Schaeffler integrates cooling system control
The unit ensures rapid warm-up of the engine and transmission and cuts CO2 emissions
AE in Technology.
- Published in Technology.
Very cool: Two rotary valves control the powertrain's cooling circuit
Schaeffler has developed an innovative thermal management unit for Audi’s latest 1.8-litre turbocharged gasoline engine. The unit ensures rapid warm-up of the engine and transmission and cuts CO2 emissions by 2.5g/km.
The plastic module features an integrated water pump and uses two rotary valves to control coolant flow throughout the entire powertrain and HVAC system.
The Audi engine features an integrated exhaust manifold. This enables higher output and reduced consumption but cooling is challenging and means greater heat rejection to heat exchangers. The OEM approached Tier One Schaeffler for a solution. Development work began in 2007.
Michael Weiss, Schaeffler’s director of engine systems thermal management, said: “Electronically controlled thermostats are a cheap, known technology. But when engines become more complex, you might need two and you have more and more parts. Then it makes sense to integrate everything in one module.
“And when you have high power density, as in the Audi engine, reaction time is critical. We don’t have the 5-6s delay that a thermostat takes to open. Our module is connected to the throttle – as soon as you demand more power the valves open.”
The module features two rotary slide valves driven by an electric motor and gearbox, and a belt-driven plastic water pump. When valve one is closed, there’s standing water in the cylinder block; coolant only heats up in the cylinder head, ensuring rapid warm-up of engine and cabin. When it opens, coolant flows through the second valve. The valve has four ports: one for the engine, radiator and transmission oil cooler, and one to the engine oil cooler. This enables complete control of the entire cooling circuit.
The main development challenges were managing the tight positional tolerances between the water pump and the cylinder block and finding a motor able to cope with the high vibration loads. “We couldn’t use metal for the housing material because of the manufacturing complexity so we needed a plastic able to cope with the temperatures and vibrations. The tooling is extremely complex – 27 pistons on four layers to make the moulding,” said Weiss.
The module is made from PPS with 40% glass-fibre reinforcement and weighs around 1.2kg. Schaeffler has three other programmes for the technology in both gasoline and diesel applications. The Audi 1.8 develops 125kW/320Nm and launches in the A4 and A5.
