US Patent 9163635 Electric fluid pump

An electric water pump includes a housing, a propelling mechanism disposed in the housing, and a driving mechanism for driving a driving shaft of the propelling mechanism. The driving shaft has a fluid passage in fluid communication with an impeller chamber and a cooling chamber in the housing. The propelling mechanism further includes a spiral rod disposed in the fluid passage and co-rotatable with the driving shaft, and an impeller disposed in the impeller chamber. During operation of the propelling mechanism, the impeller drives flow of a fluid, and the spiral rod co-rotates with the driving shaft to change the rate of the fluid flowing through the driving shaft.