U.S. patent number 3,836,001 [Application Number 05/273,257] was granted by the patent office on 1974-09-17 for pump with self-cleaning lint filter.
This patent grant is currently assigned to Westinghouse Electric Corporation. Invention is credited to Robert L. Heldreth.
United States Patent |
3,836,001 |
Heldreth |
September 17, 1974 |
PUMP WITH SELF-CLEANING LINT FILTER
Abstract
The invention provides a bi-directional single-impeller
centrifugal pump having a filter screen enclosed within the pump
housing and interposed, in the pump chamber, between the single
pump inlet and one of two outlets defined in the housing for
filtering the fluid pumped through the one outlet in response to
the impeller rotating in one direction. When the impeller is
reversed to pump the fluid through the other outlet, the particles
of lint etc., retained within the pump chamber by the filter screen
are then free to exit the pump as flushed therefrom by the fluid
being pumped through the other outlet.
Inventors: |
Heldreth; Robert L. (Mansfield,
OH) |
Assignee: |
Westinghouse Electric
Corporation (Pittsburgh, PA)
|
Family
ID: |
26956052 |
Appl.
No.: |
05/273,257 |
Filed: |
July 19, 1972 |
Current U.S.
Class: |
210/167.01;
415/121.2; 415/911; 210/409; 415/169.1 |
Current CPC
Class: |
D06F
39/085 (20130101); F04D 29/426 (20130101); B01D
35/26 (20130101); F04D 29/708 (20130101); D06F
2103/42 (20200201); Y10S 415/911 (20130101) |
Current International
Class: |
F04D
29/00 (20060101); A47L 15/42 (20060101); F04D
29/42 (20060101); D06F 39/08 (20060101); B01D
35/00 (20060101); B01D 35/26 (20060101); F04D
29/70 (20060101); B01d 035/22 (); B01d
035/02 () |
Field of
Search: |
;415/152A
;210/167,409,416,433 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spear, Jr.; Frank A.
Attorney, Agent or Firm: Winans; F. A.
Claims
What is claimed is:
1. A reversible centrifugal pump comprising a housing providing a
pump chamber bounded by the intrnal wall structure of the housing
and including a top wall defining inlet means for receiving fluid
to be pumped, a peripheral side wall defining first and second
outlet means for directing the discharge of the pumped fluid and a
bottom wall; a rotatable impeller enclosed within said chamber and
coupled to drive means for rotation in either direction with said
fluid being received for discharge at said first outlet means when
said impeller is rotated in one direction and at said second outlet
means when said impeller is rotated in the opposite direction; and
means for filtering the fluid received at said first outlet means
comprising a strip of foraminous material stationarily mounted
within said pump chamber and defining a peripheral edge contiguous
with said internal wall structure, and disposed between said inlet
means and said first outlet means and between said first outlet
means and said second outlet means so that said inlet means and
said second outlet means are in flow communication through said
chamber free of said filtering means and said inlet means and said
first outlet means are in flow communication only through said
filtering means whereby,
rotation of said impeller in said one direction to primarily
discharge fluid through said first outlet means, causes said fluid
to pass through said filtering means leaving particles removed by
said means within the pump chamber and subsequent rotation of said
impeller in the opposite direction to primarily discharge fluid
through said second outlet means causes said particles previously
retained within the pump chamber by said filtering means to be
carried with said fluid for discharge therefrom.
2. Pump structure according to claim 1 wherein said foraminous
strip has an arcuate configuration as viewed in a plane
perpendicular to the axis of said impeller, for effectively
partitioning said pump chamber into two annular chambers, with said
first outlet means opening into one of said annular chambers and
said second outlet means opening into the remaining annular
chamber.
3. Pump structure according to claim 2 wherein said wall structure
defines indexing means cooperating with said peripheral edge of
said foraminous strip to properly position said strip within said
housing.
4. Pump structure according to claim 3 wherein said indexing means
includes notches in said wall structure for receiving said
peripheral edge of said foraminous strip.
5. Pump structure according to claim 4 wherein said foraminous
strip extends on the order of 2/3 of the distance around said pump
chamber.
6. Pump structure according to claim 1 wherein the rate of fluid
discharged through said first outlet means is substantially less
than through said second outlet means.
7. Pump structure according to claim 6 wherein said foraminous
strip extends generally concentric with said side wall to partition
said chamber into two annular chambers with said first outlet means
opening into one chamber and said second outlet means opening into
the other chamber, said filtered particles being retained in said
second chamber when said impeller is rotated in said one direction
and flushed from said second chamber by fluid entering said second
chamber from both said inlet means and said first chamber when said
impeller is rotated in said opposite direction.
Description
RELATED APPLICATION
The pump of the present invention is related to the pump disclosed
in the copending application, Ser. No. 166,096 , now U.S. Pat. No.
3,751,179, of W. A. Wasemann having a common assignee.
BACKGROUND OF THE INVENTION
1. Field of the Invention:
This invention relates to a centrifugal pump having a pumping
chamber defined by a casing providing one inlet and two outlets
with the pumped fluid being directed through either one or the
other of the outlets depending upon the direction of rotation of
the pump impeller. More particularly, the present invention is
directed to a pump of the above nature including a filter
interposed within the pumping chamber between the inlet and one of
the outlets for filtering water discharged through that one outlet,
with the filter being cleaned by a flushing action when the
impeller is reversed to pump the water through the other
outlet.
2. Description of the Prior Art:
In that the pump of the present invention is primarily utilized in
the environment of laundry apparatus, such as an automatic washing
machine, the prior art associated with this environment will be
discussed.
It is well known to continuously circulate the wash water during
the agitation or wash portion of the timed cycle of an automatic
washing machine to provide an opportunity to pass the wash fluid
through a filtering mechanism to trap the suspended lint particles
and the like which, if not filtered, tend to be caught in the
clothes being laundered as the wash water flows through them. One
such apparatus for filtering the circulating water is shown in U.S.
Pat. No. 2,555,725 which shows a pump attached to the
water-containing tub of the washing machine. The pump includes two
outlets with valve means and associated valve control means to
determine the flow path the pumped fluid has between a
recirculating line (the line through which the water is
continuously circulated) or a drain line. Interposed between the
pump and the valve in the circulating line is a self-cleaning
filtering mechanism which is placed in a filtering position in this
line by automatic control means. Through the use of this pump and
associated filter structure, as the wash fluid is being pumped
through the recirculating line, the control means maintains the
filter in the path of the fluid; however, when the timer control
has advanced through the wash portion of the cycle to a drain and
pump-out portion, the filtering means will automatically move to
another position whereupon it is subjected to a flushing action by
the draining fluid and thereby cleaned.
As the laundry appliance field is highly competitive the
above-described pump and filtering mechanism requiring valves and
automatic actuating mechanisms including solenoids, was
prohibitively expensive and therefore the most prevalent type of
pumping and filtering means comprises a reversible centrifugal pump
which pumps to either a recirculating line or a drain line
depending upon the direction of rotation of the impeller, with the
recirculating line discharging above the normal water level in the
clothes containing tub so that a manually accessible filter could
be interposed between the recirculating line and the water. This
structure eliminated the expensive valve and valve control means
and also permitted the structure defining the filtering mechanism
to serve as a receptacle for washing additives which were than
added to the wash water by the action of the recirculating water as
it passed through the filtering structure.
The above arrangement was generally accepted even though it had
obvious shortcomings, not the least of which was that the water
falling from the recirculating discharge tended to splash on the
filtering pan and carry with it lint particles previously trapped
by the filter. Further, the filter required attention in that it
had to be regularly manually cleaned. And, lastly, the impact of
the recirculating fluid on the filtering pan tended to aerate the
water often causing an oversudsing problem.
SUMMARY OF THE INVENTION
The invention discloses a bi-directional single impeller
centrifugal pump having a filter screen permanently disposed within
the pump housing in position to filter the water flowing through
the outlet connected with the recirculation line and flushed by the
water flowing to the outlet associated with the drain line so that
the lint particles trapped by the filter within the pump housing
are subsequently carried to drain whenever the pump is placed in
that mode of operation. Such pump and filter mechanism, in addition
to providing a self-cleaning filter, eliminates the necessity for
valves and valve control mechanisms to determine the direction of
the pumped fluid and further permits the option of directing the
recirculating line to discharge into a washing machine below the
normal water level within the machine thereby eliminating splashing
and sudsing.
DRAWING DESCRIPTION
FIG. 1 is a cross-sectional elevation view of the pump of the
present invention;
FIG. 2 is a plan view of the lower housing member including the
impeller and filtering screen; and,
FIG. 3 is an elevation view of the pump in a washing machine.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred structure of the centrifugal pump of the present
invention will be described with reference to both FIGS. 1 and 2.
As therein shown, the pump 10 has a housing 12 generally formed by
fastening together two separate components, namely a bottom member
14 and a top member 16. Each member is preferably molded from a
plastic such as polypropylene.
The bottom member 14 includes a generally planar bottom wall 18 and
an upstanding peripheral side wall 20 with the juncture between the
side wall and the bottom wall radiused so as to provide a generally
smooth contour. The side wall 20 terminates in a radially outwardly
projecting flange 22 having apertures 24 therein through which
connecting bolts 26 are received. The bottom wall 18 also centrally
defines an aperture 28 having a stepped wall configuration so as to
properly receive a seal 30 through which the rotating shaft 32 of a
reversible motor 34 projects into the pump housing 12. Similarly,
flange 22 has a stepped configuration such as at 36 for receiving
an annular O-ring 38 generally around the inner periphery of flange
22.
The top member 16 includes a generally planar top wall 40 in
opposed facing relation with bottom wall 18, with the outermost
periphery of top wall 40 radiused as at 42 to provide a generally
smooth contoured transition between the horizontal top wall and the
vertical side wall 20 of the bottom member 14. The radially
outermost portion of the top member 16 defines a flange 44 in
opposed facing relation to flange 22 of the bottom member and has
apertures 46 for alignment with apertures 28 of the bottom member
through which the mounting bolts 26 are received. It is seen that
in the assembled position shown in FIG. 1, the face-to-face
engagement of the cooperating flange members compresses the O-ring
38 to provide a generaly water-tight seal around the periphery of
the housing 12.
The central portion of top wall 40 defines a generally cylindrical
chamber defined by an upstanding generally vertical wall 48 covered
by a contoured dome member 50 and provides a configuration for the
housing to internally accommodate structure attaching the impeller
to the drive shaft 32 of the motor 34 as will be subsequently
described.
The vertical wall 48 defines an opening 52 therein which is bounded
by an outwardly projecting nipple member 54 providing an inlet to
the pumping chamber 56 which can generally be defined as the
internal space formed by the opposing top wall 14 and bottom wall
18 and peripheral side wall 20.
An impeller 58 is disposed within the housing 12 in driving
engagement with shaft 32 of a reversible motor 34. The impeller 58
includes a central hub portion 60 having a sleeve member 62 which
telescopically receives the shaft 32 therein. The upper end of the
sleeve contains an aperture in alignment with a threaded aperture
in the shaft for receiving a bolt member 66. Sealing means such as
a top disk 69 and an O-ring 70 are interposed between the headed
bolt 66 and the sleeve to provide a sealing engagement when the
bolt is tightened to secure the impeller on shaft 32. The lower
portion of the hub 60 has a generally truncated conical form to
conform to the contour of the lower bottom wall 18 and seal 30 and
itself encloses a mating sealing means 72 in facing engagement with
the seal 30 of the bottom member 14.
The impeller 58 extends radially outwardly from the hub member
forming a generally planar bottom wall 74, the bottom face of which
is in close facing relationship with the bottom wall 18 of the
bottom member 14. The upper face of the impeller's bottom wall 74
supports a plurality of impeller blades 76 which have an arcuate
configuration (see FIG. 2) to provide a pumping capability in
either direction of rotation of the impeller; however, with the
pumping capacity of the blade in one direction being substantially
more efficient than the pumping capacity of the impeller blade in
the opposite direction.
Referring now to FIG. 2, it is seen that the side wall 20 of the
bottom member 14 defines outlet apertures 78 and 80 which are
bounded by integrally molded outwardly extending nipple portions 82
and 84 respectively. Aperture 78 is generally the larger of the two
outlets and its associated nipple portion 82 extends generally
tangentially from the side wall 20. Additionally, a short
projection or dam means 86 extend inwardly from the side wall 20
generally adjacent the aperture 78 on the side opposite the
tangential wall of the nipple portion 82 and in parallel facing
relation thereto.
Outlet aperture 80 and its associated nipple portion 84 extend
generally parallel to outlet aperture 78 and nipple 82 however in a
non-tangential position with respect to the side wall 20. Aperture
80 is also associated with a dam member 88 extending inwardly from
the side wall 20 on the side of the aperture closest to the dam 86
associated with outlet aperture 78 so that the two described dam
members are interposed within the pumping chamber between the two
outlets 78 and 80. It is to be noted that the dam members extend
from the bottom wall upwardly to a height so as to abutt the top
wall 40, and thus are notched as at 86a and 88a so as to permit
them to receive the top wall radius 42.
The pump as described up to this point is generally the same as the
pump in the previously identified copending related application;
however, the pump 10 of the present invention further includes
filter means 90 disposed within the pump chamber 56 to generally
partition the pump chamber into two annular chambers 92 and 94 as
separated by the filter means 90.
Referring to FIG. 1, the filter means 90 comprises a generally fine
mesh screen member 96, preferably molded of plastic, having the
general configuration of an arcuate strip of constant height
sufficient to extend from the bottom wall 18 to the top wall 40 and
properly positioned within the pumping chamber by being received
within an arcuate notch 98 formed in the bottom wall and a similar
opposing arcuate notch 100 formed in the top wall. Further, the
screen is positioned immediately in front of outlet aperture 80
with one end abutting dam member 88 which contains a notch 102 for
properly seating the filter in this position. The opposite end of
the screen member is outwardly formed as at 104 so as to extend
toward the side wall 20 and it likewise is properly seated in
position by being received within a notch 106 formed therein.
It is thus seen that with the top member 16 and bottom member 14
secured together the fluid, entering the inlet 52, must first pass
through some portion of the filter 90 before it can be discharged
through outlet aperture 80 and nipple 84, whereas, the fluid is
free to exit through the other outlet 78 without passing through
the filter 90.
In the pump 10, as described, when the impeller is rotated by the
motor in a counterclockwise direction, as viewed in FIG. 2, fluid
entering the inlet 52 is discharged through outlet aperture 78 at a
relatively large volume whereas, when the impeller is reversed so
as to be rotated in the clockwise direction the pumped fluid is
discharged from the pumping chamber 56 through outlet aperture 80
at a substantially reduced volume. Thus, as shown in FIG. 3, in the
normal application, the inlet opening is connected to the outer tub
108 of an automatic washing machine 110 through an appropriate hose
112 with the outlet aperture 78 and nipple 82 connected to a drain
hose 114 and outlet aperture 80 and nipple 84 connected to a
recirculating line 116. Therefore, with the washing machine
performing a washing or agitating function, the impeller 58 is
rotated in a clockwise direction so as to continuously recirculate
the water. In this mode of operation the lint containing wash water
enters the pumping chamber through the inlet opening 52 and in
flowing through the filter 90 so as to be discharged through the
recirculating aperture 80 the lint is retained on the screen member
96 or in the chamber 92 formed between the impeller and the screen
member 96. When the impeller is reversed at the end of the
agitation cycle to pump the wash water to drain, the lint collected
within chamber 92 is flushed by the incoming water so as to exit
chamber 92 through the drain outlet aperture 78 thereby cleaning
all the collected lint from the screen 96 and the chamber 92.
It is noted in FIG. 2 that the screen member 96 extends annularly
approximately two-thirds of the way around the pump chamber,
thereby providing more than sufficient cross-sectional area to
accommodate the relatively low volumetric flow rate discharging
from the recirculating outlet 80 without causing any substantial
velocity gradient across the filtering member that might accompany
a filtering area of reduced size. As a matter of fact, in a
transparent working model of the above-described pump, it was noted
that the lint collected in chamber 92 did not exhibit any definite
tendency to plaster itself against the screen 96 and in fact the
lint particles remained in a generally suspended fluidized
condition being continuously stirred by the turbulence of the fluid
in the chamber 92 such that when the impeller was reversed to pump
to drain, the lint collected in chamber 92 was immediately flushed
through the drain outlet clearing the pumping chamber for
subsequent operation. However, it has been found that a filter
screen of a cross-sectional area only equal to the cross-sectional
area of the recirculating outlet under the same circumstances
became immediately clogged with lint and prevented the flow through
the recirculating outlet. As the amount of lint developed under
actual washing conditions depends upon the type of fabrics being
laundered and, as an oversized screen or filtering member such as
disclosed does not effect the pumping characteristics of this pump,
it is better to provide a large filtering area, such as one having
the length described so that even when exposed to extreme lint
producing washing conditions it will permit flow. The choice of an
oversized screen area is not meant to imply that a filter of lesser
area will not operate satisfactorily under most conditions;
however, for the purpose of the present pump, in that the filter is
generally inaccessible once the pump has been mounted on the
machine, it was felt safer to oversize than undersize the area of
the filter.
Referring again to FIG. 3, it is seen that a pump of the above
construction having a filter within the body of the pump permits
the option of directing the recirculating filtered water to
re-enter the tub either above the water level to be used to flush
wash additives from a dispenser as is presently well known in the
art or below the water level (shown in phantom) to eliminate the
aeration of the water and its attendant sudsing.
* * * * *