Stoves and furnaces – Hot-air furnaces – Compressed air
Reexamination Certificate
2000-08-03
2001-11-20
Yeung, James C. (Department: 3743)
Stoves and furnaces
Hot-air furnaces
Compressed air
C126S09900D, C126S312000, C415S078000, C415S189000
Reexamination Certificate
active
06318358
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates generally to a draft inducing blower in a furnace, and, more particularly, the invention pertains to an improvement in the blower design that provides internal cooling for a motor that drives the blower.
(2) Description of the Related Art
Blowers to which the present invention is directed are common in the art. Generally, these blowers are located downstream of a combustion chamber or combustion tubes in the furnace, depending upon the style of furnace. The blower draws combustion air into the combustion chamber or combustion tubes, where the combustion air is mixed with fuel and ignited to generate heat for the furnace. The heated exhaust gases are then drawn through a heat exchanger by the blower and discharged from the blower to an exhaust pipe that vents to the outside atmosphere.
The blower generally includes a blower housing and a blower motor installed on the blower housing. The blower housing typically has a side wall, top piece, and bottom piece that define a volute for the blower housing. When the blower is energized, an impeller, operably connected to a shaft of the blower motor, rotates in the volute to draw exhaust gases through an intake hole in the center of the bottom piece and to compress gases in the volute. The impeller draws exhaust gases directly from the combustion chamber or combustion tubes into the blower housing. The pressurized exhaust gases are directed into a discharge exit that extends outward and away from the side wall of the blower housing. The discharge exit is coupled to an exhaust pipe that vents the exhaust gases to atmosphere. In this arrangement, the impeller rotates at a high rate of speed to generate sufficient air flow to draw combustion air into the combustion chamber and combustion tubes and to expel the exhaust gases into the exhaust pipe.
In a typical conventional furnace, the combustion air is drawn into a vestibule of the furnace before it is directed into the combustion chamber or combustion tubes. Generally, the blower motor and blower housing are located in the vestibule with the blower intake in communication with the combustion chamber or combustion tubes. Control electronics for the furnace are also generally located in the vestibule.
During operation of the furnace, temperatures in the vestibule increase and tend to degrade performance of furnace components located in the vestibule. The proximity of the vestibule to the combustion chamber or tubes and the heat generated by the blower motor as the motor runs elevate the temperature within the vestibule. The hot exhaust gases circulating through the blower also contribute to the elevated temperatures in the vestibule. The elevated temperature within the vestibule tends to shorten the life of the blower motor, and electronics and controls located within the vestibule. However, because the blower draws relatively cool air into the vestibule before combustion, the vestibule is generally the preferred place on the conventional furnace for positioning temperature sensitive equipment for the furnace. Additionally, to maintain proper operation of the blower motor during the period of elevated temperature in the vestibule, conventional blower motors utilize an auxiliary fan attached to the rotating shaft of the motor to dissipate the heat generated by the motor.
Although the auxiliary fan usually provides adequate heat removal for the motor, the auxiliary fan has many disadvantages. First, the use of an auxiliary fan on the blower motor increases the size and/or height of the motor assembly, thereby preventing the streamlining of the motor assembly and reduction of the space reserved for the blower in the furnace. Because the auxiliary fan is generally positioned outside of the motor casing, guards and other safety devices must be attached to the motor casing to prevent inadvertent contact with the rotating fan blades during operation. The guard and the fan itself also add cost to the blower motor. The blower motor with an auxiliary fan generates additional noise. Finally, because the motor is positioned in the vestibule, the auxiliary fan recirculates and reuses air in the vestibule. This recirculation and reuse of the air in the vestibule contributes to the elevated temperatures of the vestibule and the associated components positioned therein. Because the motor operates in the vestibule at higher temperatures, the motor must again be upscaled in design, which adds cost to the blower.
Therefore, it is an object of the present invention to provide an improved blower that overcomes the disadvantages of conventional blowers, while providing a blower that cools the blower motor without the use of an auxiliary fan attached to the blower motor.
SUMMARY OF THE INVENTION
The present invention overcomes shortcomings of prior art furnaces that use an auxiliary fan attached to the blower motor to cool the blower motor. The blower of the present invention provides cooling for the blower motor with the flow of air induced by the blower.
The blower of the present invention has an impeller that is configured to create a primary air flow of combustion air into the blower housing and a secondary air flow through the blower motor. The secondary air flow is drawn through a casing of the blower motor and into the blower housing where it is mixed with the exhaust gases and discharged from the blower housing. Preferably, the blower housing has an enlarged shaft hole that is sized to allow sufficient cooling air to pass through the motor casing and motor into the blower housing.
During furnace operation, the impeller of the blower draws air into the vestibule. A first portion of the air is used by the furnace for combustion, and a smaller, second portion of the air is used for cooling the blower motor and exhaust gases. The impeller draws the second portion directly over the motor into the exhaust stream. Because the second portion is not recirculated with air in the vestibule, it does not contribute to the elevated temperature in the vestibule. As the air in the vestibule has not been recycled by the blower motor, the air in the vestibule is turned over and replaced more rapidly making the vestibule cooler.
The blower of the present invention eliminates the need for an auxiliary fan and allows for the blower to be more compact and streamlined. The blower of the present invention has no external rotating equipment, and the safety concerns and costs incident with the auxiliary rotating fan are obviated. The blower motor of the present invention allows the use of a lower cost blower motor while reducing the noise associated with the blower. When installed in the furnace, the blower of the present invention provides a cooler vestibule and therefore cooler environment for the furnace electronic controls. The blower of the present invention also cools the exhaust stream from the furnace so as to lower overall operating temperatures of the furnace.
REFERENCES:
patent: 2654529 (1953-10-01), Smith
patent: 3274990 (1966-09-01), MacCracken
patent: 3730642 (1973-05-01), Barnstead
patent: 4236443 (1980-12-01), Schossow
patent: 4974579 (1990-12-01), Shellenberger et al.
patent: 5060720 (1991-10-01), Wollaber et al.
patent: 5309892 (1994-05-01), Lawlor
patent: 5350281 (1994-09-01), Hagshenas
patent: 5352099 (1994-10-01), Austine et al.
patent: 5375651 (1994-12-01), Colwell
patent: 5478275 (1995-12-01), Malm
patent: 5803707 (1998-09-01), Schips et al.
patent: 5814908 (1998-09-01), Muszynski
patent: 6231311 (2001-05-01), Gatley et al.
Howell & Haferkamp LC
Jackel Incorporated
Yeung James C.
LandOfFree
Furnace blower with double sided impeller does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Furnace blower with double sided impeller, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Furnace blower with double sided impeller will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2600591