Harmonic Drive Systems Inc.

Yuya Murayama

Yoshihide Kiyosawa

Yoshitomo Mizoguchi

Norio Shirokoshi

Naoki Kanayama

Satoshi Kishi

Shizuka Yata

According to a tooth profile designing method for a strain wave gear device, a first curve from a point A (φ=0) to a point B (φ=π/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−λ) 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 α (α<1), or a fourth curve is obtained by multiplying only the y-coordinate of the second curve by β (β>1). An addendum tooth profile of the external teeth is defined using the third curve or the fourth curve.

Tooth profile designing method for strain wave gearing

A speed ratio switching type strain wave gearing can switch the speed ratio of output rotation with respect to one input rotation into two states or multiple states with a simple configuration. The speed ratio switching type strain wave gearing includes first and second internally tooted gears, an externally toothed gear having first and second external teeth formed on the external peripheral surface thereof, a wave generator that causes the first and second external teeth to partially mesh with the first and second internally toothed gears, a clutch mechanism that can selectively switch the first and second internally toothed gears into a fixed state. Input rotation from the wave generator can be reduced in speed at a different speed ratio and derived from the externally toothed gear by selectively switching the first and second internally toothed gears into a fixed state.

Speed ratio switching type strain wave gearing

A strain wave gearing has a wave generator which flexes an externally toothed gear in a radial direction to form meshing portions thereof with an internally toothed gear in positions that are separated along a circumferential direction of the externally toothed gear. When the wave generator rotates, the meshing portions move in the circumferential direction. Non-meshing regions are formed in part of the meshing portions along the tooth trace direction thereof. The non-meshing regions are those of a prescribed width including the support center of a wave bearing in the tooth trace direction. The concentration of stress in the tooth root of the externally toothed gear can be alleviated, and the tooth-root fatigue strength of the externally toothed gear can be increased.

Strain wave gearing

A strain wave gearing wherein the tooth profile of an external teeth of a cup-shaped or silk-hat-shaped external gear is set as follows. The tooth-tip tooth thickness decreases gradually from an external-teeth outer end toward an external-teeth inner end along an external tooth trace direction. In addition, a pressure angle at a pitch point (P) increases gradually from the external-teeth outer end toward the external-teeth inner end along the external tooth trace direction. Thus, it is possible to realize a cup-type or silk-hat-type strain wave gearing in which external teeth mesh with internal teeth in a wide range along the tooth trace direction, rather than only in one cross-section perpendicular to the axis in the tooth trace direction.

Strain wave gearing having 3-dimensional meshing tooth profile

The roller insertion groove of the inner ring of a crossed roller bearing is provided with an outer circumferential surface-side groove opening that is exposed to an inner rings-side V-groove. The groove opening is defined by circumferential direction opening edge that extends in the circumferential direction along the inner ring-side V-groove and side opening edges that extend from both ends of the circumferential direction opening to the ring-shaped end face of the inner ring. Concentration of stress occurs in the corners between the circumferential direction opening edges and the side opening edges. The circumferential direction opening edge is formed so as not to coincide with the minimum outer diameter section of the inner ring-side V-groove.

Crossed roller bearing

In this hollow strain wave gearing unit, a shaft end part of a hollow rotary shaft of a wave generator is located inside a cup-shaped flexible external gear. The shaft end part is supported by a bearing attached to a bearing holder that is fixed to a boss of the flexible external gear. In the bearing holder, an elastic leaf spring part that is displaceable in the axial direction constitutes a part that supports a holder body part that holds the bearing. A preload is applied by the leaf spring part to the bearing in the axial direction. Thus, there is no need to separately arrange a preload application member inside the flexible external gear, and the axial length of the hollow strain wave gearing unit can be shortened.

Bearing holder, bearing mechanism, and strain wave gearing device

A hollow-type strain wave gearing unit has a cup-shaped flexible externally-toothed gear, in which one shaft end portion of a hollow rotation shaft of a wave generator is located. The shaft end portion is supported by a bearing mounted on a bearing holder fixed to a boss of the flexible externally-toothed gear. The bearing holder has a retainer holding portion to prevent a retainer of a wave generator bearing from coming off in the axis line direction. There is no need to dispose a retainer holding plate of the wave generator bearing inside the flexible externally-toothed gear, whereby the axial length of the hollow-type strain wave gearing unit can be reduced.

A hollow-type strain wave gearing unit () has a sealing member () for sealing a gap () opening to the inner peripheral surface of a unit hollow portion () passing through in an axis () direction. The gap () includes a gap section () between an outer peripheral side end race () on the wave generator side and a boss side end face (), both faces opposing each other in the axis () direction, and the sealing member () is assembled therein. The gap section () is formed in a state partially entering the inside of the inner ring () of the second bearing () supporting the wave generator (). It is possible to realize a hollow-type strain wave gearing unit with a sealing mechanism that is suitable for increasing the inner diameter of the unit hollow portion and for reducing the unit axial length.

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Azumino, Japan

Yuya Murayama