Fuel Injector Calibration for Torque Consistency
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Solution Overview
Problem
Fuel injectors in engines fueled with gaseous fuels, such as natural gas, exhibit variability in fuel delivery, leading to inconsistent torque responses, which is problematic for automated manual transmissions that require precise torque control for smooth gear shifting and reduced wear on components.
Innovation Solution
A method and apparatus for in situ calibration of fuel injectors, which calculates an indicated torque and friction torque to determine a pulse-width correction factor, adjusting the pulse-widths of fuel injector signals to maintain accurate fuel delivery and torque control, even as the engine and transmission operate at zero brake torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fuel injectors are used in heavy-duty trucks fueled with gaseous fuels, then the engine can operate with gaseous fuel capability, but fuel delivery variability occurs leading to inconsistent torque responses
Solution Approach 1:
The system performs preliminary calibration of fuel injector pulse-widths by operating the engine at zero brake torque conditions and measuring actual engine speeds. This preliminary characterization data is stored and used to correct future fuel delivery commands, preventing inconsistent torque responses before they occur during normal operation.
Solution Approach 2:
The system implements feedback by measuring actual engine speed during calibration mode, comparing it to expected engine speed, and using the difference to determine corrective pulse-width adjustments. This feedback loop ensures that fuel delivery variability is compensated for, maintaining consistent torque responses throughout the injector's operational life.
2Extent of automation
If automated manual transmissions are used, then gear shifting can be executed automatically, but precise and repeatable torque amounts are required from the engine which is difficult to achieve with variable fuel delivery
Solution Approach 1:
The system performs preliminary calibration of fuel injector pulse-widths by operating the engine at zero brake torque conditions and measuring actual engine speeds. This preliminary characterization data is stored and used to correct future fuel delivery commands, preventing inconsistent torque responses before they occur during normal operation.
Solution Approach 2:
The system implements feedback by measuring actual engine speed during calibration mode, comparing it to expected engine speed, and using the difference to determine corrective pulse-width adjustments. This feedback loop ensures that fuel delivery variability is compensated for, maintaining consistent torque responses throughout the injector's operational life.
3Device complexity
If fuel injector pulse-widths are not corrected, then the system operates with original factory settings, but torque errors occur leading to poor shift quality and accelerated component wear
Solution Approach 1:
The system performs preliminary calibration of fuel injector pulse-widths by operating the engine at zero brake torque conditions and measuring actual engine speeds. This preliminary characterization data is stored and used to correct future fuel delivery commands, preventing inconsistent torque responses before they occur during normal operation.
Solution Approach 2:
The system performs self-calibration by using its own engine speed measurements during zero brake torque operation to determine the corrective pulse-width adjustments needed. The engine essentially calibrates itself without requiring external testing equipment or complex diagnostic tools, maintaining simplicity while improving reliability.
4Manufacturing precision
If in situ calibration is performed, then fuel injector pulse-widths can be corrected for variability, but the calibration process requires operating the engine at zero brake torque which adds operational steps
Solution Approach 1:
The system performs self-calibration by using its own engine speed measurements during zero brake torque operation to determine the corrective pulse-width adjustments needed. The engine essentially calibrates itself without requiring external testing equipment or complex diagnostic tools, maintaining simplicity while improving reliability.
Data Source
AI summary
An apparatus and method are provided for calibrating injection of fuel into at least one combustion chamber of an internal combustion engine. The internal combustion engine comprises at least one fuel injector and a fuel rail. The fuel rail is pressurized to a fuel rail pressure. The method comprises steps of (a) calculating an indicated torque for the internal combustion engine operating at a target fuelling from inputs comprising a fuelling command; (b) calculating a friction torque for the internal combustion engine from inputs comprising the target engine speed; (c) calculating a torque error from a difference between the indicated torque and the friction torque; and (d) determining a pulse-width correction factor for a first baseline pulse-width applied to actuate the at least one fuel injector whereby the torque error is below a predetermined threshold when the internal combustion engine is operating at the target fuelling.