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US 7,597,089 B2Granted
Engine with EGR system
AssigneeMitsubishi Heavy Industries, Ltd.
InventorHiroyuki Endo
Life of this patent
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Abstract
A 4-stroke cycle engine has an EGR system equipped with a particulate filter, an external EGR system, and an exhaust valve sub-lift type internal EGR system. With the engine, reduction of NOx emission by EGR can be achieved without incurring a deterioration in engine durability by enabling operation of the engine with the proper EGR rate over all operating ranges of the engine by making it possible to compensate for reduction in EGR amounts due to a reduced DPF pressure difference which occurs when the recovering operation of the DPF is performed.
Claims4
An engine with an EGR (exhaust gas recirculation) system comprising:
- a particulate filter;
- an EGR conduit for introducing a fraction of exhaust gas flowing through an exhaust gas passage to an inlet air passage of the engine;
- an EGR valve for controlling opening and closing of the EGR conduit;
- a means for detecting an exhaust gas pressure difference in the particulate filter;
- and
- a controller, in which reference values of pressure difference in the particulate filter commensurate with reference values of EGR rate of internal EGR are established, for calculating an EGR amount-to-be-corrected based on a pressure difference deviation between the detected exhaust gas pressure difference and the reference values of pressure difference in the particulate filter, and controlling valve opening of the EGR valve in accordance with the calculated EGR amount-to-be-corrected,
- wherein the controller performs exhaust valve sub-lift type internal EGR by allowing an exhaust valve or exhaust valves to lift by a small lift in an intake stroke to allow a fraction of exhaust gas in an intake passage in a cylinder of the engine to flow back into the cylinder.
4 more elements
Dependencies are inferred from the claim text.