Abstract:
Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor during selected engine no-fueling conditions. The learned zero point is used to infer EGR flow and accordingly adjust EGR valve control. In addition, EGR valve leakage is diagnosed based on the zero point learned during a DFSO adaptation relative to a zero point learned during an idle adaptation.
Abstract:
Methods and systems are provided for an engine including a first turbocharger having a first compressor and a second turbocharger having a second compressor. An EGR differential between the first compressor and the second compressor may be increased under a condensation condition, and decreased under a surge condition. The EGR differential may also be decreased when a compressor outlet temperature exceeds an outlet temperature threshold.
Abstract:
Methods and systems are provided for reducing torque transients experienced when a dedicated EGR cylinder is transitioned in to or out of dedicated EGR mode. During a transition, each of an intake throttle and a wastegate is adjusted in opposing directions. Throttle and wastegate adjustments are coordinated with adjustments to spark timing and intake cam timing to provide sufficient torque reserve for the transition.
Abstract:
Various systems and methods are provided for controlling the temperature of outlet gasses from a throttle bypass turbine. In one embodiment, a method of operating a throttle bypass turbine comprises controlling a temperature of outlet gas flowing out of the turbine by routing the outlet gas through an exhaust gas recirculation heat exchanger positioned in an exhaust gas recirculation passage, the turbine coupled to an intake passage.
Abstract:
Methods and systems are provided for injecting exhaust gases from an exhaust gas recirculation system proximate to a trailing edge of a compressor wheel of a compressor. In one example, a compressor of a turbocharger may include an exhaust gas recirculation inlet volute within a casting of the compressor. The exhaust gas recirculation inlet volute may include an injection port positioned downstream of the trailing edge of the compressor wheel for injecting exhaust gases into intake air flow.
Abstract:
Methods and systems are provided for operating an engine including a DEGR system during start-stop and DFSO conditions. In one example, the DEGR cylinder may be deactivated prior to deactivating the non-DEGR cylinder group and stopping the engine, to purge EGR from the intake system.
Abstract:
An engine is provided that includes an exhaust gas recirculation (EGR) conduit in fluidic communication with a first exhaust valve in a cylinder and an intake system, an exhaust conduit in fluidic communication with a second exhaust valve in the cylinder and an emission control device. During operation with the first valve active and the second valve deactivated, a fixed EGR level can be provided. However, during operation with the first valve deactivated and the second valve active, increased engine output can be achieved with reduced EGR without requiring additional exhaust throttling or switching valves.
Abstract:
Methods and systems are provided for a branch communication valve in a twin turbocharger system. A branch communication valve may be positioned adjacent to a dividing wall separating a first scroll and a second scroll of the twin turbocharger. In an open position, the branch communication valve increases fluid communication between the first scroll and the second scroll and in a closed position, the branch communication valve decreases fluid communication between the first scroll and the second scroll.
Abstract:
Methods and systems are provided for expediting EGR purging in a hybrid vehicle during transient operations, such as tip-out to lower load conditions. In response to decreasing engine torque demand, engine fueling is disabled and a motor is used to spin the engine unfueled until a desired LP-EGR rate is achieved. Alternatively, engine operation is maintained with EGR disabled until the desired LP-EGR rate is achieved, and the excess engine torque generated is stored in a system battery.
Abstract:
Methods and systems are provided for expediting purging of LP-EGR from an air intake system during conditions of decreasing engine load. During a tip-out, an EGR valve is closed while the engine is shifted to a VDE mode of operation to improve engine tolerance to EGR at lower engine loads and until the EGR is sufficiently purged. A non-VDE mode is resumed if higher engine loads are restored, else, a deceleration fuel shut-off mode is selected if the tip-out continues to zero load.