GM Engineer Uses Head Phone Technology to Up Fuel Economy in 2011 Chevy Equinox
Here’s what they did: An engine is more fuel efficient when it runs at lower engine speed (RPM)––1,000-1,500––so they wanted to run the Equinox engine in that range in order to get 32 highway. They new they could beat the fuel economy of competitiors Honda CR-V, Toyota RAV4 and Ford Escape, which are all rated at 28 mpg highway if they could run the engine at those RPMs.
But, when they ran it at the lower RPMs, it produced a low frequency rumble noise that could be heard in the cabin. A lack of cabin noise is one of the prized attributes of vehicles today and reviewers are quick to comment on noise in the cabin. They had to find a way to deaden that sound.
Their brainstorming sessions led them to try noise cancellation that is seen in high-end stereo headphones. They created an Active Noise Cancellation module that detects when the engine is running in the 1000-1500 RPM range. The engine speed triggers the module to create a sound-killing countermeasure that is run through the vehicle speakers. The engine noise is eliminated through this module.
Engineers weren’t just battling the engine rumble. They had to work around all the other ambient noises in a vehicle such as road noise, sounds from the stereo system and conversations in the vehicle in order to target the rumble from the engine.
Vallance, a second-generation GM engineer says Active Noise Cancellation is a bold step taken late in development that improved fuel economy up to one mile per gallon. It is standard on the Equinox with a 4-cylinder engine. Rock on, Equinox.