Fuel Injector On-Time Calculation via Pressure Prediction
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Solution Overview
Problem
Conventional methods for determining fuel injector on-time are inadequate due to changes in fuel system pressure profiles, which affect the actual volume of fuel delivered, influenced by pressure waves, engine speed, and fuel system pressure set-points, leading to inaccuracies in fuel injection.
Innovation Solution
A system and method that includes a fuel assembly with a controller that predicts the pressure profile in the fuel system and adjusts the fuel injector's open time based on this prediction to ensure accurate fuel delivery, using parameters such as pump command, fuel system set-point, and pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a predetermined two dimensional look-up table is used to determine fuel injector on-time, then the device complexity is reduced, but the measurement precision of fuel delivery accuracy deteriorates due to pressure profile changes
Solution Approach 1:
The patent transitions from a static look-up table approach to a dynamic prediction model that continuously adapts to changing fuel system pressure profiles. The system uses differential equations to model pressure wave propagation and predicts instantaneous pressure at the injector, allowing real-time adjustment of on-time calculations to maintain accuracy under varying operating conditions.
Solution Approach 2:
The system changes the approach from using fixed pressure values in a look-up table to dynamically calculating pressure profiles based on multiple variables including pump command, fuel system set-point, and measured pressure. This parameter-based dynamic calculation allows the system to adapt to changing conditions while maintaining fuel delivery accuracy.
2Device complexity
If pressure profile changes are not compensated, then the device complexity remains low, but the reliability of fuel injection deteriorates due to inaccurate fuel delivery
Solution Approach 1:
The system incorporates feedback by continuously monitoring fuel system pressure and using this information to update the pressure profile prediction. The measured pressure is fed back into the differential equation model to refine the predicted pressure at the injector, creating a closed-loop system that maintains reliability despite pressure variations.
Solution Approach 2:
The system performs preliminary calculation of the pressure profile using differential equations before the actual fuel injection occurs. By predicting the pressure trajectory in advance based on pump command and system characteristics, the system can pre-determine the appropriate on-time adjustment needed to compensate for upcoming pressure changes.
3Measurement precision
If a dynamic pressure prediction model is implemented, then the fuel delivery accuracy is improved, but the device complexity increases due to additional calculations and sensors
Solution Approach 1:
The patent introduces a mathematical model of the fuel system as an intermediary between the simple pressure sensor input and the complex fuel injection control output. The differential equation-based pressure profile prediction acts as a mediator that transforms basic sensor data into accurate on-time calculations without requiring direct complex measurement at the injector.
Solution Approach 2:
The system replaces the need for direct physical pressure measurement at the fuel injector with a mathematical prediction model. Instead of mechanically measuring pressure at multiple points, the system uses differential equations to substitute and calculate the pressure profile based on easily measurable parameters like pump command and fuel system pressure.
Data Source
AI summary
The disclosure provides a system and method to calculate an actual on-time of a fuel injector. The system may include one or more modules located in a control system. The control system uses information available before the fuel injection signal is transmitted to the fuel injector to model and predict a pressure profile in a fuel system that provides high-pressure fuel to the fuel injector, and uses that information along with a fueling command to calculate an actual on-time for the fuel injector.