Q&A: Didier Lexa at Getrag
Dual-clutch transmissions strategy, how commodity prices affect actuation systems, and why automated manuals won't make a omeback
- Published in Q&A.
Didier Lexa, Getrag's chief technology officer
What can you do to improve your dual-clutch transmissions?
We have to continue to be better than automatics in terms of fuel efficiency. They're better in terms of the number of speeds – nobody knows if that’s really needed. We want to improve transmission efficiency but it won't be a major breakthrough: you have to work on many things to reduce parasitic losses, such as pump on demand for actuation and low viscosity oil in wet clutches.Your core DCT family has six speeds: is there a benefit in having more, or could you achieve a wider ratio spread with just six?
We can now package six and seven speeds in the same architecture. It might be necessary for some applications, but six already gives us better fuel efficiency than eight- and nine-speed automatics. The next step will be transmissions which also have electric motors.
Do you see opportunities for lower-cost DCT applications, or is it better to focus on the mid- and premium segments?
You have two types of application: front-wheel drive – which is 80% of the volume – and inline. For inline we're focusing on niche applications such as Ferrari and BMW. It’s important to have this kind of business because it helps us to stay ahead of the competition in terms of product development, but it’s not going to be a volume product. On front-wheel drive the situation is completely different; fuel efficiency is the main driver.
Could you improve the efficiency of high-torque applications using dry clutches?
As long as we have to consider towing and gradients, you have to design clutches able to sustain these conditions. We'll have to stay with wet clutches to get the heat out. But wet clutches are coming quite close to dry clutches in terms of efficiency, so if you want to have a compromise between low inertia – which is important for new gasoline engines – and good efficiency, then you might go for wet, even for small DCTs. Our strategy is to have both.
What's happening with actuation technology?
Electromechanical systems are being phased-out due to the copper price. From a technical view, it’s a good solution because you only use energy when it’s needed. But the boundary conditions are changing fast; rare earth metals are going sky-high too. And that’s why we have to think about going back to hydraulic actuation systems because they might be more cost-effective.
More suppliers are making DCTs now – how does that affect you?
Maybe it’s going to help us, because every OEM is coming to the conclusion that they need one. So that’s increased demand. Cost-pressure is going to increase too: as soon as you go from a niche-type product to high volume, you have to show a roadmap for price competitiveness. We've started to go in that direction with DCTs.
And manual transmissions: what more can you do with these?
They're good on weight-to-torque ratio and efficiency, but there are areas where you can gain maybe 0.5 or 0.8 percentage point improvements – we're looking at every way of reducing parasitic losses. We also are thinking about, for some applications, going to seven-speeds. Shifting should also be best-in-class; we're doing a lot of work on this. You'll see it on our 6MTT250 – that’s going to be a new generation of front-wheel drive transmission, for medium-torque applications, which will also be very flexible in terms of gear ratios.
What do you think of automated manual transmissions?
All the attributes are there except for shift comfort. You have to invest in hybridisation to get rid of torque interruption so I don't think it's going to become mainstream. If you look at India and China, you could say they're very cost-conscious and also very efficiency-conscious so they should go for it. But why should they accept a comfort issue that nobody else accepts?
