U.S. patent application number 10/993824 was filed with the patent office on 2006-05-25 for circumferentially pleated filter assembly and method of forming the same.
Invention is credited to Brian L. Fall, Thomas J. Hamlin, Mahesh Z. Patel, John L. Pulek, Aaron Spearin.
Application Number | 20060108277 10/993824 |
Document ID | / |
Family ID | 36407750 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060108277 |
Kind Code |
A1 |
Fall; Brian L. ; et
al. |
May 25, 2006 |
Circumferentially pleated filter assembly and method of forming the
same
Abstract
A filter assembly is provided which includes an outer filter
sleeve formed at least in part by a plurality of pleats, an inner
filter sleeve formed at least in part by a plurality of pleats,
wherein the inner and outer filter sleeves define a passage
therebetween. An inlet cap is secured to a first end of the inner
and outer filter sleeves and it has at least one inlet port
communicating with the passage, and an end cap is secured to a
second end of the inner and outer filter sleeves and it has an end
surface closing the passage. Methods of forming such a filter
assembly are also provided.
Inventors: |
Fall; Brian L.; (East
Haddam, CT) ; Hamlin; Thomas J.; (Vernon, CT)
; Patel; Mahesh Z.; (Plantsville, CT) ; Pulek;
John L.; (Cheshire, CT) ; Spearin; Aaron;
(Willimantic, CT) |
Correspondence
Address: |
CUNO INCORPORATED
400 RESEARCH PARKWAY
P. O. BOX 1018
MERIDEN
CT
06450-1018
US
|
Family ID: |
36407750 |
Appl. No.: |
10/993824 |
Filed: |
November 19, 2004 |
Current U.S.
Class: |
210/338 ;
210/446; 210/493.1; 210/493.2; 55/380; 55/521 |
Current CPC
Class: |
B01D 2201/122 20130101;
Y10T 156/1038 20150115; Y10T 156/1025 20150115; B01D 29/232
20130101; B01D 29/54 20130101; Y10T 156/1051 20150115; B01D 29/111
20130101; B01D 29/21 20130101 |
Class at
Publication: |
210/338 ;
210/446; 210/493.1; 210/493.2; 055/380; 055/521 |
International
Class: |
B01D 29/07 20060101
B01D029/07 |
Claims
1. A filter element comprising: a) an outer filter sleeve formed at
least in part by a plurality of longitudinally extending pleats; b)
an inner filter sleeve formed at least in part by a plurality of
longitudinally extending pleats, the inner and outer filter sleeves
defining a passage therebetween; c) an inlet cap secured to a first
end of the inner and outer filter sleeves and having at least one
inlet port communicating with the passage; and d) an end cap
secured to a second end of the inner and outer filter sleeves and
having an end surface closing the passage.
2. A filter element as recited in claim 1, wherein the outer filter
sleeve includes a plurality of circumferentially disposed arcuate
pleats.
3. A filter element as recited in claim 1, wherein the inner filter
sleeve includes a plurality of circumferentially disposed arcuate
pleats.
4. A filter element as recited in claim 2, wherein adjoining
circumferentially disposed arcuate pleats of the outer filter
sleeve partially overlap one another.
5. A filter element as recited in claim 3, wherein adjoining
circumferentially disposed arcuate pleats of the inner filter
sleeve partially overlap one another.
6. A filter element as recited in claim 4, wherein adjoining
circumferentially disposed arcuate pleats of the outer filter
sleeve overlap one another over approximately 50% to 80% of the arc
length of the pleats.
7. A filter element as recited in claim 5, wherein adjoining
circumferentially disposed arcuate pleats of the inner filter
sleeve overlap one another over approximately 50% to 80% of the arc
length of the pleats.
8. A filter element as recited in claim 2, wherein adjoining
circumferentially disposed arcuate pleats of the outer filter
sleeve are circumferentially spaced from one another.
9. A filter element as recited in claim 3, wherein adjoining
circumferentially disposed arcuate pleats of the inner filter
sleeve are circumferentially spaced from one another.
10. A filter element as recited in claim 2, wherein the
circumferentially disposed arcuate pleats of the outer filter
sleeve are uniformly distributed about the circumference of the
outer filter sleeve.
11. A filter element as recited in claim 3, wherein the
circumferentially disposed arcuate pleats of the inner filter
sleeve are uniformly distributed about the circumference of the
inner filter sleeve.
12. A filter element as recited in claim 2, wherein the
circumferentially disposed arcuate pleats of the outer filter
sleeve have equal arc length.
13. A filter element as recited in claim 3, wherein the
circumferentially disposed arcuate pleats of the inner filter
sleeve have equal arc length.
14. A filter element as recited in claim 2, wherein each of the
circumferentially disposed arcuate pleats of the outer filter
portion has a radially outer pleat leg and a radially inner pleat
leg, and wherein the arc length of the radially inner pleat leg is
shorter than the arc length of the radially outer pleat leg.
15. A filter element assembly as recited in claim 3, wherein each
of the circumferentially disposed arcuate pleats of the inner
filter portion has a radially outer pleat leg and a radially inner
pleat leg, and wherein the arc length of the radially inner pleat
leg is shorter than the arc length of the radially outer pleat
leg.
16. A filter element as recited in claim 1, wherein the outer
filter sleeve and the inner filter sleeve are each formed by a
multi-layered pleated composite including at least one layer of
filter media, an upstream support/drainage layer and a downstream
support/drainage layer.
17. A filter element as recited in claim 16, wherein the at least
one layer of filter media is selected from the group of filter
materials consisting of melt-blown filter media, nonwoven filter
media, glass fiber media and needled felt media.
18. A filter element as recited in claim 16, wherein the
multi-layered composite includes plural layers of filter media each
having the same porosity.
19. A filter element as recited in claim 16, wherein the
multi-layered composite includes plural layers of filter media each
having a different porosity.
20. A filter element as recited in claim 16, wherein the
support/drainage layers of the multi-layered composite are formed
from materials selected from the group consisting of extruded
polymeric meshes, nets and spun bonded polymeric non-wovens.
21. A filter element as recited in claim 1, wherein the inlet cap
is bonded to the outer filter sleeve and the inner filter
sleeve.
22. A filter element as recited in claim 1, wherein the end cap is
bonded to the outer filter sleeve and the inner filter sleeve.
23. A filter element as recited in claim 1, wherein the inlet cap
has a two-piece construction that includes an inner portion and an
outer portion, and wherein the inner filter sleeve is bonded to the
inner portion of the inlet cap and the outer filter sleeve is
bonded to the outer portion of the inlet cap.
24. A filter element as recited in claim 1, wherein the end cap has
a two-piece construction that includes an inner portion and an
outer portion, and wherein the inner filter sleeve is bonded to the
inner portion of the end cap and the outer filter sleeve is bonded
to the outer portion of the end cap.
25. A filter element as recited in claim 1, wherein an elastomeric
seal is molded over an outer periphery of the inlet cap.
26. A filter element as recited in claim 1, wherein the inlet cap
has a closed end surface.
27. A filter element as recited in claim 1, wherein the inlet cap
has an open end surface.
28. A filter element as recited in claim 1, further comprising a
sheath surrounding the outer filter sleeve and formed from a
material having a relatively open porosity.
29. A filter element as recited in claim 1, wherein the inner
filter sleeve defines a central bore of the filter assembly and the
end cap includes a central exit port communicating with the central
bore.
30. A filter element comprising: a) a radially outer filter sleeve
formed by longitudinally extending circumferentially disposed
arcuate pleats; b) a radially inner filter sleeve arranged
concentrically with the radially outer filter sleeve and formed by
longitudinally extending circumferentially disposed arcuate pleats,
the inner and outer filter sleeves defining an annular passage
therebetween; c) an inlet cap secured to a first end of the inner
and outer filter sleeves and having at least one inlet port
communicating with the annular passage; and d) an end cap secured
to a second end of the inner and outer filter sleeves and having an
annular end surface closing the annular passage.
31. A filter element as recited in claim 30, wherein adjoining
circumferentially disposed pleats of the outer filter sleeve
partially overlap one another, and wherein adjoining
circumferentially disposed pleats of the inner filter sleeve
partially overlap one another.
32. A filter element as recited in claim 30, wherein adjoining
circumferentially disposed pleats of the outer filter sleeve
overlap one another over approximately 50% to 80% of the arc length
of the pleats, and wherein adjoining circumferentially disposed
arcuate pleats of the inner filter sleeve overlap one another over
approximately 50% to 80% of the arc length of the pleats.
33. A filter element as recited in claim 30, wherein adjoining
circumferentially disposed arcuate pleats of the outer filter
sleeve are circumferentially spaced from one another, and wherein
adjoining circumferentially disposed arcuate pleats of the inner
filter sleeve are circumferentially spaced from one another.
34. A filter element as recited in claim 30, wherein the
circumferentially disposed arcuate pleats of the outer filter
sleeve are uniformly distributed about the circumference of the
outer filter sleeve, and wherein the circumferentially disposed
arcuate pleats of the inner filter sleeve are uniformly distributed
about the circumference of the inner filter sleeve.
35. A filter element as recited in claim 30, wherein the
circumferentially disposed arcuate pleats of the outer filter
sleeve have equal arc length, and wherein the circumferentially
disposed arcuate pleats of the inner filter sleeve have equal arc
length.
36. A filter element as recited in claim 30, wherein the outer
filter sleeve and the inner filter sleeve are each formed by a
multi-layered pleated composite including at least one layer of
filter media, an upstream support/drainage layer and a downstream
support/drainage layer.
37. A filter element as recited in claim 30, wherein the inlet cap
and the end cap are bonded to the outer filter sleeve and the inner
filter sleeve.
38. A filter element as recited in claim 30, wherein at least one
of the inlet cap and the end cap has a two-piece construction.
39. A filter element as recited in claim 30, wherein an elastomeric
seal is molded over an outer periphery of the inlet cap.
40. A filter element as recited in claim 30, further comprising a
sheath surrounding the radially outer filter sleeve and formed from
a material having a relatively open porosity.
41. A filter element as recited in claim 30, further comprising a
sheath covering a radially inner surface of the radially inner
filter sleeve and formed from a material having a relatively open
porosity.
42. A filter element as recited in claim 30, wherein the inner
filter sleeve defines a central bore of the filter assembly and the
end cap includes a central exit port communicating with the central
bore.
43. A filter element comprising: a) a radially outer filter sleeve
formed by a multi-layered pleated composite including a plurality
of longitudinally extending circumferentially disposed arcuate
pleats; b) a radially inner filter sleeve arranged concentrically
with the radially outer filter sleeve and formed by a multi-layered
pleated composite including a plurality of longitudinally extending
circumferentially disposed arcuate pleats, wherein the inner filter
sleeve defines a central bore, and wherein the inner and outer
filter sleeves define an annular passage therebetween; c) an inlet
cap secured to an upper end of the inner and outer filter sleeves
and having at least one inlet port communicating with the annular
passage; d) an end cap secured to a lower end of the inner and
outer filter sleeves, having an annular end surface closing the
annular passage and a central exit port communicating with the
central bore; and e) a porous sheath surrounding the radially outer
filter sleeve.
44. A filter element as recited in claim 43, wherein the inner
filter sleeve and the outer filter sleeve are bonded to side
surfaces of the inlet cap and end cap.
45. A filter element as recited in claim 43, wherein the inner
filter sleeve and the outer filter sleeve are bonded to end
surfaces of the inlet cap and end cap.
46. A filter element as recited in claim 43, wherein the
multi-layered pleated composite forming the inner filter sleeve and
the outer filter sleeve include at least one layer of filter media,
an upstream support/drainage layer and a downstream
support/drainage layer.
47. A filter element as recited in claim 46, wherein the at least
one layer of filter media is selected from the group of filter
materials consisting of melt-blown filter media and microporous
membranes.
48. A filter element as recited in claim 46, wherein the
multi-layered pleated composite includes plural layers of filter
media each having the same porosity.
49. A filter element as recited in claim 46, wherein the
multi-layered pleated composite includes plural layers of filter
media each having a different porosity.
50. A filter element as recited in claim 46, wherein the
support/drainage layers of the multi-layered pleated composite are
formed from materials selected from the group consisting of
extruded polymeric meshes, nets and spun bonded polymeric
non-wovens.
51. A filter assembly comprising: a) a housing having an interior
chamber and a removable cover enclosing the interior chamber, and
including an inlet conduit for delivering unfiltered fluid to the
interior chamber and an outlet conduit for carrying filtered fluid
from the interior chamber; and b) a filter element disposed within
the interior chamber of the housing and including concentrically
arranged radially inner and radially outer filter sleeves each
having a plurality of longitudinally extending circumferentially
disposed arcuate pleats, wherein the inner and outer filter sleeves
define an annular passage therebetween for receiving unfiltered
fluid from the inlet conduit of the housing, and wherein the inner
filter sleeve defines a central bore communicating with the outlet
conduit of the housing, an inlet cap secured to an upper end of the
inner and outer filter sleeves and having a plurality of inlet
ports communicating with the annular passage, and an end cap
secured to a lower end of the inner and outer filter sleeves and
having a central exit port communicating with the central bore.
52. A filter assembly as recited in claim 51, wherein the inlet cap
includes an over-molded peripheral sealing surface for sealingly
engaging the cover of the housing when the filter assembly is
enclosed therein.
53. A filter assembly as recited in claim 51, wherein the inlet cap
has an open end surface with a central aperture formed therein for
sealingly engaging the inlet conduit of the housing.
54. A filter assembly as recited in claim 51, wherein the inlet cap
has a closed end surface.
55. A filter assembly as recited in claim 51, further comprising a
perforated basket for supporting the filter assembly within the
housing.
56. A method of forming a filter element comprising the steps of:
a) preparing a plurality of upstanding pleats each having first and
second pleat legs, wherein the first pleat leg of one pleat is
joined to the second pleat leg of a preceding pleat by a medial
pleat section; b) moving the upstanding pleats into an overlapped
condition wherein each medial pleat section becomes part of the
second leg of a preceding pleat; and c) forming the overlapped
pleats into a cylindrical configuration.
57. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes forming the upstanding pleats with first and second pleat
legs of equal height.
58. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes forming the upstanding pleats with first and second pleat
legs of different height.
59. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes forming the upstanding pleats With first and second pleat
legs of different height, wherein the height of the first pleat leg
is less than the height of the second pleat leg.
60. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes joining the first pleat leg of one pleat to the second
pleat leg of a preceding pleat with a medial pleat section that
includes at least one medial pleat segment.
61. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes joining the first pleat leg of one pleat to the second
pleat leg of a preceding pleat with a medial pleat section that
includes two medial pleat segments.
62. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes joining the first pleat leg of one pleat to the second
pleat leg of a preceding pleat with a medial pleat section that
includes two medial pleat segments of equal length.
63. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes joining the first pleat leg of one pleat to the second
pleat leg of a preceding pleat with a medial pleat section that
includes two medial pleat segments of different length.
64. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes joining the first pleat leg of one pleat to the second
pleat leg of a preceding pleat with a medial pleat section having a
length that is less than the height of the preceding pleat leg.
65. A method of forming a filter element according to claim 56,
wherein the step of preparing a plurality of upstanding pleats
includes joining the first pleat leg of one pleat to the second
pleat leg of a preceding pleat with a medial pleat section having a
length that is about half the height of the preceding pleat leg.
Description
BACKGROUND OF THE DISCLOSURE
[0001] The subject disclosure is directed to fluid filtration, and
more particularly, to a bag-type filter assembly having two
concentric circumferentially pleated media sleeves defining an
annular passage therebetween, which receives fluid for
filtration.
[0002] Bag-type filter systems for fluid filtration are well known
in the art. These systems typically include a cylindrical housing,
which is closed at one end and has a removable cover at the opposed
end. An inlet conduit delivers fluid to be filtered into the
housing and an outlet conduit removes filtered fluid from the
housing.
[0003] Replaceable bag filters are disposed within the housing in
order to filter fluids delivered thereto. Typically, bag filters
include filter media having an open upper end and a closed bottom.
The filter bag is supported within an open mesh basket or cage,
which is typically suspended within the housing. The basket is
intended to support the media of the filter bag to prevent it from
bursting as the bag fills with liquid.
[0004] There are several disadvantages associated with existing
bag-type filters. One such disadvantage is that filter bags have a
large hold-up volume. Thus, removal of a used filter bag is quite
difficult, because it can be relatively heavy. A full filter bag
could weigh as much as thirty pounds and it may contain hazardous
substances, adding to the difficulty of removal. To remedy this
situation, evacuation balloons have been used to reduce the hold-up
volume prior to the removal of a used bag. However, these balloons
are often cumbersome to handle.
[0005] Another disadvantage associated with existing bag filters is
that they provide a limited amount of effective filtration area.
Efforts to increase the effective filtration area of existing bag
filter have been limited because of the industry standardization of
basket sizes. That is, filter bags are typically available it two
distinct sizes: (#1) 7'' diameter.times.16'' long; and (#2) 7''
diameter.times.32'' long. Consequently, any increase in effective
filtration area is limited by the requirement that the outer
diameter of the filter cannot be altered.
[0006] There have been a number of efforts to design bag filters to
minimize hold-up volume and maximize the effective area for
filtration. For example, U.S. Pat. No. 4,081,379 discloses an
annular filter bag that provides more available surface area than a
conventional filter bag. U.S. Pat. Nos. 4,863,602 and 4,877,526
disclose a bag filter with increased surface area that includes
multiple wrapped layers of melt-blown media with a flexible
transport layer in between. The Hayward Lofclear 500 Series bag
filter provides increased surface area by folding a pre-filter
layer, which is wrapped by final filtration layers. For the most
part, these prior art efforts have fallen short.
[0007] A particularly useful bag-type filter assembly is disclosed
in U.S. Pat. Nos. 6,030,531 and 6,238,560. In this unique filter
assembly, effective surface area is increased by providing two
concentric media sleeves connected at one end to an open inlet cap
and at the opposed end to a closed end cap. The dual sleeve
configuration also minimizes the hold-up volume of fluid remaining
in the filter element after use, making it easier to remove from
the filter basket/housing.
[0008] Over the years, the design of cylindrical pleated filter
cartridges has involved similar efforts to maximize the amount of
filter media or surface area that may be fit into a filter
cartridge having a given outer diameter. In a standard radially
pleated filter cartridge, the number of pleats that can be packed
about the cartridge core limits the amount of filter media that may
be packed into the cartridge. Consequently, there is a substantial
amount of empty space between adjacent pleats at the outer
periphery of the filter element.
[0009] A spiral pleated filter element is comparable to a standard
radially pleated filter element in that it includes a plurality of
longitudinal pleats disposed in a cylindrical configuration. In a
spiral-pleated filter, however, the ends of the pleats are rolled
over to minimize the spacing between adjacent pleat surfaces near
an outer diameter of the filter element. In this case, the pleat
height is substantially greater than the distance between the outer
periphery of the cartridge core and the inner periphery of the
cartridge cage. Consequently, in a spiral-pleated filter, the
pleats at the outer periphery occupy the excess volume that would
normally represent empty space in a radially pleated filter
element. This provides increased filter surface area as compared to
a standard radial pleat configuration.
[0010] It would be beneficial to employ techniques used to enhance
effective surface area in pleated filter cartridges to bag-type
filters. This would provide increased filter life, lower pressure
drop and lower the operating costs for the customer.
SUMMARY OF THE DISCLOSURE
[0011] The subject disclosure is directed to a new and useful
bag-type filter assembly, which includes an outer filter sleeve
formed at least in part by a plurality of longitudinally extending
pleats, and an inner filter sleeve formed at least in part by a
plurality of longitudinally extending pleats. The concentric
pleated filter sleeves provide a significant increase in the
effective surface area of the filter assembly of the subject
disclosure, as compared to conventional bag-type filters known in
the art. The enhanced surface area increases the life of the
filter, lowers pressure drop and lowers the operating costs for the
customer. The concentric inner and outer filter sleeves define an
annular fluid passage therebetween, which has a reduced hold-up
volume as compared to conventional bag-type filters known in the
art. This reduction in hold-up volume eases the removal of the
filter assembly from its housing after the filter has exceeded its
useful lifespan.
[0012] An inlet cap is secured to a first end of the inner and
outer filter sleeves and it has at least one inlet port
communicating with the fluid passage of the filter assembly. An end
cap is secured to a second end of the inner and outer filter
sleeves and it has an end surface closing the fluid passage. In a
presently preferred embodiment of the disclosure, a sheath
surrounds the downstream side of the outer filter sleeve to provide
a smooth continuous surface to protect the filter media and aid in
installation and removal from the basket. The sheath is formed from
a material having a relatively open porosity, such as a polymeric
mesh or screen. It also envisioned that a similar sheath would
surround or otherwise protect the downstream side of the inner
filter sleeve to further aid in the installation and removal of the
filter from the basket.
[0013] Preferably, each filter sleeve includes a plurality of
longitudinally extending, circumferentially disposed arcuate
pleats. In an embodiment of the disclosure, adjoining
circumferentially disposed arcuate pleats of either or both filter
sleeves partially overlap one another over approximately 50% to 80%
of the arc length or arcuate height of the pleats. In an embodiment
of the disclosure, adjoining circumferentially disposed arcuate
pleats of either or both filter sleeves are circumferentially
spaced from one another. In an embodiment of the disclosure, the
circumferentially disposed arcuate pleats of either or both filter
sleeves are uniformly distributed. In an embodiment of the
disclosure, the circumferentially disposed arcuate pleats of either
or both filter sleeves have equal arc length. In embodiments of the
disclosure, each of the circumferentially disposed arcuate pleats
of the outer and inner filter sleeves has a radially outer pleat
leg and a radially inner pleat leg. Typically, the arc length or
arcuate height of the radially inner pleat leg is shorter than the
arc length or arcuate height of the radially outer pleat leg.
[0014] The outer filter sleeve and the inner filter sleeve are each
preferably formed from a multi-layered pleated composite that
includes at least one layer of filter media, an upstream
support/drainage layer and a downstream support/drainage layer. The
filter media is preferably selected from the group of filter
materials consisting of any flexible and pleatable filter media
such as melt-blown media, felt, wet laid paper (glass fiber), with
the preferred medias being selected from melt-blown filter media
and microporous membranes. Other filter materials may also be used
depending upon the application in which the filter is employed.
[0015] In one embodiment of the disclosure, the multi-layered
composite includes plural layers of filter media each having the
same porosity. In another embodiment of the disclosure, the
multi-layered composite includes plural layers of filter media each
having a different porosity. The support/drainage layers of the
multi-layered composite are preferably formed from materials
selected from the group consisting of extruded polymeric net or
meshes and polymeric nonwovens (i.e., spunbonded, etc.). Other
drainage/support materials may also be used depending upon the
application within which the filter is employed.
[0016] In accordance with an embodiment of the disclosure, the
inlet cap is bonded to the outer filter sleeve and the inner filter
sleeve, and an elastomeric seal may be molded over an outer
periphery of the inlet cap. The end cap is also bonded to the outer
filter sleeve and the inner filter sleeve. Preferably, the inner
filter sleeve defines a central bore of the filter assembly and the
end cap includes a central exit port communicating with the central
bore.
[0017] In an embodiment of the disclosure, at least one of the
inner and outer filter sleeves is bonded to side surfaces of the
inlet cap and end cap. In another embodiment of the disclosure at
least one of the inner and outer filter sleeves are bonded to end
surfaces of the inlet cap and end cap.
[0018] The subject disclosure is also directed to a filter assembly
that includes a radially outer filter sleeve formed by a
multi-layered pleated composite including a plurality of
longitudinally extending circumferentially disposed arcuate pleats,
a radially inner filter sleeve arranged concentrically with the
radially outer filter sleeve and formed by a multi-layered pleated
composite including a plurality of longitudinally extending
circumferentially disposed arcuate pleats. The inner filter sleeve
defines a central bore, and the inner and outer filter sleeves
define an annular passage therebetween. An inlet cap is bonded to
an upper end of the inner and outer filter sleeves and it has at
least one inlet port communicating with the annular passage. An end
cap is bonded to a lower end of the inner and outer filter sleeves,
and it has an annular end surface closing the annular passage and a
central exit port communicating with the central bore. In addition,
a porous sheath of material surrounds the radially outer filter
sleeve. A similar sheath may also surround the inner surface of the
radially inner filter sleeve.
[0019] The subject disclosure also covers a filtration system that
includes a housing or pressure vessel having an interior chamber
and a removable cover, which is encloses the interior chamber. An
inlet conduit delivers unfiltered fluid to the interior chamber of
the housing and an outlet conduit carries filtered fluid from the
interior chamber of the housing. The system further includes a
filter element disposed within the interior chamber of the housing
and including concentrically arranged radially inner and radially
outer filter sleeves each having a plurality of circumferentially
disposed arcuate pleats. The inner and outer filter sleeves define
an annular passage therebetween for receiving unfiltered fluid from
the inlet conduit of the housing, and the inner filter sleeve
defines a central bore communicating with the outlet conduit of the
housing.
[0020] An inlet cap is secured to an upper end of the inner and
outer filter sleeves, with a plurality of inlet ports communicating
with the annular passage, and an end cap is secured to a lower end
of the inner and outer filter sleeves, with a central exit port
communicating with the central bore. Preferably, the inlet cap
includes an over-molded peripheral sealing surface for sealingly
engaging the cover of the housing when the filter assembly is
enclosed therein. In addition, the system includes a perforated
basket for supporting the filter assembly within the housing.
[0021] The subject disclosure is also directed to a method of
forming a filter element which includes the steps of the preparing
a plurality of upstanding pleats each having first and second pleat
legs, wherein the first pleat leg of one pleat is joined to the
second pleat leg of a preceding pleat by a medial pleat section,
moving the upstanding pleats into an overlapped condition wherein
each medial pleat section becomes part of the second leg of a
preceding pleat, and forming the overlapped pleats into a
cylindrical configuration. The step of preparing a plurality of
upstanding pleats includes forming the upstanding pleats with first
and second pleat legs of equal height, first and second pleat legs
of different height, or with first and second pleat legs of
different height, wherein the height of the first pleat leg is less
than the height of the second pleat leg.
[0022] The step of preparing a plurality of upstanding pleats
includes joining the first pleat leg of one pleat to the second
pleat leg of a preceding pleat with a medial pleat section that
includes at least one medial pleat segment. The medial pleat
section can include two medial pleat segments. These segments can
be of equal length or they can be of a different length. The length
of the medial pleat section is preferably less than the height of
the preceding pleat leg, and more preferably the length of the
medial pleat section is about half the height of the preceding
pleat leg.
[0023] These and other aspects of the bag-type filter assembly of
the subject disclosure will become more readily apparent to those
having ordinary skill in the art from the following detailed
description of the disclosure taken in conjunction with the
drawings described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] So that those having ordinary skill in the art to which the
subject disclosure appertains will more readily understand how to
make and use the filter assembly of the subject disclosure,
presently preferred embodiments thereof will be described in detail
hereinbelow with reference to the drawings, wherein:
[0025] FIG. 1 is a perspective view of a filter assembly
constructed in accordance with a presently preferred embodiment of
the subject disclosure, wherein a portion of the outer sheath that
surrounds the filter element is cutaway to reveal the inner and
outer circumferentially pleated filter sleeves which form the
filter element, and wherein the pleated filter sleeves are
partially sectioned to reveal the pleat configuration thereof and
the fluid passage defined therebetween;
[0026] FIG. 1a is an enlarged localized perspective view of the
pleated filter sleeves shown in FIG. 1, wherein a section of a
pleat of each sleeve is divided to illustrate the upstream
drainage/support layer, the downstream drainage/support layer and
the plural media layers which form the pleated composite;
[0027] FIG. 2 is a top end view of the filter assembly of FIG. 1,
illustrating the structural features of the inlet cap disposed at
the upper end of the filter assembly, which includes a plurality of
circumferentially spaced apart arcuate inlet ports for admitting
fluid into the fluid passage defined between the pleated filter
sleeves;
[0028] FIG. 2a is a partial perspective view of a filter assembly
of the subject disclosure, which includes a closed inlet cap, as
compared to the open inlet cap shown in FIG. 2;
[0029] FIG. 3 is a bottom end view of the filter assembly of FIG.
1, illustrating the structural features of the end cap disposed at
the lower end of the filter assembly, which has an annular end
surface closing the passage defined between the pleated filter
sleeves;
[0030] FIG. 4 is an enlarged localized end view of the filter
assembly, with a portion of the end cap broken away to reveal the
pleat configuration of the inner filter sleeve, and wherein
adjoining circumferentially disposed arcuate pleats of the inner
and outer filter sleeves abut one another, whereby the crest of one
pleat follows the base of an adjoining pleat;
[0031] FIG. 5 is an enlarged localized end view of the filter
assembly, with a portion of the end cap broken away to reveal the
pleat configuration of the inner filter sleeve, and wherein
adjoining circumferentially disposed arcuate pleats of the inner
and outer filter sleeves partially overlap one another;
[0032] FIG. 6 is a cross-sectional view of a portion of the inlet
cap shown in FIG. 2, taken along line 6-6, illustrating the manner
in which the inner and outer sleeves of the filter element are
secured to the inlet cap;
[0033] FIG. 7 is a cross-sectional view of a portion of the end cap
shown in FIG. 3, taken along line 7-7, illustrating the manner in
which the inner and outer sleeves of the filter element are secured
to the end cap;
[0034] FIG. 8 is a cross-sectional view of the filter assembly of
the subject disclosure disposed with a pressure vessel, wherein a
series of arrows indicate the directional flow path of fluid
through the filter assembly;
[0035] FIG. 9 is a perspective view of a pleat formation used to
form the circumferential pleats of the subject disclosure, that
includes upstanding pleats having first and second pleat legs of
equal height, wherein the first pleat leg of one pleat is joined to
the second pleat leg of a preceding pleat by a flat medial pleat
section;
[0036] FIG. 10 is a top plan view of the pleat formation shown in
FIG. 9;
[0037] FIG. 11 is a perspective view of the circumferential pleats
formed by moving the pleat formation of FIGS. 9 and 10 into an
overlapped condition, wherein each medial pleat section becomes
part of the second leg of a preceding pleat;
[0038] FIG. 12 is a perspective view of another pleat formation
used to form the circumferential pleats of the subject disclosure,
that includes upstanding pleats having first and second pleat legs
of equal height, wherein the first pleat leg of one pleat is joined
to the second pleat leg of a preceding pleat by a medial pleat
section including two medial pleat segments of equal length;
[0039] FIG. 13 is a top plan view of the pleat formation shown in
FIG. 13;
[0040] FIG. 14 is a perspective view of the circumferential pleats
formed by moving the pleat formation of FIGS. 12 and 13 into an
overlapped condition, wherein the two medial pleat segments of
equal length are flattened to become part of the second leg of a
preceding pleat;
[0041] FIG. 15 is a top plan view of the circumferential pleats
shown in FIG. 14;
[0042] FIG. 16 is a perspective view of another pleat formation
used to form the circumferential pleats of the subject disclosure,
that includes upstanding pleats having first and second pleat legs
of different height, wherein the first pleat leg of one pleat is
joined to the second pleat leg of a preceding pleat by a medial
pleat section including two medial pleat segments of different
length;
[0043] FIG. 17 is a top plan view of the pleat formation shown in
FIG. 16; and
[0044] FIG. 18 is a perspective view of the circumferential pleats
formed by moving the pleat formation of FIGS. 16 and 17 into an
overlapped condition, wherein the two medial pleat segments of
different length are flattened to become part of the second leg of
a preceding pleat.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0045] Referring now to the drawings wherein like reference
numerals identify similar structural elements and/or features of
the subject disclosure, there is illustrated in FIG. 1a filter
assembly constructed in accordance with a presently preferred
embodiment of the subject disclosure and designated generally by
reference numeral 10. Filter assembly 10 is a type of filter
assembly commonly referred to as a bag-type filter, which is
preferably collapsible and readily disposable after use.
[0046] Referring to FIG. 1, the filter assembly 10 includes a
generally cylindrical inner filter sleeve 12 and a generally
cylindrical outer filter sleeve 14. The inner and outer filter
sleeves 12, 14 are each formed, at least in part, from a plurality
of longitudinally extending, circumferentially disposed arcuate
pleats 16, which will be described in greater detail below. The
pleats 16 are used to increase the amount of effective filtration
area within the filter assembly relative to prior art bag-type
filters. The effective surface area is the amount of filter media
that is accessible to fluid during use. An elongated annular
passage 18 is defined between the inner and outer pleat sleeve 12,
14, for receiving unfiltered fluid, and the inner filter sleeve 12
defines a central bore 20 of the filter assembly 10 for fluid
transfer.
[0047] An inlet cap 22 is secured to an upper or first end of the
inner and outer filter sleeves 12, 14, in a manner, which will be
discussed in greater detail below with reference to FIG. 6. Inlet
cap 22, which is best seen in FIG. 2, includes a plurality of
circumferentially disposed arcuate inlet ports 24 and a central
access port 23. Inlet ports 24 communicate with the annular passage
18 defined between the inner and outer filter sleeves 12, 14 for
facilitating the ingress of unfiltered fluid into the passage. The
central access port 23 of inlet cap 22 is adapted and configured to
mount or otherwise sealingly accommodate an inlet conduit (see FIG.
8), which passes through the central bore 20 of the filter assembly
10 to deliver unfiltered fluid to the inlet ports 24 of inlet cap
22.
[0048] Referring to FIG. 2, inlet cap 22 is preferably formed from
a high-strength, lightweight, plastic material, such as
polypropylene. For ease of assembly, the inlet cap 22 is formed
from two distinct structural elements, including an inner body
portion 22a and an outer flange portion 22b. The inner body portion
22a of inlet cap 22 defines an impervious annular end surface 25
that defines the central access port 23. Access port 23 is
dimensioned and configured to accommodate an inlet conduit, which
delivers unfiltered or otherwise untreated fluid into the trough
formed by inlet cap 22. The outer flange portion 22a of inlet cap
22 defines the inlet ports 24 that communicate with annular passage
18.
[0049] In another embodiment of the present disclosure, which is
illustrated in FIG. 2a, the inlet cap 122 is closed or blind, and
thus there is no central access port formed in the end surface
thereof. In such an instance, the inlet conduit, which delivers
unfiltered fluid to inlet ports 124 of inlet cap 122, communicates
with the filter assembly through the top or cover of the housing,
which supports the filter assembly.
[0050] The two component parts of the inlet cap 22 are preferably
mechanical secured together through the interaction of a number of
locking features including a plurality of circumferentially spaced
apart engagement tabs 27 formed on the inner body portion 22a of
the inlet cap 22 and a plurality of corresponding recesses (not
shown) formed on the outer flange potion 22b of the inlet cap 22.
In addition, while not shown, a series of arcuate tabs project
radially inwardly from the outer body portion 22b to engage a
corresponding annular lip formed on the surface of the inner body
portion 22a. Alternate means of securing or otherwise fastening or
joining the two components of the inlet cap together may be
employed. It is also envisioned that inlet cap 22 can be formed as
a single unitary member.
[0051] The outer flange portion 22b of inlet cap 22 also has a
radially outer shoulder 22c that may include an elastomeric
over-molded sealing surface 29, best seen in FIG. 6. The
over-molded sealing surface 29 improves the seal interface between
the inlet cap 22 of filter assembly 10 and the housing which
supports the filter assembly 10 during use, as shown for example in
FIG. 8. An over-molded seal of this type is disclosed in a commonly
assigned U.S. Provisional Patent Application Ser. No. 60/404,111
entitled "Seal For Collapsible Filter Element," filed dated Aug.
15, 2002, which is incorporated by reference herein.
[0052] Referring again to FIG. 1, an end cap 26 is secured to a
lower or second end of the inner and outer filter sleeves 12, 14,
in a manner, which will be discussed in greater detail below with
reference to FIG. 7. As best seen in FIG. 3, end cap 26, has an
impervious annular end surface 28 closing the annular passage 18
between the inner and outer filter sleeves 12, 14. End surface 28
prevents the egress of unfiltered fluid from filter assembly 10. In
addition, end cap 26 has a relatively large central exit port 32
communicating with the central bore 20 formed by inner filter
sleeve 12 to facilitate the egress of filter fluid from the filter
assembly 10, and to permit the passage of the inlet conduit shown
in FIG. 8. It is envisioned and encompassed by the subject
disclosure that end cap 26 could be formed from two separate
components. These components would be configured and assembled in a
manner similar to the two component parts of the inlet cap 22.
[0053] With continuing reference to FIG. 1, a sheath 30 surrounds
the outer filter sleeve 14 and is formed from a material having a
relatively open porosity, such as for example, a polymeric mesh or
screen. Sheath 30 serves to ease the installation of the filter
assembly 10 into a basket (not shown), by reducing hang-ups of the
pleats on the sides of the basket. It is envisioned that this same
type of sheathing may be associated with the radially inner surface
of the inner filter sleeve 12, within the central bore 20 of filter
assembly 10, to protect the inner filter sleeve 12 from the basket
during installation and to ease removal.
[0054] Referring now to FIG. 1a, the inner and outer filter sleeves
12, 14 of filter assembly 10 are each formed by a multi-layered
pleated composite. The pleated composite structure may be produced
on a conventional pleating machine, such as a pusher bar pleater,
blade type pleater, or gear type pleater or it may be formed by
conventional folding techniques. Alternatively, it is envisioned
that the pleated composite could be produced using a device in
which the media is wrapped or otherwise formed about a mandrel that
is repeatedly indexed in a reciprocating or similar manner.
[0055] The composite preferably includes one or more layers of
filter media 34, an upstream support/drainage layer 38 and a
downstream support/drainage layer 36. In the case of the outer
filter sleeve 14, the upstream support/drainage layer 38 is
associated with the radially inner side of the sleeve, while the
downstream support/drainage layer 36 is associated with the
radially outer side of the sleeve. Conversely, in the case of the
inner filter sleeve 12, the upstream support/drainage layer 38 is
associated with the radially outer side of the sleeve, while the
downstream support/drainage layer 36 is associated with the
radially inner side of the sleeve.
[0056] The upstream and downstream drainage/support layers 36, 38
of the multi-layered composite from which the inner and outer
filter sleeves 12, 14 are formed can be made of any material having
suitable drainage characteristics. For example, the
drainage/support layers 36, 38 can be in the form of a mesh or
screen or a porous woven or non-woven sheet. Meshes and screens
come in various forms including metallic meshes that are often used
for high temperature filtration applications, and polymeric meshes
that are typically used for lower temperature applications.
Polymeric meshes come in the form of woven meshes and extruded
meshes. Either type may be employed. It is envisioned that the
upstream and downstream drainage/support layers 36, 38 of the inner
and outer sleeves 12, 14 can be made from the same or different
material depending upon the filtration application in which filter
assembly 10 is employed.
[0057] The filter media layers 34 of the multi-layered composite
from which the inner and outer filter sleeves 12, 14 are formed can
be selected in accordance with the fluid to be filtered and the
desired filtering characteristics. The filter medium can comprise a
porous film, i.e. microporous membrane or a fibrous sheet or mass
i.e. needled felt, melt-blown, glass fiber, etc. It may have a
uniform or graded pore structure and any appropriate effective pore
size, and it may be formed from any suitable material, such as a
natural material or synthetic polymer. As compared to conventional
radial pleated filters or spiral pleated filters, the filter
assembly of the subject disclosure can employ relatively thick
filter media and support/drainage material without reducing the
effective filtration area of the filter assembly.
[0058] It is also envisioned that the filter media can include two
or more layers of media having different filtering characteristics,
wherein one layer would serve as a prefilter for the other layer.
In one embodiment of the disclosure, the multi-layered composite
from which the inner and outer sleeves 12, 14 are formed includes
plural layers of filter media 34 each having the same porosity. In
another embodiment of the disclosure, the multi-layered composite
from which the inner and outer sleeves 12, 14 are formed includes
plural layers of filter media 34 each having a different porosity.
In such an instance, layers of more open, i.e., less retentive,
grades of media would be disposed on the upstream side of the
composite and layers of tighter, i.e., more retentive, grades of
media would be disposed on the disposed downstream side of the
composite. It is also envisioned that a layer or layers of
non-pleated media more open than the most open pleated media layer,
can be positioned on the upstream side of both pleated filter
sleeves 12, 14. These layers would serve to reduce the loading on
the downstream pleated medias, promoting extended life.
[0059] It is also envisioned and well within the scope of the
subject disclosure that the composite from which filter sleeves 12,
14 are formed can consist of one or more layers of media laminated
to one or more layers of a support/drainage material. For example,
a fluoropolymer media may be laminated to a spunbonded
polypropylene support/drainage material. Alternatively, a
fluoropolymer media layer laminated to a polypropylene symmetric or
asymmetric mesh or netting. There are significant advantages to
using such laminated materials, including improvements in
inventory, manufacturing and assembly.
[0060] In an exemplary embodiment of the subject disclosure, the
material defining the filter media layers 34 of the inner and outer
filter sleeves 12, 14 are meltblown polypropylene medias. The
material defining the upstream support layers 38 of the inner and
outer filter sleeves 12, 14 is polymeric netting, and the material
defining the downstream drainage layers 36 of the inner and outer
filter sleeves 12, 14 is a non-woven spunbond material. In this
exemplary embodiment of the subject disclosure, the inner pleated
filter sleeve 12 has an inner diameter of about 4.750'' and the
outer pleated filter sleeve 14 has an outer diameter of about
6.687''. These dimensions are dependent upon the dimensions of the
basket within which the filter assembly is deployed for
service.
[0061] It is envisioned that the longitudinally extending
circumferentially disposed arcuate pleats 16 of the inner filter
sleeve 12, the outer filter sleeve 14 or both the inner and outer
filter sleeves 12, 14 have equal arc length. Each arcuate pleat 16
has a pair of legs, including a radially inner leg 16a and a
radially outer leg 16b, as illustrated for example in FIG. 1a. The
two legs 16a, 16b of each pleat 16 have a different arc length or
arcuate height. The arc length of the radially inner pleat leg 16a
is typically shorter or less than the arc length of the radially
outer pleat leg 16b. For purposes of this disclosure, the overall
arcuate height of each pleat 16 is measured relative to the inner
pleat leg 16a thereof.
[0062] In one exemplary embodiment of the disclosure, the arc
length or arcuate height h.sub.i of the radially inner leg 16a of
each pleat 16 is about 1.0 inch and the arc length or arcuate
height h.sub.o of the radially outer leg 16b of each pleat 16 is
about 1.5 inches. In another exemplary embodiment of the
disclosure, the arc length or arcuate height hi of the radially
inner leg 16a of each pleat 16 is about 0.75 inches and the arc
length or arcuate height h.sub.o of the radially outer leg 16b of
each pleat 16 is about 1.125 inches.
[0063] It is envisioned that adjoining or otherwise adjacent
circumferentially disposed arcuate pleats 16 of the inner filter
sleeve 12, the outer filter sleeve 14 or both the inner and outer
filter sleeves 12, 14 and are uniformly distributed about the
circumference of the inner and outer filter sleeves 12, 14. That
is, the pleats are uniformly spaced from one another, so that there
is no pleat overlap, as shown for example in FIG. 4. In other
words, the crown or top of each pleat 16 resides at or near the
root or base of an adjoining pleat 16, unlike conventional radially
pleated cartridges wherein the roots and crowns of the pleats are
radially spaced from one another. Consequently, the inner and outer
filter sleeves 12, 14 of filter assembly 10 have a substantially
continuous radial thickness t.sub.R equal to three (3) times the
thickness of a pleat leg, about substantially the entire
circumference of each filter sleeve. In this instance, the
circumference "C" of each filter sleeve 12, 14 is defined by the
following equation: C=h.sub.iN where N is the number of pleats
forming the filter sleeve.
[0064] It is also envisioned that adjoining or otherwise adjacent
circumferentially disposed arcuate pleats 16 of the inner filter
sleeve 12, the outer filter sleeve 14, or both the inner and outer
filter sleeves 12, 14 partially overlap one another. In accordance
with the subject disclosure, adjoining or otherwise adjacent
circumferentially disposed arcuate pleats 16 of the inner filter
sleeve 12, the outer filter sleeve 14 or both the inner and outer
filter sleeves 12, 14 can overlap one another over approximately
50% to 80% of the arc length of the pleats, measured relative to
the amount the inner pleat leg 16a of one pleat overlaps the inner
pleat leg 16a of an adjoining pleat.
[0065] In one example shown in FIG. 5, the pleats 16 of both the
inner and outer filter sleeves 12, 14 overlap one another over
approximately 50% of the arc length of the pleats. Consequently,
the inner and outer filter sleeves 12, 14 have a substantially
continuous radial thickness t.sub.R equal to five (5) times the
thickness of a pleat leg, about substantially the entire
circumference of each filter sleeve. In this instance, the
circumference "C" of each filter sleeve 12, 14 is defined by the
following equation: C=h.sub.iNO.sub.p where N is the number of
pleats forming the filter sleeve and O.sub.p is the percentage of
overlap that exists between two adjacent pleats in the filter
sleeve.
[0066] Thus, if the arc length or arcuate height h.sub.i of the
radially inner leg 16a of each pleat 16 is about 1.0 inch and the
arc length or arcuate height h.sub.o of the radially outer leg 16b
of each pleat 16 is about 1.5 inches, one-third of the arcuate
pleat height or 0.5 inches of the upstream and downstream surfaces
of the outer pleat leg 16b of each pleat 16 will be exposed or
otherwise out of contact with the surface of an adjacent pleat leg.
Similarly, if the arc length or arcuate height h.sub.i of the
radially inner leg 16a of each pleat 16 is about 0.75 inches and
the arc length or arcuate pleat height h.sub.o of the radially
outer leg 16b of each pleat 16 is about 1.125 inches, one-third of
the arcuate pleat height or 0.375 inches of the upstream and
downstream surfaces of the outer pleat leg 16b of each pleat 16
will be exposed or otherwise out of contact with the surface of an
adjacent pleat leg.
[0067] In accordance with the subject disclosure, the total amount
of overlap O.sub.T that exists between adjacent pleats 16 in a
filter sleeve 12, 14 is defined by the following equation:
O.sub.T=h.sub.iO.sub.p
[0068] Referring to FIG. 6, as mentioned above, inlet cap 22 is
secured to the upper end of the inner and outer filter sleeves 12,
14. Specifically, the multi-layered composite structure of filter
sleeves 12, 14 is ultrasonically welded, heat bonded or otherwise
secured to the inlet cap 22 using any commonly known attachment
method. The upper portion of the inner pleated filter sleeve 12 is
directly secured to the outer peripheral surface of wall 42 of the
inner body portion 22a of inlet cap 22. Similarly, the upper
portion of the outer pleated filter sleeve 14 is directly secured
to the outer peripheral wall 44 of the outer flange portion 22b of
inlet cap 22.
[0069] Referring to FIG. 7, as mentioned above, end cap 26 is
secured to the lower end of the inner and outer filter sleeves 12,
14. Specifically, the multi-layered composite structure of filter
sleeves 12, 14 is ultrasonically welded, heat bonded or otherwise
secured to the end cap 26 using any commonly known attachment
method. The lower portion of the inner pleated filter sleeve 12 is
directly secured to the outer peripheral surface of an upstanding
flange wall 46 of end cap 26. Similarly, the lower portion of the
outer pleated filter sleeve 14 is directly secured to the outer
peripheral surface of wall 48 of the end cap 26.
[0070] Those skilled in the art will readily appreciate that
securing the filter sleeves 12, 14 to exterior or outer peripheral
surfaces of the inlet cap 22 and end cap 26, as explained above,
allows for more flexibility and lower costs during assembly. Those
skilled in the art will also appreciate that by welding, bonding or
otherwise sealing the media and support layers to each other at
both ends of filter assembly 10, in the manner described above and
illustrated in FIGS. 6 and 7, unfiltered fluid must flow through
all of the media layers of the filter sleeves 12, 14. This
eliminates any chance of bypass and premature plugging of the final
filter layers, and allows the user to get the maximum life out of
the filter assembly 10 of the subject disclosure. This is in
contrast to typical pleated cartridge filters, which are assembled
with ends caps that are typically potted or otherwise bonded to the
opposed ends of the pleats, making bypass possible if the pleat
ends are not completely encased.
[0071] Referring now to FIG. 8, in use, the collapsible bag-type
filter assembly 10 of the subject disclosure is disposed within a
perforated basket or container 50, which is preferably metal. At
such a time, the circumferential pleats 16 of the outer filter
sleeve 14 are fully supported by the outer portion 50a of basket 50
and each other and therefore they will not shift during use.
Additionally, the circumferential pleats 16 of the inner filter
sleeve 12 are fully supported by the inner portion 50b of basket 50
and each other. Consequently, they will not shift during service.
This allows for consistent pressure drops and longer filter life.
The basket 50 is supported with a housing or pressure vessel 52,
which has a removable top or cover 54. When the basket 50 is
disposed within the housing 52, the over-molded elastomeric sealing
surface 29 on the outer shoulder 22c of inlet cap 22 seals against
the surface of housing cover 54. In addition, a pair of O-rings
55a, 55b, disposed about the upper end of the inlet conduit 56 of
pressure vessel 52 sealingly engage the circumferential wall of the
central access port 23 of inlet cap 22.
[0072] In operation, the inlet conduit 56 delivers unfiltered fluid
into the trough formed by inlet cap 22, as indicated by the
directional flow lines. The unfiltered fluid then flows through the
plural inlet apertures 24 in inlet cap 22 and into the interior
passage 18 formed between the inner and outer filter sleeves 12, 14
of filter assembly 10. Under pressure, the fluid is drawn through
the pleated media layers of the inner and outer filter sleeves 12,
14 for filtration and conditioning. Thereafter, filtered fluid
exits filter housing 52 through outlet conduit 58 at the bottom of
the housing, as indicated by the directional flow lines.
[0073] Those skilled in the art will readily appreciate that the
arrangement of the basket 50 and housing 52 illustrated in FIG. 8
is a non-limiting example of a system within which the filter
assembly 10 may be employed. It is envisioned that the filter
assembly 10 of the subject disclosure may be employed with other
types of arrangements and systems without departing from the spirit
or scope of the subject disclosure.
[0074] When the bag-type filter assembly 10 of the subject
disclosure has exceeded its useful life, it may be easily removed
from the housing 52. Upon removal, filter assembly 10 may be
collapsed. This is accomplished by approximating the inlet cap 22
toward the end cap 26. The collapsed filter assembly may then be
discarded. It should be appreciated by those skilled in the art
that the size of the interior passage 18 of filter assembly 10 is
relatively small as compared that of a standard bag-type filter
which has only one filter media sleeve. Therefore, the hold-up
volume associated with filter assembly 10 is substantially reduced
as compared to a typical bag-type filter. The low hold-up volume
promotes easy removal of the filter assembly 10 from the housing
52, and minimizes fluid loss, which can result in contamination of
the area around the housing.
[0075] Referring now to FIGS. 9 and 10, there is illustrated a
pleat formation designated by reference numeral 200, which is used
to form the circumferential pleats of the inner and outer filter
sleeves of the filter assembly of the subject disclosure. Pleat
formation 200 includes upstanding pleats 216, each having first and
second pleat legs 216a and 216b of equal height. In pleat formation
200, the first pleat leg 216a of one pleat 216 is joined to the
second pleat leg 216b of a preceding pleat 216 by a flat medial
pleat section 216c.
[0076] When the circumferential pleats of the subject disclosure
are formed, the upstanding pleats 216 of pleat formation 200 are
moved into an overlapped condition, which is shown in FIG. 11. In
this overlapped condition, each medial pleat section 216c becomes
part of the second leg 216b of a preceding pleat 216'. By way of
example, if the height of each pleat leg 216a, 216b is 1.0 inch,
and the length of the medial pleat section 216c is 0.050 inches,
the resulting circumferential pleats 216' shown in FIG. 18 will
each have a radially inner pleat leg with an arc length of 1.0 inch
and a radially outer pleat leg with an arc length of 1.50
inches.
[0077] Referring to FIGS. 12 and 13, there is illustrated another
pleat formation designated by reference numeral 300, which is used
to form the circumferential pleats of the inner and outer filter
sleeves of the filter assembly of the subject disclosure. Pleat
formation 300 includes upstanding pleats 316, each of which has
first and second pleat legs 316a and 316b of equal height. In pleat
formation 300, the first pleat leg 316a of one pleat 316 is joined
to the second pleat leg 316b of a preceding pleat 316 by a medial
pleat section that includes two medial pleat segments 316c and 316d
of equal length "1". Thus, pleat formation 300 takes the form of a
W-shape construction, consisting essentially of alternating tall
and short pleats.
[0078] When the circumferential pleats of the subject disclosure
are formed, the two medial pleat segments 316c and 316d are splayed
out, collapsed or otherwise flattened by moving in the direction
indicated by arrow "x". The pleats 316 are then moved into an
overlapped condition. In this condition, which is shown in FIGS. 14
and 15, the two medial pleat segments 316c and 316d become part of
the second leg 316b of a preceding pleat 316. By way of example, if
the height of each pleat leg 316a, 316b is 1.0 inch, and the length
of each medial pleat segment 316c, 316d is 0.25 inches, the
resulting circumferential pleats 316' will have a radially inner
pleat leg with an arc length of 1.0 inch and a radially outer pleat
leg with an arc length of 1.50 inches.
[0079] It is envisioned that the W-shaped configuration of pleat
formation 300 can be employed to maintain adjacent pleat surfaces
of the filter sleeves in spaced apart relationship, so that they do
not contact one another over the majority of the axial length of
the filter sleeves, and thus there is less restriction to flow
through the sleeves. In this instance, surface-to-surface pleat
contact would mainly occur at the opposed ends of the two filter
sleeves, where the sleeves are sealed or otherwise affixed to the
end caps. Alternatively, it is envisioned that the circumferential
pleats formed by the W-shaped composite, could be secured in place
using spot welds or a similar technique, so that the medial pleat
are maintained in a flattened state.
[0080] Referring to FIGS. 16 and 17, there is illustrated another
pleat formation designated by reference numeral 400, which is used
to form the circumferential pleats of the inner and outer filter
sleeves of the filter assembly of the subject disclosure. Pleat
formation 400 includes upstanding pleats 416, each having first and
second pleat legs 416a and 416b. In pleat formation 400, the first
pleat leg 416a of each pleat 416 is longer than the second pleat
leg 416b of each pleat 416. In addition, the first pleat leg 416a
of one pleat 416 is joined to the second pleat leg 416b of a
preceding pleat 416 by a medial pleat section that includes two
medial pleat segments 416c and 416d of different length.
Preferably, the length of the leading medial pleat segment 416c is
less than the length of the trailing medial pleat segment 416d.
[0081] The medial pleats segments 416c, 416d are asymmetric and
thus a preferential collapse zone is defined along the length of
the longer trailing segment 416d. When the circumferential pleats
416' are formed, the two medial pleat segments 416c and 416d are
collapsed or otherwise flattened out by moving in the direction
indicated by arrow "x" to become part of the second leg 416b of a
preceding pleat 416', as shown in FIG. 18.
[0082] Although the circumferentially pleated bag-type filter
assembly of the subject disclosure has been described with respect
to several presently preferred embodiments, those skilled in the
art will readily appreciate that modifications or changes may be
made thereto without departing from the spirit and scope of the
present disclosure as defined by the appended claims.
* * * * *