Hornsby-Akroyd oil engine
The Hornsby-Akroyd oil engine was the first successful design of internal combustion engine using "heavy oil" as a fuel. It was the first to use a separate vapourising combustion chamber and is the forerunner of all hot-bulb engines.
Early internal combustion engines were quite successful running on gaseous and light petroleum fuels. However, due to the dangerous nature of gasoline and light petroleum fuel, legal restrictions were placed on their transportation and storage.[clarification needed] Heavier petroleum fuels, such as kerosene, were quite prevalent, as they were used for lighting. However, heavier oils posed specific problems when used in internal combustion engines.
Oil used for engine fuel must be turned to a vapour state and remain in that state during compression. Furthermore, the combustion of the fuel must be powerful, regular, and complete, to avoid deposits that will clog the valves and working parts of the engine.
Early oil engines
The earliest mention of an oil engine was by Robert Street, in his English patent no. 1983 of 1794. There is also strong evidence to suggest that Robert Street built a working version of his engine according to Horst O. Hardenberg. Other oil engines were built by Nicéphore Niépce, Etienne Lenoir, Siegfried Marcus, Julius Hock of Vienna and George Brayton in the 19th century. All of these engines with the exception of Brayton's were non-compression.
Herbert Akroyd Stuart
Akroyd Stuart's first prototype engines were built in 1886. In 1890, in collaboration with Charles Richard Binney, he filed Patent 7146 for Richard Hornsby and Sons of Grantham, Lincolnshire, England. The patent was entitled: "Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapour or Gas and Air".
Stuart's oil engine design was simple, reliable and economical. It had a comparatively low compression ratio, so that the temperature of the air compressed in the combustion chamber at the end of the compression stroke was not high enough to initiate combustion. Combustion instead took place in a separated combustion chamber, the "vapouriser" (also called the "hot bulb") mounted on the cylinder head, into which fuel was sprayed. It was connected to the cylinder by a narrow passage and was heated either by the cylinder's coolant or by exhaust gases while running; an external flame such as a blowtorch was used for starting. Self-ignition occurred from contact between the fuel-air mixture and the hot walls of the vapouriser.
The Stuart engine is of four cycle design. During the intake stroke, fresh air is inducted into the cylinder through a mechanically operated intake valve. Simultaneously, oil is injected into the vapouriser. The vapour of the oil is almost entirely confined to the vapouriser chamber. This cloud of hot oil vapour is too rich to support combustion. On the compression stroke of the piston, the fresh air is forced through the narrow neck and into the vapouriser. Just as compression is completed, the mixture is just right to support combustion and ignition occurs.
By contracting the bulb to a very narrow neck where it attached to the cylinder, a high degree of turbulence was set up as the ignited gases flashed through the neck into the cylinder, where combustion was completed. As the engine's load increased, so did the temperature of the bulb, causing the ignition period to advance; to counteract pre-ignition, water was dripped into the air intake.
First production oil engine
Akroyd-Stuart's engines were built from 26 June 1891 by Richard Hornsby and Sons, a large manufacturer of steam engines and agricultural equipment, as the Hornsby Akroyd Patent Oil Engine under licence and were first sold commercially on 8 July 1892. It was the first internal combustion engine to use a pressurised fuel injection system. The engine was hugely successful. During the period from 1891 through 1905, a total of 32,417 engines were produced.
- "The Akroyd Oil Engine". Ray Hooley's - Ruston-Hornsby - Engine Pages. Archived from the original on 2011-05-24. Retrieved 2007-07-29.
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- Wrangham, D.A. (1956). The Theory & Practice of Heat Engines. Cambridge University Press. p. 664.
- Ransome-Wallis, Patrick (2001). Illustrated Encyclopedia of World Railway Locomotives. Courier Dover Publications. p. 27. ISBN 0-486-41247-4.