According to a tooth profile designing method for a strain wave gear device, a first curve from a point A (=0) to a point B (=/2) in a moving locus of external teeth with respect to internal teeth is extracted. A similarity curve is obtained by multiplying the first curve by (1) using the point B as a center of similarity, and a second curve is obtained by rotating the similarity curve by 180 about a midpoint C between the point A and the point B as a center of similarity. A third curve is obtained by multiplying only the x-coordinate of the second curve by (<1), or a fourth curve is obtained by multiplying only the y-coordinate of the second curve by (>1). An addendum tooth profile of the external teeth is defined using the third curve or the fourth curve.

The present disclosure discloses a harmonic reducer with conjugate cycloidal profiles, including a circular spline, a flexspline, a wave generator and a flexible bearing. A profile of the circular spline and a profile of the flexspline are conjugate cycloidal profiles. The profile of the circular spline and the profile of the flexspline are formed by hypocycloids and epicycloids formed by two rolling circles around a pitch circle of the circular spline and a pitch circle of the flexspline under an engaging state respectively. A sum of radii of the first rolling circle and the second rolling circle is equal to a difference between radii of the pitch circle of the circular spline and the pitch circle of the flexspline under the engaging state. The wave generator is a biarc cam wave generator, a cam curve is an arc within an angle of contact in the long axis direction.

A strain wave gearing includes a rigid internally toothed gear, a flexible externally toothed gear disposed coaxially within the internally toothed gear, and a wave generator fitted within the externally toothed gear. The internally toothed gear and the externally toothed gear are spur gears having module m; and the number of teeth of the externally toothed gear is 2n less than the number of teeth of the internally toothed gear, where n is a positive integer. Taking a transverse cross-section at a prescribed position along a tooth trace direction of the external teeth as a main cross-section, a degree of flexing, with respect to a rim-neutral circle of the externally toothed gear prior to ellipsoidal flexing, of a rim-neutral line of the ellipsoidally flexed externally toothed gear is set, at a position on the major axis in the main cross-section, to 2mn.

A method of manufacturing a flexible gear and a method of manufacturing a flexible gear unit that can achieve a further improvement in productivity and a further reduction in production cost, and a gear that allows a further improvement in productivity and a further reduction in production cost are provided. A method of manufacturing a flexible gear is provided which includes preparing a matrix with a flexible gear shape, and forming, by an electroforming method using the matrix, a flexible gear shape with predetermined thickness and releasing the flexible gear shape from the matrix. A method of manufacturing a flexible gear unit is provided which includes the method of manufacturing the flexible gear according to the present technology, and joining a shaft and/or a hub to the flexible gear. Further, a gear is provided which includes a gear part, a body part, and a diaphragm part, is made from a material suitable for an electroforming method, and has flexibility.

One aspect of the present disclosure provides a strain wave gear device including an internal gear, an external gear and a wave generator. The wave generator has a cam and a fourth bearing. The cam has a non-circular outer peripheral surface, and the fourth bearing is positioned between the inner peripheral surface of the external gear and the outer peripheral surface of the cam. The fourth bearing has an outer ring, an inner ring, a plurality of balls, and a retainer. The strain wave gear device includes a restricting portion provided such that the restricting portion can avoid touching the retainer. The restricting portion can restrict the fourth bearing from moving in the direction extending along the axis of rotation.

A drive assembly with selective disconnect includes a motor with a motor drive shaft; a harmonic drive coupled to one end of the motor drive shaft; an output shaft coupled to the harmonic drive; and a retracting mechanism that selectively retracts the motor drive shaft axially to decouple the motor drive shaft from the harmonic drive.

A flat strain wave gearing (1) has a mechanism for preventing a flexible externally toothed gear (4) from moving in the direction of the device center axis (1a) with respect to a rigid internally toothed gears (2, 3). The mechanism has an inner-peripheral groove (11) formed on inner teeth (3a) of the internally toothed gear (3), an outer-peripheral groove (12) formed on outer teeth (4a) of the externally toothed gear (4), and a flexible ring (13) mounted between the inner-peripheral groove (11) and the outer-peripheral groove (12). The ring (13) is engageable with groove inner-peripheral surfaces (11a, 11b, 12a, 12b), from the direction of the device center axis (1a), at meshing positions of the both gears (2, 4).

With a wave gear device, the gears employ homothetic curve tooth profiles AD, BE. Furthermore, a transposition is applied to the external teeth along the tooth trace such that the movement loci M.sub.2, M.sub.3 of the external teeth in a section perpendicular to the axis, from the aperture end to the inner end, share the movement locus M.sub.1 of the aperture end and bottom portion thereof, and a continuous meshing of the teeth in the tooth trace direction is achieved. Furthermore, the tooth bottom rim thickness of the aperture end of the external teeth is optimized using a modified Goodman diagram, and a tooth bottom rim thickness which takes into account the relationship between the tooth profile and the transmitted torque from the aperture end to the inner end is employed for the flexible external gear.

A rotary actuator includes a housing having a first end and a second end spaced from the first end along an axis. The housing defines a cavity extending circumferentially about the axis. An output shaft is arranged coaxially with the axis. The output shaft extends outwardly from the cavity through the first end. A drive system is disposed in the cavity and axially spaced from the first end. A gearbox is disposed in the cavity between the output shaft and the drive system. The gearbox is coupled to the drive system and the output shaft. A rotational controller is disposed in the cavity between the drive system and the second end. The rotational controller is configured to actuate the drive system to adjust an angular position of the output shaft.

A harmonic gear device includes a rigid internal gear, a flexible external gear and a wave generator. The rigid internal gear is an annular component having internal teeth. The flexible external gear is an annular component, which has external teeth and is configured on an inner side of the rigid internal gear. The wave generator is configured on an inner side of the flexible external gear, and deflects the flexible external gear. The harmonic gear device deforms the flexible external gear along with the rotation of the wave generator taking a rotation axis as the center, such that some of the external teeth mesh with some of the internal teeth. The flexible external gear rotates relative to the rigid internal gear in accordance with the difference between the numbers of teeth of the flexible external gear and the rigid internal gear.