Fuel Injector Calibration Using Multi-Variable Polynomial Functions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing techniques for calibrating and trimming gaseous fuel injectors in internal combustion engines are inadequate due to their reliance on linear relationships and ideal injector assumptions, leading to errors in fuel delivery and start of injection timing, especially when influenced by multiple engine operating parameters such as gaseous and liquid fuel rail pressures and hydraulic pulse width.
Innovation Solution
A method involving calibration phases to determine multi-variable functions of engine operating conditions, allowing for the calculation of nominal and corrected values of fuel injector family characteristics, which are then used to adjust the fuel injector's performance, taking into account dimensional variations and real-time engine conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional linear calibration techniques are used for gaseous fuel injectors, then the calibration process is simple, but the accuracy of fuel delivery and injection timing is insufficient due to the influence of multiple engine operating parameters
Solution Approach 1:
The patent changes the calibration approach from linear to multi-variable polynomial functions that account for multiple engine operating parameters including gaseous fuel rail pressure, liquid fuel rail pressure, and hydraulic pulse width. This allows the calibration to accurately reflect the non-linear behavior of gaseous fuel injectors under varying operating conditions, significantly improving fuel delivery accuracy and injection timing precision
Solution Approach 2:
The patent extends the calibration from a single-dimension linear approach to a multi-dimensional polynomial approach that simultaneously considers multiple engine operating parameters. By incorporating gaseous fuel rail pressure, liquid fuel rail pressure, and hydraulic pulse width as independent variables in polynomial functions, the calibration captures the complex interactions between parameters that affect injector performance
2Reliability
If ideal injector assumptions are made in calibration, then the calibration process is simplified, but errors in fuel delivery and start of injection timing occur due to dimensional variations in real injectors
Solution Approach 1:
The patent applies local quality by determining separate polynomial calibration functions for different engine operating conditions rather than using a single universal linear calibration. Each operating condition (combinations of gaseous fuel rail pressure, liquid fuel rail pressure, and hydraulic pulse width) has its own calibrated polynomial function that accounts for the specific behavior of the injector under those conditions, thereby improving injection timing accuracy and fuel delivery precision
Solution Approach 2:
The patent performs comprehensive polynomial calibration during the manufacturing phase that anticipates and compensates for dimensional variations in real injectors. By pre-determining calibration coefficients for multiple operating conditions and storing them in lookup tables, the system eliminates the need for complex real-time calculations and ideal injector assumptions, directly improving reliability while maintaining ease of manufacture
3Measurement precision
If multiple engine operating parameters are considered in calibration, then the accuracy of injection behavior correction is improved, but the amount of trim information required increases
Solution Approach 1:
The patent uses polynomial functions of controlled order (second-order or higher) that capture the essential non-linear behavior of the injector without requiring exhaustive calibration for every possible operating condition. By selecting appropriate polynomial orders and using lookup tables with representative operating points, the system achieves high injection behavior accuracy while limiting the quantity of trim information required
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for correcting injection behavior of a fuel injector comprising calculating a nominal value of a fuel injector family characteristic for an average fuel injector from a family of fuel injectors as a multi-variable function of engine operating conditions; calculating a corrected value of the fuel injector family characteristic as a function of the nominal value; and employing the corrected value when actuating the fuel injector to inject fuel.