Electronic distribution backup apparatus

Claim 1

An electric distribution backup apparatus comprising an electronic distributor for sequentially distributing an ignition signal to each of a plurality of igniters disposed so as to correspond to respective ones of a plurality of cylinders of an engine on the basis of a reference position signal for each of said cylinders generated by a revolution sensor in accordance with the revolution of said engine and on the basis of a rotating angle signal generated by said revolution sensor, the improvement comprising: an auxiliary revolution sensor for detecting another reference position signal of each of said cylinders when said revolution sensor for generating said two signals is out of order; control means for outputting a failure judging signal in response to detection of the failure of said revolution sensor on the basis of the two signals from revolution sensor, for outputting an auxiliary reference cylinder signal on the basis of a signal from said auxiliary revolution sensor, for outputting a clock signal in place of said rotating angle signal, and for outputting an ignition backup signal; and a pseudo reference position signal generator for generating a pseudo reference position signal in place of said reference position signal on the basis of said auxiliary reference cylinder signal; wherein said clock signal, said pseudo reference position signal, and said ignition backup signal are input to said electronic distributor, when said revolution sensor is out of order so that each of said igniters is ignited sequentially.