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The paper deals with the existing Diesel nozzles optimisation of the conventional injection system pump - high pressure pipe - nozzle. The aim of the optimisation is to increase the injection rate of the nozzle by 9 %, lower the fuel consumption and reduce the emissions of the engine. Existing and optimized nozzles should feature the same inlet pressure, i.e. the same load on the pump allowing that the same pump may be used also for the redesigned nozzle. Redesigned was the tip of the nozzle. The nozzle was optimized by computer simulation. The prototype of the redesigned nozzle was then tested on the test stand and in the four - stroke air - cooled engine according to the 13-mode ECE R49 cycle. Explained is also the influence of fuel injection parameters on engine performance and emission. All test results are presented in the paper.

The paper deals with the optimisation process of existing engines and the compilation of data to allow future electronic control of fuel injection. The general trend is towards the development of high-pressure electronic injection with injection pressures exceeding 1500 bar and with the reduced injection timing. We based our research measurements of diesel engine on the above assumptions. The measurements were undertaken on an engine tester by means of an analyser, charge amplifiers, a needle lift transducer and pressure measuring sensors. Using the measuring instruments we measured the needle lift, injection pressures in the nozzle, combustion pressures, fluctuations of pressure in the charge and exhaust ducts in relation to the crankshaft angle,crank revolutions per minute, preinjection angle and engine loading. Moreover, we measured the fuel consumption, the temperature of cylinders and bridges between valves in the engine.