Patent ID: 8221554

Claim:
A dishwasher with an efficient prewash function comprising: a cabinet for holding items to be washed; a wash compartment in the cabinet, the wash compartment having a sump for collecting liquid; at least one spray assembly for spraying a liquid into the cabinet; a circulation pump assembly for circulating the liquid from the sump through a first path to and through the spray assembly into the wash compartment and back to the sump for prewashing or through a second path to and through a filter assembly and back to the sump for filtration, the first path excluding the filter assembly and the second path excluding the spray assembly; a drain pump assembly for pumping the liquid from the sump through a third path out of a drain after prewashing and filtration are completed; a controller in communication with the circulation and drain pump assemblies for directing liquid flow path selectively through either the first path, the second path, or the third path; and a filter assembly including a housing having a first end, a second end, and a passageway between the first and second ends, the filter assembly including a filter membrane within the passageway, the housing passageway forming a portion of the second path in a direction from the first end to the second end and forming a portion of the third path in a direction from the second end to the first end, the filter assembly receiving a working flow for prewashing via the first end from the sump, filtering particles from the working flow via the filter membrane, and transmitting the working flow via the second end during a filtering portion of a prewash cycle, the filter assembly receiving a flushing flow after prewashing via the second end, transmitting the flushing flow through the filter membrane to flush out particles filtered from the working flow, and transmitting the flushing flow via the first end to the drain.