BASIC MECHANICAL BASIC MECHANICAL ENGINEERINGENGINEERING

INTERNAL INTERNAL COMBUSTION COMBUSTION

ENGINESENGINES

Four Stroke Cycle – Otto Four Stroke Cycle – Otto CycleCycle

Four Stroke Cycle – Otto Four Stroke Cycle – Otto CycleCycle

Starting position, intake stroke, and compression stroke.

Ignition of fuel, power stroke, and exhaust stroke.

Four Stroke Cycle – Diesel Four Stroke Cycle – Diesel CycleCycle

Four Stroke Cycle – Diesel Four Stroke Cycle – Diesel CycleCycle

Two Stroke Cycle – Otto Two Stroke Cycle – Otto CycleCycle

Comparison of 4 - stroke & Comparison of 4 - stroke & 2 - stroke Engines2 - stroke Engines

• To produce same power 2 stroke To produce same power 2 stroke

cycle engine will be of less weight cycle engine will be of less weight

and spaceand space

• More uniform turning moment in 2 More uniform turning moment in 2

stroke cycle engine stroke cycle engine

• Since no valve in 2 stroke cycle Since no valve in 2 stroke cycle

engine more mechanical efficiency, engine more mechanical efficiency,

simple construction, low initial cost, simple construction, low initial cost,

power saving…power saving…

• Fuel consumption is increased in 2 Fuel consumption is increased in 2

stroke cycle engine stroke cycle engine

Comparison of 4 - stroke & Comparison of 4 - stroke & 2 - stroke Engines2 - stroke Engines

• Two-stroke engines don't last nearly as Two-stroke engines don't last nearly as

long as four-stroke engines due to the long as four-stroke engines due to the

lack of a dedicated lubrication system.lack of a dedicated lubrication system.

• Two-stroke engines produce a lot of Two-stroke engines produce a lot of

pollution due to the combustion of the pollution due to the combustion of the

oil and due to the fact that each time a oil and due to the fact that each time a

new charge of air/fuel is loaded into new charge of air/fuel is loaded into

the combustion chamber, part of it the combustion chamber, part of it

leaks out through the exhaust port.leaks out through the exhaust port.

Fuel Supply – Fuel injection Fuel Supply – Fuel injection in Diesel Enginesin Diesel Engines

Fuel Supply - Carburetion in Fuel Supply - Carburetion in Petrol EnginesPetrol Engines

Different Systems in IC Different Systems in IC EnginesEngines

• Ignition System in Petrol EnginesIgnition System in Petrol Engines

• Cooling System in IC EnginesCooling System in IC Engines

• Lubrication System in IC EnginesLubrication System in IC Engines

– Splash MethodSplash Method

– Pressure feed MethodPressure feed Method

– Properties of Lubricants: Viscosity, Not Properties of Lubricants: Viscosity, Not

vaporizing at operating temperature vaporizing at operating temperature

range, High specific heat, Good cohesive range, High specific heat, Good cohesive

and adhesive qualitiesand adhesive qualities

MPFI EngineMPFI Engine

MPFI EngineMPFI Engine