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CVTs can give cars better perfomance than manual or automatic transmissions because of their ability to hold the engine at the RPM that gives it the most power and therefore best acceleration and the fact that they don't have to actually shift gears (since they are always shifting). The only problem
with that is that when an engine is held at a high RPM, it sounds pretty aweful. Some companies like Nissan create software that lets the engine gradually increase speed to prevent the CVT from actually holding the car at any RPM. While it makes the engine sound more normal, it sacrifices acceleration.
I propose a system that would use speakers to cancel out the sound of an engine at the RPM that it is held at when floored. Because CVTs do hold certain RPMS, there would be no need for sensors (since it would only have to cancel out the sound of a fixed RPM). Once that sound is canceled, other speakers would play pre-recorded sounds of an engine reving through the RPM range. The system would work by translating the car's speed into pretend gear ratios and then calculate how quickly the RPMs would increase, when to "shift", where the redline is, etc. There could even be a seperate simulated RPM tachometer that would read what RPM the speakers were playing. The system would only work when the car is floored since that is the only time that CVTs go into high rpm mode and sound bad. In total this would essentially provide the acceleration of a CVT with the excellent sound of a conventional automatic or manual transmission.
A Nissan Murano floored
http://www.youtube....watch?v=9N_3aSmWhys
Proof that any engine held at a constant RPM sounds bad [acurafan07, Mar 16 2007]
Electric cars kill blind people
http://www.autoblog...-blind-pedestrians/
Quiet operating volume makes it difficult to tell when an electric car is coming without seeing it directly. [Smurfsahoy, Mar 18 2007]
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MAY give better economy than an auto box. Not necessarily better performance. Not as good performance as manual. |
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Actually better performance than a manual is easily possible. CVTs immidiately "downshift" to the rpm that the engine pulls hardest in while manuals require time to downshift and even then have to keep shifting. In 0-60 times published by car magazines, manuals appear faster because the testers rev the engine then dump the clutch (something that you can't do with a CVT) when in every day driving, dumping the clutch isn't possible. |
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Continuously Variable Tranmission |
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I think this is an awesome idea. Why is the simulated engine sound necessary at all, though? Just cancel out, and leave the cab totally quiet. You don't need the feedback in a CVT car anyway. |
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Other advantages are that the exact same speaker system (with sensors, why not just throw these in - pah!) could cancel out sounds that the air makes on your car, sounds while driving under tunnels, wheels on pavement vibrations, or any other noninformative, annoying, constant sound. Car horns and the little kids playing baseball that you're about to ram into have very irregular voices comparitively, and wouldn't be cancelled effectively, so this would not cut down on safety. |
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As an ironic analog to this problem, I am including a link about how electric cars are really dangerous for blind people and children, due to their very quiet operation. (Your idea wouldn't do this, since the sound is only pumped into the cab, but it's still interesting) |
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Hmm I just realized that you would need something to make sure that the waves are lined up perfectly. This means that one of two things is necessary, neither of which is good for a car: |
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1) You are wearing headphones that inject the anti-waves directly into your ear precisely in line with the noises you wish to cancel. This is quite doable, and on the market already, but it can create problems for a driver of a car, since you need to be able to hear traffic sounds to drive safely. It might be possible to have a microphone outside the car that plays these sounds to you through those same headphones, though. |
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2) The speaker that puts out anti-waves could be right next to the actual wave source. But this only works if both are point sources. An engine is big, and waves are coming too unpredictably from too many directions to match them at their source. |
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Yeah I suppose for people who want a completely silent cabin you could just turn the simulated engine sounds off... But for me, I'd keep it on because for one thing I like the sound of an engine and for another, dead silence can be awkward in many situations. |
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Conversation in the back seat of a car: |
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"So, uh, by the way... that favorite dress of yours that you thought you lost last week, well, I sort of took it. And modified it into a jock strap..." |
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<After 10 seconds of silence, the driver slowly reaches over and turns on the artificial engine noises> |
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