Have you ever wondered exactly how your car engine works? In this article, we will specifically discuss the 4-stroke internal-combustion engine, look at the individual components of a car engine and explain their functions and purpose. By the end of the article, you should have a clearer understanding and a new respect for your car’s engine.
YOUR CAR’S ENGINE – THE HEART OF YOUR CAR
Your car’s engine is the heart of your car and is a complex, fascinating component that converts heat from burning fuel into power that enables your car to move.
The necessary chain of reactions is set in motion by a spark, which ignites a fuel/air mixture inside a sealed cylinder (internal combustion), causing an explosion which in turn provides the power to drive the car.
A CAR’S ENGINE IS MADE UP OF THE FOLLOWING PARTS:
Engine Block (Cylinder Block), Combustion Chamber, Cylinder Head, Pistons, Piston Rings, Piston Pin, Crankshaft, Camshaft, Connecting Rod, Timing Chain, Valve Train, Engine Valves, Rocker Arms, Pushrods/Lifters, Fuel Injectors, Spark Plugs, Oil Pan, Manifolds, Gasket, Cylinder Liner and Flywheels.
THE THREE KEY PARTS OF A CAR ENGINE
In a broad way, an engine can be divided into three key parts:
The Cylinder Head (also known as the Engine Head), the Engine Block and the Oil Sump.
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CYLINDER HEAD
This is the detachable upper part of the engine. It is the entry point for the fuel to enter the engine chamber and for the exhaust gases to exit. It consists of the camshafts, valves and spark plugs.
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ENGINE BLOCK (CYLINDER BLOCK)
This is the lower, heavier part of the engine, a casing for the main moving parts of the car’s engine and is where the combustion takes place. The key components in the cylinder block are the cylinders, pistons and crankshaft, and sometimes the camshaft
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OIL SUMP
This is located in the lowermost part of the engine and consists of the oil pan and the oil filter.
INTERNAL COMBUSTION ENGINES – THE FUNDAMENTALS
Let’s start by specifically exploring how an internal-combustion engine works. An internal combustion engine is a modern engine that runs on either petrol or diesel. This engine is considered a technological wonder due to its sophisticated technology.
An internal-combustion engine is basically a heat engine, converting energy from the heat of burning the fuel to torque or motion which is applied to the wheels, making the car move. And because this combustion takes place internally, it is thereby known as an internal-combustion engine.
Internal combustion engines have pistons that are located inside cylinders that move up and down the cylinder. The piston is connected by a connecting rod to a crankshaft, and their movement causes the crankshaft to rotate, which in turn powers the car’s drive wheels. Depending on the vehicle, there could be anything between two and 12 cylinders in its engine, with a piston moving up and down in each.
Almost every modern-day car with an internal-combustion engine uses a four-stroke combustion cycle. This means that it creates usable power in 4-strokes, namely Intake stroke, Compression Stroke, Power Stroke and Exhaust Stroke. The four-stroke cycle is also known as the Otto cycle, in honour of Nikolaus Otto, who invented it in 1867.
THIS IS WHAT HAPPENS DURING THE CYCLE:
- The piston starts at the top of the cylinder, the intake valve opens allowing the cylinder to fill with air and fuel, moving the piston down.
- The piston moves back up, compressing this fuel-air mixture. This pressure creates a powerful explosion that ignites the mixture, creating motion.
- This propels the piston upwards – when it reaches the top of its stroke, Power Stroke, the spark plug then emits a spark to ignite the fuel. This creates an explosion driving the piston back down. It is these explosions that propel your car to move.
- Once the piston hits the bottom of its stroke, Exhaust Stroke, the exhaust valve will open and burned gases leave via the exhaust.
Now the engine is ready for the next cycle and the intake valve opens to take in another charge of fuel and air.
THE KEY COMPONENTS IN THE FOUR-STROKE COMBUSTION CYCLE
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CYLINDER HEAD
The core of the car’s engine is the cylinder head which is located at the top of the engine block. This is where fuel combustion takes place and where the power for your car is generated. It houses components such as the inlet and exhaust valves as well as springs and lifters. Most cars have a 4. 6 or 8-cylinder engine – the numbers indicate the number of cylinders your engine has and the higher the number, the more power is produced. In a multi-cylinder engine, the cylinders will either be laid out in a straight line, V-shaped or in a flat arrangement (also known as horizontally opposed or boxer).
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SPARK PLUG
Spark plugs provide a high-voltage current that ignites the fuel/air mixture in the combustion chamber which put the pistons in motion to power your vehicle. You will find a spark plug at the top of each cylinder head.
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INTAKE VALVES AND EXHAUST VALVES
These engine valves are located in the cylinder head. As their names suggest, the main function of the intake and exhaust valves is to let air in and out of the cylinders at the correct time. Intake valves open to allow the air/fuel mixture to flow into the engine’s cylinders prior to compression and ignition, while the exhaust valves open after ignition has occurred to expel the exhaust gases from the combustion process.
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PISTON
A piston is a cylindrical engine component that slides back and forth in the cylinder caused by forces produced during the combustion process.
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PISTON RINGS
Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder, sealing the combustion chamber as well as transferring heat to the cylinder wall and controlling the consumption of oil.
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CONNECTING ROD
The connecting rod also called a ‘con rod’, is a part of a piston engine that connects the piston to the crankshaft.
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CRANKSHAFT
The crankshaft is known as the backbone of the internal combustion engine. A crankshaft converts the vertical, reciprocating motion of the pistons into a horizontal rotational motion. It transmits power to the wheels through the car’s gearbox.
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OIL SUMP
The oil sump is a metal dish covering the bottom of the engine block, also known as an oil reservoir. It contains the engine oil required for the lubrication of all the engine’s parts.
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CAMSHAFT
Often the block also houses the camshaft, which is responsible for opening and closing the valves in the cylinder head. Sometimes the camshaft is in the head or mounted above it.
TURBOCHARGED AND SUPERCHARGED ENGINES
There are engines on the market today with some variants and differences that have been made to them. For example, Turbocharged and Supercharged engines, that fall under the forced-induction options. This is when additional air is pumped into the combustion chamber increasing the available oxygen and thus the amount of fuel that can be burnt, which results in more power output and increased efficiency, especially when combined with the use of an intercooler.
Diesel engines can also be turbocharged or supercharged (but without the use of spark plugs because it uses the heat of compression as the source for igniting the fuel). You may have heard the term Turbo-Diesel which is simply a turbocharged diesel engine.
DIFFERENT TYPES OF CAR ENGINES OVER THE YEARS
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EXTERNAL COMBUSTION ENGINE
An external combustion engine (for example the steam engine in olden-day trains and steamboats) is where the fuel (coal, wood, oil) burns outside the engine to create steam. It is the steam that creates motion inside the engine.
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INTERNAL COMBUSTION ENGINE
An internal combustion engine is a modern marvel of an engine that runs on either petrol or diesel. The main difference between petrol and diesel-run engines is that diesel does not use spark plugs.
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HYBRIDS
Hybrids are car engines that use two or more sources of power, usually an internal combustion engine and an electric motor.
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ALL ELECTRIC
An electric motor has a battery instead of a petrol tank and converts electrical energy into mechanical energy in order to drive the car. It makes sense that an all-electric car has far fewer parts than a traditional engine, and does not need to be lubricated, making them much easier to maintain.
As long as the engine is of the internal-combustion variety, the basics of how it works remain the same. Now you can proudly say you know how a car engine works!
