Closed-loop control of an infinitely variable transmission

Patent metadata

Field	Value
Publication number	US-11268615-B2
Application number	US-202117232225-A
Country	US
Kind code	B2
Filing date	Apr 16, 2021
Priority date	Apr 16, 2020
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

A nonlinear closed-loop control combined with an integral time-delay feedback control is disclosed to adjust a speed ratio of an infinitely variable transmission (IVT) system. A speed ratio control for an IVT system involves a forward speed controller and a crank length controller for different speed ranges. The time-delay control is designed to reduce speed fluctuations of the output speed of an IVT with an accurate speed ratio. The speed ratio of an IVT with the disclosed control strategy can achieve an excellent tracking response for the desired constant output speed and reduce speed fluctuations of the output speed of an IVT by the time-delay feedback control.

First claim

What is claimed is:

1. An infinitely variable transmission control system comprising:
a crank length controller comprising electronic components configured to:
determine a desired output rotation speed of an infinitely variable transmission (IVT); and
determine a control signal for a crank length control mechanism based on the determined output rotation speed; and

a crank length control mechanism configured to receive the control signal and control the crank length of the infinitely variable transmission based on the control signal,

wherein the crank length controller is configured to:
determine an estimated output rotation speed of the infinitely variable transmission; and
determine the control signal for the crank length control mechanism based on the estimated output rotation speed.

2. The infinitely variable transmission control system of claim 1 , wherein the desired output rotation speed is determined based on a desired output speed and a desired input speed of the infinitely variable transmission.

3. The infinitely variable transmission control system of claim 1 , wherein the desired output rotation speed is determined based on the equation:

ℓ

c
⁢

⁢
r

*

=

2

⁢
p
⁢

⁢

r
og

⁢

w
u
*

4
⁢

i
n

⁢

w
n
*

wherein r og is a pitch radius of an output gear of the infinitely variable transmission, w u * is a desired output speed of the infinitely variable transmission, i n is the speed ratio of the gear pair, and w n * is a desired input speed of the infinitely variable transmission.

4. The infinitely variable transmission control system of claim 1 , wherein the crank length controller is configured to determine the control signal based on the equation:
cr =l Δw u

wherein cr is the crank length, l is an integral gain, and Δw u is a tracking error of the crank length controller.

5. The infinitely variable transmission control system of claim 1 , wherein the crank length controller is configured to change the control signal for adjusting the crank length based on an estimate of the output rotation speed of the infinitely variable transmission.

6. The infinitely variable transmission control system of claim 1 , wherein the crank length controller is configured to use a look-up table to determine the crank length and to determine the control signal.

7. The infinitely variable transmission control system of claim 1 , wherein the infinitely variable transmission comprises a pair of meshed gears, an input-control module, and a motion conversion module.

8. The infinitely variable transmission control system of claim 7 , wherein the input-control module comprises a first and a second planetary gear set positioned on a secondary shaft, an active control gear positioned on a control shaft, and an idler control gear positioned on an idler shaft, wherein speeds of the control shaft and the idler shaft are controlled by an actuator,
wherein the motion conversion module comprises a first and a second scotch yoke system positioned on an input shaft, a transmitting shaft, and an output shaft,
wherein a driving gear is positioned on the input shaft and wherein a driven gear is positioned on the secondary shaft,
wherein a combination of an input speed from the secondary shaft and speeds of the control shaft and idler shaft constitute an output from the input-control module to the motion conversion module through the first and second planetary gear sets, respectively, wherein output speeds of the first and second planetary gear sets are input speeds of the first scotch yoke system and an output speed of the second planetary gear set is directly transmitted as an input speed to the second scotch yoke system via the transmitting shaft,
wherein a combination of input speeds of the first and second scotch yoke systems are converted to translational speeds which are subsequently converted to rotational speeds of four output gears positioned on the output shaft through four rack-pinion meshings, and
wherein the rotational speeds of the four output gears are rectified by one-way bearings and transmitted to the output shaft as an IVT output speed.

9. The infinitely variable transmission control system of claim 8 , wherein the gears are noncircular gears.

10. The infinitely variable transmission control system of claim 8 , wherein the input shaft is connected to a prime mover.

11. An infinitely variable transmission control system comprising:
an input-control module configured to control a motion conversion module of an infinitely variable transmission (IVT); and
a forward speed controller comprising electronic components configured to:
determine a crank length for the infinitely variable transmission, a desired modulated input speed of the input-control module, and an output torque of an output shaft of the infinitely variable transmission; and
output a control signal to the input-control module based on the determined crank length, the desired modulated input speed, and the output torque.

12. The infinitely variable transmission control system of claim 11 , wherein the input-control module includes an electronic motor configured to receive the control signal and to control modulation of an input rotation speed of the input-control module based on the control signal.

13. The infinitely variable transmission control system of claim 11 , further comprising at least one of: (I) a crank length controller comprising electronic components configured to:
determine a desired output rotation speed of the infinitely variable transmission; and
determine the crank length based on the desired output rotation speed;

(II) a torque sensor operatively connected to the output shaft of the infinitely variable transmission, configured to measure the output torque of the output shaft, and configured to output a signal representative of the measured output torque to the electronic components of the forward speed controller; or
(III) both (I) and (II).

14. The infinitely variable transmission control system of claim 11 , wherein the forward speed controller comprises a time-delay feedback controller configured to:
determine an input speed of the infinitely variable transmission; and
adjust the control signal to the input-control module based on a tracking error of the output speed of the infinitely variable transmission.

15. The infinitely variable transmission control system of claim 11 , wherein the infinitely variable transmission comprises a pair of meshed gears, an input-control module, and a motio

Assignees

• Univ Maryland

Inventors

• Zhu Weidong
• Wang Xuefeng
• Li Gang

Classifications

• F16H3/76

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

• F16H59/44

  dependent on machine speed {, e.g. the vehicle speed} (F16H59/46 takes precedence) · CPC title

• F16H59/40

  Output shaft speed · CPC title

• F16H59/42

  Input shaft speed · CPC title

• F16H2061/009

  using formulas or mathematic relations for calculating parameters · CPC title