Cylinder Block
The cylinder block serves as the fundamental component of an engine, acting as a chamber where fuel combustion occurs. The piston is positioned within the cylinder to regulate the pressure exerted on the exhaust produced by the fuel combustion. Typically made from high-quality cast iron, the block is manufactured through a casting process to form a single piece, as it endures exceptionally high pressure and temperature levels.
Cylinder Head
The upper section of the engine cylinder is secured with a removable cover, which primarily functions to seal the cylinder block and prevent the ingress and egress of gases.
Piston
The piston is designed to slide effortlessly within the cylinder to transfer energy via a connecting rod. It is essential for the piston to be both lightweight and durable, which is why it is often crafted from aluminum alloys or cast iron using a casting method to maintain the strength of the alloys.
Connecting Rod
The connecting rod interlinks the piston and the crankshaft, facilitating the conversion of the piston’s reciprocating motion into rotational movement. It is generally made from high-temperature resistant materials such as nickel-chromium-vanadium steel.
Crankshaft
The crankshaft receives motion from the connecting rod and transforms it into rotational energy. Its design and dimensions are influenced by the number and arrangement of the cylinders.
Valves
Each cylinder within the engine is equipped with two valves. The first valve regulates the intake of fuel and air, while the second controls the expulsion of gases produced from the combustion process.
Engine Bearings
Engine bearings are installed between the moving components—such as the connecting rod, piston, and crankshaft—to minimize friction among these parts.
Spark Plug
The spark plug generates a spark within the combustion chamber, initiating the combustion process between the fuel and compressed air.
Crankcase
The crankcase, often referred to as the main structure of the engine, houses the cylinder, crankshaft, and piston. It is also where engine oil is stored to provide cooling.
Fuel Injector
The fuel injector is responsible for atomizing fuel into the combustion chamber at extremely high pressure, which enhances the mixing of fuel with air efficiently.
Types of Diesel Engines by Size
Diesel engines can be categorized into three primary sizes: large, medium, and small. Small engines generate around 188 kilowatts (approximately 252 horsepower), making them among the most versatile. These engines are commonly employed in cars, trucks, as well as some agricultural, construction, and stationary applications such as small power generators found on recreational boats and mechanical engines, and typically consist of four to six cylinders.
Medium engines produce between 188 to 750 kilowatts (252 to 1006 horsepower), and are predominantly used in heavy-duty trucks, generally containing six cylinders and are turbocharged.
Large diesel engines yield 750 kilowatts or more and are typically utilized in marine applications, locomotives, mechanical functions, and for electric power generation.