Power roller bearing of toroidal-type continuously variable transmission unit

Abstract

A power roller bearing of a toroidal-type continuously variable transmission unit that is used for a transmission of an automobile or the like comprises a power roller, an outer race, balls, a retainer, etc. Annular raceway grooves are formed individually on the respective opposite end faces of the outer race and the power roller. Treated-surface layers for enhancing the endurance of the power roller bearing are formed individually on the respective surfaces of the raceway grooves. The treated-surface layers include super-finished surfaces with the surface roughness of 0.05 Ra or less, formed individually on the raceway grooves, and low-friction layers formed individually on the super-finished surfaces. Alternatively, the treated-surface layers include residual compression stress layers formed on the respective surface layer portions of the raceway grooves by shot-peening.

What is claimed is:  
     
         1 . In a power roller bearing of a toroidal-type continuously variable transmission unit, which is provided for swinging motion between an input disc capable of being rotated by means of a drive source and an output disc opposed to said input disc, the power roller bearing of the toroidal-type continuously variable transmission unit comprising: 
 an outer race;    a power roller in rolling contact with said input disc and output disc; and    balls provided for rolling motion between said outer race and said power roller,    said outer race and said power roller having annular raceway grooves in which said balls roll individually,    at least one of the respective raceway grooves of said outer race, heat-treated and ground, and said power roller being formed having treated-surface layers including super-finished surfaces with the surface roughness of 0.05 Ra or less and residual compression stress layers shot-peened so that the residual compression stress therein ranges from −20 kgf/mm 2  to −100 kgf/mm 2 .    
     
     
         2 . In a power roller bearing of a toroidal-type continuously variable transmission unit, which is provided for swinging motion between an input disc capable of being rotated by means of a drive source and an output disc opposed to said input disc, the power roller bearing of the toroidal-type continuously variable transmission unit comprising: 
 an outer race;    a power roller in rolling contact with said input disc and output disc; and    balls provided for rolling motion between said outer race and said power roller,    said outer race and said power roller having annular raceway grooves in which said balls roll individually,    both of the respective raceway grooves of said outer race and said power roller being formed having super-finished surfaces with the surface roughness of 0.05 Ra or less and low-friction layers on at least one of the super-finished surfaces, the low-friction layers being formed of at least one of lubricative substances including gold, silver, lead, molybdenum disulfide, tungsten disulfide, and fluoroplastics.