An intake air duct serves as a passage for supplying air to an engine, and includes a first intake air passage, {HEAD ~ a second intake air passage}, {TAIL ~ an opening and closing valve}, an interlocking member and a coiled spring 
An intake air duct serves as a passage for supplying air to an engine , and includes a first intake air passage , { HEAD ~ a second intake air passage } , { TAIL ~ an opening and closing valve } , an interlocking member and a coiled spring
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