Fuel Delivery System Volumetric Efficiency Self-Calibration
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Solution Overview
Problem
The existing fuel delivery systems for vehicle engines with direct in-cylinder injection face inaccuracies in measuring higher pressure fuel pump efficiency due to manufacturing variability, wear, and DI pump inlet pressure, leading to inefficient fuel delivery.
Innovation Solution
A method is introduced where the lower pressure pump is operated in pulsed mode to self-learn and measure the higher pressure pump's volumetric efficiency, allowing for accurate efficiency determination by sending a voltage above a threshold value, thereby improving the robustness of vapor detection and fuel rail pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pump model is used to determine volumetric efficiency of the higher pressure pump, then the efficiency can be calculated, but the measurement is sensitive to manufacturing variability, wear, and inlet pressure changes leading to inaccuracies
Solution Approach 1:
The system performs self-calibration by automatically determining the actual volumetric efficiency of the high pressure pump during operation. The controller measures actual fuel delivery against commanded fuel delivery to calculate real-time efficiency metrics, allowing the system to self-correct for manufacturing variations and wear without external intervention or complex modeling
Solution Approach 2:
The system implements continuous feedback by monitoring the actual volumetric efficiency and using this information to adjust fuel delivery commands. The controller compares expected fuel delivery based on pump commands with actual fuel delivery measurements, creating a closed-loop system that compensates for efficiency degradation due to wear or pressure variations
2Measurement precision
If the lower pressure pump operates in pulsed mode to self-learn volumetric efficiency, then the efficiency determination accuracy is improved, but the system complexity increases due to additional control logic and timing requirements
Solution Approach 1:
The system continuously determines volumetric efficiency during normal pump operation rather than requiring separate calibration procedures. By continuously monitoring the relationship between pump commands and actual fuel delivery, the system maintains accurate efficiency data without interrupting fuel supply or requiring additional calibration equipment
Solution Approach 2:
The control system uses the existing fuel pressure sensor and pump command signals as intermediaries to indirectly measure volumetric efficiency. Rather than requiring direct measurement of pump internal conditions, the system uses readily available sensor data and control signals to calculate efficiency, simplifying the measurement approach while maintaining accuracy
3Quantity of substance
If volumetric efficiency is measured during all operating conditions, then more data is collected, but measurements taken when pump inlet pressure is below threshold values are inaccurate
Solution Approach 1:
The system applies different measurement acceptance criteria based on operating conditions. When pump inlet pressure is below the threshold value, the system identifies these measurements as low quality and excludes them from efficiency determination. This local quality assessment ensures that only measurements taken under appropriate conditions contribute to the volumetric efficiency calculation
Solution Approach 2:
The system changes the operational parameters under which efficiency measurements are accepted by introducing a minimum inlet pressure threshold. By requiring that measurements be taken only when inlet pressure exceeds this threshold, the system ensures that all contributing measurements are taken under conditions where the pump operates efficiently and measurements are accurate
Data Source
AI summary
A method for operating a fuel delivery system for an engine is provided. The method includes sending a voltage above a threshold value to a lift pressure pump, determining a volumetric efficiency of the direct injection pump when the lower pressure fuel pump is above a threshold pressure, and controlling the lift pump based on the volumetric efficiency of the direct injection pump.