German supplier Schaeffler is counting on the electrification of the clutch to boost the fuel economy and driving comfort of manual transmissions without a significant increase in the cost of the world’s most popular gearbox.
Matthias Zink, who is global head of Schaeffler's transmission systems division, told Automotive News Europe that 10 vehicles fitted with the company's e-clutch solutions are being tested by automakers. He declined to name the brands conducting the tests, but Zink said he expects one of Schaeffler's solutions to be in a production vehicle by mid-2018. The attraction of adding an e-clutch to a manual is that it makes it possible to put the engine into idle mode or to switch it off, allowing the vehicle to coast, which improves fuel economy and reduces emissions.
"Coasting is a sort of stop-start in motion. That means a manual transmission equipped with an electronic clutch could reduce real-driving fuel consumption by more than 8 percent," Zink said. Schaeffler's entry e-clutch, which the supplier calls MTPlus, short for manual transmission plus, adds about 100 euros to the production cost of a traditional manual. Typically, that means the car buyer would have to pay 200 euros to 300 euros more for the technology.
Since it is electronically controlled, there are different levels of savings possible from the MTPlus, Schaeffler said. The most basic, which would involve putting the engine into idle when coasting in the transmission's highest gear, improves fuel economy by 3.1 percent under so-called real world driving conditions, Schaeffler says. Idling the engine when coasting in each gear increases the saving to 4.4 percent. The best results come when the system switches off the engine when coasting, which improves fuel usage by 8.2 percent, Zink said.
The challenge that Schaeffler faces is that the full benefits of MTPlus are not recognized under the current homologation rules in Europe. The New European Driving Cycle (NEDC), which has been in effect since 1970 and updated last in 1997, doesn’t factor in fuel economy and CO2 reductions from coasting. However, benefits from coasting are included in the latest draft of the worldwide harmonized light vehicles test procedures (WLTP), which are due to take effect in 2017. Schaeffler generated its fuel-savings estimates based on WLTP.