| 摘要 |
PROBLEM TO BE SOLVED: To relieve a concentration of stress acting on walls at deforming time of a fuel storage chamber by arranging a stress absorbing means on the periphery of the prescribed part of the walls having the prescribed part having rigidity higher than the walls. SOLUTION: A projecting bead 76 for surrounding the vicinity of a fuel pipe 60 corresponding to a stress absorbing means to a lower wall 8 is integrally molded on the lower wall 8 having the fuel pipe 60 having rigidity higher than the lower wall 8. A projecting bead 75 for surrounding the vicinity of a cutoff valve 12 corresponding to a stress absorbing means to an upper wall 7 is integrally formed on the upper wall 7 having the cutoff valve 12 having rigidity higher than the upper wall 7. According to this constitution, even when the upper wall 7 and the lower wall 8 are curved and deformed, since the beads 75, 76 are respectively arranged on the periphery of the cutoff valve 12 of the upper wall 7 and the periphery of the fuel pipe 60 of the lower wall 8, a stress concentration to the periphery of the cutoff valve 12 of the upper wall 7 and the periphery of the fuel pipe 60 of the lower wall 8 can be respectively relieved to thereby eliminate breaking of the upper wall 7 and the lower wall 8.
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