Continuously variable transmission

• US 7,198,585 B2
• Filed: 01/05/2005
• Issued: 04/03/2007
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Original Assignee: Fallbrook Technologies Incorporated
• Inventors: Allen, David J., Smithson, Robert A., Miller, Donald C.
• Primary Examiner(s): Wright; Dirk
• Application Number:
  US11/030,018
• Publication Number:
  US 20050119086A1
• Time in Patent Office: 818 Days
• Field of Search: 475/214, 475/215, 476/37, 476/38
• US Class Current: 475/214
• CPC Class Codes: B62M 11/04 of changeable ratio
• CPC Class Codes: B62M 11/14 with planetary gears
• CPC Class Codes: B62M 9/08 involving eccentrically- mounted or elliptically-shaped driving or driven wheel; with expansible driving or driven wheel
• CPC Class Codes: F16H 15/28 with external friction surface
• CPC Class Codes: F16H 15/40 in which two members co-operative by means of balls, or rollers of uniform effective diameter, not mounted on shafts
• CPC Class Codes: F16H 15/50 Gearings providing a continuous range of gear ratios
• CPC Class Codes: F16H 15/503 in which two members co-operate by means of balls or rollers of uniform effective diameter, not mounted on shafts
• CPC Class Codes: F16H 15/52 in which a member of uniform effective diameter mounted on a shaft may co-operate with different parts of another member
• CPC Class Codes: F16H 2037/088 Power split variators with summing differentials, with the input of the CVT connected or connectable to the input shaft
• CPC Class Codes: F16H 2037/101 Power split variators with one differential at each end of the CVT
• CPC Class Codes: F16H 37/084 at least one power path being a continuously variable transmission, i.e. CVT
• CPC Class Codes: F16H 37/0853 CVT using friction between rotary members having a first member of uniform effective diameter cooperating with different parts of a second member
• CPC Class Codes: F16H 37/086 CVT using two coaxial friction members cooperating with at least one intermediate friction member
• CPC Class Codes: F16H 61/6649 characterised by the means for controlling the torque transmitting capability of the gearing
• CPC Class Codes: F16H 63/067 mechanical actuating means
• CPC Class Codes: Y10T 29/49464 Assembling of gear into force transmitting device
• CPC Class Codes: Y10T 408/65 Means to drive tool

Abstract

A variable speed transmission having a plurality of tilting balls and opposing input and output discs is illustrated and described that provides an infinite number of speed combinations over its transmission ratio range. The use of a planetary gear set allows minimum speeds to be in reverse and the unique geometry of the transmission allows all of the power paths to be coaxial, thereby reducing overall size and complexity of the transmission in comparison to transmissions achieving similar transmission ratio ranges.

Claims

1. A power transfer apparatus comprising:

a first plurality of balls, each ball having a tiltable axis about which it rotates;

a first disc in contact with the first plurality of balls;

a first idler in contact with the first plurality of balls;

a second plurality of balls, each ball having a tiltable axis about which it rotates;

a second disc in contact with the second plurality of balls;

a second idler in contact with the second plurality of balls;

an input shaft connected to the first and second discs; and

a third disc in contact with the first and second plurality of balls.

2. The apparatus of claim 1, further comprising a planetary gearset mounted on a shaft, the shaft defining a longitudinal axis, wherein the planetary gearset is operationally coupled to the first, second, or third disc.

3. The apparatus of claim 2, wherein the discs and idlers are mounted coaxially with the planetary gearset along the longitudinal axis.

4. The apparatus of claim 2, wherein the planetary gearset provides a torque input to the input shaft.

5. The apparatus of claim 2, wherein any one of the discs or idlers provides a torque input to the planetary gearset.

6. The apparatus of claim 2, wherein the planetary gearset comprises:

a ring gear mounted coaxially about the longitudinal axis;

a plurality of planet gears in engagement with the ring gear;

a plurality of planet shafts, one for each planet, about which the planet gears rotate;

a sun gear mounted coaxially about the longitudinal axis and in engagement with each of the planet gears; and

a planet carrier mounted coaxially about the longitudinal axis and adapted to support and position the planet shafts.

7. The apparatus of claim 2, further comprising a shaft operationally connected to the idlers and adapted to receive a torque from the idlers and to transmit the torque out of the apparatus.

8. The apparatus of claim 2, further comprising an iris plate positioned between the first and second pluralities of balls.

9. The apparatus of claim 8, wherein the tiltable axis comprises a rotatable spindle.

10. The apparatus of claim 9, wherein further comprising a plurality of rollers coupled to the spindle.

11. The apparatus of claim 8, further comprising cages that support the balls, one cage for each of the first and second plurality of balls.

12. The apparatus of claim 11, the cages comprising stators.

13. The apparatus of claim 12, the cages comprising spacers between the stators.

14. The apparatus of claim 12, further comprising a stator bridge that provides support for and couples to at least some of the stators.

15. The apparatus of claim 14, wherein the iris plate is mounted coaxially with and about the stator bridge.

16. The apparatus of claim 6, further comprising a force generator adapted to generate an axial force that increases the traction between the discs, balls, and idlers.

17. The apparatus of claim 16, wherein the axial force is a function of a transmission ratio of the apparatus.

18. The apparatus of claim 16, wherein the force generator comprises:

a fourth disc having a threaded bore;

a first set of ramps operably coupled to the fourth disc near an outer diameter of the fourth disc;

a plurality of bearings adapted to engage the first set of ramps; and

a second set of ramps, the second set of ramps operably coupled to the first disc and adapted to engage the bearings.

19. The apparatus of claim 18, the force generator further comprising:

a rotatable screw adapted to engage the threaded bore;

a third set of ramps, the third set of ramps operably coupled to the screw; and

a fourth set of ramps, the fourth set of ramps operably coupled to the first disc and adapted to engage the third set of ramps.

20. The apparatus of claim 19, wherein the force generator further comprises:

a thrust bearing contacting the screw;

a linkage assembly adapted to apply a force to the thrust bearing tending to move the screw away from the first disc in response to a shift in the transmission ratio;

wherein in response to a shift in the transmission the linkage assembly varies the axial force applied to the thrust bearing as a function of the transmission ratio.