Power tool switch including speed control
US4179644A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 10, 1978 |
| Grant date | Dec 18, 1979 |
| Priority date | — |
| Expiry date | Jan 10, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S388/937
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A double pole, trigger actuated switch employs a bridge contact and a separate contactor for opening and closing both lines from a source of current to an associated power tool. The bridge contact is always closed first and opened last with respect to the contactor so that the former is not subjected to arcing and may be made smaller and less expensively than the latter. The contactor is of the fast closing type constructed to minimize arcing. A speed control circuit is associated with the contactor. The entire switch, including the speed control circuit, is provided in a compact housing for mounting in small portable hand tools such as electric drills. A heat sink is exposed to the ambient air by virtue of louvers in the switch housing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.