Engine Injector Needle Slow Close Control for Fuel Backflow Prevention
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Solution Overview
Problem
Existing engine control devices face challenges in preventing fuel backflow into the injector after injection, leading to deposit formation at injection holes and improper fuel injection, particularly due to the difficulty in controlling needle motion and the adverse effects on fuel spray state and economy.
Innovation Solution
The engine control device employs a slow close control mechanism that reduces the needle's moving speed before reaching the close position, temporarily stops the needle's motion, and adjusts the speed according to the engine's operating state, using current control to stabilize and precision-control the needle's motion, thereby preventing fuel backflow and deposit formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the needle closes quickly after fuel injection, then the injection speed is high and fuel economy is improved, but the sac portion is placed under negative pressure causing fuel backflow and deposit formation
Solution Approach 1:
The control device performs preliminary action by temporarily stopping the needle's closing motion before it reaches the closed position. This prevents the sac portion from being placed under negative pressure, thereby avoiding fuel backflow and deposit formation while maintaining high injection speed during the main injection phase
Solution Approach 2:
The system dynamically adjusts the needle motion by transitioning from constant high-speed closing to temporary stop, then to gradual closing. This dynamic control optimizes both injection speed and prevents negative pressure conditions that cause backflow
2Reliability
If the needle is temporarily stopped during closing, then fuel backflow is prevented, but the injection period is extended affecting fuel economy
Solution Approach 1:
The temporary stop is applied only partially during the closing process, specifically before the needle reaches the closed position, rather than extending the full injection period. This partial application prevents backflow while minimizing the extension of the injection period and its impact on fuel economy
3Measurement precision
If current control is used to precision-control needle motion, then the needle can be precisely positioned, but the control system complexity increases
Solution Approach 1:
The control device uses feedback from the injector controller to monitor needle position and adjust current supply accordingly. This feedback mechanism enables precise needle positioning during the temporary stop and gradual closing phases while keeping the control system manageable through coordinated control between the control device and injector controller
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 solution effectively blocks fuel backflow, ensuring stable long-term fuel injection and maintaining optimal fuel spray conditions, even at high speeds, while minimizing the impact on fuel economy.
Implementation Method 1
When a current is supplied to the solenoid coil 44, a magnetic force is generated
Implementation Method 2
the needle 42 is displaced to the close position by an elastic force of the coil spring 45
Implementation Method 3
the sac portion 48 is placed under negative pressure, and a backflow from the combustion chamber 6 to the sac portion 48 occurs
Data Source
AI summary
Disclosed is a control device of an engine 1 including an injector. The injector has a needle which is displaced between a close position where no fuel is allowed to flow into a sac portion and an open position where the fuel is allowed to flow into the sac portion. The control device has a fuel injection controller controlling a fuel injection period and an injector controller controlling a motion of the needle. The injector controller executes control to reduce a moving speed of the needle before the needle reaches the closed position when the injection period ends.