02GF74
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| posted on 20/9/06 at 08:17 AM |
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engine valve technologoy
are the engines using non cam activated valves e.g. electromagnetically operated valves?
if noit, then why not?
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nick205
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| posted on 20/9/06 at 08:26 AM |
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I seem to remember reading about BMW doing some development with different methods of valve actuation and possibly Honda too. I'm not aware of
any production engines with alternative technology yet though.
Makes perfect sesne to me provided the reliability, weight and performance criteris can be met. It would free engine designers to look at different
shapes and positions for valves and would presumably allow infinitely variable valve timing over the rev range - like vtec/vvc, but better.
A lnog time before it would reach the likes of us though 
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matt_claydon
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| posted on 20/9/06 at 08:31 AM |
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A friend of mine did a project on this at uni - they got a single cylinder bike engine running with solenoid operated valves. Don't know if
it's been looked at by any of the big manufacturers - I'd be very surprised if they aren't working on it though.
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nib1980
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| posted on 20/9/06 at 08:34 AM |
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Most of the technologies require 24volt sytems, and most OEMs like mine won't swap over to the higher voltage.
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02GF74
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| posted on 20/9/06 at 08:48 AM |
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quote:
Originally posted by nib1980
Most of the technologies require 24volt sytems, and most OEMs like mine won't swap over to the higher voltage.
that' interesting .... I reads a few years back that car electric will be standardised to be 48 V - reson being with all the electrical gubbins
fitted, the weight of the loom is quite significant; higher voltage means thinner wires.
It would be interesting project to diy proviing there was some fialsfe to prevent valve hitting piston head.
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martyn_16v
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| posted on 20/9/06 at 08:53 AM |
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I'd expect to see it in F1 before it got anywhere else. The problem is developing solenoids that are able to actuate against the high cylinder
pressures, cycle at the required speed, and still maintain accurate valve position. It'd take some seriously powerful magnets to provide all
that, I don't know if the materials are available yet to do so.
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clockwork
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| posted on 20/9/06 at 09:24 AM |
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What nib said.
Valeo is pioneering such a system.
One of the other benefits that is not widely publicised is the ability to utilise the engine as a braking mechanism with electromagnetic valves this
becomes easy.
Brake dust is actually very bad for your health and an environmental problem.
EDITED: I would be surprised to see it on F1 cars due to the weight, and speed implications. 19000+ rpm is a lot more opening and closing per minute
than 6000. You may be right though, it would certainly prove its reliability if it worked in that environment.
[Edited on 20/9/06 by clockwork]
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twybrow
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| posted on 20/9/06 at 09:34 AM |
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The current required to operate them , and the losses experienced are huge. Several companies have played with the idea over the years, but at present
the technology is not suffiently developed.
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02GF74
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| posted on 20/9/06 at 10:02 AM |
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quote:
Originally posted by clockwork
EDITED: I would be surprised to see it on F1 cars due to the weight, and speed implications. 19000+ rpm is a lot more opening and closing per minute
than 6000. You may be right though, it would certainly prove its reliability if it worked in that environment.
[Edited on 20/9/06 by clockwork]
Pretty sure I heard the renaulr had them in an F1 car but they were pneumatically operated.
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UncleFista
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| posted on 20/9/06 at 10:43 AM |
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quote:
Originally posted by 02GF74
Pretty sure I heard the renaulr had them in an F1 car but they were pneumatically operated.
Peugeot were running pneumatic valvegear in F1 over a decade ago, ISTR it wasn't overly reliable 
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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Peteff
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| posted on 20/9/06 at 10:50 AM |
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Ferrari used it and their reliability isn't an issue
2001 Ferrari V10 with pneumatic valve gear
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Coose
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| posted on 20/9/06 at 10:51 AM |
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The Suzuki MotoGP bikes have pneumatically operated valves. Not sure how they work though.
Ducati have sued desmodromic valves for lots of years - two followers, where one opens the valve and the other closes it. It reduces valve bounce to
an absolute minimum!
I can't understand why rotary valve development seems to have died a death!?!
Spin 'er off Well...
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NS Dev
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| posted on 20/9/06 at 11:57 AM |
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arggghhhh!!!
Everybody talks about "pneumatically operated valves"
they are NOT pneumatically operated!!
They have pneumatic valve SPRINGS!!!!
This is common to most top level competition engines now, and in VERY basic terms an ECU controls valve spring pressure, minimising it at lower speeds
to reduce losses and maximising it at high speeds to prevent bounce. Also removes the problem of natural frequencies.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Richard Quinn
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| posted on 20/9/06 at 12:07 PM |
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Didn't the F1 engines still have cams to open the valves? I thought that they were just closed by pneumatics instead of springs
Sorry, added my reply whilst still on page one of the thread! Still, nice to know that I was correct
[Edited on 20/9/06 by Richard Quinn]
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NS Dev
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| posted on 20/9/06 at 12:10 PM |
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yep, exactly correct!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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clockwork
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| posted on 20/9/06 at 12:33 PM |
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Sorry are we talking about pneumatic or electromagnetic?
If electromagnetic, I'm pretty sure nobody is using them. Though a link would prove me wrong.
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Catpuss
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| posted on 20/9/06 at 06:08 PM |
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From what I understand F1 cars use nitrogen instead of the springs. The valves are cam opened as normal, but use a small piston on the follower for
pressurisation as the cam goes past the pressure is released and the air pushes the valve shut acting like a spring. As there is not a perfect seal
there is a nitrogen remote cylinder to keep the pressure up.
I think they have some sort of spring/friction damping still to damp the opening and avoid the valve decellerating too fast when it reaches fully
open.
Here you go :
http://scarbsf1.com/valves.html
Suzuki also experiemented with rotary valves in their bikes in the 60s but I think that was for 2 strokes
I think also Lotus have been looking at solenoid based valves from some time too.
On top of that Mazda have at least one fruity engine with no inlet valves relying on the turbo pressure to keep the gasses escaping.
[Edited on 20/9/06 by Catpuss]
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gazza285
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| posted on 20/9/06 at 07:40 PM |
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quote:
Originally posted by Coose
I can't understand why rotary valve development seems to have died a death!?!
Because the cylinder pressures are acting on the rotating valve as it turns. When the mixture is ignited the pressures are huge, and you have still
got a rotating valve in the chamber, the pressure pushes on the valve which makes the mechanical losses high. Sealing the ports is also a major
problem as the seals see both high pressures and low pressure vacuums, making the engines inefficient as well.
Guess who worked on a few rotary valve engine prototypes for the Shell Ecomarathon a few years back. Lots of either inefficient running engines, or
fairly efficient engine that siezed within minutes. Non of the rotary valve engines came close either way to a poppet valve engine on the dyno for
power or efficiency. We binned the lot.
DO NOT PUT ON KNOB OR BOLLOCKS!
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