ContiTech Vibration Controls has developed an active vibration control technology for tomorrow's vehicle drive system

Hybrid propulsion, active cylinder controls, compression devices are some of the new technologies that the auto industry is working on for the future. These technologies are likely to usher in more fuel-efficient and environment friendly automobiles. Other than eco-freindly modes of propulsion, the auto industry is constantly striving to save weight. Make components lightweight and thus save on fuel. Lightweight vehicle components however also give rise to various other contradictory issues that new engines, in principle, generate more vibrations. 

Says Dr Hans-Jurgen Karkosch, head of advanced automotive development at ContiTech Vibration Controls,"What is more, lightweight construction is more prone to vibration. We have therefore arrived at a point where little more can be eked out of conventional passive mounting concept." 

Karkosch and his team are focusing on the development of active vibration systems that adhere to the principle of counteracting vibrations. They have already successfully tested the technology they have developed on many experimental vehicles of various makes. 

Active systems 

Four components form the basis of an active vibration system: power generating actuator, an electronic controls device, a power amplifier and an acceleration sensor. ContiTech has a key patent for an electromagnetic actuator. The design of the actuator and the functional development of the active systems in particular fall within ContiTech Vibration Control's core competency. The expertise in Continental's Automotive Systems divisions can also be called into play in the development of control devices and sensors. 

The active absorber system employs electric energy to get the actuator vibrating. This vibration is fed in to the body of a passenger car. Under certain physical conditions it functions as counteracting vibration to absorb the engine's structure-borne noise. This can have the effect to reducing the noise level in the passenger compartment by as much as 12 dBA," explains development engineer Peter Marienfeld. " Already a drop of 10 dBA is perceived by the human ear as a halving of the noise level." 

The actuator is an integrated component of hydromounts. It is capable of absorbing even low-frequency noise interference in the 20-to-40 hertz range. This makes it especially good at offsetting vibrations in the idling range," notes Marienfeld. 

Sound engineering 

Above and beyond the compensation function per se, active vibration systems can also be used to generate a customer specific sound in the vehicle. To achieve this, vibrations are technically reduced in a given frequency range and increased in others. This work to harmonise the structure-borne noise emitted by the engine. Fluctuations in vibrational intensity can be compensated and, at the same time, noise perceived as annoying eliminated," explains Karkosch. 

With the goal of making components lighter and smaller, product development engineers at vibration Controls are already at work on the technology of the future. The next step in development is to test new working of actuator and sensor. Tests with piezo materials have proven very promising. In terms of functionality, they yield results similar to what is obtained with single-purpose actuators," notes Karkosch. Active vibration control components are currently begin tested in diverse projects with European vehicle manufacturers.