An internal combustion engine system includes a first EGR valve to control flow in a first flow path, and a second EGR valve to control flow in a second flow path. A temperature sensor is disposed in the exhaust gas feedstream upstream of the exhaust purifying device, and a controller is in communication with the internal combustion engine and the temperature sensor and is operatively connected to the first and second EGR valves. The controller executes a routine to monitor the temperature of the exhaust gas feedstream upstream of the exhaust purifying device and control the first valve to control flow of exhaust gas to the air intake system via the first flow path and control the second valve to control flow of exhaust gas to the air intake system via the second flow path based upon the temperature of the exhaust gas feedstream upstream of the exhaust purifying device.

A dual path exhaust gas recirculation (EGR) system for an engine includes a common EGR intake path and first and second low pressure EGR paths including respective first and second EGR valves. The common EGR intake path is connected to the exhaust system downstream of a catalyst and includes an EGR cooler. The first EGR path is coupled directly to the EGR cooler and an inlet of a turbocompressor. The second EGR path is coupled directly to the EGR cooler and the intake system, thereby bypassing the turbocharger and an engine throttle valve. The engine includes an absence of any high pressure EGR path and the EGR valves are controlled such that the first EGR valve is closed and the second EGR valve is open at low engine speed and load operating conditions thereby providing EGR directly to the intake system that bypasses the turbocharger and throttle valve.

An internal combustion engine system includes a first EGR valve to control flow in a first flow path, and a second EGR valve to control flow in a second flow path. A temperature sensor is disposed in the exhaust gas feedstream upstream of the exhaust purifying device, and a controller is in communication with the internal combustion engine and the temperature sensor and is operatively connected to the first and second EGR valves. The controller executes a routine to monitor the temperature of the exhaust gas feedstream upstream of the exhaust purifying device and control the first valve to control flow of exhaust gas to the air intake system via the first flow path and control the second valve to control flow of exhaust gas to the air intake system via the second flow path based upon the temperature of the exhaust gas feedstream upstream of the exhaust purifying device.

A system includes a controller that is configured to respond to engine load being at a designated engine load point by operating an engine with a lower exhaust gas recirculation (EGR) amount and a more advanced fuel injection timing than any other steady-state engine load point when EGR and fuel injection are enabled. The controller is further configured to respond to engine load being within a range of engine load points around the designated engine load point by increasing the EGR amount and retarding fuel injection timing as load increases and as load decreases away from the designated engine load point. This may result in decreased fuel consumption while maintaining emissions below designated levels.

A system includes a controller that is configured to respond to engine load being at a designated engine load point by operating an engine with a lower exhaust gas recirculation (EGR) amount and a more advanced fuel injection timing than any other steady-state engine load point when EGR and fuel injection are enabled. The controller is further configured to respond to engine load being within a range of engine load points around the designated engine load point by increasing the EGR amount and retarding fuel injection timing as load increases and as load decreases away from the designated engine load point. This may result in decreased fuel consumption while maintaining emissions below designated levels.

A method for processing sensor signals in a control unit of a motor vehicle and a control unit for carrying out the method. The control unit is provided for the open-loop and/or closed-loop control of a system and acquires signals from this system. The system is modeled with the aid of a model, at least one value being ascertained for a slow signal based on the model.