Coconote
AI notes
AI voice & video notes
Export note
Try for free
Overview of Internal Combustion Engines
Aug 26, 2024
Internal Combustion Engine (IC Engine) Overview
Definition
: An IC engine is an internal combustion engine where ignition and combustion of fuel occur inside the engine.
Principle
: Charge is ignited inside a combustion chamber under high pressure.
Historical Background
First Commercially Successful IC Engine
: Created by ATN Lenore around 1860.
First Modern IC Engine
: Known as the Auto Engine, created in 1876 by Nikolaus Otto.
Types of IC Engines
Common Types
:
Two-stroke piston engines
Four-stroke piston engines
Six-stroke piston engines
Wankel rotary engines
Components of IC Engine
Main Parts
Cylinder Block
: Structure containing cylinders and other components.
Cylinder
: Chamber where fuel is combusted and power is generated.
Cylinder Head
: Sits above the cylinders and forms the roof of the combustion chamber.
Piston
: Movable part that converts energy from combustion into mechanical work.
Piston Rings
: Metallic rings sealing the combustion chamber, minimizing gas loss to the crankcase.
Connecting Rod
: Connects the piston to the crankshaft; converts reciprocating motion into rotary motion.
Small End
: End that connects to the piston.
Big End
: Connects to the crankshaft.
Crankshaft
: Converts reciprocating motion into rotational motion.
Crankcase
: Main housing providing support for the cylinder and crankshaft bearings.
Valves
: Control air intake and exhaust from the cylinder.
Crank Pin
: Connects the crankshaft to the connecting rod.
Intake and Exhaust Ports
: Passages between the manifold and the valves.
Spark Plug
: Used in petrol engines to ignite the air-fuel mixture.
Injector
: Used in diesel engines to spray fuel into the combustion chamber.
Working Principles of Different Engine Types
Four-Stroke Petrol Engine
Cycle
: Autocycle (constant volume cycle)
Four Strokes
: Intake, Compression, Power, Exhaust (completed in two revolutions of the crankshaft).
Intake Stroke
: Inlet valve opens, and air-fuel mixture enters the cylinder.
Compression Stroke
: Piston moves upward, compressing the mixture.
Power Stroke
: Spark ignites the mixture, pushing the piston down.
Exhaust Stroke
: Exhaust valve opens, burnt gases exit.
Four-Stroke Diesel Engine
Cycle
: Diesel cycle (constant pressure cycle)
Similar to Petrol Engine
but uses an injector instead of a spark plug.
Intake Stroke
: Air enters the cylinder.
Compression Stroke
: Air is compressed; diesel fuel is injected.
Power Stroke
: Combustion pushes the piston down.
Exhaust Stroke
: Exhaust gases are expelled.
Two-Stroke Petrol Engine
Cycle
: Completes in one revolution of the crankshaft.
Two Strokes
: Combines intake, compression, power, and exhaust.
First Stroke
: Piston moves up, compressing the mixture and drawing in fresh charge.
Second Stroke
: Combustion occurs, pushing the piston down and expelling exhaust.
Two-Stroke Diesel Engine
Similar Operation
to the two-stroke petrol engine but uses diesel fuel.
Advantages and Disadvantages
Four-Stroke vs. Two-Stroke Engines
Advantages of Two-Stroke Engines:
Higher power output (1.7 times that of four-stroke).
More uniform turning effort on the crankshaft.
Lighter and smaller.
Simpler gear arrangement for reversing.
Disadvantages of Two-Stroke Engines:
Higher cylinder temperature increases fire risk.
More lubricant consumption.
Lower thermal efficiency due to fuel losses during scavenging.
Higher wear and tear due to faster valve gear operation.
Conclusion
Understanding IC engines is crucial for various applications in automotive and mechanical engineering.
Further learning resources available.
📄
Full transcript