Fuel Injector Timing Control to Prevent Nozzle Backfiring
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Solution Overview
Problem
Modern injection nozzle designs for gaseous alternative fuels in internal combustion engines are prone to damage due to backfiring, caused by a long combustion phase and non-linear closing behavior, which results in incomplete closure before ignition, leading to combustion during the injection process and nozzle degradation.
Innovation Solution
The method involves electronically determining the length of the period after the injection period has ended to ensure the injection nozzle is fully closed before ignition, using parameters such as injection pressure, pressure drop, and rotational speed to adjust the closing time and prevent backfiring, implemented in an engine control unit with a characteristic map to manage these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the injection period is extended to ensure complete fuel injection, then the fuel injection completeness is improved, but the nozzle closing time is delayed causing combustion to occur during injection which leads to backfiring and nozzle degradation
Solution Approach 1:
The system determines the required period length in advance based on injection pressure, pressure drop, and rotational speed parameters before ignition occurs. This preliminary determination ensures the nozzle has sufficient time to close completely before the fuel-air mixture is ignited, preventing combustion during the injection process and eliminating backfiring that would degrade the nozzle.
Solution Approach 2:
The period length is not fixed but dynamically determined based on operating conditions such as injection pressure, pressure drop across the nozzle, and engine rotational speed. This dynamic adjustment allows the system to optimize the closing time under varying operational conditions, ensuring complete nozzle closure before ignition while adapting to changing engine states.
2Productivity
If the ignition timing is advanced to improve combustion efficiency, then the combustion efficiency is improved, but the combustion may occur while the nozzle is still closing resulting in backfiring
Solution Approach 1:
The system calculates the required period length in advance based on the relationship between injection parameters and nozzle closing behavior. By determining this period before ignition occurs, the system ensures that ignition timing is coordinated with nozzle closure, preventing combustion during the closing process while still achieving efficient combustion.
Solution Approach 2:
The system uses feedback from sensor measurements of injection pressure, pressure drop, and rotational speed to continuously determine the appropriate period length. This feedback mechanism allows the system to adapt ignition timing based on actual operating conditions, ensuring combustion efficiency while preventing backfiring under varying engine states.
3Reliability
If the nozzle closing speed is increased to prevent combustion during closing, then backfiring is prevented, but the injection period must be shortened which may compromise fuel injection completeness
Solution Approach 1:
The system changes multiple parameters simultaneously - injection pressure, pressure drop management, and period length determination - to optimize both nozzle closing speed and injection completeness. By adjusting these parameters based on operating conditions, the system achieves rapid nozzle closure to prevent backfiring while ensuring sufficient fuel injection quantity and completeness.
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 prevents backfiring and nozzle degradation by ensuring the nozzle is fully closed before ignition, thereby extending its lifespan and maintaining engine efficiency.
Implementation Method 1
a gaseous fuel is injected into at least one combustion chamber of the internal combustion engine during an injection period by means of at least one injection nozzle
Implementation Method 2
a fuel-air mixture situated in the combustion chamber is ignited after the expiry of a period commencing at an end point in time of the injection period
Data Source
AI summary
Methods and systems are provided for an engine system. In one example, a method includes adjusting an opening and a closing time of a fuel injector in response to an ignition time of a combustion mixture. The adjusting may include a threshold margin as a further parameter for adjusting the opening and the closing time.