Engine Controller Dynamic Air-Fuel Ratio Switching for NOx Reduction
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Solution Overview
Problem
Internal combustion engines using hydrogen gas face increased NOx emissions due to varying air-fuel ratios, necessitating a technique to reduce NOx while maintaining target output.
Innovation Solution
A controller for internal combustion engines sets and selects operating conditions for fuel injection and throttle valves to achieve air excess ratios greater than or equal to 1.2 or less than or equal to 1, optimizing NOx reduction and output based on engine situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If various air-fuel ratios are set according to the situation in an internal combustion engine using hydrogen gas, then the target output can be achieved, but NOx emissions increase
Solution Approach 1:
The patent implements dynamic switching between two operating conditions (first and second conditions) based on real-time engine operating situations. The controller selects which condition to apply by evaluating current engine parameters, thereby dynamically adjusting the air-fuel ratio strategy to prevent NOx increase while maintaining target output.
Solution Approach 2:
The patent changes the air excess ratio parameter between two distinct ranges: greater than or equal to 1.2 in the first operating condition, and 1 or less in the second operating condition. This parameter switching allows the system to achieve target output through different combustion modes without entering the intermediate range where NOx emissions increase.
2Object-generated harmful factors
If air excess ratio is set to greater than or equal to 1.2 to reduce NOx, then NOx emissions decrease, but achieving target output becomes more difficult
Solution Approach 1:
The controller dynamically switches between the first operating condition (air excess ratio ≥ 1.2 for NOx reduction) and the second operating condition (air excess ratio ≤ 1 for output maintenance) based on real-time engine operating situations, allowing the system to achieve target output while minimizing NOx emissions through conditional selection.
Solution Approach 2:
The patent segments the operating conditions into two distinct modes: first condition with air excess ratio ≥ 1.2 for NOx reduction, and second condition with air excess ratio ≤ 1 for output maintenance. This segmentation allows the system to apply the appropriate condition based on current engine state, resolving the contradiction between NOx reduction and output achievement.
3Power
If air excess ratio is set to 1 or less to maintain target output, then target output is achieved, but NOx emissions increase
Solution Approach 1:
The controller implements dynamic condition selection, switching between the second operating condition (air excess ratio ≤ 1 for output maintenance) and the first operating condition (air excess ratio ≥ 1.2 for NOx reduction) based on real-time engine operating situations, thereby achieving target output while preventing NOx increase through intelligent condition selection.
Solution Approach 2:
The patent segments operating conditions into two distinct modes with clear boundaries: second condition with air excess ratio ≤ 1 for output maintenance, and first condition with air excess ratio ≥ 1.2 for NOx reduction. This segmentation eliminates the intermediate range where NOx increases, allowing the system to select the appropriate condition based on current engine state.
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 controller effectively reduces NOx emissions by controlling air excess ratios, promoting lean or rich combustion to minimize NOx production while ensuring target engine output, particularly during the warm-up period of the SCR catalyst.
Implementation Method 1
The internal combustion engine includes a cylinder, a fuel injection valve that supplies hydrogen gas into the cylinder
Implementation Method 2
a throttle valve that adjusts an intake air amount
Data Source
AI summary
A first condition is set to such a condition of a fuel injection amount of a fuel injection valve and an opening degree of a throttle valve that an air excess ratio in a cylinder becomes greater than or equal to a prescribed value set as a value greater than 1.2 while satisfying a target output of an internal combustion engine. A second condition is set to such a condition of the fuel injection amount and the opening degree of the throttle valve that the air excess ratio in the cylinder becomes 1 or less while satisfying the target output of the internal combustion engine. A controller of the internal combustion engine is configured to obtain the first and second operating conditions that correspond to the target output, and select one of the operating conditions in accordance with the operating situation of the internal combustion engine.