Electrical safety interlock and pulse-type reset circuit for a vacuum cleaner system
US4993104A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1989 |
| Grant date | Feb 19, 1991 |
| Priority date | — |
| Expiry date | Aug 11, 2009 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA47L9/2857
- WIPO fieldFurniture, games
- WIPO sectorOther fields
Abstract
A safety interlock circuit for a vacuum cleaner system is disclosed for interrupting the flow of current through conductors of a vacuum hose and handle assembly whenever an electrical attachment accessory is disconnected from the handle assembly during operation of the vacuum. A pulse-type reset circuit is also disclosed for re-enabling current flow through the conductors of the vacuum hose and handle assembly after the electrical attachment accessory has been reattached to the handle assembly. The safety interlock circuit of the preferred embodiment comprises a relay coil, a plurality of normally open relay contacts, and a current sensing resistor, all connected in series with an AC power source and a motor of the electrical attachment accessory. A voltage doubler is also connected in parallel with the current sensing resistor for supplying a DC voltage to the relay coil. The safety interlock circuit operates to interrupt current flow by opening the normally open relay contacts whenever the relay coil is de-energized. The pulse-type reset circuit comprises a momentary contact pushbutton reset switch, a plurality of transistors, a capacitor, and a plurality of optical-electrical co…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.