US Patent 7637476 Control system for a gas cooking device

“Control system for a gas cooking device or any other gas device comprising at least one gas burner (1) and, for each gas burner (1), an electromagnetic valve (2) to open or cut off the gas flow to the gas burner (1), said electromagnetic valve (2) comprising magnetic means (10, 11, 12) to keep the gas flow open, and an actuator (3) that is operated manually so that it acts on the magnetic means (10, 11, 12) of the electromagnetic valve (2), thereby opening the gas flow. The control system (20) generates a current signal (I) that circulates through the magnetic means (10, 11, 12) of the electromagnetic valve (2) and detects when the actuator (3) is operated in accordance with the change in magnetic reluctance of said magnetic means (10, 11, 12).”