Gear Pump Performance Degradation Process Temperature Rise Modeling And Maintenance Strategy Optimization

As one of the power components of hydraulic systems,gear pumps are the"heart" of hydraulic systems,and are widely used in aerospace,military and civil applications because of their simple structure and ability to adapt to working conditions.The reliability of gear pump performance has a key role in the safe operation of the system,so the study of gear pump performance degradation process and the timely and correct implementation of preventive maintenance activities for gear pumps can effectively improve the reliability,safety and economy of system operation.Based on this,this paper takes the external gear pump as the research object and starts the research from the following aspects:(1)To analyze the wear degradation mechanism of gear pumps,temperature is selected as a characteristic parameter to reflect the degradation of gear pump performance,and the relationship between gear pump heat generation and gear pump wear degradation is analyzed based on the power loss method,and the analysis results show that as the wear degradation of gear pumps increases,the power loss increases and the heat generation increases,resulting in low gear pump efficiency and finally the temperature increases.At the same time,the simulation analysis of gear pump temperature change using AMESim software,the simulation results show that the gear pump efficiency will be reduced along with the gear pump and its oil temperature increase,which can provide a theoretical basis for modeling the degradation process of gear pump performance based on temperature.(2)The performance degradation data of the gear pump is obtained through the gear pump performance degradation test,and the test data is preprocessed to provide data support for the gear pump degradation process modeling.Considering the influence of ambient temperature,the temperature difference between the gear pump temperature and ambient temperature is selected as the degradation quantity and its degradation characteristics are analyzed.The analysis results show that the temperature difference data has certain random fluctuations but the overall trend is rising,and the Wiener process model with random and drift terms combined with the characteristics of temperature difference data can better describe the performance degradation process of gear pumps.(3)Three Wiener process models are constructed based on the temperature difference data to describe the performance degradation of the gear pump.A two-stage parameter estimation method is adopted,and the parameters in the degradation models are calculated using the maximum likelihood estimation method and the least squares method,respectively.The best fit of the nonlinear degradation model in exponential form is determined by combining statistical indicators,and its corresponding distribution function and failure probability density function are given,which can provide some reference for the performance degradation modeling of gear pumps and support the degradation model for the subsequent establishment of preventive maintenance optimization model.(4)A cycle inspection plan and preventive replacement strategy are proposed for the performance degradation process of gear pumps.The current degradation level of gear pumps is obtained through the cycle inspection plan,which is compared with the replacement threshold to implement replacement activities,and the inspection interval and preventive replacement threshold are optimized with the objective of minimizing the long-term operating cost rate.Based on this,a preventive maintenance strategy for gear pumps with periodic inspections and variable thresholds is further proposed.Considering the imperfection of maintenance and the influence of the number of repairs on the strategy,the number of repairs is taken as one of the decision variables,and a degradation rate adjustment factor is introduced to describe the change in the degradation rate of gear pumps after each repair.Meanwhile,the optimal maintenance strategy is obtained by optimizing the inspection interval,the number of preventive maintenance and the preventive maintenance threshold corresponding to each preventive maintenance with the lowest longterm operating cost rate of the gear pump as the optimization objective.