Patent ID: 8683885

Claim:
A friction drive transmission apparatus comprising: a driving roller unit and a driven roller unit which are supported rotatably, the driving and driven roller units being pressed in press contact to each other and arranged to transmit power from one of the driving and driven roller units to the other by a frictional transmission force produced in a contact portion therebetween, the driving and driven roller units comprising a plurality of roller pairs having different roller radii, at least one of the driving and driven roller units being supported rotatably on an eccentric shaft so that an inter-axis distance of each of the plurality of roller pairs is varied by rotation of the eccentric shaft, and the power is transmitted selectively by one of the plurality of roller pairs; and a pressing force imparting member configured to vary a pressing force imparted to the roller pairs so as to vary the frictional transmission force smoothly at a time of a shift, the pressing force imparting member comprising: an actuator that increases the pressing force by adding an additional force to the plurality of roller pairs; and a controller for the actuator, the controller being configured to: control the pressing force with the actuator, hold the additional force before a shift operation, and increase the additional force transiently at the time of the shift so as to vary the frictional transmission force smoothly at the time of the shift.