Fuel Injector Balancing via Pressure Drop Learning
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Solution Overview
Problem
Existing fuel injector calibration methods, such as pressure base injector balancing (PBIB), struggle to accurately balance fuel delivery across multiple direct injection events with closely spaced injections, leading to persistent injector variability and reduced engine efficiency.
Innovation Solution
A method that learns fuel mass errors for each injection pulse within a group of fuel injections using total fuel rail pressure drops and inter-injection spacing, adjusting the transfer function for subsequent injection events to account for residual electrical energy and pulse-width effects, enabling precise pulse-width corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple direct injection events are performed with closely spaced injections (less than 6 milliseconds apart), then fuel injection frequency and productivity are improved, but measurement precision of fuel mass error deteriorates because PBIB balancing requires at least 8 milliseconds inter-injection spacing
Solution Approach 1:
The patent segments the fuel injection process into multiple closely-spaced injection events within a single cylinder cycle, allowing the system to deliver multiple injections (e.g., pilot injection, main injection) with intervals less than 6 milliseconds. This segmentation enables higher fuel injection frequency while maintaining the ability to measure and correct fuel mass errors through the controller's learning algorithm that tracks pressure drops across each injection event.
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously monitors fuel rail pressure drops during each injection event and uses this information to learn and correct fuel mass errors. The system measures the actual fuel mass delivered by comparing pressure drops against expected values, then adjusts subsequent injection pulse widths to compensate for deviations, enabling precise measurement even during closely-spaced injections.
2Measurement precision
If PBIB balancing requires pump to be disabled before injector firing to reduce confounding pressure changes, then measurement precision is improved, but loss of time increases due to pump shutdown and startup delays
Solution Approach 1:
The patent applies preliminary action by pre-loading fuel into the fuel rail before injection events and using a high-pressure fuel pump capable of maintaining stable pressure without requiring shutdown. The controller learns fuel mass errors by tracking pressure drops during injection events while the pump remains operational, eliminating the need for pump shutdown and startup delays while maintaining measurement precision through continuous pressure monitoring.
3Device complexity
If injector residual energy from prior injection affects subsequent injection opening time, then device complexity is reduced by using standard injector design, but manufacturing precision of fuel delivery deteriorates due to variable opening times affecting fuel mass
Solution Approach 1:
The patent uses feedback to compensate for injector residual energy effects. The controller monitors fuel rail pressure drops during each injection event and learns the actual fuel mass delivered, including variations caused by residual energy from prior injections. This learning algorithm adjusts subsequent injection pulse widths to account for opening time variations, maintaining precise fuel mass delivery control despite using standard injector designs with residual energy effects.
Solution Approach 2:
The patent changes the control parameter from fixed pulse width to adaptive pulse width based on learned fuel mass errors. The controller adjusts injection pulse width duration dynamically to compensate for variations in injector opening time caused by residual energy, ensuring consistent fuel mass delivery across multiple injection events while maintaining simple standard injector hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively balances injector errors across multiple injection events, even when injections are closer than the minimum required spacing, improving engine performance and reducing emissions by adaptively updating pulse-widths for each injection.
Implementation Method 1
direct fuel injectors (DI) for injecting fuel directly into an engine cylinder
Implementation Method 2
a pressure drop across a fuel rail coupled to an injector with a fuel mass injected by the corresponding injector
Data Source
AI summary
Methods and systems are provided for injector correction learned while a direct injector delivers fuel as a group of fuel injections per cylinder event. The correction is learned using a pressure based injector balancing approach while relies on a sensed pressure drop across the group of fuel injections. Errors for individual pulses of the group of injections is learned as a function of inter-injection spacing and individual pulse-width commands.