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Hybrid technology offers key opportunities for fuel economy and performance enhancement also in the sport cars application. The main driver of the technology is the vehicle requirements definition and the development of the components focused on efficiency, performances and weight reduction.

The legislation limits for pollutants emissions are strongly pushing OEMs to electrification of their vehicle fleet. Even high performance car manufacturers are taking on the challenge of using electrification - a trend also observed for premium and exotic vehicles. This electrification job is seen from some manufacturers as an opportunity to increase the vehicle performances while moving to more “green” powertrains. It means that the installation of electric power on the vehicle should certainly not affect the performances of the vehicle models with only an internal combustion engine, but increase the performances while cutting the pollutants emissions during driving. As such it is no easy task, since the hybrid system (battery, inverter, and electric motor) affects strongly the overall vehicle weight and thus its driving dynamics as well as system cost. On top of this most manufacturers look for synergies between hybrid and standard versions in order to minimize cost and investments of the overall vehicle platform. All the arguments above weigh even stronger focussing on high performance cars due to the challenges posed by low to medium production volumes. Because of this, modularity of the specific subsystems plays a key role during the concept selection.

Torque-fill capability during gearshifts is an important customer requirement in automated transmission systems. This functionality can be achieved through transmission system layouts (e.g., based on dual-clutch technology) characterized by significant mechanical complexity, and hence with relatively high cost and mass. This paper describes a parallel hybrid electric drivetrain concept, based on the integration of an electric motor drive into a relatively simple six-speed automated manual transmission. The resulting hybrid electric drivetrain actuates the torque-fill function through control of the electric motor torque during the gearshifts on the engine side of the drivetrain. An optimal controller, based on the off-line computation of the control gain profiles, is presented for the clutch re-engagement phase. The novel controller allows computationally efficient consideration of clutch energy dissipation during the clutch re-engagement phase of the gearshift. The performance with the optimal controller is contrasted with that of two conventional clutch engagement controllers, along a set of gearshifts simulated with an experimentally validated vehicle model.

Because of the introduction of progressively more restrictive regulations that aim to reduce fuel consumption and CO2 emissions, the automotive industry is focusing its efforts on environmentally friendly passenger cars. In particular, different electrification roadmaps are pursued by the individual car makers, and electrified drivetrain layouts are progressively introduced into the market. This process involves all vehicle segments, including high performance passenger cars. In this context, this study presents a novel hybridized automated manual transmission (HAMT) for cars with high power characteristics. The HAMT includes six gear ratios associated with the internal combustion engine, and two gear ratios associated with an electric motor. The energy efficiency of the HAMT is measured on a drivetrain test rig, and compared with that of an equivalent dual clutch transmission (DCT). Simulation results based on the experimentally measured efficiency maps show the significant energy consumption reduction of the HAMT in its internal combustion engine mode, with respect to the DCT.

Oerlikon Graziano has designed and patented an elegant DHT concept, starting from the know-how cumulated in the last years from the concept of the OGeco transmission, previously presented at the CTI Berlin. This has been achieved by continuous improvement activities ongoing on the demo vehicle and focusing on the market needs. The transmission is a modular concept which starts from a traditional 2-shaft single-clutch transmission. Thanks to a link between two main gears of the gearbox and the direct gearing between the electric machine and this linked gear arrangement, free-mounted on the primary shaft, the concept allows a very efficient electric path of the transmission, which presents two different gear ratios between the electric machine and the secondary shaft. The solution is particularly innovative, because keeping a very simple and well known architecture (therefore cost effective), it allows the connections to be made with standard transmission components, selectively coupling the electric machine to either the primary or the secondary shaft. This feature, then, represents a mixed P2-P3 hybrid architecture and therefore takes the advantages of both (e.g. powershifting-P3, recuperation-P3, cranking-P2, standstill charging-P2). It allows a performance increase of up to 40% on 0–100 kph and up to 25% benefit on CO2 emission, with a charge-sustaining strategy for the battery, with the installed electric power being 30% of the total. Thanks to its scalability and to the possibility of having different power-split configurations the system can be used both as a mild-hybrid or as a plug-in hybrid solution, within a 48V or HV system.

The paper describes the advantages due to the adoption of multi-speed transmission systems within fully electric vehicles. In particular, the article compares a conventional single-speed transmission layout, a 2-speed layout based on a novel gearbox architecture capable of seamless gearshifts, and a Continuously Variable Transmission layout. The selection of the optimal gear ratios for the 2-speed system has been based on an optimization procedure, taking into account the efficiency characteristics of the components of the whole vehicle powertrain. The control system for the Continuously Variable Transmission system has been designed with the aim of maximizing the efficiency of the operating points of the electric motor. The results show that there is a significant advantage in adopting a 2-speed transmission system over the single-speed layout, and, despite a reduction in motor losses, the typically lower efficiency characteristics of Continuously Variable Transmissions do not result in lower energy consumption for the four case study vehicles.

This paper deals with the simulation of the low frequency drivability of through-the-road parallel (TTRP) hybrid electric vehicles (HEVs). The current literature relating to HEVs is predominantly focused on energy efficiency optimisation. However, the drivability of this HEV typology can be particularly critical, due to the interaction of the front and rear axle dynamics. The article presents an experimentally validated non-linear model of a TTRP HEV, consisting of a front axle driven by an internal combustion engine (ICE) with a six-speed transmission, and a rear axle powered by an electric motor with a prototype two-speed transmission. The simulated TTRP HEV is then considered with both driven axles, and drivability manoeuvres in conditions of constant gear are carried out. The results are analysed to study acceleration and jerk profiles, and understand the anti-jerk control system fundamentals through linearisation methods.

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.