Analysis Of Friction Characteristics Of Herringbone Gear Lubricated With Non-newtonian Fluid Elastohydrodynamic Lubrication

Herringbone gear not only has the advantages of high transmission efficiency and compact structure inherent in traditional gear,but also does not produce axial force.Therefore,it is often used in heavy loads and high reliability requirements,such as aviation,shipping and other fields.However,it is impossible to detect the friction coefficient,abrasion and lubrication state of the gear at every moment in the meshing process,due to the time variability of gear transmission.Therefore,the research on the above problems has always been the focus area of gear research.Based on the theory of non-Newtonian fluid line contact elastohydrodynamic lubrication,the friction coefficient and meshing efficiency of the herringbone gear pair are studied in this paper.1)The non-Newtonian fluid line-contact elastohydrodynamic lubrication is numerically calculated.The influence of each parameter on lubrication state and friction coefficient is analyzed,which provides a theoretical basis for the study of gear lubrication.The degree of influence of friction coefficient,from large to small,is unit load,sliding speed,viscosity of lubricating oil and entrapping speed.2)The lubrication characteristics of EHL helical contact gear based on non-Newtonian fluid are studied.The lubrication characteristics of helical gear at different meshing positions are analyzed according to the variation rule of each parameter of the gear.The oil film pressure and the oil film thickness of the helical gear at the root of the tooth(meshes into point)are maximum and minimum.At the same time,according to the elastohydrodynamic theory,helical gear has higher bearing capacity than spur gear under the same parameters.3)The numerical solution of herringbone gear with non-Newtonian fluid line contact EHL is analyzed.Study the difference of each parameter in the meshing process between herringbone gear and helical gear.The influence of working condition parameters on friction coefficient and meshing efficiency is studied.It is concluded that compared with helical gear with the same parameters,human word gear has more time under low unit load in the meshing area,which is beneficial to improve service life.Secondly,the distribution of the friction coefficient of the hermitage gear is as follows: the friction coefficient of the nodeposition is the smallest,and the friction coefficient of the tooth root tip position is larger.Finally,the meshing efficiency decreases with the increase of rotating speed in the low speed region,decreases with the increase of rotating speed in the medium and high speed region,and increases with the increase of torque.4)The meshing efficiency of the herringbone gear with different power is measured by using the power closed herringbone gear test bed.At the same time,it is compared with the theoretical results to verify the correctness of the contact theory.It is pointed out that the calculation of friction coefficient and meshing efficiency based on non-Newtonian fluid line contact elastohydrodynamic lubrication is consistent with the experimental results.This theory has some guiding significance in the design of herringbone gear.