The Colorado State University Vehicle Innovation Team’s new HEV systems required both new packaging and custom mounting to retain driver and passenger safety in the event of a crash. This is the responsibility of CSU’s Mechanical Team.
Year Two began for the Mechanical Team with removing components from the vehicle. These included the internal combustion engine, transmission, interior and exhaust to get ready to outfit the Malibu with newly designed systems.
Once the car was stripped down to the essentials, the team took to the drawing board to start integrating new components into the vehicle using Computer Aided Design (CAD) through Siemens NX. The main areas of focus are the powertrain, battery box and hydrogen tanks. Using the full model of the vehicle provided by General Motors, the team was able to place key powertrain elements like the UQM Power Phase 145 electric motor and Borg Warner single speed transmission into the engine bay. Mounts were then designed to interface with the stock mounts used to hold the internal combustion engine and transmission. These mounts were analyzed using Finite Element Analysis (FEA) to determine whether they were able to withstand a crash. Once these mounts were deemed sufficient, flat patterns of the mounts were created and a Waterjet was used to cut the mounts very precisely. These mounts were then TIG welded and the powertrain was integrated into the vehicle.
The Mechanical Team was also in charge of the manufacturing of new CV shafts. These shafts allow the power to travel from the new Borg Warner transmission to the stock Malibu wheel hubs. They have special spline patterns on either end to mate with the Borg Warner transmission and the Malibu wheels. Once the mechanical team was able to track down the splined shafts, new CV shafts were fabricated and welded together.
The fuel cells, which turn hydrogen and oxygen into electricity and water vapor, require gaseous hydrogen to operate. This hydrogen is stored in three tanks mounted in the trunk of the car. These tanks, made by Dynatek, are made from aluminum wrapped in layers of carbon fiber for added stiffness and strength. Much like the motor mounts, the position of the tanks was decided and then mounts were designed and analyzed through Siemens NX.
The battery pack, which was designed by CSU’s Energy Storage Team in Year One, sits in a large carbon fiber box. This box is designed to fit underneath the rear seat, where the gasoline tank used to be, and would be an integral structural member in the event of a side impact. In order to replace the structural member with CSU’s battery box, the team analyzed both systems, the stock configuration and the proposed modification, to ensure stiffness would be retained. Using Siemens NX-8 and NASTRAN, this analysis was carried out and presented to representatives of General Motors and Argonne National Labs and approved. Mounts were designed and analyzed like those for the powertrain and electric motor. Manufacturing of these mounts began in February 2013 and the batteries were mounted in time for regional inspection in March.
The Mechanical Team was happy to get all the different systems that CSU’s VIT designed into the vehicle in a safe and efficient manner, but most of all, the team is excited to get the car driving with zero emissions during Year Three!