Piezo Injector Actuation Using Adaptive Current-Voltage Curves
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Solution Overview
Problem
Existing fuel injection systems face inaccuracies due to large component tolerances in the injector and supply lines, leading to undesirable dead times and control tolerances, which affect the precision of fuel injection and increase exhaust emissions.
Innovation Solution
A method and device for actuating a piezo actuator in fuel injection systems that involves identifying and adapting current/voltage characteristic curves based on real-time current and voltage profiles, allowing for precise control signals independent of trapezoidal shapes, and accounting for component variations to improve injection accuracy and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard current forms with predetermined rise and fall times are used to actuate the piezo actuator, then the device complexity is reduced and ease of manufacture is improved, but the injection precision deteriorates and dead times increase
Solution Approach 1:
The patent implements dynamic adaptation of current forms by continuously measuring actual current and voltage profiles during injection processes and using this data to adjust subsequent current forms. This transforms the static, predetermined current profiles into dynamic, adaptive profiles that compensate for component variations in real-time, thereby maintaining injection precision without increasing manufacturing complexity
Solution Approach 2:
The system incorporates feedback mechanisms by measuring the actual current flowing through and voltage applied to the piezo actuator during each injection process. These measurements are fed back to the control unit, which uses them to adapt the current/voltage characteristic curves and optimize subsequent injection cycles, eliminating dead times and improving precision
2Ease of manufacture
If component tolerances are accepted as given, then the manufacturing cost is reduced and ease of manufacture is improved, but the control precision deteriorates and dead times increase
Solution Approach 1:
The patent changes the parameters of the control system by continuously measuring actual current and voltage profiles and using these measurements to adapt the current/voltage characteristic curves. This allows the system to compensate for component tolerances by adjusting control parameters in real-time, thereby maintaining high control precision despite variations in injector and supply line components
3Device complexity
If trapezoidal current forms are used for actuation, then the device complexity is reduced, but the flexibility in injection process control deteriorates
Solution Approach 1:
The system transforms fixed trapezoidal current forms into dynamic, adaptive current profiles by continuously measuring actual system behavior and adjusting subsequent current forms accordingly. This enables flexible adaptation to different injection requirements and component variations while maintaining relatively simple device architecture
Solution Approach 2:
The patent enables flexibility by allowing the control unit to change current form parameters (rise time, fall time, amplitude) based on measured actual profiles and adapted characteristic curves, rather than being constrained to fixed trapezoidal shapes
4Device complexity
If correction is made only on the sum of errors at the end of charging process, then the device complexity is reduced, but the injection precision deteriorates due to ignoring discharging process
Solution Approach 1:
The patent ensures continuous optimization by measuring and adapting during both the charging and discharging processes, rather than making a single correction at the end of charging. This continuous adaptation maintains precision throughout the entire injection cycle
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 enhances the precision of fuel injection, reduces exhaust emissions, and adapts to the actual behavior of the injection system, providing a free setpoint current prescription that optimizes the injection process by filtering out interference frequencies and considering real output stage behavior.
Implementation Method 1
piezoelectrically operated injection valves
Data Source
AI summary
Various embodiments include a method for actuating a piezo actuator of an injection valve of a fuel injection system comprising: determining actuation signals for the piezo actuator using a stored current/voltage characteristic curve for carrying out an injection process; detecting the profile of the current flowing through the piezo actuator during the injection process and the profile of the voltage applied to the piezo actuator during the injection process; adapting the stored current/voltage characteristic curve based at least in part on the detected current profile and the detected voltage profile; and determining actuation signals for the piezo actuator using the stored, adapted current/voltage characteristic curve for carrying out a subsequent injection process.