A diesel engine is an internal combustion engine which operates using the Diesel cycle (named after Dr. Rudolph Diesel). The defining feature of the Diesel engine is the use of compression ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression. This is in contrast to a gasoline engine, which utilizes the Otto cycle, in which ignition is initiated by a spark plug following the aspiration and compression of a fuel/air mixture.

Diesel engines were originally used in very large vehicles such as trucks, locomotives and ships, (and also as a stationary engine), as more efficient replacement for the steam engine. The diesel engines of today are refined and improved versions of Rudolf Diesel's original concept. They are often used in submarines, ships, locomotives, and large trucks and in electric generating plants. Starting in the 1930s and initially developing slowly they have been used in a few automobiles. Since the 1970s diesel engines have developed dramatically and have been used in many more cars, starting with larger on-road and off-road vehicles (especially sport utility vehicles in the USA). As they have been refined they have been used in smaller and smaller cars. Today the smallest cars on the European market have a highly efficient diesel engine option and forty percent of all new car sales in Europe are diesel.cn: date=September 2008

History

Rudolf Diesel was born in Paris in 1858. His actual nationality was German. His parents were Bavarian immigrants. Rudolf Diesel was educated at Munich Polytechnic. After graduation he was employed as a refrigerator engineer. However, his true love lay in engine design. Diesel designed many heat engines, including a solar-powered air engine. In 1893, he published a paper describing an engine with combustion within a cylinder, the internal combustion engine. In 1894, he filed for a patent for his new invention, dubbed the diesel engine. Diesel was almost killed by his engine when it exploded. However, his engine was the first to prove that fuel could be ignited without a spark. He operated his first successful engine in 1897.

In 1898, Diesel was granted patent #608,845 for an "internal combustion engine".

Though best known for his invention of the pressure-ignited heat engine that bears his name, Rudolf Diesel was also a well-respected thermal engineer and a social theorist. Diesel's inventions have three points in common: They relate to heat transference by natural physical processes or laws; they involve markedly creative mechanical design; and they were initially motivated by the inventor's concept of sociological needs. Rudolf Diesel originally conceived the diesel engine to enable independent craftsmen and artisans to compete with large industry.cn: date=September 2008