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Engineering/Technical Ask technical questions about cars. Do you know how a car engine works? |
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03-23-2004, 12:30 PM | #1 | |
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alternative to cams and valves ??
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 |
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03-23-2004, 05:46 PM | #2 | |
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Re: alternative to cams and valves ??
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. |
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03-24-2004, 01:32 AM | #3 | |
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Re: alternative to cams and valves ??
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
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03-24-2004, 09:50 AM | #4 | |
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Re: alternative to cams and valves ??
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? |
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03-24-2004, 03:41 PM | #5 | |
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Re: alternative to cams and valves ??
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.
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03-24-2004, 08:04 PM | #6 | |
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Re: alternative to cams and valves ??
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.
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03-27-2004, 01:28 PM | #7 | |
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Re: Re: alternative to cams and valves ??
[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. |
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03-27-2004, 03:25 PM | #8 | |
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so there is no engine yet where there is ports spinning around where the valves and cams usualy go?
like that >>> lol (but not that small) |
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03-27-2004, 04:09 PM | #9 | |
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Re: alternative to cams and valves ??
There is such a thing as a sleeve valve engine that used this concept.......in the 1920's.
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03-27-2004, 07:07 PM | #10 | |
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Re: alternative to cams and valves ??
oh i think i am going to cry.
sum geekn F****nicked my idea!! AGAIN!!! A R G H 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 Last edited by matt horton; 03-28-2004 at 02:49 AM. |
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03-28-2004, 12:19 PM | #11 | ||
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Re: Re: alternative to cams and valves ??
Quote:
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. |
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03-28-2004, 05:47 PM | #12 | ||
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Re: Re: alternative to cams and valves ??
Quote:
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.
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03-30-2004, 03:49 PM | #13 | |
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Re: alternative to cams and valves ??
could i put the plug in the top of the piston?
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03-30-2004, 03:53 PM | #14 | |||
Pretty much amazing
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Re: alternative to cams and valves ??
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.
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ec437 on grammar; Quote:
Quote:
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03-30-2004, 10:12 PM | #15 | |
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Re: alternative to cams and valves ??
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
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