Combustion

Part 2 - Internal Combustion

Top video is a Brayton cycle engine.

Designing the first internal combustion engines was not easy. The piston, cylinder and crankshaft had already been invented but steam engines were external combustion engines. There was no fire in the cylinders. And they had double acting pistons capable of delivering power for the full length of the stroke, on every stroke of the piston. The force on the piston depends entirely on the area of the piston and the steam pressure. And the pressure could be maintained for the full stroke of the piston. 

They didn't need flywheels, gears or clutches since they provide maximum torque at zero revolutions per minute; ideal for locomotives.

In 1804 a Swiss military engineer, François Isaac de Rivaz, thought the explosive charge in a cannon could be used to drive a piston instead of a cannon ball. He built an internal combustion engine that used a mixture of hydrogen and oxygen ignited by an electric spark. In 1807 his engine drove the first vehicle to be powered by an internal combustion engine.

In 1807, French engineers Nicéphore and Claude Niépce (who went on to invent photography) built an engine which ran on lycopodium powder (the highly flammable dry spores of clubmoss plants) and used it to power a boat.

The first internal combustion engines adopted pistons, cylinders and crankshafts from the steam engines but getting just the right amount of air and fuel into the cylinder and igniting it at exactly the right time and then getting rid of the exhaust gases before starting the cycle again was difficult.

Thomas Mead and Robert Street both patented internal combustion engines in 1794 and the first American engine was built by John Stevens in 1807.  

Between 1825 and 1835, Samuel Brown developed the first commercially viable internal combustion engine based on James Watt's condensing steam engine. He burned coal gas to fill the cylinder with hot gas and cooled it with a water spray to create a partial vacuum. A later design burned hydrogen and carbon monoxide in a separate combustion chamber and this was used to power a 36 foot boat fitted with paddle wheels. A similar engine was used to pump 2000 gallons per minute of water for the Croydon Canal in 1830 south London, England.

A more efficient gas/vacuum engine was invented in 1854 by Eugenio Barsanti and Felice Matteucci and was sold worldwide from about 1877 until it was superseded by still more efficient engines.

In 1860, Belgian engineer Jean Joseph Etienne Lenoir converted a steam engine to use a mixture of coal-gas and air, ignited by a spark ignition system. In 1863, a one cylinder, internal combustion engine fueled with hydrogen drove his 'Hippomobile' a distance of eleven miles in less than three hours. Despite it being inefficient, noisy, liable to overheat and capable of only 3 km/h, 143 were sold in Paris by 1865. About 500 Lenoir engines, between 6 and 20 hp, were built mainly to drive printing presses, water pumps, and machine tools.

Late in 1860 Nikolaus Otto and his brother, Wilhelm, learned of the Lenoir engine and built a copy. But unable to get a patent, in 1861, Otto built another engine using a fuel charge compressed before ignition but it broke after running for a few minutes and Otto's brother gave up on the idea.  In 1862 and 1863, Otto tried to improve the the design with the help of mechanic Michael J. Zons but he was running out of money and had to get a job.

In 1864, Otto and Zons formed a company (Deutz AG) financed by Eugen Langen. Their new engine ignited coal gas (then used for gas lighting) to create a vacuum, and atmospheric pressure to drive the piston. It used less than half the gas of the Lenoir engine, but produced only 3 hp and required up to 13 ft (4.0 m) headroom. Yet it was a commercial success and by 1875 the company was selling 634 engines a year. 

In 1872 the American engineer George Brayton built the first commercial engine to use liquid fuel (kerosene and oil). It differed from other piston engines in that the fuel/air mixture burnt progressively at constant pressure as it moved from a compressor cylinder and reservoir to a working/expansion cylinder. Brayton cycle engines were displayed at the Centennial Exposition, in Philadelphia in 1876, and at the 1878 Paris Exhibition and were considered the first safe and practical oil engine. In 1881 John Philip Holland used a Brayton engine to power the world's first successful self-propelled submarine, the Fienian Ram.

Note the centrifugal speed governor on top of the engine.

Meanwhile in 1876, Otto's manager, Gottlieb Daimler introduced Franz Rings and Herman Schumm who worked with Otto on an engine design using in-cylinder, fuel/air compression. It was a single cylinder, four stroke engine operating on the "Otto cycle" and the first modern internal combustion engine.

1. On the downward piston stroke (intake) a mixture of coal-gas and air was sucked into cylinder.

2. On the upward stroke (compression) the piston compressed the gas/air mixture and, at the top of the stroke, the fuel mixture was ignited by a flame (on later engines, by an electric spark).

3. On the downward stroke (power) the hot expanding mixture drove the piston down.

4. On the upward stroke (exhaust) the exhausted gas was forced from the cylinder.

This meant that the engine delivered power only once every four strokes and some of this had to be used to suck in a new charge, compress it and push out the exhaust gases on the other three strokes while also overcoming friction. This required a flywheel to store energy.

In the next 17 years, Otto sold more than 50,000 engines, all of them stationary engines. When Gottlieb Daimler proposed designing a smaller engine for transport vehicles, Otto was not interested. So, Daimler formed a new company with Wilhelm Maybach and avoided royalty payments to Otto when he discovered a four cycle engine had been patented in 1862 by Beau De Rochas, and that invalidated Otto's patent.