COOLING DEVICE FOR MOTOR

PURPOSE:To reduce the generation of a turbulent flow and coarse and dense states at a time when cooling air flows in, and to lower the noises of cooling air by forming the suction-side end face of a cooling fan case in a complete opening section and forming a front end section in the periphery of the complete opening section in an R shape. CONSTITUTION:When the armature 1a of a motor 1 is turned, a cooling fan 7 is also rotated, and cooling air is sucked in by a cooling-air inflow hole 8a, cools the inside of the motor 1, and is discharged to the outside from an air hole section 1d. The inflow speed of cooling air sucked in from the cooling-air inflow hole 8a is equalized by the side face 8b of a cooling fan case in uniform thickness and a concentric wall 8c in uniform thickness on the outside of the side face 8b at that time, and the front end sections of the side faces 8b and 8c are formed in an R shape and the generation of a turbulent flow is inhibited, and noises by cooling air are reduced.