Understanding Diesel Engines: Principles, Technical Parameters, and Components

The fundamental working principle of a diesel engine is to adopt high-pressure injection and compression ignition, causing fuel to combust within the cylinder. This creates high-temperature and high-pressure gas that expands in the cylinder, pushing the piston to move reciprocally. Then, through the piston connecting rod-crank mechanism, this reciprocal motion is converted into the rotational motion of the crankshaft, thereby driving mechanical work.

 

There are many components in a diesel engine, with the main ones including:

 

1. Cylinder Block

The main body structure of the engine, containing the cylinders.

 

 

2. Cylinder Head

Mounted on top of the cylinder block, it encloses the cylinder.

3. Piston

Reciprocates within the cylinder and comes into contact with the fuel-air mixture in the combustion chamber.

 

 

4. Piston Ring

Fitted around the piston, maintains cylinder pressure and controls lubrication.

5. Connecting Rod

Connects the piston to the crankshaft, transferring the reciprocating motion of the piston into the rotational motion of the crankshaft.

6. Crankshaft

Converts the up-and-down motion of the piston into rotary motion, transferring it to the transmission system.

7. Camshaft

Controls the opening and closing of the valves.

8. Valves

Regulate the flow of gases into and out of the cylinder, including the intake and exhaust valves.

 

9. Fuel Injector

Injects fuel into the combustion chamber at timed intervals and precise quantities.

 

10. Fuel Pump

Transports fuel to the injector.

 

11. Turbocharger

Uses the energy from exhaust gases to increase air intake, enhancing engine power.

 

 

12. Crankcase Ventilation System

Controls and reduces pressure and emissions in the crankcase.

 

13. Oil Pump

Supplies lubricating oil to the engine's moving parts.

 

14. Oil Pan

Stores the lubricating oil.

 

15. Water Pump

Responsible for circulating coolant to help cool the engine.

 

16. Fan and Radiator

Assist in cooling the coolant to prevent the engine from overheating.

 

17. Starter Motor

The mechanical device that uses electrical energy to start the engine.

 

18. Alternator 

Charges the battery while the engine is running and powers other electrical devices.

 

19. Control System

Modern diesel engines typically have an Electronic Control Unit (ECU) to precisely control fuel injection and valve timing.

 

Diesel Engine Classification

 

Classification Method	Classification
By Working Cycle	Four-stroke diesel engines and two-stroke diesel engines.
By Cooling Method	Water-cooled diesel engines and air-cooled diesel engines.
By Intake Method	Turbocharged diesel engines and naturally aspirated (non-turbocharged) diesel engines.
By Speed	High-speed diesel engines (more than 1000 rpm), medium-speed diesel engines (350-1000 rpm), and low-speed diesel engines (less than 350 rpm).
By Combustion Chamber	Direct injection diesel engines, swirl chamber diesel engines, and precombustion chamber diesel engines.
By Action of Gas Pressure	Single-acting diesel engines, double-acting diesel engines, and opposed piston diesel engines.
By Number of Cylinders	Single-cylinder diesel engines and multi-cylinder diesel engines.
By Application	Marine diesel engines, locomotive diesel engines, automotive diesel engines, agricultural machinery diesel engines, construction machinery diesel engines, power generation diesel engines, and stationary power diesel engines.
By Type of Fuel Used	Gasoline engines, diesel engines, liquefied petroleum gas engines, and dual-fuel engines.
By Arrangement of Cylinders	Inline engines, V-type engines, radial engines, horizontally opposed engines, and flat engines.

 

The main technical parameters of a diesel engine include power, displacement, torque, speed, compression ratio, fuel efficiency, cooling system, starting method, emission standards, dimensions and weight, cylinder bore and stroke, number of cylinders and their arrangement, fuel type, and more.