VCM for 4-Stroke DieselsModel: Valve Control Management
The VCM system varies valve timing and lift by interposing a high pressure oil chamber into the engine valve train. Under the designation VCM Valve Control Management, ABB Turbocharging and engine component specialist INA Schaeffler KG are developing an advanced variable valve train system. VCM offers engine builders a vital technology for attaining low NOx emissions combined with optimized fuel efficiency and increased power density on the four-stroke diesel and gas engines of the future. VCM is based on INA’s UniAir system for automotive engines. It allows variation of both valve timing and lift on four-stroke diesel and gas engines in the power range above 400 kW. A prototype of the new VCM system is currently undergoing an extensive test program. Following successful test bed trials, first results from “hot” on-engine trials confirm the system’s suitability for highly flexible valve timings on 4-stroke engines. VCM is an ideal 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 Emission Control Areas 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 is also a versatile and valuable tool for closely adapting 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 pressurized 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.