System for determining egr cooler degradation

Abstract

Systems and methods for diagnosing an EGR system are presented. The method provides for indicating EGR system degradation in response to a temperature at an outlet of an EGR cooler. The method may require less calibration effort than a model based diagnostic.

Description

technical field [0001] The present description relates to methods and systems for improving operation and diagnostics of exhaust gas recirculation (Exhaust Gas Recirculation, EGR) systems. This approach may be particularly useful for engines with cooled EGR. Background technique [0002] Engines may include EGR to help reduce engine emissions and improve engine efficiency. In some systems, the EGR may be cooled by a cooler in communication with the engine exhaust passage and the engine intake manifold. The EGR system may further include a bypass valve for directing EGR about the EGR cooler such that EGR is directed from the exhaust passage to the engine intake manifold. Therefore, the EGR system can provide cooled or exhaust temperature EGR gas to the engine according to the engine operating state to improve engine emissions and fuel economy. However, during some conditions it is possible to degrade the EGR cooler and / or the EGR cooler bypass valve. For example, it is po...

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Problems solved by technology

However, the EGR system model may require significant calibration time and may not be well compatible with the physical system during some operating conditions

For example, the EGR temperature estimate may not fit the measured EGR temperature shortly after opening the EGR bypass valve to allow cooled EGR to flow to the engine intake system because it may be difficult to determine when untreated exhaust gas is flowing to the engine How much heat has been extracted from the exhaust in the EGR cooler while the intake manifold

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