US Patent 9948158 Motor cooling systems and devices

A motor cooling system for cooling a motor unit including a stator assembly and a rotor assembly configured to rotate a rotor shaft, which includes a stator casing and an arm casing. The stator casing includes a stator casing body having a stator casing wall with an internal cavity to receive the motor unit and a rib with a groove defined between adjacent portions of the rib. The arm casing includes an arm casing body having an internal cavity to receive the stator casing and a port in fluid communication with the groove.