TravisR

iTrader: (9)

No it doesn't, it is absolutely impossible for anything to change the timing of the wave coming back down the crank. In order to do that you basically would have to change the speed of the wave in the material you’re transmitting it through by a huge amount. The harmonic dampeners that work with the visco-elastic principle do not do this. They are able to absorb small amounts of energy more easily like corn starch once the de-latent material absorbs a reasonable amount of energy the system takes a much higher modulus and quickly turns that energy into friction.
You cannot freeze energy in a harmonic system and then release it as you please. You can see this effect in every version of a wave. Examples of this would be an electromagnetic wave interfacing with a dielectric material. A rope tied to a pole with a movable end, or non movable end. Unless you extend the length of the nose of the crankshaft you can't get the tuned length of the crankshaft to change. It will always resonate at particular frequencies and if there are particularly bad resonances then you get an upgrade to a full on balancer which produces an equal and opposite wave to cancel the bad resonant out.

matttheniceguy

Wouldn't the damper change the timing of some of the wave? Some of the wave will bounce right off the end of the crank and go back down the shaft as if the damper wasn't there, but some of the wave will travel into the damper, across the elastomeric coupler, reflect off the outer ring, come back through the elastomeric coupler, and head back into the crankshaft. Tune the speed of the wave through the damper right and you can get it to go back into the crank shaft 180 degrees out of phase with the wave that reflected right off the crank end can't you? (or at least somewhat out of phase enough to cause destructive interference).

Your not storing or freezing any energy, just giving it a second longer path to travel down and come back through, which will change it's phase relative to waves that took the shorter path.


Bah... what we need here is a proper look at how these things are designed and what principals they are using. Anyone have anything on that?

TravisR

iTrader: (9)

Yea that’s true, but the end of the dampener is the same distance as the end of the stock piece. And the waves reflected by the elastomeric ring on the stock pulley and the visco-elastomer fluid in the aftermarket pulley will more than likely give about the same reflection with lower amplitude. The easiest way for me to relate it is an electromagnetic wave hitting an unevenly tapered dielectric material. The waves which make it through are transferred out of the system via heat. The waves that make it back are part of the system.

I enclosed a picture that I thought the wave coming back off the nose looked like. I had to do it in CAD because there is just no way to make a mathematical equation that easily looks like that. You have the impact that traveled down and could not be absorbed by the dampener. It was simply rejected. Then the gradual reflected energy of the dampener as it fails to suppress all the energy and this tapers off exponentially as smaller energies do not trigger the dampening (the latent higher modulus), and finally the energy that was able to be reflected back by the end of the crank and any energy left from the dampener that’s still ringing a bit. There should also be a trailing negative wave, but meh, you get the point.

Now regardless of what dampener you’ve got on the end this pattern should look the same, but let’s say its not? What did you accomplish instead of a solid b your now tuned for producing a b flat. That is maybe a 100 R.P.M. in difference in where the standing waves get excited. I think that’s the major flaw in the argument of it changes the resonant frequency all together. You would have to put some HUGE changes on this system to move all the resonant frequencies out of the band of the engine. If that could be done, why manufacture motors with balancer shafts and all that, it is expensive, heavy, there are tons of downsides over a simpler dampener. It slices, it dices, it turns, it even makes Juliann potatoes and yes it does the dishes, but wait there’s more!

JustJake

Would it be possible to use multiple bore sizes to disrupt the timing of the harmonics on the crankshaft?

kotomile

iTrader: (24)

Why not nip it in the bud? Remove the head, and weld the pistons to their bores. No power stroke = no oil pump damaging waves.

TurboTim

iTrader: (9)

OMG I think you finally found the secret to successful DEI