Fastening means for electronic air cleaner cells

A fastening means for an electronic air cleaner. The air cleaner containing an air cleaner collector section. The air cleaner collector section is a series of high voltage and low voltage plates which are held by cell expansion tubes. On either end of the air cleaner collector section, end plates are placed in order to hold the air cleaner collector section in place. Flare tubes are passed through the end plates and the cell expansion tubes and are flared in order to fasten the end plates in place, thereby fastening the air cleaner collector section.

FIELD OF THE INVENTION 
This invention is in the field of electronic air cleaner cells. More 
specifically, this invention is a means for fastening the air cleaner 
collector section to the end plates of the cell. 
BACKGROUND OF THE INVENTION 
Electronic air cleaners have been in existence since the early 1960's. This 
field is now well developed and highly competitive. Due to the extent to 
which air cleaners have been developed, any improvement in cost or 
reliability to the air cleaner is significant. 
Electronic air cleaner cells are constructed by joining air cleaner 
collector sections to end plates of the cells. Previously this was 
accomplished with screws from the end plates into the expansion tubes 
which support the collection plates. For smaller cells, a second method 
was used which consisted of passing a threaded rod through the first end 
plate, the collector expansion tube and, finally, the second end plate. A 
washer and nut was added to secure the assembly. 
Air cleaners manufactured utilizing the method of placing a screw through 
the end plates into the cell expansion tubes have problems with screws 
coming loose due to variations in the required driving torque. The screws 
also come loose during handling or washing. At this time, this method is 
also expensive, as this method of manufacture requires the use of a human 
operator. Further, if the air cleaner cell were to be disassembled, the 
expansion tubes would be irreparable, requiring the air cleaner collection 
cell to be replaced. This is partially due to the fact that once the 
screws are threaded into the expansion tube, removed and replaced in the 
same expansion tube, the screw would not be able to achieve the same 
torque as when originally assembled. 
The most significant problem created through use of the screws is torsional 
stress imparted on the cell expansion tubes by the screws. These torsional 
stresses reduce cell quality by warping the collection plates. The screw 
heads also tend to "walk" or shift on the end plate when tightened, 
placing lateral forces upon the collection plates, also warping the 
collection plates. This is significant as the air cleaner cell has every 
other collection plate charged to 4,075 volts dc. The remaining collection 
plates are grounded. Therefore, if the collection plates are warped, 
arcing may occur between the plates, reducing the effectiveness of the air 
cleaner. 
The second prior art manner of assembly involves the use of a tie rod. This 
method of manufacture consists of passing a threaded rod through the first 
end plate, the cell expansion tube and, finally, through the second end 
plate. The tie rod was fastened in place by adding a washer and a nut. The 
use of a tie rod eliminates some of the problems with torsional stresses 
applied to the device. However, the tie rod is expensive, requires manual 
assembly and is also susceptible to the nuts loosening due to variations 
in the required driving torque, handling and washing. The tie rod is used 
primarily on small air cleaner cells due to the costs of the tie rod 
assembly. The screws impose such a severe torque upon the cell expansion 
tubes that screws are not practical with the smaller cells; the failure 
rate of the smaller cells manufactured with screws being too high. 
However, due to the cost of the tie rod assembly, the tie rods are not 
utilized where the failure rate of the air cleaner cells does not offset 
the costs. 
Examples of electronic air cleaners can be found in U.S. Pat. No. 3,143,403 
by Elmer H. Swensen and in U.S. Pat. No. 3,188,784 by K. M. Nodolf. 
SUMMARY OF THE INVENTION 
In accordance with the invention, a tube having a flared end is inserted 
through the first end plate, then through the collector section expansion 
tube and, finally, through the second end plate. The end of the tube which 
was passed through the second end plate is then flared. 
With this structure there are no torsional forces or lateral forces 
imparted upon the cell expansion tubes and collection plates. This lessens 
the occurrence of warping of the collection plates. An electronic air 
cleaner, in accordance with this invention, has noticeably lower fallout 
rates (failure rates) for the air cleaner collector section.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Screw 5 of FIG. 1 is utilized to fasten the end plates to the air cleaner 
collector section in the "prior art" assembly. Tie rod 10 of FIGS. 2 and 
2a is utilized to fastened the end plates to the air cleaner collection 
section in the "prior art" assembly for smaller cell assemblies. Tie rod 
10 consists of a solid aluminum rod 13 which has its top end coined to a 
flat shape. Bottom end 11 is threaded in order to receive a nut. 
Flare tube 20 of FIG. 3 is utilized for fastening the air cleaner collector 
section 32 for this invention. Flare tube 20 consists of a hollow tube 22 
having a first end 21 which is flared. Flare tube 20 is made out of 
3003-H12 aluminum. The opposing end 25 is the same diameter as the 
remainder of the tube, however, opposing end 25 is later flared during 
assembly. 
FIGS. 4 and 4a depict an air cleaner collector section 32 utilized in the 
electronic air cleaner. Air cleaner collector section 32 consists of high 
voltage or hot plates 30 and low voltage or ground plates 35. The high 
voltage plates 30 and the ground plates 35 are alternated in air cleaner 
collector section 32. In operation, high voltage plates 30 are charged to 
4,075 volts dc, ground plates 35 being grounded or at a zero volt 
potential. For assembly of air cleaner collection section 32, collection 
plates 30 and 35 are alternately placed in a holding fixture (not shown). 
Expansion tubes 40, 41, 42, 43, 44, 45, 46 and 47 are passed through both 
high voltage plates 30 and ground plates 35 and then expanded radially to 
secure plates 30 and 35. Further, high voltage plates 30 are electrically 
connected to expansion tubes 40, 43, 44 and 47 such that high voltage 
plates 30 receive a voltage charge of 4,075 volts dc through expansion 
tubes 40, 43, 44 and 47 during operation. High voltage plates 30 are cut 
away such that expansion tubes 41, 42, 45 and 46 do not come in contact 
with high voltage plates 30. Ground plates 35, conversely, are designed 
such that ground plates 35 are electrically connected to expansion tubes 
41, 42, 45 and 46. However, ground plates 35 are also cut away in such a 
manner that they are not in contact with expansion tubes 40, 43, 44 or 47. 
In this manner, a dc voltage differential is achieved between high voltage 
plates 30 and ground plates 35. The resultant voltage field is utilized to 
trap ionized particles in the air. 
Air cleaner collector section 32 is fastened between two end plates 50 as 
shown in FIGS. 5 and 5a. FIGS. 5 and 5a demonstrates the "prior art" 
methods of fastening end plates 50 to air cleaner collector section 32. 
Air cleaner collector section 32 when fastened by screws 5, have screws 5 
placed through end plates 50 such that screws 5 are screwed into expansion 
tubes 41, 45 and 46. Normally only expansion tubes 41 and 45 (or 42 and 
46) would have screws 5 used to fasten air cleaner collection section 32. 
FIGS. 5 and 5a further demonstrate expansion tube 42 with tie rod 10 
utilized for fastening the air cleaner collector section. As shown in 
FIGS. 5 and 5a tie rod 10 is first passed through a washer 15, through 
first end plate 50, then expansion tube 42 of air cleaner collector 
section 32, and then second end plate 50. When tie rods 10 are used to 
fasten air cleaner collection section 32, expansion tubes 41, 42 and 45 
are used. Tie rod 10 is fastened in place by placing a second washer 15 on 
tie rod 10 and then a nut 14 is torqued onto tie rod 10. 
FIGS. 6 and 6a depict the preferred embodiment of the invention. Flare 
tubes 20 are inserted through a first end plate 50 and expansion tubes 41, 
42, 45 and 46. Although FIGS. 6 and 6a shows expansion tubes 41, 42, 45 
and 46 filled with flare tubes 20, it is possible to use only expansion 
tubes 41 and 45 (or 42 and 46). Flare tube 20 has first end 21 which is 
flared to retain first end plate 50. Flare tube 20 opposing end 25 is 
inserted through end plate 50 and air cleaner collector section 32. A 
second end plate 50 is then placed on air cleaner collector section 32 and 
flare tube 20 is also inserted through second end plate 50. After flare 
tube 20 is inserted through both end plates 50 and the air cleaner 
collector section 32, flare tubes 20 are flared at ends 25 using an 
orbital riveter. An orbital riveter is utilized to prevent buckling of 
flare tube 20 as it is flared. By using an orbital riveter, dimension 
consistency without tight tolerances of the flare tubes is possible. This 
is possible as the orbital riveter continually spins while compressing 
flare tube 20, allowing equal pressure upon the entire flare tube. This 
allows flare tubes 20 to be of slightly varying lengths, as the riveter 
will flare the flare tube 20 until a desired compression of end plates 50 
is obtained upon air cleaner collector section 32. The head for the 
orbital riveter can be obtained from Bracker Corporation of Pittsburgh, 
Pa. 
Flare tubes 20 also add benefits to the air cleaner collector section and 
the method of manufacture. Flare tube 20 provides additional stiffness to 
the assembly by supporting the cell expansion tube through which it 
passes. An additional cost saving advantage is that flare tube 20 can be 
fastened in place using a fully automatic process significantly lowering 
the cost of manufacture. Finally, air cleaner cells can be broken down 
without damaging air cleaner collector section 32 by drilling out flare 
tube 20. Through use of the flare tube it is possible to make a air 
cleaner which is subject to a lower failure rate and has a longer life, as 
a flare tube, unlike the screw and the tie rod, will not come loose.