Patent ID: 6929074

Claim:
An elbow-type power hand tool comprising: a housing; a power drive mounted inside said housing, said power drive including a motor, a planet gear set, and a transmission shaft, said transmission shaft defining an axial line; a torque controller mounted in said housing for controlling output torque of said transmission shaft; a battery pack mounted in said housing for providing electricity to said power drive; an output shaft coupled to an end of said transmission shaft, said output shaft defining an axial line, which defines with the axial line of said transmission shaft a contained angle smaller than 180°; and a chuck assembly coupled to an end of said output shaft for holding a tool bit: wherein said planet gear set comprises a ring gear having a plurality of protruded portions projecting from a top side thereof; said torque controller comprises a socket, a constraint member, a spring member, an outer ring, and a plurality of steel balls, said socket comprising a first body portion accommodating said ring gear, a second body portion for the passing of said transmission shaft, a connecting portion connected between said first body portion and said second body portion, an outer thread extended around a periphery of said second body portion, and a plurality of through holes radially extended through said connecting portion, said second body portion having an outer diameter smaller than said first body portion; wherein said constraint member comprises a coupling barrel, an inner thread formed in an inside wall of said coupling barrel and threaded onto the outer thread at said second body portion, a constraint portion extended from a top side of said coupling barrel, and a plurality of grooves longitudinally arranged on said constraint portion; wherein said steel balls are respectively mounted in the through holes of said socket and stopped at the top side of said ring gear; wherein said spring member has one end thereof pressed on said constraint portion of said constraint member and an opposite end thereof pressed on said steel balls; wherein said outer ring is sleeved onto said constraint member, having a plurality of ribs longitudinally arranged around an inside wall thereof and respectively engaged into the groves of said constraint member; wherein said housing comprises two oval side holes through which the user can rotate said outer ring with the hand.