Multi-Fuel Engine Transient Fuel Control
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Solution Overview
Problem
Multi-fuel engine systems face transient fuel issues when transitioning between co-fueling modes, leading to torque losses, abnormal combustion, and degraded fuel economy due to the complexity of managing multiple fuels and varying fuel chemistry.
Innovation Solution
Limiting the rate of change in fuel split ratio during transitions between co-fueling modes, allowing gradual adjustments based on engine operating conditions such as temperature, MAP, and fuel volatility to reduce transient fuel effects and improve engine control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fuel split ratio is changed rapidly to take advantage of co-fueling benefits, then fuel economy and emissions can be improved, but transient fuel issues occur leading to torque losses and abnormal combustion
Solution Approach 1:
The patent implements dynamic adjustment of the fuel split ratio based on real-time engine operating conditions. The controller continuously monitors parameters such as engine speed, load, temperature, and pressure, and dynamically transitions between different fuel injection profiles (CNG-only, gasoline-only, or co-fueling modes) to optimize both fuel economy and combustion stability under varying conditions.
Solution Approach 2:
The patent changes the fuel split ratio parameter gradually rather than abruptly. When transitioning between co-fueling modes with different split ratios, the controller adjusts the proportion of CNG and gasoline in a controlled manner, limiting the rate of change to prevent transient fuel issues while still achieving the desired fuel economy improvements.
2Adaptability or versatility
If co-fueling is enabled during all operating conditions, then serendipitous advantages can be achieved, but transient fuel issues and control complexity increase
Solution Approach 1:
The patent segments the operating conditions into distinct regions based on engine speed, load, temperature, and pressure parameters. Different fuel injection profiles are assigned to different operating regions, with co-fueling enabled only in conditions where it provides serendipitous advantages. This segmentation allows the system to manage complexity by making control decisions based on predefined regions rather than continuous complex calculations.
3Measurement precision
If the fuel split ratio is adjusted frequently to match actual fuel in cylinder, then combustion control accuracy can be improved, but transient effects are exacerbated
Solution Approach 1:
The patent uses preliminary action by pre-determining fuel injection profiles for different operating conditions and transitioning between them based on monitored parameters. Rather than making frequent continuous adjustments, the controller switches between predefined profiles that have already been optimized for specific conditions, reducing the number of transitions and associated transient effects while maintaining accurate fuel control.
Data Source
AI summary
Methods are provided for reducing transient fuel issues in a multi-fuel engine system. When transitioning from co-fueling with a first fuel split ratio to co-fueling with an alternate fuel split ratio, the change in fuel split ratio is gradually ramped in over multiple engine cycles. This reduces combustion stability issues and the disturbance potential of a wholesale fuel change.