U.S. patent number RE32,537 [Application Number 06/750,058] was granted by the patent office on 1987-11-03 for self-cleanable filter.
Invention is credited to Mordeki Drori.
United States Patent |
RE32,537 |
Drori |
November 3, 1987 |
Self-cleanable filter
Abstract
A self-cleanable filter, comprises: a housing having a fluid
inlet, a fluid outlet, and a dirt purging opening; a filter body
within the housing and having a surface facing the inlet side of
the housing; and a cleaning body within the housing and movable
from a home position along the cylindrical surface of the filter
body for cleaning same. The cleaning body comprises a first section
defining an internal chamber having an inlet opening facing the
surface of the filter body to be cleaned and movable along said
surface, and a second section closing the dirt purging opening when
the cleaning body is in its home position. The second section has
an outlet opening communicating with the internal chamber and
located within the housing in the home position of the cleaning
body but movable through the housing purging opening to a position
externally of the housing upon the movement of the cleaning body
for cleaning the filter. A number of embodiments are described
wherein the cleaning body is mounted for linear movement, rotary
movement, and both linear and rotary movements, with respect to the
filter body. In most of the described embodiments, the filter
includes a sensor for automatically sensing the pressure difference
between the inlet and outlet and for initiating a cleaning
operation.
Inventors: |
Drori; Mordeki (Kiron,
IL) |
Family
ID: |
27270707 |
Appl.
No.: |
06/750,058 |
Filed: |
June 27, 1985 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62853 |
Jul 31, 1979 |
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Reissue of: |
727860 |
Sep 29, 1976 |
04042504 |
Aug 16, 1977 |
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Foreign Application Priority Data
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May 23, 1976 [IL] |
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49635 |
Jun 23, 1976 [IL] |
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49875 |
Aug 20, 1976 [IL] |
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50317 |
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Current U.S.
Class: |
210/107; 210/108;
210/355 |
Current CPC
Class: |
B01D
29/60 (20130101); B01D 29/902 (20130101); B01D
29/684 (20130101); B01D 29/114 (20130101); B01D
29/117 (20130101); B01D 29/682 (20130101); B01D
29/114 (20130101); B01D 29/117 (20130101); B01D
29/60 (20130101); B01D 29/682 (20130101); B01D
29/684 (20130101); B01D 29/902 (20130101) |
Current International
Class: |
B01D
29/11 (20060101); B01D 029/38 () |
Field of
Search: |
;210/791,797,798,107,108,355,413,414 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wyse; Tom
Attorney, Agent or Firm: Barish; Benjamin J.
Parent Case Text
.Iadd.This application is a continuation of application Ser. No.
06/62,853, filed July 31, 1979. .Iaddend.
Claims
What is claimed is:
1. A self-cleanable filter, comprising: a housing having a fluid
inlet, a fluid outlet, and a dirt purging opening; a filter body
within the housing and having a .Iadd.cylindrical upstream
.Iaddend.surface facing the inlet side of the housing; and a
cleaning body within the housing and movable .Iadd.axially
.Iaddend.from a home position along said cylindrical .Iadd.upstream
.Iaddend.surface of the filter body for cleaning same; said
cleaning body comprising a first section defining an internal
chamber having .[.an.]. .Iadd.a circular .Iaddend.inlet opening
facing the surface of the filter body to be cleaned and movable
.Iadd.axially .Iaddend.along said surface for cleaning same; and a
second section closing the dirt purging opening when the cleaning
body is in its home position, said second section having an outlet
opening communicating with said internal chamber and located within
said housing in the home position of the cleaning body but movable
through the housing purging opening to a position externally of the
housing upon the movement of the cleaning body for cleaning the
filter.
2. A filter according to claim 1, wherein said second section of
the cleaning body includes a hollow rod communicating at one end
with said internal chamber and formed at its opposite end with said
outlet opening.
3. A filter according to claim 2, wherein .[.the filter body
includes a cylindrical surface to be cleaned, and.]. said second
section of the cleaning body includes a plurality of said hollow
rods disposed in a circular array with respect to said cylindrical
surface of the filter body, one of the ends of the rods
communicating with the internal chamber of said first section, the
opposite ends of the rods projecting through the housing and being
connected together by a circular member externally of the
housing.Iadd., said opposite ends of the rods being formed with
said outlet openings which are normally disposed within the housing
but are movable externally thereof upon the axial movement of the
cleaning body.Iaddend..
4. A filter according to claim 1, wherein said first section of the
cleaning body is in the form of an annular ring defining an annular
internal chamber.
5. A filter according to claim 4, wherein said filter body is of
cylindrical shape and its outer surface faces the inlet side of the
housing, said annular ring of the cleaning body first section being
disposed around said cylindrical filter body and including said
circular inlet opening on its inner surface.
6. A filter according to claim 4, wherein said filter body is of
cylindrical shape and its inner surface faces the inlet side of the
housing, said annular ring of the cleaning body first section being
disposed within said cylindrical filter body and including said
circular inlet opening on its outer surface.
7. A filter according to claim 1, further including
pressure-sensing means for sensing the pressure difference at the
inlet and outlet of the housing, and drive means effective, upon
sensing a predetermined pressure difference, to move said cleaning
body along the filter body for cleaning same.
8. A filter according to claim .[.7, wherein said.]. .Iadd.1,
further including .Iaddend.drive means .[.comprises.].
.Iadd.comprising .Iaddend.a cylinder fixed to said housing, and a
piston movable therein and fixed to said cleaning body externally
of the housing.
9. A filter according to claim 8, wherein said drive means
comprises a plurality of cylinders fixed to said housing around the
circumference thereof, and a plurality of pistons, one movable
within each cylinder, fixed to said cleaning body externally of the
housing. .[.10. A filter according to claim 7, wherein said
pressure-sensing means comprises a displaceable member within the
housing having one surface exposed to the inlet side of the housing
and its opposite surface exposed to the outlet side of the housing
so as to be displaceable to actuate said drive means upon the
presence of a predetermined pressure difference at the inlet and
outlet of the housing..]. .[.11. A filter according to claim 10,
wherein said pressure-sensing means further comprises a control
line connected to said drive means and having an inlet exposed to
the housing inlet pressure, said displaceable member carrying a
control element blocking said control line inlet but unblocking
same when the displaceable member senses predetermined pressure
difference between the housing inlet and outlet..]. .[.12. A filter
according to claim 1, wherein said housing is of cylindrical shape
and said filter body is also of cylindrical shape and is disposed
within the housing coaxially thereto..]. .[.13. A filter according
to claim 1, wherein said housing includes a first section formed
with said inlet and outlet, and a second section depending from the
first section between the inlet and outlet, said filter body being
of cylindrical shape and disposed in the second housing section,
and said dirt purging opening being disposed in the bottom of the
second section..]. .[.14. A filter according to claim 13, wherein
said first section of the cleaning body includes an annular ring
defining an annular chamber formed with a circular inlet opening
movable along the surface of the filter body to be cleaned; and
wherein said second section of the cleaning body includes a hollow
rod communicating at one end with said annular chamber and closed
at its opposite end, said cleaning body outlet opening being formed
through a wall of the hollow rod adjacent to its closed end, the
outer surface of the hollow rod including a recess between its
outlet opening and closed end such that in the home position of the
cleaning body the closed end of its hollow rod is disposed within
the dirt purging opening of the housing, with the hollow rod outlet
opening disposed within the housing, but upon movement of the
cleaning body to clean the filter body, the hollow rod recess first
moves into the housing purging opening to permit the discharge of
dirt particles from the bottom of the second section of the
housing, and then the hollow rod outlet opening moves into and
through the purging opening to discharge dirt particles washed from
the filter body through the annular chamber and hollow rod of the
cleaning body..]. .[.15. A filter according to claim 13, wherein
said filter body is of cylindrical shape, the inner surface thereof
facing the fluid inlet side of the housing, and the outer surface
thereof facing the fluid outlet side of the housing, the cleaning
body being movable within the filter body to clean the inner
surface thereof..]. .[.16. A filter according to claim 13, wherein
said cleaning body further includes a recipricatory drive shaft
fixed to the cleaning body coaxial to the filter body and extending
through an opening formed in the upper wall of the first section of
the housing..]. .[.17. A filter according to claim 16, wherein said
drive shaft carries a piston at one end movable within a cylinder
fixed to the first section of the
housing..]. 18. A filter according to claim 1, further including
sensor means for sensing the pressure difference at the inlet and
outlet of the housing, fluid control means responsive to the
sensing of a predetermined magnitude of pressure difference for
automatically driving the piston a complete forward stroke within
the cylinder thereby moving the cleaning body the complete length
of the filter body, and limit means sensing the end of the forward
stroke of the piston for driving same a complete return stroke and
thereby returning the cleaning body to its home position with
respect to the filter body. 19. A filter according to claim 18,
further including means for disabling said sensor in all positions
of the cleaning
body except its home position. 20. A filter according to claim 1,
wherein said surface of the filter body facing the housing inlet is
cylindrical, and said cleaning body is rotatable about the
longitudinal axis of said cylindrical surface of the filter body
for causing the inlet opening of
the cleaning body to sweep across said cylindrical surface. 21. A
filter according to claim 20, wherein the cleaning body, in
addition to being rotatable about the longitudinal axis of the
cylindrical surface of the filter body, is also movable along said
longitudinal axis to move the outlet opening of the cleaning body
through .[.the.]. .Iadd.a .Iaddend.housing opening and thereby to
initiate a self-flushing of the
filter. 22. A filter according to claim 21, wherein said second
section of the cleaning body includes a hollow rod communicating at
one end with said internal chamber and provided with said outlet
opening at its opposite end, said opposite end of the hollow rod
further including a plug and a radially recessed connection between
same and said outlet opening such that in the home position of the
cleaning body the plug is disposed within .[.the dirt purging.].
.Iadd.said .Iaddend.opening of the housing, with the cleaning body
outlet opening disposed within the housing, but upon movement of
the cleaning body to initiate the self-flushing of the filter body,
said recessed connection first moves into the housing .[.purging.].
opening to discharge dirt particles from the bottom of the second
section of the housing, and then the cleaning body outlet opening
moves into and out through the .[.purging.]. opening to discharge
dirt particles flushed from the filter body through the internal
chamber and hollow rod of the
cleaning body. 23. A filter according to claim 20, wherein said
cleaning body includes a third section in the form of a dirt
purging conduit extending externally of the housing and having an
inlet connected to said second section of the cleaning body and an
outlet eccentric to the axis of rotation of the cleaning body so as
to rotate same by the reaction force
of the fluid exiting from the purging conduit. 24. A filter
according to claim 20, wherein the cleaning body is movable both
rotatably about the axis of the filter body and longitudinally of
said axis for the complete length of said cylindrical surface of
the filter body for causing the inlet opening of the cleaning body
to sweep across said cylindrical surface along a spiral path.
.[.25. A self-flushing filter, comprising: a housing having a fluid
inlet and a fluid outlet; a filter body within the housing and
having a cylindrical surface facing the inlet side of the housing;
a cleaning body having an inlet adjacent to the filter body and an
outlet connectible to the atmosphere for effecting a self-flushing
action of the filter body via the inlet of the cleaning body, said
cleaning body being rotatable about the axis of the filter body and
also being movable longitudinally of the said axis for the complete
length of said cylindrical surface of the filter body for causing
the inlet of the cleaning body to sweep across said cylindrical
surface along a spiral path; and drive means for moving said
cleaning body both rotatably about
and longitudinally of said axis..]. .[.26. A filter according to
claim 25, wherein said inlet of the cleaning body is of a
relatively small cross-sectional area..]. .[.27. A filter according
to claim 25, wherein said drive means is automatically actuated
upon sensing a predetermined difference in fluid pressure at the
housing inlet and outlet..]. .[.28. A filter according to claim 27,
wherein said drive means comprises: a piston fixed to the cleaning
body and movable in a cylinder fixed to the housing; a sensor for
sensing the difference in pressure at the housing inlet and outlet
and actuating said piston upon sensing a predetermined pressure
difference; and a purging conduit connected at one end to the
cleaning body, the opposite end of the purging conduit having an
outlet which is eccentric to the axis of rotation of the cleaning
body so as to rotate same by the reaction force of the fluid
exiting from the purging conduit..]. .[.29. A filter according to
claim 25, wherein said drive means is manually actuated..]. .[.30.
A filter according to claim 29, wherein said manually-actuated
drive means comprises a sleeve fixed to the cleaning body and
having an outer surface formed with spiral threads cooperating with
internal spiral threads formed in the housing, a manually rotatable
member formed with longitudinal ribs, the inner surface of the
sleeve being formed with longitudinal recesses cooperable with the
longitudinal ribs in the manually rotatable member, the arrangement
being such that the manual rotation of said latter member displaces
said sleeve, and thereby the cleaning body affixed thereto, in a
rotatable direction by virtue of said threads and in a longitudinal
direction by virtue of said recesses, to thereby cause the cleaning
body to sweep across the cylindrical surface of the filter body
along a spiral path..]. .[.31. A self-flushing filter, comprising:
a housing having a fluid inlet and a fluid outlet; a filter body
within the housing and having a cylindrical surface facing the
inlet side of the housing; a cleaning body coaxially disposed with
respect to said filter body and including an internal chamber
having a circular inlet opening adjacent to said cylindrical
surface of the filter body, said cleaning body further including an
outlet connectable to the atmosphere for effecting a self-flushing
action of the filter body via said circular inlet opening; and
drive means for moving said cleaning body longitudinally of the
axis of the filter body to cause the circular inlet opening of the
cleaning body to sweep along said cylindrical surface of the filter
body..]. .[.32. A self-flushing filter, comprising: a housing
having a fluid inlet and a fluid outlet; a filter body within the
housing and having a cylindrical surface facing the inlet side of
the housing; a deflector deflecting the fluid to flow from the
fluid inlet, through the filter body, and then out through the
fluid outlet; a cleaning body having an inlet adjacent to the
filter body and an outlet connectable to the atmosphere for
effecting a self-flushing action of the filter body via the inlet
of the cleaning body; drive means for moving said cleaning body
with respect to said filter body to cause the cleaning body inlet
to sweep along the cylindrical surface of the filter body facing
the inlet side of the housing; and pressure-sensing means disposed
within said deflector for sensing the pressure difference at the
inlet and outlet sides of the housing and effective, upon sensing a
predetermined difference, to actuate said drive means..]. .Iadd.33.
A self-cleanable filter, comprising: a housing having a fluid
inlet, and a fluid outlet, a filter body within the housing and
having a cylindrical surface facing the inlet side of the housing;
and a cleaning body within the housing and movable axially from a
home position along said cylindrical surface of the filter body for
cleaning same; said cleaning body comprising a first section
defining an internal chamber having a circular inlet opening facing
the surface of the filter body to be cleaned and movable axially
along said surface for cleaning same; and a second section having
an outlet opening communicating with said internal chamber and
located within said housing in the home position of the cleaning
body but movable, upon the axial movement of the cleaning body, to
connect said internal chamber to the atmosphere for cleaning the
filter body by producing a reverse flow of fluid therethrough to
the atmosphere, said second section of the cleaning body including
a plurality of hollow rods disposed in a circular array with
respect to said cylindrical surface of the filter body, one of the
ends of the rods communicating with the internal chamber of said
first section, the opposite ends of the rods projecting through the
housing and being connected together by a circular member
externally of the housing, said opposite ends of the rods being
formed with outlet openings which are normally disposed within the
housing but are movable externally thereof upon the axial movement
of the cleaning body..Iaddend.
Description
RELATED APPLICATIONS
This application is related to my patent application Ser. No.
727,859.Iadd., now U.S. Pat. No. 4,045,345, .Iaddend.filed on the
same date as the present application and also to my patent
application Ser. No. 715,544 filed Aug. 18, 1976.Iadd., now U.S.
Ser. No. 4,067,812.Iaddend..
BACKGROUND OF THE INVENTION
The present invention relates to filters, and is particularly
directed to an arrangement which enables the filter to be
conveniently or automatically cleaned.
Filters, such as those used in water irrigation systems, require
periodic cleaning. This usually involves closing down the supply
line in which the filter is used, dismantling the filter, cleaning
its parts, and then re-assembling it. Such a procedure is very
time-consuming and costly. A number of arrangements have been
proposed for providing filters with a self-cleaning capability, but
the known arrangements are generally .[.extremely.]. costly and/or
inefficient.
SUMMARY OF THE INVENTION
According to a broad aspect of the present invention, there is
provided a self-cleanable filter, comprising: a housing having a
fluid inlet, .Iadd.and .Iaddend.a fluid outlet.[., and a dirt
purging opening.].; a filter body within the housing and having a
surface facing the inlet side of the housing; and a cleaning body
within the housing and movable .Iadd.axially .Iaddend.from a home
position along said surface of the filter body for cleaning same.
The cleaning body includes a first section defining an internal
chamber having .[.an.]. .Iadd.a circular .Iaddend.inlet opening
facing the surface of the filter body to be cleaned and movable
.Iadd.axially .Iaddend.along said surface for cleaning same, and a
second section .[.closing the housing purging opening when the
cleaning body is in its home position. The second cleaning body
section has.]. .Iadd.having .Iaddend.an outlet opening
communicating with the mentioned internal chamber.[.,
which.]..Iadd.. The latter .Iaddend.outlet opening is located
within the housing when the cleaning body is in its home position,
but is movable .[.through the housing purging opening to a position
externally of the housing upon the movement of the cleaning body
for cleaning the filter..]..Iadd., upon the axial movement of the
cleaning body, to connect the internal chamber to the atmosphere
for cleaning the filter body by producing a reverse flow of fluid
therethrough to the atmosphere. .Iaddend.
A number of embodiments of the invention are described below for
purposes of example.
According to another important feature present in the described
preferred embodiments, the filter further includes pressure-sensing
means for sensing the pressure difference at the inlet and outlet
of the housing, and drive means effective, upon sensing a
predetermined pressure difference, to move the cleaning body along
the filter body for cleaning same. This feature makes the filter
automatically self-cleaning whenever it becomes so blocked with
dirt that the pressure difference between its inlet and outlet
rises to a predetermined value.
Further features and advantages of the invention will be apparent
from the description below.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is herein described, by way of example only, with
reference to the accompanying drawings, wherein
FIGS. 1-6 are longitudinal sectional views of six forms of
self-cleaning filters constructed in accordance with the
invention,
FIGS. 1a, 4a and 5a .[.being.]. .Iadd.are .Iaddend.sectional views
along lines IA, IVA, VA of FIGS. 1, 4 and 5, respectively,
FIGS. 6a and 6b being sectional views along lines VIA and VIIB of
FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The filter illustrated in FIGS. 1 and 1a is of the on-line type
described in FIGS. 1 and 2 of the above-cited patent application
Ser. No. 715,544 but modified to include the self-cleanable feature
of the present invention. The filter includes an inner rigid core,
generally designated 2, constituted of an inner metal tube 3 and an
outer plastic body 4 bonded thereto. The opposite ends of metal
tube 3 serve as the inlet 5 and outlet 6 of the filter and are
adapted to be threadedly attached to the upstream and downstream
pipes, respectively. The filter further includes a conical
deflector 10 fixed within the inner rigid metal tube 3 between one
group of radial holes 12 and a second group of radial holes 14
formed through the wall of the tube at longitudinally-spaced
locations. The filter further includes an outer tubular housing 16
which is radially spaced from core 2 and is removably secured
thereto at one end by threads 18. A wall 19 formed at one end of
tubular housing 16 and an O-ring 19' seals-off one side of the
space between the housing and the inner core, the opposite side of
that space being sealed-off by an annular flange 20 integrally
formed with the plastic body 4 and carrying an O-ring 22 sealingly
engaging the open end of housing 16. A filter body 24 of
substantially cylindrical form is disposed in the space between
core 2 and housing 16 and overlies the radial holes 14 formed
through the core.
It will be seen that the water flowing through inlet 5 is deflected
by deflector 10 to flow through holes 12, filter 24, holes 14 back
into the interior of the inner rigid tube 2, and then through
outlet 6. Further details of the construction and operation of such
a filter may be found in the above-cited Patent Application.
In accordance with the present invention, the filter illustrated in
FIGS. 1 and 1a is provided with a cleaning body within housing 2
movable in a rectalinear path along the outer cylindrical surface
of the filter body 24 for cleaning it. The cleaning body, generally
designated 30, comprises a first section 32 in the form of an
annular ring defining an annular internal chamber 34, and a second
section comprising a plurality (e.g., three) hollow rods 36
disposed in a circular array with respect to the outer cylindrical
surface of the filter body 24. One end of each of the hollow rods
36 communicates with the internal chamber of the annular ring 32,
and their opposite ends project through sealed dirt-purging
openings 37 in wall 19 of the housing and are connected to a common
ring 38 by means of bolts 40. Each of the hollow rods 36 is formed
with an opening 42 normally located within housing 16, but movable
with the complete cleaning body 30 so as to be disposed externally
of the housing when the filter is to be cleaned. Annular ring
section 32 of the cleaning body is formed with a circular inlet
opening 44 adapted to be moved along the outer surface of the
filter body 24 during this cleaning operation.
The filter illustrated in FIGS. 1 and 1a further includes a
pressure-sensing means for sensing the pressure difference at the
inlet 5 and outlet 6 of the housing, and drive means effective,
upon sensing a predetermined pressure difference, for moving the
cleaning body along the filter body in order to clean it.
The drive for the cleaning body 30 comprises three cylinders 50
integrally formed with the outer housing 16. Each cylinder 50
includes a piston 52 normally disposed in its home position
adjacent to wall 54 at the inlet 5 side of the filter and defines a
chamber 56 with that wall. The opposite face of each piston 52
defines a second chamber 58 with wall 60 at the opposite end of
cylinder 50. Piston 52 includes a stem 62 which passes through a
sealed opening in end wall 60 and is attached to external ring 38
by means of bolts 64.
As will be described more particularly below, whenever it is
desired to effect the cleaning operation, chambers 56 of the
cylinders 50 are pressurized, thereby driving the pistons 52
rightwardly. This movement of the pistons is transmitted via their
stems 62 and external ring 38 to the hollow rods 36 of the cleaning
body 30, these rods being fixed to the same external ring 38 as the
piston stems 62. Thus, when chambers 56 of cylinders 50 are
pressurized, the annular ring 32 of the cleaning body 30 is moved
right-wardly along the outer surface of the filter body 24. The
annular ring 32 is returned by pressurizing chambers 58 in
cylinders 50.
The pressure-sensing means for automatically actuating the
above-described drive includes a diaphragm 70 disposed within
deflector 10, the deflector including an opening 72 for exposing
the left face of the diaphragm to the pressure at the inlet side 5
of the filter housing. The opposite face of diaphragm 70 is exposed
to the pressure at the outlet side 6 of the housing by means of
another opening 74 formed in the rear wall 76 of the deflector.
Diaphragm 70 is spring-urged towards the inlet side of the housing
by means of a coil spring 80 interposed between rear wall 76 of the
deflector and a circular disc 82 engaging or fixed to the
respective face of the diaphragm. Disc 82 includes a guiding stem
84 passing through a central opening formed in the rear wall 76 of
the deflector 10.
The opposite face of diaphragm 70, i.e., that facing the inlet 5
side of the filter, carries a central valve member 86 which is
adapted to move into or out of engagement with respect to an inlet
88 of an axial bore 90 formed in a stem 91 of deflector 10. The
opposite end of bore 90 terminates in a nipple 92 which receives a
control line 94 leading to an external connector 96 on the
filter.
The filter includes two further groups of external connectors,
namely connectors 98 from chambers 56 of cylinders 50, and
connectors 100 from chambers 58 of cylinders 50. Each of the
cylinders 50 is also provided with a small vent opening 102 at the
right end of its respective chamber 58, vent 102 being of smaller
cross-sectional area than that of the opening in external connector
100 from chamber 58.
For purposes of explaining the operation of the device, the
pressure at the external connector 96 is designated "P", that at
the external connector 98 is designated "L", and that at the
external connectors 100 is designated "D". The device operates as
follows:
If the filter body 24 is reasonably clean, there is but a small
drop in pressure during the flow of the water through the filter
body 24, and therefore the pressure at the outlet 6 will be but
slightly below that at the inlet 5. Diaphragm 70 senses the
difference in pressure between the inlet and outlet, via openings
72 and 74 respectively, and spring 80 is designed so that valve
member 86 carried centrally of diaphragm 70 will be in contact with
the inlet 88 of bore 90 connected to the control line 94 at all
times that the pressure difference between the inlet and outlet is
below a predetermined amount, i.e. when the filter is reasonably
clean.
Now, as dirt accumulates on the filter body 24, particularly on its
outer cylindrical surface facing the inlet 5, a drop in the outlet
pressure occurs, thereby increasing the difference in pressure
between the inlet and outlet. When this pressure difference reaches
a predetermined magnitude, diaphragm 70 flexes (rightwardly) such
that its valve member 86 separates from the inlet 88 of bore 90.
The inlet pressure "P" is now applied, via control line 94 and
external connector 96, to a fluid control device 104 which causes
chamber 56 of the cylinders 50 to become pressurized, via their
external connectors 98, thereby driving the pistons 52 rightwardly
in their cylinders. External ring 38 is thereby driven rightwardly
by the piston stems 62, which external ring in turn drives the
cleaning body 30 rightwardly via the right ends of the hollow rods
36 connected to the external ring.
As the cleaning body 30 is thus driven rightwardly, the openings 42
in the hollow rods 36 of the cleaning body move externally of the
housing and thus become vented to the atmosphere. This occurs just
as the circular inlet 44 of the cleaning body annular ring 32
approaches the end (left) of the filter body 24. At this time, the
pressure within the hollow rods 36 is atmospheric, whereas the
pressure at the outlet 6 of the filter is substantially higher.
Accordingly, the higher water pressure in the center of core 2 will
produce a reverse flow of water from the outlet 6 through the
filter 24, circular opening 44, annular chamber 34, the center of
the hollow rods 36, and outlet openings 42 which are then external
to the housing.
Thus, as the cleaning body 30 is driven rightwardly by the pistons
52, its circular inlet opening 44 sweeps along the outer
cylindrical surface of the filter body 24 while the dirt from the
filter body is washed out through circular opening 44 into annular
chamber 34 and out through the outlet openings 42. An interplay of
three pressures is involved at the mouth of circular opening 44,
namely the outlet (6) pressure at one side of the opening, the
inlet (5) pressure at the other side of the opening, and
atmospheric pressure within the opening, all of which tend to
agitate the water at the mouth of the opening to enhance the
cleaning action.
The cleaning body 30 is returned to its initial home position by
pressurizing chambers 58 of the cylinders 50, which returns pistons
52, and thereby the annular ring 32, to their illustrated home
positions.
Many control arrangements are known for driving the postons 52
rightwardly when external connector 96 becomes pressurized in the
manner described above, and for returning the pistons to their home
positions when they have reached their limit of travel. FIG. 1
illustrates one form of fluid control device 104 which may be used.
It comprises a housing 106 having a first piston 108 movable
therein and having a stem 109 bearing against a second piston 110
biassed by a return spring 112. Housing 106 is formed with a vent
114, and piston 110 is formed with a stem 115 having an axial bore
116 extending therethrough. Stem 109 of piston 108 is formed with a
first axial bore 118 through one end, and a second axial bore 120
through the opposite end, the two bores terminating short of each
other. Bore 118 communicates with a radial port 122, and bore 120
communicates with a second radial port 124. The device further
includes a sleeve 126 having a first external connector 128 adapted
to be connected by a tube to external connectors 100 from chambers
58 of the cylinders 50 (and thereby to receive pressure "D"), and
with a second external connector 130 adapted to be connected by a
tube to the external connectors 98 leading to chambers 56 of the
cylinders (and thereby adapted to receive pressure "L").
Sleeve 126 further includes a pair of projections 132, 134 adapted
to receive between them one arm of a lever 136 pivotably mounted at
138 to an arm 140 fixed to housing 106 of the control device. Arm
136 includes an over-center spring 142 which produces a snap-action
movement of the arm. The arm is actuated at the two limits of
travel of pistons 52 by means of a pair of abuttments carried on an
arm 144 fixed to the external ring 38 to which the piston stems 62
are also fixed. One abuttment 146 is disposed at one end of arm 144
to pivot lever 136 in one direction (counter-clockwise) when the
pistons 52 have travelled to their rightmost positions, and a
second abuttment 148 is adapted to pivot lever 136 in the opposite
direction (counter-clockwise) when the pistons have returned to
their illustrated home positions.
The control device 104 actuates the cleaning body 30 to effect a
self-cleaning operation in the following manner:
When the filter body 24 is clean, diaphragm 70 causes its valve
member 86 to engage the end of deflector stem 91, and therefore
pressure "P", applied via connectors 96 and 107, is low. Thus, the
pistons 108 and 110 in control device 104 will be in their extreme
rightmost positions under the influence of spring 112. In this
position, the pressure to chamber 58, via connectors 128 and 100,
will be low. However, pressure is continuously applied via vent 102
to chamber 58, thereby forcing piston 52 to the illustrated
leftmost home position, connector 130 (pressure "L") being vented
to the atmosphere via bores 118, 116, 114.
Now, when diaphragm 70 senses a difference in pressure between the
inlet 5 and outlet 6 which is greater than a predetermined
magnitude, it moves away from deflector stem 91, uncovering the
inlet end 88 of bore 90, whereby pressure "P" is applied to
external connectors 96 and 107. This causes the pistons 108 and 110
to be moved leftwardly against spring 112. When this occurs,
chamber 58 is vented to the atmosphere via connectors 100, 128, and
bores 118, 116, 114; whereas high pressure "P" is applied to
chamber 56 via connectors 107, 130, 98. Thus, the pistons 52 will
be driven rightwardly, thereby also driving the cleaning body 30
rightwardly as the latter cleans the outer surface of the filter
body 24 in the manner described below.
It will be noted that during this point in the operation of the
device, although pressure is applied via bleeding openings 102 into
the chambers 58, these openings are of smaller cross-sectional area
than the openings provided by the external connectors 100, so that
the pressure within chamber 58 is dissipated through external
connectors 100 to permit the driving of the pistons 52 by
pressurizing chambers 56.
When the pistons 52 and the cleaning body 30 have been driven to
their rightmost positions stop 146 on arm 144 connected to the
external ring 38 engages arm 136 and produces a snap-action which
shifts sleeve 126 leftwardly. When this occurs, chambers 56 are
vented to the atmosphere via connectors 98, 130, and bores 118,
116, 114, so that the pressure applied to chambers 58 via openings
102 drives the pistons 52 leftwardly to return them and the
cleaning body 30 to their home (leftmost) positions.
It will thus be seen that so long as the pressure differential
between the inlet 5 and outlet 6 is below a predetermined maximum,
the pistons 52 are not actuated, and therefore the cleaning body 30
remains in its normal non-operative position illustrated in FIG. 1.
However, as soon as, and so long as, the pressure differential
exceeds a predetermined magnitude, as sensed by the deflection of
diaphragm 70, the inlet pressure is applied via line 94 and control
device 104 to chambers 56 of the cylinders 50 to drive the pistons
rightwardly, and thereby to cause the annular ring 32 of the
cleaning body 30 to sweep along the outer surface of the filter
body 24 and to purge the dirt therefrom via outlet openings 42 in
the cleaning body.
FIG. 2 illustrates another filter including a cleaning device in
accordance with the present invention. Thus, in the arrangement
illustrated in FIG. 2, the filter body 174 is of a common screen
type wherein the water passes through inlet 155 to the interior of
the filter and exists from outlet 156. Thus, in FIG. 2, the
internal cylindrical face of the filter 174 is exposed to the inlet
155 and on it would accumulate most of the dirt. Accordingly, the
annular ring 182 of the cleaning device 180 is movable within the
cylindrical filter 174, and includes an internal chamber 184 having
an inlet in the form of a circular opening 194 in the outer surface
of the ring so as to sweep along the inner surface of the filter
body 174. Annular ring 182 is connected to a central hollow shaft
186. One end of shaft 186 communicates with chamber 184 via hollow
arms 187, and the opposite end of the shaft is formed with openings
192 which are normally disposed within the housing 152 of the
filter, but which are moved externally of the housing through a
dirt-purging port 193 when the cleaning body 180 is actuated to
clean the filter.
The cleaning body 180 in FIG. 2 may be actuated manually by merely
providing the end of rod 186 with a handle 198 for manual pulling
same.
The automatic arrangement illustrated in FIG. 1 could be included
in FIG. 2, and the manual arrangement of FIG. 2 could likewise be
used in FIG. 1.
FIG. 3 illustrates the invention embodied in an off-line type
filter of the construction illustrated in FIGS. 3 and 4 of my
patent application Ser. No. 715,544. This embodiment of the
invention includes a further variation in the operation of the
cleaning body, which cleaning operation is initiated whenever the
predetermined pressure difference is sensed between the inlet and
outlet, and once initiated, it continues (even though the above
condition terminates) for a complete forward stroke and then for a
complete return stroke of the cleaning body. If the predetermined
pressure difference continues to exist when the cleaning body has
returned to its home position (thereby indicating the filter is
still too dirty), another complete cycle, including a foward stroke
and a return stroke, will again be initiated.
The filter of FIG. 3 generally comprises five main members as in
FIGS. 1 and 1a, namely: an inner rigid tube of great mechanical
strength (e.g. of metal) generally designated 202; an outer housing
of less mechanical strength (e.g. of plastics) generally designated
204; a cylindrical filter body generally designated 206; a
deflector generally designated 208 disposed within the inner rigid
tube 202; and a cleaning body, generally designated 240, for
cleaning the filter.
The outer housing 204 is made of two sections, namely a horizontal
section 204a parallel to and overlying tube 202, and a vertical
section 204b below and at right angles to housing section 204a and
tube 202. The cylindrical filter body 206 is disposed within the
vertical housing section 204b.
The inner rigid metal tube 202 includes threads at its opposite
ends, i.e. inlet end 202a and outlet end 202b, for connecting same
to the upstream and downstream pipes (not shown), respectively.
Tube 202 is further formed with one or more openings 210 (a
plurality being shown) through its wall on one side of deflector
208, and with similar one or more openings 212 through its wall on
the other side of the deflector, so that the deflector is located
between these axially-spaced openings 210, 212. The deflector 206
and the horizontal housing section 204a are preferably both formed
simultaneously by injection moulding plastics material over and
within the inner rigid tube 202, such that some of the plastics
material also flows through additional openings 214 in the inner
rigid tube 202 to firmly fix the deflector 206 and the horizontal
housing section 204a to the tube 202.
One end of the horizontal housing section 204a is radially spaced
from holes 210 to provide a first chamber 216, and the opposite end
of the horizontal housing section is radially spaced from holes 212
to provide a second chamber 218, the two chambers being separated
by partition 215 constituted by the plastics material flowing
through openings 214 during the injection moulding of the housing
section 204a and the deflector 208. End caps 220 and 222 are
threaded onto the ends of the housing section 204a into engagement
with the respective ends of the inner tube 202 and thereby serve as
end walls sealing the respective ends of the chambers 216 and
218.
The horizontal housing section 204a if formed with an internally
threaded socket 224 depending from its lower surface, which socket
receives the vertical housing section 204a for the filter body 206,
section 204a being threaded at its upper end for mating with the
threads of socket 224. The lower wall of the horizontal housing
section 204a further includes a depending annular flange or ledge
228 within socket 224, and the inner surface of the vertical
housing section 204b includes another annular ledge 230 aligned
with ledge 228. The filter body 206 is constituted of a stack of
filter discs clamped between the annular ledges 228 and 230 when
the vertical housing section 204b is threaded within socket 224 of
the horizontal housing section 204a.
The inner surface of housing section 204b is formed with a
plurality of axially-extending circumferentially-spaced ribs 234
which engage the outer surfaces of the filter body 206 so as to
space them from the internal surface of the housing section 204b.
The outer surface of housing section 204b may be similarly formed
with a plurality of axially-extending circumferentially-spaced ribs
235 to facilitate its manual rotation when it is threaded into
socket 224 of the horizontal housing section 204a.
The horizontal housing section 204a is further formed with a large
opening 236 inboard of its annular ledge 228 so as to establish
communication (via holes 210) between the interior of filter body
206 and the inlet end 202a of tube 202, and with a smaller opening
237 between annular ledge 228 and its socket 224 to establish
communication (via holes 212) between the outlet end 202b of the
tube and the space between the outer surface of the filter body 206
and the inner surface of the vertical housing section 204b. The
bottom of housing section 204b is formed with a dirt-purging port
238 communicating with the interior of the filter body 206, which
port is opened by withdrawing a plug (250, as described below) in
order to discharge from the filter the dirt particles accumulating
in the bottom of housing section 204b.
When using the illustrated filter, its inlet end 202a is connected
to the upstream pipe and its outlet end 202b is connected to the
downstream pipe. The water flows into inlet 202a and, being blocked
by deflector 208, is forced to flow through holes 210 into chamber
216, through opening 236 into the interior of the cylindrical
filter body 206, through the filter body (namely through the spaces
between its discs) to the space between the external surface of the
filter body and the internal surface of the housing section 204b,
through opening 237 into chamber 218, and finally through holes 212
back into the interior of tube 202 and out through its outlet end
202b. Further details of the construction of the filter of FIG. 3
may be had from my above-cited Patent Application.
A cleaning body, generally designated 240, is disposed within the
cylindrical filter body 206 and moves in a rectilinear path within
it to clean its inner surface 241. Cleaning body 240 is of
generally the same construction as illustrated in FIG. 2 above. It
includes a first section in the form of an annular ring 242, and a
second section in the form of a hollow rod 244. Annular ring 242
defines an inner annular compartment 246 having a circular inlet
opening 248 located adjacent to the inner surface 241 of the filter
body 206. Hollow rod 244 communicates at one end with the inner
compartment 246 of ring 242. The opposite end of rod 244 carries
plug 250 having a sealing ring 252 disposed within the purging
opening 238 of housing section 204b in the illustrated home
position of the cleaning body 240.
Hollow rod 244 is open at the lower end to define opening 254 just
above its end plug 250. Plug 250 is attached to the lower end of
the rod by means of a plurality of radial vanes 255, to thereby
define as annular recession 256 from its outer surface between the
closed tip of rod 244 (i.e. its plug 250) and its outlet opening
254.
A stem 260 is secured to the upper end of the cleaning body 240 and
passes through an opening in the upper surface of housing section
204a. The upper end of stem 260 carries a piston 262 movable within
a cylinder 264 threadedly received in a socket 265 formed in the
upper surface of housing section 204a. Piston 262 thus defines two
compartments within cylinder 264, namely a first compartment 266
between the piston and end wall 268 of the cylinder, and a second
compartment 270 between the piston and the upper surface of housing
section 204a. A nipple 272 communicates with compartment 266, and a
second nipple 274 communicates with compartment 270 via a
passageway 276 formed in housing section 204a.
It will thus be seen that when compartment 266 is pressurized,
piston 262 and cleaning body 240 are driven (downwardly) through a
forward stroke to cause inlet opening 248 of the cleaning body to
move along the inner surface 241 of the filter body 206; and when
compartment 270 is pressurized, the piston and the cleaning body
are driven through a return stroke (upwardly) to return the piston
and the cleaning body to their illustrated home positions.
The operation of the cleaning body 240 in the filter of FIG. 3 is
automatically initiated upon sensing a pressure difference of
predetermined magnitude between the inlet 202a and the outlet 202b
of the filter. This pressure difference is sensed by a diaphragm
280 fixed among its outer margin within deflector 208 on the outlet
side 202b of the filter. Sensor diaphragm 280 is retained in place
by a cap 292 threaded into an annular surface in deflector 208, the
cap being formed with an opening 284 exposing the respective face
(left) of diaphragm 280 to the outlet pressure. A corresponding
opening 286 is formed in deflector 208 exposing the opposite face
(right) of the diaphragm to the inlet pressure. The latter face of
the diaphragm carries a central valve member 288 which is adapted,
upon deflection of the diaphragm, to move into or out of engagement
with respect to the mouth of an axial bore formed in a central stem
292 of the deflector. The diaphragm 280 is biassed to bring its
valve member 288 into contact with stem 292 by means of a coil
spring interposed between a disc 298 carried by diaphragm 280, and
cap 282 of the deflector. This spring encloses a guiding boss 300
having a reduced end movable within an opening 302 formed centrally
of cap 282.
It will be seen that the latter spring normally biasses diaphragm
280 so that its valve member 288 closes the mouth of the bore in
stem 292. However, should the pressure difference between the
filter inlet 202a and outlet 202b exceed a predetermined magnitude,
as would be the case when the filter body 206 is unduly clogged,
the inlet pressure will cause diaphragm 280 to flex such that its
valve member 288 is moved out of engagement with respect to the
mouth of that bore. When this occurs, the pressurized water from
the outlet end 202b of the filter enters the bore and passes, via
passageway 304, to an external nipple 306. This pressure is then
transmitted to a fluid control device, generally designated 310,
which is used for controlling the movement of the piston 262 within
cylinder 264, and thereby the movement of the cleaning body 240
with respect to the filter body 206.
The fluid control device 310 includes: an inlet opening 312
receiving the pressure from nipple 306 via a tube 314; a further
opening 316 receiving pressurized water via a tube 318 connected
via another nipple 320 to the inlet side 202a of the filter; an
opening 322 connected via tube 324 to nipple 272 communicating with
compartment 266; an opening 326 connected via tube 328 to nipple
274 communicating with compartment 270; and two drain openings 330
and 332.
Within the fluid control device 310 is a stem 334 carrying four
pistons P1, P2, P3 and P4. Stem 334 projects through an end wall
335 of the device, opposite to the end of the control inlet opening
312, and terminates in an enlarged end 336.
The return stroke of the piston 262, and of the cleaning body 240,
is initiated automatically at the end of the forward stroke by
means of a member 340 which is brought into contact with end 336 of
stem 334 of the fluid control device 310. Member 340 is carried at
the end of a lever arm 342 pivotably mounted at 344 and coupled at
346 to a rod 348 disposed within an axial bore 350 in piston stem
260. Rod 348 is formed at its opposite free end with an enlarged
tip 352 of slightly smaller diameter than the diameter of bore 350,
the bore terminating at its upper end in an annular shoulder 354 of
smaller internal diameter than the enlarged tip 352 of the rod.
At the end of the forward stroke of piston 262, enlarged tip 352 of
rod 348 engages shoulder 354 so that the rod is pulled down and
thereby causes its member 340 to engage member 336 and to return
the stem 334 of the fluid control device 310 to its home position
illustrated in the drawings.
In the embodiment of the invention illustrated herein, when a
cleaning cycle of operation is initiate, the cleaning body is first
driven through a complete forward stroke and then is automatically
driven through a complete return stroke back to its illustrated
home position. This cycle of operation is initiated by the
pressure-differential sensor diaphragm 280, which moves away from
the mouth of the bore in stem 292 to transmit a control pressure to
inlet 312 of the fluid control device 310. Once the cleaning
operation is initiated, the fluid control device takes over, and
the sensor diaphragm 280 is disabled. For this purpose, a pin 360
is movable within an opening in deflector 208 at the juncture of
its bore formed in stem 292 and its bore 304 leading to nipple 306,
the opposite end of pin 360 being engageable with piston stem 260.
The latter stem is formed with an enlarged diameter section 364
terminating in an inclined cam surface 365 just above pin 360 in
the home position of piston 262 and its stem 260, the lower section
260' of stem 260 being of smaller diameter than its section
364.
The arrangement is such that the illustrated home position of
piston 262 and its stem 260, pin 360 engages the smaller diameter
section 260' of the stem so that communication is permitted between
bore 304 and the bore in stem 292 whereby the sensor is enabled to
transmit or not transmit pressurized fluid to bore 304 according to
the pressure difference sensed by the diaphragm 280 as described
above. However, in all other positions of the piston 262 and its
stem 260, pin 360 engages the larger diameter section 364 of stem
260, blocking the communication between these bores and thereby
disabling the diaphragm 280 from transmitting pressurized fluid via
bore 304 to inlet 312 of the valve control device 310.
The operation of the device of FIG. 3 is as follows:
Normally, when the filter body 228 is relatively clean, the
pressure at the filter outlet 202b will be only slightly less than
that at the inlet 202a, so that diaphragm 280 will be urged by
spring 296 to bring its valve member 288 against the mouth of the
bore within the deflector stem 292. At this time, the fluid control
device 310 will be in the home position illustrated in the
drawings, since the inlet pressure introduced via nipple 320, tube
318, and opening 316, is transmitted via opening 326, tube 328, and
nipple 274 to compartment 270, so that piston 262 would be urged to
its home position. In this position, the cleaning body 240 is also
in its home position wherein the circular inlet opening 248 of its
annular ring 242 is disposed at the upper edge of the filter body
206, and openings 254 in the hollow rod 244 are disposed within
housing section 204b, the purging opening 238 of the housing being
closed by the plug 250 at the tip of the hollow rod 244.
Now, as the filter becomes clogged with dirt particles in the water
flowing through the inlet 202a, an increasing pressure drop occurs
between the pressure at the inlet 202a and the outlet 202b. When
this pressure drop exceeds a predetermined magnitude, the inlet
pressure flexes diaphragm 280 such as to bring its control member
288 out of engagement with the mouth of the bore in stem. At this
time, the inlet pressure is applied via bore 304, nipple 306, and
tube 314 to the control inlet 312 of the fluid control device 310,
causing the piston rod 334 to move to its upper position. In this
position, the inlet pressure introduced into opening 316 passes
through outlet opening 322 and is transmitted via tube 324 and
nipple 272 to compartment 266, compartment 270 on the other side of
the piston being vented to the atmosphere via nipple 274, tube 328,
opening 326, and drain opening 332.
Piston 262 is then driven downwardly, thereby also driving
downwardly the cleaning body 240.
Upon the initial movement of hollow rod 244 of the cleaning body,
plug 250 withdraws from, and annular recess 256 enters into, the
purging opening 238. When this occurs, the dirt particles that have
accumulated in the bottom of section 204b of the housing are washed
out of the filter. As the piston 262 and cleaning body 240 continue
to move downwardly, rod 244 moves through the purging opening 238
until its outlet opening 254 is located externally of the housing.
The interior of rod 244 and annular chamber 246 is thus vented to
the atmosphere, so that as the inlet circular opening 248 of the
cleaning body sweeps along the inner surface of the filter body
206, it picks up the dirt particles from the filter body and washes
them out through opening 254 of the hollow rod 244.
The cleaning device 240 is thus driven through a complete forward
stroke until its inlet opening 248 moves to the lowermost end of
the filter body 206. Stem 260 of piston 262 will also have moved to
its lowermost position, at which time the internal annular shoulder
354 within stem 260 engages the enlarged tip 352 of rod 348. When
this occurs, the further downward movement of the piston stem 260
will pull lever 342 downwardly to bring its member 340 against end
336 of stem 334 in the fluid control device 310, returning the
stem, and the pistons P1, P2, P3, P4 carried thereby, to their home
positions as illustrated in the drawing.
The high inlet pressure introduced into inlet 316 of the fluid
control device 310 is now transmitted through outlet 326, tube 328,
and nipple 274 to chamber 270; whereas chamber 266 on the opposie
side of piston 262 is now vented to the atmosphere via tube 334,
and openings 322 and 330 of the fluid control device 310.
Accordingly, the piston will now be driven through a return stroke
back to the illustrated home positions of the piston and of the
cleaning body 240. The cleaning body also effects the cleaning of
the filter during this return stroke since the interior of hollow
rod 244 continues to be vented to the atmosphere via opening 254,
until the latter opening, together with annular recess 256, passes
back through the dirt purging opening 238.
As indicated earlier, as soon as stem 260 begins to move away from
its home position, its larger diameter section moves to underlie
pin 360, causing the latter pin to move into its opening and to
block the communication between bore 304 and the bore in stem 292.
This disables the diaphragm 280 from exerting any further control
until piston 262 has driven the cleaning device 240 first through a
complete forward stroke and then through a complete return stroke
back to the illustrated home position. When the above members have
returned to their home positions, the larger diameter stem section
364 no longer underlies pin 360 so that the pin can move out of its
blocking position, and therefore the diaphragm 280 is enabled to
again sense the pressure difference with respect to the inlet and
outlet of the filter, and if the pressure difference still exceeds
the predetermined magnitude, another pressure pulse is transmitted
via bore 304 to the inlet 312 of the valve control device 310 to
initiate another complete cycle of operation of the cleaning
device.
Valve control device 310 preferably includes a small vent opening
366 to facilitate the return of stem 334 and its pistons. In
addition, the device may include a coarse filter screen or sleeve
368 to remove large particles from the water introduced through the
inlet 102a.
FIGS. 4 and 4a illustrate another off-line type filter constructed
in occordance with the invention. The top section of the filter of
FIG. 4 is of the same construction as in FIG. 3, and therefore is
not shown or described herein, the modification involved in the
embodiment of FIG. 4 residing in the illustrated bottom section of
the filter. To facilitate understanding the construction of the
filter of FIG. 4, corresponding reference numerals, but starting
with "400", have been generally used to identify similar parts as
in that in FIG. 3.
Thus, the filter illustrated in FIG. 4 comprises an inner metal
tube 402 having an inlet 402a and an outlet 402b, an outer plastic
housing having an upper horizontal section 402a and a lower
vertical section 404b, and a cylindrical filter body 406 disposed
within the lower housing section 404b with the inner surface of the
filter facing the housing inlet 402a. The lower end of housing
section 404b is formed with a dirt-purging opening 438. As
described above with respect to FIG 3, the water flowing through
the inlet 402a is deflected by a deflector (only a fragment of
which is shown at 408) to flow through openings 410 into the centre
of the filter body 406, then through the filter body, and finally
to exit from the filter through openings 412 and outlet 402b.
A cleaning body, generally designated 440, is disposed within the
cylindrical filter body 406 to clean its inner surface. Whereas the
cleaning body in the filter illustrated in FIG. 3 has an annular
inlet opening which is moved in a rectilinear path to sweep across
the complete inner surface of the filter body, the cleaning body in
the filter illustrated in FIG. 4 is provided with an inlet opening
of substantially smaller cross-sectional area which is movable in a
spiral path in order to sweep across the complete inner surface of
the filter body 406. Such an arrangement concentrates the suction
forces applied to the filter body and thereby assures a better
cleaning action.
More particularly, the cleaning body 440 illustrated in FIG. 4
includes a first section 442 and a second section 444. Section 442
includes a chamber 446 having an inlet opening 448 facing the
filter body 406. Section 444 is in the form of a hollow rod
communicating at one end with compartment 446 and carrying at its
opposite end a plug 450 having an O-ring 452. plug 450 is attached
to the lower end of rod 444 by means of a plurality of radial vanes
455 which produce a radially-recessed connection between plug 450
and the outlet end 454 of rod 444.
As described with respect to FIG. 3 above, the arrangement is such
that in the illustrated home position of the cleaning body 440, the
plug 450 is disposed within the dirt-purging opening 438 of the
housing, with the outlet 454 of hollow rod 444 disposed within the
housing; but upon movement of the cleaning body to initate the
self-flushing of the filter body 406, the recess produced by the
vanes 455 first moves into the purging opening 438 to discharge
therethrough the coarse dirt particles (i.e., those not passing
through the filter body 406), and then the cleaning body outlet
opening 454 moves into and out through the purging opening 438 to
discharge therethrough the dirt particles flushed from the filter
body through inlet 448, internal chamber 446 and hollow rod 444 of
the cleaning body.
As also described with respect to FIG. 3 above, the self-flushing
operation is automatically initiated by a sensor which senses a
predetermined pressure drop between the inlet 402a and outlet 402b
to actuate a piston and cylinder drive for driving the cleaning
body 440 to cause its inlet 448 to sweep along the inner surface of
the filter body 406. For the sake of simplifying the present
description, the sensor and drive illustrated in FIG. 3, are not
illustrated in FIG. 4 except for the end of the stem (shown at 460)
coupling the cleaning body to the piston. In FIG. 3, the cleaning
body is driven in a rectilinear path by the piston, and therefore
the piston stem is fixed to the cleaning body. In FIG. 4 however,
the cleaning body is driven both rotatably and rectilinearly, and
therefore the cleaning body is rotatably coupled to stem 460. For
this purpose stem 460 is received in an opening in a horizontal arm
461 fixed to the cleaning body 440, the tip of the stem being
formed with an enlarged head 463 spaced from arm 461 by a bearing
ring 465.
Stem 460 attached to the driving piston (262 in FIG. 3) thus moves
the cleaning body 440 in the longitudinal direction with respect to
the filter body 406. The cleaning body 440 is driven in the rotary
direction within the filter by a reaction tube 500 disposed on the
outlet side of the housing purging opening 438 and having a
coupling sleeve 502 connected to plug 450 by means of additional
vanes 504. The housing purging opening 438 is bordered by an
annular flange 506 closed by a collar 508 having an opening through
which passes the coupling sleeve 502 of reaction tube 500. The
latter tube is formed with a pair of outlets 510 which are
eccentric to the longitudinal axis 512 of rotation of the cleaning
440, so that the discharge of water through outlets 510 of tube 500
produces a reaction force rotating the tube, and thereby the
cleaning body 440 to which it is fixed by vanes 504 and 455.
The filter illustrated in FIG. 4 operates as follows: As described
with respect to FIG. 3, when the filter body 406 is relatively
clean, the piston stem 460 will be in the illustrated position so
that plug 450 carried at the end of hollow rod 444 of the cleaning
body 440 will close the housing dirt purging opening 438; therefore
no self-flushing action will occur. However, as soon as the filter
body 406 becomes sufficiently clogged with dirt particles so that a
large pressure drop is produced between the inlet 402a and the
outlet 402b, this is sensed (by sensor diaphragm 280 in FIG. 3)
which automatically actuates the piston-cylinder drive to drive
piston stem 460 downwardly, and thereby to cause the inlet opening
448 of the cleaning body 440 to move longitudinally along the inner
surface of the filter body 406.
Upon the initial movement of hollow rod 444 of the cleaning body,
plug 450 moves outwardly of the dirt purging opening 430, so that
the dirt particles that have accumulated in the bottom of housing
section 404b are immediately washed out via the spaces between the
vanes 455, 504, sleeve 502, and the eccentric outlets 510 of
reaction tube 500. This produces a reaction force rotating tube 500
and thereby the cleaning bod 440 connected to it. The inlet opening
448 of the cleaning body is thus moved along a spiral path, this
path being the resultant of the rectilinear movement of piston stem
460 and the rotary movement of reaction tube 500.
As the piston stem 460 moves further downwardly, the outlet opening
454 of the hollow rod 444 passes through the dirt purging opening
438, and as soon as this occurs, it vents the interior of rod 444
to the atmosphere via sleeve 502 and reaction tube 500. Thus, as
the inlet opening 448 of the cleaning body sweeps along the inner
surface of the filter body 406 by the above-described spiral path,
it picks up the dirt particles from the inner surface of the filter
body and washes them out through the reaction tube 500 whose
eccentric outlets 510 continue to rotate the cleaning body 440 by
the reaction force so produced.
As indicated earlier, by moving the inlet opening 448 of the
cleaning body 440 through a spiral path, the complete internal
surface of the filter body 406 may be swept by an inlet opening
having a relatively small cross-sectional area, thereby
concentrating the suction force so produced and enhancing the
cleaning action.
FIGS. 5 and 5a illustrate another embodiment wherein the cleaning
body is rotated within the filter body by means of a reaction tube.
In FIG. 5, however, no rectilinear movement of the cleaning body is
produced (except slightly to initiate the self-flushing action),
and therefore the cleaning body is provided with an inlet opening
extending the complete length of the filter body.
More particularly, the filter of FIGS. 5 and 5a is also an off-line
construction including an inner metal tube 602, having an inlet
602a and an outlet 602b; and outer plastic housing 604 having a
horizontal section 604a and a vertical section 604b; a cylindrical
filter body 606 disposed within housing section 604b; a deflector
608 disposed within the inner rigid tube 602; and a cleaning body
640 for cleaning the interior of the filter body 606. As in FIGS. 3
and 4, the water passing through the inlet 602a is deflected by
deflector 608 through openings 610 to the interior of filter body
606, then passes through the filter body, and finally exits through
openings 612 and outlet 602b.
In the construction of FIGS. 5 and 5a, however, the cleaning body
640 includes an internal chamber section 646 formed with an inlet
opening 648 extending the complete length of the filter body 606.
The cleaning body 640 is normally in the illustrated home position
wherein the upper end of its elongated inlet opening 648 is
disposed slightly above the filter body 606, but lowers to align
inlet opening 648 with the filter body 606 when a self-flushing
action is initiated. At that time, the hollow rod section 644 of
the cleaning body, which section communicates with inlet opening
648 via the internal chamber 646, is lowered to move plug 650 out
of the dirt purging opening 638. The interior of the filter is
first flushed of the coarse dirt particles which did not pass
through the filter body 606, and then the filter body is flushed,
the flushing water in both cases exiting through the eccentric
outlets 710 of reaction tube 700 connected to the cleaning body, as
described above with respect to FIG. 4. This flushing of the filer
through the eccentric outlets 710 causes the reaction tube 700 to
rotate the cleaning body 640, thereby causing the elongated inlet
opening 648 of the cleaning body to sweep along the inner surface
of the filter body 606 during flushing action.
As indicated above, the cleaning body 640 is only rotated (not
reciprocated) about the longitudinal axis of the filter body 606
during this flushing action. However, to initiate the flushing
action, the cleaning body must be lowered to move plug 650 first,
and then outlet 654, out through the housing purging opening 638.
The initiation of the selfflushing action is done automatically by
a diaphram sensor 680 which operates to sense the pressure
difference between the inlet 602a and outlet 602b and to control a
pilot valve in response thereto, all as described with respect to
FIG. 3 above.
In FIGS. 5 and 5a, however, the pilot valve 710 is actuated by
sensor 680 to move piston 662, to which stem 660 is connected, but
through a short stroke within a cylinder 664, sufficient only to
move plug 650 and the cleaning body outlet 654 through the dirt
purging opening 638. The lower end of piston stem 660 passes
through an opening in arm 661 carried at the upper end of the
cleaning body 640 and terminates in a large head 663 under arm 661.
The opposite end of cleaning body 640 is provided with an enlarged
surface 665 such that the pressure within housing section 604b
normally tends to move the cleaning body 640 downwardly. This
downward force is countered by the pressure within chamber 670
between piston 662 and cylinder 664, the latter chamber being
pressurized from the inlet of the filter via an opening 671 through
the wall of housing 604a. When pilot valve 710 is actuated, by
diaphram sensor 680 sensing a predetermined pressure difference
between the inlet 602a and the outlet 602b, chamber 670 is vented
to the atmosphere via an opening 673 formed in cylinder 664 and
leading to the pilot valve 710, and another opening 675 formed in
the wall of the pilot valve. When chamber 670 is thus vented to the
atmosphere, this counterforce is removed, and therefore the
internal pressure within the housing section 604b is effective to
move the cleaning body 640 downwardly to initiate a self-flushing
action as described above, and also to align the elongated inlet
opening 648 of the cleanding body with the inner surface of the
filter body 606. As also described above, the self-flushing action
so initiated causes the reaction tube 700, through which the
flushed water exits, to rotate the cleaning body 640, and thereby
to rotate its elongated inlet opening 648 along the complete inner
surface of the filter body 606.
FIGS. 6, 6a and 6b illustrate a simplified, inexpensive embodiment
wherein the self-flushing action is initiated, not automatically as
described above, but rather manually. In addition, during this
self-flushing action, the inlet opening of the cleaning body is
caused to sweep the inner surface of the filter body along a spiral
path as in the FIG. 4 embodiment.
More particularly, the filter illustrated in FIGS. 6, 6a and 6b
includes a housing having an inlet 802a at one end, an outlet 802b
at the opposite end, and an intermediate depending section 804 in
which the cylindrical filter body 806 is disposed with its inner
surface facing the inlet 802a. In this case, the filter 806 may be
a simple cylindrical screen. The bottom of housing section 804 is
formed with a dirt-purging oening 838, which is normally closed by
a plug 850 carried at the lower end of a cleaning body, generally
designated 840, as in FIG. 4 but excluding the reaction tube (500)
for rotating the cleaning body.
In the simplified construction illustrated in FIGS. 6, 6a, 6b, the
cleaning body 840 is moved by manual means, rather than by
automatic means, to cause its inlet opening 848 to sweep the inner
surface of the filter body 806 along a spiral path during the
flushing action.
The manual drive means in FIG. 6 includes a cap 851
rotatably-mounted over the end of a neck 853 carried by the filter
housing 804. Cap 851 is formed with a central stem 855 having a
plurality of parallel ribs 857 extending longitudinally of its
length. A sleeve 861 is fixed to the upper end of cleaning body 840
and is formed on its inner surface with a plurality of parallel
recesses 863 extending longitudinally of its length, and on its
outer surface with spiral threads 865 engaging internal spiral
threads formed on the inner surface of housing neck 853.
It will be seen that manually rotating cap 851 rotates sleeve 861
by virtue of the splined (ribs-and recesses) coupling between the
two. Rotation of sleeve 861 causes it to move downwardly by virtue
of its spiral threads 865 engaging the internal threads formed in
housing neck 853, this downward movement of the sleeve being
permitted by the splined coupling between the sleeve and stem 855
of cap 851.
Accordingly, rotation of cap 851 imparts a longitudinal and rotary
movement to sleeve 861 and thereby to the cleaning body 840,
causing the inlet opening 848 of the cleaning body to sweep the
inner surface of the filter body 806 along a spiral path.
To facilitate the rotation of cap 851, it may be provided with a
pivotable handle 869 which is normally disposed within a recess
formed in the cap, but which may be pivotted outwardly to a
position at right angles to the longitudinal axis of cap 851 to
facilitate rotating the cap and thereby sleeve 861.
Many other variations, modifications and applications of the
invention will be apparent.
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