Aquesta és una còpia de la versió author's final draft d'un article publicat a la revista Journal of mechanical science and technology.La publicació final està disponible a Springer a través de http://dx.doi.org/10.1007/s12206-017-0131-3 This is a copy of the author 's final draft version of an article published in the journal Journal of mechanical science and technology.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
AbstractThe increase of power generated by wind turbines has increased the stresses applied in all of its parts, which causes the appearance of premature failures. In particular, pitch and yaw gears suffer of excessive wear, mainly due to inappropriate lubrication. This paper presents a novel method to automatically lubricate the wind turbine pitch gear during operation. A micro-nozzle to continuously inject fresh grease between the teeth in contact was designed, manufactured and installed in a test bench of a 2 MW wind turbine pitch system. The test bench was used to characterize the fatigue behavior of the gear surface using conventional wind turbine greases under real cyclic loads. The measurements of wear evolution in a pitch gear with and without micro-nozzle show a decrease of 70% of the wear coefficient after 2x10 4 cycles.