Testing the limits of hoses

Louise Davis

Markus Linzmaier introduces some extremely tough lines for active chassis control

Automakers are currently working on active chassis control systems.

Such systems guarantee the end customer a high level of comfort, increase safety and, at the same time, enable a sporty driving style. In the future, lowering the body for motorway driving is intended to reduce air resistance and, with it, fuel consumption and pollutant emissions.

In a recent application of this sort, the stresses to which the material was subjected by the extremely tight bending radii required posed particular major challenges for the hose developers.

Technology expert Continental was called upon to work in close consultation with the end customer to make this development possible. A dedicated test rig was developed to identify where the hoses’ limits lie.

The rig approximately simulates both the real chassis motions and the temperature curve.

The first step towards this was to create a virtual test rig model. In this, the installed position of the lines in the vehicle was transmitted directly from the 3D CAD program to the test rig.

Shifting the limits

The polyamide inner lining of the hoses was also modified again to ensure that the requirements relating to the high resistance to temperature and pressure (160 bar continuous pressure, and up to 180 bar briefly, in the range from -40°C to 130°C) are also met.

In conjunction with the results from the motion test rig, this enabled the limits for the bending radii of hydraulic hoses to be considerably shifted.

That is because the tests showed that, even under continuous loading, the hoses can be bent substantially more than the previous calculations had predicted.

For Continental, the investment in an extensive advance development capability has paid off because more and more application fields are opening up for the lines tested with it.

In the future, the active chassis control system could also become increasingly attractive for the SUV segment, which has seen such strong growth.

After all, these large, heavy vehicles will be able to achieve greatly enhanced comfort and safety as a result and cut fuel consumption.

And the wide range of uses to which SUVs are put really demand different chassis settings that are adapted to the relevant requirements.

The trend towards chassis control is more than a passing fad. Continental is convinced that it will soon become accepted as standard among the array of driver assistance systems. Not least because it helps the vehicle manufacturers satisfy their ever more demanding customers who attach great importance to comfort, sporty handling and, above all, safety.

And, contrary to suppositions dating back a number of years, hydraulic systems can continue to play a major role in this. That is because a purely electronic chassis control system is not yet capable of moving the large masses at the required speed – while, in addition, being very much more expensive than an electrohydraulic control system.

Look to the future

Chassis control could also soon be a standard feature in electric vehicles because, particularly during typical motorway driving involving long distances, the reduction in fuel consumption resulting from lowering the chassis would considerably extend the vehicle’s range – a major factor in the purchase decision for end customers.

The motion test rig now gives us the capability to test different applications and develop tailored solutions in consultation with our customers.

Markus Linzmaier is with Contitech

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