Infinitely variable speed transmission

Abstract

In an infinitely variable speed transmission T of this invention, a belt variable speed mechanism 4 is arranged between a first rotatable shaft 1 and a second rotatable shaft 2. A planetary gear mechanism 81 is provided which comprises a first, a second, and a third element. The first element is drivingly coupled to the second rotatable shaft 2. The second and third elements are drivingly coupled by way of different power transmission lines to the first rotatable shaft 1. An enclosed gear housing space 78 is defined at the back of a fixed sheave 14 of a second variable speed pulley 13 of the belt variable speed mechanism 4, to house therein the planetary gear mechanism 81. A belt transmission mechanism 55 is arranged between the first and second rotatable shafts 1 and 2. Supported on a flange 82 integral with the second rotatable shaft 2 is a planetary gear 84 having a first gear part 85 that engages with a first sun gear 88 and a second gear part 86 that engages with a second sun gear 90. The first sun gear 88 is drivingly coupled to a second transmission pulley 57 of the mechanism 55. The second sun gear 90 is drivingly coupled to the second variable speed pulley 13 of the mechanism 4. The distance between the shafts 1 and 2 can be changed easily, and the size of casing for gear engagement area covering can be made as small as possible.