| 摘要 |
<p>A burner controller (10) for safe operation of a furnace has a an electromechanical latch (34) for holding first and second fuel valves (41, 42) open responsive to an enable signal. The latch comprises an armature (32) attached to the second valve (42) and an electromagnet assembly (33) attached to the first valve (41). When the electromagnet assembly (33) receives the enable signal and the armature (32) is attracted to the electromagnet assembly (33), the magnetic force opposes force of a spring (27) urging the first and second valve (41, 42) simultaneously closed. When the enable signal is not present, the spring forces (27) both valves (41, 42) into their closed position. An auxiliary valve (58) in series flow arrangement with the second valve (42) opposes flow of fuel passing through the second valve (42) in certain situations.</p> |
