PatRon: Harmonically Reciprocating Piston Rotary Engine

Hello all.

Here :



is a PatRon Reciprocating-Piston Rotary-Engine.



It comprises a crankshaft, a piston rotatably supported on a crankpin of the crankshaft, and a rotating cylinder wherein the piston reciprocates sealing one side of a combustion chamber.

For a complete reciprocation of the piston inside the cylinder they are required two rotations of the crankshaft.

Without external balance shafts, the balancing of the inertia force, moment and torque is perfect (even for the single cylinder).



A synchronizing gearing keeps the cylinder rotating at the same direction with the crankshaft and at half angular speed than the crankshaft; the high pressure gas in the combustion chamber does not load the synchronizing gearing.

Not only the power passes directly to the load and the synchronizing gearing remains unloaded but, additionally, the cylinder liner remains rid of thrust loads. Think how.


The stroke S of the piston along the cylinder equals to four times the distance between the (fixed) rotation axis of the crankshaft and the (fixed) rotation axis of the cylinder.

The relation between the displacement D of the piston along its cylinder and the rotation angle f of the crankshaft is like:

D=(S/2)*sin(f/2)

which is a pure sinusoidal (or harmonic) motion.




With the PatRon:

* the power passes directly to the load (more directly than in the conventional reciprocating piston engines: there is no connecting rod (the piston is rotatably mounted directly on the crankpin), there are no thrust loads on the cylinder liner),

* the synchronizing gearing remains unloaded by the high gas pressures during the compression - combustion – expansion,

* the two halves of the "immovable" casing (one per side of the spinning cylinder) are easily coupled / bridged forming a space wherein the cylinder spins safely,



* only one crankshaft is required (and only a set of balance webs secured on the crankshaft for the complete balancing of the engine),

* there are no high speed bearings loaded by heavy inertia loads,

* in case of air-cooling the rotation of the cylinder simplifies things (the cylinder is also the fan),

* if desired, the power can be delivered by the rotating cylinder (which spins at half crankshaft speed),

* it is for single acting, for double acting pistons, even for “multi-acting” single-piece pistons,

* it is for two-stroke and four-stroke engines, etc


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


In a few words:

The PatRon brings the good sealing and the small surface to volume ratio of the reciprocating piston engines in the rotary engines, without introducing significant side effects.


Thoughts?

Objections?

Thanks
Manolis Pattakos

For one, it would be very difficult to make this engine emissions compliant.

The rotating cylinder assembly also would limit its applications to mainly aircraft use.

Ziggy2 said:

For one, it would be very difficult to make this engine emissions compliant.

The rotating cylinder assembly also would limit its applications to mainly aircraft use.

Click to expand...

Give it up. It is near enough a rotary, they gave up on those things 100 years ago. 2 stroke will never pass emissions. A 4 stroke version will be near impossible to pass emissions, You going to spin the catalyst and obligatory computer controls?

dream or reality?

Well it looks like you have put a lot of thought and effort into this design but like others here have noted, it looks like a single cylinder version of one of the old rotary engines used most notably by the French in their World War One airplanes. Perhaps you could point out what, if any, significant differences there is between the two designs.

Onepass said:

Well it looks like you have put a lot of thought and effort into this design but like others here have noted, it looks like a single cylinder version of one of the old rotary engines used most notably by the French in their World War One airplanes. Perhaps you could point out what, if any, significant differences there is between the two designs.

Click to expand...

"What is the improvement over the Rhone and Gnome?"

The energy from the high-pressure gas in the combustion chamber of the PatRon rotary engine passes "directly" to the load; more "directly" than in the conventional reciprocating piston engines (the Gnome and Rhone included) wherein the force on the piston crown passes to the wrist pin, then it splits to a thrust force on the cylinder liner and to a force on a connecting rod interposed between the wrist pin and the crankpin.

The elimination of the connecting rods saves more than half of the reciprocating weight.

Without thrust loads on the cylinder liner you need not a piston skirt.

Without thrust loads on the cylinder liner you need substantially less lubricant (the lubricant is only to prevent the metal to metal contact of the piston rings with the cylinder liner, which means less oil in the fuel for a 2-stroke).

Without thrust loads on the cylinder liner there is no friction between the cylinder wall and the piston skirt.

With the piston reciprocating harmonically (pure sinusoidal motion), as in the PatRon, you have some 15% additional dwell at the combustion dead center (the combustion completes at higher expansion ratios and is more efficient).

With the harmonic motion of the piston there are no second order forces to balance. The single cylinder PatRon is better balanced than the 9 cylinder Gnome and Rhone (and every other conventional radial engine regardless of number and arrangement of cylinders).

The balancing of the single cylinder PatRon compares only with the Wankel rotary.

The throw of the crankshaft is half: for a piston stroke of 80mm, the throw of the crankshaft is 20mm, while in a conventional (or in a Gnome and Rhone) it is 40mm. This gives a stronger crankshaft (overlap between crankpin and crank journals).

Etc.

Thanks
Manolis Pattakos

manolis said:

"What is the improvement over the Rhone and Gnome?"

The energy from the high-pressure gas in the combustion chamber of the PatRon rotary engine passes "directly" to the load; more "directly" than in the conventional reciprocating piston engines (the Gnome and Rhone included) wherein the force on the piston crown passes to the wrist pin, then it splits to a thrust force on the cylinder liner and to a force on a connecting rod interposed between the wrist pin and the crankpin.

The elimination of the connecting rods saves more than half of the reciprocating weight.

Without thrust loads on the cylinder liner you need not a piston skirt.

Without thrust loads on the cylinder liner you need substantially less lubricant (the lubricant is only to prevent the metal to metal contact of the piston rings with the cylinder liner, which means less oil in the fuel for a 2-stroke).

Without thrust loads on the cylinder liner there is no friction between the cylinder wall and the piston skirt.

With the piston reciprocating harmonically (pure sinusoidal motion), as in the PatRon, you have some 15% additional dwell at the combustion dead center (the combustion completes at higher expansion ratios and is more efficient).

With the harmonic motion of the piston there are no second order forces to balance. The single cylinder PatRon is better balanced than the 9 cylinder Gnome and Rhone (and every other conventional radial engine regardless of number and arrangement of cylinders).

The balancing of the single cylinder PatRon compares only with the Wankel rotary.

The throw of the crankshaft is half: for a piston stroke of 80mm, the throw of the crankshaft is 20mm, while in a conventional (or in a Gnome and Rhone) it is 40mm. This gives a stronger crankshaft (overlap between crankpin and crank journals).

Etc.

Thanks
Manolis Pattakos

Click to expand...

How are you going to get the rings to seal when they are rocking around?

Hi

This looks like application of the Tusi mechanism.

With the cylinder rotating I don't see how you can effectively get the air/fuel in and the exhaust gas out.

Why not lock the cylinder in place and let everything else rotate. Then you can use direct fuel injection to meet emission standards. Everything will then be simplified and much more compact.

Rather than using counter weights, I would change the configuration to a 2 cylinder boxer engine. Greater power/kg.

Onepass said:

Well it looks like you have put a lot of thought and effort into this design but like others here have noted, it looks like a single cylinder version of one of the old rotary engines used most notably by the French in their World War One airplanes. Perhaps you could point out what, if any, significant differences there is between the two designs.

Click to expand...

Yes the Gnome rotary.

Hello Monnlight Machine

You write:
“How are you going to get the rings to seal when they are rocking around?”


The rings are not rocking.

The piston rings of the PatRon perform two motions: a rotation (at constant angular speed) with the cylinder about a fixed rotation axis, and a pure sinusoidal (or harmonic) reciprocation along the cylinder axis.

The piston rings are forced by the cylinder liner (whereon they abut and slide) to perform their rotary motion.

The piston rings are forced by the ring-grooves of the piston (wherein they are hosted) to perform the harmonic reciprocation.



For comparison think the motion performed by the side seals of the LiquidPiston rotary engine:



The LiquidPiston is supported by “the” MIT, by “the” DARPA (3.5 million dollras, so far) and by “the “Shikorsky”.
They use to call their engine “reverse Wankel”.


In the Wankel Rotary (say of the Mazda RX-8) the driving of the apex seals is a real challenge. Because the “grooves” at the three corners of the rotor are "open" (they cannot support the apex seal in the radial direction). Even worse: because the inertia force on an apex seal changes direction when the apex seal passes from the area between the spark plugs (or the area between the intake and exhaust ports).


For more, read at http://www.pattakon.com/pattakonPatWankel.htm


Instead of having a “sealing grid” with, inevitably, several gaps (through which a significant part of the compressed gas leaks), as happens in the Wankel and in the “Reverse Wankel” of LiquidPiston, in the PatRon rotary engine they are used conventional piston rings and the gas and oil leakage is as small as in the conventional reciprocating piston engines.


So, please take another look and let me know where you see the problem.

Thanks
Manolis Pattakos

Hello Dazz.

You write:
“With the cylinder rotating I don't see how you can effectively get the air/fuel in and the exhaust gas out.”

As in the LiquidPiston and in the Cross-Bishop-Watson rotary valve engines.


You also write:
“Why not lock the cylinder in place and let everything else rotate. Then you can use direct fuel injection to meet emission standards. Everything will then be simplified and much more compact.”

I think you mean as in the Harmonic Engine at http://www.pattakon.com/pattakonPPE.htm#harmonic ?



So, why the Patron rotary and not a non-rotary Harmonic?

Among others:

because of the bi-directional and heavy loads on the synchronizing gearing during each combustion (which calls, among others, for reliability issues in the long term);

because of the "indirect" passing of the power from the piston to the load: the force on the piston crown, due to the high pressure gas in the combustion chamber, passes initially to the crankpin of a secondary crankshaft, then (and loading heavily the synchronizing gearing) it passes, through a set of bearings of higher speed, to the power shaft and to the load;

because of the difficulty in synchronizing the two halves of the "power shaft" (see the shaft 7 and the gearwheels 7A and 7B on it):



because of the heavy inertia loads on the "high speed" bearings by which the "secondary" crankshaft is rotatably mounted on the power shaft: these bearings support the assembly of the secondary crankshaft and of the piston (together with the balance webs on the secondary crankshaft);

because of the need for additional balance webs on the power shaft,
etc.



You also write:
“Rather than using counter weights, I would change the configuration to a 2 cylinder boxer engine. Greater power/kg”

The counter weights are secured on the crankshaft of the PatRon.

A 2 cylinder boxer also has counter weights on its crankshaft.

However, the balancing of a 2 cylinder boxer is, by far, worse than the balancing of a single cylinder PatRon.

Think of the inertia moment and of the inertia torque of the BMW boxer of a GS1200 wherein they had to put additional external counter-rotating balance shaft to take some of the vibrations.

In comparison, and as regards its inertia balancing (or "vibration free quality"), the PatRon is perfect; as perfect as the best reciprocating V-12 engines; as perfect as the Wankel rotary engine and the turbines.

Thanks
Manolis Pattakos

Hello all.


Here is a more “unconventional” PatRon for small airplanes, ultralights etc.:






It is an over-square direct injection Diesel with plenty of piston skirts.


With 120mm bore and 60mm stroke (about as over-square as the Ducati Panigale 1299) it gives a 2-Stroke capacity of 1,350cc.

The maximum dimension of the spinning cylinder is 1ft, i.e. the distance from the top of the one cylinder head to the top of the other cylinder head is only 305mm.


The scavenging is quite strange:

At some angle of the cylinder the piston opens the “leading” port and the pressure of the gas in the cylinder drops sharply.
Several (like 10 or 15) degrees later the piston opens the trailing port, too. The exhaust happens through both ports. Gradually the leading port becomes the intake port with the trailing port being the exhaust port:
The motion of the cylinder in the ambient air pushes air to enter from the leading port to scavenge the cylinder and then to exit from the trailing port.
After the BDC the pistons moves “upwards”; initially it closes the trailing port; the air entering the cylinder from the leading port continues to enter (due to inertia) until the piston closes the leading port, too.
The gas in the cylinder is compressed. Near the TDC diesel fuel is injected into the bowl at the center of the crown of the piston.
After the TDC it follows the expansion.
After the middle stroke the piston opens the leading port (it serves as exhaust port and as intake port) and so on.

I.e. it uses neither crankcase scavenging, nor some external scavenge pump.

If it works, it makes an extremely compact, simple and lightweight Diesel, which is also perfectly balanced, which also provides some 15% longer piston dwell at the TDC as compared to the conventional Diesels (the PatRon running at 5,000 rpm gives to the combustion as much time as a conventional Diesel running at 4,500rpm), and which eliminates the load between the piston skirts and the cylinder liner (the skirts are there only to seal the crankcase).

At 5,000rpm of the cylinder (i.e. at 10,000rpm of the crankshaft) it could make some 200bhp (i.e. as much as the Ducati Panigale 1299) because it is a 2-stroke.

As for its weight, 1/4 of the Panigale 1299 engine is reasonable.

As for its Brake Thermal Efficiency, it has all the characteristics for a top BTE.


This animation is explanatory:



(the same animation at slow motion is at http://www.pattakon.com/PatRon/PatRon_Model_2_Slow.gif )


Regarding the unconventional scavenging, it resembles to the way the Gnome and Rhone rotary engines (those with the ports on the cylinder liner) were running:





(more details at Page Not Found | The Vintage Aviator )

They were using the "exhaust" valve of a cylinder unconventionally: initially it was acting as an exhaust valve (during the last half of the expansion cycle and during the exhaust cycle), later (during the intake / admission cycle) it was acting as an intake valve allowing fresh "unfiltered" air to fill the cylinder; at the end of the inlet cycle rich air/fuel mixture was entering into the cylinder through the ports on the cylinder liner.



This version shows how compact the PatRon can be.

For a 1350cc 2-stroke double-acting-piston PatRon the external diameter of the rotating cylinder/cylinder head is only 1ft (305mm)

Applying the similarity, for a 50cc version the external diameter drops to 100mm. Think of a 50cc 2-stroke 2-“cylinder”engine for a chainsaw or for a model airplane having such a size.

Thanks
Manolis Pattakos

Hello all.

In the GIF video-animation here:



they are shown the spinning cylinder (it is from a Honda C-50), the spinning crankshaft (you can see its main journal spinning about a stationary axis, you can also see the crankpin of the crankshaft holding the piston rod that holds the piston head (which is also from a Honda C-50) that reciprocates inside the spinning cylinder.

In the following GIF_video_animation:



the piston have been removed to show the spinning crankshaft and the spinning cylinder.
The only orbiting thing in this video is the crankpin.


The previous GIF_videos at slow motion are at

http://www.pattakon.com/PatRon/PatRon_GIF_Video_1_Slow.gif

and

http://www.pattakon.com/PatRon/PatRon_GIF_Video_2_Slow.gif

Here is another GIF video-animation showng the spinning crankshaft and the orbiting-spinning piston (the piston head is from a Honda C50):



The same video-animation in slow motion is at http://www.pattakon.com/PatRon/PatRon_GIF_Video_3_Slow.gif

Thanks
Manolis Pattakos

Seems an interesting concept, but on a practical note how are you planning to manage intake and exhaust gasses? Moving seals do not tend to be the most reliable of devices.

As your official surface-area to volume troll, I like these! Questions:

In your opposed-cylinder two-head piston versions, I do not see the same perfect intrinsic balance as in your single-cylinder. You could, of course, build a rotating "boxer" with separate pistons, but the same epicyclic non-wobbling motion.

I trust it is there, but I do not se how the design is anchored to anything to take the torque reaction against output torque..Additional gearing not shown?

I think your ram-air scavenging would work, but also wonder how you would couple your orbiting ports to intake (for Otto cycle) and exhaust. For Diesel I suppose you could have a low-pressure rotary coupling for fuel feed and add a cam somewhere to operate a unit injector

I admire your creativity and powers of visualization.

As machinists we see lots of pretty pictures and latterly computer animations, and most of them are just that.
May I suggest you actually build an engine that works, ...........and tell us all about it.

Hello MagneticAnomaly

You write:
“In your opposed-cylinder two-head piston versions, I do not see the same perfect intrinsic balance as in your single-cylinder. You could, of course, build a rotating "boxer" with separate pistons, but the same epicyclic non-wobbling motion.”


I see the opposite:

Wthout the piston-balance-web of the single-acting piston, the double acting piston offers the same perfect balancing quality.

Because the one piston head acts as the piston-balance-web for the opposite piston head (or, more correctly, the one piston half acts as the piston-balance-web of the opposite piston half)).

Regarding the balancing of a PatRon with a double acting piston, this drawing:



shows, at top, a PatRon double acting piston rotatably mounted on the crankpin of its crankshaft. The crankshaft is at a random angle.

The center of the crankpin of the spinning crankshaft moves along the periphery Ps.
A point mass m on the, say, left piston head is picked randomly.

On the right piston head, anti-diametrically (relative to the center of the crankpin, which is also the center of the piston) it is taken another equal point mass m.

As the piston spins about the crankpin center, the two point masses move along a periphery Po having center at the center of the crankpin.

With the crankshaft spinning about its rotation axis and the piston (with its center on the center of the crankpin) moving parallel to itself, the left point mass moves along the periphery Ps1 circle (the radius of the Ps1 equals to the radius of the Ps which equals to 1/4 of the piston stroke), and the right point mass moves along the periphery of the Ps2 circle (same radius with the Ps1 and the Ps).


In the middle figure they are shown the velocities of the two point masses.

The left point mass m, moving along the periphery of the Ps1, has a velocity Vs1 (tangential to the periphery of the PS1). The same point mass moving along the periphery of the Po circle (spinning motion of the piston about the center of the crankpin) has a velocity Vo1 (tangential to the periphery of the Po). The sum of the two velocities gives the actual velocity V1 of the left point mass.

Similarly for the right point mass.

The velocity V1 of the left point mass is different than the velocity V2 of the right point mass in both: magnitude and direction.


In the lower figure they are shown the relative inertia forces.

Due to its motion around the periphery Ps1, the left point mass undergoes a centrifugal force Fs1 (this force “passes” from the center C1 of the Ps1).
Due to its motion around the periphery Po, the left point mass undergoes a centrifugal force Fo1 (this force passes from the center Co of the Po).
The sum of the Fs1 and Fo1 vectors is the total inertia force F1 the left point mass undergoes.

Similarly for the right point mass: it undergoes a centrifugal force Fs2 due to its motion around the periphery of the Ps2 circle and another centrifugal force Fo2 due to its motion around the periphery Po; the total inertia force the right point mass undergoes is F2 and is different (in both: magnitude and direction).

The previously mentioned forces Fs1 and Fs2 are equal in magnitude, they are parallel and they have the same direction; this gives zero total moment of these two forces about the center Co of the crankpin.

The previously mentioned forces Fo1 and Fo2 are equal in magnitude (the two point masses are at equal eccentricity from the Co and rotate with the same angular speed) and co-linear; this makes zero the moment of these two forces about the center Co of the crankpin.

By adding the two forces F1 and F2 at the center Co, the total force from the pair of the two masses is F. An equal and opposite inertia force -F is provided by a pair of spinning point masses on the balance webs of the crankshaft.

So, there is no way the motion of the two point masses to create an unbalanced inertia moment.

Taking one-by-one all the pairs of point masses constituting the double acting piston (each pair comprising two equal and anti-diametrically arranged point masses (anti-diametrically relative to the center of the crankpin)), the total unbalanced inertia moment is zero and the total unbalanced inertia force is zero too.

So, every configuration of the PatRon rotary engine (either it is based on single-acting piston(s) or on double-acting piston(s)), without external balance shafts, can be perfectly balanced no matter how many working chambers or cylinders it comprises.




You also write:
“I trust it is there, but I do not se how the design is anchored to anything to take the torque reaction against output torque. Additional gearing not shown?”


Things are simple:

During compression / combustion / expansion the bearings by which the cylinder is rotatably mounted onto the casing (the stationary part in the first animation of post #12) apply a force to the casing: the magnitude of this force equals to the gas pressure times the bore surface, the direction of this force is parallel to the cylinder axis the specific instance, the “point of application” of this force is at center of the cylinder bearing(s) which is a fixed point of the casing.

Similarly, during combustion compression / combustion / expansion the bearings by which the crankshaft is rotatably mounted on the casing apply another force to the casing; this force has the same magnitude with the force applied on the casing by the cylinder AND OPPOSITE DIRECTION; its “point of application” is at the center of the crankshaft bearing(s) which is another fixed point of the casing.

The distance of the above two application points is the distance of the two rotation axes (the one of the rotating cylinder, the other of the rotating crankshaft). This distance equals to 1/4 of the piston stroke.

Only at the TDC the two equal and opposite forces are co-linear (zero torque).
Before and after the TDC the two forces form a pair of forces which applies a torque on the casing.

This is the reaction torque you refer to.

Alternatively you can think how things work in the case of the Wankel rotary.

If the previous are confusing, please let me know to further explain.




You also write:
“I think your ram-air scavenging would work, but also wonder how you would couple your orbiting ports to intake (for Otto cycle) and exhaust. For Diesel I suppose you could have a low-pressure rotary coupling for fuel feed and add a cam somewhere to operate a unit injector”


There are many ways to pass the gas and the fuel.

However forget the rest versions and think of the direct injection Diesel in the post #12, for aviation use.

Bore: 120mm
Stroke: 60mm
Displacement: 1357cc
Expected peak power: near 200bhp at 5,000rpm of the cylinder (10,000rpm of the crankshaft).
(the peak power estimation is based on the 4-stroke Ducati Panigale 1299 which makes 205bhp at 10,500rpm of its crankshaft).

It is an extremely lightweight (without auxiliaries its weight will be less than 30Kg/65lb), compact (1ft /305mm maximum external dimension of the rotating cylinder), perfectly balanced, top fuel efficient (which means even lower take-off weight because for a specific range it requires less fuel), simple (there are three moving parts in total) and reliable engine, which is rid of thrust loads on the cylinder liners (a source of significant frictional losses in the state-of-art Diesels) and which is rid of loads on the synchronizing gearing and which minimizes its scavenging pumping loss.

Regarding the scavenging:

QUOTE from http://www.pattakon.com/pattakonPatRon.htm

“An example:

The combustion chamber is like a long room (say, a corridor) having a big window towards the north and another big window towards the south.
Outside the room it blows a strong wind coming from the north (this is what the rotation of the cylinder causes).
At the end of the expansion (a little after the middle-stroke) the north window opens. The pressure in the room is high.
The high pressure in the room pushes a big part of the "air" to exit from the north window and the pressure to drop sharply.
A little later the south window opens allowing gas to exit from that window too.
Due to the north wind, the flow from the north window gradually weakens, stops and reverses its direction, while the flow from the south window strengthens.
With both windows wide open (BDC), the strong north wind enters from the north window, scavenges the room (and cools down the walls, the ceiling and the floor of the room from within) and exits from the south window.
Later the south window closes, with the north window still open.
The wind continues to enter into the room from the north window (due to inertia / ram effect) overfilling the room with air (a kind of asymmetrical port timing: the exhaust closes before the transfer).
Finally the north window of the room closes trapping the air entered, and the compression starts.”

END OF QUOTE


In such an engine for small airplanes (and the similar) the only compromises are the induction of unfiltered air and the noise from the exhaust (which is lower than the noise from the propeller the engine drives).


Regarding the emissions, the above 2-stroke PatRon di Diesel for small airplanes has no reason to be worse than the state-of-the-art 4-stroke Diesel engines: due to the absence of thrust loads, the cylinder liner needs only a thin film of lubricant to prevent the metal-to-metal contact between the piston rings and the cylinder liner. This allows a specific lube consumption as low as in the 4-stroke di Diesels (Achates Power lab tests with their sided-located double-crankshaft prototype 2-stroke Diesel engines).
Without lubricant in the combustion chamber (read at http://www.pattakon.com/tempman/LubricationParticulateEmissionDiesel.pdf ) and with optimized injection and with optimized combustion bowl shape (which is rid of the limitation imposed by the poppet valves of the 4-stroke Diesels) the emissions have no reason to be worse than those of the 4-strokes.


Thanks
Manolis Pattakos

Limy Sami said:

As machinists we see lots of pretty pictures and latterly computer animations, and most of them are just that.
May I suggest you actually build an engine that works, ...........and tell us all about it.

Click to expand...

This guy knows!!!

I do admire your enthusiasm

Complexity didn't do in the rotary engines back in WW1... Precession did. How do you propose to deal with that?