Patent ID: 6227182
Filing Date: 2001-05-08
Classification: F02D,F02M,Y02T

Abstract:
In an internal combustion engine equipped with an exhaust-gas recirculation system that recycles part of inert exhaust gas back through the engine, an exhaust gas recirculation control system for executing exhaust-gas recirculation control, comprising:a sensor means for detecting operating conditions of the engine;an air-flow meter for detecting an actual intake-air flow rate (QAC) during EGR addition;an exhaust-gas-recirculation passage means for connecting an exhaust manifold with an intake manifold;an exhaust-gas-recirculation control valve means disposed in said exhaust-gas-recirculation passage means for regulating an EGR rate; andan EGR control means configured to be electronically connected to said sensor means and said exhaust-gas-recirculation control valve means for automatically regulating the EGR rate to a final desired EGR rate; said EGR control means comprising(1) a basic EGR rate arithmetic-calculation section arithmetically calculating a basic EGR rate (MEGRM) as a function of a first predetermined engine operating condition of the operating conditions,(2) a first correction factor arithmetic-calculation section arithmetically calculating a first correction factor (KEGR1) for the basic EGR rate as a function of a second predetermined engine operating condition of the operating conditions except the first predetermined engine operating condition,(3) an intake-air flow rate estimation section estimating an intake-air flow rate (BQACK) from the first predetermined engine operating condition, the basic EGR rate (MEGRM), and the first correction factor (KEGR1),(4) a second correction factor arithmetic-calculation section arithmetically calculating a second correction factor (KEGR2) by comparison of the intake-air flow rate (BQACK) estimated by said intake-air flow rate estimation section with the actual intake-air flow rate (QAC) detected by said air-flow meter, for executing feedback-correction with respect to the basic EGR rate,(5) an EGR rate correction section interrelatively making a first EGR-rate correction based on the first correction factor (KEGR1) and a second EGR-rate correction based on the second correction factor (KEGR2) with respect to the basic EGR rate (MEGRM) to produce the final desired EGR rate (MEGR), and(6) an EGR control section executing exhaust-gas recirculation control on the basis of the final desired EGR rate, so that the EGR rate is regulated to the final desired EGR rate.