Failure detection device for exhaust recirculation apparatus of engine with supercharger

A failure detection device for an exhaust recirculation apparatus of an engine with a supercharger,

• the engine including an intake passage, an exhaust passage, and an injector configured to supply fuel to a combustion chamber, the intake passage being provided with an intake regulating valve configured to regulate an intake amount of air flowing in the intake passage,
• the supercharger including:
• (i) a compressor disposed in the intake passage upstream of the intake regulating valve, (ii) a turbine disposed in the exhaust passage, and (iii) a rotary shaft connecting the compressor and the turbine to integrally rotate,
• the exhaust recirculation apparatus including:
• (i) exhaust recirculation passage configured to allow part of exhaust gas discharged from the combustion chamber of the engine to the exhaust passage to flow as exhaust recirculation gas to the intake passage to return to the combustion chamber, and (ii) an exhaust recirculation valve configured to regulate a flow of the exhaust recirculation gas in the exhaust recirculation passage, the exhaust recirculation passage having an inlet connected to the exhaust passage downstream of the turbine and an outlet connected to the intake passage upstream of the compressor,
• the failure detection device being provided in the exhaust recirculation apparatus of the engine, the failure detection device comprising:
• an air flow meter configured to measure the intake amount of air flowing in the intake passage;
• a rotation speed sensor configured to detect a rotation speed of the engine;
• a throttle sensor configured to detect an opening degree of the intake regulating valve;
• and
• an electronic control unit configured to:
• open and close the exhaust recirculation valve based on a predetermined operating condition;
• determine a failure in the exhaust recirculation valve based on changes in the intake amount measured by the air flow meter when the exhaust recirculation valve is opened or closed;
• when the failure is determined in the exhaust recirculation valve, calculate:
• (i) an estimated value of the intake amount based on (1) the rotation speed detected by the rotation speed sensor, and (2) the opening degree detected by the throttle sensor, and (ii) an actual measured value of the intake amount by the air flow meter and
• determine whether the failure of the exhaust recirculation valve occurred in an open state of the exhaust recirculation valve or a closed state of the exhaust recirculation valve by comparing the estimated value and the actual measured value.