Abstract: A strain wave gearing is lubricated by a non-hydrophobized powder enclosed in an internal space until the strain wave gearing is fully broken in, and the non-hydrophobized powder is transferred to contact surfaces of contact parts to form a lubricating film. During operation under load, the strain wave gearing is lubricated by a hydrophobized powder enclosed in the internal space instead of the non-hydrophobized powder. Each of the powders used is a powder of an ionic crystalline compound (MoS2, WS2, etc.) having a layered crystal structure. By lubricating the strain wave gearing with the hydrophobized powder during operation under load, any temporary decrease in efficiency at the start of operation is minimized and stable operation of the strain wave gearing can be maintained.

Abstract: In this optical rotary encoder, detection tracks of a rotating disc are irradiated with detection light emitted from a light-emitting element. An optical signal obtained via slits in the detection tracks passes through a slit pattern in a fixed slit plate and is received by light-receiving surfaces of a light-receiving element. The slit pattern in the fixed slit plate is formed so as to fit into a range of an effective spot of the detection light. An LED or other light-emitting element that has a small effective spot diameter can be used, which is advantageous in terms of reducing costs and making the device more compact.

Abstract: 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=0.1L?0.35L, t1=0.9h1?1.3h1, and t2=0.3h2?0.9h2??Condition 1: L1=0.1L?0.35L, t1=0.3h1?0.9h1, and t2=0.9h2?1.3h2??Condition 2: L1=0.1L?0.35L, t1=0.3h1?0.9h1, and t2=0.3h2?0.9h2??Condition 3: It is possible to obtain a dual-type strain wave gearing in which wear resistance and tooth bottom fatigue strength are increased.

Abstract: A double-row cylindrical roller bearing employs a cross roller bearing for one cylindrical roller bearing and a parallel cylindrical roller bearing for the other cylindrical roller bearing. The relative positions of a first cylindrical roller on the cross roller bearing part side and a second cylindrical roller on the parallel cylindrical roller bearing part side are not restricted in the direction of the bearing center axis lines thereof. As a result, a bearing having high rigidity and being easy to process and assemble can be achieved at low cost. Increase in friction torque in bearing sliding sections and fluctuation in bearing properties can also be suppressed.

Abstract: A wave bearing of a wave generator of a strain wave gearing is provided with steel or stainless steel cylindrical hollow rollers between an inner-race-side raceway surface and an outer-race-side raceway surface, the hollow rollers serving as rolling elements. The ratio Di/Do of the inner diameter Di to the outer diameter Do of the hollow rollers is set to 0.95 or more. The relative radius of curvature of hollow rollers that have been flexed into an ellipsoidal shape increases with respect to the inner-race raceway surface and the outer-race raceway surface with which the hollow rollers are in contact, and the Hertz maximum contact stress is reduced. The hardness of the hollow rollers, the inner-race raceway surface, and the outer-race raceway surface can be reduced.

Abstract: A restraint mechanism for limiting the movement of the flexible external gear of a flat strain wave gearing in the axial direction has a first restraining member installed in a floating state in a first recess and a second restraining member installed in a floating state in a second recess. The restraining member is able to limit the movement of the flexible external gear in the axial direction to a range in which there are no difficulties during actual use. Moreover, compared with when movement of the flexible external gear is limited using members that are disposed at fixed positions, it is possible to reduce the sliding abrasion that occurs between the flexible external gear and the first and second restraining members.

Abstract: A wave gear device includes a circular spline that has an annular shape and rigidity; a flex spline that has an annular shape and flexibility, and is disposed in the circular spline; and a wave generator that is disposed in the flex spline, is configured to cause the flex spline to be distorted in a radial direction and is configured to partially mesh with the circular spline, and is configured to move a meshing position between the circular spline and the flex spline in a circumferential direction. The ratio of the Vickers hardness on an inner circumferential surface of the flex spline to the Vickers hardness on an outer circumferential surface of the wave generator is 1.2 or more and 1.7 or less.

Abstract: In a rotation transmission mechanism that transmits the rotational driving force of a motor to a load-side member via a speed reducer, a strain wave gearing is used as the speed reducer, and the allowable load torque of members in the powertrain other than the strain wave gearing is greater than a predetermined upper-limit load torque. The allowable load torque of the strain wave gearing is dictated by the ratcheting torque, which is set so as not to exceed the upper-limit load torque. In an overload state, ratcheting is generated in the strain wave gearing, so that the strain wave gearing functions as a mechanical fuse. Other power transmission members can be protected from an overload state without adding a separate member such as a torque limiter.

Abstract: A rotary actuator has a hollow motor and hollow reduction gears arranged coaxially on either side of the hollow motor. A rotary shaft is arranged so as to pass through a hollow motor shaft of the hollow motor. The hollow reduction gears have hollow input shafts connected to the shaft ends on either sides of the hollow motor shaft. The hollow reduction gears have hollow output shafts connected to sections of the rotary shaft protruding from both ends of the hollow motor shaft. The connection position of the hollow output shaft with respect to the rotary shaft can be adjusted in the rotational direction. A load is rotationally driven by the rotary shaft. By increasing the axial length of the hollow motor, it is possible to obtain a small-diameter rotary actuator having a rotational output with large torque.

Abstract: A wave generator for a strain wave gearing is provided with a rigid plug having an ellipsoidal plug-outer-circumferential surface, and a ring-shaped displacement body that is flexed to an ellipsoidal shape by the plug. The ring-shaped displacement body is provided with a plurality of radially arranged displacing sections. The plug-contacting surfaces of the displacing sections are in sliding contact with the plug-outer-circumferential surface and when the plug rotates, the displacing sections are repeatedly displaced in the radial direction. By the displacement of the displacing sections, wave motion is generated in an external gear. It is possible to achieve a wave generator capable of generating wave motion in the external gear with a small rotational torque.

Abstract: A wave gear device includes a circular spline that has an annular shape and rigidity; a flex spline that has an annular shape and flexibility, and is disposed in the circular spline; and a wave generator that is disposed in the flex spline, is configured to cause the flex spline to be distorted in a radial direction and is configured to partially mesh with the circular spline, and is configured to move a meshing position between the circular spline and the flex spline in a circumferential direction. The ratio of the Vickers hardness on an inner circumferential surface of the flex spline to the Vickers hardness on an outer circumferential surface of the wave generator is 1.2 or more and 1.7 or less.

Abstract: A wave generator for a strain wave gearing makes a flexible externally toothed gear to flex into an elliptical shape and mesh with rigid internally toothed gears, and makes meshing positions of the flexible externally toothed gear with the both gears to move in a circumferential direction. On the inner side of a rigid plug of the wave generator, a plug support ring is secured and integrated. The rigid plug is formed from an iron-based material, and the plug support ring is formed from a high-rigidity material that is more rigid than the iron-based material. Since deformation of the rigid plug is suppressed, the wave generator provided with a large hollow part can be obtained.

Abstract: A wave generator of a strain wave gearing is provided with a rigid plug, a wave bearing mounted to the ellipsoidal outer peripheral surface of the rigid plug, and four elastic claws that rotate integrally with the rigid plug. The balls of the wave bearing include balls in a loose state and balls in a tight state. The loose-state balls adjacent to the tight-state balls are applied with braking force by the elastic claws immediately before they transition into a tight state, and the orbital motion thereof is temporarily prevented or suppressed, whereby the gaps between the loose-state balls and the adjacent tight-state balls are secured. It is possible to prevent increase in rotational torque, damage to the balls or other defects due to ball-to-ball contact by the tight-state balls.

Abstract: A strain wave gearing has a cup-shaped externally toothed gear that is provided with a body formed with external teeth, a diaphragm extending from an end of the body, and a rigid boss integrally formed in the diaphragm. The ratio B/A is set equal to or less than 0.59 where A is the reference pitch circle diameter of the external teeth and B is the outer diameter of the boss. The radial length from the inner peripheral edge of the diaphragm to the outer peripheral edge thereof in the present externally toothed gear is large. This enables to reduce bending stress generated in each part of the externally toothed gear due to coning, and a meshing state of the external teeth with the internal teeth in the tooth trace direction can also be improved, whereby further flattening of the externally toothed gear can be realized.

Abstract: A silk hat-type strain wave gear device has a crossed roller bearing for supporting an internal gear and an external gear so as to allow relative rotation. A first gap part between the inner and outer rings of said bearing is sealed by an oil seal and a second gap part thereof is in communication with a gear-side gap part on the outside of the external gear. A bearing seal separates the second gap part from the gear-side gap part. The bearing seal prevents excessive inflow of lubricant from the gear-side gap part into the second gap part. Excess lubricant that has flowed into the bearing can flow back from the second gap part to the gear-side gap part. Excess lubricant in the bearing is prevented from leaking through the oil seal to the outside.

Abstract: 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.

Abstract: The flexible external gear of a strain wave gearing is provided with: a cylindrical body part capable of flexing in the radial direction; external teeth formed on the outer circumferential surface thereof with a constant pitch; and grooves formed on the inner circumferential surface of the cylindrical body section along the circumferential direction thereof with the same pitch as the external teeth. The grooves are grooves with a wave-shaped cross-sectional shape having the center line of the tooth crest of the external tooth as the center and extend in the width direction of the external teeth. It is possible to increase the tooth bottom fatigue strength of the flexible external gear by increasing the tooth bottom thickness, while maintaining ease of flexing and a tooth shape that can withstand tangential forces due to meshing.

Abstract: In a strain wave gearing, the addendum tooth profile of an internal gear is defined by the formula a and that of an external gear is by the formula b at a principal cross-section located at a tooth-trace-direction center of the external gear, on the basis of a movement locus (Mc) of ?=1 of the teeth of the external gear with respect to those of the internal gear in the principle cross-section taken at the center of the tooth trace of the external gear obtained when the tooth meshing is approximated by rack meshing. It is possible to avoid superimposition of flexion-induced bending stresses and tensile stresses caused by load torque at the major-axis locations of the external gear, and the transmission torque capacity of a strain wave gearing can be improved.

Abstract: In a strain wave gearing, the addendum tooth profile of an internal gear is defined by the formula a and that of an external gear is by the formula b at a principal cross-section located at a tooth-trace-direction center of the external gear, on the basis of a movement locus (Mc) of ?=1 by the teeth of the external gear with respect to those of the internal gear. It is possible to avoid superimposition of flexion-induced bending stresses and tensile stresses caused by load torque at the major-axis locations of the external gear, and the transmission torque capacity of a strain wave gearing can be improved.

Abstract: An internal contact part of a wave generator of a strain wave gearing, a contact part between an externally toothed gear and the wave generator, and tooth surface parts are lubricated by a lubricating fine powder. When the strain wave gearing is in operation, the lubricating fine powder is supplied to the internal contact part and the contact part by a first powder guide that rotates integrally with the wave generator. Having passed through these sections, the lubricating fine powder is supplied to the tooth surface parts by a second powder guide that rotates integrally with the wave generator. Each component part can be reliably lubricated regardless of the orientation of the strain wave gearing during operation.