A heat engine in which fuel is burned inside the cylinder rather than (as with a steam engine) outside it. Multiple commercial internal-combustion engines predate the Otto cycle: Étienne Lenoir's gas-fueled, non-compressed two-stroke engine reached commercial sale in the early 1860s (a few hundred deployed for printing presses, water pumps, and machine tools), and the Otto & Langen atmospheric engine, commercialized through Deutz from the early 1870s, outsold Lenoir on efficiency. The four-stroke cycle itself was patented in 1862 by the French engineer Alphonse Beau de Rochas as a thermodynamic concept, but Nikolaus Otto built the first practical compressed-charge engine on this principle in May 1876, with a German patent granted in 1877. The Otto cycle — not the Lenoir or Otto-Langen designs that preceded it — is the propulsion ancestor of every petrol or diesel bus engine in history; Carl Benz used it in his 1885 Patent-Motorwagen and in the 1895 Netphen omnibuses, the first motorbuses in the world.[1,2]
Role. Built the first commercially-sold internal-combustion engine, 1860 (gas-fueled, non-compressed, two-stroke)
Contribution. First ICE to achieve commercial production and sales — a few hundred units deployed running printing presses, water pumps, and machine tools. Predated Otto's compressed-charge engine by 16 years. Eventually superseded by Otto's far-more-efficient four-stroke design.
Role. Built the first practical four-stroke compressed-charge internal-combustion engine, 1876
Contribution. Solved the problem of progressive (rather than explosive) combustion via charge stratification — making the four-stroke principle commercially viable. Patent granted 1877.
Role. Patented the four-stroke cycle as a thermodynamic concept, 1862
Contribution. Theoretical formulation of the four-stroke cycle 14 years before Otto's working engine. Underrecognized because his patent didn't lead to a working machine and Otto's name attached to the cycle.
| Year | Event | Type | Significance |
|---|---|---|---|
| 1860 | Étienne Lenoir's gas engine reaches commercial sale. | scaling | First internal-combustion engine to achieve commercial production. ~500 built (under license in Germany included), used for printing presses, water pumps, and machine tools. Sixteen years before Otto. Not in the bus lineage — the Otto cycle (1876) is — but a meaningful prior milestone in commercial ICE history.[7] |
| 1862 | Beau de Rochas patents the four-stroke cycle as a concept. | patent | Theoretical priority on the four-stroke cycle, but no working engine.[8] |
| 1876 | Otto builds the first working compressed-charge four-stroke engine, 9 May. | invention | The compressed-charge breakthrough that made the four-stroke cycle practical; the Otto cycle is the propulsion ancestor of every petrol or diesel bus engine.[9] |
| 1877 | Otto granted German patent for the four-stroke engine. | patent | Patent later partially invalidated due to Beau de Rochas's prior art, but commercial dominance was already established.[10] |
Every claim above is backed by a verbatim excerpt from the source listed here. Click any citation number to jump to its source. Sources are deduplicated: a single source may support several claims on this page.
Nikolaus Otto was a German engineer who developed the four-stroke internal-combustion engine, which offered the first practical alternative to the steam engine as a power source. Otto's innovation in creating a four-stroke piston cycle engine in 1876 marked a pivotal moment in engine design.
By 1865, 143 had been sold in Paris alone, and production of Lenoir Gas Engines, by Reading Gas Works in London, had begun. Most applications of the Lenoir engine were as a stationary power plant powering printing presses, water pumps, and machine tools.
Belgian-French engineer who invented the internal combustion engine in 1858
Other engineers, especially Nicolaus Otto, began making improvements to internal combustion technology, which soon rendered the Lenoir design obsolete.
After 14 years of research and development, Otto succeeded in creating the compressed charge internal combustion engine on May 9, 1876, finding a way to layer the fuel mixture into the cylinder to cause the fuel to burn in a progressive, as opposed to explosive fashion.
Although Otto was the first to build an engine based upon this principle, the four-stroke cycle was patented in 1862 by the French engineer Alphonse Beau de Rochas, but it is commonly known as the Otto cycle.
Fewer than 500 Lenoir engines of 6-20 hp were built, including some under license in Germany. Most applications of the Lenoir engine were as a stationary power plant powering printing presses, water pumps, and machine tools.
the four-stroke cycle was patented in 1862 by the French engineer Alphonse Beau de Rochas
Otto succeeded in creating the compressed charge internal combustion engine on May 9, 1876
Otto was granted a patent for his four-stroke engine in 1877.