Method for operating an internal combustion engine employing a dedicated-cylinder egr system

Abstract

A multi-cylinder spark-ignition internal combustion engine includes a plurality of first and second intake valves disposed between the air intake system and a corresponding plurality of engine cylinders. The engine also includes a dedicated-cylinder exhaust gas recirculation (EGR) system including an exhaust runner fluidly connected between exhaust valve(s) of one of the cylinders and the air intake system of the engine. A controllable intake valve activation system is configured to control openings of the plurality of first and second intake valves. A controller is operatively connected to the engine and the controllable intake valve activation system, and includes an instruction set to monitor operation of the engine, and control openings of the plurality of first intake valves and control openings of the plurality of second intake valves to generate in-cylinder mixing of a cylinder charge that achieves combustion stability for an engine speed/load operating point.

1 . A multi-cylinder internal combustion engine system, comprising:
 an engine subassembly including an engine block defining a plurality of cylinders and a plurality of first and second intake valves disposed in a cylinder head between an air intake system and the cylinders;   a dedicated-cylinder exhaust gas recirculation (EGR) system including an exhaust runner fluidly connected between an exhaust valve of one of the cylinders and the air intake system of the engine;   a controllable intake valve activation system configured to control openings of the plurality of first and second intake valves;   a controller operatively connected to the internal combustion engine and the controllable intake valve activation system, the controller including an instruction set, the instruction set executable to:
 monitor of a parameter associated with combustion stability in the engine, and 
 operate the controllable intake valve activation system to control openings of the first intake valves and control openings of the second intake valves, wherein the openings of the first and second intake valves are selected to achieve combustion stability in the engine. 
   
     
     
         2 . The engine system of  claim 1 , wherein the instruction set is further executable to:
 monitor operation of the engine to determine an engine speed/load operating point, and control the controllable intake valve activation system to control openings of the first intake valves and control openings of the second intake valves to achieve combustion stability at the engine speed/load operating point.   
     
     
         3 . The engine system of  claim 2 , wherein the instruction set executable to control the controllable intake valve activation system to control openings of the first and second intake valves and control openings of the second intake valves to achieve combustion stability at the engine speed/load operating point comprises a calibration that includes preferred openings of the first and second intake valves based upon the engine speed/load operating point. 
     
     
         4 . The engine system of  claim 1 , wherein the instruction set executable to control the controllable intake valve activation system to control openings of the first intake valves and control openings of the second intake valves comprises the instruction set being executable to control the controllable intake valve activation system to open both the first intake valve and the second intake valve during each intake stroke of each combustion cycle. 
     
     
         5 . The engine system of  claim 1 , wherein the instruction set executable to control the controllable intake valve activation system to control openings of the first intake valves and control openings of the second intake valves comprises the instruction set being executable to control the controllable intake valve activation system to open only the first intake valve. 
     
     
         6 . The engine system of  claim 5 , further comprising the instruction set being executable to control the controllable intake valve activation system to open only the first intake valve during each intake stroke of each combustion cycle, wherein open time of the first intake valve is extended to effect valve closing during a subsequent compression stroke. 
     
     
         7 . The engine system of  claim 5 , further comprising the instruction set being executable to control the controllable intake valve activation system to open only the first intake valve during each intake stroke of each combustion cycle, wherein open time of the first intake valve is reduced to effect valve closing prior to the end of the intake stroke. 
     
     
         8 . The engine system of  claim 1 , wherein the instruction set executable to control the controllable intake valve activation system to control openings of the first intake valves and control openings of the second intake valves comprises the instruction set being executable to control the controllable intake valve activation system to open only the second intake valve during each intake stroke of each combustion cycle. 
     
     
         9 . The engine system of  claim 8 , wherein the instruction set is further executable to control the controllable intake valve activation system to open only the second intake valve during each intake stroke of each combustion cycle, wherein open time of the second intake valve is extended to effect valve closing during a subsequent compression stroke. 
     
     
         10 . The engine system of  claim 8 , wherein the instruction set is further executable to control the controllable intake valve activation system to open only the second intake valve during each intake stroke of each combustion cycle, wherein open time of the second intake valve is reduced to effect valve closing prior to the end of the intake stroke. 
     
     
         11 . A method for operating a multi-cylinder internal combustion engine that includes a variable intake valve activation system and a dedicated-cylinder exhaust gas recirculation (EGR) system, the method comprising:
 monitoring an engine parameter associated with combustion stability during operation of the dedicated-cylinder EGR system; and   controlling, by a controller, the variable intake valve activation system to control opening of a first intake valve and control opening of a second intake valve to achieve combustion stability.   
     
     
         12 . The method of  claim 11 , further comprising:
 monitoring operation of the engine to determine an engine speed/load operating point, and   controlling the controllable intake valve activation system to control openings of the first intake valves and control openings of the second intake valves to achieve combustion stability at the engine speed/load operating point.   
     
     
         13 . The method of  claim 12 , wherein controlling the controllable intake valve activation system comprises a calibration that includes preferred openings of the first and second intake valves based upon the engine speed/load operating point. 
     
     
         14 . The method of  claim 11 , wherein controlling the controllable intake valve activation system comprises opening both the first intake valve and the second intake valve during each intake stroke of each combustion cycle. 
     
     
         15 . The method of  claim 11 , wherein controlling the controllable intake valve activation system comprises opening only the first intake valve during each intake stroke of each combustion cycle. 
     
     
         16 . The method of  claim 15 , further comprising controlling the controllable intake valve activation system to open only the first intake valve during each intake stroke of each combustion cycle, wherein the opening of the first intake valve is extended to end during a subsequent compression stroke. 
     
     
         17 . The method of  claim 15 , further comprising controlling the controllable intake valve activation system to open only the first intake valve during each intake stroke of each combustion cycle, wherein the opening of the first intake valve is reduced to end during the intake stroke. 
     
     
         18 . The method of  claim 11 , wherein controlling the controllable intake valve activation system comprises opening only the second intake valve during each intake stroke of each combustion cycle. 
     
     
         19 . The method of  claim 18 , further comprising opening only the second intake valve during each intake stroke of each combustion cycle, wherein opening of the second intake valve is extended to end during a subsequent compression stroke. 
     
     
         20 . The method of  claim 18 , further comprising opening only the second intake valve during each intake stroke of each combustion cycle, wherein the opening of the second intake valve is reduced to end during the intake stroke.