Room air cleaner

Details Room air cleaner Room air cleaner

2002-01-11

2003-09-09

Smith, Duane (Department: 1724)

Gas separation

Deflector

Fixed gas whirler or rotator means

C055S471000, C055S473000, C096S384000

Reexamination Certificate

active

06616722

ABSTRACT:

The present invention relates to the art of air filter systems and more particularly to a high efficiency, low noise, portable room air cleaner. The invention is particularly applicable to a portable canister type air cleaner and will be described with particular reference thereto; however, the invention has much broader applications and may be used in vacuum cleaners and/or to filter air in other environments by employing the novel air filtering arrangement as contemplated in the present invention.
BACKGROUND OF THE INVENTION
As more and more people move to urban environments, there is an ever 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 of these particles in the air can act as irritants and/or increase or aggravate a person's allergies. Airborn pollutants can also contribute to respiratory infections and illnesses which can be hazardous to individuals with respiratory problems. Particles in the air can create problems such as burning eyes, nose and throat irritation, contributing to headaches and dizziness, which can result in coughing and sneezing. Furthermore, these particles can include various types of spores, dust mites, microorganisms, 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.
Specialized filters have been developed to remove many of the small particles in the air. Such filters are known as HEPA filters, which stands for 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 filters which are efficient in removing 99.97% the airborn particles the size of 0.3 micron or larger. Such filters are commonly used in ultra clean environments such as in a laboratory, in electronic and biologically clean rooms, in hospitals and the like. These filters have recently been incorporated in air filters for business and individual use.
In U.S. Pat. No. 4,629,482 a portable HEPA room air cleaner is disclosed. The air cleaner incorporates a cylindrical HEPA filter and the filter is mounted within the filter housing having an air discharge at its base. A centrifugal fan is incorporated in the housing to draw air through the filter and discharge air at the base of the housing. Due to the configuration of the air cleaner, it is necessary to space the base of the apparatus from the main housing. Such a configuration also requires that the apparatus be designed somewhat larger than some consumers may desire. The discharge of air at the base of the unit results in the recirculation of particles which have already settled on the floor. Such recirculation of settled particles can result in increased particle irritation. The air cleaner does not incorporate a gas filter to remove irritable or noxious gas from the air.
In U.S. Pat. No. 5,435,817, another type of portable HEPA room air cleaner is disclosed. This unit is cylindrical in shape and includes a base discharge. A centrifugal fan is used to draw air into the top of the unit and discharge filtered air at the base of the unit. The unit incorporates an outer deflector wall to radially discharge air at the bottom of the unit, such that the exhaust air is channeled generally circumferentially about the base of the unit. The discharged air at the base of the unit results in the redistribution of settled particles back into the air. The air cleaner is also absent any mechanism for removing unwanted gases in the air.
Assignee's U.S. Pat. No. 5,641,343 discloses an improved air cleaner design which discharges purified air near the top of the unit to reduce recirculation of settled particles. The air cleaner also incorporates an internal air flow design which reduces pressure drop through the air cleaner thereby improving the efficiencies of the air cleaner. The air filter further incorporates an improved filtering agent to remove more particles as compared to standard HEPA filters. The efficiencies of standard HEPA filters are all based upon 0.3 micron size particles. Historically, it was believed that particles about 0.3 micron in size were the most difficult to remove from the air. However, recent particle filtration testing has shown that particles the size of about 0.1 micron are the most difficult to remove from the air. Standard HEPA filters do not efficiently remove such small particles and allow such particles to freely pass through the filter medium. An analysis of these small particles has shown that the particles do not naturally fall out of the air, but instead remain entrained in the air by constantly bouncing off other particles in the air (i.e. Browning effect). These small particles have also been found to deviate from the air flow thus making such particles even more difficult to remove from the air. The improved particle filter used in U.S. Pat. No. 5,641,343 overcomes this particle filtration problem by incorporating a filter which can remove at least about 99.98% of particles about 0.1 micron in size. The filter system can also include a gas filter to remove unwanted gases from the filtered air.
Although Assignee's air filter disclosed in U.S. Pat. No. 5,641,343 greatly improves air purification technology, additional improvements in air purification efficiencies were still demanded. During the air purification process, the air intake section is preferably the largest surface area component of the air cleaner so as to maximize the size of the air filter and volume of air to be purified. However, when the air intake is enlarged, the air purification unit must be enlarged, since the reduction in size of the air exhaust will cause an increase in pressure drop and significant reductions in efficiencies. In order to overcome the increased pressure drop, larger motors must be used which are more costly, noisier and energy consuming. In addition to the noise caused by the increased motor size, the velocity of air through the smaller air exhaust region results in additional noise during operation. To address this problem, Assignee invented an improved air cleaner which is disclosed in U.S. Pat. No. 5,837,020. The air cleaner disclosed in U.S. Pat. No. 5,837,020 includes an air exhaust having a plurality of arcuate shaped vanes. The vanes all have the same shape and size and are symmetrically oriented about the air exhaust. The ends of each vane are spaced the same distance from the blower fan to effectively draw air from the blower fan. The drawn air is directed outwardly along the outwardly radiating arcuate vanes. The use of the arcuate vanes overcome the pressure drop problems associated with a smaller air exhaust region thereby allowing larger volumes of air to be expelled in a given surface area. As a result, the size of the air exhaust can be reduced, which in turn can reduce the size of the air cleaner. Furthermore, a larger motor does not need to be used for a smaller air exhaust, since compa

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