First high-heat plastic air intake manifold with integrated charge air cooler in production on hybrid sports car
|Plastic air intake manifold with integrated CAC for 3-cylinder 1.5-liter engine.|
The world’s first high-heat plastic air intake manifold (AIM) with integrated charge air cooler (CAC) in Stanyl Diablo, Royal DSM’s high-temperature-resistant polyamide 46, recently went into production on a recently introduced hybrid sports car—by its description (although not by confirmation from DSM) the BMW i8 (earlier post). Royal DSM noted that the use marks another major step forward in the use of thermoplastics in automotive high-heat zones.
The injection-molded AIM/CAC manifold operates at 220 °C and withstands pulses of high internal pressure. DSM worked closely together with a leading system supplier to develop the AIM/CAC combination, with DSM providing extensive development and processing support. The part is made in Stanyl Diablo OCD2100, which contains 40% glass fiber reinforcement as well as a specially developed and patented heat stabilizer. This grade has a continuous-use temperature of 220 °C and is able to withstand peak temperatures up to 250 °C.
In 2012, Röchling Automotive and DSM received the 2012 Automotive Innovation Award (Powertrain Segment) from the Society of Plastics Engineers–Europe for the first serial production of a DSM Akulon-based air-intake manifold (AIM) with an integrated liquid charged air cooler. Akulon is used for lower temperature AIM applications, combining long term heat aging performance and mechanical properties at 180-200 °C. That unit is applied in Volkswagen TSI engines.
Integrating the CAC into the AIM reduces the length of piping previously needed to reach the air-to-air cooler in the front of the car, leading to increased engine responsiveness and reducing turbo lag. However, this application requires a great deal more from its constituent plastic materials.
Integrating the cooler into the AIM significantly changes the geometry of the manifold in a way that could cause a loss of stiffness and strength, which are critical at higher temperatures, DSM notes. The new geometry also requires materials with high weldability and weld-aging resistance to maintain the part’s integrity. At the same time, the material must withstand exhaust gas recirculation (EGR) and blow-by.
Integrated high temperature AIM/CACs have been produced before, but they have typically incorporated metal components for the manifold. However, the car maker wanted a plastics solution in order to minimize weight and maximize the design flexibility to enable a highly functional assembly to fit into a small space.
The car incorporates a number of technologies that give it the performance of a top-level sports car but a carbon footprint lower than that of a compact city car—among them a hybrid synchronous electric motor combined with a turbocharged 1.5-liter gasoline engine. The engine makes use of an extremely high turbo pressure that results in a very high internal air temperature.
While the integrated AIM/CAC unit makes it possible to deliver higher performance while still meeting the latest gas emission requirements, integrating the cooler into the AIM drives the internal air temperature up to 220 °C in continuous use, with peaks up to 250°C. This increase in pressure and temperature puts additional demands on the manifold material.
Stanyl Diablo polyamide 46 provides a weight reduction of up to 40% versus aluminum, and its optimized processing characteristics reduce system cost. It combines very good mechanical performance with outstanding high temperature resistance, retaining its high stiffness even under continuous-use temperatures of up to 220 °C.
The AIM/CAC is assembled from several moldings using hot gas welding. Due to Stanyl Diablo’s best-in-class weld strength, the assembly is highly resistant to pressure pulsation loads. In addition, parts show good dimensional stability, and Stanyl Diablo OCD2100 produces parts with good surface finish, despite the high level of glass reinforcement.
With national laws everywhere clamping down on engine emissions, and car makers focusing more and more on energy efficiency, we expect the use of plastics air intake manifolds with integrated charge air coolers to increase globally. Stanyl Diablo OCD2100 out-performed the competition in this project, with its combination of high temperature resistance and weld line performance after aging. DSM can expect strong business with this material in that type of application in the future.
With the latest generation of engines, it’s a tough challenge to create air management systems that combine long-term high performance with low weight and top environmental credentials. So I am really happy that, thanks to Stanyl Diablo, we have been able to achieve the challenging targets together with our customer.—Kurt Maschke, Global Segment Manager Air/Fuel, at DSM
DSM is a leader in the development of high temperature resistant thermoplastics for automotive engines. Diablo technology, developed and patented by DSM, improves the long term temperature resistance of materials such as Stanyl polyamide that already have better high temperature performance than standard polyamides; and DSM is also using it to upgrade performance in its Akulon polyamide 6. DSM also licenses Diablo technology to other high temperature thermoplastics suppliers.