modder alert, electronic valves are here

[dcb]

index
people are doing it, using microcontrollers and solenoids to control engine valves, flick a switch to go from high duration "cam" to atkinson cycle, and all points inbetween...

[cleanspeed1]

Doesn't Sturman Industries offer something similiar?

[some_other_dave]

I wonder if they're solenoid valves? I wonder what the durability is? I wonder what the power consumption is? I wonder what the limitations are for valve weight, opening and closing speeds, duty cycle, and RPM? I wonder if they can be used to only partly open a valve?

If they're up to full-time use in an automotive engine, these could be a major improvement over our current engines. Greatly reduced friction, and the ability to custom-tailor your valve openings to current conditions and demands, and more!

Electrically-operated valves have been just around the corner for a long time now. I'm hoping this means they may actually wind up in a real car engine soon!

-soD

[user removed]

So, it's more energy efficient to actuate a valve using electricity generated by an alternator, driven by the same engine?

regards
Mech

[dcb]

A better alternator wouldn't hurt, but the power demands of the poppet valves are not great to begin with, at normal RPMs anyway, and you don't have all those cam bearings and slidy bits (and sometines rocky bits) and chain/sprockets. So it might be a wash in this case, don't know. I don't expect to see a large change in valvetrain power consumption in any event.

[Phantom]

I would love to have something like this for my car but im not sure if that could be scaled up to the valve opening that my larger engine would need, as the more they open the slower it is to respond.

I wonder how much force the solenoids can handle? The reason is if they can handle 90# springs pressing back it could be relatively easy for me to add them to my push rod engine. I would remove the push rods add a separate oil line for the rockers since it is no longer being supplied by the push rods. Then place the solenoids under the rockers to act as the cam and push rods, this will reduce the amount of travel that is needed and remove the delay in closing since it still has a spring to snap it closed. If needed lighter valves could be used (I think the stock springs are 85-90#) I do not think that there are lighter springs, but the rocker ratio can be increased to help the amount of lift.

Hopefully the duty cycle can be adjusted to change the amount of lift.

[dcb]

Originally Posted by Phantom

...
I wonder how much force the solenoids can handle? The reason is if they can handle 90# springs pressing back it could be relatively easy for me to add them to my push rod engine.

Seriously, if they can push on 90lb springs without appreciable power penalty then you can possibly remove your rockers and install a custom valve cover with the solenoids already in place (oh my poor valve cover screws).

But if they can electrically control position in both directions then maybe it could be a head rebuild with some light springs for a close bias and custom valves and a custom valve cover with solenoids to match up to. Sort of like electronic desmodromic. (plus open source controller of course )

[DonR]

WWII German Torpedo's used engines with rotary valves. No springs. I can't attest to how much friction there was. & it's not like longevity was at the top of the priority list. Only had to go maybe a mile or two on a limited air supply.

I know F1 engines use pneumatically assisted valve springs to close faster. This does not use a solenoid.

Just make sure you can never crash a valve.

[dcb]

crashing in the traditional sense seems less likely. With a "rigid" valvetrain, if the piston hit the valve something had to give, i.e. the valve or the piston face or a pushrod or ???

It might be much less of an issue here. I still think you want some closed bias spring, probably nothing like 90lbs though if the solenoid can pull as well as push, but if the piston pushes the valve and the valve has somewhere to go then it might not be catastrophic, or it might be, dunno.

[Diesel_Dave]

I've worked with a couple prototype "camless" engines. Just google "variable valve timing" or "variable valve actuation" and you'll find lots of stuff. Various concepts have been around since at least the 70's, maybe even earlier. BMW (Valvetronic) , Ford, and pretty much all the manufacturers either have some limited form of this, or are at least looking into it. Some systems still have a cam, but have some additional mechanism of providing variable valve timing and/or lift.

The advantage of such system isn't the power consumption of the valvetrain. Frankly, I'd be suprised if there was one.

Here are some of the advantages of flexible valvetrains:

1) Variable timing can be used to eliminate throttling losses, i.e. at part load adjust your intake valve opening and/or closing time to get less air in the cylinder.
2) It enables you to run different valve profiles at different operating points so you can get the best performance everywhere rather than having to pick 1 profile that works okay everywhere.
3) It enables different cycles like Atkinson cyle or Miller cycle--even HCCI/PCCI combustion. Potentially you can also switch into or out of these cycles, although it's a controls challenge to abruptly change from one cycle to another with the engine running.
4) Cylinder deactivation is relatively easy.

People have also been looking at all kind of ther stuff. Like using it for "internal" EGR, i.e. close the exhast valve early to trap exhaust in the cylinder rather than sending it in a tube back around the engine.

The challenge with all this stuff is being able to control it effectively. Realize that with valves if you mess up for 1/10 of a second and valve meets piston = really, really bad things.