Fuel Injector Drive Current Control for Stable Half-Lift Injection
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Solution Overview
Problem
The accuracy of the injection amount in a half-lift state is degraded due to increased gradients of the injection pulse width and amount, and the needle colliding with the fixed core causes the valve body to bound, leading to non-linear control and increased Particulate Number (PN), which affects the control accuracy and continuity of the injection amount.
Innovation Solution
A drive device for a fuel injection device that stabilizes the valve body behavior in the half-lift state by reducing gradients of the injection pulse width and amount, using a configuration with multiple springs and a controlled current supply to minimize collisions and ensure consistent injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high voltage is applied to the coil to rapidly raise the current and generate magnetic flux, then the valve body can be quickly actuated, but the gradient of the displacement amount increases and the injection amount accuracy is degraded
Solution Approach 1:
The patent applies dynamic voltage control by switching between high voltage (for rapid current rise and quick valve actuation) and low voltage (for stable current maintenance and precise injection control). This dynamic voltage adjustment allows the system to achieve both fast response and high precision injection amount control by adapting the voltage level to the specific operational phase.
2Speed
If the magnetic attraction force is increased to improve valve response, then the valve body moves faster, but the needle collides with the fixed core causing the valve body to bound and control linearity is lost
Solution Approach 1:
The patent employs cushioning measures by controlling the current waveform to reduce the magnetic attraction force gradient as the needle approaches the fixed core. This prevents excessive collision force and reduces valve body bounding, thereby maintaining control linearity while still achieving fast valve response.
Solution Approach 2:
The patent changes the current waveform parameters dynamically during the valve actuation process. By adjusting the current rise rate and maintaining appropriate current levels, the system optimizes the magnetic attraction force to achieve fast valve response without causing excessive needle collision and valve body bounding.
3Speed
If the injection pulse width gradient is increased to improve response time, then the valve opens faster, but the injection amount change amount increases and control resolution is exceeded
Solution Approach 1:
The patent applies dynamic voltage control to manage the injection pulse width gradient. By using high voltage initially for rapid valve opening and then switching to low voltage for precise current maintenance, the system achieves fast valve response while keeping the injection amount change within controllable resolution limits.
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 drive device reduces the controllable minimum injection amount and ensures stable valve operation by minimizing gradients and collisions, maintaining linear control over the injection amount and reducing Particulate Number (PN) emissions.
Implementation Method 1
the drive device first applies the voltage of the high voltage source to the coil to quickly raise the current and rapidly generates a magnetic flux in the magnetic circuit
Implementation Method 2
a magnetic attraction force acting on the needle increases and thus the gradient of the displacement amount of the valve body increases
Data Source
Figure 1
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Figure 4
AI summary
The purpose of the present invention is to provide a drive device that improves the precision of injection quantities by stabilizing the behavior of a valve body 214 under the condition that a valve body reaches a height position lower than a maximum height position and making the injection pulse width and the injection quantity gradient small. The present invention is a drive device for a fuel injection device for use in an internal combustion engine, wherein: the fuel injection device is provided with a valve body 214 that can open and close a fuel passage, a needle 202 that activates an opening and closing valve by transmitting power between itself and the valve body 214, and an electromagnet that comprises a solenoid 205 and a fixed core 207 provided as drive means for the needle 202, and a cylindrical nozzle holder 201 disposed on the outer peripheral side of the needle 202; and the drive device 150 controls a drive current flowing to the coil so as to decrease from the maximum drive current to a first drive current 610 that is lower than the maximum drive current before the valve body 214 reaches the maximum height position so that the valve body 214 reaches a height position lower than the maximum height position.