Fuel Injector Flow Characteristic Evaluation via Common Rail Pressure Control
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Solution Overview
Problem
Current fuel injection systems lack an effective diagnostic tool to analyze the performance of fuel injectors, leading to potential faults such as coking buildup, excessive engine noise, and poor drivability, which can result in drivability problems and excessive emissions.
Innovation Solution
A method and system for evaluating fuel injectors by generating injection commands and pump commands for test cycles, maintaining constant common rail pressure, and processing data to determine flow characteristics of fuel injectors, using a processor and memory element to analyze the performance of each injector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no diagnostic tool is used for fuel injectors, then the system operates without additional complexity, but injector performance degradation goes undetected leading to drivability problems and excessive emissions
Solution Approach 1:
The fuel injection system performs self-diagnosis by using the existing pump and injectors to execute test injection cycles. The control system generates test commands that sequentially activate each injector while measuring its flow characteristics, allowing the system to self-evaluate injector performance without external diagnostic equipment.
Solution Approach 2:
The system implements feedback by measuring the actual fuel flow from each injector during test cycles and comparing it against expected flow characteristics. The control system processes the relationship between pump flow commands and actual injector output to detect deviations indicating coking buildup or performance degradation, then provides diagnostic information about injector health.
2Reliability
If traditional diagnostic methods are used, then injector faults can be detected, but the diagnostic process is time-consuming and requires engine shutdown
Solution Approach 1:
The diagnostic method enables continuous evaluation of injector performance during engine operation without requiring shutdown. The control system executes test injection cycles while the engine runs, maintaining fuel pump operation and measuring injector flow characteristics in real-time, thus eliminating downtime associated with traditional offline diagnostic methods.
3Measurement precision
If sequential attenuation of fuel request schedule is applied to each injector, then individual injector flow characteristics can be measured, but the test cycle complexity increases
Solution Approach 1:
The diagnostic approach segments the evaluation of each injector by sequentially activating one injector at a time while attenuating the fuel request schedule for that specific injector. This segmentation allows isolated measurement of individual injector flow characteristics independent of other injectors, achieving precise measurements through systematic division of the diagnostic process.
Data Source
AI summary
A method for analyzing a fuel injection system includes generating injection commands, including attenuating a predetermined fuel request schedule for a different one of the plurality of injectors in a plurality of test cycles. Fuel is injected according to the injection commands to complete the plurality of test cycles. The processor generates pump commands for the pump to maintain a substantially constant pressure of the common rail during the test cycles. First command data are stored for the plurality of test cycles corresponding to the injection commands sent during the test cycles. Second command data are stored for the test cycles corresponding to the pump commands sent during the test cycles. The processor processes the first command data and the second command data to determine flow characteristics of the plurality of fuel injectors.