Continuously variable transmission

Patent metadata

Field	Value
Publication number	US-2019113121-A1
Application number	US-201716092160-A
Country	US
Kind code	A1
Filing date	Apr 12, 2017
Priority date	Apr 12, 2016
Publication date	Apr 18, 2019
Grant date	—

Abstract

The invention relates to a continuously variable transmission (CVT) comprising a ratio varying unit and a compound epicyclic gear set. The ratio varying unit has a rotating first side and a rotating second side, the rotational axes of the first and second sides being coaxial. The compound epicyclic gear set comprises a first set of planets, being rotationally mounted within a carrier and meshing with a sun gear. The epicyclic gear set also has a first annulus gear and a second set of planets; the second set of planets also being rotationally mounted within the carrier and meshing with a second annulus gear. One of the first or second rotating sides of the ratio varying unit is coupled to the carrier and the other of the first or second rotating sides of the ratio varying unit is coupled to the sun gear.

First claim

1 . A continuously variable transmission (CVT) comprising a ratio varying unit and a compound epicyclic gear set;
the ratio varying unit having a rotating first side and a rotating second side, the rotational axes of the first and second sides being coaxial; the compound epicyclic gear set comprising a first set of planets; the first set of planets being rotationally mounted within a carrier and meshing with a sun gear, a first annulus gear and a second set of planets; the second set of planets also being rotationally mounted within the carrier and meshing with a second annulus gear; one of the first or second rotating sides of the ratio varying unit being driveably coupled to the carrier and the other of the first or second rotating sides of the ratio varying unit being driveably coupled to the sun gear.

2 . A CVT according to claim 1 wherein the ratio varying unit provides a negative speed ratio between the first and second rotating sides.

3 . A CVT according to claim 2 , wherein the ratio varying unit comprises a toroidal variator.

4 . A CVT according to claim 3 , wherein the ratio varying unit comprises a toroidal variator.

5 . A CVT according to claim 1 , wherein both of the respective rotating sides of the ratio varying unit are directly connected to the compound epicyclic gear set.

6 . A CVT according to claim 1 , wherein a rotational axis of the compound epicyclic gear set is coaxial with the rotational axes of the first and second sides of the ratio varying unit.

7 . A transmission comprising:
a transmission input shaft; a transmission output shaft; a ratio varying unit having a rotating first side and a rotating second side; an epicyclic gear arrangement comprising a first member which can be driven by a first side of the ratio varying unit, a second member which can be driven by the second side of the ratio varying unit, a third member, and a fourth member which can be driven by the transmission input shaft; a first clutch arrangement configured to driveably couple the first member to the output shaft; a second clutch arrangement configured to driveably couple to second member to the output shaft; a third clutch arrangement configured to driveably couple the third member to the output shaft.

8 . A transmission according to claim 7 comprising a fourth clutch arrangement configured to driveably couple two of the first, second and third clutch arrangements to the output shaft.

9 . A transmission according to claim 8 wherein the said two clutch arrangements are selector devices.

10 . A transmission according to claim 8 wherein the fourth clutch arrangement is a “normally closed” friction clutch.

11 . A transmission according to claim 7 , wherein a fifth clutch arrangement is provided for selectively grounding the third member.

12 . A transmission according claim 7 , wherein the first member is a sun gear, the second member is a carrier assembly, the third member is a first annulus gear and the fourth member is a second annulus gear.

13 . A transmission according to claim 12 wherein, in the frame of reference of the carrier assembly, the second annulus gear rotates in the opposite direction to the sun gear and the first annulus gear.

14 . A transmission comprising:
a transmission input shaft; a transmission output shaft; a ratio varying unit having a rotating first side and a rotating second side, the rotational axes of the first and second sides being coaxial; an epicyclic gear set comprising a first input arranged to he driven by the transmission input shaft, a second input arranged to be driven by a first side of the ratio varying unit, and a third input arranged to be driven by the second side of the ratio varying unit; a first drive mode in which the speed of the transmission output is proportional to the speed of the first side of the ratio varying unit, and a second drive mode in which the speed of the transmission output is proportional to the speed of the second side of the ratio varying unit, wherein, at one particular speed operating ratio of the ratio varying unit, the ratio of the speed of the transmission output shaft to the speed of the transmission input shaft is the same in both the first and second drive modes.

15 . (canceled)

16 . A transmission according to claim 14 , in which the transmission output shaft is arranged to rotate in the same direction as the transmission input shaft in the first and second modes.

17 . A transmission according to claim 16 , in which the transmission is arranged such that the first and second modes provide forwards vehicle operation only.

18 . A transmission according to claim 14 , in which the transmission is adapted to define a synchronous shift point at a junction between first and second modes.

19 . A transmission according to claim 14 , in which the ratio varying unit has a ratio spread greater than 4.

20 . A transmission according to claim 19 , in which the ratio varying unit has a ratio spread greater than 6.

21 - 45 . (canceled)

Assignees

• Allison Transm Inc

Inventors

• Gaskell Christopher

Classifications

• F16H15/38

  with two members B having hollow toroid surfaces opposite to each other, the member or members A being adjustably mounted between the surfaces · CPC title

• F16H2037/0873

  with switching means, e.g. to change ranges · CPC title

• F16H2015/383

  with two or more sets of toroid gearings arranged in parallel · CPC title

• F16H37/086 Primary

  CVT using two coaxial friction members cooperating with at least one intermediate friction member · CPC title

• F16H2037/103

  Power-split transmissions with each end of a CVT connected or connectable to a planetary gear set having four or more connections, e.g. a Ravigneaux set · CPC title