| Petrol-electric hybrid is the common hybrid form of hybrid power supply, andpower-split device is the core component in a petrol-electric hybrid car. Differentialpower-split device (PSD) is that the traditional differential movement form is appliedto power-split device. Power-split device makes the power from the engine andelectric motor through a certain control algorithm coupled together to efficiently drivewheel to go forward, and the excess energy is recycled through a generator. Becausethe device adopts planetary transmission and compact structure, and has high gearspeed and more generate heat, the research of thermal characteristics of PSD forcooling and lubrication has important guiding significance. In this paper, the researchcontent is supported by the national natural science foundation project-"under thecondition of multi-field coupling PSD design theory and method for HEV"(projectNo.51075179). This paper first for PSD carries system overall temperaturecharacteristic research, and due to more use of bevel gears, then for bevel gear pairresearches the oil churning characteristics, and further analyzes its transient thermalcharacteristics under the influence of lubricating oil. In this paper, the main researchcontents, methods and conclusions are as follows:(1) A variety of types of power loss calculation models are introduced in detail,including gear mesh friction power loss, rolling bearing friction power loss, oilchurning power loss, windage loss and other friction power loss. The key parameterfor solving the convection thermal resistance, convection heat transfer coefficient, isdiscussed in detail, and the convective heat transfer coefficient calculation modelsrelated to the gear, bearing and PSD shell are established. A set of feasible calculationmethod of PSD power losses and convective heat transfer coefficient model isformed.(2) The heat transfer of PSD is analyzed, the PSD analysis and divide oftemperature nodes is completed. Conduction, convection thermal resistance and thethermal resistance related to the gear mesh are modeled. Based on the PSD heat transfer, the PSD system thermal network model is established. According to theKirchhoff’s law in electricity, heat balance equation of each node is established, andthe temperature data is solved by Matlab, which represents overall temperature field.PSD change of temperature field is analyzed, and how the changes in the externalenvironment temperature and the working condition influences average temperatureof lubricating oil and the planetary gear, is thoroughly analyzed and researched.(3) In view of the situation of the bevel gear transmission in PSD, oil churningcharacteristics of bevel gear pair are studied. CFD basic theory is analyzed, and the3-D geometric bevel gear box is established by Catia. Import the model into Gambitto divide flow and solid regions, to carry on the reasonable grid, and to set upboundary conditions. Based on dynamic grid technique, transient fluid distribution issimulated by Fluent. Fluid field distribution is analyzed, oil churning losscharacteristics for the bevel gear pair are further studied under the lubrication, andhow gear speed and oil immersion depth influences oil churning losses of master andslave gear is analyzed.(4) After the analysis of oil churning characteristic, under immersion oillubrication, heat transfer in the bevel gear box is analyzed in detail. Surface andvolume group is organized for computing grid by Gambit, to simulate the thermalcyclic loading. Friction heat flow calculation model for bevel gear pair is establishedby empirical formula. Cyclic loading of input heat flow of Gear meshing tooth surfaceis realized using the UDF technology. The change rule of temperature field of bevelgear and fluid in the beginning of gear drive is analyzed, and how lubricant oilinfluences thermal characteristics of bevel gear pair is further studied. |
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