UNIT 2 AUTOMOTIVE ENGINE
3 . Basic Engine Systems
A spark-ignition engine requires four basic systems to run. Diesel engines require three of these systems.
There are two types of piston engines-spark ignition (SI) and compression ignition (CI) .
Spark-ignition engines use an electric ignition system with spark plugs. Electric sparks at the spark plugs ignite, or set fire, the fuel in the engine cylinders.
UNIT 2 AUTOMOTIVE ENGINE
3 . 3 Lubricating system
The lubricating system has an oil pan at the bottom of the engine which holds several quarts [liters] of oil.
This is called a mid-engine arrangement. Other cars have been built with the engine mounted at
the rear, in back of rear seat. The Volkswagen“ beetle” is an example of rear.
A movable piston in the cylinder is forced down by the expanding gases of combustion.
UNIT 2 AUTOMOTIVE ENGINE
In the rear-wheel-drive arrangement, the engine sits longitudinally. Its long dimension is from front to back.
UNIT 2 AUTOMOTIVE ENGINE
Some cars have the engine mounted in back of the front seat.
An oil pump, driven by the engine, sends oil from this reservoir through the engine.
After circulating through the engine, the oil drops back down into the oil pan.
• Each cylinder is repeatedly filled with the mixture. Then, the mixture is ignited and burned, producing high pressure.
• The high pressure makes the pistons move (or rotors spin) .
UNIT 2 AUTOMOTIVE ENGINE
2 . Engine Types
Various kinds of engines are used in automotive vehicles. The two major types are:
(a) The piston engine in which pistons move up and down, or reciprocate, in the engine cylinders. This is the engine used in all cars today, except for some models of Mazda.
(b) The Wankel rotary engine in which rotors rotate, or spin. The Mazda Motor Corporation of Japan is the major manufacturer of this engine.
UNIT 2 AUTOMOTIVE ENGINE
• This turns shafts that rotate the wheels, causing the vehicle to move.
UNIT 2 AUTOMOTIVE ENGINE
3 . 2 Ignition system
Every time the fuel system delivers air / fuel mixture to a cylinder, the ignition system follows up by delivering an electric spark.
UNIT 2 AUTOMOTIVE ENGINE
3 . 1 Fuel system
• The fuel system supplies gasoline or diesel fuel to the engine.
• This fuel is mixed with air to make a combustible mixture (a mixture that will burn) .
1. Purpose and Locations of Enginபைடு நூலகம்s
2. Engine Types 3. Basic Engine Systems
4. Enemy Conversion 5. Four-Stroke-Cycle Gasoline Engine
Operation
UNIT 2 AUTOMOTIVE ENGINE
This ignites the mixture which creates the high pressure that moves the pistons and turns the car wheels.
The ignition system takes the low voltage of the battery and builds it up to a very high voltage: as high as 47, 000 volts in some systems.
Because the engine burns fuel inside, or internally, the engine is known as an internal combustion engine ( ICE)
UNIT 2 AUTOMOTIVE ENGINE
Most automotive engines are located at the front of the vehicle.
The compression-ignition engine uses the heat of compression to ignite the fuel. When air is compressed, it gets very hot. The diesel fuel is sprayed into this very hot air and is ignited by the heat.
The exhaust system reduces the noise of the burned gases leaving the engine cylinders and carries these exhaust gases safely away from the people in the car.
The internal combustion engine is a device used to convert the chemical energy of the fuel (gasoline or diesel fuel) into heat energy, and then to convert this heat energy into usable mechanical energy.
1 . Purpose and Locations of Engines
The purpose of an automotive engine is to supply the power needed to move the vehicle.
The engine produces this power by burning fuel inside it.
UNIT 2 AUTOMOTIVE ENGINE
3 . 5 Other engine systems
An engine will run with the four basic systems described above—fuel, ignition, lubricating, and cooling.
➢ After the hot oil drops down into the oil pan, the oil gives up some of this heat to the air passing under the oil pan.
➢ The rest of the heat is removed by the cooling system.
A battery provides the electric power to operate the starting motor and the ignition system during cranking.
UNIT 2 AUTOMOTIVE ENGINE
4 . Energy Conversion
The oil pump continues to circulate the oil as long as the engine is running.