Abstract: To address the demand for multi-power path transmission in the intelligent development of aero-engines, the structural design and control method of an accessory gearbox with variable power paths are investigated. An innovative structure based on a normally-closed electromagnetic dog clutch is designed, where power path switching is achieved through clutch engagement and disengagement; A dynamic model of the transmission chain system with electromechanical and electromagnetic multi-field coupling is constructed, enabling precise simulation of the power-path switching process; A power path switching control strategy is formulated, and bench tests are conducted for verification. The results indicate that the design realizes two power paths and four working modes: main engine operation mode, air safety mode, ground maintenance mode, and main-engine startup mode. Simulations show that under air safety mode, when the main engine speed drops to 10% and 64%, the power path switching times are 0.1285 s and 0.3000 s, respectively. Bench tests demonstrate that the power path switching time does not exceed 0.35 s; the electromagnetic clutch can stably transmit torque at 11.7 krpm in the engaged state, and remain stably disengaged for over 3900 s with a speed difference of 8.4 krpm between both ends. The study validates the structural reliability and control method effectiveness of the variable power path gearbox, providing technical support for the intelligent development of aero-engine accessory drive systems.

Key words: accessory gearbox, variable power path, electromagnetic clutch, structural design, dynamics, switching control