For its new generation of 4- and 6-cylinder gasoline engines with indirect charge air cooling, the BMW Group has opted for intake manifolds from MANN+HUMMEL with a fully integrated cooler.
The indirect charge air cooling offers a number of advantages. Its function is more constant and effective than direct charge air cooling and reduces CO2 emissions by up to three percent. In addition, the working principle enables a reduced charge air volume and therefore a faster buildup of boost pressure which improves the responsiveness of the engine. The MANN+HUMMEL solution fully exploits these advantages. The indirect charge air cooling is integrated in the intake manifold and goes one step further. In contrast to conventional screw-in solutions the cooler is completely encapsulated by the shells of the intake manifold which allows the whole system to impress with its high stability without the need for external sealing surfaces.
The BMW Group was looking for a solution for its 4- and 6-cylinder gasoline engines which is able to withstand the high system loads with regard to boost pressure and temperature differences in the component. The engineers at MANN+HUMMEL managed this challenge with the aid of modern simulation technology, expertise and know-how. The engineers used a special bypass seal between the cooler and intake manifold shells to meet the requirements with regard to chemical resistance and low leakage values. The double lip seal made from ethylene acrylate elastomer is able to compensate high tolerances while simultaneously remaining dimensionally stable. The cooler and intake manifold positively lock in order to firmly and securely join them together.
With a temperature difference of less than three Kelvin over four respectively six cylinders, the system also enables an excellent uniform temperature distribution. It is also remarkable that the whole system has to withstand high temperature differences of up to 150 Kelvin between the air inlet and outlet. Absolute manifold pressures of up to three bar and the large areas of the plastic shells required by the cooler lead to a high load on the intake manifold. With the aid of simulations, internally produced prototypes and intensive testing, the specialists at MANN+HUMMEL perfectly designed the components. Special cambering and selective ribbing ensure the highest stability and also reduce weight at the same time. The design also focused on an ideal air flow. The consistent filling of the cylinders is maintained by a plenum design improved by computational fluid dynamics which also leads to a lower pressure loss. The joining of the components using hot gas welding enables narrower and stronger weld seams. The advantages of the complete solution supplied by MANN+HUMMEL with its customized design impressed the BMW Group. The vehicle manufacturer uses the new solution in its 4- and 6-cylinder gasoline engines with longitudinal installation.