US Patent 7789049 Variable capacity water pump via electromagnetic control

A variable flow coolant pump for an engine of a motor vehicle comprises a pump housing defining a fluid chamber. The fluid chamber includes a fluid inlet and a fluid outlet for providing flow of coolant through the housing. An impeller is rotationally supported in the fluid chamber between the inlet and the outlet for pumping coolant through the housing. An engine driven shaft is disposed within the housing for supporting the impeller and rotating the impeller about a longitudinal axis. An electromagnetic field generator selectively produces a magnetic field that moves the impeller axially along the shaft between a first position and a second position which selectively changes the amount of coolant flow through the housing between the fluid inlet and the fluid outlet.