Fuel Injector Closing-Time Control for Accurate Ballistic Injection
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Solution Overview
Problem
Existing fuel injection systems in internal combustion engines face challenges in accurately metering small amounts of fuel with reduced calibration effort, particularly in maintaining precision over the engine's lifetime and avoiding deviations in fuel quantity due to injector variability.
Innovation Solution
A control device and method for a fuel injector that includes a control unit with a calculation unit, memory, and learning mechanism to determine target closing times and adjust pulse durations based on individual injector characteristics, using correlations and learning modes to adapt to environmental and aging conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the closing time of the fuel injector is determined based on drive voltage and characteristic curves for each injection pulse width, then the accuracy of small fuel injection is improved, but the calibration effort and system complexity increase
Solution Approach 1:
The patent changes the control parameter from pulse width to closing time, and further to closing velocity (derivative of closing time). This parameter transformation simplifies the control approach while maintaining or improving injection accuracy, especially in ballistic operation range where traditional pulse width control becomes complex and injector-specific.
Solution Approach 2:
The patent extracts the essential control characteristic by focusing only on the closing phase of the injector valve. By taking the derivative of the closing time to obtain closing velocity, the system isolates the most critical parameter for accurate fuel metering, eliminating the need for comprehensive characteristic curves for each pulse width.
2Manufacturing precision
If individual characteristic curves are created for each fuel injector, then the manufacturing precision of fuel injection is improved, but the ease of manufacture and calibration deteriorates
Solution Approach 1:
The control system performs self-calibration by automatically determining the closing time characteristic for each injector during operation. The ECU measures the actual closing time from the drive voltage signal and calculates the closing velocity without requiring external calibration equipment or manual procedures, enabling each injector to be individually characterized in-situ.
Solution Approach 2:
The system uses feedback from the actual injector closing behavior (detected via drive voltage signal analysis) to adaptively control the injection process. By continuously monitoring and adjusting based on measured closing times and velocities, the system achieves consistent fuel injection across different injectors without manual calibration.
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 significantly reduces fuel amount deviations between different injectors and injections, requiring minimal calibration effort while ensuring continuous adjustment to maintain accuracy over the engine's operating life.
Implementation Method 1
An injector coil may be arranged between a fixed iron core and a housing of the fuel injector. The fixed iron core, the injector coil and the housing may form an electromagnet.
Implementation Method 2
In a valve closing state in which the injector coil is not energized, the valve body may be urged into the valve seat by a spring force of at least one spring that may bias the valve body in valve closing direction
Data Source
AI summary
The herein described subject matter relates in particular to a control device (150) and a method for controlling a fuel injector (101) attached to an internal combustion engine to allow reducing the deviation of the fuel amount between different injectors/different injections in ballistic operation, the control device (150) comprising a control parameter calculation unit (603), an injection pulse calculation unit (604), an injection pulse compensation unit (605) and at least one memory (607 or 608). The control parameter calculation unit (603) is configured to determine a target closing time for the fuel injector (101) based on a fuel amount to be injected into the internal combustion engine. If the determined target closing time is larger than a maximum closing time of the fuel injector (101) in ballistic operation, the injection pulse calculation unit (604) is configured to calculate a pulse duration for the injector (101) based on a characteristic curve of the fuel injector (101), and to output the calculated pulse duration to the fuel injector (101) for injecting the fuel amount into the internal combustion engine. If the determined target closing time is equal to or smaller than the maximum closing time in the ballistic operation, the injection pulse compensation unit (605) is configured to receive a set of parameters from the at least one memory (607 or 608), to calculate a pulse duration for the fuel injector (101) based on the determined target closing time and the set of parameters; and to output the calculated pulse duration to the fuel injector (101) for injecting the fuel amount into the internal combustion engine.