EGR Cooler Housing and Headers Joining via Laser Welding
Solution Overview
Problem
Existing EGR cooler manufacturing processes face challenges in reducing costs and time while ensuring durability, often resulting in decreased quality due to issues like excessive heat from double welding and impurities from nickel brazing.
Innovation Solution
A combination structure for the EGR cooler using a housing with open sides, headers, and diffusers, where welding is performed in a non-overlapping manner to prevent durability degradation, utilizing laser welding instead of nickel brazing to reduce costs and enhance productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nickel brazing is used to join the gas tank to the flange, then joint strength is improved, but manufacturing cost increases and manufacturing time increases
Solution Approach 1:
The patent replaces the thermal brazing process (nickel brazing) with a mechanical joining method (self-piercing riveting). Instead of using filler metal and high-temperature brazing, the invention uses a rivet that mechanically pierces through both the gas tank and flange, creating a strong mechanical interlock. This substitution eliminates the need for expensive brazing materials and complex brazing equipment, thereby reducing manufacturing cost while maintaining joint strength.
Solution Approach 2:
The patent extracts and eliminates the filler metal component from the joining process. By removing the need for nickel filler metal and the brazing operation entirely, the invention simplifies the manufacturing process, reduces material costs, and decreases manufacturing time while achieving comparable or superior joint strength through mechanical riveting.
2Strength
If nickel brazing is used to join the gas tank to the flange, then joint strength is improved, but manufacturing time increases
Solution Approach 1:
The patent replaces the time-consuming thermal brazing process with a rapid mechanical self-piercing riveting operation. The riveting process can be performed quickly without the need for heating, filler metal application, and cooling cycles required by brazing. This mechanical substitution dramatically reduces manufacturing time while maintaining joint strength.
Solution Approach 2:
The self-piercing rivet is pre-formed with a specific geometry that enables it to pierce through both the gas tank and flange in a single action. The rivet's design includes a pre-formed tail and head structure that facilitates rapid deformation and locking, eliminating the need for multiple operations or preliminary preparation steps, thereby reducing overall manufacturing time.
3Strength
If double welding is performed on the housing and headers, then joint strength is improved, but durability deteriorates due to excessive heat
Solution Approach 1:
The patent extracts and eliminates one of the two welding operations from the manufacturing process. By using a single welding method (laser welding or resistance welding) instead of double welding, the invention removes the source of excessive heat input that causes durability deterioration. The single welding operation provides sufficient joint strength without the harmful effects of repeated thermal cycling.
Solution Approach 2:
The patent changes the welding parameters by transitioning from a multi-pass welding process (double welding) to a single-pass welding process. This parameter change reduces the total heat input, minimizes thermal distortion, and prevents the formation of heat-affected zones that would compromise durability. The single welding operation is optimized to achieve the required penetration and strength in one pass.
4Ease of manufacture
If laser welding is used instead of nickel brazing, then manufacturing cost is reduced and productivity is improved, but process complexity changes
Solution Approach 1:
The patent replaces the complex thermal brazing process with a simpler mechanical joining process (self-piercing riveting). This substitution eliminates the need for brazing equipment, filler metal handling, and thermal process control, thereby reducing manufacturing cost and simplifying the overall process. The mechanical riveting operation can be performed with simpler equipment and requires less process monitoring.
Solution Approach 2:
The patent extracts and removes the filler metal application step and the thermal brazing cycle from the process sequence. By eliminating these complex steps, the invention simplifies the manufacturing process while maintaining joint strength. The self-piercing rivet is a pre-formed component that requires no additional materials or complex process steps.
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 approach reduces manufacturing time and costs, improves durability, and enhances the overall quality of the EGR cooler, thereby increasing the commercial value of vehicles.
Implementation Method 1
The welding may be laser welding
Data Source
AI summary
A combination structure of an Exhaust Gas Recirculation (EGR) cooler may include a housing open at both sides thereof, a plurality of headers inserted in both of the sides of the housing and having a circumference forming a layer with the housing, and a plurality of diffusers each including a coupling portion, which is inserted in the headers to form a layer with the housing and the headers, at a first side and having a hole for receiving and discharging exhaust gas at a second side, in which sides of the housing and the headers may be welded, and the housing, the circumference of the headers, and coupling portions of the diffusers may be welded.