Vaporizing oil engine
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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. 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 vapor 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.
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[edit] Early Oil Engines
The earliest mention of an oil engine was by Street, in his English patent of 1791. The earliest working engine was built by Julius Hock, of Vienna, in 1870. Hock's was a non-compression engine, not unlike Lenoir's. Others made refinements to the oil engine; Priestman, Brayton and Capitaine are some of the more notable. However, it was Herbert Akroyd Stuart's design that was the most successful.
[edit] Herbert Akroyd Stuart
Stuart's oil engine design was simple, reliable and economical. The engine utilized a combustion chamber, or "vaporizer," separated from the main part of the cylinder by a narrow passageway. Vaporization of the fuel is accomplished by the injection of liquid fuel onto the hot inner surface of the vaporizer. The surface is sufficiently hot to cause ignition of the mixture of fuel and air when compression is completed. The heat of combustion is enough to maintain the high temperature of the vaporizer surface.
To start, the vaporizer is heated by a separate lamp. After five to ten minutes, oil is injected onto the hot vaporizer surface, where it quickly gassifies, and the engine is rotated by hand in the standard fashion.
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 vaporizer. The vapor of the oil is almost entirely confined to the vaporizer chamber. This cloud of hot oil vapor 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 vaporizer. Just as compression is completed, the mixture is just right to support combustion and ignition occurs.
[edit] First production vaporizing oil engine
Richard Hornsby & Sons was a large manufacturer of steam engines and agricultural equipment in 1891 when they entered into an exclusive contract with Herbert Akroyd Stuart to manufacture what would be known as the Hornsby-Akroyd oil engine. The engine was hugely successful. During the period from 1891 through 1905, a total of 32,417 engines were produced.
