BMW i7 undergoing rigorous acoustic testing to achieve 'best possible comfort'

MANILA: The new BMW i7 is undergoing a series of tests at the BMW Group’s laboratories and on its test benches to guarantee the best possible comfort ever achieved in a BMW. The program is also created to ensure electromagnetic compatibility (EMC).

The BMW i7 is being made with the goal of combining legendary driving pleasure with unrivaled levels of comfort. The acoustic properties are an important consideration here. The degree to which unwanted noises can be kept away from the occupants determines the level of well-being in the interior of the purely electric luxury car. Because there are so many possible noise sources to consider, near-production prototypes of the BMW i7 go through a rigorous acoustic testing process.

Test and development engineers at the Research and Innovation Center in Germany examine the vehicle’s entire range of sound emissions and "imissions." In order to completely identify the acoustic properties of the new luxury cars, motor rolling and rolling noise, as well as aeroacoustics and vibration comfort, are all thoroughly examined. This includes the precise alignment of acoustic pedestrian protection and the motor sound produced in the BMW i7’s interior, the latter of which was developed as part of BMW IconicSounds Electric, a joint initiative between BMW and Hollywood film soundtrack composer Hans Zimmer.

The acoustic benches at the BMW Group’s Research and Innovation Center FIZ North have been specially built to satisfy the demands of electromobility and enable realistic simulation of all driving circumstances. Any obnoxious noise detected by development engineers during test drives can be replicated and selectively removed here. Drive acoustics and tire noise are measured and validated on all road surfaces relevant to day-to-day traffic using roller dynamometers with a unique quiescent levels and interchangeable surface coverings.

The BMW i7 strives to revolutionize the luxury segment’s high standards and this extends to acoustic comfort as well. The electric motor’s noiseless power delivery was given a great importance. Among the contributing factors are acoustic optimization of the electric drive units, a model-specific mount concept, and a new noise encapsulation for the electric motors. These elements, when combined, allowed the BMW i7 to achieve effective acoustic decoupling across a wide frequency range, delivering optimal acoustic comfort in the cabin in all driving conditions. As a result, the driver of the purely electric luxury car can always choose between the motor’s standard silence and the emotionally compelling BMW IconicSounds Electric created in partnership with Zimmer.

Increased front-end body rigidity and tires with an internal foam absorber for integrated noise insulation further contribute to the new luxury car’s remarkable acoustic and vibration comfort.

The BMW i7’s clear-cut body surface, flush-integrated door hands, aerodynamically tuned exterior mirrors, and the almost fully closed underbody not only contribute to its low air resistance, but also help establish its exceptional acoustics.

Aside from the noise and vibrations from the car, outside noise sources are also primary sources of discomfort when driving. The new acoustic simulator at FIZ North allows for the recreation of noise released in everyday traffic under laboratory settings. To assess the effectiveness of the interior noise insulation, several loudspeakers are used to transmit these noises from all directions onto the car prototypes.

State-of-the-art materials made along with acoustic lightweight construction enable extremely effective and weight-optimized sound insulation. Sound absorbers placed in the pillar trim, seats, roof liner, and rear shelf provide excellent shielding of external and internal noise. This, combined with the comfort glazing, which keeps unwanted sounds out through the window panes, puts the final touch to the customer experience. There are also fleece pieces in the doors and on the sill and wheel arch trim, which minimize rolling noise and improve the overall comfort experience.

The development and test engineers strive to guarantee that the new luxury car provide the highest comfort experience ever realized in a BMW by conducting extensive analyses, including an EMC analysis. Prototypes of the new luxury car are subjected to powerful electromagnetic fields in the FIZ’s EMC absorber hall to evaluate the sensitivity of their electrical systems to interference and examine how they interact with the environment.

The diagnostic results conveyed from the car through fiber optic cables can be analyzed in real time by the test engineers. The EMC absorber hall test program ensures overall vehicle protection, guaranteeing highly dependable suspension control and assistance systems as well as interference-free reception of online data, telephone, radio, television, and navigation signals.

Photos from BMW

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