Tools – Miscellaneous
Reexamination Certificate
2003-02-04
2004-11-02
Shakeri, Hadi (Department: 3723)
Tools
Miscellaneous
C081S177100, C081S442000
Reexamination Certificate
active
06810776
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
FEDERALLY SPONSORED RESEARCH
Not Applicable
BACKGROUND OF THE INVENTION-FIELD OF INVENTION
This invention relates to devices for freeing the jammed rotor plate and cutters of a garbage disposal device.
BACKGROUND OF THE INVENTION
Garbage disposal units commonly installed in kitchen sinks are prone to jamming. Such disposals have a narrow drain aperture in the sink floor that opens into a wider chamber below. At the base of this chamber is a flat circular plate. Two upraised detents or cutting blades are mounted at the opposing edges of this plate. When the motor spins this plate via a shaft from below, waste is thrown outward on the plate to the cutting blades. There it is pulverized by the rotational speed of the blades and by being pressed between the blades and the outer wall of the disposal chamber. Water from the sink then washes the pulverized material out, down, and away.
Jamming occurs when a hard piece of waste, such as a pit or bone fragment,becomes lodged between moving parts of the unit, such as the rotor plate and outer wall of the chamber or in the region where the power shaft enters the chamber from below. To overcome this jamming, it is necessary to work the waste fragment out either by rotating the plate backward and forward, or by further crushing the fragment by turning the circular plate in its accustomed direction with considerable force. Householders often try to do this with a kitchen utensil, broomstick, or long screwdriver. However, because of the shape of the disposal with its narrow sink drain opening, it is very difficult to apply force in the proper lateral direction to the cutters and thereby unjam the plate. In some cases a great deal of force must be applied because the previous rotation of the plate or efforts to free it have more firmly wedged the waste fragment in place. In such circumstances, the efforts to unjam the disposal may damage it. In the end, many homeowners are forced to call a plumber who disassembles the unit or replaces it. Throughout this process, homeowners are often tempted to insert their hands into the disposal unit. Should the power be turned on while this is happening, grievous injuries can result.
Inventors have previously tried in several ways to address this problem of the need safely to exert considerable torque in the unusual confines of an installed disposal unit. U. S. Pat. No. 4,050,334 to Davis, Jr. (1977) discloses a wrench shaped roughly in the shape of a zee (See Prior Art, FIGS.
7
A and
7
B). The wrench is in the form of a shaped single-piece of metal with a straight, vertical shaft section. The handle end of the wrench is bent at an acute angle to the axis of the shaft section, and the opposing toolbar end is bent in the plane of the handle section to lie perpendicular to the shaft section. The toolbar section is long enough to engage both cutting blades on the rotor plate, but too long, when held in its working, horizontal position, to fit through the narrow sink opening. By angling the tool section into a semi-vertical position, it is possible to insert the toolbar end through the sink opening and then position it flat against the rotor at the bottom. In this position, with the shaft section now vertical, the handle end, which is bent out from the shaft in the opposite direction of the toolbar end, is turned to rock the rotor back and forth. In this design, however, several factors limit the amount of lateral force that can be applied to the cutters. The zee shape of the wrench causes one of the two cutters to be engaged primarily as a pivot for the turning procedure. The shape of the device also causes the shaft to rotate about an axis somewhat offset from the central access of the rotor plate. As a result of these factors, most of the lateral force is applied to the second, opposing cutter at the free end of the toolbar. This force is reduced by the reverse lever effect of its being exerted at the relatively distant tip of the toolbar. This unbalanced application of lateral force to the two cutters significantly reduces the amount of torque that can be applied to the underlying rotor plate. In the absence of sufficient force, many serious jams cannot be overcome and may even be worsened. A further problem is that the thin, vertical metal shaft of this one-piece device cannot be securely grasped to apply turning force.
U.S. Pat. No. 2,803,981 to Stoecker (1957), U.S. Pat. No. 3, 213,720 to Wallis et al. (1965) and U.S. Pat. No. 5,685,209 to Fiedler (1997) take a different approach to this problem. All disclose a single vertical shaft attached to a handle at the top, and, at the bottom, to the toolbar. The toolbar is connected at its center to the shaft at the shaft's bottom end and the toolbar is allowed, by means of a hinge, rivet, or nut and bolt arrangement, to pivot at its connection point. To permit the toolbar's insertion into the sink opening, the toolbar is tilted up on one of its sides so as to lie close to the shaft and extend away from the shaft on the other. Once inside the chamber of the disposal, the toolbar can be flattened out to its working horizontal position by being pressed against the rotor. Since the toolbar is attached at its center to the vertical shaft, this permits more equal application of torque to the rotor than the single-piece zee design.
However, this approach also has problems. It requires considerable torque to be applied to the toolbar at the weakest point of the entire device: the single hinge, rivet, or bolt connection that permits the toolbar to pivot at the base of the shaft. Whatever means are used to design this pivoting attachment, the repeated application of a great amount of torque at this point can easily cause the pivot to loosen, bend or break over time. If the pivot is even slightly bent out of shape, the toolbar may then be stuck in the horizontal position, making its removal from the narrow sink aperture very difficult, adding a further serious problem to the original one of jamming. This situation invites the homeowner to insert a hand into the disposal chamber to free the stuck toolbar, with the attendant risks of such an action. Returning the toolbar to a semi-vertical position for removal through the narrow opening is also a problem in this design. The U.S. Pat. No. 5,685,209 to Fiedler (1997) seeks to remedy this in one embodiment by making one side of the toolbar slightly longer than the other, allowing gravity to pull the resulting heavier side down. However, this inequality of lengths decenters the axis of the shaft from that of the rotating plate and reduces the equality of force applied to the cutters. The required looseness of the pivot for this solution is also easily threatened by dirt in the disposal chamber or any deformation of the pivot point caused by torque applied at that point. In another embodiment in the U.S. Pat. No. 5,685,209 to Fiedler (1997), a spring
150
is used to hold the toolbar in a semi-vertical position until pressed against the rotor plate (See Prior Art FIG.
8
A). In another embodiment of the same patent (Prior Art FIG.
8
B), a pull rod
152
is used to angle the bar up for removal. Such mechanisms are particularly subject to damage in the dirty environment of the disposal chamber and when great rotational force is applied to the tool. All pose the risk of leading the homeowner to insert a hand into the disposal chamber to free the stuck mechanism.
All garbage disposal unjamming devices face a common problem of inserting a toolbar long enough to exert balanced force to two cutters on opposite sides of the rotor plate yet also able to pass through the narrow drain opening. All such devices heretofore known suffer from one or more of a number of disadvantages:
(a) If the device is made of a single piece and formed so as to allow the toolbar to pass through the opening, the resulting shape does not permit a balanced application of lateral force in opposing directions to each cutter.
(b) If the problems of toolbar insertion and the need for central posi
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