慶應義塾大学 - 電気自動車研究室
Electric Vehicles
Actual Example: Eliica - Integrated Platform Structure
Eliica uses an integrated platform structure.
The first step is developing the frame. Using aluminum extrusion shaping technology, we build a hollow beam structure approximately 20 cm wide by 17 cm high in section. For extrusion shaping we create a single die. Forcing molten aluminum through the die enables us to produce structural members of the same sectional dimensions, up to about 50 m in length. The lengths required for the floor of the car body are cut from the beam, and four lengths are welded together to form the floor structure.
Suspension arms are then fitted to the frame. Once eight motors and mechanical brakes have been added, the integrated platform is complete.
The cabin for mounting on the integrated platform can be created in any shape.
However, since half of the energy used when travelling at highway speeds is due to wind drag, it is vital to create a body with the lowest possible wind resistance. Experience has shown that streamlined designs reduce wind resistance. Bearing this in mind, we drew many sketches and selected several of them for rendering.
The rendering was then converted to digital data
Based on that data, we were able to create a three-dimensional model. For Eliica we created a 1:5 scale model in industrial clay. The model was tested in a wind tunnel and revised according to the test results.
After more than 100 revisions, the car began to take shape. Once the wind resistance figures were sufficiently low, we ended the testing and applied color to create a conceptual model that was close to the finished car.
Using this model as a base, we designed the body structure, produced parts, and assembled them. A press-formed monocoque body would be used for mass production, but as only two Eliica units were developed, we built the body frame from steel pipe.
We then made a body out of fiberglass reinforced plastic (FRP), five times larger than our scale model, and mounted it on the frame to create a complete body.
The interior has the same layout as a regular sedan. One major difference is the gull wing structure for the rear doors. The concept behind this was to enable elegant access to the rear seats.
The driver’s seat is very simple. Like an automatic transmission vehicle, it has an accelerator, a brake pedal, and a steering wheel. To the right of the steering wheel are buttons marked “N,” “D,” and “R.” Press the brake and touch “D” to go forward. Touch “R” to reverse.
Eliica