Thermodynamic Modeling And Analysis Calculation Of Aircraft Electro-Hydrostatic Actuator

The electro-hydraulic actuator(EHA)has the advantages of small volume,light weight,high efficiency,good safety and convenient maintenance.EHA is the inevitable choice for the advanced aircraft to improve its performance.In the process of aircraft flight,the pilot drives the elevator,rudder and other rudder surfaces of the aircraft by command to control the flight attitude and ensure the normal operation of the aircraft,so the safe operation of EHA is very important.However,the extreme requirements of the aviation industry for weight reduction force EHA to develop in the direction of high speed and pressure,which makes EHA overheating become an important factor affecting its application.Therefore,the thermal analysis of EHA is a key step in its development and preparation,so this paper uses the method of lumped parameter and numerical simulation to carry out the thermodynamic analysis of EHA.In this paper,aiming at the problems involved in EHA thermodynamic analysis,the structure and principle of EHA,energy loss of plunger pump and motor,dynamic viscosity temperature characteristics of hydraulic oil,lumped parameter modeling,ANSYS simulation,AMESim simulation,board level thermal analysis of electronic devices are studied in depth.The main contents are as follows:(1)Firstly,after the detailed analysis of EHA components and operation process,the structure and schematic diagram of EHA system are established;on this basis,the energy loss of swashplate plunger pump and brushless DC motor,the main heat source of EHA,is quantitatively analyzed;further tests are carried out to determine the viscosity of hydraulic oil at different temperatures,and the viscosity temperature characteristics of YH-15 hydraulic oil are obtained by function fitting based on Matlab The heat dissipation condition of EHA system is analyzed,which lays a foundation for further EHA thermodynamic calculation and analysis.(2)Aiming at the problem of EHA hydraulic system without large heat sink and poor heat dissipation condition,based on the structure and principle of EHA,the eight node lumped parameter modeling framework is established,and the differential equations of hydraulic system thermodynamic model are established according to the analysis idea of lumped parameter method.Then,based on Matlab/Simulink simulation calculation,the temperature rise curve of EHA components is determined.(3)Then,based on AMESim hydraulic analysis software,select the appropriate model,configure the reasonable parameters,and establish the thermodynamic simulation analysis model of EHA to verify the correctness and feasibility of EHA thermal analysis based on the lumped parameter method.The results show that the error between theoretical calculation and simulation analysis is within a reasonable range,and the lumped parameter thermal analysis method is suitable for the thermodynamic calculation of EHA.Based on the ANSYS simulation software,the thermodynamic finite element analysis of the brushless DC motor in EHA is done.Comprehensively grasp the overall temperature change of EHA device.(4)Aiming at the practical problems of strong thermal sensitivity and easy failure of PCB in EHA internal motor drive circuit,a three-dimensional model of PCB is established,and the board level thermal analysis of PCB in motor drive circuit is carried out by importing ANSYS/Icepak software.The results show that the temperature of power tube is too high.Finally,the heat sink is selected to enhance the heat dissipation,and the structure and size of the heat sink are optimized based on Icepak.This paper takes the lumped parameter method as the main research method,the research route of combining theoretical calculation with simulation,and carries out the thermodynamic calculation and Analysis on the power loss components such as the hydraulic system,motor and electronic components of the electro-hydraulic actuator.It puts forward the eight node lumped parameter modeling thermal analysis method of EHA,and achieves innovation.The research results show that the temperature rise of motor and electronic device is fast,the heat and heat dissipation of motor and electronic device can not be ignored,which is an important part of EHA thermal analysis;the eight node lumped parameter modeling thermal analysis proposed in this paper is basically consistent with the software simulation test results,and the lumped parameter thermal analysis method is applicable to the thermodynamic analysis of EHA hydraulic system,which can predict the temperature change quickly and accurately.The temperature control level is e Ha hydraulic system design and component selection provide reference for EHA design and airworthiness certification.