Analysis Of Load Sharing Characteristics Of Gear Split-Torque Transmission System With Elastic Quill Shafting

Applied to high-power helicopter main rotor transmission,2-input cylindrical gear split-torquetransmission system increases helicopter’s payload and performance through two parallel paths fortransmitting torque by the fixed axis gear trains. Compared with the planetary design, the split-torquetransmission system can offer the following advantages: high reduction ratio of the final stage, areduced number of gear stages, fewer gears and bearings, high transmission efficiency, increasedreliability, lower noise levels from gear meshes, smaller volume and lower overall drive systemweight. Thus, the study on split-torque helicopter transmission has great significance for thedevelopment of helicopter main rotor transmission. The research contents mainly consist of torsionalstiffness and modal analysis of elastic quill shafting, the equivalent displacement formula of the gearinstallation error along the meshing line, dynamics model, dynamic load sharing characteristics andsoftware development.The software Romax was used to establish elastic quill shafting and modal characteristic iscalculated.The natural frequency, vibration mode and limited speed are studied. Improved designsolutions are proposed to keep the gearbox in good condition. A simple and practical calculatingmethod,which can be realized through program, is presented. The correct result has been proven fromthe results of comparison and analysis.The equivalent displacement formula of the gear installation error and eccentric error along themeshing line is obtained. So the complete equivalent displacement formula system of the gear errorsalong the meshing line is set up in this system.A dynamic analysis model was established for a2-input cylindrical gears split-torque transmission,in which the time-varying mesh stiffness, backlashes, mesh errors and damping were considered; Withthe characteristic of closed loop structure, differential equations could be obtained without rigiddisplacement, using the relationship between relative meshing displacement and the shaft torsionallinear displacement.The dimensionless differential equations for this train which eliminate the rigidbody movement is obtained.Through solving of dynamic equation by the Runge-Kutta method, the dynamic responses of thesystem were acquired. The influence rules of torsional stiffness,backlash, composite transmissionerror, support stiffness on nonlinear dynamic load sharing characteristics for the2-input cylindricalgears split-torque transmission are analyzed. The distribution law of the sensitivities of load sharingcoefficient to support stiffness was obtained.According to the above results, taking MATLAB software as a platform, design and analysissoftware of2-input cylindrical gears split-torque transmission about tooth match, torsional stiffnesscalculation and dynamic analysis is developed, which visual interface is user-friendly.