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2. Read the text and insert the missing words
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2. Read the text and insert the missing words
| bottom, crankshaft, dead, compression, strokes |
Engines operate on cycles. There are four 1 __________ of the piston in one cycle of engine operation. There are two downward strokes toward the crankshaft and two upward strokes away from the 2___________. When the piston is at the end of the stroke away from the crankshaft this is the top 3____________ centre (TDC). When the piston is at the end of the downward stroke (toward the crankshaft) this is the 4___________ dead centre (BDC). The piston’s movement from TDC to BDC is an engine stroke. The four strokes in a cycle of the internal combustion engine are intake, 5____________, power and exhaust.
UNIT XI. DIESEL ENGINE. FOUR-STROKE CYCLE
Vocabulary: rise/raise
Rise- rose-risen – вставать, подниматься
Raise - поднимать
1. Which alternative is possible in each sentence?
| The sun rises/raises in the East and sets in the West. Rise/raise your hand if you want to answer |
2. Choose the correct verb
1. She read the telegram (rose / raised) and half ran towards the door.
2. May I (rise / raise) my glass to your health, madam?
3. He is very weak after the flu. He can hardly (rise / raise) from the bed.
4. He (rises / raises) his head and sees that a visitor is entering his office.
5. Early to bed and early to (rise / raise) makes a man healthy, wealthy and wise.
6. Prices tend to (rise / raise) this time of the year.
7. When a gas is compressed, its temperature (rises / raises).
8. Air is drawn into the cylinder and compressed by the (raising/rising) piston.
9. If you (rise / raise) the amount of fuel and air through a diesel engine, it will increase its operating temperature.
10. Gas temperature in the cylinder may (raise / rise) up to 2500°C.
11. As the piston reaches the end of the suction stroke the air inlet valve closes and the piston begins to (rise / raise) on the second stroke.
12. During the exhaust stroke the piston (raises / rises) to expel gases, then the inlet valve opens, exhaust valve closes.
13. When the air is compressed, its temperature (rises / raises).
14. On the power stroke both valves (inlet and exhaust) are closed in order to (rise / raise) pressure during the mixture combustion.
Talking about temperature
| Temperature is measured in: - degrees Celsius (°C) - degrees Fahrenheit (°F) 32°F is 0°C |
3. Read and translate the sentences. Guess the meaning of the underlined words
1. At the end of the compression stroke the air temperature is about 1, 000°F. The burning of fuel raises the temperature to about 3, 000°F.
2. The ignition of the fuel requires that the fuel be highly compressed, which produces a temperature of about 1, 000°F.
3. Components of gasoline have ignition point from about 100°F to 400°F.
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4. The engine metal may reach 300°C.
5. Even hot exhaust gases of up to 800°C can be cooled to a desired (желательный) low temperature.
6. When the temperature of coolant rises to between 180 and 195°F (82-91°C), the thermostat starts to open, allowing fluid (жидкость) to flow through the radiator.
7. By the time the coolant reaches 200-218°F (93-100°C), the thermostat is open completely.
8. Gas temperature in the cylinder may reach 4500°F (2500°C).
Grammar. Active voice and Passive voice
4. Look at the verbs in bold, state if they are Active or Passive Voice
Read the text and choose the answer a), b), c) which you think fits best according to the text
Diesel Engine
A diesel engine is a machine which produces power by burning oil in air which has been quickly compressed to a high pressure by a piston moving in a closed cylinder. As the piston moves from the bottom dead center upwards it compresses the air above it into a smaller and smaller volume. If the final volume of the air is one twenty-fifth of its original volume, the engine is said to have a compression ratio (коэффициент сжатия) of 25.
When the piston is at the top dead center, the air in the cylinder is highly compressed and is also very hot (about 3000°F). Oil is injected into the hot air. The oil ignites instantaneously. The heat of its compression raises the temperature of the air still higher and so the pressure of the closed air is very much increased also.
The piston is pushed down again violently. This second stroke of the piston is called the power stroke.
After reaching the bottom of its working stroke the piston begins to rise again.
The diesel engine produces power by burning oil in air which
a) has been rapidly compressed
b) has been slowly squeezed
c) hadn’t been compressed
1. The engine is said to have a compression ratio of 25 if the final volume is
a) 1/25 of its original weight
b) 0, 04 of its original volume
c) 0, 5 of its original temperature
2. The fuel is injected into
a) highly compressed cold liquid
b) a little squeezed hot liquid
c) highly squeezed hot air
3. The pressure and temperature of the compressed air
a) decreases
b) rises
d) raises
4. During the power stroke the piston
a) is pushed upward
b) moves downward
c) rises
5. Read the following pairs of sentences and state if the predicates are in Active or Passive voice
1. a) Like gasoline engines, diesels mix air and fuel into a combustible mixture.
b) Air and fuel are mixed into a combustible mixture.
2. a) As the piston compressed the air, it became hotter.
b) As the air was compressed, it became hotter.
3. a) The differences between diesels and gasoline engines are due to the ways the engines have been used.
b) The differences between diesels and gasoline engines are due to the ways people have used them.
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