U.S. patent number 3,810,480 [Application Number 05/259,872] was granted by the patent office on 1974-05-14 for fluid control system.
This patent grant is currently assigned to The Maytag Company. Invention is credited to Stewart W. Faust, Thomas R. Smith.
United States Patent |
3,810,480 |
Smith , et al. |
May 14, 1974 |
FLUID CONTROL SYSTEM
Abstract
A fluid control system for a dishwashing apparatus is disclosed
that includes a reversible two-cavity pump assembly with each of
the cavities having an inlet in open fluid communication with the
washing chamber and with the first cavity having an outlet in open
fluid communication with the fluid distribution system and the
second cavity having an outlet in open fluid communication with an
external drain conduit. An impeller is disposed within each of the
cavities and a divider is positioned between the cavities for
defining an annular orifice therebetween. Operation of the
impellers in a first direction effects pumping of fluid from said
chamber to the fluid recirculation system with the first pump while
the second pump maintains a substantially static low pressure head
at the outlet thereof to prevent drainage of fluid from said
chamber while preventing suction of fluid from the drain. The pumps
are operable in the opposite direction to intially continue
recirculation of fluid with the first pump while the second is
operable for draining fluid from the chamber and pumping it toward
an external drain.
Inventors: |
Smith; Thomas R. (Newton,
IA), Faust; Stewart W. (Newton, IA) |
Assignee: |
The Maytag Company (Newton,
IA)
|
Family
ID: |
27363114 |
Appl.
No.: |
05/259,872 |
Filed: |
June 5, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
27883 |
Apr 13, 1970 |
|
|
|
|
738277 |
Jun 19, 1968 |
3542594 |
|
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Current U.S.
Class: |
134/104.1;
134/188; 210/411; 134/186; 210/167.31 |
Current CPC
Class: |
A47L
15/4289 (20130101); A47L 15/4208 (20130101); A47L
15/4225 (20130101); A47L 15/0031 (20130101) |
Current International
Class: |
A47L
15/42 (20060101); D06F 33/02 (20060101); B08b
003/02 () |
Field of
Search: |
;134/104,186,188
;210/167,411 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bleutge; Robert L.
Attorney, Agent or Firm: Landwier; William G. Ward; Richard
L.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a division of Ser. No. 27,883 filed Apr. 13,
1970, now abandoned which in turn is a division of Ser. No. 738,277
filed June 19, 1968, now U.S. Pat. No. 3,542,594.
Claims
We claim:
1. In a dishwashing apparatus, the combination comprising: a
washing chamber for receiving articles to be washed; fluid
recirculation means for spraying washing fluid into said chamber to
remove particles from articles contained therein; large mesh first
stage filter means for removing large particles from said fluid;
fine mesh second stage filter means for removing relatively fine
particles from the large mesh filtered fluid; auxiliary spray means
associated with said fine mesh filter means for removing filtered
particles from said fine mesh filter means; a first fluid egress
from said chamber for withdrawing fine mesh filtered fluid from
said chamber; a second fluid egress from said chamber for
withdrawing large mesh filtered fluid from said chamber; first pump
means having an inlet communicating with said first fluid egress
and an outlet communicating with said fluid recirculation means and
said auxiliary spray means and operable in first and second
directions for supplying fine mesh filtered fluid to said fluid
recirculation means and said auxiliary spray means; second pump
means communicating with said second fluid egress and an external
drain and operable in one of said directions for removing large
mesh filtered fluid from said chamber and pumping it toward said
external drain; reversible drive means drivingly connected to said
first and second pump means; and means controlling said drive means
for effecting common rotation of said first and second pump means
selectively in said first and second directions.
2. In a dishwashing apparatus as defined in claim 1 wherein said
first and second egresses are in the form of first and second fluid
conduits independently and separately connected to said lower
portion of the washing chamber.
3. In a dishwashing apparatus, the combination comprising: a
washing chamber for receiving articles to be washed and having a
sump in a lower portion thereof; fluid recirculation means for
spraying washing fluid into said chamber to remove particles from
the articles contained therein; large mesh filter means for
removing relatively large particles from the washing fluid; fine
mesh filter means for removing relatively fine particles from the
washing fluid; auxiliary spray means for effecting cleaning of said
fine mesh filter means; a first fluid conduit for receiving fine
mesh filtered fluid from said sump; a second fluid conduit for
receiving large mesh filtered fluid from said sump; first pump
means having an inlet communicating with said first fluid conduit
and an outlet communicating with said fluid recirculation means and
said auxiliary spray means and operable in first and second
directions for supplying fine mesh filtered fluid to said fluid
recirculation means and said auxiliary spray means; second pump
means having an inlet communicating with said second fluid conduit
and an outlet communicating with a drain conduit and operable in
said second direction for maintaining a sufficiently large positive
head at said second pump outlet for pumping large mesh fluid from
said sump and through said drain conduit toward an external drain;
housing means defining pump cavities for said first and second pump
means, said second pump means being operable in said first
direction for maintaining a positive head at the outlet thereof
below a predetermined height in said drain conduit for preventing
flow of fluid through said drain conduit and preventing suction of
fluid from said drain conduit; reversible drive means attached to
said housing means and including a shaft member drivingly
connecting said first and second pump means for common rotation
thereof; and means controlling said drive means for selectively
rotating said first and second pump means in said first and second
directions.
4. In a dishwashing apparatus as defined in claim 3 wherein said
filter means is disposed in said sump for filtering said washing
fluids and wherein said auxiliary spray means is disposed within
said filter means for backwashing filtered particles from said
filter means during rotation of said first pump means in said first
and second directions.
5. In a dishwashing apparatus, the combination comprising: a
washing chamber for receiving articles to be washed; fluid
recirculation means for spraying washing fluid into said chamber to
remove particles from the articles contained therein; a first fluid
egress from a lower portion of said chamber for conducting washing
fluid from said chamber; fine mesh filter means for removing
relatively fine particles from the washing fluid passing through
said first fluid egress; auxiliary spray means associated with said
fine mesh filter means for removing filtered particles from said
fine mesh filter means; a second egress from a lower portion of
said chamber for conducting washing fluid by-passing said fine mesh
filter means; large mesh filter means for removing large particles
from the fluid passing through said second fluid egress; first pump
means having an inlet communicating with said first fluid egress
and an outlet communicating with said fluid recirculation means and
said auxiliary spray means and operable in first and second
directions for supplying fine mesh filtered fluid to said fluid
recirculation means and said auxiliary spray means; second pump
means having an inlet communicating with said second fluid egress
and an outlet communicating with a drain conduit and operable in
one of said directions for removing large mesh filtered fluid from
said chamber and pumping it through said drain conduit toward an
external drain; reversible drive means drivingly connected to said
first and second pump means; and means controlling said drive means
for effecting common rotation of said first and second pump means
selectively in said first and second directions.
6. In a dishwashing apparatus, the combination comprising: a
washing chamber for receiving articles to be washed and having a
sump in a lower portion thereof; fluid recirculation means for
spraying washing fluid into said chamber to remove particles from
the articles contained therein; fine mesh filter means in said sump
for removing relatively fine particles from said washing fluid;
auxiliary spray means associated with said fine mesh filter means
for removing filtered particles therefrom; a first fluid conduit
connected to a first portion of said sump for receiving fine mesh
filtered fluid; a second fluid conduit connected to a second
portion of said sump spaced from said fine mesh filter means for
receiving washing fluid and particles therein by-passing said fine
mesh filter means; first pump means having an inlet communicating
with said first fluid conduit and an outlet communicating with said
fluid recirculation means and said auxiliary spray means and
operable in first and second directions for supplying fine mesh
filtered fluid to said fluid recirculation means and said auxiliary
spray means; second pump means having an inlet communicating with
said second fluid conduit and an outlet communicating with a drain
conduit including a portion raised above the outlet of said second
pump means and operable in said first direction for maintaining a
positive head at said second pump outlet of less than the height of
said raised portion for substantially preventing fluid flow through
said drain conduit and operable in said second direction for
maintaining a positive head at said second pump outlet greater than
the height of said raised portion for pumping washing fluid and
particles therein from said sump through said drain conduit toward
said external drain; reversible motor means operable for effecting
common rotation of said first and second pump means; and means
controlling said motor means for selectively rotating said first
and second pump means in said first and second directions.
7. In a dishwashing apparatus, the combination comprising: a
washing chamber for receiving articles to be washed and having a
sump in a lower portion thereof; fluid recirculation means for
spraying washing fluid into said chamber to remove particles from
the articles contained therein; large mesh first stage filter means
for removing relatively large particles from said fluid; fine mesh
second stage filter means in said sump for removing relatively fine
particles from the large mesh filtered fluid; auxiliary spray means
associated with said fine mesh filter means for removing the
filtered particles therefrom; a first fluid conduit connected to a
first portion of said sump for receiving fine mesh filtered washing
fluid; a second fluid conduit connected to a second portion of said
sump spaced from said fine mesh filter means for receiving large
mesh filtered fluid and relatively fine particles therein bypassing
said fine mesh filter means; first pump means having an inlet
communicating with said first fluid conduit and an outlet
communicating with said fluid recirculation means and said
auxiliary spray means and operable for supplying fine mesh filtered
washing fluid to said fluid recirculation means and said auxiliary
spray means; second pump means having an inlet communicating with
said second fluid conduit and an outlet communicating with a drain
conduit, said second pump means being operable in said first
direction for maintaining a positive head at said second pump
outlet below a predetermined height in said drain conduit for
substantially preventing fluid flow through and suction from said
drain conduit and operable in said second direction for maintaining
a positive head at said second pump outlet greater than said
predetermined height for pumping large mesh filtered fluid and fine
particles therein from said sump and through said drain conduit
toward said external drain; housing means defining first and second
pump cavities for said first and second pump means; means within
said housing means separating said first and second pump cavities
while permitting flow of a relatively small quantity of fine mesh
filtered fluid from said first pump cavity into said second pump
cavity in said first direction of rotation; reversible motor means
operable for effecting common rotation of said first and second
pump means; and means controlling said motor means for selectively
rotating said first and second pump means in said first and second
directions.
Description
BACKGROUND OF THE INVENTION
1. The Field of the Invention
This invention relates to a washing apparatus and more particularly
to a dishwasher fluid control system for selectively achieving
recirculation or draining of the fluid.
2. Description of the Prior Art
Prior art has shown dishwashers in which fluid is pumped from a
sump area to a distribution system within the chamber for spraying
washing fluid on the articles to be washed. It has also been shown
desirable to provide a filter system for removing particles from
the fluid prior to recirculation onto the articles within the
chamber. In addition, prior art has shown the desirability of
providing a second pump communicating with the sump and operable
during a drain portion of the cycle for removing fluid from the
sump and pumping it toward an external drain.
In the interest of economy, the combination of these two pumps into
a device driven by a single motor is desirable. Prior art devices,
however, include certain compromises and limitations or rely on
auxiliary devices to achieve the desired selective fluid control.
In some of these devices, in which the common drive means is
operable for driving both pumps, auxiliary valves are required to
prevent the draining of the tank during recirculation or to prevent
suction of fluid from the drain into the sump. In still other
devices, limitations on impeller design or pump cavity
configuration or the addition of vents to various portions of the
pump cavity are included to overcome undesirable features present
in the previous devices. Some of the devices simply accept
undesirable characteristics such as that of allowing some backflow
of fluid through the drain pump during the recirculation
operation.
Still other prior art shows the desirability of providing a
self-cleaning filter system associated with fluid distribution
control. Such a system is shown in U.S. Pat. No. 3,090,391 issued
to H. J. Kaldenberg et al. May 21, 1963 and assigned to the
assignee of the instant invention. Provision of such a filter in a
two-cavity combination pump design brings with it additional
problems of providing sufficient fluid flow to the self-cleaning
filter to maintain the filter clean during the washing cycle and
during the initial portion of the drain cycle.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an improved fluid
control system for achieving selective recirculation of fluid
within a washing chamber and drainage of fluid from the washing
chamber.
It is a further object of the present invention to provide an
improved fluid control system for a dishwashing apparatus including
a motor-driven dual pump assembly for achieving recirculation of
fluid during a wash operation and pump-out of fluid during a drain
operation.
It is a further object of the present invention to provide a fluid
control system for a dishwashing apparatus including a reversibly
driven dual pump assembly operable for effecting a recirculation of
fluid to the washing chamber during the wash operation and at least
the initial portion of the drain operation while selectively
effecting removal of fluid only during the drain operation with a
system free of electromechanical valves.
It is yet a further object of the present invention to provide a
fluid control system for a dishwasher having a pair of commonly
driven reversible pumps wherein each includes an inlet openly
communicating with the washing chamber and the first pump includes
an outlet communicating with the fluid distribution system and the
second pump includes an outlet in open communication with the drain
conduit and wherein the pumps are operable as a unit for achieving
recirculation of washing fluid during the washing operation while
preventing discharge of fluid to the drain conduit and preventing
suction of fluid from the drain.
The above objects are realized in a dishwashing apparatus having a
pump assembly including two cavities and being selectively driven
in either direction by a reversible motor to achieve a
recirculation of fluid with one of the pumps and a substantially
static fluid condition with the other of the pumps during rotation
in a first direction and to selectively achieve a recirculation of
fluid with one of the pumps and discharge of fluid from the washing
chamber with the other of the pumps with the motor rotating in the
second direction.
Operation of the device and further objects and advantages thereof
will become evident as the description proceeds and from an
examination of the accompanying four pages of drawings which
illustrate a preferred embodiment of the invention and in which
similar numerals refer to similar parts throughout the several
views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational section view of the lower portion of a
dishwashing apparatus embodying the instant invention;
FIG. 2 is a perspective view looking into the bottom of the
dishwashing apparatus laying on its side and showing further
constructional details of a preferred embodiment of the instant
invention;
FIG. 3 is a sectional view of the motor and pump assembly embodying
elements of the instant invention with the section being taken
substantially in the plane defined by the longitudinal axis of the
pump assembly and by lines 3--3 in FIG. 2;
FIG. 4 is a schematic drawing showing relative fluid flow patterns
of the instant fluid control system;
FIG. 5 is a cross sectional view of a first pump portion as taken
along lines 5--5 of FIG. 3;
FIG. 6 is a cross sectional view of a second pump portion as taken
along lines 6--6 of FIG. 3;
FIG. 7 is an enlarged fragmentary sectional view of the central
axis portion showing constructional details of the pump assembly of
FIG. 3;
FIG. 8 is an electrical schematic circuit showing components and
circuitry controlling the dishwashing apparatus shown in FIG.
1;
FIG. 9 is a schematic diagram related to FIG. 8 and showing
sequential operation of timer contacts included in the electrical
circuit of FIG. 8; and
FIG. 10 is a diagrammatic view showing the development of a portion
of the second pump cavity.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, there is shown the lower portion of a
dishwashing apparatus including a cabinet 10 comprising
substantially vertical sidewall 11 and a generally horizontally
disposed sloping bottom wall 13 cooperable with the sidewall 11 to
define a washing chamber 14. Means, such as the rack member 15, is
provided within the chamber 14 for holding articles to be
washed.
The fluid distribution system, shown generally in FIGS. 1 and 4,
includes a rotatable lower spray arm 16 and a spray nozzle 18
rotatable with the spray arm 16 for spraying washing fluid onto the
articles within the chamber 14. The fluid recirculated into the
washing chamber 14 by the spray arm 16 and the spray nozzle 18 is
collected in a sump area 19 defined in part by a housing 17
depending from the bottom wall 13. The fluid system further
includes a motor-driven dual pump assembly, shown more specifically
in FIGS. 3, 5, 6, and 7 and as will be more fully described
hereinafter.
Filter means 20, located in the sump area 19, is self-cleaning and
continuously operable for removing particles from the fluid in the
sump area 19 as fluid is drawn through the pump assembly 21 for
recirculation to the spray arm 16 and nozzle 18. The filter means
20 includes a cylindrical filter screen 23 having fine mesh
openings and is disposed within the sump area 19 and enclosed at
its upper end by a substantially imperforate filter cap 24. As best
shown in FIG. 4, the fluid flows from the sump 19 through the
filter screen 23 and through the filtered-fluid conduit 25 to the
pump 21 and is forced through a recirculation conduit 26 toward the
recirculation spray arm 16 and nozzle 18 and upper spray means 27.
An auxiliary spray arm 28, located within the filter means 20, is
operable for receiving a portion of the fluid from the
recirculation conduit 26 and for spraying fluid on the downstream
side of the filter screen 23 to remove particles collected on the
upstream side thereof. There is also provided a first stage filter
29 upstream from the fine mesh screen 23 for removing the large
particles from the washing fluid. Further constructional and
operational details of a filter of this type may be found in U.S.
Pat. No. 3,090,391 issued to H. J. Kaldenberg et al. May 21, 1963
and assigned to the assignee of the instant invention.
Means are provided for supplying fluid to the washing chamber 14
from an external source. The fluid is allowed to flow into the sump
area 19 and lower portion of the washing chamber 14. The normal
fluid level at rest is shown by broken line 32 in FIG. 4.
As best shown in FIG. 4, the sump area 19 communicates with the
inlets 30 and 31 of two effectively separate pumps 33 and 34 both
of which are housed within the combined dual pump assembly 21.
Though shown below the sump in FIG. 4 to more clearly illustrate
the fluid system by diagrammatic means, the pumping assembly 21 is
actually positioned adjacent the bottom wall 13 at substantially
the same elevation as sump 19. The inlet 30 of the first pump 33,
operable for recirculating fluid to the washing chamber 14, is
connected to the sump 19 at a position within the filter screen 23
so as to receive filtered fluid from the sump area 19 for
recirculation to the spray arm 16 and spray nozzle 18. This fluid
path includes a filtered-fluid conduit 25 connecting the sump area
19 to the inlet 30 of the recirculation pump 33, and a
recirculation conduit 26 connecting the outlet 36 of the
recirculation pump 33 to the lower spray conduit 38, the upper
spray conduit 39, and the auxiliary spray conduit 40.
The second pump 34, operable for draining fluid from the washing
chamber 14, is connected to the sump 19 at an upstream position
from the filter 23 so as to receive unfiltered fluid and particles
which have been collected outside the filter screen 23 and in the
sump 19 during the recirculation of fluid to the washing chamber
14. The drain pump inlet 31 is connected to the sump 19 by
unfiltered-fluid conduit 41. An external drain conduit 43 extends
from the outlet 44 of the drain pump 34 to an external drain. A
portion of the drain conduit 43 is elevated above the pump assembly
21 and the lower portion of the washing chamber 14.
An integral part of the fluid system is the dual pump assembly 21
shown in FIGS. 3, 5, 6, and 7. The pump assembly 21 is driven by a
motor 45 and is mounted adjacent the lower side of the bottom wall
13 of the washing chamber 14, along with the motor 45, by a bracket
46 secured along one edge to the bottom flange 48 of the cabinet
sidewall 11 and along the other edge to the underside of the
washing chamber bottom wall 13. This bracket 46 is shown in
perspective in FIG. 2 and in cross section in FIGS. 5 and 6. The
motor 45 is attached to the bracket 46 by a pair of resilient
longitudinally extending spacers 49 that are connected to the motor
45 and in turn connected to the mounting bracket 46 as shown in
FIGS. 5 and 6.
The motor 45 is a fractional horsepower reversible motor of the
type commonly used in household appliances and, referring to FIG.
3, includes an end bell 50 and a sidewall portion 51 that are
connected to the pump assembly 21 by a plurality of through bolts
53. The motor stator 54 is carried by the sidewall 51 while the
armature 55 and shaft 56 are rotatively supported by a first
bearing 58 in the end bell 50 and a second bearing 59 retained
within a portion of the pump housing 60. The pump housing 60
includes a substantially cylindrical outer portion 61 engageable
with the motor sidewall 51 at one end and a pump cover 63 at the
other end and further includes an inner portion 64 defining a pair
of volute-type pump cavities 65 and 66 and adapted to receive one
end of the armature shaft 56.
Referring to the central portion 64 of the pump housing 60, as best
shown in FIGS. 3 and 7, the one end of the armature shaft 56 is
rotatively supported by the second bearing 59 and extends into the
cavities 65 and 66 of the pump housing 60. The second bearing 59 is
clamped between a portion of the pump housing 60 and a mounting
plate 68 that is in turn secured to the pump housing 60. A
retaining ring 69 is axially secured to the shaft 56 and bears
against the motor side of the bearing 59 to locate the shaft 56
axially with respect to the pump housing 60. The shaft 56 extending
into the pump housing 60 is adapted, as by a double-D section, to
receive and rotate a pair of impellers 70 and 71. The drain pump
impeller 71 includes a longitudinally extending hub 73 engageable
with a washer 74 abutting the inner race 75 of the second bearing
59 and thereby properly locates the drain impeller 71 within the
second pump cavity 66. The recirculation impeller 70 is also
mounted on the shaft 56 and includes a hub portion 76 abutting one
end of the drain impeller hub 73 to properly locate the
recirculation impeller 70 within the first pump cavity 65. A screw
member 78 axially retains the two impellers on the shaft 56.
A sealing system is included in the pump assembly 21 to prevent
leakage of fluid from either of the pump cavities 65, 66 into the
bearings of the motor area. There is an annular seal 79 beneath the
head of the screw 78 that secures the impellers 70, 71 to the shaft
56 for preventing leakage around the screwhead and through the
central mounting opening of the first impeller 70. A second annular
seal 80 is provided at the juncture of the hubs 76, 73 of the first
and second impellers 70, 71 to prevent leakage at this point. These
two annular seals 79, 80 are effective for providing a seal between
surfaces that rotate as a unit. A seal assembly 81 for preventing
leakage at the junction of relatively rotatable members is provided
to the left of the second impeller 71. This seal assembly 81
includes a resilient portion 83 sealingly engageable with an
annular recess in the housing 60 and further includes a seal ring
84 fixed to this resilient portion 83 and biased by a coil spring
85 toward a wear ring 86 carried by the impeller 71. The wear ring
86 secured to the second impeller 71 is mounted within a recess of
the impeller 71 by a resilient cushion member 88.
The housing further defines a fluid vent 89 from the central
portion 64 of the pump housing 60 in the area to the left of the
seal assembly 81 and extending from the seal area outwardly through
the outer portion 61 of the pump housing 60 to allow escape of
fluids that might bypass the seal arrangement.
The recirculation pump 33, comprising the first cavity 65 and the
recirculation impeller 70 disposed therein, is operable for
recirculating fluid to the washing chamber 14 and is shown in
section in FIGS. 3 and 5. The pump 33 is defined at least in part
by the pump cover 63 that includes an inlet 30 disposed
substantially coaxially with the axis of rotation of the pump
assembly 21 and connected to the sump 19 through the filtered-fluid
conduit 25. The cavity 65 is in the form of a volute terminating in
a substantially tangentially extending outlet 36 connected in turn
to the recirculation conduit 26. The recirculation impeller 70
includes a flange portion 90 extending outwardly from the hub 76
and a plurality of arcuate-shaped vanes 91 mounted on one side of
the flange portion 90. The radially inward portion of the vanes 91
define a central eye 93 coaxially aligned with the recirculation
pump inlet 30.
The recirculation pump 33 is operable in a clockwise direction as
shown in FIG. 5, and which will be considered the forward direction
of the dual pump 21, to effect through centrifugal pumping a
pressure differential between the inlet 30 and outlet 36 of the
recirculation pump 33 of approximately 25 inches of mercury with a
fluid flow rate of 45 g.p.m. In the reverse, or counterclockwise,
direction of rotation, the recirculation pump 33 is operable for
pumping fluid from the inlet 30 to the outlet 36 with a pressure
differential of approximately 3 inches of mercury.
The drain pump 34, comprising the second pump cavity 66 and the
drain impeller 71, is shown in section in FIG. 6 and is disposed to
the left of the first pump cavity 65 as viewed in FIG. 3. A
fragmentary portion of the impeller 71 is shown in FIG. 6 and the
impeller blades or vanes removed have the same shape as those shown
in FIG. 6. The second volute cavity 66 is relatively smaller in
diameter than the first cavity 65 and the difference between the
smallest and largest radius of the volute is less than that for the
first cavity 65. A dam or fluid cutoff 92 projects into the cavity
66 to a position adjacent the impeller 71 to direct fluid from the
cavity 66 into outlet 44.
It is noted that the inlet 31 for the pump cavity 66 is displaced
to the left of the impeller 71 as viewed in FIG. 7, or below the
impeller 71 as viewed in FIG. 6. It is necessary, therefore, to
move the fluid axially within the pump cavity 66. To accomplish
this axial movement of the fluid from the inlet 31 to the outlet 44
while also maintaining a pumping system operable for achieving a
substantially static condition in the opposite, or clockwise
direction of rotation, the leftmost portion of the pump cavity 66,
as in FIGS. 3 and 7, includes a particular ramp arrangement as
indicated in FIG. 6 and more clearly shown in the ramp development
of FIG. 10.
The fluid from the sump 19 enters the second pump cavity 66
generally tangentially through inlet 31 at a radial position
substantially aligned with the vanes but axially displaced to the
left of the vanes as shown in FIGS. 3 and 7. As best shown in FIGS.
6 and 7, a ramp means extends from the leftmost position 140 of the
inlet 31, to the first plane 141 and then up a bevelled step 143 to
a plateau 144 extending around a large portion of the annular
groove 145 and terminating in a first incline portion 146 disposed
for axially moving the fluid to a shelf aligned with the leftmost
portion 148 of the outlet 44. A second incline portion 149 extends
back to the plane 141.
This ramp means is more specifically shown in the ramp development
of FIG. 10 in which the broken line 150 is the broken line 150
shown in FIG. 6. The ramp development, extending toward the left
from the broken line 150 shows the ramp construction of the second
pump cavity 66 as it extends in a counterclockwise direction in
FIG. 6. FIG. 10 shows the plane 141, the bevelled step 143, the
plateau 144, and the first and second incline portions 146 and 149.
This ramp means is operable for moving fluid from the axial
position 140 to the axial position 148 upon rotation of the
impeller 71 in the counterclockwise direction.
It may then be seen that, with the pump rotating in a
counterclockwise direction, the fluid is pumped from the inlet 31
through the second pump cavity 66 to the tangentially extending
outlet 44 disposed angularly from the inlet 31 so that the fluid
tends to move circumferentially and axially in a spiral-like path
from the inlet 31 toward the outlet 44.
The combination of the second incline portion 149 and the bevelled
step portion 143, adjacent the broken line 150 effectively provide
a recess or pocket at the point of entry of the inlet into the pump
cavity 66 is cooperable with cutoff 92 to provide a unique valve
means for facilitating achievement of the efficient pumping
operation in the counterclockwise direction while also facilitating
achievement of a static condition at the outlet 44 and a condition
of relatively small fluid flow toward the inlet 31 with the pump 34
operating in the clockwise direction as in the recirculation
operation. This second incline portion 149, and bevelled step
portion 143 disposed adjacent the first plane 141 at the inlet in
cooperation with cutoff 92, function effectively as a one-way valve
within the drain pump 34.
The drain pump impeller 71 is operable in the same direction as the
impeller 70 of the recirculation pump 33 and, during operation of
the pump assembly 21 in a clockwise direction, the drain pump 34
maintains a substantially static condition in the drain conduit 43
of approximately 6 to 14 inches of water while permitting a
relatively small amount of fluid flow from the second cavity 66
toward the unfiltered-fluid conduit 41 through inlet 31. The fluid
flowing toward the unfiltered-fluid conduit 41 is that fluid which
bypasses a cavity divider member 94 and effectively flows downhill
from pump inlet 31 toward the sump 19 as will be more full
explained hereinafter.
In the reverse direction of rotation, or in the counterclockwise
direction, as during the drain operation, the drain pump 34 is
operable for effecting a pressure head in the drain conduit 43 of
approximately 3.5 feet of water with a flow of 4.5 g.p.m. through a
drain hose of approximately 7/16 inch diameter.
Referring again to FIG. 4, the relative fluid flow effected by the
pumping system is shown schematically. In this diagram, the pumping
effected by the pumping assembly 21 operating in the clockwise
direction is shown in full line arrows. The pumping effected during
counterclockwise rotation of the pumping assembly is shown in
broken line arrows. More specifically, FIG. 4 indicates that
clockwise rotation of pump 33 will effect movement of fluids from
sump 19 through filtered-fluid conduit 25 toward inlet 30 and then
pass through outlet 36 and be directed toward the lower spray
conduit 38, upper spray conduit 39, and auxiliary spray conduit 40.
It has been indicated above that clockwise rotation of pump 34 will
effect a substantially static pressure in the drain conduit 43 to
prevent suction of fluids therefrom and thus no flow arrows are
shown for clockwise rotation of pump 34. It has also been indicated
above, though not shown schematically in FIG. 4, that a small
amount of fluid will bypass the divider member 94 and flow in a
generally downhill direction from the inlet 31 of the second pump
toward sump 19.
Counterclockwise rotation of the pumping assembly 21 will effect
continued flow through pump 33 in the same relative pattern as
effected in the clockwise rotation of pump 33. The pumping
efficiency, however, will be at a lower level as indicated
hereinabove. The counterclockwise rotation of the pump 34 effects a
substantially increased pressure at the outlet 44 to produce a
draining of fluid from sump 19 through unfiltered fluid conduit 41,
pump 34 and drain conduit 43 to the external drain as shown by
broken line arrows in FIG. 2.
Disposed within the pump housing 60 between the first and second
cavities 65, 66 is the annular divider member 94 connected to the
housing 60 by a plurality of screw members 95. A flange portion 96
extends inwardly between the first and second impellers 70, 71 and
terminates in a lip portion 98 adjacent the hub 76 of the first
impeller 70. As best shown in FIG. 7, the annular lip portion 98
terminates at a position spaced from the periphery of the impeller
hub 76 to define an annular orifice 99 between the first and second
pump cavities. This relatively small annular orifice 99 achieves a
degree of pressure control and limits fluid flow between the two
cavities 65, 66 while avoiding contact between the stationary
divider 94 and rotatable impeller hub 76. This lip portion 98 being
in close proximity to the hub 76 also prevents passage of particles
from the drain pump cavity 66 into the recirculating pump cavity 65
during operation of the pump 21.
It has been found that a small fluid flow through the annular
orifice 99 and the drain pump cavity 66 toward the drain pump inlet
31, as described hereinabove, is beneficial in securing a more
rapid response of the drain pump 34 in initiating fluid flow from
the sump 19 upon reversal in direction of rotation. It is believed
that the improved operation results from a condition wherein less
air is trapped in the drain pump circuit. The fluid flow through
the annular orifice 99 during operation of the pump assembly 21 in
the recirculation direction maintains the drain pump circuit
substantially full of fluid rather than air and therefore the time
required to purge the air from the drain pump 34 upon reversal in
direction of rotation is substantially eliminated.
It is noted that the recirculation pump 33 is operable for
maintaining a relatively high fluid pressure in a portion of the
first pump cavity 65 and in the absence of the divider member 94
the high pressure would be transmitted at least in part to the
drain pump cavity 66. Tests on the preferred embodiment have shown
that without the divider 94 between the first and second pump
cavities 65, 66 defining the orifice 99, the operation of the pump
21 in the clockwise direction will effect recirculation of fluid to
the recirculation conduit 26 but will at the same time, due to the
transmission of high pressure head to cavity 66, effect drainage of
fluid from the sump 19 toward the drain conduit 43. The divider 94,
providing an orifice width of approximately 0.010 inch in the
preferred embodiment, thus effectively serves as a pressure orifice
for controlling pressure differentials and fluid flow between the
cavities.
Tests have also shown that the relative size of conduits 41 and 43
are important in maintaining proper operation of pump 34 in the
clockwise direction. In an operable embodiment tested, the
unfiltered fluid conduit 41 is 3/4 inch I.D. and the drain conduit
43 is 7/16 inch I.D. Decreasing the size of conduit 41 results in
increased fluid velocity through the conduit which also tends to
result in less accumulation of air in the drain pump circuit.
An electrical schematic diagram and a timer sequencing program for
effecting energization of the motor 45 and other components to
control the fluid flow system are shown in FIGS. 8 and 9
respectively. Referring to FIG. 8, there is shown, connected
between power lines L.sub.1 and L.sub.2, a plurality of operating
and control components under control of a timer 97 including
sequentially operable timer contacts 100 through 119 controlled by
a plurality of cams (not shown) driven by a timer motor 121 that is
in turn controlled by the timer contacts 104, 105, and 106. The
circuit further includes a water valve having a coil 123 for
selectively permitting flow of water to the washing chamber 14
under the control of a pair of timer contacts 100, 101. A heater
124 disposed within a lower portion of the washing chamber 14 and
connected across power lines L.sub.1 and L.sub.2 is controlled by a
manually operable switch 125 and a pair of timer contacts 102, 103.
A second switch member 126, linked with the manually operable
heater switch 125, is in the timer motor circuit in series with a
pair of timer contacts 104, 105. Also connected across power lines
L.sub.1 and L.sub.2 is a detergent dispenser 128 and a rinse
conditioner dispenser 129 controlled by contact pairs 114, 115 and
116, 117. The detergent and rinse conditioner dispensers 128 and
129 are selectively operable at predetermined portions of the
dishwashing cycle to add chemicals to the washing or rinse fluid to
improve the effectiveness.
The main drive motor 45 is connected across power lines L.sub.1 and
L.sub.2 and is under the control of a relay 130 including a switch
131 controlled by a current sensitive coil 133. The drive motor 45
is energized in the forward, or recirculation, direction through a
first pair of contacts 107, 108 in series with a first start
winding 134 and in the reverse, or drain, direction through a
second pair of contacts 108, 109 in series with a second start
winding 135. The common contact 108 is connected in series with the
relay switch 131. The motor run winding 136 is connected in series
with the current relay coil 133 which is in turn connected to power
line L.sub.2 by a pair of parallel paths. The first path is through
a pair of timer contacts 112, 113 whereas the second path to power
line L.sub.2 is through a separate pair of timer contacts 110, 111
and through subinterval switch contacts 118, 119 associated with
the timer mechanism 97 and operable in a manner as will be fully
described hereinafter. It is thus seen that the drive motor 45 will
be energized and will rotate in a direction as determined by the
programmed operation of contact 108 to selectively energize one of
the alternate start windings 134 and 135. If, for example, the
timer contacts 107, 108 in series with the first start winding 134
are closed, the motor 45 will be rotated in the recirculation
direction. Upon operation of the current sensitive relay switch 131
to the open position, the start winding 134 will be de-energized
but the motor 45 will continue rotating in the recirculation
direction by virtue of energization of the run winding 136 through
the pair to timer contacts 112, 113. It will be seen that the
subinterval contacts 118, 119 are operable for effecting a reversal
in the direction of rotation at a given point in the cycle.
The subinterval contacts 118, 119 are operative between the open
and closed position during each increment or interval of time
within the program cycle. As shown in FIG. 9, the subinterval
contacts 118, 119 are closed for a major portion of each increment
but are open for a short period of time for breaking the circuit to
the run winding 136 when energized through time contacts 110, 111.
During this subinterval, the motor 45 stops and the alternate start
winding 135 is energized for effecting rotation of the motor 45 in
the opposite direction.
It is believed that a consideration of the electrical circuit shown
in FIG. 8 and of the timer sequencing program shown in FIG. 9 will
allow a complete understanding of the operation of the dishwashing
apparatus to one skilled in the art. This consideration of the
circuit and sequencing will show that a series of operations is
provided by the dishwashing apparatus as follows:
Increment Operation Duration (minutes) 1 "Off" 11/4 2 Pause 11/4 3
Fill 11/4 4 - 5 Rinse 21/2 6 - 7 Drain 21/2 8 "Off" 11/4 9 Pause
11/4 10 Fill 11/4 11 - 12 Wash 21/2 13 Drain 11/4 14 Fill 11/4 15 -
17 Rinse 33/4 18 Drain 11/4 19 Pause 11/4 20 Fill 11/4 21 - 32 Wash
15 33 Drain 11/4 34 Fill 11/4 35 - 37 Rinse 33/4 38 Drain 11/4 39
Fill 11/4 40 - 43 Rinse 5 44 - 45 Drain 11/4 46 - 59 Heat Drying
171/2 60 Cool Down 11/4 ______________________________________
This cycle of operations is divided into a first portion including
increments 2-7 which may be termed "Rinse and Hold" and a
"Dishwashing" portion extending from increment 9 through 45. For
heavy washing, the entire portion of increments 9-45 may be
utilized whereas a light washing operation may be selected by
setting the timer mechanism at increment 19, for example. The final
portion of the cycle of operations includes the "Dish Drying"
portion and extends from increment 46 through 59.
By way of summary, sequential operation and specific operational
characteristics of the fluid system as pertaining to operation of
the dishwashing apparatus will be reviewed. The operator may
initiate the dishwashing apparatus by manually advancing a timer
dial (not shown), for example, to advance the time mechanism 97
into increment 9 to begin the "Dishwashing" operation. After an
initial pause, the fill valve 123 is energized to effect filling of
the lower portion of the dishwasher chamber 14 to water level line
32 with approximately 3 gallons of washing fluid. In the 11th
increment, a pair of timer contacts 112, 113 are energized to
effect energization of the motor 45. Since the start winding 134
for the washing or recirculation direction of rotation is energized
through a pair of timer contacts 107, 108 in series with the start
relay switch 131, the motor 45 will be energized in the direction
for recirculating fluid to the spray arm 16 and spray nozzle 18.
Rotation will be maintained in this direction through the run
winding 136 in series with the current relay coil 133 and the timer
contacts 112, 113. With the motor 45 energized for the
recirculation operation, the pump impellers 70, 71 will rotate in a
clockwise direction as shown in FIGS. 5 and 6. Operation of the
motor 45 in this clockwise direction rotates both impellers 70, 71
at approximately 3,450 rpm for effecting fluid flow from the sump
area 19 to the recirculation conduit 26 with the recirculation pump
33 and for effecting a substantially static condition in the drain
conduit 43 by the drain pump 34.
As previously indicated, the inlet-to-outlet pressure differential
maintained by the recirculation pump 33 is approximately 25 inches
of mercury with the fluid flow rate of 45 g.p.m. A major portion of
this fluid is directed to the upper and lower spray conduits 38 and
39 whereas a smaller portion is directed to the auxiliary spray
conduit 40 for projecting fluid on the downstream side of the
filter screen 23 to remove particles therefrom.
Rotation of the drain pump 34 in the clockwise direction maintains
a substantially static condition in the drain conduit 43. More
specifically, the drain pump 34 maintains a substantially static
head of 6 to 14 inches of water in the drain conduit 43 to prevent
suction of fluid from the drain conduit 43 toward the washing
chamber 14 while at the same time being sufficiently small to
prevent pumping of fluid from the sump 19 to a drain through the
elevated drain conduit 43. The divider 94 effectively defines a
pressure orifice 99 and prevents transfer of the high pressure from
the recirculation pump 33 to the drain pump 34 and also thereby
limits fluid flow. A limited fluid flow from the recirculation pump
33 into the drain pump 34 is useful in preventing air from being
trapped in the drain pump circuit.
Through control of the electrical circuit by the timer contacts 107
through 113 and the subinterval contacts 118, 119 of the timer
mechanism 97 the motor direction of rotation may be reversed at a
preselected position within the cycle of operations as determined
by the timer sequencing program. The reversal in the motor
direction will effect rotation of the pump impellers 70, 71 in the
counterclockwise direction as viewed in FIGS. 5 and 6.
In the drain direction of rotation, the recirculation pump 33
remains operative for pumping fluid from the sump 19 toward the
recirculation conduit 26 as long as sufficient fluid remains in the
sump area 19. This pumping is effective for maintaining a pressure
head of approximately 3 inches of mercury pumping toward the
recirculation conduit 26.
The drain pump 34 is operable in the counterclockwise direction for
effecting pumping of fluid from the sump 19 of the washing chamber
14 toward the drain conduit 43. A preferred embodiment of this pump
structure maintains a pressure head of 3 to 4 feet of water with a
flow of 4.5 g.p.m. through a tube of approximately 7/16 inch
diameter.
During this drain direction of rotation in which the washing fluid
and particles removed from the articles being washed is pumped to
the drain conduit 43, the passage of particles from the drain pump
cavity 66 to the recirculation cavity 65 is prevented by the
divider member 94 which effectively serves as a proximity seal.
It is therefore seen from the foregoing description that the
dishwashing apparatus described hereinabove provides a novel fluid
control system including an improved pump structure 21 having a
pair of fluid pumps 33, 34 within a common pump housing 60. This
pump and fluid system is operative for achieving a desirable
recirculation of fluid to the washing chamber and to a
self-cleaning filter while maintaining open fluid communication
through the pump to the drain conduit but preventing both pump-out
and suction during recirculation. This system eliminates
electromechanical valves or other auxiliary fluid control devices.
The pump structure achieves economies in construction through the
use of a common housing and the elimination of the auxiliary fluid
control.
In the drawings and specification, there has been set forth a
preferred embodiment of the invention and although specific terms
are employed, these are used in a generic and descriptive sense
only and not for purposes of limitation. Changes in form and the
proportion of parts as well as the substitution of equivalents are
contemplated as circumstances may suggest or render expedient,
without departing from the spirit or scope of this invention as
further defined in the following claims.
* * * * *