A New Diesel Injection Pump with High Injection Rate, Its Influence on Smoke and Emissions

This report discusses some problems connected with the reduction of exhaust emissions and fuel consumption for direct injection Diesel engines; it indicates how they may be solved without modifying the basic power unit. The study was made on a standard production engine used in European heavy duty trucks. The effect of a number of individual variables was studied, including injection timing, injection rate, exhaust gas treatment (catalytic exhaust system), intake air pressure (including supercharging), charge dilution with exhaust gas recirculation, etc. After this first series of tests had been made, the effect of a combination of these variables was examined. To obtain the optimum results with a system providing a very fast injection rate, the effect of changes in the degree of turbulence was evaluated.

The results of the study demonstrate that the use of a pump which is able to provide very high injection rates enables an engine to operate with low values of NO₂ + HC with only marginal losses in power and fuel consumption, and at the same smoke level. The second part of the paper gives details of the FIAT DRF experimental injection pump which provided the very high injection rates needed for this programme.