Power System

The power plant of the automobile includes an engine, fuel supply and exhaust, cooling and heating systems. Let’s speak about the internal-combustion engine, because this is the most common engine. Gasoline internal-combustion engines power most automobiles, but some engines use diesel fuel, electricity, natural gas, solar energy, or fuels derived from methanol (wood alcohol) and ethanol (grain alcohol).

The basic components of an internal-combustion engine are the engine block, cylinder head, cylinders, pistons, valves, crankshaft, and camshaft. The lower part of the engine, called the engine block, houses the cylinders, pistons, and crankshaft. The components of other engine systems bolt or attach to the engine block. The block is manufactured with internal passageways for lubricants and coolant. Engine blocks are made of cast iron or aluminium alloy.

The upper part of the engine is the cylinder head. It seals the tops of the cylinders. Pistons compress air and fuel against the cylinder head before ignition. The top of the piston forms the floor of the combustion chamber. Fuel vapor enters and exhaust gases leave the combustion chamber through openings in the cylinder head controlled by valves. Inlet (intake) valves open to allow fuel to enter the combustion chambers. Outlet (exhaust) valves open to let exhaust gases out.

You know that the greatest number of cars use piston engines. The four-cycle piston engine requires four strokes of the piston per cycle. The first downstroke draws in the petrol mixture. The first upstroke compresses it. The second downstroke—the power stroke—following the combustion of the fuel, supplies the power, and the second upstroke evacuates the burned gases. Intake and exhaust valves in the cylinder control the intake of fuel and the release of burned gases. These gases escape with the sudden opening of the exhaust valve. They rush to a silencer (muffler), an enlarged section of piping containing expanding ducts and perforated plates through which the gases expand and are released into the atmosphere. Greater smoothness of operation of the four-cycle engine were provided by the development of the four-cylinder engine, which supplies power from one or another of the cylinders on each stroke of the cycle. A further increase in power and smoothness is obtained in engines of 6, 8, 12, and 16 cylinders, which are arranged in either a straight line or two banks assembled in the form of a V.

ANSWER THE QUESTIONS:

1.What does the power plant include? 2. What is the most common type of the engines?

3. How does the four-cycle piston engine work? 4. What is a silencer? 5. What types of fuel do you know? 6. Describe the internal-combustion engine.

Дата добавления: 2015-07-15