Fuel Injector Control Valve Sleeve for Leakage Reduction
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Solution Overview
Problem
Leakage between the control valve member and the bore of the control valve body in fuel injectors leads to inefficiency due to increased clearance caused by pressure expansion, which existing solutions attempt to mitigate through pressure compensating chambers and precise machining but require complex installation and high precision.
Innovation Solution
A control valve assembly with a sleeve subassembly that includes a radial protrusion on the stem and a sealing mechanism, where the sleeve is attached to the control valve member via a weld or sealing ring, allowing for pressure compensation and reduced leakage by maintaining a consistent clearance and expanding to fit the bore as pressure increases, thereby minimizing the leak path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure compensating chamber with an insert is used to reduce leakage, then leakage is reduced, but device complexity and manufacturing precision requirements increase
Solution Approach 1:
The invention extracts the pressure compensation function from a complex insert assembly and implements it through a simple sleeve component that moves with the control valve member. This separates the sealing function (control valve member) from the pressure compensation function (sleeve), eliminating the need for precise machining of frustoconical faces and complex insert installations while maintaining effective leakage reduction
Solution Approach 2:
The sleeve acts as an intermediary component between the control valve member and the control valve body. It provides the necessary pressure compensation by moving axially with the control valve member, maintaining a consistent clearance without requiring direct precision machining or complex installation procedures
2Reliability
If precise machining of the control valve member and control chamber is performed, then leakage is reduced, but manufacturing cost and complexity increase
Solution Approach 1:
The sleeve automatically compensates for pressure-induced expansion of the control valve body by moving axially with the control valve member. This self-compensating mechanism eliminates the need for high-precision machining of the control valve member and control chamber, as the sleeve adapts to dimensional variations and pressure conditions automatically during operation
3Reliability
If the control valve member is made more rigid to reduce distortion, then leakage is reduced, but the ability to compensate for pressure expansion is limited
Solution Approach 1:
The sleeve is designed to move axially dynamically with the control valve member in response to pressure changes. This dynamic movement allows the sleeve to compensate for pressure-induced expansion of the control valve body, maintaining a consistent clearance and effective sealing without requiring the control valve member itself to be highly rigid
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 solution effectively reduces fuel leakage by maintaining a consistent clearance and ensuring the sleeve expands to fit the bore as pressure increases, maintaining a tight seal and preventing pressure from increasing within the clearance, thus enhancing the injector's efficiency and compatibility with existing systems.
Implementation Method 1
Increasing fuel pressure within the bore 8 causes the guide portion of the bore 8 to expand, thereby increasing clearance between the control valve member 4 and the control valve body 6
Implementation Method 2
The stem may comprise at least one radial protrusion, wherein the protrusion contacts an inner surface of the sleeve
Implementation Method 3
The sleeve may be attached to the control valve member at least by a weld between an enlarged portion of the stem and a contact point on an inner surface of the stem
Data Source
AI summary
A subassembly for a high pressure fuel injector control valve includes a control valve member and a sleeve attached to a stem of the control valve member, the sleeve extending along at least a partial axial length of the stem of the control valve member, and wherein a clearance, provided between the sleeve and the control valve member, is in fluid communication with the control chamber such that during use, pressure compensation occurs, as the sleeve is caused to expand and seal against the control valve bore, thereby preventing leakage of fuel within the control valve assembly.