PatRoVa Rotary Valve engine

[manolis]

Hello Niels.

A similar solution, i.e.:

single-piece crankshaft supported at both sides of the crankpin,
single piece connecting rod,
single piece casing (including the crankcase, the cylinder and the cylinder head)

seems interesting / advantageous for the single cylinder, too (the drawings are stereoscopic):

Give another look to the above drawing:

It shows the moving parts of this single cylinder PatRoVa 4-stroke engine.

In comparison to a 2-stroke, and excluding the timing belt, it adds only one moving part (the rotary valve).

Strong, well balanced and well supported crankshaft,
single piece crankcase (no need for bolting),
compact and simpler overall structure,
etc.

Thanks
Manolis Pattakos

.

 

[Toolguy]

That is a good looking and interesting design. I am curious - how do you make a 1 piece crankshaft and 1 piece connecting rod and assemble them. Also, how are the valves sealed off from the combustion chamber?

 

[manolis]

Hello Toolguy

You write:
“That is a good looking and interesting design. I am curious - how do you make a 1 piece crankshaft and 1 piece connecting rod and assemble them.”


Here is a single piece crankshaft and the single piece connecting rods of the PatOP Opposed Piston prototype engine:

After the insertion of each connecting rod at its respective crankpin, the plain bearings are inserted and secured.
It works in theory.
It works in practice:
Here is the PatOP opposed piston engine. It has a single piece crankshaft, and single piece connecting rods.
It is a compression ignition engine.
The 636cc direct injection Diesel PatOP engine stands free on a desk:

[ame]https://www.youtube.com/watch?v=2ByEgfTTq1I[/ame]

For more: http://www.pattakon.com/pattakonPatOP.htm


In the case of the single cylinder model engine or of the V-2 model engine (drawings and animations in my last two posts), things are way easier than in the PatOP.
The big end of the connecting rod has 13mm diameter while the main journals of the crankshaft are 12mm in diameter.

The crankpin of the crankshaft is properly shaped to allow the assembly of the single piece connecting rod.
It is easy and simple.

More interesting is that the crankcase (wherein the single piece crankshaft is rotatably mounted with the single piece connecting rod(s) driven by the crankpin of the crankshaft) together with the cylinders and the lower side of the cylinder head(s) is a single piece, too.

Assembly:
The piston (without the wrist pin) is inserted into its cylinder.
The crankshaft is inserted into the crankcase (the size of the balance web of the crankshaft allows it).
The connecting rod is inserted into the crankshaft.
The assembly of the crankshaft with the connecting rod is moved oppositely to the cylinder until the crankshaft journals to abut on the holes for the roller bearings.
The piston is pulled towards the lower end of the cylinder and the wrist pin is inserted and secured.
The assembly of the crankshaft with the connecting rod(s) and the piston(s) is moved at its normal position and the two roller bearings (those supporting the crankshaft on the crankcase) are assembled and locked.



You also write:
“Also, how are the valves sealed off from the combustion chamber?”

Just think how a ring-less piston seals the combustion chamber in a model engine.

The PatRoVa rotary valve has a much easier duty than a ring-less piston.



Please let me know if something is confusing to further explain.

Thanks
[FONT=&quot]Manolis Pattakos[/FONT]

 

[Toolguy]

Very interesting mechanics. Thanks much for taking the time to answer my questions.

Best Regards -
Warren

 

[manolis]

Hello all.

Quote from http://www.cycleworld.com/2014/11/2...alves-motogp-tech-analysis-with-kevin-cameron

“Benefits Of Pneumatic Valves

MotoGP rookie Jack Miller is feeling the effects of what his Honda engine “wants.”
By Kevin Cameron posted Nov 29th, 2014 at 10:00pm

I noted that MotoGP rookie Jack Miller, describing his recent test at Malaysia’s Sepang International Circuit, spoke of the “smoother, more controlled power delivery” of the pneumatic-valve Honda RC213V-RS.

I like to emphasize that pneumatic springs have value other than the raw ability to reach high rpm. What pneumatics do best is make the valves follow short-duration, high-lift cams that metal springs cannot. Engines with metal springs must be given longer duration and reduced lift if they are to reach competitive rpm, and both of these changes compromise performance. Yamaha was behind this 8-ball in 2006.
Increasing duration (valve open time) to give metal springs longer time in which to accelerate/decelerate valves has two harmful effects:

1) Keeping the intakes open longer after bottom center (BDC) allows the piston, rising on its compression stroke at low- and mid-rpm, to push out part of the fresh charge it has just pumped in (at higher revs, the inertia of the faster-moving intake flow prevents this). Less charge retained in the cylinder equals less engine torque.

2) Beginning to open the intakes earlier before top center (TDC) extends the overlap period during which the exhausts are not yet closed yet the intakes have begun to open. This creates a window through which exhaust pipe waves act to create a deep flat spot just before peak torque. (This occurs at mid-rpm when the returning pipe wave is positive and pushes exhaust gas back into the cylinder and possibly even fills the intake pipes and airbox with exhaust. The torque-weakening effect of all this exhaust gas in the cylinder produces the flat spot.)

The result of the above is both weak torque in the low- and midrange, and a steeper, more abrupt torque rise from the flat spot to the torque peak just above it. The rider finds it tricky to exit corners smoothly when his engine has to accelerate through such a steep torque rise.

The third effect is reduced intake flow even on top end, caused by the reduction in valve lift required if a metal-spring engine is to reach higher revs.
In sum, what pneumatic springs really do is allow valve motion to more closely approximate what the engine and its airflow “want.”

END OF QUOTE


It seems the poppet valves have reached their limit in the MotoGP racing engines.

For even more power at higher revs, they are required even bigger valves and even longer valve lifts.

The metal valve springs cannot follow.

The Desmo of Ducati has reached its limits.

The pneumatic valve springs are better, however the inertia loads increase with rpm square, they also increase proportionally with the valve lift, they also increase proportionally with the mass of the valve (which increases with the cube of the valve diameter).



Here is a PatRoVa Rotary valve with tapered disks (the exhaust exits from the centers):

and a stereoscopic animation (instructions on how to see it at http://www.pattakon.com/pattakonStereoscopy.htm )

Thoughts?

Objections?

Thanks
Manolis Pattakos

 

[Niels Abildgaard]

I like it very much and think it will look even nicer as uniflow Two stroke with a single chain or belt for exhaust-valve drive

 

[manolis]

Hello Niels

You write:
“I like it very much and think it will look even nicer as uniflow Two stroke with a single chain or belt for exhaust-valve drive”


A 2-stroke version of the PatRoVa is in the “rotary valve” web page of the www.pattakon.com


On the other hand, with 4-strokes capable to rev at extreme revs, the 2-stroke seems not the ideal choice


Back to the moto-GP engines and their need for “square valve lift profiles”:


In this plot ( from http://www.pattakon.com/pattakonPatRoVa.htm ) :

it is shown the way the PatRoVa rotary valve can give as square profile as desirable.


According the above plot, the (peak) valve area is the area of the “blue” window times two (because there are two such windows that cancel out the total force applied by the high gas pressure (during compression, combustion, expansion) on the rotary valve, and on the bearings of the rotary valve).

Keeping constant the area of the blue window (and its radial dimension),
and increasing the diameter of the rotary valve (the rotation axis of the rotary valve (at the cross, at top) moves away from the window),
the f1 angle decreases (and the f4 angle increases by the same amount to keep the inlet duration: 2*(f1+f4) constant).

As the diameter of the rotary valve increases, the duration the window remains completely open during the induction (which is: 2*(f4-f1) ) increases, while the duration of the two ramps (2*(2*f1)), which is when the blue window is “partially open&#8221 decreases.

For instance, if the diameter of the rotary valve doubles (keeping the area of the blue window and its radial “height” unchanged), the f1 halves, which means the duration of the two ramps halves and the angle 2*(f4-f1) during which the blue window remains completely open increases by the same amount (simply talking: what is lost at the ramps is added to the “full open” duration).

Increasing more and more the diameter of the rotary valve, the “valve lift profile” gets more and more square.
Theoretically, it can be as square as desirable.


Increasing the external diameter of the PatRoVa rotary valve, and keeping unchanged the radial “height” of the window, the hub (or shaft) of the PatRoVa rotary valve gets even stiffer, while the exhaust port on the rotary valve moves away from the “high pressure sealing area” of the rotary valve (the area on the two opposed disks where the window gets red), which further helps in keeping the “sealing clearances” (between the rotary valve and the windows of the combustion chamber) too small:

Worth to note here:
The sealing of the PatRoVa is not based on the contact of some surfaces or sealing means (as happens, for instance, in the Cross-Bishop rotary valve, wherein the sealing is based on a set of immovable seals abutting onto the working cylindrical surface of the rotary valve).


According all the previous, the increase of the external diameter of the PatRoVa rotary valve (in order the valve lift profile to be more and more “square&#8221 does not limit the rev limit of the engine. Because its bearings are rid of loads, and because its “sealing” is not based on the contact of surfaces (which means, it is a frictionless sealing).

The only limitation is the required space for the bigger diameter PatRoVa rotary valves.


By the way, in the moto-GP revs (r.p.m.), a substantially bigger clearance is allowed because the time for leakage is substantially reduced as compare to that of non-racing engines.

Achieving at, say, 200 rpm of the manual cranking, such a compression (the valve is dry):

the clearance required at, say, 100 (a hundred) times higher revs (20,000r.p.m), where a motoGP PatRoVa is to work, is by far bigger and way easier to be achieved and maintained.



QUOTE from http://www.pattakon.com/tempman/Bishop_Rotary_Valve_AutoTechBRV.pdf

Testing of these engines (the Bishop Rotary Valve F1engine) was prematurely terminated when the FIA announced changes to Article 5.1.5 of the engine regulations late in 2004 with the specific purpose of banning this rotary valve technology.

End of QUOTE.


Does anybody know whether the rotary valves are already banned in the motoGP engines?


Thanks
Manolis Pattakos

 

[2002hummer]

Question? What sort of compression ratio do you get. With the large volume in the rotary valve assembly there must be a way to bring the compression up around 9.5 to 1, a good compression for a gas engine.

 

[manolis]

Hello 2002hummer.

You write:
“Question? What sort of compression ratio do you get. With the large volume in the rotary valve assembly there must be a way to bring the compression up around 9.5 to 1, a good compression for a gas engine.”


The following drawing is based on the first PatRoVa prototype (nothing to do with optimization):

The volume in the cavity is 25cm3.

The total port area (12cm2) is, more or less, as having on the cylinder head two intake an two exhaust poppet valves of 32mm diameter each (the Honda 1,600cc VTEC engine (B16A2, one of the best sport car engines, ever) has 33mm intake valves diameter, 28mm exhaust valves diameter and 5.5mm valve stem diameter.

Note: the 33mm diameter intake valve seats on a “hole” having a diameter of 28.5mm).

Note also: each cylinder of the Honda VTEC is 400cc.

With the same cylinder (81mm bore, 400cc capacity) and 1mm clearance between the (flat) piston crown and the cylinder head, the resulting compression ratio for the PatRoVa is: 14.3:1.

According the Bishop Rotary Valve team, in their F1 test engines (more at http://www.pattakon.com/tempman/Bishop_Rotary_Valve_AutoTechBRV.pdf ) “no evidence of knock has ever been observed”, even at compression ratios as high as 17:1 (their optimum compression ratio was 15.3:1 for F1 use).

I.e. the 14.3:1 is not too much.

The compact and fatty combustion chamber of the PatRoVa (compare it to the skinny and attenuated combustion chamber of a Ducati Panigale 1299 Superleggera) can offer a combustion that completes almost entirely inside the cavity (the flame has a short distance to travel till the ends of the cavity), leading to a, say, 13:1 to 14:1 mean expansion ratio which can increase substantially the brake thermal efficiency, decreasing at the same time the exhaust gas temperature (as Mazda calls it: a low temperature combustion).



In short stroke racing engines (say, bore to stroke ratios 2.0:1 to 3.0:1 ), the design with the tapered disks allows a “shorter” engine (the lower “side” of the two oppositely arranged fronts – i.e. the two flat sealing surfaces of the spool – “get” into the piston crown, if desirable) and a higher compression ratio:

If desirable, the compression ratio can further increase either by shaping properly the ceiling and the side walls of the cavity (which, besides occupying a good part of the cavity, can also improve the air-flow capacity) add/or by using en extension on the piston crown that gets into the cavity, say like:

Thanks
[FONT=&quot]Manolis Pattakos[/FONT]

 

[Nick Hulme]

With substantially faster combustion and with substantially more compact combustion chamber, things improve a lot (fuel efficiency, clean exhaust, less cooling, etc).
.

You are assuming combustion takes place while all the mixture is in the chamber, how much advance and what speed of flame front propagation will be required for that to happen at the revs normal for the engine you are using as a basis for this comparison?

 

[manolis]

Hello.


Regarding the spark advance and the combustion duration in the PatRoVa rotary valve:


QUOTE from http://home.people.net.au/~mrbdesign/PDF/AutoTechBRV.pdf about the Bishop rotary valve engine:

“This oblique flow through the window is responsible for one of the rotary valves most useful attributes - its strong in-cylinder tumble flow. The tumble ratio on engines with near square bore/stroke ratios is typically twice that reported for similar 4 valve engines. Unlike the poppet valve this high tumble flow is generated without any loss of volumetric efficiency (VE) and is responsible for very fast burn rates observed. Production based engines built in the early 1990’s had ignition timing of 15°, or less than half that of the best four valve engines.”

End of QUOTE


In the PatRoVa the combustion chamber (i.e. the cavity at the “top” of the cylinder head) is substantially more compact and more fatty and more concentrated around the spark plug than the combustion chamber of the Bishop rotary valve.

The high tumble flow in the PatRoVa remains strong even at the end of the compression (piston at the TDC) because of the shape of the cavity.

These characteristics make the required spark advance substantially shorter than in a Cross-Bishop rotary valve engine (and a few times shorter than in the best 4-valve engines), and the combustion ends shortly after the TDC.


For comparison with a high-tech poppet valve engine:

Think of the combustion chamber of the Ducati Panigale 1299 (116mm bore, 60.8mm stroke, 12.6:1 compression ratio (i.e. mean “height” of the combustion chamber when the piston is at the TDC: 4.5mm)) which is like a coin with abnormal top and bottom surfaces (valves, valve pockets etc).

The flame in the Panigale 1299 propagates in two only dimensions, while in the PatRoVa the flame propagates in all three dimensions.

The flame in the Panigale has to travel twice the distance it travels in the PatRoVa.

The stronger tumble, swirl and turbulence in the PatRoVa force a substantially faster flame propagation.

With the combustion completed substantially earlier in the PatRoVa Panigale, the actual expansion ratio is substantially bigger, the fuel efficiency is better, the exhaust gas temperature is lower and the power output is higher.

Thanks
Manolis Pattakos

 

[Nick Hulme]

The flame in the Panigale 1299 propagates in two only dimensions

Think that through and get back to me once you understand what you've said there and it's implications for Physics as we know it.

 

[manolis]

Hello.

Thanks
Manolis Pattakos

 

[Nick Hulme]

A one dimensional figure is a line with only length, not a tube, a two dimensional figure is a plane with no thickness, not a cylinder, a two dimensional combustion chamber, among other things, would give you an infinite compression ratio,
Thanks,
Nick

 

[manolis]

Hello all.


The following drawings show a 2-stroke Flat-Head PatRoVa:

The last animation is stereoscopic (more on how to see stereoscopically at http://www.pattakon.com/pattakonStereoscopy.htm )

The piston is shown in the BDC (bore 116mm, stroke 60.8mm, i.e. as in the 4-stroke Desmo Ducati Panigale 1299)

The blue rotary valve spins at half crankshaft speed.

There are two exhaust ports on the ceiling of the combustion chamber, and two “cuts” on the rotary valve.

The passageway around the hole for the spark plug (at the centre of the cylinder head) provides “pressure” at the top of the rotary valve, so that the rotary valve can spin without friction (the flow of the exhaust gas happens only through the bottom side of the rotary valve).


If the exhaust ports at the top of the combustion chamber seem not big enough, then a different version can be used wherein the rotary valve rotates at crankshaft speed and serves two neighboring cylinders (twin even firing 2-stroke), with the rotation axis (or the shaft) of the unique big-diameter rotary valve being between the two cylinders; in such a case, the area of the exhaust port on the ceiling of the combustion chamber can be as big as the piston area.

Thanks
[FONT=&quot]Manolis Pattakos[/FONT]

 

[dkwflight]

HI
I wonder about sealing and the changes from heat.
I suppose with careful choice of materials the dimension changes due to temperature rise would be minimal.
Still what about sealing?
If the valve leaks by the engine might have trouble idling.
Starting may need high speeds to initiate combustion.
Good luck with the development of this engine
Dennis

 

[manolis]

Hello Dennis and thanks.

The sealing is based on keeping the clearances too small, preferably without sealing means (which require lubrication, consume energy, etc).

The question turns to whether the PatRoVa design can keep the clearances as small as required.


The form of the PatRoVa rotary valve (a short and extremely stiff hub / shaft having two disks secured at its ends),

the loading of the PatRoVa rotary valve from the high pressure gas (which eliminates the total force acting on the valve and on its bearings),

its unconventional architecture according which:
only the one dimension relates with the sealing clearances (the other two dimensions are insignificant for the sealing efficiency),
the combustion chamber has uniform temperature (because every point of it relates equaly with the intake and the exhaust),
the width of the combustion chamber is small (keeping small the thermal expansion),
the limited angle (some 90 degrees) around the rotary valve wherein a tiny clearance between the disks of the rotary valve and the ports of the combustion chamber is required,

etc,

allow (and, more important, can maintain during the operation) the required tiny clearances.

Thanks
Manolis Pattakos

 

[manolis]

Hello all.

According an Issue Notice of the US Patent and Trademark Office:

a patent is granted for the PatRoVa Rotary Valve.

The patent number is US9,677,434.

Thanks
Manolis Pattakos

 

[Nick Hulme]

Still what about sealing?

It will work fine dry if the tolerances are tight enough, the down side is that a system with such tight tolerances will not be tolerant of any contaminants and, like Ducati engines, will eat itself in an interesting way at an unpredictable point ;-)


The patent is a great (but expensive to enforce) protection against the hordes wanting to use your design without paying

- Nick

 

[manolis]

Hello all.

Today the US-PTO published the USA patent granted for the PatRoVa rotary valve.

Here is the link:

http://patft.uspto.gov/netacgi/nph-...50&s1=9677434.PN.&OS=PN/9677434&RS=PN/9677434

Thanks
Manolis Pattakos