Air filter construction

A plurality of separate V-shaped wire mesh members are arranged and connected in side-by-side relationship to provide a plurality of V-shaped cells across an air stream. A W-shaped retainer or connector formed of perforated sheet metal has outer, downstream facing trackways which receive side edges of the wire mesh members, and a central, upstream facing trackway which receives and retains the free edges of V-shaped filter media bags which are inserted into the V-shaped cells overlying the wire mesh. A stabilizer bar extends across and attaches to the exposed adjoining edges of the V-cells to support the cells in proper relation and retain the filter media in place.

BACKGROUND OF THE INVENTION 
In the construction of V-cell air filters a sheet of relatively heavy 
gauge, wire mesh or screen is folded in a V-shape or series of adjacent 
V-shapes to form a supporting frame with a plurality of such "cells" for 
supporting an overlying fibrous filter media. Most prior art filters of 
this type also include a rectangular metal frame to support the edges of 
the wire screen in position across the air flow conduit, and triangular 
sheet metal caps across the open tops and bottoms of the V-cells to close 
off and stabilize the upper and lower ends of the wire mesh frame. A 
filter cell of this type is generally illustrated and described in U.S. 
Pat. No. 3,984,221 although the claims of such patent are primarily 
directed to an improved retaining strip for the filter media of such 
filters. 
Two significant problems have existed in the abovementioned and other 
similar prior designs of V-cell filters. One problem is caused by the 
retainers and frame areas in prior devices, which are dead areas as far as 
the passage of air is concerned. In a high velocity system (approximately 
1500 fpm) such "dead areas" become a limiting component by considerably 
increasing the size and capacity of the fan motors required to maintain 
the even flow of air therethrough. This increased fan size is required 
because in such prior systems the dead areas led to a pressure drop of 1.5 
inches of mercury at air velocities of 1500 fpm. Consequently the 
increased horsepower requirements for the fan motors increase the energy 
requirements to operate the system, making the system significantly more 
expensive to purchase and maintain. This problem is more acute than may 
first seem, because fan motor size varies according to the cube of the 
ratio of pressure drops. For example doubling the pressure drop requires a 
fan motor increase of eight-fold. 
A second problem in prior V-cell filters may also be attributed to the 
substantially dead or blocked areas, and the need to increase the 
effective areas of exposed filtering media through which air passes to 
maximize filter efficiency. The effective filter area is measured by the 
ratio of filter surface area to conduit cross-sectional area. Prior 
attempts at V-cell filters have been able to achieve such a ratio of only 
about 7.5 to 1. A prior attempt to locate a common solution to the 
undesirable high pressure drop and to the need for maximizing filter 
surface area resulted in the removal of considerable portions of the 
retainers and sheet metal frame surface in the cells, and replacing these 
areas with fibrous filter media. This solution utilized a plurality of cut 
wire mesh sections so connected as to form a substantially open V-cell 
wire mesh arrangement. The filter media was laid into the V-cell and 
clamps in the form of two plates bolted to the screen applied at the 
forward or upstream edges to hold the media in place. 
The aforementioned approach was somewhat effective to significantly reduce 
the pressure drop and maximize effective filter area. However, while the 
improved V-cell design improved these two important problems, new problems 
in attaching the new filter media to the frame and in stabilizing the cell 
to decrease vibration and noise were created. The bag-like filter media 
was difficult for maintenance personnel to attach and therefore the bags 
were often incorrectly replaced resulting in poor filtration. 
Additionally, the excess time spent changing the bags significantly 
increased system down time. 
It is to an improved means for connecting the separate wire mesh V-cells 
and for attaching filter media thereto that the present invention is 
directed. 
SUMMARY OF THE INVENTION 
The present invention is directed to the elimination of the above-discussed 
problems by providing an improved connecting element for joining the 
adjacent edges of the V-cells including a means for assembling the fibrous 
filter media thereto. The improved media connecting means is so fabricated 
as to engage the lateral upstream edges of adjacent wire mesh V-cells 
between spaced outer grooves or tracks and also to receive and retain in 
an intermediate groove or track the free side edges of adjacent fibrous 
filter bags inserted into adjoining cells. 
The connecting element is fabricated from a thin strip of perforated sheet 
metal which is bent into a W-configuration having three elongated, 
vertically extending trackways, the central one preferably facing upstream 
and the outer ones preferably facing downstream. In use each of the outer 
trackways, receives one lateral edge of two adjacent wire mesh V-cells. 
The center trackway, which faces in the opposite or upstream direction, 
receives one side edge of each of the overlying filter media bags from the 
adjacent cells and retains the edges therein. 
Each of the three trackways which comprise the media connecting element is 
a longitudinal extension including two sidewalls and an adjoining, rounded 
rear wall. The side walls of the center track and the inner wall of each 
outside track are common to each other and again, as stated above, the 
center trackway faces in a direction opposite to that of the outer tracks. 
To erect the filter cell the prescribed number of V-shaped wire mesh cells 
are placed side by side, with the open ends all preferably facing upstream 
and the adjacent lateral edges in alignment. The connecting elements are 
emplaced by merely slipping one lateral edge of the V-cells into one of 
the outer trackways and securing it, and the corresponding edge of the 
adjacent V-cell into the other of the outer trackways and securing it. A 
filter media bag is then inserted inside each of the V-cells, tied in 
place at the rear or apex of the V, and the opposite side edges stretched 
around the outer walls of the connecting member and slipped into place in 
the center trackway. A simple blunt-edged tool such as a paperwheel may be 
used to slip the edge into the track where it will be held in place by 
friction. The top and bottom edges of the bag may be connected to the 
cover or base in any conventional manner. 
A further means for holding the media edges in place, and for minimizing 
vibration of the frames during operation of the system is a horizontally 
mounted stabilizer bar. The stabilizer is mounted horizontally across the 
front of the upstream side of the filter cell by means of clips on the bar 
which snap into place over each of the assembled media connector elements. 
The bar is positioned approximately along the center portion of the cell 
between the top and bottom and acts as a stabilizer against vibration and 
shifting of the individual V-cells. The aforementioned clips are welded or 
otherwise fastened to the bar at spaced intervals therealong corresponding 
to the widths of the V-cells. The clips will expand to slip over the 
connecting elements and the media and by means of a spring-like tension 
are held securely in place. 
It is therefore an object of the present invention to provide an improved 
construction for V-cell filters having fibrous filter media bags mounted 
to an underlying open framework of wire mesh V-cells. 
It is an object of the present invention to provide a V-cell filter frame 
and means for assembly thereof which will improve air flow through the 
filter cell. 
It is a further object of the present invention to provide a connecting 
element for V-cell filters which joins adjacent wire mesh backing cells 
and the filter media thereto and permits the easy removal and replacement 
of the filter media during maintenance.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Turning to FIG. 1, a V-cell air filter unit F according to the present 
invention is illustrated and includes generally a plurality of V-shaped, 
wire mesh cells 10, top wall or frame cover C and bottom wall C', end cell 
caps or stiffeners 20, the unique media connecting element 30, and a 
stabilizer bar 40. The fibrous filter medium which is inserted into each 
cell and completes the working unit is not illustrated in this view. 
However, the preferred bag-type filter 50 is shown in FIG. 4. 
In more detail, the components as shown, when assembled form a multiple, 
V-cell air filtering unit F of the type which is positioned within a 
walled conduit in the path of on-coming impure air stream to cleanse the 
air before it is recirculated or exhausted into the atmosphere. The top 
and bottom walls C,C' are sheet metal and are either connected to or 
representative of the walls of the air flow conduit within which the cell 
is placed. A portion of one side wall W is illustrated in FIG. 1, it being 
understood that a similar wall exists on the other side of the conduit 
even though not shown. The path of air flow is parallel to these walls 
C,C' moving in the direction of the arrows in FIG. 1. 
Each section or cell 10 is generally made from a substantially rectangular 
piece of heavy gauge wire mesh or screening which is folded into a V-shape 
to form a chamber 15 with walls which converge in a downstream direction. 
A unit F may include two or more cells 15. In the illustrated embodiment 
two cells are shown for purposes of illustration, however, five or six 
cells is the more conventional situation. 
After each section or cell 10 is formed, the cell end caps 20 are emplaced, 
primarily for stability. The caps 20 are fabricated from relatively thin 
sheet metal and are cut substantially in a triangular or truncated shape. 
They include a pair of tabs 21 on each side edge which are folded or bent 
around selected ones of the ribs on or near the top edges 17 and bottom 
edges 17' of the wire screening to cap the ends of the cells. The purpose 
of caps 20 is to stabilize and maintain the screen mesh in the 
V-formation. A cap 20, as illustrated, is preferably placed on each end 
17,17' of the individual cell 15, but, if desired, a single, centrally 
located, similarly shaped support may suffice. 
At this point the cells 10 are ready for positioning and emplacement of the 
unique connector elements 30 which join the adjacent edges of adjacent 
cells 10 and provide a retainer for the fibrous filter media bags shown in 
FIG. 4. 
The connector element 30 itself is more clearly illustrated in FIG. 3 while 
its relationship to other unit F components is best shown in FIG. 2. The 
W-or M-shaped element includes a pair of outer, downstream facing 
trackways 32,32', and an inner, upstream facing trackway 34 between the 
outer trackways 32,32'. Each of the trackways 32,32' are formd by an outer 
sidewall 33 and an inner sidewall 35. The inner track 34 is formed between 
adjacent inner walls 35. Each trackway 32,32' and 34 includes a rounded 
rear wall 37. The element 30 is actually formed by reverse bending a sheet 
of perforated metal at three points. Widthwise the outer tracks are 
preferably of such a width as to frictionally engage the wire mesh edges 
16, while inner track 34 is of a width less than a double thickness of the 
filter media 50 causing the media to be compressed as it is inserted into 
trackway 34. 
Looking at FIG. 2, one can see the element 30 is placed over and connects 
two adjacent cells by slipping one cell edge 16 into each of the outer 
tracks 32,32'. If the fit is not tight enough, connector elements 30 may 
be secured to the wire mesh by using ring shaped hooks 25 which pass 
through the mesh and a perforation, then are closed by pliers. 
The filter media, preferably in the forms of bags 50, are placed into the 
cells, with the sides 51 of each bag wrapping around the outer sidewalls 
33 of the connecting element 30 and being inserted into the inner trackway 
34. Using a small blunt-edged tool or wheel the edges 52 are more easily 
pushed into and held in the track 34. The rear edge of each bag is then 
secured to the apex of the screen cell 10 in a conventional manner as by 
tying. 
The stabilizer bar 40 is then snapped on to the unit F as shown in FIGS. 1 
and 2. The horizontally mounted bar 40 illustrated in FIGS. 1 and 2 
includes a bar portion 41 and a plurality of recesses 42 positioned at 
spaced intervals therealong to further support and secure the media to the 
connector elements 30. When the bar 40 is emplaced on the unit F the 
connecting elements 30 fit into recesses 42, and are held securely therein 
by a friction fit. 
The stabilizer bar 40 in addition to helping maintain the filter media 
edges in place, stabilizes the frames 10 to decrease vibration and rattle 
when the system is operating. It should be noted that the bar 40 is of 
such slender, elongated design that, when placed in the path of air at the 
front of Unit F, it does not impede the flow of air therethrough. 
From the above description it is apparent that an entire unit F may be 
constructed without the use of rivets and/or screws. It is particularly 
important that the connecting element 30 and stabilizer 40 may be merely 
slipped into frictional engagement with the V-cells 10 and with each 
other. Therefore maintenance personnel may easily remove those components 
and quickly replace the filter media bag 50. The bag 50 includes a tie 53 
along the rear seam which is tied to the wire mesh at the apex of the 
cell. System down time is significantly reduced. 
While a preferred embodiment has been discussed herein it should be 
understood that changes and alterations may be made without affecting the 
scope of the invention as claimed below.