Infinitely Variable Transmission Dalhousie University Mechanical Engineering

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

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

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 $

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

Infinitely Variable Transmission IVT Mechanics

Fundamental IVT Functional Components

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

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

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

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

Infinitely Variable Transmission Model Demonstration

Infinitely Variable Transmission Design Improvements

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

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

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

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

Infinitely Variable Transmission Baja / IVT Modeling

Infinitely Variable Transmission Current Status

Final Stages of Development Correctly Model Baja Vehicle –Race Technology AX22 Computer Optimization of Masses

Infinitely Variable Transmission 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

Questions