CONTINUOUSLY VARIABLE TRANSMISSION

• US 20080039271A1
• Filed: 08/20/2007
• Published: 02/14/2008
• Est. Priority Date: 10/05/2004
• Status: Active Grant

• Current Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Original Assignee: Fallbrook Technologies Incorporated
• Inventors: Lohr, Charles, Armstrong, Oronde, Miller, Donald, Pohl, Brad, Nichols, Jon, Thomassy, Fernand, Poth, Wesley, Simister, Mathew, Dawe, Daniel, Smithson, Robert
• Granted Patent: US 7,976,426 B2
• Time in Patent Office: Days
• US Class Current: 476/38
• CPC Class Codes: B62M 23/00 Transmissions characterised by use of other elements; Other transmissions
• CPC Class Codes: B62M 9/00 Transmissions characterised by use of an endless chain, belt, or the like cycle chain guards B62J13/00
• CPC Class Codes: F16H 15/28 with external friction surface
• 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: Y10T 29/49462 Gear making
• CPC Class Codes: Y10T 29/49464 Assembling of gear into force transmitting device
• CPC Class Codes: Y10T 29/49467 Gear shaping
• CPC Class Codes: Y10T 29/4984 Retaining clearance for motion between assembled parts

Abstract

A continuously variable transmission (CVT) having a main shaft configured to support and position various components of the CVT. Shift cam discs cooperate with ball-leg assemblies to shift the transmission ration of the CVT. Load cam discs, a torsion disc, rolling elements, and a hub cap shell are configured to generate axial force, transmit torque, and manage reaction forces. In one embodiment, a splined input shaft and a torsion disc having a splined bore cooperate to input torque into the variator of the CVT. Among other things, various ball axles, axle-ball combinations, and reaction force grounding configurations are disclosed. In one embodiment, a CVT having axial force generation means at both the input and output elements is disclosed.

Claims

1. A shift cam disc for facilitating a ratio shift of a continuously variable transmission (“

CVT”

), the CVT having a ball-leg assembly, the shift cam disc comprising;

a surface following the x and y values of the datum curve according to a set of parametric equations of the form;

theta=2*gamma_max*t−

gamma_max
x=Leg*sin(theta)−

0.5*ball_dia*RSF*theta*pi/180+0.5*ARM*cos(theta);


y=leg*cos(theta)−

0.5*arm*sin(theta).

2. The shift cam disc of claim 1, wherein gamma_max is an angle value between 15 and 30 degrees.

3. The shift cam disc of claim 1, wherein RSF is greater than 1.0.

4. The shift cam disc of claim 1, wherein RSF is less than 2.5.

7. The shift cam disc of claim 1, wherein the gamma limits the RSF.

8. The shift cam disc of claim 1, wherein the RSF factor is a function of CVT ratio such that the relation between the idler position of the CVT and the CVT ratio is linearly proportional.

5. The shift cam disc claim Error! Reference source not found., wherein minimum gamma is less than −

20°

.

6. The shift cam disc claim Error! Reference source not found., wherein maximum gamma is greater than +20°

.

9. A method of manufacturing a shift cam disc for facilitating a ratio shift of a continuously variable transmission (“

CVT”

), the CVT having a ball-leg assembly, the method comprising;

generating a datum curve according to a set of parametric equations of the form;

theta=2*gamma_max*t−

gamma_max
x=Leg*sin(theta)−

0.5*ball_dia*RSF*theta*pi/180+0.5*ARM*cos(theta);


y=leg*cos(theta)−

0.5*arm*sin(theta); and

forming a shift cam disc surface according to the x and y values of the datum curve.

10. The method of claim 9, wherein gamma_max is an angle value between 15 and 30 degrees.

11. The method of claim 9, wherein RSF is greater than 1.0.

12. The method of claim 9, wherein RSF is less than 2.5.

13. The method of claim 9, wherein minimum gamma is less than −

20°

.

14. The method of claim 9 wherein maximum gamma is greater than +20°

.

15. The method of claim 9, wherein the gamma limits the RSF.

16. The method of claim 9, wherein the RSF factor is a function of CVT ratio such that the relation between the idler position of the CVT and the CVT ratio is linearly proportional.

17. A method for generating cam profiles for facilitating a ratio shift of a continuously variable transmission (“

CVT”

), the CVT having a ball-leg assembly, the method comprising;

determining a desired cam profile; and

generating a datum curve that corresponds to the desired cam profile according to a set of parametric equations of the form;

theta=2*gamma_max*t−

gamma_max
x=Leg*sin(theta)−

0.5*ball_dia*RSF*theta*pi/180+0.5*ARM*cos(theta);


y=leg*cos(theta)−

0.5*arm*sin(theta).

18. The method of claim 17, wherein gamma_max is an angle value between 15 and 30 degrees.

19. The method of claim 17, wherein RSF is greater than 1.0.

20. The method of claim 17, wherein RSF is less than 2.5.

21. The method of claim 17, wherein minimum gamma is less than −

20°

.

22. The method of claim 17, wherein maximum gamma is greater than +20°

.

23. The method of claim 17, wherein the gamma limits the RSF.

24. The method of claim 17, wherein the RSF factor is a function of CVT ratio such that the relation between the idler position of the CVT and the CVT ratio is linearly proportional.