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Rudolf Diesel

inventor of the "rational heat engine"

Rudolf Diesel

Rudolf Christian Karl Diesel was born in Paris, France, on March 18, 1858, the son of German immigrants. As a young boy he spent many hours in the Paris Museum of Arts and Crafts, where he often made drawings of the various machines on display. After the family moved to London upon outbreak of the Franco-Prussian War in 1870, Diesel began frequenting the Science Museum there. He was subsequently sent to Augsburg, Germany, to live with an uncle, a professor of mathematics at the Augsburg trade school. It was in Augsburg that he first saw a pump which created heat by compression of air, and it was this pump that would eventually lead to the engine which now bears his name.

In 1875 Diesel began attending lectures at Munich Technical University, and subsequently graduated with the most brilliant record in the university's history to that time. One of the lectures he attended was held by Carl von Linde, whose research in thermodynamics had led to the invention of refrigeration techniques. After graduating Diesel began working at Linde's refrigeration company. In 1880 he returned to Paris to assist in the construction of a refrigeration plant, and then became manager of that plant. He would continue to work for Linde until about 1890.

During the course of Diesel's university studies and early working career he determined that existing engines were inefficient and became resolved to build a better one. He initially worked on an expansion engine that used ammonia as the working fluid, but the engine exploded during a test and left Diesel seriously injured. He then decided to use the heat generated by compressing air to ignite a fuel mixture in the cylinder, and in 1885 he set up a shop-laboratory in Paris to perfect the concept. He received his first patent in 1892, and his second in 1893. Also in 1893, he published a paper about his engine, entitled The Theory and Design of a Rational Heat Engine.

Diesel's first successful engine

With help from Linde, Diesel was able to secure financing from two German companies to develop his engine, and he began working in Augsburg in 1893. His first successful engine -- a single cylinder, four stroke model that made 25 horsepower -- was built in 1897, and demonstrated at a Munich exhibition the following year. Diesel began selling licenses to build his engine, and soon became a millionaire.

What made (and continues to make) Diesel's engine different was that, unlike other internal combustion engines, it requires no spark plug to ignite the fuel. In "traditional" engines, the fuel is combined with the air first, the air-fuel mixture is then compressed, and then a spark is introduced to ignite the fuel. But in Diesel's engine, the fuel is not introduced until the air is already compressed and hot, and it is the hot air that causes the fuel to ignite.

While Diesel's engine enjoyed immediate success, it did have its problems. The tremendous pressures under which the engine operated meant that any flaw in the materials from which it was made could easily lead to failure. In addition, Diesel always insisted that his engines be built to his original specifications and was habitually slow about incorporating improvements into the basic design. To make matters worse, Diesel's was not the first compression-ignition engine to be tested, and some of his patents were contested. Although Diesel ultimately won all of the patent battles and therefore the right to have his name permanently affiliated with the compression-ignition engine, the battles left a toll on his mental health, which many have said was already questionable.

On September 29, 1913, Diesel disappeared during a trip across the North Sea from Antwerp, Belgium, to Harwich, England, aboard the mail steamer Dresden. His body was found in the water a few days later, and it is believed by most that he committed suicide by jumping off the ship. His book, The Genesis of Diesel Motors, was published shortly before his death.


The Engines of Our Ingenuity

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This page was last updated on September 29, 2018.