Patent ID: 7540220

Claim:
An electronic torque wrench, comprising: a tubular housing having a receiving space; a working unit connected pivotally to said tubular housing, and having a drive head extending outwardly of said tubular housing, and an abutment portion extending into said receiving space; a strain sensor provided in said working unit; a trip unit disposed in said receiving space, and including a cylinder fixed to said tubular housing and having a chamber containing hydraulic fluid, a trip element disposed movably between said abutment portion and said cylinder, and a control element connected to said cylinder, said trip element having a seat portion to seat said abutment portion, and a plunger extending into said chamber, said control element pressurizing said hydraulic fluid so as to push said plunger to thereby cause said abutment portion to be seated on a center of said seat portion of said trip element, or depressurizing said hydraulic fluid so as to permit said abutment portion to move away from the center of said seat portion; and a central processor provided on said tubular housing and connected electrically to said strain sensor and said control element, said central processor controlling said control element to depressurize said hydraulic fluid when an applied torque measured by said strain sensor is larger than a preset reference torque value.