Patent ID: 7458297

Claim:
An electronic torque wrench, comprising: a tubular housing having a surrounding wall that confines a receiving space having a longitudinal axis; a working unit having a drive head extending outwardly of said tubular housing, and a shank portion extending axially into said receiving space and pivoted to said surrounding wall at a pivot point; a strain sensor provided in said working unit; a trip unit having a pair of driven elements protruding from said shank portion in two opposite directions transverse to said longitudinal axis and movable to and away from said surrounding wall, said driven elements being further movable between a non-tripping position, in which said driven elements are pressed tightly against said surrounding wall so that said working unit cannot pivot relative to said tubular housing, and a tripping position, in which said driven elements are not pressed tightly against said surrounding wall so that said working unit is permitted to pivot relative to said tubular housing, said trip unit further having a control element disposed in said shank portion to press or release said driven elements and connected electrically to said central processor; and a central processor provided in said tubular housing and connected electrically to said strain sensor and said trip unit, said central processor controlling and moving said driven element to said tripping position when an applied torque measured by said strain sensor is larger than a preset reference torque value; wherein said control element has a plunger disposed in said shank portion and movable axially so as to extend in between and push said driven elements against said surrounding wall, or to retract away from and release said driven elements; and wherein said control element further has a spring biasing said plunger to extend in between said driven elements, and a solenoid coil to retract said plunger from said driven elements.