| 摘要 |
PURPOSE:To make a contact range extend as far as the whole lot of a worm face width range, by including the point displaced to the outlet side of a worm tooth surface in the contact range of hourglass worm gears at a center angle to a wheel center from a design referential pitch point. CONSTITUTION:An angular velocity omega20 of a virtual wheel is made differ from an angular velocity omega2 of a wheel, and on the central plane surface of the wheel, an engaging relationship of internal gears is made to be turned out between the wheel and the virtual wheel, then its engaging pitch point P' is set to the position displaced in the axial direction of a hourglass worm rather than a design referential pitch point P on a central line of the hourglass worm gear. And, on the pitch circumference of a hourglass worm wheel, a generatrix is set so as to cause a perpendicular line erected on tne generatrix to pass through the enging pitch point P' at a point Po shifted more distant to the engaging outlet side of a helical tooth surface of the hourglass worm than the design referential pitch point. With this constitution, an effective contact range is made possible to extent as far as the whole lot of a worm face width range. |
