Machine element or mechanism – Gearing
Reexamination Certificate
1999-08-06
2001-05-15
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Gearing
Reexamination Certificate
active
06230587
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a corrugated gear, and particularly a corrugated gear wherein the tooth profile of the flexible gear and the tooth profile of the rigid gear are chosen in such a way that every tooth of the flexible gear can make a loop-shaped movement within a tooth gap of the tooth profile of the rigid internally geared gear, wherein that the movement contour of a tooth of the flexible gear while making its loop-shaped movement determines at least approximately the contour of a tooth gap of the tooth profile of the rigid gear.
2. Description of the Related Art
All corrugated gears include a deformable internal gear. This could be made of metal or could also be made of plastic. A guide curve is used to describe the shape of the deformed internal gear (for example, an ellipse in harmonic drives) (see FIG.
1
). If the deformations under load are not considered, or in the case of a too general model, engagement discontinuities or disruptions occur, which have a negative impact on effectiveness and life expectancy (see FIG.
2
).
The deformations can occur in a radial direction, for example among the individual rollers or studs or planet arms, or the deformations can occur in the direction tangential to the internal gear, when the internal gear is stretched or stressed in the longitudinal direction during the transmission of torque. When these deformations are not taken into consideration this leads to disruptions in gear tooth engagement, to an increase in tooth flank wear, and, as a result of the deformation of the tooth head in the radial direction, to damage of the gear tooth head and a reduction in gear tooth efficiency. The tooth efficiency has a very large influence on the efficiency particularly in high reduction planetary gears and also in corrugated gears.
SUMMARY OF THE INVENTION
The invention comprises a corrugated gear including the features of:
a) a rigid internally geared gear;
b) a flexible externally geared gear within the internally geared gear;
c) a wave generator to bring the gear with external teeth into a cross-sectional shape in such a way, that the gear with external teeth is only meshing partially with the rigid internally geared gear and the engagement segment of the two gears rotates in the direction of the circumference;
d) by the rotation of the wave generator a relative movement of the two gears can be produced;
e) the flexible gear and the rigid gear are both rim gears;
f) in order to avoid engagement obstructions the tooth profile of the rigid gear and the tooth profile of the flexible gear are coordinated or matched.
According to the invention the gear is characterized thereby, that
g) the tooth profile of the flexible gear and the tooth profile of the rigid gear are chosen in such a way that every tooth of the flexible gear can make a loop-shaped movement within a tooth gap of the tooth profile of the rigid internally geared gear, and
h) the movement contour of a tooth of the flexible gear while making its loop-shaped movement determines at least approximately the contour of a tooth gap of the tooth profile of the rigid gear.
REFERENCES:
patent: 4663813 (1987-05-01), Carlson
patent: 4667539 (1987-05-01), Fickelscher
patent: 4770059 (1988-09-01), Beyer
patent: 4850237 (1989-07-01), Hatayama et al.
patent: 4874067 (1989-10-01), Greenwell
patent: 4969376 (1990-11-01), Fickelscher
patent: 463227 (1968-11-01), None
patent: 3784839 (1988-11-01), None
patent: 3876566 (1989-03-01), None
patent: 69212703 (1992-11-01), None
patent: 69406515 (1995-01-01), None
Motyka, St.; “Verkürzte Bauform des Harmonic Drive”, of: DE-Z, Konstruktion 45 (1993), S. 221-226.
Estremsky Sherry
IMS Morat Soehne GmbH
Pendorf & Cutliff
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