Failure detection device for blow-by gas recirculation apparatus of engine

摘要

An engine includes a EGR valve to regulate a EGR flow rate. A blow-by gas recirculation passage allows blow-by gas generated in the engine to flow in a surge tank to return to the engine. A PCV valve operates in response to negative pressure to regulate a blow-by gas flow rate in the recirculation passage. During deceleration fuel cutoff of the engine, an ECU holds a throttle valve at a predetermined slight opening degree and controls the EGR valve to be forcibly opened from a valve-closed state to change intake pressure (negative pressure) in the surge tank and determines whether or not the PCV valve is in sticking failure based on changes in intake amount detected by an air flow meter before and after the negative pressure changes.

主权项

1. A failure detection device for a blow-by gas recirculation apparatus of an engine, wherein
the engine includes a combustion chamber, an intake passage, an exhaust passage, a fuel supply unit to supply fuel to the combustion chamber, and an intake regulating valve to regulate an intake amount flowing in the intake passage, the engine is provided with an intake pressure changing unit to change intake pressure in the intake passage downstream of the intake regulating valve and an intake amount detecting unit to detect intake amount flowing in the intake passage upstream of the intake regulating valve to detect an operating condition of the engine, the blow-by gas recirculation apparatus includes a blow-by gas recirculation passage to allow blow-by gas generated in the engine to flow in the intake passage to return to the engine, and a PCV valve configured to be operated in response to negative pressure to regulate a flow rate of blow-by gas in the blow-by gas recirculation passage, the blow-by gas recirculation passage having an outlet connected to the intake passage downstream of the intake regulating valve, and the PCV valve including a pipe-shaped main body, a valve element placed to be able to reciprocate in the main body, and a spring biasing the valve element in a direction to open, and an opening degree of the valve element being determined by balance between negative pressure acting in the main body, a biasing force of the spring and surrounding pressure of the spring, and the failure detection device further includes a failure determining unit configured such that, both during deceleration operation of the engine and when fuel supply by the fuel supply unit is cut off, the failure determining unit holds the intake regulating valve at a predetermined slight opening degree, controls the intake pressure changing unit to change intake pressure in the intake passage downstream of the intake regulating valve, and determines whether or not the PCV valve is failed based on changes in the intake amount detected by the intake amount detecting unit before and after the intake pressure changes.