Solid material comminution or disintegration – Apparatus – Including means applying fluid to material
Reexamination Certificate
2000-03-14
2002-08-27
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Apparatus
Including means applying fluid to material
C241S046017, C241S046080
Reexamination Certificate
active
06439487
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to food waste disposers and, more particularly, to a grinding mechanism or assembly for a food waste disposer.
BACKGROUND OF THE INVENTION
Although food waste disposers are widely available, manufacturers continue to optimize the grinding operation of such disposers. To perform the grinding operation, conventional disposers typically include a rotating grind plate. The rotating grind plate has grinding lugs attached to the plate. The food waste delivered to the rotating grind plate is forced by the grinding lugs against a stationary shredder ring. The stationary shredder ring has teeth that grind the food waste into particulate matter sufficiently small to pass from above the rotating plate to below the grinding plate via gaps between the teeth outside the periphery of the rotating plate. The particulate matter then passes to a discharge outlet and into the drain pipe.
The fineness and speed of the grind are important considerations in designing the grinding mechanism for a disposer. A manufacturer must consider the demands of a wide variety of food waste with varying properties (i.e., soft, hard, stringy, leafy, and resilient). The types of food waste have changed over the years. Due to healthier diets, consumers tend to eat more fruits and vegetables. This results in food waste having a soft, stringy, leafy, and resilient consistency. Additionally, the modern diet increased the use of white meat. The waste from meat is typically bone. Although the bones from white meat are typically not as durable or difficult to grind than bones from red meat, the bones from white meat tend to splinter. The grinding mechanism must be adequate for all types of food waste.
The type and geometry of the grinding lugs affect the fineness and speed of the grind. Grinding lugs may either be stationary (fixed lugs) or free to rotate (swivel lugs). Early food waste disposers used fixed lugs One example of a disposer with fixed lugs is disclosed in U.S. Pat. No. 4,128,210 (Brenner et al.). There, a fixed impeller or lug extends upwardly and is rigidly attached to the rotating grinding plate. The geometry of the fixed impeller or lug includes a series of steps. The steps rise inwardly toward the center of the rotating grinding plate. Another example of a disposer with fixed lugs is disclosed in U.S. Pat. No. 5,340,036 (Riley), which is owned by the assignee of the present application. There, fixed impellers or lugs are used in a dry waste disposer. In one embodiment, the geometry of the fixed grinding impeller or lug is sloped where the slope rises or increases inwardly toward the center of the rotating grinding plate. In other embodiments, the geometry of the fixed grinding impeller or lug is in a z-shaped or c-shaped configuration. A further embodiment includes a flat grinding impeller or lug. Again, the impeller or lug is rigidly fixed to the rotating plate.
Today, disposers typically use swivel lugs. A food waste disposer having swivel lugs is disclosed in U.S. Pat. No. 6,007,006 (Engel et al.), which is owned by the assignee of the present application and incorporated herein by reference in its entirety. The disposer may be mounted in a well-known manner in the drain opening of a sink using mounting members of the type disclosed in U.S. Pat. No. 3,025,007 (Weiczorek), which is owned by the assignee of the present application and also incorporated herein by reference in its entirety.
As shown in
FIG. 1
, a conventional disposer includes an upper food conveying section
20
, a lower motor section
22
, and a central grinding section
24
disposed between the food conveying section
20
and the motor section
22
. The food conveying section
20
includes a housing
26
that forms an inlet
28
at its upper end for receiving food waste and water. The housing
26
also forms an inlet
30
for passing water discharged from a dishwasher (not shown). The housing
26
has diverters
96
that are shaped to points
97
. The food conveying section
20
conveys the food waste to the central grinding section
24
. The motor section
22
includes an induction motor
32
imparting rotational movement to a motor shaft
34
. The motor
32
is enclosed within a motor housing
36
having an upper end frame
38
, a metal lower end frame
40
, and a bent metal stator band
42
extending between the upper and lower end frames
38
and
40
.
The grinding section
24
shows a typical grinding plate with swivel lugs. The swivel lug grind system in
FIG. 1
has a circular rotating plate or disc
48
, a pair of swivel lugs
72
, and a stationary shredder ring
46
. The plate
48
is mounted to the motor shaft
34
of the motor section
22
. The swivel lugs
72
are fastened to the plate
48
, but are free to rotate relative to the rotating plate
48
. The grinding section
24
includes a housing
52
. The housings
26
and
52
are fastened to the lower end frame
40
by a plurality of bolts
54
.
As shown in
FIGS. 2 and 3
, the shredder ring
46
, which includes a plurality of spaced teeth
58
, is fixedly attached to an inner surface of the housing
52
. In the operation of the food waste disposer, the food waste delivered by the food conveying section
22
to the grinding section
24
is forced by the swivel lugs
72
against the teeth
58
of the shredder ring
46
. The edges of the teeth
58
grind the food waste into particulate matter sufficiently small to pass from above the grinding plate
48
to below the grinding plate
48
via gaps between the teeth
58
outside the periphery of the plate
48
. Due to gravity, the particulate matter that passes through the gaps between the teeth
58
drops onto the upper end frame
38
and, along with water injected into the disposer, is discharged through a threaded discharge outlet
98
into a tailpipe
97
. As shown in
FIG. 1
, the tailpipe
97
may be connected to the discharge outlet
98
by an off-the-shelf plumbing nut
99
. There are other known ways to connect a food waste disposer to a tailpipe
97
as explained in U.S. Pat. No. 6,007,006 (Engel et al.).
Although the food waste disposer in
FIG. 1
operates efficiently and effectively, it has been found, through the present invention, that a fixed lug grind system can provide a finer grind by optimizing the design of the grind elements.
The problem of jamming is another important consideration in designing the grinding operation. Prior food waste disposers with fixed lugs were known for jamming. Jamming occurs when hard objects such as bones or broken pieces of flatware enter the food waste disposer and get stuck between the rotating grinding elements and the stationary shredder ring. In an attempt to resist jams, the prior art tried to increase the rotational speed of the rotating grind elements or capacitor start. This required increasing the horsepower of the motor, however, and resulted in additional costs of the disposer.
Additionally, to resist jams, the prior art attempted to add swivel lugs to the rotating grinding plate. Although the food waste disposer in
FIG. 1
with swivel lugs reduces jams, it has been found, through the present invention, that jamming can also be reduced using fixed lugs by modifying the profile of the lugs without increasing horsepower or capacitor start.
The use of swivel lugs has disadvantages. For example, swivel lugs produce a noisier grinding operation. Moreover, the use of swivel lugs creates a problem known as “stuck” lugs. This happens when a food particle (typically a bone fragment or splinter) lodges itself beneath the lug and prevents the lug from moving. A “stuck” lug can cause imbalances, resulting in further noise and a degradation of the grind performance. Additionally, when a swivel lug is “stuck,” the food waste is more coarse, which can result in clogged drains.
The use of swivel lugs also increases the chances of “riding.” Riding occurs when food particles rotate at the same speed as the grind elements without being ground. Swivel lugs promote riding because they comply to the motion of the food partic
Anderson Scott W.
Barke David W.
Boske Paul W.
Kolloch Timothy W.
Emerson Electric Co.
Howrey Simon Arnold & White , LLP
Rosenbaum Mark
LandOfFree
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