US 2997130 A
Description (OCR text may contain errors)
Aug. 22, 1961 K, M, NoDoLF FLUID CLEANING APPARATUS Filed Jan. 8, 1959 AIR FLOW INVENTOR. KEITH M. NODOLF United States Patent O 2,997,130 c FLUID CLEANING APPARATUS Keith M. Nodolf, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis,
' a corporation of Delaware Filed Jan. 8, 1959, Ser. No. 785,638 3 Claims. (Cl. 1837) same market presently using mechanical filters which are commonly used in the conventional forced air residential furnaces. With the increased desirability to have more efficient air cleaning in residential circulating systems, the need for a relatively cheap and yet efficient air cleaning apparatus has increased.
The present invention is an electrostatic air cleaning apparatus with an ionization and collection section. The apparatus has a cleaning efficiency much higher than the conventional mechanical filters, and it has exterior dimensions similar to the conventional mechanical filters; so that, the improved electrostatic air cleaner can be easily substituted for many types of mechanical filters.
An object of the present invention is to provide an improved electrostatic gas cleaning apparatus.
Another object of the present invention is to provide an improved electrostatic gas cleaning apparatus having a relatively short dimension in the direction of gas flow; so that, the unit might easily replace a conventional mechanical filter. Y
And still another object of the present invention is to provide in an improved electrostatic gas cleaning apparatus, an improved particle collecting section made up of relatively closely spaced, parallel, corrugated plates which are oppositely charged and having spacer means between the plates; so that, when connected to a source of voltage an electric iield is established between the parallel plates.
These and other objects of the present invention will become apparent upon the study of the following speciiication and drawings of which:
FIGURE l is a schematic side view of the present invention showing a portion of the ionization section and the collecting section of the cell.
FIGURE 2 is a rear view of the improved unit looking in the opposite direction of air flow as shown in FIG- URE 1.
Referring to FIGURE l, an electrostatic gas cleaning apparatus is shown having an ionization section 10 and a collecting Section lil which is spaced downstream of the ionization section. The sections are separated from one another by a mechanical filter medium 12. Medium 12 provides a pressure dropped across the unit; so that, a pressure responsive dirty iilter indicator can be used. 'I'he medium also provides-a more-even air distribution through the unit to increase the efficiency of the ionization and collection. When the leading edge of the positive plates 31 of the collection unit are closer to the leading edge of thenegative plates 30 and 32, the medium provides increased arcing path between the positive plate 31 land the ground plates 14 ofthe ionization section. When the medium is used, the ionization wire can be placed somewhat downstream of Wire mesh 16 to control the ionization current without having arc-over to the ground plates of collection section 11. The sections have common sides of which only a side 13 is shown in FIG- URE l. When placed in operation, the unit is mounted so that air iirst passes through ionization section 10 Where the particles of foreign material in the air are charged. As the air passes downstream into collecting section 11, the charged particles are attracted to a plate of the opposite polarity to lose their charge and are collected.
The unit might have a dimension in the direction of air flow of approximately 2 inches; so that, the outer dimensions of the unit are approximately 2 inches by 20 inches by 2() inches. The dimensions are the same as many conventional mechanical filters, using some sort of spun glass or fiber material, which are normally placed in forced air furnaces. With the size comparable to the mechanical filters, the present invention is adapted to replace the mechanical lters by sliding it into position and connecting it to an appropriate high voltage power supply in a manner as shown in FIGURE l.
The ionization unit 10 is of a conventional type except for size. Unit 10 comprises a plurality of parallel metal plates 14 which are held by appropriate groove 15 (shown in FIGURE 2) of end plates 20 and 21 located at the two extremities of plate 14. Plate 14 has a tab 26 at each end which is inserted through the notch of the ends 20 and 21 and bent over. Tab 26 provides a support for the plate to hold it in position. The plates of the ionization unit are connected by the tab 26 to the negative side of a source of D.C. potential. Spaced in between the parallel plates 14 is a wire 22 which is Ystrung between the ends 20 and 21 and is parallel to the plates. The wire has a coil 23 at each end which is inserted through a notch in the end sections 2d and 21 for holding the wire in tension and providing an electrical connection to the positive side of the D.C. power source, through an appropriate connecting strip (not shown) running along end plate 20. The leading surface of unit 10 is covered with a protective wire mesh 16.
Collecting unit 11, as shown in FIGURE 2 looking at the rear of the unit shown in FIGURE l, has a plurality of parallel, corrugated metal plates, three of which are labeled as 30, 31 and 32. The plates are so assembled that every other plate is known as the ground plate, and the plates intermediate the ground plates are known as the positive plates. The positive plates, one of which being 31, are slightly narrower than the ground plates for the dimension measured in the direction of air ow. The shorter dimension of plate 31 then provides an increased air space between the edges of the ground plates 30 and 32 and the edge of the positively charged plate 31 for insulation purposes. When the collecting unit 11 is placed against the filter medium 12, the ground plates are contacted, but a space is maintained between the positive plates and the medium. On the downstream side, any object laying across the end of the unit would only contact the edges of ground plates 30 and 32. The downstream surface of section 11 is covered with a protective wire mesh 17.
The ends of the plates 30, 31 and 32 are received in appropriate grooves of end sections 33 and 34 for holding the plates in a spaced relationship. The edge of the end sections 33 and 34 facing into the cell have an elongated surface 35 between adjacent plates as shown in FIGURE 2. This elongated surface is formed when the ends 33 and 34 are molded, and it provides for a long creep distance between the oppositely charged plates to lessen the chances of Voltage breakdown during operation.
The ends of plates 30, 31 and 32 have tabs which are received in notches in ends 33 and 34. Plate 30 has tabs 40 and 41 which are inserted into the groove of end sections 33 and 34, respectively. The tabs are then bent over to provide the electrical connection to the negative side of a D.C. source of power through a terminal strip (not shown) along end plate 34. Tabs 42 and 43 of the positive plate 31 are also inserted through the appropriate grooves of the ends 33 and 34, respectively. Both tabs 42 and 43 are bent over to hold the place in position, and tab 43 is used to connect the positive plate of the cell to the positive side of a source of D.C. voltage through a terminal strip (not shown) running along end plate 34.
To provide the spacing intermediate the ends of the plates 30, 31 and 32, a plurality of spacer bars or rods are attached to each plate. These bars are made of a nonconducting material such as polyethylene or plastic, and they are attached at their ends to a high point on each plate. Specifically referring to FIGURE l, bars 50 and 51 are shown attached to the underside of plate 30. The side View of the bar 51 is shown in FIGURE 2. Since the bar 51 spans one corrugation of the plate 30 and the corrugations of the parallel plates are in alignment, the adjacent oppositely charged plate 31 will engage bar 51 intermediate its ends to maintain a spacing between adjacent plates 30 and 31. Attached to the underside of the positive plate 31, are bars 52 and 53 as shown in FIGURE l. Bars 52 and 53 are attached to plate 31 to span the corrugation and engage the adjacent plate 32 intermediate their ends. A spacing is then provided between adjacently oppositely charged plates 30 and 32.
While only one set of spacer bars is shown in FIG- URE 2, it is obvious that any number of these bars might be used across the plates intermediate ends 33 and 34 to maintain the parallel oppositely charged plates in a given spaced relationship. The arrangement of the bars S1 and 53 as shown in FIGURE 2, is such that the distance across the insulating bar is greater than the plate spacing as measured perpendicular to the adjacent plate surface. This has a marked advantage in allowing higher voltages to be used in the collecting unit 11 as voltage breakdown does not occur when the creep distance along insulator 51 is significantly greater than the perpendicular spacing between the adjacent plates.
The operation of the gas cleaning apparatus is quite conventional. The unit as shown in FIGURE 1 would be connected when slid into an appropriate housing which would be a part of the duct in a forced air heating or4 cooling apparatus. As the unit Was placed in position, appropriate means would contact tabs 21, 43, and 41, as well as, coil 23 to connect ionization section 10 and collecting section 11 to a conventional source of high voltage D C. The air flow would carry foreign particles into the ionization section and the particles would be charged as the air passed between positively charged wires 22 and ground plates 14. With the foreign particles charged, the air would pass through the medium 12 and into the collecting section. The foreign particles would be attracted to the plates of the collection section of opposite charge and would collect in the collecting unit.
As soon as the dirt collected on the parallel plates of the collecting unit and on medium 12 reached some predetermined quantity, some appropriate indicator would inform the homeowner that the filtering apparatus needed cleaning. The unit would lbe slid from its housing and washed in some appropriate manner.
While the invention has been described in one particular manner, the intention is to limit the scope of the invention only by the appended claims, in which I claim:
1. In an electrostatic gas cleaning apparatus having a relatively small dimension in the direction of gas How, an ionizing section comprising parallel spaced plates having charged wires strung therebetween so that as the gas passes between said plates and said wires, foreign material in the gas is electrically charged, a particle collecting section comprising, a iirst set of parallel, corrugated, conductive plates, a second set of parallel, corrugated,
conductive plates, a pair of insulating ends having a plurality of spaced slots, said first and second set of plates being held between said spaced ends so that each plate of said sets has its surface parallel to the direction of gas flow and its extremities in a slot in said ends to form an assembly of .alternate plates of said rst set and then said second set with the corrugations of adjacent plates matching, a plurality of straight insulating members having a relatively small cross section as compared to their lengths, each of .said members being attached to said plates intermediate said ends to span at least one corrugation and touch an adjacent plate intermediate the ends of said members so that said first set of plates are electrically insulated from said second sets of plates, and means connecting said first and second set of plates to the opposite sides of a source of power, and a mechanical filter medium spaced between said ionizing section and said collecting section.
2. In an electrostatic gas cleaning apparatus of a compact type adapted to replace a conventional mechanical filter, Van ionization section, a collecting section, and a power supply, said ionization section being mounted upstream said collecting section and being connected to said power supply to charge the `foreign particles of material in suspension in the gas, said collecting section being downstream said ionization section and comprising, a plurality of corrugated conductive plates, a pair of insulating end members having parallel grooves, said plates being assembled between said end members in spaced relationship with the corrugations in alignment so that said plates having their relatively short dimension in the direction of gas ow as compared to the dimension of the plates across the collecting section perpendicular to the gas flow, the perpendicular distance between adjacent plates is approximately constant over the complete surface of all of said plates and the corrugated surface of each of said plates is parallel to the direction of gas ow, and a plurality of insulating spacer means spaced across the width and length of said plates, said spacers beingrelatively straight and having a length much greater than their cross sectional dimensions, each of said spacers spanning a corrugated portion of one plate and engaging an adjacent plate near the middle portion of said spacer intermediate the points of contact on said one plate.
3. In a collecting cell for an electrostatic gas cleaning apparatus, a plurality of corrugated metal plates assembled With the corrugations in alignment so that adjacent plates have all portions thereof an equal distance apart as measured perpendicular to a surface of said plates and Vso that the corrugated surfaces of said plates are parallel to the direction of gas flow through the cell, a plurality of spacer means, said spacer means being attached to each of said plates at a plurality of spaced points across the surface of said plate, each of said spacer means cornprising a thin straight section of dielectric material being relatively long as compared to its cross sectional dimensions, each of said spacer means being attached to one of said plates to span at least one of the corrugations and touch an adjacent plate intermediate the attachment of said spacer on said one plate.
References Cited in the file of this patent UNITED STATES PATENTS 2,567,899 Warburton Sept. 11, 1951 2,579,441 Palmer Dec. 18, 1951 2,813,595 Fields Nov. 19, 1957 2,875,845 Penney Mar. 3, 1959 FOREIGN PATENTS 464,308 Germany Aug. 16, 1928 750,701 France May 29, 1933