Coates Rotary Valves

[JD@af]

I've mentioned these in a thread in this forum already titled too many cylinders., but it seems that there has been no other mention of them here from what I can tell I couldn't find anything about them (except for my one post about them, which I located using the quick search function).

Does anybody have any impressions of them that they'd like to share? If you are not familiar with them, here's the web site:

http://www.coatesengine.com

I personally think they're a better direction for cylinder head design than the one that BMW is taking. BMW is researching and building prototype cylinder heads without cams, that control valve movements and timing electronically. The Coates rotary valve design does basically the opposite, keeping the cams, and pretty much only the cams, while eliminating all the other moving parts from the head (along with motor oil!!).

Imagine a smaller, lighter cylinder head, that needed no motor oil for lubrication (the system uses very low friction parts), made great power, and offered high rpm endurance (your first enemy of high rpm use is the threat of "valve float," where the valve cannot snap itself back into the valve seat fast enough to avoid contact with the piston, often due to mechanical limitations of the system at certain high rpms - this limiting factor commonly establishes a given engine's redline). Sounds like a dream too good to be true to me

But please, I'm curious for your thoughts. Thanks-

-JD

[Moppie]

I believe Texan described them as "Death" in another post here some time ago. (as I havnt seen him since, but if you talk about him enough he does seem to show up).

[JD@af]

Oh man, I'll have to see if I can reach him on email and find out more. He was so excited about them about a year or so ago... hmmm.

Well anyway, thanks for the tip, Moppie.

[texan]

Actually I think the Coates system is great, providing they can really demonstrate it's effectiveness on a production type engine. They claim to have done just that, but I'd just be super excited to see them develop an aftermarket cylinder head for say, a B series Honda motor, and let that do their talking. The concept itself certainly seems more simple than poppet valves though, you almost have to wonder why it wasn't thought of and worked out long before now (prolly just a status qou thing).

[Moppie]

wow. speak of the devil and he shall appear!!!


Making the coates system varialbe lift would have its problems, leaving you back were started with a popet vavle.

[Hudson]

This would have been a great idea had it made it into production 10 or 20 years ago (and I know the idea's been around for quite some time) but camless valves will be an even greater improvement when they arrive in a few years. As soon as 42-volt electrical systems are made available in cars (about two years away in some cars), camless valves will follow shortly. BMW's not the only one planning this.

As far as not needing oil in the head, are you sure about his? I don't care how "low friction" the parts are, those cams are moving quite fast and will be rubbing against other parts (or else there would be no seal and no compression) which will cause friction. Oil will be necessary in the head. Teflon on teflon (the lowest friction combination possible) would still need lubrication at 2,500 rpm.

[JD@af]

Originally posted by Hudson
As far as not needing oil in the head, are you sure about his? I don't care how "low friction" the parts are, those cams are moving quite fast and will be rubbing against other parts (or else there would be no seal and no compression) which will cause friction. Oil will be necessary in the head. Teflon on teflon (the lowest friction combination possible) would still need lubrication at 2,500 rpm.

Originally posted by http://www.coatesengine.com/Body.htm
Absence of poppet valves and other operating accessories normally housed under the valve cover has permitted elimination of both oil lubrication and cooling water flow in the upper portion of the cylinder head. This reduces the overall engine height by as much as 20 cm from that of its conventional counter part, and maintains a clean engine.

The new, patented simple valve-train unit has minimized the area of contact for fluid flow through the gas exchange ports by making use of wide-open circular cross-sections. This significantly cuts down the pumping loss and unmatchably increases the volumetric efficiency to achieve a high torque/power-density engine.

The new dynamically balanced rotating spherical port valve eliminates entirely mechanical noise produced by current poppet-valve components. Hissing sound generated as gas flow squeaks through the narrow annulus valve opening in the conventional cylinder head is no longer audible. At the same time, the new unit cuts down, by an order of magnitude, the need for power out of the crankshaft. Normally a big parasitic power drain is required in conventional engines to drive the valve train.

Without quoting the entire web site, poke around, and they have some info on the materials used to lubricate the valves. In fact, I think they even went so far as to say that their heads coul operate without needing a valve cover in place!

As for the 10 to 20 years ago thing, I think you're only half right. Valves themselves still represent disruptions in airflow as the air/fuel mixture enters the combustion chamber. This disruption can be used to help aid air/fuel mixing, but in general, I like the idea of eliminating valves altogether. Besides that, do you think that eliminating the cams will be sufficient to prevent valve float at high rpm use? I think that this will continue to represent a challenge for engine designers married to poppet valves.

[Hudson]

Valve float is eliminated with electro-magnetic valves. Formula 1 engines have used them and they run speeds much higher than you'll find in street cars. If you want to eliminate the traditional "valve" itself, that, too, can be done with an electro-magnetic system, again taking up less space than the system you're discussing.

This idea has been tossed around for decades. I know I've seen the design atleast ten years ago...and if I saw it then, it had to be around well before that time.

Nowhere on the site does it go into how the valves are lubricated. My money's on this engine either a) needing a lubrication system to work properly over the long haul or b) having such a gap (or wearing one away) that you would lose compression well before 50k miles. I know the site says that one prototype engine went over 150,000 miles, but until someone properly explains how you can have a low-tolerance moving part without any lubrication, I will not believe it.

Besides, since this idea's been around for over ten years, why hasn't it been put into production? Engineers are not "married" to the idea of the traditional engine design. They will, and have, taken dramatic steps in new directions when a better idea comes along. I don't think this is all you believe it to be.

[JD@af]

Late response to this thread. I had meant to say that I was very impressed with your rebuttal, and you kind of took the wind out of the rotary valves' sail in contrast with advanced electro-magnetic technology being used in the cylinder head to control air and fuel entering and exiting the combustion chambers. As much as I still like the idea of rotary valves (part of me is still very fundamentally old-fashioned, and therefore I admire the simplicity of the overall design), they seem to just not cut it ultimately as competition for electro-magnetic applications. Nice job!!

[Slickvic]

Hudson, here is the info about the lubrication issue. Also, electromagnetic or not, conventional poppet valves restrict airflow when open which the Coates system does not.

Among the primary engineering challenges in the
development of the Coates head was implementing a reliable
seal between the combustion chamber and the valve, while
keeping friction at a minimum. The rubbing of metal against
metal, which results from a rotating surface moving over a
fixed one, usually causes substantial wear and lessens the
ability to form an effective seal.
Coates said that he has solved these problems using a
unique sealing mechanism with each valve. Although the seal
is fixed in the cylinder head, part of it moves in a linear
motion in response to cylinder pressure generated during
compression. As a result, the seal surface is pushed solidly
against the periphery of the rotating valve. The sealing
surfaces are, therefore, in contact for one piston stroke, or
one quarter revolution of the crankshaft.
The Coates rotary valves are fashioned from Nitralloy, and
the face of the seal is made from a proprietary carbon-
ceramic alloy. Both materials are highly resistant to wear,
and neither requires lubrication in the engine. "The seal
wears only 0.0001 inch every 25,000 vehicle miles," Coates
said. Indeed, the seal compensates automatically for wear
during engine compression by means of its linear motion.
A similar, but not identical, carbon-ceramic composition
is used in the bearings that support the shaft on each side
of the valves. Meanwhile, conventional steel ball bearings
provide support at opposite ends of the shaft.

[JD@af]

NOW THAT IS SOME GOOD SHIT!!!

[Steel]

wow..he smarT

[Slickvic]

No Steel, I just good use of a search engine and cut & paste.
"Work smart, not hard"

[GTStang]

It all sounds good but what kinda money does it cost to make heads like this over the good old heads we been using for decades? My only question

[Shaw]

I read the post on the Coates (CSRV) engine with some interest as my company is currently bringing it to market as part of an advanced power generation system (*Well to Wire Energy Inc.) The units are in production at this time and a diesel version of the system has been licensed to a company called McLean England & Associates of Little Rock Arkansas.