Patent ID: 9627943
Date: 2017-04-18
CPC Classifications: H02K

Claim:
1. A motor cooling structure for cooling a motor, which includes a shaft transmitting power and a rotor core attached to an outside of the shaft, by a cooling medium, comprising: a cooling medium supply passage that extends to an inside of the shaft in an axial direction of the shaft and passes the cooling medium through the cooling medium supply passage; and a plurality of separate cooling medium passages each of which is branched from the cooling medium supply passage to the rotor core while flowing the cooling medium without branching the cooling medium in the axial direction in order to cool the rotor core and ejects the cooling medium from one or more ejection holes from a plurality of ejection holes opened to a surface of the rotor core, wherein each branch of each separate cooling medium passage from the cooling medium supply passage is further branched in a radial direction at one of two end portions of the rotor core, and leads to at least two separate cooling medium passage portions that pass through the rotor core in the axial direction and connect to different outlets in a balance plate at the other one of the two end portions of the rotor, wherein two of the separate cooling medium passages are branched in the radial direction at a same one of the two end portions of the rotor core, wherein distances from a cooling medium inlet, through which the cooling medium flows into the cooling medium supply passage, to the respective ejection holes are equal between the plurality of cooling medium passages, and wherein the shaft includes a surface including a groove that extends in the axial direction, a part of one of the separate cooling medium passages is formed between the groove and the rotor core, and the groove formed at the surface of the shaft directly communicates with the cooling medium supply passage of the inside of the shaft through a hole in a radial direction.