Segmented Urea and Fuel Tank Assembly to Prevent Weld Cracking
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Solution Overview
Problem
Current fuel and urea tank manufacturing methods face challenges such as high costs, uneven wall thickness, material wastage, and potential cracking due to welding stresses, which affect the strength and service life of the tanks.
Innovation Solution
The tanks are designed with separate upper, middle, and lower shells welded after injection molding, with stress dispersion to the ends and a grid rib structure to distribute impact forces, reducing stress concentration and enhancing mechanical strength and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the tank is formed by blow molding process, then the production cost is reduced, but the wall thickness becomes uneven and mechanical strength decreases
Solution Approach 1:
The tank is divided into three separate shells (upper, middle, and lower) that are injection-molded individually and then welded together. This segmentation allows each shell to be manufactured with precise wall thickness control through injection molding while maintaining cost-effectiveness, resolving the contradiction between manufacturing precision and production cost.
2Manufacturing precision
If the tank is formed by injection molding as an integrated structure, then the wall thickness is uniform, but welding is required which introduces stress concentration and cracking risk
Solution Approach 1:
The tank is segmented into three shells welded at upper and lower ends, distributing welding stresses away from the liquid-bearing middle section. This segmentation maintains uniform wall thickness through injection molding while improving cracking resistance by positioning welds in low-stress areas.
Solution Approach 2:
Different regions of the tank are designed with different shell thicknesses: the upper and lower shells have greater thickness to accommodate welding operations and withstand compression, while the middle shell has optimized thickness for liquid flow and reduced weight. This local quality differentiation resolves the contradiction between uniformity and stress distribution.
3Reliability
If the middle shell has greater height, then the welded joints are positioned away from the maximum impact force area, but the overall structural strength may be compromised
Solution Approach 1:
The middle shell is designed with a height of 4-6 times the shell thickness, creating a long intermediate section that positions welded joints at the ends away from the maximum impact force area in the middle. This local geometric optimization maintains overall structural strength while improving cracking resistance at critical welded regions.
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 design achieves uniform wall thickness, improved mechanical strength, reduced cracking risk, and extended service life by dispersing welding stress and optimizing the structural integrity of the tanks.
Implementation Method 1
the upper shell, the middle shell and the lower shell are welded by hot melting
Data Source
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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; on the other hand, because the middle area of the shell bears the maximum flow impact force caused by the shaking of liquid such as fuel, avoiding setting welded joints in the middle of the shell can not only improve the overall strength of the shell, but also avoid the cracking of the welded part of the shell due to suffering from the impact force, and improve the service life of the fuel tank.