A comparison between two-position variable compression ratio and continuously variable compression ratio engines using numerical simulation

Malpress, Ray and Buttsworth, David R. (2009) A comparison between two-position variable compression ratio and continuously variable compression ratio engines using numerical simulation. In: ASME Internal Combustion Engine Division Fall Technical Conference (ICEF 2009), 27-30 Sep 2009, Lucerne, Switzerland.

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Fuel consumption for the New European Driving Cycle (NEDC) is assessed via numerical simulation for a vehicle operating with two types of variable compression ratio device: i) a continually variable compression ratio (VCR) device that optimises efficiency at all loads, and ii) a VCR device that allows the engine to operate at one of two discrete compression ratios. The simulated engine configuration uses late intake valve closing (LIVC). A maximum geometric compression ratio (GCR) of 17:1 is adopted in the simulations resulting in a constant effective compression ratio of 10.2:1 in all configurations. Reduction from full load is achieved in the simulation with LIVC until the maximum GCR is reached after which lower loads are achieved through throttling. In the two-position VCR engine simulation, the full load range is achieved through throttling in combination with LIVC. At part load, in combination with LIVC, the VCR devices increase the geometric compression ratio to return the effective compression ratio to that for full load in each case. The simulations indicate that the increase in net fuel consumption over a driving cycle is effectively no different for the two-position VCR engine relative to a continually variable CR and this justifies further research into two-position VCR technology. Net fuel consumption can also be improved by the use of a limited acceleration that maintains the engine in the reduced compression stroke configuration. An acceleration rate with a driver feedback mechanism is proposed which, in combination with a two-position VCR engine, shows potential for significant reduction in fuel consumption of greater than 15% relative to the full compression, fixed CR configuration for the NEDC.

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Item Type: Conference or Workshop Item (Commonwealth Reporting Category E) (Paper)
Refereed: Yes
Item Status: Live Archive
Additional Information: Copyright © 2009 by ASME. Permanent restricted access to paper due to publisher copyright restrictions.
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Mechanical and Mechatronic Engineering
Date Deposited: 10 Sep 2010 03:10
Last Modified: 19 Nov 2014 04:15
Uncontrolled Keywords: variable compression ratio; two-position; atkinson cycle; new european driving cycle
Fields of Research : 09 Engineering > 0902 Automotive Engineering > 090201 Automotive Combustion and Fuel Engineering (incl. Alternative/Renewable Fuels)
09 Engineering > 0913 Mechanical Engineering > 091307 Numerical Modelling and Mechanical Characterisation
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Identification Number or DOI: 10.1115/ICEF2009-14042
URI: http://eprints.usq.edu.au/id/eprint/5876

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