I don’t have a
science background. I didn’t grow up dismantling machines and getting oil all
over my clothes. I grew up writing books of accounts. But life is funny
sometimes and here I find myself working in the field of diesel engines and gas
spare parts supply. A business that my family has run for the past 40 years.
And for a commerce
student, wrapping my head around the technical details was not easy. But with
proper guidance and some genuine curiosity, it can be done. For me, the
curiosity came when I read a book about engines that was once owned by my
grandfather, passed on to my father and then to me (much like the business
itself). It was a rusty old book but it didn’t matter because the core working
of an internal combustion engine has hardly changed in the past century. It got
me started on the right foot, which led me to exploring other books, websites
and YouTube videos about the topic.
If you’re new to
this field and find things going over your head, don’t worry we’re all
beginners here. First, let’s start with the basics. Just how does an engine
work?
Spares involved:
-Piston (with pin
and rings)
-Connecting Rod
-Cylinder Liner
-Valves and its
associates like seats and spring
-Fuel Injector
-Camshaft
-Crankshaft
When the engine
runs, there are basically 4 strokes taking place (which is the reason why it’s
called a 4-stroke engine).
1st stroke (Suction Stroke):
Suction air comes
in the liner cylinder through inlet valve. This air pushes the piston down.
2nd Stroke (Compression Stroke):
This air is
compressed as the piston comes up. Here, both intake as well as exhaust valves
remain closed. At the compression stroke, the temperature of pressure air is
550 degree Celsius, which is higher than self ignition value of the diesel.
3rd Stroke (Power Stroke):
The fuel injector
injects fuel in the cylinder which results in an uncontrollable fire, a spark
in the cylinder which will push the piston down. This evaporates the fluid and
because of the fire the temperature gets up to 2500 degree Celsius.
In the whole
4-stroke cycle, this is the only stroke where in the piston is pushed and power
is generated. Hence the name, power stroke.
4th Stroke (Exhaust Stroke)
Due to inertia (the resistance of any physical object to any change in
its state of motion) , the piston would move upwards again and the
exhaust valves open up which would take away gas out from the cylinder.
The rotation of the
valves is done in uniformity by camshaft. Depending on how the crankshaft is
rotating, the camshaft will rotate at half the speed of the crankshaft to match
up the rotation.
This stroke cycle
is universal in any 4-stroke diesel engine, be it an automobile engine in your
car or an industrial engine. The basic principle remains the same; just the
number of strokes taking place at a time on the pistons would change depending
on the size, nature and the application of the engine.
To understand the
above explanation in animation, please refer to the YouTube links below.
