Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Various components of the wind turbine that are disposed in the nacelle must be supported. Thus, a bed plate is provided in the nacelle to support, for example, the shaft and, optionally, the gearbox if present, and the generator. In particular, the shaft must be supported as it extends from the rotor blades and the hub to the gearbox and/or generator. Typical prior art devices for supporting the shafts include pillow blocks. For example, in a typical configuration, the main rotor shaft is pressed fit and held in place in the main bearing housing with a relatively tight fitting inner ring. A locknut is provided as a separate, backup retention device and is engaged with threads defined in the main rotor shaft.
For example, referring to FIG. 3, a prior art configuration is illustrated for retaining the main bearing around rotor shaft 20 in position relative to the pillow block 30. With this configuration, a lock nut 38 is threaded onto threads defined in the outer circumferential surface of the shaft 20, with the lock nut 38 advancing axially so as to engage against an inner ring 48. The main bearing is pressed onto the main shaft 20 and is housed by the pillowblock. The lock nut 38 configuration serves primarily as a secondary or backup retention means.
The threaded locknut assembly can, however, be disadvantageous. For example, the costs and time associated with machining the threads on the main rotor shaft can be significant. An annual inspection of the locknut requires manual loosening and re-tightening of the nut with a spanner wrench, which is cumbersome to use and has resulted in injury to technicians due to the high torque required to adequately tighten the locknut to design specifications.
Thus, an improved retention assembly that eliminates at least certain of the drawbacks of the conventional locknut assembly would be an advantageous advancement in the industry.