23 replies to this topic

[MDK87]

Why hasn't it been invented?

What do you think the limiting factor is when it comes to using solenoid valves in a piston engine?

 

If I had to take a guess, perhaps it has something to do with back EMF affecting cycle time (especially at high RPM's) as it would require high amount of current to overcome even a light spring tension.

Then why can't we use low tension valve springs? Oscillatory motion? 

 

What are the actual reasons?

Obviously an electronically controlled valvetrain would improve volumetric efficiency at just about every RPM.

 

It would be cool if someone with a bit of coin and know how started digging into this!

 

[jack be nimble]

I think f1 was pneumatic valves, Im not sure if they aee banned now or not.
12v is the issue. Its not enough grunt. Eventually we will go to 30v or more and its probable then. Jump starts will be a hazard then tho

[Benzo4gT]

There have been a few attempts at it, or combinations of it over the years (Mercedes etc.). The limiting factors are cost, maintenance, reliability, viability and the true economy of the engine when it's in a chassis.

 

The faster the rpm the higher the energy will have to be to pull it back up, plus the safest engine design would have to be non-interference as a fail safe in case there was a failure of the solenoids

 

The engine in the chassis would have to generate some serious power through the charging system to accommodate the high power demands of this system if it needed tons of energy like Jack has said.

 

The only real benefit would be eliminating parasitic losses due to not having camshafts. Hollow camshafts help with this, but not much.

 

An solenoid system would work decently only if there was an elimination of spring force, as you mentioned.

 

Rotating valves are inefficient so they can be canned.

 

 

A direct injection high compression engine which could be configured to run as a 2 stroke (for power) and 4 stroke (economy) with solenoid controlled adjustable port sizes and location (via a sliding collar around the cylinder which

 

would obviously eliminate valve train completely) and also timing events, advanced swirl design piston/head shape blah blah could show promise, if burning condensed sunlight is still an option that is   

[jack be nimble]

Nickel air batteries are coming. We will be electric before long

[MDK87]

Jack as far as I'm aware they have already set 42V as the standard operating voltage for next generation vehicles. This would help a lot with the energy demand of such a system, and remains under the 50V shock hazard guideline. Just don't jump start in the rain. Haha

 

Ben there is so much more than frictional/parasitic power that could be gained. 

I thought about the interference issue also and in my head, non-interference engines are a step back when it comes to pumping losses. 

If you could isolate the piston in the bore you could receive a collision signal at which point the coil could be released, I'm not sure if Lenz's law would pose a problem here though.. Now I'm getting sidetracked. 

 

I wonder if Mercedes published any info about their system.

[MDK87]

Actually maybe you couldn't, the hydrodynamic bearings might prove a connectivity issue.

[bj]

The weight of the valve and hence the amount of power/energy to accelerate and decelerate.

 

Compare it to a injector which have been around for a long time and pretty well optimized.

Basically the same concept but with a much lighter valve and they only manage 1mS (approx) open/close times.

now you have 10-100x the weight hanging off the solenoid which would make for a very slow valve.

 

So you could try just run more current through your solenoid...

but for your typical peak/hold injector of 4 amps you would be somewhere around the 40-400 amps PER valve.

 

Then you have the problem of slowing the valve, as fuel injects have a liquid between the seat and valve they can pretty much just hit them together as it acts as a lubricant/buffer(my thoughts)

Try that on a head and you'll damage the valve and/or seat.

 

then you have the problem of distance.....................................

injector only has to move in the order of 1mm but your intake/exhaust will need to move more like 10x that distance.

solenoid force drops off exponentially with distance sooooo.

yet another factor complicating matters

 

Just off the top of my head but probably many more this to overcome.

 

Nothing is impossible

[dakiller]

Very interesting

[Geo&Kez]

A direct injection high compression engine which could be configured to run as a 2 stroke (for power) and 4 stroke (economy) with solenoid controlled adjustable port sizes and location (via a sliding collar around the cylinder which

would obviously eliminate valve train completely) and also timing events, advanced swirl design piston/head shape blah blah could show promise, if burning condensed sunlight is still an option that is

Que the Orbital engine company. Now making high efficiency motors for drones for the US military out of a shed in Wangara. Why did development stop for the auto industry? Aust gov to scared to back a good idea?

Rotating valves work but keeping them sealed is the hard part. Didn't Ducati have a production bike with a setup like this?

[jack be nimble]

Dunstill had one for the old grey holden motor. Rotary valve head that is.

[Geo&Kez]

As opposed to the desmo valve setup. Ducati played with this too.



Mitsubishi could even go two for one and make them balance shafts as well!

The Koenigsegg stuff looks the goods, but fuck, imagine looking for that air leak....... 'Just put it in the pool.... We'll do a bubble test...'

[jack be nimble]

Ducati just had a means to pull the valves shut as well as open.
Yea, keonigsegg has it together. No 1/4 times for the old saab tho

[evo-gsr]

I think Koeniggsegg has a lot more technical ideas up their sleeve that they are yet to reveal.

[jack be nimble]

Air valves, 3d printers with moving parts printed inside, 3d custom carbon fibre printing, air tank regenerative boost.
What else is there?.......benzo??

[evo-gsr]

You forgot to mention the car from Back To The Future !

[MDK87]

Fuarrrk Koenigsegg, they do some innovative shit! That video is awesome.

I guess for the most part, the pneumatic system they have would be almost as good as a fully electronic one. I just didn't think a pneumatic actuator could be made to function at those speeds.

This technology will seperate the boys from the men when it comes to dyno tuning. Haha

At the end he started speaking of an energy storage system similar to a pneumatic version of Permo-Drive but without the need for additional pumps/motors etc.

It makes perfect sense to complement his pneumatic valvetrain system.

They don't quit thinking do they? Haha love it.

 

LOL George. 

What are those ball valves off? 

I remember seeing somewhere an electromagnetic version of ball valve like this, which would make the valves individual and eliminate the camshaft.

 

Its good to see people trying new things.

Edited by MDK87, 28 November 2014 - 12:00 AM.

[jack be nimble]

Its just old f1 tech. Problem is if you get a flat air tank....
And normal people dont want to wait for air to build up before driving away. I know trucks have to.

Might be ok in a rich guys sports car, but its not like they have any particular mechanical appreciation anyway.

Those rotary valves- the exhausts would get such a hiding

[Geo&Kez]

That was the problem Jack, from what I remember reading, they just couldn't get the thing to seal after a while. Imagine the heat that would be storing itself in those shafts.

There is other shit out there. I've seen diaphragm valve concepts, rotating cylinder concepts, rotating head concepts.......list goes on. I'm figuring I never smoked enough bongs to come up with shit like that.

[evo-gsr]

Or maybe you need more bongs and some better shit to put in it...?

[BMGTZ]

rotax   rotary valve. =awesome till the fucken disc cracks and you melt the piston