Air-Fuel Ratio Control Failure Detection with Variation Thresholds
Solution Overview
Problem
Existing air-fuel ratio control systems for internal combustion engines face challenges in accurately determining failures in air-fuel ratio control systems, particularly due to variations in operational state parameters that can lead to erroneous failure determinations and reduced accuracy.
Innovation Solution
The system includes an air-fuel ratio detector, a fuel amount controller, an operational state parameter acquiring device, an extractor, a failure determination device, a variation state parameter calculator, and a determination stopping device, which extract specific frequency components and calculate a variation state parameter reflecting the operational state parameter's history to stop failure determination when the parameter exceeds a threshold, preventing erroneous failures and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If failure determination is continuously executed based on frequency components, then detection capability is improved, but erroneous determination occurs when operational state parameters vary significantly
Solution Approach 1:
The patent changes the parameter of failure determination execution from continuous to conditional based on operational state stability. The control unit calculates variation amounts of operational state parameters (intake air flow rate, engine speed, throttle valve opening amount) and only executes failure determination when these variations are below predetermined thresholds, thereby preventing erroneous determinations during transient states while maintaining detection capability during stable operation
Solution Approach 2:
The patent implements feedback by continuously monitoring operational state parameters and using their variation amounts to control the execution of failure determination. The control unit calculates real-time variation amounts of intake air flow rate, engine speed, and throttle valve opening amount, and uses this feedback information to dynamically adjust whether failure determination should be executed, ensuring accurate detection only when operational conditions are stable
2Productivity
If data acquisition is permitted during significant operational state changes, then productivity is improved, but measurement precision deteriorates due to unstable conditions
Solution Approach 1:
The patent changes the parameter of data acquisition permission from static to dynamic by introducing variation amount thresholds. Instead of continuously acquiring data regardless of operational state, the system calculates variation amounts of operational state parameters and only permits data acquisition for failure determination when these variations are within acceptable ranges, thereby maintaining measurement precision while optimizing productivity
Data Source
AI summary
An air-fuel ratio control apparatus for an internal combustion engine includes an air-fuel ratio detector, a fuel amount controller, an operational state parameter acquiring device, an extractor, a failure determination device, a variation state parameter calculator, and a determination stopping device. The operational state parameter acquiring device is configured to acquire at least one operational state parameter. The failure determination device is configured to execute failure determination of determining a failure in an air-fuel ratio control system of the internal combustion engine based on a specific frequency component extracted by the extractor. The variation state parameter calculator is configured to calculate a variation state parameter. The determination stopping device is configured to stop the failure determination if the variation state parameter calculated by the variation state parameter calculator is equal to or larger than a predetermined threshold value.