Ventilation – Having inlet airway – Including specific air distributor
Reexamination Certificate
2000-10-04
2001-11-27
Lu, Jiping (Department: 3749)
Ventilation
Having inlet airway
Including specific air distributor
C454S258000, C417S423150, C417S032000, C415S213100, C415S214100, C416S246000
Reexamination Certificate
active
06322443
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to electromechanical apparatus for improving air flow through a duct system such as is commonly present in a home heating and air conditioning system.
Most homes that have forced air heating and air conditioning systems include only a single heating unit or furnace that commonly includes a plenum containing a heat exchanger and a refrigeration coil connected to an air conditioning unit. A single fan, operating in response to a single centrally placed thermostat, forces air to flow through a duct system that includes the furnace plenum. The duct system distributes the thermally treated air to various rooms of the home that are typically located at varying distances from the furnace. The length of duct work between the furnace and any given room of the home typically varies considerably, which causes the cooling and heating to occur preferentially in certain portions of the home.
It is known that enhanced uniformity in cooling and heating of a home can be achieved by equipping the home with multiple forced air heating and air conditioning units each of which is controlled by a thermostat located within a particular zone of the home. While such zone controlled systems operate very satisfactorily, they are generally substantially more expensive and cannot be economically justified in many circumstances.
It is also known to enhance the distribution of air through one duct of a duct system with the aid of a booster fan located in the duct work, often near or at a register end of the duct. Typically such fans are wired in conjunction with the furnace fan so that they are controlled by the same thermostat, and turn on and off with the furnace fan. It is also known, for example from U.S. Pat. No. 5,860,858, to control the operation of such a duct fan based on sensed air pressure within the duct. It is also known, for example from U.S. Pat. Nos. 4,576,331 and 5,632,677 to simply supply the fan with power on a continuous basis, and to control the supply of power to the fan with a thermostat located in the vicinity of the register.
The mechanical installation of such booster fans has typically been accomplished by inserting a special segment of ducting containing the booster fan as shown, for example, in U.S. Pat. No. 5,860,858. Such an installation typically requires tools to cut an existing segment from the duct work followed by sealing the new special segment in place within the duct work, often in very uncomfortable circumstances, such as in a crawl space under a home. To avoid such complex installation, both U.S. Pat. Nos. 4,576,331 and 5,632,677 disclose the alternative of simply replacing the existing register with a special register containing the booster fan. Unfortunately the known embodiments of such special registers have an unsightly appearance and are therefore undesirable.
What is needed is a booster fan mechanism that is easily installed without any special tools, yet is substantially invisible once it is installed.
SUMMARY OF THE INVENTION
A booster fan of the present invention is designed for use in a forced air heating and air conditioning system, where the system includes a duct having distal end and a register situated at a distal end of the duct leading to a room to which an enhanced flow of thermally treated air is desired. The booster fan assembly includes a fan, an electric motor coupled to the fan, an electric cord coupled to the motor and adapted to be coupled to a source of electric power, and a support coupled to the motor and adapted to be inserted in the duct from the distal end. The support has a flexible perimeter portion for contacting the interior surface of the duct and a central portion extending inward from the perimeter portion that is coupled to the motor. An outer surface of the support is selectively engageable with an interior surface of said duct at a selected location near said distal end. The support can take the form of an incomplete ring that is collapsible from a first diameter to a second smaller diameter to permit insertion of the assembly into the duct from the distal end. The support can also include two inwardly directed handle portions normally spaced from each other, the handle portions being compressible toward each other to cause contraction of the perimeter portion. Preferably, the support includes an outer surface formed of a conformable material for elastically gripping the interior surface of the duct and inhibiting any fan noise.
The booster fan assembly of the present invention should preferably be selected to have a fan diameter that is at least 70% of the diameter of the duct in which the assembly is to be inserted. The assembly also should include at least one sensor connected to the electric cord and responsive to a condition of the air in the vicinity of the fan to control the flow of electric power from the source to the motor. The sensor preferably takes the form of a pair of sensors arranged in parallel to each other, a first of the pair of sensors being responsive to air below a first selected temperature to cause power to be conducted from the source to the motor in the presence of cooled air in the duct, and a second of the pair of sensors being responsive to air above a second selected temperature to cause power to be conducted from the source to the motor in the presence of heated air in the duct. To ensure safe operation of the booster fan, the assembly also preferably includes a transformer coupled to the plug end of the electric cord for transforming the conventional source voltage of 117 VAC to a safer lower voltage, of about 24 VAC, or less.
The booster fan assembly of the present invention is intended to be installed in the duct by removing the register from the distal end of the duct, and inserting the booster fan assembly into the duct while deflecting the flexible perimeter portion of the support toward the center of the duct. Once the assembly is positioned at the desired location in the duct, one allows the flexible perimeter portion to expand outwardly into contact with a inner surface of the duct. In using the illustrated embodiment of the present invention, the inward deflection and outward expansion of the support perimeter portion is controlled by grasping two inwardly directed handle portions connected to the flexible perimeter portion of the support, and moving the handle portions toward each other to cause contraction of the perimeter portion of the support while positioning the support at said selected position, the perimeter having sufficient spring-like memory to expand against the interior surface of the duct upon release of the handle portions. The electrical cord is then extended out from the distal end of the duct to a convenient electrical socket that can provide power to the booster fan assembly. The register is then replaced onto the distal end of the duct so that the booster fan assembly becomes substantially invisible.
This entire installation procedure can usually be achieved quickly and without the use of any tools or hardware. The support can be made in a variety of sizes to fit the variety of duct sizes conventionally employed in both home and commercial systems. The low voltage motor and wiring makes concealment of the installation easy and safe. The dual thermostat control ensures that the fan will automatically come on when there is warmed air or cooled air in the duct. These and other features and advantages of the present invention will become apparent from a consideration of the following description of the preferred embodiment that references the accompanying drawings.
REFERENCES:
patent: 4576331 (1986-03-01), Harwell
patent: 4722266 (1988-02-01), Deckert
patent: 4754697 (1988-07-01), Asselbergs
patent: 4809593 (1989-03-01), Asselbergs
patent: 4846399 (1989-07-01), Asselbergs
patent: 5364026 (1994-11-01), Kundert
patent: 5489238 (1996-02-01), Asselbergs
patent: 5492456 (1996-02-01), Knight et al.
patent: 5607354 (1997-03-01), Mill et al.
patent: 5632677 (1997-05-01), Elkins
patent: 5860858 (1999-01-01), Wett
Brinks Hofer Gilson & Lione
Lu Jiping
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