The importance of the diesel engine
Knowing about the invention of diesel engines
Of all internal combustion engines, the diesel typ can extract the most energy from fuel. It obtains nearly twice as much work as a gasoline engine from a comparable amount of fuel. It is several times more efficient that a steam engine, but this efficiency appears only in a narrow range of speeds. The diesel is too heavy for most automobiles and airplanes. It is especially suited for running small ships, for generating electric power in diesel-electric locomotives, and for stationary engine work.
How the Diesel Engine Works
The diesel works on the cylinder and piston principle. The cylinders may be arranged in line, in a V, in opposition, or radiating from a center, like spokes in a wheel. Several radial groups, stacked one above the other, make up what is called a "pancake" engine.
Operation starts as the piston pushes the air into one end of the cylinder. Here the air is compressed to 1/16th of the space it would normally occupy. The compression heats the air about 1,000 degree Fahrenheit. At his point the fuel is injected into the cylinder. It catches fire like the flashing of grease in a frying pan. The explosion of the gas formed by the ignited fuel and compressed air pushes the piston to the other end of the cylinder. This is the power strke that turns the crankshaft.
The system of fuel injection is the heart of the diesel engine. Each cylinder has a pump which forces the fuel oil through a nozzle fitted with a number of fine holes. The oil is blown through the holes at a terrific speed. It breaks up into a fine spray which ignites immediately in the hot air to produce a powerful explosive force. The fuel injector also regulates the speed of the diesel. It varies the amount of oil injected into the cylinder and thus controls the force of the power stroke.
Diesel engines operate either on a four-stroke cycle or a two-stroke cycle. The first is shown in the diagram on the preceding page. It has one power stroke in every four. In this type each upward movement of the piston compresses air and the fuel is injected near the top of the stroke. Each down stroke starts with delivery of power from the exploding fuel. Toward the end, air from a blower sweeps out the burned gases. In the four-stroke engine, air is pulled into the cylinder by the intake stroke.
Invention and Swift Developemt of the Diesel Engine
In the late 1870's Rudolf Diesel was an engineering student at the Munich Technical College in Munich, Germany. There he heard a professor describe the low efficiency of the steam engine. Diesel determined to build a new type. His first model, built in 1892, almost killed him when he tried to start it. But by 1897, Diesel had constructed a successful engine using powedered coal as the fuel. The first diesel engine for commercial service was installed in St. Louis, Mo., in 1898. Within a few years, thousands of diesels were in use. Diesel continued to make improvement. He gained a fortune and high honors from his invention. In 1913 he mysteriously disappeared from a steamer on which he was crossing the English Channel. His important papers were missing also. No definite proof of his death was ever offered.
Today diesel engines are used widely. They have become progressively cheaper, lighter, and more efficient. Engines range in size from 15 to 1,500 horsepower. Diesel-electric locomotive haul crack passenger trains at record speeds, pull heavy freight loads at mountain grades, and perform switching duties at railroad yards. Cross-country truck and bus operators use diesels because of their low operating cost. Marine diesels are in use in tugs, freighters, and smaller passenger ships and on many naval vessels.
The diesel is favored as a cheap and efficient power source in electricity plants, factories, mines, amd pumping stations. Diesel motors drive pumps, air compressors, tractors, hoists and winches, air-conditioning and refrigeration machinery, power shovels, and many other industrial machines and tools.