The second intake air passage is opened by the opening and closing valve when {HEAD ~ a first urging force}, which acts onto the coiled spring while the interlocking member swings so as to interlock with the opening and closing valve being swung in an opening direction by a negative pressure exerted in the second intake air passage, is larger than {TAIL ~ a second urging force}, which is exerted by a spring elasticity of the coiled spring 
The second intake air passage is opened by the opening and closing valve when { HEAD ~ a first urging force } , which acts onto the coiled spring while the interlocking member swings so as to interlock with the opening and closing valve being swung in an opening direction by a negative pressure exerted in the second intake air passage , is larger than { TAIL ~ a second urging force } , which is exerted by a spring elasticity of the coiled spring
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH