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kdboyce
Way back when my college buddy came up with some ideas he liked. One of them ...
LarryM99
I have a Honda Insight, and even when the gas engine is running people walking ...
Active vibration control technology solves noise issues in hybrid cars
Julien Happich
11/26/2011 5:06 PM EST
In the quest for fuel economy, engine cylinders are switched on and off in hybrid cars, causing varying vibrations and resulting noise levels. Trelleborg's innovative active vibration control (AVC) system is claimed to out-performs traditional passive systems by monitoring and adjusting to sound levels, significantly contributing to improved driver comfort.
AVC monitors and adapts to changing noise and vibration conditions by incorporating a microphone in the cabin as an error sensor, rather than the traditional accelerometer mounted adjacent to the actuator. Data from the microphone is fed into an Electronic Control Unit (ECU) that sends a signal to an electromagnetic actuator or "shaker" located near mount attachment points (possible hot spots for vibration). This "shaker" generates a wave of identical or directly proportional amplitude to the waveform of the original disturbance, but with opposite polarisation, creating the desired level of destructive interference to reduce or cancel the amplitude of the perceived noise or vibration.
AVC can be used on any engine type but is especially suited to hybrid vehicles that include a combustion engine. The Trelleborg Automotive market-leading system includes a closed loop controller, CAN interface, bespoke user interface software, superior IO protection, integrated accelerometer and USCAR connector plus advanced electromagnetic actuator.
In addition, Trelleborg's AVC system uses the "voice coil" approach within the electromagnetic actuator. Inertial voice coil shakers employ a permanent magnet that helps them to move quickly and therefore deal more effectively with higher frequencies, as well as the lower frequencies found at idle. This makes them suitable for dealing with booming 2nd and 4th order sounds and vibrations in addition to idle concerns.
Trelleborg's AVC technology is rated to IP69K, a test specification for applications where high pressure and high temperature is used to sanitise equipment. The AVC system can also replace the balance shaft, giving a significant overall weight reduction in the vehicle, contributing to further fuel efficiencies and cost savings.
Visit Trelleborg Automotive at http://www.trelleborg.com/automotive.
This article originally appeared on EE Times Europe.
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DrQuine
11/27/2011 9:50 AM EST
A very nice solution to an emerging problem. Another acoustic problem associated with such vehicles is their silent operation when in pure electric mode when they may surprise (especially visually impaired) pedestrians. The hybrids will benefit from noise cancellation in reduced active cylinder modes and a little "introduced engine noise" as a warning they are approaching in the pure electric mode (a simple add-on).
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Dave.Dykstra
11/27/2011 6:00 PM EST
Very interesting. I suppose that cost and complexity have been the issues that have prevented something similar from having been done before. The implementation appears to be very ingenious and a sample of some very good engineering.
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LarryM99
11/28/2011 7:05 PM EST
I have a Honda Insight, and even when the gas engine is running people walking in parking lots don't seem to be aware of me. I want at least to be able to generate a loud throat-clearing sound...
larrym
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kdboyce
11/28/2011 9:27 PM EST
Way back when my college buddy came up with some ideas he liked. One of them was a Engine Noise Generator that would make your VW bug sound like a dragster racer. The basic idea now makes more sense in light of the silent electrics. OK, OK, maybe not a dragster sound, but more along the line of a PUTT PUTT or electronically synthesized bubbly sound (ala Chitty Bang Bang) that clearly sets the electrics and hybrid apart from those nasty old combustion engines with high horsepower. Not only would it be different, but also maybe more acceptable than roaring engines.
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