Premixed charge compression ignition engine with optimal combustion control

A premixed charge compression ignition internal combustion engine, comprising:

• an engine body;
• a combustion chamber formed in the engine body;
• an intake air system for supplying intake air, including at least one of air and a mixture of air and fuel, to said combustion chamber;
• an exhaust system for directing exhaust gas from said combustion chamber, said exhaust system including an exhaust port associated with said combustion chamber and formed in said engine body, and an exhaust valve operable to open and close said exhaust port in timed relation to a combustion event;
• combustion history control system for controlling a combustion history of future combustion events in said combustion chamber to optimize engine operation, said combustion history control system including a temperature control system for ultimately varying the temperature of the mixture of fuel and air, said temperature control system including a residual mass fraction control system for varying a residual mass fraction of combustion products in said combustion chamber, said residual mass fraction control system including a variable exhaust valve timing control means associated with said combustion chamber for controlling a time duration during which said exhaust valve is open during an intake stroke of the engine based on engine operating conditions so as to cause exhaust gas to flow from said exhaust port into said combustion chamber to increase an amount of residual exhaust gas in said combustion chamber after a combustion event so as to optimize engine operation.

A premixed charge compression ignition internal combustion engine, comprising:

• an engine body;
• a plurality of cylinders formed in the engine body;
• a respective piston mounted in each of said plurality of cylinders for reciprocal movement through successive exhaust and intake strokes, each respective piston defining a combustion chamber for containing a mixture of fuel and air;
• an intake air system for supplying intake air to said plurality of cylinders;
• an exhaust system for directing exhaust gas from said plurality of cylinders;
• combustion history control system for controlling a combustion history of future combustion events in said combustion chamber of each of said plurality of cylinders to optimize engine operation, said combustion history control system including a temperature control system for ultimately varying the temperature of the mixture of fuel and air, said temperature control system including a residual mass fraction control system for varying a residual mass fraction of combustion products in said combustion chamber, said residual mass fraction control system including a throttle valve positioned in said exhaust system to limit exhaust gas flow thereby increasing the residual mass fraction of combustion products;
• and
• a processor for controlling said throttle valve based on engine operating conditions to optimize combustion.

A method for controlling a timing of combustion of future combustion events in a combustion chamber of an internal combustion engine using a timing of combustion control system, the engine operable in a premixed charge compression ignition mode during which the engine is capable of operating in a stable mode wherein a combustion timing will return to a steady state timing value upon the occurrence of a perturbation without the use of the timing of combustion control system permitting continuous stable engine operation and capable of operation in an unstable mode wherein the combustion timing one of advances and retards upon the occurrence of a perturbation without returning to the steady state timing value potentially causing termination of engine operation unless the timing of combustion control system is used, comprising:

• providing the timing of combustion control system for advancing and retarding the timing of combustion of future combustion events in the combustion chamber, said combustion history control system including at least one of a temperature control system for ultimately varying the temperature of a mixture of fuel and air for combustion in the combustion chamber, a pressure control system for ultimately varying the pressure of the mixture, an equivalence ratio control system for varying an equivalence ratio of the mixture and a mixture autoignition property control system for varying an autoignition property of the mixture;
• operating the engine with the timing of combustion retarded sufficiently to cause engine operation in the unstable mode;
• controlling at least one of said temperature control system, said pressure control system, said equivalence ratio control system and said mixture autoignition property control system while the engine is operating in the unstable mode to compensate for the perturbations to cause timing of combustion to remain at approximately the steady state timing value thereby maintaining steady engine operation in the unstable mode.