Brushless motor

摘要

A brushless motor that is highly waterproof and highly watertight is provided. The brushless motor has a casing 1 configured to incorporate and hold a circuit board 4 and to support a rotor 3 rotatably. The casing 1 is configured such that the first annular wall 21 a of a motor cover 21 is secured in part to the inner circumferential surface of the second annular wall 22 a of a board cover 22. The first annular wall 21 a has an annular groove 21 c in its outer circumferential surface. An O-ring 23 is fitted in the annular groove 21 c, accomplishing a highly waterproof and watertight sealing between the motor cover 21 and the board cover 22.