Method to optimize engine operation using active fuel management

Abstract

A method for operating an internal combustion engine comprises providing a vehicle having an internal combustion gasoline engine including multiple cylinders and wherein the engine is operating in a deactivated cylinder mode, receiving a torque request if a cylinder reactivation torque smoothing mode is active, setting a variable torque ratio to 1.0 if the torque request is greater than a fast exit threshold torque, setting the variable torque ratio to 0.0 if the torque request is less than a slow exit threshold torque, setting the variable torque ratio to a value between 0.0 and 1.0 if the torque request is between the fast exit threshold torque and slow exit threshold torque, and calculating a component of final engine output torque.

The following is claimed: 
     
         1 . A method for operating an internal combustion engine, the method comprising:
 providing a vehicle having an internal combustion gasoline engine including multiple cylinders and wherein the engine is operating in a deactivated cylinder mode;   receiving a torque request if a cylinder reactivation torque smoothing mode is active;   setting a variable torque ratio to r max  if the torque request is greater than a fast exit threshold torque, and   setting the variable torque ratio to a value less than r max  if the torque request is less than the fast exit threshold torque.   
     
     
         2 . The method of operating an internal combustion engine of  claim 1  further comprising calculating a component of final engine output torque using the variable torque ratio. 
     
     
         3 . The method of operating an internal combustion engine of  claim 2  wherein calculating the component of final engine output torque t f  further comprises calculating the component of final engine output torque according to the formula:
     t   f   =r ( t   fast ), and 
 wherein t fast  is the fast exit threshold torque and r is the variable torque ratio. 
 
     
     
         4 . The method of operating an internal combustion engine of  claim 1  wherein setting the variable torque ratio to a value below r max  if the torque request is below the fast exit threshold torque further comprises setting the variable torque ratio to a value proportional to the torque request if the torque request is below the fast exit threshold torque. 
     
     
         5 . The method of operating an internal combustion engine of  claim 1  wherein setting the variable torque ratio to r max  if the torque request is greater than a fast exit threshold torque further comprises setting the variable torque ratio r to 1.0 if the torque request is greater than the fast exit threshold torque. 
     
     
         6 . A method for operating an internal combustion engine, the method comprising:
 providing a vehicle having an internal combustion gasoline engine including multiple cylinders and wherein the engine is operating in a deactivated cylinder mode;   receiving a torque request if a cylinder reactivation torque smoothing mode is active;   setting a variable torque ratio to r min  if the torque request is less than a slow exit threshold torque, and   setting the variable torque ratio to a value greater than r min  if the torque request is greater than the slow exit threshold torque.   
     
     
         7 . The method of operating an internal combustion engine of  claim 6  further comprising calculating a component of final engine output torque using the variable torque ratio. 
     
     
         8 . The method of operating an internal combustion engine of  claim 7  wherein calculating the component of final engine output torque t f  further comprises calculating the component of final engine output torque according to the formula:
     t   f   =r ( t   slow ), and 
 wherein t slow  is the slow exit threshold torque and r is the variable torque ratio. 
 
     
     
         9 . The method of operating an internal combustion engine of  claim 6  wherein setting the variable torque ratio to a value greater than r min  if the torque request is greater than the slow exit threshold torque further comprises setting the variable torque ratio to a value proportional to the torque request if the torque request is greater than the slow exit threshold torque. 
     
     
         10 . The method of operating an internal combustion engine of  claim 6  wherein setting the variable torque ratio to r min  if the torque request is less than a slow exit threshold torque further comprises setting the variable torque ratio to 0.0 if the torque request is less than the slow exit threshold torque. 
     
     
         11 . A method for operating an internal combustion engine, the method comprising:
 providing a vehicle having an internal combustion gasoline engine including multiple cylinders and wherein the engine is operating in a deactivated cylinder mode;   receiving a torque request if a cylinder reactivation torque smoothing mode is active;   setting a variable torque ratio to r max  if the torque request is greater than a fast exit threshold torque, and   setting the variable torque ratio to a value less than r max  if the torque request is less than the fast exit threshold torque.   
     
     
         12 . The method of operating an internal combustion engine of  claim 11  further comprising setting the variable torque ratio to r min  if the torque request is less than a slow exit threshold torque. 
     
     
         13 . The method of operating an internal combustion engine of  claim 12  further comprising setting the variable torque ratio to a value between r min  and r max  if the torque request is between the fast exit threshold torque and the slow exit threshold torque. 
     
     
         14 . The method of operating an internal combustion engine of  claim 13  further comprising calculating a component of final engine output torque using the variable torque ratio. 
     
     
         15 . The method of operating an internal combustion engine of  claim 14  wherein calculating the component of final engine output torque t f  further comprises calculating the component of final engine output torque according to the formula:
     t   f   =t   slow   +r ( t   fast   −t   slow ), and 
 wherein t fast  is the fast exit threshold torque, t slow  is the slow exit threshold torque, and r is the variable torque ratio. 
 
     
     
         16 . The method of operating an internal combustion engine of  claim 15  wherein setting the variable torque ratio to a value between r min  and r max  if the torque request is between the fast exit threshold torque and the slow exit threshold torque further comprises setting the variable torque ratio to a value proportional to the torque request if the torque request is between the fast exit threshold torque and the slow exit threshold torque. 
     
     
         17 . The method of operating an internal combustion engine of  claim 16  wherein setting the variable torque ratio to r max  if the torque request is greater than a fast exit threshold torque further comprises setting the variable torque ratio to 1.0 if the torque request is greater than the fast exit threshold torque. 
     
     
         18 . The method of operating an internal combustion engine of  claim 17  wherein setting the variable torque ratio to r min  if the torque request is less than a slow exit threshold torque further comprises setting the variable torque ratio to 0.0 if the torque request is less than the slow exit threshold torque. 
     
     
         19 . The method of operating an internal combustion engine of  claim 18  wherein setting the variable torque ratio to r max  if the torque request is greater than a fast exit threshold torque further comprises setting the variable torque ratio to r max  if the torque request is greater than the fast exit threshold torque wherein the fast exit threshold torque is derived from calibration tables having a fast exit threshold torque value for one of a plurality of operational parameters. 
     
     
         20 . The method of operating an internal combustion engine of  claim 19  wherein setting the variable torque ratio to r min  if the torque request is less than a slow exit threshold torque further comprises setting the variable torque ratio to r min  if the torque request is less than the slow exit threshold torque wherein the slow exit threshold torque is derived from calibration tables having a slow exit threshold torque value for one of a plurality of operational parameters.