Method and apparatus for optimized combustion in an internal combustion engine utilizing homogeneous charge compression ignition and variable valve actuation

Abstract

A valvetrain system mechanization for an internal combustion engine using compression ignition, including homogeneous charge compression ignition, having two intake and one or more exhaust valves per cylinder. The valves are operated by dual overhead camshafts having two-step cams. The intake and exhaust camshafts are provided with phasers for varying the opening and closing of the intake and exhaust valves. A two-step roller finger follower is disposed for each valve between the cam lobes and the valve stem. The two sets of intake and exhaust valves are controlled by separate oil control valves. Swirl of gases may be introduced by mismatching the lifts of the valves. The valve opening times, closing times, lifts, fuel injection, compression ratio, and exhaust gas recirculation may be varied to optimize combustion conditions for a range of engine operating modes.

1 - 23 . (canceled)  
   
   
       24 . In an internal combustion engine using compression ignition having a plurality of cylinders, and having a first and second intake valve and at least one exhaust valve for each cylinder, and having a variable valve actuator for controlling said first and second intake valves of at least one cylinder, and having an exhaust camshaft phaser, 
 a method for operating said engine in a predetermined operating mode, comprising the steps of: 
 a) adjusting the setting of said exhaust phaser to provide a predetermined opening and closing timing of said exhaust valves; and  
   b) adjusting the setting of said valve actuator for controlling said first and second intake valves of at least one cylinder to provide a predetermined schedule of intake activation and deactivation.    
   
   
       25 . A method in accordance with  claim 24  wherein said engine further having means for recirculating exhaust gas from an engine exhaust system into said cylinders and having means for varying fuel injection timing into said cylinders, said method including the further steps of: 
 a. adjusting the setting of said exhaust gas recirculation means to provide a predetermined amount of exhaust gas recirculated into the cylinders; and    b. adjusting the time and amounts of fuel injection into the cylinders according to a predetermined fuel injection schedule.    
   
   
       26 . A method in accordance with  claim 24  wherein said engine includes a first and second exhaust valve for each cylinder and a variable valve actuator controlling said first and second exhaust valves of at least one cylinder, said method including the further step of adjusting the setting of said variable valve actuator for controlling activation and deactivation of said first and second exhaust valves.  
   
   
       27 . A method in accordance with  claim 24  wherein said engine includes an intake cam phaser, said method including the further step of adjusting the setting of said intake cam phaser to provide a predetermined opening and timing of said intake valves.  
   
   
       28 . A method in accordance with  claim 26  wherein said engine includes an intake cam phaser, said method including the further step of adjusting the setting of said intake cam phaser to provide a predetermined opening and timing of said intake valves.  
   
   
       29 . A method in accordance with  claim 28  wherein said predetermined operating mode is Cold Start, comprising the steps of: 
 a) advancing said intake phaser to provide early opening and early closing of said intake valves and high effective compression ratio;    b) setting said first intake valves on low lift and setting said second intake valves on zero lift to provide in-cylinder charge swirl;    c) advancing said exhaust phaser to provide early opening and early closing of said exhaust valves to warm said engine exhaust system and to trap exhaust gases for cylinder heating; and    d) setting said first and second exhaust valves on normal lift.    
   
   
       30 . A method in accordance with  claim 28  wherein said predetermined operating mode is Warm Idle, comprising the steps of: 
 a) advancing said intake phaser and retarding said exhaust phaser to reduce compression ratio and increase effective expansion ratio;    b) setting said first intake valves on high lift and setting said second intake valves on zero lift to provide in-cylinder charge swirl; and    c) setting said first and second exhaust valves on normal lift.    
   
   
       31 . A method in accordance with  claim 28  wherein said predetermined operating mode is Low Load, comprising the steps of: 
 a) advancing said intake phaser and retarding said exhaust phaser to provide an intermediate compression ratio and a high effective expansion ratio;    b) setting said first intake valves on high lift and setting said second intake valves on zero lift to provide in-cylinder charge swirl; and    c) setting said first and second exhaust valves on normal lift.    
   
   
       32 . A method in accordance with  claim 28  wherein said predetermined operating mode is Medium Load, comprising the steps of: 
 a) retarding said intake phaser to reduce effective compression ratio;    b) setting said first intake valves on high lift and setting said second intake valves on zero lift to provide in-cylinder charge swirl;    c) retarding said exhaust phaser to provide a high effective expansion ration; and    d) holding said first exhaust valves open during part of the induction stroke to provide internal exhaust gas recirculation and in-cylinder exhaust gas swirl.    
   
   
       33 . A method in accordance with  claim 32  wherein said engine includes a means for varying fuel injection timing into said cylinders, said method including the further step of pulsing said fuel injection means a plurality of times beginning ahead of top dead center of the compression stroke of said engine such that injected fuel is substantially premixed before combustion.  
   
   
       34 . A method in accordance with  claim 28  wherein said predetermined operating mode is Peak Torque, comprising the steps of: 
 a) retarding said intake phaser to reduce effective compression ratio;    b) setting said first and second intake valves on high lift to increase in-cylinder combustion air; and    c) fully advancing said exhaust phaser to provide early exhaust valve opening.    
   
   
       35 . A method in accordance with  claim 28  wherein said predetermined operating mode is Peak Power, comprising the steps of: 
 a) retarding said intake phaser to reduce effective compression ratio below that for Peak Torque mode;    b) setting said first and second intake valves on high lift to increase in-cylinder combustion air; and    c) fully advancing said exhaust phaser to provide early exhaust valve opening.    
   
   
       36 . A method in accordance with  claim 28  wherein said predetermined operating mode is Acceleration Transient Operating Mode, comprising the steps of: 
 a) fully advancing said intake phaser to increase in-cylinder combustion air;    b) setting said first intake valves on high lift and setting said second intake valves on zero lift to provide in-cylinder charge swirl;    c) fully advancing said exhaust phaser to provide early exhaust valve opening to rapidly accelerate said turbocharger;    d) holding said first and second exhaust valves open during part of the opening of said first and second intake valves to provide internal exhaust gas recirculation; and