Automatic purge filtration system for a dishwasher

A soil separation and collection system for a dishwasher wherein the dishwasher has an interior wash chamber receiving wash liquid and a sump disposed at the bottom of the wash chamber, the soil separation and collection system comprising:

• a pump chamber;
• a wash impeller arranged for rotation within the pump chamber for pumping wash liquid;
• a soil collector fluidly connected to the pump chamber and receiving fluid flow from the pump chamber;
• a pressure sensor for sensing fluid pressure within the soil collector;
• a drain pump fluidly connected to the soil collector;
• and
• means controlling the drain pump such that the drain pump is energized for purging the soil collector of soils in response to the pressure within the soil collector exceeding a predetermined limit pressure and the drain pump is deenergized in response to reduced pressure in the soil collector.

A soil separation and collection system for a dishwasher wherein the dishwasher has an interior wash chamber receiving wash liquid and a sump disposed at the bottom of the wash chamber, the soil separation and collection system comprising:

• a pump chamber;
• a wash impeller arranged for rotation within the pump chamber for pumping wash liquid;
• a soil collector fluidly connected to the pump chamber and receiving fluid flow from the pump chamber;
• a drain pump fluidly connected to the soil collector and the sump;
• and
• a control valve for allowing the drain pump to drain fluid from the soil collector while preventing fluid flow from the sump to the drain pump when the wash impeller is pumping wash liquid.

A method of processing water and soil entrained in the recirculating water within a dishwasher having a sump, the method comprising the following steps:

• passing water and soil through an impeller;
• passing at least a portion of the water and soil through a soil collector having a filter screen such that water is filtered through the filter screen and soils are retained in the soil collector;
• sensing the pressure within the soil collector;
• purging the soil collector such that collected soils and water are pumped out of the soil accumulator to drain in response to the pressure within the soil collector exceeding a predetermined limit pressure at least until the pressure within the soil collector falls below the predetermined limit pressure.

A method for operating a dishwasher, said dishwasher comprising a tub, a wash pump and a drain pump, the tub having a lower sump portion for receiving wash liquid, the wash pump being operable to take wash liquid from the sump and distribute the same throughout the tub, the drain pump being operable to deliver wash liquid to drain, the method comprising the steps of:

• introducing a quantity of wash liquid into the tub;
• operating the wash pump to distribute wash liquid throughout the tub and wash soils from dishes enclosed by the tub;
• pumping wash liquid and entrained soils into a soil collector, through a filter screen and back into said sump;
• filtering the soils from the wash liquid as the wash liquid passes through the filter screen and storing the soil in the soil collector;
• sensing the pressure within the soil collector;
• energizing the drain pump to send wash liquid from the soil collector to drain for purging the soil collector in response to the pressure within the soil collector exceeding a predetermined limit pressure;
• deenergizing the drain pump in response to reduce pressure within the soil collector.