System using time resolved air/fuel sensor to equalize cylinder to cylinder air/fuel ratios with variable valve control

Claim 1

A method of minimizing cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using a high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ratio; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; evaluating the cylinder to cylinder air/fuel ratio variations when the engine is operating at maximum valve lift, and generating correction signals for each cylinder; adjusting said fuel charges in each of the cylinders from said baseline level in response to said correction signals; storing the fuel charge correction signal for each cylinder; and modifying the fuel charges from baseline using the correction signal when operating in a variable lift mode.

Claim 2

A method of minimizing cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using a high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ratio; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; evaluating the cylinder to cylinder air/fuel ratio variations when the engine is operating at maximum valve lift, and generating correction signals for each cylinder; adjusting said fuel charges in each of the cylinders from said baseline level in response to said correction signals; storing the fuel charge correction signal for each cylinder; and modifying the fuel charges from baseline using the correction signal when operating in a variable lift mode.

Claim 4

A method of minimizing cylinder to cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ratio; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; evaluating the cylinder to cylinder air/fuel ratio variations when the engine is operating at maximum valve lift, and generating correction signals for each cylinder; adjusting said fuel charges in each of the cylinders from said baseline level in response to said correction signals; determining the amount of variation in intake valve lift between the independent variable lift intake valves; comparing said lift variation to a predetermined acceptable limit; and varying said individual cylinder fuel charge from baseline when said variation in lift is above said acceptable limit, thereby reducing said variation below the limit.

Claim 5

A method of minimizing cylinder to cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ratio; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; evaluating the cylinder to cylinder air/fuel ratio variations when the engine is operating at maximum valve lift, and generating correction signals for each cylinder; adjusting said fuel charges in each of the cylinders from said baseline level in response to said correction signals; determining the amount of variation in intake valve lift between the independent variable lift intake valves; comparing said lift variation to a predetermined acceptable limit; and varying said individual cylinder fuel charge from baseline when said variation in lift is above said acceptable limit, thereby reducing said variation below the limit.

Claim 6

A method of minimizing cylinder to cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using a high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ratio; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; determining the amount of variation in intake valve lift between the independent variable lift intake valves; comparing said lift variation to a predetermined acceptable limit; and varying said individual cylinder fuel charge from baseline when said variation in lift is above said acceptable limit, thereby reducing said air/fuel ratio variation to an acceptable level.

Claim 7

A method of minimizing cylinder to cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using a high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ratio; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; determining the amount of variation in intake valve lift between the independent variable lift intake valves; comparing said lift variation to a predetermined acceptable limit; and varying said individual cylinder fuel charge from baseline when said variation in lift is above said acceptable limit, thereby reducing said air/fuel ratio variation to an acceptable level.

Claim 8

A method of minimizing cylinder to cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using a high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves, in conjunction with an engine driven camshaft and a lost motion mechanism, in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ration when the engine is operating at less than maximum valve lift; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; evaluating the cylinder to cylinder air/fuel ratio variations when the engine is operating at maximum valve lift and generating correction signals for each cylinder; adjusting said fuel charges in each of the cylinders from said baseline level in response to said correction signals; storing the fuel charge correction signal for each cylinder; and modifying the fuel charges from baseline using the correction signal when operating at less than maximum valve lift.

Claim 9

A method of minimizing cylinder to cylinder air/fuel ratio variation in a multi-cylinder engine having variable lift intake valves, comprising the steps of: sensing the oxygen ratio of a combined exhaust gas stream from a plurality of cylinders using a high speed sensor which generates a composite air/fuel ratio signal; monitoring the engine rotational position and cycle, to generate an engine event signal; analyzing said composite air/fuel ratio and engine event signals, and generating individual cylinder air/fuel ratio signals; controlling the air flow of each cylinder using the variable lift intake valves, in conjunction with an engine driven camshaft and a lost motion mechanism, in response to said individual cylinder air/fuel ratio signals to adjust the air/fuel ration when the engine is operating at less than maximum valve lift; supplying fuel to each cylinder of the engine using a plurality of fuel injectors each coupled to a different cylinder using baseline fuel charges for a given operating condition; evaluating the cylinder to cylinder air/fuel ratio variations when the engine is operating at maximum valve lift and generating correction signals for each cylinder; adjusting said fuel charges in each of the cylinders from said baseline level in response to said correction signals; storing the fuel charge correction signal for each cylinder; and modifying the fuel charges from baseline using the correction signal when operating at less than maximum valve lift.

Claim 12

An apparatus for minimizing cylinder to cylinder air/fuel ratio variations in a multi-cylinder engine, said apparatus comprising: an oxygen sensor, mounted within an exhaust stream from a plurality of cylinders, for sensing the exhaust gas oxygen ratio of the exhaust gasses, and generating a composite air/fuel ratio signal; position sensing means for monitoring the engine rotational position and cycle, to generate a engine event signal; a variable lift intake valve coupled to each cylinder of the engine; means for analyzing said composite air/fuel ratio and said engine event signal, to determine the individual cylinder air/fuel ratios; variable lift valve control means for individually controlling the variable lift intake valves in response to said individual air/fuel ratio signals to reduce cylinder to cylinder variation; wherein the engine has a V configuration having two banks of cylinders and two separate corresponding exhaust streams, wherein said oxygen sensor comprises two oxygen sensors, one in each of said exhaust streams.

Claim 13

An apparatus for minimizing cylinder to cylinder air/fuel ratio variations in a multi-cylinder engine, said apparatus comprising: an oxygen sensor, mounted within an exhaust stream from a plurality of cylinders, for sensing the exhaust gas oxygen ratio of the exhaust gasses, and generating a composite air/fuel ratio signal; position sensing means for monitoring the engine rotational position and cycle, to generate a engine event signal; a variable lift intake valve coupled to each cylinder of the engine; means for analyzing said composite air/fuel ratio and said engine event signal, to determine the individual cylinder air/fuel ratios; variable lift valve control means for individually controlling the variable lift intake valves in response to said individual air/fuel ratio signals to reduce cylinder to cylinder variation; wherein the engine has a V configuration having two banks of cylinders and two separate corresponding exhaust streams, wherein said oxygen sensor comprises two oxygen sensors, one in each of said exhaust streams.

Claim 16

An apparatus for minimizing cylinder to cylinder air/fuel ratio variations in a multi-cylinder in-line engine with only one exhaust stream said apparatus comprising: a single oxygen sensor, mounted within an exhaust stream from a plurality of cylinders, placed in the exhaust stream at a point after exhaust gasses from all of the cylinders are combined into a single stream of gas, for sensing the exhaust gas oxygen ratio of the exhaust gasses, and generating a composite air/fuel ratio signal; position sensing means for monitoring the engine rotational position and cycle, to generate a engine event signal; a variable lift intake valve coupled to each cylinder of the engine, wherein said plurality of variable lift intake valves includes an engine driven camshaft and a lost motion variable valve lift mechanism; means for analyzing said composite air/fuel ratio and said engine event signal, to determine the individual cylinder air/fuel ratios; variable lift valve control means for individually controlling the variable lift intake valves in response to said individual air/fuel ratio signals to reduce cylinder to cylinder variation; a plurality of electronically actuated fuel injectors each coupled to a cylinder; fuel correcting means for analyzing said individual air/fuel ratio signals and engine event signal when said engine is operated with said variable lift intake valves at maximum valve lift, to identify cylinder to cylinder air/fuel variability and to generate a corresponding fuel injector correction signals; a fuel controller responsive to said fuel correcting means for electronically actuating said fuel injectors; means for determining the amount of variation in intake valve lift between said independent variable lift intake valves; means for comparing said lift variation to a predetermined acceptable limit; and means for varying said individual cylinder fuel charge from baseline when said variation lift is above said acceptable limit, thereby reducing said variation below the limit.

Claim 17

An apparatus for minimizing cylinder to cylinder air/fuel ratio variations in a multi-cylinder in-line engine with only one exhaust stream said apparatus comprising: a single oxygen sensor, mounted within an exhaust stream from a plurality of cylinders, placed in the exhaust stream at a point after exhaust gasses from all of the cylinders are combined into a single stream of gas, for sensing the exhaust gas oxygen ratio of the exhaust gasses, and generating a composite air/fuel ratio signal; position sensing means for monitoring the engine rotational position and cycle, to generate a engine event signal; a variable lift intake valve coupled to each cylinder of the engine, wherein said plurality of variable lift intake valves includes an engine driven camshaft and a lost motion variable valve lift mechanism; means for analyzing said composite air/fuel ratio and said engine event signal, to determine the individual cylinder air/fuel ratios; variable lift valve control means for individually controlling the variable lift intake valves in response to said individual air/fuel ratio signals to reduce cylinder to cylinder variation; a plurality of electronically actuated fuel injectors each coupled to a cylinder; fuel correcting means for analyzing said individual air/fuel ratio signals and engine event signal when said engine is operated with said variable lift intake valves at maximum valve lift, to identify cylinder to cylinder air/fuel variability and to generate a corresponding fuel injector correction signals; a fuel controller responsive to said fuel correcting means for electronically actuating said fuel injectors; means for determining the amount of variation in intake valve lift between said independent variable lift intake valves; means for comparing said lift variation to a predetermined acceptable limit; and means for varying said individual cylinder fuel charge from baseline when said variation lift is above said acceptable limit, thereby reducing said variation below the limit.

Claim 18

An apparatus for minimizing cylinder to cylinder air/fuel ratio variations in a multi-cylinder engine, said apparatus comprising: an oxygen sensor, mounted within an exhaust stream from a plurality of cylinders, for sensing the exhaust gas oxygen ratio of the exhaust gasses, and generating a composite air/fuel ratio signal; position sensing means for monitoring the engine rotational position and cycle, to generate a engine event signal; a variable lift intake valve coupled to each cylinder of the engine; means for analyzing said composite air/fuel ratio and said engine event signal, to determine the individual cylinder air/fuel ratios; variable lift valve control means for individually controlling the variable lift intake valves in response to said individual air/fuel ratio signals to reduce cylinder to cylinder variation; a plurality of electronically actuated fuel injectors, each coupled to a cylinder, capable of producing variable fuel charges from a baseline fuel charge for a given operating condition; means for determining the amount of variation in intake valve lift between said variable lift intake valves; means for comparing said lift variation to a predetermined acceptable limit; and means for varying said individual cylinder fuel charge from baseline when said variation in lift is above said acceptable limit, thereby reducing said air/fuel ratio variation to an acceptable level.

Claim 19

An apparatus for minimizing cylinder to cylinder air/fuel ratio variations in a multi-cylinder engine, said apparatus comprising: an oxygen sensor, mounted within an exhaust stream from a plurality of cylinders, for sensing the exhaust gas oxygen ratio of the exhaust gasses, and generating a composite air/fuel ratio signal; position sensing means for monitoring the engine rotational position and cycle, to generate a engine event signal; a variable lift intake valve coupled to each cylinder of the engine; means for analyzing said composite air/fuel ratio and said engine event signal, to determine the individual cylinder air/fuel ratios; variable lift valve control means for individually controlling the variable lift intake valves in response to said individual air/fuel ratio signals to reduce cylinder to cylinder variation; a plurality of electronically actuated fuel injectors, each coupled to a cylinder, capable of producing variable fuel charges from a baseline fuel charge for a given operating condition; means for determining the amount of variation in intake valve lift between said variable lift intake valves; means for comparing said lift variation to a predetermined acceptable limit; and means for varying said individual cylinder fuel charge from baseline when said variation in lift is above said acceptable limit, thereby reducing said air/fuel ratio variation to an acceptable level.