Abstract:

Gears are often used in the deployment mechanism of a large satellite antenna to spread the truss synchronously, and seizure is a main invalidation of a pair of synchronous gears in the deployment mechanism. From the ultimate position of the gearing mesh, the seizure-preventing condition for the gear pair is given in this paper. Then, with gears’ mismachining tolerances and fitting allowances and the space temperature cosidered synchetically, an analystical model of seizure-preventing reliability of the gear pair is presneted, and the movement function of the gearing mesh is obtained, which is expressed by the tooth clearance. With the true dimensions of the shape and position of a gear regarded as random variables, the formula of the gear’s degree of seizure-preventing reliability is derived by the method of second-order moment. Finally, a real satellite antenna with hoop-truss is calculated and some conclusions are obtained as follows: 1) the effect of thermal loads on the seizure-preventing reliability of synchronous gears deserves not to be ignored; 2) if two gears are fixed at the normal center-to-center distance, the thermal distortion in the space will obviously lower their performance; 3) properly adopting the method to fix the gear pair at the normal-shifted center-to-center distance, and preventing the deployment mechanism from working at high temperature can improve the degree of seizure-preventing reliability. Computational results show that the analytical model of seizure-preventing reliability in this paper is reasonable and efficient.

Key words: satellite antenna, synchronous gear, seizure-preventing, movement reliability