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PatATE: Asymmetric Transfer and Exhaust in two-stroke engines

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Hello all.

Here is an unconventional two-stroke (the PatATE) in comparison to a conventional two-stroke:

PatATE_1.gif

The main difference is that the exhaust port is now a "hybrid" port (the 4): at the end of the expansion the valve 7 connects the hubrid port with the exhaust passageway 5, and the exhaust starts the conventional way.

Later the valve 7 opens the transfer passageway 6 and seals the exhaust passageway 5; the exhaust continues through auxiliary (and "lower") exhaust ports 8; the transfer uses the conventional (symmetrical) transfer port 9 and the hybrid port 4.

Later the piston closes the conventional transfer port 9 and the auxiliary exhaust ports 8. 

In the conventional two-stroke the exhaust remains open for several degrees (while the transfer is closed). In the PatATE the transfer continous (while the exhaust is closed). Regarding the operation of the engine, it looks like a significant difference.

Here are some more drawings / graphs:

PatATE_2.gif



PatATE_3.gif


PatATE_4.gif

PatATE_5.gif

PatATE_6.gif
 

In the following animation it is a PatATE having a rotating  (sleeve?) valve to control the hybrid port from outside (the rotary valve does not deal with the high pressure; the sealing of the high pressure is realized by the piston, the piston rings and the cylinder liner as in the conventional 2 and 4 stroke engines) :

PatATE_Rotary_Anim_6_Half_Speed.gif

The speed of the rotary valve (red) is half the speed of the crankshaft.

Besides the asymmetric transfer and exhaust, the rotary valve (red) gives asymmetric intake, too, without reed valves or conventional rotary/drum valves.

 

In the follwoing animation the rotary valve spins at crankshaft speed:

PatATE_Rotary_Single_Anim_1_small.gif

Here is the timing plot:

PatATE_Rotary_Porting.png

 

The valve controls the asymmetric intake, too (no need for reed or typical rotary or drum valves for the control over the intake).

The above timing in comparison to a conventional 2-stroke (Yamaha RD350LC'86):

 

PatATE_vs_RD350LC_porting.png

 

In the PatATE the exhaust (red curve) starts opening 10 degrees later than the exhaust of the RD350LC (green line), however the port area increases at a substantially faster rate (about double), allowing a substantially faster blowdown.

In the PatATE the exhaust closes substantially earlier than the transfer (blue curve) preventing fresh fuel to be lost in the exhaust.

In the PatATE the same port (the hybrid port) is used for the exhaust during a portion of the cycle, and for the transfer for another portion of the cycle, which among others means about half temperature of the hybrid port bridges as compared to the "red" hot bridge of the exhaust port of the conventional 2-strokes. It also means substantial reduction of the specific lube consumption (substantially higher fuel to oil ratio without the fear of scuffing).

With the exhaust closing far earlier (some 50 crank degrees earlier than the exhaust in a conventional 2-stroke), the 2-stroke PatATE can be far greener and pass the emissions regulations.

 

The discussion started at 

but I was asked to open a new thread.

 

For more: http://www.pattakon.com/pattakonPatATE.htm and  http://www.pattakon.com/pattakonPatAT.htm

 

Thanks
Manolis Pattakos

Edited by manolispattakos
corrections to drwawings

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Hello all.

Here is the valve lift versus the crankshaft angle of several older 4-stroke Ducati engines:

4stroke_Ducati_timing.png

For each of the above 4-stroke Ducati engines, the exhaust valve opens at 90, or so, degrees before the BDC. 
Similarly for their intake valves: they close at 90 degrees, or so, after the BDC.
 

Adding to the previous graph the curves from the following plot:
 

PatATE_vs_RD350LC_porting.png

 

it results this graph:

2stoke_vs_4stroke_timing.png

Compare the pair of the red and blue curves (drawn by bold line) at left (2-stroke PatATE, exhaust and transfer opening versus the crankshaft angle) with, say, the pair of curves “G Corsa EX” (thin cyan line at left) and “G CORSA IN” (thin dark-cyan line at right) of the Ducati “G-Corsa”.

Then spot on the left pair of curves for the Yamaha RD350LC conventional 2-stroke: dark-green bold line for the exhaust, yellow bold line for the transfer, with the exhaust closing more than 30 crankshaft degrees after the transfer (and a rate of opening (blowdown) for the exhaust substantially lower than that of a PatATE having "softer" timing).


Aren’t the PatATE curves quite different than those of the conventional RD350LC 2-stroke?

Aren’t the PatATE curves more similar to those of the, say, 4-stroke Ducati G-Corsa? 


This is what the PatATE brings to the 2-stroke engines: a completely different (and relatively similar to 4-strokes) way for the gas exchange.

Thanks
Manolis Pattakos

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Hello Ossagp

You write: "Is there a working model?"

 

Not yet.

 

The most relevant to the PatATE prototype we have made, is the proof of concept prototype of the pattakon PatATi Opposed Piston:

PatATi_OP_full.gif

 

 

 

It is a 800cc (80mm bore, 80+80=160mm stroke), single cylinder, loop scavenged (not through scavenged), perfectly balanced Opposed Piston with compact combustion chamber, asymmetric intake and asymmetric transfer.

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

Thanks

Manolis Pattakos

 

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That looks pretty cool. What is the means of lubricating the rotating sleeve in the cylinder? 

 

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Many years back (in the 1970's), we experimented with rotating barrels (2S), and rotating shutter valves (4S). Too much wear and sealing issues like with a rotary, which had much less critical sealing points.

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looks like you are adding complexity for the sake of efficiency.  One of the "charms" of two strokes is limited number of moving parts.

does this design move a two stroke closer to the theoretical doubling of the HP of a similar sized 4 stroke, that would be something.  

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On 10/18/2017 at 11:19 AM, Dirt Hokie said:

looks like you are adding complexity for the sake of efficiency.  One of the "charms" of two strokes is limited number of moving parts.

does this design move a two stroke closer to the theoretical doubling of the HP of a similar sized 4 stroke, that would be something.  

From the looks of the port sizes and path the mixture take I don't think they'll be performance engines. More the like the Stihl 4 mix motors or husqvarna x torque, good for power eqpt but maybe not bikes?

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