How does a Four Stroke Diesel Engine (Compression Ignition Engine) Work?

In this article I going to describe you about how does a four stroke diesel engine work.

Diesel engine which is also known as compression ignition
engine is widely used in automobile industries. Many big vehicles such as truck, bus, car
etc. used diesel engine as the power unit because of its higher torque and greater
mileage than petrol engine. Diesel engine is very popular in Indian market as
well as in other countries because of lower price of diesel than petrol in many
countries. So the requirement of diesel engine is much more than petrol engine.
The ignition temperature of diesel is lower than petrol so
the working of diesel engine is slightly different than petrol engine.

Working of Four Stroke Diesel Engine

The power generation process in four stroke diesel engine is
also divided into four parts. Each part is known as piston stroke. In IC
engine, stroke is referred to the maximum distance travel by the piston in a
single direction. The piston is free to move only in upward and downward
direction. In four stroke engine the piston move two time up and down and the
crankshaft move two complete revolution to complete four piston cycle. These
are suction stroke, compression stroke, expansion stroke and exhaust stroke.
Suction stroke:
In the suction stroke or intake stroke of diesel engine the piston start moves from top end of the cylinder to bottom end of the cylinder and simultaneously inlet valve opens. At this time air at atmospheric pressure drawn inside the
cylinder through the inlet valve by a pump. The inlet valve remains open until
the piston reaches the lower end of cylinder. After it inlet valve close and seal
the upper end of the cylinder.
How does four stroke diesel engine (compression ignition engine) works?
Compression stroke:
After the piston passes bottom end of the cylinder, it starts
moving up. Both valves are closed and the cylinder is sealed at that time. The piston moves
upward. This movement of piston compresses the air into a small space between
the top of the piston and cylinder head. The air is compressed into 1/22 or
less of its original volume. Due to this compression a high pressure and
temperature generate inside the cylinder. Both the inlet and exhaust valves do
not open during any part of this stroke. At the end of compression stroke the piston
is at top end of the cylinder.
How does four stroke diesel engine (compression ignition engine) works?
Power stroke:
At the end of the compression stroke when the piston is at
top end of the cylinder a metered quantity of diesel is injected into the
cylinder by the injector. The heat of compressed air ignites the diesel fuel
and generates high pressure which pushes down the piston. The connection rod
carries this force to the crankshaft which turns to move the vehicle. At the
end of power stroke the piston reach the bottom end of cylinder.
How does four stroke diesel engine (compression ignition engine) works?
Exhaust stroke:
When the piston reaches the bottom end of cylinder after the
power stroke, the exhaust valve opens. At this time the burn gases inside the
cylinder so the cylinder pressure is slightly high from atmospheric pressure.
This pressure difference allows burn gases to escape through the exhaust port
and the piston move through the top end of the cylinder. At the end of exhaust
all burn gases escape and exhaust valve closed. Now again intake valve open and
this process running until your vehicle starts.
How does four stroke diesel engine (compression ignition engine) works?

Pankaj Mishra

Pankaj Mishra is a blogger by passion and Mechanical Engineer by profession. He has completed his B.Tech degree in mechanical engineering in the year 2015. He loves to share his knowledge and help others.

2 thoughts on “How does a Four Stroke Diesel Engine (Compression Ignition Engine) Work?

  • January 17, 2020 at 7:17 pm

    Hey there! I realize this is kind of off-topic but
    I had to ask. Does managing a well-established blog like yours take a lot of work?
    I’m completely new to operating a blog but I do write in my diary on a
    daily basis. I’d like to start a blog so I can share my own experience
    and views online. Please let me know if you have any ideas or tips for new aspiring
    bloggers. Thankyou!


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