The diesel engine was invented by Rudolf Diesel, in the year 1893. Rudolf Diese was a German engineer, employed by the firm MAN.
Rudolf Diesel studied high thermal efficiency engines, with the use of alternative fuels in internal combustion engines. Diese's goal was to replace the old steam engines that were inefficient, very heavy and expensive.
First steps before reaching the diesel engine
In 1806, brothers Claude and Nicéphore Niépce developed the first known internal combustion engine and the first fuel injection system. The two brothers tested systems with different fuel types and compositions.
Finally in 1816 they experimented with alcohol and white petroleum oil (a fuel similar to kerosene). They discovered that kerosene-type fuel could be vaporized. Being able to be vaporized made the fuel highly flammable.
The Brayton constant pressure motor
In 1874, George Brayton developed and patented a 2-stroke oil-fed constant pressure motor, "The Ready Motor". This engine used a metered pump to supply fuel to an injection device in which the oil vaporized by air and burned when it entered the cylinder. Brayton engines were used to supply mechanical power.
In 1885, the English inventor Herbert Akroyd Stuart began to investigate the possibility of using a paraffin oil (very similar to modern diesel) for an engine. Paraffin, unlike gasoline, would be difficult to vaporize in a carburetor since paraffin volatility is not enough.
Hot bulb motors
The hot bulb motor is the predecessor of the diesel engine. The first prototype of the hot bulb engines was developed in 1886. The first models built of this type of engine were produced from 1891 by Richard Hornsby and Sons. In this type of engine they used a low pressure fuel injection system.
The Hornsby-Akroyd oil engine used a comparatively low compression ratio, so that the temperature of the compressed air in the combustion chamber at the end of the compression stroke was not high enough to start combustion. Instead, the combustion was carried out in a separate combustion chamber, the "vaporizer" or "hot bulb" mounted on the cylinder head, in which the fuel was sprayed. The autoignition was caused by the contact between the air and fuel mixture and the hot walls of the vaporizer.
As the engine load increased, the bulb temperature also increased, causing the ignition period to advance; to counteract the pre-ignition, water was dripped into the air inlet.
In 1892, Akroyd Stuart patented a water-jacketed vaporizer to increase compression ratios. The main objective was to reduce autoignition problems at higher loads and compression ratios. In the same year, Thomas Henry Barton at Hornsbys built a high compression version for experimental purposes. In this version, the vaporizer was replaced by a cylinder head, therefore, it did not depend on the preheated air, but on combustion through higher compression ratios.
Herbert Akroyd Stuart was a pioneer in developing ignition by compression thanks to the heat of combustion retained in the bulb. However, Rudolf Diesel was credited with the true inventor of the compression ignition engine that relied solely on compression heat and no other form of heat retained.
The distinguishing feature of the Diesel patent is greater compression and thermal efficiency along with the fuel injection time and the vaporization of the fuel through the injection system and not through the heated surface.
Invention of the diesel engine - Rudolf Diesel
The definition of a diesel engine for many has become an engine that uses compression ignition. For some it may be an engine that uses heavy fuel oil. For others, an engine that does not use spark ignition.
However, the original cycle proposed by Rudolf Diesel in 1892 was a constant temperature cycle (a cycle based on the Carnot theory) that would require much more compression than is necessary for compression ignition. The idea of Diesel was to compress the air so strongly that the temperature of the air exceeded that of combustion.
In later years, Diesel realized that his original cycle would not work and adopted the constant pressure cycle. Diesel, in the description of the corresponding patent, no longer mentions that the compression temperatures must exceed the combustion temperature. Now all that is mentioned is that the compression must be high enough for the ignition.
Rudolf Diesel had a major accident due to the explosion of one of his experimental diesel engines. The accident caused injuries to Diesel and his collaborators and almost cost him his life.
For years Diesel worked to be able to use fuels other than gasoline, based on the principles of compression engines without spark ignition. The origins of this type of thermal engine can be traced back to the steam engine. In this way, in the year 1897, MAN produced the first engine according to the studies of Rudolf Diesel.
The fuel used for its operation was light oil. Light oil was a low-volatile fuel, which in those years was widely used, better known as fuel oil. The main application of fuel oil, at that time, was mainly to light street lamps.