Exhaust Filter Abnormality Detection Using Periodic Air-Fuel Imbalance
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Solution Overview
Problem
Existing methods for determining filter abnormalities in internal combustion engines can adversely affect the combustion state, leading to inefficiencies and emissions issues.
Innovation Solution
A filter abnormality determination system that includes imbalance control, where the air-fuel ratio of one cylinder is adjusted differently from others, using sensors to detect oxygen concentration in the exhaust gas, and a determination unit to assess filter health without significantly impacting engine combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If air-fuel ratio is changed to determine filter abnormality, then filter abnormality can be detected, but combustion state is adversely affected
Solution Approach 1:
The system performs air-fuel ratio changes periodically at predetermined intervals rather than continuously. The control unit executes a sequence where it changes the air-fuel ratio to a first value, waits for a predetermined time, then changes it to a second value, and repeats this cycle. This periodic approach allows filter abnormality detection while giving the combustion system time to stabilize between measurements, thus minimizing adverse effects on combustion state reliability.
2Measurement precision
If air-fuel ratio is changed frequently for detection, then detection accuracy improves, but fuel efficiency and output performance deteriorate
Solution Approach 1:
The control unit implements periodic air-fuel ratio changes with predetermined intervals between measurements. By spacing out the detection cycles rather than performing continuous or frequent changes, the system maintains adequate detection accuracy while allowing the engine to operate at optimal combustion conditions between measurements, thereby preserving fuel efficiency and output performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate filter abnormality detection while minimizing disruptions to the engine's combustion state, ensuring consistent performance and efficiency.
Implementation Method 1
a sensor that is provided in the exhaust passage so as to face the filter and that outputs a detection value corresponding to an oxygen concentration in an exhaust gas
Data Source
AI summary
A filter abnormality determination system includes: an internal combustion engine having a plurality of cylinders; an exhaust passage connected to the internal combustion engine; a filter provided in the exhaust passage and opposed to the filter and outputting a detection value corresponding to an oxygen concentration in the exhaust gas; and a determination device, wherein the determination device includes a control unit that executes an imbalance control for controlling an air-fuel ratio of one of the plurality of cylinders to a value different from an air-fuel ratio of another of the plurality of cylinders; and a determination unit for determining whether the filter is abnormal based on a detection value of the sensor corresponding to an air-fuel ratio of an exhaust gas of the one cylinder during execution of the imbalance control.