Heroes of silence.

It is not just the absence of a combustion engine and its typical noises that gives the driver of an electric vehicle a completely different driving experience with extremely low ambient noise. The various noise damping measures such as reduced wind and road noise, and the powerful, immediately responsive accelerator also play a part. Certain measures make this possible, such as the use of special films in the manufacture of windshields, the installation of insulating films and materials in the body of the vehicle, and the replacement of exterior mirrors with camera systems that are not exposed to the airstream.

The result: The lower noise levels in a battery-powered electric vehicle – true silence in many driving situations – make creaking and squeaking noises more annoying than before. In some cases, the noises triggered by vibrations or stick-slip phenomena are heard for the first time. Even common functional noises produced by indicators, relays, servomotors, actuators, and actuation noises produced by manual and power adjustment mechanisms in seat and door modules can be distracting at low levels if they do not blend in with the vehicle’s quality profile and acoustic design. Design departments are starting to focus on things like “tinny” sounding locking cams and springs in locking mechanisms, as well as the sounds made by seat rail systems and actuators.
Acoustic vehicle alert systems in Europe, warning pedestrians of approaching vehicles at speeds of up to 12 m/h, will only partially drown out noise interference. In addition, these systems, as well as sound programs that “play” engine sounds or synthetic drive noises, can be turned off by the user. This is likely to occur frequently in order to test the “e-silence” or to demonstrate it to other interested parties. Low noise remains an important design condition and specialty lubricants are becoming increasingly important – as part of after-sales for noise control and as part of the design. The noise levels of a wide range of components and assemblies are reduced according to requirements, thanks to this aging-resistant lifetime lubrication. The lubricants offer targeted vibration damping and friction coefficient optimization, enabling long-term, reproducible cycles in various components, while supporting functionality, acoustics and haptics. The good surface adhesion of manual and electrical lift drives and actuators, cable pull systems and open tooth segments of interior components or door modules, ensures excellent damping properties and low starting torques even at low temperatures.

Test bench for testing individual functions of seat modules.

BECHEM has a long history in the field of noise elimination and muffling in automobiles. In 2000 BECHEM was the first company to introduce a system case representing a small cross section of today’s wide range of noise damping applications. At that time, the case was used to present product solutions to development departments in the automotive industry. The aim was for it to become part of the design because “subsequent and often expensive solutions for an existing design should be avoided,” Thomas Mießner, application engineer in the business unit Speciality Lubricants at BECHEM, emphasizes and adds: “Almost 70% of warranty returns are at least partially related to noise interference inside the vehicle. Electric vehicles exacerbate the problem.”

Measurement of the tendency of coated materials to crease in the air-conditioned stick-slip test bench. Any noise interference, no matter how soft or brief, is a challenge for many developers. Especially when dealing with electric vehicles as they have significantly lower noise levels.

Nowadays, in addition to the actual lubricants, pastes and dispersions, coatings are also included. These anti-friction coatings are included in today’s “noise damping case” as a selection of coated material blanks. The metal, polymer and rubber strips make the huge problem-solving potential – quite literally – tangible. “Many developers and suppliers are not yet fully aware of the wide range of possible applications for anti-friction coatings. The touch dry lubrication solution has enormous problem-solving potential,” explains Thomas Mießner.

BECHEM has continuously developed its lubricants. Today, they have a completely different role to play. BECHEM was awarded the Brose Innovation Award for the second time (2014 and 2018) because these products significantly improve the functionality and lifetime of closure systems and door modules. In addition to new lubricant concepts, BECHEM offers highly specialized formulations that are fully compatible with the ever-evolving materials and material combinations.

Measurement of the noise class of lubricating greases according to the SKF Be-quiet standard. Effective lubrication systems can reduce noise by their very design, and save parts and weight, for example by reducing the wall thickness of housings.