Method and apparatus for controlling combustion quality in lean burn reciprocating engines

A method for analyzing the combustion quality in a lean burn reciprocating engine comprising the steps of:

• receiving a succession of ionization signals of the lean burn reciprocating engine for successive cycles of a running engine;
• processing a plurality of related ionization signals for signal stability;
• identifying, using an initial current level for all of the signals, an ionization signal starting point and a peak for the ionization signal;
• associating a geometric parameter with the ionization signal which relates the ionization signal starting point to the peak for the ionization signal;
• comparing the geometric parameter against a reference geometric parameter related to a desired combustion quality for an air/fuel ratio relating to λ greater than 1.4;
• and
• providing an indication of combustion quality.

A system for controlling the combustion quality in a lean burn reciprocating engine comprising:

• means for receiving a succession of ionization signals of the lean burn reciprocating engine for successive cycles of a running engine;
• means for processing a plurality of related ionization signals for signal stability;
• means for identifying, using an initial current level for all of the signals, an ionization signal starting point and a peak for the ionization signal;
• means for associating a geometric parameter with the ionization signal which relates the ionization signal starting point to the peak for the ionization signal;
• comparing the geometric parameter against a reference geometric parameter related to a desired combustion quality relating to λ greater than 1.4;
• and
• means for outputting an indication of combustion quality.

A method for analyzing the combustion quality in a lean burn reciprocating engine comprising the steps of:

• receiving a succession of ionization signals of the lean burn reciprocating engine for successive cycles of a running engine;
• for each ionization signal of the succession of ionization signals:
• measuring the variation of the ionization signal with respect to an engine parameter of the lean burn reciprocating engine;
• associating a floating bounded space with the ionization signal such that the floating bounded space captures a characteristic of the ionization signal which distinguishes an abnormal combustion condition from a normal combustion condition for an engine operating with an air to fuel ratio corresponding to a λ greater than 1.4;
• determining if a portion of the ionization signal is within the floating bounded space;
• providing an indication that an abnormal combustion condition has been detected if the portion of the ionization signal is within the floating bounded space;
• processing a plurality of related ionization signals for signal stability;
• identifying, using an initial current level for all of the signals, an ionization signal starting point and a peak for the ionization signal;
• associating a geometric parameter with the ionization signal which relates the ionization signal starting point to the peak for the ionization signal;
• comparing the geometric parameter against a reference geometric parameter related to a desired air/fuel ratio relating to λ greater than 1.4;
• and
• providing an indication of combustion quality.

A method for analyzing the combustion quality in a cylinder of a lean burn reciprocating engine comprising the steps of:

• determining a peak pressure location of the cylinder for successive cycles of a running engine;
• receiving a succession of ionization signals of the lean burn reciprocating engine for the successive cycles;
• processing a plurality of related ionization signals for signal stability;
• identifying, using an initial current level for all of the signals, an ionization signal starting point of the ionization signal and a peak for the ionization signal;
• associating a geometric parameter with the ionization signal which relates the ionization signal starting point to the peak for the ionization signal;
• comparing the geometric parameter against a reference geometric parameter related to the peak pressure location for an air/fuel ratio relating to λ greater than 1.4;
• and
• providing an indication of combustion quality.

A method for controlling the combustion quality in a cylinder of a lean burn reciprocating engine comprising the steps of:

• determining a peak pressure location of the cylinder for successive cycles of a running engine for an air/fuel ratio relating to λ greater than 1.4;
• receiving a succession of ionization signals of the lean burn reciprocating engine for the successive cycles;
• processing a plurality of related ionization signals for signal stability;
• identifying, using an initial current level for all of the signals, a start point of the ionization signal and a peak for the ionization signal;
• associating a geometric parameter with the ionization signal which relates the start point of the ionization signal to the peak for the ionization signal;
• comparing the geometric parameter against a reference geometric parameter related to a fifty percent burn rate point;
• and
• adjusting a control parameter of the engine such that an error difference between the geometric parameter and the reference geometric parameter is minimized.