Pirelli Noise Canceling Tire

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Tesla has begun using the ContiSilent tire in some of their vehicles.

Quote:
The Model S uses the ContiSportContact 5P high performance tire that’s outfitted with a sound absorbing polyurethane foam attached to the inner tire. This allows the tire to maintain the same level of grip, steering response and wet performance, but also roll substantially quieter. Early versions of the rear wheel drive Model S P85 were equipped with Continental’s ExtremeContact DW tire which many owners have reported to exhibit much louder road noise than the newer ContiSilent tires.


http://www.tractionnews.com/know-tesla-uses-noise-reducing-tire-technology/
 
Originally Posted By: SubLGT
Continental has similar tech, called ContiSilent.".........Continental has introduced ContiSilent, a new technology that significantly reduces tire noise inside the vehicle. Continental says the improvement can be as high as 9 dB............"
http://www.autosphere.ca/tirenews/2013/08/09/continental-introduces-contisilent/


Certainly a better claim than Pirelli's "Noise Cancelling". Its really just noise reduction (aka, damping, absorption), not "Cancelling".
The term 'noise cancelling' has specific engineering meaning. It means active counter-phase frequency-specific acoustic wave interference, not what Pirelli's tire actually does.
Again, the marketing people go wild with the name and lie to the public.

Originally Posted By: SubLGT
I wonder if punctures are still repairable on these "silent" tires?

I wondered something similar when I squirted latex tire sealant into a tire the other day to fix a tiny leak. It does coat the inside surface. It needs to be cleaned, or in the Pirelli foam case, needs to have the foam surgically removed in the area of the puncture, then I guess you have to glue the section of foam back on there after the puncture is sealed !!! Adds labor costs.
 
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Originally Posted By: SubLGT
The polyurethane foam sponge is designed to absorb these vibrations,


Good idea! Now who will take the initiative to manufacture Polyurethane foam inserts for regular tires??
wink.gif
 
Originally Posted By: PeterPolyol
Originally Posted By: SubLGT
The polyurethane foam sponge is designed to absorb these vibrations,
Good idea! Now who will take the initiative to manufacture Polyurethane foam inserts for regular tires??
wink.gif


Great idea. DIY project: Get some foam, cut it, find the right kind of glue, and then hope it stays put (the nail-biting part....).

Reminds of the semi-recent Uniroyal Nail Guard tires. (Maybe discontinued, as not on their website.) They would coat the inside of the tire with goo to self-seal small punctures. Kind of like what can be done by shooting a bottle of green Slime into a tire. Goo should absorb noise at similar frequencies as this new-fangled polyurethane glued-in inserts.
 
Acura and Lexus use noise reducing wheels on some of their vehicles.

Honda describes their approach in this paper
http://papers.sae.org/2014-01-0022/

Quote:
...technology was developed for mounting Helmholtz resonators on the wheels, enabling reduction of tire cavity noise without placing restrictions on the tires…

... The main structural feature is the fitting and fixing of thin, lightweight plastic Helmholtz resonators in grooves newly cut in the wheels, with the basic concept of the design being to increase the resonator holding force when centrifugal force acts upon it.The cabin noise was verified by driving a vehicle equipped with these tire cavity noise-reducing wheels over a rough road surface. The results confirmed noise reduction effects of approximately 10 dB, and tire cavity noise was also reduced to an inaudible level...
 
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Originally Posted By: SubLGT
Acura and Lexus use noise reducing wheels on some of their vehicles. Honda describes their approach in this paper http://papers.sae.org/2014-01-0022/ "...technology was developed for mounting Helmholtz resonators on the wheels, enabling reduction of tire cavity noise without placing restrictions on the tires…"

That concept of 'Tuned Mass Damper' is the obvious thing to do when targeting energy absorption at a natural (resonant) frequency (or several ones) of interest. Those Helmholtz resonators have high hysteretic plastic material to heat up, absorbing the energy in the narrow band targeted. Clever. Many engineers would have mounted a bunch of rubber covered tuning forks to absorb it, not the greatest solution because they might weigh more and stick up inside there for tire changers to break off.
 
Originally Posted By: oil_film_movies
Great idea. DIY project: Get some foam, cut it, find the right kind of glue, and then hope it stays put (the nail-biting part....).


brb lemme try them on 75 ratio all terrains.

I've only seen the tech on cars with low profile tires though. The new Lincoln Continental with 245/40R20s come to mind. I'd like to see them in at least crossover/large SUV tires though.
 
Originally Posted By: oil_film_movies

That concept of 'Tuned Mass Damper' is the obvious thing to do when targeting energy absorption at a natural (resonant) frequency (or several ones) of interest. Those Helmholtz resonators have high hysteretic plastic material to heat up, absorbing the energy in the narrow band targeted. Clever. Many engineers would have mounted a bunch of rubber covered tuning forks to absorb it, not the greatest solution because they might weigh more and stick up inside there for tire changers to break off.

Narrow-band efficacy indeed. Helmholtz resonators can also operate at a constructive resonant frequency amplifying noise rather than cancelling it, the basis behind some intake manifolds.

Originally Posted By: oil_film_movies

Great idea. DIY project: Get some foam, cut it, find the right kind of glue, and then hope it stays put (the nail-biting part....).

Just need to find a source of custom, laser-cut foam donuts really. Cut it a little over the inner diameter of the tire, stuff it in and it should secure itself
 
Originally Posted By: PeterPolyol
Narrow-band efficacy indeed. Helmholtz resonators can also operate at a constructive resonant frequency amplifying noise rather than cancelling it, the basis behind some intake manifolds.

The tire system doesn't "cancel" anything. It does absorb some. "Cancelling" in engineering means a 180 degree phase, same amplitude, cancellation of noise at specific frequencies or one frequency.

The air in the tire's Helmholtz device resonates at a certain frequency, and then that resonance puts the energy into the plastic diaphragm (with high hysteresis) ... aka, shakes the plastic material .... which heats it up slightly, and that is how the noise energy gets absorbed. Converted to heat in the plastic material.

The main point is the engineers figured out a way to absorb and convert the energy into heat, just like a shock absorber on your suspension.

The intake manifold you mention, yes a Helmholtz too, has the air outlet aimed at the cylinder intake, different than just the energy absorbed in the tire device here. Note the intake manifold material is very stiff (k/m) and does not absorb much of the energy at all compared to the plastic diaphragm in the tire which itself is k/m-engineered to soak up the Helmholtz frequencies.
 
I didn't know we were being so peculiar about the term 'cancellation', but I'll raise you one and point out that it's technically the wheel assembly that bears the resonant cavities and not the tire
wink.gif

You're right, this isn't active noise cancellation as in a powered, inverse-phase to the original exciting wave meant to be destroyed. Then again, I never mentioned it being active or powered. Nevertheless, it does not exclude the ability of a passive tuned-resonance cavity from passively cancelling a primary wave. Do you have any references for the simple damping action of a polymer in the wheel? I have doubts that simple damping is the primary mode of frequency attenuation in the Helmholtz-equipped wheel.

The damping you're describing is more akin to the polyurethane foam described in OP, which is indeed just a simple damper of mid-range resonant frequencies, where the foam is intended to control mid-range resonances produced inside of the wheel cavity by, you guessed it, simple damping. Not as effective, but still something inexpensive that can mount on any standard wheel.

Quote:

The Kühl wheel design was found to be uneffective in shifting the natural frequency of the rim outside the 200 – 250 Hz range. A Helmholtz resonator, which would form a part of the rim structure was tested to selectively remove the tire cavity resonance mode, creating the audible noise peak [5]. In the Helmholtz resonator, depicted in Figure 3 and Figure 4, pressure differences exist between the tire cavity and the second introduced cavity causing pressure waves to move between these cavities. These pressure waves are designed to cancel one another, thereby reducing the sound pressure levels. The designed frequency was determined through wheel assembly testing at 230 Hz while the geometric parameters are determined by the following formula [5]...

From this site outlining various ways to cancel tire cavity resonances.
https://www.researchgate.net/figure/2676...holtz-resonator

As I understand it from the sae.org preview that was posted earlier, the resonators are basic. The material they are made from is thin plastic and they are affixed to the wheel using slots. The centrifugal force of the wheel intended to enhance the 'holding force' of the thin plastic chambers. Now, I don't have access to the full paper, but it's mentioned nowhere that the primary (or any) mode of damping is by acoustic polymer deformation (and the associated heat generated) but rather using the tuned-resonance of the Helmholtz cavities to cancel pressure waves. Do you have a reference for that?


Just as a follow-up: The intake manifold mentioned (the one I have is aluminum) has 3 cavity configurations, opened and closed by butterfly valves. Why three? Because of the limited productive range of each. That point right there being the reason I quoted your earlier post. When the engine operates outside of the constructive resonant frequency of one chamber, if that resonant cavity is not changed (to a different tune), the resonance can actually begin to counter-phase at the intake port in another RPM range, reducing charge volume vs at the constructive resonant frequency, or compared with no tuned resonance at all. That would be the passive noise cancellation one is looking for in a tire and just the opposite of what one is looking for an in an intake manifold, with the principle being exactly the same.
No plastics or polymers are absorbing, or rather 'simply damping', excitation over there. The air mass is the only functioning spring in that case. Tuned Helmholtz-resonators and mass-damping are not synonymous.
 
Originally Posted By: PeterPolyol
Do you have any references for the simple damping action of a polymer in the wheel? I have doubts that simple damping is the primary mode of frequency attenuation in the Helmholtz-equipped wheel. ..... Tuned Helmholtz-resonators and mass-damping are not synonymous.


There is energy conservation (and conversion) principles in physics, the biggest reference you seek, and there is a reference which explains the same thing I did:
"The principal method that causes the Helmholtz resonator to be effective is that the movement of air in the neck of the resonator causes a thermo-acoustic conversion of energy from acoustic sound to heat ...." -- http://pub.dega-akustik.de/IN2016/data/articles/000506.pdf which is specifically referring to the circular tire cavity noise issue here.

Not synonymous? There are unifying first principles at play here. (This is what makes an engineer see solutions, applying physics.) Basic energy-mass-stiffness-damping of Helmholtz resonators and Tuned Mass Dampers are indeed the same.
HR_and_vibration_absorber_sys.JPG


Originally Posted By: PeterPolyol
Quote:
..... tire cavity and the second introduced cavity causing pressure waves to move between these cavities. These pressure waves are designed to cancel one another, thereby reducing the sound pressure levels. ...

From this site outlining various ways to cancel tire cavity resonances.
https://www.researchgate.net/figure/2676...holtz-resonator

Again, NOT cancellation inside the circular tire cavity. The abstract you quoted does not match the actual paper it refers to, probably written by a another person unfamiliar with what the original paper and author actually had working.

Its not that hard to understand if explained this way: Tire cavity acoustic waves excite the Helmholtz cavity at it's resonant frequency, which then absorbs the energy and converts it to heat. Otherwise the acoustics would have been transmitted more through the suspension and surrounding air.
 
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Originally Posted By: PeterPolyol
Nevertheless, it does not exclude the ability of a passive tuned-resonance cavity from passively cancelling a primary wave.


There is another way to look at this.

You'd agree that the counter wave from the Helmholtz resonator must be 180 degrees out of phase to cancel the excitation wave, right?

Thing is, you don't get a 180 degree response from the Helmholtz resonator when excited at the resonant frequency.

The Helmholtz device is primarily a simple 2nd order transfer function, and if you look at the Bode plot you'll notice a 90 degree phase lag response, NOT a 180 degree response at the natural (resonant) frequency.
Note: The Helmholtz device damping (zeta) may be quite low, maybe around 0.05, so the peak would be even higher than the chart shows.

3028052632_08d289e925.jpg
 
Hankook has "Sound Absorber" technology.

Quote:
Hankook says the technology is currently only available in its Ventus S1 evo. SUV, but is in the process of applying it to other sizes and products. These will mainly be UHP tires with low aspect ratios.

Tire noise can stem from a variety of factors, including compound, construction, and tread pattern. In this case, the issue is increased cavity noise that’s typical for lightweight, low-profile tires...

To help deal with the cavity noise, the Sound Absorber technology uses a noise absorbing polyurethane foam inlay sheet that’s bonded to the inside of the tire using Sealguard material. Hankook says the technology reduces the tire’s noise by more than five decibels, which in turn gives drivers the impression that on-road noise has been reduced by more than 50 percent.

The internal foam pad increases the tire’s weight by 450 grams, but Hankook says because it’s placed inside the tire, instead of engineered into the tread or sidewall, it doesn’t affect fuel efficiency.


https://www.autosphere.ca/tirenews/tires...ping-the-peace/
 
Originally Posted By: SubLGT
Hankook has "Sound Absorber" technology.
Quote:
....noise absorbing polyurethane foam inlay sheet that’s bonded to the inside of the tire using Sealguard material. ....

SealGuard material by itself would absorb a lot of sound, a soft gooey material coating the inside of the tire. Similar to Uniroyal's old "Nail Guard" stuff.
Problem is, adding green "Slime", a DIY equivalent, to a car tire these days is problematic, trying to get the fiber-rich goo past the TPMS sensor openings at the base of the valve stem.
 
Originally Posted By: oil_film_movies

There is energy conservation (and conversion) principles in physics, the biggest reference you seek, and there is a reference which explains the same thing I did:
"The principal method that causes the Helmholtz resonator to be effective is that the movement of air in the neck of the resonator causes a thermo-acoustic conversion of energy from acoustic sound to heat ...." -- http://pub.dega-akustik.de/IN2016/data/articles/000506.pdf which is specifically referring to the circular tire cavity noise issue here.


As I type, the acoustic energy from the keyboard that is lost on any physical mass is converted to heat. The concept is so basic that it's taken for granted. Reading the .pdf I'm getting an understanding of this fascination with damping ratios and the energy conversion associated with it, but it's my understanding the author mentioned it only to highlight the end of some of the energy's life as acoustic noise- the problem being solved for.



Originally Posted By: oil_film_movies

Not synonymous? There are unifying first principles at play here. (This is what makes an engineer see solutions, applying physics.) Basic energy-mass-stiffness-damping of Helmholtz resonators and Tuned Mass Dampers are indeed the same.

Sure, sure I agree, but they're definitely not synonymous. Not all Helmholtz cavities function as dampers and no other type of tuned-mass damping device uses exclusively a common gas as both the spring and the mass. No problem seeing the "unifying first principles" between the specific use of a Helmholtz cavity for damping purposes vs other tuned-mass dampers of the general category. Also by definition, a resonator and damper are 180 degrees apart (if you will) in function.

Originally Posted By: oil_film_movies

Again, NOT cancellation inside the circular tire cavity. The abstract you quoted does not match the actual paper it refers to, probably written by a another person unfamiliar with what the original paper and author actually had working.

Any counter-phase resonance destructive to the source phase-frequency qualifies as cancellation, there is no minimum-degree or amplitude threshold that I'm aware of to qualify.

Also bear in mind that the computerized active noise cancellation you're apparently reserving the term 'noise-cancellation' for, is only more effectively noise-cancelling vs passive methods and yet, is never even perfect. In physical real-life, nothing rings perfectly.

Originally Posted By: oil_film_movies

You'd agree that the counter wave from the Helmholtz resonator must be 180 degrees out of phase to cancel the excitation wave, right?

I do not agree and did not say that.

Originally Posted By: oil_film_movies
Tire cavity acoustic waves excite the Helmholtz cavity at it's resonant frequency, which then absorbs the energy and converts it to heat. Otherwise the acoustics would have been transmitted more through the suspension and surrounding air.

And that's also what happens! Aside from the noise that is lost through the mass-damping effect of the apparatus, the offending (target) frequency in this case 255Hz, is also simply shifted to less offensive frequencies, thus that portion of noise energy is not converted to heat at that stage. As far as noise attenuation, this is the basic principle behind noise-shaping. Damping is clearly not the only means of noise attenuation in Helmholtz wheels.
From your reference document (refer to Fig 12 & 13):
"It can be seen that the amplitude at the resonance of 255Hz is reduced by approximately 15dB, by splitting that frequency into two adjascent smaller frequencies which are around dB lower in amplitude. The lower Doppler frequency is reduced by around 2dB due to the bandwidth of the Helmholtz resonator. While the tyre cavity sound pressure amplitude is reduced through the use of Helmholtz resonators, it creates many smaller resonances, at lower amplitudes"


Quote:

Note: The Helmholtz device damping (zeta) may be quite low, maybe around 0.05, so the peak would be even higher than the chart shows.
Sure. The mass of air in the the neck area is not so massive after all.
 
Yokohama has announced a new "quiet" tire, the dB V552, that does not use an internal foam liner like the other tires mentioned in this thread. It will initially be available only in the Asian market, in a wide range of sizes from 14" to 18".

http://www.tyrepress.com/2017/10/be-quiet-yokohama-launches-its-most-silent-tyre-ever/

Quote:
...Yokohama Rubber says the Advan dB V552 is based on the concept of “an unprecedentedly silent tyre that changes the in-car atmosphere” and is intended to deliver “an amazingly calm in-vehicle atmosphere” and a “more pleasant in-car experience to drivers.”

Numerous tyre elements, including tread pattern, profile shape and internal structure, were reviewed “from a zero-basis unbiased by past designs” in order to reduce noise energy….
 
Toyo has taken an approach that differs from the usual foam on the inner liner.
http://www.toyo-rubber.co.jp/english/news/2018/180709_e.html

Quote:
...One method for reducing tire cavity noise is the idea of internally mounting material that has a sound-absorbing effect was implemented in the tire industry as a leading technology. However, we focused on the fact that air flow is generated inside the tire so we incorporated our unique approach to reduce noise by utilizing the flow of air...

...the break-through point that we devised was to mount an arch-shaped perforated film device...

...Tire cavity noise is in the frequency band of 200 Hz to 250 Hz. To check the efficacy of this device in reducing noise targeting this frequency band, we ran actual vehicle tests using tires we manufacture and market. The results of our measurements of noise levels inside the vehicle, showed that tire cavity noise on a passenger vehicle traveling using tires implemented with this device was notably reduce to a maximum level of -12 dB in the frequency range of 200 Hz to 250 Hz, compared to driving on current tires that do not have this device installed...
 
I wonder how a flat repair will be accomplished on these tires? Over the years I estimate that I have had at least 3-4 flat repairs done on every new set of tires over their life span. The only way that I can see to repair these tires would be to plug it from the outside, like they used to do in the old days.
With this in mind, I think that engineering the noise reduction into the wheels is a far better option. Kudos to Honda on this one.
 
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