Control apparatus for internal combustion engines

A combustion control apparatus for an internal combustion engine having a plurality of cylinders and means for generating a timing signal relating to the timing of firing of combustion in said cylinders, comprising:

• a plurality of combustion flame optical sensors, each associated with a respective cylinder, for detecting firing of combustion in said cylinders;
• a plurality of optical fiber cables, each connected to a respective one of said combustion flame optical sensors;
• an optical signal processing circuit connected to all of said optical fiber cables to produce an output signal having a series of pulses each corresponding to an optical signal of a respective optical sensor;
• detecting means responsive to said timing signal and said output signal of said optical signal processing unit for detecting a condition of combustion in said cylinders on the basis of said series of pulses;
• and
• means for controlling at least one of fuel air ratio and ignition timing in said internal combustion engine using detected conditions of combustion in said cylinders.

A combustion control apparatus for an internal combustion engine having a plurality of cylinders, comprising:

• a combustion flame optical sensor, associated with a cylinder for detecting firing combustion in said cylinder, said optical sensor having a non-linear characteristic;
• optical signal processing means connected to said optical sensor for converting an optical output thereof to an electrical signal output;
• linear processing means connected to said optical signal processing means for linearizing said electrical signal output thereof;
• and
• means for controlling at least one of fuel air ratio and ignition timing in said internal combustion engine using an output of said linear processing means.

A method of controlling fuel air ratio and ignition timing in an internal combustion engine so as to maintain values of fuel air ratio and ignition timing within a target range in which combustion is stable and NOx concentration is tolerable, comprising the steps of:

• (a) detecting a misfiring state of said engine;
• (b) detecting NOx concentration information of said engine;
• and
• (c) adjusting the value of at least one of fuel air ratio and ignition timing so that both fuel air ratio and ignition timing fall within a target range defined by a misfire boundary and a predetermined NOx concentration boundary.

A method of detecting misfire of an internal combustion engine, comprising the steps of:

• detecting combustion light intensity in respective combustion chambers of the engine;
• converting the detected combustion light intensity of a combustion chamber into an electrical signal corresponding to a measure of the detected combustion light intensity;
• comparing the level of said electrical signal with a predetermined slice level;
• and
• detecting misfire when a signal level of the electrical signal is less than the slice level.

A method of detecting misfire of an internal combustion engine, comprising the steps of:

• detecting combustion temperature in respective cylinders of the engine;
• converting the detected combustion temperature of a cylinder into an electrical signal corresponding to a measure of the detected combustion temperature;
• comparing the electrical signal with a predetermined level;
• and
• judging a misfire condition of the engine when the electrical signal is
• less than the predetermined level.

A method of detecting a condition of operation of an internal combustion engine, comprising the steps of:

• detecting combustion light intensity in respective combustion chambers of the engine:
• converting the detected light intensity of a combustion chamber into the electrical signal corresponding to a measure of the detected combustion light intensity;
• and
• comparing the electrical signal with a predetermined slice level and judging that the engine is operating outside of an allowable limit of NOx emission when the signal level of the electrical signal is less than said predetermined slice level.

A method of detecting a condition of an internal combustion engine, comprising the steps of:

• detecting combustion light intensity in respective combustion chambers of the engine;
• converting the detected combustion light intensity of a combustion chamber into an electrical signal corresponding to a measure of the detected combustion light intensity;
• and
• detecting an amount of NOx emitted from the engine on the basis of said electrical signal.

An apparatus for controlling an internal combustion engine, comprising:

• means for detecting combustion light intensity in respective combustion chambers of the engine;
• means for converting detected combustion light intensity of a combustion chamber into an electrical signal corresponding to a measure of the detected combustion light intensity;
• means for comparing the electrical signal with a predetermined slice level and judging that the engine is operating in a misfire condition when the signal level of the electrical signal is less than the predetermined slice level;
• and
• means for controlling at least one of fuel air ratio and ignition timing
• until no misfire takes place.

An apparatus for controlling an internal combustion engine, comprising:

• means for detecting combustion temperature in respective combustion chambers of the engine;
• means for converting detected combustion temperature of a combustion chamber into an electrical signal corresponding to a measure of the detected combustion temperature;
• means for comparing the electrical signal with a predetermined level and judging that the engine is operating in a misfire condition when the signal level of the electrical signal is less than the predetermined level;
• and
• means for controlling at least one of fuel air ratio and ignition timing until no misfire takes place.

An apparatus for controlling an internal combustion engine, comprising:

• means for detecting combustion light intensity in respective combustion chambers of the engine;
• means for converting detected combustion light intensity into an electrical signal corresponding a measure of the detected combustion light intensity;
• means for comparing the electrical signal with a predetermined level corresponding to an allowable limit of NOx exhausted from the engine and judging the amount of NOx to be outside of the limit when a signal level of the electrical signal is equal to or larger than the predetermined level;
• and
• means for controlling at least one of fuel air ratio and ignition timing until the amount of NOx is within an allowable limit.