Transmission Theory Of High Order Elliptic Gear And Its Application In Flowmeter

Non-circular gear mechanism has the characteristic of motion transmission according to the specified transmission ratio function,which has been widely used in mechanical instruments and instruments.However,with the wide application of digital technology in machinery and instruments,the motion transmission characteristic of non-circular gear mechanism has been gradually replaced by the motion numerical control technology.The extensive application of computer technology in the field of mechanical parts design and manufacturing has greatly improved the power optimization design and manufacturing efficiency of non-circular gear and ensured the manufacturing accuracy,which has created conditions for the application of non-circular gear mechanism in the field of mechanical power transmission.At present,the design of high-density power transmission device with small volume and light weight based on the superior power characteristics generated by the special pitch curve of non-circular gear is becoming a hot spot in the application research of non-circular gear mechanism in aerospace field.Aiming at the design of high-order elliptic gear and its application in flowmeter,this paper studies the dynamic performance requirements of high-order elliptic gear flowmeter with small volume and large flow by using the special transmission characteristics of non-circular gear.In this paper,the design method,transmission characteristics and application in the flow meter of high-order elliptic gear are studied and analyzed by theoretical analysis and simulation.The main work and results accomplished are as follows:Firstly,the mathematical theory basis and transmission characteristics of high order elliptic gear are studied.The design method of high order elliptic gear pitch curve and its verification condition and the design method of tooth profile are studied.In order to verify the correctness of the design and modeling method of non-circular gear,the influence of eccentricity and order on transmission characteristics is analyzed by combining MATLAB theoretical results and ADAMS simulation results.Then,the application of higher order elliptic gear in flowmeter is studied.The solid model of the high-order elliptic gear flowmeter is drawn by PRO/E,and its working principle and characteristics are described.The relations of theoretical displacement and instantaneous flow are derived.Combined with MATLAB,the influence of order and eccentricity on instantaneous flow is discussed,and the pulsating non-uniformity coefficient is calculated.Secondly,the suppression of flow pulsation is studied.Two kinds of smoothing methods are proposed for the pulsation defects of the flowmeter :(1)after increasing the variable speed non-circular gear,the smoothing effect is optimized by changing the eccentricity of the elliptic gear pair and the variable speed non-circular gear pair;(2)The pitch curve of variable speed non-circular gear is designed according to the transmission ratio.This method can achieve the optimization result of complete flattening.Finally,the two-dimensional flow field analysis of the high-order elliptic gear flowmeter is studied.Based on FLUENT numerical simulation analysis,the variation diagram of velocity field,pressure field and outlet flow rate and velocity in the flowmeter chamber was obtained.The results showed that the change of eccentricity would cause the change of instantaneous flow rate.Gear meshing can also cause small flow pulsation,but it is not the main cause of flow pulsation.The results reflect the real situation of oil flow in the cavity and confirm that there is no interference in the model.Through the above research and analysis,not only solved the problem in the design of the non-circular gear,also of high order elliptic gear flowmeter is optimized,eliminate the flow pulsation,up to the small volume,big flow performance requirements,improve the working performance and service life of the flowmeter,for the elliptical gear application in engineering has important significance and application value.