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  • Technical information

    ABB TurbochargingVCM Valve Control Management the heart rate reactor

  • 2

    VCM Valve Control Management

    The ability to control valve timing and valve lift on combustionengines brings a range of benefits in terms of engine operatingperformance, emissions and fuel consumption. Followingwidespread use in the automotive sector, the technology is now arousing interest in the large engine sector served byABB Turbocharging. It is seen as an enabling technology for a number of measures on 4-stroke diesel and gas engineswhich target lower emissions, reduced fuel consumption,increased power density and enhanced transient behavior.

    Proven technology Anticipating this demand, in 2009 ABB Turbocharging agreeda collaboration with one of the leading exponents of variablevalve timing in the automotive sector, German engine compo-nent specialist Schaeffler Technologies GmbH & Co. KG. Theagreement centers on the development of the UniAir /MultiAir

    variable valve train system for automotive engines to suitapplications on large 4-stroke diesel and gas engines withpower outputs above 400 kW.

    VCM The result of the cooperation is VCMV = Valve C = Control of timing and/or liftM = Management in steady or transient mode

    Like UniAir /MultiAir , it uses electro-hydraulic technology to achieve progressive variation of timing / lift of the inlet orexhaust valve.

    VCM offers the following features: Stepless: Unlike purely mechanical systems, e.g. those whichvary the positions of the fulcrums of cam followers to changethe timing of valve actuation and valve stroke, VCM offers a wider range of fully proportional control of valve timing / lift.Compact and add-on: The VCM system combines all ele-ments in a single module which can be readily installed on 4-stroke engines. The majority of VCM equipment is locatedunder the valve cover and by using the engine lube oil as itshydraulic fluid and a simple solenoid valve as its control organ,only two control / supply connections are required.The systemalso requires no major changes to engine architecture and the modules are readily fitted during the assembly process atthe engine builders works.

    VCM module locates above the normal engine valves.

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    VCM applications

    V for Versatile The stepless variation in valve timing and lift achievable withVCM represents a versatile tool for: Varying Miller Cycles on coming generations of low

    emissions diesel and gas engines Closely adapting engine performance to the operating

    profile of a given engine application, e.g. switching fromemissions to fuel optimized modes

    Potential for realizing internal exhaust gas recirculation on 4-stroke engines

    Enabling MillerIndeed, ABB Turbocharging sees VCMs foremost applicationas one of the major enabling technologies for engine buildersseeking to exploit strong Miller Cycles as a route to far loweremissions of NOx. The Miler Cycle is an ingenious way ofcooling the cylinder charge of diesel engines to eliminate thecombustion chamber temperature peaks responsible for over90 % of NOx formation. On gas engines the technique can beused to substantially increase power density.

    Miller Cycle principle On 4-stroke engines, substantial cooling of the engine intakeair is achieved by shortening the opening period of the inletvalve and so reducing the time during which the cylindercharge can enter the cylinder on the induction stroke. Theearlier end of induction promotes expansion, and hence cooling in the cylinder charge. However, the short valve timingsof the strong Miller Cycles needed to achieve the kinds of NOxreductions prescribed in planned emissions legislation arematched to a diesel or gas engine operating at its MaximumContinuous Rating or MCR. At lower loads longer valveopening periods are needed to avoid emissions of smoke andparticulate matter and poor engine response to load changesdue to intake air deficiency.

    VCM solution With its capability to vary valve timing, VCM provides enginebuilders with a powerful tool for adapting the strength of MillerCycles across the complete operating load and speed rangesof 4-stroke diesel and gas engines.

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    Shifting the curve fuel consumption and NOx reduction potentialusing two stage turbocharging to achieve strong Miller Cycles on further developed diesel engines.

    Early Miller Cycle and standard induction at the moment of inlet valve closure.

    inlet

    Standardinlet valveclosurenear BDC

    BDC

    TDC

    Inductionstroke

    Millerinlet valveclosurebefore BDC

    exhaust inlet exhaust

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    How VCM works

    VCM achieves stepless variation in valve timing by interposinga high pressure oil chamber into the engine valve train betweenthe valve and its mechanical actuation system. A solenoidvalve varies the filling of the chamber with engine lube oilpressurized by a camshaft-actuated pump. This enables boththe timing of the opening and closing of the valve to be variedas well as the distance the valve opens (valve lift). The pumpalso feeds a brake unit to limit forces when the valve contactsits seat.

    The VCM system variesvalve timing and lift by introducing a highpressure oil chamberinto the engine valvetrain.

    Pressure accumulatorMiddle pressure chamberOil supplyEngine valvesPump unitHigh pressure chamberSolenoid valveActuator /brakeCamshaft

    Camshaft angle

    Valv

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    t

    Camshaft angle

    Valv

    e lif

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    Camshaft angle

    Valv

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    Camshaft angle

    Valv

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    Late opening/early closure, limited lift Double opening

    Early closureFull lift

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    ABB TurbochargingA unique partner for advanced engine components.

    VCM Valve Control Management is a major element in ABB Turbochargings growing portfolio of products and services for engine builders and engine end users. Their common aimis to optimize the performance, economy, reliability, availability,life cycle costs and not least the exhaust emissions of dieseland gas engines.

    Proactive solutions For ABB Turbocharging this means proactively addressing theneeds and concerns of both engine builders and engine end users to devise solutions which are both effective andeconomic.

    ComplementaryVCM is one of two complementary building blocks ABB Turbocharging is offering to address the current major con-cerns of engine builders: Compliance with the strict limitations on emissions of oxides

    of nitrogen (NOx) from engines on land and at sea due to beimplemented in the middle of the present decade

    Increasing fuel efficiency in the face of the steady rise in theprice of fossil fuels and international agreements governingemissions of the greenhouse gas carbon dioxide (CO2)

    VCM and Power2 interactionMeshing perfectly with VCM is ABB Turbochargings Power2two stage turbocharging system. These complementary tech-nologies represent essential enablers of Variable Miller Cycleson large 4-stroke engines.

    On the one hand Power2 provides the high turbochargingpressure ratios needed for the very strong Miller Cyclesrequired to realize high NOx reduction percentages.

    On the other hand VCM allows engine gas exchange to beoptimized over a full range of engine operating conditions,hence allowing the effect of the Miller Cycle to be varied.

    Via its effect on engine gas exchange VCM is also an effectivemethod of varying the output of the two turbochargers in thePower2 system.

    Unique development partner With these technologies, ABB Turbocharging is a unique partner for two of the major on-engine systems required by diesel and gas engine builders to prepare their products for the new era of strict global emissions limitations.

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    Emissions complianceIMO Tier III and EPA Tier 4 are typical of the emissions legislation to be enacted in the middle of the present decadeaffecting engines with outputs over 500 kW.

    IMO Tier IIIThe third stage of marine engine emissions legislation issuedby the International Maritime Organisation and due in 2016builds on IMO Tier II, due in 2011. In 2016 the generally appli-cable 20 % reduction in NOx emissions vis--vis IMO Tier I(introduced 2000) continues to govern NOx emissions on thehigh seas. However, IMO Tier III demands an 80 % reductionin NOx emissions from vessels operating in Emissions ControlAreas, or ECAs.

    ECAs are, broadly, coastal waters close to areas of populationor environmentally sensitive locations. ECAs already designatedare the complete East and West Coasts of the USA andCanada, straits like the English Channel, landlocked seas like the Baltic and numerous port approaches.

    NO

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    500 1000 1500 2000 2500 [1/min]

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    Tier II, from 1 January 2011

    Tier III, from 1 January 2016

    [g /kWh]

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    IMO NOx curves

    EPA Tier 4 standardsEmissions standards issued by the USAs Environmental Pro-tection Agency cover NOx emissions from water borne, mobileand stationary engines of all sizes used in a wide range ofapplications Up to 2015, the EPA Tier 4 standard requiresNOx emissions to be reduced by around 90 % compared tothe 2008 Tier 1 baseline.

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