It's cool when old technology gets applied in a new way but...

Jstas

...it makes one wonder, why didn't we think of this sooner?

http://www.autoblog.com/2008/02/27/new-self-inflating-tire-constantly-under-pressure/

From the article:

Coda's new system uses a peristaltic pump built into the tire to constantly maintain air pressure. You may have seen a peristaltic pump used in hospitals to deliver intravenous drugs to patients. It's basically a spinning wheel pressed against a liquid-filled tube. As the wheel turns, it pushes the tube's contents through one end and pulls more in the other. In our case, your car's wheel is the wheel and your air-filled tire the tube. A valve ensures that your tire's pressure is always constant. Theoretically, the peristaltic pump is much simpler and therefore more reliable than a compressor-based system. It's also potentially lighter, cheaper and doesn't require a power source. Sounds like a darn smart idea to us. Coda plans to display its system at the 2008 SAE World Congress in Detroit on April 14th through the 17th, so we'll see if it makes a splash there with auto industry engineers.

shadowofnight

I use peristaltic pumps at work to meter out slurry for our CMP tools.....they themselves rarely if ever need changing out ( I had one actual pump go bad ) ...but the tubes that carry the slurry ( Any liquid ) INSIDE the pump need changing out on a regular basis ...the rotor makes contact with the tube all the way through the pump cycle and it wears out the tube in time.

We include tubing change out in the yearly pm...I have seen pencil whippers not change them out and have them fail before the next major pm. Also, the tubing has to be installed with a specified amount of tension for the pump to function correctly...too loose and the rotor catches the slackened tubing and locks solid....too tight and it meters inconsistently.

Basically they are fairly difficult to install and PM , but once installed correctly they are an extremely reliable pump.

obieone

Couldn't they take it one step further, and make them gear driven pumps, like the old style fuel pumps on cars, where they were directly coupled to the drivetrain?
Build in an auto release valve at whatever the recommended tire pressure is for that model vehicle. I'm assuming that's kind of what they're doing with the Humvees?

mhardy6647

peristaltic pumps generally cannot pump against much of a pressure head.

zingo

That's awesome. I love technology.