Abstract: An intake and exhaust system of an internal combustion engine includes an exhaust gas recirculation passage (35) communicates a part of an exhaust passage (7) downstream of a turbine with a part of an intake passage (6) upstream of a compressor and a cooling circuit (51), the cooling circuit including a first evaporator (52) provided in a part of the exhaust passage downstream of the turbine and upstream of a junction with the exhaust gas recirculation passage and storing a medium, an ejector pump (54) using vapor from the first evaporator as a driving flow, a condenser (57) for cooling and condensing the vapor ejected from the ejector pump and returning the condensed medium to the first evaporator, and a second evaporator (55) provided in the exhaust gas recirculation passage to cool the exhaust gas passing through the exhaust gas recirculation passage by evaporating a medium stored therein with a negative pressure created by the ejector pump.

Abstract: An intake and exhaust system of an internal combustion engine includes an exhaust gas recirculation passage (35) communicates a part of an exhaust passage (7) downstream of a turbine with a part of an intake passage (6) upstream of a compressor and a cooling circuit (51), the cooling circuit including a first evaporator (52) provided in a part of the exhaust passage downstream of the turbine and upstream of a junction with the exhaust gas recirculation passage and storing a medium, an ejector pump (54) using vapor from the first evaporator as a driving flow, a condenser (57) for cooling and condensing the vapor ejected from the ejector pump and returning the condensed medium to the first evaporator, and a second evaporator (55) provided in the exhaust gas recirculation passage to cool the exhaust gas passing through the exhaust gas recirculation passage by evaporating a medium stored therein with a negative pressure created by the ejector pump.

Abstract: In an internal combustion engine in which the valve operating characteristic for intake valves can be switched, and the air-fuel ratio can be switched between a relatively lean level and a relatively rich level, the air-fuel ratio is switched in accordance with a change in engine operating condition.

Abstract: A system for controlling the supercharge pressure in an internal combustion engine having a mechanical supercharger which is connected to the crankshaft of an engine and includes a variable compressing construction capable of varying the internal compression ratio. The system comprises a supercharge pressure varying assembly for varying the supercharge pressure, a detector for detecting the operational condition of the supercharge pressure varying assembly, and a control device for operating the supercharge pressure varying assembly into a supercharge pressure reducing position in response to the detection, by the detector, of the fact that the supercharge pressure varying assembly is in a low level compressing state in an operational condition of the engine in which the mechanical supercharger should be brought into a high level compressing state. Thus, even if an abnormality occurs in the variable compressing assembly, an increase in the temperature of the intake gas in the engine is prevented.

Abstract: A supercharged internal combustion engine includes an intake passage, a supercharger arranged in the intake passage, an exhaust passage, and a catalytic converter arranged in the exhaust passage. A supercharging pressure control system for the engine controls the opening of a supercharging pressure control valve for controlling supercharging pressure of intake air supplied to the engine by the supercharger. When the temperature of the catalytic converter falls outside a predetermined range, the opening of the control valve is controlled in a manner such that the temperature of the catalytic converter is brought into the predetermined range.

Abstract: A method for controlling the supercharge pressure in an internal combustion engine having a mechanical supercharger which is connected to the crankshaft in the engine and in which the internal compression ratio of the supercharger can be varied. In the method, the internal compression ratio of the mechanical supercharge is varied on the basis of at least a preset supercharge pressure and an engine revolution rate. This ensures that the supercharge pressure can be matched with the internal compression ratio to prevent a pulsing, thereby preventing noise from being generated.