Test study on the rotary oil circuit resistance characteristics and oil supply boundary of an NGW-type high-speed planetary gearbox

GONG Cunzhong; YOU Mingming; PENG Longlong; HU Yanan

doi:10.16578/j.issn.1004.2539.2026.04.013

Abstract：[Objective]When the external oil supply system pressure of an NGW-type high-speed planetary gearbox suddenly dropped significantly,internal transmission components were damaged within a short period of time.To determine the cause,a combined method of numerical calculations and bench tests was used to analyze the correlation between the sudden drop in oil supply pressure and the occurrence of the fault.To prevent similar incidents,a method for determining the oil supply boundary based on changes in vibration response was proposed.This method involves conducting a comprehensive investigation of the oil supply parameter boundaries to provide a basis for optimizing oil supply parameters.[Methods]To confirm the cause of the fault,firstly,a lubricating oil film calculation model for the planetary shaft was established,analyzing the theoretical oil demand for the planetary shaft.Secondly,a test bench for the rotary oil circuit of the gearbox was set up to clarify the resistance characteristics of this rotary oil circuit.Finally,a three-dimensional flow field model of the oil circuit was established to analyze the oil distribution inside the gearbox,clarifying the actual oil supply state of the planetary shaft during normal operation.To determine the oil supply parameter boundaries,the vibration response of the gearbox with high sensitivity to oil supply was used as a criterion for assessing oil sufficiency.A method involving gradually reducing the oil supply and incrementally loading while comparing changes in vibration response was employed to conduct the oil supply boundary investigation.[Results]The analysis and test results show that under normal supply pressure,the lubricating oil entering the gearbox meets the requirements of the planetary shaft.However,when the oil supply pressure suddenly drops,due to the resistance characteristics of the rotating oil circuit,the amount of oil entering the gearbox becomes very limited or even non-existent,which is the fundamental cause of the fault.The oil supply boundary investigation reveals that when the oil supply pressure and corresponding flow rate decrease to a certain extent,the gearbox enters an oil-starved state.The amplitude of the meshing frequency response is most sensitive to oil-starved operation and can serve as a criterion for assessing oil sufficiency.The research provides a basis for oil supply allocation and safety parameter settings in the oil supply system.