Design Project Leads to Advanced Manufacturing ExperienceSat, 09/01/2018 - 10:57
Q: How has CIMA’s electric vehicle project with Moldex and Giant Motors evolved?
A: CIMA has already fulfilled its end of the project, which involved the design of the motor and battery configuration in collaboration with Moldex, as well as the testing of its performance. We created four electric-vehicle prototypes, each with different powertrain and battery characteristics that resulted in four performance standards in terms of autonomy and response time. We tested the duration and charging times of the batteries, as well as the acceleration from 0 to 60km/h in each prototype and they all complied with the requirements established by the Mexico City Ministry of Science, Technology and Innovation (SECITI). Originally, the vehicle had to comply with 120km of autonomy and our results yielded a range of 125-135km under controlled laboratory conditions and on a closed road.
Q: How will CIMA continue with research in electric-vehicle technology after the conclusion of this venture?
A: We delivered three of the four prototypes to Giant Motors, which is the leading partner in the project. We kept one of the vehicles as part of the arrangement that Giant Motors and Moldex had with ITESM and the goal is to keep working on more tests for electric-vehicle technology. This “Prototype Zero” as we call it, will be a mobile testing center for CIMA that will help us participate in the development of better motor technology and research in battery performance.
Q: What lessons did this project provide CIMA and the industry regarding the construction of electric vehicles?
A: The construction of the prototypes clearly illustrated the difference in dynamics between an internal combustion vehicle and an electric vehicle, mostly in the suspension and in driving comfort while turning because of the car’s weight distribution. In an internal combustion unit, most of the weight is in the front of the car. On the contrary, an electric vehicle has a more evenly distributed configuration and if designed properly, its center of gravity can even be at its center. For the vehicle to have a proper functionality, suspension and steering components must be redesigned according to the new weight distribution.
Just adapting an existing vehicle design to include an electric motor is not ideal according to our findings. For the Moldex project, we adapted an existing FAW truck from Giant Motors but our autonomy results would have been even better if we had re-engineered other components in the vehicle as well. Companies such as Volkswagen in Puebla and Ford in Cuautitlan will start to participate in the design of components for electric-vehicle applications and they have already reached out to CIMA so we can teach their engineers about these differences.
Q: What experience did you implement to improve the results of the prototypes created?
A: During the development of the project, we applied a mathematic model to determine the best motor-battery configuration for the vehicle according to its future application. This model used a formula that took rolling resistance between the tire and the pavement into account but, during the testing phase, we found that actually the width of the tire had a significant impact on the vehicle’s performance and its potential autonomy. By narrowing the tire’s area of contact with the pavement, we were able to increase the car’s autonomy by approximately 10 percent.
Another interesting result was that the implementation of a mechanical transmission can improve the performance of electric vehicles. Traditionally, electric vehicles do not need a gearbox because the electric motor can generate enough torque for the car to function properly. The vehicle we were adapting to an electric configuration already had a transmission and we did not want to discard it. We performed our tests with the electric motor coupled with the transmission and that resulted in the possibility of having a smaller motor and a smaller battery bank, which in turn lowered the weight of the entire vehicle.