A hot-tube ignitor was an early device that fit onto the cylinder head of an

internal-combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combust ...

, used to ignite the compressed fuel/air mixture by means of a flame heating part of the tube red-hot. A hot-tube ignitor consisted of a

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

porcelain Porcelain () is a ceramic material made by heating substances, generally including materials such as kaolinite, in a kiln to temperatures between . The strength and translucence of porcelain, relative to other types of pottery, arises mainl ...

tube, closed at one end and attached to the cylinder head at the other and an adjustable burner that could be moved to position its flame at any point along the length of the tube.

Operation

The compression stroke in the cylinder pushed some left over combustion products in the tube, followed by fresh (unburned) fuel/air mixture. When the compression was enough that the fuel reached the red-hot area of the tube, ignition occurred. On early designs, ignition timing was adjusted by adjusting the position of the red-hot spot on the tube—this was accomplished by moving the burner along the length of the tube. Most later styles used a fixed burner and varied tube lengths to change ignition timing.

Disadvantages

Hot-tube ignitors had many problems, most caused by the sudden pressure changes in the tube because of the operation of the engine and the high temperature of the tube. It was extremely difficult to find materials that were both durable enough for these conditions and inexpensive. Also important was never setting the burner flame where it would heat the tube white hot, which would rapidly damage the tube and could cause it to burst explosively. This mistake was made often. The tubes used were typically 6 to 12 inches long, which tended to make them impractical for use on anything but large engines (e.g., stationary motors in factories). Tubes rarely lasted longer than a year before needing replacement, especially when the engines were fueled with high sulfur gases like unpurified

producer gas Producer gas is fuel gas that is manufactured by blowing a coke or coal with air and steam simultaneously. It mainly consists of carbon monoxide (CO), hydrogen (H2), as well as substantial amounts of nitrogen (N2). The caloric value of the produce ...

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

References

*{{cite book , last = Hiscox , first = Gardner Dexter , title = Gas, Gasoline, and Oil-Engines including Producer-Gas Plants A complete and practical work treating on gas, gasoline, kerosene, and crude petroleum oil-engines, including producer-gas plants for gas-engine owners, gas engineers, and intending purchasers of gas-engines, fully describing and illustrating the theory, design, construction, and management of the explosive motor for Stationary, Marine, and Vehicle Motor Power , edition = Twentieth edition, revised and enlarged , publisher = Norman W. Henley Publishing Company , location = New York , year = 1911 , pages = 122–127 Ignition systems

Operation

Disadvantages

See also

References