Fuel Injector Control Valve Parallelism and Air Gap by Laser Ablation
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Solution Overview
Problem
In fuel injector control valves, achieving precise parallelism and a consistent final air gap between the magnetic armature and the valve body is challenging due to high tolerances and the generation of debris during traditional precision methods, which are no longer suitable with the introduction of piezo-actuation.
Innovation Solution
A method involving the use of picosecond or femtosecond pulsed lasers to ablate the armature upper face, creating parallel bands to achieve parallelism and adjust the final air gap, with precise measurement and calculation of tilt axis and pass depth to ensure accurate alignment and surface flattening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional precision methods (grinding, micro-finishing, lapping, or turning) are used to achieve parallelism and final air gap, then manufacturing precision can be improved, but debris is generated and the process becomes unsuitable for piezo-actuation applications
Solution Approach 1:
The patent replaces traditional mechanical precision methods (grinding, lapping, turning) with laser ablation technology. The laser beam removes material through vaporization rather than mechanical contact, achieving the required parallelism and final air gap precision without generating mechanical debris. This substitution of mechanical systems with optical/thermal systems directly resolves the contradiction between precision and debris generation.
Solution Approach 2:
The patent changes the physical state and parameters of material removal from mechanical contact forces to laser-induced thermal vaporization. By controlling laser parameters (pulse duration, power, scanning speed), the process achieves precise material removal with clean ejection of vaporized material rather than mechanical chips or swarf, thereby improving precision while eliminating harmful debris.
2Ease of manufacture
If fixed stepped plate methods are used to achieve final air gap, then manufacturing simplicity is maintained, but manufacturing precision is insufficient for current performance requirements
Solution Approach 1:
The patent replaces the fixed mechanical stepped plate positioning method with laser ablation. Instead of relying on the precision of mechanically manufactured steps and fixtures, the laser directly removes material to achieve the exact required final air gap and parallelism. This substitution maintains relative manufacturing simplicity while dramatically improving precision outcomes.
3Measurement precision
If piezo-actuation is introduced to improve response control, then control precision is improved, but traditional tolerance methods are no longer suitable and debris generation becomes a problem
Solution Approach 1:
The patent replaces mechanical tolerance-based positioning with laser ablation to achieve the precise final air gap required for piezo-actuated control valves. The laser process works in conjunction with piezo-actuation by providing a clean, precise initial positioning without debris that could interfere with the piezoelectric components, thereby enabling both control precision and eliminating harmful factors.
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 achieves the required parallelism and final air gap tolerances of 10 μm and 2 μm respectively, improving the accuracy and reliability of the control valve by removing material progressively to correct surface tilt, thereby enhancing the performance and reducing debris generation.
Implementation Method 1
ablating the armature via successive pass of said individual depth and, generating the ablated face, in successively ablating a plurality of parallel bands extending along the tilt axis
Data Source
AI summary
A method is provided for achieving final air gap and parallelism of a control valve of a fuel injector, the control valve having a body defining an transverse top face and including a thick disc magnetic armature having a planar transverse upper face. The method includes a) measuring the actual position from the armature upper face and the body top face and, determining the actual parallelism error between said faces; and b) ablating the armature to generate an ablated upper face parallel to the body top face, the distance from the ablated upper face to the body top face being a final air gap.