An EGR valve is provided in an EGR passage circulating a part of an exhaust gas of an exhaust pipe in an intake pipe as an EGR gas, the EGR valve adjusting an EGR gas amount flowing in the EGR passage when an engine is in an EGR region, a differential pressure device is provided in the intake pipe, the differential pressure device adjusting a differential pressure of the EGR valve, a control unit is provided to control the EGR valve and the differential pressure device, and the EGR control method includes switching whether to adjust the EGR gas amount using the EGR valve and the differential pressure device or to adjust the EGR gas amount using the EGR valve only on the basis of an exhaust gas pressure of an inlet portion of the EGR passage.

A method for propulsion of a vehicle (100) having a combustion engine (101) and a gearbox (103), the engine (101) having a combustion chamber with an inlet for supply of combustion gas and an outlet for evacuation of exhaust gas, the method includes, during a change of gear from a first higher to a second lower gear ratio, increasing the pressure (P.sub.ut) at the chamber outlet (202) with a turbocharger unit and, when the rate of revolution (n) of the combustion engine (101) has at least partially fallen, controlling the turbocharger unit (203) such that the combustion gas pressure (P.sub.in) is increased.

Provided is an engine which is provided with an EGR device, wherein: an actual intake/exhaust gas pressure ratio π1 of an intake-gas pressure P1 to an exhaust-gas pressure P2 is calculated from the detected exhaust-gas pressure P2 and the detected intake-gas pressure P1; an estimated intake/exhaust gas pressure ratio π2 of the intake-gas pressure P1 to the exhaust-gas pressure P2 is calculated from an engine rotational frequency N, and a fuel injection amount F; and, in cases when the actual intake/exhaust gas pressure ratio π1 is less than a prescribed value π0, an EGR gas weight Megr is calculated based on the actual intake/exhaust gas pressure ratio π1, and in cases when the actual intake/exhaust gas pressure ratio π1 is equal to or more than the prescribed value π0, the EGR gas weight Megr is calculated based on the estimated intake/exhaust gas pressure ratio π2.

There is provided a control device for an internal combustion engine including a variable-capacity turbocharger, which has a turbine with a variable nozzle and an actuator that controls the variable nozzle opening degree, and a throttle disposed in an intake passage. The control device includes an electronic control unit (ECU). The ECU include a first control mode as a control mode for the intake air amount. When an air amount range on the high flow rate side including a maximum value of a required air amount for the internal combustion engine is defined as a high air amount range, the ECU controls the actuator and the throttle so as to increase the throttle opening degree while maintaining the variable nozzle at a fully-closed opening degree as the required air amount is increased in the high air amount range on the side of the maximum value in the first control mode.

A method for determining a desired intake manifold pressure of an internal combustion engine by means of an iterative method, wherein a cylinder charge is determined for an intake manifold pressure iterated during the iterative method, and the desired intake manifold pressure is determined as a function of the cylinder air charge that has been determined. In addition, a control device for carrying out the method is provided.

A method for controlling a two-stroke engine operatively connected to a turbocharger, the turbocharger being in fluid communication with the engine to provide a boost pressure thereto, the method including: comparing one of (i) an actual power output of the engine; and (ii) an exhaust temperature representative of an actual temperature of exhaust gas being discharged by the engine, with a corresponding threshold value thereof; in response to the one of the actual power output of the engine and the exhaust temperature being less than the corresponding threshold value: determining a corrective amount of boost pressure to add to the boost pressure of the turbocharger; and controlling the turbocharger to increase the boost pressure of the turbocharger by the corrective amount. Another method for controlling a two-stroke engine operatively connected to a turbocharger is also disclosed.

A rotation adjusting device is controlled such that an engine speed rising rate at the time of acceleration request is made smaller when a turbocharging pressure is lower than the turbocharging pressure is higher. Therefore, an engine speed can be increased at such a low speed that a rising delay in the turbocharging pressure hardly occurs, in a low turbocharging pressure region. Further, when the rotation adjusting device is controlled such that the engine speed rising rate at the time of the acceleration request is set to a value corresponding to the turbocharging pressure, an MG2 torque is controlled to compensate for an insufficient drive torque of an actual engine torque for a request engine torque. Therefore, even when the engine torque is increased slowly by increasing the engine speed at a slow speed, the insufficient drive torque is compensated for by the MG2 torque.

A turbocharger control method and related systems are provided. An operational command to control a level of boost provided by the turbocharger is received. In response to receiving the operational command, an exhaust gas recirculation (EGR) valve is instructed to move from a current position to a desired position. A time taken for the EGR valve to move from the current position to the desired position is determined. A maximum rise rate of exhaust manifold pressure corresponding to a predicted EGR valve position is determined. A permitted exhaust manifold pressure limit for the turbocharger is determined based on a current exhaust manifold pressure, the maximum rise rate of exhaust manifold pressure and the time taken. An operation of the turbocharger is controlled such that the permitted exhaust manifold pressure limit is not exceeded.

A method is disclosed for controlling a compression release brake mechanism in a combustion engine. The method comprises: determining a desired exhaust manifold gas pressure level; continuously monitoring a set of control parameters, including at least two of cylinder pressure, exhaust manifold pressure, turbine speed and turbine expansion ratio; controlling a brake pressure valve and a variable turbine geometry by said control parameters, to drive one of the control parameters to a set first maximum level; and, while maintaining the first of the set of control parameters at the set first maximum level, controlling an exhaust gas recirculation valve by said control parameters in a closed loop to allow exhaust gas to recirculate towards an air inlet system while driving a second of the set of control parameters to a set second maximum level.

When it is determined that there is a likelihood of occurrence of an abnormality in a supercharger, a maximum engine rotation speed and a maximum MG2 rotation speed are changed to a low rotation speed side and operating points of an engine and a rotary machine are controlled such that an engine rotation speed and an MG2 rotation speed are respectively within ranges which do not exceed the changed maximum rotation speeds. Accordingly, even when the supercharger does not operate normally and an abnormal increase in a supercharging pressure occurs, it is possible to curb a high-rotation state of the engine rotation speed and the MG2 rotation speed. As a result, even when an abnormal increase in the supercharging pressure occurs, it is possible to curb a decrease in durability of components.