Variable Valve Timing And Lift On Four Stroke Diesels

By Keith Henderson at November 10, 2011 06:02
Filed Under: Research & Development

Valve Control Management (VCM) is the name of a system under development by ABB Turbocharging, Switzerland and engine component specialist Schaeffler Technologies GmbH & Co. KG , Germany. It offers engine manufacturers a breakthrough technology for attaining low NOx emissions, optimal fuel efficiency and increased power density.
   
Aimed at  four stroke diesel and gas engines above 400 kW output, it’s an advanced variable valve train system, that allows variation of both valve timing and lift, reducing harmful exhaust emissions and allowing engine performance to be adapted to the operating profile of a given engine application. It is based on Schaeffler Technologies INA UniAir system for automotive engines and a prototype of the new VCM system is currently undergoing an extensive test program.


Caption: Prototypes of ABB Turbochargings VCM Valve Control Management system
are currently undergoing rigorous testing. First results confirm its potential for highly
flexible valve timings on four stroke engines.   
Image Credit: ABB Turbo Systems

VCM, together with an appropriate turbocharging system, allow Miller Cycles to be used on four stroke diesels and gas engines with the prospect  of attaining  IMO Tier III (Emission Control Area)
NOx emission levels. VCM further 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 operating principle (see diagram below)
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.


Captions: The VCM system varies valve timing and lift by interposing a high pressure oil chamber into the engine valve train.
Legend:
1.    Pressure accumulator
2.    Middle pressure chamber
3.    Oil supply
4.    Engine valves
5.    Pump unit
6.    High pressure chamber
7.    Solenoid valve
8.    Actuator/brake
9.     Camshaft
Image Credit: ABB Turbo Systems 

 

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