Electric water pump

Abstract

An electric water pump includes a pump cover having an inlet through which coolant flows; a stator chamber having a stator generating a magnetic field according to a control signal; a rotor chamber having a rotor rotating according to the magnetic field generated by the stator; a separation wall configured to separate the stator chamber from the rotor chamber; a shaft having a central axis, fixed to the rotor so as to rotate together with the rotor about the central axis thereof; and an impeller fixed to a front portion of the shaft so as to rotate together with the shaft, the impeller pressurizing a coolant having flowed in through the inlet, wherein at least one wing portion is formed on a part of the shaft to increase a flow of the coolant.

What is claimed is: 
     
         1 . An electric water pump comprising:
 a pump cover having an inlet through which a coolant flows;   a stator chamber having a stator that generates a magnetic field according to a control signal;   a rotor chamber having a rotor rotated by the magnetic field;   a separation wall configured to separate the stator chamber from the rotor chamber;   a shaft having a central axis, the shaft fixed to the rotor so as to rotate together with the rotor about the central axis; and   an impeller fixed to a front portion of the shaft that rotates together with the shaft and pressurizes the coolant flowing through the inlet,   wherein at least one wing portion is formed on a part of the shaft to increase a flow of the coolant.   
     
     
         2 . The electric water pump of  claim 1 , wherein the wing portion is formed at a front or a rear end portion of the shaft. 
     
     
         3 . The electric water pump of  claim 2 , wherein the shaft comprises:
 a trunk portion extended through a center of the separation wall along the central axis; and   an extending portion having a smaller diameter than the trunk portion and extended from a front portion or a rear portion of the trunk portion along the central axis,   wherein the wing portion has at least one rotatable blade protruding from the front portion or the rear portion of the trunk portion so as to increase the flow of the coolant.   
     
     
         4 . The electric water pump of  claim 2 , wherein the wing portion has at least one rotatable blade protruding outwardly in a radial direction from an exterior circumferential portion of the trunk portion or the extending portion to increase the flow of the coolant. 
     
     
         5 . The electric water pump of  claim 4 , wherein the wing portion has a tapered shape which becomes narrow gradually in a radial direction, and has a sharp end portion. 
     
     
         6 . The electric water pump of  claim 4 , wherein the wing portion comprises:
 at least one long blade configured to protrude from the exterior circumferential portion in a radially outward direction; and   at least one short blade configured to protrude from the exterior circumferential portion in a radially outward direction, the at least one short blade having a smaller radius of rotation than the long blade.   
     
     
         7 . The electric water pump of  claim 6 , wherein the at least one long blade and the at least one short blade are alternately arranged. 
     
     
         8 . The electric water pump of  claim 4 , further comprising:
 a body having the stator chamber and the rotor chamber; and   a driver case mounted at a rear end of the body, having a fixing member protruding in a forward direction to fix the separation wall thereto.   
     
     
         9 . The electric water pump of  claim 8 , wherein a separation space is formed between a rear surface of the separation wall and a front surface of the driver case. 
     
     
         10 . The electric water pump of  claim 9 , wherein a front end portion of the fixing member is disposed apart from the rear surface of the separation wall.