US 9,435,279 B2 · Inter-cylinder air-fuel ratio variation abnormality detection apparatus

Abstract

When two abnormal cylinders are causing variation abnormality, these abnormal cylinders are identified. A parameter correlated with a degree of fluctuation of output from an air-fuel ratio sensor installed in an exhaust passage common to a plurality of cylinders is calculated. Based on the calculated parameter, inter-cylinder air-fuel ratio variation abnormality is detected. The following steps are carried out: (A) a step of forcibly changing amounts of fuel injected for two of the plurality of cylinders and calculating the parameter, (B) a step of changing the two cylinders to other two cylinders and repeating the step (A), and (C) a step of identifying two cylinders causing variation abnormality based on a plurality of the parameters calculated in the steps (A) and (B).

Claims12

Dependent claims

An inter-cylinder air-fuel ratio variation abnormality detection apparatus comprising:

an air-fuel ratio sensor installed in an exhaust passage common to a plurality of cylinders to detect inter-cylinder air-fuel ratio variation abnormality based on a calculated parameter;
and
an electronic control unit configured to carry out:
(A) a step of forcibly changing amounts of fuel injected for two of the plurality of cylinders and calculating the parameter that correlates with a degree of fluctuation of output from the air-fuel ratio sensor;
(B) a step of changing the two cylinders to two other cylinders and repeating the step (A);
and
(C) a step of identifying two cylinders causing the inter-cylinder air-fuel ratio variation abnormality based on a plurality of the parameters calculated in the steps (A) and (B).

4 more elements

An inter-cylinder air-fuel ratio variation abnormality detection apparatus comprising:

a plurality of fuel injectors that inject an amount of fuel for each of a plurality of cylinders;
an air-fuel ratio sensor installed in an exhaust passage common to the plurality of cylinders to detect inter-cylinder air-fuel ratio variation abnormality based on a calculated parameter;
and
an electronic control unit operatively connected to the plurality of fuel injectors, the electronic control unit configured to carry out:
(A) a step of controlling two of the plurality of fuel injectors to forcibly changing the amounts of fuel injected for two of the plurality of cylinders and calculating the parameter that correlates with a degree of fluctuation of output from the air-fuel ratio sensor;
(B) a step of changing the two fuel injectors and two cylinders to two other fuel injectors and two other cylinders and repeating the step (A);
and
(C) a step of identifying two cylinders causing the inter-cylinder air-fuel ratio variation abnormality based on a plurality of the parameters calculated in the steps (A) and (B).

5 more elements

Dependencies are inferred from the claim text.

Inter-cylinder air-fuel ratio variation abnormality detection apparatus

Life of this patent

Inter-cylinder air-fuel ratio variation abnormality detection apparatus

Life of this patent

Abstract

Claims12