Premixed charge compression ignition engine with optimal combustion control

A method for operating a premixed charge, compression ignition engine, the engine having a cylinder and a piston moveable in the cylinder, and the method comprising the steps of:

• providing in the cylinder a gaseous medium containing oxygen;
• forming a combustible mixture by mixing generally homogeneously into the gaseous medium a first fuel that tends to autoignite relatively less readily and a second fuel that tends to autoignite relatively more readily;
• compressing the combustible mixture with the piston until combustion starts, wherein combustion starts at multiple ignition sites distributed throughout the combustible mixture after a delay in a timing of the start of combustion determined by a ratio of the first fuel to the second fuel;
• and
• controlling the timing of the start of combustion by varying the ratio of the amount of the first fuel to the amount of the second fuel.

An engine comprising;

• an engine body with at least one cylinder;
• a piston slidably positioned in each said at least one cylinder, and being movable between a bottom dead center position and a top dead center position;
• a liquid fuel supply valve attached to said engine body;
• a gaseous fuel supply valve attached to said engine body;
• an electronic control unit in control communication with said liquid fuel supply valve and said gaseous fuel supply valve, and being operable to actuate said liquid fuel supply valve when said piston is approximately between 180 degrees and 60 degrees before the top dead center position.

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 delivering intake air, including at least one of air and a mixture of air and fuel, to said combustion chamber;
• combustion control system for controlling combustion events to reduce emissions, said combustion history control system including a mixture autoignition property control system for varying an autoignition property of the mixture, said mixture autoignition property control system including a first fuel supply for supplying a first fuel to the engine and a second fuel supply connected to at least one of said intake air system and said combustion chamber for supplying a second fuel to the engine, said first fuel having a first autoignition property and said second fuel having a second autoignition property different from said first autoignition property;
• and
• a processor adapted to control an amount of said second fuel delivered to said at least one of said intake air system and said combustion chamber.

A method for operating a homogeneous charge, compression ignition engine, the engine having a cylinder and a piston moveable in the cylinder, and the method comprising the steps of:

• providing in the cylinder a gaseous medium containing oxygen;
• forming a combustible mixture by mixing generally homogeneously into the gaseous medium a first fluid fuel that is relatively difficult to ignite and a second fluid fuel that is relatively easy to ignite;
• and
• compressing the combustible mixture with the piston until combustion starts generally simultaneously at a plurality of locations distributed throughout the combustible mixture after an ignition delay determined by the proportion of the first fuel to the second fuel.

A method for operating a homogenous charge, compression ignition engine, the engine having a cylinder and a piston moveable in the cylinder, and the method comprising the steps of:

• providing in the cylinder a gaseous medium containing oxygen;
• forming a combustible mixture by mixing generally homogeneously into the gaseous medium a first fluid fuel that is relatively difficult to ignite and a second fluid fuel that is relatively easy to ignite;
• compressing the combustible mixture with the piston until combustion starts generally simultaneously at a plurality of locations distributed throughout the combustible mixture after an ignition delay determined by the proportion of the first fuel to the second fuel;
• and
• wherein the ignition delay begins when the piston is at a predetermined rotational position relative to top dead center and wherein the method further comprises the step of controlling the ignition delay by varying the ratio of the amount of the first fuel to the amount of the second fuel.

An engine comprising;

• an engine housing with at east one cylinder;
• a piston slidably positioned in each said at least one cylinder, and being movable between a bottom dead center position and a top dead center position;
• a liquid fuel supply valve attached to said engine housing;
• a gaseous fuel supply valve attached to said engine housing;
• a controller in control communication with said fuel injector and said gaseous fuel supply valve, and being operable to actuate said fuel injector when said piston is closer to said bottom dead center position than said top dead center position.