Spark Timing Control for Cold Start Particulate Reduction

The patent applies preliminary action by advancing spark timing before top dead center during cold start conditions to preheat combustion chamber surfaces before fuel injection. This preliminary heating action prevents fuel impingement on cold surfaces that would otherwise generate excessive particulates, while still allowing the catalytic converter to warm up subsequently.

The patent inverts the conventional approach by advancing spark timing instead of retarding it during cold start. Conventional wisdom retards timing to direct heat to the catalytic converter, but this patent does the opposite - it advances timing to direct heat to combustion surfaces first, then transitions to retarded timing once surfaces are heated, thereby eliminating particulate formation while still achieving catalytic light-off.

The patent applies dynamics by implementing a transition strategy where spark timing is advanced during an initial phase to heat combustion surfaces, then dynamically switched to retarded timing once surfaces reach adequate temperature. This dynamic adjustment optimizes the balance between reducing particulates and heating the catalytic converter, minimizing total warm-up time while maintaining low emissions.

The patent uses periodic action by dividing the cold start process into distinct phases: an initial phase with advanced timing for surface heating, followed by a transition phase, and finally a catalytic heating phase with retarded timing. This periodic switching of spark timing strategies ensures both particulate reduction and efficient catalytic converter warming.