Fuel Injection Control for Multi-Cylinder Engine Imbalance
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Solution Overview
Problem
Existing fuel injection systems for multi-cylinder internal combustion engines face challenges in accurately detecting and correcting air-fuel ratio imbalances among cylinders, leading to increased emissions of unburned substances and nitrogen oxides due to erroneous lean corrections caused by selective diffusion of hydrogen.
Innovation Solution
A fuel injection amount control system that acquires a post-correction air-fuel ratio imbalance index value by correcting a pre-correction index value based on the intake air amount, allowing for precise control of fuel injection amounts to maintain a stoichiometric air-fuel ratio, thereby reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is performed using the output value of the upstream air-fuel ratio sensor, then the average air-fuel ratio of the engine is controlled to coincide with the target air-fuel ratio, but erroneous lean corrections occur due to selective diffusion of hydrogen, causing increased emissions
Solution Approach 1:
The patent introduces an intermediary correction mechanism that detects hydrogen selective diffusion effects through the air-fuel ratio sensor output and applies a correction value to compensate for the erroneous lean corrections. This intermediary correction process filters out the harmful effect of hydrogen diffusion while preserving the useful feedback control function.
Solution Approach 2:
The patent changes the parameter used for feedback control by introducing a corrected air-fuel ratio value that accounts for hydrogen selective diffusion. Instead of using the raw sensor output directly, the system adjusts the air-fuel ratio parameter to reflect the true combustion state, thereby eliminating erroneous corrections and reducing emissions.
2Quantity of substance
If a fuel injection valve injects fuel in an amount excessively larger than the designated fuel injection amount, then the air-fuel ratio of the particular cylinder becomes richer, but significant imbalances appear among the air-fuel ratios of individual cylinders
Solution Approach 1:
The patent segments the feedback control into cylinder-specific adjustments. By detecting air-fuel ratio imbalances among individual cylinders and applying correction values specific to each cylinder's condition, the system maintains uniformity in the air-fuel ratio composition across all cylinders while allowing individual fuel injection adjustments.
3Measurement precision
If the air-fuel ratio of the engine is controlled to be leaner to compensate for richer cylinders, then the average air-fuel ratio approaches the target value, but the air-fuel ratio of the richer cylinder remains too rich and emissions increase
Solution Approach 1:
The patent applies local quality control by detecting and correcting air-fuel ratio deviations specific to individual cylinders. Instead of applying a uniform lean correction to all cylinders, the system identifies richer cylinders and applies targeted correction values to those specific cylinders, ensuring each cylinder operates at the optimal air-fuel ratio and preventing emissions increases.
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
The system effectively reduces emissions by accurately representing air-fuel ratio imbalances and adjusting fuel injection amounts to prevent erroneous lean corrections, improving the efficiency of the three-way catalyst in cleaning exhaust gases.
Implementation Method 1
erroneous lean corrections caused by selective diffusion of hydrogen
Implementation Method 2
improving the efficiency of the three-way catalyst in cleaning exhaust gases
Data Source
AI summary
A fuel injection amount control system acquires a pre-correction air-fuel ratio imbalance index value that increases as the degree of ununiformity in the air-fuel ratio among cylinders increases, based on an output value of an upstream air-fuel ratio sensor, and obtains a value (intake air amount correlation value) corresponding to the intake air amount and a value (engine speed correlation value) corresponding to the engine speed over a period in which the pre-correction air-fuel ratio imbalance index value is acquired. Also, a post-correction air-fuel ratio imbalance index value is acquired by correcting the pre-correction air-fuel ratio imbalance index value based on the intake air amount correlation value and the engine speed correlation value, and the air-fuel ratio of the engine is controlled based on the post-correction air-fuel ratio imbalance index value.