The BMW i7 in acoustic testing!

Reading time 5 Min.

Optimized noise insulation, aeroacoustics and vibration comfort: In order to ensure the best comfort experience ever realized in a BMW, the new BMW i7 undergoes a wide range of tests in the laboratories and on the test benches of the BMW Group. The test program also includes ensuring electromagnetic compatibility. The new BMW i7 is being developed with the aim of combining brand-typical driving pleasure with a first-class comfort experience. The acoustic properties are a key factor here. The well-being in the interior of the purely electrically powered luxury sedan is significantly influenced by keeping the occupants away from annoying noises. A large number of possible noise sources must be taken into account. The test program that the near-series prototypes of the BMW i7 and all other model variants of the future BMW 7 Series complete as part of the acoustic testing is correspondingly extensive.

BMW i7 – acoustic testing

At the Munich Research and Innovation Center (FIZ), the test and development engineers check all of the vehicle's noise emissions and immissions. The drive and road noise as well as the aeroacoustics and the vibration comfort are analyzed in detail in order to record the acoustic properties of the new luxury sedans in all their facets. This also includes the precise tuning of the acoustic pedestrian protection and the engine sound emitted in the interior of the BMW i7, which was developed as part of BMW IconicSounds Electric in a cooperation between the BMW Group and the Hollywood film music composer Hans Zimmer.

The driver of the BMW i7 has the choice: characteristic silence or BMW IconicSounds Electric from the cooperation with Hans Zimmer.

In the new acoustic test benches in the new FIZ Project House North, which are specially designed to meet the requirements of electromobility, all driving situations can be realistically mapped. Disturbing noises, which the trained ears of the development engineers notice during test drives on the road, can be recreated there and eliminated in a targeted manner. Roller dynamometers with a unique quiet level and exchangeable coverings enable the measurement and validation of drive acoustics and tire noise on all road surfaces relevant to everyday traffic around the world.

The requirement for the BMW i7 is to redefine the high standards of the luxury segment in terms of acoustic comfort. In particular, great importance was attached to the silent power generation of the electric drive. The acoustic optimization of the electric drive units, the model-specific bearing concept and a newly developed noise encapsulation for the electric motors all contribute to this.

The sum of these measures helps the BMW i7 to achieve effective sound decoupling across a wide frequency range, which ensures maximum acoustic comfort in the interior in all driving situations. As a result, the driver of the purely electric luxury sedan always has the choice of enjoying either the characteristic quietness of the drive or the emotionally powerful BMW IconicSounds Electric from the cooperation with Hans Zimmer.

The increased body rigidity in the area of ​​the front end as well as tires, in which an internal foam absorber ensures integrated noise insulation, raise the acoustic and vibration comfort of the new luxury sedans to an outstanding level.

Acoustic testing in the climate test bench and in the wind tunnel.

In order to be able to test the effectiveness of all measures even under extreme climatic conditions, the development engineers in the FIZ Project House North use the acoustic climate test bench specially designed for this purpose. There, all globally relevant conditions can be simulated and a wide variety of noise sources, such as the acoustics of the air conditioning and ventilation system in the entire vehicle, can be analyzed and optimized, especially at very low or high temperatures. Just like the drive and tire rolling acoustics, the flow noise can also be reduced in a targeted manner. The aeroacoustics of the BMW i7 are therefore also perfected in the acoustic wind tunnel. The clearly designed body surfaces, flush integrated door handles and aerodynamically optimized exterior mirrors, as well as the almost completely closed underbody, not only contribute to the low air resistance of the luxury sedan, but also to its excellent acoustics.

Innovative materials for optimized noise insulation.

In addition to the noise and vibrations emanating from the vehicle itself, it is above all the external sources of noise that impair the comfort experience while driving. In the new acoustic simulator at FIZ Nord, the noise emissions that emanate from everyday traffic, for example from road construction sites or passing trucks, can be simulated under laboratory conditions. There, the vehicle prototypes are exposed to sound from all directions with a large number of loudspeakers in order to test the effectiveness of the noise insulation in the interior.

Innovative materials that were developed as part of the acoustic lightweight construction ensure highly effective and at the same time weight-optimized noise insulation. The outstanding shielding of external and internal noise is achieved, among other things, with the help of sound absorbers that are incorporated into the pillar panels, the seats, the roof liner and the rear storage compartment. The customer experience is perfected together with the comfort glazing, which prevents disturbing noise entry through the panes. In addition, fleeces in the doors and on the sill and wheel arch trim reduce road noise and ensure maximum comfort.

Intensive testing of electromagnetic compatibility.

With their detailed analyzes and precise optimization, the development and test engineers are pursuing the goal of guaranteeing the best comfort experience ever realized in a BMW in the new luxury sedans. This also includes examining electromagnetic compatibility (EMC). In the so-called EMC absorber hall of the FIZ, the prototypes of the new luxury sedans are exposed to strong electromagnetic fields in order to check the susceptibility of their electrical systems to failure and their interaction with the environment.

The test engineers can analyze the diagnostic results transmitted from the vehicle via fiber optic cables in real time. The test program in the EMC absorber hall enables comprehensive protection of the entire vehicle - from the absolutely reliable functioning of the chassis control and assistance systems to the interference-free reception of online data, telephone, radio, TV and navigation signals.

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For maximum well-being in the luxury segment: the BMW i7 undergoing acoustic testing at the new FIZ North location.
Photo credit: BMW

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