The invention relates to a wave generator for a strain wave gear, said wave generator in a main portion having a bearing seat for a radially flexible roller bearing. The wave generator is distinguished by having a cone portion that adjoins the main portion in the axial direction and tapers off in a direction away from the main portion.

A wave generator of a strain wave gearing has a rigid plug provided with an elliptical outer peripheral surface, and a roller bearing. The outer peripheral surface of the plug is provided with a major-axis-side outer-peripheral surface portion formed at a major axis position L1, and a minor-axis-side outer-peripheral surface portion formed at a minor axis position L2. The major-axis-side outer-peripheral surface portion is a tapered surface that is tapered along a center axis line, and the minor-axis-side outer-peripheral surface portion is an inverted tapered surface that is tapered in the opposite direction. An externally toothed gear can be supported and flexed into an elliptical shape without partial contact by using the wave generator in which the roller bearing is used.

A strain wave gearing has contact parts which are the portions to be lubricated other than the teeth of an externally toothed gear and an internally toothed gear, the contact parts being respectively lubricated with an inorganic lubricating powder having a lamellar crystal structure. The lubricating powder, during the operation of the strain wave gearing, is crushed between the contact surfaces of each of the contact parts to move and adhere to the contact surfaces, thereby forming thin surface films thereon. Additionally, the powder is thinly spread by pressure and reduced into finer particles to change into a shape which facilitates intrusion into the space between the contact surfaces. By both the fine particles having changed in shape and the surface films, the lubrication of the contact parts is maintained. Neither the fine particles nor the surface films are viscous.

A harmonic drive assembly and fluid-powered linear motors with both axial pistons are rotary piston arrangements incorporating the harmonic drive assembly are disclosed. The motors may be used in downhole drilling applications, but the drive assembly and/or motors may be used in other applications. The assembly, motors and methods use advanced harmonic drives, advanced helical drives, and combinations thereof with 1) motors with axial pistons and reciprocating linear rings to convert reciprocative axial motion to continuous rotary motion, and 2) motors with rotary pistons and reciprocating linear rings to rectify reciprocative rotary motion to continual rotary motion to improve performance over prior configurations. Axial pistons provide a robust simple solution for generating rotation; Rotational pistons provide increased torque generation as the torque generated is proportional to motor length. Since downhole drills are long, a high-torque motor can be produced using this method.

A strain wave gearing unit has a unit housing, a strain wave gearing, and a bearing device. Balls of a bearing part of the bearing device are positioned on the diametrically outer side with respect to a cylindrical barrel part of an externally toothed gear. The diameter S of the balls is 0.05 to 0.15 times the pitch diameter D of the externally toothed gear. The centers of the balls are positioned between a point at a distance of 1.2 times the diameter S toward the cylindrical-barrel-part side from an inner-side end surface of a diaphragm along a center axis and a point at a distance of 1 times the diameter S toward a side opposite the cylindrical barrel part from the inner-side end surface. The bearing device can be configured to be used in common for strain wave gearing units having different axial lengths.

A harmonic drive includes an internally toothed housing element (2), a pot-shaped output element (4) which is mounted in the housing element (2), and a likewise pot-shaped, resilient drive element (19) which is connected to the output element (4) and has an external toothing system (13) which meshes with the internal toothing system (14) of the housing element (2). A spring element (35) is active between the housing element (2) and the output element (4), which spring element (35) is arranged in an annular chamber which is delimited radially to the inside by a sleeve section (24) of the resilient drive element (19), radially to the outside by a cylindrical section (5) of the output element (4), and in the axial direction firstly by an annular disc-shaped surface (23) of the housing element (2) and secondly by a bottom (9) of the output element (4).

A unit-type strain wave gearing device provided with a cross roller bearing that supports an internally toothed gear and an externally toothed gear in a state in which both gears can rotate relative to each other, and a meshing section of both gears is lubricated with grease. A gap by which the meshing section and the cross roller bearing raceway groove communicate is formed between the inner ring of the cross roller bearing and the external gear. Due to the pump effect caused by deflection of the external gear, grease is pushed from the meshing section to the gap. Some grease is returned to the inner space of the externally toothed gear via a grease-flowing hole that penetrates the diaphragm of the external gear. Thus, leakage of grease from an oil seal of the cross roller bearing to the unit side can be controlled.

A gear device includes an external gear, and an internal gear that meshes with the external gear. The external gear is formed of metal. The internal gear is formed of a carbon fiber reinforced resin.

Methods for the fabrication of metal strain wave gear flexsplines using a specialized metal additive manufacturing technique are provided. The method allows the entire flexspline to be metal printed, including all the components: the output surface with mating features, the thin wall of the cup, and the teeth integral to the flexspline. The flexspline may be used directly upon removal from the building tray.

Provided is a double-flexspline harmonic reducer, comprising a strong flexspline (3), a weak flexspline (2) and a wave generator (1). The strong flexspline (3) and the weak flexspline (2) are coaxially fixed in an axial direction and a radial direction, and teeth which can be engaged with each other and are different in the number thereof are provided on the strong flexspline (3) and the weak flexspline (2) respectively. The wave generator (1) causes the weak flexspline (2) to undergo non-circular elastic deformation and then to partially engage with the strong flexspline (3), and a contact portion of the strong flexspline (3) and the weak flexspline (2) undergoes non-circular elastic deformation under a radial pressure from the weak flexspline (2). A wall thickness of the strong flexspline (3) is greater than or equal to 2 times and less than 5 times that of the weak flexspline (2).