MOTORSPORT
“The Toyota Hybrid System – Racing (THS-R) is an evolution of the technology that helped the Supra HV-R win at Tokachi,” says Murata. “Of course, there have been significant advances over the past five years so the system is more efficient, lighter and delivers better performance, but it can be considered part of the same story.” The Toyota engineer believes this was an essential step in the evolution of hybrid systems for motorsport. “Toyota learned a huge amount from this experience. We were able to better understand the demands and challenges of racing a hybrid system, so this experience took us a big step closer to the dream of racing a Toyota hybrid at Le Mans.” In recent years, the ACO has opened up the rules to encourage hybrids, but with certain limitations. The maximum energy that can be generated in any braking event is 500MJ and that can only be harvested and delivered to either the front or rear wheels. Rather than committing to one or the other, Toyota has kept its options open by configuring the car to do either. This does not come without some compromises – most significantly weight distribution. Placing motor generators in the front adds weight. However, taking them and their associated driveshafts away causes a rearward weight shift at odds with the aero downforce balance, so they have to be replaced with ballast. This aggravates a problem with the weight of the system, which is believed to be more than 150kg – a big part of the 900kg total. For the rear version, a Denso-developed motor-generator is hooked up to the transmission. The company is an official partner and was also responsible for the 2007 Supra units. At the front, an Aisin AW motor generator is being evaluated. If a front-mounted system is used, then there is the theoretical possibility of using it to influence the handling. However, the rules dictate that the frontmounted option cannot be used to power the car below 120km/h (75mph), severely limiting that potential. According to Vasselon, the benefit is not just the performance, but efficiency: “For any given performance level, a hybrid powertrain will achieve this with less fuel,
Q+A: YOSHIAKI KINOSHITA, TOYOTA RACING TEAM PRESIDENT What is your assessment of Toyota Racing’s first race? It was very promising but ultimately disappointing. It was our dream to lead the race and to do so, even for only a short time, was fantastic. Of course, Anthony’s accident was a scary moment, and a turning point in the race. We all wish him a speedy recovery; it was difficult to enjoy the race after that. Unfortunately we faced some problems on #7 and had to retire. It is normal we had to deal with some technical issues in the race because our car is very young and we have not had enough testing, but nevertheless it was an extremely sad moment for us. We leave Le Mans with several areas to improve for future races but we can also be proud; the whole team gave everything they had and I want to say thank you for their great efforts. In your opinion, how did the Toyota Hybrid System perform? In the first place, it is a significant achievement from the Motor Sport Division and the Toyota Motor Corporation hybrid department team to bring such technology to Le Mans. In terms of performance we are happy with how the hybrid system contributed to our overall speed. I think we showed that our concept has strong promise and we continue to work hard on reliability. How did you enjoy the competition with Audi? We did not know if we could fight with Audi, so we enjoyed the battle while it lasted. Big congratulations to Audi on their well-deserved victory. Le Mans is an extremely hard race to win and they did a fantastic job. As well as being tough competitors on the track, Audi were also very welcoming and friendly; it was a pleasure to race with them. It was also an honor to join their victory party on Sunday and hear the appreciative words of Dr Ullrich. We look forward to some exciting battles in the future and some fun moments between us as well. What is the team’s plan for the rest of the season? We will compete in the rest of the FIA World Endurance Championship races with one car. That means five races in which to learn about our car and hopefully improve; our target is simply to show our best possible performance at each race.
Toyota’s driver line-up included the two-time Le Mans winner Alex Wurz, emerging endurance star Nicolas Lapierre and ex-F1 driver, Kazuki Nakajima
“Just leaving the garage on the electric power is very futuristic. Then when you let the clutch go and the internal combustion engine kicks in, it’s like an old friend has returned” 78 // July 2012 // Electric & Hybrid Vehicle Technology International
so it is an extremely relevant technology and one we are excited to bring to endurance racing.” Packaging was less of an issue in a sportscar than it would have been in a single seater, and the Nisshinbo capacitors occupy the space provided for a theoretical passenger. “The main advantage of supercapacitors is the very quick energy recovery rates, which enable the system to fully recharge in a short period of braking,” says Murata. “This is a key point in developing a hybrid system that will deliver extra laptime performance.” With the amount of power storage required, lithium-ion batteries would have performed far worse, as well as generating unwelcome heat. The TS030 can even operate in electric-only mode for short distances and was an eerie sight in pre-season testing, trundling up the pitlane on electric power before letting the engine kick in. “Just leaving the garage on the electric power is very futuristic,” says driver Alex Wurz. “Then when you let the clutch go and the IC engine kicks in, it’s like an old friend has returned.” And this is not just a marketing exercise, says Murata: “We expect the knowledge we gain from our WEC program to contribute to hybrid road car development, but it is too soon to say positively that supercapacitors will be part of that technology transfer. The demands of a road car hybrid system are very different to motorsport in terms of energy recovery and braking distances, so the energy storage method is not necessarily interchangeable.”