Furnace inducer motor cooling system

Information

  • Patent Grant
  • 6352431
  • Patent Number
    6,352,431
  • Date Filed
    Thursday, November 2, 2000
    23 years ago
  • Date Issued
    Tuesday, March 5, 2002
    22 years ago
Abstract
A furnace includes a main blower housed in an inlet plenum that circulates temperature controlled air through the furnace and an inducer fan that circulates combustion gases through the furnace. The inducer fan is driven by an inducer fan motor with a housing that defines a hollow interior and surrounds the motor. The inducer fan motor housing is in communication with the inlet plenum and operation of the main blower draws cooling air through the interior of the motor housing to cool the motor.
Description




BACKGROUND OF THE INVENTION




(i) Field of the Invention




This invention relates generally to furnaces and particularly to cooling a motor that drives a draft inducing fan in a furnace. The invention provides for an improved method of cooling the motor that drives the inducer fan and an apparatus for practicing the method.




(ii) Description of the Related Art




Typically, a household furnace includes an inducer fan and motor that draw a flow of air through a combustion chamber and then a heat exchanger of the furnace before exhausting the combustion gases from the furnace, and a blower fan and motor that draw a flow of air into the furnace and blow the flow of air across the heat exchanger to heat the air and then deliver the heated air to the conduit system that directs the heated air through the household.




In typical prior art furnaces, the fan motor is located in the vestibule of the furnace which also houses the electronics and controls for controlling the furnace. The heat generated by the blower motor elevates the temperature within the vestibule. The elevated temperature within the vestibule can shorten the life of the electronics and controls located within the vestibule. Additionally, the excess heat generated by the motor can shorten the life of the motor itself.




Typical prior art furnace fans utilize a motor that has an auxiliary fan attached to the rotating shaft of the motor to cool the motor. The auxiliary fan forces a flow of air across the motor to dissipate the heat generated by the motor. An auxiliary fan, however, has many disadvantages.




One disadvantage is that the auxiliary fan increases the size or height of the motor assembly thereby preventing the streamlining of the motor assembly and the associated furnace within which the motor assembly is used. Another disadvantage is that the use of an auxiliary fan produces an additional load on the motor which can reduce the overall motor efficiency and increase the energy consumption of the furnace in which is it used. Furthermore, the use of an auxiliary fan increases the cost of manufacturing the draft inducing fan. Another disadvantage is that the auxiliary fan can generate additional noise which may require the furnace within which it is used to incorporate additional sound deadening techniques. Finally, because the motor is typically used in a vestibule, the airflow of the auxiliary fan is channeled into the vestibule thereby contributing to the elevated temperature of the vestibule and the associated components residing therein.




Therefore, it is an object of the present invention to provide an apparatus and method for cooling the motor that eliminates the need for an auxiliary fan.




SUMMARY OF THE INVENTION




The present invention overcomes shortcomings of prior art furnaces that use an auxiliary fan attached to the motor to cool the motor driving the draft inducing fan by providing a furnace that cools the motor with the flow of air induced by the draft inducing fan. By eliminating the need for an auxiliary fan, the present invention allows for the motor and fan assembly to be more compact and streamlined than the prior art motor, fan and auxiliary fan assemblies. Additionally, the present invention reduces the overall cost of providing a means to cool the motor while reducing the noise associated with cooling the motor with only a minimal load being placed on the motor.




In general, the furnace of the present invention is comprised of a motor which resides in a housing having at least one inlet and at least one outlet. A fan is driven by the motor and resides in a fan housing. The fan housing is operatively connected to and communicates with the motor housing and is configured and adapted to cause a flow of air to flow through the motor housing prior to entering the fan housing, thereby cooling the motor.




More specifically, the furnace is comprised of a motor in a motor housing having at least one inlet and at least one outlet. A combustion chamber has at least one inlet and an outlet with the at least one combustion chamber inlet being operatively connected to and communicating with the at least one motor housing outlet. A heat exchanger has an inlet and an outlet with the heat exchanger inlet being operatively connected to and communicating with the combustion chamber outlet. A fan driven by the motor resides in a fan housing and the fan housing has an inlet and an outlet. The heat exchanger outlet is operatively connected to and communicates with the fan housing inlet. The fan causes a flow of air to flow into the motor housing through the at least one motor housing inlet, around the motor, and exit the motor housing through the at least one motor housing outlet. The flow of air then flows into the combustion chamber through the at least one combustion chamber inlet, through the combustion chamber, and exits the combustion chamber through the combustion chamber outlet. The flow of air then flows into the heat exchanger through the heat exchanger inlet, through the heat exchanger, and exits the heat exchanger through the heat exchanger outlet. The flow of air then flows into the fan housing through the fan housing inlet and exits the fan housing through the fan housing outlet. The flow of air cools the motor as it flows through the motor housing and around the motor without the need for an auxiliary fan.




In another embodiment of the invention, the furnace is provided with a main blower in an inlet plenum of the furnace for circulating temperature controlled air through the furnace and an inducer fan for circulating combustion gases through the furnace that heat the circulated temperature controlled air. The inducer motor for driving the inducer fan is provided with a motor housing that defines a hollow interior of the motor housing that surrounds the motor. The motor housing is placed in communication with the inlet plenum. During operation of the main blower, cooling air is drawn through the interior of the inducer fan motor housing and into the inlet plenum of the furnace. The flow of air cools the inducer motor as it flows through the motor housing and around the motor without the need for an auxiliary fan on the inducer motor.











BRIEF DESCRIPTION OF THE DRAWINGS




Further objectives and features of the present invention are set forth in the following detailed description of the preferred embodiment of the invention and in the drawing figures wherein:





FIG. 1A

is schematic drawing of a traditional furnace employing one embodiment of the present invention to cool the motor driving the fan;





FIG. 1B

is a schematic drawing of the furnace of

FIG. 1A

wherein the combustion chamber has a single inlet and the vestibule chamber has a plurality of inlets;





FIG. 2A

is a schematic drawing of a traditional furnace employing an alternative embodiment of the present invention to cool the motor that drives the fan;





FIG. 2B

is a schematic drawing of the furnace of

FIG. 2A

wherein the air passageway has a single outlet;





FIG. 3

is a schematic drawing of another embodiment of the furnace; and





FIG. 4

is a schematic drawing of an alternate embodiment of the furnace of the present invention where cooling air is drawn across the inducer motor by operation of a main blower of the furnace.











DETAILED DESCRIPTION OF THE INVENTION




The furnace, as can be seen in FIG.


1


A and generally indicated as


20


, is basically comprised of a blower


22


which draws a flow of air


24


from the exterior environment and draws the flow of air


24


through a heat exchanger


26


wherein the flow of air


24


is heated and flows out of the heat exchanger and back into the environment which is to be heated by the furnace


20


. The furnace


20


heats the flow of air


24


in the heat exchanger


26


by drawing a flow of combustion heated air


28


through the heat exchanger


26


. The flow of combustion heated air


28


is drawn through the heat exchanger


26


by a fan


30


which is driven by a motor


32


. The flow of air


28


is heated in a combustion chamber


34


by burners


35


or the like, as is well known in the industry, prior to be drawn through the heat exchanger


26


. The flow of combustion air


28


is drawn into the fan


30


and exhausted through an exhaust pipe


36


. In the case of a high efficiency furnace, the air being drawn into the combustion chamber


34


originates from outside the furnace


20


and can be in the room environment or outside the environment which is to be heated and is drawn into the furnace through the inlet pipe


38


. Although, it should be understood that while the exhaust and inlet pipes


36


,


38


have been described as pipes they can be part of a chimney or other air channeling structures as are well known in the industry.




Preferably, the motor


32


resides in a housing


40


having at least one inlet


42


and at least one outlet


44


. The fan


30


which is driven by the motor


32


resides in a fan housing


46


and is operatively connected to and communicates with the at least one motor housing outlet


44


and is configured and adapted to cause a flow of air


48


to flow through the motor housing


40


prior to flowing through the fan housing


46


. The flow of air


48


thereby cools the motor


32


as it flows through the motor housing


40


and around the motor


32


.




Preferably, the combustion chamber


34


has at least one inlet


50


and an outlet


52


. The at least one combustion chamber inlet


50


is operatively connected to and communicates with the at least one motor housing outlet


44


so that the flow of air


48


through the motor housing


40


flows through the combustion chamber


34


prior to flowing into the fan housing


46


. The heat exchanger


36


has an inlet


54


and an outlet


56


. The heat exchanger inlet


54


is operatively connected to and communicates with the combustion chamber outlet


52


and the heat exchanger outlet


56


is operatively connected to and communicates with the fan housing


46


. The flow of air


48


through the combustion chamber


34


flows through the heat exchanger


26


prior to flowing into the fan housing


46


. The fan housing


46


has an inlet


58


and an outlet


60


. The fan housing inlet


58


is operatively connected to and communicates with the heat exchanger outlet


56


and the fan housing outlet


60


is operatively connected to and communicates with the exhaust pipe


36


. The fan


30


causes the flow of air


48


to enter the motor housing


40


through the at least one motor housing inlet


42


, flow around the motor


32


and through the motor housing


40


, and then exit the motor housing


40


through the at least one motor housing outlet


44


. The flow of air


48


then flows into the combustion chamber


34


through the at least one combustion chamber inlet


50


and through the combustion chamber


34


where it mixes with the furnace fuel and is heated by combustion, and then exits the combustion chamber


34


through the combustion chamber outlet


52


. The flow of combustion heated air


48


then flows into the heat exchanger


26


through the heat exchanger inlet


54


and through the heat exchanger


26


, and then exits the heat exchanger


26


through the heat exchanger outlet


56


. The flow of combustion heated air


48


then flows into the fan housing


46


through the fan housing inlet


58


and through the fan housing


46


, and then exits the fan housing


46


through the fan housing outlet


60


. The flow of air


48


then exits the furnace


20


through the exhaust pipe


36


. The flow of air


48


thereby cools the motor


32


as it flows through the motor housing


40


and around the motor


42


.




Preferably, the furnace


20


also has a vestibule chamber


62


which has at least one inlet


64


. The motor


32


and the motor housing


46


reside in an interior


66


of the vestibule chamber


62


. In a typical furnace, the vestibule chamber interior


66


also contains the electronics and controls (not shown) to control the operation of the furnace


20


. The flow of air


28


being drawn into the furnace


20


by the fan


30


flows through the at least one vestibule chamber inlet


64


prior to flowing through the combustion chamber


34


.




In a preferred embodiment, as can be seen in

FIGS. 1A and B

, the at least one motor housing outlet


44


is connected to and communicates with the at least one combustion chamber inlet


50


by an air passageway


68


. The air passageway


68


channels the flow of air


48


from the at least one motor housing outlet


44


to the at least one combustion chamber inlet


50


. The flow of air


48


flowing through the motor housing


40


flows through the vestibule chamber interior


66


prior to flowing into the motor housing


40


. The flow of air


48


thereby cooling the electronics and controls (not shown) and any other components that reside in the vestibule chamber interior


66


along with cooling the motor


32


.




In one aspect of the preferred embodiment, the at least one motor housing inlet


42


is one of a plurality of motor housing inlets


70


and the at least one vestibule chamber inlet


64


is one of a plurality of vestibule chamber inlets


72


. The flow of air


28


being drawn into the furnace


20


by the fan


30


flows through the plurality of vestibule chamber inlets


72


and into the vestibule chamber interior


66


. The flow of air


48


that flows through the motor housing


40


flows from the vestibule chamber interior


66


and into the motor housing


40


through the plurality of motor housing inlets


70


.




In another aspect of the preferred embodiment, the combustion chamber


34


is sealed, as shown in FIG. I B, and all the air flowing through the combustion chamber


34


flows through the air passageway


68


prior to flowing into the combustion chamber


34


. Because the combustion chamber


34


is sealed, the flow of air


28


being drawn into the furnace


20


by the fan


30


is the same flow of air


48


that is flowing through the motor housing


40


. The flow of air


28


enters the vestibule chamber interior


66


through the at least one vestibule chamber inlet


64


and flows into the motor housing


40


through the at least one motor housing inlet


42


. The flow of air


28


then flows through the motor housing


40


and into the air passageway


68


through the at least one motor housing outlet


44


. The flow of air


28


then flows through the air passageway


68


and into the combustion chamber


34


through the at least one combustion chamber inlet


50


, which is connected to the air passageway


68


and exits the combustion chamber


34


through the combustion chamber outlet


52


. The flow of air


28


then flows through the heat exchanger


26


and the fan housing


46


as previously discussed. Because all of the air being drawn into the furnace


20


by the fan


30


flows through the motor housing


40


, a maximum amount of air flows through the motor housing


40


and a maximum amount of cooling is achieved.




In yet another aspect of the preferred embodiment, as can been seen in

FIG. 1A

, the at least one combustion chamber inlet


50


is one of a plurality of combustion chamber inlets. The plurality of combustion chamber inlets include a main combustion chamber inlet


76


and secondary combustion chamber inlet


78


. The main combustion chamber inlet


78


is connected to and communicates with the air passageway


68


so that the flow of air


48


flowing through the motor housing


40


flows through the air passageway


68


and into the combustion chamber


34


through the main combustion chamber inlet


76


. The secondary combustion chamber inlet


78


is open to and communicates with the vestibule chamber interior


66


. Because the combustion chamber


34


has a plurality of inlets that communicate with both the motor housing


40


and the vestibule chamber interior


66


, a first portion


80


of the flow of air


28


being drawn into the furnace


20


by the fan


30


will flow from the vestibule chamber interior


66


and into the motor housing


40


and through the air passageway


68


and then enter the combustion chamber


34


through the main combustion chamber inlet


76


. A second portion


82


of the flow of air


28


being drawn into the furnace


20


by the fan


30


will flow from the vestibule chamber interior


66


directly into the combustion chamber


34


through the secondary combustion chamber inlet


78


. The first and second portions


80


,


82


join together in the combustion chamber


34


and are drawn through the rest of the furnace


20


as described above. Because the flow of air


24


being drawn into the furnace


20


by the fan


30


will follow the path of least resistance, the resistance encountered by the first and second portions


80


,


82


of the flow of air


28


must be designed and balanced so that a sufficient amount of air flows through the motor housing


40


to cool the motor


32


. The resistance to the first portion


80


of the air flow


28


is determined generally by the number, size, location and spacing of the plurality of motor housing inlets


70


and the spacing and restrictions experienced between the motor housing


40


and the motor


32


and any obstructions encountered within the air passageway


68


prior to flowing into the combustion chamber


34


. The resistance encountered by the second portion


82


of the air flow


28


is generally determined by the size, dimension and location of the secondary combustion chamber inlet


78


. While the secondary combustion chamber inlet


78


has been shown as being a single inlet, it should be understood that the secondary combustion chamber inlet


78


can be one of a plurality of secondary combustion chamber inlets without departing from the scope of the invention as defined by the claims.




In an alternate embodiment, as shown in

FIGS. 2A and B

, the at least one vestibule chamber inlet


64


is connected to and communicates with the at least one motor housing inlet


42


by an air passageway


84


having at least one inlet


86


and at least one outlet


88


. The air passageway


84


causes the flow of air


48


through the motor housing


40


to originate outside of the vestibule chamber


62


and flow through the at least one vestibule chamber inlet


64


and the at least one air passageway inlet


86


prior to entering the motor housing


40


. The at least one air passageway outlet


88


is connected to the at least one motor housing inlet


42


and the flow of air


48


flowing through the motor housing


40


flows from the air passageway


84


through the at least one air passageway outlet


88


and into the motor housing


40


through the at least one motor housing inlet


42


. The flow of air


48


then exits the motor housing


40


through the at least one motor housing outlet


44


and flows into the vestibule chamber interior


66


. The vestibule chamber interior


66


is operatively connected to and communicates with the at least one combustion chamber inlet


50


so that the flow of air


48


exiting the motor housing


40


and entering the vestibule chamber interior


66


flows through the vestibule chamber interior


66


and then into the combustion chamber


34


through the at least one combustion chamber inlet


50


. Preferably, the vestibule chamber


62


is sealed so that the entire flow of air


28


being drawn into the furnace


20


by the fan


30


flows through the at least one vestibule chamber inlet


64


and through the air passageway


84


. Because the vestibule chamber


62


is sealed, all air flowing through the vestibule chamber interior


66


flows into the combustion chamber


34


through the at least one combustion chamber inlet


50


.




In one aspect of the alternate embodiment, as can be seen in

FIG. 2A

, the at least one air passageway outlet


88


is one of a plurality of air passageway outlets. The air passageway


84


has a primary air passageway outlet


90


and at least one secondary air passageway outlet


92


. The primary air passageway outlet


90


is connected to the at least one motor housing inlet


42


and the at least one secondary air passageway outlet


92


is open to the vestibule chamber interior


66


. Because the air passageway


84


has a plurality of outlets, the flow of air


28


being drawn into the furnace


20


by the fan


30


will be split into a plurality of flows of air. A first portion


94


of the flow of air


28


will be channeled through the air passageway


84


and into the motor housing


40


through the primary air passageway outlet


90


. The first portion


94


of the flow of air


28


is the same as the flow of air


48


flowing through the motor housing


40


. The first portion


94


of the flow of air


28


exits the motor housing


40


through the at least one motor housing outlet


44


and flows into the vestibule chamber interior


66


. A second portion


96


of the flow of air


28


will be channeled through the air passageway


84


and into the vestibule chamber interior


66


through the at least one secondary air passageway outlet


92


. Because the vestibule chamber


62


is sealed the first and second portions


94


,


96


of the flow of air


28


can mix together in the vestibule chamber interior


66


and are both drawn into the combustion chamber


34


through the at least one combustion chamber inlet


50


. The first and second portions


94


,


96


then flow through the heat exchanger


42


and the fan housing


46


and are exhausted from the furnace


20


through the exhaust pipe


36


.




When the air passageway


84


has both a primary air outlet


90


and at least one secondary air passage outlet


92


, the flow of air


28


being drawn into the furnace


20


by the fan


30


will follow the path of least resistance when being drawn into the combustion chamber


34


. Therefore, the resistance experienced by the first portion


94


of the flow of air


28


and the second portion


96


of the flow of air


28


must be designed and balanced to ensure that the first portion


94


of the flow of air


28


which flows through the motor housing


40


is adequate to cool the motor


32


. As was discussed above, the general factors that effect the resistance experienced by the first and second portions


94


,


96


of the flow of air


28


include the size, location and obstructions experienced by both the first and second portions


94


,


96


of the flow of air


28


as they follow their respective flow paths.




In another aspect of the alternate embodiment, as can be seen in

FIG. 2B

, the at least one air passageway outlet


88


is a single air passageway outlet


98


and is connected to the at least one motor housing inlet


42


. The air passageway


84


channels the flow of air


28


being drawn into the furnace


20


by the fan


30


through the single air passageway outlet


98


and into the motor housing


40


through the at least one motor housing inlet


42


. The entire flow of air


28


through the furnace flows through the motor housing


40


. A maximum amount of air flows through the motor housing


40


to cool the motor


32


and a maximum amount of cooling occurs.




In yet another alternate embodiment, as can be seen in

FIG. 3

, the at least one vestibule chamber inlet


64


is connected to the at least one motor housing inlet


42


by a first air passageway


100


. The first air passageway


100


causes the flow of air


28


being drawn into the furnace


20


by the fan


30


to originate outside of the vestibule chamber


62


and flow through the at least one vestibule chamber inlet


64


, through the first air passageway


100


, and into the motor housing


40


through the at least one motor housing inlet


42


. The at least one motor housing outlet


44


is connected to the at least one combustion chamber inlet


50


by a second air passageway


102


. The second air passageway


102


causes the flow of air


28


to flow from the motor housing


40


, through the at least one motor housing outlet


44


, through the second air passageway


102


and into the combustion chamber


34


through the at least one combustion chamber inlet


50


. The flow of air


28


then flows through the heat exchanger


28


, through the fan housing


46


and exits the furnace


20


through the exhaust pipe


36


.




In yet another alternate embodiment of the invention, as can be seen in

FIG. 4

, the general arrangement of the furnace


20


is as previously described. The furnace


20


has the main blower


22


housed in an inlet plenum


107


where the main blower


22


draws temperature controlled air


24


from the exterior environment such as from the cold air return ducts in a house, and pressurizes the temperature controlled air


24


to flow over a heat exchanger


26


where the temperature controlled


24


air is heated and directed into the supply ducts for the house. The furnace


20


also has an inducer fan


108


that draws the combustion air


28


into the vestibule


62


of the furnace


20


. After entering the vestibule


62


, the combustion air


28


enters the combustion chamber


34


, flows through the burners


35


, flows through the heat exchanger


26


to heat the temperature controlled air


24


, and flows out of the furnace


20


through the exhaust pipe


36


.




As stated previously, the inducer fan


108


has a fan housing


110


and an impeller


112


rotatably disposed within the fan housing


110


for drawing or inducing a flow of the combustion air


28


into the combustion chamber


34


. The impeller


112


is operably driven by an inducer fan motor


114


mounted on the inducer fan housing


110


. The motor


114


has a motor housing


116


that defines a hollow interior


117


of the motor housing that surrounds the motor


114


. The motor


114


and motor housing


116


are preferably positioned in the vestibule


62


with the inducer fan


108


. In the embodiment of the invention shown in

FIG. 4

, the motor housing


116


is separated from the inducer fan housing


110


such that the combustion air


24


that flows through the inducer fan housing


110


does not enter the motor housing


116


. In contrast to the embodiments of the invention previously shown, in

FIG. 4

, the cooling air


118


for the inducer fan motor


114


is supplied by the operation of the main blower


22


.




The inducer fan motor housing


116


is provided with an inlet opening


120


and an outlet opening


122


that communicate with the motor housing interior


117


. The motor housing outlet


122


includes a plurality of holes


126


circumferentialy spaced about a cylindrical exterior surface


128


of the inducer fan motor housing


116


. An annular manifold


130


extends around the cylindrical exterior surface


128


of the motor housing


116


and around the circumferentialy spaced holes


126


. Preferably, an outlet pipe


132


extends between the manifold


130


surrounding the motor housing outlet


122


and the inlet plenum


107


. The motor housing inlet


120


is formed as a plurality of holes


134


through an axial end


136


of the motor housing


116


. The motor housing inlet


120


may also be formed in a similar fashion to the outlet


122


with a plurality of holes


134


circumferentialy spaced about the motor housing exterior surface


128


and an inlet manifold extending over the inlet holes


134


. The motor housing inlet


120


is provided with an inlet pipe


138


extending from the inlet


120


to a cooling air source


140


. As shown in

FIG. 4

, the inlet pipe


138


is directed from the inlet


120


to the external environment outside the furnace


20


and the furnace vestibule


62


so that the cooling air flow


118


does not interfere with the operation of the inducer fan


108


and its circulation of combustion gases


28


through the vestibule


62


. The inlet


120


and outlet


122


are arranged on axially opposite sides of the motor housing


116


and at a distance apart so that the cooling air


118


may be drawn axially across the motor


114


to cool bearings and other motor components located within the motor housing interior


117


.




In operation, the main blower


22


draws temperature controlled air into the inlet plenum


107


. From the inlet plenum


107


, the temperature controlled air


24


is pressurized by the main blower


22


and directed over the heat exchanger


26


where it is heated and returned to the external environment. When the main blower


22


is energized, the suction forces created by the main blower


22


draw cooling air


108


from the cooling air source


140


(the furnace external environment) into the inlet pipe


138


, through the motor housing inlet


120


, and into the motor housing interior


117


. Inside the motor housing interior


117


, the cooling air flows over the motor components to the outlet


122


cooling the motor


114


and its components. The suction forces created by the main blower


22


draw the cooling air


118


from the outlet


122


into the outlet pipe


132


where the cooling air


118


is directed to the inlet plenum


107


and the suction of the main blower


22


. The motor housing


116


, the manifold


130


, the outlet pipe


132


and the inlet pipe


138


are sealed together to avoid any combustion exhaust of the furnace being drawn into the main blower


22


. In this arrangement, the cooling air


118


that was drawn over the motor


114


is mixed with the temperature controlled air


24


in the inlet plenum


107


before the mixture is directed to flow over the heat exchanger


36


. Thus, a portion of the temperature controlled air


24


that is circulated through the furnace


20


includes the cooling air


118


drawn through the motor housing interior


117


.




While the present invention has been described by reference to specific embodiments, it should be understood that modifications and variations of the invention may be constructed without departing from the scope of the invention as defined by the following claims.



Claims
  • 1. A furnace comprising:an inducer fan for circulating combustion gases through the furnace; an inducer motor in an inducer motor housing, the inducer motor driving the inducer fan; a blower fan for circulating temperature controlled air through the furnace; and an inlet plenum of the furnace containing the blower fan, the inlet plenum communicating with the inducer motor housing whereby operation of the blower fan draws cooling air into the inducer motor housing to cool the inducer motor.
  • 2. The furnace of claim 1, wherein:the inducer motor housing is in direct communication with the inlet plenum whereby cooling air drawn over the motor is directed to and mixed in the inlet plenum with the temperature controlled air and circulated through the furnace by the main blower fan.
  • 3. The furnace of claim 1, wherein:the inducer motor housing defines a hollow interior around the motor, the motor housing has at least one inlet hole and at least one outlet hole through to the hollow interior, and the outlet hole is in communication with the furnace inlet plenum.
  • 4. The furnace of claim 3, wherein:an inlet pipe is connected to the inducer motor housing at the inlet hole and an outlet pipe is connected to the inducer motor housing at the outlet hole, the inlet pipe directs cooling air into the interior of the inducer motor housing and the outlet pipe directs cooling air from the interior of the inducer motor housing to the inlet plenum.
  • 5. The furnace of claim 4, wherein:the inlet pipe draws the cooling air from outside the furnace.
  • 6. The furnace of claim 5, wherein:the inducer fan and inducer motor are housed in a vestibule that is partitioned from the inlet plenum of the furnace and the inlet pipe draws cooling air from outside the vestibule.
  • 7. The furnace of claim 4, wherein:the inducer motor housing is spaced from the blower fan by the outlet pipe.
  • 8. A furnace comprising:an inducer fan for circulating combustion gases through the furnace; an inducer motor in an inducer motor housing having a hollow interior surrounding the inducer motor; and a blower fan of the furnace housed in an inlet plenum of the furnace, the inlet plenum being in communication with the interior of the inducer motor housing, the blower fan drawing cooling air into the interior of the inducer motor housing when the blower fan is operated.
  • 9. The furnace of claim 8, wherein:the blower fan circulates temperature controlled air through the furnace and a portion of the temperature controlled air is cooling air drawn through the interior of the inducer motor housing.
  • 10. The furnace of claim 9, wherein:the inducer motor housing is in direct communication with the inlet plenum whereby temperature controlled air and cooling air are mixed in the inlet plenum.
  • 11. The furnace of claim 8, wherein;the inducer motor housing has inlet and outlet holes that communicate with the interior of the inducer motor housing, the outlet hole is in communication with the inlet plenum whereby operation of the blower fan draws cooling air through the inlet hole into the interior of the inducer motor housing and out of the outlet hole into the inlet plenum.
  • 12. The furnace of claim 11, wherein:the inducer motor housing has an inlet pipe connected at the inlet hole and an outlet pipe connected at the outlet hole, the outlet pipe extends between the inducer motor housing and the inlet plenum such that operation of the blower fan draws the cooling air through the inlet pipe, then through the inducer motor housing interior and then through the outlet pipe into the inlet plenum.
  • 13. The furnace of claim 12, wherein:the inducer motor housing is housed in a vestibule of the furnace that is partitioned from the inlet plenum and the inlet pipe extends from outside the furnace vestibule to the inlet hole of the inducer motor housing.
  • 14. The furnace of claim 8, wherein:the furnace is a high-efficiency furnace.
  • 15. A method of cooling an inducer fan motor in a furnace, wherein the furnace has a main blower fan housed in an inlet plenum that circulates temperature controlled air through the furnace and an inducer fan that circulates combustion gases through the furnace, the inducer fan is driven by the inducer fan motor, the inducer fan motor has a motor housing defining a hollow interior that surrounds the inducer fan motor, the method of cooling the inducer fan motor comprising the steps of:providing the motor housing with an inlet and an outlet into the hollow interior of the motor housing; communicating the outlet with the inlet plenum; communicating the inlet with a cooling air source; and operating the main blower fan so as to draw cooling air from the cooling air source into the inlet, then through the hollow interior of the motor housing and then through the outlet into the inlet plenum.
  • 16. The method of claim 15, wherein:operating the main blower fan to draw cooling air into the inlet, then through the hollow interior of the motor housing and then through the outlet into the inlet plenum mixes the cooling air with the temperature controlled air in the furnace inlet plenum.
  • 17. The method of claim 16, wherein:mixing the cooling air with temperature controlled air heats the temperature controlled air before the temperature controlled air passes through the furnace.
  • 18. The method of claim 15, wherein;communicating the outlet with the inlet plenum includes connecting an outlet pipe to extend between the motor housing outlet and the inlet plenum.
  • 19. The method of claim 15, wherein;communicating the outlet with the inlet plenum includes providing at least one hole through the motor housing that communicates with the inlet plenum.
  • 20. The method of claim 15, wherein:communicating the inlet with the cooling air source includes connecting an inlet pipe to extend between the motor housing inlet and an exterior environment of the furnace.
RELATED U.S. APPLICATION DATA

This application is a continuation-in-part of application Ser. No. 09/631,925, filed Aug. 3, 2000.

US Referenced Citations (15)
Number Name Date Kind
4626720 Fukasaku et al. Dec 1986 A
4651711 Velie Mar 1987 A
4848313 Velie Jul 1989 A
4906182 Moller Mar 1990 A
5201024 Steffes Apr 1993 A
5313930 Kujawa et al. May 1994 A
5341795 Chou et al. Aug 1994 A
5347980 Shellenberger Sep 1994 A
5368010 Weber, III et al. Nov 1994 A
5477846 Cameron Dec 1995 A
5775318 Haydock et al. Jul 1998 A
5834869 Morgan et al. Nov 1998 A
6021775 Dempsey et al. Feb 2000 A
6216685 Payne Apr 2001 B1
6231311 Gatley et al. May 2001 B1
Continuation in Parts (1)
Number Date Country
Parent 09/631925 Aug 2000 US
Child 09/705172 US