Soil sensing system for a dishwasher

A method of sensing soils in an automatic dishwasher having an interior wash chamber for receiving wash liquid and a sump region disposed at the bottom of the wash chamber, a wash pump disposed in the sump region and having an intake through which wash liquid is drawn from the sump, the wash pump having a first outlet and a second outlet, and a lower wash arm and an upper wash arm operatively connected to the first outlet, the method comprising the steps of:

• drawing wash liquid through the sump region into the wash pump intake;
• directing wash liquid from the wash pump second outlet to a soil collector;
• collecting soils in the soil collector having a filter;
• selectively directing wash liquid from the wash pump first outlet to the lower wash arm and the upper wash arm;
• selectively directing wash liquid from the wash pump first outlet to the lower wash arm;
• spraying wash liquid from the lower wash arm through at least one jet and toward the filter when the wash liquid is directed to the lower wash arm;
• selectively directing wash liquid from the wash pump first outlet to the upper wash arm thereby disabling the lower wash arm;
• sensing soils in the soil collector with a pressure sensor when the lower wash arm is disabled;
• comparing the soil pressure in the soil collector to a predetermined limit pressure;
• activating a response if the soil pressure in the soil collector exceeds the limit pressure;
• and
• enabling the lower spray arm.

A method of sensing soils in an automatic dishwasher having an interior wash chamber for receiving wash liquid and a sump region disposed at the bottom of the wash chamber, a wash pump disposed in the sump region and having an intake through which wash liquid is drawn from the sump, the wash pump having a first outlet and a second outlet, and a backwash device that receives wash liquid from the First outlet, the method comprising the steps of:

• drawing wash liquid through the sump region into the wash pump intake;
• selectively directing wash liquid from the wash pump first outlet to the backwash device;
• directing wash liquid from the wash pump second outlet to a soil collector;
• collecting soils in the soil collector having a filter;
• spraying wash liquid from the backwash device and toward the filter when the wash liquid is directed to the backwash device;
• disabling the backwash device to discontinue the flow of wash liquid to the backwash device;
• and
• sensing soils in the soil collector with a pressure sensor when the wash liquid is not directed to the backwash device.