With changing vehicle technology, the expectations of drivers and passengers are also undergoing a sea change. They expect a quieter in-cabin atmosphere and an escape from the noise and pollution from the road. Road Noise Cancellation or RNC sensors from Molex offer a new experience for both automotive manufacturers and users. These sensors are lightweight, inexpensive, and use an innovative compact technique of combating road noise.
With growing environmental concerns, electric and hybrid vehicles are causing a greater impact on the automotive market. As these vehicles are quieter than their counterparts with combustion engines, their occupants indicate they perceive a higher level of road noise. The road surface transmits a low-frequency broadband sound that creates a hypnotic humming road noise, through the tires, the suspension, and various body components, into the vehicle. The absence of a combustion engine makes the road noise more perceptible in electric vehicles.
Reducing this noise using sound-dampening materials can be expensive and add to the vehicle’s weight. Early attempts to cancel the road noise actively used complex wire harnesses, while the material they used was less efficient and not as economical as users desire. Moreover, sensors and sound-dampening systems in automotive applications are vulnerable to several harsh environmental factors, including dust, rocks, and water, which can easily damage them.
RNC sensors from Molex are pioneering a newer trend in the luxury category of electric vehicles. The sensing element utilizes the A2B technology that captures sound waves. The system reduces noise from the road that a combustion engine would typically mask.
The A2B audio bus technology minimizes the time the sensors take between receiving the excitation vibrations and generating the processing signal. That means noise cancellation is more efficient. In addition, the sensors can measure the road noise at a slower speed, which allows placing them farther away from the source of the sound. The technology also provides more network data channels.
RNC sensors typically capture sound waves from the vibrations of the vehicle chassis. After detecting the sound waves, it transfers them to the processing unit. This generates a cancellation wave and transmits it to the inside of the vehicle as it travels on the road. The sensors use the A2B audio bus technology by Analog Devices and are daisy-chained to each other. This has the advantage of eliminating the home-run wire harnessing or star-pattern wiring and the use of sound-dampening materials that earlier systems used.
Moles has designed the casings for the sensors to anticipate the dust and water of the harsh automotive environment, for which they carry an IP6K9K rating for the enclosure for protecting the system. Molex also offers their space-saving sealed Mini50 Connector interface. They also offer various mechanical housing configurations for orienting the sensing element to mount them perpendicular to or parallel to the ground. This allows the use of a variety of terminal sizes and connector orientations.
RNC sensors are a low-cost technology for capturing vibration energy from vehicle suspension for optimal cancellation, compared to other noise-cancellation systems. It is possible to configure them in groups of 4 to 8 sensors, depending on the need.