Patent ID: 7168503
Filing Date: 2007-01-30
Classification: B25B

Abstract:
1. A power hand tool comprising: a housing; a motor fixedly mounted inside said housing, said motor having a motor shaft; a transmission gear set mounted inside said housing, said transmission gear set comprising at least one sun gear coupled to said motor shaft, at least one planet carrier, at east one planet gear set rotatably mounted on said planet carrier and rotatable by said sun gear directly or indirectly, and an output shaft fixedly provided at said planet carrier; a torque control mechanism comprising: an impact mechanism comprising a final output shaft, a transmission shaft, an impact element, and a spring member, said final output shaft being rotatably mounted in said housing and partially extended out of said housing, said final output shaft having a coupling portion at one end thereof, said transmission shaft being coupled to the output shaft of said transmission gear set for synchronous rotation with the output shaft of said transmission gear set, said impact element being sleeved onto said transmission shaft and axially movable along said transmission shaft between a third position and a fourth position, said impact element having a coupling portion, the coupling portion of said impact element being coupled to the coupling portion of said final output shaft for allowing rotation of said final output shaft with said transmission shaft and the output shaft of said transmission gear set when said impact element is located at said third position, the coupling portion of said impact element being disengaged from the coupling portion of said final output shaft when said impact element is located at said fourth position, the spring member of said impact mechanism being supported between said transmission shaft and said impact element to hold said impact element in said third position; wherein said impact element is stopped by said adjustment device in said third position and prohibited from moving to said fourth position when said adjustment device is in said first position.