Glow tube ignition

A glow tube ignition consists of an externally heated, continuously glowing tube in the cylinder head of the first gasoline engines and was used until shortly after the beginning of the 20th century. The glow tube ignited the fuel mixture.

Gottlieb Daimler and Wilhelm Maybach made the gas engine developed by Nikolaus August Otto suitable for the use of liquid fuels, especially gasoline . In 1883 Daimler and Maybach registered a so-called "gas engine with hot-tube ignition" under the patent number DRP 28022. It was the first high-speed four-stroke gasoline engine in world history. The glow tube ignition, together with other inventions, such as the cam groove control of the exhaust valve, made "high-speed" engines possible for the first time. Up until then, four-stroke engines based on the Otto principle were running at speeds of around 150 rpm, but Daimler and Maybach achieved 600 rpm for the first time, and later 900 rpm.

The high-voltage ignition with an ignition spark through the ignition coil and interrupter did not emerge until more than two decades later, but it replaced glow tube ignition in all engine construction.

Only the miniature motors used today in model construction, so-called glow igniter motors , still work according to a similar principle. The principle of every ignition is the introduction of the required activation energy into the ignitable mixture to start the oxidation . The determining factor is the so-called cetane number . In the case of diesel fuels , the compression end temperature is sufficient to initiate ignition; in glow-ignition engines this is supported by a glow element located in the combustion chamber. For fuels with a very high activation energy or high octane number , external ignition is used: by means of a spark plug or an open flame in the case of glow tube ignition.