Gas separation: processes – Electric or electrostatic field – Including baffling – deflection – or restriction of gas flow
Reexamination Certificate
1999-01-20
2001-05-08
Chiesa, Richard L. (Department: 1724)
Gas separation: processes
Electric or electrostatic field
Including baffling, deflection, or restriction of gas flow
C055SDIG003, C096S062000, C096S066000, C096S097000, C361S233000, C417S049000
Reexamination Certificate
active
06228149
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for moving, filtering and ionizing air. More particularly, the present invention relates to a fan assembly having a tubular housing and electrodes which ionize air and cause the air to be filtered and to move through the tubular housing without use of moving parts, such as an impeller, thereby providing air filtration and ventilation without generation of vibrations and acoustic disturbances.
2. Description of the Related Art
Conventional fans, ventilation systems and air filtration systems presently used in industrial, commercial and residential applications typically employ an impeller or the like to generate an air flow. The rotary movement of the impeller in such systems causes acoustic disturbances and vibrations, the noise level of which may be excessive for a particular application. For example, it may be desirable to generate a virtually noiseless air flow for industrial applications such as cooling of personnel or equipment, exhausting and/or filtering of air, drying processes, and clean room applications. Noiseless air filtration may also be desirable in residential ventilation and filtration systems. Conventional impeller-based devices are incapable of providing air movement without generating significant noise. Accordingly, there is a need for a system capable of providing noisefree air flow and/or air filtration.
Electric fields have been used in a variety of technologies to ionize molecules or to generate a stream of electrons. For example, electrostatic precipitators conventionally use an electrostatic charge to remove particles from an air stream by attracting electrostatically charged particles to an oppositely charged collector. The system disclosed in U.S. Pat. No. 4,518,401 to Pontius et al. is representative of such systems. Specifically, Pontius et al. disclose an electrostatic precipitator comprising a plurality of positively-charged, longitudinally-extending vertical plates and a plurality of negatively-charged, vertically-extending rods interspaced between the plates. As air flows through the precipitator, the electric field formed between the rods and plates causes a corona discharge from the rods which negatively charges particles in the air, which are then drawn to the positively-charged plates and removed from the air. The plates are mechanically rapped periodically, causing the particles to fall into collection hoppers.
Other patents disclosing electrostatic precipitators include: U.S. Pat. No. 2,593,869 to Fruth; U.S. Pat. No.2,756,838 to Roberts; U.S. Pat. No.2,778,443 to Yereance; U.S. Pat. No. 3,798,879 to Schmidt-Burbach et al.; U.S. Pat. No. 3,910,778 to Shahgholi et al.; U.S. Pat. No. 5,199,257 to Colletta et al.; U.K. Patent No. 2,229,117 to Colletta; German Patent No. 4410213 to Kogleschatz; and German Patent No. 4400827 to Pechmann. In each of these systems, the air flow through the precipitator is generated by conventional means, and the electric field within the precipitator is generally perpendicular to the direction of flow; consequently, the ionizing action of the precipitator and the shape and orientation of the electric field are not suitable for causing or increasing air flow.
Electric fields have been used in conjunction with magnetic fields in ion pumps to form a vacuum by ionizing air molecules and causing the ions to colloid with and be buried within a cathode material. For example, U.S. Pat. No. 4,631,002 to Pierini discloses an ion pump comprising hollow anode elements formed between two cathode plates disposed between opposite poles of a magnet. Other patents disclosing ion pumps include U.S. Pat. No. 4,687,417 to Amboss and U.S. Pat. No. 3,452,923 to Lamont. While such pumps ionize air molecules, they are designed to trap such molecules and thus cannot generate an air flow.
Electric fields have also been used in electron beam generators and accelerators to accelerate electrons. For example, U.S. Pat. No. 5,463,268 to Schroeder discloses an electron accelerator which employs a negatively-charged electrode within an acceleration tube and conductive rings to accelerate electrons to a high velocity. U.S. Pat. No. 3,431,455 to Beyer discloses an electron imaging device which directs a beam of electrons onto a surface to form a charge pattern. Such devices typically operate in a vacuum and are not suitable for ionizing and accelerating air molecules or generating an air flow.
While the above patents establish that electric fields have been used to ionize air molecules and particles and to accelerate electrons, electric fields have not been exploited in the generation of an air flow, such as that produced by conventional impeller fans. In particular, it has not been demonstrated that a significant volume of air can be moved through a chamber from an air inlet to an air outlet by applying an electrostatic field to the air within the chamber. Further, conventional electrostatic precipitators used in ventilation systems do not enhance or increase air flow. Thus, fans that employ an electric field as a means of moving air are unknown.
SUMMARY OF THE INVENTION
It is an object of the present invention to produce an air flow using a fan assembly having no moving parts.
It is another object of the present invention to produce an air flow by applying an asymmetric electric field to a volume of air.
It is a further object of the present invention to provide a fan assembly that is virtually noiseless and free of vibrations while producing an air flow.
Another object of the present invention is to filter particles from an air stream flowing through a fan assembly.
Yet another object of the present invention is to ionize air molecules flowing through a fan assembly.
A further object of the present invention is to move air in a highly energy efficient manner.
The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
According to the present invention, air is moved, ionized and filtered by means of an electric field within a fan assembly having no moving parts. The system includes a tubular housing which draws air in through a flared inlet end and exhausts filtered air through an outlet end. Within the housing is a needle electrode which extends longitudinally. A net electrode is disposed within the housing on the outlet side of the needle electrode and extends in a transverse direction. The net electrode can be planar or curved to present a concave surface to the needle electrode. An electric potential on the order of tens of thousands of volts is applied between the needle and net electrodes to form an electric field therebetween. The combination of the longitudinally oriented needle electrode and the transversely oriented net electrode and their relative arrangement creates an electric field that is asymmetric in the longitudinal direction and that tends to ionize and accelerate air molecules toward the net electrode, carrying the air molecules past the net electrode and through the air outlet.
The voltage applied across the electrodes is a function of the space between the electrodes and is sufficient to produce a corona effect which ionizes air molecules in the field without causing discharge in the air or arcing between the electrodes. The spacing between the electrodes must be small enough to form an electric field of sufficient strength to ionize air molecules in a concentration sufficient to produce a significant air flow. However, the distance between the electrodes must be large enough that the ions generated are predominantly negative (in the case where the net electrode is positively charged), such that a large majority of the ions will be attracted to and accelerate toward the net electrode.
The overall length of the housing, the distance between the inlet end and the electrodes, and the distance between the electrodes are generally propor
Alenichev Alexey
Karadgy Viacheslav G.
Tkachenko Viktor
Chiesa Richard L.
Patterson Technique, Inc.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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