New Engine Technology - Coates "Spherical Valve" Engine

Messages
111
Location
Levittown, PA
Neat new concept: http://www.coatesengine.com/technology.html In the late 1960s and 1970s, most vehicles combustion engines in the USA were running at a compression ratio of 12 to 1, which resulted in an engine efficiency of approximately 55 percent. The rest of the engine power was lost in friction, pumping and heat loss. When it was found that lead additives in fuel had an adverse effect on the environment, it was removed from the fuel. This caused the poppet valves and combustion chamber on poppet valve engines to overheat, raising the temperature to in excess of 2500 degrees F and damaging the poppet valves. The answer to this problem was to lower the compression ratio of all engines to 10 to 1 or lower, thus reducing efficiency of the combustion engine to approximately 24 percent. This means less miles per gallon (MPG), lower brake horse power (BHP) and lower torque. The air traveling in through the inlet venturi of a combustion engine inlet travels at a speed of up to 450ft a second. In normally aspirated engines this works fine, but in poppet valve engines, the BHP and torque decreased as the air traveling in does not increase in speed unless a turbo or supercharger is incorporated. At higher RPMs the poppet valve tends to float or bounce and is unable to service the cylinder and chamber to capacity with air and fuel mixture. This is the reason for adding two extra valves to modern engines, causing unburned fuel to escape through the exhaust system which leads to a loss of power, lower MPG and produces significant pollution. The poppet valves' stems are lubricated with engine oil which is burned off after a short period of running. The stem of the inlet valve system is also lubricated with engine oil, which is washed off and inducted into the combustion chamber with air and fuel mixture. This slows combustion and produces further emissions and eventually clogs the catalytic converter. Variable valve timing has advantages at lower RPMs as it can shorten the overlap duration of the valves, but has extra moving parts that eventually wear. On quick deceleration, it can cause piston and valve contact where serious damage can occur. Poppet valves, if not activated with hydraulic systems, must have clearance readjusted periodically. The successful poppet valve of the original combustion engine has been used and modified continuously until the present. However, it is the most troublesome part of a combustion engine and has lower efficiency at higher RPMs. Remedy The Coates Spherical Rotary Valve Engine is the most advanced in the world, with the most positive valving system ever built. The breathing capabilities of the system are almost double that of a poppet valve. For instance: a static test of a five-litre poppet valve engine on an airflow machine produced a reading of 133 cubic feet per minute (CFM) with valve fully opened. The five-litre Coates Spherical Rotary Valve Engine on the same machine, however, produced a reading of 319 CFMs fully opened; a colossal advantage in airflow comparison. A five-litre poppet vavle engine tested on a dynomometer under the same loads and conditions at 5500 produced 480 BHP and 454 foot pounds of torque. The maximum RPMs on the poppet valve engine were 5700 RPMs; the Spherical Rotary Valve Engine in comparison reached 14,850 RPM's, The Coates Spherical Rotary Valve comprises two spherical rotary valves assembled on two separate shafts - one for inlet and one for exhaust. They rotate on ceramic carbon bearing with no oil lubrication, the spheres do not make contact with any part of the housing. The seals are a floating type and are also made of a ceramic material. They have two piston rings and are floating in a small cylinder-type chamber, they are activated by the compression and the combustion strokes of the engine which allows 100 percent sealing effectiveness, when compressed. Because the valves rotate away from the combustion chamber and are vented and charged on the opposite side of each sphere, this creates a lower combustion chamber temperature, allowing for higher compression ratios to be used thus creating an extremely efficient engine. Some of the Coates Spherical Rotary Combustion Engines are at 12 to 1, 13 to 1, 14 to 1 and 15 to 1 compression ratios depending on the application.
 
Messages
453
Location
ON, Canada
Seems cool, but... Would cylinder valves not make more sense? Or they need to be spherical because of the kind of sealing they work with? How come the sealing is 100% efficient when activated AND it is able to survive the ROTATION at 7k RPM? Without lubrication? How come Mazda did not use this kind of seal in their rotary engines? Spheres have to stick into combustion chamber to make pumping restriction minimal when valves are open... In any case, the combustion chamber will be far from ideal semi-sphere. Hmm...
 
Messages
1,908
Location
Fort Worth, TX
Few if any engines of the 1960's operated at 12.0:1 cr, primarily some low production race engines not destined for the street. From the high eights/low nines to the high tens/low elevens is more like it. High compression is more efficent, but it is harder on rings, crankshafts, sparkplugs, etc., as one or two cylinders of an engine wear faster than others due to fuel distribution. Regular leaded gas was good for up to the low nines, and premium was wanted for above that. The factory ratings were as much as 1/2-point high (10.0:1 was really around 9.5:1 cr). Big engined American luxury cars were generally in the tens, with a very mild camshaft overlap. This enabled excellent torque off-line, unreal throttle response, and good cruise economy. Once CR dropped the big motors were nothing more than gaas hogs . . a wholly different driving experience. We see the same in luxury cars (and others) today where peak torque and horsepower are at a low rpm; 80-90% of peak torque is available over the vast majority of the rpm range. It took computer-controls and FI to achieve this. And CR went back up as fuel burn control became more sophisticated. I read of the Coates engine several years ago. Am always glad to see new ideas.
 
Messages
70
Location
Central MN
I'm not an engineer, but I certainly believe that our reliable ic engines can be improved upon. I strongly suspect that any car company trying to maximize it's fuel economy will look at virtually every new design that holds promise. Perhaps this is one of them? Glen
 
Messages
1,485
Location
Germantown, MD
This thing pops up on every automotive board I frequent every couple of years. It's not new. If it worked like they say it does, I'm sure the automakers would be clamoring to use it. That they aren't should tell us something. I'd love to know how they got an engine to run at 3x it's normal operating speed just by changing the valvetrain. 14,500 rpm is 600cc motorcycle territory, and those only achieve those high rpms because they have a very short stroke, keeping cylinder accelerations at a reasonable level. jeff
 
Messages
780
Location
Palatine IL
Looks like a good bit of rotating mass. Lots of heat brought into the valve cover area to cook oil or maybe the rotary valves don't need oil and just get and stay real hot after some extended running. If the performance benefits were there, racers would be using it even if the car companies were slow to step in. Has less power and economy at low rpm due to the chamber shape and no capability for variable valve timing. I wonder how long the seals hold up. Very non-economical since it makes more power by being able to spin faster without float. Probably has to idle rough at 2500 rpm to make that power at 15k rpm. Totally bogus comparison for a street vehicle and production based piston speeds. Seems more of a race oriented design but we have F1 teams spinning near 20K with pneumatic actuated valves and completely variable timing so it seems that there's a reason it's still not being manufactured.
 
Messages
3,593
Location
Outside smalltown, IL
quote:
Originally posted by JTK: What's the disadvantage of this valvetrain? The sealing surface around the 'balls'? Joel
That would be one. I image they use ceramics for the seal because that's the only way they could get the system to work for any length of time. Also, poppet valves are forced closed by combustion. These valves will tend to be forced open. There also the combustion chamber shape to be considered. It might be impossible to get a reasonably shaped combustion chamber with these valves. That's one of the reasons side valve engines are so inefficient even though they mechanically simpler than any OHV setup...
 
Messages
11,392
Location
Florida, Cape Coral
Atlas Imperial Diesel Engine Company (California) worked on and invented the spherical engine valve system in the 1940 & 50s. They found usefull measurable gains in engine efficiency but, scrapted the project because of long term reliability issues. Maybe new materials availiable today will make the idea a reality?
 
Messages
1,034
Location
GA, USA
Using the same principle as CVT, VVT with this valve design is conceivable. Keep in mind, with F1 engines, it's a matter of the regs. I'm sure the engine builders would consider this valve design and eliminate the current pneumatic, reciprocating valve setup but it's simply not allowed. Rotational mass is preferable to the reciprocating type.
 
Messages
39,805
Location
Pottstown, PA
If this was practical ..or even if it wasn't ..but offered some type of substantial advantage ..someone would have it in production. The Wankel wasn't efficient ..nor did it set any longevity records when it first came out, yet the ability to rev very high with light weight put it in use. You see these kinds of things all the time. They appear to pop out from the dark crevaces whenever we have an energy crisis and people need "hope" that someone is going to pull a rabbit out of a hat. It surely costs more then it can yield in benefit ..otherwise it would "be".
 
Messages
43,671
Location
'Stralia
It's been and gone a number of times. In the early parts of last century, this concept was tried (and I think some were sold to the public), along with conical rotating valves, cylindrical, slide, and sleeve valves (once very popular). When I did my thesis, Arthur Bishop (inventor of the variable ratio rack and pinion) was working on a cylindrical version with great BSFC, great power, and problems keeping gas out of the oil, and oil out of the cylinder.
 
Messages
214
Location
Illinois
quote:
You see these kinds of things all the time. They appear to pop out from the dark crevaces whenever we have an energy crisis and people need "hope" that someone is going to pull a rabbit out of a hat. It surely costs more then it can yield in benefit ..otherwise it would "be".
I know diddly about all this valve stuff, but THAT makes a whole lot of sense... [Cheers!]
 
Messages
260
Location
Newtown, PA
I remember reading that Dr. Wankel developed rotary valves for a major german manufacturier in the 60's, BMW or Mercedes. Anyway, they never made anything of it. This design may suffer from being too good, with all that flow it's gonna have bad intake velocity at low rpms. Probably also very expensive to produce and i can't seem to find a picture of the combustion chamber. I also wonder how this design would take to forced induction.
 
Messages
12,385
Location
Northern CA
quote:
Originally posted by TheTanSedan: Few if any engines of the 1960's operated at 12.0:1 cr, primarily some low production race engines not destined for the street.
The efficency number for the 12:1 engine was ** too. The emphasis on the higher airflow was a bit of puffery. Maybe true, but not as relivant as their numbers would have you believe. Modern engines are coming close to 100% volumetric efficiency with poppet valves. There may be something to their engine, but when the plain unvarnished truth isn't enough, it makes everything a person says suspect.
 
Messages
12,385
Location
Northern CA
quote:
Originally posted by Raven18940: The new 2.8 v6 turbo in the saab 9-3 aero has sodium filled exhaust valves, how trick is that. [Razz]
My older brother put sodium filled valves in the flathead V8 Ford engine he built in 1954. Sodium filled valves weren't new then. I remember the year because he was home on leave from the Air Force, I was in the early 6th grade and got to help him build the engine. I remember the sodium because he 'splained what would happen if he cut into the sodium while he was reworking the valves on a lathe.
 
Messages
780
Location
Palatine IL
quote:
Originally posted by Blokey: Using the same principle as CVT, VVT with this valve design is conceivable. Keep in mind, with F1 engines, it's a matter of the regs. I'm sure the engine builders would consider this valve design and eliminate the current pneumatic, reciprocating valve setup but it's simply not allowed. Rotational mass is preferable to the reciprocating type.
Variable timing is real important to these engines and there is no rule against this design. The reciprocating mass in those motors is extremely small so there is no disadvantage. They're activated without engine drain or spring resistance from a presuure tank and capable of much higher RPM than they're currently running at. It's not the RPM bottleneck nor has the parasitic loss of a cam drive.
 
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