Innovative valve train saves 20% fuel
A new, electrohydraulic valve train dispenses with camshafts and oil in the cylinder head. It has been in test operation with natural gas since October 2018 and, according to the developers, has so far run smoothly.10 Sep. 2019 David Schahinian
An engine’s valve train controls the supply of fresh air and discharge of exhaust gases; the valves are opened and closed by its camshafts. The new concept from the Swiss Federal Laboratories for Materials Testing and Research (Empa) does things very differently: The valves are actuated hydraulically and individually controlled electrically via a solenoid coil. The researchers explain that this means that less energy is required over a wide operating range than with conventional systems. In addition, a water-glycol mixture is used as the hydraulic fluid instead of oil, because its rigidity makes it very suitable for fast-switching hydraulic systems. Another advantage of the valve train, according to Empa, is that it can be used flexibly with new and renewable fuels. The ‘FlexWork’ control system is currently being tested in a passenger car engine powered by natural gas. It has already “survived many millions of cycles in fired engine operation flawlessly”.
Meanwhile, Drive Technology Holland has launched a toothed belt drive that dispenses with gears. The system consists of two adjustable conical pulleys that center themselves, reports the Eindhoven-based company.
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