| 摘要 |
PROBLEM TO BE SOLVED: To prevent intrusion of foreign matter through a silencer hole by employing an elastic material in the housing surrounding a motor and a membrane being stretched over a hole in an end bracket. SOLUTION: The thin outer rotor type brushless motor comprises a housing 1, an end bracket 2, a stator core 3, and a stator coil 4 on the stator side and a rotor case 5, a permanent magnet 6, and a shaft 7 on the rotor side. The housing 1 is provided with a concentric silencer groove or hole for varying the natural frequency. A rotor is disposed in the housing and in order to prevent intrusion of a foreign matter, the groove or the hole must be choked with thermoplastic elastomer having hardness close to that of rubber. Hardness of the elastomer is set in the range of Shore hardness (D) 45-55. According to the structure, intrusion of dust, and the like, can be prevented while eliminating vibration and keeping silence. |
