I'm Jake O'Neal, creator of Animagraffs. And this is how a Car Engine works.
Let's start at a single piston, the powerhouse of the engine, and work our way outwards.
The four stroke cycle
When a piston travels to the end of its range, whether up or down, that's a stroke.
Car engines use a four stroke cycle, and it goes like this:
First, intake. The piston descends, sucking an air-fuel mixture into the cylinder
through the intake port, with both intake valves open.
Next, compression. With all valves closed the piston comes back up,
compressing the fuel and air mixture for more powerful combustion.
Then, the power stroke. An electrical spark ignites the compressed fuel and air mixture,
and the resulting combustion forces the piston to the bottom of the cylinder again.
A connecting rod transfers this power to the crankshaft.
Finally, exhaust. The piston comes back up,
pushing the spent mixture out through open exhaust valves and the exhaust port.
Connecting multiple pistons
For smooth power delivery, pistons take turns firing. The firing order for this engine
is 1-3-4-2. Camshafts with specially shaped cams push spring-loaded valves open in turn.
Cam gears and a timing belt or chain links everything to the crankshaft,
and it all spins together.
The crankshaft translates piston power out of the engine.
It has counterweights to balance against the pistons for perfectly smooth revolutions.
This is what RPM means -- we're counting the number of full crankshaft revolutions per minute.
The engine block holds the crankshaft and cylinders, and the cylinder
head holds valves, ports, cams, etc. A geared flywheel sits at one side of the
crankshaft for connection to a transmission. It's also where the starter connects to the system.
This engine has four cylinders arranged in a single row.
But there are many other possible configurations, like six cylinders with three on each side, angled
in a V shape. Or eight. Despite different design goals, the basic engine parts are all there.
Now let's look at the other systems that support this combustion process.
Air intake Air comes in through an air filter,
and then into the intake manifold where it mixes with fuel before being sucked
into individual cylinders through intake ports.
Fuel The fuel pump carries gas from the tank,
through a fuel filter, to the engine
where fuel injectors emit a precisely timed spray of gas into the intake port.
Cooling Engines get very hot during operation
and require a cooling system. Coolant channels around the cylinders and through the cylinder
heads carry a special liquid called "anti-freeze" to keep temperatures within safe operating range.
(It's called anti-freeze because it won't freeze in icy weather).
After cooling hot engine parts, coolant circulates through the radiator.
The radiator has a network of small tubes and fins. Coolant passes through these channels while
air (pulled in by the radiator fan) flows by the tubes, cooling the hot liquid for recirculation.
A water pump keeps the coolant system flowing and properly pressurized.
The thermostat regulates coolant temperature by either routing coolant back
through the engine or to the radiator for further cooling.
Electrical
The spark plug delivers the electrical spark that ignites the fuel-air mixture for combustion.
The metal core is insulated from the outer metal casing with porcelain.
The spark jumps between these conductive surfaces. The coil pack delivers electrical current to the
spark plugs as directed by the ECM (engine control module). The ECM is a computer that
directs many core engine functions like spark timing, valve timing, air to fuel ratio, etc.
The alternator works like a power generator, converting the engine's mechanical energy into
electricity to charge the battery or run other electrical systems while the engine is running.
The battery provides power to the starter for engine start.
Oil Motor oil is used to lubricate,
clean, prevent corrosion, improve sealing, and cool the engine by carrying heat away from moving
parts. Rings around the top of the piston head keep oil out of the combustion process while
otherwise allowing the cylinder to be lubricated. Oil galleries are channels through the
engine block and cylinder head that carry oil to various engine parts.
Oil flows through the engine and back to the oil pan for recirculation.
The oil pump keeps oil properly pressurized and flowing.
Oil rests in the oil pan when not in circulation. The oil filter keeps oil clean from contaminants.
Exhaust
The exhaust manifold collects gases from multiple cylinders into one pipe.
Exhaust flows through the catalytic converter, which captures toxic chemicals in engine exhaust.
And then out through a muffler that reduces exhaust noise.
Full model And finally,
here's the full functioning engine with all the basic systems we've discussed.