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20 th Century Fuel Induction Systems for S.I. I.C. Engines

20 th Century Fuel Induction Systems for S.I. I.C. Engines. P M V Subbarao Professor Mechanical Engineering Department. Control the Size of Fuel Droplets and Trajectories …. Need for Fuel Injection in SI Engine.

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20 th Century Fuel Induction Systems for S.I. I.C. Engines

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  1. 20th Century Fuel Induction Systems for S.I. I.C. Engines P M V Subbarao Professor Mechanical Engineering Department Control the Size of Fuel Droplets and Trajectories …...

  2. Need for Fuel Injection in SI Engine • One of the main factors to achieve near complete combustion and better engine performance is the generation of a homogenous mixture of air and fuel in the cylinder. • The most of fuel should evaporate in the ports and mix with the inlet air.

  3. Artificial Induction of Fuel • The fuel-induction systems for current (high percentage) spark-ignition engines inject the fuel. • There are both mechanical and electronically controlled injection systems. • Helps in achieving better volumetric efficiency • More uniform fuel distribution • More rapid response to changes in loading conditions • More precise control of the equivalence ratio. • First step in this direction was Engines with Single pint Fuel Injection.

  4. Instability of Fluid Ligament in Ambient Air • Spray formation occurs in following stages: • Development of a jet, • Conversion of a jet into liquid sheets and ligaments, • Disintegration of ligaments into relatively large droplets (primary break-up) • Break-up of large droplets into smaller ones (secondary break-up).

  5. Kelvin-Helm Holtz Instability

  6. Wave Theory of Instability • WAVE theory is based on the temporal Kelvin-Helmholtz instability. • The maximum growth rate of disturbances (Ω )and the corresponding wavelength Λ decide the value of spray angle.

  7. Geometrical Features of Fuel Spray The maximal deviation of the emerging droplets from the axis, described by the angle .

  8. Length of Spray

  9. Frequency diagram for Size of droplets D is the droplet diameter and N is the normalized number distribution.

  10. Simplified Engineering fuel Evaporation model • The comprehensive fuel spray model predicts individual motions of liquid fuel droplets and evaporation of each droplet. • It also includes a more detailed treatment of in-cylinder evaporation. • In a simplified engineering model a representative diameter for the entire group is defined to compute evaporation rate. • Equivalent diameter of same number of uniformly sized droplets having same total surface area.

  11. Sauter Mean Diameter • Introducing the definition of SMD: where dnozzis the nozzle diameter, μf , μgare the fuel and gas dynamic viscosity, respectively, Re the Reynolds number and We the Weber number.

  12. Selection of Nozzle diameter & Flow Rate

  13. Cost Vs Fuel Economy

  14. Anatomy of EFI Solenoid Magnet

  15. Current SI Engines MPFI Engines High Specific Power Fuel economy better than carbureted  Quality governing, no throttling High HC emissions during transient operation Limited improvement at part load

  16. Need for Further Development • Formation a liquid fuel layers at the port and the cylinder walls should be minimized. • The better solution is injection of fuel even in in the inlet port of gasoline (SI) vehicles using MPFI system.

  17. Evolution of Fuel Inductions Systems : Third Generation

  18. Speed Density Electronic MPFI

  19. Speed Density Electronic MPFI • Speed-density system uses engine speed, manifold pressure and air temperature to calculate the engine air flow. • The electrically driven fuel pump delivers the fuel through a filter to the fuel line. • A pressure regulator maintains the pressure in the line at a fixed value (270 kPa). • Branch line leads to each injector, the excess fuel returns to the tank vial a second line. • Typical injection times for automobile applications range from 1.5 to 10 ms. • The appropriate coil excitation pulse duration or width is set by the electronic control unit (ECU). • In speed-density system the primary inputs to the ECU are the outputs from the manifold pressure sensor, the engine speed sensor and temperature sensors installed in intake manifold.

  20. For warm-engine operation, the mass of air per cylinder per cycle is: • The ECU forms the pulse which excites the injector solenoids proportional to estimated mass of air. • Addition temperature signals are used to find out cold start or hot engine cylinder conditions.

  21. Electronic MPFI with Air-flow Meter

  22. Two Wheeler Vehicles going the Eco-way : 2006

  23. Jul 31, 2006  : New motorbike technology bids goodbye to the carburettor • On June 26, Hero Honda, for the first time in India, launched the fuel injection (FI) technology in two-wheelers under the brand name Glamour FI. 

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