Variable-ratio line gear mechanism

Patent metadata

Field	Value
Publication number	US-10465787-B2
Application number	US-201515527015-A
Country	US
Kind code	B2
Filing date	Dec 31, 2015
Priority date	Aug 13, 2015
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

The present invention is a variable-ratio line gear mechanism. The mechanism forms a transmission pair consisting of a driving line gear and a driven line gear, of which axes intersect at an arbitrary angle. Transmission is generated by point contact meshing movement of line teeth between the driving line gear and the driven line gear. A contact curve of the line tooth is designed in accordance with space conjugate curve meshing theory, and the designing equation is divided into an equal transmission ratio part and a variable transmission ratio part. The equal transmission ratio part provides a uniform transmission, and the variable transmission ratio part makes the transmission ratio smoothly transit. The line gear mechanism is able to provide periodically transmission with variable transmission ratio, to provide a plurality of transmission ratios during a movement period of the driven line gear, and to enable smooth transitions between respective transmission ratios in accordance with movement rules.

First claim

The invention claimed is:

1. A variable-ratio line gear mechanism adapted to form a transmission pair consisting of a driving line gear and a driven line gear, of which axes intersect at an arbitrary angle, the driving line gear consisting of a wheel body and line teeth, the driven line gear consisting of a wheel body and line teeth, contact curves of the line tooth of the driving line gear and the line tooth of the driven line gear meshing in accordance with a pair of space conjugate curves, the driving line gear being connected with an actuator to provide an input, there being one or more line teeth on the driving line gear, the line tooth of the driving line gear being meshed with the line tooth of the driven line gear by point contact, the driven line gear being connected with an output end to provide a movement or an output of force, the line tooth on the driven line gear being the one with property of variable transmission ratio, so that in one movement period, a plurality of transmission ratios exist, and a smooth transition among different transmission ratios can be made, resulting in a transmission with periodically variable transmission ratio,
and wherein the contact curve on the line tooth of the driving line gear for meshing is a circular helix, the line tooth of the driven line gear is divided into an equal transmission ratio part and a variable transmission ratio part, and there are two equations for the contact curve on the line tooth for meshing: one is an equal transmission ratio equation for realizing equal transmission ratio, and the other one is a variable transmission ratio equation for realizing variable transmission ratio
and wherein, during the transmission of said mechanism, the variable transmission ratio equation can make the transmission ratio of the line gear smoothly change from one value to another, i.e. a derivative value of transmission ratio function increases or decreases from 0 to a certain value, and then smoothly back to 0,
and further wherein said variable transmission ratio equation is determined as follows: O−xyz is a Cartesian coordinate system that is arbitrarily fixed in space, O is an origin of the coordinate system O−xyz, x, y, z are three coordinate axes of the coordinate system O−xyz, a Cartesian coordinate system O p −x p y p z p is determined in accordance with a position of the coordinate system O−xyz, a plane x p O p z p is in a same plane as a plane xOz, a distance from a coordinate origin O p to the axis z is a, a distance from O p to the axis x is b, an angle between the axis z and an axis z p is (π−θ), θ is an angle between angular velocity vectors of the driving and driven line gears, with 0°≤θ≤180°, and coordinate systems O 1 −x 1 y 1 z 1 and O 2 −x 2 y 2 z 2 are respectively the coordinate systems fixed on the driving line gear and the driven line gear; during transmission, the driving line gear and driven line gear rotate around the axis z and the axis z p respectively, and an initial meshing place of the driving line gear and the driven line gear is an initial position; at the initial position, coordinate systems O 1 −x 1 y 1 z 1 and O 2 −x 2 y 2 z 2 coincide with the coordinate systems O−xyz and O p −x p y p z p , respectively; at any time, the origin O 1 coincides with O, an axis z 1 coincides with the axis z, the origin O 2 coincides with O p , an axis z 2 coincides with the axis z p , the driving line gear rotates around the axis z at a uniform angular velocity ω 1 , angular velocity direction of the driving line gear is a negative direction of the axis z, and an angle that the driving line gear rotates through around the axis z is φ 1 ; the driven line gear rotates around the axis z p at a uniform angular velocity ω 2 , angular velocity direction of the driven line gear is a negative direction of the axis z p , an angle that the driven line gear rotates through around the axis z p is φ 2 ,then an equation of the driving contact curve is as follows in the coordinate system O 1 −x 1 y 1 z 1 :

{

x
M

(
1
)

=

m
⁢

⁢
cos
⁢

⁢
t

y
M

(
1
)

=

m
⁢

⁢
sin
⁢

⁢
t

z
M

(
1
)

=

n
⁢

⁢
π

+
nt

⁢

⁢

(

-
π

≤
t
≤

-

π
2

)

,

and then an equation for variable transmission ratio contact curve is:

{

x
M

Assignees

• Univ South China Tech

Inventors

• Chen Yangzhi
• Huang Huai
• Lv Yueling

Classifications

• F16H2057/0087

  Computer aided design [CAD] specially adapted for gearing features; Analysis of gear systems · CPC title

• F16H35/02 Primary

  for conveying rotary motion with cyclically varying velocity ratio · CPC title

• F16H55/10

  Constructively simple tooth shapes, e.g. shaped as pins, as balls · CPC title

• F16H55/08 Primary

  Profiling · CPC title

• F16H3/42

  with gears having teeth formed or arranged for obtaining multiple gear ratios, e.g. nearly infinitely variable · CPC title