Gas separation: apparatus – Electric field separation apparatus – With control means responsive to sensed condition
Reexamination Certificate
1998-10-02
2001-06-12
Chiesa, Richard L. (Department: 1724)
Gas separation: apparatus
Electric field separation apparatus
With control means responsive to sensed condition
C095S002000, C095S004000, C095S078000, C096S019000, C096S056000, C096S060000, C096S080000
Reexamination Certificate
active
06245131
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electrostatic air cleaners.
BACKGROUND OF THE INVENTION
Electrostatic air cleaners are widely used in air circulating systems, such as heating, ventilating, and air conditioning systems, to remove dust and other contaminants from the air circulating through the system. Electrostatic air cleaners employ a highly charged grid that applies an electrical charge to the dust and contaminants passing through it, and oppositely charged collectors to attract the charged dust and contaminant particles. While these systems are very beneficial and effective, they can be difficult to install, and more particularly difficult to retrofit in existing air circulating systems. This difficulty is at least in part due to the fact that if the electrostatic air cleaner operates when the air is not circulating in the air circulating system, the electrostatic air cleaner generates ozone. Thus the electrostatic air cleaner must generally be wired into air circulating system to prevent this undesirable result, and thus installation of electrostatic air cleaners is complicated and time-consuming, and often requires professionals. Previous attempts have been made to provide an electrostatic air cleaner that can sense air flow, see, for example Baysinger, U.S. Pat. No. 3,989,486, incorporated herein by reference. However, these systems generally relied upon diaphragm operated electromechanical or electronic switches or thermistors for measuring pressure differentials between the air circulating system and the ambient environment.
In modern high efficiency sealed systems, the pressure differential between the system and the ambient is unknown, and thus is it difficult to implement such a system. In installations in garages and attics natural convective currents may “fool” these prior systems into activating the electronic air cleaning system, even though the system blower is off.
One attempt to overcome these difficulties is the use of a sail switch, which detects air flow within the system, but these switches are typically very large and thus cannot be incorporated into a self-contained electrostatic air cleaning system, and must be mounted remotely.
Moreover, it is difficult to mount conventional electrostatic air cleaners in the small enclosures provided in some new construction. Some electrostatic cleaners have cover mounts that require clearance around the covers which prevent mounting the cleaners in tight spaces. Other electrostatic air cleaners have covers with components that protrude beyond the profile of the frame opening, also preventing the cleaner from being mounted in tight spaces. This problem was exacerbated by the fact that in conventional electrostatic air cleaners, the cover could typically only be mounted in one orientation, limiting how the electrostatic air cleaner could be incorporated into the air circulating system.
SUMMARY OF THE INVENTION
The present invention relates to an improved electrostatic air cleaner which is of simple construction, and which does not need to be wired into the air circulating system, so it is easy to install, even in retrofit situations. Generally, the electrostatic air cleaner comprises a flow sensor for sensing the pressure differential across the electrostatic air cleaner by sensing the flow of air through a bypass tube. The electrostatic air cleaner also includes a switch, responsive to the flow sensor, for operating the electrostatic air cleaner only when the flow of air exceeds a predetermined threshold, corresponding to a desired pressure differential across the electrostatic air cleaner. Thus the electrostatic air cleaner operates only when air is flowing in the air circulating system, yet it does not have to be wired into the fan control of the air circulating system.
In the preferred embodiment, an electrostatic air cleaner cover unit is adapted to be secured over the opening in a frame in an air circulating system for mounting a removable air filter, and at least one removable electrostatic air cleaning cell. The cover unit has a baffle for substantially blocking the air flow between the air filter and the cover unit. The baffle has an opening therein, and a tube aligned with the opening in the baffle. An air flow sensor is disposed in the tube for sensing the air flow through the tube. A switch, responsive to the air flow sensor, conducts power to the at least one electrostatic air cleaning cell when the sensed air flow exceeds a predetermined threshold, thus insuring that the electrostatic air cleaner is operated only when there is air flowing in the air circulating system, and more preferably when the air flow corresponds to the air circulating system blower being on.
The cover unit has first and second sides, and preferably has two baffles, one baffle positioned to engage the filter when the first side of the cover unit is oriented upstream, and the other baffle positioned to engage the filter when the second side of the cover unit is oriented upstream. Each baffle has an opening therein, and the tube is aligned with the opening in each baffle, so that regardless of which way the cover unit is installed over the opening, the air flow between the filter and the cover unit is directed through the tube, and sensed by the air flow sensor.
The cover unit has its own conventional power connection, and a contact disk for providing electric power to the at least one electrostatic cell. Thus, no special power connections need to be made to electrostatic air cleaner, further facilitating installation. The cover unit is designed so that it does not have an “up” side or a “down” side, so that it can be placed over the opening the cabinet in any convenient orientation. The cover is sized to the profile of the opening in the frame, and is designed to pull straight back from the cabinet, reducing the amount of clearance required, and thus allowing an electrostatic air cleaner to be installed in air circulating systems where they previously would not fit. The ability of the cover to be used in either orientation also makes it less prone to end-user mistakes.
These and other features and advantages will be in part apparent and in part pointed out hereinafter.
REFERENCES:
patent: 2932966 (1960-04-01), Grindell
patent: 3989486 (1976-11-01), Baysinger
patent: 4290788 (1981-09-01), Pittman et al.
patent: 4376637 (1983-03-01), Yang
patent: 4562522 (1985-12-01), Adams et al.
patent: 4654772 (1987-03-01), Thorne
patent: 5071455 (1991-12-01), Abedi-Asi
patent: 5124905 (1992-06-01), Kniepkamp
patent: 5454859 (1995-10-01), Chiba et al.
patent: 5688308 (1997-11-01), Voigts
patent: 52-50969 (1977-04-01), None
patent: 54-2266 (1979-01-01), None
White-Rodgers Division Emerson Electric Co. Electro-Air, The Electro-Air Electronic Air Cleaner Compartment (brochure), Undated.
White-Rodgers Division Emerson Electric Co. Mountain-Air, Electronic Air Cleaner (brochure), 1978.
McElroy Jerry W.
Rippelmeyer Dennis M.
Chiesa Richard L.
Emerson Electric Co.
Harness Dickey & Pierce
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