Third Generation Fuel Induction Systems for S.I. Engines

P M V SubbaraoProfessor

Mechanical Engineering Department

Artificial Injection of Right and Metered amount of Fuel

at Right Location…...

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 possibly fuel should be evaporated in the ports and mixed with the inlet air.

• The less possibly fuel as a liquid layer should be formed at the port and the cylinder walls

• The better solution is injection of fuel even in in the inlet port of gasoline (SI) vehicles using MPFI system.

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.

• Better volumetric efficiency

• More uniform fuel distribution

• More rapid response to changes in loading conditions

• More precise control of the equivalence ratio.

Overview of Electronic Fuel Injection System

Anatomy of EFI

Solenoid Magnet

Force on the Rod

Initial Magnetic Energy of the field

0

22

2 B

LRU i

Final Magnetic Energy of the field

00

22

2

m

f

BLRU

Change in energy

12 00

22

mB

LRU

L

U

dx

dU

dx

WForce

12 00

22

mBRF

Standard Gasoline Injectors

The route to Reach the Goal

• It is also important to know the time and condition with which the fuel should be sprayed in the port.

• The process of forming mixture in gasoline fuel injection vehicles is initiated with;

– the spray of fuel from injector and

– accompanied with the process of mass and momentum transmission.

– It is essential to recognize the structure and spray pattern.

The story of Mixture Formation & Fuel Spray

Gasoline Fuel Sprays in Port

Port Fuel Injection System

Control of Wall Wetting in Port Injection

Spray Formation

• Spray formation is explained as Breakup Mechanism, described as:

• Stretching of fuel ligament into sheets or streams.

• Appearance of ripples and protuberances.

• Formation of small ligaments or holes in sheets.

• Collapse of ligaments or holes in sheets.

• Further breakup due to vibration of droplets.

• Agglomeration or shedding from large drops.