Despite a lack of technical training, Nikolaus August Otto (1832-1891) had the ingenuity to make the first practical internal combustion engine. He later devised the four-stroke engine, known as the Otto cycle, which was widely used for automobile and other motors.

Nikolaus Otto was born in Holzhausen auf der Heide, a small village on the Rhine River in Germany. Although his father, the village postmaster, died soon after Otto was born, his mother raised him well. Young Otto excelled in school, and his mother planned for him to continue with a technical education, but the failed German revolution in 1848 and declining economic conditions made his mother believe that he would be better off as a merchant.

Otto left high school and got a job as a clerk in a grocery store. He soon was working as a clerk in the nearby city of Frankfurt. His older brother Wilhelm owned a textile business in Cologne, and he helped Otto get a job as a sales representative. Otto sold tea, sugar, and kitchenware to grocery stores along the western border of Germany.

Otto's First Engine

Though he spent a great deal of time travelling between his home in Cologne and the many small towns he served, he still had time to meet and begin a long courtship with Anna Gossi. Their courtship lasted nine years, due to his travelling and a new interest of Otto--engines. What little we know of his early interest and experiments with engines comes to us from the love letters that Anna received and saved after they married.

While he was traveling as a salesman, Otto first learned about the new gas-powered engine invented by Etienne Lenoir. It was the first workable internal combustion engine. Before that, the energy to run an engine usually came from external combustion, such as in a steam engine. In a steam engine, a fire was used to heat water. The resulting steam was compressed and, upon expanding, pushed a piston, fitted to a cylinder, that transferred the power to a crankshaft. Then steam was directed to the other side of the piston, forcing it back. Thus, every stroke of the piston contributed power.

Although a great advance, the Lenoir engine was never an efficient and practical invention. It used the same principal as a steam engine, except that the piston was moved not by steam pressure, but by the ignition of a mixture of air and gas. When the mixture was ignited, an explosion and rapid expansion pushed the piston back. But it was noisy, used far too much expensive fuel that needed to be stored or transported in a gaseous state, and produced too much heat. It was initially popular as a replacement for steam engine applications but soon fell from favor.

Otto was sure that the Lenoir engine would be more flexible if it ran on liquid fuel. Although he had been deprived of a technical education, Otto invented a carburetor for this engine and worked to improve it in other ways. He tried to patent the carburetor in Prussia in 1861 but was denied a patent. In 1861, Otto built his first gasoline-powered engine.

Partnership with Langen

In 1864, Otto was lucky to meet Eugen Langen. Langen had interests in manufacturing and sugar production and had designed much of the equipment that his businesses owned. He was looking for new interests, and Otto's engine intrigued him. Langen saw that, though imperfect, the engine had possibilities, and agreed to invest in Otto and his engine. Together they formed N.A. Otto and Cie. Langen brought cash to the relationship, Otto brought his expertise. The company began work on improving the engine and building a factory for its manufacture.

Three years later, they had developed a much-improved engine. It bore little resemblance to either the Lenoir engine or to Otto's early prototypes. When they decided to exhibit the engine at the 1867 Paris Exhibition, it was almost a disaster. The French judges at first ignored the engine in favor of more familiar styles. An old school friend of Langen sat on the board of judges, and he convinced the others that efficiency should be part of the decision. When tests showed that the Otto-Langen engine was using less than half the energy that the other engines were using, the machine was awarded the gold medal.

The resulting publicity created a demand for their engine that the partners could not meet. Seeking capital, they entered into a partnership with Ludwig August Roosen-Runge, a businessman from Hamburg. The company became Langen, Otto, and Roosen in March 1869, and its factory moved to the Cologne suburb of Deutz. Roosen-Runge's money helped, but demand still outstripped supply. Langen convinced his brothers and their partners in the sugar business to invest. Their combined investment was more than 13 times what Roosen-Runge had invested, and it enabled a new company, Gasmotoren-Frabrik Deutz AG, to be incorporated in January 1872. Otto, who had never invested money in the business, received no stock in the new company and accepted a long-term employment contract instead.

Langen made one very important hiring decision at Deutz. Gottleib Daimler had trained as a gunsmith before he became an engineer. He had years of experience in factories across Europe, and Langen saw him as the man who could run the new, larger factory. Daimler was appointed technical director to the Deutz works. Daimler brought with him his protege, a young engineer named Wilhelm Maybach. Over the next ten years, Maybach, who would become one of the great engine designers, would work closely with Otto on many projects, including developing the internal combustion engine for use in road vehicles.

The Four-Stroke Engine

Deutz became the premiere engine manufacturer in the world and was soon licensing its design around Europe. In 1876, Otto's newest invention was built, and the internal combustion engine was never the same. Otto knew that the engines based on Lenoir's basic design had reached their limitations. They were noisy, vibrated a lot, and were limited in the amount of power they could produce. He knew that more power and efficiency could be reached if the fuel mixture could be better controlled and compressed. He saw that the way to do this was to use only one piston per chamber and spread the cycle of combustion over four strokes.

In the four strokes of the Otto cycle, the first outward stroke of the piston draws a mixture of air and fuel into the piston through a valve into the cylinder. The second stroke compresses the mixture, preparing it to be ignited. Ignition of the fuel-air mixture causes an explosion, and the rapid expansion of the resulting gases provides the power for the third stroke. On the fourth, inward stroke, the piston forces the exhaust gases out of the cylinder through another valve.

This design went against what was considered prudent at the time. Most engineers believed that every stroke had to provide power, as in the steam engine. They thought Otto's design would be inefficient if only one stroke out of four provided power. But of greater importance to Otto was the concept of the stratified charge. While watching how smoke left a chimney densely, then spread out into the air, he realized that he could use the same principle within a cylinder to make an engine run cleaner and smoother. Although the four-stroke engine was an immediate success, the stratified-charge theory was disputed and discredited. In this, Otto was a century ahead of his time, for the Honda Motor Company of Japan would find great success with a stratified-charge engine in its automobiles beginning in the 1970s.

The four-stroke engine became known as the Otto engine, and the concept was called the Otto cycle. It was another big success for the Deutz works, and once again the factory fell short of the capacity needed to meet demand. It was the peak of the worldwide Industrial Revolution, and Deutz was able to sell 8,300 Otto engines between 1876 and 1889, more than eleven a week on average.

Patent Fights

The concept of the Otto engine was so advanced that there was little that competing manufacturers could do. Deutz protected its position as the world's sole supplier and licenser of Otto engines, taking any infringement of Otto's patent to court and protecting the patent against spurious claims. In 1884, Deutz's competitors got a lucky break. An old French pamphlet detailing the concept of the Otto cycle but published before Otto had built his engine was discovered by a lawyer, C. Wigand, a friend of a pair of engine manufacturers from Hannover, Ernst and Berthold Korting. The pamphlet was based on an 1862 patent filed by French engineer Alphonse Beau de Rochas. It did not matter that Beau de Rochas had not built an engine nor that he had let his patent lapse by failing to pay his annual patent tax. (In many countries, an annual fee is required to maintain a patent.) And Beau de Rochas had never tried to defend his patent, even though the Otto engine was famous, selling in great numbers, and had won a gold medal at the 1878 Paris Exposition. Even so, with the help of Wigand, the Korting took the case to the courts.

Although the case was weak, the atmosphere in Germany was not in Otto's favor. There was no national patent registry, and patents could be held in any or all provinces. Often, one province would grant a patent while another would deny it. So Wigand could choose to fight the patent in the most cooperative province. Some historians speculate that the German government did not want to limit who could hold patents because it wanted to decrease monopolies and spread wealth. Whatever the reason, Otto lost the case. Although more than 30,000 four-stroke engines were built before 1886, and Deutz marketed them with the widely accepted "Otto engine" name, Otto's German patent was revoked. The Kortings were free to manufacture Otto cycle engines. Otto was able to retain his patent in England.

Because they did not see eye-to-eye with Otto, in 1882 Daimler and Maybach left Deutz to set up their own company. Daimler and Maybach were successful with their automotive application in 1889. They placed their engine, an Otto-cycle four-stroke engine, into a horse carriage, producing the first four-wheeled automobile. They set to work improving the vehicle so it could be offered for sale. The first Daimlers were sold in 1890.

Otto died on January 26, 1891 in Cologne, a rich man thanks to the licenses he shared in and the patents he held. The company he and Langen began became one the largest companies manufacturing internal combustion engines: Klockner-Humboldt-Deutz AG. A memorial honoring Otto stands in the forecourt of the neo-baroque Deutz train station in Cologne.

It has often been said that this person or that person "put the world on wheels." Perhaps more than anyone, that is true about Nikolaus Otto. Though only Daimler's name is recognized by most of the world as the maker of the first automobile, historians and those inside the automobile industry recognize the man who was responsible for the ingenuity that gave us the Otto-cycle engine.

Further Reading

• Cummins, C. Lyle, Internal Fire, Carnot Press, 1976.
• Suzuki, Takahashi, The Romance of Engines, Society of Automotive Engineers, 1997.