Numerical Simulation And Test For Critical Components Of 4Wd Vehicle Transfer Case

In order to research the drive characteristic of 4wd vehicle transfer case, computer numerical simulation method was applied. The research was going about several fields, such as:modal characters, force characters and gear drive lubrication characters.Firstly,the modal characters of transfer case was researched on two fields:calculate modal and test modal.3d model was build and finite mesh model was build by ANSYS Model. ANSYS Modal was applied to calculate the initial 18 steps parameters of free modal of transfer case, and the initial 7-18 steps parameters of free modal was corresponding to the initial 1-12 steps parameters of structural modal. Based on the test modal theory, DH5922 signal acquisition test system was applied to calculate the test modal parameters. Using the multipoint simulate single point pickup method and Lanczos eigen value solving method, arranging 28 test nodes, the initial 12 free modal parameters was calculated. By comparison,mode of vibrations in two different modal parameters was the same, max frequency error was 9.2%, the results of calculating and test modal was identical. The finite modal proved to be true.Secondly, based on automobile design theory and engineering practice, conditions was received and input loads was calculated; By building the Romax transfer case model and input the loads, the parameters of the force in gears and bears was received.Thirdly, the static and fatigue characters was simulated on the transfer case in simulation environment of ANSYS Workbench. By calculation, the characters of stiffness, intensity, fatigue of transfer case was received. The max principle stress of target architecture was lower than yield strength of meterials 189MPa,the maximum was 159MPa. The max deformation was 0.29mm and a kind of less. In fatigue conditions, constant amplitude and rate of load was input and fatigue characters of stress and strain was set. The max safety factor was 1.37, higher than 1.2, and the maximum zone was radial shape.Finally the research was focus on lubricating property of the first level cylindric spiral gears, and was proceed in CFD software Fluent. The first level gears fluid model was build and VOF two-phases model was chosen. Though defining the material parameters of air, oil, using UDF function to define the immersion oil depth of pinion, the two-phases transfer case fluid model was finished. Dynamic mesh technology was used to define the rotational speed of gears,k-ε viscous model was chosen and PISO solution algorithm was applied to calculate. In the condition of 23mm immersion oil,0-26 T, the volume fraction, pressure, velocity parameters was as follow. Air below gear mesh zone gradually increased, bubbles moved along side the pinion, oil level of both side gradually rised. The principal press numerical value was 0-800Pa, the principle velocity was lower than 0.9m/s.The fluid gradually thread though the mesh zone from top to bottom. The immersion oil depth of 3 conditions was 13,23,33 mm. Test was designed by making PMMA transfer case shell and building drive tester. High speed photography was applied to get the results.