Patent ID: 8075444
Filing Date: 2011-12-13
Classification: F16H

Abstract:
1. A friction drive device comprising: a first roller including a roller support part; a second roller rotatably engaged with the first roller to receives a press force from the first roller at a contact point between the first and second rollers to transmit mechanical power between the first and second rollers; and a cam member supporting the first roller through the roller support part, the cam member including a cam surface having a slope angle relative to a tangent line at the contact point between the first and second rollers such that the cam surface presses against the roller support part to transmit a drive force between the first and second rollers via friction generated at the contact point; the first and second rollers having first and second center axes, respectively that are spaced apart by prescribed radial distance, the first and second rollers being further configured and arranged relative to an x y coordinate system when the first and second rollers are not under load such that the x y coordinate system has an x-axis and a y-axis with an origin corresponding to the first center axis of the first roller, and the y-axis passes through the second center axis of the second roller, the cam surface being located in a first quadrant of the x y coordinate system, and the cam surface having a concaved cross sectional shape lying in a plane perpendicular to the first center axis that forms a concave arc with a single radius, such that the concave arc of the cam surface has a cam surface center located in a third quadrant of the x y coordinate system with the cam surface center of the cam surface lying on or outside of an imaginary arc defined by the prescribed radial distance extending from the first center axis of the first roller.