Diesel Engines

Question 1

Describe the induction stage of the 4 stroke cycle

Answer 1

Air is drawn into the cylinder as the piston moves from BDC to TDC, the inlet valve is open to allow the air to draw in.

Question 2

Describe the compression stage of the 4 stroke cycle

Answer 2

Both valves remain closed, the pistol moves towards TDC compressing the fresh air creating heat, towards the end of the stroke atomised fuel is injected into the top of the cylinder.

Question 3

Describe the power stage of the 4 stroke cycle

Answer 3

The piston reaches TDC, the compressed hot air reacts with the atomised fuel creating combustion, this forces the piston down to BDC

Question 4

Describe the exhaust stage of the 4 stroke cycle

Answer 4

The piston begins its return to TDC, the exhaust valve opens allowing the remaining gases to be purged from the cylinder

Question 5

What is the purpose of an engine?

Answer 5

It a prime mover that uses combustion to drive mechanical motion. They can be used to provide electricity to the ships supply

Question 6

What is valve overlap?

Answer 6

Valve overlap is a short period after exhaust where both valves open temporarily to cool the valves and promote charge exchange.