Accumulator Vessel Lid Structure for Thread Load Distribution
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Solution Overview
Problem
Conventional high-pressure hydrogen accumulator vessels face safety concerns due to hydrogen environmental embrittlement, particularly at threaded portions, which can lead to fatigue cracks and vessel failure, especially under repeated loading conditions.
Innovation Solution
The design incorporates a screwable lid structure with a protruding portion that distributes the load uniformly across multiple threads, reducing stress concentration and facilitating easy opening and closing, while a stopper restricts inward movement to ensure secure closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a screwable nut type lid structure is adopted to prevent hydrogen contact with threaded portions, then hydrogen environmental embrittlement is avoided, but load is not uniformly distributed and maximum load concentrates on the first thread
Solution Approach 1:
A seal member is introduced as an intermediary component between the lid and the accumulator vessel body. The seal member includes a load distribution portion that contacts the threaded portion, mediating the load transfer and distributing it across multiple threads rather than concentrating it on the first thread, thus preventing fatigue cracks while maintaining hydrogen isolation
2Strength
If the height of threads is reduced in a tapered fashion to reduce thread overlap, then load on the first thread is reduced, but production cost increases and opening/closing becomes difficult
Solution Approach 1:
Rather than modifying the thread geometry itself (which would increase manufacturing complexity), the invention introduces a seal member with a specifically designed load distribution portion as an intermediary. This component redistributes the load without requiring tapered threads or complex machining, maintaining ease of manufacture while achieving fatigue strength improvement
3Strength
If the height of threads is reduced in a tapered fashion, then load on the first thread is reduced, but opening and closing of the lid becomes difficult
Solution Approach 1:
The seal member acts as a load-distributing intermediary that allows the lid to be screwed on and off easily while preventing fatigue cracks. The load distribution portion spreads the clamping force across multiple threads, reducing stress concentration without creating the threading difficulties that would result from tapered thread designs
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A pressure accumulation container (10) has a screw-in part (3) and a lid part (2) which is located on the axially inner side of the screw-in part and the axially inner side surface of which serves as a pressure receiving surface. The lid part has, on the inner circumferential side thereof, a protruding section (22) that extends toward the axially outer side. The protruding section comes into contact with an axially inner side end of the screw-in part so as to separate the axially inner side surface on the outer circumferential side of the screw-in part from the axially outer side surface on the outer circumferential side of the lid part.