fuel or a fuel/air mixture from a manifold 48 toward the heat exchanger 20 for combustion. To light the burners 28, an igniter 36 (shown in FIGS. 3-5) is located at each of the burners 28 to ignite the fuel ejected from the orifice 30, typically between the burner 28 and the heat exchanger 20. In this embodiment, an igniter/flame sensor assembly 32 is located at each burner 28 of the plurality of burners 28, eliminating the need for crossovers of the prior art between burners 28. As shown in FIGS. 3-5, the igniter/flame sensor assembly 32 includes a mounting base 34, typically of a ceramic or metallic material, that when installed in the furnace 10, fits over a burner access port 38. The igniter 36 extends from the mounting base 34, and is positioned at the burner 28.

Referring now to FIG. 3, the igniter/flame sensor assembly 32 further includes a flame sensor 42 extending from the same mounting base 34 as the igniter 36 to sense a flame at the burner 28 when the burner 28 is operating. By integrating the flame sensor 42 with the igniter 36 on the common mounting base 34, it eliminates a need for a separate mounting base, and a separate opening at the burners 28 for the flame sensor, thus reducing paths for thermal energy transfer into the vestibule chamber 24.

In one embodiment, as shown in FIG. 3, the flame sensor 42 is a screen flame sensor 42 including a sleeve 44 with a plurality of sleeve openings 46 surrounding the igniter 36. In another embodiment, as shown in FIG. 4, the flame sensor 42 is a substantially helical shape wound around the igniter 36. In still another embodiment, as shown in FIG. 5, the flame sensor 42 is partially surrounded by a semi-circular igniter 36. It is to be appreciated, however, that these integral flame sensor 42 and igniter 36 configurations are merely exemplary, and other flame sensor 42 and igniter 36 configurations are contemplated within the present disclosure. For example, in another embodiment, the igniter 36 and the flame sensor 42 may extend from the same mounting base 34 substantially parallel to each other, without overlapping. While the embodiments of FIGS. 3, 4 and 5 illustrate hot surface igniters 36, other types of igniters may be utilized. In another embodiment, as shown in FIG. 6, the flame sensor 42 and a sparker 48, serving as the igniter in this embodiment, both extend from the common mounting base 34. The sparker 48 includes two sparker rods 50, that when one sparker rod 50 is energized with an electric current and the other sparker rod 50 is grounded, causes a spark to occur at a gap 52 between tips 54 of the sparker rods 50.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

1. An integral igniter and flame sensor assembly for a furnace comprising:

a mounting base installable in an access port to the burner in a furnace;

an igniter extending from the mounting base toward at least one burner of the furnace; and

a flame sensor extending from the mounting base toward the at least one burner.

2. The assembly of claim 1, wherein the flame sensor extends at least partially around a perimeter of the igniter.

3. The assembly of claim 2, wherein the flame sensor comprises a screen having a plurality of screen openings around the igniter.

4. The assembly of claim 2, wherein the flame sensor comprises a helical coil wrapped around the igniter.

5. The assembly of claim 2, wherein the igniter extends at least partially around a perimeter of the flame sensor.

6. A burner assembly for a furnace comprising:

at least one burner; and

an integral igniter and flame sensor including: a mounting base installable in an access port to the at least one burner in the furnace; an igniter extending from the mounting base toward the at least one burner; and

a flame sensor extending from the mounting base toward the at least one burner.

7. The burner assembly of claim 6, wherein the at least one burner is a premix burner.

8. The burner assembly of claim 6, wherein the flame sensor extends at least partially around a perimeter of the igniter.

9. The burner assembly of claim 8, wherein the flame sensor comprises a screen having a plurality of screen openings around the igniter.

10. The burner assembly of claim 8, wherein the flame sensor comprises a helical coil wrapped around the igniter.

11. The burner assembly of claim 6, wherein the igniter extends at least partially around a perimeter of the flame sensor.

12. A furnace comprising:

a housing;

a heat exchange portion disposed in the housing including: a heat exchanger; and a burner assembly located to heat the heat exchanger, the burner assembly including: at least one burner; and

an integral igniter and flame sensor including:

a mounting base installable in an access port to the at least one burner in the furnace;

an igniter extending from the mounting base toward the at least one burner; and

a flame sensor extending from the mounting base toward the at least one burner.

13. The furnace of claim 12, wherein the at least one burner is a premix burner.

14. The furnace of claim 12, wherein the flame sensor extends at least partially around a perimeter of the igniter.

15. The furnace of claim 14, wherein the flame sensor comprises a screen having a plurality of screen openings around the igniter.

16. The furnace of claim 14, wherein the flame sensor comprises a helical coil wrapped around the igniter.

17. The furnace of claim 12, wherein the igniter extends at least partially around a perimeter of the flame sensor.