Gas separation: processes – Deflecting – And filtering
Reexamination Certificate
2001-03-19
2002-12-03
Hopkins, Robert A. (Department: 1724)
Gas separation: processes
Deflecting
And filtering
C095S287000, C055S337000, C055S379000, C055S414000, C055S429000, C055S472000, C055S486000, C055S492000, C055S521000, C055SDIG003, C015S353000
Reexamination Certificate
active
06488744
ABSTRACT:
The present invention relates to the art of air filter systems and, more particularly, to an improved vacuum cleaner employing a novel filter system. The invention is particularly applicable for a canister type vacuum cleaner and it will be described with particular reference thereto; however, the invention has much broader applications and may be used to filter air by employing the novel filter system and filtering method as contemplated by the present invention.
INCORPORATION BY REFERENCE
U.S. Pat. Nos. 5,248,323; 5,515,573; 5,593,479; 5,603,741; 5,641,343; 5,651,811; 5,658,362; 5,837,020; 6,090,184; and Des. 432,746 are incorporated herein as background information regarding the type of cleaning systems to which the present invention is particularly applicable, and to preclude the necessity of repeating structural details relating to such cleaning systems. Several of these patents illustrate a canister type vacuum cleaner with a low velocity receptacle or chamber into which is placed a conical filter sheet formed from non-woven cellulose fiber placed over a downwardly extending support structure for the purpose of removing particulate material from the air flowing through the vacuum cleaner. The rigid perforated conical support structure or member holds the filter sheet in its conical configuration. The support member and filter sheet are mounted together with the layer covering the rigid support member. Within the conical support member there is provided a generally flat disc shaped cellulose filter sheet for further removal of particulate solids as the solids pass with the air from the canister through the conical filter sheet and through the disc to the outlet or exhaust of the vacuum cleaner.
BACKGROUND OF THE INVENTION
As more people populate urban environments, there is an increasing need to provide a clean air environment at home and in the work place. In urban areas, where pollution levels sometimes exceed maximum values set by the EPA, the need for a clean air environment becomes even more apparent. In view of the posed hazards these polluted environments create, the public has demanded a means for removing pollutants from the environment to provide a healthy environment for both living and working. Furthermore, many particles in the air can act as irritants and/or increase or aggravate a person's allergies. Airborne pollutants can also contribute to respiratory infections and illnesses which can be hazardous to individuals with respiratory problems. Particles in the air can also create problems such as burning eyes, nose and throat irritation; cause or contribute to headaches and dizziness, and/or cause and/or contribute to coughing and sneezing. Furthermore, these particles can include various types of spores, dust mites, micro-organisms, such as bacteria and/or viruses, and/or other types of harmful particles which may cause serious illness or infection to a person.
In an effort to reduce the number of particles from the air and/or other environments, many homes, offices, and buildings have incorporated a central filtering system to remove particles entrained in the air. Unfortunately, these systems are very expensive and/or do not remove many of the small particles which can be the most hazardous and irritable to persons, such as spores, micro-organisms, such as bacteria and/or viruses, dust mites and some harmful chemicals. Typically, these filtering systems only remove about 300,000 particles out of about 20 million particles which flow into the filter medium. The small particles, which make up a majority of the particles in the air, freely pass through these conventional filter systems and are recirculated through the home and/or office.
In an effort to remove particles from a home and/or office environment, and reduce the amount of particles recirculated during the vacuuming of the home and/or office, two design strategies have been developed by Assignee, one relating to the design of the vacuum cleaner and the second relating to the design of the filters. Assignee has found that canister type vacuum cleaners provide superior cleaning efficiencies as compared with upright vacuum cleaners. One particular canister type vacuum cleaner is illustrated in U.S. Pat. No. 5,248,323, which is incorporated herein by reference. The canister type vacuum cleaner includes a reduced or low velocity chamber with a high velocity air inlet. Air is drawn into the low velocity chamber by an electric motor which drives a rotary fan. The rotary fan creates a vacuum in the low velocity chamber to draw air laden with particulate material through the chamber and to blow the filtered air through an outlet in the motor housing as exhausted clean air. Canister type vacuum cleaners normally include a cylindrical or a conical cellulose filter extending downwardly into the canister or low velocity chamber. The filter is typically formed of a porous mat to remove dirt and debris carried by the air drawing into the low velocity chamber. The high velocity air drawn into the chamber has entrained large solid particles. The large particles which are brought into the low velocity chamber are swirled or vortexed in a centrifuge configuration with convolutions so that the large particles are extracted by the vortexed or cyclonic action of the air in the canister. Thereafter, the air is pulled through the filter toward an upper motor that drives a fan which creates a vacuum in the canister or low velocity chamber. The fan then expels the filtered air outwardly through an exhaust passage, or passages, above the canister. A filter, such as a thin filter disc, is provided between the conical filter and the fan to prevent large particulate material that is inadvertently passed through the cylindrical or conical filter from contacting the fan. The '323 patent discloses the use of an activated charcoal containing filter to efficiently remove gaseous impurities in the air, such as paint fumes and other odor creating gases.
The canister type vacuum cleaner, as so far described, though exhibiting improved cleaning efficiencies as compared with upright vacuum cleaners, only removes relatively large particles entrained in the air. Many of the air particles of a size less than 10 microns pass freely through the filter medium and are recirculated in the room. These small particles can act as irritants to an individual and the recirculation of such particles can increase such irritation to an individual. High density filters can be used to filter out these very small particles in the air; however, high density filters cause large pressure drops through the filter and thus cannot be cost effectively used in standard vacuum cleaners.
The filter system disclosed in U.S. Pat. Nos. 5,593,479 and 5,651,811 addresses the problem of filtering small particles by disclosing a multi-layer filter which includes at least one layer of electrically charged fiber material encapsulated between at least two layers of support material. The multi-layer filter effectively removes small particles from the air which penetrate the cellulose fiber layer. The multi-layer filter is a specialized filter developed to remove many of the small particles in the air. Such filters are known as HEPA filters, High Efficiency Particle Air Filters, which, by government standards, are filters with a minimum efficiency of 99.97%. The industry defines HEPA filters as those which are efficient in removing 99.97% of the airborne particles having the size of 0.3 micron or larger. HEPA filters are commonly used in ultra clean environments such as in a laboratory, in electronic and biologically clean rooms, in hospitals, and the like. HEPA filters have recently been incorporated in air filters for business and individual use. The '479 and '811 patents disclose that an activated charcoal filter can also be used to remove odors from the air.
The multiple filter system disclosed in the '479 and '811 patents was further improved by the filter system disclosed in U.S. Pat. No. 6,090,184. The filter system disclosed in the '18
Fay Sharpe Fagan Minnich & McKee
HMI Industries Inc.
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