pneumatic systems.

[andreasklapp]

wasn't sure where i should really put this, i put it here because i think it would have to be fired electrically. anybody think of a good way to translate the rotation of a crankshaft into an electrical signal you could use to operate pneumatic cylinders in place of a camshaft? i know it sounds crazy, but bear with me (or don't, i don't really care). it seems like there is a lot going on with the design of the valvetrain right now, i've been looking around a little bit lately and have found spherical rotary valves, springless valves, and pneumatic vale springs. i hear that bmw is trying to come up with a camless hydraulic valve system. now i'm not really educated in any way, i'm not an engineer, but it seems like if you could program a circuit to open and close a pneumatic cylinder directly inline with a valve stem at the right degree of rotation in just the right length (or depth). that would be the setup. the mechanics of it seem really simple. i'm sure there is a lot i'm missing that would have to be de-bugged. anybody got any ideas? the only things i can think of are a crank trigger running to some kind of modified distributor to send a signal to a solenoid to open and close a doubleacting cylinder. or a computer program to do the same thing. the computer would probably make more sense, be a little less complex in the end, be programmable so that you could run different "cams" for different settings (a drag setup, an efficiency setup,etc.) it seems like you would be able to vary the lift and duration according to rpm with it as well. i'll probably never be able to put together a model of it as i am flat broke most of the time, but just throwing it out there.

 

[RPM]

The fuel injectors in the newer diesels work kinda like that but with hydraulics and electronics. They use a hi pressure oil pump and a computer full of electronics to make it all work.

I read an article years ago in one of the trade magazines about electronic valve control. I don't remember which company was working on it. Anyway very similar to what you describe. Nice smooth idle, get on the gas and it changes lift and duration to really up the power. Then get up to highway speeds and it tamed down again. All done with a computer.

 

[Shea Laking]

Honda has had VTEC and iVTEC for years now; simply electronically controlled valve timing advance. Run by the ECM, of course.

Actually, many if not most manufacturers have some form of variable valve timing on at least some models, including the "domestics."

It seems like a good idea on the surface and works pretty well in practical, day-to-day use (my Odyssey has VTEC and I really like it ). Keep in mind, you most likely ever be able to create a car that idles like a 50 MPG econobox and revs like a 4 second Top Fueller...

This may not even be what you're asking, anyway...As far as control and adjustment or operation, everything nowadays is computerized. You would use a crank trigger wheel and sensor to indicate cylinder position to the computer and one or more cam position sensors to indicate position of the cam or cams, again to the computer.

Pneumatic actuators sound interesting...might just have to "Gooogle" that later, when I've got some free time.

Hope I didn't muddy up your thought process too much....[S

Regards,
Shea

 

[andreasklapp]

ah, it's one of those things i probably won't ever even get to start on. i've heard a little about the vtec, but i don't really know anything about it. i'm thinking more along the lines of removing the cam altogether and controlling the whole thing with a computer so they would act one way at low rpm and another at high rpm, and possibly do away with some of the heat and drag of a camshaft. i can basically see the whole thing, and essentially how it COULD work, but i'm no computer whiz, and to broke to even think about trying to buy a bunch of crazy parts and a computer (and a little motor to play with). all of them also being things that would almost immediately be destroyed, at least five times over before i had the most basic little bugs worked out. but it's interesting to think about.

 

[440Clark]

I think the biggest issue you are looking at is a Pnuematic controlled cylinder cannot act fast enough to open and close the port window at any kind of real rpm. Using a rotating disc like the snowmobiles use might be a viable option.