Camless valve operation

[Begle1]

What's the best way to do it on a 4-stroke piston engine?


Best I can think of is using a solenoid in the combustion chamber to bleed off a little bit of high pressure air, then using another solenoid for each valve.

Or would it be easier to use high pressure oil pumps?

[GO OVRIT]

What's the best way to do it on a 4-stroke piston engine?

With a camshaft.

[Begle1]

Camshafts suck. You know that they're not going to exist in 20 years, but what's going to replace them?

HPOP's, I imagine... But F1 cars used a pneumatic system of some kind, so I hear.

[Ace]

Yep, in 20 years price will no longer be any object and everyone will able to afford million-dollar cars. Just imagine all the wires and electronic boxes on the Cummins engines by then! As if there aren't enough now already.

[Begle1]

What would any of today's cars be worth if they were being made in 1988? Today we have better materials, better tolerances, way more electronics, et cetera. A $20,000 Chevy Cobalt would probably cost $100,000 in 2008.

A ton of cars today use cam-powered valvetrains with variable-valve-timing or variable-cam-timing contraptions that are very complicated; VTEC, VVL, MiVEC, VANOS, VVTL, NVCS, on and on.

A high pressure oil system would remove the camshafts, the lifters, the pushrods, the rockers, the finger followers, the timing belt and all the crap in the variable valvetrain contraptions.

In all of that stuff's place, it would have a high pressure oil pump, which I don't think would need to be any bigger or fancier than what's found on HEUI Diesel systems, and a big solenoid for each valve. And some kind of seal that would let the high pressure oil open the valve a 40 times a second.

The system would likely be more expensive due to the tolerance required in the HPOP system, but the ability to let an engine make peak torque at every speed would mean that engine would need less cylinders and less displacement, and that would help recoup losses. And I don't see it becoming close to as complicated as some of the exotic valve trains around today.

I find it hard to believe that nobody's made a oil-pressure-operated valvetrain yet. I wouldn't think that the task demanded of the HPOP would be any more difficult to meet than the task demanded of a modern injection pump.

Hell, use a common-rail HPOP to open valves. There we go.

[Begle1]

Huh... Tucker Torpedo prototypes had functioning oil-pressure-actuated valvetrains in 1947... I wonder how his seals worked.

http://en.wikipedia.org/wiki/Camless

[Ace]

I think as part of an internal combustion engine valvetrain system they would be excessively expensive, complex, unreliable and thus quite impractical.

[mprmn08]

I honestly think if you had good solenoids and wired to a tunable computer and were able to go in there and set parameters and now how to read that it wouldnt be that bad. i mean you could really make it the ultimate variable valve timing for whatever you were doing, (i.e. towing, racing, mpg's) i think it wouldnt be bad but thats just me.

[GO OVRIT]

Personally I'll sacrifice optimum performance and efficiency for reliability any day.

[Begle1]

I don't see why it'd be any less reliable than any Diesel direct injection system. Instead of the fluid being pressurized through a hole and bypassing back to the tank, it's pressurizing against a valve spring/ cylinder pressure and bypassing back to the pan.

No valve adjustments or timing belts; no cam wear.

In return for the complexity of two extra injection pumps, you make peak torque at every RPM.

I don't understand why it's not already out there, at least in high-dollar exotics.

[xpetecx]

Ive been reading this thread and finding in very intresting. I have one question though, If the valves were oil driven how would the engine start? The motor would have to be a no interference motor, other wise the pistons would hit the not moving yet valves. I think the time part would be the hardest, unless im missing something. With no mechainical connection how would you time the valve train with the crank on start up?

[Begle1]

Without oil pressure, the valves would be closed. The pressure would work against the valve springs to open up the valves.

Starting without oil pressure, especially in the cold, would be a bear. Just like it is on Powerstroke's with HEUI systems.


Timing would be entirely electronic. If gasoline engines can time spark entirely through electronic means, no reason why an engine couldn't time valves.

[dodgetkboy78]

Well, they make engines with no camshaft, they are called two strokes..................

The new cummins is unreliable enough, just imagine if there was wires opening the valves!

God.........

Technology has not been kind to the automotive industry in the past ten years.

MY cummins has like 350,000 miles on it, how much you wanna bet the cam will still be good in another 350,000?

Not to mention oil ain't gonna flow fast enough for high RPM.

Practical reliability peaked in the early 70's guys.......minus a few here and there........94 chevy trucks, 94-99 Ddges, the 12V cummins.......the 4.7L ford.............

But hey, who is for owning a vehicle we cant work on?

[redneckroot]

I like mechanical things, easy to fix and I don't need 10 different computer set ups to read different vehicles. Example: I have a 1939 Cletrac DD (diesel) crawler (bulldozer without the blade) it was an old oil field tractor that ran 24 hours a day 7 days a week it has a winch on it that can hold several thousand feet of line. In 1975 my grandfather passed away and it was parked in a barn. The barn fell in about 8 years ago. My uncle told me I could have the crawler if I could get it. So my brother and I went down it took me a few hours to dig through the tin and wood from the barn. It was set up to run two 6V batteries, so instead I threw 2 12V's on it just to see if it would even crank over. Thew some diesel in the tank my brother proceeded to beat on the stucken starter. The starter freed up and it started cranking, quick shot of either and it was running, didn't even bleed the lines from the pump, and it drove over and through the rest of the barn. If you think I'm full of crap stop over and I'll show you the rusted pile in my barn. So if it can still run and run well actually after sitting for 30 years I'll take mechanical operated things over anything else. On top of that my old Jeeps that I always end up pulling out of peoples weeds always fire up. I've even towed them around to free the stuck motors up and had them running. Old reliable motors is what I'm a fan of. But maybe I'm just a moron that doesn't know how to work on the newer stuff.

[dodgetkboy78]

Your not a moron, simple is always most reliable.