Patent ID: 8820432

Claim:
A pneumatic impulse wrench for tightening screw joints, comprising: a housing having an air inlet passage, an exhaust air outlet passage, and a manually operated throttle valve; a motor; an output shaft; an impulse unit coupling the motor to the output shaft; a torque indicating unit which generates electric signals in response to an output torque; an electrically activated inlet valve; and a programmable operation control unit which communicates with the impulse wrench, wherein the inlet valve is located in the air inlet passage and is arranged to control the air flow through the air inlet passage; wherein an electrically activated exhaust valve is arranged on an outlet side of the motor to control the exhaust air flow through the exhaust air outlet passage; wherein the control unit is configured to individually activate said inlet valve and said exhaust valve in accordance with a programmed tightening strategy and in relation to signals received from the torque indicating unit; wherein said exhaust valve is a proportional valve which is continuously adjustable and which is arranged to be activated in response to signals from the control unit for regulating the exhaust air flow during a screw joint tightening process; and wherein said inlet valve comprises a bi-position valve shiftable between an open position and a closed position, wherein said inlet valve is spring biased towards the open position and is arranged to be shifted towards the closed position by the control unit to interrupt a tightening process as a tightening target condition is reached.