Alternative to camshaft

[grgrgray]

Recent thread on here got me thinking, does anyone know, has any manufacturer tried using electrical actuation to open and close inlet and exhaust valves on an internal combustion engine either Diesel or Petrol.

This system would allow the ecu to control valve timing, lift and duration based on the engine map and give much tighter control of the burn cycle.

Replacing the camshaft with this system would reduce internal friction and internal engine loss giving much more efficient and powerful engines.

Anyway, any engine designer out there.

[cuprabob]

Don't F1 engines not use such a system?

[Ray Luxury-Yacht]

F1 and MOTO GP bikes have been using pneumatic valves for years, operated by controlled compressed air.

I think the Fiat MultiAir engine is the first incarnation of a similar, more basic system being used in a road car.

[grgrgray]

Just googled it and most F1 engines use camless pneumatic systems by the look of it. If formula 1 use it, it will come to road cars eventualy

[Toyless]

grgrgray said:

Just googled it and most F1 engines use camless pneumatic systems by the look of it. If formula 1 use it, it will come to road cars eventualy

I think raod cars will end up with hydraulic valves over pneumatic though.

[Pigeon]

Oh yes, this idea has been had before. Not aware of any production engines using it but it's certainly being researched.

Not really my favourite idea as far as the "electrical" part of it goes... because it requires a large number of fking massive high-power heavy-duty solenoids operating in an environment which is distinctly hostile to electrical gear, which to me says expense and unreliability both in large measure.

I'd prefer to do it by using miniature hydraulic rams as valve actuators - which would be barely more complicated devices than commonplace hydraulic tappets - controlled by a rotary valve which would simply be a rotating shaft with suitably shaped grooves in it surrounded by a sleeve with holes drilled in it which can be moved to change the relationship between the holes and the grooves, a bit like the fuel metering method of a traditional diesel injection pump - again a simple and reliable device. This is how I want to operate the valves on my two-stroke diesel project.

[DrTre]

grgrgray said:

Just googled it and most F1 engines use camless pneumatic systems by the look of it. If formula 1 use it, it will come to road cars eventualy

They're not camless, they use pneumatics to close the valve positively to prevent valve bounce.
Actuation is still mechanical, with no VVT.

[grgrgray]

Do two strokes have valves? thought they used the vacuum created by the piston to push fuel/air into the combustion chamber and the exhaust gasses out.

Anyway, I think the ECU would be best programmed to open and close the valves (4 stroke) in the same way it controls the fuel/air mixture and injection. It would mean the perfect lift and dwell could be programmed through the rev range based on engine load.

[grgrgray]

DrTre said:

They're not camless, they use pneumatics to close the valve positively to prevent valve bounce.
Actuation is still mechanical, with no VVT.

The Renault system is camless.

http://scarbsf1.com/valves.html

Edit - Not been tried in a race car yet though

Edited by grgrgray on Sunday 13th February 19:59

[DrTre]

grgrgray said:

The Renault system is camless.

http://scarbsf1.com/valves.html

Edit - Not been tried in a race car yet though

Edited by grgrgray on Sunday 13th February 19:59

Yes, hence F1 engines aren't camless.

ETA when I say "yes" I mean, I know they have developed one previously however it's not what they run, and no F1 engines do. There's a common misconception that "pneumatic valves" means "computer controlled" like solenoids.

Edited by DrTre on Sunday 13th February 20:05

[thinfourth2]

grgrgray said:

Just googled it and most F1 engines use camless pneumatic systems by the look of it. If formula 1 use it, it will come to road cars eventualy

I always thought that F1 engines just rev way too high for it to work as there is no valve that can operate quickly enough to open and close 158 times a second and have meaningful control.

Pneumatic valve springs have been around for ages but still use a camshaft.

The marine world has camshaftless engines for quite a while

Google the sulzer RTA-flex engines

[mattmurdock]

grgrgray said:

The Renault system is camless.

http://scarbsf1.com/valves.html

Nope, as per your linky, this system was supposedly tested, but has never raced or been tested in a road car application.

Edit: Doh, beaten to it.

[Ian974]

I was thinking about something similar and ended up wondering if it would be possible to usethe camshaft as a 'rotary valve' or something, using the lobes to block the inlets and outlets rather than pushing valves etc.
I imagine that it would need to be extremely precise and would possibly really stress the camshafts, have fairly large issues with regards to flow, but it was just an idea. If you could get it working well having two moving parts in the cylinder head would be preferable to umpteen valves, springs and so on...
Ultimately if individual pneumatic/hydraulic valve actuation grows further it'd be completely irrelevant anyway.

[thewhooshparrot]

is this not similar to the system used on the ducati race bikes,desmosedici,albeit controlled hydraulically,but still with no camshaft,and the road going desmo i believe uses the same tech?
also,isnt the new fiat multiair of a similar design?using the valves to control throttle?

[DrTre]

thewhooshparrot said:

is this not similar to the system used on the ducati race bikes,desmosedici,albeit controlled hydraulically,but still with no camshaft,and the road going desmo i believe uses the same tech?

Don't think the desmosedicis use anything other than straightforward Desmodromic valving which is camshaft operated.

[crofty1984]

Look up Lotus's Active Valve Train (AVT) System. It uses hydraulics. Theoretically you could have a different lift and duration on every revolution of the engine.

[thinfourth2]

Ian974 said:

I was thinking about something similar and ended up wondering if it would be possible to usethe camshaft as a 'rotary valve' or something, using the lobes to block the inlets and outlets rather than pushing valves etc.
I imagine that it would need to be extremely precise and would possibly really stress the camshafts, have fairly large issues with regards to flow, but it was just an idea. If you could get it working well having two moving parts in the cylinder head would be preferable to umpteen valves, springs and so on...
Ultimately if individual pneumatic/hydraulic valve actuation grows further it'd be completely irrelevant anyway.

Huge sealing issues with rotary valves

[Petrolhead_Rich]

Hmm, electronic bits to open the valves, that is going to give a nice repair bill at 80-100,000miles isn't it?

[grgrgray]

Petrolhead_Rich said:

Hmm, electronic bits to open the valves, that is going to give a nice repair bill at 80-100,000miles isn't it?

It would give better longevity, no metal to metal contact you get with a camshaft. Sure the electronics would need development but eventualy would be as usual as coil packs are currently.

[Life Saab Itch]

thinfourth2 said:

Huge sealing issues with rotary valves

Roland Cross solved that problem in 1938.

Shame no-one else picked up on the idea.