Synergistic Optimization of Structural Parameters of the Type IV Hydrogen Storage Cylinder Neck Seal Ring and Numerical Analysis of Its Sealing Performance

The Type IV hydrogen storage cylinder has become the preferred component for hydrogen fuel cell vehicles owing to its high hydrogen storage density, lightweight characteristics, and resistance to hydrogen embrittlement. Nevertheless, the sealing structure at the cylinder neck and its dynamic sealing performance during hydrogen refueling are critical factors governing the sealing reliability of the hydrogen storage cylinder neck. To address the sealing reliability challenges of the Type IV cylinder neck, a novel sealing structure was proposed based on principles of theoretical mechanics and mechanical design. A three-dimensional numerical model of the seal ring under hydrogen absorption-induced expansion was developed to systematically investigate the influences of the seal ring’s material properties, cross-sectional shape and radial dimensions, and groove geometry on sealing performance. Results demonstrate that a smooth transitional arc combined with a large radial cross-sectional dimension of the seal ring markedly reduces internal stress. The chamfer at the groove top exerts minimal impact on sealing characteristics (ΔP< 1.37MPa), whereas reducing the fillet radius at the groove bottom effectively mitigates stress concentration. Concerning material parameters, the elastic modulus of the seal ring exhibits a negative correlation with the sealing performance at the cylinder neck. Under cooperative sealing with double O-rings, the uniformity of contact pressure distribution improves by 10-17% relative to a single ring, accompanied by a one order of magnitude reduction in leakage rate.