With incomplete combustion prevention device open type gas burning appliances

摘要

PURPOSE: To avoid an erroneous operation in view of safety caused by difference in use of environment of an open type gas burner by a method wherein a combustion time is changed in response to a result of discrimination of an output varying gradient caused by variation in combustion state and the combustion is stopped or terminated after elapsing of the changing time. ;CONSTITUTION: A primary thermocouple 58 is arranged near a gas burner and a secondary thermocouple 60 is arranged near a heat exchanger. The sum of the electromotive forces of the primary thermocouple 58 and the secondary thermocouple 60 is sent to a thermoelectromotive force level discriminating circuit 70 and a gradient varied in response to time of a sensor output value is discriminated by a sensor output gradient discriminating circuit 72 in reference to the resulting electromotive force value. Then, a time is counted by a timer driving circuit 76 in response to the result of this discrimination and whether or not the combustion is continued is discriminated by a combustion continuation available or non-available discriminating circuit. And this is further discriminated by the combustion continuation available or non-available discriminating circuit. In the case that it is discriminated at the combustion continuation available or non-available discriminating circuit that the combustion time does not reach the continuous combustion time discriminated, a gas solenoid valve driving circuit 80 is driven so as to shut off a gas solenoid valve (a magnet safety valve) 36.;COPYRIGHT: (C)1996,JPO