HV Batteries in Electric Vehicles

New System Solution For Potting and Thermal Management

Electric mobility is gaining momentum: Vehicles with alternative drive systems are regarded as a central component in the fight against noise pollution and steadily rising emissions. Several European countries are already planning to part with the combustion engine. In China – currently the world's largest market for electric vehicles – binding quota regulations for electric and hybrid cars are scheduled for application as early as 2019.

The heart of these vehicles is the built-in HV battery. It consists of hundreds to thousands of individual cells of various shapes and performance classes. They are embedded in a housing that protects the battery from harmful environmental influences such as dust, dirt or moisture. Thermal influences also play a central role here: for normal operation of an electric vehicle, outside temperatures of 10 to 25°C and operating temperatures of approx. 20 to 40°C are optimal. If the temperatures exceed or fall below this ideal range it can have negative effects on the service life, capacity and especially the operational safety of the HV battery. High thermal loads not only accelerate the aging of individual cells. They can also cause internal short circuits and, as a result, serious to irreparable damage to the traction battery and vehicle.

Thermally conductive pastes protect against overheating and vibrations

In order to prevent this, large quantities of thermally conductive paste are used. Approximately 5 to 10 liters of these highly viscous and abrasive materials are dispensed per vehicle in-between the HV battery and the housing – and the trend is rising. In addition to the built-in cooling system, they ensure reliable heat dissipation and help prevent potential defects caused by overheating. Due to their soft, flexible consistency, they also protect the sometimes sensitive components of the HV battery from shocks and vibrations during driving.

Due to the large volumes that have to be dispensed within the required cycle time, as well as their high viscosity and abrasive fillers, the application of heat-conducting media places the highest demands on the dispensing technology used. Scheugenpflug offers a new system solution, consisting of a dispensing system and material feeding system, especially for the encapsulation of HV batteries. This allows high flow rates and thus an increased part throughput - even with highly abrasive potting materials.

New system solution for battery encapsulation

Scheugenpflug has developed the new volumetric high performance dispenser Dos HP based on the proven piston dispenser. With this dispenser, dispensing rates of up to 80 ml/s (max. volume per shot: 316 ml) can be achieved - with consistently high dispensing accuracy. To ensure a sufficiently large movement range for the media application, the Dos HP is mounted to a robot arm.

The PailFeed200 Abrasive barrel follower plate system for 200 l drums is used to feed the potting material to the dispenser quickly and reliably. The delivery volume of the integrated double piston pump is 480 cm3/stroke, the possible delivery pressure is up to 65 bar.