The AgileJoint compensation element facilitates the fitting of ducts for indirect charge air cooling. MANN+HUMMEL has now further improved this clever solution for the BMW Group.

Intelligent thermal management, maximum power and low emissions are the current requirements for modern engines. Especially in the high-end area, the trend is away from direct over to indirect charge air cooling. MANN+HUMMEL applies the innovative AgileJoint compensation element to charge air ducts used in indirect charge air cooling. AgileJoint effortlessly compensates fitting tolerances or dimensional changes due to thermal expansion. In addition, it replaces expensive elastomer hoses which were previously used for decoupling. That cuts costs and provides a weight advantage of up to 30 percent. The solution also convinces through its easy fitting.

One instead of two

The plastic specialists from MANN+HUMMEL Bad Harzburg further improved the AgileJoint for the second big series application for the BMW Group. In the first variant, the male coupling consisted of two components, the actual duct and a connection piece which was welded on. In the new variant, this part is now formed directly in the plastic duct. This is made possible by a blow molding process as this process can also be used to manufacture complex duct geometries. The use of this process, however, is a challenge. In contrast to injection molding, the internal geometry is not determined by the tool. As a result, wall thicknesses can vary and lead to higher tolerances. In addition, in the blow molding process the glass fibers are mainly orientated in the direction of the extruded hose. The result is a lower mechanical load-bearing capacity in circumferential direction. Apart from that, in the area of the male connector where the parts have to withstand high forces there is a thinner wall due to the process.

1. Joint Connector: forms the female part of the AgileJoint together with the crown ring

2. Crown ring: is pre-assembled to the male part and joins a snap-fit with the female coupling

3. Connection piece: injection molded male part of the AgileJoint, welded to the actual duct

4. Charge air duct: blow molded with welding interface to connection piece

5. Charge air duct: with connection piece blow molded directly to the duct without interface

6. Support ring: gives mechanical strength to the connection and reduces ovality

Little helper

The solution is the integration of a support ring to generate the required stability. This is not just pushed in, but is pressed from the inside to the outside with the blow molded part using a crimp process with a segmented tool. The process takes the dimension situation of each individual component into account and in this way reduces its oval shape and ensures a stable connection which can also withstand the highest pull-off forces. After the successful use of the first AgileJoint variant and the nomination for the ’Supplier Innovation Award‘, BMW Group will now fit the new charge air duct to its 3.0 liter inline 6-cylinder gasoline engines for the 3, 5 and 7 Series as well as X3 and X5. The BMW Group again benefits from excellent fitting characteristics, reduced costs and lower weight.