| 摘要 |
A power tool having a housing ( 10,11 ), a rotation motor and an output shaft ( 12;112 ) journalled in the housing ( 10,11 ) and adapted to carry a working implement, wherein the housing ( 10,11 ) has a neck portion ( 19 ) with an annular seal surface ( 22 ), and a seal structure ( 23;123 ) on the output shaft ( 12;112 ) has a clearance surface ( 24; 124 ) facing the annular seal surface ( 22 ) of the housing ( 10,11 ) and being arranged with a narrow gap ( 25;125 ) left between the clearance surface ( 24;124 ) and the annular seal surface ( 22 ) on the housing ( 10,11 ) to form a contact free dust barrier intended to prevent foreign particles from entering the housing ( 10,119 ), and an air flow path is provided in the housing ( 10;119 ) to supply air at the inner periphery of the clearance surface ( 24;124 ) thereby generating by centrifugal action an air flow out through the narrow gap ( 25;125 ) at rotation of the output shaft ( 12 ). |
