Improving fuel efficiency of tractor diesel engines by upgrading injector nozzles

BACKGROUND: The reliability of a fuel supply system determines the performance of a diesel engine. The weakest part of it is injectors. The most common cause of failure of the injector nozzle is the disruption of the needle mobility due to obliteration of the spraying holes. AIM: Improving the fuel efficiency of a diesel engine by upgrading the injector nozzles. METHODS: To diminish the obliteration process, upgrade of the injectors by cutting a helical groove on the guide part of the needle was proposed. Commercial and upgraded injectors were used for the experiment. During the pouring process, the helical groove was filled with fuel, which served as a lubricant and increased the fuel supply. Fuel efficiency was assessed by the value of injection rate. The obliteration process was assessed by the gap resistance coefficient, defined as the ratio of fuel consumption at the end of the fuel pouring to fuel consumption at the beginning of the fuel pouring. RESULTS: As a result, the dependence of the gap resistance coefficient on the volume of the helical groove was obtained. When the total gap increases by 2 times (due to the screw channel), the fluid flow decreases by no more than 20%, and the gap filling coefficient is 0.8 ... 0.9. The dependences of the injection rate and unevenness of fuel injection on the fuel pump shaft rotation velocity were obtained. At the fuel pump shaft rotation velocity of 850...1100 rpm, the unevenness of fuel supply did not exceed 1...2%. When the rotation velocity decreases to 400...800 rpm, the unevenness increases to 2.7...16.1%. CONCLUSION: To diminish the process of obliteration of the spray gap, the reasonable volume of the helical groove should be 0.5...0.9 of the volume of the gap between the body and the nozzle needle.