Subsystems ICEngines

8/17/2019 Subsystems ICEngines

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Fuel systems for SI engines

Presented by :

Dr. Kamal Kishore Khatri


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Fuel systems for SI engines

• Carburetion:- In the SI engine a combustible fuel airmixture is prepared outside the engine cylinder. Theprocess of preparing this mixture is called carburetionand the device is called carburetor.

• Factors affecting carburetion:-

• The engine speed

• The vapourization characteristics of the fuel

•

The temperature of the incoming air and• The design of the carburetor, intake system and the

combustion chamber.


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• Air fuel mixtures

• Fuel and air are mixed to form three followingtypes of mixtures:-

• Chemically correct mixture

• Rich mixture and• Lean mixture

• The carburetor should provide an A/F ratio in

accordance with engine operating requirements.


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Mixture requirements at different

loads and speeds:-


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Automotive engine air-fuel mixture

requirement

• The carburetor must supply the A/F to satisfy

the following demands:-

• Idling (mixture must be enriched)

• Cruising (Mixture must be leaned)

•

High Power (mixture must be enriched)


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utomot ve eng ne a r- ue m xture

requirement cont.


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r nc p e o ar uret on: mp e

carburetor


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Solex Carburetor


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Conventional fuel supply system for SI

engines


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Petrol Injection:-

• Modern carburetors, have certain drawbacksas given below:-

• In multicylinder engines the mixture supplies

to various cylinders varies in quality &quantity.

• Carburetors do not give free flow passage for

the mixture, so decreases.• It has many wearing parts.

• Freezing may take place at low temperature.


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Petrol Injection cont.

• Surging may take place when it is tilted.

• In petrol engines, the fuel may be injectedduring the suction stroke in the inlet manifold

at low pressures. Two methods of injectionare :

• Continuous injection system

•Timed injection system

• The timing and duration of the fuel injection isdetermined by Electronic control unit (ECU).


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Multi Point fuel injection system

(MPFI)

Port Injection


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Fuel supply system for CI Engines


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Typical fuel feed system for CI Engine


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Injection Systems in CI Engines

b


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Distributor system

l lif


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Fuel lift pump

k f l


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Jerk pump type fuel Injection


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Thank you……..

Documents

Subsystems ICEngines