Stoves and furnaces – Hot-air furnaces – Compressed air
Reexamination Certificate
2000-05-10
2001-05-01
Lazarus, Ira S. (Department: 3743)
Stoves and furnaces
Hot-air furnaces
Compressed air
C310S062000, C310S063000, C310S065000, C417S368000, C110S219000
Reexamination Certificate
active
06223740
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to fuel-fired heating appliances and, in a preferred embodiment thereof, more particularly relates to a fuel-fired, forced draft furnace having a specially designed self-cooling draft inducer fan.
In a forced draft fuel-fired heating appliance, such as a gas-fired air heating furnace, combustion products from a heat exchanger into which burner flames are injected are exhausted (after a substantial amount of heat is extracted from the combustion products by supply air passed exteriorly over the heat exchanger) from the heat exchanger by a draft inducer fan. A draft inducer fan of conventional construction and operation typically has a housing with an inlet opening formed on an inboard side thereof and mounted over a hole in a center panel portion of the furnace which forms a wall of the furnace housing portion in which the heat exchanger is disposed in the path of supply air being flowed through the furnace housing for heating therein.
An impeller wheel within the inducer fan housing is rotated by an electric motor carried by the housing and projecting outwardly from its outboard side, to draw spent combustion products into the fan housing and then discharge them to a flue structure operatively coupled to the outlet of the inducer fan. To cool the draft inducer fan motor, first and second small auxiliary cooling fans are typically connected to the drive shaft of the draft inducer fan. The first cooling fan is coaxially coupled to the inducer fan drive shaft between the electric motor and the inducer fan housing and functions, during operation of the inducer fan, to direct a cooling stream of air against the inboard shaft end bearing. The second cooling fan is coaxially coupled to the inducer fan drive shaft outboard of the electric motor and functions, during operation of the inducer fan, to direct a cooling stream of air against the motor windings and the outboard shaft end bearing.
This conventional arrangement of two auxiliary cooling fans associated with a draft inducer fan carries with it several well known problems, limitations and disadvantages. For example, this multi-fan arrangement undesirably adds to the operating noise level of the overall draft inducer fan assembly. Moreover, the previous necessity of using three fans in the overall draft inducing structure adds to the cost, complexity and space requirements for such structure. Additionally, the cooling air flow used to cool the inboard motor shaft end bearing can be deflected from the inducer fan housing against the adjacent fuel burner structures in a manner undesirably disrupting their flame patterns.
As can readily be seen from the foregoing, a need exists for an improved draft inducer fan structure that eliminates or at least substantially reduces these problems, limitations and disadvantages typically associated with conventional self-cooling draft inducer fan assemblies of the type generally described above. It is to this need that the present invention is directed.
SUMMARY OF THE INVENTION
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, fuel-fired heating apparatus, illustratively in the form of a gas-fired, forced draft air heating furnace, is provided has a wall structure defining a chamber for receiving a fluid to be heated, a heat exchanger disposed in the chamber and operative to receive a throughflow of hot combustion products and transfer combustion heat to the received fluid, and a fuel burner operative to introduce a flame and resulting hot combustion products into the heat exchanger.
According to a feature of the present invention, the fuel-fired heating apparatus is provided with a specially designed, self-cooling draft inducer fan assembly that includes a draft inducer fan, a single cooling fan, and a specially designed baffle structure.
The draft inducer fan is coupled to the heat exchanger and is operative to force therethrough combustion products received from the fuel burner. A motor outwardly projects from the housing side and is coupled to a drive shaft having outboard and inboard end portions respectively and rotationally carried by outboard and inboard bearing structures. The single cooling fan is representatively an umbrella type cooling fan and is secured to the outboard end of the drive shaft and is rotatable thereby to create a flow of cooling air which is directed toward the housing side and sequentially passes and cools the outboard bearing structure, a portion of the motor, and the inboard bearing structure. The baffle structure is associated with the housing side and is operative to receive air discharged from the cooling fan and facilitate contact between the received air and the inboard bearing structure. By virtue of the use of this baffle structure, the single cooling fan is able to cool the motor and both of the inboard and outboard bearing structures.
In a preferred embodiment of the fuel-fired heating apparatus, the draft inducer fan is disposed adjacent the fuel burner, which is illustratively an inshot-type gas burner, and the baffle structure is further operative to deflect the received air away from the fuel burner in a manner preventing the cooling air from being deflected off the fan housing in a manner impinging on and disrupting the burner flame. Illustratively, the baffle structure includes first and second nonparallel wall portions projecting in an edgewise direction outwardly from the housing side and having a gap between sections thereof through which the received air is discharged from the baffle structure in a direction generally transverse to the axis of the drive shaft.
Representatively, the first and second baffle structure wall portions are arranged in a generally V-shaped configuration and are transversely secured to a base wall section which is suitably secured to the housing side and interposed between the housing side and the inboard bearing section. The draft inducer fan is secured to the chamber wall structure of the apparatus above the fuel burner structure, and the side gap in the generally V-shaped baffle structure wall portion is arranged in a manner such that the cooling air received by the baffle structure is generally horizontally discharged from the gap.
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Kepesky Robert I.
Kim Seung-Ho
Painter Walter S.
Konneker & Smith P.C.
Lazarus Ira S.
Lee David
Rheem Manufacturing Company
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