Exhaust-gas recirculation system and method for exhaust-gas recirculation

摘要

The present disclosure provides systems and methods for adjusting an exhaust gas recirculation rate to provide accurate air-fuel ratio. The disclosure provides a method for calculating an exhaust-gas recirculation rate based on a measured exhaust-gas lambda and a turbocharger speed. Through the use of the exhaust-gas lambda and the turbocharger speed it is possible to calculate an exhaust-gas recirculation rate while dispensing with the difficult and unreliable determination of the mass air flow for determining an exhaust-gas recirculation rate, thus providing a stable method which further reduces fuel consumption and emissions.

主权项

1. An exhaust-gas recirculation system comprising:
a turbocharger; an exhaust-gas lambda sensor arranged downstream of the turbocharger; a turbocharger speed sensor for measuring a speed of the turbocharger; and a non-transitory controller configured to:
calculate a reduced turbocharger speed based on the measured speed of the turbocharger, calculate an exhaust lambda setpoint, and calculate a feedforward exhaust-gas recirculation valve setpoint as a function of the reduced turbocharger speed and one or more of a turbine pressure ratio, an engine pressure ratio, a position of a variable nozzle turbine, and an engine pressure ratio measure,determine an exhaust lambda setpoint error by comparing the exhaust lambda setpoint to an exhaust lambda measured by the exhaust-gas lambda sensor, andactuate an exhaust-gas recirculation valve as a function of the exhaust lambda setpoint error and the feedforward exhaust-gas recirculation valve setpoint.