Ceramic Heater Brazing Structure for Load Dispersion
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Solution Overview
Problem
Existing brazing structures for ceramic heaters and glow plugs face challenges in maintaining durability and reliability under high temperature and pressure conditions, as the brazed-welded portions tend to experience localized load concentration, leading to potential failures.
Innovation Solution
A brazing structure with a ceramic member featuring a small diameter portion closer to one end, where the brazing member fills the space between this portion and the tubular metal fitting's inner surface, dispersing the load and enhancing welding strength by covering the metallized layer's edge, while a nickel-plated layer on the tubular metal fitting improves wettability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional brazing structure with a metallized layer on the ceramic member is used, then the assembly is simple to manufacture, but the brazed-welded portion experiences localized load concentration under high temperature and pressure, reducing reliability
Solution Approach 1:
The ceramic member features a small diameter portion at a specific location (closer to one end than the metallized layer) that creates a localized geometric variation. This local structural modification allows the brazing member to fill the space between the small diameter portion and the tubular metal fitting, covering the edge of the metallized layer and dispersing loads effectively without requiring complex changes to the entire ceramic structure
Solution Approach 2:
The brazing structure is divided into distinct functional zones: the metallized layer region for brazing attachment, the small diameter portion for load dispersion, and the brazing member filling the space between them. This segmentation allows each portion to perform its specific function optimally, with the brazing member acting as an intermediary that covers the metallized layer edge and distributes mechanical loads
2Strength
If the brazing member fills the space between the small diameter portion and the tubular metal fitting, then load dispersion and welding strength are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The small diameter portion is pre-formed on the ceramic member before the brazing process. This preliminary geometric preparation ensures that when the brazing member is applied, it naturally fills the space between the small diameter portion and the tubular metal fitting, covering the metallized layer edge. This preliminary action simplifies the brazing process by creating a self-aligning structure that guides the brazing material to the correct position
Solution Approach 2:
The brazing member serves as an intermediary element that connects the ceramic member (with its small diameter portion) and the tubular metal fitting. It fills the space between these two components, covers the edge of the metallized layer, and provides a load-dispersing interface. This intermediary structure enhances welding strength while maintaining manufacturing feasibility through standard brazing 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
The solution significantly improves the durability and reliability of the brazed-welded portion by dispersing loads and increasing the contact area, ensuring high welding strength and resistance to severe conditions like high temperature and pressure.
Implementation Method 1
The brazing member fills a part of the space between the small diameter portion and the inner surface of the tubular metal fitting which faces to the part of the small diameter
Implementation Method 2
a plated layer having a main component made of nickel is formed on the inner surface of the tubular metal fitting
Data Source
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AI summary
A ceramic heater comprising a rod-like ceramic member in which a metallized layer is formed on at least a part of an outer surface of the ceramic member, and a tubular metal fitting in which at least a part of the ceramic member is inserted, the inner surface of the tubular metal fitting and the metallized layer being brazed through a brazing member. The ceramic member has a small diameter portion in a region which is located closer to a first end of the ceramic member than the metallized layer and which is inside the tubular metal fitting. A part of the space between the small diameter portion and the inner surface of the tubular metal fitting is filled with the brazing member, the inner surface facing to the part of the small diameter. Consequently, even under severe conditions, such as a high temperature and/or a high pressure, a highly durable brazing structure, such as the ceramic heater, including a brazed portion which has high welding reliability can be obtained.