Active air flaps, thermoacoustic encapsulation boost engine efficiency

As automakers search for new means of minimizing the fleet consumption of their vehicles, they have come across the concept of intelligent thermal management as a means of boosting engine efficiency. Essentially, this entails sealing off the engine compartment from its surroundings to as great an extent as possible when it is not in operation in order that it retain its heat, i.e., temperature, and thus minimize the frequency of cold-start situations.

Tier 1 supplier Röchling Automotive (Mannheim, Germany) is adopting a two-pronged approach to such thermal management, which also brings noise damping benefits to boot. Firstly, multilayered encapsulation technology based on low-weight reinforced thermoplastics (LWRT) is employed to thermally and acoustically seal the engine bay from its surroundings. As the 15-mm-thick LWRT materials are laminated with an extremely thin layer of aluminum, they are also resistant to inflammable liquids, they can be used for applications located beneath the powertrain.

Low-weight reinforced thermoplastic sheet (above) is laminated with aluminum (below) to deliver a thermal and acoustic insulation solution for auto engines.

Röchling Automotive says that such encapsulation close to the engine makes especially good sense as this is where the engine has the largest thermal and acoustic radiation surface. Noise reduction directly at the source can reportedly also enable secondary weight savings of up to 12 kilograms.

The second components of the Röchling Automotive solution is the adoption of active grille shutters that isolate the engine from peripheral components such as turbochargers and water pumps that would normally act as thermal bridges and draw heat away from the engine. This type of encapsulation allows virtually the entire periphery of the engine to be effectively isolated by closing various openings. The result is a lower cooling rate.

These active air flaps also improve aerodynamics. When open, they allow high cooling capacity through maximum air flow. In the closed position, they reduce the time which the components need to reach operating temperature by up to 30 percent. This technology has reportedly proven to be very effective in urban traffic and over short and long distances.

"To achieve a higher degree of closure and maximum efficiency, the air flap is becoming the crucial component of engine encapsulation as it allows the front of the vehicle to be sealed off more and more," explains Ludwig Huber, General Manager Innovation and Business Development, Röchling Automotive. "As a result, there are less and less cold-start situations in everyday operation and the engine works more energy-efficiently and produces fewer emissions thanks to its lower fuel consumption." Measurements revealed potential savings with regard to fuel consumption and CO2 emissions of up to two or three percent. 

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