Pulley apparatus

A pulley apparatus, comprising:

• a rolling bearing having an inner ring that has an inner ring raceway around the outer circumferential surface thereof, an outer ring that has an outer ring raceway around the inner circumferential surface thereof, and a plurality of rolling elements that are provided between the inner ring raceway and the outer ring raceway;
• and
• a pulley that has an outer circumferential surface around which a belt is placed, and an inner circumferential surface that is fitted around the outer circumferential surface of the outer ring;
• wherein
• at least one locking groove is provided around part in the axial direction of the outer circumferential surface of the outer ring, the locking groove having a width that is within the range of 1/20 to ½ the width of the outer ring;
• knurling is formed on the bottom surface of this locking groove by a knurling process such that concave sections and convex sections that extend in the width direction of the knurling are alternately arranged around the entire circumference;
• each of these concave sections comprising a bottom surface and two inside surfaces on both sides in the circumferential direction of the bottom surface and that are continuous with the tip end surfaces of the adjacent convex sections;
• these concave sections having a trapezoidal shape by regulating the angle of intersection between the inside surfaces within the range 45° to 120°;
• and furthermore, the diameter D of the circumscribed circle of the tip end surface of the convex section, the depth h in the radial direction of the concave sections, and the length L in the circumferential direction of the bottom surface of the concave sections satisfy the relationship 0.004 D≦h≦0.015 D, and 0.01 D≦L≦0.03 D;
• and
• a plurality of trapezoidal shaped protrusions that extend in the width direction and that engage with the concave sections are formed around part in the axial direction of the inner circumferential surface of the pulley.