Control apparatus for internal combustion engine

Abstract

This control apparatus for an internal combustion engine includes: a turbo-supercharger; a port injection valve and an in-cylinder injection valve; and catalysts. The control apparatus determines whether or not blow-by of gas to an exhaust passage from an intake passage through a combustion chamber occurs, or whether or not a condition in which the blow-by of gas is likely to occur is satisfied. If the determination is affirmative, the control apparatus sets the fuel injection timing for the port injection valve or the in-cylinder injection valve so as to execute fuel injection after an exhaust valve is closed. Further, if the aforementioned determination is affirmative, the control apparatus sets the fuel injection amount so that the air-to-fuel ratio defined using the amount of air passing through the intake valve coincides with a value leaner than the stoichiometric air-to-fuel ratio.

1 . A control apparatus for an internal combustion engine, comprising:
 a supercharger that supercharges intake air;   a fuel injection valve that injects fuel into the internal combustion engine;   a catalyst that is installed in an exhaust passage and is capable of purifying exhaust gas;   an air-to-fuel ratio sensor that is installed in the exhaust passage on an upstream side of the catalyst to detect an air-to-fuel ratio of exhaust gas at an upstream of the catalyst;   a variable valve operating mechanism that is capable of adjusting a valve overlap period during which an opening period of an intake valve and an opening period of an exhaust valve overlap with each other;   intake valve passing-through air amount obtaining means for obtaining an amount of air passing through the intake valve;   overlap period adjusting means for adjusting the valve overlap period so that when blow-by of gas to the exhaust passage from an intake passage through a combustion chamber occurs or when a condition in which the blow-by of gas is likely to occur is satisfied, an amount of the blow-by in which the air-to-fuel ratio of exhaust gas detected by the air-to-fuel ratio sensor is equal to or lower than a value obtained by adding a predetermined value to a stoichiometric air-to-fuel ratio is obtained;   injection timing setting means for, if the amount of the blow-by is not obtained by an adjustment of the valve overlap period by the overlap period adjusting means in a case where the blow-by of gas occurs or the condition in which the blow-by of gas is likely to occur is satisfied, setting a fuel injection timing for the fuel injection valve so that fuel injection is executed after the exhaust valve is closed; and   fuel injection amount controlling means for, if the amount of the blow-by is not obtained by an adjustment of the valve overlap period by the overlap period adjusting means in a case where the blow-by of gas occurs or the condition in which the blow-by of gas is likely to occur is satisfied, setting a fuel injection amount so that an air-to-fuel ratio defined using the amount of air passing through the intake valve becomes a value leaner than the stoichiometric air-to-fuel ratio.   
     
     
         2 . The control apparatus for the internal combustion engine according to  claim 1 ,
 wherein the control apparatus for the internal combustion engine further comprises catalyst temperature determination means for determining whether or not a temperature of the catalyst is higher than a predetermined value, and   wherein the fuel injection amount controlling means sets a fuel injection amount so that when the blow-by of gas occurs or the condition in which the blow-by of gas is likely to occur is satisfied and the temperature of the catalyst is higher than the predetermined value, the air-to-fuel ratio defined using the amount of air passing through the intake valve becomes a value leaner than the stoichiometric air-to-fuel ratio.   
     
     
         3 . The control apparatus for the internal combustion engine according to  claim 1 ,
 wherein the fuel injection amount controlling means includes air-to-fuel ratio lean-correction means for correcting the fuel injection amount so that the air-to-fuel ratio of exhaust gas detected by the air-to-fuel ratio sensor becomes a value leaner than the stoichiometric air-to-fuel ratio.   
     
     
         4 . The control apparatus for the internal combustion engine according to  claim 3 ,
 wherein the air-to-fuel ratio lean-correction means further includes lean-degree determination means for, when an amount of the blow-by of gas is large, changing a target air-to-fuel ratio of exhaust gas to a value leaner than that when the amount of the blow-by of gas is small.   
     
     
         5 . The control apparatus for the internal combustion engine according to  claim 4 ,
 wherein the lean-degree determination means changes the target air-to-fuel ratio of exhaust gas to a leaner value so that an air-to-fuel ratio defined using an in-cylinder charged air amount obtained by subtracting the amount of the blow-by of gas from the amount of air passing through the intake valve coincides with the stoichiometric air-to-fuel ratio.   
     
     
         6 . The control apparatus for the internal combustion engine according to  claim 1 ,
 wherein the control apparatus for the internal combustion engine further comprises:   air-to-fuel ratio feedback controlling means for adjusting the fuel injection amount so that the air-to-fuel ratio of exhaust gas detected by the air-to-fuel ratio sensor becomes a predetermined target air-to-fuel ratio;   air-to-fuel ratio feedback suspend means for, when the blow-by of gas occurs or when the condition in which the blow-by of gas is likely to occur is satisfied, suspending an adjustment of the fuel injection amount by the air-to-fuel ratio feedback controlling means; and   in-cylinder air amount obtaining means for obtaining an in-cylinder charged air amount out of the amount of air passing through the intake valve,   wherein the fuel injection amount controlling means sets the fuel injection amount so that when the blow-by of gas occurs or when the condition in which the blow-by of gas is likely to occur is satisfied, an air-to-fuel ratio defined using the in-cylinder charged air amount becomes the stoichiometric air-to-fuel ratio.   
     
     
         7 . The control apparatus for the internal combustion engine according to  claim 1 ,
 wherein the variable valve operating mechanism is capable of changing opening and closing timings of the intake valve and a closing timing of the exhaust valve, and   wherein the overlap period adjusting means executes an adjustment of the closing timing of the exhaust valve in priority to an adjustment of the opening and closing timings of the intake valve when controlling the amount of the blow-by of gas by adjusting the valve overlap period.   
     
     
         8 . The control apparatus for the internal combustion engine according to  claim 1 ,
 wherein the fuel injection valve includes a first fuel injection valve that injects fuel into the intake passage and a second fuel injection valve that injects fuel into a cylinder, and   wherein the control apparatus for the internal combustion engine further comprises fuel injection valve selection means for selecting the second fuel injection valve as a fuel injection valve that is used when fuel injection control is performed by the fuel injection timing setting means and the fuel injection amount controlling means.   
     
     
         9 . The control apparatus for the internal combustion engine according to  claim 1 ,
 wherein the control apparatus for the internal combustion engine further comprises gas blow-by determination means for determining whether or not the blow-by of gas occurs, or whether or not the condition in which the blow-by of gas is likely to occur is satisfied, and   wherein the gas blow-by determination means determines that the blow-by of gas is occurring when the air-to-fuel ratio of the exhaust gas detected by the air-to-fuel ratio sensor is leaner than or equal to a sum of the stoichiometric air-to-fuel ratio and a predetermined value.   
     
     
         10 . A control apparatus for an internal combustion engine, comprising:
 a supercharger that supercharges intake air;   a fuel injection valve that injects fuel into the internal combustion engine;   a catalyst that is installed in an exhaust passage and is capable of purifying exhaust gas;   an air-to-fuel ratio sensor that is installed in the exhaust passage on an upstream side of the catalyst to detect an air-to-fuel ratio of exhaust gas at an upstream of the catalyst;   a variable valve operating mechanism that is capable of adjusting a valve overlap period during which an opening period of an intake valve and an opening period of an exhaust valve overlap with each other; and   a controller that is programmed to:   obtain an amount of air passing through the intake valve;   adjust the valve overlap period so that when blow-by of gas to the exhaust passage from an intake passage through a combustion chamber occurs or when a condition in which the blow-by of gas is likely to occur is satisfied, an amount of the blow-by in which the air-to-fuel ratio of exhaust gas detected by the air-to-fuel ratio sensor is equal to or lower than a value obtained by adding a predetermined value to a stoichiometric air-to-fuel ratio is obtained;   set a fuel injection timing for the fuel injection valve so that fuel injection is executed after the exhaust valve is closed if the amount of the blow-by is not obtained by an adjustment of the valve overlap period in a case where the blow-by of gas occurs or the condition in which the blow-by of gas is likely to occur is satisfied; and   set a fuel injection amount so that an air-to-fuel ratio defined using the amount of air passing through the intake valve becomes a value leaner than the stoichiometric air-to-fuel ratio if the amount of the blow-by is not obtained by an adjustment of the valve overlap period in a case where the blow-by of gas occurs or the condition in which the blow-by of gas is likely to occur is satisfied.