Electrostatic air filter

Abstract

An electronic air filter having a plurality of electrodes supported by rigid fixtures that are attached to a common case. The rigid fixtures that support the electrodes with different electrical potentials are attached to each other or to a common body in a way that increases or maximizes the creeping discharge path along the surface. Even conductive contaminants do not, therefore, provide an electrical shortage between the electrodes.

Claims

1. An electrostatic air filter comprising: a case formed by walls and having an open air inlet and an open air outlet; a first electrode set having a first electrical potential assembled on a first rigid fixture; a second electrode set having a second electrical potential different from said first electrical potential and assembled on a second rigid fixture separate from said first rigid fixture; said first rigid fixture is mounted to said case at a first set of spots and said second rigid fixture is mounted to said case at a second set of spots; wherein said first set of spots is spaced from said second set of spots by an extended creeping distance; and wherein said first electrode set is a collecting electrode set and said collecting electrode set comprises a plurality of collecting electrodes mounted parallel to each other and substantially parallel to a principal air flow direction; wherein said second electrode set is a repelling electrode set and said repelling electrode set comprises a plurality of repelling electrodes mounted parallel to each other, substantially parallel to a principal airflow direction and interleaved with said plurality of collecting electrodes; wherein said collecting electrodes have collecting electrode apertures and said repelling electrodes have repelling electrode apertures; wherein said first rigid fixtures go through said repelling electrode apertures without touching said repelling electrodes; wherein said second rigid fixtures go through said collecting electrode apertures without touching said collecting electrodes; wherein said walls include a first inner wall and a first outer wall generally parallel to said principal airflow path on a first side of said case and said first inner wall and said first outer wall are positioned to define an air gap there between; wherein said walls include a second inner wall and a second outer wall generally parallel to said principal airflow path on a second side of said case opposing said first side of said case and said second inner wall and said second outer wall are positioned to define an air gap there between; said first inner wall and said second inner wall have one or more apertures; said first rigid fixtures are secured to said first outer wall on said first side of said case and go through apertures in said first inner wall without touching said first inner wall and said first rigid fixtures are connected to said second inner wall; said second rigid fixtures are secured to said second outer wall on said second side of said case and go through apertures in said second inner wall without touching said second inner wall.

2. The electrostatic air filter according to claim 1 wherein one or more of said walls is corrugated.

3. The electrostatic air filter according to claim 1 wherein a surface of at least one of said first rigid fixture and said second rigid fixture is corrugated.

4. The electrostatic air filter according to claim 1 further comprising a shield positioned to block said air gaps.

5. An electrostatic air filter electrode assembly comprising: an accordion rack; a first group of electrodes mounted in parallel on said accordion rack; and a second group of electrodes which operate at a different potential than the first group of electrodes mounted in parallel on said accordion rack; wherein said first group of electrodes are mounted in an alternating sequence with said second group of electrodes; wherein said accordion rack further comprising lateral supports each having a plurality of members connected in an accordion fashion at middle pivot points and edge pivot points; and wherein at least some of said members include extended portions which extend beyond said edge pivot points; and further comprising corona electrodes mounted on said extended portions.

6. The electrostatic air filter according to claim 1 wherein said walls include a first set of parallel walls and a second set of parallel walls; and said first rigid fixture is mounted to said first set of parallel walls and not in contact with said second set of parallel walls and said second rigid fixture is mounted to said second set of parallel walls and not in contact with said first set of parallel walls.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A shows a schematic illustration of a prior art electrode configuration. FIG. 1B shows a portion of FIG. 1A enlarged.

(2) FIGS. 2A, 2B, 2C, 2D and 2E show an electrostatic filter with a case.

(3) FIGS. 3A and 3B show a partial view of a filter with an inlet exciting electrode and corona wires located on the frame.

(4) FIGS. 4A and 4B show a second embodiment of an electrostatic filter.

(5) FIGS. 5A and 5B show the top view of an electrostatic filter in unfolder and folded configurations.

(6) FIGS. 6A, 6B, 6C, 6D and 6E show an alternative electrode support configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) Before the present invention is described in further detail, it is to be understood that the invention is not limited to the particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

(8) Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

(9) Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, a limited number of the exemplary methods and materials are described herein.

(10) It must be noted that as used herein and in the appended claims, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise.

(11) All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

(12) The invention is described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.

(13) The term creeping distance is used to indicate the distance between the two closest points on the surface of an insulated structures between components having different potentials, for example corona electrodes and collecting electrodes. The term creeping path is used to indicate the path of current flow on the surface of an insulated structure between components having different potentials, for example corona electrodes and collecting electrodes. The creeping path is no shorter than the creeping distance as the creeping path is the actual current path and the creeping distance is a measure of the minimum distance along a surface between two points.

(14) An electrostatic air filter may have several groups of electrodes. All electrodes in a group have the same or similar electrical potential. The electrical potential difference between the groups of electrodes may be ranged from several kilovolts to several tens of kilovolts.

(15) Corona electrodes in an electrostatic air cleaner may be in the form of thin wires and may be located on a corona frame. The collecting electrodes may be secured on common rigid fixture. Sets of rods or brackets may be used to mount the collecting electrodes.

(16) Electrodes that belong to the same group may be secured on a common rigid fixture. The rigid fixtures may be secured, integrated with, or attached to a non-conductive case in a manner where the attachment points for rigid fixtures that support the electrodes under different electrical potentials are spaced apart from each other along the surface of the case. The spacing may be selected to increase the creeping distance between electrodes of differing potentials. The spacing may be greater than the minimum spacing otherwise permitted

(17) FIGS. 2A, 2B, 2C, 2D, and 2E show an electrostatic air filter 201 with a case 202. The case 202 may be non-conductive and may have two horizontal and two vertical walls attached to each other. The electrostatic air filter 201 may have a corona electrode frame 203 with parallel thin wires, an exciting electrode 204 with an air penetrable electrically conductive web, collecting electrodes 205 which may be secured by four brackets 208 to vertical walls 206 of the case 202, and repelling electrodes 209 which may be received in slots 213 provided in horizontal walls 210 of the case 202. The exciting electrode 204 may be secured to the case 202 by brackets 208. The brackets 208 may be attached to the vertical walls of the case 202 with latches 211, 212. The exciting electrode 204 may be grounded or at a low (i.e., safe) electrical potential. The exciting electrode 204 may also serve as an electrical protection for people and as a rough pre-filter at the same time. The exciting electrodes 204 may be located on upstream or downstream side of the corona electrode 203.

(18) The exciting electrode 204 fixture may be attached to opposing parallel walls of the case, for example, at the vertical walls. The corona wires may be under high electrical potential in the order of several kilovolts to several tens of kilovolts. Therefore, the corona electrode 203 fixture may be attached to orthogonal walls, for example, the horizontal walls of the case 202. Such a configuration provides an extended creeping path from the corona electrode frame 203 to the exciting electrode frame 204 via the surface of the case 202.

(19) The repelling electrodes 209 may be located between the collecting electrodes 205 and may be parallel to each other. The repelling electrodes 209 may be attached to the horizontal plates of the case 202 by the slots 213. The repelling electrodes may be under high electrical potential that is close to or, in some instances, the same as the electrical potential on the corona electrode wires. Therefore there is no need to separate the corona electrode frame 203 and the repelling electrodes 209 by a long creeping path.

(20) The collecting electrodes 205 may be secured by the brackets 208. The collecting electrodes 205 may be located between the repelling electrodes and may be parallel to each other. The collecting electrodes 205 may be under a low electrical potential that is close to the electrical potential of the exciting electrodes 204. The collecting electrodes 205 may be separated from the horizontal walls of the case by air gaps.

(21) The brackets 208 may hold the collecting electrodes 205 and may be secured to the vertical walls of the case 202, while the repelling electrodes 209 may be attached to the horizontal walls. Such an arrangement ensures an extended creeping path along the surface between the collecting electrodes 205 and the repelling electrodes 209.

(22) The shortest distance for the creeping discharge is from the outmost repelling electrodes 209 via part of the horizontal wall of the case 202, then via part of the vertical wall of the case 202, and finally via part of the brackets 208 to the outmost collecting electrodes 205. This path is much longer than it would be if the collecting electrodes and the repelling electrodes were both supported by the horizontal wall of the case 202 like in the existing art.

(23) Another feature further prevents a creeping discharge between the electrodes that are under different electrical potentials. The surfaces connecting such electrodes may be made winding or corrugated or convoluted in the same manner as surfaces of outdoor electrical insulators in transmission lines. That feature, along with the arrangement described above, ensures an even longer path for the creeping discharge along the surface.

(24) FIGS. 3A and 3B show a partial view of a filter with an inlet exciting electrode 304 and corona wires located on the frame 303. A protecting shield 310 may be provided to impair, deflect, or block air passage along the walls of the case 202. This reduces the amount of particulate that will settle and contaminate the walls of the filter case 202.

(25) The collecting electrodes 205 may advantageously be located on a separate fixture, i.e., on the brackets 208 or 308. When the collecting electrodes 205 (305 in the FIG. 3) become contaminated, the whole collecting electrodes assembly may be removed from the case 202. Usually, the distance between the neighboring electrodes is larger than the thickness of the electrodes. In this case, two or more collecting electrodes assemblies may be inserted into each other. This way, they occupy much less space. A consumer or a customer, therefore, would enjoy cost and space savings on shipment and storage.

(26) FIGS. 4A and 4B show a second embodiment of an electrostatic filter. The electrostatic air filter 401 may contain collecting electrodes 403 and the repelling electrodes 404. The collecting electrodes 403 and the repelling electrodes 404 may be assembled on an accordion rack 402. The accordion rack may be constructed of folding bars connected at middle pivot points 408 and edge pivot points 409. The collecting electrodes 403 and repelling electrodes 404 may be secured at the edge pivot points 409 of the bars of the accordion rack 402. The bars may have shorter extensions 405 and longer extensions 406. The exciting electrode 407 may be a conductive web similar to 204 in the FIG. 1 and may be attached to the longer extensions. The corona electrodes (not shown) may be similar to electrodes 203 in FIG. 1 and may be attached to the shorter extensions 406. Alternatively, the corona electrodes may be attached to the longer extensions 405 while the exciting electrode may be attached to the shorter extension 406.

(27) In the configuration shown in FIGS. 4A and 4B, the distance, along any structural component between collecting electrodes 403 and adjacent repelling electrodes 404 may be substantially greater than the space between the collecting electrodes 403 and adjacent repelling electrodes 404. The shortest creeping path therebetween requires traversal of the folding bars.

(28) As a practical example, assuming that the width (along the air flow direction) of the collecting electrode 403 is equal to 200 mm and the width of the repelling electrode 404 is equal to 180 mm, then the creeping path along the bars is approximately 150 mm. At the same time, the electrodes are separated from each other by about 10 mm. The arrangement shown in FIGS. 4A and 4B increases the creeping path by about 15 times compared with the shortest distance between the electrodes through the air.

(29) The arrangement shown in the FIGS. 4A and 4B has still another advantage over the existing art. It is foldable. FIG. 5A shows a top view of an electrostatic air filter in an unfolded (operational) configuration. FIG. 5B shows a top view of an electrostatic air filter in a folded (stored) configuration. The unfolded configuration, shown in FIG. 5A may be about 530 mm (left to right), while the folded configuration shown in FIG. 5B may occupy just 63 mm. This is more convenient for filter maintenance (replacement) and also presents an advantage in cost savings for shipment and storage of the electrostatic air filter parts. In order to facilitate deployment of the electrodes, the pivots may have some sliding clearance and mechanism for locking the plate in the deployed (or open) position of the folding bars/pivot points.

(30) FIGS. 6A, 6B, 6C, 6D and 6E show an alternative electrode support configuration for increasing the creeping path length and has substantially improved filter performance in dirty atmospheres.

(31) The electrostatic air filter 601 may contain a plurality of collecting electrodes 602 with apertures 608 and a plurality of repelling electrodes 603 with apertures 609. The collecting and repelling electrodes may alternate. The collecting electrodes 602 may be assembled with the conductive rods 604. These rods 604 may be attached to the collecting electrodes 602 and to the case wall 607. The repelling electrodes 603 may be assembled on conductive rods 605. Rods 605 may be attached to repelling electrodes 603 and to the case wall 606. The case walls 606 and 607 may be made of non-conductive material like ABS plastic.

(32) The rods 604 are not electrically connected to repelling electrodes 603 and the rods 605 are not electrically connected to collecting electrodes 602. Therefore, the creeping path does not exist here. However, the creeping path is along the surface of the case wall 606 and 607. The rods 604 may pass through an aperture 610 in the walls 606. Aperture 610 may have a diameter greater than the diameter of the rod 604. Therefore, there is no electrical contact between the collecting electrodes 602 and the wall 606. The same provision may be provided for the rods 605 with apertures 608 and rods 604 with apertures 609.

(33) The creeping path between the collecting electrodes 602 and the repelling electrodes 603 may be substantially greater than in the existing art. The creeping path in the embodiment shown in FIGS. 6A and 6B is from the rod 605 along the wall 606 all way to the vertical wall of the case (not shown), then up along the vertical wall, and then back along the wall 607 to the place where the rod 604 is secured to the wall 607. In addition, the electrostatic air filter may be equipped with a protecting shield similar to shield 310 shown in FIG. 2. In addition, the creeping path may be further increased by forming walls 606 and 607 with a corrugated shape.

(34) The techniques, processes and apparatus described may be utilized to control operation of any device and conserve use of resources based on conditions detected or applicable to the device.

(35) Thus, the specific systems and methods for the electrostatic air filter have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the disclosure. Moreover, in interpreting the disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms contains and containing should be interpreted as referring to members, or components in a non-exclusive manner, indicating that the referenced elements and components, may be present, or utilized, or combined with other members and components that are not expressly referenced.