Food soil handling system for a dishwasher

A food soil handing system for a dishwasher is provided. A main carrier arm has two driver arms rotatably mounted thereon. Each driver arm turns a driver gear engaged with a stationary ring gear. Rotation of the driver arms results in rotation of the main carrier arm, providing significant torque. The main carrier arm is disposed above a drain plate having perforations to drain wash water. A pair of resilient wipers are secured to the main carrier arm to wipe across the plate as the carrier arm rotates. The wipers mash soft food particles through the perforations. Hard items are either swept around or passed over by the wipers for later retrieval.

BACKGROUND OF THE INVENTION 
The present invention generally relates to dishwashers. More specifically, 
the present invention relates to spray arm arrangements and food soil 
handling systems for dishwashers. 
It is desirable to provide a dishwasher which can effectively wash dishes 
which are loaded in a wash cavity of the dishwasher, without the dishes 
having been pre-rinsed to remove food soil. Improvements in dishwashers 
have led to models which are capable of more adequate removal of heavy 
food soil. Therefore, dishwasher users have become accustomed to loading 
dishwashers with dishes which initially have a significant amount of food 
soil remaining on the dishes, further increasing the demands on dishwasher 
performance. 
During operation of a dishwasher, wash water drains from a basin and is 
recirculated through a pump. Food particles washed from the dishes are 
carried by the wash water. A substantial accumulation of such food 
particles can cause a drain system to clog. Therefore, it is desirable to 
provide a dishwasher food soil handling system which prevents clogging. In 
order to prevent such clogging, devices for processing food particles are 
generally known. For example, U.S. Pat. No. 5,143,306 discloses a 
dishwasher having rotating knives driven by a motor for scissoring food 
particles against a grate. Also, U.S. Pat. No. 4,228,962 discloses a 
dishwasher having a grate which is rotatably driven on a pump shaft 
against a resilient block. 
Hard foreign objects, such as rings, screws, etc., are sometimes 
accidentally placed inside a dishwasher. These objects can be damaged by a 
food soil handling device. Likewise, foreign objects or hard food remains 
such as bones, seeds, etc., can damage a food soil handling device. 
Therefore, it is desirable to provide a food soil handling system which 
prevents foreign objects from becoming damaged. Also, it is desirable to 
provide a food soil handling device which is not itself damaged by loose 
hard objects present in a dishwasher. 
An auxiliary component such as a food soil processing device must be 
powered. Preferably, such a device is powered by pressure of the wash 
water exiting a spray arm providing a reaction force which provides the 
power through a conversion of motion from the rotating spray arm into 
mechanical motion of the auxiliary device components. Unfortunately, it 
has been a problem to adequately power auxiliary elements in a dishwasher. 
More particularly, the torque generated by a traditional spray arm is 
sometimes insufficient to overcome the frictional resistance of an 
additional device, or one which provides a significant level of food soil 
processing. 
A traditional dishwasher has a single spray arm rotatably disposed above a 
bottom wall of the wash cavity. Such a spray arm is caused to rotate by 
reaction thrust from water exiting through appropriately oriented spray 
nozzles disposed in the spray arm. A spray arm of this type is incapable 
of generating adequate torque to power other friction-creating elements. 
Therefore, it would be desirable to provide a dishwasher spray arm system 
which provides a substantial amount of torque to power other elements 
operably connected therewith. 
Furthermore, a traditional spray arm has individual nozzles which follow a 
circular path, the same path being repeated during each revolution. It 
would be desirable to improve cleaning action by providing a changing 
spray pattern. Therefore, it would be desirable to provide an improved 
dishwasher spray arm system which movably directs its nozzles in a 
changing path. 
It is known to provide a dishwasher spray system including multiple 
rotating spray arms. For example, U.S. Pat. No. 3,667,473 discloses a 
dishwasher having two small rotating arms mounted on ends of a main 
carrier arm. Also, U.S. Pat. Nos. 3,496,949 and 3,468,486 disclose 
dishwashers having one small rotating arm at the end of a main carrier 
arm. However, in each of these systems, the main arm is freely rotatable 
and is driven simply by water thrust through nozzles located in the main 
arm. Therefore, such systems do not create significant torque. 
SUMMARY OF THE INVENTION 
The present invention provides a dishwasher having a spray arm system which 
creates a significant amount of torque. The present invention also 
provides the food soil handling system driven by this torque. 
To this end, a dishwasher appliance is provided having a rotatable carrier 
arm and at least one driver arm. Each driver arm is rotatably mounted to 
the carrier arm. A ring gear is provided which remains stationary, 
relative to the dishwasher. Also, a driver gear is associated with each 
driver arm and is operably connected rotate with the driver arm. Each 
driver gear is engaged with the stationary ring gear, whereby rotation of 
each driver arm causes the carrier arm to rotate. 
In an embodiment, each driver arm has a plurality of nozzles, the nozzles 
being directed to provide reaction thrust to the drive arms to provide a 
rotational motion. 
In an embodiment, the dishwasher appliance has two driver arms carried on a 
single carrier arm. Also, the driver arms and the carrier arm are hollow 
for delivering a flow of water through each of the arms. 
In an embodiment, a dishwasher appliance is provided having a plate 
positioned above a bottom wall of the wash cavity with a plurality of 
perforations through the plate for draining wash fluid from the wash 
cavity. A rotatable carrier arm is disposed above the plate. At least one 
wiper element is secured to the carrier arm, positioned to resiliently 
contact against the plate. Each wiper element is operable to force soft 
materials through the perforations as the carrier arm rotates and drags 
the wiper over the surface of the plate. Preferably, the wiper elements 
are sufficiently resilient to pass over hard items too large to fit 
through the perforations, but which are held stationary on the plate. 
It is, therefore, an advantage of the present invention to provide an 
improved food soil handling system for a dishwasher. 
A further advantage of the present invention is to provide a spray arm 
system for producing substantial torque. Another advantage of the present 
invention is to provide a spray arm system for washing dishes with a 
changing spray pattern. 
Yet another advantage of the present invention is to provide a food soil 
handling system resistant to clogging. Moreover, an advantage of the 
present invention is to provide a food soil handling system that mashes 
soft food particles. 
A still further advantage of the present invention is to provide a food 
soil handling system which does not damage foreign objects and also which 
is not itself damaged by hard foreign objects. 
Another advantage of the present invention is to provide a food soil 
handling system that traps had food particles. 
Additional features and advantages of the present invention are described 
in, and will be apparent from, the detailed description of the presently 
preferred embodiments and from the drawings.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
In accordance with the invention described with reference to the 
accompanying figures wherein like numerals designate like parts, a 
dishwasher 10 is provided as illustrated in FIG. 1. The dishwasher 10 has 
a housing 11, a door 12, and an upper 14 and lower wire rack 16 for 
holding dishes. The housing 11 generally defines a wash cavity 17 with a 
bottom wall 18 having a circular sump 20 (FIG. 3). In the embodiment 
illustrated in FIG. 1, a main carrier arm 22 is rotatably disposed above 
the bottom wall 18. Rotatably mounted at the ends of the carrier arm 22 
are two driver arms 24. 
Referring to FIG. 2, the carrier arm 22 is rotatably mounted onto a hub 26, 
which extends upwardly above the sump 20. The hub 26 is formed integrally 
with the housing of a pump 28 within which an impeller 30 is located. The 
impeller 30 is driven by a motor 32. 
The carrier arm 22 is hollow and receives water pumped through apertures 33 
in the hub 26. Furthermore, the carrier arm 22 is elongated in shape and 
is mounted to the hub 26 generally midway between ends of the carrier arm 
22. 
The two driver arms 24 are rotatably mounted at opposite ends of the 
carrier arm 22. Each driver arm 24 is carried on a top end of a shaft 36 
which extends through the carrier arm 22. A lower end of the shaft 36 has 
a driver gear 38 secured to it. The shaft 36 is free to rotate relative to 
the carrier arm 22, but the driver arm 24 and the driver gear 38 are 
mounted to the shaft 36 so that no relative rotation occurs between the 
driver arm 24 and the driver gear 38. 
Each shaft 36 and driver arm 24 is hollow and the shaft 36 is provided with 
inlet 37 and outlet 39 apertures to permit a flow of water through the 
shaft into the driver arm. A plurality of nozzles 40 are provided in the 
driver arms 24. As illustrated by the arrows in FIG. 2, water flows from 
the sump 20, through the pump 28 and into the carrier arm 22. Water then 
flows through the shafts 36 into the driver arms 24, from where the water 
escapes under pressure from the nozzles 40. 
The nozzles 40 are configured to direct a water spray in a direction for 
thrusting the respective driver arms 24 to rotate in a common rotational 
direction. As illustrated, each driver arm 24 has two nozzles 40, one 
being positioned at each end of the driver arm. However, more or fewer 
nozzles 40 can be provided. Preferably, all of the nozzles 40 are directed 
to thrust the respective driver arms 24 to rotation, as opposed to a 
conventional system wherein some nozzles 40 can be configured to provide 
no thrust. 
Turning to FIG. 3, a stationary ring gear 42 is mounted to the bottom wall 
18 in a fixed manner. In the embodiment shown, the stationary gear 42 is 
circular and has a diameter approximately equaling the length of the 
carrier arm 22. The driver gears 38 are arranged as planet gears to engage 
the stationary gear 42. 
As indicated by the arrows in FIG. 3, water thrust from the nozzles 40 
results in counter-clockwise rotational motion of each driver arm 24. 
Because the driver gears 38 are secured to rotate with the driver arms 24, 
the driver gears 38 engageably roll along the stationary gear 42. As the 
driver gears 38 rotate, the carrier arm 22 is rotated in a clockwise 
direction. Thus, each nozzle 40 follows a constantly changing path. 
As illustrated in FIGS. 2 and 4, the stationary gear 42 is disposed around 
a periphery of the sump 20. Below the ring gear, a flat annular plate 44 
is disposed across the top of the sump 20. Perforations 46 are provided in 
the plate 44 for permitting a flow of wash water therethrough. Wash water 
drains through the perforations 46 and collects in the sump 20. The pump 
28 recirculates the water from the sump 20 back through the spray arms 22, 
24. 
Secured to the main carrier arm 22 are two flexible wipers 48. Each wiper 
48 extends downwardly from the carrier arm 22 between the pump 28 and the 
driver gears 38 to resiliently contact an area of the plate 44 having the 
perforations 46. During operation, as wash water falls onto the plate 44, 
food particles can get stuck in the perforations 46, if they are too large 
to pass through the perforation. As the wipers 48 wipe around the plate 
44, soft food particles are mashed and forced through the perforations 46. 
Water washes the mashed, soft food down into the sump 20. Hard food 
particles which are too large to fit through the perforations 46 are swept 
along the surface of the plate 44, eventually wearing down in size or 
ultimately being removed from the plate 44 by a user after a wash cycle is 
finished. 
Preferably, food soil carried by the wash water is removed by a 
conventional removal system such as that disclosed in U.S. Pat. No. 
5,165,433 or some other soil separator arrangement (not shown). If a hard 
item gets stuck in a perforation, the wipers 48 resiliently flex to pass 
over the object. Also, hard foreign objects mistakenly placed in the 
dishwasher 10, such as wedding rings, coins, screws, nuts, etc., are wiped 
around atop the plate 44 for later retrieval without danger of damage to 
either the items or the dishwasher 10. 
It should be understood that various changes and modifications to the 
presently preferred embodiments described herein will be apparent to those 
skilled in the art. Such changes and modifications may be made without 
departing from the spirit and scope of the present invention and without 
diminishing its attendant advantages. For example, the carrier arm 22 can 
be configured to carry a different number of driver arms such as one, 
three, four, etc. Also, the directions of motion indicated by arrows in 
FIG. 3 can simply be reversed by reversing the direction of the nozzles 
40. Furthermore, another gear arrangement could be provided, for example, 
wherein the stationary gear has outwardly directed teeth and the driver 
gears engage around an outer periphery thereof. It is, therefore, intended 
that such changes and modifications be covered by the appended claims.