TWO-STAGE TURBOCHARGER SYSTEM, INTERNAL COMBUSTION ENGINE, AND METHOD FOR CONTROLLING TWO-STAGE TURBOCHARGER SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a two-stage turbocharger system, an internal combustion engine, and a method for controlling the two-stage turbocharger system, in which high turbocharger formation can be attained without being influenced by constraining conditions of an outlet temperature of a compressor installed at a downstream side by a cooling device of the turbocharger and further it is possible to avoid deterioration of an engine performance, such as a fuel consumption, by selecting an operation range where the cooling device of the turbocharger is used.SOLUTION: A two-stage turbocharger system comprises: between a low pressure stage compressor 12b and a high pressure stage compressor 11b, a usual sucking air passage 13 and a cooling air sucking passage 15 bypassing the usual air sucking passage 13 and provided with a turbocharger cooling unit 14; a three-way solenoid valve 16 for changing-over the usual sucking air passage 13 to the cooling air sucking passage 15 in one case in which an outlet temperature Tis higher than a temperature determination value T' and in the other case in which a refrigerant temperature Tis lower than an outlet temperature Tand a turbocharger pressure Pis larger than a pressure determination value P', and, in the other further cases, changing-over it to the usual sucking air passage 13; and an ECU 17 for controlling the three-way solenoid valve 16.