Atkinson cycle (Atkinson cycle Engines)

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  • BRIEF HISTORY OF ATKINSON CYCLE

    Invented in 1882 by

    British engineer James

    Atkinson

    Patents for the existing Otto

    cycle engine presented a need

    for a new crankshaft design

    The Atkinson cycle is designed to

    provide efficiency at the expense

    of power density, and is used in

    some modern hybrid electric

    applications. Also called the

    Barta engine in (1884).

  • ATKINSON-CYCLE ENGINES

    Operates on a four-stroke cycle

    Intake

    Compression

    Combustion

    exhaust

    Its Combustion stroke is longer than compression

    stroke allowing more expansion of combustion

    gases.

    These are all strokes complete in one revolution

    of crankshaft.

  • THERMODYNAMICS OF ATKINSON-CYCLE

    ENGINE

    The ideal Atkinson cycle consists of following

    operations:

    1-2 Isentropic or reversible adiabatic compression

    2-3 Isochoric heat addition (Qin)

    3-4 Isentropic expansion

    4-1 Isobaric heat rej (Qout)

  • ATKINSON ENGINE V/S OTTO ENGINE

    Atkinson and Otto engines are very similar.

    Atkinson uses slightly different timing for valve

    opening and closing events

    In particular, the intake valve stays open as the

    compression stroke begins.

    This difference results in increased fuel

    efficiency, but decreased peak power

  • ATKINSON ENGINE V/S OTTO ENGINE

    From a mechanical standpoint, the only thing

    that needs to change between an Otto cycle and

    an Atkinson cycle is the camshaft(s)

    The power of the engine can be supplemented by

    an electric motor during times when more power

    is needed.

  • ATKINSON CYCLE V/S OTTO CYCLE

    the Atkinson cycle has an efficiency advantage

    over the Otto cycle.

    Atkinson cycle has a larger expansion ratio than

    compression ratio.

    The power output would be lower in Atkinson

    cycle engine as compared to a similar sized Otto

    cycle en

  • COMPARISON OF OTTO AND ATKINSON CYCLES

  • ADVANTAGE AND DISADVANTAGE OF ATKINSON

    CYCLE ENGINE

    The main advantage of the Atkinson cycle is that

    it is much more efficient than the Otto cycle.

    But the Biggest disadvantage is reduction in

    power density (power/unit volume) arising from

    the reduction in air intake

    However Atkinson cycle engine can be supplemented with electric motor to provide more power if needed

    Electric motors can be used in combination or independent of Atkinson cycle engines to provide the desired power output most efficiently

  • USES OF ATKINSON CYCLE ENGINE

    Today Atkinson cycle engine used in many cars

    such as

    Toyota Prius hybrid electric

    Ford Escape/Mercury Mariner/Mazda Tribute

    hybrid electric

    Toyota Camry hybrid electric

    Honda Accord Plug-in Hybrid

    Lexus CT 200h

  • ATKINSON-CYCLE ENGINES TODAY

  • TODAY ATKINSON CYCLE ENGINE

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