So I got to talking with one of my friends. We were discussing VVT, V-tec, etc and it kinda struck me why dont we just eliminate the cam itself and use nothing but solenoids to time the valves?
This would allow for better fuel mileage under cruising (hold the valves shut longer and advance the spark.) Higher timing better fuel burn and better mileage and then under a PE sort of situation or in boost or whatever you could use different timing profiles to allow for maximum power at certain RPM ranges. It would also allow for smaller engine profiles as we wouldnt have to have a wide head for two cams.
It just seems so perfect and I dont understand why more hasnt been done with it in the automotive design community. The only issue we could really see is a solenoid failure being catastrophic.
So how does everyone else feel? Am I way off base?
Edited 1 time(s). Last edited Monday, January 03, 2011 4:47 PM
TheSundownFire (GME Chat) wrote:... a solenoid failure being catastrophic....
Far from being hugely knowlegable about the topic, but I would think this would be the reason.
Solenoids are finicky when they aren't being operated at 1000+ rpms and surrounded by intense heat
Buddy Club Ecotec Cavalier
* More to come *
Solenoids are used in V-TEC and VVT? They work fine in the temps and RPMs way over 1k as far as I know.
The concept's been attempted, and is still in development, but the physics of operating a solenoid this large at the frequencies required are still confounding engineers. Durability continues to elude them.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
I could imagine. I wish I had the skill, time, and money to work on a project like this. Id imagine you could reduce the stroke and wear on the solenoid but using a rocker type design. Even something like a 10:1 ratio would make the movement of the solenoid almost nothing. Think you doing .400 lift. The solenoid would only have to move .040 inches. Obviously the solenoids would have to be a regularly maintenanced item.
I see a Senior Capstone project for myself in a few years.
If I remember BMW as of late was putting a bunch of money into this...
Neat idea but you cant beat the simplicity and reliability of a camshaft.
Ive been reading a bit and everyone claims to be "developing it" but so far no ones put up the goods at all. I read that a Mercedes in 2007 was supposed to be released with electronic valve timing but nothing such happened.
Maybe its a useless endeavor due to the popularity of hybrids and electric vehicles. But I dont see any reason why its a less valid idea than a car with no performance ability and amazing gas mileage. Hell if I could get a Suburban that would do 40 mpg I would be much happier than driving a Prius that drives like a go cart and gets 80 mpg. Take the CRZ for example. Sport Hybrid. It makes around 150 hp and still only manages high 30s low 40s with a continuously variable transmission. I just have such a bone to pick with hybrids in general I guess.
Bill Hahn Jr. wrote:The concept's been attempted, and is still in development, but the physics of operating a solenoid this large at the frequencies required are still confounding engineers. Durability continues to elude them.
Bill nailed it.
I'm willing to bet by the time engineers figure out how to design a solenoid that will actuate a valve (either directly or via a rocker setup) the internal combustion engine will be a relic.
not to mention if you have a charging system that is malfunctioning (bad alternator, battery, whatever), and one of your valve-solenoids doesn't fire correctly or freezes open it could turn into a situation akin to a broken timing belt/ chain... meaning major engine damage from something as stupid as alternator failure.
TheSundownFire (GME Chat) wrote:I just have such a bone to pick with hybrids in general I guess.
Me too.
I've read about this in concept discussions before, but I have to agree with the above post. I think by the time the technology arrives to make such a setup work reliably, the internal combustion engine we know and love will be long gone.
"In Oldskool we trust"
Theres no way on earth Id try this on an interference engine. Thats asking for issues. If a valve sticks open its not a huge deal. No compression but nothing terribly destructive. Fix the solenoid and youre golden. A solenoid placed at the top of the head would be easily serviceable. Whats the worst that could happen if a valve sticks closed? A blown head gasket maybe wrecked piston. That would be the only time I could see it being mutually assured destruction and thats only in an engine with 2 valves per cylinder. If we were to use a solenoid for each valve (albeit that would be more complex and failure prone) in a 4 valve per cylinder engine that would half provide a temporary safe mode for the engine until the solenoid could be serviced. A multiple solenoid failure would destroy the engine but statistically the is probably as likely as snapping the timing chain in a car.
Im speaking merely in a simple commuter car engine. Nothing boosted or high comp etc even though a properly setup up program would work well on a boosted car. Really easy to pull timing if knock were to be detected.
Because even with the lightest valves out there, the amount of inertial force that is created when flying open a valve, stopping it, flying it closed, stopping it, and doing the whole cycle over is not currently feasible. There's an incredible amount of force there.
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- Sold my beloved J in April 2010 -
TheSundownFire (GME Chat) wrote:Theres no way on earth Id try this on an interference engine. Thats asking for issues.
The very term "interference engine" could not even be applied to a theoretical engine with infinitely variable valve timing and lift. Valve lift is an integral factor in the interference equation.
TheSundownFire (GME Chat) wrote:Whats the worst that could happen if a valve sticks closed? A blown head gasket maybe wrecked piston.
Not even close. Cylinder deactivation in modern engines are but one example of such closed valves, in which the air in the cylinder simply becomes a spring, adding the energy it takes to compress the air back into the crankshaft with the piston on the way down.
Not to crash the dreams of budding young innovative minds, but the basic rule of thumb applies here: As it's not an original idea, the reason it does not yet exist in a production environment is simply because it is not yet feasible, due to significant remaining challenges. The best minds in autodom have been on this one for a while. Have a seat, grab the popcorn, and give them the benefit of the doubt for being way past simple observations and/or complete misconceptions.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
TheSundownFire (GME Chat) wrote:Solenoids are used in V-TEC and VVT? They work fine in the temps and RPMs way over 1k as far as I know.
They arent moving at those rpms though. With vtech its on at a certain rpm and it stays on then off at a certian rpm they enable and disable the larger 3rd cam lobe so there isnt constant movement in your idea. With the vvt the solenoid pushes a tensioner in and out between the cams to widen on tighten the LSA and change things so that the best Torque/HP. A bit more work than the vtech but still not on and off 1000 times a minute.
Tis not a theoretical engine. F1 cars have been using camless engines for years, though they use a pneumatic system.
You could adapt it to an existing engine therefore using close to stock valve and cam profiles.
But anyways, I was just looking for a sounding board since Ive been bored as hell today. Ill keep my ideas in my head from now on.
Zs Z wrote: TheSundownFire (GME Chat) wrote:Solenoids are used in V-TEC and VVT? They work fine in the temps and RPMs way over 1k as far as I know.
With the vvt the solenoid pushes a tensioner in and out between the cams to widen or tighten the LSA and change things so that the best Torque/HP.
What kind of VVT is this? Curious, as this is not the GM VVT approach.
Zs Z wrote:A bit more work than the vtech but still not on and off 1000 times a minute.
Got that right. Of course, on a modern four-cylinder, we're approaching 4000 times a minute, or 67 times a
second. It's amazing what a modern valve train contends with!
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
Bill Hahn Jr. wrote:Zs Z wrote: TheSundownFire (GME Chat) wrote:Solenoids are used in V-TEC and VVT? They work fine in the temps and RPMs way over 1k as far as I know.
With the vvt the solenoid pushes a tensioner in and out between the cams to widen or tighten the LSA and change things so that the best Torque/HP.
What kind of VVT is this? Curious, as this is not the GM VVT approach.
!
I thought that was how the LE5 worked, someone explained it to me who I thought knew what they were talking about.
TheSundownFire (GME Chat) wrote:Tis not a theoretical engine. F1 cars have been using camless engines for years, though they use a pneumatic system.
Umm...not really. The F1 engines are indeed camshaft equipped, but use pneumatics in lieu of valvesprings, as valvesprings are very short-lived at 18,000 RPM. Yere, there's our friends Inertia and Physics crashing the party again!
The theoretical engine I refer to is the solenoid-operated valve engine you are alluding to.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
Zs Z wrote:Bill Hahn Jr. wrote:Zs Z wrote: TheSundownFire (GME Chat) wrote:Solenoids are used in V-TEC and VVT? They work fine in the temps and RPMs way over 1k as far as I know.
With the vvt the solenoid pushes a tensioner in and out between the cams to widen or tighten the LSA and change things so that the best Torque/HP.
What kind of VVT is this? Curious, as this is not the GM VVT approach.
!
I thought that was how the LE5 worked, someone explained it to me who I thought knew what they were talking about.
GM VVT (such as used in Ecotec, but I believe this approach also applies to their other DOHC's, in this case the High Feature V6 and Atlas series engines) uses hydraulically-actuated cam sprockets that can independently alter intake and exhaust cam timing (also called "phasing") in an advanced or retarded mode. I believe the total range to be about 20 degrees in each direction. PCM-directed solenoids meter oil flow into these hydraulic sprockets to perform the timing changes. The system is completely closed-loop in that each camshaft's position is monitored and compared against crankshaft position to track actual position to target position.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
That is how V-Tec works. Im looking at a nice diagram right now.
TheSundownFire (GME Chat) wrote:That is how V-Tec works. Im looking at a nice diagram right now.
Well, no...not really. While it may use similar hardware (this may be the root of your misconception here), VTEC is primarily associated with changes in valve lift and/or duration. On the other hand, GM VVT changes neither, but advances or retards the camshafts to alter cylinder pressure, exhaust scavenging, and other timing-related features.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
Bill Hahn Jr. wrote:TheSundownFire (GME Chat) wrote:Tis not a theoretical engine. F1 cars have been using camless engines for years, though they use a pneumatic system.
Umm...not really. The F1 engines are indeed camshaft equipped, but use pneumatics in lieu of valvesprings, as valvesprings are very short-lived at 18,000 RPM. Yere, there's our friends Inertia and Physics crashing the party again!
Thats why I hate the internet. I literally just read that in 5 or 6 different places.
Edited 1 time(s). Last edited Monday, January 03, 2011 7:53 PM
Bill Hahn Jr. wrote:TheSundownFire (GME Chat) wrote:That is how V-Tec works. Im looking at a nice diagram right now.
Well, no...not really. While it may use similar hardware (this may be the root of your misconception here), VTEC is primarily associated with changes in valve lift and/or duration. On the other hand, GM VVT changes neither, but advances or retards the camshafts to alter cylinder pressure, exhaust scavenging, and other timing-related features.
If im remembering right the V-tech cams have 2 small lobes and one big lobe between them for each pair of valves. They also use a rocker arm setup like the ecotec except 2 rockers are on the valve springs and a third in between them that is free to float up and down for the large lobe. At the predetermined rpm a solenoid kicks on and through oil pressure pushes a pin out to lock the middle rocker arm to the 2 smaller ones for use with the larger duration and lift. It makes the car more street friendly and top end happy at the same time.
Edited 1 time(s). Last edited Monday, January 03, 2011 8:18 PM
Bill Hahn Jr. wrote:TheSundownFire (GME Chat) wrote:That is how V-Tec works. Im looking at a nice diagram right now.
Well, no...not really. While it may use similar hardware (this may be the root of your misconception here), VTEC is primarily associated with changes in valve lift and/or duration. On the other hand, GM VVT changes neither, but advances or retards the camshafts to alter cylinder pressure, exhaust scavenging, and other timing-related features.
I was agreeing with ZsZ. You posted as I was typing obviously.
