How an automobile engine works


From this diagram we are going
to learn how, basically, an automobile engine works. This is a cylinder. This is basically one cylinder
that we have. And these are the walls of the cylinder, and
this is the piston that we have. And this piston is
what moves up and down. And we have two inlet. One inlet is for fuel and air
to come in and mixture. And this is a valve that
opens and closes. And there is another outlet
here that takes out the exhaust gases, and there is
another valve that opens and closes at appropriate times. And when the fuel and the air
mixture is inside, the spark plug provides a spark to
ignite the mixture. Now, let’s see in sequence what
happens in this cylinder. This piston, basically,
moves up and down. So the first step is to bring
the fuel and oxidizer, or air, inside the mixture. So this valve opens up. This valve, of course,
is closed. And this fuel and air mixture
comes in as this piston is pushed down. This acts like a syringe,
a medical syringe. When we push this down, the
fuel and air mixture is basically sucked in, and it
fills up this entire volume as this piston comes down. That is the first
step or stroke. This is a four-stroke engine
that we are talking about. First stroke is intake. And the second stroke, now, the
second step is we close both of these valve and
push this mixture. This mixture is, again by
pushing the piston up, this mixture that is in here is
compressed to very high pressures, roughly about eight
times to nine times. And this piston moves
back up here. And again, we have to spend
energy to move the system or compress this mixture here. When this mixture is
compressed to the predetermined pressures, at
that time the spark plug ignites this mixture. And this flame front travels
all the way and burns all this fuel. And this fuel reaches very
high temperatures, and it pushes the piston all the way
down, all the way down. So this is actually
the power stroke. The first stroke is intake. The second stroke
is compression. Compression. And the third stroke is
the power stroke. That is the stroke that gives us
the power from this engine. In the first stroke and the
second stroke, we have to supply the energy that is
required to bring in the oxidizer and fuel and
also to compress. And after this mixture expands,
or pushes the piston down, this valve, this exhaust
valve, will open. And of course, this valve
is still closed. And the piston, again, moves
back up, for which we have to supply the power. And all of these gases go out
through this exhaust. And once the exhaust gasses
are out, this valve closes again and this valve
opens, and the entire cycle again repeats. So the fourth stroke is
the exhaust stroke. So this is a, basically,
four-stroke engine that we are talking about. We need to know the four strokes
and the important components of this
engine cylinder. And there generally will
be multiple cylinders. We’re talking about one here. And there could be 4,
there could be 6. There could be 8, or even
10 or even 12 sometimes. So as the engine becomes bigger
and bigger, you have more cylinders. And that gives us more power.