Balanced eccentric gear design and method

Patent metadata

Field	Value
Publication number	US-9768664-B2
Application number	US-201514719257-A
Country	US
Kind code	B2
Filing date	May 21, 2015
Priority date	May 21, 2015
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A wobble plate drive system may include a stator having a central axis, an upper surface perpendicular to the central axis, and a plurality of stator teeth disposed on the upper surface. The system may further include a wobble plate having a wobble axis disposed at a non-zero angle relative to the central axis, a lower wobble surface perpendicular to the wobble axis, and an upper wobble surface perpendicular to the wobble axis. A plurality of lower wobble teeth may be disposed on the lower wobble surface and a plurality of upper wobble teeth may be disposed on the upper wobble surface. The system may include an output gear having an output axis substantially aligned with the central axis and a lower surface perpendicular to the output axis. A plurality of output teeth may be disposed on the lower surface. The wobble plate may be configured to rotate as it nutates around the stator.

First claim

We claim:

1. A wobble plate drive system, comprising:
a stator having a central axis, an upper surface perpendicular to the central axis, and a plurality of stator teeth disposed on the upper surface;
a wobble plate having a wobble axis disposed at a non-zero angle relative to the central axis, a lower wobble surface perpendicular to the wobble axis, an upper wobble surface perpendicular to the wobble axis, a plurality of lower wobble teeth disposed on the lower wobble surface, and a plurality of upper wobble teeth disposed on the upper wobble surface; and
an output gear having an output axis substantially aligned with the central axis, a lower surface perpendicular to the output axis, and a plurality of output teeth disposed on the lower surface;
wherein the wobble plate is configured to rotate as it nutates around the stator.

2. The wobble plate drive system of claim 1 , wherein the wobble plate has a down position where the wobble plate is closest to the stator, further wherein the plurality of lower wobble teeth and the plurality of stator teeth are configured such that the plurality of lower wobble teeth first engage the stator teeth at a position 90 degrees away in a direction of nutation from the down position.

3. The wobble plate drive system of claim 1 , wherein each tooth of the plurality of stator teeth, the plurality of lower wobble teeth, the plurality of upper wobble teeth, and the plurality of output teeth have a face defined by a compound involute of a circle and an ellipse.

4. The wobble plate drive system of claim 1 , wherein the stator includes an inner diameter, an outer diameter, and a pitch circle, the plurality of stator teeth disposed between the inner and outer diameters, and the pitch circle disposed between the inner and outer diameters, further wherein the plurality of stator teeth and the plurality of lower wobble teeth are configured such that a set of contact forces exerted by the pluralities of stator teeth and lower wobble teeth on each other are substantially tangent to the pitch circle.

5. The wobble plate drive system of claim 4 , wherein each tooth of the plurality of stator teeth has a tooth height and the tooth height has a maximum value between the inner diameter and the outer diameter and a minimum value at one of the inner diameter or the outer diameter.

6. The wobble plate drive system of claim 1 , wherein each tooth of the plurality of stator teeth has a rectangular footprint on the upper surface, each tooth of the plurality of lower wobble teeth has a rectangular footprint on the lower wobble surface, each tooth of the plurality of upper wobble teeth has a rectangular footprint on the upper wobble surface, and each tooth of the plurality of output teeth has a rectangular footprint on the lower surface.

7. The wobble plate drive system of claim 1 , wherein
a pair of adjacent stator teeth define a tooth pitch as an angular separation between corresponding locations on each tooth of the pair of adjacent stator teeth;
each tooth of the pair of adjacent stator teeth defines a tooth footprint on the upper surface; and
each tooth footprint of the pair of adjacent stator teeth has an angular width that is less than one half of the tooth pitch.

8. A method for operating a wobble plate drive mechanism, comprising:
nutating a rotor about a fulcrum, the rotor including a plurality of lower rotor teeth and a plurality of upper rotor teeth,
impelling a first side of the rotor to press against a stationary stator at a first location, the stator including a plurality of stator teeth,
impelling a second side of the rotor to press against an output plate at a second location, the second location being on an opposite side of the rotor as the first location, the output plate including a plurality of output teeth, and
engaging the lower rotor teeth with the stator teeth and the upper rotor teeth with the output teeth as the rotor nutates about the fulcrum.

9. The method of claim 8 , wherein each tooth of the pluralities of stator teeth, lower rotor teeth, upper rotor teeth, and output teeth has a face defined by a compound involute of a circle and an ellipse.

10. The method of claim 8 , wherein each tooth of the plurality of stator teeth has a rectangular footprint on an upper surface of the stator, each tooth of the plurality of lower rotor teeth has a rectangular footprint on a lower surface of the rotor, each tooth of the plurality of upper rotor teeth has a rectangular footprint on an upper surface of the rotor, and each tooth of the plurality of output teeth has a rectangular footprint on a lower surface of the output plate.

11. The method of claim 10 , wherein
a pair of adjacent stator teeth define a tooth pitch as an angular separation between corresponding locations on each tooth of the pair of adjacent stator teeth; and
each tooth footprint of the pair of adjacent stator teeth has an angular width that is less than one half of the tooth pitch.

12. The method of claim 8 , wherein the stator defines a stator plane, the output plate is configured to be parallel to the stator plane, and the rotor is configured to be inclined at an angle with respect to the stator plane and the output plate and disposed between the stator and the output plate.

13. The method of claim 8 , further comprising applying a force to the rotor in a direction towards the stator at a third location that is 90 degrees removed from the first location around the rotor in a direction of nutation.

14. The method of claim 8 , wherein each tooth of the plurality of stator teeth is disposed between an inner diameter and an outer diameter and has a tooth height, the tooth height having a maximum value between the inner diameter and the outer diameter and a minimum value at one of the inner diameter or the outer diameter.

15. A gear for use in a nutating wobble plate drive system, the gear comprising:
a central axis, a surface perpendicular to the central axis, an inner diameter, and an outer diameter;
a set of teeth disposed on the surface between the inner diameter and the outer diameter, and
at least one of the set of teeth having a first driving face extending from the inner diameter to the outer diameter, the first driving face defined by a compound involute of a circle and an ellipse,
the at least one of the set of teeth being disposed on the surface between the inner diameter and the outer diameter.

16. The gear of claim 15 , wherein at least one of the set of teeth has a rectangular footprint on the surface.

17. The gear of claim 15 , wherein:
a pair of adjacent teeth define a tooth pitch as an angular separation between corresponding locations on each tooth of the pair of adjacent teeth;
each tooth of the pair of adjacent teeth defines a tooth footprint on the surface; and
each tooth footprint of each tooth of the pair of adjacent teeth has an angular width that is less than one half of the tooth pitch.

18. The gear of claim 15 , wherein at least one of the teeth has a second driving face defined by a compound involute of a circle and an ellipse, the second driving face disposed opposite to the first driving face.

19. The gear of claim 18 , wherein at least one of the teeth has an upper tooth surface having a tooth height, the upper tooth surface extending from the first driving face to the second driving face; and wherein the tooth height has a maximum value between the inner diameter and the outer diameter and a minimum value at one of the inner diameter or the outer diameter.

20. The gear of claim

Assignees

• Boeing Co

Inventors

• Atmur Robert J
• Sargent William Patrick

Classifications

• F16H55/17

  Toothed wheels (worm wheels F16H55/22; chain wheels F16H55/30) · CPC title

• F16H1/32

  in which the central axis of the gearing lies inside the periphery of an orbital gear · CPC title

• F16H1/321 Primary

  the orbital gear being nutating · CPC title

• F16H2055/173

  Crown gears, i.e. gears have axially arranged teeth · CPC title

• H02K7/1163

  where at least two gears have non-parallel axes without having orbital motion · CPC title