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7. Read the texts and fill in the gaps with the following words
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7. Read the texts and fill in the gaps with the following words
• fuel • exhaust • chamber •motion • crankshaft
The engine has valves. They are intake valves and 1___________ valves. Intake valves allow the fuel to enter the combustion 2____________. Exhaust valves allow the gases to leave the combustion chamber. The valves open and close the combustion chamber where the burning of 3____________ takes place. The connecting rod connects the pistons and the 4____________. It changes the reciprocating 5____________ of pistons into the rotary motion of the crankshaft.
8. Put the words in the correct order
1. is, The temperature, very high, of the compressed air.
2. upward, moves, The piston.
3. four operations, There are, in the four-stroke cycle.
4. the burn gases, The exhaust valve, and, the piston, forces out, opens.
5. provide, What factors, the engine’s efficiency?
6. What, are, an internal combustion engine? the principle parts, of.
7. do, How many, cars, cylinders, have?
9. Read sentences a, b, c and choose the correct one
1. a. Rapid combustion of the fuel release heat.
b. Rapid combustion of the fuel releases heat.
c. Rapid combustion of the fuel is release heat.
2. a. The purpose of the exhaust stroke is drive the spent gases out.
b. The purpose of the exhaust stroke is to driven the spent gases out.
c. The purpose of the exhaust stroke is to drive the spent gases out.
3. a. At the end of the intake stroke the piston located at the bottom dead center.
b. At the end of the intake stroke the piston is locate at the bottom dead center.
c. At the end of the intake stroke the piston is located at the bottom dead center.
4. a. An engine must be water-cooled because it operates at high temperature.
b. An engine must to be water-cooled because it operates at high temperature.
c. An engine must be water-cooled because it operate at high temperature.
5. a. As the piston goes down, it creates vacuum in the cylinder.
b. As the piston go down, it creates vacuum in the cylinder.
c. As the piston goes down, it create vacuum in the cylinder.
10. Read the text and arrange the items of the plan according to the context of the text
a. Function of the valves
b. What happens during the cycle
c. Four-stroke cycle
d. Principle of operation
e. Types of cycles
f. Definition of internal combustion engine
g. What is a stroke
The Engine
The engine is the source of power that makes the car move. It is usually called an internal combustion engine because gasoline is burned within its cylinders or combustion chambers. Most automobile engines have six or eight cylinders.
The engine produces power by burning air and fuel. The fuel is stored in a fuel tank. The fuel tank is connected to a fuel pipe. The fuel pipe carries the fuel to a fuel pump. The fuel pump is connected to the carburettor. The fuel pump pumps the fuel into the carburettor. In the carburettor the fuel is mixed with air. The fuel and air are drawn into the engine cylinder by the piston. Then the fuel and air are compressed by the piston and ignited by the spark plug. They burn and expand very quickly and push the piston down. Thus, the power is produced. The burnt fuel and air are driven out of the cylinder by the piston.
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The flow of gases into and out of the cylinder is controlled by two valves. There is an inlet valve allowing fresh fuel mixture into the cylinder and an exhaust valve which allows the burnt gases to escape.
There are two basic engine operating cycles:
a) the four-stroke cycle;
b) the two-stroke cycle.
The greatest number of cars use piston engines. The four-cycle piston engine requires four strokes of the piston per cycle.
The complete four-stroke cycle comprises:
1. the intake stroke (the piston moves downwards);
2. the compression stroke (the piston moves upwards);
3. the power stroke (the piston moves downwards);
4. the exhaust stroke (the piston moves upwards).
The upper limit of the piston movement is called the top dead centre (t. d. c. ). The lower limit of piston movement is called the bottom dead centre (b. d. c. ). A stroke is the piston movement from the top dead centre to the bottom dead centre or from the bottom dead centre to the top dead centre. In other words, the piston completes a stroke each time it changes the direction of its motion.
On the intake (induction) stroke the intake valve is opened. The mixture of air and vaporized gasoline is delivered into the cylinder through the inlet valve. On the compression stroke the inlet valve is closed so that the mixture can be compressed. On the power stroke both valves (inlet and exhaust) are closed in order toraise pressure during the mixture combustion. On the exhaust stroke the exhaust valve is opened to exhaust the residual gas. In the two-cycle engines the entire cycle of events is completed in two strokes or one revolution of the crankshaft.
11. Do the test
1. Fill in the gaps in the following text with the correct form of the words
| 1. In most engines one cycle of _____________ | operate |
| 2. takes place over four ___________ of a piston, | stroke |
| 3. made in two engine _________________. | revolve |
| 4. During the _____________ stroke of the cycle, | one |
| 5. the piston ______________ away from the | move |
| 6. cylinder head while ____________ the | simultaneous |
| 7. __________ valve is opened. The motion of | take |
| 8. piston during this stroke _________ | suck |
| 9. a fuel-air charge into the _____________ | combust |
| 10 chamber. During the _______________stroke | compress |
| 11. the piston ______________ and compresses the | descend |
| 12. ______________. | mix |
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