Turbocharged internal combustion engine with a portion of exhaust gases from engine bypassing turbocharger turbine for rapid catalyst light-off without waste gate performance penalty in turbine

An engine system, comprising:

• an internal combustion engine having a plurality of cylinders, wherein the engine cylinders are divided into a first sub-group of cylinders and a second sub-group of cylinders, each cylinder of both first and second sub-groups of cylinders having a main exhaust valve for discharging exhaust gases from the cylinders;
• an exhaust manifold system comprising a main exhaust manifold that receives exhaust gases from the second sub-group of cylinders, and a bypass exhaust manifold that receives exhaust gases from the first sub-group of cylinders;
• a bypass line coupled to the bypass exhaust manifold to receive exhaust gases therefrom;
• an exhaust gas feed conduit coupled to the main exhaust manifold to receive exhaust gases therefrom;
• a first turbocharger comprising a first compressor and a first turbine, the first turbine comprising an exhaust gas inlet coupled to the exhaust gas feed conduit to receive exhaust gases therefrom, and comprising an exhaust gas discharge conduit for discharging exhaust gases that have passed through the first turbine, a downstream end of the bypass line being coupled to the exhaust gas discharge conduit;
• and
• a partial-engine bypass valve system disposed between the engine cylinders and the turbocharger, the partial-engine bypass valve system defining a non-bypass position and a bypass position, wherein the partial-engine bypass valve system comprises a bypass exhaust valve for each cylinder of the first sub-group of cylinders, each bypass exhaust valve being coupled to the bypass exhaust manifold to feed exhaust gases from the first sub-group of cylinders into the bypass exhaust manifold when the bypass exhaust valve is open, each main exhaust valve being coupled to the main exhaust manifold to feed exhaust gases from the all cylinders into the main exhaust manifold when the main exhaust valves are open,
• wherein in the non-bypass position, during an exhaust phase of each engine cycle, the bypass exhaust valve(s) remain closed while the main exhaust valves open, such that exhaust gases from the first sub-group of cylinders flow directly into the main exhaust manifold and exhaust gases from the second sub-group of cylinders flow directly into the main exhaust manifold for supply to the first turbine, while exhaust gases are prevented from flowing from any of the engine cylinders to the bypass exhaust manifold,
• wherein in the bypass position, during an exhaust phase of each engine cycle, the bypass exhaust valve(s) of the first sub-group of cylinders and the main exhaust valves of the second sub-group of cylinders open, while the main exhaust valve(s) of the first sub-group of cylinders closes, such that exhaust gases from the first sub-group of cylinders flow into the bypass exhaust manifold and thereby bypass the first turbine, and exhaust gases from the second sub-group of cylinders flow into the main exhaust manifold for supply to the first turbine.