Electric water pump

An electric water pump apparatus comprising:na stator generating a magnetic field according to a control signal; anda rotor enclosed by the stator and rotated by the magnetic field generated at the stator to pressurize coolant,wherein the rotor includes:na rotor core having a hollow cylindrical shape to receive a shaft therein, and provided with a plurality of recesses formed by a plurality of guiding protrusions formed at an exterior circumference of the rotor core along a length direction;a plurality of permanent magnets respectively mounted in the plurality of recesses of the rotor core;a front rotor cover covering and being mounted at a front end of the rotor core and front ends of the plurality of permanent magnets and a rear rotor cover covering and being mounted at a rear end of the rotor core and rear ends of the plurality of permanent magnets, so as to fix the rotor core and the plurality of permanent magnets to each other, wherein the front and rear rotor covers are separately formed; anda rotor case enclosing an exterior circumference of the rotor core and the plurality of permanent magnets so as to fix the rotor core and the plurality of permanent magnets to each other in a state that the rotor core and the plurality of permanent magnets are mounted at the front and rear rotor covers;wherein the rotor case is made of a bulk mold compound including a potassium family that has a low coefficient of contraction; andwherein the front and rear rotor covers are provided with at least one balance hole wherein rotational balance of the rotor is adjusted by changing the location and number of the at least one balance hole;wherein the stator includes:na stator core having a hollow cylindrical shape to receive the rotor therein and provided with a stator groove at an inner circumference thereof along a length direction; anda stator case mounted at both distal ends of the stator core, andwherein the stator case is provided with at least one balance hole, wherein rotational balance of the stator is adjusted by changing the location and number of the at least one balance hole.

An electric water pump apparatus comprising:na stator generating a magnetic field according to a control signal;a rotor enclosed by the stator and rotated by the magnetic field generated at the stator;a pump cover having an inlet through which coolant flows in and an outlet through which pressurized coolant flows out;a body having:na front surface forming a volute chamber between the pump cover and the front surface;a stator chamber formed at an outer portion of the body in a radial direction and the stator being mounted in the stator chamber; anda rotor chamber formed at an inner portion of the body in a radial direction, and the rotor being mounted in the rotor chamber, wherein the stator fluidly insulates the rotor chamber from the stator chamber;a shaft having a central axis, fixed to the rotor so as to rotate together with the rotor about the central axis, and mounted in the rotor chamber;an impeller fixed to a front portion of the shaft so as to rotate together with the shaft, pressurizing the coolant having flowed in through the inlet, and mounted in the volute chamber;a driver case detachably mounted at a rear end of the body, formed of a case surface at a front surface thereof, having a rear surface opened backward, and formed with a driver chamber therein; anda driver mounted in the driver chamber and applying a control signal to the stator, wherein the rotor comprises:na rotor core having a hollow cylindrical shape, and provided with a plurality of recesses formed by a plurality of guiding protrusions formed at an exterior circumference of the rotor core along a length direction;a plurality of permanent magnets respectively mounted in the plurality of recesses of the rotor core;a front rotor cover covering and being mounted at a front end of the rotor core and front ends of the plurality of permanent magnets and a rear rotor cover covering and being mounted at a rear end of the rotor core and rear ends of the plurality of permanent magnets, so as to fix the rotor core and the plurality of permanent magnets to each other, wherein the front and rear rotor covers are separately formed; anda rotor case enclosing an exterior circumference of the rotor core and the plurality of permanent magnets so as to fix the rotor core and the plurality of permanent magnets each other in a state that the rotor core and the plurality of permanent magnets are mounted at the front and rear rotor covers;wherein the rotor case is made of a bulk mold compound including a potassium family that has a low coefficient of contraction; andwherein the front and rear rotor covers are provided with at least one balance hole, wherein rotational balance of the rotor is adjusted by changing the location and number of the at least one balance hole.