Infinitely Variable Transmission

1. Infinitely Variable Transmission Dalhousie University Mechanical Engineering

2. The Team Well, Dr. Hubbard hoped we’d fail the first time… • Joel Kaser • Craig Martin • Blair Mountain • Kirby Nickerson

3. 2006 SAE MINI-BAJA • Infinitely Variable Transmission (IVT) • Design, Build, and Test • Improvements

4. DESIGN REQUIREMENTS • IVT designed for Mini Baja power, size and shape • Weight of IVT is to be less than 31lbs • Vibration free • Maintenance free throughout Baja Competition • Total cost less than $1000.00

5. CVT and IVT’s • Most CVT’s use varying pulley diameters • Range between fixed limits (1 to 4) • IVT range is 0 to 1 • Acts as a clutch • 70% versus 90% efficient

6. Infinitely Variable Transmission IVT Mechanics

7. IVT Mechanics FundamentalIVT Functional Components

8. IVT Mechanics • Output from Engine is Input to IVT • Input Yoke Spins Masses via Pins and Links • Masses are Fixed to bearings which sit on lobes • Lobes have offset shaft bore, creating moment arm

9. IVT Mechanics • Rotation of masses creates a moment about arm assembly shaft • As mass spins relative to lobe, direction of torque changes • Oscillation of torque direction results in oscillation of arm shaft rotation

10. IVT Mechanics • Oscillating shaft disadvantageous • Set of one-way clutches stop counter-clockwise rotation of arm assembly shaft. • Arm assembly shaft oscillates between no motion and clockwise rotation • Do not want output shaft to exhibit stop/go movement

11. IVT Mechanics • To achieve consistent output shaft rotation, additional set of clutches in output shaft • These clutches clamp onto arm assembly shaft, operate opposite direction of earlier clutches • When arm assembly shaft rotates clockwise, clutches clamp, causing output shaft to rotate • When arm assembly stops, clutches release, allowing output shaft free rotation

12. Infinitely Variable Transmission Model Demonstration

13. Infinitely Variable Transmission Design Improvements

14. Previous Issues • Failing Bearings • Complex Masses • Bearings shifting off lobes (axial play) • Bending in Cantilevered Arm Assembly

15. Improvements • Masses • Rectangular for easier manufacturing/testing • Roller Bearings with Inner Race • - Eliminated need for hardened steel lobes • - Easier Manufacturing • - Increased to 1.5” ID for better load rating

16. Improvements • Lobes • standard steel vs. hardened • Lip and c-clip to prevent bearing axial motion • ¼” offset for greater torque • increased to 1.5” OD • Brass spacers between lobes • Yoke Pins (red) • Spacers added to restrict axial motion • Arm Support (yellow) • Retained by spring pin to make body + arm + support one solid assembly

17. Improvements • Yoke Body • Second bearing (red) to prevent cantilevered bending • Moved input shaft out of body ½” • Arm Assembly Shaft • 5/8” ASTM 1144 to resist shear • Extended ½” to allow second bearing to prevent cantilevered bending

18. Infinitely Variable Transmission Baja / IVT Modeling

19. Baja/IVT Modeling

20. Baja/IVT Modeling

21. Infinitely Variable Transmission Current Status

22. Current Status • Final Stages of Development • Correctly Model Baja Vehicle • Race Technology AX22 Computer • Optimization of Masses

23. Infinitely Variable Transmission Conclusion

24. Conclusion • IVT designed to meet all weight and geometry constraints • 52 km/hr • 28 lb • Design will work • Desktop model • Model Baja • IVT prototype functional by end of January

25. Questions