Wave gear device provided with tapered flexible externally toothed gear
AssigneeHarmonic Drive Systems Inc.
InventorShoichi Ishikawa
Life of this patent
Estimating the term…
Abstract
In an elliptical rim neutral line of each axially perpendicular cross section in a tooth trace direction of a flexible externally toothed gear of a wave gear device, external teeth are applied with addendum modification along the external teeth tooth trace direction so that the bending stress generated at the root rim surface of the external teeth that is caused by flexing of the flexible externally toothed gear is averaged out, the maximum value thereof can be reduced, and the transferred torque of the wave gear device can be increased.
Claims3
A wave gear device provided with a tapered flexible externally toothed gear, comprising:
- an annular rigid internally toothed gear;
- a flexible externally toothed gear coaxially arranged inside of the internally toothed gear;
- and
- a wave generator fitted inside of the externally toothed gear, wherein
- the flexible externally toothed gear is provided with a flexible cylindrical part, a disk-shaped diaphragm extending from a rear end of the cylindrical part in a radial direction, and external teeth formed on an external peripheral surface of a front end opening side of the cylindrical part;
- a portion of the front end opening side of the cylindrical part is made to elliptically flex by the wave generator, and the external teeth at the two end parts in a major axis direction of an elliptical curve mesh with internal teeth of the rigid internally toothed gear;
- and
- a flexing amount on the major axis of an elliptical curved line in the external teeth of the flexible externally toothed gear that is elliptically flexed gradually increases from a rear end of the diaphragm side to a front end of the front end opening side along a tooth trace direction of the external teeth, and wherein
- the flexible externally toothed gear and the rigid internally toothed gear are both spur gears of a module m;
- a number of teeth of the flexible externally toothed gear is set to have 2n less teeth than a number of teeth of the rigid internally toothed gear, where n is a positive integer;
- in an axially perpendicular cross section of any position in a tooth trace direction of the external teeth, when a circle that passes through the center of the thickness direction of a root rim of the external teeth prior to being elliptically flexed is referred to as a rim neutral circle and a curved line that passes through the center of the thickness direction of the root rim after being elliptically flexed is referred to as an elliptical rim neutral line, the flexing amount w in a major axis direction of the elliptical rim neutral line relative to the rim neutral circle is w=2 κmn, where κ is a flexing coefficient;
- and
- a product of a root rim thickness t and the flexing amount w is constant for each axially perpendicular cross section in the tooth trace direction of the external teeth.
Dependencies are inferred from the claim text.