The internal combustion engine is called so because fuel is burned directly inside the engine itself. Most automobile engines work on a 4-stroke cycle. A cycle is one complete sequence of 4 strokes of the piston in the cylinder. The operating cycle of the four-stroke petrol engine includes: inlet stroke (intake valve opens), compression stroke (both valves closed), power stroke (both valves closed), exhaust stroke (exhaust valve is opened).
To describe the complete cycle, let's assume that the piston is at the top of the stroke (top dead center) and the inlet and the exhaust valves are closed. When the piston moves down the inlet valve opens to intake a charge of fuel into the cylinder. This is called the inlet (intake) stroke. On reaching the lowest position (bottom dead center) the piston begins to move upward into the closed upper part on the cylinder, (he inlet valve is closed and the mixture is compressed by the rising piston. This is called the compression stroke. As the piston again reaches the top dead center the spark plugs ignite the mixture, both valves being closed during its combustion. As a result of burning mixtures the both valves being closed during its combustion. As a result of burning mixtures the gases expand and great pressure makes the piston move back down the cylinder. This stroke is called the power stroke. When the piston reaches the bottom of its stroke, the exhaust valve is opened, pressure is released, and the piston again rises. It lets the burnt gas flow through the exhaust valve into the atmosphere. This is called the exhaust stroke which completes the cycle. So the piston moves in the cylinder down (intake stroke), up (compression stroke), down (power stroke), up (exhaust stroke).
The heat released by the fuel is transformed into work so that the reciprocating movement of the pistons is converted into rotary movement of a crankshaft by means of connecting rods.
1 -intake 2 - compression 3 - power 4 - exhaust
. 1. Principle of Operation of the Four-Stroke Petrol Engine
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1. intake - 3. power
2. compression 4. exhaust
The exercises to be done after reading the text
5. , , , , .
6. .
1. Why is the engine called the internal combustion engine?
2. What stroke is called the inlet one?
3. What is a compression stroke?
4. What takes place in the cylinder on power stroke?
5. What takes place on the exhaust stroke?
6. By means of what is the reciprocating movement of the pistons converted into rotary movement of a crankshaft?
1.It is called so because the fuel (the mixture) is burned
a)directly inside the engine;
b)outside the engine.
2. The inlet stroke is called so because during moving down the piston
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a) the inlet valve opens to intake a charge of fuel into the cylinder;
b)the inlet valve is closed and the mixture is compressed.
3.The compression stroke is a stroke..
a) when the inlet valve opens to intake a charge of fuel into the cylinder;
b) when the inlet valve is closed and the mixture is compressed.
4. On power stroke.
a)the spark plugs ignite the mixture, both valves are closed during its combustion;
b)the exhaust valve is opened and the residual gas flows through the exhaust valve into the atmosphere.
5.On the exhaust stroke...
a)the spark plugs ignite the mixture, both valves are closed during its combustion;
b)the exhaust valve is opened and the residual gas flows through the exhaust valve into the atmosphere.
6. It is done...
a)by means of pistons;
b)by means of the connecting rods.
7. , .
1.The internal combustion engine is called so because fuel is burned
a)outside the engine;
b)inside the engine.
2.On the inlet stroke..............
a)the intake valve opens;
b)the intake valve is closed;
c)the intake and the exhaust valves are closed.
3. On the compression stroke.......
a). the intake valve opens;
b).the intake valve is closed;
c).the intake and the exhaust valves are closed.
4. On the power stroke..
a).the intake valve opens;
b)the intake valve is closed;
c)the intake and the exhaust valves are closed.
5. On the exhaust stroke.....
a).the exhaust valve opens;
b).the intake valve is closed;
c).the intake and the exhaust valves are closed.
8. , .
DIALOGUE Tracing a Fault
Nick: Peter, I know you are a good driver. I would like you to have a
look at my car.
Peter: What's wrong with your car?
N.: I don't know.
P.: Let me have a look. When did you have your plugs checked?
N.: Three days ago. I thought I had run out of fuel but the tank is half full.
P.: The carburettor is in order but the engine is misfiring. I guess
the battery has run down. It needs recharging.
N.: Too bad.
P.: Don't get upset about it. It won't take you long to have your
battery recharged.
N.: Do you really think so?
P.: I am sure of it. I advise you to have the engine greased.
N.: I'll follow your advice. Thank you, Peter.
P.: Don't mention it, Nick. I'm very sorry I couldn't help you.
N.: Well, you helped me to find the fault. Thanks a lot. Good-bye.
P.: See you later.
9. , .
1. - , .
-Let me trace the fault.
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-Yes, I am. I have been driving for fifteen years now. May be you have run out of fuel?
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-When did you have your plugs checked?
-. .
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-Good idea. They will have the car fixed.
2.- ?
-Last month. The engine is in good condition now. It was well
greased.
-. . (The brakes are slack.) (The battery has run down.)
-It can be easily done.
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3.- ?
-I want a second-hand car. Could you help me?
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-I hear there are good cars on sale 42nd Street.
- . .
-Good idea. If I choose a car there, I won't have to bother any more.
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10. , .
DIALOGUE
At the Repairing Shop
Client: Good afternoon! Can you help me? There is something wrong with the engine.
Master: Hi! What is wrong with it?
.: I don't know. It wouldn't start. Maybe the pistons and valves are in disorder.
M.: Let's have a look! Well, they are quite right.
C.: And what about the crankshaft, or electric spark plugs. I know absolutely nothing about the operating cycle of the engine.
Just a moment. Don't worry! We shall check up all units and how they work together.
Some time later
M.: My God! There is no petrol in the tank. How can you move drive?
C.: Really? Oh, I have forgotten to fill in the tank! I beg your pardon to trouble you!
M.: No trouble, at all. You are welcome!
1. as a result -
2. assume
3. bottom dead center
4. burn
5. by means of 6. charge of fuel - 7. combustion 8. combustion chamber
9. compression stroke ()
10. connecting rod
11. convert 12. crankshaft 13. cylinder
14. descend - , ()
15. describe
16. diesel engine
17. directly -
18. don't get upset
19. engine
20.exhaust stroke
22.follow sb's advice - --.
23. four-stroke cycle
24.fuel injection
25.have a look
26.heat
27.I guess
28.ignite
29.ignition
30.in order ( )
31.intake (inlet) stroke
32.internal combustion 33.engine
34.mixture
35.operating cycle
36. petrol engine
37.piston -
38.power stroke - 39.pressure
40.reach
41.recharge ()
42.reciprocating movement - -
43.residual gas -
44.rise
45.rotary movement
46.run down - ( )
47.run out of fuel
48.spark plug 49.stroke ()
50.tank
51.top dead center -
52.trace the fault - () 53.valve
Unit Four
Text: Chassis
Dialogue: Transmission Mechanism
