A toothed gear for use in a gearing, comprising a base body that forms a ring gear with a number of first teeth having a first deformability and a number of second teeth having a second deformability, wherein the second deformability is greater than the first deformability and to a gear pair of a gearing, comprising such a toothed gear and at least one further toothed gear which can be made to mesh or is in mesh with the toothed gear. The invention relates moreover to a gearing with such a gear pair.

A cup-shaped strain wave gearing has an externally toothed gear formed with a cylindrical extension portion extending from an end of an external tooth forming portion of the externally toothed gear. A space between the external peripheral surface of the cylindrical extension portion and an end face of an internally toothed gear is sealed by an oil seal. A space between an outer-side lubrication portion on the outer side of the externally toothed gear and an inner-side lubrication portion on the inner side of the externally toothed gear is blocked by a lubricant-mixing-prevention part configured from the cylindrical extension portion and the oil seal. The mixing of different types of lubricants supplied to the outer-side and inner-side lubrication portions can be effectively prevented.

A bending meshing type gear device includes a wave generator, an external gear which is bent and deformed by the wave generator, and an internal gear which meshes with the external gear, in which one gear of the external gear and the internal gear is formed of a resin, the other gear of the external gear and the internal gear is formed of a high thermal conductivity material having a thermal conductivity higher than that of the resin and wear resistance higher than that of the resin, and a tooth thickness of the one gear is larger than a tooth thickness of the other gear in a meshing range between the external gear and the internal gear.

An externally toothed gear of a dual-type strain wave gearing is provided with first and second external teeth having different teeth numbers, and a gap formed between these teeth as a cutter clearance area for tooth cutters. Where L1 is the maximum width of the gap, t1 is a depth from the tooth top land of the first external teeth to the deepest part of the gap, h1 is the tooth depth of the first external teeth, t2 is a depth from the tooth top land of the second external teeth to the deepest part, and h2 is the tooth depth of the second external teeth, any one of the following conditions 1 to 3 is satisfied:

L1=0.1L0.35L, t1=0.9h11.3h1, and t2=0.3h20.9h2Condition 1:

L1=0.1L0.35L, t1=0.3h10.9h1, and t2=0.9h21.3h2Condition 2:

L1=0.1L0.35L, t1=0.3h10.9h1, and t2=0.3h20.9h2Condition 3:

It is possible to obtain a dual-type strain wave gearing in which wear resistance and tooth bottom fatigue strength are increased.

Provided is a strain wave gear speed reducer which can improve both load torque performance and productivity, a method for manufacturing a strain wave gear speed reducer, and an actuator for link mechanism for internal combustion engine. A strain wave gear speed reducer includes; a flexible external gear having a plurality of external teeth each of which has a straight tooth profile; a rigid internal gear disposed on an outer periphery of the flexible external gear, the number of internal teeth of the rigid internal gear being greater than the number of the external teeth, the internal tooth having a straight tooth profile, and a tooth top of the internal tooth having a shape which matches or overlaps with a movement envelope of the external tooth as viewed from a direction of an axis of rotation of the flexible external gear; and a wave motion generator configured to cause the flexible external gear to be deflected in a radial direction so as to be partially engaged with the rigid internal gear, the wave motion generator being configured to rotate about an axis of rotation, thus causing an engagement portion to move in a circumferential direction.

It is included an internal gear (2), an external gear (3) having flexibility, and a wave generator (4) that forms a meshing part (P) with the internal gear (2) in the external gear (3) and moves the meshing part (P) in a circumferential direction of the internal gear (2). The wave generator (4) is configured such that the meshing part (P) is formed at three or more positions in a circumferential direction of the external gear (3). A value (Dp.sub.F/Z.sub.F) obtained by dividing a working pitch diameter Dp.sub.F of the external gear (3) by the number of teeth Z.sub.F is greater than a value (Dp.sub.R/Z.sub.R) obtained by dividing a working pitch diameter Dp.sub.R of the internal gear (2) by the number of teeth Z.sub.R.

A toothed gear for use in a gearing, comprising a base body that forms a ring gear with a number of first teeth having a first deformability and a number of second teeth having a second deformability, wherein the second deformability is greater than the first deformability and to a gear pair of a gearing, comprising such a toothed gear and at least one further toothed gear which can be made to mesh or is in mesh with the toothed gear. The invention relates moreover to a gearing with such a gear pair.

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.

A robot includes a first member, a second member, a gear device transmitting a driving force for relatively pivoting the second member, and a driving source outputting the driving force to the gear device, wherein the gear device includes an internal gear, an external gear having flexibility and partially meshing with the internal gear, and a wave generator that is in contact with an inner circumferential face of the external gear and moves a meshing position of the internal gear and the external gear along a circumferential axis, and the external gear contains nickel chromium molybdenum steel as a main material, and the internal gear contains spheroidal graphite cast iron having been subjected to quenching and tempering treatment or spheroidal graphite cast iron having been subjected to austempering treatment as a main material.

It is included an internal gear (2), an external gear (3) having flexibility, and a wave generator (4) that forms a meshing part (P) with the internal gear (2) in the external gear (3) and moves the meshing part (P) in a circumferential direction of the internal gear (2). The wave generator (4) is configured such that the meshing part (P) is formed at three or more positions in a circumferential direction of the external gear (3). A value (Dp.sub.F/Z.sub.F) obtained by dividing a working pitch diameter Dp.sub.F of the external gear (3) by the number of teeth Z.sub.F is greater than a value (Dp.sub.R/Z.sub.R) obtained by dividing a working pitch diameter Dp.sub.R of the internal gear (2) by the number of teeth Z.sub.R.