Internal Combustion Engines
An internal combustion engine is an engine with working cylinders in which combustion occurs within the cylinders, providing mechanical power. Assorted designs of internal combustion engines were developed before the 19th century, but their commercial employment was hindered until petroleum became widely available in the mid-1850s. By the late 19th century internal combustion engines were employed in a variety of applications.
Internal combustion engines were patented as early as 1807, but none of these were commercially successful. The first such engine to succeed was by Belgian engineer Étienne Lenoir, who built a single-cylinder 2-stroke spark-ignition engine in 1858 that could be operated continuously. Lenoir’s engine differed from more modern 2-stroke engines in not compressing the charge before ignition.
Such a system had been invented in 1801 by French engineer Lebon d’Humberstein. It had a power stroke at each end of the cylinder, which worked quietly but also inefficiently. d’Humberstein was assassinated before he could work through the flaws in his patented design.
In 1861, French engineer Alphonse Beau de Rochas publicized his design for a 4-stroke engine, which he never built. Meanwhile, German engineer Nikolaus Otto built his first gasoline-powered engine the same year.
Otto tinkered away for decades. In 1876, he built a 4-stroke engine that efficiently burned fuel in a piston chamber. This process became known as the “Otto cycle.” It was the first practical alternative to the steam engine.
American engineer George Brayton developed a 2-stroke kerosene engine in 1873, but it was too large and slow to be commercially viable.
2-stroke engines complete a power cycle in 2 strokes of a piston – up and down – during a single crankshaft revolution. In contrast, a 4-stroke engine requires 4 strokes to complete a power cycle: 1) intake (for the air-fuel mixture), 2) compression (in a closed piston), 3) power (the engine delivers power to turn a crankshaft), and 4) exhaust (expelling the spent air-fuel mixture).
In a 2-stroke engine, the intake and exhaust functions simultaneously. 2-stroke engines have a higher power-to-weight ratio and fewer moving parts, so can be more compact and much lighter.
Scottish engineer Dugald Clerk designed the first successful 2-stroke engine in 1878. Although the form was simplified somewhat by English engineer Joseph Day in 1891, Clerk’s basic design remains in use today.
Owing to their power, low cost, and simple design, 2-stroke petrol engines were very popular throughout the 19th and 20th centuries in devices needing small engines, such as motorcycles, outboard motors, and chainsaws. But they emit more pollution. In the US, when the federal government mandated more stringent emissions, manufacturers switched to 4-stroke engines.
German engineer Gottlieb Daimler constructed the prototype of the modern gas engine in 1885. It was small and fast, with a vertical cylinder, using gasoline injected through a carburetor. A carburetor is a device for mixing air with vaporized fuel to produce a combustible or explosive mixture.
While others were contemporaneously working on their own automobile designs, German engineer and engine designer Karl Benz was first to patent an internal combustion engine automobile, in 1886. Benz patented his engine in 1879, and then patented the processes that made the internal combustion engine feasible for autos.
In 1889, Daimler introduced a 4-stroke engine with a much higher power-to-weight ratio. It had 2 cylinders arranged in a V, with mushroom-shaped valves. With the exception of an electric starter, most modern gasoline engines are descended from Daimler’s models.
A starter is an electric motor that initiates an internal combustion engine. The starter’s job is done once the engine starts. Before electric starting, internal combustion engines got going via a hand crank: a difficult and dangerous undertaking. Engines can be unpredictable during startup. An engine can kick back, causing sudden reverse rotation.
The first electric starter was installed in 1896 by its developer, English electrical engineer H.J. Dowsing. Starters became common in the early 1920s.
Rudolf Diesel developed his namesake compression-ignition engine in 1892. Fuel was injected at the end of compression and ignited by the high temperature created from the compression. Diesel demonstrated his engine at the 1900 World’s Fair using peanut oil for fuel.