Air-supplying structure for multi-cylinder engine

Claim 1

An air supplying structure for multi-cylinder engine for conducting a two-staged supercharging to an engine body totally including 18 pieces of cylinders comprising nine pieces of cylinders serially arranged in one bank and nine pieces of cylinders serially arranged in the other bank, said air supplying structure for multi-cylinder engine comprising: totally six sets of supercharging units, each set of the supercharging units being constituted of a low-pressure stage supercharger and a high-pressure stage supercharger which are series arranged with each other so as to conduct the two-staged supercharging; each of said high-pressure stage superchargers including a compressor having an outlet connected to three pieces of adjacent cylinders which are provided in the same bank of said engine body; totally six pieces of aftercoolers, each aftercooler being connected to an intake air passage between each of said high-pressure stage superchargers and three pieces of cylinders; and totally two pieces of intercoolers, each intercooler being connected to the outlets of compressors of three pieces of said low-pressure stage superchargers; wherein said two pieces of intercoolers are arranged at the opposite sides of said engine body, respectively, along the arranging direction of said cylinders; wherein the three pieces of said low-pressure stage superchargers to be connected to one intercooler of said two pieces of intercoolers are connected, through said high-pressure stage superchargers series arranged to the three pieces of low-pressure stage superchargers, to the three pieces of cylinders in the one bank and the six pieces of cylinders in the other bank, which cylinders are arranged near the one intercooler; and wherein the three pieces of said low-pressure stage superchargers to be connected to the other intercooler of said two pieces of intercoolers are connected, through said high-pressure stage superchargers series arranged to the three pieces of low-pressure stage superchargers, to the six pieces of cylinders in the one bank and the three pieces of cylinders in the other bank, which cylinders are arranged near the outer intercooler.