Nicolaus August Otto (pronounced "nee-koh-lows aus-ghts oh-toe") was a German engineer born on June 10, 1832, and died on January 26, 1891. He invented the compressed charge internal combustion engine, which used petroleum gas and became the basis for modern engines of this type. The Association of German Engineers (VDI) developed a standard called DIN 1940, which defines an "Otto Engine" as an internal combustion engine that uses a timed spark to ignite a compressed fuel-air mixture. This definition has been used for all engines of this type since its creation.

Biography

Nicolaus August Otto was born on June 10, 1832, in Holzhausen an der Haide, Germany. He was the youngest of six children. His father passed away in 1832. Otto began school in 1838. After six years of strong performance, he moved to a high school in Langenschwalbach and remained there until 1848. He did not finish his studies but was noted for his good performance.

During school, Otto was most interested in science and technology. However, after completing a three-year business apprenticeship at a small merchandise company, he graduated. Following his apprenticeship, he moved to Frankfurt and worked as a salesman for Philipp Jakob Lindheimer, selling goods from other countries and agricultural products. Otto later worked for several companies, including IC Alpeter and Carl Mertens. He traveled across Western Germany, selling items such as coffee, tea, rice, and sugar.

Lenoir engine

In late autumn of 1860, Otto and his brother discovered a new type of gas engine created by Jean Joseph Etienne Lenoir in Paris. The brothers built a copy of this engine and, in January 1861, asked the Prussian Ministry of Commerce to grant them a patent for an engine that uses liquid fuel, based on Lenoir’s design. Their request was not approved.

First four stroke engine, 1861

Otto knew about the idea of compressed fuel charge and tried to build an engine using this principle in 1861. The engine worked for only a few minutes before breaking. Otto's brother stopped working on the idea, so Otto looked for help from other people.

Between 1862 and 1863, Otto worked with a mechanic named Michael J. Zons from Cologne to improve the engine. In 1862, Otto needed more money, so he worked for Carl Mertens to keep working on his engine.

Partnership with Eugen Langen

In early 1864, Otto looked for people to help fund his research. He found Eugen Langen, whose father was a business owner in the sugar industry. On March 31, 1864, they formed a partnership and named their company NA Otto & Cie in Cologne. This was the first company in the world that focused only on designing and building internal combustion engines.

The Otto & Langen engine from 1864 was a free piston atmospheric engine. It used gas explosions to create a vacuum, and power came from atmospheric pressure pushing the piston back. This engine used less than half the gas of similar engines made by Lenoir and Hugon, which made it a success in business. The Lenoir engine was a double-acting engine, meaning it used gas to create power on both sides of the piston. These engines were based on steam engines that were changed to run on illuminating gas. Engines made by Italian inventors Eugenio Barsanti and Felice Matteucci, described in British Patent no. 1625 from 1857, were built and are now in a museum. Unlike Otto’s engine, these were two-stroke atmospheric engines and are not similar to Otto’s design.

Although the Otto and Langen engine was commercially successful, producing 634 engines per year by 1875, it faced technical challenges. It produced only 3 horsepower (2.2 kW; 3.0 PS) but required 10–13 feet (3.0–4.0 meters) of vertical space to operate.

Otto then focused on the four-stroke cycle, a design he had tried in 1862 without success. With the help of Franz Rings and Herman Schumm, who joined the company through Gottlieb Daimler, Otto created the Four Stroke, Compressed Charge engine. This engine, known as the Otto Silent Engine, is the one referred to as the "Otto cycle." It was the first commercially successful engine to use in-cylinder compression. The Rings-Schumm engine was introduced in autumn 1876 and became popular quickly.

In summary, the Otto engine that is considered the predecessor of modern engines, as defined by the VDI, is Otto’s fourth design. He built the following engines:

• 1861: A copy of Lenoir’s atmospheric engine
• 1862: A four-stroke compressed charge engine (before Rochas’s patent) that failed quickly
• 1864: The first successful atmospheric engine
• 1876: The four-stroke compressed charge engine, known as the "Otto" cycle engine. The term "Otto cycle" applies to all four-stroke engines that use compressed gas.

Otto married Anna Gossi, and the couple had seven recorded children. His son, Gustav Otto, grew up to become an aircraft builder.

The Otto cycle

The Otto engine was created to stay in one place, like a machine that doesn't move. In this engine, a stroke is when the piston moves up or down inside a cylinder. Later, this engine was modified for use in cars, and it uses four strokes:

• (1) Downward intake stroke: A mixture of coal gas and air enters the chamber where fuel burns.
• (2) Upward compression stroke: The piston squeezes the mixture together.
• (3) Downward power stroke: The fuel mixture is ignited by a flame, and later, by an electric spark.
• (4) Upward exhaust stroke: Exhaust gas is pushed out of the chamber.

Otto only sold his engine for use in stationary machines.

Earlier patents

Otto received many patents from several countries for different inventions. When his former manager, Gottlieb Daimler, wanted to build small engines for transportation, Otto showed no interest. Daimler left and took Maybach with him. Daimler did not want to pay money to Otto (Deutz AG) for using Otto’s ideas, so he hired a lawyer to find a solution. The lawyer discovered a patent for the idea of a four-cycle engine that had been given to Beau De Rochas, a French engineer, in 1862. This discovery caused Otto to lose one of his patents and allowed Daimler to sell his engines in Germany without paying money. Neither Otto nor Daimler knew about the Rochas patent. Rochas never built an engine. It is likely that he could not have done so.

Some inventions often mentioned as coming before the Otto engine, such as those by Marcus and Barsanti, were for two-cycle (two-stroke) atmospheric engines that did not compress fuel. Otto’s atmospheric engine is not the same as the VDI (and other groups) Otto engine type. The only important engines before Otto’s were those made by Lenoir. His engines were the first to be produced in large numbers. Lenoir eventually sold about 700 engines.

Honors

Otto received many honors for his engines.

• His 1864 atmospheric engine received a gold medal at the 1867 World Exhibition in Paris.
• In 1882, Otto was given an Honorary Doctorate by the University of Würzburg.
• His home is now a museum that the local government supports.
• In 1936, Professor Nagël, who led the Association of German Engineers, decided that DIN Standard 1940 would define "Ottomotor" as the term for all engines that mix fuel, compress it, and ignite it using a special device. This replaced older terms such as "explosion motor," "detonation engine," "benzine engine," and "ignition engine."

Milestones

• 1862: First tests with four-stroke engines were conducted.
• 1864: The first engine factory in the world was created, named NA Otto Cie.
• 1867: A gold medal was awarded at the World Exhibition in Paris for the gas engine.
• 1869: The company moved to a new location and changed its name to Langen, Otto, and Roosen.
• 1872: The company moved to bigger buildings and was renamed Deutz Gasmotoren Fabrik.
• 1876: The four-stroke engine, called the Otto-motor, was developed.
• 1882: Production of the Atmospheric engine ended after 2,649 units were made.
• 1884: Nicolaus Otto created the electric ignition system.
• 1885: Gottlieb Daimler and Karl Benz built the first automobiles powered by liquid petroleum engines.