Automated manual transmissions back on the agenda
August 25, 2010 § Leave a comment
This month I have mostly been talking transmissions with senior driveline engineers at some of the world’s most-respected supplier firms. Some interesting trends are emerging in the gearbox world; full report’s to go in Transmission Technology International magazine, but here’s a brief summary.
- There’s great potential to reduce fuel consumption and emissions by focusing on improving gearboxes, and to make larger step-changes at lower cost than for engine enhancements, said the guy from BorgWarner.
- Dual-clutch transmissions (DCTs) such as Volkswagen’s DSG, Porsche’s PDK and Ford’s Powershift have been well-acclaimed globally, but sales haven’t yet matched up to forecasts (according to Ricardo) and take-up will be hampered by price. DCT’s good from an efficiency point of view as well as for driver enjoyment, but it’s complex and expensive (though there are ways to simplify its architecture, under study).
- Old-school torque-converter autos are still evolving: the latest eight-speeders (as fitted by BMW, Lexus) have shown that you can improve economy – and consumer appeal – by adding ratios. But this brings diminishing returns. The Japanese in particular still like CVT, and it’s well-suited for urban driving. Don’t write off either, just yet.
- Manual gearboxes? Still to be a majority in Europe for another decade or so, but there’s not much investment going on into development of all-new products.
- Most pundits wrote off automated manuals (no clutch pedal, usually self-shift with fully-auto mode) when DCT came along: too jerky, neither one thing nor another, some horrid examples (i.e. that of Smart Fortwo), lack of consumer interest (remember the BMW SMG?). But suppliers are looking at them again with renewed interest – intially as low-cost automation solutions for developing markets (Far East, India, South America etc.) but increasingly as an option for Europe once more.
- AMT is a. cheap to develop and build, and b. potentially very efficient. It works particularly well with stop-start systems (says the guy from Getrag), is well-suited to hybrids (there’s an AMT in the Peugeot 3008 Hybrid4) and even EVs (the Zeroshift multi-speed transmission for electric cars is a variant on the theme), and engineers like it ‘cos the ideal shift-points can be designed in (said the engineering chief from Prodrive). Good for economy, and good for meeting all those pesky legislative requirements on emissions. Both electronic and electrohydraulic systems are under development; further into the future dry-clutch structures are possible which are even more efficient.
- But will buyers like it? New-generation control software and systems integration tech smooths out the gearshifts; systems such as F1-style KERS (kinetic energy recovery) can be easily built in to further improve economy and act as a torque in-fill to ease the jerks in power delivery.
- No-one wants to call precisely which way the gearbox market is going – and certainly, they’re all still pushing DCT. But cost and fuel-efficiency are clearly defining factors behind development right now.