Exhaust switch-over valve malfunction detection system of internal combustion engine

A system for detecting malfunctions of an exhaust switch-over valve of an internal combustion engine, for opening/closing a bypass exhaust gas passage, branched from an exhaust pipe of the engine, which stores an adsorbent that adsorbs unburned components of the exhaust gas generated by the engine when the engine is started, comprising:

• a first temperature sensor, installed at the bypass exhaust gas passage, which detects a first temperature at an entrance of the bypass exhaust gas passage;
• a second temperature sensor, installed at the bypass exhaust gas passage, which detects a second temperature at an exit of the bypass exhaust gas passage;
• instruction issuing means for issuing an instruction to operate the switch-over valve to close/open the bypass exhaust gas passage;
• detection period setting means for setting a first detection period within a first period of time during which the bypass exhaust gas passage is closed in response to the instruction to operate the switch-over valve to open the bypass exhaust gas passage and a second detection period within a second period of time during which the bypass exhaust gas passage is closed in response to the instruction to operate the switch-over valve to close the bypass exhaust gas passage;
• temperature comparing means for comparing the first and second detected temperatures to each other within the first and second detection periods;
• and
• valve malfunction determining means for determining whether the switch-over valve malfunctions based on a result of the comparison.

A method of detecting malfunctions of an exhaust switch-over valve of an internal combustion engine, for opening/closing a bypass exhaust gas passage, branched from an exhaust pipe of the engine, which stores an adsorbent that adsorbs unburned components of the exhaust gas generated by the engine when the engine is started, comprising the steps of:

• (a) detecting a first temperature at the bypass exhaust gas passage;
• (b) setting means for setting a detection period based on a state of opening/closing the switch-over valve;
• and
• (c) determining whether the switch-over valve malfunctions based on the first detected temperature during the detection period.

A method of detecting malfunctions of an exhaust switch-over valve of an internal combustion engine, for opening/closing a bypass exhaust gas passage, branched from an exhaust pipe of the engine, which stores an adsorbent that adsorbs unburned components of the exhaust gas generated by the engine when the engine is started, comprising:

• (a) detecting a first temperature at an entrance of the bypass exhaust gas passage;
• (b) detecting a second temperature at an exit of the bypass exhaust gas passage;
• (c) issuing an instruction to operate the switch-over valve to close/open the bypass exhaust gas passage;
• (d) setting a first detection period within a first period of time during which the bypass exhaust gas passage is closed in response to the instruction to operate the switch-over valve to open the bypass exhaust gas passage and a second detection period within a second period of time during which the bypass exhaust gas passage is closed in response to the instruction to operate the switch-over valve to close the bypass exhaust gas passage;
• (e) comparing the first and second detected temperatures with each other within the first and second detection periods;
• and
• (f) determining whether the switch-over valve malfunctions based on a result of the comparison.