One of the goals in the series development of the all-electric BMW i7 is to keep as much disturbing noise away from the occupants as possible. BMW has now provided some details about the corresponding test programme on acoustic test benches specially designed for electromobility.
For the clientele who afford a premium saloon, it is not only the drive, not only the driving comfort, the space and the materials including the workmanship that are important, but also the car’s acoustic comfort. With a quiet electric drive, the acoustic properties are even more important. But the drive in the i7 is not supposed to be silent either: Like the i4 and iX, for example, the i7 features effects called IconicSounds by Hollywood composer Hans Zimmer.
BMW says that the well-being in the interior of the purely electrically driven luxury saloon is largely determined by keeping disturbing noises away from the occupants announces before the premiere of the i7. The German carmaker says that a large number of possible noise sources have to be taken into account. The test programme that near-production prototypes of the BMW i7 undergo as part of the acoustic testing at the Munich Research and Innovation Centre (FIZ) is correspondingly extensive.
In the new FIZ Project House North, acoustic test benches have been set up, especially for this purpose, which is specially designed to meet the requirements of electromobility. According to BMW, the roller test stands have “a unique quiet level” and exchangeable linings to simulate and measure rolling noise “on all road surfaces relevant to everyday traffic worldwide”. The stated goal is that those disturbing noises that the development engineers noticed during test drives on the road are to be recreated and specifically eliminated.
Other features were not sorted out on the test benches but were already taken into account in the design. For example, the drive units were acoustically optimised, the mounting of the e-motors was adapted for the i7 and a special noise encapsulation was developed. In addition, the increased body rigidity in the area of the front end contributes to better vibration behaviour. As with the iX, the tyres are fitted with a foam absorber to muffle the noise right inside the tyre.
Road tests have already been completed on the near-production prototypes of the i7. To keep interest in the series high, BMW had already published some info on the test drives during recent hot-land testing and winter test drives. Customers and the media will only get a real impression of the acoustic comfort when the i7 is launched on the market. The presentation is planned with other model variants of the 7 series in the course of this year.
While the acoustic test benches were purchased for the i7 in order to score points in the premium competition with the Mercedes EQS or the Tesla Model S Refresh with Active Noise Cancelling, other electric BMW models will also be able to benefit from the facility in Munich in the future.
Reporting by Sebastian Schaal, Germany
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