Patent ID: 7794214

Claim:
A pump for pumping a liquid, the pump comprising a magnetic rotor, an electromagnetic stator having at least one electrical winding located in a stator slot and at least one cooling path defined through the slot, and a working conduit defined between the rotor and stator and extending from a pump inlet to a pump outlet, the working conduit having therein an apparatus for pumping the liquid from the pump inlet to the pump outlet, the working conduit being in liquid communication with the cooling path at least at a cooling path inlet to permit a portion of the pumped liquid to circulate through the cooling path when the pump is in use, the cooling path configured to pass between the at least one electrical winding and the stator, thereby permitting the portion of the pumped liquid to contact the at least one electrical winding, wherein the working conduit and cooling path communicate via the at least one cooling path inlet and at least one cooling path outlet, the at least one cooling path inlet comprising an orifice adjacent a downstream end of the rotor relative to a direction of pumped liquid flow through the working conduit, the at least one cooling path outlet orifice comprising an orifice adjacent an upstream end of the rotor, wherein the inlet orifice is smaller than the outlet orifice.