Patent ID: 7314041
Filing Date: 2008-01-01
Classification: F02D,F02M,Y02T

Abstract:
1. An EGR control system for an internal combustion engine including at least one cylinder, comprising: a low-temperature gas recirculation device that recirculates exhaust gases emitted from the cylinder into the cylinder, as a low-temperature gas, and is capable of changing a recirculation amount of the low-temperature gas; a high-temperature gas recirculation device that executes at least one of an operation for causing combustion gases generated in the cylinder to remain in the cylinder as a high-temperature gas higher in temperature than the low-temperature gas and an operation for recirculating the high-temperature gas into the cylinder, as an operation for recirculating the high-temperature gas, and is capable of changing a recirculation amount of the high-temperature gas; EGR rate parameter-calculating means for calculating an EGR rate parameter indicative of a ratio of a total recirculated gas amount which is a sum of respective amounts of the low-temperature gas and the high-temperature gas which are recirculated into the cylinder, to a total gas amount which is a sum of the total recirculated gas amount and an amount of fresh air drawn into the cylinder, according to a first operating condition parameter indicative of an operating condition of the engine; target value-setting means for setting a target value of the EGR rate parameter according to a second operating condition parameter indicative of an operating condition of the engine; feedback correction value-calculating means for calculating a feedback correction value for causing the EGR rate parameter to converge to the set target value, with a predetermined feedback control algorithm; gas amount ratio-setting means for setting a ratio of an amount of the low-temperature gas to be recirculated by said low-temperature gas recirculation device to the total recirculated gas amount, and a ratio of an amount of the high-temperature gas to be recirculated by said high-temperature gas-recirculation device to the total recirculated gas amount, according to a third operating condition parameter indicative of an operation condition of the engine; and control means for controlling one of said low-temperature gas recirculation device and said high-temperature gas recirculation device, which recirculates one of the low-temperature gas and the high-temperature gas, of which the set ratio of the amount is larger, according to a larger one of the set ratio of the amount of the low-temperature gas and the set ratio of the amount of the high-temperature gas, and the feedback correction value.