6 replies to this topic

[manolis]

Today the United states patent office granted the US9,022,005 for the PatRE rotary engine:



For more: http://www.pattakon....takonRotary.htm


It is a four-stroke engine (as the Wankel Rotary).

In small size (model engine / RC engine) it doesn’t need sealing rings (or seals), just like the ring-less RC engines.

In normal size it needs seals, like the Wankel rotary. But in the PatRE the seals have surface contact, and not line contact (as the apex seals of Wankel rotary).

In comparison to Wankel rotary, the PatRE needs not synchronization gearing.

With four combustions per shaft rotation, it appears as having a built-in revs reduction (in comparison, the Wankel rotary makes only a combustion per rotor per power-shaft rotation).

Do you know a more free-breathing engine?

Thoughts?

Objections?

Thanks
Manolis Pattakos

[gruntguru]

Ingenious.

[manolis]

Hello.

Today it was granted and the GB2,498,372 patent:



from the UK-IPO for the PatRE rotary engine.

Anybody to compare the PatRE with the Wankel Rotary for aviation applications?

Thanks
Manolis Pattakos

[Kelpiecross]

It certainly is very clever - it appears to be the only application of the Hooke's joint to this type of "cat-and-mouse" engine (see USPTO CCL/123/18R). However (there's always a "however") as the "C-A-M" drive is only really novel thing about the whole engine I wonder if there are better ways to achieve the required "C-A-M" action. Presumably to produce a similar amount of power at similar RPM as a conventional engine - the CAM engine would have similar piston accelerations and combustion loads etc. as a conventional engine. The various arms etc. on the Hooke's joint appear to be a bit complex and flimsy to work reliably in this application. Compare the PatRE to this experimental engine:



The equivalent of the connecting rods and crankpins etc. in the above engine are comparable in size and strength to those in a conventional engine - I would guess that the CAM engine in the video is a better design than the PatRE.
And even if the PatRE (or the engine in the video) can be made to work in a reliable fashion - what would be the advantages of CAM engine
over a conventional engine? The CAM engine would have sealing problems, its piston speed (especially on the outside) would be very high. I don't see why it would have a notably better TE or power output than a conventional engine.
I am not even sure this type of engine can be truly called a "rotary" engine. I think for an engine to be called a "rotary" engine the pistons should not undergo high cyclic accelerations etc. which limit maximum RPM and cause vibrations etc.
So - the PatRE and the video engine and all other CAM engines - many more problems and disadvantages compared to a conventional engine and no apparent advantages that I can see.

Edited by Kelpiecross, 05 May 2015 - 04:46.

[gruntguru]

Advantages?

- Balance

- Zero inertia torque

- No valves

- Compact

 

As to piston accelerations etc - this engine is more like an opposed piston design where the two pistons are always accelerating in the opposite direction. The PAT version would be pferrable IMO due to its lack of gears. The yokes could easily be designed to handle the forces involved.

 

Piston cooling may be an issue?

[manolis]

Hello Kelpiecross.

You write:
“And even if the PatRE (or the engine in the video) can be made to work in a reliable fashion - what would be the advantages of CAM engine
over a conventional engine?”

The free breathing (freer than Wankel rotary – see the size of the ports as compared to the capacity of the combustion chambers).
The absence of free (unbalanced) inertia forces.
The light-weight and compactness.
The simplicity (no camshafts, no valves, no timing mechanism, not even a gearwheel in its structure) and the consequence reliability.
The built-in revs reduction and synchronization of the two counter-rotating propellers (see below).

Again: the lightweight and the compactness and the simlicity and the "direct" drive of the load (propellers) which are vital for a Flyer.


You also write:
“The CAM engine would have sealing problems, its piston speed (especially on the outside) would be very high. I don't see why it would have a notably better TE or power output than a conventional engine”

In the PatRE rotary engine the rotor-pistons are not thrusting on the casing.
Only the sealing rings (if any; in small sizes, like for model engines, the ring-less design is the case) thrust on the inner surface of the cylindrical casing.

Is their speed “very high” as you write?

Take a four-in-line four-stroke conventional engine (the PatRE is a four-stroke engine, too; and its has four independent chambers / "cylinders", too).
To complete a cycle of operation in each cylinder, it requires two crankshaft rotations and eight complete reciprocations of a “piston / piston rings” set. The inevitable trust between pistons and cylinder-liners causes significant friction loss.

In the PatRE, in one only rotation of the rotor-pistons it is completed a combustion per combustion chamber.
If you have the same capacity per combustion chamber with the 4-in-line 4-stroke mentioned above, and in order to make the same power, you need half rpm (which is also favorite for the propellers, too; the kinematic mechanism of the PatRE, which is completely rid of gearwheels, is a built-in revs reduction and a synchronization mechanism, too).

Alternatively, in order to take the same power at the same revs with the conventional reciprocating 4-stroke engine, the required capacity of the PatRE is half.

Please rethink about the “very high speed” issue.


You also write:
“The various arms etc. on the Hooke's joint appear to be a bit complex and flimsy to work reliably in this application.”

The two double Cardan (or Hooke) joints at the sides of the PatRE engine can be resized / reinforced as required; if you want to keep the central part of the engine as is, and double the size of the two double Cardan joint, you can without a problem.

On the other hand, is the Cardan joint structure flimsy? (the power of a truck passes to the wheels through Cardan joints).

Thanks
Manolis Pattakos

Edited by manolis, 06 May 2015 - 03:49.

[manolis]

Hello Gruntguru.

Zero inertia torque?

No.
The following plot is explanatory:



The oscillation of the total kinetic energy of the two rotor-pistons causes an unbalanced inertia torque.


About the piston cooling (and the overall cooling).

I think the problem is with the cooling of the casing at the area of the glow (or spark) plug and not with the cooling of the pistons.
Yet things are easier than in the Wankel rotary because during combustion in the PatRE the area of the casing exposed to the burning gas is way smaller and because the combustion into the compact combustion chamber of the PatRE completes sooner.

As in the Wankel rotary and as in the conventional reciprocating engine the rotor-pistons of the PatRE see alternatively cool gas (intake, compression), then hot gas (combustion, expansion, exhaust).
If necessary, the rotor-pistons can be cooled internally by the lubricant.


On the other hand, the lightweightness and compactness of the PatRE gives another interesting option.

Suppose you extend a lot the intake port closing towards the combustion chamber.
Air of mixture from the intake manifold gets, through the intake port, during the suction period (wherein the volume in the chamber increases).
During a significant part of the compression period the gas "finds" the intake port still open; a large part of the entered fresh gas returns back to the intake manifold (the aerodynamic resistance if negligible).
Finally the intake port closes by the "following rotor-piston" and the actual compression starts.
Suppose you reject, back to the intake manifold, the 4/5 of the entered charge.
What you have is a "heavy" Atkinson - Miller cycle (the Toyota PRIUS Hybrid operates in a limited Atkinson - Miller).

The maximum temperature and pressure of the cycle drops a lot.
The temperature of the rotor-pistons and of the casing drops a lot, too.
The gas leakage drops also.
With a high expansion ratio the fuel efficiency is high.
To realize a high expansion ratio (like 20:1 or higher), is the easiest thing to do in the PatRE.


That is,
instead of exploiting the lightweightness of the PatRE in order to achieve top power density,
we can alternatively exploit its lightweightness and free breathing to achieve high thermal efficiency with a thermodynamic cycle limited in substantially lower temperatures and pressures than in the conventional engines.

Thanks
Manolis Pattakos