Electrically driven screw-driver
OwnerKatsuyuki Totsuinventor
Life of this patent
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Abstract
An electrically driven screw-driver is disclosed in which a ratchet device is mounted to a portion of a chucking shaft to which a driver bit is detachably connected and the chucking shaft is connected to an output shaft of an electric motor through a planetary reduction system and in which a torque controlling mechanism having a clutch function is mounted to the planetary reduction system. In accordance with the electrically driven screw-driver, a combination of the ratchet device and the torque controlling mechanism permits the screw-driver to be operated in such a way that only the prefastening, or screwing step may be carried out mechanically and electrically while the finishing step of strong fastening may be performed manually, resulting in a very compact and light screw-driver which is very convenient in portability.
Claims8
An electrically driven screw-driver comprising a ratchet device mounted to a portion of a chucking shaft to which a driver bit is detachably connected, said chucking shaft being connected to the output shaft of an electric motor through a planetary reduction system, said planetary reduction system comprising a plurality of planetary gears each capable to self-rotating and revolving around a pinion gear of a power transmission connected to the output shaft of the electric motor, and having an internal gear ring coacting with the planetary gears providing an orbit for their revolution, a cylindrical casing for rotatably receiving the internal gear and a torque controlling mechanism having a clutch function mounted between said casing and the planetary reduction system, said torque controlling mechanism comprising a steel ball contacting an outer circumferencial surface of the internal gear and means for pressing the steel ball against the internal gear with a predetermined pressure.
Dependencies are inferred from the claim text.