Fuel Injector Hydraulic Stop Current Control
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Solution Overview
Problem
Fuel injectors with hydraulic stops face issues when fuel pressure is reduced, leading to a disparity between magnetic and hydraulic forces, causing the injector to block fuel injection due to a large pressure drop in the small gap, potentially resulting in incomplete fuel delivery.
Innovation Solution
A method for operating fuel injectors with hydraulic stops involves applying different current profiles to the solenoid drive, adjusting the magnetic force to balance with the hydraulic force, ensuring a larger gap and maintaining fuel injection by determining system parameters indicative of the injected fuel quantity and adjusting the current profiles accordingly to maintain equilibrium between magnetic and hydraulic forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a standard current profile is applied to the solenoid drive, then a predefined injection quantity is achieved under normal fuel pressure, but the magnetic force becomes excessively strong relative to the hydraulic force when fuel pressure is reduced, causing the gap to close and blocking fuel injection
Solution Approach 1:
The patent applies a dynamic current profile that adapts the magnetic force based on detected fuel pressure conditions. When reduced fuel pressure is detected (indicating a disparity between magnetic and hydraulic forces), the control unit modifies the current profile to reduce the magnetic force exerted on the armature, thereby dynamically adjusting the system to maintain proper gap width and reliable fuel injection under varying pressure conditions.
Solution Approach 2:
The patent changes the electrical parameter (current profile) applied to the solenoid drive based on the detected system state. By detecting a disparity between magnetic and hydraulic forces through system parameters and subsequently applying a modified current profile with reduced peak current and/or holding current, the patent adjusts the magnetic force parameter to match the reduced hydraulic force, ensuring the gap remains open and fuel injection continues reliably.
2Manufacturing precision
If the gap between armature and pole piece is kept small to maintain precise control, then the pressure drop in the gap becomes excessively large when fuel pressure is reduced, but enlarging the gap reduces control precision
Solution Approach 1:
The patent modifies the magnetic force parameter through an adapted current profile when reduced fuel pressure is detected. This parameter change allows the system to maintain a larger gap width under low pressure conditions without sacrificing control precision, as the control unit continuously monitors system parameters and adjusts the current profile accordingly to balance magnetic and hydraulic forces.
3Force
If the magnetic force is increased to ensure sufficient opening force, then the gap closes completely under reduced fuel pressure, but reducing the magnetic force may prevent proper opening under normal pressure
Solution Approach 1:
The patent implements a dynamic adjustment of the magnetic force through different current profiles based on detected fuel pressure conditions. Under normal pressure, a standard current profile provides sufficient magnetic force for reliable gap opening. When reduced fuel pressure is detected, the control unit switches to an adapted current profile that reduces the magnetic force to prevent gap closure, thereby maintaining gap opening reliability across varying pressure conditions.
Solution Approach 2:
The patent employs periodic monitoring of system parameters to detect disparities between magnetic and hydraulic forces. Based on this periodic detection, the control unit periodically adjusts the current profile to maintain appropriate magnetic force levels, ensuring the gap remains properly open under varying operating conditions.
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 ensures consistent fuel injection by maintaining a larger gap between the armature and pole piece, allowing for a larger volumetric flow and preventing blockages, thus ensuring correct functioning of the fuel injector even at reduced fuel pressures.
Implementation Method 1
a magnetic force exerted on the armature (4) in the direction of the pole piece (6)
Implementation Method 2
an opposite hydraulic force exerted on the armature (4) by fuel
Data Source
AI summary
Various embodiments include a method for operating a fuel injector comprising: applying a first current to a solenoid to perform a first injection process and inject a predefined injection quantity; determining a value of a system parameter indicating the relationship between the actual fuel quantity and the predefined quantity; determining, on the basis of the value of the system parameter, whether the actually injected fuel quantity is smaller than the predefined fuel quantity by a predefined amount corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and an opposite hydraulic force exerted on the armature by fuel; and if it was determined that the quantities differ by enough, applying a second current to the solenoid to perform a second injection; wherein the second current exerts a lower magnetic force on the armature in the direction of the pole piece.