Inside piston engines, which are the most common design found in cars, there are a number of cylinders. On one end of each cylinder there are valves that open and close to admit fuel and air, and to allow exhaust to escape after each explosion. On the other end there are pistons, connected to what is called a crank shaft.
When fuel and air are compressed inside each cylinder by the piston a spark from the ignition system sets the fuel/air mix on fire. That explosion pushes the piston down, turning the crank shaft just like a crank handle. The turning crank shaft is attached to the car's drive train through a transmission, propelling the car forward.
If you want just the basics then let me tell you it is a heat engine, that is a basic as it gets. The fuel and air supply the right conditions for the fuel to ignite which causes the air in the cylinder to expand rapidly and force the piston down. Others will tell you all the details but it boils down to heat.
When you start your engine, the fuel injectors spray fuel into the cylinders. When the spark plug ignites the fuel it causes an explosion inside the cylinders (in a predetermined order). The expanding gasses inside the cylinders cause the piston to move in a downward motion. This motion causes the crankshaft to turn (via the connecting rods). The rotary motion of the crank shaft is transferred to the accessories on the front of the engine by the belt or belts. One of these accessories is the alternator. The spinning motion of the alternator produces an electrical charge that is used by the fuel injection system (among other things) which delivers fuel to the cylinders....and on and on.
I' ll try to explain you the "theoric cycle" of an engine.
For simplicity we will focus on a single cylinder and assume the valves opens and closes at TDC and BDC only.
TDC top dead center, piston all the way up
BDC bottom dead center, pisdton all the way down.
The piston is at TDC, intake valve begins to open, and stays open during 180°(1/2 turn) till bdc, this causes a vacuum which pulls air/fuel mixture thru the intake tract.
Both valves are closed now, piston goes from bdc to tdc (180°), this is the compression stroke.
The spark plug ignites the now compressed air fuel mixture, wich burns(and not explodes) and expands rapidly, this pushes against the piston, which goes from tdc to bdc. This is the expansion or power stroke.
Now at bdc, exh valve opens and piston goes up, pushing the burnt gases out of the cylinder.
And it goes back to intake...
Note that except expansion cycle all the other cycles piston is driven only by energy accumulated by flywheel
So, what pre-determines the order? The camshaft, which drives the distributor, which delivers spark to the plugs. Cam is connected to crankshaft by timing belt (or chain) and runs at 1/2 speed of crank, and operates intake and exhaust valves in cylinder head. On INTAKE stroke, intake valve open, exhaust valve closed, piston going down and draws air/fuel mix into cylinder. When piston starts UP, intake valve closes and air/fuel mix is compressed. At TOP of compression stroke (usually just before), ignition system fires park plug. With both valves closed, this provides POWER stroke, piston is driven down. As crank rotates, when this piston starts travel back up, exhaust valve opens and spent combustion gases are forced out thru exhaust manifold and tail pipe. Between Earl and myself, those are the basics.
Try looking up ' how it works' and use petrol engine or internal combustion engine. Same for diesel.
There are two stroke and four stroke engine. Most engines are four.
The strokes are: induction( sucks in air and fuel)
Compression ( squeezes it into a small space )
Combustion ( starts to burn the fuel causing very rapid expansion)
Exhaust ( blows spent gas mixture out of cylinders )
That's basic for a four stroke. Other bits are involved eg valves.
These are operated to allow fresh air into each cylinder.( may have fuel in or be injected in )
Then both are closed for the compression and combustion strokes.
Exhaust valve then opens allowing hot gas to exit.
We have spark plug and timing plus various sensors to look at but essentials are there.
Diesels differ in that they don't use a throttle to alter amount of air going in ( fuel is injected or drawn in to suit this opening on inlet side)
They always have maximum air flow in..but simply use throttle to put more fuel in . More fuel means more power. Hence pushing accelerator pedal to go faster ( more fuel)
ok so im a girl and like most stereo types i have no idea how an engine runs, i have google searched it and it seems quite confusing. is there some one who can give me an easy to understand explanation on what goes with making a car or engine run?
i know there are different types of engines and i guess they would each work a little differently so just the basics would be helpful.
