Future generations of electric vehicles may utilize wireless charging technology that will initially be deployed to charge in the garage. Eventually, the wireless mode could also enable charging on the go at parking spaces, and potentially via extended charging pads installed in road surfaces. In all of these scenarios, the EV requires an inductive charging unit, or car pad module, positioned at the underside of the car at its lowest point. This module is exposed to the road surface, which presents challenging mechanical performance requirements.
|The car pad module for wireless charging is located at the lowest point of the chassis, exposing it to impact from stones and bumps, and to chemicals.|
German OEM Daimler AG is an automaker at the forefront of wireless charging development, and the company has been investigating various materials for use in the housing of these charging units, including aluminum (weighing in at 3.5 kg), a wet-pressed glass fiber fabric/epoxy resin composite (1.9 kg), and a compression-molded polypropylene (PP) resin matrix reinforced with glass fiber mat and fabric (2.0 kg). The latter PP option came out trumps in terms of cost, performance, and manufacturability, producing the component in a net shape from a low-complexity tools. According to Daimler, “attractive economical concepts are feasible [with this processing technology] for vehicle integration, even for small or medium volumes.
Oriented glass fiber reinforcements and the ribs formed during the compression molding process provide protection against mechanical stress applied to the part. Further, glass fiber-reinforced PP reportedly possesses a very good crack propagation prevention mechanism, which can prevent subsequent severe damage after minor damage to the surface from the impact of stones or other objects.
The stainless steel and aluminum inserts required for fixation of the module to the vehicle underbody can either be placed in the tool in a one-shot process or installed during downstream processing. The housing is assembled together with a one-mm-thick aluminum shielding plate with attached cooling fins.