Fuel Injector Servo Valve Bushing Welding and Armature Mounting
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Solution Overview
Problem
The manufacturing of fuel injector servo valves faces challenges in precision fixing of stop elements and mounting the armature in a slidable manner without interference with weld material, leading to difficulties in reducing armature rebounds and achieving high reliability at a limited cost.
Innovation Solution
A method involving a bushing with a guide portion and terminal extension, where the armature and ring are positioned and welded without requiring precise phasing, allowing for a pre-set travel greater than the bushing, and using a helical spring and magnetic actuator to control the servo valve, reducing rebounds by ensuring the armature strikes the bushing during the first rebound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the armature is mounted in a slidable way on the bushing with precise positioning of stop elements, then the axial travel and rebound reduction are improved, but the manufacturing complexity and difficulty of assembly increase
Solution Approach 1:
The patent combines the stop element and the armature mounting structure into a single integrated component. The stop element is formed as part of the bushing structure, eliminating the need for separate stop elements and complex positioning mechanisms. This merging reduces assembly complexity while maintaining the axial travel control and rebound reduction functions.
Solution Approach 2:
The patent extracts the stop element function from the armature assembly and integrates it into the bushing structure. By taking out the stop element as a separate component and incorporating it into the bushing, the design simplifies the overall assembly while maintaining precise axial travel control and reducing manufacturing complexity.
2Strength
If laser welding is used to fix the armature on the bushing, then the connection strength is improved, but the interference with external profile and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by creating a specific recess in the bushing structure where the armature is mounted. This recess provides a dedicated welding zone that is accessible to laser welding processes while maintaining the external profile integrity. The local modification allows strong welding connection without interfering with the overall external dimensions and functionality of the components.
3Manufacturing precision
If two separate stop elements are used for armature travel control, then the axial travel precision is improved, but the manufacturing precision requirements and assembly difficulty increase
Solution Approach 1:
The patent merges the functions of multiple stop elements into a single integrated bushing structure with built-in axial stop features. This consolidation maintains the precision of axial travel control while reducing the number of separate components, thereby simplifying manufacturing and assembly processes.
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 precise axial displacement and reduced rebounds of the bushing, facilitating high-reliability servo valve production with simplified welding and cost-effective manufacturing by eliminating the need for precise armature thickness and spacers, while maintaining fluid tightness and operational efficiency.
Implementation Method 1
The bushing is brought into the closing position by a corresponding spring
Implementation Method 2
controlled so as to be brought into the opening position, against the action of the spring, by a disk-shaped armature, actuated by an electric actuator
Data Source
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AI summary
The manufacturing method regards a servo valve (5) of a fuel injector, wherein a bushing (41) is designed to slide on a fixed stem for opening/closing the servo valve (5) and carries an armature (17), which is free to slide axially on the bushing (41); according to the method, the bushing (41) is provided in such a way that it has a guide portion (61) and an adjacent terminal portion (71); after the armature (17) has been mounted on the guide portion (61), a ring (73) is fitted on the terminal portion (71) so that it is brought in contact upon the armature; the ring (73) is then welded to the terminal portion (71) with weld material along a circumference so that a sight welding is carried out without any need for angular positioning between the bushing (41) and the welding device.