Fuel Injector Flow Correction for Direct Injection Coking
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Solution Overview
Problem
Fuel injector coking leads to non-uniform deposit accumulation, affecting discharge coefficients and fuel flow efficiency in internal combustion engines, particularly in direct injected engines operating at higher pressures.
Innovation Solution
A fuel control system with a control module that adjusts fuel injector constants based on fuel rail pressure differences and injector activation periods, using a comparison module to calculate and adjust fuel injector constants to compensate for coking-related inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fuel injectors operate at higher pressures in direct injected engines, then power and fuel efficiency are improved, but fuel injector coking occurs more severely leading to non-uniform deposit accumulation and degraded discharge coefficients
Solution Approach 1:
The system performs preliminary detection of fuel rail pressure changes during pump deactivation events to predict coking conditions before they severely degrade injector performance. By monitoring pressure drop characteristics in advance, the system can adjust injector constants proactively to compensate for developing coking issues.
Solution Approach 2:
The system establishes a feedback loop where fuel rail pressure measurements during pump deactivation events are used to calculate pressure differences, which then inform adjustments to injector constants. This closed-loop feedback enables continuous adaptation of injector parameters based on actual coking conditions, maintaining reliable fuel delivery despite deposit accumulation.
2Productivity
If fuel injector constants are adjusted to compensate for coking, then fuel flow efficiency is improved, but additional monitoring and control operations increase system complexity
Solution Approach 1:
The control module performs multiple functions using the same fuel rail pressure sensor: it monitors overall fuel rail pressure for engine control and simultaneously detects pressure drops during pump deactivation events for coking detection. This multi-functional use of existing components enables injector constant adjustment without adding dedicated monitoring hardware, thereby limiting complexity increases.
Solution Approach 2:
The system uses its own operational data (fuel rail pressure measurements taken during normal pump deactivation events) to self-diagnose coking conditions and self-adjust injector constants. This self-service approach eliminates the need for external diagnostic equipment or complex additional control systems, achieving improved fuel flow efficiency through intelligent use of existing system resources.
Data Source
AI summary
A fuel control system for an engine includes a control module that includes a fuel rail pressure module and a comparison module. The fuel rail pressure module determines a first fuel rail pressure of a fuel rail after a first event and a second fuel rail pressure of the fuel rail after a second event. The first event includes N conditions, a first of the N conditions comprises deactivation of a fuel pump of the engine, and N is an integer. The second event includes M conditions, a first of the M conditions comprises activation of a fuel injector, and M is an integer. The comparison module adjusts a fuel injector constant of the fuel injector based on the first fuel rail pressure, the second fuel rail pressure, and an injector activation period corresponding to the second event.