Audi R18 e-tron Quattro a Closer Look at the Hybrid Race Car

Since its inception the 24 Hours of Le Mans has been the true test of endurance. Races such as the Le Mans and Formula One are the breeding ground for new technology and technology maturation. It is here that we get to see what works, what doesn’t, and what’s reliable. As we begin to learn more and more about the successful advancements, the likelihood that you will see some of these features on cars off the track become more of a reality. Audi is one of the automakers that continues to innovate and remains on the cutting edge.

Since 1999 Audi has won 11 of the past 13 races at Le Mans. Words like dominating, leaders and innovators come to mind when describing the critical role Audi has played in the race that is held yearly at the Circuit de la Sarthe near the town of Le Mans.

Audi’s win this year comes to mark the first time that a hybrid vehicle has won the race. Once again, continuing their storied legacy of technological leaps and Le Mans “first”. In 2005 Audi challenged itself by introducing the Audi R10 TDI, that year The R10 TDI took first place and was Le Man’s first diesel powered car to do so. Since then Audi has continued to run a diesel engine in its Le Mans race cars. The Audi R18 e-tron Quattros is a (mostly) rear wheel drive turbocharged diesel hybrid that outputs 510 horsepower.  I say mostly, because what makes the Audi R18 unique is the hybrid system that powers the front wheels.

The Audi R18 e-tron utilizes a Kinetic Energy Recovery System, or KERS. KERS works by recovering the kinetic energy that is created during the car’s braking process, storing that energy and allowing it to be used at a later time. KERS has been around for a few years and has made an impact in Formula One racing. The difference between Formula One and Le Mans is how they regulate the use of KERS. F1 limits the amount of stored energy to 400kJ per lap, which equates to around 80 hp for around six seconds. In the Le Mans race, the boost is automatically engaged at certain brake points, allowing up to 500kj or around 160hp for around four seconds.

So, let’s delve a little deeper into how this simple concept works, and how it plays a role in racing.

Currently there are two types of KERS, both happen to be present in this year’s 24 Hours of Le Mans. The Toyota team, who also entered a hybrid vehicle into the race, chose to use a battery or electrical method. This approach places a generator that’s built in-between the transmission and engine to store energy via a battery or in Toyota’s case a high energy capacitor. The energy is stored in the capacitor and can later be introduced into the drive train for an extra boost in acceleration.

Audi chose to employ the flywheel method, the flywheel system is a much simpler design, however it cannot store energy as long as the electrical method.  Here we have a high speed flywheel connected to an electric motor in the transmission to store the energy rather than capacitors. The stored energy in the rotating flywheel can then be reintroduced to an electric motor that is then used to assist in acceleration.

Audi chose an interesting way to utilize this technology. Instead of keeping the vehicle purely rear wheel drive, Audi decided to use the additional energy by the KERS to power the front wheels only. Unlike in Formula One cars, where the driver can press a button to engage the additional boost in acceleration, Audi reintroduces the power once the car exits the turn and accelerates past 120 km/h or about 75 mph. This helps the car accelerate quickly out of turns, utilizing basically free power.  The Audi team stated that the front wheel drive system works great in the rain, and would have provided a tremendous advantage had it rained during the race.

The KERS technology is another reason that automakers and race teams continue to promote hybrid technology. As its use continues, hybrids will become more affordable and reliable. As long as companies such as Audi, and the regulations in motorsports continue to be open to innovation, we will begin to see a great change in our cars, trucks, buses and other vehicles that will be more efficient and hopefully fun to drive.


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