Abstract: The powered hand tool for machining includes an enclosed drive motor having a rotor shaft and is provided with at least one interior air duct through which drawn-in cooling air passes to cool the drive motor. To prevent the drive motor from being clogged or damaged by magnetizable dust, which is produced from the machining process among other things, a permanent magnet is nonrotatably attached to the rotor shaft and also located in the air duct or ducts. The invention also resides in an air-cooled drive motor having a cooling-air flow with a permanent magnet located in the vicinity of the cooling-air flow and fixed nonrotatably to the motor shaft.
Type:
Grant
Filed:
December 3, 1990
Date of Patent:
March 24, 1992
Assignee:
Robert Bosch GmbH
Inventors:
Reinhold Strozel, Wilhelm Schwarze, Helmut Stirm