Research On Tooth Profile And Pressure Pulsation Of An External Gear Motor

External gear synchronous motors are widely used in hydraulic synchronous systems due to their robustness and low cost.However,the noise of the motor is one of the limiting factors.The main source of noise comes from the pressure and flow pulsation during gears meshing.At present,one of the methods to explore the noise of the external gear synchronous motor is to quantitatively analyze the relationship between the tooth profile curve and the meshing volume.However,accurate measurement and modeling of the tooth profile is a key pre-order work to accurately predict the relationship between tooth profile and pressure pulsation.Current profile models assume the standard involute or cycloid functions in the simulation,whereas the influence of tooth face deflection and the machining error of tooth profile are not reflected in the dynamic characteristics of the gear mesh volume.Therefore,starting from the measurement method of tooth profile curve,this paper proposes and verifies a non-contact tooth profile measurement principle and reconstructs the actual tooth profile,and finally realizes the dynamic analysis of the pressure pulsation of the external gear based on the actual tooth profile.This paper proposes a new method for non-contact tooth profile measurement using CCD imaging components and LTS sensors.Firstly,the geometric relationship,applicable conditions and errors between the key variables of the measurement method are deduced.The non-contact tooth profile measurement system is designed and built,and the tooth profile measurement of the external gear synchronous motor is carried out.The test data is processed by MATLAB/C language,and the actual tooth profile curve is reconstructed to obtain accurate tooth shape information.Secondly,using CFD(Computational Fluid Dynamics)numerical simulation method to simulate the internal pressure of the motor and the fluctuation of the outlet pressure.According to the actual size of the motor,the two-dimensional Fluent flow field model was built.The pre-processing software Gambit was used for mesh division.The dynamic mesh time-varying simulation technique was used to calculate the internal transient pressure of the gear motor and the pressure pulsation at the motor outlet.Finally,the pressure pulsation test platform of the external gear motor was built.The pressure pulsation of the external gear motor unit under the inlet pressure of 1 MPa-6 MPa was tested.The results were compared with the CFD simulation results.In this paper,the tooth profile measurement test results are compared with the theoretical motor gear profile.The result is a good representation of the actual tooth profile.The average tooth profile measurement error is 0.12 mm,and a method to improve the non-contact measurement accuracy of the gear motor is proposed.In addition,the CFD numerical method is used to simulate the dynamic pressure changes of the actual tooth profile and the standard tooth profile.The results show that the tooth profile shape of the gear has a significant influence on the pressure pulsation of the motor oil discharge cavity,and the average amplitude of the pressure pulsation is mainly caused by the gap between the top of the tooth and the edge of the motor.Finally,the CFD simulation results and the test pressure pulsation amplitude results are normalized and compared,and the error is between 0.09%and 2.28%,indicating that the simulation reflects the actual test situation.In summary,the model can predict the influence of the tooth profile on the pressure pulsation of the external gear motor.Finally,the tooth profile measurement technology of the external gear synchronous motor and the related research on the influence of tooth profile on pressure pulsation are summarized and forecasted.