Stainless steel cover for plastic spray arm

The present invention provides a wash arm assembly for a dishwasher which includes a molded plastic wash arm and a stainless steel cover. The plastic wash arm has a top surface, lateral surfaces, and a bottom surface and the stainless steel cover wraps over the top surface of the plastic wash arm, around the lateral surfaces of the plastic wash arm, and over a portion of the bottom surface of the plastic spray arm to hold the cover on the spray arm. The top surface of the plastic wash arm defines a series of wash jets and the stainless steel cover defines openings aligned with the wash jets so that the metal cover does not interfere with the wash jets.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to a rotatable wash arm for a 
dishwasher and, more particularly, to an improved wash arm assembly which 
includes a plastic wash arm and a metal cover. 
2. Description of Related Art 
Automatic dishwashers which pump wash water through rotatable wash arms for 
distribution of the wash water throughout the washing chamber, to wash 
articles placed therein, have traditionally utilized wash arms 
manufactured from stainless steel material. Stainless steel wash arms, 
however, can require a large number of parts and therefore a large amount 
of manufacturing tooling and assembly. This is especially true when the 
wash arm includes extensions such as, for example, extensions for 
clean-out jets for cleaning a filter at a pump inlet. As a result, wash 
arms are often manufactured from a thermoplastic material in order to 
realize a reduction in manufacturing costs. Thermoplastic wash arms, 
however, have a different appearance than the traditional stainless steel 
wash arms and may not have a pleasing aesthetic appearance to the operator 
of the dishwasher. Accordingly there is a need in the art for an improved 
wash arm which provides a pleasing aesthetic appearance at a reduced 
manufacturing cost. 
SUMMARY OF THE INVENTION 
The present invention provides an improved wash arm assembly for a 
dishwasher which overcomes at least some of the above-described problems. 
The wash arm assembly includes a plastic wash arm and a metal cover. The 
plastic wash arm has a top surface, lateral surfaces, and a bottom surface 
and the metal cover wraps over the top surface and around the lateral 
surfaces of the plastic wash arm. In preferred embodiments, the metal 
cover extends over a portion of the bottom surface to hold the metal cover 
on the plastic wash arm. The metal cover provides a pleasing aesthetic 
appearance to the wash arm at a reduced cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to the drawing figures, components of a dishwashing machine 
10 in accordance with the present invention are shown. The dishwashing 
machine 10 generally includes a tub 12, a pump assembly 14, and a spray or 
wash arm assembly 16. The tub 12, which includes means such as racks (not 
shown) to receive dishes, silverware, glasses, and the like, defines a 
sump 18 at a lower portion thereof. The pump assembly 14, which is mounted 
to the tub 12 at a bottom of the sump 18, is powered by an electric motor 
20 and is generally operable to pump wash water from the sump 18 to the 
wash arm assembly 16 when operating in a recirculating mode, and to pump 
wash water from the sump 18 to a drain (not shown) when operated in a 
drain mode. Streams of dish-cleaning wash water project upwardly from the 
wash arm assembly 16 to the dishes in the racks and then fall to the sump 
18 at the bottom of the tub 12. The wash arm assembly 16 includes a 
plastic wash arm 22 and a metal cover 24. 
FIG. 2 illustrates the plastic wash arm 22 which includes first and second 
arm portions 26, 28 extending in opposite directions and a generally 
hollow interior. The plastic wash arm 22 is preferably molded in upper and 
lower halves 30, 32 from a thermoplastic material such as polypropylene. 
The upper and lower halves 30, 32 are subsequently joined together by a 
process such as ultrasonic welding or the like to form a water-tight joint 
and thereby create the one-piece plastic wash arm 22. The upper and lower 
halves 30, 32 are preferably joined at a generally horizontal plane 
intersecting the lateral surfaces 34 of the first and second arm portions 
26, 28. 
A top surface 36 of the plastic wash arm 22 has an upwardly stepped portion 
38 which is generally planar and extends across each of the arm portions 
26, 28. The stepped portion 38 provides or defines a series of upwardly 
directed openings or wash jets 40, 42 through which the streams of 
dish-cleaning wash water project. The illustrated plastic wash arm 22 
provides four circular wash jets 40 on the first arm portion 26 and three 
circular wash jets 40 on the second arm portion 28. Additionally, a 
generally crescent-shaped wash jet 42 is provided at the outer end of each 
of the arm members 26, 28. The wash jets 40, 42 are preferably adapted 
such that reaction forces are created by the water emanating from the wash 
jets 40, 42 to rotatably drive the wash arm assembly 16 about its axis of 
rotation 44. To achieve this result, some or all of the wash jets 40, 42 
can be upwardly and outwardly directed. Preferably, the wash jets 40, 42 
are adapted such that the wash arm assembly 16 rotates at about 20-22 
revolutions-per-minute. 
Naturally, the scope of the present invention is not limited to the 
specific pattern, shape, number, or size of the wash jets 40, 42 described 
herein. Rather, it is evident that any type or arrangement of wash jets 
40, 42 may be employed to supply sprays of wash water to the dishes within 
the tub 12. 
A generally planar bottom surface bottom surface 46 (FIG. 4) of the plastic 
wash arm 22 has a downwardly-directed cylindrical hub 48 at the 
intersection of the first and second arm portions 26, 28 which is 
generally coaxial with the vertical axis of rotation 44 of the wash arm 
assembly 16. The hub 48 includes a pair of resilient snap-fit clips 50 
(FIG. 4) for mounting the wash arm assembly 16 to the pump assembly 14. 
The hub 48 forms an interior passage which communicates the hollow 
interior of the plastic wash arm 22 with an inlet 52 at a lower end of the 
hub 48. When the wash arm assembly 16 is mounted, the inlet 52 is in fluid 
communication with an outlet (not shown) of the pump assembly 14. 
The bottom surface 46 of the plastic wash arm 22 also provides downwardly 
directed, generally rectangularly-shaped, extensions 54, 56. Each of the 
extensions 54, 56 provide or define an opening or wash jet 58, 60 through 
which a stream of filter-cleaning wash water projects. An outer extension 
54 is provided near the outer end of each of the arm portions 26, 28. Each 
outer extension 54 defines a wash jet 58 which provides an inwardly and 
generally horizontal stream of wash water. An inner extension 56 is 
provided near the hub 48 on the second arm portion 28. The inner extension 
56 defines a wash jet 60 which provides an downwardly and generally 
vertical stream of wash water. Together, the clean-out wash jets 58, 60 
operate to clean a filter at the inlet of the pump assembly 14. 
FIGS. 3 and 4 illustrate the wash arm assembly 16 with the metal cover 24 
installed on the plastic wash arm 2. The one-piece metal cover 24 is 
preferably formed from stainless steel but other suitable metals can be 
alternatively utilized. The metal cover 24 wraps over the top surface 36 
of the plastic wash arm 22, around the lateral surfaces 34 of the plastic 
wash arm 22, and over a portion of the bottom surface 46 of the plastic 
wash arm 22. As best shown in FIG. 3, the metal 24 cover substantially 
covers the entire top and lateral surfaces 36, 34 of the plastic wash arm 
22. The portion of the metal cover 24 over the top surface 36 of the 
plastic wash arm 22 is generally planar and defines clearance openings 62 
aligned with the wash jets 40, 42. The openings 62 are sized, shaped, and 
positioned such that the metal cover 24 does not interfere with the 
streams of wash water from the wash jets 40, 42. The metal cover 24 
includes a generally continuous and inwardly directed flange 64 around the 
periphery of the bottom surface 46 of the plastic wash arm 22. The flange 
64 engages the bottom surface 46 of the plastic wash arm 22 to retain the 
metal cover 24 on the plastic wash arm 22. The metal cover 24 is 
preferably formed to substantially conform to the shape of the plastic 
spray arm 24. To this end, the metal cover 24 can be stamped directly onto 
the molded plastic spray arm 22. 
FIG. 5 illustrates a metal cover 70 which is similar to the metal cover 24 
of FIG. 4 except that the metal cover 70 is held onto the plastic wash arm 
22 by a series of spaced apart inwardly extending tabs 72 at the bottom 
surface 46 of the plastic wash 22 arm rather than the generally continuous 
flange 64. FIG. 5 uses like reference numerals for like structure. The 
metal cover 70 illustrates that alternative means for attaching the metal 
cover 70 to the plastic spray arm 22 can be utilized. 
It is noted that while the illustrated embodiments describe in detail a 
lower wash arm assembly 16, the present invention can also be utilized 
with upper or intermediate wash arm assemblies. With upper or intermediate 
wash arm assemblies, however, it may be desirable to form the metal cover 
24 such that the metal cover 24 is also over substantially the entire 
bottom surface 46 of the plastic wash arm 22. 
Although particular embodiments of the invention have been described in 
detail, it will be understood that the invention is not limited 
correspondingly in scope, but includes all changes and modifications 
coming within the spirit and terms of the claims appended hereto.