| Gearbox is an indispensable important component of vehicle transmission system,as the housing not only plays a supporting role to offer the closed protection function for each part in the housing and make the transmission form a closed internal flow field,but also has an important impact on the performance of the whole vehicle driving system.The gear box will be excited by all kinds of load in the normal working process,these exciting force are likely to cause the gear box produce larger deformation and stress.If the housing is too weak,the housing will be caused damage or fatigue problem.In the machinery industry,in most cases the lubrication of lubricating oil plays roles in the friction and gearboxes are also not exceptional,so there are a lot of reasonable lubrication systems in transmission.If insufficient amount of lubricating oil in the lubrication system and cooling ability is poor,it would make the lube oil temperature too high,so the viscosity of the lubricating oil will fall down accordingly,and the surface oil films on the parts that have mutual friction will be thinned,while in gearbox,the surface oil film on the gear that is mainly for meshing get thinner,so it is easy for the meshing surface to have agglutination damages.For the bearings,if the oil film gets thinner,due to the contraction principle,it is possible for the bearing of the mechanical parts to have the conditions of seizure,being burned and etc.On the contrary,if the amount of lubricating oil in the lubrication system is too much,it will increase the loss of the stirring oil in gearboxes,which affects the efficiency delivery efficiency of the gearbox.In the process of designing the gearbox,therefore,in order to make the transmission to meet the needs of all kinds of working conditions,should the corresponding structural strength,fatigue as well as the lubricating conditions of the transmission lubrication system in the gear box should be taken into consideration.Taking the gear box of the heavy buses from some company as the research object,while verifying the static intensity and predicting the fatigue life,the article puts forward the static intensity verification and the relevant fatigue analysis under two kinds of extreme conditions.At the same time,according to the lubrication situation of the internal flow field in the housing,the article respectively analyzes the lubrication effects of the internal flow fields in housing under different working conditions.First of all,the geometric processing and the necessary model simplification of the gear box housing as well as the discretization of the simplified model have been executed and the finite element method for the housing statics analysis is applied to check if its staticstrength meets the requirement.For fatigue life prediction of the housing,on the basis of statics analysis results,the fatigue life analysis is carried out for the housing.At the same time,when checking the static strength in housing,a large number of literatures have only analyzed the housing under two kinds of working conditions,first gear and reverse gear,but does not take into account the influence of the dynamic load of the driving system.Therefore when checking the intensity,this paper proposes the intensity verification under two extreme conditions.Finally,for the simulation of internal flow field,before the analysis,the gear box housing,bearing,rotating gear and other internal structure need the necessary simplification.The housing inner surface,all holes in closed housing,housing as well as all gears and shafts constitutes a model of a closed internal flow field.It is respectively simulated that in the fourth gear,with the first axis input speed of 1500 r/min and 2000r/min,the impact of different lubricating oil heights on the lubrication results within the internal flow fields of the housing. |
