Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2001-12-17
2004-06-01
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S210000, C156S245000, C156S267000, C156S292000
Reexamination Certificate
active
06743317
ABSTRACT:
TECHNICAL FIELD
The present invention relates to fluid filtering devices, more particularly, devices constructed using generally corrugated filter media in combination with flat media, hereafter, referred to as a ‘Honeycomb designed’ filtering element.
BACKGROUND OF THE INVENTION
There exists an ongoing effort in the filtration industry to maximize filter life while simultaneously trying to reduce filter size, weight, and costs. These efforts are accomplished in part by maximizing the amount of media surface area which reduces pressure drop across the filter and prolongs its useful life. It is also desirable for the housing structure supporting the filter to be of a simplified design or even eliminated entirely. All of these factors, including the methods used for manufacturing the filter element, must be considered for maintaining low production costs.
Pleated paper filters with rigid housings have long been the industry standard for most filtering applications. These filters, however, generally require relatively expensive hardware such as centertubes and endcaps and have relatively low filter densities and load capacities.
Attempts have been made to increase the filter density and load capacity of filter elements. This has included the development of orthogonal flow filters, more commonly referred to as “Honeycomb” filters.
FIGS. 1-3
depict a honeycomb filter and segments thereof which can be made from prior art methods.
FIG. 1
illustrates a cylindrical filtering element
10
. It is noted that fluid intake in this device is shown by arrows
16
and filtered fluids exit from the bottom end as shown by arrows
18
. The filter element
10
typically includes an impervious barrier element
24
which is cylindrical in shape so as to be sized to receive the body of element
10
within. The purpose of barrier
24
is primarily to prevent entry of uncleaned fluid via the sidewalls of the element, thereby directing it in the flow shown by arrows
16
.
FIG. 2
shows a fragmentary view of a portion of the top end of filtering element
10
. Fluid
16
enters the filter through openings such as
38
and enter flutes which run essentially the length of element
10
but are plugged on the opposite end. Plugs
39
prevent entry of fluid
16
.
As can be seen in
FIG. 3
, filtering occurs within element
10
due to alternating ends of adjacent flutes being sealed to prevent fluid transfer thereby forcing all fluid to pass through the media in order to exit the element. One possible flow pattern is shown wherein fluid
16
enters open flute
50
on the inlet of filter
10
, is filtered across corrugated media layer
20
and exits via opening
32
on the outlet end of the filter. Alternatively, fluid
16
may be filtered sideways across the flat media layer
26
and exit via opening
34
at the outlet end of the filter. As fluids pass through a media wall, filtering occurs and particulate matter becomes lodged within the media itself. Because this loading will increase the face velocity at that point, particulate matter will tend to be collected at other points along the walls thereby evenly distributing the particulate matter throughout the filter until it is fully loaded.
This basic design for honeycomb filters is also well documented in the prior art. One such reference is U.S. Pat. No. 2,322,548 issued to Sigmund wherein an impervious board matrix separates a flat filtering sheet which is rolled into a cylindrical shape. Filtering occurs when the fluid entering the intake side must cross through the inner walls at a right angle to exit by the outlet side.
U.S. Pat. No. 2,210,397 issued to Dreiss uses a similar filtering scheme by carefully aligning two sheets of substantially flat filter paper with a specially designed top and bottom plates to direct airflow. U.S. Pat. No. 3,020,977 issued to Huppke et. al. introduces the additional feature of corrugated material between flat sheets, although the corrugated material performs no filtering function, but merely acts as a spacer. Likewise, U.S. Pat. No. 2,397,759 issued to Sigmund employs a corrugated member as a spacer.
None of the aforementioned references are able to achieve the high filtering density desired because of the use of construction materials which are merely structural, rather than material suited for performing both structural and performing a filtering function.
U.S. Pat. No. 4,410,427 issued to Wydeven was able to achieve the high filtering density desired in an orthogonal flow filter because of the use of materials which performed both a structural and a filtering function. Since Wydeven, numerous patents have been issued acknowledging the benefits of orthogonal flow filtering occurring from the use of honeycomb designed filters which include increased filter performance, reduced weight and overall outer dimension, as well as lower manufacturing costs.
Honeycomb filters provide benefits over other filter designs in certain applications. These benefits include: greater life expectancy, at equal efficiency; fixed geometry—no pleat bunching; more media per unit volume of filter; lower materials cost, for many applications; simple construction; and product differentiation.
Presently, honeycomb structures are being used throughout industry; offering advantages in many “non-filtering” applications. Some of the areas where product advantages are currently being obtained as a result of the honeycomb design are: 1) Automotive Catalytic Converters; 2) Structural Components; 3) Packaging and Container Materials; 4) Heat Exchangers; 5) Shock Absorbing Materials; and, 6) Aerospace Structural Components.
Prior Art Method of Producing Honeycomb designed Filter Elements
Basically, round honeycomb filters FIG.
1
and panel honeycomb filters
FIG. 12
are produced by corrugating filter media. The honeycomb filter comprises a corrugated filter media sandwiched between flat sheets of filter media on either side.
As described earlier and depicted in
FIG. 1
, round honeycomb filter elements comprise one flat sheet and one sheet of corrugated media layer positioned on top of the flat sheet, adhesively connected thereto and which forms a sheet of filter media which is subsequently rolled to form the filter element. For panel honeycomb filter elements, alternating layers of corrugated filter media and flat sheets are utilized, stacked on top of one another.
As defined here, “primary flute” is the interior space between the corrugated media and first contact with the flat-sheet media. Prior art shows that the primary flutes are formed and sealed during the corrugating process.
As defined here, “secondary flute” is the interior space between the corrugated media and contact with flat-sheet media on the opposing side of the corrugated media. Prior art shows that the secondary flutes are formed and sealed during assembly of the filter element.
Use of the terms “primary” and “secondary” do not attempt to distinguish importance; the terms are merely used to describe one set of flutes from the other set.
The terms “primary seals” and “secondary seals” are used in the specification. These terms do not distinguish the importance of one seal over the other. Rather, primary seals refer to the seals present to plug the primary flutes and secondary seals refer to the seals present to plug the secondary flutes.
Problems and Limitations Associated with using Current State of the Art Sealing Methods
Although, the previous patents cited claim various benefits, all are constructed using the same basic technology. Little attention has been given to reducing manufacturing costs or developing new, more efficient, methods of production.
For example, the same method of sealing the filter media has been used, beginning with U.S. Pat. No. 2,599,604 issued to Bauer et. al. in June of 1952 and has continued to be described in one of the most recent patents, U.S. Pat. No. 6,235,195 issued to Tokar in May of 2001. As is described in the prior art, the basic sealing method requires that a bead of sealant be applied to the filter media, to seal the secondary flutes, as the
Aftergut Jeff H.
Corcoran Gladys
Michael & Best & Friedrich LLP
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