Flexible meshing type gear device with negative deflection passing tooth profile

A flexible meshing type gear device with negative deflection passing tooth profile having a rigid internal gear, a flexible external gear inside the internal gear and a wave generator for flexing a section of the external gear perpendicular to its axis into a trilobate shape, causing the flexible external gear to mesh partially with the rigid internal gear and rotating mesh positions of the two gears in a circumferential direction, the rotation of the wave generator producing relative rotation between the two gears, characterized in being provided with the following structural features:

• (a) an amount of radial flexing (w) in a basic section defined perpendicular to a flexible external gear axis at a prescribed point on a tooth trace of the gear is defined to be an amount of negative deviation flexing smaller than a normal amount of flexing (W.sub.0),
• (b) the rigid internal gear and the flexible external gear are both spur gears,
• (c) a number of teeth of the flexible external gear is 3n (n being a positive integer) fewer than that of the rigid internal gear,
• (d) a working tooth profile of either one of the rigid internal gear or the flexible external gear, called a first gear, is defined to be a convex curve whose shape approximates a convex curve obtained by similarity transformation of a peak portion of a rack-approximated moving path of a tooth of the gear with respect to the other, called a second gear, in the basic section of the tooth trace perpendicular to the axis, the portion being convex relative to the second gear, at an enlargement ratio (.lambda.) using an apex of the moving path as an origin, and
• (e) the working tooth profile of the second gear is defined to be a concave curve whose shape approximates a concave curve obtained by similarity transformation of the same portion of the moving path at an enlargement ratio (.lambda.+1) using the apex of the moving path as the origin, whereby meshing of the tooth profiles of the first and second gears is pass messing enabling continuous contact in the basic sector perpendicular to the axis.

A flexible meshing type gear device with negative deflection passing tooth profile having a rigid internal gear, a cup-shaped flexible external gear inside the internal gear and a wave generator for flexing the external gear into an elliptical shape in a section perpendicular to its axis such that an amount of flexing is produced from a diaphragm end to an opening end thereof in approximate proportion to distance from the diaphragm, causing the external gear to mesh partially with the rigid internal gear and rotating mesh positions of the two gears in a circumferential direction, the rotation of the wave generator producing relative rotation between the two gears, characterized in being provided with the following structural features:

• (a) an amount of radial flexing (w) in a basic section defined perpendicular to a flexible external gear axis at a prescribed point on a tooth trace of the gear is defined to be an amount of negative deviation flexing smaller than a normal amount of flexing (W.sub.0),
• (b) the rigid internal gear and the flexible external gear are both spur gears,
• (c) a number of teeth of the flexible external gear is 2n (n being a positive integer) fewer than that of the rigid internal gear,
• (d) a working tooth profile of either one of the rigid internal gear or the flexible external gear, called a first gear, is defined to be a convex curve whose shape is or approximates a convex curve obtained by similarity transformation of a peak portion of a rack-approximated moving path of a tooth of the gear with respect to the other gear, called a second gear, in the basic section of the tooth trace perpendicular to the axis, the portion being convex relative to the second gear, at an enlargement ratio (.lambda.) using an apex of the moving path as an origin, and
• (e) the working tooth profile of the second gear is defined to be a concave curve whose shape approximates a concave curve obtained by similarity transformation of the same portion of the moving path at an enlargement ratio (.lambda.+1) using the apex of the moving path as the origin, whereby meshing of the tooth profiles of the first and second gears is pass messing enabling continuous contact in the basic sector perpendicular to the axis.

A flexible meshing type gear device with negative deflection passing tooth profile having a rigid internal gear, a cup-shaped flexible external gear inside the internal gear and a wave generator for flexing the external gear into a trilobate shape in a section perpendicular to its axis such that an amount of flexing is produced from a diaphragm end to an opening end thereof in approximate proportion to distance from the diaphragm, causing the external gear to mesh partially with the rigid internal gear and rotating mesh positions of the two gears in a circumferential direction, the rotation of the wave generator producing relative rotation between the two gears, characterized in being provided with the following structural features:

• (a) an amount of radial flexing (w) in a basic section defined perpendicular to a flexible external gear axis at a prescribed point on a tooth trace of the gear is defined to be an amount of negative deviation flexing smaller than a normal amount of flexing (W.sub.0),
• (b) the rigid internal gear and the flexible external gear are both spur gears,
• (c) a number of teeth of the flexible external gear is 3n (n being a positive integer) fewer than that of the rigid internal gear,
• (d) a working tooth profile of either one of the rigid internal gear or the flexible external gear, called a first gear, is defined to be a convex curve whose shape approximates a convex curve obtained by similarity transformation of a peak portion of a rack-approximated moving path of a tooth of the gear with respect to the other gear, called a second gear, in the basic section of the tooth trace perpendicular to the axis, the portion being convex relative to the second gear, at an enlargement ratio (.lambda.) using an apex of the moving path as an origin, and
• (e) the working tooth profile of the second gear is defined to be a concave curve whose shape approximates a concave curve obtained by similarity transformation of the same portion of the moving path at an enlargement ratio (.lambda.+1) using the apex of the moving path as the origin, whereby meshing of the tooth profiles of the first and second gears is pass messing enabling continuous contact in the basic sector perpendicular to the axis.