FSAE ELECTRIC
DRIVETRAIN
Northeastern Electric Racing is a team of undergraduate students at Northeastern University with the goal of designing a fully-electric, open-wheel style racecar for the Formula Hybrid + Electric competition. As the lead for the Drivetrain Project, I managed a team of approximately 8 students in the design, manufacture, and installation of the car's drivetrain. The Drivetrain Project encompasses everything from the car's motor all the way to the wheel interface.
CONSTANT-VELOCITYÂ AXLE SYSTEM
OVERVIEW
- Finalize the CV axle system from an unfinished project
- Determine what components are missing or were insufficiently designed and complete the project
CONSTRAINTS
- Must be compliant with the already purchased components
- Must interface properly with differential and wheels
CHALLENGES
- After researching CV axle systems, IÂ determined tripod boots and snap rings were missing, which would have led to the system falling apart if not properly addressed
- The previous project did not spec out any lubrication for the bearings
- The SolidWorks assembly revealed the tripod housings were too short and interfered with the differential mount
RESULTS
- Axle system is now ready for manufacture
- I specced necessary parts
- I specced longer tripod housings which will be altered to match the differential splines
- I created a manufacturing plan to alter the axles to accommodate snap rings
DIFFERENTIAL SEALING
OVERVIEW
- Finalize the differential with mount and case from an unfinished project
- Determine what components are missing or were insufficiently designed and complete the project
CONSTRAINTS
- Must use already manufactured aluminum differential mount
- Whole system must fit inside chassis
- The differential and ring/pinion gears that were already specced must be used
CHALLENGES
- The CAD of the differential was missing the ring gear, leading to incorrect dimensions of designed parts
- Previous case did not have any mounting points, did not seal, and crashed with the ring gear
- The system was missing plans for lubrication
- Material previously chosen would have led to case degradation over time due to necessary oil lubricant
- The mount did not seal; it had holes and unsealed bearings for which seals could not be purchased
RESULTS
- I specced all necessary parts
- I designed a new 3D printed case with o-rings and gasket maker sealant
- I added a high-speed rotary seal to an extension off the mount to provide a seal on the open bearings previously chosen
- I included sealed access ports in the case to allow for oil inflow and drainage as well as access to the differential to remove the axles, all without need for disassembling the entire case
- I chose the inner shape of the case to be as rounded as possible given outer geometry constraints to optimize fluid flow
MOTOR MOUNTING AND INTEGRATION
OVERVIEW
- Finalize the motor mounting and integration from an unfinished project
- Determine what components are missing or were insufficiently designed and complete the project
CONSTRAINTS
- Must use the purchased motor, bearings, yoke, and pinion gear
- Must mount such that the system will not interfere with any existing or planned systems
CHALLENGES
- A part must be designed to hold the bearings such that shims can be used to mimic the gear and bearing adjustment process of a GM 7.5" 10-bolt differential
- The existing CAD model of the yoke was incorrect
- The spacing required for the bearing holder left the motor mounting bars approximately 1/2" away the accumulator container
RESULTS
- I designed a new "bearing holder"Â to allow for proper gear backlash and bearing preload adjustments
- I added spacers for the bearing holder to allow the bearing seal to sit properly
- I designed new mounting bars for chassis integration allow for more room between the drivetrain and the accumulator
- I designed a new motor mounting plate, allowing for more space for the motor cooling attachments