Fuel injection control method for a multi-cylinder internal combustion engine, having a fail safe function for abnormality in cylinder-discriminating means

Claim 1

A method for controlling the injection of fuel into an internal combustion engine having a plurality of cylinders, pistons disposed within respective ones of said cylinders, a crankshaft to which said pistons are connected, crank angle position-detecting means for detecting predetermined positions of said pistons within said respective ones of said cylinders and generating pulses as a first signal indicative of detected predetermined positions of said pistons, and cylinder-discriminating means adapted to generate a pulse as a second signal each time said crankshaft of said engine rotates through a predetermined angle with respect to a predetermined position of one of said pistons within a particular one of said cylinders, wherein fuel is injected into said cylinders in predetermined sequence starting from a fuel injection into said particular one of said cylinders, in synchronism with pulses successively generated from said crank angle position-detecting means immediately after generation of each pulse of said cylinder-discriminating means, the sequence of fuel injections into said cylinders being changed so as to first effect fuel injection into said particular one of said cylinders immediately after generation of a pulse of said second signal and thereafter effect fuel injections into the other cylinders in said predetermined sequence when one of said cylinders which corresponds to a first pulse of said first signal is other than said particular one of said cylinders immediately after generation of said pulse of said second signal, the method comprising the steps of: (1) counting the number of times of said changing of the sequence of fuel injections and comparing the counted number with a predetermined number; (2) regarding said cylinder-discriminating means as abnormal when the counted number reaches the predetermined number; and (3) effecting fuel injections into said cylinders in said predetermined sequence in synchronism with pulses of said first signal alone, irrespective of generation of subsequent pulses of said second signal, when said cylinder-discriminating means is regarded as abnormal in said step (2).

Claim 2

A method for controlling the injection of fuel into an internal combustion engine having a plurality of cylinders, pistons disposed within respective ones of said cylinders, a crankshaft to which said pistons are connected, crank angle position-detecting means for detecting predetermined positions of said pistons within said respective ones of said cylinders and generating pulses as a first signal indicative of detected predetermined positions of said pistons, and cylinder-discriminating means adapted to generate a pulse as a second signal each time said crankshaft of said engine rotates through a predetermined angle with respect to a predetermined position of one of said pistons within a particular one of said cylinders, wherein fuel is injected into said cylinders in predetermined sequence starting from a fuel injection into said particular one of said cylinders, in synchronism with pulses successively generated from said crank angle position-detecting means immediately after generation of each pulse of said cylinder-discriminating means, the sequence of fuel injections into said cylinders being changed so as to first effect fuel injection into said particular one of said cylinders immediately after generation of a pulse of said second signal and thereafter effect fuel injections into the other cylinders in said predetermined sequence when one of said cylinders which corresponds to a first pulse of said first signal is other than said particular one of said cylinders immediately after generation of said pulse of said second signal, the method comprising the steps of: (1) counting the number of times of said changing of the sequence of fuel injections and comparing the counted number with a predetermined number; (2) regarding said cylinder-discriminating means as abnormal when the counted number reaches the predetermined number; and (3) effecting fuel injections into said cylinders in said predetermined sequence in synchronism with pulses of said first signal alone, irrespective of generation of subsequent pulses of said second signal, when said cylinder-discriminating means is regarded as abnormal in said step (2).