Research On Two Stage Differential Planetary Gear Train Used In Ship

The development of modern naval ships has prompted a higher standard on vibration and noise, which relates to fighting capacities. The two stage differential planetary gear train is one of the most important part of the powertrain. The planetary gear train is mainly composed of planetary gears and floating rings, which is the main source of vibration and noise of the powertrain. In view of the great difficulty of experimental test of the planetary gear trains, the study of the planetary system is necessary and significative.A linear time-varying lumped-parameter model is established for the planetary gear train. The model includes time-varying meshing stiffness, time-varying positions of planets of stage one and meshing phase. Based on the principle of deflections consistency of the meshing gears, the planetary gears is modeled. Also the spur couplings, crown couplings and helical couplings are modeled by applying the deflections consistency.Due to its cyclic symmetry, the planetary gear train has highly-structured natural frequencies and vibration modes. The eigenvalue problem from the planetary gear train free vibration is solved, and some interesting conclusions are obtained. The vibration modes of the planetary gear train are classified into three types, which are planet mode, coupling transverse mode and coupling rotational mode.The sensitivity of the planetary gear train natural frequencies and vibration modes to the system stiffness, mass and inertia parameters is investigated using the eigensensitivity of eigenproblem. Formulae connecting natural frequency sensitivity with the modal strain or kinetic energy are obtained.Based on the helical gears varying contact length calculation model, static transmission error is obtained. Newmark-β method is applyed to solve the dynamics equations excited by static transmission error, taking into account the time-varying planet phases in first stage. Also analyze the dynamic response of the planetary gear train under excitation of harmonious of meshing frequency.