Internal-Combustion Engine

(1) Internal-Combustion Engine is any type of machine that obtains mechanical energy directly from the expenditure of the chemical energy of fuel burned in a combustion chamber that is an integral part of the engine. Four principal types of internal-combustion engines are in general use: the Otto-cycle engine, the diesel engine, the rotary engine, and the gas turbine.

(2) The Otto-cycle engine, named after its inventor, the German technician Nikolaus August Otto, is the familiar gasoline engine used in automobiles and airplanes; the diesel engine, named after the French-born German engineer Rudolf Christian Karl Diesel, operates on a different principle and usually uses oil as a fuel. It is employed in electric-generating and marine-power plants, in trucks and buses, and in some automobiles. Both Otto-cycle and diesel engines are manufactured in two-stroke and four-stroke cycle models.

(3) The efficiency of a modern Otto-cycle engine is limited by a number of factors, including losses by cooling and by friction. In general, the efficiency of such engines is determined by the compression ratio of the engine. The compression ratio (the ratio between the maximum and minimum volumes of the combustion chamber) is usually about 8 to 1 or 10 to 1 in most modern Otto-cycle engines. Higher compression ratios, up to about 15 to 1, with a resulting increase of efficiency, are possible with the use of high-octane antiknock fuels. The efficiencies of good modern Otto-cycle engines range between 20 and 25 percent - in other words, only this percentage of the heat energy of the fuel is transformed into mechanical energy.

(4) The efficiency of the diesel engine, which is in general governed by the same factors that control the efficiency of Otto-cycle engines, is inherently greater than that of any Otto-cycle engine and in actual engines today is slightly more than 40 percent. Diesels are, in general, slow-speed engines with crankshaft speeds of 100 to 750 revolutions per minute (rpm) as compared to 2500 to 5000 rpm for typical Otto-cycle engines. Some types of diesel, however, have speeds up to 2000 rpm. Because diesels use compression ratios of 14 or more to 1, they are generally more heavily built than Otto-cycle engines, but this disadvantage is counterbalanced by their greater efficiency and the fact that they can be operated on less expensive fuel oils.

(Microsoft Encarta, 2008)

1. Определите, является ли утверждение:

The Otto-cycle engine is named after the Dutch technician who created it.

a) истинным

b) ложным

c) в тексте нет информации

2. Определите, является ли утверждение:

Internal-combustion engine is one of the most important inventions of the mid- to late 1800s.

a) в тексте нет информации

b) ложным

c) истинным

3. Определите, является ли утверждение:

The diesel engine is more effective than Otto-cycle engine.

a) ложным

b) в тексте нет информации

c) истинным

4. Определите, является ли утверждение:

The compression ratio is the ratio between the minimum and maximum volumes of the combustion chamber.

a) ложным

b) истинным

c) в тексте нет информации

5. Укажите, какой части текста (1, 2, 3, 4) соответствует следующая информация:

The rotary engine is one of the four types of internal-combustion engines.

a) 4

b) 3

c) 1

d) 2

6. Укажите, какой части текста (1, 2, 3, 4) соответствует следующая информация:

The diesel engine uses oil as a fuel.

a) 3

b) 2

c) 4

d) 1

7. Ответьте на вопрос:

What is the average crankshaft speed of diesels?

a) 100 to 750 rpm

b) 2500 to 5000 rpm

c) up to 2000 rpm

d) 500 rpm

---

Дата добавления: 2015-10-30