prao presentation with effects

8/2/2019 PRAO Presentation With Effects

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S


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Major Objectives of the GDI engine:

S Ultra-low fuel consumption that betters that of even

diesel engines

S Superior power to conventional MPI engines

S Sophisticated high-pressure injectors capable of

producing very fine, well-defined fuel sprays,coupled with advanced charge air controltechniques, now make stable GDI combustionfeasible.


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WHY NOT CARBURETTOR?

S Carburettor has following disadvantages:

S Vapour lock

S Perfect air/fuel mixture cannot be obtained

S Lack of throttle response

S Low volumetric efficiency

S Icing problem in aircraft engines

S Mechanical device

S Compromises on emission


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Major characteristics of the GDIengine:

S Lower fuel consumption and higher output

S Optimal fuel spray for two-combustion mode

SUltra-lean Combustion Mode

S Superior Output Mode


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In-cylinder Airflow

S The GDI engine has upright straight intake ports ratherthan horizontal intake ports used in conventional engines.

S The upright straight intake ports efficiently direct theairflow down at the curved-top piston, which redirects theairflow into a strong reverse tumble for optimal fuelinjection


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Fuel Spray:

S Newly developed high-pressure swirl injectors provide theideal spray pattern to match each engine operationalmodes.

S And at the same time by applying highly swirling motionto the entire fuel spray, they enable sufficient fuelatomization that is mandatory for the GDI even with arelatively low fuel pressure of 50kg/cm2


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Realization of lower fuelconsumption:

S Basic Concept:

S Extremely low fuel consumption is achieved becauseideal stratification enables fuel injected late in thecompression stroke to maintain an ultra-lean air-fuelmixture.

S Extremely stable combustion of ultra-lean mixture with an

air-fuel ratio of 40 (55, EGR included) is achieved asshown below


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Vehicle Fuel Consumption:

S Fuel Consumption during Idling:The GDI engine maintains stable combustion even at lowidle speeds. Moreover, it offers greater flexibility in setting

the idle speed.Compared to conventional engines, its fuel consumptionduring idling is 40% less.


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Fuel Consumption during CruisingDrive:

At 40km/h, for example, the GDI engine uses 35% less fuelthan a comparably sized conventional engine


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Fuel Consumption in City Driving:

S In Japanese 10E15 mode tests (representative of typicalJapanese urban driving ), the GDI engine used 35% lessfuel than comparably sized conventional gasolineengines. Moreover, these results indicate that the GDIengine uses less fuel than even diesel engines.


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Emission Control:

S Previous efforts to burn a lean air-fuel mixture haveresulted in difficulty to control NOx emission.

S However, in the case of GDI engine, 97% NOx reductionis achievedby utilizing high-rate EGR (Exhaust GasRatio) such as 30% that is allowed by the stablecombustion unique to the GDI as well as a use of a newlydeveloped lean-NOx catalyst.

S Newly Developed Lean NOx Catalyst (HC selectivedeoxidization type)


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Emission Control:


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Improved Volumetric Efficiency:

S Compared to conventional engines, the Mitsubishi GDIengine provides better volumetric efficiency.

S The upright straight intake ports enable smoother airintake.

S And the vaporization of fuel, which occurs in the cylinderat a late stage of the compression stroke, cools the air forbetter volumetric efficiency.


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Increased Compression Ratio

S The cooling of air inside the cylinder by the vaporizationof fuel has another benefit, to minimize engine knocking.

SThis allows a high compression ratio of 12, and thusimproved combustion efficiency


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Engine performance :

S Compared toconventional MPI

engines of acomparable size,the GDI engineprovidesapproximately 10%

greater output andtorque at allspeeds.


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Vehicle Acceleration :

S In high-output mode, the GDI engine providesoutstanding acceleration.The following chart compares the performance of the GDI

engine with a conventional MPI engine.


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The difference between new GDI andcurrent MPI

S Extremely precise control of fuel supply to achieve fuelefficiency that exceeds that of diesel engines by enablingcombustion of an ultra-lean mixture supply.

S Very efficient intake and relatively high compression ratiounique to the GDI engine deliver both high performanceand response that surpasses those of conventional MPIengines.


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Improved fuel conversion economy (upto 25% potential improvement, resulting

from:

S Less pumping loss (unthrottled, stratified mode);

S Higher compression ratio (charge cooling withinjection during induction

S Lower octane requirement (charge cooling withinjection during induction);

S Increased volumetric efficiency (charge cooling withinjection during induction);

S Improved transient response.


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Continued

S Less acceleration-enrichment required (no manifoldfilm)

SMore precise air-fuel ratio control

S More rapid starting;

S Less cold-start over-fuelling required.

S Extended EGR tolerance limit (to minimize the useof throttling)

S Selective emissions advantages

S Reduced CO2 emissions


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Major Specifications


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Technical features :

S Upright straight intake ports for optimal airflow control in

the cylinder

S Curved-top pistons for better combustion

S High pressure fuel pump to feed pressurized fuel into the

injectors

S High-pressure swirl injectors for optimum air-fuel mixture


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Conclusion

S The world need to protect the environment , and the morestringent emission regulations that evolved year after year havechallenged vehicle manufacturers among other things to

produce vehicles that not only conform to regulations but alsoconsistently exceed them.

S The GDI engine does this and has technology (adaptivelearning) to ensure that as the engine ages it will continue toconform by adjusting itself as the engine components andemission devises wear .

S Gasoline direct injection (GDI) engine technology has receivedconsiderable attention over the last few years as a way tosignificantly improve fuel efficiency without making a major shiftaway from conventional internal combustion technology. Inmany respects, GDI technology represents a further step in the

natural evolution of gasoline engine fuelling systems.


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References

S Internal Combustion Engines By: Anand V Domkundwar.

S Internal Combustion Engines By: Mathur & Sharma.

S www.howstuffworks.com

S www.mitsubishi-np.in

S www.autoworld.com

S www.visionengineer.com
http://www.howstuffworks.com/http://www.mitsubishi-np.in/http://www.autoworld.com/http://www.visionengineer.com/http://www.visionengineer.com/http://www.autoworld.com/http://www.mitsubishi-np.in/http://www.mitsubishi-np.in/http://www.mitsubishi-np.in/http://www.howstuffworks.com/


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