 |
6. Read the following sentences and choose the correct verb form
|
|
|
|
6. Read the following sentences and choose the correct verb form
1. During the intake stroke the piston
a) descends b) is descended
2. During this stroke the inlet valve … open by the valve mechanism.
a) holds b) is held
3. Then the piston … on the compression stroke with both valves closed.
a) is ascended b) ascends
4. The piston … the charge into the smaller space of the combustion chamber.
a) is forced b) forces
5. In the combustion chamber the charge … by an electric spark at the end of the stroke.
a) is ignited b) ignites
6. During the power stroke both valves … and gas pressure acts on the piston.
a) close b) are closed
7. The exhaust stroke then completes the cycle: the ascending piston … the spent products of combustion through the exhaust valve.
a) forces b) is forced
8. One cycle … four strokes of the piston and two revolutions of the crankshaft.
a) requires b) is required
7. Complete the sentences using one of the verbs in the correct form (each verb may be used more than once)
| Call, produce, take, use, squeeze |
A diesel engine is a machine which 1___________power by burning oil in a body of air which 2___________ to a high pressure by a moving piston. Since it is a machine that 3___________ power, it 4___________an engine, and since the burning or combustion 5___________place within the engine itself, it 6____________ an internal combustion engine. A steam engine 7___________ steam made by burning fuel outside the engine. That is external combustion.
Talking about pressure
8. Read the explanations in the boxes
|
| Pressure is measured in different units. Some companies use Imperial units (USA system) and some companies use International Standard Metric Units (IS). Imperial units measure the force in pounds, and the area in square inches. This gives a pressure in pounds (фунт) per square inch (дюйм) (psi or lb. per sq. in). International Standard Metric Units measure area in square meters and force in newtons. This gives a pressure measurement called pascal (Pa), which is newtons per square meter. Because this is a very small unit, the kilopascal (kPa) is often used. To convert psi to Pa, the following formula is used: 1psi=6895 Pa. |
Talking about speed
| Units of speed measurement are kilometers per hour (kph or km/h), miles per hour (mph), revolutions per minute (rpm). |
9. Read and translate the sentences paying attention to the abbreviations
1. The first downstroke of the piston draws in air, which is then compressed on the upstroke to about 500 lb. per sq. in. (35 kg per sq cm).
2. High-speed (1200 rpm and greater) engines are used to power trucks, buses and tractors.
|
|
|
3. Formula One driver Jenson Button was arrested driving a diesel-powered BMW coupe at 230 km/h (about 140 mph).
4. This method of igniting the fuel requires that the air be compressed to a pressure of about 500 lb. per sq. in., which produces a temperature of about 1, 000°F.
5. The diesel engine draws a full charge of air, about 18 lb. per each pound of fuel at full load and about 100 lb. per pound of fuel when idling.
6. The crankshaft speed is from 1, 200 to 4, 000 rpm and seldom exceeds 3, 000 rpm.
7. If the camshaft (распределительный вал) of a six-cylinder engine is turning at 4500 rpm, the injection system has to control and deliver 225 injection cycles per second.
8. The piston starts on an upward stoke, called compression stroke, compressing the charge of pure air a pressure of between 350 and 450 lb. per sq. in.
9. As the air molecules are compressed the air temperature increases dramatically to about 1000° F (537° C).
10. Diesels are in general slow-speed engines with crankshaft speeds of 100 to 750 rpm as compared to 2500 to 5000 rpm for typical Otto-cycle engines.
11. The best working temperature for an engine is the one which heats the
coolant at a point near the thermostat housing to about 80-85°C (176-185°F).
10. Read the words in the box and guess their meanings
| Constant, efficiency, actual, balance, counterbalance, vertical |
11. Learn the following words
advantage – преимущество
disadvantage - недостаток
to govern - регулировать
nozzle - форсунка
ratio – соотношение, коэффициент
12. Choose the correct alternative. Guess the meaning of the underlined words
1. An important component of a diesel engine is a _______________.
a) govern b) governor c) governs
2. Of all internal combustion engines, the diesel engine is the most _______________, which means it can obtain the greatest amount of mechanical energy from fuel.
a) efficient b) efficiency c) efficiently
3. The diesel engine differs from the gasoline engine in that the ignition of fuel is _______________ by compression of air in its cylinders instead of by a spark.
a) cause b) causes c) caused
4. The relationship between the volume of the cylinder when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke is called ____________________ ratio.
a) injection b) compression c) volume
5. Diesel oil is forced in the form of a fine spray through a ___________ directly into the combustion chamber.
a) cylinder head b) nozzle c) crank
6. The gas turbine engine is another form of an internal combustion engine, but it has the _________________ of high manufacturing costs.
a) advantage b) disadvantage
7. Internal combustion engines are more efficient, smaller and less expensive than external combustion ones. These _______________ make them very popular.
a) advantages b) disadvantages
|
|
|
8. A spray ______________or fuel injector is needed to deliver the oil for burning in the form of a finely divided spray.
a) nozzle b) governor c) chamber
9. There is an injector or ____________ for every cylinder.
a) ratio b) nozzle c) pump
10. The diesel engine, which must operate under a large range of speed conditions, must have a _______________ system which can control the injection4 starting point and the injection period.
a) nozzle b) governor c) piston
11. Diesel engines have a higher thermal efficiency thus developing more power in ______________ to the amount of fuel used.
a) ratio b) nozzle c) nozzle
|
|
|
