Otto, Nikolaus August (1832–1891)

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Otto was born in the village of Holzhausen, near Frankfurt. His father, an innkeeper, died when Otto was a small boy. This was a period of declining prosperity in Germany, although Otto's mother had hoped her son might receive a technical education, Otto was forced to leave school and take up employment in a Frankfurt grocery store. His brother Wilhelm, who had a textile business in Cologne, then secured him a position as a salesman in tea, sugar, and kitchen ware to grocery stores. Otto's travels took him along the German border with France and Belgium as far as Cologne where in 1859 he met Anna Gossi and began a nine-year courtship.

In 1860 Jean Lenoir built the world's first mass production internal combustion engine, a noncompression double-acting gas engine. Otto saw the potential of the Lenoir engine and perceived that the future development of the internal combustion engine would be dependant on its fuel source. In an attempt to make the engine mobile he devised an alcohol-air carburetor, and with his brother filed for a patent in 1861. Hampered by a lack of funds and a technical education, Otto spent all his leisure time in developing an engine that would surpass that of Lenoir. In 1861 Otto commissioned a Cologne instrument maker, Michael Zons, to build an experimental model Lenoir engine. Otto carried out a series of experiments with the purpose of lessening piston shock loading at the start of combustion. In one series of experiments he turned the engine over drawing in the explosive mixture, the piston was then returned to top center compressing the mixture that was then ignited. Otto found that ignition took place with great violence. This undoubtedly set the scene for the development of Otto's compression engine. In 1862 Zons built for Otto a flat four-cylinder engine. Each cylinder contained a free "cushion" piston, this engine, however, was a failure. In 1863 Otto had Zons built a one-half horsepower atmospheric engine.

In 1864 Otto's luck took a turn for the better when his engine came to the attention of Eugen Langen. Langen was a partner in a sugar refining business that he had expanded into refining sugar beets as well as cane sugar, using processing equipment of his own design. Although Langen could see the deficiencies in Otto's design he quickly made up his mind to invest in the engine. With the help of his father, Langen raised sufficient capital to form a company. In March 1864 Otto and Langen signed an agreement forming N.A. Otto & Cie, the world's first company to be set up to manufacture internal combustion engines. By 1867 the engine design was perfected and a patent applied for. The improved engine was exhibited at the 1867 Paris Exposition. After a series of tests that examined the engine efficiency and performance, the Otto and Langen engine was found to consume less than half the gas of the best noncompression engine and was awarded a gold medal. Although orders now flooded in, the partners still lacked sufficient funds. New partners were sought and Otto, whose stock holding, fell to zero, accepted a long-term employment contract. In 1872 Gasmotoren-Fabric Deutz AG came into being with Langen in control and Otto as Technical Director. Gottlieb Daimler joined the firm as production manager bringing with him Wilhelm Maybach to head the design department. Improvements were made to the engine probably by Maybach, but Daimler demanded they be patented in his name, an action that led to disputes between him and Langen. Langen also had to arbitrate numerous disagreements between the autocratic Daimler and the oversensitive Otto. Through the use of licenses and subsidiaries, Otto and Langen established an international industry with engines being built in most industrialized nations.

Around 1872 Otto returned to the problem of shockless combustion. It occurred to him, if only air was brought into the cylinder first and then the gas/air mixture, the charge would become progressively richer towards the source of ignition. Otto built a small hand-cranked model with glass cylinder to study his stratification idea by using smoke. A prototype four-stroke cycle engine was constructed in 1876. Although, at the time, Daimler thought Otto's new ideas would prove a waste of time, Langen assigned Otto an engineer and let him continue his research. Otto's ideas concerning stratification were patented in 1877. The new engine had a single horizontal cylinder and bore some similarity to the Lenoir engine. The important difference was in the admission of gas and air, also gas flame ignition. Otto seemingly had more faith in ignition by flame rather than electrical spark. The basic elements of the modern four-stroke engine are to be found in this experimental engine. A slide valve controlled air intake with a second cam operated slide valve controlling gas admission. As the piston began its outward stroke, the air valve opened and the gas valve remained closed until the piston had completed half its travel. At the end of the stroke, the valves closed and the piston began the return stoke compressing the air gas mixture. At the end of the return stroke, the gas air mixture is ignited and the piston commences its second outward stroke, the power stroke. At the end of this stroke the exhaust valve opens, and the piston returns exhausting the burnt gasses. In Otto's new design there was one power stroke for every four strokes of the piston or two revolutions of the flywheel.

Wilhelm Maybach redesigned Otto's prototype engine for mass production. The "Otto Silent" engine rapidly established the gas engine as a practical power source and Deutz jealously protected their position as the world's sole supplier of Otto's new engine. Through litigation and threats of action Deutz pursued any manufactures who attempted to infringe on the Otto patent. These actions, while effectively emasculating other engine builders, acted as a stimulus for basic research into the correctness of Otto's ideas on stratified charge and in turn the validity of his patent. Deutz's manufacturing competitors in endeavoring to discredit the stratified charge theories discovered an obscure patent filed by Frenchman A. B. de Rochas in 1862. Although de Rochas's patent had never been published, through a failure to pay the required fees, nor was there any evidence he had produced a working engine, his patent was used to challenge Deutz's monopoly. During litigation Otto strove to establish prior invention, but suffered, as have many other inventors, from inadequately documenting his research work. Although Otto must be considered the true inventor of the four-stroke cycle, patent law is more a matter of establishing priority of ideas than production of working machines. The Otto patents were overturned in Germany in 1886. In Britain, Otto's designs were licensed by Crossley who successfully defended their position by having the de Rochas patent ruled inadmissible.

Although his ideas were vindicated in Britain, the loss of his German patents were a blow to Otto's pride from which he apparently never recovered. Otto died five years later in 1891. Otto's only son Gustov became an engineer and aircraft designer in Munich, and in 1901 founded an airframe company that produced aircraft for World War I.

Robert Sier

See also: Engines; Gasoline Engines.


Barlow, K. A. (1994–1995). "Nikolaus August Otto and the Four-Stroke Engine." Transactions of the Newcomen Society 66: suppl. no. 1.

Clerk, D. (1896). The Gas and Oil Engine, 6th ed. London: Longman, Green and Co.

Cummins, C. L. (1976). Internal Fire. Oregon: Carnot Press.

Donkin, B. (1896). Gas, Oil and Air engines, 2nd ed. London: Griffin and Co.