Power screwdriver
AssigneeC. & E. Fein GmbH
InventorsThomas Scholl, Oliver Greese
Life of this patent
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Abstract
A power screwdriver is disclosed having a drive which is coupled via a clutch, disengaging as a function of torque, to a tool drive shaft for driving a tool. The screwdriver comprises an electronic control unit for controlling the drive, and a sensor which is coupled to the electronic control unit in order to switch off the drive when the clutch responds. The electronic control unit is designed for activating the drive with a certain output, preferably with a reduced output, for a limited time after switch-off.
Claims19
A power screwdriver comprising:
- a drive;
- a tool drive shaft for driving a tool;
- a clutch, releasing when a certain preset torque is reached, having an input side being coupled to said drive and having an output side being coupled to said tool drive shaft;
- a sensor being coupled to said clutch for sensing a release of said clutch;
- an angle sensor for sensing a rotation angle of said tool drive shaft;
- brake means for braking said drive after release of said clutch;
- and
- an electronic control for controlling said drive, said electronic control being coupled to said sensor for deactivating said drive when said clutch releases, and wherein said electronic control is coupled to said angle sensor for switching on said drive again upon reaching a first rotation angle after release of said clutch and for switching off said drive again upon reaching a second rotation angle after release of said clutch.
A power screwdriver comprising:
- a drive;
- a tool drive shaft for driving a tool;
- a clutch, releasing when a certain preset torque is reached, having an input side being coupled to said drive and having an output side being coupled to said tool drive shaft;
- a sensor being coupled to said clutch for sensing a release of said clutch;
- and an electronic control for controlling said drive, said electronic control being coupled to said sensor for deactivating said drive when said clutch releases, wherein said electronic control is configured for reactivating said drive with a certain output for a limited time after deactivation of said drive.
A method of controlling a power screwdriver for tightening a screw connection with a certain tightening torque, comprising the following steps:
- providing a clutch between a drive and a tool drive shaft for driving a tool, said clutch being releasable as a function of torque;
- driving said tool drive shaft via said clutch;
- monitoring said clutch for release;
- switching off said drive when said clutch releases;
- braking said drive;
- switching on said drive again for subsequently driving said clutch for a limited time period;
- and
- switching off said drive again according to a predetermined switch-off criterion.
Dependencies are inferred from the claim text.