Text B. Internal Combustion Engine

Анна Валерьевна Герасимова

Екатерина Юрьевна Джандалиева

Елена Александровна Литвинова

Надежда Владимировна Стрепетова

Методические указания по английскому языку для студентов автотранспортного факультета по теме «Моя специальность»

Темплан 2012 г. Поз. № .

Подписано в печать __________2012 г. Формат 60х84 1/16.

Бумага газетная. Печать офсетная. Усл. печ. л. 1.

Тираж 100 экз. Заказ ______

Волгоградский государственный технический университет.

400131, Волгоград, пр. им. Ленина, 28.

Unit 1. Engine.

Text A. Types of Engine.

Automotive production has always required a wide range of energy-conversion systems such as electric, steam, solar, turbine, rotary, and different types of piston-type internal combustion engines. The reciprocating-piston internal-combustion system, operating on a four-stroke cycle, has been the most successful for automobiles, while diesel engines are widely used for trucks and buses.

The gasoline engine was originally selected for the automobile due to its flexibility over a wide range of speeds. Also, the power developed for a given weight engine was reasonable; it could be produced by economical mass-production methods; and it used a readily available, moderately priced fuel i.e. gasoline. Reliability, compact size, and range of operation later became important factors.

In today’s world, there has been a growing emphasis on the pollution producing features of automotive power systems. This has created new interest in alternate power sources and internal-combustion engine refinements that were not economically feasible in prior years. Although a few limited-production battery-powered electric vehicles have appeared from time to time, they have not proved to be competitive owing to costs and operating characteristics. However, the gasoline engine, with its new emission-control devices to improve emission performance, has not yet been challenged significantly.

The first half of the twentieth century saw a trend to increase engine horsepower, particularly in the American models. Design changes incorporated all known methods of raising engine capacity, including increasing the pressure in the cylinders to improve efficiency, increasing the size of the engine, and increasing the speed at which power is generated. The higher forces and pressures created by these changes created engine vibration and size problems that led to stiffer, more compact engines with V and opposed cylinder layouts replacing longer straight-line arrangements. In passenger cars, V-8 layouts were adopted for all piston displacements greater than 4 litres. Smaller cars brought about a return a to smaller engines, the four- and six-cylinder designs rated as low as 80 horsepower, compared with the standard-size V-8 of large cylinder bore and relatively short piston stroke with horsepower ratings in the range from 250 to 350.

The automobile engines from Europe had a bigger range, varying from 1 to 12 cylinders with corresponding differences in overall size, weight, piston displacement, and cylinder bores. Four cylinders and horsepower ratings from 19 to 120 were followed in a majority of the models. Several three-cylinder, two-stroke-cycle models were built while most engines had straight or in-line cylinders. There were several V-type models and horizontally opposed two- and four-cylinder makes too. Overhead camshafts were frequently employed. The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and '80s showed an increased interest in improved fuel economy which brought in a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency.

Exercise 1. Match the descriptions of engine layouts with the diagrams.

Text B. Internal Combustion Engine.

Fuel combustion takes place in a confined space, and produces expanding gases that are used to provide mechanical power. The four-stroke reciprocating engine that is used in automobiles is the most common internal-combustion engine. In this mechanism, mechanical power is supplied by a piston that is fitted inside a cylinder. On a downstroke of the piston, the first stroke, fuel that has been mixed with air (by fuel injection or using a carburetor) enters the cylinder through an intake valve; the piston moves up to compress the mixture at the second stroke. At ignition, the third stroke, a spark from a spark plug ignites the mixture, forcing the piston down; in the exhaust stroke, an exhaust valve opens to vent the burned gas as the piston moves up. The piston is connected to a crankshaft by means of a rod. The reciprocating (up and down) movements of the piston rotate the crankshaft, which is connected by gearing to the drive wheels of the automobile. The ignition spark is provided by an electrical system whose power comes from a battery. This also supplies power to the starting system, which is a small electric motor that turns the crankshaft until the engine takes over. Water circulating around the cylinders cools the engine, and lubrication occurs motor oil that is driven around the moving engine parts by an oil pump. Small vehicles like lawn mowers and motorcycles use the two-stroke engine, which combines intake and compression in the first stroke and power and exhaust in the second.