More MPG

When developing the Chevrolet Equinox, engineers at General Motors utilized stereo headphone technology to help give the popular crossover segment-leading fuel economy.

The 2011 Chevy Equinox gets 32 miles per gallon on the highway, four mpg better than segment competitors like the Honda CR-V, Toyota RAV4 and Ford Escape – all rated at 28 mpg. It achieves this rating by enabling the crossover’s engine to run at a lower RPM. However, this posed a new challenge for noise and vibration engineers.

“There’s a boom, or very low frequency rumble that comes from the engine when it runs in that RPM range,” said Noise and Vibration Development Engineer Jim Vallance. “We knew if we could deaden those booms, we could run the engine at the lower RPM, which would provide a significant boost to fuel economy. So we started kicking around ideas and came up with noise cancellation like you see in some high-end stereo headphones.”

Vallance and his colleagues at GM’s Milford Proving Ground came up with a solution — an Active Noise Cancellation module. This module detects when the engine is running in the 1,000 – 1,500 RPM range and immediately creates a sound-killing countermeasure through the vehicle speakers, essentially eliminating the unwanted sound.

“We take a proactive approach and target only the unwanted sound in the vehicle, which in this case is linked with the engine firing frequency. Then we eliminate it,” said Vallance.

GM’s innovative Active Noise Cancellation system is standard on the Equinox when equipped with a four-cylinder engine.

http://www.chevroletinthenews.com/chevy-equinox-employs-sound-strategy-for-more-mpg/#more-1975
http://www.thinkmidway.com/blog/index.htm