Analysis On The Flow Field Of Straddle Monorail Train Gear Box

The straddle monorail gearbox is an important part of the bogie,and it is also the key equipment for power transmission during the operation of the train.In the process of high-speed operation,poor lubrication,the operation of the bearing in the gearbox and the high temperature and high pressure generated by the meshing of the gear teeth will cause wear,gluing and pitting between the bearing and the gear,thereby reducing the service life of the gearbox,the safe and stable operation of the train will also be affected.The main research object of this paper is the gearbox of the straddle monorail train.Firstly,the geometric structure of the gearbox is reasonably simplified,and then the simulation is carried out based on the grid overlap technology in star-ccm +software.The three factors of gear forward and reverse rotation,initial oil injection and driving speed are studied and analyzed on the flow field and pressure field in the gearbox and the lubricating oil of each oil inlet and return hole of the bearing.The effect of mass flow.The research results provide a theoretical basis for the design and improvement of the detailed structure of the lubricating oil flow channel of the gearbox,and have certain guiding value.Combined with the structure and working principle of the gearbox,Solidworks software is used to reasonably simplify the gearbox and make assumptions,and remove unnecessary bolt holes,round holes,fillets and chamfers and other components that have little effect on the simulation calculation.A computational model of the watershed inside the gearbox.Based on the incompressible gas-liquid two-phase flow in the gearbox,the orthogonal horizontal working table of three influencing factors(forward and reverse,initial oil injection and driving speed)is set by using the finite element analysis and three factor mixed orthogonal test method.The internal flow field,velocity field and pressure field of the gearbox under different working conditions are simulated,and the transient change law of gas-liquid two-phase distribution in the internal flow field of the gearbox is analyzed The influence of the three influencing factors on the internal flow field characteristics of the gearbox and the distribution state of the oil in the gearbox and the bearing are analyzed.At the same time,the changes of fluid pressure,flow velocity,circulating flow direction(outlet and inlet direction)and velocity law are analyzed,and the transient motion law,velocity vector diagram,volume fraction and pressure cloud diagram of the lubricating oil in the gearbox are obtained;Observe the mass flow of lubricating oil in the oil inlet and return port of each bearing,and analyze its changes with the working conditions;Through the method of range analysis,the influence of various factors on the quality and flow of lubricating oil in the gear and the oil inlet and return holes of each bearing is found,and the following conclusions are drawn:(1)When the lubricant enters the gear meshing position,the oil is blocked and the pressure in the meshing zone increases,forming a positive high-pressure zone;when it leaves the meshing position,the volume increases and the pressure in the meshing zone decreases,forming a negative pressure zone;the fluid velocity in the gear meshing zone reaches its maximum.(2)Forward and reverse rotation has the greatest impact on the time it takes for the lubricating oil to reach the gear meshing position.The time required for the forward rotation to reach the gear meshing area is much less than the time required for the reverse rotation,and the extreme difference is 0.0378s;appropriate acceleration of the gear speed can accelerate the delivery of lubricating oil to the gear position and lubricate the interior of the box.(3)Through the extreme range analysis of orthogonal simulation results,it is concluded that the influences of forward and reverse rotation,initial oil filling amount and driving speed on the lubricating oil mass flow rate of each oil inlet and oil return hole are as follows: No.1,No.2 and No.3 bearings(oil inlet holes A,B and C):forward and reverse rotation,initial oil filling amount and driving speed;No.1,No.2and No.3 bearings(oil return hole D): initial oil filling amount,forward and reverse rotation,and running speed;No.1,No.2 and No.3 bearings(oil return hole E): initial oil filling amount,driving speed,positive and negative rotation;No.4 and No.5bearing(oil inlet F): initial oil quantity,driving speed,positive and negative rotation;No.4 and No.5 bearing(oil inlet G): forward and reverse rotation,driving speed and initial oil filling amount;No.4 and No.5 bearing(oil return hole I): driving speed,forward and reverse rotation,initial oil filling amount;No.6 bearing(oil inlet H):driving speed,initial oil filling amount,positive and negative rotation;No.7 bearing(oil inlet J): initial oil quantity,driving speed,positive and negative rotation;No.8bearing(oil inlet K): initial oil quantity,driving speed,forward and reverse rotation.The main problems existing in the internal structure of the existing gearbox:The high-speed shaft has high rotation speed and large heat generation,so a sufficient amount of lubricating oil is required to dissipate heat.When the gear reverses,the lubricating oil cannot reach the meshing area for lubrication in time.Therefore,the mass flow of oil entering the oil inlet hole of the high-speed shaft bearing is less,which may easily lead to high temperature of the high-speed shaft bearing,which may seriously affect the normal operation of the gear.