The era of ‘Purpose Built Vehicle (PBV)’ is approaching. But how is PBV different from current internal combustion engines? Most of today’s cars focus on driving and moving. The cabin is also designed to consider driving efficiency and the comfort of passengers. PBV, on the other hand, focuses on purpose - after securing as much space as possible with a simple structure.
However, two technologies are essential to the era of PBVs - autonomous driving, to begin with. By utilizing this technology, the freedom of package design is increased as there is no need to install various equipment for the cabins. You can simply design a cabin that is as spacious and efficient as possible. And as the cabin gets bigger, it can be used for multiple purposes, such as portable hospitals, deployable shops, and autonomous delivery systems using robots.
The second is a dedicated platform that houses the electric drivetrain. The size of the required space varies depending on the purpose, and in order to respond to this, various types of PBVs must be made. Therefore, you need a dedicated platform that can be adjusted freely, and an electric drivetrain that can be mounted on any size of the platform.
The ‘e-CCPM (Electric Complete Chassis Platform Module)’ being developed by Hyundai Mobis is an integrated platform that will serve as the basis for future PBV. It is an all-in-one platform module that integrates the chassis module and battery for electric vehicles in the frame. Combining the ‘life module’ where passengers ride on top of the e-CCPM, a lot of different types of PBVs can be made.
Hyundai Mobis started developing the e-CCPM at the same time as it started producing its prototype in 2019; This is because it was necessary to incorporate Hyundai Mobis’ unique technology to preemptively respond to a situation in which various electric vehicle-based PBVs would emerge.
In the process of developing e-CCPM, Hyundai Mobis focused on various sizes and low-floor structures. The feature of e-CCPM is that it can make various PBVs without developing a separate platform for each vehicle type by using an aluminum frame that can be freely adjusted in size. A single platform makes it possible to create small PBVs for last-mile transportation to large-scale PBVs for various purposes, such as portable hospitals.
Considering the purpose of the PBV, the low-floor design is also impressive. The PBV should have a low floor. With the structure of putting the life module on top, the height of the frame will also determine the height of the threshold. For example, the lower the floor in a mobile hospital, the more comfortable the patient can enter without watching their steps. And if the frame’s floor is low, life modules can be built higher, allowing for more space.
In addition, the frame of the PBV must be strong and light; Because it can load multiple cargos and people. Therefore, the e-CCPM has a double-wishbone suspension with a lowered upper arm, and a GFRP (Glass Fiber Reinforced Plastic) leaf spring that replaces the conventional coil spring, for a low-profile and lightweight structure. GFRP leaf springs are about 30% lighter than steel springs.
A variety of electric drivetrains will emerge in the future. Currently, an electric motor is mounted on the axle to drive both wheels, but an "in-wheel motor" with an electric motor on each wheel will emerge soon. So, e-CCPM is designed to respond to various electric drivetrains. The prototype utilizes the EDU 3-IN-1 system, which houses the motor, inverter, and reducer altogether for optimization to power the rear wheel. It also utilizes the in-wheel motor to power the front wheel. Although it was not used for the prototype yet, the e-corner module newly developed by Hyundai Mobis could be installed.
For reference, the e-Corner module is a next-generation technology that integrates drivetrain, braking, steering, and suspension systems within each wheel of a vehicle. The in-wheel motor, e-brake, e-steering, and damper are combined into one, allowing each wheel to assist in driving without the need for mechanical connection with other devices. Because each of the four wheels of the vehicle can turn 90°, the vehicle can also rotate 360°. These futuristic wheels are suitable for PBVs that have to navigate the complex city center. e-CCPM is preparing for various drivetrain applications from suspension package design.
The e-CCPM prototype runs light and nimble. They are particularly good at changing directions with agility. Steer by Wire technology applied to e-CCPM changes the wheels’ direction with an electrical signal rather than a mechanical connection, so you can freely put the steering wheel. In addition, the ‘rear-wheel steering system’ actively controls the rear wheel according to the steering angle of the front wheel, so the direction of the rear wheel can be adjusted within 10 degrees, and the turning radius is also short. This is a new technology that the Genesis G80 Sport houses. It is also a valuable technology for PBVs in a crowded city center.
No one would know the details of the future automotive industry; of course, technology that you take for granted is often quickly replaced by new technology. The e-CCPM was carefully designed considering this aspect as well. Electro-mechanical brakes (EMB), for example, have two options: calipers and drums. Currently, the caliper method is mainly used, but it may change in the future. This is because the drum brake method can be a new solution if the regulations of brake wear particle emission becomes mandatory.
The caliper method reduces the speed by holding the brake disc that rotates together with the wheel with the caliper. The drum method inflates the brake shoes inside the drum, which rotates with the wheels, and rubs against the drum to reduce speed. Both approaches have advantages and disadvantages; The caliper method can be easily contaminated, but the cooling performance is high because the disc is exposed to the outside, and the dust is emitted into the atmosphere. The drum method reduces the speed by pressing the brake shoes inside the brake drum, which rotates with the wheels, into the drum. Because of its closed structure, the cooling performance is relatively poor. Still, it has the advantages of high durability, and that dust does not easily mix with the atmosphere.
Hyundai Mobis’ e-CCPM is obviously for the era of PBV. The automaker’s integrated platform has been refined in many ways for any type of PBV. Hyundai Mobis is currently working to increase the credibility and perfection of e-CCPM, and it is planning to complete a prototype within one or two years. Future mobility is at our doorstep, indeed.
HMG Journal Operation Team
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