Electromagnetic engine valves

[dkozloski]

Highwire, at the present time with the RareBear F8F Bearcat being out of commission, nothing can hold a candle to the Mustangs. The ironic part is that the Rolls-Royce engines won't stay together without being equipped with internal parts from the much maligned Allison V1710. Dago Red F51 had a 50-75MPH advantage on the rest of the field. When the Sabre entered service they lasted from 20-25 hours. Strangely enough, the C-W R3350's in B-29's were just about the same and that engine evolved into a 2000hr TBO. The British were masters at development. They would run a new design until it broke, fix that, and run it 'til the next thing broke and continue the process until they figured they could get some service out of it. The weak point in the Rolls-Royce Griffon was the propeller reduction gearing as the bunch at Red Baron racing found out very expensively. I have always been fascinated by large reciprocating aircraft powerplants and managed an A/C engine overhaul shop for ten years. The turbines don't do anything for me.

 

[biggestmuff]

Didn't Audi put electromagnetic valves in their F1 cars last season? I seem to remember that.

 

[Talon02]

If you put another set of valve seals (rubber) in the inside of the cylinder or some other soft compound for the exhaust due to extreme heat/ pressure the valves could open/close instantaneouly, also why not an overhead cam pressing directlyon roller valve stems with electonic clutches in the camshaft for automatic timing, way more feasible.

 

[evolotion]

Funnily enough this ti=opic was brought up by someone in uni today (think it was me)..And i never even saw this thread.

Anyways i was museing with the idea of doing this to my mini, as the A-series engine is an old stile push rod deign, it would just be a matter of removeing the long pushrods and replaceing them with solenoids. If a suitable set of rockers(i.e. 3*movement of pushrod:1*movement of valve) were used and a long throw solenoid i cant see why this would not be feisable. as for the return of the solenouid a similar system to that used to dampen the pisten in SU carbourettors could be used, If you are unfamiliar with this sustem basically its a very simple 1 way mechanical, oil based damper. In that it only dampens movement in 1 direction.)

I know this is very mini biased but thought id share my thoughts today with you all

 

[dkozloski]

Another option is desmodromic valve gear such as in a Ducati bike or some of the older Mercedes cars. This uses one cam to open the valves and another to close them with only very light spring pressure to close the valves tightly for starting. The opening cam arrangement is conventional but the closing cam uses a fork in slots in the valve stem to close the valve. The operation of my friends Ducati was very impressive right up to when the crankshft broke from overrevving.

 

[zephyrprime]

<< GM began using computers in production cars very early, an amazingly short time after the micro p was available. They were in their 2nd or 3rd generation or so when they introduced the controlled valve Cadillac 4-6-8 engine. So, if they are going to try again, it will just be a bigger, better computer. >>



I stand corrected. I don't really know a lot about this stuff firsthand, I just remember reading some article a while back.

I've dug up an article about the new engine and it seems like you are indeed correct. Electronics were employed back then.



<< GM tried deactivating unneeded cylinders 20 years ago, and wound up with the disastrous, short-lived Cadillac V-4/6/8 engine. Its operation was jerky, reliability iffy. >>




<< GM pledges no repeat of that. Displacement on demand is a simpler system, controlled by more powerful and more sophisticated electronics, notes Allen Rayl, the engineer developing the electronic controls. >>


USA Today link

 

[bizmark]

link on Cadillac's "Magnetic-Rheological" shocks. The current passes through the fluid itself, which changes its viscosity proportional the the current applied, over 1,000 times a second.

link says Renault is rumoured to have used EM valves ("LVA" -- "?? Valve Actuation") in its F1 cars.



<< Mario Illien, Ilmor-Mercedes, has gone on the record against LVA on the basis that the power consumption would be too great. The need to accelerate each of the 40, 40gm (1.4oz) valves and associated hardware at around 4000g requires an actuator force of 1600N (360lbf). He also stated that valve to piston clearances are around 0.2mm (0.008 in) and so the precision needed in controlling the valve position would be problematical. Also, the heavy electromagnetic coils and magnets would be above the CofG of the engine and so raise it overall. >>



Of course this deals with F1 cars whose RPMs are much higher than regular autos. Also I don't think the CofG issues would worry anyone outside the F1 world But still he seems to take the same issues that have been raised here.

Peopleworking on Electromagnetic Valve Actuators (EVAs).



<< The EVA system places one actuator at each valve site. Two opposing spring coils are also fitted at each site providing the primary force to open and close the valves, and to reduce power consumption and increase reliability. The spring forces are supplemented by electromagnetic force from the EVA coils. The intake and exhaust valves are independently computer-controlled and timed, making it possible to fine-tune air-fuel and exhaust flows to engine needs in a way no camshaft can. >>



So they use two springs, one for each direction. I guess this would solve the problem of the valves closing too hard, right?

link on GM's V8 that uses 4 cylinders at a time. Evidently a solenoid is used somehow to keep the valves closed. And it looks like the reason that the 4-6-8 was so bad, was that 6 cylinders are hard to balance. This new engine skips the 6 part and loses a lot of complexity that would have been needed to make it run smoothly with 6 cylinders.

link with Corvette info: engine closes one of the banks of 4 cylinders when overheating is sensed.

Speaking of Displacement-On-Demand, have you guys all heard of Saab's variable compression engine? This thing looks sweeeet. The cylinders are in the head, which tilts relative to the block to allow for longer piston travel.

 

[evolotion]

Just out of curiosity i removed all the spark plugs from my car and turned the engine over by hand, i also observed when valves were opening and closeing, by doing this i noticed that it takes a LOT of energy to open the valves, so much so that i imagine haveing say an extra alternator on a car would draw less mechanical energy than the cam shaft(s).

This is purely speculation but as far as i can tell the power output of the engine would not suffer from haveing an extra alternator.
But certainly the coils would weigh more than a camshaft and their appropriate workings.

 

[dkozloski]

The net power loss from opening and closing valves is not as great as it may seem because when the valves close the springs return energy to the system. Disregarding friction, the net would be zero.

 

[Howard]

A gift for you guys.

Another one.

 

[Bleep]

<< I've always thought that a rotating spherical or cylindrical "valve" with a large opening through the center would allow much better cylinder filling and eliminate many of the problems with reciprocating valves. Of course the rotating valve would create more frictional drag than the valve seals on poppet valves >>


Rotax has used this method for many years. Very efficient for power a little short on duribility.
Bleep