Failure detection system of exhaust secondary air supply system of internal combustion engine

A computer program embodied on a computer-readable medium for detecting a failure of an exhaust secondary air supply system of an internal combustion engine, having:

• a catalytic converter installed in an exhaust pipe of an exhaust system of the engine for reducing pollutants from exhaust gases emitted from the engine;
• a conduit connected, at one end, to the exhaust pipe at a location upstream of the catalytic converter;
• an air pump connected to an opposite end of the conduit for supplying air in the conduit;
• air pump operation control means for controlling operation of the air pump;
• valve means provided in the conduit for closing/opening the conduit, the valve means comprises a first valve which opens in response to a negative pressure and a second valve which opens in response to a pressure in the conduit;
• first valve operation control means for controlling operation of the first valve by supplying the negative pressure from the engine;
• prescribed level setting means for setting a prescribed level above a pressure under which the second valve opens;
• and
• a pressure detector which outputs a signal when a pressure in the conduit reaches the prescribed level;
• wherein the computer program comprise the steps of:
• checking the signal from the pressure detector successively with respect to time including at least at a first time when the supply of the negative pressure to the first valve is terminated and at a second time, which is different from the first time, when the air pump is terminated;
• and
• detecting a failure occurring at at least one of the air pump and the valve means based on a result of the checking.

A method for detecting a failure of an exhaust secondary air supply system of an internal combustion engine, having:

• a catalytic converter installed in an exhaust pipe of an exhaust system of the engine for reducing pollutants from exhaust gases emitted from the engine;
• a conduit connected, at one end, to the exhaust pipe at a location upstream of the catalytic converter;
• an air pump connected to an opposite end of the conduit for supplying air in the conduit;
• a valve provided in the conduit for closing/opening the conduit;
• prescribed level setting means for setting a first prescribed level which indicate a pressure below a pressure that opens the valve and a second prescribed level which indicates a second pressure above the pressure that opens the valve;
• and
• a plurality of pressure detectors including at least a first pressure detector which outputs a signal at the first prescribed level and a second pressure detector which outputs a signal at the second prescribed level;
• wherein the method comprises the step of:
• detecting a failure occurring at least one of the air pump and the valve based on operation of the air pump and the output of the pressure detectors.

A method for detecting a failure of an exhaust secondary air supply system of an internal combustion engine, having:

• a catalytic converter installed in an exhaust pipe of an exhaust system of the engine for reducing pollutants from exhaust gases emitted from the engine;
• a conduit connected, at one end, to the exhaust pipe at a location upstream of the catalytic converter;
• an air pump connected to an opposite end of the conduit for supplying air in the conduit;
• air pump operation control means for controlling operation of the air pump;
• valve means provides in the conduit for closing/opening the conduit, the valve means comprises a first valve which opens in response to a negative pressure and a second valve which opens in response to a pressure in the conduit;
• first valve operation control means for controlling operation of the first valve by supplying the negative pressure from the engine;
• prescribed level setting means for setting a prescribed level above a pressure under which the second valve opens;
• and
• a pressure detector which outputs a signal when a pressure in the conduit reaches the prescribed level;
• wherein the method comprise the steps of:
• checking the signal from the pressure detector successively with respect to time including at least at a first time when the supply of the negative pressure to the first valve is terminated and at a second time, which is different from the first time, when the air pump is terminated;
• and
• detecting a failure occurring at at least one of the air pump and the valve means based on a result of the checking.

A system for detecting a failure of an exhaust secondary air supply system of an internal combustion engine, comprising:

• a catalytic converter installed in an exhaust pipe of an exhaust system of the engine for reducing pollutants from exhaust gases emitted from the engine;
• a conduit connected, at one end, to the exhaust pipe at a location upstream of the catalytic converter;
• an air pump connected to an opposite end of the conduit for supplying air in the conduit;
• a valve provided in the conduit for closing/opening the conduit;
• prescribed level setting means for setting a first prescribed level which indicate a pressure below a pressure that opens the valve and a second prescribed level which indicates a second pressure above the pressure that opens the valve;
• a plurality of pressure detectors including at least a first pressure detector which outputs a signal at the first prescribed level and a second pressure detector which outputs a signal at the second prescribed level;
• and
• failure detecting means for detecting a failure occurring at least one of the air pump and the valve based on operation of the air pump and the output of the pressure detectors.

A system for detecting a failure of an exhaust secondary air supply system of an internal combustion engine, comprising:

• a catalytic converter installed in an exhaust pipe of an exhaust system of the engine for reducing pollutants from exhaust gases emitted from the engine;
• a conduit connected, at one end, to the exhaust pipe at a location upstream of the catalytic converter;
• an air pump connected to an opposite end of the conduit for supplying air in the conduit;
• air pump operation control means for controlling operation of the air pump;
• valve means provided in the conduit for closing/opening the conduit, the valve means comprises a first valve which opens in response to a negative pressure and a second valve which opens in response to a pressure in the conduit;
• first valve operation control means for controlling operation of the first valve by supplying the negative pressure from the engine;
• prescribed level setting means for setting a prescribed level above a pressure under which the second valve opens;
• a pressure detector which outputs a signal when a pressure in the conduit reaches the prescribed level;
• and
• failure detecting means for checking the signal from the pressure detector successively with respect to time including at least at a first time when the supply of the negative pressure to the first valve is terminated and at a second time, which is different from the first time, when the air pump is terminated and for detecting a failure occurring at at least one of the air pump and the valve means based on a result of the checking.