Title: Scavenging in a turbocharged gasoline engine

Authors: Amey Y. Karnik; Mrdjan J. Jankovic; Michael H. Shelby

Addresses: Powertrain Research and Advanced Enginnering, Ford Research and Innovation Centre, Dearborn, MI 48121, USA ' Powertrain Research and Advanced Enginnering, Ford Research and Innovation Centre, Dearborn, MI 48121, USA ' Powertrain Research and Advanced Enginnering, Ford Research and Innovation Centre, Dearborn, MI 48121, USA

Abstract: The phenomenon of air escaping the engine intake directly to the exhaust during valve overlap is commonly known as scavenging. This phenomenon is primarily observed at low-speed, high-load in engines with significant overlap between intake valve opening and exhaust valve closing. Evaluation on a turbocharged-gasoline engine shows increased low-speed torque when operating under scavenging conditions. This paper investigates the occurrence of scavenging and analyzes its consequences. A methodology is presented to infer the amount of scavenging using airflow and in-cylinder pressure measurements. Scavenging increases catalyst exotherm when operating with stoichiometric exhaust. A model is proposed to predict the additional exotherm.

Keywords: post-oxidation; scavenging; turbocharging; valve overlap; turbocharged gasoline engines; petrol engines; intake valve opening; exhaust valve closing; low speed torque; modelling; air flow; in-cylinder pressure.

DOI: 10.1504/IJPT.2012.049630

International Journal of Powertrains, 2012 Vol.1 No.4, pp.420 - 437

Received: 03 May 2011
Accepted: 25 Oct 2011
Published online: 05 Dec 2014 *

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