Method and apparatus for detecting abnormal combustion conditions in lean burn reciprocating engines

A method of identifying abnormal combustion cycles in a lean burn reciprocating engine, the abnormal combustion cycles being characterized by an abnormal event, the method comprising the steps of:

• a) collecting ionization signals relating ionization current to engine rotational position for a plurality of successive combustion cycles of the lean burn reciprocating engine, some of the combustion cycles being normal, and others of the combustion cycles being characterized by the abnormal event;
• b) identifying a characteristic of the ionization signal for the abnormal combustion cycles which distinguishes from the ionization signal for the normal combustion cycles;
• c) associating at least one floating bounded space with the ionization signals and adjusting the position and size of the floating bounded space so that the floating bounded space captures the characteristic which distinguishes the abnormal combustion cycles;
• and
• d) testing subsequently generated ionization signals with the floating bounded space to distinguish between normal and abnormal combustion cycles of the lean burn reciprocating engine.

A method to detect an abnormal combustion condition of a lean burn reciprocating engine comprising the steps of:

• associating a floating bounded space with an ionization signal such that the floating bounded space captures a characteristic of the ionization signal which distinguishes the 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;
• detecting the variation of an ionization signal with respect to an engine parameter over a combustion event;
• and
• providing an indication that the abnormal combustion condition has been detected if a portion of the ionization signal falls within the floating bounded space.

A method to detect an abnormal combustion condition of a lean burn reciprocating engine comprising the steps of:

• associating a floating bounded space with an ionization signal such that the floating bounded space captures a characteristic of the ionization signal which distinguishes the 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;
• detecting the variation of an ionization signal with respect to an engine parameter over a combustion event;
• detecting if a portion of the ionization signal falls within the floating bounded space;
• and
• adjusting at least one combustion parameter if the portion of the ionization signal falls within the floating bounded space.

An electronic system for detecting an abnormal combustion condition of a lean burn reciprocating engine comprising:

• an ionization signal detector for detecting an ionization signal that changes with respect to an engine parameter over a combustion event of the lean burn reciprocating engine operating with an air to fuel ratio corresponding to a λ greater than 1.4;
• an ionization signal analyzer which detects the variation of the ionization signal and determines if a portion of the ionization signal is within a floating bounded space that is associated with the ionization signal, the ionization signal analyzer in communication with the ionization signal detector;
• and
• an ionization signal control module communication with the ionization signal analyzer and the ionization signal detector, the ionization signal control module providing an indication that the abnormal combustion condition has been detected if the ionization signal analyzer determines if the portion of the ionization signal is within the floating bounded space.