Multicharge implementation to maximize rate of energy delivery to a spark plug gap

An ignition system for an internal combustion engine, comprising:

• a control circuit configured to generate an ignition control signal;
• an ignition coil having a primary winding and a secondary winding, said primary winding including a first end coupled to a power supply;
• a switch connected to a second end of said primary winding and configured to selectively cause a primary current to flow through said primary winding in response to said ignition control signal;
• a sensing circuit coupled to said secondary winding configured to generate a secondary current signal representative of a level of secondary current in said secondary winding;
• said control circuit being configured to cause said switch to interrupt said primary current wherein a secondary current is established in said secondary winding configured to cause a spark plug coupled to said secondary winding to produce a first spark, said control circuit being responsive to said secondary current signal to generate said ignition control signal in preparation of a second spark when said secondary current reaches a secondary current threshold;
• a speed sensor configured to generate a speed signal representative of an operating speed of said engine;
• a temperature sensor configured to generate a temperature signal representative of an ambient temperature proximate the engine;
• said control circuit including a controller having means for determining said secondary current threshold as a function of said speed signal, said temperature signal, and predetermined data stored in a memory associated with said controller.

An ignition system for an internal combustion engine, comprising:

• a control circuit configured to generate an ignition control signal;
• an ignition coil having a primary winding and a secondary winding, said primary winding including a first end coupled to a power supply;
• a switch connected to a second end of said primary winding and configured to selectively cause a primary current to flow through said primary winding in response to said ignition control signal;
• a sensing circuit comprising a resistor coupled to said secondary winding configured to generate a secondary current signal representative of a level of secondary current in said secondary winding;
• said control circuit being configured to cause said switch to interrupt said primary current wherein a secondary current is established in said secondary winding configured to cause a spark plug coupled to said secondary winding to produce a first spark, said control circuit being responsive to said secondary current signal to generate said ignition control signal in preparation of a second spark when said secondary current reaches a secondary current threshold, wherein said control circuit includes a processing circuit having a voltage source responsive to an operating speed of said engine and an ambient temperature and configured to generate a reference signal corresponding to said secondary current threshold.

A method of controlling ignition in an internal combustion engine comprising the steps of:

• (A) determining a secondary current threshold as a function of an engine speed parameter and an ambient temperature parameter;
• (B) charging an ignition coil by establishing a primary current through a primary winding of the coil;
• (C) discharging the ignition coil to produce a first spark by interrupting the primary current to thereby induce a secondary current in a secondary winding of the coil;
• (D) determining a level of the secondary current;
• and,
• (E) discontinuing the discharging of the ignition coil by establishing the primary current when the secondary current level determined in step (D) reaches the secondary current threshold determined in step (A).