Fuel Injection Flow Fuse for Common Rail Control Valve Failure
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Solution Overview
Problem
The existing common rail fuel injection systems face challenges in controlling fuel injection at low engine loads, leading to excessive fuel injection and emissions, particularly due to issues with the control valve failing to close, causing continuous fuel flow and high cylinder pressure.
Innovation Solution
The introduction of a flow fuse positioned between the first needle control volume and the first control valve, which includes a cylindrical cavity with a cup-shaped piston and restricted flow passages, ensures that the pressure in the needle control volume is raised only when the control valve is closed, preventing continuous fuel injection by blocking the flow connection in abnormal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control valve is used to control fuel injection timing and duration, then injection precision is improved, but the risk of control valve failure causing continuous fuel flow increases
Solution Approach 1:
A flow fuse is introduced as an intermediary safety device between the control valve and the needle control volume. This flow fuse monitors the pressure differential across the control valve and automatically blocks the fuel supply to the needle control volume when abnormal pressure conditions indicate control valve failure, preventing continuous fuel injection
Solution Approach 2:
The flow fuse implements a pressure-based feedback mechanism that continuously monitors the pressure differential across the control valve. When the pressure differential exceeds predetermined thresholds indicating control valve failure, the feedback triggers the flow fuse to block fuel flow, automatically correcting the abnormal condition
2Measurement precision
If the needle control volume pressure is increased to improve injection control, then injection precision is improved, but the risk of excessive fuel injection upon control valve failure increases
Solution Approach 1:
The flow fuse is pre-configured with pressure differential thresholds that trigger automatic fuel flow blocking before excessive fuel injection can occur. By establishing predetermined pressure limits and automatic blocking mechanisms in advance, the system prevents harmful effects before they manifest
3Reliability
If a flow fuse is added to prevent control valve failure effects, then system safety is improved, but device complexity increases
Solution Approach 1:
The flow fuse is designed as a separate, extractable safety module that can be independently removed or replaced. This modular approach isolates the safety function from the main injection mechanism, allowing the flow fuse to be serviced or replaced without affecting the core injection system
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 prevents excessive fuel injection, reduces emissions, and minimizes energy consumption by ensuring precise control over fuel pressure and flow, addressing the issue of control valve failure and improving overall system safety.
Implementation Method 1
The needle control volume and the needle cavity are arranged in flow communication with each other via one or mode well dimensioned openings or flow channels that restrict the flow between the two cavities, i.e. restrict the speed the pressure is able to raise in the needle control volume.
Implementation Method 2
The flow fuse includes a cup-shaped piston arranged in the cylindrical cavity such that the piston blocks a flow connection from the needle control volume to the control valve when a pressure differential across the piston exceeds a predetermined threshold value.
Data Source
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AI summary
The present invention discusses a novel fuel injection unit for a large internal combustion engine having a common rail fuel system. The fuel injection unit (10) of the present invention is connected to the common rail fuel system, the fuel injection unit (10) comprising a first nozzle (22) and a second nozzle (24), the first nozzle (22) having a first needle control volume (34) connected by means of a flow passage (48) with a first control valve (16), the first nozzle (22) and the second nozzle (24) having a common needle cavity (30), wherein a flow fuse(50) arranged in connection with the flow passage (48) connecting the first needle control volume (34) to the first control valve (16).