Schaeffler sees e-clutch as key to making manual gearboxes more frugal

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.

Clutch pedal removal

Schaeffler is also working to eliminate the clutch pedal in next-generation manuals with a solution that is calls Electronic Clutch Management (ECM), which adds sensors to the gear-lever position and gearbox. "ECM provides some of the functions and the comfort of an automatic transmission at less than half the price," Zink said, adding that he sees great potential for the technology in markets such as India and Brazil, where traditional automatics remain far too expensive for the mass market.

Fitting a traditional manual with ECM adds from 150 euros to 200 euros in production cost. By comparison, the simplest automatic, an automated manual transmission, costs automakers an estimated 300 euros to 400 euros while car buyer typically pays 700 euros to 900 euros for an AMT. A dual-clutch transmission costs automakers about 750 euros and has a starting retail price in Europe of 1,500 euros. Pedal-less clutches were offered about 20 years ago on models such as the Mercedes-Benz E class, Renault Twingo Easy and Volkswagen Golf Ecomatic, but the added convenience didn’t bring any fuel or CO2 savings because the engine was neither idled or turned off.