Strain wave gearing

Abstract: A strain wave gearing comprising a circular spline, flexspline disposed inside the circular spline, a wave generator for deforming the flexspline into, for example, an ellipsoid and a motor for rotating the wave generator to produce a relative rotation between the flexspline and the circular spline. The strain wave gearing is sometimes termed a harmonic drive transmission. In the strain wave gearing, the tooth face of each of the splines is formed in line with a mapping curve which is a similarity transformation having a reduced scale of 1/2 applied to a movement locus of the flexspline to the circular spline in accordance with the configuration of the wave generator, the transformation being effected on a reference point where the splines are transferred from the contact condition to a disengagement from each other. Thus, the teeth of the flexspline engage with those of the circular spline in the broad extent of the engagement region.

Abstract: A strain wave gearing comprising a circular spline, flexspline inside the circular spline, a wave generator for deforming the flexspline into, for example, an ellipsoid and a motor for rotating the wave generator to produce a relative rotation between the flexspline and the circular spline. The strain wave gearing is sometimes termed a harmonic drive transmission, and there is a type of gearing called flat-shaped strain wave gearing which is composed of two circular splines juxtaposed with each other, a flexspline in the circular splines having the same number of teeth as the first circular spline, a wave generator for deforming the flexspline into an ellipsoid and a motor for rotating the wave generator. In the flat-shaped gearing, each tooth of the flexspline is provided with a convex tooth face and a concave tooth flank. The tooth profile of the first circular spline is given by such a locus curve that the tooth face of the flexspline plots when the deformed configuration of the flexspline is rotated by the wave generator, and the tooth depth of the first circular spline is made equal to or larger than the working depth of the flexspline. Thus, the teeth of the flexspline engage with those of the first circular spline in the broad extent of the engagement region.

Abstract: The invention provides a compact and highly reliable motor vehicle steering device that does not require a spiral flat cable. The motor vehicle steering device includes variable gear ratio system that modifies the transmission ratio of the rotary motions between first steering shaft and second steering shaft. Variable gear ratio system comprises Strain Wave Gearing Speed Reducer that modifies the transmission ratio between first steering shaft and second steering shaft in response to the rotating speed of motor shaft. Motor shaft and second steering shaft forms a substantially concentric dual structure, drive motor is affixed, and output shaft is connected to motor shaft.