Diagnosis apparatus for internal combustion engine
View Patent ↗In a diagnosis apparatus for an internal combustion engine which determines the abnormality of a linear A/F sensor which is disposed on the upstream side of a catalyst of the engine and detects the A/F of exhaust gas, the apparatus includes a response/gain deterioration detection unit that separately detects the response deterioration in which the response of the linear A/F sensor is delayed and the gain deterioration in which the detection sensitivity of the linear A/F sensor is abnormal.
1. A diagnosis apparatus for an internal combustion engine, comprising:
a catalyst deterioration diagnosis mode, which detects deterioration of a catalyst based on outputs of a linear A/F sensor and an A/F sensor, the catalyst being disposed within a path of exhaust gas of the engine, the linear A/F sensor being disposed on an upstream side of the catalyst, and the A/F sensor being disposed on a downstream side of the catalyst; and
a linear A/F sensor deterioration diagnosis mode, in which a frequency of a diagnosis mode for diagnosing the linear A/F sensor is lower than a frequency of a control mode for controlling the A/F;
wherein both the catalyst deterioration diagnosis mode and the linear A/F sensor deterioration diagnosis mode are carried out.
2. A diagnosis apparatus for an internal combustion engine according to claim 1 , wherein the frequency of the A/F deviation of the diagnosis mode for diagnosing the linear A/F sensor in the linear A/F sensor deterioration diagnosis mode is in a range which is equal to or larger than 0 Hz and equal to or less than 1 Hz.
3. A diagnosis apparatus for an internal combustion engine according to claim 1 , wherein the frequency of the A/F deviation of the diagnosis mode for diagnosing the linear A/F sensor in the linear A/F sensor deterioration diagnosis mode is in a range which is equal to or larger than 0.3 Hz and equal to or less than 1 Hz.
4. A diagnosis apparatus for an internal combustion engine according to claim 1 , wherein both the catalyst deterioration diagnosis mode and the linear A/F sensor deterioration diagnosis mode are carried out simultaneously.
5. A diagnosis apparatus for an internal combustion engine, comprising:
a catalyst deterioration diagnosis mode, which detects deterioration of a catalyst based on outputs of a linear A/F sensor and an A/F sensor, the catalyst being disposed within a path of exhaust gas of the engine, the linear A/F sensor being disposed on an upstream side of the catalyst, and the A/F sensor being disposed on a downstream side of the catalyst; and
a linear A/F sensor deterioration diagnosis mode, in which a frequency of a diagnosis mode for diagnosing the linear A/F sensor is lower than a frequency of a control mode for controlling the A/F;
wherein both the catalyst deterioration diagnosis mode and the linear A/F sensor deterioration diagnosis mode are carried out; and
wherein it is determined to be the gain deterioration when a gain deterioration index defined by a ratio between a peak value of an A/F detected by the linear A/F sensor and a peak value of the A/F deviation controlled by the linear A/F sensor deterioration diagnosis mode is out of a predetermined range.
6. A diagnosis apparatus for an internal combustion engine according to claim 5 , wherein gain characteristics of the linear A/F sensor are corrected based on the gain deterioration index.
7. A diagnosis apparatus for an internal combustion engine, comprising:
a catalyst deterioration diagnosis mode, which detects deterioration of a catalyst based on outputs of a linear A/F sensor and an A/F sensor, the catalyst being disposed within a path of exhaust gas of the engine, the linear A/F sensor being disposed on an upstream side of the catalyst, and the A/F sensor being disposed on a downstream side of the catalyst; and
a linear A/F sensor deterioration diagnosis mode, in which a frequency of a diagnosis mode for diagnosing the linear A/F sensor is lower than a frequency of a control mode for controlling the A/F;
wherein both the catalyst deterioration diagnosis mode and the linear A/F sensor deterioration diagnosis mode are carried out; and
wherein it is determined to be the response deterioration when a response deterioration index defined by a ratio between a period of an A/F detected by the linear A/F sensor and a period of the A/F deviation controlled by the linear A/F sensor deterioration diagnosis mode is larger than a predetermined value.
8. A diagnosis apparatus for an internal combustion engine according to claim 7 , wherein gain characteristics of the linear A/F sensor are corrected based on the response deterioration index.
9. A diagnosis apparatus for an internal combustion engine according to claim 1 , wherein the diagnosis of the linear A/F sensor is inhibited when an abnormality of a fuel system of the engine is detected.