Examkin

Question

Difficulty: EasyEngine Principles and Internal Components

A standard automotive piston engine relies on a continuous four-stage operating sequence to convert fuel energy into mechanical power. Arrange the following four strokes in the correct chronological order of operation, starting from the introduction of fresh charge into the cylinder.

  1. 1Intake stroke: The intake valve opens as the piston travels downward, drawing the fresh air-fuel mixture into the cylinder.
  2. 2Compression stroke: Both valves remain tightly closed while the piston moves upward, squeezing the mixture into a smaller volume.
  3. 3Power stroke: Spark ignition combusts the compressed mixture, rapidly expanding gases to force the piston downward.
  4. 4Exhaust stroke: The exhaust valve opens as the piston moves upward, sweeping the burned gases out of the cylinder.

Answer

Intake stroke → Compression stroke → Power stroke → Exhaust stroke
The four-stroke engine cycle operates in the strict sequential order of Intake, Compression, Power, and Exhaust. The intake stroke pulls the air-fuel mixture into the cylinder, the compression stroke squeezes the mixture with both valves closed, the power stroke harnesses burning gases to drive the piston down, and the exhaust stroke pushes spent gases out through the open exhaust valve to reset the cylinder.

Step-by-Step Solution

1
Identify the introductory stroke of the four-stroke cycle
The intake stroke begins the cycle as the descending piston creates low pressure to draw in the air-fuel mixture through the open intake valve.
Combustion requires an air-fuel charge inside the cylinder before any subsequent mechanical operation can take place.
2
Determine the preparation stroke preceding ignition
The compression stroke follows as the rising piston compresses the trapped mixture against closed valves.
Compressing the air-fuel mixture elevates pressure and temperature, maximizing combustion efficiency when ignited.
3
Identify the energy-producing power phase
The power stroke takes place when ignition forces the piston downward to deliver mechanical torque to the crankshaft.
This is the sole stroke in the four-stroke cycle that generates positive mechanical power.
4
Determine the clearing stroke that concludes the cycle
The exhaust stroke completes the sequence as the piston ascends to push spent combustion gases out through the open exhaust valve.
Evacuating spent exhaust gases clears the cylinder volume so a fresh charge can enter on the next intake stroke.

Key Concept

Four-stroke internal combustion cycle operating sequence (Intake, Compression, Power, Exhaust)
Estimated Time:45s
Rate this question

Topics

Engine Principles and Internal Components

More questions from this topic