Apparatus for detecting abnormality of oxygen sensor and controlling air/fuel ratio
First Claim
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1. An apparatus for regulating the emission of exhaust gas discharged from an internal combustion engine, comprising:
- oxygen sensing means for generating an oxygen concentration signal indicating the concentration of exhaust gas discharged from an internal combustion engine;
air/fuel ratio setting means for setting the air/fuel ratio of air to fuel in an air/fuel mixture supplied to the internal combustion engine based on a predetermined threshold value and the value of the oxygen concentration signal during closed loop control and for selectively setting the air/fuel ratio to either rich or lean during open loop control; and
abnormality detection means operable during open loop and closed loop control for determining that the oxygen sensing means is abnormal when the oxygen concentration signal is outside of a predetermined range.
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Abstract
This invention provides apparatus for detecting abnormality of an oxygen sensor accurately and also apparatus for appropriately controlling the air/fuel ratio of air and fuel mixture when an oxygen sensor is abnormal. The apparatus easily and properly detects a deteriorating oxygen sensor, with the use of which exhaust of nitrogen oxides or carbon monoxide increases, and when the oxygen sensor is determined to deteriorate, the feed back control of the air/fuel ratio of air and fuel mixture supplied to an internal combustion engine is preferably performed.
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18 Claims
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1. An apparatus for regulating the emission of exhaust gas discharged from an internal combustion engine, comprising:
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oxygen sensing means for generating an oxygen concentration signal indicating the concentration of exhaust gas discharged from an internal combustion engine; air/fuel ratio setting means for setting the air/fuel ratio of air to fuel in an air/fuel mixture supplied to the internal combustion engine based on a predetermined threshold value and the value of the oxygen concentration signal during closed loop control and for selectively setting the air/fuel ratio to either rich or lean during open loop control; and abnormality detection means operable during open loop and closed loop control for determining that the oxygen sensing means is abnormal when the oxygen concentration signal is outside of a predetermined range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for detecting abnormality of an oxygen sensor that generates an oxygen concentration signal corresponding to the concentration of oxygen discharged from an internal combustion engine, comprising:
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air/fuel ratio setting means for changing the air/fuel ratio of an air/fuel mixture supplied to the internal combustion engine between lean and rich; limit value detecting means for detecting the minimum and maximum of the oxygen concentration signal when the air/fuel ratio setting means changes the air/fuel ratio between lean and rich; and abnormality detection means for determining that the oxygen sensor is abnormal when at least one of the minimum and maximum values detected by the limit value detecting means is within a predetermined range. - View Dependent Claims (16, 17, 18)
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Specification