Influence of errors and floating on static load-sharing characteristics of twin rotors concentric face-gear power-split transmission system

Twin rotors concentric face-gear power-split transmission system (TRCFGPSTS) is a new and more advanced main reducer configuration of the high-speed helicopter. Its load-sharing performance between different branches has a great impact on the service life performance. Its load distribution is complex, and the research on the influence law of error on load-sharing performance is not clear. Therefore, to study the influence of system error and pinions floating on the mechanical properties of the system, the static load-sharing mathematical model of the system was established. The load-sharing model comprehensively considers the factors of manufacturing error (ME) and installation error (IE), meshing stiffness, torsional stiffness, support stiffness and member floating. The coordination conditions of torsional angle elastic deformation of the system with central displacement offset and the mechanical balance conditions under the action of elastic support and floating support are derived, which reflects the change law of load distribution from the perspective of the system as a whole. The load-sharing model is solved by the least square method. The load-sharing coefficient (LSC) of the system is obtained. The influence of ME, IE and floating pinions on load-sharing performance is analyzed. The results show that the LSC shows irregular periodic fluctuation under the combined action of error, and the LSC is 1.212. Under the single influence of ME, the LSC also shows irregular periodic fluctuation, and the LSC is 1.610. Under the single influence of IE, the LSC presents a constant influence law, and the LSC is 1.326. The error of each gear in the III-stage has the most obvious influence on the load-sharing characteristics. The LSC of I-stage and II-stage floating pinion under the single influence are 1.113 and 1.120, respectively. The floating gear can significantly improve the load-sharing performance, and meet the load-sharing at the ±5 % service requirement.