U.S. patent application number 12/114931 was filed with the patent office on 2008-08-28 for method for making filter element.
This patent application is currently assigned to Fleetguard, Inc., an Indiana corporation. Invention is credited to Jim L. Alonzo, Michael J. Connor, Kelly Ann Detra, Mark V. Holzmann, Chirag D. Parikh, Gary L. Rickle, Gregory J. Schoenmann, Barry M. Verdegan.
Application Number | 20080203614 12/114931 |
Document ID | / |
Family ID | 36371518 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080203614 |
Kind Code |
A1 |
Holzmann; Mark V. ; et
al. |
August 28, 2008 |
Method for Making Filter Element
Abstract
A filter includes a filter element formed of filter media, and a
plastic framework molded and bonded to and structurally supporting
the filter media. One embodiment desirably provides a two-component
assembly consisting solely of two components, namely the filter
media and the plastic framework molded thereon. In a further
embodiment, the plastic framework includes a resilient seal
integrally molded therewith and of the same plastic material
thereof, eliminating a separate component for the seal. In a
further embodiment, a filter combination includes a primary filter
element and a secondary filter element. In a further embodiment, a
resilient integrally molded seal is provided.
Inventors: |
Holzmann; Mark V.;
(Stoughton, WI) ; Detra; Kelly Ann; (Brooklyn,
WI) ; Alonzo; Jim L.; (Sun Prairie, WI) ;
Parikh; Chirag D.; (Madison, WI) ; Schoenmann;
Gregory J.; (Stoughton, WI) ; Connor; Michael J.;
(Stoughton, WI) ; Rickle; Gary L.; (Warton,
OH) ; Verdegan; Barry M.; (Stoughton, WI) |
Correspondence
Address: |
MICHAEL E. TAKEN;Andrus, Sceales, Starke & Sawall
Suite 1100, 100 East Wisconsin Avenue
Milwaukee
WI
53202
US
|
Assignee: |
Fleetguard, Inc., an Indiana
corporation
Nashville
TN
|
Family ID: |
36371518 |
Appl. No.: |
12/114931 |
Filed: |
May 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10997257 |
Nov 24, 2004 |
|
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|
12114931 |
|
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Current U.S.
Class: |
264/257 |
Current CPC
Class: |
B01D 46/521 20130101;
Y10S 210/17 20130101; B01D 2265/06 20130101; B01D 46/0005 20130101;
B01D 2265/04 20130101; B01D 46/2411 20130101; B01D 46/0024
20130101 |
Class at
Publication: |
264/257 |
International
Class: |
B27N 5/00 20060101
B27N005/00 |
Claims
1-51. (canceled)
52. A method for making a filter element comprising providing
filter media composed of fibers, overmolding a plastic framework to
said filter media to structurally support said filter media, said
framework comprising a rib network comprising a plurality of ribs,
selecting the material of said framework from a family chemically
compatible with the material of said fibers, chemically bonding
said ribs of said framework to said filter media during said
overmolding of said framework, entangling the plastic material of
said ribs of said framework to some of said fibers of said filter
media during said overmolding of said framework to additionally
mechanically bond said ribs of said framework to said filter media,
to both chemically and mechanically bond said ribs of said
framework to said filter media.
53. The method according to claim 52 comprising providing said
filter element as an annular filter element extending axially along
an axis between distally opposite first and second axial ends,
overmolding said framework to extend axially along said axis
between distally opposite first and second axial ends at respective
said first and second axial ends of said filter element.
54. The method according to claim 53 comprising overmolding said
framework to have an outer peripheral surface at said first end of
said framework having a resilient seal integrally overmolded
therewith.
55. The method according to claim 54 comprising overmolding said
seal and said ribs of the same plastic material as said
framework.
56. The method according to claim 54 comprising overmolding said
seal to form at least one flexible annular flange extending
obliquely relative to said axis and radially deflectable relative
to said axis.
57. The method according to claim 56 comprising overmolding said
framework to have a plurality of axial ribs extending axially
between said first and second axial ends of said framework, and to
have a plurality of trusses at said first axial end of said
framework extending radially between said axial ribs and said
annular flange providing said seal.
58. The method according to claim 53 comprising overmolding said
framework to have a plurality of arcuate ribs extending laterally
relative to the axial extension of said framework.
59. The method according to claim 53 comprising overmolding said
framework to have a plurality of axial ribs extending axially
between first and second axial ends of said framework, and a
plurality of arcuate ribs extending laterally between said axial
ribs.
60. The method according to claim 52 comprising providing said
filter element as an annular filter element extending axially along
an axis between distally opposite first and second axial ends and
having a hollow interior, providing said filter media with an
interior facing said hollow interior, and an exterior facing away
from said hollow interior, overmolding said framework to form a
first plastic frame along said exterior of said filter media, and
to form a second plastic frame along said interior of said filter
media, overmolding said framework to form said first frame to
provide a first rib network comprising a first set of a plurality
of ribs extending along said exterior of said filter media and
overmolded thereto, and overmolding said framework to form said
second frame to provide a second rib network comprising a second
set of a plurality of ribs extending along said interior of said
filter media and overmolded thereto, to sandwich said filter media
between said first and second sets of ribs on opposite exterior and
interior sides of said filter media and overmolded bonded
respectively thereto.
61. The method according to claim 60 comprising overmolding said
framework to extend axially along said axis between distally
opposite first and second axial ends at respective first and second
axial ends of said filter element, and overmolding said framework
to form an integral connection between said first and second frames
at at least one of said first and second axial ends.
Description
BACKGROUND AND SUMMARY
[0001] The invention relates to filters, and more particularly to a
high efficiency, low restriction, cost effective filter.
[0002] There is continuing demand for fluid filters exhibiting high
efficiency and low restriction at reduced cost. The present
invention addresses and solves this need in a simple and effective
manner.
[0003] In one desirable option, an incinerable and/or recyclable
filter is provided, enabling green label product designation, which
is significant in various markets.
BRIEF DESCRIPTION OF THE DRAWING
[0004] FIG. 1 is a perspective view of a filter element constructed
in accordance with the invention.
[0005] FIG. 2 is an enlarged view of a portion of FIG. 1.
[0006] FIG. 3 is a side view partially in section of a filter
combination in accordance with the invention.
[0007] FIG. 4 is a schematic end view of an alternate embodiment of
a filter element in accordance with the invention.
[0008] FIG. 5 is like FIG. 4 and shows another embodiment.
DETAILED DESCRIPTION
[0009] FIG. 1 shows a filter 10 having an annular filter element 12
with a hollow interior 13 and extending axially along an axis 14
between distally opposite first and second axial ends 16 and 18.
The filter element includes filter media 20, preferably high
efficiency, low restriction non-pleated non-woven synthetic filter
media, to be described, and a plastic framework 21 molded and
bonded to and structurally supporting filter media 20. Filter media
20 has an exterior 20a facing exteriorly away from hollow interior
13, and has an interior 20b facing inwardly toward hollow interior
13, as shown at the cut-away portions of FIGS. 1, 2. Framework 21
is preferably provided by an external plastic frame 22a which
includes a rib network 24a having a plurality of interconnected
ribs extending along the exterior 20a of filter media 20 and bonded
thereto, to be described. Rib network 24a includes arcuate ribs
such as 26a extending laterally relative to axis 14 and providing
the filter media with torsional loading resistance, each of the
arcuate ribs being bonded to the filter media. Rib network 24a
includes a plurality of axially extending axial ribs such as 28a
providing the filter media with columnar compressive loading
resistance, each of the axial ribs being bonded to the filter
media. Ribs 28a extend along axis 14 and are preferably tapered
relative thereto to provide a frusto-conical filter element.
Framework 21 is also preferably provided by an internal plastic
frame 22b which includes a rib network 24b having a plurality of
ribs extending along the interior 20b of filter media 20 and bonded
thereto. Rib network 24b includes a plurality of axially extending
axial ribs such as 28b providing the filter media with columnar
compressive loading resistance, each of the axial ribs being bonded
to the filter media. Ribs 28b extend parallel to ribs 28a. Inner
rib network 24b includes only axial ribs 28b, but may include
partial arcuate ribs such as 26b which do not extend fully
arcuately between adjacent axial ribs 28b but instead have a
partial arcuate extension formed during mold flow. The outer and
inner rib networks 24a, 24b have open areas such as 30
substantially larger than the area of the ribs, for reduced
restriction, and reducing structural blockage.
[0010] Frame 22a of framework 21 is along the exterior 20a of
filter media 20. Frame 22b of framework 21 is along the interior
20b of filter media 20. Filter media 20 is preferably sandwiched
between the noted exterior and interior sets of ribs on opposite
exterior and interior sides 20a, 20b thereof and bonded
respectively thereto. In one embodiment, the filter is an
outside-in filter wherein fluid to be filtered flows laterally
inwardly through the filter media as shown at arrows 32 into the
hollow interior of the filter, and then the clean filtered air
flows axially rightwardly in FIG. 1 as shown at arrow 34. The noted
bonding and rib structure prevents collapse of filter media 20,
which is desirable in high pressure and/or high vacuum situations,
and in other applications and conditions where desired, for example
severe conditions in an internal combustion engine intake air
filtering application involving wet dirty fully loaded combustion
intake air. The outer frame protects the filter media from damage
during installation. The inner frame prevents media collapse under
flow conditions. Both the outer and inner frames provide torsional
and compressive strength for installation. The filter may also be
used in inside-out applications where the direction of fluid flow
is opposite to that noted above, in which embodiment the outer
frame prevents media collapse under flow conditions. By bonding the
media to the framework, the torsional strength is increased, which
helps maintain element integrity during installation.
[0011] Ribs 26a, 26b, 28a, 28b are bonded to filter media 20 by at
least one of, and preferably both of, a) a chemical bond and b) a
mechanical bond. Filter media 20 is composed of material selected
from the group consisting of synthetic, glass, cellulose, ceramic,
carbon, and metallic material. In a preferred embodiment, in
combination each of framework 21 and filter media 20 is composed of
material selected from the group consisting of organic, synthetic,
and polymeric material selected such that filter element 12 is
incinerable. In a further embodiment, each of framework 21 and
filter media 20 is composed of thermoplastic material, and further
preferably in combination the material of framework 21 and the
material of filter media 20 are of the same thermoplastic recycling
class such that filter element 12 is recyclable. Further in the
preferred embodiment, filter media 20 is composed of fibers, and
the material of framework 21 is selected from a family chemically
compatible with the material of the fibers to chemically bond ribs
26a, 26b, 28a, 28b of framework 21 to filter media 20, and also
such that the plastic material of the ribs entangles some of the
media fibers to additionally mechanically bond the ribs of the
framework to the filter media, such that the ribs of the framework
are both chemically and mechanically bonded to filter media 20. In
one embodiment, filter media 20 is provided by polyester fibers,
and the material of framework 21 is selected from the group
consisting of polyester, polypropylene, and resin. In one
embodiment, the material of framework 21 is polyester selected from
the same polymeric family as the noted polyester fibers of filter
media 20 to chemically bond ribs 26a, 26b, 28a, 28b of framework 21
to filter media 20, and also such that the polyester plastic of
ribs 26a, 26b, 28a, 28b of the framework entangles some of the
polyester media fibers to additionally mechanically bond ribs 26a,
26b, 28a, 28b of the framework to the filter media 20, such that
ribs 26a, 26b, 28a, 28b are both chemically and mechanically bonded
to filter media 20. In one embodiment, the material of framework 21
is polyester with glass reinforcement. In another embodiment, the
material of framework 21 is polypropylene, and the polypropylene
plastic of ribs 26a, 26b, 28a, 28b of the framework entangles some
of the polyester media fibers to mechanically bond plastic
framework 21 to filter media 20. In one embodiment, the framework
material is polypropylene with glass reinforcement. In another
embodiment, the framework material is polypropylene with talc
reinforcement. In a further embodiment, the material of framework
21 is a plastic resin.
[0012] In further preferred embodiments, the material of filter
media 20 is PET (polyethyleneterephthalate) non-woven polyester.
The material of framework 21 is preferably chosen from two
different plastic families. In the first family, the material of
framework 21 is that known under the tradename RYNITE 415HP-BLACK,
DuPont Rynite PET Polyester. This type of formulation, involving
15% glass reinforcement with a toughener added in the formulation,
was selected because it provides the same polymeric family to be
melt bonded during injection molding of the framework to provide a
PET plastic to PET media bond, resulting in a more robust
structural construction including between media fibers and an
integrally molded rib network 24a, 24b and because such polymeric
bond also provides some plastic working its way through the fibers
of the filter media and providing a mechanical bond as well. This
selection was also made because the enhanced robustness provides
additional vacuum resistance under severe conditions, including a
wet dirty fully loaded primary filter failure when the present
filter is used as a secondary filter in combination, to be
described. This selection was also made because the enhanced
robustness provides additional torsional loading resistance
including under severe conditions including loading and unloading
during service. This selection was also made because the enhanced
robustness provides additional columnar collapse buckling
resistance under severe service conditions, including installation
with highly compressive loads. This selection was also made because
it provides more heat resistance than polypropylene. In the second
family, 20% glass-filled or 30% talc-filled polypropylene is
selected, with a formulation involving 20% glass reinforcement with
a toughener added in the formulation. This selection provides more
economical pricing. This selection also provides a dissimilar
polymeric family to be mechanically melt bonded via polymer chain
entanglement amongst the filter media fibers during the injection
molding sequence during molding of framework 21 to provide a
polypropylene plastic to PET filter media mechanical bond. This
results in a robust structural construction between PET filter
media fibers and the integrally molded rib network 24. The
remaining reasons for this selection are similar to those above
indicated for the first noted family, except that this second
family is preferably not used in hot environments above about
180.degree. F. because the plastic of the framework may deflect
more easily under loads. Other resins may be used, such as nylon,
ABS (acrylonitrile/butadiene/styrene), PPS (polyphenylene sulfide),
and the like.
[0013] Framework 21 extends axially along axis 14 between distally
opposite first and second axial ends 36 and 38 at the noted
respective first and second axial ends of the filter element.
Framework 21 at the noted ribs is molded to and bonded to filter
media 20 along the axial extension thereof. The noted first end 36
of the framework has an outer peripheral surface 40 having one or
more resilient seals 42, FIGS. 1, 2, overmolded therewith. Seals 42
and ribs 26a, 26b, 28a, 28b are the same plastic material of the
framework 21 and are integrally molded with the framework on filter
media 20. Seal 42 is provided by at least one, and in the disclosed
embodiment of FIGS. 1, 2, three flexible annular flanges extending
obliquely to axis 14 and radially deflectable relative thereto to
seal against a circumscribing portion of a filter housing
therearound, one embodiment of which is described hereinafter. Rib
networks 24a, 24b include the noted plurality of axial ribs 28a,
28b extending axially between first and second axial ends 36 and 38
of the framework. A plurality of trusses 44, FIG. 2, at first axial
end 36 of the framework extend radially between respective axial
ribs 28a and annular flange 42 for supporting the latter. The noted
arcuate ribs 26a extend obliquely to axis 14 and laterally relative
to the axial extension of framework 21. Arcuate ribs 26a obliquely
point in the same oblique direction as annular flanges 42 providing
the noted seal. The seal provided by one or more flanges 42, the
axial ribs 28a, 28b, and the arcuate ribs 26a, 26b are all
integrally molded on filter media 20 as a single unitary integrally
molded framework.
[0014] The integral flex seal rings provided by flanges 42 provide
not only a flexible seal but also a spring-type retention by
forcing the flex rings provided by flanges 42 into a drafted
surface, preferably conical. This eliminates the need for providing
a seal from urethane potting as in the prior art. The thickness of
the rings is selected to provide enough retention under vibration
to hold the filter in place and prevent axial backing-out thereof.
The retention force is selected so as not to have too much
interference, otherwise making installation and extraction
difficult, but still provide enough retention to resist vibration
induced axial back-out. In a further embodiment, if vibration
back-out is of concern, an interference fit retention mechanism may
be provided, for example as shown in U.S. Pat. No. 6,383,244,
incorporated herein by reference, and further described
hereinafter. In such embodiment, intermittent detent undercuts may
be provide to hold back the end-most flex ring flange 42 (rightmost
in FIG. 1).
[0015] It is significant that filter element 12 is a two-piece
assembly consisting, in the preferred embodiment, solely of two
components, namely filter media 20 and plastic framework 21 molded
thereon. The plastic framework includes a resilient seal 42
integrally molded therewith and of the same plastic material
thereof, eliminating a separate component for the seal, such that
the filter element remains a two-component assembly, including the
seal. The framework extends axially along axis 14 between distally
opposite first and second axial ends at the noted first and second
axial ends of the filter element. Framework 21, including first and
second frames 22a and 22b, is an integrally molded singular
component, including integral connection between frames 22a and 22b
at at least one of and preferably both of the noted first and
second axial ends 38 and 40. The filter element remains a
two-component assembly consisting solely of two components, namely
filter media 20 and framework 21 molded thereon.
[0016] FIG. 3 illustrates a desirable filter combination and
construction, including implementation of the filter element 12 of
FIGS. 1, 2 in combination with a primary filter element 52, and
uses like reference numerals from above where appropriate to
facilitate understanding. Filter 50 includes a housing 54 extending
along axis 14 between first and second axial ends 56 and 58 at
respective first and second housing sections 60 and 62 mounted to
each other at interface 64, as is known, for example as shown in
U.S. Pat. Nos. 6,149,700, 6,402,798, incorporated herein by
reference. As is known, fluid to be filtered, e.g. air, enters
housing inlet 66 as shown at arrow 68 and flows into outer annular
chamber 70 in a spiral path and then flows laterally inwardly as
shown at arrow 72 through primary filter element 52 and secondary
filter element 12 into hollow interior 13 of the latter and then
flows axially rightwardly as shown at arrow 34 to housing outlet
74, which may include a 90.degree. elbow at 76, or may be a
straight outlet. Annular primary filter element 52 includes pleated
filter media 78 extending axially in the housing between first and
second axial ends 80 and 82 and having a hollow interior 84, for
example as shown in U.S. Pat. Nos. 6,149,700, 6,216,334, 6,306,193,
6,391,076, 6,416,561, 6,641,637, incorporated herein by reference.
Annular secondary filter element 12 preferably includes non-pleated
non-woven filter media 20 extending axially in hollow interior 84
between first and second axial ends 16, 18, as above described.
Secondary filter element 12 further includes the noted plastic
molded framework 21 molded and bonded to and structurally
supporting non-pleated non-woven filter media 20 in hollow interior
84. As in the noted incorporated '700 patent, pleated filter media
78 of primary filter element 52 has a plurality of pleats in an
annulus having an outer perimeter 86 defined by a plurality of
outer pleat tips, and an inner perimeter 88 defined by a plurality
of inner pleat tips, wherein fluid to be filtered flows through
primary filter element 52 from an upstream dirty side at outer
annular chamber 70 to a downstream clean side at hollow interior
84, and flows axially in the hollow interior. Also as in the
incorporated '700 patent, primary filter element 52 has an axial
flow passage 90 extending along axis 14 and including the flow as
shown at arrows 34 and 92, and circumscribing hollow interior 84
and having a flow perimeter 94 greater than inner perimeter 88.
Flow passage 90 corresponds to flow passage 56 in the incorporated
'700 patent. Flow arrows 34 and 92 correspond respectively to flow
arrows 58 and 59 in the '700 patent. Outer and inner perimeters 86
and 88 correspond to respective outer and inner perimeters 30 and
34 in the '700 patent. Flow perimeter 94 corresponds to flow
perimeter 60 in the '700 patent. Primary filter element 52 has
first and second end caps 96 and 98 of soft resilient compressible
material, such as foamed potted urethane. End cap 96 has an inner
perimeter at 94 greater than inner perimeter 88. End cap 96
corresponds to end cap 66 of the incorporated '700 patent and
partially covers the rightward axial ends of the pleats of pleated
filter media 78 such that the laterally outward portions 100 of the
axial ends of the pleats are covered by end cap 96 but not the
laterally inward portions 102 of the axial ends of the pleats, such
that the laterally inward portions 102 (corresponding to laterally
inward portions 74 in the incorporated '700 patent) are uncovered
and exposed at the rightward axial end of filter element 52, to in
turn allow axial flow therethrough as shown at arrow 92,
corresponding to axial flow at 59 in the incorporated '700 patent.
This additional or increased axial flow is also shown in the noted
incorporated U.S. Pat. Nos. 6,261,334, 6,306,193, 6,391,076,
6,416,561, 6,641,637.
[0017] Secondary filter element 12 in FIG. 3 is downstream of
primary filter element 52 and filters both the flow in the hollow
interior and the additional flow 92 between flow perimeter 94 and
inner perimeter 88. The additional flow 92 turns laterally inwardly
as shown at arrow 104 and flows through secondary filter element 12
and joins axial flow 34. First axial end 16 of non-pleated
non-woven filter media 20 of the secondary filter element extends
axially beyond first axial end 80 of pleated filter media 78 of the
primary filter element 52 and is axially spaced therefrom by an
axial gap 106 therebetween. Non-pleated non-woven filter media 20
has a first section 108 radially aligned with pleated filter media
78 of primary filter element 52, and has a second section 110
radially aligned with axial gap 106. The junction 112 of first and
second sections 108 and 110 is radially aligned with axial end 108
of pleated filter media 78. Fluid flow through the filter has a
first path as shown at 72 flowing laterally from pleated filter
media 78 then laterally through first section 108 of non-pleated
non-woven filter media 20, and has a second additional path flowing
axially at 92 from axial end 80 of pleated filter media 78 through
the area 102 between flow perimeter 94 and inner perimeter 88 then
turning in axial gap 106 as shown at arrow 104 and flowing
laterally through second section 110 of non-pleated non-woven
filter media 20. Axial gap 106 is axially between end cap 36 of
secondary filter element 12 and axial end 80 of pleated filter
media 78. End cap 96 of primary filter element 52 circumscribes
both axial gap 106 and end cap 36 of secondary filter element 12.
Filter housing 54 at outlet end 56 has an annular flange 114
extending axially between end cap 96 of primary filter element 52
and end cap 36 of secondary filter element 12 and engaging and
sealing each of end caps 96 and 36. A detent retention arrangement
may also be provided for further retaining the secondary element,
for example as shown at detent 60 and flange 46 in U.S. Pat. No.
6,383,244, incorporated herein by reference. Filter housing 54
further includes a valved discharge purge outlet 116 for purging
collected particulate contaminant, as is known. It is preferred
that filter element 12 taper from a first lateral cross-sectional
area at first axial end 16 to a second lateral cross-sectional area
at second axial end 18, FIG. 1, and that the noted second lateral
cross-sectional area be less than the noted first lateral
cross-sectional area. The resulting frusto-conical shape provides a
large open area at the rightward outlet end 16 in FIG. 3 and makes
the filter element 12 well suited for use as a secondary filter
element for the noted primary filter element 52 of the above noted
incorporated patents providing the noted additional flow. The
arrangement in combination provides reduced restriction within a
small package satisfying increasingly demanding space constraints
and affording high efficiency, all while being environmentally
friendly. The integral seal construction at integrally molded
flanges 42 engaging housing flange 114 is particularly cost
effective.
[0018] Further embodiments include pleated and non-pleated filter
media used with a plastic framework having only an outer frame or
only an inner frame or both an outer frame and an inner frame. FIG.
4 shows a filter element 12a having pleated filter media 20c bonded
to inner plastic frame 22b including axial ribs 28b. FIG. 5 shows
filter element 12b having pleated filter media 20c bonded to a
plastic framework including plastic frame 22b having axial ribs
28b, and plastic frame 22a having axial ribs 28a and arcuate ribs
26a. Filter media 20c has an upstream dirty side, e.g. 20d for an
outside-in flow filter, comparable to 20a, and a downstream clean
side 20e, comparable to 20b. The framework is provided by first
plastic frame 22a along upstream dirty side 20d of the filter
media, and a second plastic frame 22b along downstream clean side
20e of the filter media. Frame 22a includes the noted rib network
having a set of ribs 28a extending along upstream dirty side 20d of
the filter media at the pleat tips or creases or bend lines 20f and
bonded thereto. Frame 22b is provided by the noted rib network
including ribs 28b extending along downstream clean side 20e of the
filter media and bonded thereto along the interior of the noted
pleat tips 20f. Filter media 20c is sandwiched between the sets of
ribs 28a and 28b on opposite upstream and downstream sides 20d and
20e of the filter media and bonded respectively thereto.
[0019] In further preferred embodiments, the filter media is oiled
and die cut and then sonically welded into a conical pre-form
before it is overmolded with the plastic framework. The seam from
the sonic weld is aligned along one of the noted axial ribs, so
that the seam is sealed by and bonded to the plastic, minimizing a
possible leak path. Stand-offs such as 19 are provided at end 38 to
space the end of the media slightly from the end of the mold so
that the molten plastic is free to flow around the media to both
the inner and outer ribs at such end. Inner trusses, comparable to
trusses 44, may be provided on the interior of the element for
stress bearing. The molten plastic is preferably injected at end
36, and media end 18 may include portions which are recessed or
otherwise slightly pushed away from the axial end to provide a flow
path for the molten plastic and to prevent damming thereat.
[0020] It is recognized that various equivalents, alternatives and
modifications are possible within the scope of the appended claims.
Each of the noted annular filter elements is preferably a circular
annulus, though other annular shapes may be used, including
elliptical, racetrack-shaped, and other closed-loop annuli. The
shapes may or may not be frusto-conically tapered. The teachings of
the invention may further be applied to flat panel filter elements,
as well as other shapes. The noted ribs may alternatively be
provided by applying heated bars to partially melt and flatten
sections of the filter media into a ribbed structure, i.e. ironing
ribs into the media. The preferred implementation is an air filter,
though other fluid filter applications are possible. In an air
filter, the open areas between the ribs can be larger, since there
are lower pressure drop requirements than a liquid filter. For ease
of service, a circular seal may be preferred between the filter
element and the housing, for example at seal 42 and the housing at
flange 114. In a desirable implementation, the filter element is
installed by pressing it or slightly twisting it into the
receptacle housing at 114 while applying pressure. The louvered,
annular barbs at 42 seal against the internal surface at 114 of the
circular mounting hole in the housing, a duct, or an air handling
conduit. As the filter element slides into the receptacle,
semi-rigid semi-flexible plastic or thermoplastic barbs 42 flex
slightly inwardly, and preferably semi-rigid semi-flexible plastic
or thermoplastic walls of the receptacle at 114 flex slightly
outwardly, to secure and seal the filter element. A radial seal is
formed between the one or more flexible barbs 42 and the receptacle
at flange 114, and, if desired, an axial face seal can be formed
where the axial end 36 of the filter element meets the facing
annular surface of the receptacle. To remove the filter element,
the service technician twists and/or applies a lateral force to
free the face of the filter element from the holder at 114. In a
further embodiment, the filter element is an annular filter element
12 extending axially along axis 14 between the noted distally
opposite first and second axial ends 16 and 18, and framework 21
extends axially along axis 14 between distally opposite first and
second axial ends 36 and 38 at respective first and second axial
ends 16 and 18 of filter element 12, and the noted first end of the
framework has inner and outer peripheral surfaces, and the noted
resilient seal is integrally molded with at least one of such
surfaces.
* * * * *