High resolution electronic ignition control system

An electronic ignition system for controlling as a function of a selected engine parameter the ignition instant of an internal combustion engine having at least one cylinder and a piston disposed therein and coupled to a rotatable shaft of the engine to define a first reference position with respect to the crankshaft, the ignition instant occurring upon the termination of an arc of crankshaft rotation at a second variable position with respect to said first reference position, the arc of crankshaft rotation being initiated at a third reference position fixedly disposed before said first reference position considering the rotational direction of the crankshaft, said electronic ignition system comprising:

• (a) means responsive to crankshaft rotation for providing a first train of signals of a first frequency, each signal occurring in time when the crankshaft rotates past its third reference position;
• (b) means responsive to crankshaft rotation for providing a second train of signals of a second frequency greater than said first frequency and proportional to the speed of angular rotation of the crankshaft;
• (c) closed loop circuit means comprising comparison means coupled to receive said second train of signals for providing an error signal, oscillator means for providing a corrected, third train of signals of a third frequency greater than said second frequency and proportional to the magnitude of said error signal, and feedback means for coupling said third train of signals to said comparison means, whereby said comparison means provides said error signal as a function of the phase difference between the signals of said first and third trains of signals;
• and
• (d) counter means coupled to receive said first and third trains of signals and actuated upon the occurrence of each signal of said first train for incrementing a preset count indicative of the ignition instant for each signal of said third train, whereby upon the incrementing of said preset count to a predetermined magnitude, said counter means outputs a firing signal at the ignition instant.

An electronic ignition system for controlling the ignition instant of an internal combustion engine as a function of the rotational speed of the engine crankshaft, the internal combustion engine having at least one cylinder and a piston disposed therein and coupled to the crankshaft to define a first reference position with respect to the crankshaft, the ignition instant occurring upon the termination of an arc of crankshaft rotation at a second variable position with respect to said first reference position, the arc of crankshaft rotation being initiated at a third reference position fixedly disposed before said first reference position considering the rotational direction of the crankshaft, said electronic ignition system comprising:

• (a) means responsive to crankshaft rotation for providing a first train of signals of a first frequency,
• each signal occurring in time when the crankshaft rotates past its third reference position;
• (b) means responsive to crankshaft rotation for providing a second train of signals of a second frequency greater that said first frequency and proportional to the rotational speed of the crankshaft;
• (c) first counter means coupled to receive the first and second trains of signals and actuated upon the occurrence of each signal of said first train for incrementing a preentered count upon the occurrence of each signal of said second train, whereby when said preentered count is counted to a predetermined magnitude said first counting means outputs at the ignition instant a cylinder firing signal;
• (d) second counter means for counting said second train of signals for a predetermined interval to provide a count indicative of the rotational speed of the crankshaft;
• and
• (e) addressable memory means for storing a plurality of said preentered counts, each preentered count corresponding to a value of said first variable position empirically determined for a particular engine to achieve a maximum mean torque output from the engine for a corresponding value of the rotational speed of the crankshaft, said addressable memory means being addressed by the count of said second counter means to access and load the addressed preentered count corresponding to said second variable position into said first counter means.

An electronic ignition system for controlling as a function of a selected engine parameter, the ignition instant of an internal combustion engine having at least one cylinder, and a piston disposed therein and coupled to a rotatable crankshaft of the engine to define a first reference position with respect to the crankshaft, the ignition instant occurring upon the termination of an arc of crankshaft rotation at a second variable position with respect to said first reference position, the arc of crankshaft rotation being initiated at a third reference position fixedly disposed before said first reference position considering the rotational direction of the crankshaft, said electronic ignition system comprising;

• (a) means responsive to the crankshaft rotation for providing a first train of signals of a first frequency, each signal occurring in time when the crankshaft rotates past its third reference position;
• (b) means responsive to crankshaft rotation for providing a second train of signals of a second frequency greater than said first frequency and proportional to the rotational speed of the crankshaft;
• (c) integrator means for intergrating said second train of signals to provide a signal indicative of the rotational speed of the crankshaft;
• and
• (d) a closed loop circuit means comprising comparison means coupled to receive said first train of signals for providing an error signal, oscillator means coupled to receive said error signal and to said crankshaft speed signal for providing a corrected, third train of signals of a frequency proportional to the rotational speed of the crankshaft, and feedback means for coupling said output signal to said comparison means whereby said comparison means provides said error signal as the phase difference of the signals of the first and third train of signals.

An electronic ignition system for controlling with a high degree of resolution the ignition instant of an internal combustion engine as a function of a selected engine parameter, said internal combustion engine having at least one cylinder, a piston disposed within the cylinder, and a rotatable crankshaft coupled to the piston to be rotatably driven as combustions occur within the cylinder, the crankshaft having at least one reference position defining the positional relationship of said crankshaft to the cylinder, the crankshaft having a second reference position disposed a fixed angular distance before said first reference position considering the rotational direction of the crankshaft, said ignition instant intended to occur upon the termination of a variable crankshaft arc beginning at said second reference position, said crankshaft arc determined as a function of the selected engine parameter, said electronic ignition system comprising:

• (a) rotor means coupled to rotate with the crankshaft and having at least one first reference indicium and a plurality of second reference indicia thereon for each first reference indicium, said first reference indicium positionally related to said second reference position, said second reference indicia being spaced from each other by substantially equal first angles of crankshaft rotation;
• (b) first and second signal generating means disposed at a point fixed in relation to the rotation of the crankshaft for providing respectively a first train of signals and a second train of signals of a second frequency, each first signal occurring in time when said first reference indicium rotates past said fixed point, each second signal occurring in time when each of said second reference indicia rotates past said fixed point;
• (c) multiplying means coupled to receive said second train of signals for providing a third train of signals of a third frequency greater than said second frequency, said third frequency being such that consecutive signals of said third train define second angles of crankshaft rotation smaller than said first angles;
• and
• (d) arc termination means initiated in response to said first signal for measuring said variable crankshaft arc in response to said third train of signals to produce an ignition signal when said measured crankshaft arc equals the variable crankshaft arc set as a function of said selected engine parameter with a degree of resolution corresponding to said relatively small second angles.