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5. Read the text. Two sentences have been removed from it. Choose from sentences A-C the one which fits each gap (1-2). There is one extra sentence which you do not need to use
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5. Read the text. Two sentences have been removed from it. Choose from sentences A-C the one which fits each gap (1-2). There is one extra sentence which you do not need to use
A. Its purpose is to ignite compressed air-fuel mixture by means of an electric spark.
B. Each movement of the piston from one end of the cylinder to the other is called a stroke.
C. In some cases, this causes a breakdown of the engine.
One of the most important elements of an internal combustion engines is its ignition system which controls the time when the fuel is ignited and burnt. If the ignition begins either too early or too late the engine does not work properly. 1_______________________________.
The electric device which supplies the spark is a spark plug. It is placed in the cylinder head of an internal combustion engine. 2________________________________. The spark plug has an insulated wire which is connected with an ignition coil. The electricity, which it produces, should be at a very high voltage to create a good spark.
6. Read the title of the text and guess what it is about.
Read the text, choose from the list A-F the sentence which best summarizes each part (1-5). There is one extra sentence which you do not need to use
A. Increasing number of diesel-powered cars
B. Quality of diesel fuel
C. Speed of fuel injection
D. The number of injections
E. Amount of injected fuel
F. Fuel consumption
Modern Diesel Facts
1_____________________________
Fuel is injected into the combustion chamber in less than 1. 5 milliseconds (one and a half thousandth of a second) – about as long as a camera flash.
2______________________________
The smallest quantity of fuel injected is one cubic millimeter – about the same volume as the head of a pin. The largest injection quantity at the moment for automobile diesel engines is around 70 cubic millimeters.
3________________________________
If a camshaft of a six-cylinder engine is turning at 4500 rpm, the injection system has to control and deliver 225 injection cycles per second.
4________________________________
On a demonstrative drive, a Volkswagen 1-liter diesel-powered car used only 0. 89 liters of fuel in covering 100 kilometers – making it probably the most fuel-efficient car in the world. Bosch’s high-pressure fuel injection system was one of the main factors behind the prototype’s extremely low fuel consumption. Production record-breakers in fuel economy include the Volkswagen Lupo 3L TDI and the Audi A2 3L 1. 2 TDI with standard consumption figures of 3 liters of fuel per 100 kilometers. Their high-pressure diesel injection systems are also supplied by Bosh.
5_______________________________
In 2001 nearly 36% of newly registered cars in Western Europe had diesel engines. Austria leads the league table of registrations of diesel-powered cars with 66%, followed by Belgium with 63% and Luxemburg with 58%. Germany, with 34. 6% in 2001, was in the middle of the league table. In 1996, diesel-powered cars made up only 15% of the new car registrations in Germany.
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7. Read the text, divide it into paragraphs and give a heading to each paragraph. Which of the linking words in bold help you understand that the author a) adds some new information? b) explains the reason? c) expresses contrast; d) shows the effect
The Two-Stroke Cycle
The two-stroke engine is simpler mechanically than the four-stroke engine. The two-stroke engine delivers one power stroke every two strokes instead of one every four, thus it develops more power with the same displacement, or can be lighter and yet deliver the same power. For this reason, it is used in lawn mowers, chain saws, small automobiles and motorcycles. However, there are several disadvantages that restrict its use. Since there are twice as many power strokes during the operation of a two-stroke engine as there are during the operation of a four-stroke engine, the engine tends to heat up more, and thus is likely to have a shorter life. Also , in the two-stroke engine lubricating oil must be mixed with the fuel. This causes a very high level of hydrocarbons in its exhaust, unless the fuel-air mixture is computer calculated in order to maximize combustion.
8. Read four texts (1-4) and the titles. Choose from the list A-E the title which best summarizes each text. There is one extra title
A. Necessity of special type of fuel
B. Types of fuel injection
C. Operation of a six-stroke engine
D. Exhaust system
E. Advantages of the six-stroke engine
| 1. The six-stroke engine is similar to a regular internal combustion engine in design. The modification goes in the cylinder head, for which two supplementary chambers – a combustion chamber and an air preheating chamber – have been provided. The combustion occurs in a totally enclosed chamber, thereby increasing the thermal efficiency. The advantages include reduction in fuel consumption by at least 40%, two expansion strokes (work) in six strokes, multi-fuel usage capability, and a dramatic reduction in pollution. |
| 2. A new six-stroke engine was invented by a 75-year-old mechanic Bruce Crower, a veteran of the racing industry and the owner of a company which produces engine parts. His idea was to use the waste heat energy of combustion engines, and one day in 2004 he awoke with an idea which he immediately set to work. His addition to the internal combustion engine design is simple in principle, yet a stroke of genius. After the exhaust cycle out of the chamber his design injects ordinary water. Inside the extremely hot chamber, the water immediately turns to steam – expanding to 1600 times its volume – which forces the piston down for a second power stroke. Another exhaust cycle pushes the steam out of the chamber, and then the six-stroke cycle begins again. |
| 3. Higher compression ratios produce more power, up to a point. The more you compress the air-fuel mixture, however, the more likely it is to spontaneously burst into flame (before the spark plug ignites it). Higher-octane gasoline prevents this sort of early combustion. That is why high-performance cars generally need high-octane gasoline – their engines are using higher compression ratios to get more power. |
| 4. The fuel system pumps gas from the gas tank and mixes it with air so that the proper air-fuel mixture can flow into the cylinders. Fuel is delivered in three common ways: carburetion, port fuel injection and direct fuel injection. In carburetion, a device called a carburetor mixes gas into air ad the air flows into the engine. In a fuel-injected engine, the right amount of fuel is injected individually into each cylinder wither right above the intake valve (port fuel injection) or directly into the cylinder (direct injection). |
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9. Read the text. For questions 1-6 choose the answer a, b or c, which you think fits best according to the text
Cylinders
Internal combustion engines can contain any number of cylinders with numbers between one and twelve being common, though as many as 30 have been used. Having more cylinders in an engine provides two advantages: First, the engine can have a larger displacement (the total volume of fuel passed through the cylinder) with smaller individual reciprocating masses (that is, the mass of each piston can be less) thus making a smoother running engine (since the engine vibrates as a result of the piston moving up and down). Second, with a greater displacement and more pistons, more fuel can be combusted and there can be more combustion events (that is, more power strokes) in a given period of time. This
means that such an engine can generate more torque than a similar engine with fewer cylinders. The disadvantage of having more pistons is that the engine will weigh more and tend to generate more internal friction as the greater number of pistons rub against the inside of their cylinders. This decreases fuel efficiency and also decreases the power of the engine. For high performance gasoline engines using current materials and technology (such engines found in modern automobiles), the best solution is 10 or 12 cylinders, after which addition of cylinders makes the performance and efficiency worse, although exceptions such as the W-16 engine from Volkswagen exist.
Most car engines have four to eight cylinders, with some high-performance cars having ten, twelve, or even sixteen, and some very small cars and trucks having two or three. In previous years some large cars, such as DKW and Saab 92, had two cylinder, two-stroke engines. Motorcycles commonly have from one to four cylinders, with a few high-performance models having six.
1. Internal combustion engines can contain from one to __________________cylinders.
a) twelve
b) any number of
c) thirty
2. Great number of cylinders have _______________________.
a) advantages
b) disadvantages
c) both advantages and disadvantages
3. The engine having more cylinders can generate ______________torque than the engine with fewer cylinders.
a) the same
b) more
c) less
4. High performance may be provided by engines having _______________ cylinders.
a) 16
b) 30
c) 10-12
5. Nowadays most cars have _________________ cylinders.
a) 10-12
b) 16
c) 4-8
6. High performance motorcycles have ___________________cylinders.
a) 1
b) 6
c) 4
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