Air supply control systems for internal combustion engines

Claim 1

An air supply control system for an internal combustion engine comprising: a plurality of superchargers (B9,B10;2,3;109,110) including at least a first supercharger (B9;2;109) and a second supercharger (B10;3;110) constituted as a turbosupercharger having a turbine (8;Ts) disposed in one of separated exhaust passages (37,38;102a,102b) connected with the engine (B11;1;101) and a blower (14;Cs) connected through a shaft with the turbine and disposed in one of separated intake passages (11,13;103a,103b) connected with the engine, an exhaust cutoff valve (B7;20;111) operative selectively to be open and closed respectively for opening and closing the separated exhaust passage (38,102b) in which the turbine of said second supercharger is disposed, an intake air cutoff valve (B8;21;121) operative selectively to be open and closed respectively for opening and closing the separated intake passage (13,103b) in which the blower of said second supercharger is disposed, first actuating means (B5;25,29,32;119,128,129,135) for driving said exhaust cutoff valve to be open and closed selectively, second actuating means (B6;26,30,32;124,126,127,135) for driving said intake air cutoff valve to be open and closed selectively, engine operation detecting means (B1;32,33,34,39;­104,135,161,162) for detecting operating conditions of the engine to produce a first detection output, and actuator control means (B2) in a control unit (32, 135) for controlling, in response to the first detection output from said engine operation detecting means, said first and second actuating means to close both said exhaust cutoff valve and said intake air cutoff valve so that said second supercharger is restrained from supercharging the engine when intake air mass flow fed to the engine is to be relatively small and to open both said exhaust cutoff valve and said intake air cutoff valve so that both of said first and second superchargers work for supercharging the engine when the intake air mass flow fed to the engine is to be relatively large, characterized by engine operation change detecting means (B3) in the control unit (32;135) for detecting, based on the first detection output from said engine operation detecting means, changes in operating condition of the engine between a situation wherein the intake air mass flow fed to the engine is to be relatively small and a situation wherein the intake air mass flow fed to the engine is to be relatively large and producing a second detection output, and valve operation setting means (B4) in the control unit (32;135) for controlling, in response to the second detection output from said engine operation change detecting means, said actuator control means (B2) so that said intake air cutoff valve (B8, 21; 121) is delayed to be open compared with said exhaust cutoff valve (B7, 20, 111) when the operat­ing condition of the engine (B11) is changed into the situation wherein the intake air mass flow fed to the engine (B11) is to be relatively large from the situation wherein the intake air mass flow fed to the engine (B11) is to be relatively small and said intake air cutoff valve (B8: 21; 121) is delayed to be closed compared with said exhaust cutoff valve (B7; 20, 111) when the operating condition of the engine (B11) is changed into the situation wherein the intake air mass flow fed to the engine (B11) is to be relatively small from the situation wherein the intake air mass flow fed to the engine (B11) is to be relatively large.