| 摘要 |
<p>Spectrum analyses of gear noise show that the predominant frequencies are the tooth contact frequency (1xTCF) and twice the tooth contact frequency (2xTCF). The reason for this is that at two positions in the tooth engagement cycle, the effective mesh stiffness of conventional gearing differs substantially from the ideal mesh stiffness that eliminates the dynamic increment of load. One of these two positions occurs once per tooth engagement cycle and the other one twice, giving rise to the 1xTCF and 2xTCF excitations respectively. These periodic fluctuations in the effective mesh stiffness, which are in proportion to what is called 'static transmission error', produce inertia forces between engaged teeth that increase with both speed and proximity to the critical (resonance) speed of the gear pair. In conventional gearing the dynamic increment of load generated by these inertia forces can be as large as or even larger than the useful transmitted load. Not only is this dynamic increment non-useful, it is actually detrimental, since it increases operating noise and diminishes the torque capacity available for useful power transmission. Accordingly, the optimization of any gear pair requires that the dynamic increment be eliminated. This is done by introducing a special pattern of topological modifications to the tooth working surfaces. There is also an optimum form of these modifications which maximizes the torque capacity of the gear pair without sacrificing any of the quietness attainable through minimization of the transmission error.</p> |
