| Author | Message | ||
     Reepicheep |
http://jalopnik.com/the-future-of-the-internal-com bustion-engine-is-camless-369015485 Good video from a company that is thinking clearly. These could give you 16k RPM, an almost square "cam" profile, and could let you do neat things like turn your motor into an air compressor when you engine brake. | ||
| Sifo |
That really is exciting. You can get variable valve timing to optimize economy and power and never get valve float. I didn't see where they get the compressed air. There must be a compressor. I wonder how much loss there is from that. I'm a bit surprised they aren't using electronic actuators. Imagine being able to change your cam shaft with your keyboard! | ||
| Aesquire |
http://en.wikipedia.org/wiki/MultiAir http://www.caranddriver.com/features/fiats-multiai r-valve-lift-system-explained here is the transitional stage between old cam drive and the pneumatic future. Fiat went radical and kept it affordable. Not the fine level of control possible with F1 full pneumatic, but far more than mechanical variable timing... And you can buy a car with this, today. | ||
| Sifo |
Fix It Again Tony has confused me with their marketing on their version of this, which still uses a cam shaft and can't deliver the benefits promised in the OP. They claim that by varying the valve timing and lift they control the engine speed without the throttle, so you save energy by not pulling a vacuum in the intake manifold. It seem to me that you would still be pulling that vacuum in the cylinder when using the valve as the throttle. Wouldn't you still have the same loss? Maybe I'm missing something. Maybe it's just marketing BS.  I still see the OP as a big step forward, assuming the losses of adding the air pump don't kill the benefits. | ||
| Reepicheep |
True... I wonder how much HP is needed to generate enough compressed air. Probably not much... 16,000 actuation's a second is a LOT, but that isn't much mass being moved. It couldn't need more than 1 HP. Probably less. I do wonder how much the valves themselves would cost though. Is it a normal machined part? Or some sort of uber-unobtaninum materials and tolerance? And I wonder how you adjust the valves as they stretch? Or do they even when you can control the virtual cam? Interesting stuff for sure... | ||
| Sifo |
Of course simply getting rid of the friction involved in the cam is nothing to sneeze at either. That may completely offset the air pump losses. | ||
| Oldog |
BTW thats 266.6 hz I wonder what the swept area of the actuator is Say 1 cuin per valve x 2 per cyl X 6 for a reasonable engine = 12 cuin of compressed air per operating cycle, 12 X 266 = 3192 cuin per minute 3192 / 1728 = ~1.85 cfm air used probably less than 10 hp depending on pressure YMMV Ref 8.2 cfm 90 psi ~ 5.0 hp ( compressor head ratings )  | ||
| Aesquire |
First, I'm not defending Fiat's advertising. second, no, it is not the ultimate control promised by full pneumatic actuation. It's also much easier, and, today, cheaper. Go ahead, buy a pneumatic valve train in a car. What? no one has it? Guess we have to wait. Ditto electric solenoid valve actuation. Not ready for prime time. Fiat is involved with the F1 guys and what they have in a car you can buy today is not what you will be able to buy next decade, or maybe in 2 years, but it's here today, and it's for sale. Today. It's also a big step forward from old school hydraulic lifter/cam systems. Stroke by stroke control on intake valve timing and lift is, while not the holy grail, a pretty big help in pollution & fuel consumption control. If I didn't already have a car payment, I'd be looking seriously at the 500, and the Dodge Dart. ( Actually I think the Dart is kind of cute ) I dunno about not pulling vacuum in the manifold, but the idea is you can chose not to open the intake valves, at all, giving you an air spring in the cylinder, greatly reducing pumping losses. Not none, just better. Fiat also isn't using this system on the exhaust valves. Pretty obviously a cost/benefit decision. After all, it IS the Fix It Again Tony company. You want Dual Clutch millisecond control transmissions with a Sport mode that alters the whole car's programming, get a VW. I did.  | ||
| Crackhead |
The to not have the vacuum loss the exhaust would hold both intake and exhaust open allowing for a long duration savaging effect. Then close them with just the right amount of desired CR to have the desired power output. Also, since the valves are directly varied, it could also provide better traction control instead or or in conjunction with skip spark methods. | ||
| Johnnylunchbox |
deleted Edit: Just realized how dumb my statement was. (Message edited by johnnylunchbox on February 26, 2013) | ||
| Brumbear |
I'll bet cold weather will play hell with that system or salt air or high humidity. I remember learning about the German Panzer 35T a Skoda design tank they had an air system when they got it into the Russian winter it was a big fat paper weight. I think it's a great idea BTW but I wonder if they could use something as a bladder rather then direct air. | ||
| Ducxl |
I like Desmodromic valves  | ||
| Bluzm2 |
Duplicate post, sorry (Message edited by bluzm2 on February 27, 2013) |
