Methods and systems for boost control

Abstract

The invention discloses methods and systems for boost control. Methods and systems are provided for pressure control in a boosted engine system. A variable geometry turbine (VGT) geometry, and / or wastegate (WG), and / or an exhaust gas recirculation (EGR) valve opening is adjusted based a difference between the exhaust pressure and an intake pressure, and optionally other signals (e.g., engine speed, exhaust pressure) in order to reduce the difference between exhaust and intake manifold pressures, thereby reducing pumping work losses.

Description

technical field [0001] The description generally relates to methods and systems for pressure control in boosted engine systems. Background technique [0002] Engine systems may be configured with a boosting device, such as a turbocharger or supercharger, to provide a charge of charge air and improve peak power output, fuel economy, and emissions. A turbocharger may have a variable geometry turbine (VGT), in which the impeller vanes (or vanes) of the turbine are adjusted to vary boost pressure and exhaust pressure. The position of the VGT's impeller vanes may vary based on factors including engine speed, torque demand, desired response time, fuel economy, intake and exhaust manifold pressures, and emissions requirements. VGT tuning achieves reduced pumping losses by changing the aspect ratio of the turbocharger. [0003] One example method for adjusting VGT geometry is shown in Buckland et al. US 6,672,060. In it, the VGT geometry is adjusted by a feedback control loop tha...

AI Technical Summary

Problems solved by technology

During this period, high exhaust manifold pressure and exhaust pressure peaks lead to increased delta pressure across the engine, which increases engine pump work, which can adversely affect engine efficiency, performance, emissions, and fuel economy

Also, during this time, the expansion ratio of the turbine may increase excessively, which may cause damage to the turbocharger hardware

Additionally, such exhaust pressure peaks and high expansion ratios can lead to high cycle fatigue and ultimately degradation of several engine components such as seals, gaskets, exhaust valves and cylinder components

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