Engine Controller Cylinder Lean Imbalance Detection
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Solution Overview
Problem
Existing engine controllers fail to accurately detect lean abnormalities in cylinders, leading to unstable combustion and emission deterioration, especially when the air-fuel ratio sensor provides incorrect values.
Innovation Solution
A controller that calculates a rotation number difference and estimated imbalance rate to detect lean abnormalities in specific cylinders, using these metrics to adjust fuel injection and EGR control, thereby preventing misfire and emission issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If air-fuel ratio sensor is used to detect air-fuel ratio, then air-fuel ratio control is achieved, but detection accuracy deteriorates when sensor provides incorrect values
Solution Approach 1:
The patent introduces an intermediary detection method using rotation number variation as a mediator to infer lean abnormality. Instead of directly relying on the air-fuel ratio sensor, the system uses rotation number differences between cylinders as an intermediate indicator to detect lean conditions, thereby compensating for sensor inaccuracies.
Solution Approach 2:
The patent substitutes the traditional sensor-based detection system with a mechanical parameter-based detection system. By replacing the air-fuel ratio sensor readings with rotation number variation measurements, the system achieves more reliable lean abnormality detection that is not dependent on sensor accuracy.
2Ease of operation
If conventional air-fuel ratio control is used, then overall engine control is simplified, but cylinder-level lean abnormality detection is lost
Solution Approach 1:
The patent applies segmentation by dividing the engine control into two levels: overall engine control (simplified) and cylinder-level control (precise). The system segments the detection function to identify individual cylinders with lean abnormalities through rotation number variation analysis, while maintaining simple overall control through conventional air-fuel ratio management.
Solution Approach 2:
The patent implements local quality by providing cylinder-specific detection and control for lean abnormalities while maintaining uniform overall control. Each cylinder is monitored individually for rotation number variations, allowing localized intervention in affected cylinders without complicating the overall engine control system.
3Device complexity
If lean abnormality is not detected accurately, then EGR control can be simplified, but combustion stability deteriorates
Solution Approach 1:
The patent applies preliminary action by detecting lean abnormalities before they cause combustion instability. Through continuous monitoring of rotation number variations, the system identifies lean conditions in advance and adjusts EGR control accordingly, preventing combustion instability rather than reacting after it occurs.
Solution Approach 2:
The patent implements feedback by using rotation number variation data to continuously monitor and adjust EGR control. The system feeds back rotation number differences to the control unit, which then modifies EGR valve positioning to maintain combustion stability, creating a closed-loop control system.
Data Source
AI summary
A controller for internal combustion engine includes a rotation number detecting section to detect engine rotation number and an air-fuel ratio detecting section to detect an air-fuel ratio (A/F) of air-fuel mixture and is configured to perform leaning control of the A/F. The controller further includes a rotation number difference calculating section to calculate a difference between a rotation number variation value of a worst cylinder specified as having largest rotation number variation based on the detected rotation number detected and an average value of rotation number variation values of remaining cylinders other than the worst cylinder; an estimated imbalance rate calculating section to calculate an estimated imbalance rate based on the A/F detected by the air-fuel ratio detecting section; and a lean abnormality detecting section to detect lean imbalance abnormality in a specific cylinder based on the calculated rotation number difference and the calculated estimated imbalance rate.