Right inside the gearbox
Polyamide 6.6 stands the heat in BMW 7 Series
Locate the transmission system directly in the
gearbox? Well, why not? That’s exactly what happens in the new BMW 7
Series and the Jaguar S-Type, where the electronic micro-hybrid 6-speed transmission
control system 6HP26 (made by ZF in Friedrichshafen, Germany) sits right inside
the transmission oil. A major problem, of course, is that it has to cope with
very high temperatures of up to 140°C. In order to ensure durability under
these tough conditions, the developers (Oechsler AG in Ansbach) opted for
casings made out of BASF Polyamide 6.6.
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| In the design of the new BMW 7 Series, the 6-speed automatic transmission sits right inside the hot transmission oil in temperatures of up to 140° (photos: BASF) | The control grid casing
and mount for the new BMW 7 Series and the Jaguar S-Type are made from
Ultramid A3HG7, a heat-resistant polyamide 6.6 |
The electronic transmission control system is housed in
polyamide casing. Bosch has combined several gearbox elements in one component
with its newly developed micro-hybrid gearbox. Here too, the magic words are
functional integration. This new type of transmission control system is beneficial
because it is smaller and lighter and requires fewer interfaces. The company
claims that gear changes are now much smoother and that a better fuel economy
is achieved.
Whilst the traditional electronic control system is located elsewhere within
the car, the electronic micro-hybrid control system sits directly inside the
transmission oil where it has to withstand high temperatures. The plastic
housing has to meet the same exacting requirements. At the same time it also
houses the control grid, which provide the electronic interface between the
individual components of the transmission control system and thus ensures
that the electronic systems are fully integrated.
In order to provide durability under these harsh conditions, the plastic components
developers at Oechsler in Ansbach/Weißenberg opted to use BASF Ultramid
A3HG7. The polyamide 6.6 is 35% reinforced with glass fibres, stands up to
the required temperatures even in hot transmission oil and protects the electronic
components. Ultramid A3HG7 not only has high dimensional stability but is
also resistant to vibrations - just two mechanical properties of this material,
which has been put to good use by Bosch for many years in switching valves
and other components.