INFLUENCE OF THE METERING METHOD ON THE CHARACTERISTICS OF A DIESEL DISTRIBUTOR FUEL PUMP

Objectives The aim of the study is to improve the performance of the metering system and thus enhance control over the cyclical supply of fuel to a diesel distributor pump. The results of a study of the effect of a new metering method on the characteristics of a distributor fuel pump are presented. Methods Following mathematical analysis, a mathematical model of the working process of the fuel supply system, based on a new metering approach employing the "decay of discontinuity" method, was compiled.The model comprises a system of differential equations for continuity and momentum alongside mass balance equations for describing the boundary conditions for various cavities of the fuel system, i.e. above the plunger, under the valve, above the valve cavities and in the nozzle. The differential equations take into account the two-phase nature of the gas-liquid medium in the injection cavities and metering system, as well as the design features of the pump. An expression for the stroke of the metering plunger in the new system is given. Results The theoretical and experimental characteristics of a fuel supply system employing the proposed metering system are considered. Diagrams showing maximum injection pressures, which depend on the stroke of the metering plunger at various strokes of the injection plunger and alteration of maximum injection pressure of the nozzle depending on the rotation speed of the cam shaft, are provided. The characteristics of the fuel supply system of the pump for various spring stiffness of the metering plunger are also provided in diagram form. The comparative parameters of the fuel supply process are presented for the conventional and new metering methods. The features of the use of diesel high-pressure distributor pumps, their design and operational features are described. The advantages of the metering system proposed by the author are presented in terms of its influence on the fuel injection process. A comparative evaluation of metering methods used in contemporary distributor pumps for diesel engines is given. Conclusion The results of the experiments confirmed the suitability of the new metering method for use in diesel engines.