Dishwasher pump having soil collection system

A pump system for a dishwasher including a pump housing defining a pump chamber having an inverted frustroconical shape including an upwardly angled annular outer wall. An impeller is disposed within the pump chamber. An annular soil collection chamber is disposed partially above the pump chamber such that the bottom wall of the soil collection chamber forms the top wall of the pump chamber. Wash liquid is supplied into the soil collection chamber from the pump chamber through an opening provided in the bottom wall of the soil collection chamber located at the upper, peripheral portion of the pump chamber. The upwardly angled annular wall of the pump chamber promotes soil movement into the soil collection chamber by directing soils toward the upper portion of the pump chamber. The soil collection chamber is formed by an annular soil collector housing and a cover. The cover includes a plurality of filter screen panels such that wash liquid supplied into the soil collection chamber is filtered and soils are collected. By locating the collection chamber above the pump chamber, the inner diameter of the soil collection chamber may be formed smaller than the outer diameter of the pump chamber such that the outer diameter of the soil collection chamber may be minimized.

BACKGROUND OF THE INVENTION 
1. Field of Invention 
The present invention relates to a dishwasher pump and more particularly to 
a efficient and compact configuration for a dishwasher pump having a 
filtration and soil collection system. 
2. Description of the Related Art 
Typical domestic dishwashers in use today draw wash liquid from a sump at 
the bottom of a wash tub and spray the wash liquid within the wash tub to 
remove soils from dishes located on racks in the tub. In an attempt to 
improve performance and efficiency, some dishwashers employ a system for 
separating soil out of the recirculating wash liquid and for retaining the 
soils in a collection chamber. Frequently, a filter screen is used to 
retain soil in a soil collection chamber. U.S. Pat. No. 5,165,433, issued 
to Meyers, and U.S. Pat. No. 5,377,707, issued to Young, Jr., illustrate a 
common configuration for employing a filter screen in a dishwasher pump. 
In these references, the filter screen is arranged in an annular 
configuration in the cover of the dishwasher pump. 
While filtering is an effective means for cleaning recirculating wash 
liquid, it is relatively costly to incorporate a filter screen into a 
dishwasher pump. Filter screens are typically formed from fine, synthetic 
mesh material, such as nylon or polyester, which is heat welded to a pump 
component, for forming a plurality of filter screen panels or segments. As 
the cost of the synthetic material is relatively high as compared to other 
dishwasher pump components, it is advantageous from a cost standpoint to 
minimize the amount of mesh used. However, in order to achieve 
satisfactory filter performance, the surface area of the filter screen 
must be sufficient to filter dishwasher wash liquid without undue clogging 
concerns. 
In the annular filter screen configurations, as disclosed in the '433 and 
'707 references, the filter screen is fabricated out of rectangular 
sections of synthetic mesh which is then cut into the desired annular 
shape for incorporation in the dishwasher cover. During this fabrication 
process, the cut out center and corner sections are wasted. It can be 
readily appreciated, that for a predetermined filter screen surface area, 
the larger the inner diameter of the annular filter screen, the more waste 
material is generated in the cut out center portion and the corner 
portions. Accordingly, it is desirable, when designing a dishwasher pump 
employing an annular filter configuration, to minimize the inner diameter 
of the filter screen. 
The '433 patent illustrates a pump which centrifugally separates wash 
liquid in a pump impeller cavity and supplies soil laden wash liquid to a 
soil container chamber. In centrifugal pump systems such as this one, it 
is desirable to provide a pump impeller cavity configured to aid in the 
centrifugal separation of soils and delivery to a soil container chamber. 
Another problem to consider when designing dishwasher pump systems is water 
usage. Water usage is a critical concern in dishwasher operation for two 
reasons. Firstly, hot water usage is the principle factor in determining a 
dishwasher's energy performance. Secondly, conservation of water is 
becoming more and more of a concern in many regions of this country and 
the world. Accordingly, it is desirable to utilize a pump which is capable 
of effective operation with a minimal amount of water. In a vertical pump 
configuration such as shown in the patents '433 and '707, this means that 
it is preferable to have a pump having a minimal vertical height. In 
general, the shorter the pump, the less water is required for the pump to 
recirculate wash liquid in the dishwasher. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention is directed to a pump system for a 
dishwasher including a pump housing defining a pump chamber having an 
inverted frustroconical shape including an upwardly angled annular outer 
wall. An impeller is disposed within the pump chamber. An annular soil 
collection chamber is disposed partially above the pump chamber such that 
the bottom wall of the soil collection chamber forms the top wall of the 
pump chamber. Wash liquid is supplied into the soil collection chamber 
from the pump chamber through an opening provided in the bottom wall of 
the soil collection chamber located at the upper, peripheral portion of 
the pump chamber. The upwardly angled annular wall of the pump chamber 
promotes soil movement into the soil collection chamber by directing soils 
toward the upper portion of the pump chamber. Soil is drained out of the 
soil collection chamber through a drain conduit having a flapper type 
check valve. 
The soil collection chamber is formed by an annular soil collector housing 
and a cover which may be snap connected to the annular soil collector 
housing. The cover includes a plurality of filter screen panels such that 
wash liquid supplied into the soil collection chamber is filtered and 
soils are collected. By locating the collection chamber above the pump 
chamber, the inner diameter of the soil collection chamber may be formed 
smaller than the outer diameter of the pump chamber such that the outer 
diameter of the soil collection chamber may be minimized.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In accordance with the invention as shown in the drawings, and particularly 
as shown in FIG. 1, an automatic dishwasher generally designated 10 
includes an interior tub 12 forming an interior wash chamber or 
dishwashing space 14. The tub 12 includes a sloped bottom wall 16 which 
defines a lower tub region or sump 18 of the tub. A pump system 20, 
including a soil collection system, is centrally located in the bottom 
wall 16 and supplies wash liquid to a lower wash arm assembly 22 for 
recirculating wash liquid throughout the interior wash chamber. Wash 
liquid may also be supplied to an upper spray arm (not shown). 
Turning to FIG. 2, the pump system 20 is shown in greater detail. The pump 
includes lower and upper assemblies 30 and 32. The lower assembly 30 
includes a pump base 34 and a drain cover 36 which define a drain impeller 
chamber 38. A drain impeller 40 is rotatably secured to an output shaft 42 
of a motor 44 suspended below the pump system. 
The upper assembly 32 of the pump system includes a pump chamber 48 and an 
annular soil collection chamber 50. A pump housing 52, which partially 
defines the pump chamber 48, is secured to the pump base 34 and includes a 
circular wall portion 52a and an upwardly angled, annular wall portion 
52b. A soil collector housing 54 is disposed above and is fastened to the 
pump housing 52 via threaded fasteners 56 for forming the pump chamber 48. 
A wash impeller 58 is supported within the pump chamber 48 and is 
drivingly connected to the output shaft 42 of the motor 44. 
As shown in FIGS. 2 and 3, the soil collector housing 54 is formed having a 
flat annular wall 54a, an inner wall 54b upwardly angled from the inner 
peripheral edge of the flat annular wall 54a and an outer, cylindrical 
wall 54c extending upwardly from the outer peripheral edge of the annular 
bottom wall 54a. A center opening 60 is provided through the soil 
collector housing 54. A plurality of diffuser vanes 62 extend from the 
housing 54 toward the impeller 58 for generating pressure such that wash 
liquid is moved upwardly through the center opening 60. A pump outlet 
member 64 is connected to the center opening and directs wash liquid to 
the lower wash arm 22 and the upper wash arm of the dishwasher. 
During a wash cycle, the wash impeller 58, driven by the motor 44, draws 
wash liquid from the sump 18 and pumps wash liquid up through a pump 
outlet member 64. The pump outlet member 64 may be secured to the soil 
collector housing 54 through use of fasteners 65. A first portion of wash 
liquid is sprayed from the lower wash arm 22 against dishes supported on a 
lower dishrack and a second portion of wash liquid may be directed toward 
an upper spray arm. Wash liquid is repeatedly recirculated over the dishes 
for removing soils therefrom. 
Once soils are removed from the dishes, they are washed down into the sump 
18. A chopping system may be provided for sizing soils prior to drawing 
them into the pump chamber 48. The basic constructional features of a 
chopper assembly are explained in U.S. Pat. No. 4,319,599, entitled 
"Vertical Soil Separator for Dishwasher", herein incorporated by 
reference. The use of a chopper is optional and is not necessary to 
practice the invention. 
The soil collection chamber 50 is formed by connecting a cover 66 to the 
soil collector housing 54. The cover 66 is an annular member having a 
plurality of filter screen panels 68 (see FIG. 1). The filter screen 
panels 68 are formed from fine, synthetic mesh material, such as nylon or 
polyester, which is heat welded to the cover 66. The outer periphery of 
the cover 66 may preferably be snap connected to the soil collector 
housing 54 via snap openings 70 provided on an annular wall portion 66a of 
the cover 66 which engage projecting tabs 72 provided on the cylindrical 
wall 54c. A snap connection assembly may be used to connect the cover to 
the soil collector housing 54, rather than conventional use of threaded 
fasteners, due to the fact that the filter screen panels 68 prevent 
pressure built up such that the soil collection chamber is maintained at a 
relatively low pressure. The inner portion of the cover 66 is secured to 
the soil collector housing 54 by capturing an annular inner portion 66b of 
the cover 66 between the pump outlet 64 and the soil collector housing 54. 
It can be seen, therefore, that the upper assembly 32 is configured such 
that the soil collection chamber 50 is disposed at an elevation above the 
pump chamber 48 and extends partially above the pump chamber 48. 
Specifically, as preferably disclosed, an inner annular portion of the 
soil collection chamber 54, comprising approximately half of the chamber 
54, is disposed above the outer portion of the pump chamber 48, including 
an outermost annular portion of the wash impeller 58. This configuration, 
wherein the soil collection chamber is disposed partially above the pump 
chamber, allows for a soil collection chamber 54 having a relatively small 
outer diameter while maintaining a desirable filter screen area for 
filtering wash liquid. 
As shown in FIG. 2, the soil collection chamber 50 receives soil laden wash 
liquid from the pump chamber 48 through opening 74 provided in the annular 
wall 54a. The opening 74 is located at the intersection of the upwardly 
angled wall 52b and the annular wall 54a at the outermost portion of the 
pump chamber. Soils in the pump chamber 48, due to the swirling action of 
the wash liquid, are urged to the outermost portion of the pump chamber by 
centrifugal forces such that the wash liquid supplied into the soil 
collection chamber is laden with soils removed from the dishes being 
washed. Moreover, the upwardly angled wall 52b further enhances the flow 
of soils into the soil collection chamber by directing the soils upwardly 
toward the opening 74. A deflector wall portion 76 is provided on the 
cover 66 opposite the opening 74 for deflecting the flow of wash liquid 
through the opening 74 about the soil collection chamber 50 such that 
soils do not become embedded into the filter screen panels. 
FIG. 4 illustrates a diametric section of the pump system 20 cut through 
the drain system of the soil collection chamber 50. The drain system 
includes a drain conduit 78 extending between the soil collection chamber 
50 and the drain impeller chamber 38. A flapper type valve 82 is captured 
between the bottom surface of the drain conduit 78 and a drain cover boss 
84. The valve 82 operates as a check valve for the soil collector chamber 
such that during wash, the drain impeller urges the flapper valve 82 to 
close while during drain the flapper valve 82 opens such that soils can 
drain through the conduit 78 into the drain chamber 38. Accordingly, the 
drain cycle, the drain impeller 40 draws wash liquid out of the soil 
collection chamber 50 and pumps them to drain. 
It can be seen, therefore, that the present invention provides for a 
uniquely compact and cost effective pump system including soil collection 
system. In particular, the pump is configured to minimize the outer 
diameter of the soil collection chamber, thereby minimizing the total 
amount of filter screen required during manufacture of the pump. Moreover, 
pump chamber 48 and the opening 74 for supplying wash liquid into the soil 
collection chamber 50 are configured to enhance soil separation and 
minimize assembly costs. 
While the present invention has been described with reference the above 
described embodiment, those of skill in the Art will recognize that 
changes may be made thereto without departing from the scope of the 
invention as set forth in the appended claims.