Fuel Injection Drive Unit Dual Voltage Control
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Solution Overview
Problem
Existing fuel injection devices face challenges in reducing the minimum injection quantity due to unstable valve element behavior and rebound phenomena, which affect fuel economy and efficiency, particularly in downsizing engines where precise control is required.
Innovation Solution
A drive unit for fuel injection devices utilizing a dual voltage source system, where a high voltage source is used to drive the valve element to an open state and then switched to a lower voltage source to maintain the open state, allowing for precise control of the drive current to minimize rebound and stabilize the valve element's behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single voltage source is used to drive the fuel injection valve, then the device complexity is reduced, but the minimum injection quantity cannot be sufficiently reduced due to rebound phenomenon and unstable valve element behavior
Solution Approach 1:
The voltage source is segmented into two distinct voltage sources: a first voltage source for generating drive current during valve opening, and a second voltage source for generating hold current during valve holding. This segmentation allows independent optimization of each voltage source's characteristics to eliminate rebound phenomenon and stabilize valve element behavior, thereby reducing the minimum injection quantity.
Solution Approach 2:
The patent implements dynamic switching between two voltage sources based on the operational phase of the fuel injection valve. During the valve opening phase, the first voltage source is activated; during the valve holding phase, the second voltage source is activated. This dynamic voltage source configuration enables precise control of the coil current profile, suppressing rebound and stabilizing valve element behavior to reduce minimum injection quantity.
2Speed
If the valve element is driven with high current to ensure rapid opening, then the valve opening speed is improved, but the rebound phenomenon increases causing unstable injection quantity
Solution Approach 1:
The patent employs periodic action by sequentially activating two voltage sources in distinct time phases. The first voltage source operates during the valve opening phase to provide high drive current for rapid opening. The second voltage source operates during the valve holding phase to provide controlled hold current that prevents rebound. This periodic switching between voltage sources achieves both rapid valve opening and stable injection quantity.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining continuous current supply to the coil throughout the valve operation. The first voltage source provides continuous drive current during opening, and the second voltage source seamlessly takes over during the holding phase. This continuous current supply prevents interruptions that could cause rebound, thereby maintaining both rapid opening speed and injection quantity stability.
3Quantity of substance
If a long injection pulse width is used to increase injection quantity, then the fuel quantity is increased, but the non-linearity between pulse width and injection quantity increases in short pulse region
Solution Approach 1:
The patent changes the electrical parameters by using two different voltage sources with different current characteristics. The first voltage source provides high current for rapid valve opening, while the second voltage source provides optimized hold current for stable valve positioning. This parameter change in voltage and current profiles eliminates the rebound phenomenon that causes non-linearity, achieving a linear relationship between injection pulse width and injection quantity across the entire operating range.
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 enables rapid switching to a hold current, reducing the minimum injection quantity and stabilizing valve element behavior, thereby enhancing fuel economy and efficiency by linearizing the injection quantity characteristic.
Implementation Method 1
a voltage control means which selectively controls an electrical connection with the solenoid valve, applies a voltage from a second voltage source to the solenoid valve when opening the valve to drive the valve element from a valve closed state to a valve open state
Data Source
AI summary
In a drive unit of a fuel injection device, an electric current is supplied to the fuel injection device by applying a high voltage to the fuel injection device from a high voltage source whose voltage is boosted to a voltage higher than a battery voltage at the time of opening a valve of the fuel injection device. Thereafter, the electric current supplied to the fuel injection device is lowered to a current value at which a valve element cannot be held in a valve open state by stopping the applying of the high voltage from the high voltage source. Thereafter, in a stage where a supply current is switched to a hold current, another high voltage is applied to the fuel injection device from the high voltage source.