Unified Fuel Apportionment Controller for Multi-Fuel Engines
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Solution Overview
Problem
Multi fuel engines face complexity in controlling fuel flow rates due to the need to manage multiple fuels and account for changes in fuel quality, requiring significant design effort and accuracy in fuel properties input, which is often not met by traditional proportional-integral controllers.
Innovation Solution
A method and system that determine fuel flow rates for each fuel based on input power, fuel properties, and a specified substitution ratio, with a correction factor calculated for charge density, allowing for accurate and adaptive fuel apportionment using a single engine speed control signal and fluid flow control devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple PI controllers are used to control each fuel type individually, then each fuel rate can be set independently, but the overall control structure becomes complex and requires significant design effort
Solution Approach 1:
The patent combines multiple individual PI controllers into a single unified controller that manages all fuel types (natural gas, diesel, propane) simultaneously. This unified controller receives a single speed error signal and calculates appropriate fuel flow rates for each fuel type based on predetermined substitution ratios, eliminating the need for separate controllers and their associated complex switching logic.
Solution Approach 2:
The unified controller performs multiple functions: it controls the speed of the engine, apports fuel among multiple fuel types according to specified ratios, and adjusts fuel flow rates dynamically. This single controller replaces what would otherwise require multiple specialized controllers, simplifying the overall control architecture while maintaining precise fuel rate control.
2Adaptability or versatility
If a switching strategy is implemented to manage multiple fuel rates, then the composite fuel flow can account for fuel availability, but the design robustness and responsiveness to power requirements become difficult to ensure
Solution Approach 1:
The system pre-establishes substitution ratios for different fuel types (natural gas, diesel, propane) and stores them in the controller memory. These predetermined ratios are prepared in advance, allowing the controller to quickly and reliably calculate appropriate fuel flow rates without requiring complex real-time switching decisions, thereby ensuring both adaptability and reliability.
3Measurement precision
If fuel properties are manually input during refilling, then the fuel flow rate can be determined based on fuel quality, but the accuracy is compromised when fuel quality changes over time
Solution Approach 1:
The controller continuously monitors engine operating parameters such as intake manifold pressure and temperature, and uses these measurements to dynamically calculate and adjust fuel flow rates. This continuous feedback mechanism allows the system to adapt to changing fuel quality conditions in real-time without requiring manual re-input of fuel properties, maintaining accuracy while eliminating the time loss associated with manual monitoring.
Data Source
AI summary
A method for controlling fuel flow in a multi fuel engine is disclosed. An input power for operating the multi fuel engine at a desired engine speed is determined and a fuel flow rate based on the input power, one or more fuel properties and a specified fuel substitution ratio for apportioning the plurality of fuels is determined. Also, a correction factor for the fuel flow rate based on a desired charge density, wherein the desired charge density is based at least on a relationship between an engine load and charge density is determined and a corrected fuel flow rate, based on the determined correction factor, is output to a corresponding actuator of a fluid flow control device for the one of the fuels to cause the corresponding actuator to provide the one of the plurality of fuels at the corrected fuel flow rate.