Carbon Fiber Valves?

[chop456]

I just read that 3TEX in N.C. is working on carbon fiber valves for racing engines. Could someone here explain why this would be a measurable advantage? It seems to me that F1 would be the only conceivable application. Wouldn't you have to be turning a ridiculous amount of RPM's for the mass of a valve to make much of a difference? I'm talking the current titanium vs. carbon, not steel vs. carbon. Since springs have already been taken out of the equation, could this be somehow related to Renault's supposed camless engine? If so, then every possible milligram really WOULD be important. Also, how does carbon compare to titanium as far as it's ability to withstand heat? The brake discs are able to survive the heat/friction, but wear and erosion in terms of a valve would obviously be a problem. Sounds like the point of diminishing return to me. Wouldn't they have to be machined, and can that be done? A formed/molded valve wouldn't give you the required tolerances, would it?

So many questions, so little brain.

Oh, and hi everyone. :)

[Shadow]

Hmmm. That made me think of the revolutionary wooden block used in the Grand Prix of Gibralter back in the 1950s - well, at least as described by Peter Ustinov. :D

[Napoleon]

Originally posted by chop456
Wouldn't they have to be machined, and can that be done? A formed/molded valve wouldn't give you the required tolerances, would it?

Hello Chop.

From everything I have read on carbonfiber it seems to me that they could not make the part strong enough. You make 2 good points above but I seem to recall in the last 10 years or so auto manufacturers had gotten to the point that they could cast cranks to tolerance for street cars, but whether the tolerances would be good enough for race cars or carbonfiber is a material that could lend itself to being laid up/molded to tolerance is a different story.

[Foxman]

If they could make the part strong enough could it handle the heat, or would some sort of ceramic coating be required? I'm not sure how the rules apply to ceramics in engines.

Fox

[Turn7]

Some outboard 2-cycle engines have carbon fiber reed valves. Could they possibly be designing something along those lines?

[Napoleon]

what is a reed valve

[RichK]

Nap,

Here's an illustration:

http://www.howstuffworks.com/two-stroke2.htm

[Napoleon]

Rich the reed valve looks like it would be significantly differant in structure and the amount of stress it would undergo.

I like to clarify something in this thread. We have been talking about making things out of carbon fiber but that is not quite correct, the part would be a composite part including carbon fiber. From what I have read about making composite parts in the past, my shoot from the hip feeling is that a part as small as a valve that would be subject to a large amount of stress in something other then purly "in shear" would seem to me to be very difficult to make (and I am not even considering the temp. issue at all).

[Ziggy]

OK, don't hold me feet to the fire on this one. I read this early this morning, but have been to busy to do any homework

What I know so far (practical)

Obviously the dynamic inertia issue gets dealt upon with carbon fiber valves. You could attain much higher rpm's with lightweight valves. Everything associated with the valve train would be lighter, and thus reducing overall friction.

I can really remember who brought it up, but I think the Renault engine in question did not have cam shafts. It open and closed valves with air cylinders (it had valve springs) but I might be full of beans on this one.

Carbon Fiber has come a long way. The heat issue can be engineered into the matrix. I say this because several of the jet engines we build at work have carbon fiber on the exhaust side ... and they run pretty hot. As far as tolerances go, Im sure it can be ground, either OD or ID to a high degree of precision. In the aircraft industry Allison Engine led the way with a process known as "Single Crystal" casting. In this process, and ingot is actual grown through heat into a cavity, producing a completely stress free part. In this case, turbine blades. Even at the 90' angles, the metallurgy is such that there is absolutely no stress.

I would think that a valve might be made up of something ceramic coated. This area of technology has also exploded in the past few years (along with cryogenics, it's not just for Walt Disney anymore)!!

When I get the time, I will dig up the spec.'s on the Renault Motor of the '92 vintage. I think this years Renault F1 charge was also lacking camshafts proper. It was more like an axial trigger.

Ziggy

[Peter Venkman]

1. The nose of the Shuttle is carbon-carbon, and yes, it can stand the heat.


2. The mass of ANY reciprocating part in a race engine is very important. Loads are a function of V^2.

3. Can carbon fiber be machined? It's done every day.
And I'd bet that it would be a homogenious carbon-carbon surface that would be used on the annular valve sealing portion.

I'm waiting for rotary valves to come to F1 engine design.

[Napoleon]

Originally posted by Ziggy
In the aircraft industry Allison Engine led the way with a process known as "Single Crystal" casting.

Interesting - There is a plant in Minirva Ohio, south of Canton that makes those things. Use to be owned by Lorel Defense and Goodyear Areospace (or was it Goodrich) and someone I worked with use to do work with them. Someone I do work for sometimes among other things makes some kind of mold for stuff like that. They use so much wax in the process that when you walk in the plant you would swear you are in a candel factory (beats the dairy I do work for that smells like a sewer).

[pchall]

Didn't Polimotor try this unsuccessfully in the 80s?

As for reed valves -- anybody who had a Cox .049 with a rear intake as a kid had a reed valve two stroke. It was that nice little cruciform bit of metal held in with a spring clip in the backplate mount or the tank mount. As a valve it works with the variations in crankcase pressure, flexing just enough to pass the fuel/air mixture through on the up stroke as the case pressure drops. Nice little way to regulate fuel flow until you need throttle control.

If you want more reed valve trivia ask me about the Dynajet I bought from back pages of an Edmund Scientific catalog. That was a hell of a lot more dangerous -- and consequently much more fun -- than any Cox Thimbledrome .049.

[Napoleon]

Originally posted by pchall
Edmund Scientific catalog

That just gives me flash backs to my youth, reading the catalog and pining for my very own laser.

[chop456]

Originally posted by pchall
Didn't Polimotor try this unsuccessfully in the 80s?


I don't know. But he DID play for the Brewers and Twins. ;)

Thanks for the answers guys. I had visions of layered CF splintering all over the place while being milled. I guess that clears that up. I'd still be curious to know the weight of 1 cu.in. of Titanium vs. 1 sq. in. of CF.

Ziggy - I don't have anything concrete about the Renault, but I found this tidbit at technicalf1.com :

Quote :
“Finally J.J.His revealed it : ‘The RS23 engine for the next season fits a new system for the valve control’. We already knew that the new engine has something that makes it different from the other V10 and that it can’t be the electromagnetic valve actuation or direct injection. So we asked the specialists and we came to a plausible answer about the system that ‘should be’ integrated in the head of the RS23. (...) Renault in the early ‘90s introduced the pneumatic closing of the valve. Basically ‘air’ (commonly nitrogen) at high pressure substitutes the spring. (...) Today the system is universally adopted in F1, in the case of the Ilmor engine the ‘air spring’ is controlled via an electro-valve, a diaphragm with variable opening that adjust the pressure as function of rpm, Ferrari doesn’t control the pressure, BMW regulates the air column via an hydro-pneumatic system. Anyway there’s always the need of the camshaft. Renault explored different ways, the piezoelectric distribution is good only in theory, not feasible in the short period due to the excessive weight, the dimension and the poor reliability at the highest revs. Actually the new hypothesis is an hydraulic system. Instead of spring or nitrogen, the closing of the valve can be controlled via oil at high pressure. Furthermore, the system should be (but there’s no confirmation) adopted also for the opening of the valve. The system becomes a sort of ‘desmo-hydraulic’ working in both opening and closing and allowing to remove the camshafts and the related power losses, apart, obviously, the pump needed to keep the oil at the required pressure.”

The one I remember being talked about a few years back had electronic valve actuation.

[Classic Apex]

I have one of those carbon fiber wallets. Still in one piece. No wear-and-tear. Pretty amazing considering that load that sits atop of it.

[oddlycalm]

Material science has gotten to the point where ceramics, metals, glass and graphite have all sort of met in the middle, and the lines have gotten a bit blurred as to what things are.

With regard to graphite engine valves, the process & material isn't anything like the material used for bodywork and chassis parts. It's very likely a casting process that you might associate more with glass, followed by machining with diamond tools. As already indicated, graphite can handle very high temperatures, higher than any metal can withstand. It's commonly used for crucibles for everything from gold to growing silicon, saphire and ruby boules (ingots).

A similar misunderstanding exists regarding glass platters currently used in some hard drives. Technically, the material is glass, but if you saw it, you would think ceramic, not glass. It doesn't look anything like the glass used in windows, and it doesn't break like that glass either.

The single crystal reference in an earlier post related to amorphous metals, aka glassy metals, aka metglass. Most commonly used for high power magnets, metal is heated until molten, the sprayed onto a refrigerated drumb where it solidifies without forming any grain structure, forming a continuous ribbon of metal. The machine is call a jetcaster, and watching it work is a pretty good show. The most common material is neodymium/iron/boron. Coincidentally, this is the magnetic material used in the magnetic valve systems Renault is using. To get an idea of how powerful a neodymium magnet is, if you fully charged a 10lb. block and threw it out in the street you would have cars stuck together, unable to move...;) This process was developed in Anderson, IN at Magnequench (formerly Delco).

Fun stuff!

oc

[Napoleon]

Originally posted by oddlycalm
To get an idea of how powerful a neodymium magnet is, if you fully charged a 10lb. block and threw it out in the street you would have cars stuck together, unable to move...;)

I thought cow tipping sounded like a cool idea the first time I heard of it but doing this sounds like so much more fun.

[mapguy]

Originally posted by Napoleon
I thought cow tipping sounded like a cool idea the first time I heard of it but doing this sounds like so much more fun.

Coming from someone with extensive cow-tipping experience I would have to agree.

[Peter Venkman]

Titanium is about .17 lb./in3, or 4.7 g/cc
while Carbon Fiber (which can vary with different densities of fabric) is about .052 lb./in3, or 1.4 g/cc

Titanium is roughly 4 times heavier.

PV

[Twisty Bits]

Cheddar Goldfish vs Carbon Fibre Goldfish. Hmmmmm.

:rofl:

[oddlycalm]

Originally posted by Napoleon
I thought cow tipping sounded like a cool idea the first time I heard of it but doing this sounds like so much more fun.

The folks at Magnequench used to (and perhaps still do) get their laughs by giving out sample magnets the diameter of a penny and around 4 times thicker to visitor. I understood what it was, so I smiled, set mine down and didn't take it with me. However our area rep put his in his jacket pocket. His jacket jumped out and grabbed every steel handrail or door jams he passed by that afternoon, all his credit cards were completely erased, and he was finally relieved of it tht evening at the airport security check. That was a couple years back, before the increased security. These days they would probably have jailed him as a terrorist for the way that little magnet set off all their alarms...:cool:

oc