US3665679A - Electrostatic air cleaner - Google Patents

Abstract

An electrostatic air cleaning device including alternately charged and grounded collector plates extending between a pair of opposed insulated supporting walls. The walls are provided with recesses supporting the charged collector plates staggered relative to the grounded collector plates. A charging conductor extends transversely of the collector plates to engage the projecting edges of one set of collector plates, and a grounding conductor extends transversely of the plates to engage the opposite edges of the other set of collector plates.

Description

United States Patent McLain et al. I May 30, 1972 54 ELECTROSTATIC AIR CLEANER 2,978,066 4/1961 Nodolf ..55/145 3,027,970 4/l962 Mueller 317/261 X [721 Invenwrs' g i E g f shrley 3,040,498 6 1962 Berly ..55/138 5 3 as em 3,181,285 5/1965 Tepolt et al ..55 152 x 1 II I [73] Asslgnee FOREIGN PATENTS OR APPLICATIONS [22] Med: 1970 931,625 7/1963 Great Britain ..55/139 21 Appl. No.2 6,425

OTHER PUBLICATIONS 52 u.s.c1 ..55/137 55 124 55 126 German Primed Applicatic 1009599 Primed June 55/138, 55/139 55/143, 55/144, 55/146, 55/148 1957, (2 sheets drawing, 2 pages speclfication), In 55/154 55/481 55/483 363392? Primary Examiner-Dennis E. Talbert, Jr. [58] Field 6: Search ..55/136-146, 154-156, Lackey 55/124, 126, 148, l5l,48l,483,484 [57] ABSTRACT 5 Referen e Cit d An electrostatic air cleaning device including alternately charged and grounded collector plates extending between a UNITED STATES PATENTS pair of opposed insulated supporting walls. The walls are provided with recesses supporting the charged collector plates 1 g staggered relative to the grounded collector plates. A charging 74 3/193 55 145 X conductor extends transversely of the collector plates to en- 5 ompson gage the projecting edges of one set of collector plates, and a 2297933 /1942 Y X grounding conductor extends transversely of the plates to eng l gage the opposite edges of the other set of collector plates. am 2,925,881 2/1960 Berly et al ..55/ 3 Claims, 7 Drawing Figures Patented May 30, 1972 4 Sheets-Sheet 'L mvemons: BRucE. H. McCLPuM JOHN P. SALLEL SHIRLEY Arm 0 dm} ATTORNEY Patented May 30, 1972 3,665,679

4 Sheets -Sheet 2 INVENTOR$= BRUCE. H. McCLHIN JOH P SALLEE.

SHIRLEY Bdis o I 31 fl- ATTORNEY Patented May 30, 1972 3,665,679

4 Sheets-Sheet 5 INVENTORS1 BEucE .MCCLHIN JOHN P SALLEE.

Hngusv B. As TO BY 4.

ATTORNEY Patented May 30, 1972 4 Sheets-Shaot 4 INVENTORS RUCE. H.M LCLFHN JOHN REAL-LEE. .flsHTo fl. ATTORNEY & FE w @k SH EY Y ELECTROSTATIC AIR CLEANER BACKGROUND OF THE INVENTION This invention relates to an electrostatic air cleaning device, and more particularly to the structure of the walls supporting the collector plates.

Electrostatic precipitators of air cleaning devices are wellknown in the art. Such devices usually include two stages for treating the air, a first ionizing stage and a second collector stage. In the ionizing stage, the air moves past one or more ionizing wires from which are spaced ground electrodes to provide an electrostatic field in which the particles in the air are ionized or electrically charged. The ionized particles then move through the second collector stage, which constitutes a plurality of alternately charged and grounded parallel collector plates creating electric fields. The ionized particles are attracted to one collector plate or the other, depending upon the charge on the particle. The air then leaves the second stage, minus the particles, in a cleaner and more purified state.

Most electrostatic precipitators are provided with power packs, most of which include a voltage doubling circuit for applying a voltage to the ionized wires approximately twice as great as the voltage applied to the collector plates.

The idea of extending some of the grounded collector plates forward between the ionizer wires to also function as a grounded electrode for the ionizing wires is also known.

However, the collector plates in most electrostatic precipitators are supported in spaced apart relationship by means of rods. Some of the rods function also as conductors for the alternate charged plates. However, the grounded plates, through which the charged rods extend, must be insulated from the charged rods in some manner. Such insulation is effected either by placing insulating material between the rods and the grounded plates, or by extending the charged rods through enlarged openings in the grounded plates, and providing a second set of rods for supporting and electrically connecting the grounded plates.

The prior art does teach some electrostatic precipitators having recesses or notches for supporting the edges of some of the collector plates, but most of these precipitators also include the above-mentioned rods for either additional support or for applying a voltage to the plates.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide an electrostatic air cleaning device in which the opposed supporting walls for the collector plates include recesses or grooves in a particular arrangement, not only for supporting the edges of the collector plates, but also for supporting all the electrical conductors to the collector plates and the ionizer electrodes.

Elongated transverse recesses are formed in at least one of the supporting walls for receiving the charging and grounding conductors. Alternately offset plate recesses are formed in the supporting walls between the conductor recesses for receiving the collector plates parallel to each other, but staggered front to rear, so that the front edges of one set of collector plates will electrically contact one conductor, while the opposite edges of the other set of collector plates will electrically contact the other conductor.

By providing the recessed supporting wall structure in accordance with this invention, a minimum of component parts are required for the assembly of the devices, thus expediting the assembly for mass production.

Moreover, by providing practically the entire means for supporting, not only the collector plates, but also the conductors and the ionizing wire mounting means, the obstruction to the flow of air past the ionizer wires and the collector plates is reduced to a minimum.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top, front perspective view of the device, with portions broken away, and disclosing the device mounted in an air conduit, disclosed in phantom;

FIG. 2 is an enlarged right-end view of the device disclosed in FIG. 1, with the power pack removed;

FIG. 3 is an enlarged front elevation of the device disclosed in FIG. 1, with portions broken away;

FIG. 4 is a fragmentary top-plan view of the right end portion of the device, with portions broken away;

FIG. 5 is an enlarged, fragmentary, top-plan view, with the top of the housing and the top supporting wall removed to disclose the ionizing and collector areas;

FIG. 6 is a section taken along the line 66 of FIG. 3; and

FIG. 7 is a slightly reduced section, taken along the line 7- 7 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT As best disclosed in the drawings, the electrostatic air cleaning device 10 made in accordance with this invention includes a power pack 11, a casing or housing 12, and an air cleaning unit or cell 13.

The casing 12, as disclosed in the drawings. includes a top wall 15, a bottom wall 16, an end wall 17, a front flanged opening 18 and a rear flanged opening 19. The right end of the casing 12, as disclosed in the drawings, is open to receive the power pack 1 1.

As best disclosed in FIGS. 1, 6 and 7, front flanged opening 18 may be inserted into a front air duct section 20, and the rear flanged opening 19 may be inserted into a rear duct section 21, so that air may flow in the direction of the arrows from the front duct section 20 through the casing 12 and out through the rear duct section 21.

The right end of the casing 12 is also open to permit the insertion of the air cleaner cell 13 from the right end, while the power pack 1 1 is disconnected from the casing 12.

The air cleaning cell 13 includes a top supporting wall 23 and a bottom supporting wall 24 both of which are identical in construction, and are fixed in spaced apart parallel relationship by the opposed end walls 25 and 26.

The front and rear extremities of the bottom wall 24 com prise elongated recesses or tracks 29 and 30 extending transversely of the cell 13, or transversely of the direction of air flow, to slidably receive the bottom edges of the pre-filter and after- filter lint screens 31 and 32, respectively, of any convenient construction. The function of the pre-filter screen 31 is to remove the larger solid particles from the air stream prior to charging the smaller particles in the air stream. The function of the after-filter screen 32 is primarily to collect excess particles which may become dislodged from the collector plates by the flow of air through the cell 13.

Mounted in the forward portion of the air cleaner cell 13 are a plurality of transversely spaced vertical ionizer wires 35. The ends of each ionizer wire 35 comprise circular loops 36 which are engaged by hook members 37 projecting forward, and mechanically and electrically connected to the ionizer conductor 38. The ionizer conductor 38 is in the form of a conductive cable or wire extending transversely of the cell 13 in an elongated groove 40 formed in the bottom wall 24 of the cell 13. All of the hook members 37 and loop members 36 are conductive to transmit the electrical charge from the ionizing conductor 38 to the ionizer wires 35. The ionizer conductor 38 may be held in the elongated groove 40 by means of a cement coating 41 (FIGS. 5 and 6).

Formed in the bottom supporting wall 24 adjacent to and parallel with the ionizer conductor groove 40 is the elongated front conductor recess 43, as best disclosed in FIGS. 5 and 7. The front conductor recess 43 extends the entire length of the bottom wall 24, which is transverse to the direction of air flow through the cell 13.

In a similar manner, an elongated rear conductor recess 44 is formed in the bottom supporting wall 24 in front of and adjacent the rear screen track 30, also best disclosed in FIGS. 5 and 7.

Formed in the bottom wall 24 between the front conductor recess 43 and the rear conductor recess 44 are a plurality of parallel first collector plate recesses 45 and second collector plate recesses 46. All of the collector plate recesses 45 and 46 are elongated and extend in the same direction as the air flow through the cell 13. The collector plate recesses 45 and 46 share common side walls 47 which are insulated. All of the first recesses 45 have their rear ends closed by the rear insulated walls 48, and their front ends open to communicate with the front conductor recess 43. Conversely, all of the second collector plate recesses 46 have their front ends closed by the front insulated walls 49, and their rear ends open to communicate with the rear conductor recess 44. Thus, as best disclosed in FIG. 5, the side walls 47, rear end walls 48 and front end walls 49 form a single continuous, and sinuous wall, undulating back and forth between the alternating first and second recesses 45 and 46 from one end to the other of the bottom supporting wall 24. Because of this construction, the first recesses 45 are staggered or offset forward relative to the second recesses 46.

Aligned with every third, or any other desirable multiple, of the second collector plate recesses 46 is an extension plate recess 50 extending between the ionizer conductor groove 40 and the front screen track 29, and substantially equally spaced apart transversely and on opposite sides of each ionizer wire 35.

As previously indicated, the top wall 23 is constructed, preferably molded, in the same shape as the bottom supporting wall 24, and is provided with the same grooves and recesses formed in the bottom supporting wall 24. The corresponding grooves and recesses in the top wall 23, where described or disclosed, are indicated by the same reference numerals, followed by a prime.

A plurality of rectangular charged collector plates 53 are mounted within the cell 13 spaced parallel to each other and parallel to the direction of air flow, and are mounted to alternate with a plurality of grounded collector plates 54 and 55. The bottom edge of each charged plate 53 is received in a plate recess 45 so that its front edge projects forward into the front conductor recess 43. To provide a snug fit, the width, or the dimension of the charged plate 53 extending in the direction of air flow, is preferably slightly longer than the length of the plate recess 45 so that the rear edge of the plate 53 will abut against the rear end wall 48, while its front edge projects slightly into the front conductor recess 43. In a similar manner, the top edge of the charged plate 53 is received in the corresponding and vertically aligned recess 45 in the top supporting wall 23.

Snugly received in the front conductor recess 43 is an elongated front conductor, disclosed in the form of an elongated electrical cable 57. When the cable 57 is fitted in its recess 43, the cable 57 mechanically and electrically engages the front edge of each of the charged collector plates 53, thus retaining the collector plate 53 in its recess 45,

Each of the grounded collector plates 55 is provided with a forward extension section 60, so that when the bottom edge of the plate 55 is seated in a plate recess 46, which is in alignment with an extension plate recess 50, the extension section 60 will also seat in the recess 50. The grounded collector plates 55 are provided with cutout portions 61 to provide an air gap insulation between the grounded plates 55 and the front conductor cable 57 and the ionizer conductor 38. The extended plate sections 60 provide ground electrodes for each of the ionizer wires 35.

All of the remaining plate recesses 46 receive the bottom edges of the rectangular, grounded collector plates 54. Other than having this extended plate section 60, the grounded collector plates 55 are quite similar to the grounded collector plates 54. Both plates 54 and 55 have front edges which engage the front end walls 49, and have their rear end walls projecting slightly into the rear conductor recess 44.

A rear conductor cable 58 is snugly fitted into the entire length of the rear conductor recess 44, to mechanically and electrically engage the rear edges of each grounded collector plate 54 and 55.

The top edges of the grounded collector plates 54 and 55 are also received in plate recesses in the top supporting wall 23 identical to and vertically aligned with the bottom plate recesses 46, but which are not specifically disclosed in the drawings.

Since these plate recesses 45 and 46 are disclosed as being identical in length, although staggered in the direction of air flow, the charged collector plates 53 and the grounded collector plates 54 may be identical in construction, and even interchangeable, so that their functional differences are deter mined, not by their construction, but by their location in one or the other of the recesses 43 and 44, which determines whether the collector plate engages the front conductor cable 57, or the rear conductor cable 58.

The right end of the ionizer conductor 38 projects upward, where it is electrically connected by soldering, or otherwise, to an ionizer leader wire 63 extending through the end wall 26. The leader 63 terminates in an ionizer contact 64 on the exterior of the end wall 26, as best disclosed in FIGS. 2 and 6.

The charged collector plate 53, which is closest to the right end wall 26, is electrically connected to a conductor rod 65. The rod 65 projects to the right through an enlarged opening 66 in the end grounded collector plate 55, then through the right end wall 26 where it terminates in the collector charging terminal 67. Since the collector plate 53' engages the front conductor cable 57, any voltage which is impressed upon the terminal 67 will be supplied to all the collector plates 53 and 53, which are electrically connected in parallel through the cable 57.

The rear conductor cable 58 is also grounded at its right end through the ground leader 68, which rises on the inside of the right end wall 26, extends through the wall 26, and is electrically connected to the ground bar 70, which also functions as a handle for manipulating the cell 13. Conductive spring clips 71 may be formed at each end of the handle 70 for detachably receiving conductive chains 72 connected to the right ends of the screens 31 and 32. Thus, any stray potential charges which may be impressed upon the screens 31 and 32 will be discharged through their grounded connections 72, 71 and 70.

As disclosed in FIGS. 6 and 7, the top wall 23 is provided with a front cable 57, a rear cable 58, an ionizer conductor 38 and all the other identical elements found in the lower supporting wall 24.

The power pack 11 includes conventional electrical elements and circuitry, and preferably includes a voltage doubling circuit. A potential of approximately 8,000 volts DC is transmitted from the power pack 11 through the electrode or probe 74 to the ionizer terminal 64, so that each ionizer wire 35 has a potential of 8,000 volts DC. One-half the voltage of the ionizer wires is supplied through the electrode or probe 74 from the power pack 11 to the collector terminal 67' to impress the voltage of 4,000 volts DC upon each of the charged collector plates 53 through the end collector plate 53 and charging conductor 57. The power pack 11 is also provided with a ground contact 76 for engaging conductor handle 70, to complete the ground circuit to the grounded collector plates 54 and 55,

Power pack 11 is detachably connected to the casing 12 by means of the latches 80, so that the potentials are impressed upon the ionizer wires 35 and collector plates 53, 54 and 55, only when the power pack 11 is attached to the casing 12.

The main reason that duplicate top and bottom electrical conductors 38, 38, 57, 57, 58 and 58 are mounted in the top and bottom supporting walls 23 and 24, is so that electrical connections can be made between the power pack 11 and the various electrical elements in the cell 13, when the cell 13 is right side up or upside down. Thus, if the cell 13 were turned upside down, the ionizer probe 74 would contact the ionizer terminal 64, instead of the terminal 64, and the collector charging probe 75 would contact he collector charging terminal 67, instead of the terminal 67, and the ground contact 76 would still engage the handle 70, since the handle 70 is located in the center of the end wall 26.

The power pack 11 may be supplied with current through the supply cord 81 from any convenient source of electricity.

The collector cells 13 are also adapted to be stacked vertically, or end-to-end, or both; in order to process air in larger capacity ducts. The casings 12, would of course, be larger to receive the multiple cells 13.

The side walls 47 of the plate recesses 45 and 46 may be provided with lateral protuberances 85 (FIG. 5), if desired to snugly engage the opposite surfaces of the collector plates 53, 54 and 55, to afford tighter seats.

In actual operation, the pre-filter screen 31 catches the larger visible particles as the air enters the cell 13 from the duct 20. The smaller particles are charged by the ionizer wires 35, and then are attracted to one or the other of the collector plates 53, 54 or 55, depending upon the charge on the particles. The after-filter screen 32 primarily traps any particles which accumulate upon the plates and are subsequently removed by the passage of air. However, the after-filter screen 32 also functions in case of power failure to filter additional larger particles not separated by the pre-filter screen 31.

It has been found that the collector cell 13 removes over 90 percent of all air-borne contaminants, even particles as small as 0.01 microns, which includes cigarette smoke and some viruses.

What is claimed is:

1. An electrostatic air cleaning device comprising:

a. opposed supporting walls of insulating material having opposed, substantially planar, inner faces,

b. first elongated insulated recesses in at least one of said inner faces, substantially parallel to the air flow through said device,

c. each of said first recesses having an open upstream end and a closed downstream end,

d. second elongated recesses in at least said one of said inner faces, parallel to and alternating with said first recesses,

e. each of said second recesses having an open downstream end and a closed upstream end,

an elongated upstream conductor recess extending transversely in at least said one of said inner faces in open communication with said open upstream ends, and substantially coplanar with said first recesses,

g. an elongated downstream conductor recess extending transversely in at least said one of said inner faces in open communication with said open downstream ends, and substantially coplanar with said second recesses,

h. an elongated upstream conductor longitudinally received in said upstream conductor recess,

i. an elongated downstream conductor longitudinally received in said downstream conductor recess,

j. first collector plates extending betweensaid supporting walls,

k. each of said first collector plates having upstream and downstream edges and being received in a first recess so that said upstream edges project through said open upstream ends into said upstream conductor recess to mechanically and electrically contact said upstream conductor,

1. second collector plates extending between said supporting walls,

m. each of said second collector plates having upstream and downstream edges and being received in a second recess so that said downstream edges project through said open downstream ends into said downstream conductor recess to mechanically and electrically contact said downstream conductor,

n. means for applying an electrical voltage to one of said conductors.

0. means for electrically grounding said other conductor,

p. ionizing means upstream of said upstream conductor comprising ionizer electrodes extending between said oposed supporting walls 2. e Invention according to claim 1 in which said ionizer electrodes comprise a plurality of ionizer wires, an elongated groove extending transversely in at least one of said inner faces upstream of said upstream conductor recess and substantially insulated therefrom, an elongated ionizing conductor received in said groove and in electrical communication with said ionizer wires, and means for connecting said ionizing conductor to said voltage applying means.

3. The invention according to claim 2 in which some of said collector plates which are electrically grounded comprise ionizer plate sections projecting upstream between said ionizer wires, said plate sections having recessed portions spaced from said ionizing conductor and said upstream conductor, said upstream conductor being connected to said voltage applying means.

Claims (3)

1. An electrostatic air cleaning device comprising: a. opposed supporting walls of insulating material having opposed, substantially planar, inner faces, b. first elongated insulated recesses in at least one of said inner faces, substantially parallel to the air flow through said device, c. each of said first recesses having an open upstream end and a closed downstream end, d. second elongated recesses in at least said one of saId inner faces, parallel to and alternating with said first recesses, e. each of said second recesses having an open downstream end and a closed upstream end, f. an elongated upstream conductor recess extending transversely in at least said one of said inner faces in open communication with said open upstream ends, and substantially coplanar with said first recesses, g. an elongated downstream conductor recess extending transversely in at least said one of said inner faces in open communication with said open downstream ends, and substantially coplanar with said second recesses, h. an elongated upstream conductor longitudinally received in said upstream conductor recess, i. an elongated downstream conductor longitudinally received in said downstream conductor recess, j. first collector plates extending between said supporting walls, k. each of said first collector plates having upstream and downstream edges and being received in a first recess so that said upstream edges project through said open upstream ends into said upstream conductor recess to mechanically and electrically contact said upstream conductor, l. second collector plates extending between said supporting walls, m. each of said second collector plates having upstream and downstream edges and being received in a second recess so that said downstream edges project through said open downstream ends into said downstream conductor recess to mechanically and electrically contact said downstream conductor, n. means for applying an electrical voltage to one of said conductors. o. means for electrically grounding said other conductor, p. ionizing means upstream of said upstream conductor comprising ionizer electrodes extending between said opposed supporting walls.

2. The invention according to claim 1 in which said ionizer electrodes comprise a plurality of ionizer wires, an elongated groove extending transversely in at least one of said inner faces upstream of said upstream conductor recess and substantially insulated therefrom, an elongated ionizing conductor received in said groove and in electrical communication with said ionizer wires, and means for connecting said ionizing conductor to said voltage applying means.

3. The invention according to claim 2 in which some of said collector plates which are electrically grounded comprise ionizer plate sections projecting upstream between said ionizer wires, said plate sections having recessed portions spaced from said ionizing conductor and said upstream conductor, said upstream conductor being connected to said voltage applying means.

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