Continuously variable transmission with wedge actuation mechanism

Patent metadata

Field	Value
Publication number	US-10941840-B2
Application number	US-201715829259-A
Country	US
Kind code	B2
Filing date	Dec 1, 2017
Priority date	Jun 16, 2016
Publication date	Mar 9, 2021
Grant date	Mar 9, 2021

Abstract

A powertrain has a continuously variable transmission including a shaft rotatable about an axis. The CVT further comprises a variator assembly that includes a pulley supported on the shaft. The pulley has a movable sheave with a ramp surface. The movable sheave is axially movable on the shaft. The variator assembly also includes an endless rotatable device frictionally engaged with the movable sheave. An actuator mechanism includes a wedge component supported on the shaft. The wedge component has a wedge surface that automatically engages the ramp surface when torque on the shaft is in a first direction. The wedge surface applies a wedge force on the ramp surface. The actuator mechanism further includes an actuator that is operatively connected to the movable sheave and is activatable to apply a force on the movable sheave.

First claim

The invention claimed is:

1. A powertrain comprising:
a continuously variable transmission including:
a shaft rotatable about an axis;
a variator assembly including:
a pulley supported on the shaft and having a movable sheave with a ramp surface, wherein the movable sheave is axially and rotatably movable on the shaft; wherein the pulley has an axially-fixed sheave rotatably movable relative to the shaft, and the movable sheave is splined to the axially-fixed sheave;
an endless rotatable device frictionally engaged with the movable sheave; and

an actuator mechanism including:
a wedge component supported on the shaft; wherein the wedge component has a wedge surface that automatically engages the ramp surface when torque on the shaft is in a first direction, with the wedge surface applying a wedge force on the ramp surface; and
an actuator that is operatively connected to the movable sheave and is configured to be activated to apply a force on the movable sheave.

2. The powertrain of claim 1 , further comprising:
a thrust bearing positioned between the axially-fixed sheave and the shaft.

3. The powertrain of claim 1 , wherein the shaft is an input shaft, the axis is an input axis, the pulley is an input pulley, the wedge component is an input wedge component, and the actuator mechanism is an input actuator mechanism, and the actuator is an input linear actuator;
the continuously variable transmission further including:
an output shaft rotatable about an output axis;
wherein the variator assembly further includes an output pulley rotatably supported by the output shaft; wherein the endless rotatable device is frictionally engaged with the output pulley;
an output actuator mechanism comprising:
an output wedge component supported on the output shaft; wherein the output wedge component has a wedge surface that automatically engages with the ramp surface of the output pulley when torque on the output shaft is in the first direction with the wedge surface of the output wedge component applying a wedge force on the ramp surface of the output pulley; and
an output linear actuator that is operatively connected to the movable sheave of the output pulley and is configured to be activated to apply a force on the movable sheave of the output pulley;

wherein the wedge force of the output wedge component and the force of the output linear actuator together contribute to a clamping force of the endless rotatable device on the movable sheave of the output pulley; and
wherein the input linear actuator and the output linear actuator are configured to be activated independently of one another.

4. The powertrain of claim 1 , wherein the actuator is a linear actuator and the force applied by the linear actuator is an axial force along the axis, the linear actuator comprising:
an electric motor;
a linearly movable screw operatively connected to the movable sheave; and
a gearing mechanism operatively connecting the electric motor to the linearly movable screw;
wherein the actuator mechanism further comprises an electronic controller operatively connected to the electric motor and responsive to powertrain operating conditions; and
wherein the electronic controller is configured to activate the electric motor in response to the powertrain operating conditions to move the linearly movable screw to apply the axial force on the movable sheave.

5. The powertrain of claim 1 , wherein the shaft is an input shaft, and further comprising:
an engine coupled to the input shaft and driving the input shaft with torque in the first direction; and
wherein the force applied by the actuator is at least partially in response to the torque provided by the engine.

6. The powertrain of claim 5 , further comprising:
an electric machine operatively connected to the engine and controllable to function as a generator using torque provided by the engine; and
wherein the force provided by the actuator is varied in response to the torque provided by the engine to the generator.

7. The powertrain of claim 5 , wherein the actuator mechanism further comprises:
an electric pump;
a hydraulic system; and
an electronic controller operatively connected to the hydraulic system;
wherein the actuator is configured to be activated via fluid in the hydraulic system that is pressurized by the electric pump.

8. The powertrain of claim 7 , wherein the electric pump has a capacity of less than or equal to 10 bar.

9. The powertrain of claim 5 , wherein the actuator mechanism further comprises:
a mechanical pump configured to be driven by the engine;
a hydraulic system,
an accumulator pressurizable with fluid by the mechanical pump; and
an electronic controller operatively connected to the hydraulic system and to the engine;
wherein the actuator is activated by fluid in the hydraulic system that is pressurized by the mechanical pump when the engine is running; and
wherein the actuator is activated by fluid in the hydraulic system that is released from the accumulator when the engine is not running during a hybrid start-stop mode.

10. The powertrain of claim 9 , wherein the mechanical pump has a capacity of less than or equal to 20 bar.

11. The powertrain of claim 5 , wherein the actuator mechanism further comprises:
a mechanical pump driven by the engine;
an electric pump;
a hydraulic system; and
an electronic controller operatively connected to the hydraulic system and to the engine;
wherein the actuator is activated by fluid in the hydraulic system pressurized by the mechanical pump when the engine is running in a first set of operating conditions; and
wherein the actuator is activated by fluid in the hydraulic system pressurized by the electric pump both during a second set of operating conditions requiring greater fluid pressure than the first set of operating conditions, and when the engine is not running during a hybrid start-stop mode.

12. The powertrain of claim 1 , wherein the wedge surface and the ramp surface are configured so that a ratio of the wedge force to a clamping force of the endless rotatable device on the movable sheave is dependent on an angle of incline of the wedge surface relative to the axis of rotation of the shaft.

13. A powertrain comprising:
a continuously variable transmission including:
an input shaft rotatable about an input axis and an output shaft rotatable about an output axis;
a variator assembly including:
an input pulley supported on the input shaft and an output pulley supported on the output shaft, each of the input pulley and the output pulley having a movable sheave with a ramp surface; wherein the movable sheave of the input pulley is axially and rotatably movable on the input shaft and the movable sheave of the output pulley is axially and rotatably movable on the output shaft; and
an endless rotatable device frictionally engaged with the input pulley and with the output pulley;
wherein the input pulley has an axially-fixed sheave rotatably movable relative to the input shaft, and the movable sheave of the input pulley is splined to the axially-fixed sheave of the input pulley; and
wherein the output pulley has an axially-fixed sheave rotatably movable relative to the output shaft, and the movable sheave of the output pulley is splined to the axially-fixed sheave of the output pulley;

an actuator mechanism comprising:
an input wedge component supported on the input shaft and an output wedge component supported on the output shaft, each of the input wedge component and the output wedge component having a wedge surface that automatically engages the ramp surface of the respective input pulley and output p

Assignees

• Gm Global Tech Operations Llc

Inventors

• Yao Jian
• Duan Chengwu
• Lee Chunhao J
• Lahr Derek F
• Samie Farzad

Classifications

• F16H9/26

  with members having orbital motion · CPC title

• B60Y2300/18016

  Start-stop drive, e.g. in a traffic jam · CPC title

• F16H61/662

  with endless flexible members · CPC title

• F16H57/12

  Arrangements for adjusting or for taking-up backlash not provided for elsewhere · CPC title

• F16H63/065

  hydraulic actuating means · CPC title