Title: A novel clutchless multiple-speed transmission for electric axles

Authors: Aldo Sorniotti; Thomas Holdstock; Mike Everitt; Marco Fracchia; Fabio Viotto; Carlo Cavallino; Stefano Bertolotto

Addresses: University of Surrey, Guildford, Surrey, GU2 7XH, UK ' University of Surrey, Guildford, Surrey, GU2 7XH, UK ' Vocis Driveline Controls, American Barns, Banbury Road, Lighthorne, Warwick, CV35 0AE, UK ' Vocis Driveline Controls, American Barns, Banbury Road, Lighthorne, Warwick, CV35 0AE, UK ' Oerlikon Graziano SpA, Via Cumiana 14, 10098 Rivoli (Torino), Italy ' Oerlikon Graziano SpA, Via Cumiana 14, 10098 Rivoli (Torino), Italy ' Oerlikon Graziano SpA, Via Cumiana 14, 10098 Rivoli (Torino), Italy

Abstract: Fully electric vehicles and range-extended electric vehicles can be characterised by a multitude of possible powertrain layouts, many of them currently under investigation and comparison. This contribution presents a novel clutchless seamless four-speed transmission system which can be concurrently driven by two electric motor drives, for use in fully electric vehicles or electric axles for through-the-road parallel hybrid electric vehicles. The transmission system allows the electric motors to work in their high efficiency region for a longer period during a typical driving schedule. This paper describes the layout of the novel transmission system, the equations for modelling its dynamics and the criteria for the selection of the best gearshift maps for energy efficiency. Finally, an energy consumption and performance comparison between the novel drivetrain, a conventional single-speed electric drivetrain and a double-speed electric drivetrain is discussed in detail for two case study vehicles.

Keywords: electric vehicles; electric drivetrain; clutchless transmission systems; seamless transmission systems; gearshift; multi-speed transmission; electric axles; powertrain layouts; dynamic modelling; energy efficiency; energy consumption.

DOI: 10.1504/IJPT.2013.054155

International Journal of Powertrains, 2013 Vol.2 No.2/3, pp.103 - 131

Available online: 26 May 2013

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