FLUID DUCT, INTAKE DUCT FOR INTERNAL COMBUSTION ENGINE, AND INTAKE SYSTEM OF INTERNAL COMBUSTION ENGINE HAVING SAME INTAKE DUCT

摘要

The curved portion (22L, 22R) of a fluid duct is formed such that the centroid (G) of a cross section of the fluid passage in the curved portion (22L, 22R), which is taken along a direction of curvature radius (r) of the curved portion (22L, 22R), is offset to the outer peripheral side in the direction of curvature radius (r) from the middle position (m) of the entire width (w) of the fluid passage in the direction of curvature radius (r). Thus, the increase in the flow resistance in the curved portion can be minimized.