초록 ▼

An apparatus for detecting an abnormality in an exhaust gas recirculation control system of an engine is disclosed, which abnormality is brought about by an operation lag of a diaphragm constituting an exhaust gas recirculation valve. The exhaust gas recirculation valve is controlled in dependence o

An apparatus for detecting an abnormality in an exhaust gas recirculation control system of an engine is disclosed, which abnormality is brought about by an operation lag of a diaphragm constituting an exhaust gas recirculation valve. The exhaust gas recirculation valve is controlled in dependence on engine operation information including an intake manifold pressure. Condition to be satisfied for enabling the abnormality decision is detected. Upon satisfaction of the abnormality decision enabling condition, the exhaust gas recirculation valve is forcibly opened and/or closed. On the basis of difference of the intake manifold pressures detected upon enforcive opening/closing of the exhaust gas recirculation valve, possible abnormality of the exhaust gas recirculation control system is decided. A temporal period during which the exhaust gas recirculation valve remains opened after the start of the engine is measured to be subsequently compared with a predetermined reference duration. When the former is greater than the latter, indicating that the exhaust gas recirculation valve is sufficiently warmed up, the abnormality detection processing is enabled. Influence of the temperature characteristic of the diaphragm of the exhaust gas recirculation valve can be excluded from the abnormality decision.

대표청구항 ▼

An abnormality detecting apparatus for detecting occurrence of abnormality in an exhaust gas recirculation control system of an internal combustion engine, comprising: intake pipe means for feeding air to said internal combustion engine; a throttle valve disposed in said intake pipe means to be sele

An abnormality detecting apparatus for detecting occurrence of abnormality in an exhaust gas recirculation control system of an internal combustion engine, comprising: intake pipe means for feeding air to said internal combustion engine; a throttle valve disposed in said intake pipe means to be selectively opened and closed for regulating a flow rate of the air supplied to said internal combustion engine through said intake pipe means; an exhaust gas recirculation pipe for introducing an exhaust gas of said internal combustion engine to said intake pipe means at a location downstream of said throttle valve for thereby recirculating the exhaust gas through said internal combustion engine; an exhaust gas recirculation valve disposed in said exhaust gas recirculation pipe for regulating a recirculation flow rate of the exhaust gas flowing through said exhaust gas recirculation pipe; sensor means for detecting operation state of said internal combustion engine, to thereby output engine operation state information, inclusive of information concerning intake air pressure within said intake pipe means; exhaust gas recirculation control means for controlling said exhaust gas recirculation valve in dependence on said engine operation state information supplied from said sensor means; abnormality decision enabling condition detecting means for detecting satisfaction of an abnormality decision enabling condition for enabling a decision concerning occurrence of abnormality in said exhaust gas recirculation control means on the basis of said engine operation state information; enforcive valve opening/closing means for forcibly opening and/or closing said exhaust gas recirculation valve during a period in which said abnormality decision enabling condition is satisfied; and abnormality decision means for deciding whether abnormality occurs in said exhaust gas recirculation control system on the basis of the intake air pressures detected within said intake pipe means upon enforcive opening/closing of said exhaust gas recirculation valve; said abnormality decision enabling condition detecting means including exhaust gas recirculation duration time measuring means for measuring a temporal period during which said exhaust gas recirculation valve is maintained in the opened state after starting of said internal combustion engine; wherein decision as to occurrence of abnormality in said exhaust gas recirculation control system is enabled when said abnormality decision enabling condition detecting means detects as the abnormality decision enabling condition that said temporal period attains or exceeds a predetermined temporal value.