Machine element or mechanism – Gearing
Patent
1997-02-26
1998-12-22
Wright, Dirk
Machine element or mechanism
Gearing
475162, F16H 132
Patent
active
058507655
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a wave gear drive, and particularly to a flat wave gear drive which can be formed compactly and cheaply by a reduced number of parts.
BACKGROUND OF THE INVENTION
There have been known wave gear drives having a flexible external gear of the type which has an annular shape, a cup shape, or a silk-hat shape. Among those gear drives, the applicant of the present patent application proposes a wave gear drive having a flat silk-hat-shaped flexible external gear in Japanese Patent Application Nos. HEI 6-310834 and HEI 6-310835. A wave gear drive can be formed flat by using this type of flat silk-hat-shaped flexible external gear.
SUMMARY OF THE INVENTION
An object of the present invention is to make flat, to make small and compactly and to reduce manufacturing cost of the wave gear drive having a silk-hat-shaped flexible external gear. In particular, an object of the present invention is to realize a flat wave gear drive having a structure suitable for adopting the above-mentioned flat silk-hat-shaped flexible external gear.
In order to realize the above objects, in a flat wave gear drive according to the present invention, a device is defined at both ends thereof in an axial direction by a first and a second end plates, respectively, between which a silk-hat-shaped flexible external gear is incorporated, which comprises an annular body, external teeth formed on an outer circumferential surface of an opening end at the side of the first end plate of the body, an annular diaphragm extending continuously and outwardly along the radial direction from an opening end at the side of the second end plate of the body, and an annular thick boss extending from the outer edge of the diaphragm. A rigid internal gear is provided around the external teeth, which is formed at an inner circumferential surface thereof with internal teeth engageable with the external teeth. A wave generator is provided inside the annular body where the external teeth are formed, which flexes the annular body radially to engage the external teeth with the internal teeth partially and moves the tooth-engaged portions along a circumferential direction. Further, an input shaft is provided in a state extending along the axial direction, which is fixed to the wave generator and is rotatably supported at one end thereof by the first end plate, while is rotatably supported at the other end thereof by the second end plate. A bearing is provided around the annular body of the flexible external gear, in which its outer ring is fixed via the annular boss to the second end plate and its inner ring is fixed via the rigid internal gear to the first end plate.
The bearing is preferably a cross roller bearing. It is preferred in this case that the cross roller bearing is provided between the annular boss of the flexible external gear and the circular rigid internal gear, wherein the outer ring of the bearing, the second end plate and the annular boss are fastened to one another such that the annular boss is sandwiched between the circular end surface of the outer ring of the bearing and the inner circular end surface of the second end plate, and the inner ring of the bearing, the first end plate and the rigid internal gear is fastened to one another such that the rigid internal gear is sandwiched between the circular end surface of the inner ring of the bearing and the inner circular end surface of the first end plate.
Furthermore, where the input shaft is a hollow input shaft, it is preferred that a through hole is formed extending through the device along its axial direction.
In the flat wave gear drive according to the present invention, both axial ends thereof are defined by the first and second end plates. Between the first and second end plates, the components of the wave gear drive, namely the flexible external gear, rigid internal gear and wave generator are arranged. The bearing is provided around the flexible external gear, wherein the inner and outer rings thereof are fixed at the sides of the first and s
REFERENCES:
patent: 4770059 (1988-09-01), Beyer
patent: 4784014 (1988-11-01), Bruns et al.
patent: 4825720 (1989-05-01), Capdepuy
patent: 4840090 (1989-06-01), Iwata
patent: 5222409 (1993-06-01), Dalakian
patent: 5269202 (1993-12-01), Kiyosawa et al.
patent: 5470283 (1995-11-01), Seidou
patent: 5687620 (1997-11-01), Ishikawa
Harmonic Drive Systems Inc.
Kwon Peter T.
Wright Dirk
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