Development of an energy-efficient control system for the hydraulic drive of mobile construction machines

Abstract

Throttling-based flow distribution in the hydraulic drive of mobile construction machines remains a source of losses eliminated neither by raising the working pressure nor by improving the volumetric characteristics of pumps: the differential absorbed by the spool and by the compensator is governed by the difference between the loads of simultaneously operating consumers. The discrepancy between the fuel economy claimed for load-sensing systems and the actual consumption in service persists, while the quantitative attribution of the gain to individual control actions remains poorly developed. The purpose of the work is to develop a control structure that reduces cycle energy consumption and to quantify the contribution of each control measure. An author's computational model of the energy balance of a six-phase working cycle of a 15-16 t single-bucket excavator with a 0,65 cu. m bucket covers throttle control, hydromechanical and electronic load-sensing control, and the proposed structure with the consumers divided between two independently regulated circuits, an adaptive differential setting of 0,8 MPa, pump unloading in pauses and recovery of the energy of equipment lowering. The cycle efficiency rises from 0,562 under throttle control to 0,830, the reduced fuel consumption falls from 11,85 to 7,67 kg per machine hour and turns out to be 28,3% below the standard calculated by the procedure of Order № 916/pr of the Ministry of Construction of Russia. Of the total 20,0% saving relative to classical load-sensing control, 11,6 percentage points came from splitting the flows between circuits according to the load level, 4,8 from lowering the differential setting, 2,8 from unloading during pauses and 2,3 from recovery. The main energy efficiency reserve is concentrated in the structure of flow distribution among consumers; energy storage and return yield a noticeably smaller effect, and priority in hydraulic drive upgrading belongs to circuit coordination algorithms.