Gas separation: processes – Electric or electrostatic field – With cleaning of collector electrode
Reexamination Certificate
2001-08-08
2004-03-23
Chiesa, Richard L. (Department: 1724)
Gas separation: processes
Electric or electrostatic field
With cleaning of collector electrode
C096S029000, C096S039000, C096S040000, C096S051000, C096S096000
Reexamination Certificate
active
06709484
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to devices that produce ozone and an electrokinetic flow of air from which particulate matter has been substantially removed, and more particularly to cleaning the wire or wire-like electrodes present in such devices.
BACKGROUND OF THE INVENTION
The use of an electric motor to rotate a fan blade to create an air flow has long been known in the art. Unfortunately, such fans produce substantial noise, and can present a hazard to children who may be tempted to poke a finger or a pencil into the moving fan blade. Although such fans can produce substantial air flow, e.g., 1,000 ft
3
/minute or more, substantial electrical power is required to operate the motor, and essentially no conditioning of the flowing air occurs.
It is known to provide such fans with a HEPA-compliant filter element to remove particulate matter larger than perhaps 0.3 &mgr;m. Unfortunately, the resistance to air flow presented by the filter element may require doubling the electric motor size to maintain a desired level of airflow. Further, HEPA-compliant filter elements are expensive, and can represent a substantial portion of the sale price of a HEPA-compliant filter-fan unit. While such filter-fan units can condition the air by removing large particles, particulate matter small enough to pass through the filter element is not removed, including bacteria, for example.
It is also known in the art to produce an air flow using electro-kinetic techniques, by which electrical power is directly converted into a flow of air without mechanically moving components. One such system is described in U.S. Pat. No. 4,789,801 to Lee (1988), depicted herein in simplified form as
FIGS. 1A and 1B
. Lee's system
10
includes an array of small area (“minisectional”) electrodes
20
that is spaced-apart symmetrically from an array of larger area (“maxisectional”) electrodes
30
. The positive terminal of a pulse generator
40
that outputs a train of high voltage pulses (e.g., 0 to perhaps +5 KV) is coupled to the minisectional array, and the negative pulse generator terminal is coupled to the maxisectional array.
The high voltage pulses ionize the air between the arrays, and an air flow
50
from the minisectional array toward the maxisectional array results, without requiring any moving parts. Particulate matter
60
in the air is entrained within the airflow
50
and also moves towards the maxisectional electrodes
30
. Much of the particulate matter is electrostatically attracted to the surface of the maxisectional electrode array, where it remains, thus conditioning the flow of air exiting system
10
. Further, the high voltage field present between the electrode arrays can release ozone into the ambient environment, which appears to destroy or at least alter whatever is entrained in the airflow, including for example, bacteria.
In the embodiment of
FIG. 1A
, minisectional electrodes
20
are circular in cross-section, having a diameter of about 0.003″ (0.08 mm), whereas the maxisectional electrodes
30
are substantially larger in area and define a “teardrop” shape in cross-section. The ratio of cross-sectional radii of curvature between the maxisectional and minisectional electrodes is not explicitly stated, but from Lee's figures appears to exceed 10:1. As shown in
FIG. 1A
herein, the bulbous front surfaces of the maxisectional electrodes face the minisectional electrodes, and the somewhat sharp trailing edges face the exit direction of the air flow. The “sharpened” trailing edges on the maxisectional electrodes apparently promote good electrostatic attachment of particular matter entrained in the airflow. Lee does not disclose how the teardrop shaped maxisectional electrodes are fabricated, but presumably they are produced using a relatively expensive mold-casting or an extrusion process.
In another embodiment shown herein as
FIG. 1B
, Lee's maxisectional sectional electrodes
30
are symmetrical and elongated in cross-section. The elongated trailing edges on the maxisectional electrodes provide increased area upon which particulate matter entrained in the airflow can attach. Lee states that precipitation efficiency and desired reduction of anion release into the environment can result from including a passive third array of electrodes
70
. Understandably, increasing efficiency by adding a third array of electrodes will contribute to the cost of manufacturing and maintaining the resultant system.
While the electrostatic techniques disclosed by Lee are advantageous over conventional electric fan-filter units, Lee's maxisectional electrodes are relatively expensive to fabricate. Further, increased filter efficiency beyond what Lee's embodiments can produce would be advantageous, especially without including a third array of electrodes.
The invention in applicants' parent application provided a first and second electrode array configuration electro-kinetic air transporter-conditioner having improved efficiency over Lee-type systems, without requiring expensive production techniques to fabricate the electrodes. The condition also permitted user-selection of safe amounts of ozone to be generated.
The second array electrodes were intended to collect particulate matter, and to be user-removable from the transporter-conditioner for regular cleaning to remove such matter from the electrode surfaces. The user must take care, however, to ensure that if the second array electrodes were cleaned with water, that the electrodes are thoroughly dried before reinsertion into the transporter-conditioner unit. If the unit were turned on while moisture from newly cleaned electrodes was allowed to pool within the unit, and moisture wicking could result in high voltage arcing from the first to the second electrode arrays, with possible damage to the unit.
The wire or wire-like electrodes in the first electrode array are less robust than the second array electrodes. (The terms “wire” and “wire-like” shall be used interchangeably herein to mean an electrode either made from a wire or, if thicker or stiffer than a wire, having the appearance of a wire.) In embodiments in which the first array electrodes were user-removable from the transporter-conditioner unit, care was required during cleaning to prevent excessive force from simply snapping the wire electrodes. But eventually the first array electrodes can accumulate a deposited layer or coating of fine ash-like material.
If this deposit is allowed to accumulate eventually efficiency of the conditioner-transporter will be degraded. Further, for reasons not entirely understood, such deposits can produce an audible oscillation that can be annoying to persons near the conditioner-transporter.
Thus there is a need for a mechanism by a conditioner-transporter unit can be protected against moisture pooling in the unit as a result of user cleaning. Further there is a need for a mechanism by which the wire electrodes in the first electrode array of a conditioner-transporter can be periodically cleaned. Preferably such cleaning mechanism should be straightforward to implement, should not require removal of the first array electrodes from the conditioner-transporter, and should be operable by a user on a periodic basis.
The present invention provides such a method and apparatus.
SUMMARY OF THE PRESENT INVENTION
Applicants' parent application provides an electro-kinetic system for transporting and conditioning air without moving parts. The air is conditioned in the sense that it is ionized and contains safe amounts of ozone. The electro-kinetic air transporter-conditioner disclosed therein includes a louvered or grilled body that houses an ionizer unit. The ionizer unit includes a high voltage DC inverter that boosts common 110 VAC to high voltage, and a generator that receives the high voltage DC and outputs high voltage pulses of perhaps 10 KV peak-to-peak, although an essentially 100% duty cycle (e.g., high voltage DC) output could be used instead of pulses. The unit also includes an electrode
Lau Shek Fai
Lee Jimmy Luther
Parker Andrew J.
Chiesa Richard L.
Fliesler Dubb Meyer & Lovejoy LLP
Sharper Image Corporation
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