I've been thinking....

[nejcdolinsek]

I hope there are a few engineers on JW that can help me out on this idea I have:

Why don't they make engines that don't have valves, but instead have shutters that open and close (just like in a camera). They would be opened and closed using magnets.

The good thing about such a system would be the reduced weight (no camshaft is required, etc., etc.), very small reciprocating masses, and the much faster rate at which they can open/close...

It this any good??

[TransAm]

I'm not a true engineer, so no doubt I might be wrong, but...

Two stroke engines don't have camshafts and valve assemblies, as such. I think they are more 'efficient' than 4 stroke cycle engines. The 2 stroke motors can rev very high, but then saying that so can 4 stroke bike engines, 250cc road bikes redline at 18000 rpm.

There is also the wankel (ho ho ho) engine, which I believe does not have a conventional valvetrain.

Good topic to discuss though, and I hope those more knowledgeable than I can contribute... 8)

[topgeartom]

yeah - its a nice idea you have nejcdolinsek, but i have no idea if it holds any water.

The trouble with these sort of things is that they seem a bit too obvious, and there is usually a really straight-forward reason why they arent used.

As TransAm said - lets have a real engineer shed some light on the subject

[antonioledesma]

maybe an useless engineer just like me

I'll just try to answer the magnetic thing...
well, surely as you know, in F1, the engines have pneumatic valves. This technology allows the engine to run faster.
also, for you to have more hp, the engine must run faster, and right now one of the engine parts that limits the development are...springs.
those helicoidal things have a natural limit, so for you to have more speed in the opening and closing of the valves, you need more rigid springs
back with the magnetic bussiness... the idea of having magnetic valves has been around for some years, but the technology and development of magnetic circuits hasn't been the optimum. Maybe you could have a very simple valve system, but it would weigh more than a traditional system.

I do think that in some years magnetic valves, etc. will be around, but won't be as efficient as a pneumatic or traditional system

at this moment, I like more a spherical rotary valve system just like this:
http://www.coatesengine.com/index.html

[antonioledesma]

^^ for those who don't have an idea of how is a neumatic system... remember your visits to your dentist.
why the hell they use compressed air? why not an electric motor to move that damn thing... the "drill" (sorry, I don't know the name of that thing in english)
some drills rotate at 100,000 rpm, almost no mechanical system can withstand those speeds

[TransAm]

/\ I learn something new everyday! By the way, you are quite right, the word is 'drill' in English.

[antonioledesma]

Originally Posted by nejcdolinsek Why don't they make engines that don't have valves, but instead have shutters that open and close (just like in a camera). They would be opened and closed using magnets.

now that I'm not doing homework or studying... I've some free time

btw... with the shutter, could be a great idea, but you could add too many moving parts. More than the regular system

see this image, it's from a normal, typical camera with a... typicl shutter.
Of course exist more kinds of shutters, but the idea is the same.
Now become an engineer, and develop those valves... you could win some money for each valve

[mindgam3]

magnets weigh a lot.... the more powerful you want your magnet, the larger it has to be (or more current has to flow through, which is limited in cars)

which was the main problem BOSE have been having with their new magnet based suspension system that can oscillate far quicker than conventional srpings but just weighs too much and is likely to be used only on luxury limo's etc when it finally is released - not performance cars

[RC45]

2 stroke style reed valve and disc valves are probably "too old tech" for the "new tech" generation.. -- just like our push rods..

[FoxFour]

The concept of using solenoids instead of valves, has been tested and the concept does show some promise. However, the current 12 volt system in most cars have been shown to be inadequate, what with the other current loads that the rest of a potential car's system would consume electricity- wise. The next generation of cars that will eventually sport a 24 or 48 volt system will/would better be able to handle the current loads.

http://rbowes1.11net.com/dbowes/index.htm
http://www.machinedesign.com/ASP/str...tedArticle.asp
http://www.auto21.ca/powertrains_5controls_e.html
http://www.autospeed.com/cms/article.html?&A=0910

[FordGTGuy]

one reason is that valve fave to take imense heat and the shutter would have to be moddified for the engine timing system. If you were to use shutters the camshaft would almost be useless.it would take down the wieght of the engine but the reliability would also go down. because the shutters would have to run on electronics that can easily break.

[FoxFour]

Eventually I believe that the shutter would wear down. Can you imagine how fast this shutter would have to open and close as well as being in the direct blast of the igniting mixture inside the combustion chamber.

[TransAm]

Originally Posted by RC45 2 stroke style reed valve and disc valves are probably "too old tech" for the "new tech" generation.. -- just like our push rods..

LOL I hear ya, RC

[ZfrkS62]

some years ago there was actually a new type of valvetrain invented the increased power and efficiency. It was actually a camless, valveless system.

it was timed the same way as a camshaft, but used a much different style cylinder head. instead of using lobes, there were holes drilled through each "camshaft" where the intake manifold lined up with the combustion chamber, and combustion chamber to exhaust manifold.

when the intake port lined up, the piston was approaching its intake stroke, and would draw the air/fuel mixture in, and it would seal off for the combustion process. Then the exhaust side would open up for the expelling of the gasses.

This style opens up the possibility for higher RPMs due to the lack of valve springs.
Less moving parts, less parts to break

My apologies for not being able to recall the name of the system as it was about 3 years ago that i saw the video. I want to say it started with a W but i'm not sure. i would have to get a hold of one of my old instructors from school to recall the name ops:

[Wutputt]

Originally Posted by nejcdolinsek Why don't they make engines that don't have valves, but instead have shutters that open and close (just like in a camera). They would be opened and closed using magnets.

1) Current systems with valves work very good. Introducing a total new system would cost a lot. A more natural step is abandoning the camshaft and actuating the valves magnetically, like in antonioledesma's and FoxFour's post.


2) The shutter and its actuating mechanism has to be strong enough to withstand thermal load and the combustion pressure. This would mean those shutters has to be tick (or real expensive material, but that’s no real option for road cars), which adds weight and raises the inertia of the actuating mechanism, which could give problems at high rpms. A few years ago research in F1 concerning magnetic actuation of the valves has led to the same problem: the inertia of the magnetic actuation was to high to work accurate enough at high rpm's. For road engines the revs are much lower, but if the actuating mechanism and shutters add to much inertia it could also give problems for road engines.


3) How do you seal off properly?


4) Like Ronin said, this system is a bit more complex as the current system, something you don't want due to reliability issues and high revving situations.