S112013 球状ライダと多孔質ディスクを用いた電気しゅう動接点の潤滑特性 : 球状ライダの曲率半径が潤滑特性に及ぼす影響

Abstract

The purpose of the present study is to improve the performance characteristics of the electric sliding contacts and to extend their lifetime by using the rotating porous disk and the stationary nonporous rider with spherical surface. The theoretical and experimental analyses have been carried out to investigate the effects of the curvature radius of spherical surface of the rider on the frictional characteristics and the electrical conductivity. The experimental analysis is conducted with a pin-on-disk friction tester to measure the frictional force and the contact voltage between the sliding contacts. The oil-film force and the frictional force between the rider and the rotating disk are also calculated by simultaneously solving the modified Reynolds equation and the Laplace equation derived from Darcy's law. The numerical results qualitatively agree with the experimental results. These results show that reduction in the curvature radius of spherical surface extends the operating conditions under the continuous metal contact to a higher value of the bearing characteristic number S defined by ηU_0L(B/L)/W ( η:oil viscosity, U_0:sliding speed, L:length of rider in direction of motion, B:width of rider, W:applied load), and it also decreases the frictional force at the maximum S at which the rider could contact with the disk surface. This phenomenon is expected since upstream lubricant oil dragged into the contact region tends to easily leak out in the direction perpendicular to the sliding due to the diverging zone formed between the disk and the rider with spherical surface, yielding a lower oil-film force and enhancing the metal contacts.