Variable-Thickness Accumulator Shell for Weld Stress Relief
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Solution Overview
Problem
The existing accumulator shell members face durability issues due to stress concentration at the welds under high pressure, leading to potential breakage, and increasing weld thickness to improve durability results in increased weight, affecting fuel efficiency.
Innovation Solution
A shell member design with a thicker weld area and thinner other portions, featuring a protruding portion and taper, which reduces stress concentration and weight while maintaining pressure fluctuation buffering effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the shell member at the weld is increased to improve durability, then the weld is less likely to break under stress, but the weight of the accumulator is increased
Solution Approach 1:
The shell member is designed with non-uniform thickness, where the thickness varies in the radial direction. Specifically, the thickness at the weld portion is greater than the thickness at other portions, allowing localized reinforcement only where stress concentration occurs during welding, rather than uniformly increasing the thickness of the entire shell member. This resolves the contradiction by improving weld durability through localized thickening while maintaining lower overall weight.
2Strength
If the thickness of the shell member is increased to improve weld strength, then the weld can withstand higher stress, but the fuel efficiency of the vehicle is reduced
Solution Approach 1:
The shell member employs variable thickness distribution, with increased thickness specifically at the weld portion where strength is critical, while other portions maintain thinner walls. This localized reinforcement approach ensures adequate weld strength to withstand operational stresses without unnecessarily increasing the overall weight of the accumulator, thereby preserving vehicle fuel efficiency.
3Ease of manufacture
If the shell member has uniform thickness, then the manufacturing is simpler, but the weld portion is more prone to breakage due to stress concentration
Solution Approach 1:
The shell member is designed with non-uniform thickness where the thickness varies radially, with the weld portion having greater thickness than other areas. This design accepts increased manufacturing complexity compared to uniform thickness shells, but significantly improves weld durability by reducing stress concentration at the weld joint through the thicker local section.
Solution Approach 2:
The shell member incorporates a tapered portion with a gradual curvature transition between the thinner and thicker sections. This curved transition avoids sharp corners and abrupt thickness changes, which would create stress concentration points. The smooth curvature distribution allows the variable thickness design to be manufactured while maintaining structural integrity and weld durability.
Data Source
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AI summary
A shell member 10 constituting an accumulator 100 including a cover member 30, a shell member 10 having a cylindrical portion 11, an opening portion 13 formed at one end of the cylindrical portion 11 and welded to the cover member 30, and a closed portion 12 formed at another end of the cylindrical portion 11, and an accumulation part 70 accommodated in the shell member 10. The cylindrical portion 11 includes an upper end portion 11a, and a protruding portion 11c having the opening portion 13. The protruding portion 11c is thicker than the upper end portion 11a.