In a four-stroke internal combustion engine, which stroke follows the compression stroke?
A) Intake Stroke
B) Power Stroke
C) Exhaust Stroke
D) None of the above
The correct answer and explanation is :
The correct answer is B) Power Stroke.
In a four-stroke internal combustion engine, the sequence of events occurs over four distinct strokes: the intake stroke, compression stroke, power stroke, and exhaust stroke. The engine operates in two full rotations of the crankshaft, with each rotation consisting of two strokes. Here’s how each stroke unfolds:
- Intake Stroke: During this first stroke, the intake valve opens, and the piston moves downward in the cylinder. This creates a vacuum that draws the air-fuel mixture into the cylinder from the intake manifold.
- Compression Stroke: Once the intake valve closes, the piston moves upward, compressing the air-fuel mixture in the cylinder. The compression increases the pressure and temperature of the mixture, preparing it for ignition.
- Power Stroke: After the compression stroke, the spark plug ignites the compressed air-fuel mixture, causing it to burn and expand rapidly. This rapid expansion creates a high-pressure force that drives the piston downward. The power stroke is the key stroke where the engine produces mechanical power to drive the vehicle or machine.
- Exhaust Stroke: After the power stroke, the exhaust valve opens, and the piston moves upward again to expel the burnt gases from the combustion chamber through the exhaust valve.
In summary, after the compression stroke, the next stroke is the power stroke, during which the combustion of the air-fuel mixture generates energy to power the engine. This stroke is crucial because it is when the engine actually produces the work that is transferred to the crankshaft. Thus, the correct answer is B) Power Stroke.