초록 ▼

An automatic shutoff mechanism is designed for a pneumatic tool having an air motor, a pressurized airflow path to the motor and a torquing mechanism driven by the motor. The shutoff mechanism includes a valve member moveable between open and closed positions relative to the airflow path and biased

An automatic shutoff mechanism is designed for a pneumatic tool having an air motor, a pressurized airflow path to the motor and a torquing mechanism driven by the motor. The shutoff mechanism includes a valve member moveable between open and closed positions relative to the airflow path and biased to the open position. A trip apparatus is responsive to application of a predetermined torque for moving the valve member to a trip position disposed in the airflow path sufficiently to expose the valve member to the pressurized airflow for driving the valve member from the trip position to the closed position. Mechanical and electromechanical embodiments are disclosed.

대표청구항 ▼

1. An automatic shutoff mechanism for a pneumatic torque-applying tool having an air motor, a pressurized airflow path to the motor and a torquing mechanism driven by the motor, the shutoff mechanism comprising:a valve member movable between a normal open position permitting pressurized airflow to t

1. An automatic shutoff mechanism for a pneumatic torque-applying tool having an air motor, a pressurized airflow path to the motor and a torquing mechanism driven by the motor, the shutoff mechanism comprising:a valve member movable between a normal open position permitting pressurized airflow to the motor and a closed position blocking pressurized airflow to the motor, bias structure resiliently urging the valve member to its normal open position, the valve member having opposite first and second sides such that in the open position only the first side is exposed to pressurized airflow, and a trip apparatus responsive to application of a predetermined torque by the torquing mechanism for moving the valve member to a trip position in the airflow path spaced from the open position sufficiently that the second side of the valve member is exposed to pressurized airflow for driving the valve member from the trip position to the closed position. 2. The shutoff mechanism of claim 1, wherein the trip apparatus includes a mechanical apparatus.3. The shutoff mechanism of claim 2, wherein the trip apparatus includes inertia-responsive apparatus.4. The shutoff mechanism of claim 1, wherein the trip apparatus includes electromechanical apparatus.5. The shutoff mechanism of claim 4, wherein the electromechanical apparatus includes a torque-sensing device and a solenoid coupled to the valve member and actuated by the torque-sensing device when the predetermined torque level is reached for moving the valve member to its trip position.6. The shutoff mechanism of claim 5, wherein the torque-sensing device is disposed adjacent to the valve member.7. The shutoff mechanism of claim 6, wherein the torque-sensing device includes an inertia-responsive device.8. The shutoff mechanism of claim 6, wherein the torque-sensing device is an electromagnetic device.9. The shutoff mechanism of claim 8, wherein the torque-sensing device includes a magnetoelastic torque sensor and a magnetic field vector sensor device.10. An automatic shutoff mechanism for a pneumatic torque-applying tool having an air motor with a rotor shaft and a rotational axis, a pressurized airflow path to the motor and a torquing mechanism driven by the motor, the shutoff mechanism comprising:a valve member movable between a normal open position permitting pressurized airflow to the motor and a closed position blocking pressurized airflow to the motor; bias structure resiliently urging the valve member to its normal open position, the valve member having opposite first and second sides such that in the open position only the first side is exposed to pressurized airflow; and a trip assembly including an inertia member coaxial with the rotor shaft, and a helical coupling assembly between the inertia member and the rotor shaft such that at constant velocity the rotor shaft and the inertia member rotate together, while rapid deceleration of the rotor shaft causes the inertia member to move rotatably and axially relative to the rotor shaft to a position spaced from the valve member by a distance inversely proportional to the torque applied, the trip assembly being responsive to application of a predetermined torque for moving the inertia member into engagement with the valve member to move the valve member to a trip position in the airflow path spaced from the open position sufficiently that the second side of the valve member is exposed to pressurized airflow for driving the valve member from the trip position to the closed position. 11. The shutoff mechanism of claim 10, wherein the helical coupling assembly includes a first helical groove on an inner surface of the inertia member, a coupling member fixed to the rotor shaft and disposed coaxially within the inertia member and having a second helical groove on an external surface thereof, and at least one ball disposed in the first and second grooves for cooperation therewith to accommodate rotational and axial movement of the inertia member relative to the coupling member.12. The shutoff mechanism of claim 11, wherein the trip assembly includes a bias structure for resiliently urging the inertia member to a home position spaced a maximum distance from the valve member.13. The shutoff mechanism of claim 12, wherein the trip assembly includes a clutch mechanism responsive to movement of the inertia member from its home position for preventing return of the inertia member to the home position until after the valve member has been moved to its trip position.14. The shutoff mechanism of claim 13, wherein at least one of the helical grooves has a first axial end disposed adjacent to the home position of the inertia member and a second axial end, wherein the first axial end is disposed further from the rotational axis than the second axial end, the trip assembly including means resiliently urging the at least one ball toward the first end of the at least one of the grooves.15. The shutoff mechanism of claim 14, wherein the trip assembly further includes reset mechanism responsive to movement of the valve member toward its closed position for permitting return of the inertia member to its home position.16. A pneumatic torque-applying tool comprising:an air motor; a structure defining a pressurized airflow path to the motor; torquing mechanism coupled to the motor and driven thereby; and automatic shutoff mechanism including, a valve member movable between a normal open position permitting pressurized airflow to the motor and a closed position blocking pressurized airflow to the motor, bias structure resiliently urging the valve member to its normal open position, the valve member having opposite first and second sides such that in the open position only the first side is exposed to pressurized airflow, and a trip apparatus responsive to application of a predetermined torque by the torquing mechanism for moving the valve member to a trip position in the airflow path spaced from the open position sufficiently that the second side of the valve member is exposed to pressurized airflow for driving the valve member from the trip position to the closed position. 17. The tool of claim 16, wherein the shutoff mechanism is disposed at an end of the air motor opposite the torquing mechanism.18. The tool of claim 16, wherein the torquing mechanism is an impact mechanism, the air motor having a rotational axis, the trip apparatus including an actuation member axially movable between a home position spaced a maximum distance from the valve member and an actuating position engageable with the valve member for moving valve member to its trip position.19. The tool of claim 18, wherein the trip apparatus includes a coupling assembly accommodating movement of the actuation member, in response to each impact of the impact mechanism, from the home position an axial distance proportional the torque applied and then back to the home position, until the valve member is moved to its trip position.20. The tool of claim 18, whereinthe trip apparatus includes a clutch assembly preventing return of the actuation member to its home position between impacts of the impact mechanism. 21. An automatic shutoff mechanism for a pneumatic impact tool having an air motor, a pressurized airflow path to the motor and an impact mechanism driven by the motor, the shutoff mechanism comprising:a valve member movable between a normal open position permitting pressurized airflow to the motor and a closed position blocking pressurized airflow to the motor, bias structure resiliently urging the valve member to its normal open position, and a trip apparatus responsive to application of a predetermined reactive force to the impact mechanism for moving the valve member to a trip position in the airflow path spaced from the open position a distance such that the valve member is exposed to a pressurized air load which drives valve member to the closed position. 22. The shutoff mechanism of claim 21, wherein the trip apparatus includes a torque-responsive mechanism.23. The shutoff mechanism of claim 21, wherein the trip apparatus includes an electromechanical apparatus.24. The shutoff mechanism of claim 23, wherein the trip apparatus includes a reactive force-sensing device and a solenoid coupled to the valve member and actuated in response to the force-sensing device when a predetermined reactive force is reached for moving the valve member to its trip position.25. An automatic shutoff mechanism for a pneumatic tool having an air motor, a pressured air flow path to the motor and output mechanism driven by the motor for applying force to a work piece, the shutoff mechanism comprising:a valve member movable between a normal open position permitting pressurized airflow to the motor and a closed position blocking pressurized airflow to the motor; bias structure resiliently urging the valve member to its normal open position; and a trip assembly responsive to application of a predetermined reactive force to the output mechanism for moving the valve member to a trip position, the trip assembly including a reactive force responsive device responsive to the reactive force on the output mechanism to generate a signal indicative of the reactive force, and an actuator assembly responsive to the signal indicative of the predetermined reactive force level for moving the valve member to a trip position in the airflow path spaced from the open position sufficiently that the valve member is exposed to pressured airflow for driving the valve member from the trip position to the closed position. 26. The shutoff mechanism of claim 25, wherein the output mechanism is a torquing mechanism, the reactive force responsive device being a torque-responsive device.27. The shutoff mechanism of claim 26, wherein the torque-responsive device is disposed adjacent to the valve member.28. The shutoff mechanism of claim 27, wherein the torque-responsive device includes a mechanical device axially movable in response to torque applied.29. The shutoff mechanism of claim 27, wherein, the torque-responsive device is an electromagnetic device.30. The shutoff mechanism of claim 29, wherein the torque-responsive device includes a magnetoelastic device.31. The shutoff mechanism of claim 25, wherein the actuator assembly includes a solenoid.32. The shutoff mechanism of claim 25, wherein the output mechanism is an impact mechanism.