One of the main advantages of Continuous variable transmissions (CVT) is to reduce fuel consumption and emissions by running the engine at its maximum efficiency. This often involves overdrive ratios to keep engine speed low under cruising conditions thus compromising vehicle longitudinal response during tip-ins; in fact an additional torque is required to accelerate the engine to an operating point where higher power is available. This raises some driveability compromises especially for turbocharged diesel engines on which the transient torque response is slow due to turbo lag. This paper presents an AMESim model of a 3.0L V6 turbocharged diesel engine paired with a CVT. An air accumulator is implemented to improve the transient torque response by injecting air into the intake manifold during tip-in manoeuvres at low engine speed. A number of accumulator initial conditions and controller calibrations are investigated for a given transient manoeuvre. The system has shown a significant improvement in the transient response for part and full load tip-ins. The subsequently enhanced torque controllability permits design trade-offs for reduction of the turbocharger lag. The benefits of adequate control strategies were demonstrated, resulting in faster vehicle acceleration response and potentially better driveability.


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    Title :

    A turbocharged diesel engine with intake air accumulator to improve torque transients in a CVT powertrain


    Contributors:
    Rohrbacher, Y. (author) / Bonnet, B. (author) / Vaughan, N.D. (author)


    Publication date :

    2006


    Size :

    14 Seiten, 8 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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