A turbocharger system includes a valve assembly with an inlet, a first outlet, and a second outlet. The inlet is configured for receiving flow of an exhaust gas from an engine. The valve assembly includes a valve structure disposed within a housing. The valve structure is configured to rotate about an axis of rotation between a first position and a second position. The valve structure defines a nonlinear flow passage with an axial upstream end and radial downstream end. The valve structure, in a first position, directs exhaust gas from the inlet to the first outlet and closes off the second outlet. The valve structure, in the second position, directs exhaust gas from the inlet to the second outlet and closes off the first outlet.

A turbocharger system includes a valve assembly with an inlet, a first outlet, and a second outlet. The inlet is configured for receiving flow of an exhaust gas from an engine. The valve assembly includes a valve structure disposed within a housing. The valve structure is configured to rotate about an axis of rotation between a first position and a second position. The valve structure defines a nonlinear flow passage with an axial upstream end and radial downstream end. The valve structure, in a first position, directs exhaust gas from the inlet to the first outlet and closes off the second outlet. The valve structure, in the second position, directs exhaust gas from the inlet to the second outlet and closes off the first outlet.

An engine control device is provided, which includes an engine body where a cylinder is formed, an exhaust passage through which exhaust gas discharged from the engine body circulates, a NO.sub.x sensor disposed in the exhaust passage and configured to detect a concentration of NO.sub.x in the exhaust gas, an injector configured to change an air-fuel ratio inside the cylinder, an in-cylinder temperature changer configured to change a temperature inside the cylinder, and a controller configured to control the injector and the exhaust shutter valve. The controller controls the injector based on a detection value of the NO.sub.x sensor to variably set the air-fuel ratio inside the cylinder, and when a particular condition that the air-fuel ratio inside the cylinder is leaner than a preset upper limit is satisfied, and causes the in-cylinder temperature changer to raise the temperature inside the cylinder.

An engine control device is provided, which includes an engine body where a cylinder is formed, an exhaust passage through which exhaust gas discharged from the engine body circulates, a NO.sub.x sensor disposed in the exhaust passage and configured to detect a concentration of NO.sub.x in the exhaust gas, an injector configured to change an air-fuel ratio inside the cylinder, an in-cylinder temperature changer configured to change a temperature inside the cylinder, and a controller configured to control the injector and the exhaust shutter valve. The controller controls the injector based on a detection value of the NO.sub.x sensor to variably set the air-fuel ratio inside the cylinder, and when a particular condition that the air-fuel ratio inside the cylinder is leaner than a preset upper limit is satisfied, and causes the in-cylinder temperature changer to raise the temperature inside the cylinder.

A vehicle exhaust system includes an exhaust pipe defining an exhaust gas flow path, a heat recovery device connected to the exhaust pipe, and a diverter valve that controls exhaust gas flow between the exhaust pipe and heat recovery device. The diverter valve is moveable between at least a heat recovery mode where the diverter valve blocks flow through the exhaust pipe and directs flow into the heat recovery device, a full bypass acoustic mode where the diverter valve blocks flow through the heat recovery device and directs flow through the exhaust pipe, a transition mode where the diverter valve partially blocks flow through the heat recovery device and partially blocks flow through the exhaust pipe, and a partial bypass acoustic mode where the diverter valve blocks flow through the heat recovery device and partially blocks flow through the exhaust pipe.

A vehicle exhaust system includes an exhaust pipe defining an exhaust gas flow path, a heat recovery device connected to the exhaust pipe, and a diverter valve that controls exhaust gas flow between the exhaust pipe and heat recovery device. The diverter valve is moveable between at least a heat recovery mode where the diverter valve blocks flow through the exhaust pipe and directs flow into the heat recovery device, a full bypass acoustic mode where the diverter valve blocks flow through the heat recovery device and directs flow through the exhaust pipe, a transition mode where the diverter valve partially blocks flow through the heat recovery device and partially blocks flow through the exhaust pipe, and a partial bypass acoustic mode where the diverter valve blocks flow through the heat recovery device and partially blocks flow through the exhaust pipe.

Methods and systems of recirculating exhaust gas in internal combustion engines are disclosed. An internal combustion engine includes a set of cylinders, an intake system disposed in fluid providing communication with the set of cylinders, an exhaust system disposed in fluid exchanging communication with the set of cylinders, and a controller. In response to a detected recirculation condition, the controller prevents fluid communication between the intake system and a subset of the set of cylinders and recirculates exhaust gas between the subset of the set of cylinders and the exhaust system.

Methods and systems of recirculating exhaust gas in internal combustion engines are disclosed. An internal combustion engine includes a set of cylinders, an intake system disposed in fluid providing communication with the set of cylinders, an exhaust system disposed in fluid exchanging communication with the set of cylinders, and a controller. In response to a detected recirculation condition, the controller prevents fluid communication between the intake system and a subset of the set of cylinders and recirculates exhaust gas between the subset of the set of cylinders and the exhaust system.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, a first set of exhaust valves coupled to the first exhaust manifold may be operated at a different timing than a second set of exhaust valves coupled to the second exhaust manifold. Further, a position of a first valve positioned in a first passage coupled between the intake passage and the first exhaust manifold and/or a timing of the first set of exhaust valves may be diagnosed based on an output of a pressure sensor positioned in the first exhaust manifold.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, a first set of exhaust valves coupled to the first exhaust manifold may be operated at a different timing than a second set of exhaust valves coupled to the second exhaust manifold. Further, a position of a first valve positioned in a first passage coupled between the intake passage and the first exhaust manifold and/or a timing of the first set of exhaust valves may be diagnosed based on an output of a pressure sensor positioned in the first exhaust manifold.