Here is a more detailed description of the function of valves in an engine:
1. Intake Valves:
- During the intake stroke of the piston, the intake valves open to allow a mixture of air and fuel (in gasoline engines) or air (in diesel engines) to enter the cylinder.
- The intake valve remains open until the piston reaches the bottom of its stroke, and then the valve closes to seal the cylinder.
2. Exhaust Valves:
- During the exhaust stroke of the piston, the exhaust valves open to allow the burnt gases produced by combustion in the cylinder to escape.
- The exhaust valve remains open until the piston reaches the top of its stroke, and then the valve closes to seal the cylinder and prepare it for the next cycle.
3. Timing and Control:
- Valves are controlled precisely by the camshaft, which is connected to the crankshaft through gears or a timing belt/chain.
- The camshaft has lobes or cams that actuate the valves, determining the timing of when the valves open and close in relation to the piston's movement.
- Some engines may also incorporate variable valve timing (VVT) systems, which can adjust the timing of the valve openings to optimize engine performance and efficiency.
4. Seating and Sealing:
- Valves feature valve seats, which are designed to seal against the valve heads to prevent leakage of gases between the valve and the cylinder head or block.
- To ensure a good seal, the valve surfaces and valve seats are precision-machined and may also incorporate valve springs and other mechanisms to keep them properly closed when they are not being actuated.
By precisely controlling the flow of gases through the engine, valves play a crucial role in the proper operation of an internal combustion engine.
