Segmented Fuel and Urea Tank Assembly to Prevent Weld Cracking
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Solution Overview
Problem
Existing fuel and urea tanks in automobiles face issues with non-uniform wall thickness, high production costs, material waste, and potential cracking due to welding joints, which compromise strength and longevity.
Innovation Solution
A urea tank and fuel tank assembly is designed with separate upper, middle, and lower shells welded after injection molding, distributing welding stress to the ends and avoiding mid-section joints, with optimized height and thickness ratios and grid rib structures to enhance strength and reduce impact forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If blow molding process is used to form fuel tanks and urea tanks, then production cost is reduced and volume is increased, but wall thickness cannot be controlled uniformly leading to excessive wall thickness and raw material waste
Solution Approach 1:
The tank is divided into multiple segments (first tank body portion and second tank body portion) that are injection molded separately and then welded together. This segmentation allows each portion to be optimized for uniform wall thickness control during injection molding, eliminating the material waste associated with excessive thickness in blow molding processes.
2Manufacturing precision
If injection molding process is used to form integrated fuel tanks and urea tanks, then wall thickness uniformity is improved, but welding is required after molding which introduces welding joints that may crack and reduce strength
Solution Approach 1:
The welding operation is extracted from the middle of the tank body and relocated to the ends. The first and second tank body portions are welded at their respective end surfaces, positioning welding joints away from the middle section where liquid flow impact forces are maximum, thereby reducing stress concentration and cracking risk at the welded joints.
3Ease of manufacture
If welding joints are placed in the middle of the shell, then assembly is simplified, but the welded part suffers from maximum flow impact force causing cracking and reduced service life
Solution Approach 1:
The tank is designed with asymmetric positioning of welding joints relative to the liquid flow path. The welding joints are located at the end surfaces of the tank body portions, while the middle section remains free of welds. This asymmetric arrangement ensures that the most heavily stressed region (middle section) maintains full structural integrity without welding weaknesses.
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 assembly achieves uniform wall thickness, improved mechanical strength, reduced cracking risk, and extended service life by dispersing stress, while integrating fuel and urea tanks for reduced weight and enhanced durability.
Implementation Method 1
the upper shell, the middle shell and the lower shell are welded separately to form a cavity including a fuel cavity
Data Source
AI summary
Disclosed is a urea tank and fuel tank assembly, which belongs to the field of automobile parts. The urea tank and fuel tank assembly includes a shell, wherein the shell includes an upper shell, a middle shell and a lower shell, the upper shell, the middle shell and the lower shell are welded separately to form a cavity including a fuel cavity. The urea tank and fuel tank assembly is welded after injection molding, so that not only is the shell uniform in wall thickness and high in mechanical strength, but also the welding stress is dispersed to the upper and lower ends of the shell by setting that the upper shell, the middle shell and the lower shell are welded separately, on the one hand, the stress concentration of the welded part of the shell is reduced and the cracking of the welded part is avoided.