OK so they can cancel out the noise...but what about the vibration?
While clearly every engine model is different, I always thought that petrol engines reached maximum efficiency at higher revs (e.g. 4000 rpm) and diesel engines somewhat lower (perhaps 2500 rpm) so I must admit this article has confused me a little. Of course, that may be down to my ignorance. My own driving involves very little time between 700 and 1500 rpm. One is usually accelerating or decelerating through this range.
I should be happy if some expert wants to \'put me right\' on this matter.
Joseph Shimandle
So we started kicking around ideas and came up with noise cancellation like you see in some high-end stereo headphones.\"
Or what Honda has been doing for years on their 6 cylinder deactivation Oddessy van. GM acts like they were the first to do this, but copied Honda.
Comparing a 2 wheel drive vehicle (AWD is an option) and 4 wheel drive vehicles is clever marketing but only that. In general driving of the type most people will do the Ford Escape hybrid is going to provide the best fuel economy for an AWD vehicle. The lowest overall cost of ownership is the 27mpg highway $20,995 Subaru Forester which with AWD is $3,750 cheaper to buy than the $24,745 Equinox. $3,750 will buy the Subaru owner 1000 gallons of gas and that is enough to take them 27,000 miles.
Based on my own experience with two GM produced SUV vehicles I would expect the Subaru to be less likely to need repairs during its useful life than the Equinox as well.
There is a basic construct here that is missing. 32mpg US is about 7.8l/100k. For a 4 cylinder AWD that\'s lousy. Using noise canceling technology means they can\'t get their basic design right in the first place.
Alxaslı Ilkin
how on earth an active noise cancellation could contribute to fuel economy ?
Why not use an electric motor ? They seem to be noise-deficient if one listens to the latest talk around electric vehicles and safety !
noise cancellation like that (using the vehicle speakers) will set up nodes and antinodes. So it will be quieter in some places in the car, and louder in others.
Unless you can put the cancelling signal at the same physical location as the source, you\'re always going to get spatial interference patterns.
Maybe the frequency is so low (wavelength so long) that this doesn\'t really matter. It might just be twice as loud for people you pass on the street.
Why not just fix the engine so it doesn\'t make so much noise in the first place?
They\'re saying the ANC improves economy because it will allow them to run the engine at 1000-1500 rpm, which they\'re saying is a very efficient range for fuel milage. Sounds too low to me, too, Alien. They\'d have to choose some new gear ratios for the trans and/or the rear to get those rpms in play.
Vibration is probably already taken care of. Back 20 years or so (I guess) when Oldsmobile built the Aurora and marketed it as a step forward in luxury cars, or some such fanfare, I remember that one of the things they learned from studying Mercedes was that their chassis had a frequency of 25000kHz, which is beyond our human range. Which means - when it hit a bump, or even just rolling down the highway, the car wasn\'t pummeling you with a constant vibration background noise which, even though you\'d get used to it, would still tire you out and irritate you. They built the Auroras to that new spec, and as I remember it was a first for the Big Three at the time. But I imagine that by now the noise and vibration guys have the low frequencies taken care of...I think our hearing runs out around 15-16000kHz, so they probably get close to that even on the less expensive cars. OK, I *hope* they have by now. I\'m an optomist.
Marvin McConoughey
GM has a good approach. Lower engine RPM is possible even with existing gear ratios simply by requiring the automatic transmission to upshift earlier than now. How well GM has implemented the concept relies on their engineering skills. I agree that vibration cna be an issue. Engine mounts can be had in computer controlled hydraulic and GM\'s Magna-Matic form if that is required to absorb vibration.
Yeah, it\'s possible...good one. So every time you go 0-30mph the transmission runs through all 4 or 5 or 7 gears, whatever you have. That would be pleasent.