Research on power losses of the mizture of air and Lubricant in spur and helical gears
In the geared transmissions, tooth lubrication is necessary to cool surfaces and to reduce friction. However, during the meshing of spur or helical gears, the mixture of air and lubricant is successively compressed and expanded in the intertooth spaces giving rise to significant heating and power losses, especially for high-speed applications. And the total power loss of the system is equal to the heat transfer between the system and its environment. So the solution of pressure, temperature and density of the mixture of air and lubricant in the system is key problem.The authors have presented the simulated model of the air-lubricant pumping by spur and helical gears which based on the following three principles: (a) the simultaneous resolution of the equation of continuity combined with the first principle of thermodynamics applied to open systems, (b) the discretization of the time-varying intertooth volumes, (c) the accurate analysis of the geometry of the meshing parts to determine the flow areas and the associated leak surfaces. And calculated the parameters of the system by numerical technical and get the power loss of the system by the special formula.The spaces between the teeth in the model are sliced into a number of finite volumes or pockets with constant thermodynamic properties, connected by either radial or axial exchange surfaces (Ua and Ur in figure 1). During the meshing process, every pocket is idealized as a piston. In the case of spur gears, the positions of the pistons at one given time are identical for all the discrete pockets along the face width of one given tooth pair in mesh. In contrast, helical gears are decomposed into a series of staggered thin spur gears with the positions of the pistons depending on the axial position to simulate the more progressive intertooth volume variations. At every time step, an Euler method (predictor) and a Newton-Raphson scheme (corrector) are successively applied to all individual pockets to obtained the pressure, temperature and density of the mixture of air and lubricant. And the leak surfaces such as ‘NabghfdceN in the figure 2 can obtained by integral in each subsection. Finally, it will found that the air-lubricant pumping phenomenon can generate significant power losses.
Ning Zhao Qingjian Jia
Department of Engineering Mechanics,Northwestern polytechnical University,Xian,710072 China
国际会议
南京
英文
1-2
2009-10-18（万方平台首次上网日期，不代表论文的发表时间）