What is the primary function of the intake valve?

What is the primary function of the intake valve?

• A. Bring air to the engine
• B. Expel exhaust gases
• C. Supply fuel to the cylinder
• D. Seal the combustion chamber

Answer: (A)

Air must enter the cylinder for combustion, and the intake valve is what allows that flow. It opens during the intake stroke to let air into the cylinder (in many engines the air then carries fuel that’s metered by injectors elsewhere). Without this valve opening at the right time, the cylinder wouldn’t fill and a proper air–fuel mixture couldn’t form. The intake valve doesn’t inject fuel itself, and the job of expelling exhaust gases belongs to the exhaust valve. When closed, both valves help seal the chamber, but the primary function of the intake valve is to admit air into the cylinder.

Air must enter the cylinder for combustion, and the intake valve is what allows that flow. It opens during the intake stroke to let air into the cylinder (in many engines the air then carries fuel that’s metered by injectors elsewhere). Without this valve opening at the right time, the cylinder wouldn’t fill and a proper air–fuel mixture couldn’t form. The intake valve doesn’t inject fuel itself, and the job of expelling exhaust gases belongs to the exhaust valve. When closed, both valves help seal the chamber, but the primary function of the intake valve is to admit air into the cylinder.