Ignition control apparatus for internal combustion engine

In combination with an internal combustion engine having an output shaft rotated by the combustion of mixture, an ignition coil energized by an electric power source, and a spark plug for igniting said fuel mixture, an ignition control system comprising:

• means for producing a first pulse in synchronism with the arrival of said output shaft at a predetermined angular position;
• means for producing a second pulse at every predetermined angular rotation of said output shaft;
• means for detecting engine operating conditions including at least rotation speed of said output shaft;
• means for determining a first rotation value of said output shaft indicative of the timing of ignition relative to said predetermined angular position of said output shaft in response to said engine operating conditions detected by said conditions detecting means;
• means for determining a second rotation value of said output shaft indicative of the period of energization of said ignition coil, said second rotation value being related to said rotation speed of said output shaft detected by said conditions detecting means, said period of energization being increased as said rotational speed of said output shaft decreases below and increases above a predetermined rotation speed;
• means for subtracting said second rotation value from said first rotation value to determine the timing of energization of said ignition coil;
• means for counting the number of said second pulse in response to said first pulse to start energization of said ignition coil when the count value thereof reaches the output value of said subtracting means;
• and
• means for counting the number of said second pulse in response to said first pulse to terminate energization of said ignition coil when the count value thereof reaches said first rotation value.

An ignition control system for an internal combustion engine, said engine having an auxiliary combustion chamber communicating with a main combustion chamber through a passage, and a spark plug having a discharge electrode exposed at an opening of the passage near the main combustion chamber, the energization time period of an ignition coil being related to the engine speed, said ignition control system comprising:

• means for detecting an intake pressure of said engine and producing a signal indicative thereof;
• means for detecting the engine speed and producing a signal indicative thereof, a flow velocity of a fuel mixture in the main combustion chamber in the vicinity of the spark plug being related to said engine speed;
• means for determining ignition timing depending on said detected intake pressure and said engine speed and for producing an ignition timing signal, said ignition timing determining means including;
• a first memory connected to receive said signals indicative of the detected intake pressure and the engine speed, said first memory outputting a value of an ignition advance angle corresponding to said detected intake pressure and engine speed, and
• a first counter for counting down a value obtained by subtracting said value of the ignition advance angle from a predetermined constant, said counter producing said ignition timing signal upon completion of the counting;
• means for determining energization time period depending on the flow velocity of the fuel mixture and for producing an energization timing signal, said energization time period determining means including;
• a second memory connected to receive said signal indicative of the detected engine speed and delivering a programmed value of the energization time period corresponding to said detected engine speed, said programmed value of the energization time period representing the amount of spark ignition energy optimum to the flow velocity of the fuel mixture, said energization time period increasing as the engine speed increases above a predetermined speed, and
• a second counter for counting down a value obtained by subtracting said value of the ignition advance angle and said value of the energization time period from said predetermined constant, said second counter producing said energization timing signal upon completion of the counting;
• and
• means for controlling the energization of said ignition coil, said energization control means commencing the energization of said ignition coil in response to said energization timing signal and cutting off the energization in response to said ignition timing signal.

A method for controlling ignition of a fuel mixture in an internal combustion engine having an output shaft rotated by the combustion of a fuel mixture, an ignition coil energized by an electric power source and a spark plug, said method comprising the steps of:

• generating a speed signal related to the rotational speed of said output shaft;
• detecting at least one engine operating condition;
• determining a flow velocity of the fuel mixture in a combustion chamber in the vicinity of said spark plug;
• producing a timing signal related to the timing of an ignition spark in response to said at least one engine operating condition and said speed signal;
• producing an energization period signal related to the time period said coil is energized in response to said fuel flow velocity;
• and
• controlling the energization of said coil in response to said timing signal and said energization period signal.

A method for controlling ignition of a fuel mixture in an internal combustion engine having an output shaft rotated by the combustion of a fuel mixture, an ignition coil energized by an electric power source and a spark plug, said method comprising the steps of:

• generating a speed signal related to the rotational speed of said output shaft;
• detecting at least one engine operating condition;
• determining a flow velocity of the fuel mixture in a combustion chamber in the vicinity of said spark plug;
• producing a timing signal related to the timing of an ignition spark in response to said at least one engine operating condition and said speed signal;
• producing an energization period signal related to the time period said coil is energized in response to said fuel flow velocity, said energization period signal indicating an increasing energization time period as said fuel flow velocity increases above and decreases below a predetermined fuel flow velocity;
• and
• controlling the energization of said coil in response to said timing signal and said energization period signal.

A method for controlling ignition of a fuel mixture in an internal combustion engine having an output shaft rotated by the combustion of a fuel mixture, an ignition coil energized by an electric power source and a spark plug, said method comprising the steps of:

• generating a speed signal related to the rotational speed of said output shaft;
• detecting the intake pressure of said engine;
• determining a flow velocity of the fuel mixture in a combustion chamber in the vicinity of the said spark plug;
• producing a timing signal related to the timing of an ignition spark in response to said intake pressure and said speed signal;
• producing an energization period signal related to the time period said coil is energized in response to said fuel flow velocity, said energization period signal indicating an increasing energization time period as said fuel flow velocity increases above and decreases below a predetermined fuel flow velocity;
• subtracting said energization period signal from said timing signal to determine the timing of energization of said ignition coil;
• generating a first group of pulses in synchronism with the arrival of said output shaft at a predetermined angular position;
• generating a second group of pulses at every predetermined angular rotation of said output shaft;
• counting the number of said second pulses in response to each of said first pulses to start energization of said ignition coil when the count value thereof reaches the output value of said subtracting step;
• and
• counting the number of said second pulses in response to said first pulse to terminate energization of said ignition coil when the count value thereof reaches the value of said timing signal.