ABB Turbocharging introduces VCM

VCM offers engine builders a technology for attaining low NOx emissions combined with optimised fuel efficiency and increased power density on future four-stroke diesel and gas engines. It is based on INA’s UniAir system for automotive engines which allows variation of both valve timing and lift on four-stroke diesel and gas engines in the power range above 400kW. A prototype of the new VCM system is currently undergoing an extensive test programme and first results confirm the system’s potential for highly flexible valve timings on four-stroke engines.

VCM complements ABB Turbocharging’s Power2 two stage turbocharging system as enabling technologies of Miller cycles on four-stroke diesel and gas engines. On diesel engines, strong, variable Miller cycles hold the prospect of attaining the 80% reductions in NOx emissions specified by IMO Tier III limits for ECAs using only primary, on-engine measures. VCM allows inlet valve timings to be varied at lower engine loads to avoid increased emissions of smoke and particulates and higher thermal loading, as well as improving engine response, idling and starting.

VCM closely adapts engine performance to the operating profile of a given engine application. Variation in valve timing and lift is achieved by interposing a high pressure oil chamber into the engine valve train between the valve and its mechanical actuation system. A solenoid valve varies the filling of the chamber with engine lube oil pressurised by a camshaft actuated pump. This enables both the timing of the opening and closing of the valve to be varied as well as the distance the valve opens (valve lift). The pump also feeds a brake unit above the valve to limit forces when the valve contacts its seat.