Quote from the Hybrid Honda Accord review linked from the Priuschat front page: It employs two microphones in the passenger compartment, which transmit to a control unit which identifies any unwanted booming noises from the engine, and generates a signal that is 180-degrees out of phase. That signal is played back through the car's speakers, whether the audio system is on or off, thus cancelling out the potentially offending noise. What is this - a joke??
A joke? No. Isn't this the ANC (Active Noise Cancellation) system I've been hearing about on the Odysseys with VCM (Variable Cylinder Management)? All I think of is is that Honda is trying to mask noisy cars. Why not just make a quiet car in the first place instead of trying to hide the noise?
No, it's not a joke The problem is that the HAH uses Cylinder De-Activation to help Highway Mileage. If you shut down 3 cylinders in a V6, you get an unbalanced and noisy engine. They then use the Bose type Phase Cancellation system to make it so you can't hear your engine rattling back and forth up front. They also have special engine mounts that hopefully will prevent the wobbly beast from prematurely exiting the vehicle.
Yeah, it is tha Active Noise Cancellation thingy that, as Tempus said, cancels out the booming noise produced by the V6 in 3 cylinder mode.
Actually, I'm curious. What if you're cruising with the windows down? What about the rest of us folks who hears the engine? Is there sufficient insulation under the hood to reduce the noise?
Those that have tried driving one with the windows open while VCM is active say it sounds like a miniature helicopter is nearby. So that's likely what everyone else will hear too. That is tolerable. What isn't is the added cost. Noise-cancelling and counteractive engine-mounts isn't free. Prius doesn't have to deal with added complexity like that. And it's system is both cleaner and more efficient. So... Honda gets a kudo for their engineering but a thumbs-down for competiveness.
Who in the world would buy a car with that design. My guess is that this will not be a highly publicised feature. Second guess would be that the hybrid accord's success will be similar to that of the civic hybrid. The bright side? No waiting list.
Apparently, alot of people are buying that design. The Odyssey minivan has it, and I'm seeing them all over the place around here. Personally, I wouldn't be surprised to see Toyota do this when they start adding HSD to the trucks - assuming that they will be paring the system behind V8 engines.
Toyota will need to do something before they start working with V8s.. the V6 HSD systems are reported to be noisy when climbing hills and such. Not sure which review said that though.
Actually, with any Toyota hybrid, reviews have said they were noisy. Why? Because of our PSD. It revs up when more power is requested. All they need to do is add more insulation in the firewall or find a way to make that engine rev noise less intrusive
The fact that the revving occurs at times other than what is currently considered "normal" is the actual "problem". Being able to predict RPM is what those reviewers expect. When they discover they cannot with HSD, they call it a negative. You'd be amazed how forgiving a person is when in comes to automatic transmissions. They consider the revving & shifting it does to be totally acceptable. And they don't even realize they are doing it until switching to a Planetary-CVT. Then after awhile, they find the automatic transmission to be annoying.
I'm still wishing they use noise cancellation for something more general such as canceling most cabin noise from tires, engine, etc etc. Could probably create a home-made one? But gotta program a DSP.
Well john, I do agree with you but what about the smooth shifting automatics? Obviously if I was to drive an economy car with an automatic, the shift would be less smooth and thus annoying but what about the more "expensive" models? I just feel bad for the engine and transmission to have to deal with stress at low rpm when it has to haul the weight around
The Dodge 5.7l Hemi V-8 in the Chrysler 300 and Dodge Magnum has a cylinder shutoff feature too. They claim 10% better mileage on the highway with it. Trucks with the 5.7l Hemi don't have the cylinder shutoff feature. Anyone remember the Cadillac V-8-6-4?
<div class='quotetop'>QUOTE(priusenvy\";p=\"77459)</div> The Dodge 5.7l Hemi V-8 in the Chrysler 300 and Dodge Magnum has a cylinder shutoff feature too. They claim 10% better mileage on the highway with it. Trucks with the 5.7l Hemi don't have the cylinder shutoff feature. Anyone remember the Cadillac V-8-6-4?[/b][/quote] Yup, another prime example of GM dumping an untested technology on its buyers. That "system," if you could call it that, was around at the same time their lovely Oldsmobile v8 and Buick v6 diesels were blowing up on their customers.
<div class='quotetop'>QUOTE(Wolfman\";p=\"77329)</div> No, actually you are not. VCM isn't standard on the Odyssey minivan. Neither the $25,195 LX nor the $28,195 EX even offer it. It's only available on the $30,495 EX with Leather and the $34,695 Touring.
No, actually you are not. VCM isn't standard on the Odyssey minivan. Neither the $25,195 LX nor the $28,195 EX even offer it. It's only available on the $30,495 EX with Leather and the $34,695 Touring.[/b][/quote] <<looks up specs] honda site>> Yup, yer right. Looks like the auto rags were wrong on that one.
actually all the GM 4-6-8 lacked was modern computers. When that system came out all we had was Atari, the 286 was still a dream.
There is a fundamental limitation of VCM. Disabling half of 6 cylinders is realistic, since you can space out the cylinder pumping cycle by thirds. But with only 4 cylinders available, reducing it to just 2 for VCM would mean when one is down all the way the other is up all the way. Half would not be as smooth as thirds. The engine could run even rougher & noiser that way. Overcoming that could be rather expensive, making the already pricey system even less competitive. That would leave you stuck with an engine much larger than necessary, hardly a good choice for high efficiency.
