Bidirectional Current Waveforms for Solenoid Actuator Flux Reset
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Solution Overview
Problem
Solenoid-activated fuel injectors experience instability and unacceptable repeatability in fuel injection events due to residual magnetic flux caused by persistent eddy currents and magnetic hysteresis, especially when fuel injection events are closely spaced, leading to variations in delivered fuel mass.
Innovation Solution
Applying a bi-directional current waveform for each actuator event, where the current direction is reversed between actuated and rest positions, to rapidly reset residual magnetic flux and improve control over fuel injection, thereby stabilizing fuel flow rates across consecutive events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional unidirectional current waveforms are used for solenoid actuators, then the actuator can be operated with simple control circuits, but residual magnetic flux accumulates causing instability and poor repeatability in consecutive actuator events
Solution Approach 1:
The patent applies periodic bidirectional current waveforms that alternate polarity between consecutive actuator events. This periodic action with alternating positive and negative half-cycles actively counteracts residual magnetic flux accumulation, ensuring consistent actuator performance across multiple events while maintaining controlled complexity through systematic waveform design
Solution Approach 2:
The patent changes the current waveform parameters from unidirectional to bidirectional, incorporating both positive and negative current half-cycles. This parameter change allows the system to actively manage magnetic flux conditions, improving repeatability by preventing flux accumulation while the waveform parameters are carefully controlled to manage circuit complexity
2Productivity
If closely spaced fuel injection events are used to improve combustion efficiency, then engine performance is enhanced, but residual magnetic flux from previous events causes variations in delivered fuel mass
Solution Approach 1:
The bidirectional current waveform with alternating polarity acts periodically to reset residual magnetic flux between closely spaced injection events. This periodic flux reset ensures that each injection event starts with consistent magnetic conditions, maintaining precise fuel mass delivery even when events are closely spaced for improved combustion efficiency
Solution Approach 2:
The patent converts the harmful effect of residual magnetic flux into a beneficial control mechanism. By using bidirectional waveforms that intentionally induce controlled reverse flux, the system actively manages and eliminates unwanted flux accumulation, transforming the flux management challenge into a precision control advantage for closely spaced injections
3Productivity
If high-speed consecutive actuator events are implemented to increase productivity, then output is improved, but magnetic hysteresis and eddy currents cause instability in actuator response
Solution Approach 1:
The alternating bidirectional current waveform provides periodic action that actively manages magnetic flux stability during high-speed consecutive events. The regular alternation between positive and negative half-cycles prevents flux buildup and compensates for hysteresis effects, maintaining stable actuator response even at increased event frequencies for improved 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 approach ensures consistent fuel injection events by mitigating the effects of residual magnetic flux, enhancing the precision and stability of fuel delivery, even during closely spaced injection events, by alternating current polarity to counteract eddy currents and hysteresis effects.
Implementation Method 1
an electromagnetic actuator that receives a control signal to move between a static or rest position and an actuated position in response to an applied electromagnetic force
Implementation Method 2
The residual magnetic flux is produced in response to persistent eddy currents and magnetic hysteresis within the fuel injector
Implementation Method 3
The residual magnetic flux is produced in response to persistent eddy currents and magnetic hysteresis within the fuel injector
Data Source
AI summary
A method for providing consistent actuator events for each of a plurality of consecutive actuator events of an electromagnetic actuator, includes applying a first bi-directional current waveform for a first actuator event and applying a second bi-directional current waveform for a second actuator event immediately subsequent to the first actuator event. The first bi-directional current waveform includes applying current in a first direction when the actuator is commanded to an actuated position and applying current in a reversed second direction when the actuator is commanded to a rest position. The second bi-directional current waveform includes applying current in the reversed second direction when the actuator is commanded to an actuated position and applying current in the first direction when the actuator is commanded to a rest position.