Gear pair and nutation reducer

Patent metadata

Field	Value
Publication number	US-11835113-B2
Application number	US-202318219704-A
Country	US
Kind code	B2
Filing date	Jul 9, 2023
Priority date	Dec 22, 2021
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

A gear pair and nutation reducer are provided. The gear pair is formed by a pin gear and a non-instantaneous-pole enveloping gear in meshing engagement with each other, the effective tooth surface of the pin gear being constructed of an elliptical cone segment that is outwardly convex, and the distance between the highest and lowest points on the elliptical cone segment in the same cross-section gradually decreases inwardly along the generatrix of the reference cone of the pin gear.

First claim

The invention claimed is:

1. A gear pair comprising a pin gear and a non-instantaneous-pole enveloping gear which are in meshing engagement with each other, wherein tooth surface of the pin gear comprises effective tooth surface and ineffective tooth surface, the effective tooth surface of said pin gear is formed by an elliptical cone segment which is outwardly convex, in which surface segment the distance between the highest and lowest points in the same cross-section gradually decreases inwardly along the generatrix of the reference cone of said pin gear; wherein said effective tooth surface of said non-instantaneous-pole enveloping gear being the non-instantaneous-pole envelope of said pin gear in the non-instantaneous-pole enveloping process which is created on the non-instantaneous-pole enveloping gear during the nutational movement between the gear pair, wherein the number of teeth in said pin gear is one more than that in said non-instantaneous-pole enveloping gear.

2. A gear pair as claimed in claim 1 , wherein the ineffective tooth surface of said pin gear comprises a curved tooth-tip segment, a flat plane segment, and a curved tooth-root segment, said curved tooth-tip segment, said elliptical cone segment, said flat plane segment and said curved tooth-root segment are configured as the tooth surface of the pin gear, wherein said elliptical cone segment, said plane segment and said tooth-root segment are consecutively arranged one beside another at both ends of said tooth-tip segment, wherein every adjacent two of said tooth-tip segment, said elliptic conical surface segment, said plane segment and said tooth-root segment are tangent to each other, wherein said tooth-tip segment is smoothly convexly curved, and said tooth-root surface is smoothly concavely curved; and wherein said non-instantaneous-pole enveloping gear has a tooth surface comprising a curved tooth-tip surface, a non-instantaneous-pole enveloping tooth surface, a flat plane segment and a curved tooth-root segment, wherein said non-instantaneous-pole enveloping tooth surface, said plane segment and said tooth-root segment are consecutively arranged one beside another at both ends of said tooth-tip segment, every adjacent two of said tooth-tip segment, said non-instantaneous-pole enveloping tooth surface, said plane segment and said tooth-root segment are tangent to each other, said tooth-tip segment is smoothly convexly curved, and said tooth-root segment is smoothly concavely curved.

3. A gear pair as claimed in claim 2 , wherein said tooth-tip segment and said tooth-root segment each are formed by spline surface.

4. A gear pair as claimed in claim 1 , wherein the shaft angle T between the axis of said pin gear and that of said non-instantaneous-pole enveloped gear lies within a range of 177°≤T≤180°.

5. A gear pair as claimed in claim 1 , wherein the ratio of major axis to minor axis of elliptical cone lies within a range of 1.3 to 2.5.

6. A gear pair as claimed in claim 1 , wherein said pin gear has a tooth depth which gradually decreases radially inwardly.

7. A gear pair as claimed in claim 1 , wherein said effective tooth surface of said pin gear has a pressure angle α that satisfies requirement of 40°-R≤α≤50°-R; wherein R is the friction angle between the tooth surface of said pin gear and that of said non-instantaneous-pole enveloping gear.

8. A gear pair as claimed in claim 1 , wherein of said pin gear has a first reference cone between its face cone and root cone, wherein axis of said first reference cone is coincident with that of said pin gear, and wherein said first reference cone has a cone angle β; said non-instantaneous-pole enveloping gear has a second reference cone between its face cone and root cone, wherein axis of said second reference cone is coincident with that of said non-instantaneous-pole enveloping gear, and wherein said second reference cone has a cone angle W; said gear pair has a shaft angle T between axis of said pin gear and that of said non-instantaneous-pole enveloped gear, said pin gear has a face angle γ and a root angle P; said non-instantaneous-pole enveloping gear has a face angle K and a root angle L, the relationship between β, W, T, γ, K, L is described as follows:
89°≤β≤91°, W=T−β, β+ 0.3°≤γ≤β+2.1°, β−2.9°≤ P≤β− 0.5°, W+ 0.3°≤ K≤W+ 2.3°, W− 3.1°≤ L≤W− 0.6°.

9. A nutation reducer comprising:
a case;
an output shaft rotationally provided in said case;
a gear pair as claimed in claim 1 , wherein said non-instantaneous-pole enveloping gear is provided in said case in a fixed manner, or integrally formed with said case;
an annular spring film, having an inner ring provided with a first connecting part fixed to said output shaft, an outer ring provided with a second connecting part fixed to said pin gear, and an annular elastically deformable portion connected between said inner and outer rings, wherein said inner ring is coaxial with said output shaft of said reducer, while said outer ring is coaxial with said pin gear;
an actuator mechanism for nutational movement, provided in said case, to actuate said pin gear to perform nutational movement such that teeth of said pin gear roll on teeth of said non-instantaneous-pole enveloping gear and said annular elastically deformable portion deforms to adapt said nutational movement of said pin gear.

10. A nutation reducer as claimed in claim 9 , wherein said nutation reducer further comprises an input shaft of said reducer, which is rotationally provided in said case;
wherein said actuator mechanism for nutational movement comprises
a rotatable tilted disc provided on said input shaft of said reducer, wherein one side of said tilted disc forms a tilted plane, while the other side is perpendicular to axis of said tilted disc;
a driving mechanism driving said tilted disc to rotate;
planar high-density ball bearings provided at both sides of said tilted disc;
an annular raised platform radially inwardly protruded from the inner surface of said case around said input shaft, wherein the side of said platform contacts said planar high-density ball bearing, the side of said platform is perpendicular to axis of said input shaft; wherein the end face of said platform, back side of said pin gear, and both sides of said tilted disc serve as raceways for said planar high-density ball bearings.

11. A nutation reducer as claimed in claim 10 , wherein said driving mechanism is an electric motor, the output shaft of which is fixed to said tilted disc and thus used as said input shaft of said reducer for driving said tilted disc to rotate.

12. A nutation reducer as claimed in claim 11 , wherein said case of said reducer serves as a housing for said electric motor, in which stator of said electric motor is embedded and within which rotor of said electric motor is rotationally provided.

13. A nutation reducer as claimed in claim 10 , wherein two gear pairs are provided such that they are arranged at two opposite sides of said actuator mechanism for nutational movement in a symmetric manner.

14. A nutation reducer as claimed in claim 13 , wherein said actuator mechanism for nutational movement comprises:
a tilted disc rotationally provided in said case on said output shaft of said reducer and driven by an actuating mechanism, wherein two opposite sides of said tilted disc form a pair of symmetric tilted planes;
planar high-density ball bearings provided at both sides of said tilted disc in a symmetric manner such that both sides of said tilted disc and back sides of said pin gears in each said two gear pairs serve as raceways for said planar high-density ball bearings;
wherein said pin gears in sa

Assignees

• Jiang Hong

Inventors

• Wang Xiaochun

Classifications

• F16H1/321 Primary

  the orbital gear being nutating · CPC title

• F16H55/08

  Profiling · CPC title

• F16H57/02

  Gearboxes; Mounting gearing therein · CPC title

• F16H2057/02034

  Gearboxes combined or connected with electric machines · CPC title

• F16H1/28 Primary

  with gears having orbital motion · CPC title