Fuel Injector Idle Stroke Control for Injection Scatter
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Solution Overview
Problem
Fuel injectors with solenoid drives and idle strokes experience significant scatter in injection quantities during hydraulically ballistic operation due to variations in electrical, magnetic, and mechanical tolerances, especially at shorter injection times and higher pressures, leading to inconsistent fuel delivery.
Innovation Solution
A method involving a precharging phase to establish mechanical contact between the armature and nozzle needle, followed by voltage pulses during boost phases to control the current intensity and minimize scatter, ensuring consistent injection quantities by maintaining defined starting conditions for each injection operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a fuel injector with an idle stroke is used in hydraulically ballistic operation, then the electrical energy required can be reduced, but the injection quantities are subject to a relatively high degree of scatter
Solution Approach 1:
The solenoid is activated in advance during a precharging phase to move the armature into mechanical contact with the nozzle needle before the actual injection. This preliminary positioning ensures consistent starting conditions for each injection event, eliminating the scatter problem while maintaining the energy efficiency of ballistic operation.
2Productivity
If injection times become shorter, then productivity increases, but the relative differences in injection quantity from one injector to another become larger
Solution Approach 1:
By pre-positioning the armature in contact with the nozzle needle before each injection, the system establishes a consistent starting state that is independent of injection duration. This allows short injection times for high productivity while maintaining consistent injection quantities across multiple injectors.
Solution Approach 2:
The system changes the temporal distribution of the actuation signal by introducing a precharging phase separate from the main injection phase. This parameter change in the control strategy decouples the positioning accuracy from the injection duration, allowing short injections without compromising consistency.
3Ease of operation
If the armature is moved only by the armature pulse without magnetic force, then the injector operates in hydraulically ballistic mode, but the injection quantities are subject to high scatter
Solution Approach 1:
The magnetic force is applied in advance during the precharging phase to position the armature accurately in contact with the nozzle needle. Once positioned, the magnetic force can be reduced or switched off for the actual injection, maintaining ballistic operation simplicity while ensuring consistent starting conditions that eliminate scatter.
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
The method reduces injection quantity scatter by maintaining precise control over the armature and nozzle needle movements, achieving consistent and low-scatter fuel injection quantities, even in hydraulically ballistic operations.
Implementation Method 1
a specific temporal voltage or current profile is applied to a fuel injector... the current which generates the magnetic force... Additionally, a movable armature (22) is provided, which can be actuated by means of a solenoid (21)
Implementation Method 2
the solenoid drive has a solenoid (21) and a movable armature (22)... applying a voltage pulse to the solenoid drive during a boost phase until the current intensity of the current flowing through the solenoid reaches a predetermined peak value
Data Source
AI summary
Various embodiments may include a method for actuating a fuel injector with a solenoid drive and a nozzle needle. The solenoid drive has a solenoid and a movable armature. The fuel injector has an idle stroke between the armature and the nozzle needle. An example method includes: applying a precharging current to the solenoid drive during a precharging phase to move the movable armature into mechanical contact with the nozzle needle; and applying a voltage pulse to the solenoid drive during a boost phase until the current intensity of the current flowing through the solenoid reaches a predetermined peak value.