Examkin

Soru

Zorluk: ZorEngine Principles and Internal Components

When timing an automotive engine valvetrain, a technician must synchronize the camshaft and crankshaft. If an engine operates at a crankshaft speed of 3200 RPM3{}200\text{ RPM}, what is the rotational speed of the camshaft, and what total crankshaft rotation corresponds to each complete opening and closing cycle of an intake valve?

  1. A
    The camshaft rotates at 6400 RPM6{}400\text{ RPM}, and the intake valve cycle corresponds to 360∘360^\circ of crankshaft rotation.
  2. The camshaft rotates at 1600 RPM1{}600\text{ RPM}, and the intake valve cycle corresponds to 720∘720^\circ of crankshaft rotation.Cevap
  3. C
    The camshaft rotates at 3200 RPM3{}200\text{ RPM}, and the intake valve cycle corresponds to 180∘180^\circ of crankshaft rotation.
  4. D
    The camshaft rotates at 800 RPM800\text{ RPM}, and the intake valve cycle corresponds to 1440∘1{}440^\circ of crankshaft rotation.

Cevap

The camshaft rotates at 1600 RPM1{}600\text{ RPM}, and the intake valve cycle corresponds to 720∘720^\circ of crankshaft rotation.
In a four-stroke internal combustion engine, one full cycle requires four distinct piston strokes (intake, compression, power, and exhaust). Each piston stroke turns the crankshaft through 180∘180^\circ, meaning a full cycle requires 720∘720^\circ (two complete revolutions) of crankshaft rotation. Since each intake valve opens and closes only once per full cycle, the camshaft must complete one revolution for every two revolutions of the crankshaft. Therefore, at a crankshaft speed of 3200 RPM3{}200\text{ RPM}, the camshaft turns at half that rate (1600 RPM1{}600\text{ RPM}), and the complete valve actuation cycle corresponds to 720∘720^\circ of crankshaft rotation.

Adım Adım Çözüm

1
Determine the rotational speed relationship between the crankshaft and camshaft in a four-stroke engine.
The camshaft is geared to rotate at exactly half the speed of the crankshaft (a 1:2 drive ratio), yielding 3200 RPM2=1600 RPM\frac{3{}200\text{ RPM}}{2} = 1{}600\text{ RPM}.
Each valve must open and close exactly once per complete four-stroke combustion cycle.
2
Calculate the degrees of crankshaft rotation required for one complete four-stroke cycle.
A four-stroke cycle consists of four distinct piston strokes of 180∘180^\circ each, totaling 4×180∘=720∘4 \times 180^\circ = 720^\circ (two complete crankshaft revolutions).
The four strokes (intake, compression, power, and exhaust) each require half a crankshaft revolution (180∘180^\circ).

Anahtar Kavram

Camshaft-to-crankshaft 1:2 rotational speed ratio and four-stroke cycle degree duration
Tahmini Süre:1m 15s
Bu soruyu puanla

Konular

Engine Principles and Internal Components

Bu konudan daha fazla soru