Morphing Tire Reduces Rolling Resistance

So I can probably end up spending $2000 on tires instead of $800 and save $1000 on gas?

 

Wayne Brown's car energy simulator 'veus' reports 2.2 kw tire resistance when my CTh travels at 55 mph. This is of 10.6 total kW, or about 20%. This fractional contribution will go down at higher speeds, as air resistance continues to increase.

If Michelin decides not to rewrite physics and makes do with a brilliant 25% reduction in rolling resistance, fuel economy will increase 5.2% in our Prii.

 

I'm all for research, knowledge and expansion.
Morphing Polymers that allow my tires to adjust and provide extra efficiency? Sounds great....and problematic....

I would think you then would have to address potential problems with suspensions and rims NOT designed to work with morphing tires. Also the most efficient configuration for a tire in any given situation may not be the safest.

So one step at a time. And at this point I'm not worrying about cost, I don't see myself or anyone buying a set anytime soon.

 

The question is, would this technology stack on top of the approx. 20% lower RR you get form a very good set of LRR tires. So would LRR morphing tires provide 40% or more reduction in RR?

 

The question I have is how will the various modes be selected? Manual only is problematic because you will have people leaving it in the wrong mode for the conditions, which will reduce braking performance. In addition to special wheels, and possibly hubs, an automated system will require additional sensors. The cost isn't just in the tires themselves.

Then how will such system work with those of use that make use of coasts and glides? If LRR mode is only maintained with accelerator input, we won't see the full benefit, and would be better off with plain old LRR tires.

How about we make the info on which tires are actually LRR more readily available to the consumer first. Work it into the triple letter and treadwear system already stamped on the tire.

The fill up for a jet can cost as much as a new car. The 777 can save up 1 million pounds of fuel per year. About $400k in annual fuel costs for airframes with 30+ years service life. Yes, improved efficiency has a cost. For these jets it is one time in the purchase price. For tires, the cost is recurring every 2 to 5 years.

The average age of the US car fleet is now over 10 years. The current economy plays a part, but so does the increasing level of standard features which has been increasing the base price of cars. Even when mainstream, the support system for these tires on the car will increase the price. Increase in price increases the fleet age, which means less efficient vehicles on the road longer. Then depending on the cost of replacing these tires, some may opt to use regular tires, which just negates the point of the system.

With the trend towards optional spares, or none at all, I think the development of airless tires will have a bigger impact on the fleet than these. Unless the morphing tires can reach regular tires in price, I don't see them moving beyond high end vehicles.

 

Hi Justin,

The VEUS program is based on OEM tyres, so most of the current LRR advantage is built-in for my CT since it comes with Primacy MXM4s.

 

How did they get the "Mussels" to flex?

 

Their secrets are shut as tight as a clam.

 

Why not simply have the tires selectively under and over-inflate themselves? Highway speed? Pump it up! Need to brake in an emergency? Dump excess pressure to increase surface area. You could even direct that dump at the disk brakes to clear dust/water and help the brakes work.

Low speed? Drop to the kind of pressure that most American tires are set at, for quiet, smooshy ride. Snow/sand? Under-inflate slightly.

And of course, select comfort/handling/traction profiles for them, too. Communicate wirelessly, just like typical tire pressure monitoring. Powered the same way, too.

In fact, hardly any power or pumping machinery would be needed to keep the tires inflated properly, if this technology can be adapted to car/truck tires and perfected...
Self-inflating tire keeps the pressure up for cyclists

There, now you only need to design a conventional tire that won't wear excessively throughout these predictable deformations, and has a 'pump' structure built-in, probably around the outside edges (more flat, more pumping, more full, less pumping), and a 'dump' valve to relieve any excess pressure that it develops. Settable electronically.

And since the #1 fuel economy killer is improperly inflated tires, this would at least make sure that your tires are always uniformly and correctly inflated, for any road conditions, since they could dynamically adjust the tire pressure, wherever you go. For instance, it's 100F at 3,400 feet elevation when you checked the pressure in the high desert, but when you get to the beach, it's 68F and you're at approximately sea level, so now the tires are under-inflated. With even basic air pressure management, savings over that trip to the beach can be substantial, and safety massively improved. Especially since most people NEVER check the air - they go literally between oil changes to check the tire pressure, and drive around with literally flat tires.

 

The bike tire link has a link to self pumping car tires by Goodyear. With the amount of attention most give to tire pressure, this could be a big deal in terms of improved safety and economy.

Modulating the tire pressure to meet varying needs during a drive. I don't see it working out. At least not without the same issues has the morphing tires, which have the benefit of fast changing. Adjusting the pressure needs fast inflation and deflation in order for it to work, which will likely entail a compressor mounted on the car. The self inflating ones are self contained, and don't require changes made to the car.

 

Deflation can happen very quickly. Pop a solenoid, and out it comes.

Another simplified method that occurs to me would be to have a separate air bladder for the middle channel. This would do the same thing as the images for the 'smart tire', but you could deflate it all the way without risking deflating the tire, and inflate it rapidly, as it has far less volume than the whole tire. You could also store some air pressure in an aluminum pressure chamber around the hub, to make inflating it almost instantaneous, if required. Naturally, the computer would monitor and make sure if one of the center channels goes 'flat', that none of them inflate. Some solenoids and stepper motors to intermittently control mechanical pressure valves would be all the grunty power it needs.

I think such systems would normally only gradually inflate/deflate the tires after sustained speeds, and 'dump' for a hard stop, anyway. Or seek a 'preset' as configured by the driver/computer. Most tires (especially on U.S. vehicles) are under-inflated, if you go by the sticker on the door. So firmer tires for handling/efficiency, and softer for comfort/noise-reduction.

The big question I have for the system is, where the heck does it suck the air IN? It's awfully dirty down where the wheels are typically operating. And wet/muddy. I suppose a hub-mounted air filter with some sort of moisture block would be required, with service/inspection at every oil change and tire rotation. So there'd actually be some 'plumbing' to connect up and balance, between the wheel and the tire. And that would definitely limit the places you could get such tires serviced for a couple of years after their introduction.

 

I would be very concerned as to the tire's ability to "morph" fast enough during an emergency. If you were in eco mode and an animal ran in front of you, or another driver made an error, an emergency maneuver could turn into a deadly maneuver.

 

We have the technology. Its in the hummer. It probably can be done cheaply now
Hummer Central Tire Inflation System.

I like the air compressor better. That cyclist thing looks like it would throw the tire out of ballance.

You could hint hint, do a tread that poofs out a thin wall at high pressure. That would give very low rolling resistance. Automatic dump valve could activate if you are going above a certain speed, or traction control was losing it.

 

I think the pneumatic bladder in the tread wall addresses this. Pop open a solenoid valve, and all the pressurized air's out of it in milliseconds. Much better response than 'relaxing' some sort of 'artificial muscle'. I'd be more concerned about safety interlocks to prevent the secondary bladder from draining the main tire, in case the tire is damaged, and balancing it all, as well as making sure that central tread didn't wear out exactly as you'd see over-inflated tires wear out.

 

The hummer system, which is the only one where something like this has been tried required run flat tires in case of a malfunction. If you are going to have a solenoid quick release some pressure, then you better have a compressor to put it back in if its the wrong pressure

I don't really like the idea of an "artificial muscle" that can poof out. Either way you probably need to pay the weight penalty of runflats. Which may make the price and fuel economy gains look bad.

 

The hummer thing looks expensive as heck, no matter how you slice it.

All those articulated air connections (not only does the wheel spin, it bounces/turns) are certain to go wrong. Maybe the tire is filled through a one-way valve, and bled through another, so the pressurized side of the system can be leaky, overall... but I don't see that in the diagram on your site, so it might fill and distribute pressure to all tires equally, meaning any leak, anywhere will result in four flat tires. Keep in mind how many RPMs those wheels are doing around that pressurized seal, at all times surrounded in dirt and grit.

Machining that air supply through the center of the wheels, threading it through steering and drive components, and all the mechanical linkages and seals involved... looks tricky. Making it reliable that way? Either a design nightmare, or a maintenance nightmare, but probably both.

And any transaxle design would have to mimick the hummer's half shaft design, where the wheel hub is spun indirectly with a gear, or have the air supply go into each transaxle, and through hollow drive shafts to the wheels, where there is still probably a u-joint.

 

You can actually set different pressure in the front and rear. Some vehicles have systems to keep air pressure even with bullet holes, not the hummer though. I'm sure a non-military system can be designed cheaper Like I said, with most deflation systems run-flat tires are a must for malfunctions, you can see it right in the hummer diagram of the tire. CTIS systems are standard for many trucks and military vehicles, making them for a prius is no problem. A leak in part of the system, only takes out that part of the system. The tire simply can't be reinflated from CTIS. Tires can be removed from the system by separating the quick release valve.

They have been doing it since the 50s, its pretty straightforward. Just need one spot that rotates and is air tight. We paid for the design work already, with our tax dollars to the military.

Each wheel needs to be fed through the center. That means no solid axles. Are axles solid now? Unless you regularly go off roading, a moving inflation system is not needed. A compressor in the trunk to pump up your tires, and some automatic dump valves should suffice. That's what I do when offroading.