Direct Fuel Injector Pulse Width Adjustment
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Solution Overview
Problem
Fuel injectors in internal combustion engines face challenges in providing a consistent fuel amount when operating in non-linear or ballistic modes, leading to engine air-fuel errors and increased emissions due to deposits and varying fuel flow rates at short pulse widths.
Innovation Solution
The method involves supplying a first and second pulse width to the fuel injector during a cylinder cycle, where the first pulse width operates the injector in a non-linear region and the second in a linear region, adjusting the control parameter based on exhaust lambda to maintain a desired fuel amount and reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a short pulse width is applied to operate the direct fuel injector at elevated fuel pressure, then the fuel flow rate increases and injection duration decreases, but the injector operates in its non-linear or ballistic range where fuel injected varies substantially for small changes in pulse width
Solution Approach 1:
The system dynamically adjusts the fuel injection strategy by switching between single pulse width operation and dual pulse width operation based on real-time operating conditions. The controller determines whether to use one long pulse width or split the injection into a first pulse width (operating in non-linear range) and a second pulse width (operating in linear range), optimizing both fuel flow rate and injection precision for different engine conditions
Solution Approach 2:
The fuel injection process is segmented into multiple pulse widths instead of using a single continuous pulse. The first pulse width operates the injector in the non-linear range to deliver a portion of the required fuel, while the second pulse width operates in the linear range to deliver the remaining fuel with higher precision, effectively dividing the injection task to overcome the limitations of single-mode operation
2Duration of action of moving object
If a short pulse width is used to reduce injection duration, then the injection time decreases, but deposits at the injector nozzle contribute to unintended fuel flow variation
Solution Approach 1:
The system uses feedback from the oxygen sensor (lambda sensor) in the exhaust system to monitor the actual air-fuel ratio. This feedback information is used by the controller to adjust the fuel injection pulse widths and compensate for variations caused by nozzle deposits, ensuring consistent fuel delivery despite injector degradation over time
Solution Approach 2:
The controller changes the injection parameters by applying different pulse width combinations (first and second pulse widths) depending on operating conditions and detected fuel flow characteristics. This parameter adjustment allows the system to adapt to changing injector conditions caused by deposits while maintaining reliable and consistent fuel delivery
3Duration of action of moving object
If the fuel injector is operated in non-linear region, then the injection duration is reduced, but the amount of fuel injected varies substantially for small changes in pulse width
Solution Approach 1:
The fuel injection is segmented into a first pulse width that operates in the non-linear range for rapid fuel delivery and a second pulse width that operates in the linear range for precise fuel metering. This segmentation allows the system to benefit from both the speed of non-linear operation and the precision of linear operation
Solution Approach 2:
The system applies a first pulse width that may be excessive for the total fuel requirement, operating in the non-linear range to quickly deliver a portion of the fuel. The remaining fuel is then delivered with a second, more precisely controlled pulse width in the linear range, ensuring accurate total fuel delivery while maintaining short overall injection duration
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 first pulse width of two pulse widths provided to an injector of a cylinder during a cylinder cycle.