U.S. patent number RE32,851 [Application Number 07/163,633] was granted by the patent office on 1989-01-31 for fluid filter.
This patent grant is currently assigned to North American Filter Corporation. Invention is credited to Frederick E. Tarala.
United States Patent |
RE32,851 |
Tarala |
January 31, 1989 |
Fluid filter
Abstract
An improved fluid filter element and a filter medium therefor
include a rigid core having a coupling member attached at each end
for absorbing axial stress. A filter medium includes a plurality of
pockets and first and second neck portions sealingly attached to
said coupling member.
Inventors: |
Tarala; Frederick E.
(Pittsford, NY) |
Assignee: |
North American Filter
Corporation (Newark, NY)
|
Family
ID: |
26859817 |
Appl.
No.: |
07/163,633 |
Filed: |
March 3, 1988 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
666503 |
Oct 30, 1984 |
04615803 |
Oct 7, 1986 |
|
|
Current U.S.
Class: |
210/455; 210/457;
210/487; 55/497; 55/500 |
Current CPC
Class: |
B01D
29/395 (20130101); B01D 46/0005 (20130101); B01D
46/0012 (20130101); B01D 46/08 (20130101); B01D
2271/02 (20130101) |
Current International
Class: |
B01D
46/24 (20060101); B01D 46/52 (20060101); B01D
46/08 (20060101); B01D 46/02 (20060101); B01D
29/39 (20060101); B01D 027/04 (); B01D
027/06 () |
Field of
Search: |
;210/455,457,487,232,322,323.1,330,331,345,346,347,450,451,461,486
;55/497,500,492,498,521,529 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Fisher; Richard V.
Assistant Examiner: Millard; Wanda L.
Attorney, Agent or Firm: Cumpston & Shaw
Claims
I claim:
1. A filter medium for a fluid filter element comprising;
a continuous elongated web of filter material having.Iadd.;
.Iaddend.
a plurality of spaced-apart tabs along at least one edge of said
web;
at least .Iadd.a .Iaddend.first .[.and second parallel seams.].
.Iadd.seam .Iaddend.along said at least one edge .[.forming.].
.Iadd.joining adjacent portions of said elongated web to form
.Iaddend.a plurality of pockets.[.; at least one further seam.].
.Iadd.and .Iaddend.joining adjacent edges of adjacent ones of said
tabs, .[.said further seam intersecting at least one of said first
and second parallel seams,.]. whereby said filter element
includes;
a generally tubular central core having a neck portion at one end
of said core and a plurality of pockets extending radially
outwardly from said core.
2. The filter of claim 1 wherein said .[.seams are.]. .Iadd.seam is
.Iaddend.stitched.
3. The filter of claim 1 wherein said .[.seams are.]. .Iadd.seam is
.Iaddend.welded.
4. The filter of claim 1 wherein said .[.seams are.]. .Iadd.seam is
.Iaddend.within said pockets.
5. A fluid filter element comprising;
a substantially rigid perforated cylindrical core;
a filter medium supporting frame having a plurality of leaves
extending radially outwardly from said core;
means attaching said frame to said core;
a coupling member attached at one end to said core and at the
opposite end to a radially extending flange, said flange having a
gasket receiving surface thereon, whereby sealing forces applied to
said flange are transmitted to said core member and not to said
filter medium supporting frame.
6. The filter element of claim 5 wherein said coupling member
comprises a tubular body having a circumferential sealing surface
and an annular flange sealingly attached at said opposite end.
7. The filter element of claim 6 further comprising a filter medium
having an elongated tubular body having a generally cylindrical
neck portion at each end thereof and a plurality of pockets
extending radially outwardly from said body and attached to said
body and at each end to said neck portions; .[.first.]. and
.[.second seams.]. .Iadd.a seam .Iaddend.on each of said pockets,
said .[.seams.]. .Iadd.seam .Iaddend.sealing said .[.pockets.].
.Iadd.pocket .Iaddend.and sealing said .[.pockets.]. .Iadd.pocket
.Iaddend.to said neck .[.portions.]. .Iadd.portion.Iaddend..
8. A fluid filter comprising;
a substantially rigid core;
a filter medium supporting frame attached to said core;
a filter medium mounted on said supporting frame;
a coupling member attached to said core having a first sealing area
for sealing to said medium and a second sealing area for making an
external connection to said filter;
means for attaching said filter medium to said coupling member at
said first sealing area.
9. The filter of claim 8 wherein said coupling member comprises a
tubular body and an end flange attached to said body.
10. The filter of claim 9 wherein said first sealing area comprises
an outer circumferential surface of said body.
11. The filter of claim 10 wherein said second sealing area
comprises a flat surface portion of said flange.
12. The filter of claim 10 wherein said means attaching said filter
medium to said coupling member comprises a band clamp.
13. In a filter element of the type including a substantially rigid
tubular core, a supporting frame and first and second attaching
clips, each .Iadd.clip .Iaddend.having a core engaging portion and
a frame engaging portion, said clips disposed at opposite ends of
said core and engaging said core and said frame, the improvement
for reducing leakage comprising:
a filter medium supported by said frame and having a generally
cylindrical neck portion and a .[.U-shaped.]. .Iadd.folded over
.Iaddend.end portion; and
gasket means engaging said end portion;
means for compressing said gasket means and said end portion into
sealing engagement with said clip without exerting compressive
forces on said frame.
Description
This invention relates in general to fluid filters and more
particularly to an improved construction for filters of the type
having removable filter elements and cleanable or replaceable
filter media.
Fluid filters, including filters for liquids and gases, are in
widespread use. It is an advantage in such filters to provide a
filter medium that is supported in use in a manner substantially
eliminating leaks and which permits removal for cleaning or
replacement as required. In the past, providing a substantially
leak-free removable filter medium has been difficult. The point at
which the filter medium is attached to the supporting structure
therefor has been particularly susceptible to leakage.
Time-consuming and expensive manufacturing operations have been
brought to bear on this problem, including utilization of multiple
forms of attachment of the filter medium, such as sewing, gluing,
fabric welding and the like.
It has been another problem with filter constructions heretofore
known that when such filters were installed in a housing, the
formation of a leak-proof seal between the filter element and the
remaining elements of the filtration system has tended to reduce
the efficiency of the filter. Particularly, where such filters have
utilized gaskets in a pressure seal, the force necessary to create
an effective leak-proof seal to the gasket has, due to the
construction of the filters, caused deformation of the
filter-medium supporting frame and reduced the efficiency of the
filters.
Exemplary filters in accordance with the prior art are shown in
U.S. Pat. Nos. 1,218,848; 2,420,414; 3,486,626; 3,633,753 and
3,633,757. Additionally, still more recent constructions are known
and will be illustrated in the accompanying drawings.
It is an object of this invention to provide a fluid filter that
eliminates a potential leakage path that was present in prior art
filters.
It is another object of this invention to provide a fluid filter
having a removable filter medium adapted for field removal,
cleaning and replacement.
It is another object of this invention to provide a fluid filter
having improved fluid flow characteristics and reduced pressure
drop compared with prior art filters.
It is still another object of this invention to provide a fluid
filter having improved structural rigidity.
Briefly stated and in accordance with a presently preferred
embodiment of this invention, a fluid filter includes a
substantially rigid perforated core and a supporting frame having a
plurality of radial leaves extending outwardly from said core. A
coupling member extends axially outwardly from and is supported by
the core and includes a collar and a radially extending flange. A
filter medium having a neck portion and a plurality of pockets is
mounted on said radially-extending leaves with one leaf extending
into each pocket and the neck portion attached to the cylindrical
collar portion of the coupling member with a clamp. The
radially-extending flange is adapted to receive a gasket for
providing a seal to the filter element.
In accordance with another embodiment of this invention, the
cylindrical neck portion of the filter medium is folded back over
itself and a sealing washer is adhesively secured to the inside
surface of the neck portion of the filter medium.
While the aspects of the invention that are regarded novel are
described with particularity in the appended claims, the invention
itself, together with further advantages and features thereof, may
be more readily understood by reference to the following detailed
description taken in connection with the accompanying drawings in
which:
FIG. 1 is a cut-away view of a filter assembly of the type in which
a filter element in accordance with this invention may be used;
FIG. 2 is a fragmentary side elevational view, partly in section,
of a filter element in accordance with the prior art;
FIG. 3 is a side view in partial section of the filter assembly of
FIG. 2;
FIG. 4 is a fragmentary plan view of the filter element of FIG.
2;
FIG. 5 is a fragmentary side elevational view of the filter element
of FIG. 2 showing deformation in use;
FIG. 6 is another view of the filter element of FIG. 5;
FIG. 7 is a fragmentary side elevational view, partly in section,
of a filter element in accordance with this invention;
FIG. 8 is a partial side elevational view of a further embodiment
of this invention; and
FIG. 9 is a partial side elevational view of still another
embodiment of this invention.
FIGS. 10 and 11 are side elevational views of a filter medium in
accordance with this invention.
Turning now to FIG. 1, a filter assembly 10 in accordance with the
prior art is illustrated having a housing including a hollow
tubular body 12 and an end cap 14 forming a sealed inner chamber
16. An inlet pipe 20 passes through housing 10 and communicates
with chamber 16. A filter element 24 is disposed within chamber 16.
Filter element 24 is adapted to pass the filtrate through a filter
medium and out an exit pipe 30. The direction of fluid flow is
shown generally by arrows 32.
Conventionally, filter element 24 is sealed at one end by a gasket
34 and a sealing plate 36, which are held in position by any
convenient means, such as nut and bolt 38 and 40 that extend
axially through the filter element. A similar gasket 42 and plate
44, preferably threaded to receive outlet pipe 30, are employed at
the opposite end of filter element 24.
Further details of the construction of a removable filter element
24 in accordance with the prior art may be seen by referring now to
FIG. 2. In this and the remaining figures, like and corresponding
elements are designated by like reference numerals.
FIG. 2 is a side elevational view of a portion of filter element 24
showing parts thereof in section. Filter element 24 comprises a
generally cylindrical hollow core 50 and a filter medium supporting
frame 52 that comprises a web of preferably resilient lattice
material, such as a wire lattice formed into a circular array of
outwardly extending leaves. Frame 52 is attached to core 50 by
generally U-shaped attaching bracket 54 that has a cylindrical
inner portion engaging the inner surface of core 50, an outwardly
extending flange 56 transversing the end of core 50 and a plurality
of fingers 58 engaging inner bights of the filter medium supporting
frame 52 between adjacent leaves. Reference may also be made to
FIG. 4 in which this structure is shown in top view.
A filter medium 60 is carried by supporting frame 52. Preferably,
filter medium 60 is made of a material capable of passing the
filtrate while blocking the passage of impurities. Woven and
nonwoven sheets of fiber, both natural and artificial, are known to
provide this function. Conventionally, filter medium 60 is formed
from a sheet of filter material sewn to provide a plurality of
pockets therein, each pocket carried by one leaf of the supporting
frame.
A side elevational view, partly in section, of three adjacent
leaves of supporting frame 52 showing filter medium 60 thereon, is
illustrated at FIG. 3. A top view of this same structure appears at
FIG. 4. Reference to FIGS. 2-4 reveals that the filter medium is
formed into a serpentine arrangement and pockets are formed by
fastening adjacent portions together along the top and bottom
edges, for example by stitching, welding or the like. The top of
each pocket is folded over to provide a surface for attaching a
gasket 34. Typically, gasket 34 is attached to the surface formed
by folded-over upper portions 62 of filter medium 60 by gluing,
sewing or the like to provide a seal between the gasket and the
filter medium.
Reference to FIGS. 2-4 reveals a number of problems associated with
prior art filter constructions. While folded-over upper portions or
flaps 62 have been required to provide a sealing surface for
attaching gasket 34, these flaps impair the flow of filtrate
through the filter element by closing off the upper and lower
portions of the spaces between adjacent pockets of filter medium.
As such, increased pressure drops have been produced by prior art
filters utilizing this construction.
Additionally, this prior art construction is particularly
susceptible to leakage as may be most readily seen in FIG. 4 where
arrow 64 shows a path along which leakage commonly occurs. Leakage
at this point is almost impossible to avoid because of the fold
naturally formed in the top edge of the filter medium when flaps 62
are bent over to form the sealing surface.
A still further disadvantage of the prior art construction may be
appreciated by referring now to FIG. 5. Since gasket 34 is sealed
to flaps 62 by gluing or sewing as heretofore described, and to
plate 36 by pressure, pressure is exerted on supporting frame 52
when the filter element is installed in the housing. Deformation of
frame 52 results from the pressure exerted on the filter element by
plate 36 when the element is placed under pressure to form a seal
to gasket 34. As seen in FIGS. 5 and 6, such deformation causes
supporting frame 52 to deflect outwardly from core 50 and adjacent
leaves of the frame to deflect towards each other thereby reducing
the interleaf space, impeding the flow of filtrate and increasing
the pressure drop across the filter. In some cases, pressure on
frame 52 was sufficient to depress the upper edge of the frame out
of engagement with fingers 58 whereupon the filter would partially
disassemble and be rendered ineffective.
These and other disadvantages of prior art filter constructions are
eliminated by Applicant's new filter shown in FIGS. 7-9. FIG. 7 is
a fragmentary side elevational view, partly in section, of a filter
in accordance with this invention. The filter element designated
generally at 65 includes a cylindrical perforated core 50 of
conventional design. A supporting frame 52 is positioned around
core 50 and is attached thereto by attaching ring 54 that, along
with core 50, is conventional and is constructed as heretofore
described in connection with FIGS. 1-6.
A coupling member 66 is attached to ring 54 and includes a
generally cylindrical neck portion 68 having a flange 70 extending
outwardly therefrom at one end of the coupling member. Preferably,
coupling member 66 is a cylindrical metal member attached to
attaching ring 54 and core 50 by welding, riveting or the like, in
a manner to securely them, but not necessarily to form a seal.
Flange 70 of coupling member 66 is spaced above flange 56 of
attaching ring 54 to form a sealing area 72.
A filter medium 74 comprises a web of filter material sealed at the
top and bottom edges thereof to form a plurality of pockets, each
adapted to receive one leaf of supporting frame 52.
Preferably, filter medium 74 is sealed at the top and bottom edges
by parallel seams 76 that extend along the top of each pocket and
join into a single seam at a neck portion of filter medium 74.
It is preferred, in accordance with this invention and as shown in
FIGS. 10 and 11, to form filter medium 74 from an elongated web of
filter material 90 having a plurality of spaced-apart tabs at the
upper 91, 92 and lower 93, 94 edges thereof whereby the filter
medium shown in FIG. 11 can be formed by folding the material along
lines 102 to form bights between adjacent portions of the filter
material. The filter medium is then sealed along the dotted lines
as exemplified by lines 96, 98 and 100 at the top and bottom edges
of such material and along adjacent side portions of adjoining tabs
whereby a filter medium having a plurality of pockets 104 extending
radially outwardly from upper 78 and lower (not shown) neck
portions is provided.
A clamp 80, as seen in FIG. 7, holds neck portion 78 of filter
medium 74 in sealing engagement with neck 68 of coupling member 66.
A gasket 82 is preferably disposed on an upper surface of flange 70
when the filter assembly is in use.
It will be appreciated that the filter structure shown in FIG. 7
completely eliminates the problems heretofore discussed in
connection with prior art filter constructions. Because gasket 82
is supported by coupling member 66 that is mechanically attached to
core 50, deformation of frame 52 does not occur when the filter
element in accordance with the invention is installed in a filter
assembly. Sealing pressure is transmitted by coupling member 66 to
core 50 that may be made sufficiently rigid to absorb such stress
without significant deformation. Deformation of frame 52 is
eliminated and the pressure drop across the filter is maintained at
a constant level. Further, because clamp 80 provides a seal to
coupling member 66 which does not rely on sewing or gluing a gasket
to the filter medium, the necessity for providing flaps to form a
sealing surface at each end of the filter element is eliminated and
the flow of filtrate past the leaves of the filter element is
greatly enhanced. Still further, the inherent tendency of the prior
art construction to leak at the point where the gasket was attached
to the filter element is completely eliminated.
A modification of the filter construction shown in FIG. 7 is
illustrated at FIG. 8 wherein the construction is identical to that
shown in FIG. 7, except that the filter medium is, in essence,
turned inside out so that seams 76 are within the pockets formed in
the filter medium, thereby providing a still further improvement in
flow characteristics and reduction in back pressure.
A filter element in accordance with an alternative embodiment of
this invention is illustrated at FIG. 9. A tubular central core 50,
preferably formed of perforated metal, is provided. An attaching
ring 54 is disposed at each end of core 50 for attaching frame 52
to the core. These elements are identical to those heretofore
described in connection with the embodiments of this invention
illustrated at FIGS. 7-8. A filter medium 74, identical in
structure to the filter medium heretofore described, is carried by
frame 52. The neck portion 86 of filter medium 74 is folded back
over itself to form a U-shaped bight disposed on horizontal flange
56 of bracket 54. An inner sealing surface 84 of neck 86 is
attached, by gluing, sewing or the like, to a gasket 82. A sealing
plate 36 is employed to compress gasket 82 and folded-over neck
portion 86 of sealing medium 74 between plate 36 and bracket
54.
It will be seen that this construction eliminates the deformation
of frame 52 that was a problem in prior art filter constructions.
Further, since a sealing surface 84 is provided that is radially
inward of the top edges of the radially extending flaps of filter
medium 74, the upper edges of such flaps need not be folded over
and the flow between such flaps is greatly enhanced. Still further,
the leakage path present in prior art constructions as shown in
FIG. 4 is eliminated by this embodiment of the invention.
Preferably, the flaps are sealed by first and second spaced
parallel seams that may be ultrasonically welded, sewn or the like,
and which join into a single seam at neck portion 86 of filter
medium 74.
While the invention has been shown in connection with certain
presently preferred embodiments thereof, those skilled in the art
will recognize that many modifications may be made therein without
departing from the true spirit and scope of the invention which
accordingly, is intended to be defined solely by the appended
claims.
* * * * *