In a four-stroke diesel engine, the exhaust valve opens before the piston reaches the Bottom Dead Center to:

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RRB JE CBT 2 (Mechanical Engineering) ReExam Official Paper (Held On: 04 Jun, 2025)

Answer 1

Explanation:

Exhaust Valve Timing in a Four-Stroke Diesel Engine

A four-stroke diesel engine operates through four distinct strokes: intake, compression, power (combustion), and exhaust. The exhaust valve timing plays a crucial role in optimizing engine performance and ensuring efficient removal of burnt gases from the cylinder. Specifically, the exhaust valve opens slightly before the piston reaches the Bottom Dead Center (BDC) during the power stroke. This timing is carefully designed to improve various aspects of engine operation, including fuel efficiency, cylinder scavenging, and overall thermal performance.
The exhaust valve before the piston reaches BDC does not directly contribute to fuel atomization. Fuel atomization refers to the process of breaking fuel into fine droplets to ensure better mixing with air, which occurs during the injection process in the compression stroke of a diesel engine. The exhaust valve opening is primarily related to the removal of exhaust gases and does not influence the atomization of fuel.