Quiet please
The generator is humming, the ventilation system is droning and the angle grinder is whining - it’s enough noise to raise anyone’s stress level. And Bosch researchers are well aware that noise quality has a direct impact on personal comfort.
A familiar example of an annoying sound is the whine of a small hairdryer. But few people know that the noise quality in a car can be polluted by very similar sound effects. Running at about 10,000 rpm, the generator keeps the car’s electronics powered up, and those high revolutions can contribute substantially to vehicular noise. While the noise from a hairdryer can be improved by simply making the device a bit larger, the generator in a car is expected to produce ever more power while staying compact. The additional waste heat is simply removed by a fan. But curbing the associated noise requires all the know-how Bosch researchers can muster. They are using two methods that complement each other: On the experimental side, they are simplifying the component to an abstract rotor-stator model that includes only those specific parts that have a significant effect on noise.
Laser-welding of plastic parts creates a homogeneous connection that guarantees airtight and watertight weld seams. Bosch is already using the technique to encapsulate gas pedal modules, which electronically acquires the position of the gas pedal in the footwell. In this case, the welded joint prevents moisture from seeping into the component. This laser welding process replaces rivet fastening and eliminates the need for a rubber seal. The Bosch researchers’ art consists of understanding how to produce a high-quality weld seam. So far, this has been possible with components made of the same thermoplastic materials, like polyamides or certain polyesters. But development is focusing on combinations of different types of plastic. Because welding plastic doesn’t places any great demands on the beam quality of the laser, it suffices to use a low-maintenance diode laser with a power output of a few hundred watts. How the laser beam is guided across the part depends on the requirements of the weld seam: The laser beam might pass over the seam a single time, or there could be multiple, rapid exposures using a scanner system. The optimal process is developed for each individual application.
Laser-welding of plastic parts creates a homogeneous connection that guarantees airtight and watertight weld seams. Bosch is already using the technique to encapsulate gas pedal modules, which electronically acquires the position of the gas pedal in the footwell. In this case, the welded joint prevents moisture from seeping into the component. This laser welding process replaces rivet fastening and eliminates the need for a rubber seal. The Bosch researchers’ art consists of understanding how to produce a high-quality weld seam. So far, this has been possible with components made of the same thermoplastic materials, like polyamides or certain polyesters. But development is focusing on combinations of different types of plastic. Because welding plastic doesn’t places any great demands on the beam quality of the laser, it suffices to use a low-maintenance diode laser with a power output of a few hundred watts. How the laser beam is guided across the part depends on the requirements of the weld seam: The laser beam might pass over the seam a single time, or there could be multiple, rapid exposures using a scanner system. The optimal process is developed for each individual application.
