US Patent 11399459 Prime mover of work machine

A prime mover of a mower that is a work machine comprises: a motor having a motor rotation shaft extended along a substantially vertical direction, and a motor housing disposed coaxially with the motor rotation shaft; a centrifugal fan disposed above the motor; and a motor cover that accommodates the motor and the centrifugal fan so as to extend to the upper end of a side part of the centrifugal fan. A cooling air inlet is formed in the motor housing, the centrifugal fan having a base part provided above the cooling air inlet, and the outer diameter of the base part being greater than the outer diameter of the cooling air inlet.