Control apparatus for supercharger-equipped internal combustion engine

Abstract

Provided is a control apparatus for a supercharged internal combustion engine, which can favorably achieve a good balance between prevention of overheat of a catalyst disposed an exhaust passage and suppression of turbo lag, in a case in which a fresh air blow-through is generated through a combustion chamber from an intake passage to an exhaust passage. A turbo supercharger ( 22 ), an exhaust bypass passage ( 36 ), a WGV ( 38 ) capable of switching the opening and closing of the exhaust bypass passage ( 36 ), and variable valve operating mechanisms ( 46, 48 ) capable of changing a valve overlap period are included. The valve overlap period is shortened so that the fresh air blow-through amount Gsca becomes equal to or smaller than a predetermined blow-through determination value Gjudge when the blow-through amount Gsca is larger than the blow-through determination value Gjudge. The WGV ( 38 ) is opened when the blow-through amount Gsca is still larger than the blow-through determination value Gjudge after the valve overlap period has been shortened.

1 .- 2 . (canceled) 
     
     
         3 . A control apparatus for a supercharged internal combustion engine, comprising:
 a turbo supercharger which includes, in an exhaust passage, a turbine that is operated by exhaust energy;   an exhaust bypass passage which branches off from the exhaust passage at an upstream side portion of the turbine and merges with the exhaust passage at a downstream side portion of the turbine;   a waste gate valve which is capable of switching an opening and closing of the exhaust bypass passage;   a variable valve operating mechanism which is capable of changing a valve overlap period during which an opening period of an exhaust valve overlaps with an opening period of an intake valve; and   a controller that is configured to:   obtain a blow-through amount of fresh air that blows through a combustion chamber from an intake passage to the exhaust passage;   shorten the valve overlap period so that the blow-through amount becomes equal to or smaller than a predetermined blow-through determination value when the blow-through amount is larger than the blow-through determination value;   determine whether or not the blow-through amount is still larger than the blow-through determination value after shortening the valve overlap period; and   open the waste gate valve when determining the blow-through amount to be still larger than the blow-through determination value after the shortening of the valve overlap period, while, in order to decrease the blow-through amount, prohibiting opening of the waste gate valve until determining the blow-through amount to be still larger than the blow-through determination value after the shortening of the valve overlap period.   
     
     
         4 . The control apparatus for a supercharged internal combustion engine according to  claim 3 , further comprising an air fuel ratio sensor which is disposed in the exhaust passage to detect an air fuel ratio of exhaust gas,
 wherein the controller obtains the blow-through amount based on an output value of the air fuel ratio sensor.   
     
     
         5 . A control apparatus for a supercharged internal combustion engine, comprising:
 a turbo supercharger which includes, in an exhaust passage, a turbine that is operated by exhaust energy;   an exhaust bypass passage which branches off from the exhaust passage at an upstream side portion of the turbine and merges with the exhaust passage at a downstream side portion of the turbine;   a waste gate valve which is capable of switching an opening and closing of the exhaust bypass passage;   a variable valve operating mechanism which is capable of changing a valve overlap period during which an opening period of an exhaust valve overlaps with an opening period of an intake valve;   blow-through amount obtaining means for obtaining a blow-through amount of fresh air that blows through a combustion chamber from an intake passage to the exhaust passage;   overlap period shortening means for shortening the valve overlap period so that the blow-through amount becomes equal to or smaller than a predetermined blow-through determination value when the blow-through amount is larger than the blow-through determination value;   blow-through amount determination means for determining whether or not the blow-through amount is still larger than the blow-through determination value after the valve overlap period has been shortened by the overlap period shortening means; and   WGV control means for opening the waste gate valve when the blow-through amount is determined by the blow-through amount determination means to be still larger than the blow-through determination value, while, in order to decrease the blow-through amount, prohibiting opening of the waste gate valve until the blow-through amount is determined by the blow-through amount determination means to be still larger than the blow-through determination value.