Cleaning and liquid contact with solids – Apparatus – Electrically controlled
Reexamination Certificate
1999-11-08
2001-09-25
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
Electrically controlled
C134S095200, C134S200000, C312S213000
Reexamination Certificate
active
06293289
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
BACKGROUND OF THE INVENTION
The present invention relates to automatic dishwashing machines (dishwashers) and in particular to a dishwasher providing for low noise operation.
Dishwashers, such as those found in many homes, provide a closable chamber holding one or more racks into which eating utensils and cookware may be placed for cleaning. The chamber may include a door, opening to the front of the chamber to allow easy loading and unloading of the chamber, and closing, during a washing cycle, to prevent the escape of water which is sprayed within the volume of the chamber to wash the items placed in the racks.
Upon completion of the washing cycle, a drying cycle is initiated in which water is drained from the enclosure and moist air is discharged through an upper vent. Cool air pulled into the chamber through a lower vent rapidly dries the heated dishes.
Dishwashers can be quite noisy during the washing cycle, the noise coming from the agitated water, movement of the dishes, and the dishwasher mechanism of the water pump and motor. Some of this noise can be reduced by properly shrouding the chamber and dishwasher mechanism with sound absorbing materials. Nevertheless, a considerable amount of noise can still escape from even a properly shrouded chamber through the vents. Even a small vent area can allow a significant amount of noise to escape by diffraction.
One method of reducing noise escaping through the vent is to construct a vent which may close during the washing cycle and then open once the agitated water and pumping action has ceased to allow for proper drying of the dishes. Unfortunately, such closable vents can create a problem when the user interrupts the washing cycle to add a forgotten item for cleaning. When the dishwasher door is opened to insert the additional item, the chamber's volume of heated, moist air is replaced by colder air from the room. When the dishwasher door is reclosed, the hot dishes, racks and walls of the dishwasher together with the agitating hot water quickly heat the cold air causing it to expand. This expansion can force water from the dishwasher out through the door leading the user to believe the dishwasher has malfunctioned.
BRIEF SUMMARY OF THE INVENTION
The present inventors have recognized that a low noise vent for a dishwasher can be produced by properly combining an electrically actuated valve with a pressure actuated valve. The electrically actuated valve may be closed during the washing cycle and opened during the drying cycle, whereas the pressure actuated valve may provide relief of the surge pressure generated when the wash cycle is interrupted and started again.
Importantly, the pressure actuated valve may respond at an arbitrary time in the washing cycle independent of the cycle timer of the dishwasher while the electrically actuated valve may respond during the drying cycle when no triggering change in pressure occurs.
Specifically, then, the present invention provides a noise reducing vent for use with a dishwasher, the vent having an electrically actuated valve positioned to block passage of air from the sealable volume of the dishwasher to the outside of the dishwasher in a closed state and to allow the passage of air from the sealable volume to the outside of the dishwasher in an open state, the electrically actuated valve moving between the open and closed state in response to an electrical signal. The electrically actuated valve is combined with a pressure actuated valve positioned to block the passage of air from the sealable volume to the outside of the dishwasher in a closed state and to allow the passage of air from the sealable volume to outside the dishwasher in an open state, the pressure actuated valve moving from the closed to the open state in response to a predetermined excess of air pressure in the sealed volume over the air pressure outside the dishwasher.
It thus is one object of the invention to provide a vent that can be closed to reduce noise emitted from a dishwasher in response to normal cycle timing of the dishwasher and yet which prevents over-pressure of the sealed volume of the dishwasher such as may occur after interruptions of the washing cycle when the door of the dishwasher is opened.
The electrically actuated valve may employ a wax motor moving a valve element to cover or uncover an aperture leading between the sealable volume and outside of the dishwasher.
Thus it is another object of the invention to permit the use of an inexpensive yet slower wax motor for opening and closing the valve during the expected changes between cycles of the dishwasher while allowing response to extremely fast and unexpected pressure fluctuations caused by interruption of the washing cycle.
The predetermined pressure at which the pressure-actuated valve is triggered may be set to less than one inch of water.
Thus it is another object of the invention to provide a vent which actuates to rapidly suppress low surge pressures that might otherwise be sufficient to expel water from water traps that are used in some dishwashers to block air inlet vents during the washing cycle.
The pressure-actuated valve may be a caged ball seatable against a circular aperture leading between the sealable volume and the outside of the dishwasher. Alternatively, the pressure-actuated valve may include at least one flap hinged to movably cover an aperture leading between the sealable volume and outside the dishwasher.
Thus it is another object of the invention to provide extremely simple and robust valve mechanisms that may be pressure actuated at very low pressures.
The vent may include a common housing providing a first opening to the sealable volume and a second opening to outside the dishwasher, the first and second openings separated by a wall having a first and second aperture, each associated with one of the electrically actuated valves and pressure-actuated valves.
Thus it is another object of the invention to provide an integral vent unit such as may be mounted in the door of the dishwasher or the like.
The housing may include a second wall opposed to the first aperture having a third aperture therein and the electrically actuated valve may include a flexible boot having a valve surface sized to block the first aperture when the electrically actuated valve is actuated to block the first aperture, the flexible boot having side walls extending from the valve surface to an edge attached at the third aperture.
Thus it is another object of the invention to provide an electrically actuated valve that may be shielded from all contact material from the sealable volume of the dishwasher.
The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment does not necessary represent the full scope of the invention, however, and reference must be made to the claims herein for interpreting the scope of the invention.
REFERENCES:
patent: 4247158 (1981-01-01), Quayle
patent: 5572869 (1996-11-01), Schantz et al.
patent: 5660195 (1997-08-01), Taylor, Jr. et al.
patent: 5836324 (1998-11-01), Johnson et al.
patent: 6138692 (2000-10-01), Kobos et al.
patent: 2937589 (1981-04-01), None
Bragg Joel C.
Hapke Kenyon A.
Ark-Les Corporation
Coe Philip R.
Quarles & Brady LLP
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