Atkinson cycle (Atkinson cycle Engines)
Post on 13-Apr-2017
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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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