Injector Armature-Needle Assembly Precision Fabrication
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Solution Overview
Problem
Existing injector technologies for combustion engines face challenges in achieving precise and reliable fuel injection due to manufacturing tolerances, leading to inaccuracies in the armature-needle assembly, which affects the injector's lifetime and efficiency.
Innovation Solution
A method involving the precise fabrication of an armature-needle assembly using subtractive manufacturing and grinding techniques to form base parts with specific stop faces, allowing for a fixed coupling and adjustable armature movement between these faces, thereby enhancing the accuracy and reliability of the injector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for injector fabrication, then manufacturing complexity is reduced, but manufacturing precision deteriorates leading to inaccuracies in armature-needle assembly
Solution Approach 1:
The injector is divided into multiple base parts (first base part, second base part, third base part) that are manufactured separately with high precision using subtractive manufacturing and grinding, then assembled together. This segmentation allows each component to be precisely manufactured and controlled independently, achieving overall high manufacturing precision while managing complexity through modular assembly.
Solution Approach 2:
Stop faces are pre-formed on the base parts using grinding and subtractive manufacturing before final assembly. These preliminary formed surfaces ensure precise positioning and alignment when components are assembled, eliminating the need for post-assembly adjustments and guaranteeing accurate armature-needle assembly.
2Reliability
If standard manufacturing tolerances are applied, then manufacturing time is reduced, but injector reliability deteriorates due to accumulated tolerances
Solution Approach 1:
Traditional mechanical assembly with loose tolerances is replaced by precision grinding and subtractive manufacturing processes that achieve tight tolerances (10 μm or less) on critical surfaces like stop faces. This substitution of manufacturing methods eliminates tolerance accumulation and ensures reliable, consistent injector performance over extended lifetime.
Solution Approach 2:
The manufacturing process transitions from standard tolerances to ultra-precise dimensional control with 10 μm or less tolerance on stop faces and other critical dimensions. This parameter change in manufacturing precision directly improves injector reliability by ensuring consistent armature movement and needle positioning throughout the injector's operational life.
3Manufacturing precision
If fixed coupling of base parts is implemented, then armature movement precision is improved, but manufacturing complexity increases
Solution Approach 1:
Stop faces serve as intermediary reference surfaces between base parts. These precisely ground surfaces provide fixed coupling and accurate positioning when base parts are assembled, ensuring controlled armature movement without requiring complex fastening mechanisms or adjustment procedures.
Solution Approach 2:
The stop faces are manufactured to be perfectly parallel and perpendicular to reference surfaces, creating equipotential reference planes that ensure uniform and precise armature movement. This geometric precision eliminates variability in armature positioning and movement control throughout the injector's operation.
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 method enables the fabrication of injectors with improved accuracy and efficiency, increasing the injector's lifetime and allowing for precise control of the injected fluid volume, with the armature movement adjusted to within 10 μm tolerances.
Implementation Method 1
the forming of the first base body and/or the forming of the second base body involves grinding
Implementation Method 2
the forming of the fixed coupling comprises a welding process
Data Source
AI summary
A method of fabricating an injector of a combustion engine includes providing a first base body and a second base body for a valve needle of the injector, forming the first base body such that a first base part with a first stop face is formed, providing an armature with a bore, forming the second base body such that a second base part with a second stop face and a third stop face is formed, disposing a section of the first base part and a section of the second base part in a bore of the armature, disposing the first and second base parts relative to each other such that the first stop face abuts the second stop face, and establishing a fixed coupling between the first and second base parts, wherein the armature is movable between the first stop face and the third stop face.