Ignition timing control system

In an ignition timing control system for use with an internal combustion engine including the combination of a plurality of combustion cylinders, a spark plug associated with each cylinder for producing combustion of fuel in said cylinder, a crankshaft coupled with each of said cylinders, and a source of electrical power for providing ignition signals to said spark plugs, the improvement comprising:

• first means for generating a plurality of first reference signals having fixed timing and being respectively associated with fixed ignition timing of the combustion in said cylinders;
• second means for generating a plurality of second reference signals having variable timing and being respectively associated with variable ignition timing of combustion in said cylinders;
• means for sensing the speed of said crankshaft, and for producing a timing control signal having a frequency proportional to the sensed speed;
• and,
• means for producing trigger signals for triggering said power source to provide said ignition signals, said producing means including means responsive to said speed sensing means for outputting said trigger signals in accordance with the timing of said first reference signals only when the speed sensed by said speed sensing means is less than a prescribed value and for outputting said trigger signals in accordance with the timing of said second reference signals only when the speed sensed by said speed sensing means is at least as great as said prescribed value;
• said producing means including an electrically controllable switch having an output for outputting said trigger signals and first and second inputs for controlling the operation of said output, said first input being coupled with said first generating means for receiving said first reference signals, said second input being coupled with said second generating means for receiving said reference signals;
• and
• means for multiplying the frequency of said control signal and means for converting the multiplied frequency of said control signal to a voltage, said converting means including means for outputting an electrical signal when said voltage exceeds a prescribed value, said switch having a third input for receiving said electrical signal from said converting means, the timing of the trigger signals output from said switch being determined by the state of said electrical signal output from said converting means.

An ignition timing control system for an internal combustion engine having a plurality of combustion cylinders and a crankshaft coupled with each of the cylinders, comprising:

• means for generating reference signals associated with the ignition timing in said cylinders, said reference signals corresponding to an advanced state of ignition timing;
• means for sensing incremental rotation of said crankshaft and for producing timing control signals in accordance with the sensed incremental rotation of said crankshaft, said means for sensing, including means for multiplying the frequency of said timing control signals and means for converting the frequency of said timing control signals to a voltage proportional to said frequency;
• means coupled with said generating means and said sensing means for generating a plurality of multi bit data words using said reference signals and said timing control signals, said data words representing instantaneous rotational positions of said crankshaft;
• means for converting said data words to analog signals in accordance with a preselected ignition advance schedule;
• means for comparing the magnitude of said analog signals with the magnitude of said timing control signals for outputting timing signals when the magnitude of said analog signals is at least as great as the magnitude of said timing control signals;
• and,
• means for producing ignition trigger signals for initiating combustion in said cylinders, including means outputting said trigger signals in accordance with the timing of said first reference signal only when the rotational speed of said crankshaft is less than a prescribed value and for outputting said trigger signals in accordance with the timing of said timing signals output from said comparing means only when the rotational speed of said crankshaft is at least as great as said prescribed value.

An ignition timing control system for an internal combustion engine having a plurality of combustion cylinders and a crankshaft coupled with each of the cylinders, comprising:

• means for generating reference signals associated with the ignition timing in said cylinders, said reference signals corresponding to an advanced state of ignition timing;
• means for sensing incremental rotation of said crankshaft and for producing timing control signals in accordance with the sensed incremental rotation of said crankshaft;
• means coupled with said generating means and said sensing means for generating a plurality of multi bit data words using said reference signals and said timing control signals, said data words representing instantaneous rotational positions of said crankshaft;
• means for converting said data words to analog signals in accordance with a preselected ignition advance schedule;
• means for comparing the magnitude of said analog signals with the magnitude of said timing control signals and for outputting timing signals when the magnitude of said analog signals is at least as great as the magnitude of said timing control signals;
• and,
• means for producing ignition trigger signals for initiating combustion in said cylinders, including means outputting said trigger signals in accordance with the timing of said first reference signal only when the rotational speed of said crankshaft is less than a prescribed value and for outputting said trigger signals in accordance with the timing of said timing signals output from said comparing means only when the rotational speed of said crankshaft is at least as great as said prescribed value;
• said converting means including a demultiplexer;
• and
• said means for generating said multi-bit data word including a phase-locked loop and a programmable counter coupled with said phase-locked loop.