alternative to cams and valves ??


matt horton
03-23-2004, 01:30 PM
hi i am 14 and am new to these forums but have bean reading them for some time.

i have have a really good idea for an alternative to cams and valves but want to know it if has already been invented. to help me with this could you list all (if any) alternative cam-valve systems you know off.

as you can tell i am not really willing to share my idea, but if it has already been invented i will tell you what is was.

please help

thanks

SaabJohan
03-23-2004, 06:46 PM
There are several types of ports that have been used in internal combustion engines, the most common (and almost the only widely used type) is the poppet valve. These can be opened and closed in several ways, by camshafts, hydraulic actuation, pneumatic actuation and electromagnetic actuation. The reason for that they are so common is that the combustion pressure press down the valve into the seat and this makes the seal very good. The high rpm of most small engines have make it impossible to use other types than camshafts for actuation since they will not respond fast enough, with enough precision or the system consumes too much power or have too high weight.

Another type that's used is ports in the cylinderwalls, some engines have even used rotating cylinderwalls which opens and closes the ports. Combos of ports and poppet valves are also used.

Another type is the rotary type valve, works like a barrel-type throttle. The sealing is however a large problem.

matt horton
03-24-2004, 02:32 AM
oh yer, so thats y cams are always used, cus the pressure of the explosion pushes back on them to seal them v tightly. i am so dumb, neva thought of that. lol :D

matt horton
03-24-2004, 10:50 AM
My design sounds a bit like the throttle thing but without butterflys?? (is that the right word). Today at school I thought of a way to get around the seal problem.

The real problem is though where to put the plug, could you have some fancy contacts through the crank and in to the piston and put the plug in the piston?

buymeabmwm3
03-24-2004, 04:41 PM
for some nifty ideas, check out BMW's Valvetronic engines. They get rid of the throttle altogether, and use the valves themselves to control engine speed. Also, new engines are coming out that use electric solenoids to operate the valves, eliminating the need for camshafts. this also allows infinitely variable valve timing.

Steel
03-24-2004, 09:04 PM
Ahh.. i gotta do it...

ROTARIES! haha. Nothing like a self-valving engine eh?

But back to the topic; camshafts are really hard to beat these day's especially with computer controlled valve timing and lift systems combined with compter controlled ignition timing systems. And compared to those hydraulic and solenoid type's, camshafts are cheap to replace.

MagicRat
03-27-2004, 02:28 PM
[QUOTE=Steel]Ahh.. i gotta do it...

ROTARIES! haha. Nothing like a self-valving engine eh?

QUOTE]

Two stroke engines come to mind as well, where the piston movement covers and uncovers ports in the cylinder walls.

Two stroke diesels apply as well, where a Roots type blower is used. A terrific, efficient light weight design, just a little heavy on emissions.

matt horton
03-27-2004, 04:25 PM
so there is no engine yet where there is ports spinning around where the valves and cams usualy go?

like that >>> :rofl: lol (but not that small)

MagicRat
03-27-2004, 05:09 PM
There is such a thing as a sleeve valve engine that used this concept.......in the 1920's.

matt horton
03-27-2004, 08:07 PM
oh i think i am going to cry. :crying:

sum geekn F****nicked my idea!! AGAIN!!! A R G H
:banghead:

all i was doing was looking for these sleeve valve thingies and this came up -

just look, just look at this sh**!!

http://www.coatesengine.com/

stupid isnt it, i allways have these good ideas and some1 has allready thought of it and gon and made there 1,000,000s. I hate life :angryfire

SaabJohan
03-28-2004, 01:19 PM
for some nifty ideas, check out BMW's Valvetronic engines. They get rid of the throttle altogether, and use the valves themselves to control engine speed. Also, new engines are coming out that use electric solenoids to operate the valves, eliminating the need for camshafts. this also allows infinitely variable valve timing.
Those engines are yet not used in any high speed engines, among others they are said to have a lot of friction at high engine speeds.

Electric solenoids does only work at low speeds, they are heavy and require quite some electric power while they aren't that accurate. I find it likely that we will se good hydraulic or pneumatic systems before systems using solenoids.

beef_bourito
03-28-2004, 06:47 PM
oh i think i am going to cry. :crying:

sum geekn F****nicked my idea!! AGAIN!!! A R G H
:banghead:

all i was doing was looking for these sleeve valve thingies and this came up -

just look, just look at this sh**!!

http://www.coatesengine.com/

stupid isnt it, i allways have these good ideas and some1 has allready thought of it and gon and made there 1,000,000s. I hate life :angryfire

i was thinking of doing that exact thing for fun on a small car for fun (and extra marks in physics) and since i probably have more resources than you i probably would have beat you to it.
i was (and still am) thinking of making a small car with something along the same lines as the coats guy, using a different ignition system than the modern engine and using pure oxygen and methane or another simple gaseous carburant that can be compressed.
anyway, if you start on the project now, you can most likely get alot of extra marks for physics or if you're thinking of going into mechanical or automotive etc engineering, do this and its easy marks. good luck if you want to try and actually persue your idea.

matt horton
03-30-2004, 04:49 PM
could i put the plug in the top of the piston?

Porsche
03-30-2004, 04:53 PM
lol

Even if coates didn't think of it, I would have beaten you to make the million's. I posted an exact thread like this a couple years ago. Ironically came up with the idea at school too, even drew some poor technical drawings.

Ironman_375
03-30-2004, 11:12 PM
I also have a great invention!!!

It's a frame that has two wheels and the back wheel has a chain coming to 2 foot hold's that i like to call "PEDALS" I think i'll call it the...biIRONMAN375cycle!!!


Yeah i know i'm a smart ass
:flipa: :thefinger

SaabJohan
03-31-2004, 08:22 AM
could i put the plug in the top of the piston?
It's possible. It have also been done, Saab have for example an experiment engine with this. The positive electrod is placed in the head and the negative on the piston crown and the spark jumps between the head and the piston.

Placing both electrods on the piston will be more difficult and I wouldn't recommend that (imagine replacing the plugs).

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