A cup-type strain wave gearing having a unit structure and having: a stationary-side part including a unit housing and an internally toothed gear; a driving-side part including an output member and an externally toothed gear; and a sliding bearing supporting the stationary-side part and the driving-side part in the radial direction and the thrust direction in a state in which relative rotation is possible. The sliding bearing has a cylindrical bushing accommodated in a radial gap, and annular bushings accommodated respectively in thrust gaps. Thus, it is possible to provide an advantageous strain wave gearing having a unit structure that is more lightweight and compact than when a rolling bearing is used.

One object is to provide a speed reducer that can absorb or relieve an impact acting thereon. A speed reducer of the present invention includes: a speed reducing unit a housing that houses the speed reducing unit and a shock absorbing means that allows the speed reducing unit to move with respect to the housing in a direction of a rotary shaft of the speed reducing unit.

When a strain wave gearing is used in an application for an operation of repeating startup/stopping, an outer-side lubrication portion and an inner-side lubrication portion, which are lubricated using different types of grease, remain in a communicating state without being divided using a seal member or the like. The outer-side lubrication portion is supplied with a much smaller amount of grease than the amount that would be required if used in an application such as a steady operation. Similarly, the inner-side lubrication portion is also supplied with a much smaller amount of grease than the amount that would be required if used in an application such as a steady operation. Essentially, the outer-side lubrication portion and the inner-side lubrication portion can be lubricated appropriately using different types of grease, without the grease becoming mixed.

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.

A harmonic drive including a housing component (4) and a drive element (18) which is held on the housing component, can be deformed by a wave generator (14), is in the form of a flanged bushing and has a toothing region (17) having a cylindrical basic shape and a disc section (19) which adjoins the toothing region (17). Adjoining the disc section (19) there is a bushing section (20) which is concentric to the toothing region (17), overlaps the latter in the axial direction and is held interlockingly between a cylindrical edge section (21), which is thick-walled in comparison with the bushing section (20), of the housing component (4) and an intrinsically rigid component (22) which is likewise solid in comparison with the flanged bushing (18).

A driving device includes a motor, a wave gear device including a wave generator having first thickness, a flex spline, and a circular spline having thickness larger than the first thickness, a housing functioning as a housing of the motor and including a flange, and an oil seal fixed to the inner side of the flange and extending along the outer circumference of the shaft. The wave generator is set closer to the opposite direction of the flange to configure an internal space with the members. When the internal space is filled with grease, a distance between the oil seal and the wave generator is set smaller than distances among the other members.

An electric motor-brake assembly includes a housing within which a rotor assembly, a stator assembly, and a brake assembly are disposed. The brake assembly is operable between an engaged state and a disengaged state. The rotor assembly is axially movable within the housing and is supported by bearings supporting both radial and axial loads. When the motor stator is de-energized, the brake assembly is in the engaged state to prevent the rotor assembly from rotating in at least one rotational direction. When the motor stator is energized, the brake assembly is in the disengaged state such that the rotor assembly is free to rotate. The brake assembly can include a friction pack that is engaged and disengaged by axial displacement of the rotor assembly.

The 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 having external teeth and 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 flexes the flexible external gear. The harmonic gear device is configured to deform the flexible external gear along with the rotation of the wave generator with the rotation shaft as a center, so that some of the external teeth mesh with some of the internal teeth. The flexible external gear thus rotates relative to the rigid internal gear according to the difference in the number of teeth between the flexible external gear and the rigid internal gear.

This strain wave gear unit includes: a bottomed cylindrical first internal gear having internal teeth formed on a cylindrical part and a teeth-non-formed part protruding farther inward than the tooth bottom of the internal teeth in a corner area where a bottom wall part is integrally connected to the cylindrical part; a flexible cylindrical external gear having external teeth meshing with the internal teeth of the first internal gear, an opposed part opposed to the teeth-non-formed part with a gap therebetween, and an end part opposed to the bottom wall part to make contact therewith; a second internal gear arranged adjacent to the first internal gear and having internal teeth meshing with the external teeth; and a rotation member that causes the external gear to deform in an oval shape and causes the meshing position to move while partially meshing with the first internal gear and the second internal gear.

The tooth profile contours of a rigid internally toothed gear and a flexible externally toothed gear in this strain wave gearing are stipulated by: meshing portions which each mesh with the opposing gear; tooth-crest-side convex surface portions which, respectively, are smoothly connected to the addendum-side ends of the meshing portions and extend from said ends to the apices of the tooth crests; and tooth-bottom-side concave surface portions which, respectively, are smoothly connected to the dedendum-side ends of the meshing portions and extend from said ends to the deepest parts of the tooth bottoms. The meshing portions and tooth-crest-side convex surface portions are machined portions that are simultaneously machined by topping gear cutting, and there are no edges on the teeth of either gear on the tooth-crest side.