Flame sense circuit and method with analog output
US6985080B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 2003 |
| Grant date | Jan 10, 2006 |
| Priority date | — |
| Expiry date | Dec 11, 2023 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2223/08
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
An analog flame sense circuit is provided that utilizes the flame rectification method of sensing flame. The circuit uses an AC voltage source and discrete components to provide the sensing of the flame current. Either a single-pole or a two-pole filter may be used to smooth the generated sense voltage. A DC bias is provided to the filter to ensure a positive voltage. The circuit also includes a high-gain, high-impedance amplifier to translate the high impedance voltage of the sensing portion of the circuit to a relatively low impedance voltage for use by an electronic control circuit. In one embodiment, a high-gain emitter-follower amplifier constructed from two bi-polar junction transistors (BJTs) is used. An integrated Darlington configuration may be used, as well as a single BJT having a high gain, and an integrated operational amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.