Hydrogen Engine Fuel Injection Limits for NOx Control
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Solution Overview
Problem
Hydrogen-fueled internal combustion engines face challenges in accurately correcting fuel injection amounts based on air-fuel ratio sensor readings, leading to significant changes in NOx concentration in exhaust gas due to variations in actual air-fuel ratios, which impact exhaust gas properties.
Innovation Solution
A controller for internal combustion engines calculates a base fuel injection amount and sets an upper limit value based on engine load factor, adjusts fuel injection valves, and corrects the relationship between NOx concentration and the upper limit value to maintain optimal air-fuel ratios, thereby limiting exhaust gas deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel injection amount is corrected based on air-fuel ratio sensor detected value, then fuel injection accuracy is improved, but NOx concentration fluctuation increases in hydrogen-fueled engines
Solution Approach 1:
The controller uses feedback from the air-fuel ratio sensor to detect actual air-fuel ratio deviations and dynamically adjusts the upper limit value of fuel injection amount accordingly. When the air-fuel ratio becomes leaner than target, the controller increases the upper limit value to allow more fuel injection, thereby suppressing NOx concentration increases while maintaining accurate fuel control based on sensor feedback.
Solution Approach 2:
The patent implements dynamic adjustment of the upper limit value parameter based on operating conditions and sensor feedback. The upper limit value is not fixed but varies with engine load, rotation speed, and detected air-fuel ratio deviations. This dynamic parameter adjustment allows the system to adapt to changing conditions and prevent excessive NOx generation while maintaining fuel injection accuracy.
2Quantity of substance
If upper limit value of fuel injection amount is increased to compensate for lean air-fuel ratio, then fuel richness is improved, but exhaust gas properties deteriorate due to excessive fuel
Solution Approach 1:
The controller continuously monitors the air-fuel ratio via sensor feedback and adjusts the upper limit value only when necessary to prevent lean conditions. This feedback mechanism ensures that fuel injection amount is increased only to the extent needed to maintain proper air-fuel ratio, preventing excessive fuel injection that would lead to exhaust gas deterioration.
Solution Approach 2:
The system changes the upper limit value parameter dynamically based on detected air-fuel ratio deviations and operating conditions. By adjusting this parameter in response to actual engine state, the system optimizes fuel injection amount to achieve desired fuel richness without exceeding levels that would cause exhaust gas property deterioration.
3Stability of the object's composition
If fuel injection amount is increased to maintain air-fuel ratio, then combustion stability is improved, but exhaust gas properties worsen due to fuel richness
Solution Approach 1:
The air-fuel ratio sensor provides continuous feedback on combustion conditions, allowing the controller to make precise adjustments to fuel injection amount. This feedback ensures that fuel is injected only in the amount necessary to maintain stable combustion, preventing excessive fuel richness that would deteriorate exhaust gas properties while still achieving combustion stability.
Solution Approach 2:
The upper limit value parameter is dynamically adjusted based on combustion conditions and sensor feedback. This parameter change strategy allows the system to optimize fuel injection for combustion stability while setting appropriate boundaries to prevent fuel richness levels that would harm exhaust gas properties.
Data Source
AI summary
A controller and a control method for an internal combustion engine are provided. The internal combustion engine uses hydrogen as fuel. A base value of a fuel injection amount is calculated based on a requested torque. A smaller one of an upper limit value of the fuel injection amount and the base value is set as a target value. The upper limit value corresponds to an engine load factor. A NOx concentration difference is a difference between a NOx concentration in exhaust gas and a reference value for the NOx concentration. When the NOx concentration difference is greater than or equal to a threshold value, a relationship between the engine load factor and the upper limit value is corrected such that the upper limit value decreases.