129 results about "Strain wave gearing" patented technology

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.

In a wave gear device, similarity curve tooth profiles for defining the tooth-face tooth profile of each of a flexible externally toothed gear and a rigid internally toothed gear is determined from the movement trajectory, relative to a tooth of the rigid internally toothed gear, of a tooth of the flexible externally toothed gear at a main cross-section at which the deflection factor is κ=1. Tooth profile curves, which have been subjected to profile shifting corresponding to the difference between the deflection factor κo (>1) of the opening-end cross-section of the flexible externally toothed gear and the deflection factor κ of the main cross-section, are determined from the similarity curves; and the tooth profile curves are used to form the tooth-face tooth profile portions of the two gears. High-gear-tooth compound tooth profiles, defined from the tooth-face tooth profile portions, straight-line tooth profile portions continuing from the tooth-face tooth profile portions, and appropriate tooth-flank tooth profile portions for avoiding interference are used as tooth profiles of the internal teeth and the external teeth. Also, taking coning of the flexible externally toothed gear into account, negative profile shifting is applied from an opening-end cross-section to an inner-end cross-section of the flexible externally toothed gear, and rational meshing between the two gears is obtained along the entire tooth trace.

In a flexspline of a wave gear device, an annular flange thereof is constructed from a first annular part bent at a right angle from an outer peripheral edge of a diaphragm, and a second annular part caused to inwardly protrude at a uniform width from a leading end of the first annular part. It is possible for the annular flange to be disposed within the region where the diaphragm is formed, as viewed in the direction of an axis of the device. An outer diameter can be reduced to a greater extent than with a “silk hat”-shaped flexspline; and when a hollow wave gear device is manufactured, a hollow diameter can be more readily increased than in a case where a cup-shaped flexspline is used.

A wave gear device, wherein, when a wave generator is in a low speed rotating state, a rolling bearing state is formed by a wave bearing and the wave generator and a flexible external gear are held in a relatively rotatable state and when the wave generator is in a high speed rotating state, partition pieces and split side plate pieces forming the retainer of the web bearing are displaced to the outside to stop the rotation of balls in their axes and the revolution thereof. Accordingly, a sliding bearing state is formed by lubricating oil film formed between the wave generator and the flexible external gear and the wave generator and the flexible external gear are held in a relatively rotatable state.

The present invention provides a method for manufacturing a rigid internal gear for a wave gear device comprising an internally toothed portion and a gear main body portion comprised of different materials. In this method, a gear main body ring for forming a gear main body portion is preformed using a first aluminum alloy powder; an internal teeth-forming ring is preformed using a second aluminum alloy powder that has lower processability, is less durable, has higher abrasion resistance, and is harder than the first aluminum alloy powder; the internal teeth-forming ring is fitted inside the gear main body ring and the assembly is integrated by powder forging; and the resulting ring-shaped forging is subjected to post-processing, including cutting teeth. The gear main body portion and internally toothed portion are securely integrated by powder forging, and a lightweight rigid internal gear with high durability can therefore be obtained.

A wave gear device has a rigid internal gear, a flexible external gear, a wave generator, and a cross roller bearing for supporting the gears in a relatively rotatable manner. A toroidal composite member that functions as the rigid internal gear and an inner ring of the cross roller bearing has an inner ring-forming member that functions as the inner ring, and an internal teeth-forming member that functions as the rigid internal gear, and the internal teeth-forming member composed of a ductile casting is integrated by diffusion bonding with the inner ring-forming member composed of bearing steel.

A diaphragm of a cup-shaped flexible external gear of a cup-shaped wave gear device having a high reduction ratio of 100 or higher is given a thickness t in a position of a radius r of the diaphragm whereby the thickness t is a value that satisfies the expression A / r2 when A is a constant. The constant A is preferably a value that satisfies the expression 0.0014 D3<A<0.0026 D3, where D is a pitch diameter of the flexible external gear, and the range of the radius r whereby the thickness t is defined as described above in the diaphragm is preferably set to satisfy the expression 0.6 d<r<0.4 D, where d is a diameter of a discoid rigid boss made continuous with an internal peripheral end of the diaphragm. Stress concentration can be alleviated, and it is possible for the allowable transmission torque to be increased compared to the prior art.

A rigid internal gear 2 of the wave gear device is composed by integrating a tooth-forming ring 12 formed with internal teeth, and a main gear ring 11 into a single body. The tooth-forming ring 12 is manufactured from a ferrous or copper material that has superior strength and abrasion resistance, while the main gear ring 11 is manufactured from a lightweight material, such as an aluminum alloy. The outer circumferential surface of the tooth-forming ring 12 is aluminized to form a dispersed aluminum coating 15, before the tooth-forming ring 12 is cast within the main gear ring 11 so as to integrate the main gear ring 11 and the tooth-forming ring 12. Both parts are reliably integrated so that a large amount of torque can be transmitted, whereby realizing a rigid internal gear that is lighter than conventional models.

A flexible external gear of a silk hat shaped wave gear device has an annular body, external teeth formed on an outer circumferential portion of a first opening of the body, a circular diaphragm connected to a second opening portion of the body, and a circular boss connected to an outer circumferential end of the diaphragm. The shape of a connected portion of the diaphragm and the body is defined by a curved portion whose diameter decreases gradually from the diaphragm toward the body when viewed along a device axis. Since the body is wider on the diaphragm side, the wave generator 7 can be easily fitted into the flexible external gear from the diaphragm side.

In a cup-type or “silk hat”-type wave gear device (1), the rim thickness t of the flexible externally toothed gear (3) thereof satisfies the relations (0.5237Ln(R)−1.32)d≦t≦(0.8728Ln(R)−2.2)d if the reduction ratio R of the wave gear device is less than 80, and (1.5499Ln(R)−5.8099)d≦t≦(2.5832Ln(R)−9.6832)d if the reduction ratio R is equal to or greater than 80, where d is the radial deflection, measured at the position of the major axis of the neutral circle of the rim, in a state in which the flexible externally toothed gear is bent into an elliptical shape. The effective face width L of the external teeth (35) is a value within the range of 21 to 30% of the pitch circle diameter. Such settings make it possible to increase the bottom fatigue strength of the flexible externally toothed gear and improve the load capacity of the wave gear device (1).