Text A. Classification. Fuel System

There are numerous types of motorcars. These are motorcars with carburettor engines and motorcars with diesel engines. Every motorcar has the following components: body, engine, power train, and chassis.

There are many types of automotive power plants. They may be classified in a number of ways: by the number and arrangement of pistons and cylinders, by the means of ignition, or by the type of cooling system.

The engine is the power plant of the vehicle. In general, internal combustion engines are used operating with some fuel (petrol or gas, diesel oil, benzol). Depending on their combustion process, the engines are fundamentally classified as carburettor engines and diesel engines. Sometimes the carburettor engines are called light-oil engines and the diesel engines are called heavy-oil engines.

Another difference results from the working method of the internal- combustion engine. A difference is made between four-stroke cycle engines and two-stroke cycle engines. The internal-combustion engine, which obtains its power from the expansion of gases, is used to propel most modern automobiles. A fuel, usually gasoline, is burned with air to create the expanding gas.

When a fuel is burned in air, the resulting hot gas tries to expand, generating a force that can be used to move a piston in a cylinder, as in the automobile engine, or to drive the blades of a turbine. In either case, because the combustion takes place within it, the engine is called an internal-combustion engine.

Modern transportation relies heavily upon internal-combustion engines. All airplanes and most automobiles, ships, and railroad locomotives are powered by them. They also power lawn-mowers, chain saws, air compressors, and other power tools.

The two most common internal-combustion engines are the gasoline and the diesel engines. The first is used in most automobiles. The diesel engine burns a heavier fuel and finds its primary application in larger vehicles such as ships, locomotives, heavy trucks, and buses, though it is also used in some automobiles. Almost any liquid or gaseous fuel, however, can be used in an internal-combustion engine, including gasoline-alcohol mixtures called gasohol, alcohol, methane gas, and compressed coal gas.

The fuel system of an automobile includes the fuel tank, fuel pump, one or more carburettors, and connecting fuel lines. An air cleaner is mounted on top of the carburettor to remove dust and dirt from incomingair that is to be mixed with fuel and used for combustion. Most carburettors have at least two fuel passages, called jets, from the float chamber to the mixing chamber. The first jet provides fuel for idling and low speeds; the second provides fuel for higher speeds. Passages called intake manifolds transmit the air-fuel mixture to the cylinders. Some engines, and all diesel engines, use fuel injection, a system whereby a carefully measured amount of fuel is forced into the combustion chamber at high pressure.

Comprehension Check – 1

Date: 2015-12-18; view: 1367