VIII. Skim text 2B and get ready to speak about how internal combustion engines work.

Text 2B

Internal Combustion Engine

The purpose of a gasoline car engine is to convert gasoline into motion so that your car can move. Currently the easiest way to create motion from gasoline is to burn the gasoline inside an engine. Therefore, a car engine is an internal combustion engine – combustion takes place internally.

An internal combustion engine (ICE) is a heat engine where the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine the expansion of the high-temperature and high-pressure gases produced by combustion applys direct force to some component of the engine. The force is applied typically to pistons, turbine blades, or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy.

There are different kinds of internal combustion engines. Diesel engines are one form and gas turbine engines are another. There are also HEMI engines, rotary engines and two-stroke engines. Each has its own advantages and disadvantages.

Let's look at the internal combustion process in more detail. The principle behind any reciprocating internal combustion engine: if you put a tiny amount of high-energy fuel (like gasoline) in a small, enclosed space and ignite it, an incredible amount of energy is released in the form of expanding gas.

Almost all cars currently use what is called a four-stroke combustion cycle to convert gasoline into motion. The four-stroke approach is also known as the Otto cycle, in honor of Nikolaus Otto, who invented it in 1867. The four strokes are:

- intake stroke;

- compression stroke;

- combustion stroke;

- exhaust stroke.

Here's what happens as the engine goes through its cycle:

1. The piston starts at the top, the intake valve opens, and the piston moves down to let the engine take in a cylinder-full of air and gasoline. This is the intake stroke. Only the tiniest drop of gasoline needs to be mixed into the air for this to work.

2. Then the piston moves back up to compress this fuel/air mixture. Compression makes the explosion more powerful.

3. When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline. The gasoline charge in the cylinder explodes, driving the piston down.

4. Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe.

Now the engine is ready for the next cycle, so it intakes another charge of air and gas.

The motion that comes out of an internal combustion engine is rotational. In an engine the linear motion of the pistons is converted into rotational motion by the crankshaft. The rotational motion is nice because we plan to turn (rotate) the car's wheels with it anyway.

Now let's look at all the parts that work together to make this happen, starting with the cylinders.

Basic Engine Parts

The core of the engine is the cylinder, with the piston moving up and down inside the cylinder. The engine described above has one cylinder. That is typical of most lawn mowers, but most cars have more than one cylinder (four, six and eight cylinders are common). In a multi-cylinder engine, the cylinders usually are arranged in one of three ways: inline, V or flat (also known as horizontally opposed or boxer).

Different configurations have different advantages and disadvantages in terms of smoothness, manufacturing cost and shape characteristics. These advantages and disadvantages make them more suitable for certain vehicles.

Let's look at some key engine parts in more detail.

Spark plug

The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark must happen at just the right moment for things to work properly.

Valves

The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that both valves are closed during compression and combustion so that the combustion chamber is sealed.

Piston

A piston is a cylindrical piece of metal that moves up and down inside the cylinder.

Piston rings

Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes:

- they prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion;

- they keep oil in the sump from leaking into the combustion area, where it would be burned and lost.

Most cars that «burn oil» and have to have a quart added every 1,000 miles are burning it because the engine is old and the rings no longer seal things properly.

Connecting rod

The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates.

Crankshaft

The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the-box does.

Sump

The sump surrounds the crankshaft. It contains some amount of oil, which collects in the bottom of the sump (the oil pan).

Summary writing.

Activity 1. Rearrange and write the following sentences in a paragraph that summarizes the text:

1. The expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine.

2. Each has its own advantages and disadvantages.

3. The force is applied typically to pistons, turbine blades, or a nozzle.

4. An internal combustion engine (ICE) is a heat engine where the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit.

5. Currently the easiest way to create motion from gasoline is to burn the gasoline inside an engine.

6. The purpose of a gasoline car engine is to convert gasoline into motion so that your car can move.

7. This force moves the component over a distance, transforming chemical energy into useful mechanical energy.

8. There are different kinds of internal combustion engines: diesel engines, gas turbine engines, HEMI engines, rotary engines and two-stroke engines.

9. Therefore, a car engine is an internal combustion engine – combustion takes place internally.

Activity 2. Translate into English using the dictionary:

Двигун – одна з основних складових автомобіля. Ривок в історії створення автомобілів стався завдяки винаходу двигуна внутрішнього згоряння.

Спроби створити пристрій, подібний двигуну внутрішнього згоряння, почалися з 18 століття. Створенням пристрою, який міг би перетворювати енергію палива в механічну, займалися багато винахідників: брати Ньєпс з Франції, які придумали прилад, паливом для якого повинен був використовуватися вугільний пил; Ж.Ж. Етьєна Ленуар, який створив перший успішний двигун з карбюратором і іскровим запалюванням (1858).

У 1864 році був винайдений одноциліндровий карбюраторний двигун, що працює від згоряння нафтопродуктів (Зігфрід Маркус).

У 1873 році ще один інженер – Джордж Брайтон – зміг сконструювати 2-х циліндровий двигун. Спочатку він працював на гасі, а пізніше на бензині.

У 1876 році відбувся ривок в індустрії створення двигунів внутрішнього згоряння. Ніколас Отто вперше створив двигун, який ефективно перетворював енергію палива в механічну енергію.

1885 році Готтліб Даймлер зміг не тільки винайти, але і запустити у виробництво прототип сучасного газового двигуна – з вертикально розташованими циліндрами і карбюратором. Це був перший компактний двигун, який до того ж сприяв розвитку пристойної швидкості переміщення.

Паралельно з Даймлером над створенням двигунів і автомобілів працював Карл Бенц.

У 1903 році підприємства Даймлера і Бенца об'єдналися, давши початок повноцінному підприємству автомобілебудування. Так почалася нова ера, яка послужила подальшому вдосконаленню двигунів внутрішнього згоряння.