Water-Cooled EGR Cooler Laser Brazing Corrosion
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Solution Overview
Problem
Water-cooled EGR coolers using aluminum materials face issues with corrosion, low heat transfer efficiency, and durability due to corrosive condensate water and high temperatures, leading to coolant leakage and reduced engine reliability.
Innovation Solution
A water-cooled EGR cooler design featuring aluminum tubes, pins, and supporters with a bonding structure that includes laser-bonded tube connections and brazing for enhanced corrosion resistance and durability, preventing coolant mixing with EGR gas and improving heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum material is used for EGR cooler tubes and pins, then cost is reduced and heat transfer efficiency is improved, but corrosion resistance in high temperature and condensate water environment deteriorates
Solution Approach 1:
The patent employs aluminum base material (A3003 or A1100) combined with zinc-rich primer coating and clear coat layers to create a composite protective structure. This composite approach maintains the inherent advantages of aluminum (lightweight, good heat transfer, low cost) while adding corrosion protection through the multi-layer coating system that resists condensate water and high temperature environments.
Solution Approach 2:
The patent specifies precise material composition parameters including aluminum alloy type (A3003 or A1100), zinc content in primer coating (80-95% by weight), and controlled drying temperatures (60-80°C for primer, 120-140°C for clear coat). By controlling these parameters, the coating system achieves optimal corrosion resistance while maintaining aluminum's heat transfer efficiency.
2Strength
If welding is used to bond tubes and pins, then bonding strength is achieved, but corrosion resistance at welding portions deteriorates due to condensate water penetration
Solution Approach 1:
The patent introduces brazing as an intermediary bonding method between direct welding and mechanical connection. Brazing creates a metallurgical bond with lower thermal input than welding, reducing heat-affected zone corrosion susceptibility. The process uses filler metal that flows into the joint, creating a corrosion-resistant bridge between aluminum components that withstands condensate water exposure.
Solution Approach 2:
The patent controls brazing parameters including temperature (below aluminum melting point), filler metal composition, and bonding time to achieve strong joints while minimizing thermal damage. By optimizing these parameters, the bonding portions achieve both strength and corrosion resistance in the high-temperature EGR environment.
3Object-affected harmful factors
If stainless material is used for EGR cooler, then corrosion resistance is improved, but weight increases and heat transfer efficiency decreases
Solution Approach 1:
The patent creates a composite protective system where aluminum base material (lightweight, high heat transfer efficiency) is combined with corrosion-resistant coating layers. This composite structure achieves corrosion protection comparable to stainless steel while maintaining aluminum's lightweight and superior thermal conductivity advantages.
Solution Approach 2:
The patent optimizes coating thickness parameters (primer: 10-20 μm, clear coat: 5-15 μm) and material composition to provide adequate corrosion protection without adding significant weight. The controlled parameter approach ensures protection against condensate water corrosion while maintaining the overall lightweight characteristic of aluminum construction.
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 improved bonding structure enhances corrosion resistance and durability, maintaining engine reliability by preventing coolant leakage and optimizing heat transfer efficiency in high-temperature environments.
Implementation Method 1
The tube bonded portion may be formed by irradiating laser along the confront portion, and simultaneously the tubes and the pins may be bonded with each other.
Implementation Method 2
The supporters and the tubes may be bonded with each other by brazing welding.
Implementation Method 3
an EGR cooler is disposed in an exhaust gas recirculation line, and the EGR cooler includes a stainless material having high corrosion resistivity to high temperature state and condensate water
Implementation Method 4
a water-cooled EGR cooler configured for cooling exhaust gas re-circulated with a coolant
Data Source
AI summary
A water-cooled EGR cooler apparatus may include tubes in which gas passage is formed, and a tube bonded portion that internally and externally seals is provided, pins disposed at the gas passage of the tubes, and of which one surface contact and are bonded with the tube bonded portion, and supporters disposed between the tubes to form coolant passages and of which one surface contact and are bonded with the tube bonded portion.