Note: Descriptions are shown in the official language in which they were submitted.
1 338234
This application is a divisional of patent application
Serial No. 558,007 filed 2 February, 1988.
FIELD OF T~E INVENTION
The present invention relates to filter apparatus
and systems generally and to techniques for operating
such apparatus.
BACXGROUND OF THE INVENTION
Various types of filters are known for filtering
water and similar liquids. A particularly useful type
of filter is a disk filter. Filters of this type are
described and claimed, for example, in applicant's
U.S. Patent Nos. 4,624,785 issued November 25, 1986;
4,683,060 issued July 28, 1987; 4,654,143 issued March
31, 1987; 4,026,806:issued May 31, 1977; 4,042,504
issued August 16, 1977; 4,045,345 issued August 30,
1977; 4,271,018 issued June 2, 1981; 4,278,540 issued
July 14, 1981; 4,295,963 issued October 20, 1981.
- ~ -
-
1 338234
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved
filter for use in filtering fluids, such as water.
There is thus provided in accordance with a preferred
embodiment of the present invention, a disk-type filter
comprising a housing having an inlet connectable to an upstream
pipe and an outlet connectable to a downstream pipe and a stack
of filter units disposed within the housing for separating solid
particles from a fluid flowing between fi-lter units in the stack
of filter units from an upstream side of the stack of filter
units to a downstream side thereof, characterized in that the
stack of filter units includes a plurality of co-operating filter
units defining a plurality of paired co-operating filter
surfaces, including first and second surfaces each defining a
plurality of fingers, the fingers defined by the first surface
being arranged in registration with the fingers defined by the
second surface, the exteriors of the fingers defined by the first
and second surfaces communicating with either one of an upstream
side and a downstream side and the interiors of the fingers
defined by the first and second surfaces communicating with the
other one of the upstream side or downstream side, spaces being
defined in association with the fingers defined by the first and
second surfaces and being disposed in registration so as to
define channels, which permit particulate matter to become
disengaged with the upstream side of the fingers defined by the
-
first and second surfaces. 1 3:38~34
According to a further preferred embodiment of the
present invention, there is provided a filter unit comprising
first and second surfaces defining a plurality of fingers,
spaces being defined in association with the fingers defined by
the first and second surfaces such that when a plurality of
filter units are disposed in registration, the spaces define
~ h~nnel .~ .
Further in accordance with a preferred embodiment of
the present invention, the fingers defined by the first and
second surfaces each have formed thereon a pair of spaced,
generally raised line portions separated by an interior area,
the raised line portions on at least one of the first and second
surfaces defining a plurality of spaced grooves.
Still further in accordance with a preferred embodiment
of the present invention, the filter also comprises a filter aid
operatively associated with the stack of filter units.
Additionally in accordance with a preferred embodiment
of the present invention, the pluralities of spaced grooves
defined by the first and second surfaces define an enhanced depth
filtering pathway.
Still further in accordance with a preferred embodiment
of the present invention, there is provided a planar divider at
the interior area of each of the fingers, such that when a
plurality of filter units are disposed in registration, the line
portions and the planar dividers define a multiplicity of
backflow chambers for ~nh~nced backflowing.
Further in accordance with a preferred embodiment of
1 338234
the present invention, the stack of filter units comprises a
generally cylindrical element having an axial central bore along
its longitudinal axis.
Still further in accordance with a preferred embodiment
of the present invention, there is provided apparatus for
providing a flushing fluid flow through the filter unit including
a fluid discharge device arranged for axial movement along the
bore.
Additionally in accordance with a preferred embodiment
of the present invention, flushing chambers are defined between
the line portions.
Further in accordance with a preferred embodiment of
the present invention, there is provided a plurality of axial
connecting elements which traverse the stack of filter units at
locations intermediate i'nner and outer diameters of the stack of
filter units.
Still further in accordance with a preferred embodiment
of the present invention, there is provided a manifold defining
the inlet and the outlet in communication with the bottom of the
housing.
According to a further preferred embodiment of the
present invention, there is provided a filter comprising a
housing having an aperture at the bottom thereof, a filtering
assembly disposed in the housing, and a manifold defining an
inlet and an outlet in communication with the aperture.
-
1 338234
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and
appreciated more fully from the following detailed description,
taken in conjunction with the drawings in which:
- Fig. 1 is a partially cut-away side view sectional
illustration of a filter constructed and operative in accordance
with a preferred embodiment of the present invention;
Fig. Z is a sectional illustration taken along the
lines II-II of Fig. 1;
Fig. 3 is a sectional illustration corresponding to
that of Fig. 2 but illustrating a dual nozzle variety of filter
otherwise similar to the single-nozzle variety shown in Figs.
and 2;
Fig. 4 is a pictorial illustration of the curved
configuration of one of the stack of filter elements shown in
Fig. l;
Fig. 5 is a pictorial illustration of a portion of a
stack of filter elements of the type shown in Fig. 4;
Fig. 6 is an enlarged illustration of a portion of
the stack of filter elements illustrated in Fig. 5;
Fig. 7 is an enlarged illustration of a portion of
the stack of filter elements illustrated in Fig. 5, also showing
filter cake and/or sediment associated therewith:
Fig. 8 is an illustration of part of the stack of
filter elements illustrated in Fig. 5, illustrating the chRnne~s
between finger elements thereof;
1 33~3~
Figs. 9A and 9B correspond to Fig. 8 and illustrate
the part of the stack of filter elements with filter aid material
in association therewith and with the filter aid material having
fallen therefrom respectively;
Fig. 1~ is a partially cut-away side view sectional
illustration of a filter constructed and operative in accordance
with a preferred embodiment of the present invention and arranged
to define a drain outlet which is spaced from the bottom of the
upstream side of the housing;
Fig. ll is a partially cut-way side view sectional
illustration of a filter constructed and operative in accordance
with another preferred embodiment of the present invention,
arranged to define a drain outlet which is spaced from the bottom
of the upstream side of the housing and to include filter stack
supports which traverse the filter disks intermediate the
upstream and downstream surfaces of the filter disks;
Fig. 12 is a planar view illustration of a filter disk
constructed and operative in accordance with a preferred
embodiment of the invention for use in the apparatus of Fig. ll;
Figs. 13A and 13B are first and second illustrations
showing, in exaggerated form, the bendability of the fingers
defined by the filter disk of Fig. 12 under respective filtration
and backflowing conditions;
Fig. 14 is a pictorial illustration of a portion of a
filter stack including filter disks of the type illustrated in
Fig. 2, and illustrating, in exaggerated form, the disengagement
of filter aid material from the filter stack as the fingers snap
- 1 338234
back upon termination of the application of a pressure gradient
thereacross;
Figs. 15A and 15B are enlarged sectional views of a
portion of the filter stack of Fig. 14 respectively during
filtration and during regeneration or backflowing;
Fig. 16 is a partially cut-way side view sectional
illustration of a filter constructed and operative in accordance
with yet another preferred embodiment of the present invention,
arranged to define a central drain outlet and fluid inlet
manifold and to include filter stack supports which traverse the
filter disks intermediate the upstream and downstream surfaces of
the filter disks;
Fig. 17 is an enlarged illustration of the central
drain outlet and fluid inlet manifold of Fig. 16;
Fig. 18 is a sectional illustration taken along the
lines XVIII - XVIII of Fig. 17; and
Fig. 19 is a sectional illustration of an alternative
embodiment of central drain outlet and fluid inlet manifold
constructed and operative in accordance with a preferred
embodiment of the present invention.
- ~ 338i2~
DETAILED DESCRIPTION OF THE INVENTION
Reference is now made to Figs. 1, 2 and 3 which
illustrate a filter constructed and operative in accordance with
a preferred embodiment of the present invention and comprising a
base 7~ on which is fixedly supported a bottom housing portion
72. Removably mounted onto the bottom housing portion 72 is a top
housing portion 74, which is maintained in sealing engagement
therewith by means of a sealing ring 76.
A fluid inlet 78 is provided adjacent the bottom of
housing portion 72 and communicates with the outside cylindrical
surface, hereinafter termed the "upstream surface", of a stack of
filter elements 79. A fluid outlet assembly 8~ is coupled to
housing portion 72 and communicates with a hollow interior
portion 81 of stack of filter elements 79 adjacent the inner
cylindrical surface of the stack of filter elements, hereinafter
termed the "downstream surface".
The stack of filter elements 79 preferably comprises a
stack of hollow center filter disks 82 of the type illustrated in
Figs. 4 - 9B and 12 - 15B.
The stack of filter elements 79 is preferably removably
mounted in coaxial relationship so as to define volume 81 and is
retained in suitably tight engagement by means of top and bottom
retAining collars 84 and 86 joined by a plurality of threaded
rods 88, typically four in number, and associated nuts 9~. A
retAining member 89 supports top ret~;n;ng collar 84 and is
seAlingly mounted onto the top housing portion 74 by a threaded
retAining ring 91. A collar member 92 engages retAining member
1 338234
89. As seen in Fig. 2, each of the filter elements 82 is
preferably formed with four locating protrusions 85, each formed
to permit engagement with a rod 88. Thus it may be appreciated
that rods 88 serve to maintain the filter elements 82 in precise
azimuthal registration.
A focussed jet nozzle assembly 1~ is disposed mainly
within volume 81 and comprises a water supply shaft 11~ having a
water inlet 112 and an associated inlet valve 114.
A rotatable focussed jet outlet head 116 is arranged
for relatively free rotation about a rotation axis 118 defined in
shaft 11~ and is provided with a single output aperture 119.
Referring now to Fig. 2, it is seen that the outlet aperture is
arranged to provide an eccentric water output jet which drives
the outlet aperture 119 in rotary motion about axis 118, thus
sequentially directing~ the output jet into each of the
azimuthally separated backflow chambers 121 defined by the
adjacent filter disks 82.
According to a preferred embodiment of the invention,
there is provided above outlet aperture 119 a positioning ring
12~, curved to correspond to the curvature of the inner,
downstream, surface 122 of the stack of filter elements, for
desired positioning of the focussed jet nozzle assembly 1~ in
volume 81, whereby the axis of rotation of the focussed jet
outlet head 116 is centered with respect to cylindrical
downstream surface 122, such that the output aperture 119 is
always at a predetermined distance from the downstream surface
122, so as not to interfere with the rotation of focussed jet
outlet head 116. l 3 3 8 2~ ~
It may be appreciated that the focussed water jet
exiting from outlet aperture 119 is forced into the individual
volumes defined by the stack of filter elements facing the outlet
aperture, providing efficient flushing of the accumulated solid
material collected therein, and is not permitted to be spread
out, which would result in a reduction of its strength and its
backflowing efficiency.
The outlet aperture 119 is displaced up and down and
rotated about axis 118, and the pressurized stream produced
thereby is sequentially concentrated on individual filtering
chambers 121 defined in the stack of filter elements to provide
~nh~nced backflowing thereof.
As noted above, outlet aperture 119 is arranged to
provide a radially directed concentrated backflowing jet, which
serves to flush particulate matter from the stack of filter
elements 79.
Inlet 112 is typically coupled via a flexible hose (not
shown) to a backflow liquid supply which may be connected to a
pressurized source of liquid to be filtered 123 which
communicates with the inlet 78 via a two way valve 125.
Alternatively the inlet 112 may be coupled to another source of
high pressure fluid. Valve 125 selectably couples the water inlet
78 of the filter either to a pressurized water source or to a
backflow liquid drain 127.
During normal operation of the filter of the present
invention. focussed jet nozzle assembly 1~ is located partly
within volume 81 and shaft 11~ is sealingly coupled to the top
1(:)
1 3 ~ 8 2 3 4 -``
-
portion 74 of the housing by means of sealing collar 92 which
se~lingly engages threading on retaining member 89. Valve 125 is
oriented as shown in Fig. 1 such that liquid to be filtered
enters from the pressurized source and passes to inlet 78 and
through the stack of filter elements 79 from the upstream surface
to the downstream surface, being filtered in the process. The
filtered liquid passes through volume 81. Valve 114 is closed.
During backflow operation, valve 125 is manipulated to
close off the pressurized liquid source and to provide
communication between inlet 78 and backflow drain 127. Valve 114
is opened to provide a pressurized flow of water to focussed jet
nozzle assembly 1~ and collar 92 is disconnected.
Focussed jet outlet head 116 is manually reciprocated
axially along the interior of the stack of filter elements at the
downstream surface and is rotated by the fluid stream
eccentrically exiting therefrom through at least 36~ degrees,
causing a high pressure concentrated jet of water to enter the
backflow chambers 121 from the downstream surface of the filter
for dislodging accumulated filtered material from the upstream
side of the stack of filter elements. This arrangement enables
substantially all of the backflow chambers 121 to be thus
scanned, region by region, by the concentrated jet for efficient
backflow cleaning of the stack of filter elements.
Reference is now made to Fig. 3, which illustrates an
alternative embodiment of the apparatus of Fig. 1, wherein a
focussed jet outlet head 132 having two nearly but not exactly
oppositely directed eccentric outlet apertures 134 and 136 is
_ 1 338234
provided. According to a preferred embodiment, the two apertures
134 and 136 are arranged at different axial locations with
respect to axis 118, thus providing nearly simultaneous flushing
of chambers at two different axial locations along axis 118.
Reference is now made to Figs. 4 - 9B, which
illustrate a preferred embodiment of filter element constructed
and operative in accordance with a preferred embodiment of the
invention. The filter element is appropriate for use in any
suitable filter apparatus, and is particularly useful in the
filter apparatus described hereinabove.
Fig. 4 illustrates in plan view a portion of a filter
disk 42~ comprising a plurality of finger elements 422. It is
seen that the configuration of the finger element 422 is
preferably not exactly radial. Specifically, the outline of each
finger element is curved; along a portion of an arc. Each raised
line portion 424 is configured as part of an arc about a
different center, as illustrated in Fig. 4, for an exemplary
embodiment.
According to a preferred embodiment of the invention,
the line portion 424 is formed with a pointed end 425 adjacent
the downstream side, thereby to minimize deflection of backflow
streams impinging thereon.
The resulting configuration provides a relatively
enhanced length of the line portion, and thus of the filter
barrier per unit area of the filter element. It will be
appreciated that the filter barrier defined by the raised line
portion 424 defines a barrier between an upstream side of the
filter, here typically the radially outward side of the line
- ~ :
1 338234
portion, and the downstream side of the filter, typically the
radially inward side of the line portion. Accordingly, it may be
understood that an increase in the length of the filter barrier
per unit area of filter element provides a corresponding increase
in the filtering capacity of the unit per unit area of filter
element, and per unit volume of a filter assembly made up of a
stack of such filter elements. The raised line portion 424 is
formed with an array of grooves 423.
The spaces 426 between adjacent finger elements 422,
which typically lie at the upstream side of the filter, define
filtering volumes, which accomodate, according to a preferred
embodiment of the invention, a filter cake.
At spaces 428, defined interiorly of each finger
element 422, which typically lie at the downstream side of the
filter, there are defined planar dividers 429, which are recessed
with respect to both the line portions of the first and second
surfaces, such that when a plurality of filter elements is
arranged in registration in a stack, the planar dividers define a
multiplicity of backflow chambers 43~ for enhanced and
concentrated backflowing. These backflow chambers are
particularly suitable for pressurized backflow cleaning by the
backflow focussed jet produced by the apparatus of Figs. 1 - 3
described hereinabove.
It is a particular feature of the invention embodied in
Fig. 4 that on the downstream side there are defined backflow
chambers which concentrate the backflowing effect of a
backflowing jet of pressurized fluid, while at the same time, at
1 338234
the upstream side, particulate matter dislodged from the
filtering barrier is free to fall out of engagement with the
filter stack.
Reference is now made to Figs. 5 - 9B. The assembly
shown in these figures comprises a stack of identical filter
elements 51~ being of the type illustrated in Fig. 4 and being
formed of a plastic material, such as polypropylene. The filter
elements comprise identically patterned opposite first and second
planar surfaces. Except for grooves 423, the two planar surfaces
of each filter element arè mirror images of one another, such
that the line portions thereof on both first and second surfaces
thereof are in registration, as are the spaces between fingers
and inside fingers. The grooves 423 on the facing raised line
portions are preferably skewed with respect to one another.
Each planar surface of filter element 510 is formed
with a filter barrier defined by a raised line pattern 52~, which
preferably is arranged to extend continuously in generally
undulating configuration, defining a plurality of finger elements
522. The raised line pattern 52~ typically defines the outline of
each finger element 522 and may be configured to define a smooth
outline or alternatively a notched or serrated pattern along the
generally radially extending portion of each finger element 522.
As noted in connection with finger element 422
described hereinabove, the outline of each finger element is
preferably curved along a portion of an arc. Each raised line
portion is preferably configured as part of an arc about a
different center, as illustrated in Fig. 4.
The resulting configuration provides a relatively
14
-
- 1 338234
enhanced length of the line portion, and thus of the filter
barrier per unit area of the filter element. It will be
appreciated that the filter barrier defined by the raised line
portion 52~ defines a barrier between an upstream side of the
filter, here typically the radially outward side of the line
portion, and the downstream side of the filter, typically the
radially inward side of the line portion. Accordingly, it may be
understood that an increase in the length of the filter barrier
per unit area of filter element provides a corresponding increase
in the filtering capacity of the unit per unit area of filter
element, and per unit volume of a stack of such filter elements.
It is a particular feature of the present invention
that the upstream side of the filtering barrier defined by raised
line portion 52~ is a relatively open volume, thus providing
~nh~nced capacity for làrge particles during filtration and ease
of particle disengagement during regeneration and backflowing-,
while at the same time providing efficient filtration of small
particles.
In the embodiment of Figs. 5 - 9B, the filter elements
making up the stack of filter elements are maintained in precise
azimuthal alignment, as by means of one or more azimuthal
~1 j ning protrusions 85 associated with each stack of filter
elements and registered by a rod (not shown3 passing
therethrough. Accordingly, when the first and second planar
surfaces are arranged in juxtaposed engagement, the finger
elements 522 on the facing first and second planar surfaces of
ad~acent filter elements are in precise registration, defining a
1 338234
filter barrier between the upstream side of the filter and the
downstream side. At the locations where the finger elements on
first and second surfaces meet in touching engagement, grooves
525 on either or preferably both planar surfaces are engaged.
Underst~n~ing of this engagement may be assisted by a
consideration of Fig. 6, which is an enlargement taken along the
lines VI - VI in Fig. 5.
It is a particular feature of the present invention
that where grooves are formed on both facing line portions, such
grooves 526 and 528 on the opposite engaging surfaces are
mutually skewed, as illustrated in Fig. 6, such that they define
multiply intersecting paths for fluid flow therethrough, there
being defined at intervals along the pathway a particle size
gauge being the cross section of the single groove.
This configuration has a number of advantages,
including the fact that along much of the pathway from the
upstream side to the downstream side across the engaged first and
second surfaces, the pathway is larger than the particle size
gauge due to the effective combination of grooves formed on the
opposite facing surfaces. The multiple interconnections between
grooves provides multiple alternative paths for fluid, such that
fluid flow may continue notwithstanding blockage of certain
passageways. The relatively long and intricate pathway of the
fluid provides enhanced de~th of filtering, thus increasing
.
filtering efficiency.
Reference is now~made to Fig. 7, which corresponds to
Fig. 6 but also shows the presence of filter cake and/or
sediment during operation of the filter. The illustration shows
16
- \ -
1 338234
an embodiment wherein the upstream side is radially outward of
the raised line portion 52~ and thus intermediate finger elements
522 while the downstream side is at the radially inward side of
the raised line portion 52~ and thus communicates with the area
and volume interior of each finger element 522.
- It is seen that fluid, such as water, carrying
particulate matter, enters from the upstream side, as indicated
by arrows 53~, and deposits the particulate matter 532 upstream
of the raised line portion 52~.
It may additionally be appreciated that a filter aid
such as diatomaceous earth, activated carbon or a filter cake may
be employed and disposed at the upstream side of the stack of
filter elements, as illustrated.
It is a particular feature of the present invention
that the spaces between adjacent fingers 522 are open, such that
when a plurality of filter disks 51~ are stacked with the fingers
522 in registration, ~h~nnel s 56~ are defined between adjacent
fingers, as seen in Figs. 8 - 9B. These channels have particular
importance when a filter aid, such as a filter cake, is employed,
as the filter cake may be located on the upstream surface of the
filter disks 51~ along the periphery of the fingers 522.
Assuming that the stack of filter disks 51~ is arranged
generally vertically, it may be understood that when flow of
fluid through the filter from the upstream side to the downstream
side is terminated, the filter aid and accumulated filtered out
particulate material, which during filtering is stuck onto the
peripheral edges 524 of the fingers, as seen figuratively in Fig.
~ 338~3-4
-
9A, tends to fall through the channels 56~ to the bottom of the
filter housing, as seen figuratively in Fig. 9B.
Reference is now made to Fig. l~, which illustrates an
alternative embodiment of filter, which is identical to that
illustrated in Fig. l with the exception of the location of fluid
inlet 78. It is noted that in the embodiment of Fig. l, the inlet
78 also functions as a backflow drain and lies somewhat spaced
from the bottom of the housing 72. In Fig. 1~, the location of
the inlet 78 in spaced relationship with the bottom of the
housing 72 is emphasized. It will be appreciated by persons
skilled in the art that the arrangement of Fig. 1~ may replace
that of Fig. 1 in all the embodiments of the invention
illustrated in Figs. 2 - 9E. Fig. l~ is also illustrative of a
broader concept which is not limited to disk filters or to
filters having a backflow arrangement.
Upon termination of liquid flow through the filter
assembly, the liquid drains to the bottom of the housing, and the
particulate matter, including filter aid material and solid
particles separated from the liquid, falls into the liquid, the
filter aid material falling to the bottom of the housing and the
solid particles floating in or on the liquid, such that at least
some of the filter aid material is retained in the housing while
the solid particles are flushed out the drain.
Upon resumption of pressurized liquid flow through the
filter assembly, the filter aid becomes distributed on the
upstream side of the filter assembly and carries out its normal
function, having thus being cleaned, reoriented and recycled.
The drain may be separate from the inlet or identical
18
.
- 1 338234
therewith. In the latter case, the filter apparatus preferably
comprises a manually operable multi-flow valve 125 having a
normal position wherein liquid to be filtered is coupled to the
upstream side of the filter assembly and a backflow position
wherein liquid to be filtered is prevented from reaching the
upstream side and wherein the drain communicating with the
upstream side is coupled for draining to the atmosphere.
Reference is now made to Fig. 11, which illustrates an
alternative embodiment of filter, which is generally identical to
that illustrated in Fig. 13 with the exception of the locations
of rods 88. In the embodiment of Fig. ll, the rods 88, which
tightly secure the filter disks 82 together in stack 79, are
disposed intermediate the inner and outer diameters of the stack.
This arrangement of rods 88 eliminates interference with
backflowing which would occur were the rods 88 located inwardly
.
of the downstream surface of the stack 79 and also el;min~tes the
waste of volume in the housing which would result were the rods
88 to be located outwardly of the upstream surface, as shown in
the embodiment of Fig. l~. Thus, the embodiment of Fig. ll
m~x; mi ~es the relationship between stack diameter and inner
diameter of the housing.
The embodiment of Fig. ll is characterized in that it
includes a stack of filter elements 79, or any other suitable
filter assembly, which is configured to permit particulate matter
to fall out of engagement with the upstream side thereof to the
bottom of the housing in the absence of liquid flow through the
filter assembly. It is appreciated that the foregoing is also
19
1 ~38:234
true for the embodiments of Figs. 1 - 9B.
Reference is now made to Fig. 12, which illustrates a
filter disk 6~ constructed and operative in accordance with a
preferred embodiment of the present invention. Filter disk 6~ is
generally identical to that illustrated in Figs. 5 - 8
hereinabove, with the exceptions described hereinbelow:
Filter disk 60~ is formed with a plurality of finger
elements 6~2 having a non-radial configuration curved along a
portion of an arc. Each finger may be seen to include a line
portion 6~4, which corresponds generally to line portion 424,
described above in connection with Fig. 4. The line portion 604
for each finger may be considered to include an outwardly facing
portion 6~6 and an inwardly facing portion 6G8, joined by an
outward curved portion 61~ and an inward curved portion 612.
According to a preferred embodiment of the present
invention, the outwardly facing portion 606 is longer than the
inwardly facing portion 6~8, such that application of a positive
pressure gradient from the upstream side of the stack, here the
outside thereof, to the downstream side of the stack, here the
inside thereof, as during normal filtering operation, causes
inward bending of the fingers 6G2 in a clockwise sense for the
configuration as illustrated in Fig. 12. Removal of the pressure
gradient, as upon termination of the supply of pressurized fluid
to be filtered, allows fingers 6~2 to snap back to their original
positions.
Further in accordance with a preferred embodiment of
the invention there exists a very small difference in thickness
of the filter element between its radially inward portion and its
2~
1 338234
extreme radially outward portions, whereby the thickness of the
radially outward portions is very slightly less than that of the
radially inward portion. This difference in thickness permits the
finger elements 522 of adjacent filter elements to be slightly
spread apart in a direction parallel to axis 118 (Fig. 1) in
response to the application of a backflow jet to the volume
interior of each finger element. This spreading apart assists in
the disengagement of particles accumulating from the stacked
filter elements but is not sufficient to permit entry of small
particles into the filter stack during normal filtering flow
from the upstream side to the downstream side.
Additionally in accordance with a preferred embodiment
of the present invention, adjacent each of the inward curved
portions 612 there is provided a narrow, radially extending
structural member 614, which extends nearly but not completely to
the inner edge of the disk 6~. Structural members 614 provide
necessary structural support for the disks 6~ while also
functioning to define backflow chambers 616 between adjacent
members 614. These backflow chambers 616 are relatively broad
adjacent the downstream side of the stack for ~in;mllm
interference with a jet of ~ackflow fluid and then narrow as they
extend between respective outwardly facing and inwardly facing
line portions 6~6 and 6G8.
Additionally in accordance with a preferred embodiment
of the present invention, and as noted above in connection with
Fig. 11, accomodation is made for transversely extending rods 88,
in the form of sockets 618 which are located intermediate the
1 3382~34
_..
inner and outer diameters of the disk 600. According to a
preferred embodiment of the invention, as illustrated in Fig. 12,
the socket 618 is located in communication with the upstream side
of the disk 6~o and is arranged as an enlargement of inward
curved portion 612, so as to minimize interference with
backflowing while minimizing the loss of filter surface area at
the socket.
Reference is now made to Figs. 13A and 13B which
illustrate the bending and snap back action of the fingers 6~2 in
accordance with the present invention. In Fig. 13A, the normal
orientation of fingers 6~2, i.e. in the absence of an applied
pressure gradient, is illustrated in solid lines, while the bent
position thereof, shown in exaggerated form for the purpose of
illustration only, is illustrated in broken lines. In fact the
angular displacement of the outer ends of the fingers is quite
small and is a function of the ~aterials used for the filter
elements and of the operating pressure in the filter. In Fig.
13B, opposite~bending upon backflowing is illustrated, with the
normal orientation of fingers 602 being shown in solid lines and
the angular displacement of the outer ends of the fingers during
backflowing being shown in broken lines.
It is a particular feature of the present invention
that the bending of the fingers, which occurs upon termination of
normal filtering and also typically upon the onset of backflowing
at a given region, serves to enhance disengagement of particles
from the surface of the filter disks 60~.
Backflowing, which normally will not occur each time
there is a termination of normal filtering, is typically
r -
1 338234
accompanied by additional bending in an opposite sense from the
bending produced under normal filtration operation, and thus
produces enhanced disengagement of the filter aid material from
the stack.
It is also noted that upon backflowing, the fingers of
adjacent disks are slightly separated from each other, thus
enabiing the space between the grooves 526 and 528 to be locally
and temporarily enlarged for enhanced backflowing.
Fig. 14 illustrates pictorially the disengagement of
filter aid material from a stack of fllter disks when the fingers
6~2 snap back from their bent positions (shown in broken lines)
to their normal positions (shown in solid lines~.
Figs. 15A and 153 are enlarged sectional illustrations
of this phenomenon, showing the buildup of dirt and accumulation
of filter aid material prior to disengagement (Fig. 15A) and
following disengagement (Fig. 15B).
It will be appreciated that the filter assembly may
comprise any suitable filtering element or assembly of elements
although a stack of filter disks as described hereinabove is
preferred. A backflowing arrangement as described hereinabove is
useful in association with the filter aid ret~;n;ng arrangement
described hereinabove but is not required.
Reference is now made to Figs. 16 - 19, which
illustrate an alternative embodiment of the present invention
wherein a central inlet and outlet manifold is provided. The
embodiment of Fig. 16 is generally identical to that shown in Fig
11 with the following exception:
1 338234 - `
Disposed at the very bottom of the housing 72 is an
inlet and outlet manifold 702 which is coupled to a fluid
inlet/backflow drain conduit 704 and to a filtered fluid outlet
conduit 7~6. Fluid inlet/backflow drain conduit 704 is typically
connected to a three position valve such as valve 125 shown in
Fig. 11.
Fluid communication from a source of pressurized fluid
via valve 125 (not shown) to the upstream surface of the filter
assembly is illustrated by arrows 7~8. Fluid communication from
the upstream side of the filter assembly to the backflow outlet
is illustrated by arrows 71~. Fluid communication from the
downstream side of the filter assembly to filtered fluid outlet
conduit 7~6 is illustrated by arrows 712.
According to ore embodiment of the invention, the
manifold is provided with radially extending outlets, as shown in
Fig. 18. According to an al-ernative embodiment of the invention,
the outlets may be arranged as illustrated in Fig. 19 to provide
a tangent flow. In Fig. l9, this tangent flow of fluid to be
filtered into the housing is illustrated by arrows 714.
Referring now to rigS. 16 - 19, the structure of the
manifold 7~2 will now be described. The manifold comprises a body
member 721 which is connected to conduit 7~4 and which defines an
annular inlet passage 722, communicating with conduit 7Q4. Body
member 721 also defines a central outlet passage 724 which
communicates with outlet conduit 706.
A collar member 728 threadably engages corresponding
threading on the body member 721 and is operative to secure the
manifold in sealing engagement with an aperture 73~ formed at the
24
1 338234`
bottom of housing 72, by means of a sealing ring 732.
As seen in Fig. 17 and Figs. 18 or 19, the collar
member 728 comprises a plurality of upstanding members 734 which
define shoulders 736 which seat on the bottom of the housing 72
at the periphery of aperture 73~. Defined between adjacent
upst~n~;ng members 734 are inlet passages 738.
It is a particular feature of the manifold arrangment
shown in Figs. 17 -19 that both inlet and outlet to the filter
are provided through a single aperture in the housing 72.
It is a further particular feature of the present
invention that shoulder 736 provides centering of the entire
manifold assembly onto the housing 72. It is noted that shoulder
736 comprises a surface 743 which lies in a plane parallel to
axis 118 which provides the desired centering.
Shoulder 736 àlso comprises a surface 742 which lies in
a plane perpendicular to axis 118 and which lies over the edge of
housing 72 adjacent to aperture 73~, thereby pressing housing 72
against sealing ring 732 for providing desired sealing upon tight
threaded engagement of the collar member 728 onto the body member
721.
It will be appreciated by persons skilled in the art
that the present invention is not limited by what has been
particularly shown and described hereinabove. Rather the scope of
the invention is defined only by the claims which follow:
