How does a motor car work?
Ans: Modern day life cannot be imagined without cars, trains, motor-cycles etc. All of us know that there engines run on diesel or petrol as fuel but, how exactly diesel or petrol makes these machines run? What’s the science behind it? These are a few questions we will try to address through this question. So, get along..
How does a car engine works-
The car or vehicle runs by energy released in the engine by burning fuel. The chemical energy of fuel is converted into heat energy which moves the piston. There are 4 stages or strokes as we call it in this energy conversion cycle.These are shown in the figure below.
4 Stage/ Strokes Engine: Working Mechanism-
There is a cylinder which houses a piston, intake valve, exhaust valve, fuel injection system. The piston in turn is connected to a crank-shaft.
Intake Stroke- The piston in the cylinder is going down. Intake valve is Open. The air enters through this valve which fills the cylinder.
Compression Stroke- The piston moves upwards pushing the air inside. The Intake valve remains closed. Hence, the air in the cylinder gets compressed and heated up.
Power Stroke- When the piston reaches at the top end, the air inside is at very high temp. (greater than 1000 0C). At this instant, the fuel (diesel) is injected into the cylinder. The moment is enters in to the cylinder, it catches fire & huge volume of gases is produced and pressure rises to a very high level. Hence the piston is pushed back downwards and crank rotates.
Exhaust Stroke- This is the 4th and final stroke in this cycle. At the end of power stroke, when the piston is at the cylinder bottom, the exhaust valve opens. The gases start getting out through this valve. As the crankshaft is rotating, the piston starts upwards movement and helps flush the gases out.
At the end of this exhaust stroke, the intake valve again opens and this cycle repeats. The linear motion of piston is converted into rotational motion of the shaft which rotates the wheels and thus car runs.
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