Gaseous Fuel Injector Control for Flow Variability
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Solution Overview
Problem
Gaseous fuel injectors in internal combustion engines face variability in performance due to mechanical, chemical, and electromagnetic differences, leading to fuel delivery variations and reduced linearity, especially at low pulse widths and cold start conditions, with existing solutions like precision calibration and filter use offering limited success.
Innovation Solution
A system comprising a mass flow sensor and controller that adjusts the on-time and magnitude of the injector activation signal based on the actual mass flow rate, allowing for real-time compensation and diagnostic reporting to maintain desired fuel delivery, even under conditions of contamination and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If precision injector calibration on flow rigs during manufacturing is used, then manufacturing precision is improved, but reliability deteriorates as injectors wear and parts change shape
Solution Approach 1:
The system performs preliminary characterization of each injector's flow characteristics during manufacturing to establish baseline parameters. This preliminary data is stored and used for ongoing compensation, allowing the system to anticipate and correct for wear and drift over time rather than relying solely on initial calibration.
Solution Approach 2:
The system implements continuous feedback by measuring actual fuel flow using mass flow sensors and comparing it to desired flow rates. Based on this feedback, the control system dynamically adjusts injector pulse width and activation timing to compensate for wear, contamination, and performance drift, maintaining reliability throughout the injector's service life.
2Reliability
If very strong magnetic opening forces are used, then reliability is improved by overcoming stickiness, but use of energy worsens due to higher peak coil current
Solution Approach 1:
Instead of using constantly strong magnetic forces, the system dynamically adjusts the coil current profile based on real-time measurements of injector performance and operating conditions. The control system modulates current magnitude and duration to provide just enough force to overcome stickiness at any given moment, minimizing energy consumption while maintaining reliable opening.
Solution Approach 2:
The system changes the parameters of the magnetic actuation by adjusting coil current waveform characteristics (magnitude, duration, rise time) based on measured injector response and operating conditions such as temperature and contamination levels. This allows optimal balance between overcoming stickiness and minimizing energy use under varying conditions.
3Reliability
If coalescing filter is used upstream of fuel injectors, then reliability is improved by reducing contaminants, but device complexity increases and servicing requirements arise
Solution Approach 1:
The system performs self-diagnosis and self-compensation for injector performance degradation caused by contaminants. By continuously measuring actual fuel flow and comparing it to expected values, the system can detect and compensate for contamination effects without requiring external filters or manual intervention, effectively making the system self-servicing.
Solution Approach 2:
The control system uses feedback from mass flow sensors to detect performance changes indicative of contamination. Based on this feedback, the system adjusts injection parameters to compensate for flow restrictions caused by contaminants, eliminating the need for preventive filtration while maintaining reliability.
4Manufacturing precision
If stroke is limited to lower value for part-to-part balancing, then manufacturing precision is improved, but productivity worsens due to flow limitation
Solution Approach 1:
The system dynamically determines the optimal stroke for each injector based on real-time measurements of actual versus desired fuel flow. Rather than using a fixed limited stroke for all injectors, the control system continuously adjusts pulse width and timing to achieve the desired flow rate, allowing each injector to operate at its optimal performance point.
Solution Approach 2:
The system changes the operational parameters (pulse width, activation timing, coil current) based on measured injector characteristics and performance. This allows the system to compensate for manufacturing variations and achieve consistent fuel delivery without being constrained by conservative stroke limits, thereby improving both precision and productivity.
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 solution improves injection accuracy and consistency by dynamically adjusting injector operation, reducing fuel delivery variations and enhancing engine performance across different conditions, including cold starts and low temperatures.
Implementation Method 1
A mass flow sensor is associated with the conduit and generates a signal representative of the mass flow rate of the gaseous fuel
Implementation Method 2
Gaseous fuel injectors are known to use solenoid actuators to move a plunger or disc style armature to open an injection valve
Implementation Method 3
The armature has a rubber seal (also known as a shutter) that dynamically seals around a valve seat when the injection valve is closed
Implementation Method 4
Gaseous fuel injectors are known to use solenoid actuators to move a plunger or disc style armature to open an injection valve
Data Source
AI summary
Fuel injection accuracy of gaseous fuel injectors is important for efficient engine operation. However, the performance of the injectors varies from part to part and across their lifetime, and when an injector is under performing according to its specification it is often unknown what is causing the problem. An apparatus for operating a gaseous fuel injector in an engine comprises a mass flow sensor that generates a signal representative of the mass flow rate of the gaseous fuel in a supply conduit in the engine. A controller connected with the injector and the mass flow sensor is programmed to actuate the injector to introduce gaseous fuel into the engine; determine the actual mass flow rate of the gaseous fuel based on the signal representative of the mass flow rate; calculate a difference between the actual mass flow rate and a desired mass flow rate; and adjust at least one of on-time of the gaseous fuel injector and a magnitude of an injector activation signal by respective amounts based on the difference when the absolute value of the difference is greater than a predetermined value.