US 5,703,285 A · Diagnosis apparatus and method for an exhaust gas recirculation unit of an internal combustion engine

Abstract

A difference is obtained between a cylinder pressure during the compression stroke when an exhaust gas recirculation control valve is opened, and a cylinder pressure during the compression stroke when the exhaust gas recirculation control valve is closed. An estimated value for this difference is set from a cylinder pressure detected under the closed conditions and an exhaust gas recirculation proportion. When the difference is smaller than the estimated value, it is assumed that the exhaust gas recirculation quantity is not changing in accordance with open/close control, and the occurrence of a fault in the exhaust gas recirculation unit is thus judged.

Claims20

Dependent claims

A diagnosis apparatus for an exhaust gas recirculation unit of an internal combustion engine wherein a portion of the exhaust gas is recirculated back to an intake system via an exhaust gas recirculation passage in which is disposed an exhaust gas recirculation control valve, said apparatus comprising:

a cylinder pressure sensor for detecting a cylinder pressure of the engine;
cylinder pressure sampling means for sampling the cylinder pressure detected by said cylinder pressure sensor within a pre-set crank angle during a compression stroke;
and
diagnosis means for outputting a diagnosis signal indicating the presence or absence of a fault in said exhaust gas recirculation unit, based on the cylinder pressure sampled by said cylinder pressure sampling means and an open/close condition of said exhaust gas recirculation control valve for when said cylinder pressure was sampled.

1 more element

A diagnosis method for an exhaust gas recirculation unit of an internal combustion engine wherein a portion of the exhaust gas is recirculated to an intake system via an exhaust gas recirculation passage in which is disposed an exhaust gas recirculation control valve, said method including:

sampling the cylinder pressure detected by a cylinder pressure sensor in a pre-set sampling timing during a compression stroke, and outputting a diagnosis signal indicating the presence or absence of a fault in said exhaust gas recirculation unit based on the sampled cylinder pressure and an open/close condition of said exhaust gas recirculation control valve for when said cylinder pressure was sampled.

Dependencies are inferred from the claim text.

Diagnosis apparatus and method for an exhaust gas recirculation unit of an internal combustion engine

Life of this patent

Diagnosis apparatus and method for an exhaust gas recirculation unit of an internal combustion engine

Life of this patent

Abstract

Claims20