Patent ID: 7211014

Claim:
A variable sprocket IVT machine comprising: an angular velocity input shaft [ 18 ], a sprocket wheel [ 22 ] which is rotatably mounted on the input shaft [ 18 ] and includes a plurality of elongated sprocket tooth elements [ 30 ] which are each slidably located in and project in a common plane from radially oriented sleeves [ 34 ] in the sprocket wheel [ 22 ], an endless flexible drive element [ 12 ] which is spaced from and partially surrounds the sprocket wheel [ 22 ] in a zone in which the drive element is sprocket-driven and includes apertures [ 82 ] which are spaced at uniform intervals over a length of the drive element and in which free ends [ 52 ] of the sprocket tooth elements [ 30 ] are sequentially engageable to drive the element [ 12 ] as the sprocket wheel [ 22 ] is rotated by the input shaft [ 18 ], a track arrangement [ 20 ] on which edges of the drive element [ 12 ] are supported in a drive zone of the drive element, means [ 72 ] for varying a radius of the drive element [ 12 ] drive zone on the track arrangement[ 20 , 21 ], a drive element [ 12 ] tensioning arrangement [ 14 ] for maintaining tension on the drive element [ 12 ] as the radius of the drive element [ 12 ] drive zone on the track arrangement [ 20 ] is varied, and an output shaft [ 16 ] which is driven by the drive element, characterised in that: each of the sprocket wheel [ 22 ] sleeves [ 34 ] is located in a wheel body [ 28 ] which is independently rotatable relative to other said wheel bodies [ 28 ] on the input shaft [ 18 ], connecting arrangements [ 36 , 54 , 60 ] connecting the wheel bodies [ 28 ] to each other to provide a composite sprocket wheel [ 22 ] with the connecting arrangements [ 36 , 54 , 60 ] being adapted to regulate a degree of angular disposition of each said wheel body [ 28 ] relative to the following said wheel body [ 28 ] in the composite sprocket wheel and a radial dimension [R] of the sprocket tooth elements [ 30 ] carried by the wheel bodies in a predetermined relationship so that irrespective of the radial distance separating the drive element [ 12 ] drive zone from the input shaft [ 18 ] a said sprocket tooth element [ 30 ] which is engaged in a said drive element aperture [ 82 ] in the drive zone will position the free end [ 52 ] of the following sprocket tooth element [ 30 ] exactly for engagement in the next drive element [ 12 ] aperture [ 82 ], means for supporting the sprocket tooth elements [ 30 ] of the sprocket wheel [ 22 ] which are not engaged with the drive element [ 12 ] during rotation of the composite sprocket wheel [ 22 ], means [ 68 ] for engaging the wheel bodies [ 28 ] of the sprocket tooth elements [ 30 ] which are engaged with the endless flexible member [ 12 ], with the input shaft [ 18 ], and a control arrangement [ 84 , 86 ] for moving the sprocket tooth element [ 30 ] support means [ 24 ] to vary the ratio of rotation of the output shaft [ 16 ] relatively to the input shaft [ 18 ] during operation of the machine.