Internal combustion engine comprising a variable valve lift system and a method for controlling valve lift shifting

Abstract

An internal combustion engine comprising a variable valve lift system whereby the engine can operate selectively in either of at least two valve lift modes, and a variable valve timing system, as well as a method for controlling valve lift shifting in such an engine are disclosed. The method comprises controlling the variable valve timing system so as to reduce the difference between two of the valve lift modes regarding the output torque of the engine.

1 . A method for controlling valve lift shifting in an internal combustion engine having a variable valve lift system whereby the engine can operate selectively in either of at least two valve lift modes, the engine further having a variable valve timing system, the method comprising: 
 controlling the variable valve timing system so as to reduce a difference between two of the valve lift modes regarding the output torque of the engine.    
   
   
       2 . The method according to  claim 1 , wherein the variable valve timing system is controlled based at least partially on an engine speed and a pressure parameter of the engine.  
   
   
       3 . The method according to  claim 2 , wherein said pressure parameter is at least partly based on an engine intake manifold pressure.  
   
   
       4 . The method according to  claim 2 , wherein said pressure parameter is at least partly based on an air flow in said engine intake manifold.  
   
   
       5 . The method according to  claim 2 , wherein the variable valve timing system is controlled based at least partially on an engine speed and a position of a throttle valve of the engine.  
   
   
       6 . The method according to  claim 5 , further comprising determining a balance value of valve timing such that the output torque is essentially the same for two of the valve lift modes at said balance value.  
   
   
       7 . The method according to  claim 6 , further comprising determining a current value of the valve timing, and switching valve lift mode if said current value is within a range comprising said balance value.  
   
   
       8 . The method according to  claim 7 , wherein said range is determined at least partly based on at least one offset value in relation to said balance value of the valve timing.  
   
   
       9 . The method according to  claim 8 , wherein at least one of said offset values is predetermined.  
   
   
       10 . The method according to  claim 8 , wherein at least one of said offset values is determined at least partly based on at least one engine operating parameter.  
   
   
       11 . The method according to  claim 8 , further comprising determining a degree of requested transient torque, and determining at least one of the offset values at least partly based on said degree of requested transient torque.  
   
   
       12 . An automotive system, comprising 
 an internal combustion engine having a variable valve lift system and a variable valve timing system;    an engine control unit adapted to control said variable valve timing system so as to reduce a difference between two of the valve lift modes regarding the output torque of the engine.    
   
   
       13 . The automotive system according to  claim 12 , wherein said engine control unit is adapted to control said variable valve timing system based at least partially on an engine speed and an engine pressure parameter.  
   
   
       14 . The automotive system according to  claim 13 , wherein said engine control unit is adapted to determine said pressure parameter at least partly based on an engine intake manifold pressure.  
   
   
       15 . The automotive system according to  claim 13 , wherein said engine control unit is adapted to determine said pressure parameter at least partly based on an air flow in the intake manifold.  
   
   
       16 . The automotive system according to  claim 13 , wherein said engine control unit is adapted to control said variable valve timing system based at least partially on an engine speed and a position of a throttle valve of said engine.  
   
   
       17 . The automotive system according to  claim 16 , wherein said engine control unit is adapted to determine a balance value of valve timing such that output torque is essentially the same for two of the valve lift modes at the balance value.  
   
   
       18 . The automotive system according to  claim 17 , wherein said engine control unit is adapted to determine a current value of valve timing, and to switch valve lift mode if said current value is within a range comprising said balance value.  
   
   
       19 . The automotive system according to  claim 18 , wherein said engine control unit is adapted to determine said range at least partly based on at least one offset value in relation to said balance value of the valve timing.  
   
   
       20 . The automotive system according to  claim 19 , wherein at least one of said offset values is predetermined.  
   
   
       21 . The automotive system according to  claim 19 , wherein said engine control unit is adapted to determine at least one of said offset values at least partly based on at least one engine operation parameter.  
   
   
       22 . The automotive system according to  claim 19 , wherein said engine control unit is adapted to determine a degree of requested transient torque, and to determine at least one of said offset values at least partly based on a degree of requested transient torque.