Early fuel Injection System
Diesel's original engine injected fuel with the assistances of compressed air, which atomized the fuel and forced it into the engine through a nozzle. The nozzle opening was closed by a pin valve lifted by the camshaft to intiate the fuel injection before top dead centre(TDC).This is called an air-blast injection.Deving the three stage compressor used some power but the efficiency and net power output was more than any other combustion engine at that time.
Diesel engines in service today raise the fuel to extreme pressures by mechanical pumps and deliver it to the combustion chamber by pressure-activated injectors without air. With derect injected diesels, injectors spary fuel through 4 to 12 small srifeces in its nozzle.The early air injection diesels always had a superior combustion without the sharp increase in pressure during combustion. Research is now being performed and patents are being taken out to again use some form of air injection to reduce the nigrogen oxide and pollution, reverting to Diesel's original implementation with its superior combustion and possibly quieter.
In all major aspects, tne modern diesel engine holds true to Rudolf Diesel original design, that of igniting fuel by compression at an extremly high pressure with in cylinder. With much higher pressures and high technology injectors, present-day diesel engines use the so-called solid injection system applied by Herbert Akroyd Stuart for his hot bulb engine . The indirect injector engine could be considered the latest development of these low hot bulb ignition engines.
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