U.S. patent application number 13/093159 was filed with the patent office on 2011-08-18 for modular filter assembly.
This patent application is currently assigned to Porex Corporation. Invention is credited to Dean Haldopoulos, Benjamin Hirokawa.
Application Number | 20110198301 13/093159 |
Document ID | / |
Family ID | 38802098 |
Filed Date | 2011-08-18 |
United States Patent
Application |
20110198301 |
Kind Code |
A1 |
Haldopoulos; Dean ; et
al. |
August 18, 2011 |
Modular Filter Assembly
Abstract
Disclosed herein are modular filter assemblies having a
plurality of stacked filter plates formed from a porous material.
The filter plate can comprise a planar base portion from which a
convoluted ridge wall, having a ridge outer side surface, a ridge
inner surface, and a top ridge surface extends. A plurality of
fluid inlet troughs and a plurality if fluid outlet troughs are
defined by the ridge wall. Adjoining filter plates form a plurality
of fluid inlet cavities defined by the fluid inlet trough of one
filter plate and a portion of the bottom surface of the adjoining
filter plate; and a plurality of fluid outlet cavities defined by
the fluid outlet trough of the one filter plate and a portion of
the bottom surface of the adjoining filter plate. In use, the
plurality of fluid inlet cavities are in filtered communication
with the plurality of fluid outlet cavities.
Inventors: |
Haldopoulos; Dean; (Atlanta,
GA) ; Hirokawa; Benjamin; (Atlanta, GA) |
Assignee: |
Porex Corporation
Fairburn
GA
|
Family ID: |
38802098 |
Appl. No.: |
13/093159 |
Filed: |
April 25, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11756509 |
May 31, 2007 |
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13093159 |
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60810010 |
May 31, 2006 |
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60809981 |
Jun 1, 2006 |
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Current U.S.
Class: |
210/767 ;
210/230; 210/231 |
Current CPC
Class: |
B01D 25/26 20130101 |
Class at
Publication: |
210/767 ;
210/231; 210/230 |
International
Class: |
B01D 25/02 20060101
B01D025/02; B01D 25/00 20060101 B01D025/00 |
Claims
1-24. (canceled)
25. A modular filter assembly, comprising: a plurality of stacked
filter plates formed from a porous material, each filter plate
comprising: a planar base portion having an outer peripheral edge,
a top surface, and a bottom surface, and further defining at least
one opening extending therebetween the respective top and bottom
surface; a convoluted ridge wall extending from the top surface of
the base portion and having a ridge outer side surface, a ridge
inner side surface, and a top ridge surface, the convoluted wall
surrounding the at least one opening; a plurality of fluid inlet
troughs defined by the ridge outer side surface and a first portion
of the base portion top surface; and a plurality of fluid outlet
troughs defined by the ridge inner side surface and a second
portion of the base portion top surface; wherein at least a first
and a second filter plate of the plurality of filter plates are
stacked such that the ridge top surface of the first plate is
contacting the bottom surface of the second plate; a plurality of
fluid inlet cavities defined by the fluid inlet trough of the first
filter plate and a first portion of the bottom surface of the
second filter plate; and a plurality of fluid outlet cavities
defined by the fluid outlet trough of the first filter plate and a
second portion of the bottom surface of the second filter plate;
wherein the plurality of fluid inlet cavities are in filtered
communication with the plurality of fluid outlet cavities such that
a fluid passing from the fluid inlet cavity to the fluid outlet
cavity must pass through at least one of the ridge and filter plate
base portion.
26. The modular filter of claim 25, wherein the porous material
comprises a sintered thermoplastic material.
27. The modular filter of claim 25, wherein the plurality of filter
plates are identical.
28. The modular filter of claim 25, wherein the at least first and
second filter plates are stacked such that at least a portion of
the inlet troughs of the first filter plate are in underlying
registration with at least a portion of the outlet troughs of the
second filter plate.
29. The modular filter of claim 28, wherein the at least first and
second filter plates are stacked such that each inlet trough of the
first filter plate is in underlying registration with an outlet
trough of the second filter plate.
30. The modular filter of claim 25, wherein the convoluted ridge
wall is continuous.
31. The modular filter of claim 25, wherein the at least one
opening extending therebetween the respective top and bottom
surface has a peripheral edge defined by the plate base portion,
and wherein said peripheral edge further defines at least one key
for aligning the plurality of filter plates in a predetermined
pattern of overlying registration.
32. The modular filter of claim 25, wherein the plurality of filter
plates are stacked such that the at least one opening extending
therebetween the respective top and bottom surface of each filter
plate forms a conduit.
33. The modular filter of claim 32, wherein the plurality of fluid
outlet cavities are in communication with the conduit.
34. The modular filter of claim 32, further comprising a core
extending longitudinally through the at least one opening and
comprising opposing proximal and distal ends, a first end cap
affixed to the proximal end of the core proximate the top ridge
surface of the second filter plate, and a second end cap affixed to
the distal end of the core proximate the bottom surface of the
planar base portion of the first filter plate.
35. The modular filter of claim 25, wherein the outer peripheral
edge of the filter plate is substantially circular in shape.
36. The modular filter of claim 25, wherein the at least one
opening extending therebetween the respective top and bottom
surface of the filter plate base portion is positioned coaxially
with a longitudinal axis of the filter plate.
37. The modular filter of claim 25, wherein the at least one
opening extending therebetween the respective top and bottom
surface of the filter plate is substantially circular in shape.
38. A modular filter assembly, comprising: a plurality of stacked
filter plates formed from a porous material, each filter plate
comprising: a planar base portion having an outer peripheral edge,
a top surface, and a bottom surface; a convoluted ridge wall
extending from the top surface of the base portion and having a
ridge outer side surface, a ridge inner side surface, and a top
ridge surface; a plurality of fluid inlet troughs defined by the
ridge outer side surface and a first portion of the base portion
top surface; and a plurality of fluid outlet troughs defined by the
ridge inner side surface and a second portion of the base portion
top surface; wherein at least a first and a second filter plate of
the plurality of filter plates are stacked such that the ridge top
surface of the first plate is contacting the bottom surface of the
second plate; a plurality of fluid inlet cavities defined by the
fluid inlet trough of the first filter plate and a first portion of
the bottom surface of the second filter plate; and a plurality of
fluid outlet cavities defined by the fluid outlet trough of the
first filter plate and a second portion of the bottom surface of
the second filter plate; wherein the plurality of fluid inlet
cavities are in filtered communication with the plurality of fluid
outlet cavities such that a fluid passing from the fluid inlet
cavity to the fluid outlet cavity must pass through at least one of
the ridge and filter plate base portion.
39. The modular filter of claim 38, wherein the porous material
comprises a sintered thermoplastic material.
40. The modular filter of claim 38, wherein the plurality of filter
plates are identical.
41. The modular filter of claim 38, wherein the at least first and
second filter plates are stacked such that at least a portion of
the inlet troughs of the first filter plate are in underlying
registration with at least a portion of the outlet troughs of the
second filter plate.
42. The modular filter of claim 41, wherein the at least first and
second filter plates are stacked such that each inlet trough of the
first filter plate is in underlying registration with an outlet
trough of the second filter plate.
43. The modular filter of claim 38, wherein the convoluted ridge
wall is continuous.
44. A method of filtering a contaminant from a fluid stream
comprising the steps of: providing a plurality of filter plates
formed from a porous material each comprising: a planar base
portion having an outer peripheral edge, a top surface, and a
bottom surface; a convoluted ridge wall extending from the top
surface of the base portion and having a ridge outer side surface,
a ridge inner side surface, and a top ridge surface; a plurality of
fluid inlet troughs defined by the ridge outer side surface and a
first portion of the base portion top surface; and a plurality of
fluid outlet troughs defined by the ridge inner side surface and a
second portion of the base portion top surface; stacking at least a
first and second filter plate of the plurality of filter plates in
a stacked arrangement to form a modular filter assembly, wherein in
the stacked arrangement the ridge top surface of the first plate is
contacting the bottom surface of the second plate, a plurality of
fluid inlet cavities are defined by the fluid inlet troughs of the
first filter plate and a first portion of the bottom surface of the
second filter plate, and a plurality of fluid outlet cavities are
defined by the fluid outlet troughs of the first filter plate and a
second portion of the bottom surface of the second filter plate,
wherein the plurality of fluid inlet cavities are in filtered
communication with the plurality of fluid outlet cavities such that
a fluid passing from the fluid inlet cavity to the fluid outlet
cavity must pass through at least one of the ridge and filter plate
base portion; and passing a fluid containing a particulate
contaminant from at least one fluid inlet cavity to at least one
fluid outlet cavity.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. Nos. 60/810,010 filed May 31, 2006, and 60/809,981
filed Jun. 1, 2006, the entire contents of which are hereby
incorporated by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to the field of porous
filters and more particularly to modular porous filter assemblies
for filtration of fluids containing one or more contaminants.
BACKGROUND OF THE INVENTION
[0003] Filters for fluids, including liquids and gases, have been
known in the art. For instance, filters are commonly used in such
systems as air filtration systems, water filtration systems, water
purification systems, and the like. A common type of filter is a
cartridge-type filter with a replaceable filter typically mounted
on a core and placed into a filtration system. The replaceable
filter is typically formed from a porous, relatively soft material
having pores sized to prevent contaminants and/or other particles
(hereinafter "contaminants" for the sake of convenience and without
intent to limit) from flowing through the filtration system, while
letting the fluid pass therethrough. However, contaminants and
particles typically become embedded in such filters such that the
filters must be replaced on a regular basis.
[0004] Typically, cartridge-type filters are cylindrical elements
having a substantially open longitudinal center portion with
radially-outwardly extending, longitudinal folded portions or
pleats. A plurality of pleats is commonly arranged around a tubular
core defining a cylinder. When viewed in a transverse
cross-section, the pleats typically extend radially outward from
the core toward the outer periphery of the filter. A drawback of
this pleated design is that, because the filter industry has become
standardized, the overall dimensions of the filter body are
restricted and it therefore becomes difficult to increase the size
of a filter beyond the conventional dimension of the filter body.
Thus the filter capacity and effectiveness are limited by the
surface area of the filter cartridge.
[0005] Because the effectiveness of the standard cartridge-type
filter is generally a function of the surface area of the filter,
several attempts have been made to modify the pleat design in order
to increase the available surface area. For example, attempts have
been made to modify the length at which a pleat extends from the
center core toward the periphery of the cartridge. In one example,
an attempt has been made to form pleats that are radially curved
rather than having pleats that extend linearly from the core of the
cartridge. The increase in the length of each radially curved pleat
was intended to result in an increased surface area of the
filter.
[0006] Despite these several attempts, conventional filter
technology has been unable to achieve significant increases in
surface area while maintaining industry accepted standards for
overall filter dimensions. Accordingly, it would therefore be
desirable to form a filter that has an increased surface area for
removing contaminants from a fluid stream. The increase in surface
area could in turn provide for an increased filtering capacity,
and/or an increase in the effective service life of the filter.
SUMMARY OF THE INVENTION
[0007] The present invention relates, in part, to modular filter
assemblies that are suitable for use in filtration of any fluid,
including liquid or gas, that contains a contaminant. The inventive
filter assemblies can, in one aspect, provide an increased surface
area per unit of volume relative to those filters conventionally
know in the art. As such, the filters of the present invention can
in one aspect provide an increased filtering capacity for a given
volume of space. In another aspect, the inventive filter assemblies
of the present invention are readily customizable according to any
desired size and configuration at relatively low capital expense.
Still further, the filter assemblies of the present invention
provide improved resistant to the undesired affects that can
typically result from an increase in backpressures over the service
life of a filter. Therefore, in another aspect, the filter
assemblies of the present invention can provide an increased
effective service life over the conventionally known filters.
[0008] In one aspect, the present invention provides a filter
assembly comprised of a plurality of stacked filter plates formed
from a porous material. The filter plate can comprise a planar base
portion having an outer peripheral edge, a top surface, and a
bottom surface. A convoluted ridge wall extends from the top
surface of the base portion and has a ridge outer side surface, a
ridge inner side surface, and a top ridge surface. A plurality of
fluid inlet troughs is defined by the ridge outer side surface and
a first portion of the base portion top surface. A plurality of
fluid outlet troughs is defined by the ridge inner side surface and
a second portion of the base portion top surface. At least a first
and a second filter plate of the plurality of filter plates are
stacked such that the ridge top surface of the first plate contacts
the bottom surface of the second plate and to form: i) a plurality
of fluid inlet cavities defined by the fluid inlet trough of the
first filter plate and a first portion of the bottom surface of the
second filter plate; and ii) a plurality of fluid outlet cavities
defined by the fluid outlet trough of the first filter plate and a
second portion of the bottom surface of the second filter plate.
The plurality of fluid inlet cavities are in filtered communication
with the plurality of fluid outlet cavities such that a fluid
passing from the fluid inlet cavity to the fluid outlet cavity must
pass through at least one of the ridge and filter plate base
portion.
[0009] In another aspect, the present invention provides a method
of filtering a fluid filtrate comprising providing a modular filter
assembly as described above, in which the plurality of fluid inlet
cavities are in filtered communication with the plurality of fluid
outlet cavities such that a fluid passing from the fluid inlet
cavity to the fluid outlet cavity must pass through at least one of
the ridge and filter plate base portion; and passing a fluid
containing a particulate contaminant from at least one fluid inlet
cavity to at least one fluid outlet cavity.
[0010] In still another aspect, the present invention provides a
method for manufacturing the modular filter assemblies described
herein. The method generally comprises charging a desired porous
filter material precursor composition into a mold configured to
provide a filter plate having a desired size and shape. Once
charged, the porous filter material precursor composition can then
be sintered according to conventionally known sintering techniques
known to one of ordinary skill in the art. Any desired number of
filter plates can be prepared in order to provide a filter assembly
comprising a desired plurality of filter plates in a stacked
arrangement as described herein. It will be appreciated that,
contrary to the methods known in the art for preparing molded
filters, the method of the present invention does not require the
usage of a core pin in order to mold the individual filter plates.
As such, the concentricity of the inventive filter plates can be
more uniform, thus enabling the manufacture of a more efficient
filter assembly.
[0011] Additional aspects of the invention will be set forth, in
part, in the detailed description, figures and any claims which
follow, and in part will be derived from the detailed description,
or can be learned by practice of the invention. It is to be
understood that both the foregoing general description and the
following detailed description are exemplary and explanatory only
and are not restrictive of the invention as disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate several aspects
of the invention and together with the description, serve to
explain the principles of the invention.
[0013] FIG. 1 is a perspective view of a stackable linear flow
filter plate according to one aspect of the present invention.
[0014] FIG. 2 is a perspective view of a plurality of stacked
filter plates as shown in FIG. 1.
[0015] FIG. 3 is a perspective view of a stackable radial flow
filter plate according to one aspect of the present invention.
[0016] FIG. 4 is a perspective view of a plurality of stacked
filter plates as shown in FIG. 3.
[0017] FIG. 5 is a perspective view of two convoluted ridge
portions extending from the base plate portion of the filter plate
of FIG. 3.
[0018] FIG. 6 is a perspective view of an exemplary filter assembly
according to one aspect of the present invention.
[0019] FIG. 7 is a perspective view of a stackable linear flow
filter plate comprising support ribs, according to one aspect of
the present invention
[0020] FIG. 8A is a plan view of a filter plate defining a
plurality of apertures extending through the base plate portion,
according to one aspect of the present invention.
[0021] FIG. 8B. is a plan view of a filter plate comprising a
plurality of protrusions defining apertures therethrough, according
to one aspect of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The following description of the invention is provided as an
enabling teaching of the invention in its best, currently known
embodiment. To this end, those skilled in the relevant art will
recognize and appreciate that many changes can be made to the
various embodiments of the invention described herein, while still
obtaining the beneficial results of the present invention. It will
also be apparent that some of the desired benefits of the present
invention can be obtained by selecting some of the features of the
present invention without utilizing other features. Accordingly,
those who work in the art will recognize that many modifications
and adaptations to the present invention are possible and can even
be desirable in certain circumstances and are a part of the present
invention. Thus, the following description is provided as
illustrative of the principles of the present invention and not in
limitation thereof.
[0023] As used herein, the singular forms "a," "an" and "the"
include plural referents unless the context clearly dictates
otherwise. Thus, for example, reference to a "filter plate"
includes embodiments having two or more such filter plates unless
the context clearly indicates otherwise.
[0024] Ranges can be expressed herein as from "about" one
particular value, and/or to "about" another particular value. When
such a range is expressed, another embodiment includes from the one
particular value and/or to the other particular value. Similarly,
when values are expressed as approximations, by use of the
antecedent "about," it will be understood that the particular value
forms another embodiment. It will be further understood that the
endpoints of each of the ranges are significant both in relation to
the other endpoint, and independently of the other endpoint.
[0025] As used herein, the term or phrase "filtered communication"
is intended to include aspects where in order for a fluid to pass
from a fluid inlet cavity to a fluid outlet cavity, the fluid must
pass through a filter medium such as, for example, a porous
material. In one aspect, the porous filter medium can be a ridge
wall and/or a filter plate base portion.
[0026] As briefly summarized above, the present invention provides
a modular filter assembly suitable for filtering a fluid, e.g., a
liquid and/or a gas. Without limitation, the modular filters of the
present invention are well suited for use in such exemplary systems
as air filtration systems, water filtration systems, water
purification systems, and the like. One particular application for
the modular filter assembly of the present invention is in
recreational water filtration systems, such as pools, spas, hot
tubs, and the like.
[0027] With specific reference to the figures, a filter assembly
100 of the present invention is comprised of a plurality of stacked
filter plates 110 formed from a porous material. As shown in FIG.
1, each filter plate 110 comprises a planar base portion 112 having
an outer peripheral edge 114, a top surface 116, and a bottom
surface 118. A convoluted ridge wall 122 having a ridge outer side
surface 122(a), a ridge inner side surface 122(b), and a top ridge
surface 122(c) is formed on and extends therefrom the top surface
of the base portion. A plurality of fluid inlet troughs 130 are
defined by the ridge wall outer side surface 122(a) and a first
portion 116(a) of the base portion top surface. Likewise, a
plurality of fluid outlet troughs 132 are also defined by the ridge
wall inner side surface 122(b) and a second portion 116(b) of the
base portion top surface.
[0028] As shown in FIG. 2, a plurality of filter plates 110 can be
stacked such that the ridge top surface 122(c) of a first plate is
contacting the bottom surface 118 of an overlying second plate.
When stacked in this manner, a plurality of fluid inlet cavities
140 are thereby defined by the fluid inlet troughs of a first
filter plate and a first portion 118(a) of the bottom surface of an
overlying adjacent second filter plate. Likewise, a plurality of
fluid outlet cavities 142 (shown in FIG. 4) are also defined by the
fluid outlet troughs of the first filter plate and a second portion
118(b) of the bottom surface of the adjacent overlying second
filter plate. The resulting plurality of fluid inlet cavities are
thus in filtered communication with the plurality of fluid outlet
cavities such that any fluid passing from a fluid inlet cavity to a
fluid outlet cavity must pass through at least one porous ridge
wall and/or a porous filter plate base portion.
[0029] In one aspect, a plurality of filter plates 110 can be
stacked in a predetermined orientation such that at least a portion
of an inlet trough of a first filter plate is in underlying
registration with at least a portion of an outlet trough of an
adjoining filter plate. Still further, as shown in FIG. 2, a
plurality of filter plates 110 can also be stacked relative to one
another such that each inlet trough of the first filter plate is in
underlying registration with an outlet trough of the second filter
plate.
[0030] In forming a filter assembly of the present invention it
should be understood that the shape of a filter plate and the
corresponding configuration of the convoluted ridge wall can be
provided in any desired manner that is capable of forming a
plurality of inlet and outlet cavities when a plurality of the
filter plates are stacked as described herein. For example, as
shown in FIG. 1 and FIG. 2, the filter plates can be substantially
rectangular in shape having, a convoluted ridge wall forming a
plurality of substantially parallel closed end alternating inlet
and outlet troughs. In this aspect, when a plurality of identical
filter plates are stacked such that at least a portion of the inlet
troughs of the first filter plate are in underlying registration
with at least a portion of the outlet troughs of a second adjacent
overlying filter plate, the resulting filter assembly is well
suited for use as an in line or laminar flow filter.
[0031] In an alternative aspect, and as shown in FIG. 3, a
stackable filter plate can have a substantially circular outer
peripheral edge and a continuous convoluted ridge wall. The
circular shape enables the formation of a substantially cylindrical
filter assembly when a plurality of filter plates are stacked as
described herein, and as further shown in FIG. 4. The filter plate
base portion can define at least one opening 120 extending between
the respective top and bottom surface of a filter plate base
portion and positioned interior relative to the continuous
convoluted ridge wall such that the plurality of fluid outlet
troughs are in open fluid communication with the at least one
opening 120.
[0032] Once again, it is contemplated that the continuous
convoluted ridge wall can have any desired configuration that is
capable of defining a plurality of fluid inlet and fluid outlet
troughs as described herein. For example, as shown in FIG. 5, the
continuous convoluted ridge wall can have a first convoluted
portion 122(d) defining a first plurality of substantially parallel
inlet and outlet troughs, and an opposing second convoluted portion
122(e) defining a second plurality of substantially parallel inlet
and outlet troughs. The first plurality of inlet and outlet troughs
is positioned such that each inlet trough of the first plurality is
oppositely aligned with an outlet trough of the second plurality.
Likewise, each outlet trough of the first plurality is oppositely
aligned with an inlet trough of the second plurality. According to
this exemplified aspect of the invention, alternately stacked
filter plates can be oriented 180 degrees relative to an adjacent
filter plate such that at least a portion of the inlet troughs of a
first filter plate are in underlying registration with at least a
portion of the outlet troughs of a second adjacent overlying filter
plate. If desired, the peripheral edge of the least one opening
extending therebetween the respective top and bottom surface of the
base plate portion can further define at least one key 150 for
aligning the plurality of filter plates in a predetermined pattern
of overlying registration.
[0033] As shown in FIG. 4, a stacked plurality of filter plates
such as those shown in FIG. 3 can form a longitudinally extending
cylindrical filter assembly. Further, the at least one opening 120
extending therebetween the respective top and bottom surface of
each filter plate forms a longitudinally extending conduit 126 with
the at least one opening of adjacent overlying and/or underlying
filter plates. As further shown in FIG. 6, a plurality of stacked
filter plates 110, forming the longitudinally extending conduit
126, can be positioned on a tubular or cylindrical core 170. End
caps 160 can also be placed over the longitudinal ends of the
stacked filter assembly, to thereby retain the stacked filter
assembly in position relative to the core. The end caps can be used
to maintain the stacked filter assembly at a desired level of
compression. In use, a pressure gradient can be applied such that a
fluid is directed into the plurality of formed fluid inlet cavities
140 and must traverse through a ridge wall and/or filter plate base
portion to thereby enter a fluid outlet cavity in communication
with the conduit 126 an any optional core 170 disposed therein and
to filter out at least a portion of one or more contaminants within
the fluid.
[0034] In still another aspect, each of the plurality of filter
plates can further define one or more apertures 180 extending
through the planar base portion between the respective top and
bottom surface. In one aspect, the aperture(s) can be defined apart
from the at least one opening 120. For example, one or more
apertures 180 can be defined proximate the outer peripheral edge of
the base portion as illustrated in FIG. 8A. It is to be appreciated
that the filter plates shown in FIGS. 8A and 8B are top plan views
and are therefore shown without a convoluted ridge wall for
exemplary purposes only. As will be appreciated, the convoluted
ridge wall can be formed around the apertures in various manners as
described herein. In yet another aspect, the base portion can
comprise one or more protruding members 182 that protrude from the
outer peripheral edge, such as shown in FIG. 8B. According to this
aspect, each protruding member can define a respective aperture 180
extending therethrough. In either aspect, compression rods (not
shown) can be provided and positioned within respective apertures
of the plurality of filter plates to maintain the stacked filter
assembly under a desired level of compression. End caps can be
positioned on each end of the stacked arrangement and held in
compression by the compression rods. Although FIGS. 8A and 8B show
base plates defining four apertures, it is contemplated that any
number of apertures can be provided that allow the filter plates to
be held in compression by end caps.
[0035] In yet another aspect, it is contemplated that a plurality
of filter plates can be welded, adhered, or otherwise fastened
together so that the top ridge surface of the convoluted ridge wall
of a first filter plate is fixed to the bottom surface of the
planar base portion of a second filter plate. In this aspect, the
filter plates can optionally be assembled to form a modular filter
assembly without the use of compression means, such as compression
rods, end caps, central core, and the like.
[0036] The filter assembly 100 of the present invention can be used
for any fluids (i.e., liquids and gases), such as water, solvents,
air, or the like. According to an embodiment of the present
invention, filter 100 can be used in industrial or recreational
water filters as well as municipal filters. For example, a filter
formed in accordance with the principles of the present invention
can be used to remove other particles (e.g., sand) from water prior
to desalination for portable use. Furthermore, in an alternative
embodiment filter 100 can be used in a laboratory to filter
microbial contaminants from a solution.
[0037] As briefly summarized above, the filter assemblies of the
present invention can, in various aspects, provide several
advantages over the conventional filters known in the art. For
example, it will be appreciated upon practicing the present
invention that a filter assembly of the present invention can
comprise any number of filter plates in a stacked arrangement. As
such, the desired size of a filter assembly is easily customizable
by virtue of simply altering the desired number of filter plates in
a given stacked assembly. Additionally, the use of a plurality
stacked plates having relatively short convoluted ridge walls can
enable a relatively thinner convoluted ridge wall to be used while
still maintaining operability under increased backpressures that
may occur during the effective service life of the filter. To this
end, and without limitation, it is contemplated that the present
invention can provide filter plates having convoluted ridge walls
and planar base portions of any desired thickness. For example, in
one aspect the thickness of the convoluted ridge wall or planar
base portion can be less than 0.050 inches, less than 0.040 inches,
less than 0.030 inches, or even less than 0.020 inches.
[0038] Similarly, the height or distance that the convoluted ridge
wall extends from the base portion of a filter plate can be any
desired length or height and can vary depending on the intended use
of the filter. For example, and without limitation, the height of
the convoluted ridge wall can be at least 0.10 inches, at least
0.25 inches, at least 0.50 inches, 0.75 inches, or even at least
1.0 inches. To that end, as fluid enters the inlet troughs, the
force of the fluid can tend to push the ridge wall in the direction
of the flow. The forces may increase as the walls trap particulate
material in the filter media. Accordingly, with reference to FIG.
7, the ridge walls can be provided with support ribs 124 to support
the ridge walls and to resist the tendency of the fluid pushing the
ridge wall in the direction of the flow. It is contemplated that,
in one aspect, the support ribs will extend upwardly from the top
surface of the base plate at a height that is less than the height
of the ridge walls, so as to allow the movement of fluid over the
support ribs. Further, the support ribs can b provide in either or
both of the inlet or outlet troughs. However, in one aspect it is
preferred for the support ribs to be formed or provided only within
the outlet troughs. Thus, as the outer ridge wall accumulates
particulate matter, it can be easily cleaned without interference
from support ribs. Support ribs can be added as needed based on the
rigidity of the ridge walls, the height of the ridge walls, and the
forces on the ridge walls. Although the support ribs are shown in
FIG. 7 in a linear or laminar filter plate, it is contemplated that
support ribs can be provided in a filter of any shape, such as a
radial flow filter plate as shown in FIG. 3.
[0039] Still further, the present invention also provides the
ability to produce filters having increased surface area per unit
of volume relative the conventional filters known in the art. For
example, in one aspect, the ability to utility a relative thin
ridge wall, as discussed above can enable the preparation of a
filter plate having an increased surface area for a given quantity
of porous material. Additionally, the incorporation of the filter
plate base portion as a viable filter surface area can also
increase the effective surface area of the inventive filter
assembly. As such, it should be understood that the filter assembly
of the present invention can be prepared having any desired surface
area per unit of volume. For example, and without limitation, a
filter assembly comprising a plurality of stacked filter plates
depicted in FIG. 3, wherein each filter plate has an outside
diameter of approximately 6 inches, and inside diameter of
approximately 2 inches and stacked length of approximately 10
inches can have a surface area of at least 7 square feet, at least
10 square feet, at least 12 square feet, at least 15 square feet,
at least 20 square feet, or even at least 25 square feet.
[0040] The filter plates of the present invention can be formed
from any conventional porous material. However, in one aspect, the
porous material is a sintered porous material, such as a sintered
porous thermoplastic material. Some suitable base materials that
can be used to provide the porous thermoplastic substrate are
described in U.S. Pat. No. 6,551,608 to Yao; Pending U.S. Published
Application No. U.S. 2003-0062311-A1, both of which are
incorporated herein by reference in their entirety. Suitable
thermoplastics for use in forming filter 100 of the present
invention include, but are not limited to, polyolefins, nylons,
polycarbonates, poly(ether sulfones), and mixtures thereof, as well
as fluoropolymers, such as polyvinylidene difluoride (pvdf) and
polytetrafluoroethylene (ptfe). A preferred thermoplastic is a
polyolefin. Examples of suitable polyolefins include, but are not
limited to: ethylene vinyl acetate; ethylene methyl acrylate;
polyethylenes; polypropylenes; ethylene-propylene rubbers;
ethylene-propylenediene rubbers; poly(1-butene); polystyrene;
poly(2-butene); poly(1-pentene); poly(2-pentene);
poly(3-methyl-1-pentene-); poly(4-methyl-1-pentene);
1,2-poly-1,3-butadiene; 1,4-poly-1,3-butadiene; polyisoprene;
polychloroprene; poly(vinyl acetate); poly(vinylidene chloride);
and mixtures and derivatives thereof. A preferred polyolefin is
polyethylene. Examples of suitable polyethylenes include, but are
not limited to, low density polyethylene, linear low density
polyethylene, high density polyethylene, ultra-high molecular
weight polyethylene, and derivatives thereof. In alternative
embodiments the filter material may also be composed of or formed
from sintered metal, steel mesh, woven metal, ceramic materials,
non-woven materials, bi-component, continuous, or staple fiber
media using an extrusion or pultrusion process.
[0041] Examples of polyolefins suitable for use in the invention
include, but are not limited to: ethylene vinyl acetate (EVA);
ethylene methyl acrylate (EMA); polyethylenes such as, but not
limited to, low density polyethylene (LDPE), linear low density
polyethylene (LLDPE), high density polyethylene (HDPE), and
ultra-high molecular weight polyethylene (UHMWPE); polypropylenes;
ethylene-propylene rubbers; ethylene-propylene-diene rubbers;
poly(1-butene); polystyrene; poly(2-butene); poly(1-pentene);
poly(2-pentene); poly(3-methyl-1-pentene-);
poly(4-methyl-1-pentene); 1,2-poly-1,3-butadiene;
1,4-poly-1,3-butadiene; polyisoprene; polychloroprene; poly(vinyl
acetate); poly(vinylidene chloride); and mixtures and derivatives
thereof.
[0042] The porous thermoplastic materials of the invention can
further comprise materials such as, but not limited to, lubricants,
colorants, fillers, and mixtures thereof. Suitable fillers include,
but are not limited to: carbon black, cellulose fiber powder,
siliceous fillers, polyethylene fibers and filaments, and mixtures
thereof.
[0043] Sinterable thermoplastics other than those recited herein
can also be used in this invention. As those skilled in the art
will appreciate, the ability of a thermoplastic to be sintered can
be determined from its melt flow index (MFI). Melt flow indices of
individual thermoplastics are known or can be readily determined by
methods well known to those skilled in the art. For example, an
extrusion plastometer made by Tinius Olsen Testing Machine Company,
Willow Grove, Pa., can be used. The MFIs of thermoplastics suitable
for use in this invention will depend on the particular porous
thermoplastic material and/or the method used to prepare it. In
general, however, the MFI of a thermoplastic suitable for use in
the materials and methods of the invention is from about 0 to about
15. The temperatures at which individual thermoplastics sinter
(i.e., their sintering temperatures) are also well known, or can be
readily determined by routine methods such as, but not limited to,
thermal mechanical analysis and dynamic mechanical thermal
analysis.
[0044] The characteristics of a sintered porous material can depend
on the average size and distribution of the particles used to make
it as well as the particles' average shape. In one aspect of the
invention, the thermoplastic particles arc substantially spherical.
This shape provides certain benefits. First, it facilitates the
efficient packing of the particles within a mold. Second,
substantially spherical particles, and in particular those with
smooth edges, tend to sinter evenly over a well defined temperature
range to provide a final product with desirable mechanical
properties and porosity. Typical pore size starting approximately
at 5 .mu.m and up to approximately 500 .mu.m is preferred, however,
smaller and larger pore sizes are also possible. For example, the
pore sizes can be as low as about 1 .mu.m and as high as about 500
.mu.m, whereas the porosity can be as low as about 30% and as high
as about 90%. Pore size and porosity selection is obvious to one of
ordinary skill in the art depending on the process and/or the
starting material selected.
[0045] Preferably, a filter plate 110 is molded from sintered
porous plastic. According to an embodiment of the invention a mold
having a desired configuration can be filled with sintered porous
plastic precursor composition, such as for example, a powder batch
and the particles can be fused together by heating to form the
resulting filter plate 110 in the shape of the mold. The particular
sintering conditions are known in the art and will depend, in part,
upon the particular sintered porous plastic precursor composition.
To this end, one of skill in the art will be able to determine the
particular sintering conditions without requiring undue
experimentation.
[0046] Because of such molding process, filter plates of any
desired shape, configuration, or dimensions may be readily formed
from a porous material in one continuous and contiguous piece. To
this end, it should be appreciated that the molding process for
each plate does not require the usage of a core pin as is typically
required to prepare the conventionally known molded filters. As
such, each molded filter plate can be prepare having a more uniform
concentricity, thus enabling the manufacture of a more uniform and
efficient stacked filter assembly. As used herein, the term
concentricity is intended to refer, without limitation, to the
concentration of porous material across the ridge wall and/or base
plate portion of a given filter plate.
[0047] The particles used to form the porous plastic to be sintered
can be formed by several processes known in the art. One such
process is cryogenic grinding. Cryogenic grinding can be used to
prepare thermoplastic particles of varying sizes. But because
cryogenic grinding provides little control over the sizes of the
particles it produces, powders formed using this technique may be
screened to ensure that the particles to be sintered are of a
desired average size and size distribution.
[0048] Underwater pelletizing can also be used to form
thermoplastic particles suitable for sintering. Although typically
limited to the production of particles having diameters of greater
than about 36 .mu.m, underwater pelletizing offers several
advantages. First, it provides accurate control over the average
size of the particles produced, in many cases thereby eliminating
the need for an additional screening step and reducing the amount
of wasted material. A second advantage of underwater pelletizing,
which is discussed further herein, is that it allows significant
control over the particles' shape.
[0049] Underwater pelletizing is described, for example, in U.S.
Pat. No. 6,551,608 to Yao and U.S. Published Patent Application No.
U.S. 2003-0062311-A1, filed Aug. 23, 2002, Ser. No. 10/226,235,
both of which are incorporated herein by reference in their
entirety. Thermoplastic particle formation using underwater
pelletizing typically requires an extruder or melt pump, an
underwater pelletizer, and a drier. The thermoplastic resin is fed
into an extruder or a melt pump and heated until semi-molten. The
semi-molten material is then forced through a die. As the material
emerges from the die, at least one rotating blade cuts it into
pieces herein referred to as "pre-particles." The rate of extrusion
and the speed of the rotating blade(s) determine the shape of the
particles formed from the pre-particles, while the diameter of the
die holes determine their average size. Water, or some other liquid
or gas capable of increasing the rate at which the pre-particles
cool, flows over the cutting blade(s) and through the cutting
chamber. This coagulates the cut material (i.e., the pre-particles)
into particles, which are then separated from the coolant (e.g.,
water), dried, and expelled into a holding container.
[0050] In one aspect, the average size of particles produced by
underwater pelletizing can be accurately controlled and can range
from about 0.014'' (35.6 .mu.m) to about 0.125'' (318 .mu.m) in
diameter, depending upon the thermoplastic. Average particle size
can be adjusted simply by changing dies, with larger sized dies
yielding proportionally larger particles. The average shape of the
particles can be optimized by manipulating the extrusion rate and
the temperature of the water used in the process.
[0051] The material used to form filter plate 110 can also be made
with functional characteristics, such as antimicrobial activity,
chlorine reduction activity, or the like. The material can also be
treated to be antibacterial, such as by incorporating antimicrobial
treatments into or onto the material. Such treatment addresses and
corrects a common problem of bacterial growth in or on filters.
[0052] Some suitable antiviral or antimicrobial agents are
disclosed in U.S. Pat. No. 6,551,608 to Yao, the disclosure of
which is herein incorporated by reference. Some antiviral or
antimicrobial agents include, but are not limited to: phenolic and
chlorinated phenolic compounds; resorcinol and its derivatives;
bisphenolic compounds; benzoic esters; halogenated carbanilides;
polymeric antimicrobial agents; thazolines;
trichloromethylthioimides; natural antimicrobial agents; metal
salts; broad-spectrum antibiotics, and mixtures thereof. Preferred
antiviral or antimicrobial agents include, but are not limited to:
2,4,4'-trichloro-2'-hydroxy-diphenyl ether;
3-(4-chlorophenyl)-1-(3,4-di-chlorophenyl)urea;
poly(iminoimidocarbonyl iminoimidocarbonyl iminohexamethylene
hydrochloride); silver ions; salts; mixtures thereof or the
like.
[0053] While the foregoing description and drawings represent
embodiments of the present invention, it will be understood that
various additions, modifications and substitutions may be made
therein without departing from the spirit and scope of the present
invention as defined in the accompanying claims. In particular, it
will be clear to those skilled in the art that the present
invention may be embodied in other specific forms, structures,
arrangements, proportions, and with other elements, materials, and
components, without departing from the spirit or essential
characteristics thereof. One skilled in the art will appreciate
that the invention may be used with many modifications of
structure, arrangement, proportions, materials, and components and
otherwise, used in the practice of the invention, which are
particularly adapted to specific environments and operative
requirements without departing from the principles of the present
invention. The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims, and
not limited to the foregoing description. The cartridge or parts of
the cartridge can be made larger or smaller based on the intended
application. Furthermore, multiples of the cartridge can be stacked
together to achieve more surface area and thereby gain more
capacity. Also, multiple stacks of multiple cartridges may be
used.
* * * * *