Fuel Injector Transfer Function Adjustment for Air-Fuel Ratio Control
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Solution Overview
Problem
Fuel injector variability due to nozzle deposits and differences in nozzle holes leads to engine air-fuel ratio errors, especially in ballistic operating regions where fuel flow is non-linear, necessitating re-characterization of fuel injector flow during an engine's life cycle.
Innovation Solution
Adjusting the fuel injector transfer function or gain based on exhaust lambda and fuel fraction provided to the cylinder, allowing for operation in ballistic regions while minimizing air-fuel ratio disturbances by separating and adapting errors in the second fuel injector's transfer function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single transfer function is used for all fuel injectors, then the system is simple to operate, but fuel injector variability causes engine air-fuel ratio errors
Solution Approach 1:
The patent applies parameter changes by adjusting the transfer function parameters for individual fuel injectors based on their actual performance characteristics. Each injector receives a customized transfer function with modified parameters that account for manufacturing variations, nozzle deposits, and aging effects, thereby maintaining accurate air-fuel ratio control while managing injector variability.
Solution Approach 2:
The patent implements local quality by applying different transfer functions to different fuel injectors based on their individual characteristics. Instead of using a uniform transfer function across all injectors, the system tailors the transfer function parameters to each specific injector's performance, addressing local variations in injector behavior caused by manufacturing tolerances and degradation over time.
2Adaptability or versatility
If fuel injector operates in ballistic operating region, then pulse width range is expanded, but non-linear fuel flow causes additional fuel flow differences
Solution Approach 1:
The patent addresses ballistic operating region challenges by implementing parameter changes in the transfer function that specifically account for non-linear fuel flow characteristics. The transfer function parameters are adjusted to compensate for the non-linear relationship between pulse width and fuel flow in the ballistic region, enabling accurate control across the expanded pulse width range while maintaining fuel flow precision.
3Device complexity
If fuel injector transfer function includes errors, then air-fuel ratio control is simplified, but engine air-fuel ratio varies significantly
Solution Approach 1:
The patent employs feedback mechanisms to detect and correct transfer function errors. By monitoring actual fuel injector performance and comparing it against the commanded values, the system identifies deviations and adjusts the transfer function parameters accordingly. This feedback loop enables the system to maintain accurate air-fuel ratio control while accounting for manufacturing errors and injector degradation over time.
Data Source
AI summary
Systems and methods for improving fuel injection of an engine that includes a cylinder receiving fuel from two different fuel injectors is disclosed. In one example, a transfer function or gain of a direct fuel injector is adjusted in response to an exhaust lambda value and a fraction of fuel supplied to a cylinder during a cylinder cycle.