Portable electric tool with variable torque

US4758754A · kind A · utility

Assignee

• C. & E. FEIN GMBH · DE

Inventors

• Manfred Fink · Weinsberg, DE
• Klaus M. Junginger · Rastatt, DE
• Wolfgang Schreiber · Stuttgart, DE

Key dates

• Filing date: Jan 30, 1987
• Grant date: Jul 19, 1988
• Expiry date: Jan 30, 2007

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B25B23/147
• WIPO field: Machine tools
• WIPO sector: Mechanical engineering

Abstract

In motor-operated machines, especially portable electric tools, it is essential to prevent an impermissibly high torque on the driveshaft or operating spindle. This is attained by means of a torque-disengagement mechanism. An especially elegant, compact, precisely responsive torque-disengagement mechanism is attained by mounting one of the two bearings for a driveshaft in the machine housing or similar structure in such a way that it can move across the longitudinal axis or radially far enough to initiate a switching procedure. The bearing is secured in an initial position by means of an opposing force. The position represents both the zero position for the switching procedure and the correct position of the axis of the driveshaft during operation. If the machine includes a means of varying the torque, the power of the opposing force can be adjusted and maintained either continuously or discontinuously. The opposing force is generated in a practical way by a spring, specifically either by a compact but still powrful stack of cup springs or by a torque rod, both requiring little space.