Justification of the optimal operating time for the main pumps of a mining hydraulic excavator

As the pump operates and wears out, the gap in the friction pairs increases and the volumetric efficiency decreases, the pump flow gets reduced, which leads to increasing duration of working and auxiliary operations, the operating cycle of the excavator, a decrease in its productivity and excessive fuel consumption. Infrequent pump replacement can lead to a significant increase in fuel consumption and reduced excavator performance. If the pump is replaced prematurely, its service life will not be used to the full extent. In order to develop a method for establishing optimal operating hours that allow minimizing fuel consumption and the cost of replacing a pump, taking into account operating conditions, a mathematical model of the pump operation is proposed, which makes it possible to obtain an expression for determining the differentiated optimal value of operating time between replacements. A calculation method and a software algorithm have been developed in the MatLab Simulink software suite to calculate the rate of decrease in the volumetric efficiency, as well as to establish the influence of volumetric efficiency on the fuel consumption and performance of a hydraulic excavator to be utilized in the model using the example of the HPV375 pump of the Komatsu PC2000-8 excavator, Based on the proposed mathematical model of the main pumps operation, a method has been developed for calculating the differentiated operating time between replacements of the main pumps of a mining hydraulic excavator, taking into account the rate of decrease in volumetric efficiency, replacement costs and damage due to changes in productivity and excessive fuel consumption. The dependence of the rate of changes in the volumetric efficiency of the pump is presented for the excavation, viscosity, contamination and temperature of the working fluid parameters. A coefficient of “reserve of partial engine power transferred to the pump” is proposed, determined by the ratio of the difference between the average maximum and initial partial power to the value of the initial partial power, which allows estimation of the operating time of the main pumps without affecting productivity of the excavator.