| 主权项 |
1. An inline four-cylinder engine with two turbo chargers, in which four cylinders and exhaust ports of the four cylinders are arranged in line at a single cylinder head, exhaust gas from the exhaust ports is introduced to the two turbo chargers, and an exhaust valve and an intake valve of each cylinder have a valve overlap period during which the exhaust valve and the intake valve are both opened,
wherein exhaust passages of the engine which connect to the exhaust ports of the four cylinders are divided into two groups, each group being provided for two cylinders which comprise an end-portion cylinder positioned at an end portion, in a line direction, of the engine and a central-portion cylinder positioned beside said end-portion cylinder and having an ignition timing which is adjacent to an ignition timing of said end-portion cylinder such that said ignition timing of said central-portion cylinder and said ignition timing of end-portion cylinder are one of a relatively-early ignition timing and a relatively-late ignition timing respectively, said two turbo chargers are arranged for said two groups of exhaust passages one each, each of said two groups of exhaust passages is comprised of two independent cylinder pipes which independently connect to the exhaust ports of the two cylinders, each of said turbines of said two turbo chargers comprises a pair of turbine scrolls which are independently connected to said two cylinder pipes and a turbine wheel which is driven by the exhaust gas flowing down through said two cylinder pipes, the pair of turbine scrolls comprising an outside-positioned turbine scroll which is arranged at a relatively-outside position in the turbine so as to have a relatively-long distance from a rotational center of the turbine wheel and an inside-positioned turbine scroll which is arranged at a relatively-inside position in the turbine so as to have a relatively-short distance from the rotational center of the turbine wheel, and one of said two independent cylinder pipes for the cylinders having a relatively-early ignition timing is connected to said outside-positioned turbine scroll, and the other of said two cylinder pipes for the cylinders having a relatively-late ignition timing is connected to said inside-positioned turbine scroll. |
