Intro
As early as 1863, the Frenchman Etienne Lenoir had test-driven a vehicle which was powered by a gas engine which he had developed. However, this drive plant proved to be unsuitable for installing in and driving vehicles. It was not until Nikolaus August Otto’s four-stroke engine with magneto ignition that operation with liquid fuel and thereby mobile application were made possible. But the efficiency of these engines was low. Rudolf Diesel’s achievement was to theoretically develop an engine with comparatively much higher efficiency and to pursue his idea through to readiness for series production.
The first working prototype of a combustion engine:
In 1897, in cooperation with Maschinen -fabrik Augsburg-Nürnberg (MAN), Rudolf Diesel built the first working prototype of a combustion engine to be run on inexpensive heavy fuel oil. However, this first diesel engine weighed approximately 4.5 tonnes and was three meters high. For this reason, this engine was not yet considered for use in land vehicles. However, with further improvements in fuel injection and mixture formation, Diesel’s invention soon caught on and there were no longer any viable alternatives for marine and fixed-installation engines.
“It is my firm conviction that the automobile engine will come, and then I will consider my life’s work complete.”
- Rudolf Diesel
:Rudolf Diesel
Rudolf Diesel (1858–1913), born in Paris, decided at 14 that he wanted to become an engineer. He passed his final examinations at Munich Polytechnic with the best grades achieved up to that point.
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| Rudolf Diesel |
Idea for a new engine
Diesel’s idea was to design an engine with significantly greater efficiency than the steam engine, which was popular at the time. An engine based on the isothermal cycle should, according to the theory of the French physicist Sadi Carnot, be able to be operated with a high level of efficiency of over 90%. Diesel developed his engine initially on paper, based on Carnot’s models. His aim was to design a powerful engine with comparatively small dimensions. Diesel was absolutely convinced by the function and power of his engine.
Mixture formation in the first diesel engines:
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Fuel injector
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Compressed-air injection
Rudolf Diesel did not have the opportunity to compress the fuel to the pressures required for spray dispersion, spray disintegration and droplet formation. The first diesel engine from 1897 therefore worked with compressed- air injection, whereby the fuel was introduced into the cylinder with the aid of compressed air. This process was later used by Daimler in its diesel engines for trucks. The fuel injector had a port for the compressed- air feed and a port for the fuel feed (2). A compressor generated the compressed air, which flowed into the valve. When the nozzle (3) was open, the air blasting into the combustion chamber also swept the fuel in and in this two-phase flow generated the fine droplets required for fast droplet vaporization and thus for auto- ignition.
A cam ensured that the nozzle was actuated in synchronization with the crankshaft. The amount of fuel to be injected as controlled by the fuel pressure. Since the injection pressure was generated by the compressed air, a low fuel pressure was sufficient to ensure the efficacy of the process.
References:
- Fundamentals of Automotive and Engine Technology by Konrad Reif
- writes of Konrad Reif
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