Fuel Valve Needle Control via Pilot Valve Segmentation
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Solution Overview
Problem
Conventional fuel valves for large turbocharged two-stroke diesel engines with cross-heads suffer from significant energy losses due to leak flow and slow opening and closing speeds, which hinder emission reduction and improve specific fuel consumption.
Innovation Solution
An electronically controlled fuel valve with a spool valve that selectively connects the closing chamber to either the tank port or the fuel inlet port, reducing leak oil flow and enabling faster control of the valve needle, utilizing a solenoid-controlled ball valve to manage pressure chamber connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a pressure chamber with throttled connections is used to control the valve needle, then the valve can be controlled, but the opening and closing speeds are slow
Solution Approach 1:
A pilot valve is introduced as an intermediary device to control the pressure chamber. The pilot valve selectively connects the pressure chamber to either the fuel inlet port or tank port, enabling faster pressure changes than direct throttled connections alone could achieve.
Solution Approach 2:
The control system is segmented into two stages: the pilot valve for rapid pressure changes and the pressure chamber for controlled valve needle movement. This segmentation allows each component to optimize its function for speed control.
2Loss of energy
If the connection to tank port is less restricted than fuel port connection, then pressure chamber pressure can be controlled, but substantial drain losses occur during valve open time
Solution Approach 1:
The pilot valve operates periodically to selectively connect the pressure chamber to the fuel inlet port or tank port based on valve operation phase. During valve open time, it connects to the fuel inlet port to prevent drain losses, and during closing, it connects to the tank port for pressure control.
Solution Approach 2:
The system transitions from a static throttled connection design to a dynamic system where the pilot valve actively manages connections based on real-time operational requirements, optimizing both energy efficiency and control capability.
3Speed
If solenoid valve controls the connection to tank port, then valve needle position can be controlled, but opening and closing movement is slower than desired
Solution Approach 1:
The system replaces the purely mechanical solenoid valve control with a hybrid system where the pilot valve (electronically controlled) manages the pressure chamber connections, enabling faster response times while maintaining automated control.
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 reduces specific fuel consumption and emissions by minimizing leak oil flow and enhancing the speed of valve needle operation, achieving better control over fuel injection.
Implementation Method 1
The connection to the tank port can be opened and closed by an electrically controlled solenoid valve that typically is a solenoid controlled ball valve
Implementation Method 2
The fuel valve is provided with a spring biased axially movable valve needle
Data Source
Figure 1
Figure 2
AI summary
A fuel valve (1) for injecting fuel into the combustion chamber of a large turbocharged two stroke diesel engine, with a resiliently biased and axially movable valve needle (20) cooperating with a valve seat (22), a plurality of nozzle holes (35) distributed axially and radially over the nozzle (30), an electronically controlled valve connected to a closing chamber in for urging the valve spindle (20) to its seat (22) for alternatively connecting the closing chamber to a tank port (18) or to a fuel inlet port (16).