Fuel supply system in IC engine in automobile engineering

About fuel supply system

1. FUEL SUPPLY SYSTEM IN IC ENGINES

2. Fuel supply system The basic fuel supply system in a petrol engine consists of a  fuel tank , fuel lines, fuel pump, fuel filters, air cleaner, carburetor and inlet manifold . The system responsible for preparing the correct mixture of air and fuel, and directing this mixture to each of the cylinders is known as "Induction System. Types of fuel supply systems: Gravity system Pressure system Vacuum system Pump system Fuel injection system

3. Fuel–tank It is made of galvanized MS sheet and is fast and under the chassis with straps nuts and bolts with rubber packing in between. The tank usually coated with lead tin alloy inside the tank to protect against corrosion. Petrol connection is taken at the bottom sometimes a fine wire gauge strainer is also fitted in it so that petrol leaving the tank is free from coarse suspended impurities.

4. Fuel pumps The function of the fuel pump is to pump fuel from the tank and feed it to the carburetor. These pumps are designed to pump a sufficient quantity of fuel at all working conditions so that the pipeline always remains filled up with fuel at all working conditions failing which these are chances of vapor lock usually called airlock in the pipeline. Two main types of pumps generally used are A C Mechanical pump S U Electrical pump

5. Carburettors Carburetor is the device that mixes petrol and air in correct proportions and supplies to the combustion chamber in right quantity. • A Carburetor atomizes, vaporizes and mixes the petrol in correct proportions with air as required by the engine and supplies the right quantity of the mixture to the engine.

6. Functions of a carburetor   The main functions of a carburetor are The main function of carburetors to mix air and gasoline and provides a high combustion mixture. It controls the engine speed. It also regulates the air-fuel ratio. Increase or decrease the amount of mixture according to the engine speed and load changing. To keep certain head of fuel in the float chamber all the time. Vaporize the fuel and mix to air to a homogeneous air-fuel mixture. To supply the correct amount of air-fuel mixture at the correct strength under all conditions of load and speed of the engine.

7. Carburetors are also classified as Up-drought Horizontal Down-drought Carburetors.

8. Zenith Carburettor

9. Solex Carburettor

10. MPFI Injection system Multi-Point Fuel Injection System aka the MPFI system was originally only developed for the airplane engines. Nowadays, it is widely used in light commercial vehicles. MPFI system is the most advanced gasoline injection system currently in the automobile industry.

11. Air cleaners The air cleaner not only cleans the air by removing the dust and dirt particles but also muffles the noise resulting from the intake of air through the carburettor In addition, the air cleaner acts as a flame arrester in case the engine backfires through the carburettor . Backfiring occurs at certain times due to the ignition of the air-fuel mixture in the cylinder before the intake valve closes. When this happens, there is a momentary flask-back through the carburettor . The air cleaner prevents this flame from spreading through the carburettor and possibly igniting the petrol fumes outside the engine. Types of Air Cleaners in Engine Oil bath type air cleaner or wet type air cleaner Dry-type air cleaner

12. Wet type air cleaner

13. Super charging The process of supplying the air fuel mixture at a higher pressure is called super charging Super charging increases the pressure of the air fuel mixture which is higher than the atmospheric pressure There are three types of super charging Centrifugal type Roots type Vane type

14. Centrifugal Type Supercharger A centrifugal-type supercharger is relatively light and compact and produces a continuous flow of air under pressure. The mixture of fuel and air enters the rotating impeller in a direction parallel to the shaft. The impeller (rotor) rotates in a close-fitting casing at the speed of 10,000 to 15,000 rpm. Thus, the impeller imparts high velocity to the mixture due to centrifugal action.

15. Roots Type Supercharger The roots type supercharger consists of two rotors with two, three, or more lobes on each rotor. The shafts are connected by gearing and rotate at the same speed. The rotors are made of such dimensions that they rotate in the housing with a slight clearance, and also have a clearance between them Air enters the space between the rotor lobes at the inlet and is carried around the rotors to the discharge port. There is no compression in this process.

16. Vane Type Supercharger It is also known as the centric vane-type supercharger. It consists of an eccentric drum on which a number of vanes are mounted in such a manner that they can slide in the slots provided for them. Each slot carries one vane The vanes are pushed out by the springs which are at the inner side of the vane. The outer edge of the vanes remains in contact with the inner surface of the supercharger body. The drum is rotated by the power shaft. The vanes are carried around. Since the vanes are free for radial movement, the outer edges of the vanes remain in contact with the inner surface of the body.

17. Fuel supply system in CI engines The fuel supply system of a diesel engine can be called as the heart of the engine, since the engine performance directly depends upon the proper functioning of this system—which must supply, meter, inject and atomize the fuel. Fuel injection systems are manufactured with great accuracy, hence they are costlier. Fuel will flow either because of gravity or fuel feed pump, which is provided to supply fuel through the filter to the injection pump. Which pumps the fuel to the injectors which are provided in the cylinder heads.

18. Fuel injection system The function of fuel injection system is to inject proper quantity of fuel into the engine cylinders at the correct tome and at predetermined rate. These systems may be classified into two systems. Solid injection system Air injection system In the solid injection system only the liquid fuel is injected, whereas in the air injection system liquid fuel is injected along with compressed air. The air injection system is less reliable, less efficient and requires an air compressor for supplying air at 7 Mpa or higher pressure. Due to which reasons it become obsolete.

19. Fuel injection system Two types of solid injection systems are in use 1. common rail fuel injection system 2. Individual pump fuel injection system Most modern engine fuel systems use an advanced technology known as CRDI or Common Rail Direct Injection. Besides, both petrol and diesel engines use a common ‘fuel rail,’ which supplies the fuel to injectors. In individual pump injection system fuel will flow from the storage tank to filters to low pressure pumps. This low pressure pump pumps the fuel to 4 separate metering and pressure pumps. These separate metering and pressure pumps will pump the fuel to individual injectors which are provided in the cylinder heads. These are used in large slow speed engines.

20. Individual pump fuel injection system

21. Fuel injection pump Fuel injection pump (FIP) is the device used in the diesel engine for pumping the fuel to the injectors and it also helps to distribute and meter the supply of fuel to all injectors. The other function of the FIP is to pump the correct quantity of fuel at the right time (Just before the piston reaches TDC during compression stroke) and within a specified duration. In ECU-controlled vehicles, the fuel injection pump is only used to pressurize the fuel line as the distribution of fuel is controlled with the help of electric injectors and ECU units. The fuel injection pumps are driven with the help of a crankshaft or by the camshaft. different types of fuel injection pumps used in diesel engines:- 1. Inline fuel injection pump or jerk type fuel injection pump 2. Distributor fuel injection pump.

22. Jerk type fuel injection pump

23. Distributor fuel injection pump

24. Fuel Filters It is an important part of this system as it protects the engine from harmful waste and is also known as a fuel strainer. As the name suggests, it is a fixed filter in the fuel line that detects dirt and rust particles and separates them from the fuel. It is usually built into a cartridge containing filter paper. The diesel engine life is mostly dependent on the quality of fuel and lubrication of internal parts. Unfiltered fuel may contain several kinds of contamination. These substances must be removed before the fuel enters the system.

25. Primary and secondary fuel filter

26. Fuel feed pump The function of feed pump is to deliver the fuel from the fuel tank to fuel injection pump through the fuel filter. The feed pump is attached to the injection pump and driven by its camshaft. Where is fuel feed pump mounted in diesel engine? Specific designs vary, but in the most common configuration, these pumps are mounted on the side of the injection pump and driven by the camshaft, either directly or via a pushrod.

27. It consist of a nozzle valve(NV) fitted in the nozzle body (NB). The nozzle valve is held on its seat by a spring ‘S’ which exerts pressure through spindle E. ‘AS’ is the adjusting screw by which nozzle valve lift can be adjusted. Usually the nozzle valve is set to lift at 135 to 175 bars pressure. FP is the feeling pin which indicates whether valve is working properly or not The fuel under pressure from the fuel pump enters the injector through the passages B and C and lifts the nozzle valve. The fuel travels down nozzle N and injected into the engine cylinder in the form of fine spray. Then the pressure of the oil falls, the nozzle valve occupies its seat under the spring force and fuel supply is cut off. Any leakage of fuel accumulated above the valve is led to the fuel tank through passage A. The leakage occurs when the nozzle valve is worn out.