The invention relates to power transmission systems and components of the type including a pulley having a circumferentially spaced portion of its drive face spaced unequal distances from the pulley axis of rotation, but more particularly, the invention relates to a tension compensating gear set of the eccentric type with a gear member having external teeth that mesh with internal teeth of a floating, annular gear member.
Eccentric type gear sets are used for a variety of purposes in power transmission systems with a flexible power transmission member. For example, such gear sets may be used to increase the minimum bend radius of a flexible power transmission member such as illustrated in German Patent No. 115,719; as a speed reduction means as shown in U.S. Pat. No. 3,190,149; or as a means for compensating for differences in tension in a flexible power transmission member such as shown in U.S. Pat. No. 4,501,576. The term "flexible power transmission member" as used herein includes a toothed or synchronous belt, a V-belt, a V-ribbed belt, a flat belt, and a chain.
Radial disengagement of meshing teeth of a tension compensating gear set is characteristically inhibited by a flexible power transmission member, and lateral disengagement of meshing teeth of the gear set may be prevented by lateral side plates of the type as disclosed in aforementioned U.S. Pat. No. 4,501,576 or German OS 31 00 922.
Problems associated with such eccentric type gear sets as used with a flexible power transmission member, are that of noise and vibration as caused by the annular gear member not having a fixed or precise center of rotation. Variations in tension of the flexible power transmission member cause a radially inward force to be applied to the annular gear member causing its gear teeth to wedge with the teeth of the gear member and carry radial loads; this radial force is in addition to the tangential force carried by the gear teeth at their meshing flank surfaces.