Jobs with a future Use the clutch and save energy

By developing an automated clutch actuation system, Jörg Buhl is helping to reduce CO₂ emissions by motor vehicles.

Starting, braking, stopping – commuter traffic usually turns into a daily grind that seriously irritates most drivers. But for Jörg Buhl, rush hour also has a positive side. While he’s sitting in his car with its six-speed manual transmission, he often finds that his journey through the slow-moving traffic provides him with inspiration for his work at ZF. Because there, optimizing clutch actuation is one of the many projects Buhl and his team are working on. Ideally, clutches would be actuated by an automated driveline, like those already used for automatic transmissions and automated manual gearboxes. But to make clutch actuation easier or even unnecessary for drivers of vehicles with manual transmissions – in traffic jams, at least – Buhl and his team are developing the clutch-by-wire system. This comprises a manual transmission with an automated clutch actuation system. The automation makes it possible to actuate the clutch pedal without mechanical linkages – the decision to engage or disengage the clutch is communicated by wire to an actuator. This actuator system enables drivers in stop-and-go traffic to shift from first to second gear without touching the clutch. “But the major advantage of the clutch-by-wire system is the way it reduces fuel consumption,” says ZF’s Head of Actuator System Design.

Revolutionary clutch-by-wire concept enhances efficiency

Clutch-by-wire cuts fuel consumption by enabling vehicles fitted with manual transmissions to coast.

The 47-year-old engineer, who studied Production Engineering, has been working on the clutch-by-wire concept for a long time. The technology has been in existence since 1993. “Back then, it didn’t get any market traction,” explains Buhl. Only a couple of years ago did automakers start to show more interest in the technology, because fuel consumption and emissions have now become significant issues. This is where the “coasting function” – previously the exclusive preserve of vehicles with automated drivelines – comes into play. In driving conditions where a vehicle’s combustion engine is not required to deliver any power, for example while rolling slowly along in traffic or on slight downhill inclines, a clutch-by-wire system automatically disengages the driveline, reducing fuel consumption by up to 10 percent. Then, once the vehicle’s speed falls below a certain level, the clutch automatically re-engages and the engine can once again deliver its power to the wheels. What’s more, clutch-by-wire systems can also include other options, such as a stall prevention function or driver-assist functions for relieving stress in stop-start traffic.

Video: Jörg Buhl comments on his work in actuator development, where he is also further developing clutch-by-wire technology.

Mechanical systems controlled by sophisticated software

In terms of technology, the clutch-by-wire system developed by ZF is, of course, much more advanced than first-generation systems. Now sophisticated software guides the mechanical components. “Modern computers are significantly faster,” says Buhl, “meaning we can incorporate more features.” Then there’s all the additional experience ZF has acquired. “We’ve been working on the development of software and actuator systems for 20 years, so we can offer an optimized system architecture,” explains Buhl.

Buhl himself started his career at ZF in Schweinfurt, back in 2001. His ten-member team works closely with colleagues in software development – they’re always getting together for brainstorming sessions: “Any and every idea is welcome – we let our imaginations run wild!” They like to celebrate the joint progress they’re making: “clutch-by-wire systems can reduce fuel consumption and emissions by an enormous margin,” says Buhl. And for a responsible family man, who hopes to leave a cleaner world to his three children, that’s an important consideration.

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