TECHNOLOGY - KERS
pressure to close the normally open clutches and transmit the drive, seamlessly changing from one gear to another with no torque interruption as the speed across the engaged clutch reduces to near zero. The total system cost is a
significant amount lower than previous offerings from Flybrid, itself significantly cheaper than other manufacturers’ battery- based KERS. ‘In terms of a cost comparison with our previous CVT-based systems, it’s about 70 per cent of the cost, even in low volumes. Part of the reason for that is there’s a lot of commonality – all the clutch packs are identical and all the hubs are the same, so we are making larger quantities of the same components, which helps us control the price. In comparison to electric hybrid, it is massively cheaper. I’d say our system is half the price of a comparable electric system.’
LMP1 APPLICATION The entire CFT system is mounted in a bespoke housing that, in the case of the ORECA 01 used by Hope Racing, sits between the car’s Xtrac transmission and a turbocharged, 2.0-litre, in-line four developed by Lehmann. But the CFT can also be located elsewhere on the powertrain (see fig 1, right). Despite looking quite sizeable, the addition of the CFT has not increased the wheelbase of the ORECA, something that highlights the versatility of the concept. ‘In this case it does not impact the wheelbase. Originally, the chassis was fitted with a Judd V10 and the wheelbase is the same as it was. It would be more of a challenge with a longer engine but, if you look at the installation, the flywheel sits above the clutch of the car, but not overlapped with it at all. There is 200mm or so of shortening you could do relatively easily. We have designed the gearing that sits between the CFT and the car gearbox so there are several options of gears available on the same centres, so the same hybrid system will suit a high revving N/A engine or a low revving turbo diesel.’ Despite this apparent
versatility, the CFT cannot yet be described as a fully off-the-shelf system, as it requires significant
Due to commonality of parts, the CVT KERS is significantly cheaper than current electric and battery-based systems on the market, which should see it gain more widespread use among smaller teams in the future
Locations for energy storage and recovery devices, when connected to driven axle
7 5 6 Gearbox Clutch 4 3 2
Prime mover
1
Figure 1: the CFT KERS device may be connected to a vehicle’s transmission in any of the locations numbered 1 to 7. When using connection locations 1 to 4, there is the advantage of multiplying the number of gears in the CFT by the number of gears in the vehicle gearbox. In locations 5 to 7 the CFT KERS may be configured with more than three gears, and the round trip losses for kinetic energy recovery are lower due to the proximity to the vehicle wheels
work to integrate with the other systems on a car. ‘Off the shelf is a funny term,’ says Hilton. ‘In terms of the hybrid system, yes, it is ‘off the shelf’ but, in terms of vehicle integration, it is not. Every car requires its own bit of work to make the software talk to the other elements of the car, so on the ORECA we are interfacing with a Bosch ECU, a Megaline control unit for the gearshift and a Cosworth logging
box for the ACO. So we have four control units all talking to each other. On other vehicles, which may use McLaren, Marelli or other systems, there is different work involved. It also requires a new bellhousing, but any customers who have bought an Xtrac 1059 2011 Sportscar gearbox, with the standard main case, already have one that is KERS ready, and effectively we can supply them with a kit of bits to turn it from a
standard car to a hybrid car. The only thing the chassis team need to do is fit a new bellhousing and find a location for the hydraulic block and KERS controller.’
EARLY TESTING
The initial running on the ORECA did not go entirely to plan, with a number of electronic system issues preventing the team completing all the testing they had hoped for. Also an issue with
Le Mans •
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