| 摘要 |
PCT No. PCT/SE97/02101 Sec. 371 Date Jun. 15, 1999 Sec. 102(e) Date Jun. 15, 1999 PCT Filed Dec. 16, 1997 PCT Pub. No. WO98/26903 PCT Pub. Date Jun. 25, 1998A torque impulse tool for screw joint tightening includes a housing, a pneumatic motor with a rotor, an output shaft, a hydraulic impulse generator coupling the rotor to the output shaft, and an automatic power shut-off device including a pressure air inlet valve communicating with the pneumatic motor and shiftable between a fully open condition, a partially open condition and a closed condition. In addition, an activation mechanism is provided which is co-rotative with the rotor and which includes a connection member engaging the inlet valve for shifting the inlet valve between the fully open condition, the partially open condition and the closed condition. The activation mechanism includes (i) a first inertia member arranged to accomplish shifting of the inlet valve from the partially open condition to the closed condition as a predetermined maximum retardation magnitude level is reached in the rotor, and (ii) a second inertia member arranged to accomplish shifting of the inlet valve from the partially open condition to the fully open condition at retardation magnitudes in the rotor exceeding a predetermined threshold level, below the maximum retardation magnitude level, thereby providing a reduced motor speed and power output during an initial tightening stage. |
