Fuel System Aging Compensation via Valve Current Adjustment
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Solution Overview
Problem
Common rail fuel systems in vehicles do not effectively account for normal aging of components, leading to false positive leak tests and unnecessary engine shutdowns, which increase maintenance costs and operator frustration.
Innovation Solution
A fuel system with a controller that adjusts the electrical current supplied to a valve based on pre-firing and firing correction factors to maintain commanded rail pressure, reducing the likelihood of false positive leak tests and accounting for component aging, thereby improving fuel economy and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical fuel system leak tests are performed without accounting for component aging, then leak detection capability is maintained, but false positive leak tests increase leading to unnecessary engine shutdowns
Solution Approach 1:
The system performs preliminary characterization of valve and pump performance during normal operation before leak testing. By establishing baseline electrical current values and pressure characteristics during regular fuel injection cycles, the system prepares aging compensation data in advance, allowing accurate distinction between normal aging and actual leaks during subsequent leak tests
Solution Approach 2:
The system dynamically adjusts leak test thresholds based on measured electrical current values and pressure characteristics that change with component aging. By monitoring how electrical current varies with rail pressure over time and updating reference values accordingly, the system adapts test parameters to reflect current component condition, preventing false positives while maintaining leak detection sensitivity
2Device complexity
If fixed electrical current thresholds are used for leak detection, then leak testing simplicity is maintained, but accuracy decreases due to component aging variations
Solution Approach 1:
The system continuously monitors electrical current values during fuel injection and uses this feedback to update reference current values for leak test thresholds. By comparing actual current measurements against dynamically updated references that account for aging, the system maintains high detection accuracy without requiring complex manual calibration procedures
Solution Approach 2:
The system automatically characterizes its own component aging by monitoring electrical current variations during normal operation and self-adjusts leak test thresholds accordingly. This self-service approach eliminates the need for external calibration equipment or complex manual adjustment procedures while maintaining high measurement precision
3Device complexity
If component aging is not accounted for in rail pressure control, then control system simplicity is maintained, but fuel economy and emissions performance deteriorate
Solution Approach 1:
The system adjusts valve control parameters based on measured electrical current values that reflect component aging. By modifying electrical current supplied to the control valve according to updated reference values, the system maintains precise rail pressure control despite aging, optimizing fuel injection performance for fuel economy and emissions without requiring complex mechanical adjustments
Data Source
AI summary
Various methods and systems are provided for health assessments of a fuel system. In one example, a fuel system includes a low-pressure pump operable to pump fuel from a fuel source at a first pressure, a high-pressure pump operable to increase the first pressure to a second pressure, a valve positioned between the low-pressure pump and the high-pressure pump and operable to control fuel flow to the high-pressure pump, a common fuel rail fluidly coupling the high-pressure pump to a plurality of fuel injectors coupled to cylinders of an engine, and a controller. The controller is operable to adjust an amount of valve electrical current supplied to the valve to reach a commanded pressure of the common fuel rail during cylinder firing conditions, the supplied valve electrical current adjusted based on a valve pre-firing correction factor for the valve obtained based on valve electrical current prior to cylinder firing commencing.