| Because of the meshing line beyond pitch point and the direction of friction does not change, the node external gear (NER gear) has greater load bearing capacity, lower vibration and noise by the external-meshing gear meshing behind the pitch point or the internal-meshing gear meshing before the pitch point. So NER gear in every field can be widely used. Consequently, the design and dynamics analysis of node external gear transmission is very importantly.The relationship between the parameters of NER was studied. Selecting proper modification coefficients, reducing the tooth depth, changing the meshing angle can all obtain a gear pair of meshing beyond pitch point. The parameters which influenced to the degree of mesh beyond pitch point have been analyzed. The design parameters of a NER pair were got.According to the node external gear pair’s characteristic, the comprehensive radius of curvature’s change rule has been researched, and the traditional contact stress calculation has been improved. The load bearing capacity of the node external gear and the ordinary gear were calculated.The sliding coefficient calculation’s formula of external-meshing gear and internal-meshing gear was derived. The influence of the direction of friction to tooth surface abrasion, vibration, tooth face stress and lubrication has been researched.The vibrant model including time-variant stiffness, friction, and tooth lateral clearance is established by Lumped-mass Method. The motion differential equation of the model is presented, and is solved using numerical integration. By using the finite element calculation software, intrinsic frequency and vibration mode of the gear pair were calculated. The results indicated that the NER transmission system has higher intrinsic frequency, lower vibration and smaller dynamic load coefficient. |
