Renault Group

The origins of E-TECH technology

episode 2


Using its expertise in electric vehicles, its experience in Formula 1 and with the enthusiasm and passion of its engineering, development and control teams, Renault has developed the innovative hybrid E-TECH powertrain. Offered in a “full hybrid” version on the Clio and in a “full rechargeable hybrid” version on the New Captur and New Mégane, this was invented and developed in a way that was both unusual and truly inspiring. In this second instalment, the LEGO bricks give way to EOLAB, the futuristic prototype.
2014 EOLAB concept-car

#1 A 1 litre per 100 kilometer demonstrator

A quick leap through time to arrive at the Paris Motor Show 2014, a few years after the “development” of the LEGO model. Renault gives the world its first glimpse not only of the 5th generation Espace, but also of EOLAB, its vision of the ultra-refined car of tomorrow. Beneath the bonnet of this road-ready show car, with its proven record fuel consumption of 1L/100 km, there is a rechargeable hybrid powertrain. It consists of a 3-cylinder petrol engine, an electric traction engine and… an innovative, clutchless 3-speed transmission: two of the speeds are mated with the electric traction engine, the third with the combustion engine. Together, these three speeds allow nine operating combinations of combustion and electric traction on EOLAB. Does that remind you of anything?

You’ve got it! This is just what Nicolas Fremau had envisaged four years previously as he assembled his LEGO transmission! Meanwhile, he had to call on the ingenuity of the teams once again. This time, it would be to build the first real prototype of the transmission that was destined to be at the heart of the future E-TECH hybrid system. A collaborative effort which has left behind several souvenirs, such as this development video, and which will end with the presentation of a Dacia “Z.E. on demand” hybrid engine at Innov’Days 2012, thus meeting the timescale of 14 months initially required by the then management team.

#2 An inevitable coming together

At the same time, another engineering team, led by Laurent Taupin is working on a prototype for a vehicle with ultra-low fuel consumption, called EOLAB. The effort to get below the threshold of 2 litres/100 km, the goal set for car manufacturers by the then government, is focused on three areas: a lighter vehicle platform and body, a high level of aerodynamism and the most economical traction chain possible.
We had a quantified objective: to get a city car the size of a Clio, in other words, 4 metres in length, to lose 400 kilos. However, this had to be done with no added cost, and without getting rid of any of the features offered to the customers. With its lowered, sharply sloping roof, EOLAB made us review the position of the passengers: they had to be low down and further forwards. We had to lower the bottom of the windscreen too to maintain good visibility. This caused a real “housing crisis” under the bonnet, as the volume of the engine compartment had shrunk.
Laurent Taupin
EOLAB Project Leader
Hybrid powertain installation

And it wasn’t just the volume. The narrowness of the EOLAB platform constrained the width of the powertrain. At that time, no hybrid engine with a clutch could be installed in the space available. Except for … the “Z.E. on demand” engine, which matched the specifications to a T: it used a Twingo combustion engine (H4BT, or TCe 90), tilted 49° to the rear, making it easier to install on the EOLAB subframe, and the much-vaunted clutchless, 3-speed gearbox, making the whole more compact. And it wasn’t just its dimensions that met the requirements, it ticked lots of other major boxes too: its simplicity guaranteed the reliability of the EOLAB prototype, it had no unnecessary weight penalties and, as it prioritised electric mode, it minimised the fossil fuel requirements on the road. Lastly, with a battery installed to the rear of the platform, the EOLAB prototype’s centre of gravity could be lowered and re-positioned, thus improving safety and the driving experience.

The EOLAB-Z.E. on demand combination soon became the obvious solution as, if we were to see the project through to a successful conclusion, it would be necessary to create a lighter vehicle at the same time as designing a lighter powertrain that used an innovative technology. This gave us two complementary ways of fulfilling Renault’s requirement, in other words, the provision of a smart, frugal solution accessible to all. There was a need for this car to find its engine and for this engine to finds its car. They found each other at the start of 2013.

Laurent Taupin

EOLAB Project Leader

#3 Sleepless nights, cold sweats

Now the development phase starts, and the aim is to be ready for the Paris Motor Show in the autumn of 2014. In Lardy (engines) and in Aubevoye (vehicle), the teams get cracking. The designers talk to the aerodynamics engineers, the mechanical engineers work with the materials specialists, the engine designers set out to find the most suitable battery. Everyone has the same objective, as defined by Laurent Taupin: the reduction of CO2 emissions, the common objective of all of the disciplines engaged in the project.
Tighter engine compartment

The task is far from easy. The reliability of the E-TECH system that we know today had yet to be achieved, and the way it worked was, at times, chaotic. So there were many months of slaving late into the night, especially during the summer of 2014, inventing and re-inventing, to get EOLAB and its brand-new powertain operational. Laurent Taupin and his teams had many sleepless nights and got the cold sweats and, at times, it would have been easy to lose heart. However, the human adventure on which they had embarked was only ever going to end in success.

The main difficulty lay in the gear changes, which had to be smooth and without flat spots, despite the lack of a clutch. Now, we had no problem with the latter, except for a really troublesome flat spot that made itself felt between the 2nd and 3rd speed if the driver kept their foot on the accelerator. Add to that a horrible whining noise at every gear change because the dog clutches had been poorly machined. The feeling in the meetings changed and many times the prototype was brought back by the recovery truck. We can admit it today, but a few hours before we were due to let the journalists loose on the EOLAB prototype at Mortefontaine, at the sidelines of the Paris Motor Show, we didn’t really know if everything would go as planned.

Laurent Taupin
EOLAB Project Leader

However, as Laurent Hurgon, our in-house professional driver, had successfully pushed the vehicle to its limits, there was every chance that the test drives would run smoothly. That is exactly what happened. The journalists were won over by a prototype that they could really put through its paces, especially when it lived up to its promises: 1 litre/100 km with no loss of dynamism (0-100 km/h in 9.2 seconds) or handling.

Henceforth, the E-TECH powertrain not only had a solid base, but it had also demonstrated its value on the road. All that was needed was to optimise its operation for it to be installed in production vehicles.