Bolt Tightening Control Method for 4P Generator with Solid-Pole Rotor

摘要

For a 4P generator with a solid-pole rotor, a large load is applied during operation to the bolts that clamp the pole shoes, which support the field coils on outer diameter side of the magnetic poles. On the other hand, in order to suppress the repeated loads, it is necessary to increase the axial force (fastening force), thus the constraints on the permissible range of fastening force is severe. We have, therefore, developed a bolt tightening control method that can manage fastening force with high accuracy so that it can satisfy the constraints. In the case of the torque control method that is a generally adopted as bolt tightening control method, the instruction torque value is determined to meet the constraints on the axial force which is estimated based on the tightening torque. Accuracy level for axial force estimation is, however, very low. Where the level of constraints is very high, it is impossible to adopt this method. In case of our newly developed bolt tightening control method, the axial force can be directly measured so control is possible even when the constraints are severe. In addition, in order to improve the productivity of assembly, we improved the tightening control method by using an elastic rotation angle tightening.