Machine element or mechanism – Gearing
Reexamination Certificate
1999-08-02
2001-06-26
Marmor, Charles A (Department: 3681)
Machine element or mechanism
Gearing
Reexamination Certificate
active
06250179
ABSTRACT:
TECHNICAL FIELD
This invention relates to a silk hat flexible engagement gear device which can be manufactured small and compactly, and at the same time cheaply with using a small number of component parts.
BACKGROUND ART
As the flexible engagement gear device, such types are known whose component part, flexible external gear is of a circular shape, a cup shape, and a silk hat shape. Among these types of flexible engagement gear devices, the applicant of this application has proposed a flexible engagement gear device having a flat silk-hat flexible external gear in JP-A 8-166051 and JP-A 8-166052. Using a flat silk-hat flexible external gear makes it possible to constitute a flexible engagement gear device flat.
DISCLOSURE OF INVENTION
An object of this invention is directed to further reduction in number of component parts and in manufacturing cost of a flexible engagement gear device which is provided with a silk-hat shaped flexible external gear.
In order to achieve the above object, the following constitution is employed for a flexible engagement gear device which comprises a circular rigid internal gear, a silk-hat shaped flexible external gear, and a wave generator, wherein the flexible external gear has an annular body, external teeth formed on a outer circumferential surface of an open end of the body, a cylindrical diaphragm extending radially and outwardly from an open end at an opposite side of the body, and a thick boss connected integrally to an outer circumferential end of the diaphragm, wherein the body of the flexible external gear is disposed inside the rigid internal gear so that the external teeth face internal teeth of the rigid internal gear, and wherein the wave generator is fixed inside the body where the external teeth are formed and flexes the annular body in a radial direction, to thereby engage the external teeth partially with the internal teeth and to shift engagement portions in a circumferential direction.
Namely, the flexible engagement gear device has a first end plate and a second end plate disposed at both sides along a device axial direction, between which the rigid internal gear, flexible external gear and wave generator are arranged. Further, an input shaft is arranged to pass through and is fixedly connected to the wave generator. The input shaft is rotatably supported at one end by the first end plate and at the other end by the second end plate. Furthermore, a bearing for supporting the rigid internal gear and the flexible external gear to allow relative rotation thereof is disposed in a manner that it encloses the body of the flexible external gear at a position adjacent to the rigid internal gear. In addition, with the rigid internal gear being held between an inner race of the bearing and the first end plate, these three members are put together along the device axial direction, and the first end plate and the rigid internal gear are coupled together with the side of the inner race by means of a plurality of first fixing bolts attached from the side of the first end plate. Likewise, an outer race of the bearing, the circular boss and the second end plate are put together along the device axial direction so that the circular boss is held between the outer race of the bearing and the second end plate, and the second end plate and the circular boss are coupled together with the side of the outer race by means of a plurality of second fixing bolts attached from the side of the second end plate.
It is preferable to use a cross roller bearing as the above-mentioned bearing which is capable of supporting thrust load.
The input shaft may be a hollow input shaft arranged to have the both ends thereof pass through the first and second end plates. With is, a hollow portion of the hollow input shaft can be used for wiring and the like, and a rotational drive source such as a motor can be arranged at either sides of the first and second end plates, increasing flexibility of device layout.
Moreover, the rigid internal gear and the inner race may be made as a single component part, which is preferable that the number of component parts can be reduced and that misalignment of these parts can be prevented. Similar effects can also be obtained where the first end plate and the inner race are made as a single component part. In particular, such effects can be enhanced where the rigid internal gear, the inner race and the first end plate are made as a single component part.
According to the silk hat flexible engagement gear device as constituted above, both ends thereof is defined by the first and second and plates, the flexible external gear, rigid internal gear and wave generator are disposed between the first and second end plates, a bearing is disposed on an outer circumference of the flexible external gear, the inner and outer races of the bearing are fixed on the first and second end plates, respectively, and the input shaft for rotating the wave generator is rotatably supported at its both ends by the first and second end plates. Therefore, the bearing and the rigid internal gear are arranged adjacent to each other between the first and second end plates, which serve as a device housing. Hence, an additional member is not required to arrange as a device housing.
Further, in order to shorten the axial length of the silk hat engagement flexible gear device of this invention, the axial length of the annular body of the flexible external gear having a silk-hat shape must be shortened. With using the flat-type, silk-hat shaped flexible external gear aforementioned and proposed by the applicant of this application, flattening of the device can easily be obtained.
Furthermore, in the silk hat flexible engagement gear device according to this invention, the first end plate, the flexible external gear and the outer race of the bearing can easily be coupled with one another simply by placing the thick cylindrical boss formed on the outer circumferential edge of the diaphragm of the flexible external gear between the first end plate and the outer face of the bearing. Similarly, the rigid internal gear, the inner race of the bearing and the first end plate can easily be coupled with one another simply by placing the rigid internal gear between the inner race of the bearing and the first end plate.
Furthermore, the projecting direction of the input shaft, in other words, the mounting side of the motor can be changed only by replacing the first and second end plates at both ends without changing shapes or the like of the rigid internal gear, flexible external gear or wave generator, these parts being main constituent parts of the wave gear device.
Especially, in the silk hat flexible engagement gear device of this invention, the first end plate and the rigid internal gear are coupled with each other with the first fixing bolts. Conventionally, these three members are temporarily fastened by temporarily-fastening bolts and then are fastened by fastening bolts. In this invention, the first fixing bolts corresponding to the temporarily fastening bolts are used to couple these members with one another. Thus, only either one of the temporarily-fastening bolts or the fastening bolts are required. As a result, only one group of bolt-holes are required to form instead of two groups of bolt-holes for the temporarily-fastening bolts and the fastening bolts. According to the silk hat flexible engagement gear device of this invention, the number of component parts of the device can be reduced, and assembly of the parts thereof can be made easily, whereby reducing the manufacturing cost.
The above-mentioned functions and effects are also applied where three members (the second end plate, the circular boss of the flexible external gear and the outer race of the bearing) are coupled with one another by means of the second fixing bolts.
REFERENCES:
patent: 4598947 (1986-07-01), Foiurrey et al.
patent: 4825720 (1989-05-01), Capdepuy
patent: 5715732 (1998-02-01), Takizawa et al.
patent: 5775178 (1998-07-01), Asawa et al.
patent: 5850765 (1998-12-01), Shirasawa
patent: 590614
Burns Doane Swecker & Mathis L.L.P.
Harmonic Drive Systems Inc.
Marmor Charles A
Parekh Ankur
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