Torque control circuit for electrical motor
US7936140B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 9, 2008 |
| Grant date | May 3, 2011 |
| Priority date | — |
| Expiry date | Jul 17, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P7/295
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The torque control circuit of a hand tool contains a motor driving circuit, a current detection circuit, a reference voltage generation circuit, a current limiting circuit, and a torque configuration circuit. In the last stage of operation of the hand tool and when the average current has reached a predetermined level, the average current is maintained for a period of time to provide a constant average power and therefore to achieve an appropriate tightness of the bolt or nut being operated. The detection and control of current is achieved by a linear circuit which is robust to the heavy noises produced by the motor. A microprocessor is adopted to consider factors such as temperature in determining a suitable current level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.