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TROY, MI – A small percentage of American drivers have become accustomed to stop/start systems by virtue of their placement on hybrid-electric vehicles, which now make up about 2.5% of U.S. light vehicles, according to Ward’s data.

But stop/start systems soon will get a major boost with the arrival of mild hybrids from several auto makers as they adjust their fleets to meet new fuel-economy mandates by 2016.

Some 10 million stop/start systems are expected to be on the road worldwide by 2015, according to some estimates.

Germany’s Schaeffler Group, a leading supplier of torque converters, has a new approach that simplifies integration of stop/start systems in conventional vehicles equipped with automatic transmissions, which are enormously popular in the U.S.

An automatic transmission makes it more difficult to incorporate stop/start because the torque converter between the engine and transmission is always engaged.

But Schaeffler has designed a permanently engaged starter that turns the torque converter into a useful weapon in reducing fuel consumption by allowing stop/start to function seamlessly – and cost-effectively – with automatic transmissions.

The system uses a 1-way clutch between the engine crankshaft and the torque converter’s starter ring gear that allows the mesh between the ring gear and the starter motor pinion to remain constant. Once the engine stops, restarts are immediate, Schaeffler says.

Eliminating slow response at restart and accommodating “change of mind” driving situations were chief objectives as the supplier developed the permanently engaged starter, says Jeff Hemphill, Schaeffler Group USA’s vice president-product development for LuK USA and region director-technical product development.