Intake stroke

Definition

The intake stroke is the phase in an internal combustion engine cycle where the engine draws in a mixture of air and fuel into the combustion chamber. This process is crucial because it sets up the conditions for the subsequent compression and combustion stages, directly influencing engine efficiency and power output.

5 Must Know Facts For Your Next Test

1. During the intake stroke, the piston moves down in the cylinder, creating a vacuum that pulls in the air-fuel mixture through the open intake valve.
2. The duration and timing of the intake stroke are critical for optimal engine performance; improper timing can lead to incomplete filling of the combustion chamber.
3. In multi-cylinder engines, multiple intake strokes occur simultaneously across cylinders, improving overall engine efficiency and smoothness.
4. The mixture of air and fuel can be adjusted to optimize performance under various operating conditions, like heavy acceleration or cruising.
5. The design of the intake manifold can significantly affect how well the air-fuel mixture enters the combustion chamber during the intake stroke.

Review Questions

• How does the intake stroke contribute to the overall efficiency of an internal combustion engine?
  • The intake stroke is essential for drawing in the right amount of air-fuel mixture needed for combustion. If this process is efficient, it helps ensure that there is enough mixture for optimal power production without wasting fuel. The effectiveness of the intake stroke can influence engine performance parameters like horsepower and torque, making it a critical phase in achieving overall engine efficiency.
• Discuss how variations in timing during the intake stroke can affect engine performance and potential issues that may arise.
  • Variations in timing during the intake stroke can lead to several performance issues. For example, if the intake valve closes too early, it can trap insufficient air-fuel mixture in the combustion chamber, leading to poor combustion efficiency. On the other hand, if it closes too late, it may allow unburned mixture to escape, wasting fuel and decreasing power. These timing issues can result in rough engine operation and reduced overall performance.
• Evaluate how advancements in intake system design impact modern internal combustion engines compared to earlier designs.
  • Advancements in intake system design have significantly improved modern internal combustion engines by enhancing airflow dynamics and optimizing fuel-air mixing. Technologies such as variable intake manifold systems allow for better control over airflow depending on engine speed and load. These innovations lead to improved power output, fuel efficiency, and lower emissions when compared to older designs that often had fixed geometries. Overall, modern designs help meet stricter environmental regulations while maintaining high performance.

Related terms

Piston: A cylindrical component that moves up and down within the engine cylinder, compressing the air-fuel mixture during the compression stroke.

Combustion chamber: The space within the engine where the air-fuel mixture is compressed and ignited to produce power.

Four-stroke cycle: A type of internal combustion engine cycle that consists of four distinct strokes: intake, compression, power, and exhaust.