The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 13, 2010
Filed:
Jan. 11, 2007
Shoichi Ishikawa, Yokohama, JP;
Noboru Takizawa, Azumino, JP;
Shoichi Ishikawa, Yokohama, JP;
Noboru Takizawa, Azumino, JP;
Harmonic Drive Systems Inc., Tokyo, JP;
Abstract
A wave gear drive comprises a circular rigid internal gear and a flexible external gear inside the rigid internal gear. A wave generator in the flexible external gear flexes the flexible external gear into an elliptical shape. The cross-section of the flexible external gear perpendicular to the axis at a point in the tooth trace direction of the flexible external gear is set as the main cross-section. The rigid internal gear and flexible external gear are gears with a module m, and the flexible external gear has a number of teeth that is smaller than the number of teeth of the rigid internal gear. The moving route M of a tooth of the flexible external gear with respect to a tooth of the rigid internal gear that accompanies rotation of the wave generator when meshing of the teeth in the main cross-section is approximated by rack meshing. On the entering side of the meshing of the teeth to the major axis of the moving route M, a first similar curve AC is obtained by similarity transformation of a pressure angle .alpha. orthogonal to the direction of the moving route M. The first similar curve AC is employed as the basic addendum tooth profile of the rigid internal gear. A second similar curve CB is obtained by rotating the first similar curve AC 180° about endpoint C, and by a similarity transformation in which the first similar curve AC is multiplied by a ratio of similitude (1−λ)/λ. The second similar curve CB is employed as the basic addendum tooth profile of the flexible external gear.