Safety device for a tool powered by an electric motor
US4847721A · kind A · utility
13Cited by
7References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1987 |
| Grant date | Jul 11, 1989 |
| Priority date | — |
| Expiry date | Aug 12, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/093
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A safety device for a tool powered by an electric motor. It has a main switch, electronic controls, and a tachometer-generator. In order to provide a device for switching off a motor as a function of motor speed that is simple and economical and that will retain the same nominal switch-off value for the total life of the device, a relay is wired in parallel with the motor and controls the supply of power to the motor through a relay contact.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.