Control circuit for a power tool
US4066942A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 1975 |
| Grant date | Jan 3, 1978 |
| Priority date | — |
| Expiry date | Oct 10, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05D17/02
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
This disclosure deals with a control circuit for a tool including a motor for turning a rotatable power output shaft of the tool. A torque measuring device is coupled to the shaft and generates a signal which is a function of the torque output. The control circuit responds to the torque output and to a reference signal representing a preselected torque, and automatically turns off the motor when the torque output reaches the preselected torque. Further, the control circuit may cyclically turn the tool on and off at very short time intervals as the preselected torque value is being approached, in order to reduce the reaction torque felt by an operator of the tool. In addition, the lengths of the on times in successive cycles may be gradually decreased as the torque output level increases, with the result that the average reaction torque remains substantially constant even though the peak torque output increases.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.