Fuel Injector Coil Current Control for Eddy Current Loss
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Solution Overview
Problem
In fuel injection devices for internal combustion engines, the electromagnetic force suctioning the movable core is decreased due to energy loss from eddy currents generated in the conductor surrounding the magnetic circuit when the fuel injector is inserted into an attachment hole, leading to inefficiencies in fuel injection.
Innovation Solution
A fuel injection device with a control portion that manages the coil current to increase and hold it at specific target values, reducing eddy current generation by controlling the magnetic flux variation, thereby maintaining a consistent electromagnetic force for efficient fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel injector is inserted deeply into the attachment hole to ensure proper positioning, then the fuel injector can be securely mounted, but the coil portion is surrounded by the conductor of the cylinder head, generating eddy currents that decrease the electromagnetic force
Solution Approach 1:
The patent extracts the harmful interaction by introducing a non-magnetic spacer between the coil portion and the conductor of the cylinder head. This spacer removes the eddy current generation path while maintaining the secure mounting configuration, thus preserving electromagnetic force without compromising mounting security
Solution Approach 2:
The non-magnetic spacer acts as an intermediary element between the coil portion and the cylinder head conductor. It physically separates the magnetic field from the conductor, preventing eddy current generation while allowing the fuel injector to remain securely mounted in the attachment hole
2Force
If the coil current is increased to compensate for eddy current losses, then the electromagnetic force can be maintained, but energy consumption increases
Solution Approach 1:
The patent converts the harmful eddy current effect into a beneficial control opportunity by using the controlled variation of magnetic flux to reduce eddy current generation. The holding control portion maintains coil current at a level that optimizes electromagnetic force while minimizing energy loss, transforming the energy consumption issue into a controlled parameter
3Speed
If the coil current is rapidly increased to improve response speed, then the valve body can open faster, but eddy currents are more strongly generated, causing energy loss
Solution Approach 1:
The patent implements periodic control through two distinct control portions: an increasing control portion for rapid response and a holding control portion for energy-efficient maintenance. This periodic switching between acceleration and maintenance phases achieves fast response while minimizing continuous energy loss from eddy currents
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 solution effectively restricts the decrease in electromagnetic force, enhancing the fuel injection efficiency by minimizing energy loss from eddy currents and ensuring reliable operation of the movable core suction.
Implementation Method 1
The coil is energized to generate a magnetic flux
Implementation Method 2
The stator core forms a part of a magnetic circuit which is a passage of the magnetic flux and generates an electromagnetic force
Implementation Method 3
The movable core is suctioned by the electromagnetic force
Implementation Method 4
An eddy current is generated in the conductor according to a variation in magnetic flux generated in the magnetic circuit
Data Source
AI summary
A fuel injection device includes a fuel injector and a control portion. The fuel injector is inserted into an attachment hole which is placed at a predetermined position of a cylinder head. The fuel injector has a housing in which a coil is provided. At least a part of the housing which accumulates the coil is surrounded over the whole circumference by an inner circumference surface of the attachment hole. The control portion has an increasing control portion and a holding control portion. The increasing control portion increases a current flowing through the coil to a first target value. The holding control portion holds the current to the first target value.