Sunday 14th March 1909

Prosper L’Orange, Benz engineer, was issued with a patent for a pre-combustion chamber type diesel engine that led to the manufacturing of diesel-powered automobiles. The precombustion chamber connects to the engine cylinder via a restricted passage, or burner. In operation, a narrow cone of fuel is sprayed down towards the burner by the single orifice injector nozzle. At this time the technology did not exist to manufacture nozzles with multiple orifices and diesels used high pressure air to spray the fuel directly into the cylinder. L’Orange also discovered that indirect injection diesel engines ran more smoothly and quietly than direct injection engines. Use of a precombustion chamber also reduced stress on the engine’s structure, so that it could be made less heavy than a direct injection engine. However, indirect injection engines require higher compression ratios, about 20:1, to compensate for the greater surface to volume ratio causing more heat loss from the cylinder charge. They are also more difficult to start when cold, therefore the precombustion chambers are fitted with electrically heated glowplugs.