System and method for operating an internal combustion engine

Abstract

An internal combustion engine is operated in accordance with a Miller cycle. The engine includes a piston disposed in the engine cylinder and configured to reciprocate between a top dead center position and a bottom dead center position of the engine cylinder. An air intake valve is coupled to the cylinder. The air intake valve is closed when the piston is about the bottom dead center position in the engine cylinder. An exhaust valve is coupled to the engine cylinder. The exhaust valve is opened for a predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve so as to exhaust a predetermined quantity of fresh charge from the engine cylinder via the exhaust valve.

1 . A method for operating an internal combustion engine in accordance with a Miller cycle, comprising:
 moving a piston from a top dead center position towards a bottom dead center position in an engine cylinder;   closing an intake valve of the internal combustion engine when the piston is about the bottom dead center position in the engine cylinder;   opening an exhaust valve for a predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve so as to exhaust a predetermined quantity of fresh charge from the engine cylinder via the exhaust valve.   
     
     
         2 . The method of  claim 1 , wherein the predetermined time period corresponds to a predetermined degree of crank angle. 
     
     
         3 . The method of  claim 1 , wherein about the bottom dead center position comprises a crank angle of less than or equal to 90 degrees from the bottom dead center position of the engine cylinder. 
     
     
         4 . The method of  claim 1 , comprising operating the internal combustion engine comprising a four-stroke engine. 
     
     
         5 . The method of  claim 1 , comprising operating the internal combustion engine comprising a two-stroke engine. 
     
     
         6 . The method of  claim 1 , comprising opening the exhaust valve for the predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve during an intake stroke. 
     
     
         7 . The method of  claim 1 , comprising opening the exhaust valve for the predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve during a compression stroke of the piston. 
     
     
         8 . The method of  claim 1 , further comprising compressing intake air in the engine cylinder after closing the exhaust valve when the piston is moved from the bottom dead center position towards the top dead center position of the engine cylinder during the compression stroke of the piston. 
     
     
         9 . The method of  claim 1 , wherein exhausting a predetermined quantity of fresh charge from the engine cylinder via the exhaust valve comprises reducing a compression ratio compared to an expansion ratio of the internal combustion engine. 
     
     
         10 . An internal combustion engine operated in accordance with a Miller cycle, the internal combustion engine comprising:
 an engine cylinder;   a piston disposed in the engine cylinder and configured to reciprocate between a top dead center position and a bottom dead center position of the engine cylinder;   an air intake valve coupled to the cylinder; wherein the air intake valve is closed when the piston is about the bottom dead center position in the engine cylinder; and   an exhaust valve coupled to the engine cylinder; wherein the exhaust valve is opened for a predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve so as to exhaust a predetermined quantity of fresh charge from the engine cylinder via the exhaust valve.   
     
     
         11 . The engine of  claim 10 , wherein the predetermined time period corresponds to a predetermined degree of crank angle. 
     
     
         12 . The engine of  claim 10 , wherein about the bottom dead center position comprises a crank angle of less than or equal to 90 degrees from the bottom dead center position of the engine cylinder. 
     
     
         13 . The engine of  claim 10 , wherein the internal combustion engine comprises a four-stroke engine. 
     
     
         14 . The engine of  claim 10 , wherein the internal combustion engine comprises a two-stroke engine. 
     
     
         15 . The engine of  claim 10 , wherein the exhaust valve is opened for the predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve during an intake stroke of the piston. 
     
     
         16 . The engine of  claim 10 , wherein the exhaust valve is opened for the predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake during a compression stroke of the piston. 
     
     
         17 . The engine of  claim 10 , wherein the internal combustion engine has a lower compression ratio compared to an expansion ratio. 
     
     
         18 . An internal combustion engine operated in accordance with a Miller cycle, the internal combustion engine comprising:
 an engine cylinder;   a piston disposed in the engine cylinder and configured to reciprocate between a top dead center position and a bottom dead center position of the engine cylinder;   an air intake valve coupled to the cylinder; wherein the air intake valve is closed when the piston is about the bottom dead center position in the engine cylinder; and   an exhaust valve coupled to the engine cylinder;   a controller communicatively coupled to the air intake valve and the exhaust valve and configured to control at least one of the air intake valve, the exhaust valve, wherein the exhaust valve is opened for a predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve so as to exhaust a predetermined quantity of fresh charge from the engine cylinder via the exhaust valve.   
     
     
         19 . The engine of  claim 18 , wherein the predetermined time period corresponds to a predetermined degree of crank angle. 
     
     
         20 . The engine of  claim 18 , wherein about the bottom dead center position comprises a crank angle of less than or equal to 90 degrees from the bottom dead center position of the engine cylinder. 
     
     
         21 . The engine of  claim 18 , wherein the internal combustion engine comprises a four-stroke engine. 
     
     
         22 . The engine of  claim 18 , wherein the internal combustion engine comprises a two-stroke engine. 
     
     
         23 . The engine of  claim 18 , wherein the controller is configured to open the exhaust valve for the predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve during an intake stroke of the piston. 
     
     
         24 . The engine of  claim 18 , wherein the controller is configured to open the exhaust valve for the predetermined time period when the piston is about the bottom dead center position of the engine cylinder after closing the intake valve during a compression stroke of the piston 
     
     
         25 . The engine of  claim 18 , wherein the engine has a lower compression ratio compared to an expansion ratio.