Heat Exchanger System

Abstract

A heat exchanger system and a method of assembly is provided for a gas appliance such as a furnace. The heat exchanger system includes an attachment plate having at least one recess sized to receive an inlet of a heat exchanger. The heat exchanger has a first flange disposed at the inlet that is positioned in the recess. A second flange in the attachment plate recess is crimped onto the inlet flange to couple the heat exchanger to the attachment plate. The attachment plate may also include a pair of slots that extend from the recess that are sized to receive a pair of third flanges on the heat exchanger.

Description

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to gas furnaces and in particular to gas furnaces having a sealed connection between a combustion chamber and a primary heat exchanger.

Gas fired appliances, such as residential and light commercial heating furnaces for example, often arrange a combustion chamber in series with one or more heat exchangers. The heated gas from the combustion chamber flows through the heat exchanger that transfers thermal energy from the combustion gas to air passing over the heat exchanger. In general, the pressure within the heat exchanger is less than atmospheric pressure. As a result, atmospheric air may be drawn into the system resulting in a disruption of the combustion process that decreases efficiency.

The connection between the combustion chamber and the heat exchanger is one area where a seal to prevent infiltration of air is desired. This connection is typically adjacent the combustion chamber. As a result, the infiltration of air may impinge upon the flame, which disrupts the combustion process resulting in an incomplete combustion of the fuel. The heat exchanger typically has an inlet with a flange that extends from one end. A flat plate that includes sponge rubber gaskets is crimped to the flange. While this seal arrangement is suitable, the process of crimping requires additional backup tooling to prevent separation of the heat exchanger during assembly. Further, the circular/parallel inlet flange causes aggressive wear on the fabrication tooling.

Accordingly, while existing gas furnaces are suitable for their intended purposes improvements may be made in improving the coupling and sealing of the heat exchanger to a combustion chamber to minimize the impingement of air on the combustion process.

This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a heat exchanger system is provided. The heat exchanger system includes an attachment plate having at least one recess and a pair of slots extending from the at least one recess. A heat exchanger member having an inlet, the inlet having a first flange coupled within the at least one recess and a pair second flanges disposed within the pair of slots.

According to another aspect of the invention, a heat exchanger system for a gas appliance having a combustion chamber is provided. The heat exchanger system includes an attachment plate coupled to the combustion chamber, the attachment plate having at least one recess, a first slot extending from one side of the at least one recess and a second slot extending from the at least one recess opposite the first slot. A heat exchanger member having an inlet fluidly is coupled to receive a combustion gas from the combustion chamber. The inlet has a first flange arranged about an opening and fixedly disposed in the at least one recess, and a pair of second flanges arranged adjacent and substantially perpendicular to the first flange. The pair of second flanges is disposed in the first slot and the second slot.

According to yet another aspect of the invention, a method of assembling a heat exchanger system to a combustion chamber is provided. The method includes the step of providing an attachment plate having at least one recess and a pair of slots extending from the at least one recess. A heat exchanger member is provided having an inlet with a first flange disposed about an opening and a pair of second flanges adjacent the first flange. The first flange is disposed in the at least one recess. The pair of second flanges is disposed in the pair of slots. The heat exchanger member is coupled to the attachment plate in the at least one recess. The inlet is supported with the at least one recess when the heat exchanger member is coupled to the attachment plate.

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

BRIEF DESCRIPTION OF THE DRAWING

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 perspective cut away illustration of a gas furnace in accordance with an embodiment of the invention;

FIG. 2 is a schematic illustration of a combustion chamber and heat exchanger arrangement in accordance with an embodiment of the invention;

FIG. 3 is a perspective illustration of an attachment plate for use with the gas furnace of FIG. 1;

FIG. 4 is a perspective illustration of another embodiment attachment plate for use with the gas furnace of FIG. 1;

FIG. 5 is a perspective view illustration of a primary heat exchanger for use with the gas furnace of FIG. 1;

FIGS. 6-7 are perspective view illustrations of the primary heat exchanger of FIG. 5 being assembled to the attachment plate of FIG. 3;

FIG. 8 is a perspective view illustration of the attachment plate of FIG. 3 crimped onto the primary heat exchanger of FIG. 5; and,

FIG. 9 is a partial cross sectional view of the attachment plate of FIG. 4 crimped onto the primary heat exchanger of FIG. 5.

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

FIG. 1 is a perspective cutaway view of furnace 10. Furnace 10 includes burner assembly 12, combustion chamber 14, combustion air pipe 16, gas valve 18, primary heat exchanger 20, condensing heat exchanger 24, condensate collector box 26, exhaust vent pipe 28, induced draft blower 30, inducer motor 32, thermostat 34, low pressure switch 42, high pressure switch 44, and furnace control 50.

Burner assembly 12 is located within combustion chamber 14 and is supplied with air via combustion air pipe 16. Fuel gas is supplied to burner assembly 12 through gas valve 18, which may be a solenoid-operated gas valve, and is ignited by an igniter assembly (not shown). The gases produced by combustion within combustion chamber 14 flow through a heat exchanger assembly, which includes primary or non-condensing heat exchanger 20, secondary or condensing heat exchanger 24, and condensate collector box 26. It should be appreciated that while only a single heat exchanger 20 is illustrated, the furnace 10 may have multiple heat exchangers 20 coupled in parallel to the combustion chamber 14. The gases are then vented to the atmosphere by inducer motor 32 through exhaust vent pipe 28. The flow of these gases, herein called combustion gases, is maintained by induced draft blower 30, which is driven by inducer motor 32. Inducer motor 32 is driven in response to speed control signals that are generated by a furnace control circuit located within furnace control 50, in response to the states of low pressure switch 42 and high pressure switch 44, and in response to call-for-heat signals received from thermostat 34 in the space to be heated.

Air from the space to be heated is drawn into furnace 10 by blower 52, which is driven by blower motor 54 in response to speed control signals that are generated by furnace control 50. The discharge air from the blower 52, herein called circulating air, passes over condensing heat exchanger 24 and primary heat exchanger 20 in a counter-flow relationship to the flow of combustion air, before being directed to the space to be heated through a duct system (not shown).

It should be appreciated that it is desirable to provide an adequate seal between the combustion chamber 14 and the primary heat exchanger 20. Since the pressure within the primary heat exchanger 20 is lower than atmospheric pressure (ΔP˜0.2-0.3 inches of water, 49.8-74.7 Pascal) air will tend to be drawn into the heat exchanger 20 and combustion chamber 14 disrupting the combustion process. Referring to FIGS. 2-3, in one embodiment the primary heat exchanger 20 is coupled to the combustion chamber 14 by an attachment plate 36. In the exemplary embodiment, attachment plate 36 is formed from a metal sheet material, such as steel or aluminum for example. The sheet is formed with one or more embossed portions or recesses 38 having an opening 40 substantially centered therein as shown in FIG. 3. A flange 48 extends from the opening 40 within the recess 38 to form a groove 56. Extending from each recess are a pair of slots 46 that are arranged substantially 180 degrees apart. The slots 46 intersect and extend between the groove 56 and the edge of the attachment plate 36. As will be discussed in more detail herein, the recess 38, flange 48, groove 56 and slots 46 are sized to receive and cooperate with an inlet opening flange on the primary heat exchanger 20. Further, the attachment plate 36 may include multiple recesses 38 to allow multiple primary heat exchangers 20 to be coupled in parallel to the combustion chamber 14.

The attachment plate 36 may also include a second plurality of recesses 58 disposed about the periphery. The recesses 58 include a hole 60 that is formed in the bottom of the recess 58. The holes 60 may be sized to receive a fastener (not shown) that couples the attachment plate 36 to the combustion chamber 14. In some embodiments, a gasket (not shown) is disposed between the attachment plate 36 and the combustion chamber 14. The recesses 38, 58 provide additional advantages in compressing or pinching the gasket material as the attachment plate is coupled to the combustion chamber 14. It should be appreciated that while the embodiments described herein refer to a separate attachment plate 36, in other embodiment the recesses 38, opening 40, flange 48 and slots 46 may be integrated into the housing of the combustion chamber 14. It should be appreciated that the recesses 58 allow the fasteners to be tightened to the combustion chamber 14 when the primary heat exchanger 20 is installed.

Another embodiment of the attachment plate 36 is illustrated in FIG. 4. In this embodiment, opening 40 has a scalloped flange 62 that includes a plurality of projections 64. In one embodiment, the projections 64 are defined by a smooth curved profile that contiguously extends from a trough portion to a peak portion as the flange 62 extends about the opening 40. In one embodiment, the plurality of projections 64 includes a first projection 66 and a second projection 68 are arranged on opposite sides of the flange 62 with each projection 66, 68 centered on one of the slots 46. As will be discussed in more detail herein, the projections 66, 68 include additional material that provides advantages in reducing or eliminating the infiltration of atmospheric air into the combustion chamber 14.

The primary heat exchanger 20 is formed in two halves 70, 72 from a sheet metal material, such as steel or aluminum for example as shown in FIG. 2 and FIG. 5. The two halves 70, 72 are joined together by a suitable process such as fasteners, crimping, welding, brazing or a combination thereof for example. The primary heat exchanger 20 includes an inlet 74 that is fluidly coupled to receive heated gases from the combustion chamber 14. A serpentine path 76 extends through the heat exchanger 20 providing a surface area for the transfer of heat from the combustion chamber gases to air flowing over the primary heat exchanger 20. The gases leave primary heat exchanger 20 via an outlet 78 that is fluidly coupled to the condensing heat exchanger 24.

In the exemplary embodiment, the inlet 74 has a first flange 80 arranged substantially perpendicular to the flow of combustion gases. The first flange 80 further defines the outer diameter of the inlet opening 82. A pair of second flanges 84 extends away from the inlet 70 and provides an area for the crimping of the two heat exchanger halves 70, 72. The outer surface of the inlet 70 and the first flange 80 are sized to fit within the groove 56 such that the flange 48 of the attachment plate 36 fits within and extends into the opening 82. It should be appreciated that where the two halves 70, 72 meet, a small gap 86 may exist due to the curvature of the material in forming the second flanges 84.

Referring now to FIG. 6-FIG. 8, the assembly of the primary heat exchanger 20 with the attachment plate 36 will be described. The primary heat exchanger 20 is arranged such that the inlet 74 is inserted into the groove 56 with the second flanges 84 aligned with and disposed in the slots 46. With the inlet 74 and attachment plate 36 so arranged, an operator inserts a crimping tool 88 or fixture into the opening 40. When actuated, the tool 86 bends the attachment plate flange 48 over the inlet first flange 80 crimping the flanges 48, 80 and forming a seal without an intermediary gasket or seal member. The recess 38 provides support for the heat exchanger halves 70, 72 while the crimp is being formed. This support by the recess 38 provides advantages in preventing the heat exchanger halves 70, 72 from separating as a result of the radial crimping force applied to the flange 48. It should be appreciated that by preventing separation of the heat exchanger halves 70, 72, an increase in the gap 86 during the crimping process may be prevented or minimized. In one embodiment, the operator may place a sealant, such as a silicone material or a sponge rubber for example, into the groove 56 and slots 46 prior to inserting the primary heat exchanger 20 into the grooves 56 and slots 46. It should be appreciated that the crimping of the attachment plate 36 to the primary heat exchanger 20 provides advantages in improving the seal and also assists in preventing the separation of the heat exchanger halves 70, 72 during the crimping operation.

In embodiments where the attachment plate 36 includes the scalloped flange 62, additional advantages are gained in increasing the amount of material that overlaps the gap 86. As shown in FIG. 9, the projections 66, 68 extend up an inner wall 90 of the inlet 74. In this arrangement, the projections 66, 68 over lap the gap 86 along a portion of the inner wall 90 in addition to the first flange 80. In the event that air does infiltrate the gap 86, the air will be directed with the flow of the combustion gases since the projections 66, 68 extend parallel to the wall 90. By flowing the air in a direction parallel to the combustion gases there would be no or minimal impingement of infiltration air on the combustion flames, and thus not affecting combustion efficiency or reliability.

As disclosed, some embodiments of the invention may include some of the following advantages: improving the seal between the combustion chamber and the heat exchanger inlet; not reducing the efficiency of the combustion process in the event of infiltration; improving the support of the heat exchanger during the assembly process; the directing infiltrating air away from the combustion chamber.

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. A heat exchanger system comprising: an attachment plate having at least one recess and a pair of slots extending from said at least one recess; and,a heat exchanger member having an inlet, the inlet having a first flange coupled within said at least one recess and a pair second flanges disposed within said pair of slots.

2. The heat exchanger system of claim 1 wherein said attachment plate further includes a third flange within said at least one recess, wherein said first flange is coupled to said at least one recess by said third flange.

3. The heat exchanger system of claim 2 wherein said third flange includes a plurality of projections.

4. The heat exchanger system of claim 3 wherein: said heat exchanger member includes a first half coupled to a second half which define a gap in said inlet; and,said plurality of projections includes a first projection adjacent one of said pair of slots and a second projection adjacent a second of said pair of slots.

5. The heat exchanger system of claim 4 wherein: said inlet includes an inner wall; and,said first projection and said second projection are arranged parallel to said inner wall.

6. The heat exchanger system of claim 4 wherein said plurality of projections includes a plurality of curved projections defining a plurality of peak portions and a plurality of trough portions.

7. A heat exchanger system for a gas appliance having a combustion chamber, said heat exchanger system comprising: an attachment plate coupled to said combustion chamber, said attachment plate having at least one recess, a first slot extending from one side of said at least one recess and a second slot extending from said at least one recess opposite said first slot; and,a heat exchanger member having an inlet fluidly coupled to receive a combustion gas from said combustion chamber, said inlet having a first flange about an opening and fixedly disposed in said at least one recess, and a pair of second flanges arranged adjacent and substantially perpendicular to said first flange, said pair of second flanges being disposed in said first slot and said second slot.

8. The heat exchanger system of claim 7 wherein said attachment plate further includes a third flange within said at least one recess, wherein said first flange is coupled to said at least one recess by said third flange.

9. The heat exchanger system of claim 8 wherein said third flange includes a plurality of projections.

10. The heat exchanger system of claim 9 wherein: said heat exchanger member includes a first half coupled to a second half which define a gap in said inlet; and,said plurality of projections includes a first projection said first slot and a second projection adjacent said second slot.

11. The heat exchanger system of claim 10 wherein said first projection and said second projection are arranged parallel to a flow direction of said combustion gas.

12. The heat exchanger system of claim 11 wherein: said inlet includes an inner wall; and,said first projection and said second projection are arranged parallel to said inner wall.

13. The heat exchanger system of claim 12 wherein said plurality of projections includes a plurality of curved projections defining a plurality of peak portions and a plurality of trough portions.

14. A method of assembling a heat exchanger system to a combustion chamber comprising: providing an attachment plate having at least one recess and a pair of slots extending from said at least one recess;providing a heat exchanger member having an inlet with a first flange disposed about an opening and a pair of second flanges adjacent said first flange;disposing said first flange in said at least one recess;disposing said pair of second flanges in said pair of slots; and,coupling said heat exchanger member to said attachment plate in said at least one recess; and,supporting said inlet with said at least one recess when said heat exchanger member is coupled to said attachment plate.

15. The method of claim 14 further comprising: providing said attachment plate with a third flange disposed within said at least one recess; and,bending said third flange about said first flange to couple said heat exchanger member to said attachment plate.

16. The method of claim 15 further comprising providing a radial crimping force said third flange on said first flange to form a seal.

17. The method of claim 16 wherein said third flange includes a plurality of projections and said plurality of projections includes a first projection aligned with one of said pair of slots and a second projection aligned with a second of said pair of slots.

18. The method of claim 17 wherein: said inlet has an inner wall; and,said bending of said third flange bends said first projection and said second projection such that a portion of said first projection and said second projection are arranged substantially parallel to said inner wall.

19. The method of claim 17 wherein: said heat exchanger member includes a first heat exchanger half and a second heat exchanger half and a gap disposed in said inlet between said first heat exchanger half and said second heat exchanger half; and,said bending of said first projection and said second projection includes bending said first projection and said second projection over said gap.

20. The method of claim 19 wherein said supporting of said inlet prevents an increase in a size of said gap when said first projection and said second projection are bent over said gap.