Method and apparatus for reducing wash tub displacement during spin cycle ramp-up

摘要

A method and a suspension structure for reducing displacement of a wash basket of a washing machine includes first providing the wash basket with a balance ring. The balancing ring is attached to the basket in the plane that is generally perpendicular to a rotation axis of the basket. The balancing has a balancing mass that is movable relative to the ring. The wash basket is supported by a tuned suspension structure to the machine. Two resonance critical frequencies for two translational degrees of freedom and that are in the plane of the balancing ring are determined. The three resonance rotational frequencies for the three rotational degrees of freedom of the suspension structure are also determined. The suspension structure is tuned so that the two critical frequencies of translation each occur at or below a critical first motor speed and so that the three rotational frequencies occur at a second speed that is above the critical rotation speed. The motor is controlled to initially ramped up the speed of the wash basket to an initial spin speed that is incrementally higher than the first critical speed and lower than the second speed. The motor speed is then dwelled for a period of time at the initial spin speed. The motor is then ramped up to a final spin speed that is above the second speed. A washing machine of the invention incorporates the tuned suspension structure or a motor that is speed controlled as described, or both.