V. Read the text about two types of engines and compare them. Use notes.
spark plug, n. – свеча зажигания exhaust outlet, n. – выпуск
fuel injector, n. - топливная форсунка fuel inlet, n. – всасывание
two-stroke engine, n. – двухтактный двигатель
four-stroke engine, n. – четырёхтактный двигатель
oil sump, n. - масляный поддон valve, n. – клапан
crankshaft, n. – коленчатый вал piston, n. – поршень
compression stroke, n. – такт сжатия
combustion stroke, n. – рабочий ход
exhaust stroke, n. – такт выпуска
induction stroke, n. – ход (такт) впуска
top dead center, n. – верхняя мёртвая точка
bottom dead centre, n. – нижняя мёртвая точка
Types of Engines
All motor vehicles have engines. The two most common types of engines for land vehicles are the petrol and the diesel engines. Petrol engines are usually lighter and smaller than diesel engines. Petrol engines are also less noisy than diesel engines. They usually go faster. On the other hand, diesel engines use less fuel and last longer than petrol engines. This is why larger vehicles such as trucks and trains use them. They are also safer than petrol engines, because there is less danger of fire.
All petrol engines have spark plugs and diesel engines do not have spark plugs. They have fuel injectors.
According to the engine cycle and configuration all internal combustion engines are divided into two stroke engines and four stroke engines.
For a four-stroke engine key parts of the engine include the crankshaft, one or two camshafts and valves. All four-stroke engines have an oil sump.
For a two-stroke engine there is an exhaust outlet and fuel inlet instead of a valve mechanism. They don’t use an oil sump because they have oil in the fuel.
I
n
both types of engines
there
are one or more cylinders and for each cylinder there is a spark
plug, a piston and a crank. The activities that take place in the
engine cylinder can be divided into four stages, which are called
strokes. The four strokes are: intake,
compression,
power and exhaust.
"Stroke" refers to the piston
movement. The upper limit of piston movement is called top
dead centre,
TDC. The lower limit of piston movement is called bottom
dead centre,
BDC. A stroke constitutes piston movement from TDC to BDC or from BDC
to TDC. In other words, the piston completes a stroke each time it
changes the direction of motion.
Section B. Car Operating Systems
Read the text “Fuel System” and explain the fuel system operation. Fuel System
In addition to the engine itself there are four separate mechanisms which are used to feed the engine. These mechanisms are the fuel system, the lubrication system, the electrical system and the cooling system. The ignition system as a part of the electrical system is used to start the car.
The
fuel system consists of a tank,
a fuel pipe,
a
pump
and a carburetor.
The fuel is stored in a fuel tank. The fuel tank is connected to a fuel pipe. The fuel pipe carries fuel to the fuel pump. This pump can be either mechanic or electric in operation. Electric pumps are situated near the tank but a mechanic pump is located near the engine because it is driven by the camshaft.
The fuel pump is connected to the carburetor. There the fuel is mixed with air. The optimum ratio of air to petrol in the fuel mixture is 15 parts of air to 1 part of petrol.
The fuel and air are compressed by the piston and they are drawn into the engine.
In the engine the fuel and
air are burnt and produce power.
Notes:
fuel, n. – топливо
fuel pipe, n. – топливопровод
pump, n. – насос
fuel tank, n. – топливный бак
camshaft, n. – кулачковый вал
petrol, n. – бензин
ratio, n. – пропорция, соотношение
piston, n. – поршень