Energy Efficiency Improvement of Hydraulic Indirect Elevator

This article addresses the current issue of energy consumption in the hydraulic drive systems of working machines, with particular emphasis on elevators. This paper describes the results of experimental comparative research and estimation of energy and time consumption for two drive systems of a hydraulic indirect elevator. The purpose of this article is to compare the energy consumption of a typical multi-valve system (MV) system with that of an innovative new electro-hydraulic drive (EHD) system with a variable speed pump. The EHD system uses a frequency converter with an energy recovery module to control the speed of the car in both directions and the return of potential energy during the lowering cycle. The comparison of these drive systems was performed under the same conditions, realizing the same elevator work cycles. This paper proposes methods for estimating the energy consumption of an MV system based on measurement data collected during an experiment. The results indicate that the EHD system was less energy-intensive, even at below 60%. The smaller the load mass, the shorter the operating time of the EHD system compared to the MV system. The introduced coefficients defining the energy consumption per unit of mass and payload displacement showed more than twice the decrease in energy demand during lifting and energy recovery possibility during lowering. The EHD system provides the same coefficient values regardless of the distance traveled, which makes it a predictable system, in contrast to the MV system, especially during lowering cycles. The benefits of the EHD also include a less complex hydraulic system (elimination of most valves).