| Hydro-mechanical continuously variable transmission(HMCVT)is double power flow stepless transmission.Hydro-mechanical continuously variable transmission(HMCVT)put hydraulic static transmission(HST)and mechanical drive system in parallel,through a fixed axis gear pair and planetary gears carries out engine power distribution or the convergence of engine power and carries out stepless regulation in the range of expected speed by using the stepless speed regulation characteristic of pump-motor.This type of transmission makes full use of the high eff-iciency of mechanical transmission and the stepless speed regulation characteristics of hydraulic transmission,has advantages of high transmission power,good operation comfort and fuel economy,especially meets complex requirements of high-power tractor’s working condition.So,it is an important development direction in the future of high-power tractor.This paper was supported by Jiangsu Science&Technology Support Plan(BE2014134)and Jiangsu Union Innovation Fund(BY2014128-04),did a comprehensive research on the hydraulic mechanical stepless transmission theory,and combined with the domestic and foreign typical design scheme and tractors specific requirements designed a new type of hydraulic mechanical stepless transmission,this paper mainly study the following several aspects:1.To research the original prutotype(?)variable transmission.In view of the vibration of the transmission mechanism and aiming at reducing the transmission of vibration intensity,study the vibration of the transmission curve under the actual working condition.According to the actual working condition of vibration,found that the transmission problems and solve them in operation.2.Based on the original transmission scheme and on its basis to improve and put forward a new transmission scheme,and probes into the new transmission scheme of four kinds of possibility is demonstrated,and then determine a new transmission structure,space layout more reasonable solution.The determination of structural parameters of a new transmission scheme,lay the foundation for parametric modeling and analysis.3.Using the geometric transmission design of three axis type,no output half shaft structure,reduce the complexity of the transmission scheme,and easy to tear open outfit maintenance,compact structure,reduce the vibration of transmission,also make the design more concise and easy,easy to manufacture.4.Using solid modeling software Creo hydraulic mechanical stepless transmission structure design,mainly analyses the modeling process of gear design,the parameterized design of helical gear.Calculates and analyses the risk the size of the journal,and three-dimensional modeling was carried out on the main transmission parts.Three-dimensional modeling includes transmission,double row planetary gear output after the bus structure,bus structure,the planetary gear lubrication and cooling structure and body structure.5.Analysis on transmission box statics,and in the actual working condition of lower effect force and the strain and compared with the actual yield strength,then to analyze the design rationality of enclosure structure,provide scientific theory basis for the design of the transmission.6.Modal analysis,analysis to calculate the first ten order modal vibration mode and natural frequency.The mode diagram analysis and find out the larger area of stress and strain.After the modal analysis,harmonic response analysis,analysis of the case within the scope of the excitation frequency of dynamic response and trend,find out their frequency of maximum response,try to avoid in the design or away from,make a design more reasonable. |
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