Configuration Design,load Sharing And Dynamics Research For The Torque-split Face Gear Transmission Of Helicopter

The torque-split gear transmission has a wide application prospect and is widely used in the transmission system of modern helicopter.The torque-split face gear transmission for helicopter studied in this paper has the advantages of high power density,large reduction ratio,high reliability and compact structure,which has been applied to the transmission system of advanced helicopters.The configuration design,load sharing and dynamic characteristics of the torque-split gear transmission are crucial to give full play to its advantages of the torque-split face gear transmission of helicopter.In this paper,the torque-split face gear transmission of helicopter is taken as the research object,the problems of the correct engagement of the torque-split gear transmission is studied.Moreover,the mechanism of the uneven load sharing of the torque-split gear transmission is analyzed,and the static load sharing characteristics of the concentric torque-split face gear transmission system are studied.The lumped parameter method is used to establish the dynamic model of the transmission system,and the inherent characteristics,dynamic responses and dynamic load sharing characteristics of the system are analyzed.A general configuration design method of torque-split gear transmission is established.By using this method,the mathematical model for the design of the internal and external meshing duplex torque-split gear transmission is established,and the relationship among the number of teeth,module and gear arrangement angle is given.The advantages of this method are demonstrated by comparing numerical examples and meshing conditions with those in the literature.Through simplification,the proposed configuration design method is applied to the concentric torque-split face gear transmission and planetary gear transmission.The static load sharing problem of the concentric torque-split face gear transmission is studied.The direction of power flow in the ideal condition of this configuration is analyzed,and the mechanism of uneven load is revealed.And based on the principle of deformation coordination,the load distribution process of the torque-split gear transmission is analyzed.The hybrid finite element/lumped parameter load sharing calculation model of the concentric torque-split face gear transmission is established.By calculating and storing the flexibility matrix of the flange nodes in advance,the calculation efficiency of the model is improved.The finite element simulation is used to verify the hybrid finite element/lumped parameter load sharing calculation model,and the results show that the calculation error of this model is less than 5%.Based on this model,the influences of the key parameters,such as support stiffness,the stiffness of the face gear body and no-load transmission error of gear pair,on the load sharing characteristics of the concentric torque-split face gear transmission system are studied.The dynamic models of the spiral bevel gear pair,the low angular face gear pair and the orthogonal straight gear pair in the main reducer of the helicopter are established by using the lumped parameter method,and the dynamic differential equations are established by using the Lagrange method.The correctness of the method of establishing the dynamic model of the gear pair is verified by the dynamic experiment of the orthogonal face gear pair.Moreover,the solution method of the inherent and dynamic characteristics of the gear transmission system is given,and the dynamic load coefficient of the system is defined,which lays a foundation for the analysis of the natural and dynamic characteristics of the main reducer of helicopter.The dynamic model of the main reducer of helicopter is established.Based on the dynamic models of various types of gear transmission established in the previous chapter,a fast method of establishing dynamic model of complex gear transmission system is proposed,and the correctness of the method is verified.The equivalent diameter method is used to simplify the stepped gear shaft into a smooth shaft,and the gear shaft of the main reducer is divided into cantilever shaft,two end support shaft and mixed support shaft according to the support mode of gear.For the mass element and elastic element in the lumped parameter model of the main reducer,the calculation methods of the equivalent support stiffness,the equivalent lumped mass and the equivalent moment of inertia of each component are given.The dynamic characteristics of the main reducer of helicopter are analyzed.The equivalent lumped mass,the equivalent moment of inertia,the equivalent stiffness and the coupling stiffness of the double gear shaft are calculated.The natural frequency and mode shape of the main reducer under the system parameters are also calculated.The modal energy method is used to gain the modal kinetic energy and modal strain energy of the system.The distribution of modal kinetic energy and modal strain energy in the system,as well as the relationship between the system parameters.The influences of the mass,moment of inertia and stiffness on the inherent characteristics of the system are studied.The dynamic transmission error,dynamic meshing force and dynamic load coefficient of the main reducer are solved.By defining the reference gear pair,the relative meshing phase of each gear pair in the system is calculated.The influences of the meshing phase and the support stiffness on the dynamic response of the system are analyzed.The dynamic load sharing characteristics of the concentric torque-split face gear transmission are analyzed.The influences of different output power range of the tail rotor on the direction of the power flow of the concentric torque-split face gear transmission are studied.The relationship between the transmission error and the uneven load sharing,and the relationship between the stiffness and the uneven load sharing under dynamic condition are clarified by the method of group calculation.The influences of the system parameters on the dynamic load sharing characteristics of the system are analyzed.Based on the analysis,the load sharing methods of the concentric torque-split face gear transmission are proposed.