Method of detecting abnormality in exhaust gas recirculation control system of internal combustion engine and apparatus for carrying out the same

In an internal combustion engine equipped with an exhaust gas recirculation control system which includes an exhaust gas recirculation passage connected between an exhaust pipe and an intake pipe of said engine, and an exhaust gas recirculation control valve disposed in said exhaust gas recirculation passage for controlling an exhaust gas recirculation through said recirculation passage,

• an apparatus for detecting occurrence of an abnormality in said exhaust gas recirculation system on the basis of a change in a pressure within said intake pipe which is brought about by actuation of said exhaust gas recirculation control valve, said apparatus comprising:
• suction pressure sensing means disposed in said intake pipe at a position downstream of a throttle valve for detecting a pressure within said intake pipe;
• engine operating state detecting means for detecting whether said engine is being decelerated;
• actuation means responsive to an output signal of said engine operating state detecting means indicative of a deceleration of said engine for temporarily actuating said exhaust gas recirculation control valve to thereby fetch an output signal of said suction pressure sensing means;
• decision means for determining, on the basis of the output signal of said suction pressure sensing means, whether a difference between the suction pressures before and after the actuation of said exhaust gas recirculation control valve reaches a preset value within a predetermined time;
• and
• diagnosis means for determining that said exhaust gas recirculation system suffers an abnormality when decision of said decision means is affirmative.

In an internal combustion engine equipped with an exhaust gas recirculation control system which includes an exhaust gas recirculation passage connected between an exhaust pipe and an intake pipe of said engine, and an exhaust gas recirculation control valve disposed in said exhaust gas recirculation passage for controlling an exhaust gas flow through said recirculation passage,

• a method of detecting occurrence of an abnormality in said exhaust gas recirculation system, said method comprising the steps of;
• detecting a change in a quantity representative of an operating state of said engine, said change being brought about by actuating said exhaust gas recirculation control valve from one to another state;
• measuring a time taken for said change of said quantity to reach a preset value;
• and
• making decision as to occurrence of an abnormality in the exhaust gas recirculation system on the basis of the time as measured.

In an internal combustion engine equipped with an exhaust gas recirculation control system which includes an exhaust gas recirculation passage connected between an exhaust pipe and an intake pipe of said engine, and an exhaust gas recirculation control valve disposed in said exhaust gas recirculation passage for controlling an exhaust gas recirculation through said recirculation passage,

• an apparatus for diagnosing said exhaust gas recirculation system as to occurrence of an abnormality, said apparatus comprising:
• detection means for detecting a change in a quantity representative of an operating state of the engine, said change being brought about by actuating said exhaust gas recirculation control valve from one to another state thereof;
• time measuring means for measuring a time taken for said change of said quantity to reach a preset value;
• and
• decision means for making decision as to occurrence of an abnormality in the exhaust gas recirculation system on the basis of the time as measured.