Spiral wound electrostatic air cleaner and method of assembling

An electrostatic air cleaner collector and/or ionizer section has their oppositely charged elements being formed of single, continuous, electrically conductive elements, spirally wound around insulator rods to jointly define a spiral passage through which air is caused to flow. The collector and ionizer may be assembled separately by such a winding process, or they may contain common insulator rods around which the conductive element of both sections may be simultaneously wound. A conductive rod may be inserted to electrically interconnect the high voltage elements of the respective ionizer and collector sections.

BACKGROUND OF THE INVENTION 
This invention relates generally to electrostatic air cleaning devices and 
more particularly, to an improved cell structure and method of making 
same. 
A typical electrostatic air cleaner cell includes an ionizer section and a 
collector section, both of which include discreet high voltage elements 
interconnected between grounded plates. That is, the ionizer has positive 
wires and negative strips alternately connected, in parallel relationship, 
between the grounded plates. The collector section has installed between 
its grounded plates, alternate high and low voltage plates arranged in 
parallel relationship. This combination of high and low voltage plates and 
wires are typically secured and isolated from one another by a variety of 
insulators, tubes, spacers etc. The finished cells are therefore 
relatively heavy and expensive, both in materials and in labor of 
assembly. 
One problem that is sometimes experienced with conventional cells is that 
of "oil canning", wherein an aluminum plate can be caused to flex or "bow 
out" to one side, thereby reducing the distance from the adjacent, 
oppositely charged plate. This in turn can cause arcing and damage to the 
cell. 
It is therefore an object of the present invention to provide an improved 
electrostatic air cleaner cell structure and method of manufacture. 
Another object of the present invention is the provision in electrostatic 
air cleaner for eliminating the occurrence of "oil canning". 
Yet another object of the present invention is the provision for 
simplifying the structure of an electrostatic air cleaner cell. 
Still another object of the present invention is the provision for reducing 
the weight and the cost of manufacture of an electrostatic air cleaner 
cell. 
Yet another object of the present invention is the provision for an 
electrostatic air cleaner cell which is economical to manufacture and 
effective and efficient in use. 
These objects and other features and advantages become readily apparent 
upon reference to the following description when taken in conjunction with 
the appended drawings. 
SUMMARY OF THE INVENTION 
Briefly, in accordance with one aspect of the invention, the positive and 
negative (or grounded) plates of the collector are formed of a pair of 
intermeshed, spiral elements which are radially spaced and insulated from 
one another such that they jointly define a spiral shaped channel through 
which the air to be cleaned may flow. 
In accordance with another aspect of the invention, the electrostatic air 
cleaner cell is assembled by winding both the positive and negative 
elements, in an intermeshed spiral pattern, around a plurality of 
insulator connector rods which are progressively added as the spiral wraps 
progress radially outwardly. In this manner, the process of winding the 
elements can be easily and efficiently accomplished without interference 
of the rods. Further, the tension in the windings can be maintained so as 
to prevent the oil canning phenomenon which might otherwise occur. 
By yet another aspect of the invention, the collector and ionizer sections 
can be made simultaneously by using rods that project axially beyond the 
axial limits of the collector such that the ionizer wires and strips may 
be spirally wound around the rod extensions in much the same way as the 
collector elements. Again the pair of spirally wound elements define a 
spiral passage through which the air may flow to be ionized. In order to 
electrically interconnect the wires of the ionizer section with the plates 
of like plurality in the collector, a common conductive rod may be 
inserted between the ionizer and the collector sections. 
In the drawings as hereinafter described, a preferred embodiment is 
depicted; however, various modifications and alternate constructions can 
be made thereto without departing from the true spirit and scope of the 
invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, an electrostatic air cleaner cell in accordance 
with the present invention is shown to include an ionizer section 11, and 
a collector section 12, with the two being interconnected in serial flow 
relationship along a central axis 13, along which the flow of air would 
pass as it flows through the cell to be cleaned. 
The framework for the cell includes a bottom plate 14, a middle plate 16, 
and a top plate 17, each of the individual plates being interconnected by 
a plurality of insulator connector rods 18 in a manner to be described 
hereafter. 
Each of the plates 14, 16 and 17 has a generally rectangular peripheral 
framework 19, with generally radially extending ribs 21 leading to a 
central structural portion 22. The plates are made from a stiff, high 
density polypropylene or pressed polyester material which demonstrates 
high electrical insulative properties. The ribs 21 have a plurality of 
openings 23 formed therein for receiving the rods 18 in a manner to be 
described below. 
It should be mentioned that both the structure and the method of the 
present invention is applicable to both the collector and the ionizer 
sections taken individually or in combination. That is, the collector and 
the ionizer may be assembled separately, with either or both using the 
concepts of the present invention, with the two then being interconnected 
to complete the final cell structure. Alternatively, they may be assembled 
simultaneously as a single unit, with both employing the principals of the 
present invention. Such a combined structure is shown in FIGS. 1 and 2. 
Referring now to FIG. 2, the ionizer section 11, which is bounded by middle 
plate 16 and top plate 17, includes a positive ionizer wire 24 and a 
negative ionizer strip 26, with each being wound, in a spiral pattern, 
around a plurality of connector rods 18 so as to intermesh, one within the 
other, to form a completed ionizer section with fixed radial spacing 
between the positive ionizer wire and the negative ionizer strip through 
which air can flow and be ionized. Examples of suitable materials that 
could be used for the positive ionizer wire 24 and the negative ionizer 
strip 26 are 5 mil tungsen wire or 10 mil aluminum foil, respectively. A 
metalized film could also be used for the negative ionizer strip 26. The 
particular manner in which the positive ionizer wire 24 and the negative 
ionizer strip 26 are wound around the rods 18 will be more fully described 
hereinafter. 
Similarly, the collector section 12, which is bounded at its one end by the 
bottom plate 14 and its other by the middle plate 16, is comprised of a 
positive collector plate 27 and a negative collector plate 28, both wound 
in a spiral fashion, such that they intermesh to jointly define spiral 
shaped passages through which the ionized air may flow, with the ionized 
particles then tending to collect on the negative (grounded) collector 
plate 28. A suitable material for use as the collector plates would be a 
10 mil aluminum foil. 
The connector rods 18, which function to interconnect bottom plate 14, 
middle plates 16, and top plate 17, and around which the positive ionizer 
wire 24, the negative ionizer strip 26, the positive collector plate 27 
and the negative collector plate 28 are wound, include the shorter 
collector-only, positive 29 and collector-only, negative 31 rods as well 
as the longer collector/ionizer, positive 32 and the collector/ionizer, 
negative 33 rods. The collector-only rods 29 and 31 extend between the 
bottom and middle plates 14 and 16, respectively, whereas the 
collector/ionizer rods 32 and 33 extend between the bottom plate 14 and 
the top plate 17 to thereby serve as structural elements for both the 
collector section 12 and the ionizer section 11. 
A collector-only positive rod 29, which is identical to a collector only 
negative rod 31 is shown in greater detail in FIG. 3. The rods 29 are made 
of an electrically insulative material such as, for example, an L-3 
STEATITE, which is commercially available from Duco Ceramics Inc.. Indents 
34 and 36 are formed near the respective ends thereof for interconnecting 
with the respective bottom plate 14 and middle plate 16 at the holes 37 
and 38. That is, the rod 29 is pushed through the plates 14 and 16 until 
the edges of the plates 14 and 16, around the holes 37 and 38, snap into 
the indents 34 and 36, respectively. 
Similarly, the collector/ionizer, positive rod 32, which is identical to 
the collector/ionizer, negative rod 33, has indents 39, 41 and 42 which 
are snapped into holes in the respective bottom plate 14, middle plate 16 
and top plate 17. As an alternative structure, the rods may be made from a 
fiberglass, reinforced, polyester "pultrusion" material manufactured by 
Haysite Division of Synthane-Taylor and, rather than using indents, the 
rods may be glued in place. 
In the above description of the ionizer and collector sections, 11 and 12, 
respectively, reference has been made to the positive elements (i.e. the 
positive ionizer wire and the positive collector plate) and to the 
negative elements (i.e. the ionizer strip and the negative collector 
plate). It should be mentioned that these terms are used in a relative 
sense, in that the positive elements are more positive than the negative 
elements. That is, the negative elements are preferably at ground, whereas 
the positive elements are at a high potential level, such as 8,000 volts. 
Thus, the term "negative" is meant to be construed in the broader sense 
wherever used herein. Further, it should be mentioned that the positive 
and negative sections could be reversed when negative ionization is 
employed. 
For purposes of describing the method of assembly, reference is now made to 
FIGS. 5-8. First, the bottom, middle and top spacer plates 14, 16 and 17 
are axially aligned as shown in FIG. 2 and at block 43 of FIG. 5. The most 
central connecting rods 18 are then installed between the plates such that 
the plates are snapped into place (block 44). Next, the assembly is placed 
in proper alignment with various spools of material to be used for winding 
the various positive and negative elements on to the unit. This is shown 
in FIG. 6 wherein the rods corresponding to the ionizer section 11 are 
placed in the plane of the spool 46 of ionizer wire and the spool 47 of 
ionizer strip material. Similarly, the portion of the rods corresponding 
to the collector section is aligned in the plane of a pair of spools 48 
and 49 of aluminum foil. The ends of the material from each of the spools 
is then attached to the appropriate rod in preparation for the subsequent 
winding process. This attachment may be accomplished by any of a variety 
of methods such as mechanical fasteners, rivets, welding, crimping, etc. 
That is, the ends of the material from spools 48 and 49 are connected to 
the rods 29 and 31 corresponding to the collector positive and collector 
negative plates, respectively. Similarly, the material from the wire spool 
46 and the aluminum foil spool 47 are connected to the ionizer portion of 
the positive rod 32 and to the ionizer portion of the negative rod 33 
respectively. These steps are recited in block 51 of FIG. 5. The winding 
process can now be initiated by rotating the assembly as indicated in FIG. 
6, with connecting rods 18 being progressively added in a outwardly 
spiraling pattern, such that the proper spacing is maintained between the 
opposite polarity elements. Further, during this winding process the 
proper tension is maintained in the material being wound such that it is 
relatively taut, and therefore the subsequent occurrence of "oil canning" 
can be avoided. This step is shown in block 52, FIG. 5. At the the end of 
the winding process, the ionizer section 11 and the collector section 12 
will appear as shown in FIGS. 7 and 8, respectively. It is then necessary 
to connect each of the positive and negative elements to their most 
radially outer rod. That is, in the ionizer section 11, the positive 
ionizer wire 24 is secured to the rod 53, and the negative ionizer strip 
26 is secured to the rod 54. The material from the spools 46 and 47 is 
then severed and the spools are prepared for the next unit. In a similar 
manner, the end of the positive collector plate 27 is secured to the 
radially outer rod 56 of the collective section, and the outer end of the 
negative collector plate 28 is secured to radially outer rod 57 of the 
collector section 12. The material from the spools 48 and 49 is then 
severed to remove the completed cell. 
With such an integral structure, wherein the collector and ionizer are 
assembled simultaneously and as a single unit, it is desirable that the 
negative ionizer wire 24 of the ionizer section be at the same potential 
as the negative collector plate 27 of the collector. The same may be true 
for the respective positive sections. Further, it is desirable that this 
be accomplished with a simple electrical connection. This can be easily 
accomplished with the present invention by a single connector rod which, 
instead of being made of insulative material, is made of a conductive 
material such as copper or aluminum. For this purpose, such a conductive 
rod may be placed at any position within the unit wherein it makes 
electrical contact with both the negative (or positive) ionizer wire 24 
and the negative (or positive) collector plate 27. The high voltage power 
can then be connected to either the ionizer 11 or the collector 12 and it 
will be automatically connected to the other. This step is shown in block 
58 of FIG. 5. 
While the combination ionizer/collector has been shown and described as 
having three plates, it should be mentioned that the top plate could be 
eliminated such that the relatively short ionizer rods are simply 
cantilevered out from the second plate. 
It will be seen in FIGS. 7 and 8 that, whereas the pattern of the positive 
and the negative elements are somewhat rectangular in form, they are also 
formed in a spiral pattern in that they start as small rectangles and 
become progressively larger toward the outer side. It should be recognized 
that this pattern may be varied substantially while remaining within the 
general scope contemplated by this invention. 
While the invention has been described with some specificity as shown in 
the preferred embodiment, it will be recognized by those skilled in the 
art that various modifications and alternate constructions can be made 
thereto while remaining within scope and spirit of the present invention.