BMW has released more photos of the upcoming i7 (codenamed G70) undergoing pre-production development, this time focusing on acoustic testing. At the carmaker’s Research and Innovation Center (FIZ) in Munich, engineers focus on ensuring that occupants are isolated from disturbing noises and potential vibrations, which can come from various sources.
Using acoustic test benches, the team recreates irritating noises registered during test drives and can selectively eliminate them. Roller dynamometers with a unique quiescent level and interchangeable surface coverings enable the measurement and validation of drive acoustics and tyre noise on all road surfaces that are relevant to day-to-day traffic anywhere in the world.
The i7’s electric motors are not exempt from acoustic optimization, with a newly developed noise encapsulation serving to ensure maximum acoustic decoupling across a wide frequency range. This allows drivers to enjoy the characteristic silence of the electric drive unit, or the BMW IconicSounds Electric sound generator system developed in collaboration Hans Zimmer.
Other initiatives include increased body rigidity at the front end and tyres with a foam absorber on the inside for further increase acoustic and vibration comfort. The near-production prototypes of the i7 aren’t the only cars to benefit from this development, as the future 7 Series is also subject to such testing, the carmaker said.
Engineers also subjected i7 prototypes to an acoustic climate test bench to test the vehicle in a range of simulated globally relevant conditions. For instance, the acoustics of the air conditioning and ventilation system throughout the entire vehicle can be fine-tuned for better acoustics at very low or very high temperatures.
Ambient noise from the wind rushing over the vehicle’s body is also observed in an acoustic wind tunnel, with the i7’s clear-cut body surfaces, flush-integrated door handles, aerodynamically optimised side mirrors and nearly closed underbody contributing to reducing air resistance that improves acoustics as well as efficiency.
Other forms of noise intrusion from daily driving can come not just from sources like construction sites and passing trucks, for example, so these are also recreated using loudspeakers to give engineers a good idea of where to place highly effective and weight-optimised sound insulation.
Examples on the i7 include sound absorbers incorporated in the pillar trim, seats, roof liner and rear shelf, which work together with the comfort glazing to prevent unwelcome noise from entering through the windows. There are also fleece elements in the doors and on the sill and wheel arch trim to reduce rolling noise and improve the experience of comfort.
Last but not least, testing at the FIZ also involves an analysis of the i7’s electromagnetic compatibility (EMC). Given the sheer number of electronics onboard the vehicle, these systems must be analysed to ensure they are not susceptible to powerful electromagnetic fields.
Looking to sell your car? Sell it with Carro.
Is it only the 7 that has this special treatment? As the 5 I sat in was not that muted at all.