Diesel engine exhaust recirculating system diagnostic
AssigneeNissan Motor Co., Ltd.
InventorsHiromichi Miwa, Takashi Shirakawa
Life of this patent
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Abstract
An intake pressure and exhaust pressure of an engine are predicted from a fresh air flowrate in a diesel engine comprising an exhaust gas recirculation system and a sensor for detecting the fresh air flowrate. A fault in the system is diagnosed based on the predicted intake pressure and exhaust pressure. Preferably, fault diagnosis in the exhaust gas recirculation system is based on a differential pressure between the intake pressure and exhaust pressure, or on a comparison of an estimated EGR rate and target EGR rate found from the intake pressure and exhaust pressure, without providing any special sensors. Smoke emission is also reduced by limiting the maximum fuel injection amount of the engine.
Claims14
A device for diagnosing a fault in an exhaust gas recirculation system of a diesel engine, comprising:
- means for detecting a flowrate of fresh air entering said engine,
- means for predicting an intake pressure of said engine from said fresh air flowrate,
- means for predicting an exhaust pressure of said engine from said fresh air flowrate, and
- means for determining whether or not there is a fault in said exhaust gas recirculating system based on said intake pressure and said exhaust pressure.
A device for diagnosing a fault in an exhaust gas recirculation system of a diesel engine, comprising:
- a sensor for detecting a flowrate of fresh air entering said engine, and
- a microprocessor is programmed to:
- predict an intake pressure of said engine from said fresh air intake flowrate,
- predict an exhaust pressure of said engine from said fresh air intake flowrate, and
- determine whether or not there is a fault in the exhaust gas recirculation system based on said intake pressure and exhaust pressure.
Dependencies are inferred from the claim text.