Method for operating an internal combustion engine having two inlet valves

Abstract

The invention relates to a method for controlling an internal combustion engine, which has a first inlet valve (P) and a second inlet valve (S) per cylinder, which can be operated independently of one another between maximum operation (P 1 , S 1 ) and minimum operation. The change of the inlet valves takes place preferably by engine oil pressure, in a basic state (P 1 +S 2 ) the first inlet valve (P) is in maximum operation (P 1 ) and the second inlet valve (S) is in minimum operation (S 2 ). From the basic state, the valve control device switches the first inlet valve (P) into a minimum operation (P 3 ) at low engine rotational speeds/engine torques and sufficient engine oil pressure and switches the second inlet valve (S) into maximum operation (S 1 ) at high engine rotational speeds/engine torques.

1 . A method of operating an internal combustion engine with at least one cylinder, the cylinder having a primary intake valve and a secondary intake valve disposed therein, the method comprising: 
 operating the primary valve at a first lift profile and the secondary valve at the second lift profile as a default condition wherein the primary valve is capable of being switched between said first lift profile and a third lift profile and the secondary valve is capable of being switched between said second lift profile and a fourth lift profile and the primary and secondary valves are independently controllable.    
     
     
         2 . The method of  claim 1  wherein said first lift profile has a taller valve stroke than said third lift profile and said fourth lift profile has a taller valve stroke than said second lift profile.  
     
     
         3 . The method of  claim 1  wherein said first lift profile has a longer opening duration than said third lift profile and said fourth lift profile has a longer opening duration than said second lift profile.  
     
     
         4 . The method of  claim 1  wherein a valve stroke of the secondary valve operating with said second lift profile is less than 40% of a valve stroke of the primary valve with said first lift profile.  
     
     
         5 . The method of  claim 1  wherein said third lift profile of the primary valve and said fourth profile of the secondary valve are caused to be selected by oil pressure acting on a valve change device.  
     
     
         6 . The method of  claim 1  wherein the primary valve operates with said first lift profile and the secondary valve operates with said second lift profile when oil pressure is below an actuation pressure.  
     
     
         7 . The method of  claim 1 , further comprising: operating the primary valve at said first lift profile and the secondary valve at said fourth lift profile in response to at least one of engine speed and torque.  
     
     
         8 . The method of  claim 1 , further comprising: operating the primary valve at said first lift profile and the secondary valve at said fourth lift profile when engine speed and torque are in a higher range.  
     
     
         9 . The method of  claim 1 , further comprising: operating the primary valve at said second lift profile and the secondary valve at said third lift profile in response to at least one of engine speed and torque.  
     
     
         10 . The method of  claim 1 , further comprising: operating the primary valve at said second lift profile and the secondary valve at said third lift profile when engine speed and torque are in a lower range.  
     
     
         11 . An internal combustion engine, comprising: at least one engine cylinder; 
 a primary inlet valve disposed in each of said cylinders;    a secondary inlet valve disposed in each of said cylinders;    a first variable valve control device allowing switching of the primary inlet valve between a first and a third lift profile;    a second variable valve control device allowing switching of the secondary inlet valve between a second lift profile and a fourth lift profile; and    an engine control unit coupled to the engine and to said first and second variable valve control devices, said engine control unit controlling said variable valve control devices based on a speed and torque of the engine.    
     
     
         12 . The engine of  claim 11  wherein said variable valve control devices are actuated by engine oil pressure.  
     
     
         13 . The engine of  claim 11  wherein said engine control unit manages oil pressure actuation of said variable valve control devices.  
     
     
         14 . The engine of  claim 11  wherein a default operating condition is when said primary inlet valve is operated at said first lift profile and said secondary valve at said second lift profile as a default condition.  
     
     
         15 . The engine of  claim 14  wherein said first lift profile has a taller valve stroke than said third lift profile and said fourth lift profile has a taller valve stroke than said second lift profile.  
     
     
         16 . The engine of  claim 14  wherein said first lift profile has a longer opening duration than said third lift profile and said fourth lift profile has a longer opening duration than said second lift profile.  
     
     
         17 . The engine of  claim 14  wherein said default operating condition is requested by said engine control unit when engine speed and torque is in a medium range.  
     
     
         18 . The engine of  claim 14  wherein said engine control unit causes switching of said first valve control device to said third lift profile at a lower range of engine speed and torque.  
     
     
         19 . The engine of  claim 14  wherein said engine control unit causes switching of said second valve control device to said fourth lift profile at a higher range of engine speed and torque.