Turbocharger system with turbine bypass circuit to reduce emissions during engine cold start

An engine system comprising:

• an engine including a cylinder head defining first and second exhaust manifolds each having an outlet port and a bypass runner, wherein the cylinder head has a first boss defining the outlet port of the first manifold, a second boss defining the outlet port of the second manifold, and a third boss defining a first outlet port of the bypass runner of the first manifold and a second outlet port of the bypass runner of the second manifold;
• a first turbocharger in fluid communication with the outlet port of the first manifold;
• a second turbocharger in fluid communication with the outlet port of the second manifold;
• an exhaust aftertreatment device in fluid communication with the first and second turbochargers;
• and
• a turbocharger bypass circuit including a valve assembly having an inlet side connected in fluid communication with the bypass runners of the first and second manifolds, an outlet side in fluid communication with the aftertreatment device, and a valve having an open position in which the inlet and outlet sides are in fluid communication and a closed position in which the inlet and outlet sides are not in fluid communication, wherein the first turbocharger is attached to the first boss, the second turbocharger is attached to the second boss, and the valve assembly is attached to the third boss.

An engine system comprising:

• an engine including a block defining first and second sets of cylinders, reciprocating pistons each disposed in one of the cylinders, and a crankshaft connected to all of the pistons;
• a first turbocharger including variable geometry turbine in fluid communication only with the first set of engine cylinders;
• a second turbocharger including variable geometry turbine in fluid communication only with the second set of engine cylinders;
• a turbocharger bypass circuit including a valve assembly mounted to the block and having an inlet side in fluid communication with the first and second sets of engine cylinders and an outlet side in fluid communication with an exhaust aftertreatment device;
• and
• a controller programmed to:
• in response to a catalyst temperature of the aftertreatment device being less than a threshold, command a valve of the valve assembly to an open position,
• in response to the catalyst temperature of the aftertreatment device exceeding the threshold, command the valve to a closed position,
• in response to the catalyst temperature being less than the threshold, command the variable geometry turbines to a closed position, and
• in response to the catalyst temperature exceeding the threshold, command the variable geometry turbines to an open position.