Patent ID: 6167783
Filing Date: 2001-01-02
Classification: F16H,Y10T

Abstract:
A flexible meshing type gear device including a rigid internal gear, a cup-shaped or silk-hat-shaped flexible external gear and a wave generator,the flexible external gear including a cylindrical body, a diaphragm formed continuously with one end of the body to extend radially inward or outward and external teeth formed on an outer peripheral surface of an opening portion of the body, the external teeth being capable of meshing with internal teeth formed on an internal peripheral surface of the rigid internal gear, the wave generator flexing sections of the body of the flexible external gear perpendicular to an axis of the body into an elliptical shape such that the amount of deflection increases from the diaphragm side thereof toward the opening portion thereof approximately in proportion to distance from the diaphragm, thereby meshing external teeth located at opposite ends of a major axis of the ellipse with the internal teeth, rotation of the wave generator moving the mesh positions of the two gears in a circumferential direction to produce relative rotation between the two gears, which flexible meshing type gear device is a flexible meshing type gear device having a three-dimensional non-interfering wide mesh range tooth profile characterized in that both gears are defined as spur gears of module m, the number of teeth of the flexible external gear as z.sub.F and the number of teeth of the rigid internal gear as z.sub.c =z.sub.F +2g (g being a positive integer), amount of radial deflection of a tooth trace opening portion of the flexible external gear in a section perpendicular to the axis is defined as .kappa..sub.e gm (.kappa..sub.e.ltoreq.1, .kappa..sub.e : opening portion deflection coefficient), amount of radial deflection of an inner extremity of the tooth trace of the flexible external gear is defined as .kappa..sub.i gm (.kappa..sub.i <.kappa..sub.e, .kappa..sub.i : inner extremity deflection coefficient), meshing of the two gears is simulated with racks, similarity transformation is effected on a composite curve consisting of an envelope obtained by axially projecting movement loci of rack teeth relative to each other from the tooth trace opening portion to the tooth trace inner extremity in sections perpendicular to the axis and a movement locus near the tooth trace inner extremity, and the resulting curve is adopted as a basic addendum profile of the external teeth and the internal teeth, rack axial direction deviation from the rack-approximated tooth profile at a contact point in sections perpendicular to the axis that arises in actual meshing is resolved into that caused by an inclination angle of a tooth center line of the external tooth of the flexible external gear relative to a tooth space center line of the internal tooth of the rigid internal gear and that caused by shift of a movement locus of the tooth of the flexible external gear from a rack movement locus, and the basic addendum profile of the external gear and the internal gear is corrected so that an algebraic sum of the resolved deviations becomes zero, a dedendum profile of the internal tooth is formed by effecting similar interference prevention correction on a tooth profile generated by movement as a rack of the uncorrected addendum profile of the external tooth near a major axis of the tooth trace opening portion, and a dedendum profile of the external tooth is formed similarly to the dedendum profile of the internal tooth, with or without imparting some amount of clearance, the external tooth and the internal tooth effecting continuous contact meshing in a section perpendicular to the axis at the tooth trace opening portion of the external tooth and the tooth trace inner extremity, and continuous contact meshing along the tooth trace between the tooth trace opening portion and the tooth trace inner extremity.