4843 engines john daniel

describe the operating principles of diesel engines

The Direct Injection Engine
The engine uses the heat caused by compressing air in a cylinder, with a piston, to ignite fuel oil which is injected into the cylinder. This oil burns and creates an increase in pressure which forces the piston back down the cylinder, providing the power. The burnt gasses are exhausted from the cylinder and replaced by fresh charge through valves, commonly positioned above the piston in the cylinder head.
The fuel oil is pushed into the engine under high pressure at the correct time by an injector pump. The oil is sprayed into the engine cylinder as a very fine mist from the nozzle of an injector. The fine fuel oil mist readily mixes with hot air in the cylinder, ignites and provides an efficient burn. The injector pump also meters the amount of fuel delivered. The more fuel the more power the engine.

 Operating cycle of the common four stroke engine .the engine provides one combustion event during the four piston strokes

Its a DI cylinder.

fuel being injected into a swirl chamber with a heated glow plug

 

4843 engines

describe the operating principles of petrol engines

A model of a four stroke petrol engine.

• Rocker (A)
• Inlet Valve (B)
• Piston (C)
• Connecting Rod (D)
• Crankshaft (E)
• Camshaft (F)
• Pushrod (G)
• Exhaust Valve (H)

The 4 stroke is so called as all the required functions to make the engine run are completed in 4 strokes of the piston-- inlet, compression, power, exhaust.

The first stroke is the inlet or induction stroke. As the piston moves down inside the cylinder, the inlet valve opens allowing a fresh change of mixed gasoline and air to enter the cylinder.

After the piston has completed the inlet stroke, the inlet valve closes and the piston returns back up inside the cylinder to compress the mixture in readiness for the power phase.

After the gases have been ignited, the piston is driven down inside the cylinder forcing the crankshaft to rotate.

As the piston completes its power stroke, the exhaust valve opens in readiness for the exhaust phase.