5 Questions
What is the purpose of inlet valve lead in an IC engine?
To open certain degrees earlier than T.D.C. to fill the cylinder to its capacity
What is the purpose of exhaust valve lead in an IC engine?
To open certain degrees earlier than B.D.C. to develop a suction effect by the outgoing gases
What is the purpose of overlap period in an IC engine?
To remain open for certain degrees at the end of the exhaust stroke and beginning of the suction stroke
What does variable valve timing (VVT) system allow in an engine?
Open and close valves at different times depending on operating conditions
How does inlet valve lead contribute to scavenging burnt gases?
By opening certain degrees earlier than T.D.C.
Study Notes
Valve Timing in IC Engine
- Inlet valve lead allows the inlet valve to open before the piston reaches the top dead center (TDC), ensuring that the cylinder is filled with a fresh air-fuel mixture before the piston starts moving down.
- Exhaust valve lead allows the exhaust valve to remain open for a short period after the piston reaches the bottom dead center (BDC), ensuring that the exhaust gases are fully expelled from the cylinder.
Overlap Period
- The overlap period is the time when both inlet and exhaust valves are open simultaneously, which helps to improve the efficiency of the engine by allowing some of the exhaust gases to be scavenged out of the cylinder.
Variable Valve Timing (VVT) System
- VVT system allows the engine to change the timing of the valve operation, enabling the engine to operate at its maximum efficiency under different load and speed conditions.
Scavenging Burnt Gases
- Inlet valve lead contributes to scavenging burnt gases by creating a pressure difference between the cylinder and the atmosphere, allowing the fresh air-fuel mixture to enter the cylinder and push out the remaining exhaust gases.
Test your knowledge on valve timing in internal combustion engines, which involves the opening and closing of valves in relation to the movement of the piston and flywheel. Understand the significance of early valve opening and late closing for optimal cylinder filling and burnt gas scavenging.
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