Analysis of Power (Energy) Losses on Spool Valves of Hydraulic Mining Machines

The world's leading manufacturers of hydraulic equipment: Boschrexroth, Atos, PONAR Wadowice, etc. are constantly working hard to improve the design of hydraulic equipment. In recent years, the quality of hydraulic equipment, including hydraulic valves, has been significantly improved. But still, the efficiency of hydraulic equipment, in terms of energy losses, leaves much to be desired. By such an important indicator as efficiency factor, the hydraulic drive of mining machines is much inferior to the electric drive. The paper presents an analysis of one of the main elements of the control system of hydraulic drives - the hydraulic distributor. Using the example of the most widely used typical spool distributor, it is shown that energy (pressure) losses in hydraulic distributors occur due to vortex formation (turbulence) in separate parts of the hydraulic distributor. The cause of vortex formation is sharp changes in the cross-section of the liquid flow (contraction, expansion), as well as the presence of sharp changes in the direction of the flow. All these factors are well illustrated in the KompasFlow programme, which is based on computational fluid dynamics and is a version of the FlowVision software package integrated into KOMPAS-3D as an application. Visualisation layers show specific sections of the hydraulic distributor in which there are changes in flow direction, pressure and velocity values, and areas of turbulence. Visualisation of the fluid flow in the spool hydraulic distributor clearly confirms the fact that the currently existing designs of hydraulic distributors do not allow to exclude completely or minimise the number of vortex formation zones. It is necessary to create a new design of the hydraulic distributor operating on other, different principles from the existing one. The new design of the distributor should completely exclude or minimise the number of zones of possible turbulence occurrence and provide a corresponding reduction in energy (pressure) losses on the hydraulic distributor. The obtained results of the research can be used in real production.