The Venturi Formula E team is contesting the 2015-16 season with a powertrain developed with McLaren and Hewland. It’s essentially an updated version of the first season set-up. Thus, the car has a McLaren inverter and motor, mated to a Hewland four speed gearbox and housed inside an aluminium case. For a blend of performance, reliability and cost, this has worked well for Venturi (and its season two customer team Dragon) but Renault e.dams and ABT Schaeffler Audi Sport have both shown that there’s more performance to be found with a clean sheet design.
This week, Venturi released teaser images of its season three development car via Twitter. The pictures reveal some tantalising details of its powertrain (shown above; highlighting is our own). What can we learn?
It’s immediately clear that the team has gone further with its development programme than with its current configuration. The teaser photo appears to show a repositioned motor and transmission – and a carbon fibre casing.
The presence of the McLaren inverter suggests that the British company remains a development partner. The single unit indicates that the powertrain will continue to feature a single motor, too. However, Venturi is now also partnering with ROHM to produce silicon carbide (SiC) switches inside the inverter, which would yield electrical, thermal and weight advantages over the IGBTs currently used within inverters. So it appears that the inverter design and manufacture will be a tripartite relationship between Venturi, ROHM and McLaren. It will be fascinating to see how that will unfold and where else the tech may be used.
The gear case appears to be made from carbon fibre and is probably just a semi-finished, unmachined bare casing used for mock-up purposes. Adopting a carbon case, even if it’s simply an outer structure to hold the suspension and a separate internal differential case, shows there is a significant step up in the technology adopted by Venturi. The cost and complexity in the use of carbon is balanced by the reward of reduced weight, which is especially important at the back of the rear-heavy car. Just look at Renault’s performance in Beijing for evidence (the French team is running an integrated gear casing and motor bellhousing, crafted from carbon fibre).
From the shape of the gear case, we can see there is space for a large diameter differential and ring gear. This suggests that the reduction in final drive gearing from the motor to the differential will mostly be from its outer gear, which in turn implies that there will not be a multi-ratio gearbox. It could be that Venturi elects to go for a single gear – or for a two-speed set-up, similar to that used by Renault.
Similarities to the Renault powertrain continue with the motor orientation. A1lthough the motor aperture in the casing isn’t visible in the leaked photo, the short length between the differential and the battery unit plus the size of the differential hints at a transverse motor mounting, identical to Renault’s.
The single inverter and very large reduction gear makes it likely that we’ll see a single radial flux motor in use. This separation of motor and inverter may mean a separate motor partner is involved.
In summary we can deduce that Venturi’s new format will be a Renault-style style set-up, with a single radial motor mounted laterally inside a carbon fibre casing and driving the differential through one or two gears. This will be a lighter solution than the team’s season two powertrain, and the simpler gear train should improve efficiency.
As ever, we await new spy photos eagerly as well as collective preseason testing this summer and we’ll bring you more season three powertrain details as we discover them.
Craig Scarborough is Current E’s technical editor.