Diesel Engine
An internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber.
Four-Stroke Cycle
Intake, compression, combustion, and exhaust
Intake Stroke
Air only is drawn into the cylinder
Compression Stroke
The piston compresses the intake air, increasing the temperature enough for the fuel to ignite
Combustion Stroke
Fuel is injected into the combustion chamber and ignites from the high temperature of the compressed air.
Exhaust Stroke
The piston forces exhaust gases out of the cylinder.
Diesel Engine Compression Ratio
14-23
Gasoline Engine Compression Ratio
9-11
Diesel Engine Output Control
Controlled by adjusting the fuel injection volume.
Preheating System
Heats the compression air for cold engine starting
Glow Plug
A type of preheating system that heats the air inside the combustion chamber.
Intake Heater
A type of preheating system that directly heats the air coming from the air cleaner.
Cetane Number
Represents the ignitability of diesel fuel. A higher number means better ignitability.
Diesel Knock
A noticeable noise and vibration caused by a sharp rise in pressure inside the combustion chamber.
Causes of Diesel Knock
Low engine temperature, low intake air temperature, low cetane number fuel, early injection timing, and poor fuel mixing.
How to Prevent Diesel Knock
Shorten the ignition delay by using high cetane fuel, raising compression pressure, and maintaining proper engine temperatures and injection timing.
Ignition Delay
The period where injected fuel evaporates and mixes with air to form an ignitable mixture.
Flame Propagation
The stage where ignition starts and the flame burns outward, causing a sharp pressure rise.
Direct Combustion
The stage where fuel is burned with the flame in the combustion chamber immediately after injection
After Burning
The period where remaining fuel that could not burn earlier combusts after the main injection ends.
Direct Injection Combustion Chamber
A combustion chamber formed between the cylinder head and piston where fuel is injected directly
Swirl Chamber Type Combustion Chamber
A combustion chamber with a spherical swirl chamber connected to the main combustion chamber to create a swirling air flow.
Liner Type Cylinder
A cylinder design where a cylinder liner is inserted into the cylinder block.
Linerless Type Cylinder
A cylinder design that uses a special alloy cast iron which is more resistant to wear, without a separate liner.
