Lubrication Performance Research Of Urban Rail Transit Transit Gearbox

With the development of China’s urban rail transit industry towards high-speed,heavy-duty direction,the carrying capacity and transmission speed of urban rail transit train gear box need to be further improved.The lubrication performance of the urban rail transit gearbox has a great influence on its carrying capacity and transmission speed,so it is very important to study the lubrication performance of the urban rail transit gearbox.The lubrication performance of the urban rail transit gearbox mainly includes gear lubrication regime,effective lubricant amount of the gearbox,thermal balance temperature and efficiency of the gearbox,leakage of the labyrinth seal of the gearbox,and performance of the lubricant.The lubrication regime of the gear determines the additive type of the lubricant.The effective amount of lubricant in the gearbox affects the thermal balance temperature and efficiency of the gearbox.Leakage of the labyrinth seal on the gearbox reduces the amount of available lubricant.The distribution of the pressure field in the gearbox determines the labyrinth seal inlet pressure.The viscosity of the lubricant also directly affects the thermal balance temperature and efficiency of the gearbox.In this paper,the regime of lubrication of gears,the effective amount of oil in the gearbox,thermal balance temperature and efficiency,the leakage of labyrinth seals,and the performance of lubricants are studied.The main research contents are as follows.(1)Based on the AGMA 925-A03 standard and the operating conditions of the urban rail transit gearbox,this paper establishes the gear lubrication model for urban rail transit.The calculation and analysis show that the specific film thickness and film thickness of the tooth surface at the constant speed condition is the largest,followed by the deceleration condition,the secondary acceleration condition,and the first acceleration condition.The analysis shows that the specific film thickness and the film thickness of gear tooth surface decreases as the tooth surface roughness increases.The film thickness and the specific film thickness of the gear tooth surface increase as the viscosity of the oil increases.The gears of the urban rail transit gearbox are in the regime of boundary lubrication in the first-acceleration and second-acceleration conditions,and the gears are in the regime of mixed lubrication under constant speed and deceleration conditions.(2)The simulation analysis of the flow field of the urban rail transit gearbox using the computational fluid dynamics method is carried out on constant speed conditon of the urban rail transit gearbox.According to the flow field simulation results,the internal flow channel structure of the gearbox is optimized,so that the internal fluid resistance of the box is reduced and the effective lubricant amount is increased.The influence of the depth of oil immersion of the gear and the speed on the amount of effective lubricating amount in urban rail transit gearbox was studied.The results show that the increase in the gear speed and the depth of gear immersion will increase the effective lubricant amount of the urban rail transit gearbox.The immersion depth of the rail transit gearbox was determined.(3)According to the oil immersion depth of the gears,the churning power loss of the urban rail transit gearbox was calculated,and the thermal network model of the urban rail transit gearbox was established.After calculation,the thermal balance temperature of urban rail transit gearbox is obtained.After analysis,the urban rail transit gearbox has an increase in the thermal balance temperature of the oil in the housing,input shaft bearings,output shaft bearings,and gears,as the input shaft speed increases,the viscosity of the lubricant increases,and the thermal conductivity of the housing decreases.With the increase of the depth of oil immersion,the thermal balance temperature of the lubricants in the urban rail transit gearbox first decreases and then increases.The efficiency model of the urban rail transit gearbox was established.It was concluded that the maximum power loss of the churning oil under the constant speed conditions was the largest,and the churning power was lower under the first-order acceleration and deceleration conditions.As the input shaft speed increases,the efficiency of the urban rail transit gearbox increases first and then decreases.As the input torque increases,the efficiency of the urban rail transit gearbox increases until the efficiency value stabilizes.As the viscosity increases,the efficiency of the urban rail transit gearbox increases first and then decreases.(4)According to the distribution of the pressure field inside the urban rail transit gear box,the inlet pressure of the labyrinth seal is obtained.According to the theories of thermodynamics and fluid mechanics,a square labyrinth seal mathematical model was established.Solve the square labyrinth seal leakage formula by iterative method.The influence of the geometric parameters of the square labyrinth seal on the leakage is studied by the flow field simulation method.The results show that as the pressure difference,the radius of the rotating shaft,and the seal gap increase,the leakage of the square labyrinth seal increases.As the speed increases and the cavity width increases,the leakage of the labyrinth seal decreases.As the depth of the square sealed cavity increases,the leakage decreases first and then increases.As diamond-shaped cavity angle increases,diamond labyrinth seal leakage increases.When the conditions are the same,the leakage of the circular labyrinth seal is less than that of the square labyrinth seal,and also less than the leakage of the diamond labyrinth.According to the above research results,the labyrinth seals of the three urban rail transit gearboxes are optimized.The results show that the leakage of the labyrinth seal of the optimized urban rail transit gearboxes is reduced.(5)An urban rail transit gearbox test rig was built.The thermal balance temperature of each key node was measured by the urban rail transit gear box rig test.The error between the bench test measurement results and the thermal equilibrium temperature calculated by the thermal network method in Chapter 4 is within 5%.The test verifies the effectiveness of the thermal network model of the urban rail transit gearbox.The rig test verifies that the thermal balance temperature of the key components of the urban rail transit gearbox decreases first and then increases with the i ncrease of the oil immersion depth.The rig test verifies that with the increase of input torque,the efficiency of the urban rail transit gearbox first increases and then tends to be stable.Based on the frequent starting conditions and tribological analysis design of urban rail transit gearbox,the oil parameters of the urban rail transit gearbox are obtained.A 48-hour start-stop test was performed on the urban rail transit gearbox test rig using the lubricant formulated according to the design parameters to verify the rationality of the design parameters of the lubricant for the urban rail transit gearbox.The effect of viscosity,viscosity index and extreme pressure anti-wear additives on the lubrication performance of the urban rail transit gearbox was studied by rig test.The research results show that with the increase of the viscosity of lubricant,the temperature rise of the bearing and the lubricant of urban rail transit gearbox increase,and the efficiency of urban rail transit gearbox decreases.As the viscosity index of lubricants increases,the temperature rise of the bearing and the lubricant of urban rail transit gearbox decrease,and the efficiency of urban rail transit gearbox increases.Lubricant extreme pressure anti-wear additives can reduce the temperature rise of the bearing and the lubricant of urban rail transit gearbox and improve the efficiency of the gearbox.