26 replies to this topic

[manolis]

In the GIF animation of the PatPortLess engine below



the balance webs on the crankshaft (cyan), the (red) contra-rotating counterweight besides the crankshaft (at right), and the (red) contra-rotating small counterweights secured on the intake camshaft (at left) balance completely the first order inertia force without increasing the inertia torque.

The vibration-free quality of this single cylinder PatPortLess is better than the vibration-free quality of the four-stroke two-cylinder TwinAir engine of FIAT used in several successful small and medium size cars: the two engines have the same number of combustions per crankshaft rotation, but the PatPortLess has a better balancing (the single counter-rotating balancing shaft of the FIAT TwinAir engine cancels the first order inertia force in expense of a substantially increased inertia torque; this is why in engines like the Yamaha TDM it is used a pair of counter-rotating balancing shafts).

If the two-cylinder four-stroke TwinAir of FIAT is good, according the journalists / testers, for the new Alfa Romeo Mito, the single cylinder PatPortLess is better.

Any thoughts?


Longer piston dwell:

Unlike the conventional engines wherein the connecting rods are push-rods, the connecting rods of the PatPortLess are pull-rods: they are heavily loaded only in tension; the loads try to straighten / to unbend them (thinner and lightweight con-rods).

The PatPortLess arrangement shifts the combustion to the slow dead center.
In a conventional engine having a "connecting rod to stroke" ratio equal to 2, the crank angle during which the piston remains at the top 10% of its stroke is 66.2 degrees.
In a PatPortLess having a "connecting rod to stroke" ratio equal to 2, too, the crank angle during which the piston remains at the top 10% of its stroke is 83.9 degrees.

At the same revs (rpm), the piston of the PatPortLess remains in the top 10% of its stroke for 27% more time than the piston of the conventional (83.9/66.2=1.27).

Equivalently, when the PatPortLess operates at 27% higher revs than the conventional, the pistons of both remain in the top 10% of their strokes for the same time. For instance, when the abovementioned PatPortLess operates at 6000 rpm and the abovementioned conventional operates at only 4.750 rpm (=6000/1.27), the pistons of both remain in the top 10% of their strokes for (83.9/360)*(60/6000)=0.00233 seconds.

For lower "connecting rod to stroke" ratios, things get worse for the conventional.
For shorter intervals near the CTDC (say 5% of the piston stroke instead of the 10% used in the previous comparison), things get worse for the conventional.

In a reciprocating engine having 15:1 compression ratio:
when the piston has covered 5% of its stroke moving away from the Combustion TDC, the "remaining" expansion ratio has drop to 8.8:1; any quantity of fuel burned at that moment would undergo an expansion ratio of 8.8.
when the piston has covered 10% of its stroke moving away from the Combustion TDC, the "remaining" expansion ratio has drop to 6.25:1; any quantity of fuel burned at that moment would undergo an expansion ratio of only 6.25.

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

Thanks
Manolis Pattakos

[Lee Nicolle]

No

[SenorSjon]

No. I've driven the two cilinder Panda and didn't like it one bit. I prefer 4 cilinders on my motorbike as well, so no 1 or 2 cilinder engines, I would consider 3.

[paipa]

I have no objections in principle. I'd love to test it for the novelty and who knows then.

[Catalina Park]

I would give it a go.

[Johan Lekas]

Yepp! I love unconventional solutions 

[Sisyphus]

Looks like a lot of cranks and counterweights and things turning around for a single cylinder.  And the ports to get the fuel/air mixture into the 4 intake valves around the crank must look interesting.

[desmo]

Shades of the Gnome et Rhone (hope I got that right) monosoupape eh.

[rory57]

Straight six at least before I'll buy.

[Magoo]

[manolis]

Hello all and thanks for your replies.

With their two cylinder TwinAir engine, FIAT / Alfa Romeo proves in practice that one combustion per crank rotation is adequate for small / medium size cars.

Quote from Autocar for the 2014 Alfa Romeo Mito TwinAir 105 bhp:
“You can forgive the TwinAir’s noise and vibrations up to a point, because it is one of the most characterful engines around with a sound that almost begs you to drive it that little bit harder. The problem is that when you do, you quickly run out of revs and into a soft limiter just short of the indicated 6000rpm redline.”


VW 1.4-litre TSI ACT (cylinder deactivation system) was voted at the Engine Expo International as the “Best New Engine” of 2013.
Quote from the Internet:
“Temporary shutoff of the second and third cylinders – in conjunction with an economical style of driving – reduces fuel consumption by over 0.5 liters per 100 kilometers.
Even with two cylinders the excellently balanced 1.4 TSI runs just as quietly and with low vibration as with four active combustion chambers.”

The consumption reduction comes from the fact that the two active cylinders of VW operate at substantially heavier load when the two others are deactivated.
At light loads the efficiency of the spark ignition engines drops a lot.
The bad thing with VW’s solution is that the deactivated cylinders still have pistons and piston rings reciprocating inside them consuming energy as friction.
If the two deactivated pistons could be removed, the reduction of the fuel consumption would double (?), as well as the vibrations and the noise.
The “cylinder deactivation” in Diesels is not so good because the friction of the idle cylinders is bigger and because the thermal efficiency of the Diesels at partial loads is not bad.

The single cylinder PatPortLess has similar inertia vibrations with the four-in-line of VW. The first order inertia forces are full balanced in both, the inertia torque is “similar”, the unbalanced second order inertia forces are similar, too.

When the VW engine operates at partial loads, it pays its vibration-free quality / smoothness / quietness by the friction (mechanical energy loss) of moving a pair of “useless” pistons / sets of piston rings.
In the PatPortLess engine the only that is added is the big counter-rotating counterweight. The added friction / weight / cost is substantially lower in comparison.

The number of combustions per crank rotation is the same when the VW runs at partial loads.

According the:
“Even with two cylinders the excellently balanced 1.4 TSI runs just as quietly and with low vibration as with four active combustion chambers”,
the single cylinder PatPortLess fits for the propulsion of small / medium size cars.


There are already on the roads good / respectable cars having two cylinder engines (like the TwinAir of FIAT or like the VW TSI ACT at partial loads).

The reasonable next (and final?) step is cars having engines with one only cylinder.
The two-stroke engines had, so far, significant problems with the lubrication, the reliability and the emissions.
Do you see such problems in the PatPortLess?
If not, why not a car with a single cylinder di Diesel PatPortLess?



Desmo wrote: “Shades of the Gnome et Rhone (hope I got that right) monosoupape eh.”

Not necessarily monosoupape.
Here is the version with four intake valves on the piston crown:



It is a two-cylinder even-firing flat full-balanced (as full-balanced as the OPOC of EcoMotors). All the counterweights are either on the crankshaft or on the two intake camshafts (i.e. no need for additional "external" balancing shafts).

SenorSjon, isn’t this better than the four-in-line?

The first animation at http://www.pattakon....PatPortLess.htm is the single cylinder version with four intake valves on the piston crown (there is also a windows exe animation of it).

Desmo, is there any drawing / picture of the « inside » of Gnome et Rhone?



Johan Lekas : YEIA SOY PATRIDA.



Sisyphus wrote:
“And the ports to get the fuel/air mixture into the 4 intake valves around the crank must look interesting.”

There are no intake ports.
The cylinder head has only exhaust valves.
Do you know the Detroit Diesel (later GM) cylinder heads with the four exhaust valves and the centrally located fuel injector?
A Detroit-Diesel cylinder head can be used for the PatPortLess.

Question:
When the loads (from combustion and inertia) are taken with a pair of parallel connecting rods, is the friction increased?
Suppose you slice the connecting rod of a conventional engine in two thinner connecting rods that remain side-by-side. Is the friction increased?



Sisyphus wrote:
“Looks like a lot of cranks and counterweights and things turning around for a single cylinder”.

This is not an ordinary single cylinder.
Quote from www.pattakon.com for PatPortLess:
With the cylinder-liner rid of intake and exhaust ports, this engine combines:
true "four-stroke" lubrication,
true "four-stroke" specific lube consumption,
true "four-stroke" scuffing resistance,
uniflow scavenging efficiency,
double valve-area and
some 30% longer piston dwell at the CTDC (Combustion Top Dead Center).

With the built-in piston-type supercharger, a good volumetric efficiency in a wide range of revs can be achieved (as wide as in the four-stroke engines).

Thanks
Manolis Pattakos

[Greg Locock]

I don't think the firing frequency is going to be much different to any other engine with that cylinder size, so the difference in refinement will be largely due to inertial forces.

 

NVH engineers cope, albeit unhappily, with I4 engines which typically run about 20g rms, second order, at 6000 rpm. block vibration. Most of that is L/r related inertial.

 

Do you have calcs or measurements for block vibration for this thing?

 

There is a significant potential market for quiet efficient compact IC engines in EREVs.

[manolis]

Hello GrecLocock.

The total second order inertia force of the I4 is four times the second order inertia force of the single (for same pistons, same con-rods, same stroke).

The total second order inertia torque of the I4 is also four times the second order inertia torque of the single.

I.e. when the 1st order inertia force of the single is removed (without increasing the inertia torque), the single and the I4 are quite similar in NVH as regards their inertia vibrations (for instance when the two engines are driven without load). The only difference is the small 3rd order inertia torque of the single (which is cancelled in the I4 by the other cylinders).

I think there is no need for additional calculations.


Desmo: I found a picture of the Gnome et Rhone mechanism (the intake valve is on the piston crown):



The intake valves open and close automatically.
Mixture of air, fuel and lubricant comes from the crankcase and through the intake valve enters the cylinder.

In the PatPortLess the idea is the opposite: to separate the lubricant from the air / air-fuel mixture.
In a di (Diesel or spark ingition) PatPortLess the air "sees" no more lubricant than what the air in the conventional 4-stroke engine "sees".
I.e. the idea in the PatPortLess is to combine the advantages of the two-stroke engines with those of the four-strokes.

Thanks
Manolis Pattakos

[Bob Riebe]

Medium size car?

 

Do you mean a U.S.  medium size car now reduced to the size of a Chevy II, or something  the size of a Mazca Mizer ?

Edited by Bob Riebe, 11 December 2013 - 21:32.

[Greg Locock]

I'd be chasing the EREV market then.

[manolis]

Medium size car?
Do you mean a U.S. medium size car now reduced to the size of a Chevy II, or something the size of a Mazca Mizer ?

I mean a car like:

the mentioned Alfa Romeo Mito TwinAir (Length: 4063mm, Width: 1720mm, Height: 1446mm, Weight: 1130 Kg empty),

or

like the mentioned VW POLO TSI ACT (Length: 3976 mm, Width: 1682mm, Height: 1462mm, Weight: 1212 Kg empty).

In cars of this size and weight, it is already acceptable by the typical owner / driver / tester the operation with only one combustion per crankshaft rotation.


Thanks GregLocock.


According the previous posts it seems that if the two-cylinder four-stroke TwinAir engine of the Alfa Romeo Mito were replaced by a (compact and lightweight) single-cylinder two-stroke di-Diesel PatPortLess, the driver / passengers would notice a decrease of the vibrations / noise.

The Diesel (compression ignition) fits better with the two strokes because a Diesel engine operates permanently on lean burn (from very lean at idling / light-loads, to lean at medium / heavy loads).

Thanks
Manolis Pattakos

[bigleagueslider]

I would consider buying a new car with a single cylinder engine if a good technical case could be made in favor of the single versus multi-cylinder engines.  I doubt such a case could be made in overall terms of cost, fuel economy, performance, etc, but I'd be willing to listen.

[manolis]

I would consider buying a new car with a single cylinder engine if a good technical case could be made in favor of the single versus multi-cylinder engines. I doubt such a case could be made in overall terms of cost, fuel economy, performance, etc, but I'd be willing to listen.

Hello Bigleagueslider.


Fuel economy:

The conventional di Diesels are the most efficient engines today (40-45% BTE in the big trucks, more than 50% in the giant marine engines).

The Diesel has a higher friction mean effective pressure (FMEP) than a “similar” spark ignition engine; on the other hand, the Diesel keeps a better brake thermal efficiency (BTE) at partial loads than the spark ignition.

The cylinder deactivation (VW TSI ACT) is not good for the Diesels because their friction is bigger and because a better thermal efficiency than the spark ignition is maintained at partial loads.

The same reasoning explains why most hybrids have spark ignition engines.

As a two-stroke, a PatPortLess di Diesel has substantially lower friction than a four stroke Diesel of the same displacement. It completes its operation in a reciprocation of the piston and not in two of the four-strokes.
As for the lubrication – emissions - reliability (the Achilles’ hill of the two-strokes), the PatPortLess is as good as the four-strokes: true four-stroke lubrication, true four-stroke lube-consumption, true four-stroke scuffing-resistance.

The sub-square design of the PatPortLess improves the through-scavenging; it also keeps small the “surface to volume” ratio that further improves the BTE (and the fuel economy).

If there are no objections to the previous, when a single cylinder di Diesel PatPortLess replaces the engine of a medium size car like the VW POLO TSI ACT (or like the Alfa Romeo Mito TwinAir), the fuel consumption will drop substantially.


Cost:

I tried, but I can’t see how the cost of a single cylinder PatPortLess can be higher than, or comparable to, the cost of a 4-stroke multicylinder of similar power.

The number of parts decreases, the weight and the dimensions decrease.

Which part of the PatPortLess seems so expensive to justify a cost comparable to the cost of multicylinder 4-stroke engines of similar power output?


Performance:

With the built-in piston-type volumetric scavenging pump the PatPortLess can operate either as a supercharged di Diesel, or as a turbocharged di Diesel (see at http://www.pattakon....P.htm#CrossHead ) or as a turbo-super-charged di Diesel.

Taking under account the high revving ability of the PatPortLess (additional time at the CTDC for efficient combustion, low friction), what I see is more power than a 4-stroke having the double capacity.

For instance, the 1.6 D2 4-stroke Diesel of Volvo makes 115 bhp at 3600 rpm, which means a specific power of 72 bhp/lt at 3600 rpm.

Multiply this specific power by 2 (because the PatPortLess is a two stroke engine), then multiply it by 1.3 (30% higher revs because there is a substantial delay at the CTDC) to get 187 bhp/lt.

Theoretically, a 635cc single cylinder PatPortLess (say 128mm stroke, 79.5mm bore as in the animation) can make 118 bhp at 4700 rpm.
Practically, say more than 100 bhp with di Diesel fuel econimy.

Judging from the 20 Kp weight of the 635cc PaTOP di Diesel prototype (at http://www.pattakon....ttakonPatOP.htm ) :



a PatPortLess of the same capacity has no reason to be more heavy than 25 - 30 Kp.

Doesn't a powerful lightweight and compact engine mean better performance?


Thanks
Manolis Pattakos

Edited by manolis, 14 December 2013 - 07:53.

[indigoid]

If you could package it appropriately, a lightweight ~100bhp diesel single with improved NVH would be great for dual-purpose/adventure motorcycles IFF it could lead to substantially improved mileage (not just enough to compensate for diesel fuels being heavier than gasoline) and thus range

 

Some prior art (personally I think 220kg is too much for this kind of bike):

 

http://www.motorcycl...Quick-Ride.aspx

 

 

We've previously discussed aero being a major efficiency blocker with pretty much all bikes, so achieving a substantial step forward is probably going to be difficult. There's lots of options out there for putting bigger fuel tanks on adventure bikes, but they mostly add substantial weight and often add it in poor locations - too high and too far forward.

[Kelpiecross]

Diesel motorbikes are apparently fairly common in India - the Royal Enfield diesel does over 200mpg.

[Powersteer]

vibrations, they attract woman so I would not mind a single cylinder e-class

 

[manolis]

According a link of bigleagueslider post in another thread,

"Volkswagen of America will introduce the Passat BlueMotion Concept at the 2014 North American International Auto Show in Detroit next week. Based on the current Passat that was developed specifically for North America, the BlueMotion label defines the version that has the best efficiency in the model lineup. In this case, the Passat BlueMotion Concept has a manufacturer-estimated highway fuel economy of 42 mpg (5.6 l/100 km), best-in-class among non-hybrid, gasoline-engined mid-size sedans.
The Passat BlueMotion Concept features an all-new version of the Volkswagen 1.4-liter EA211 TSI engine with direct injection and turbocharging. (Earlier post.) Additionally, this Passat also offers Active Cylinder Management (ACT) technology, previously seen on the European Volkswagen Polo and Golf models."


The engine of this car (length over 4.5mm, empty weight ~ 1400 Kg) is the same VW 1.4 TSI ACT engine mentioned in the previous posts. At light loads the two middle cylinders are deactivated.

It seems that "one combustion per crankshaft rotation" goes beyond the small-medium size cars.

It seems that the two middle cylinders of the VW 1.4 TSI ACT engine are the only ones that are deactivated.
Questions:
What is the long-term effect on the engine after, say, 100.000 miles?
Is it clever to operate at heavy load the two “worn” cylinders and leave the actually “unused” pair of cylinders idle?
Does it reduce the TBO?

Thanks
Manolis Pattakos

[gruntguru]

I would suspect not.

 

Wear is minimal during normal operation (as opposed to cold start and warm up). In addition the difference in wear between a cylinder when lightly loaded vs moderately loaded is very slight. The motored cylinders should suffer either.

 

Manolis. Is the torque theta curve of your 2 stroke single, similar to that of a four stroke twin?

[JAW]

 Think maybe most buyers don't know or care what mill is doing the work these days, unless it is too obviously obnoxious..

 

& higher B.M.E.P. is an inherent 2T advantage..

[manolis]

I would suspect not.
Wear is minimal during normal operation (as opposed to cold start and warm up). In addition the difference in wear between a cylinder when lightly loaded vs moderately loaded is very slight. The motored cylinders should suffer either.
Manolis. Is the torque theta curve of your 2 stroke single, similar to that of a four stroke twin?

Hello Gruntguru.

With the two deactivated cylinders running on pure air and without compression(?), the conditions for the cylinder liner, the piston rings, the piston skirt, the piston pin, the crankpin, the valves, the cam lobes(?) etc are quite different.
Also the lubrication is different. How much lubricant is left, by the oil scraper rings, to enter the cylinder with and without load? (for instance, with and without subpressure / vacuum in the cylinder during the suction stroke).

I don't bet, yet I expect in the next couple of years VW to upgrade their ACT system in order to be capable of changing from time to time the pair of deactivated cylinders, so that the wear among cylinders be balanced and the reliability of the engine be maximized.


The inertia torque vs. the crank angle is slightly different between the balanced PatPortLess and the conventional straight four.

The Fourier analysis of the inertia torque says that:

both have zero 1st order inertia torque (while the conventional single has a 13% -relative to the 2nd order- 1st order inertia torque, the PatPortLess has zero: the "center" of the two counter-rotating counterweights is properly offset from the crankshaft center).

the single cylinder PatPortLess has a 38% -relative to the 2nd order- 3rd order inertia torque, which is absent in the straight-four.

both have the same 4th order inertia torque (3% relative to the 2nd order).

By the way, the unbalanced inertia force in both engines is pure 2nd order.


Despite the 3rd order inertia torque of the PatPortLess, its overall unbalanced inertia torque is substantially smaller than the unbalanced inertia torque of the straight-four of VW 1.4 TSI ACT because the total reciprocating mass of the straight-four is bigger (the one engine is 4-stroke, the other is 2-stroke).

I.e., at partial loads (urban cycle, for instance) the noise and the vibrations (NVH) inside the VW Passat 1.4 TSI ACT would reduce if the straight-four VW engine were substituted for the single cylinder PatPortLess.
Sounds bizarre, yet it is so.

Then it comes the fuel efficiency: the straight four has a lot of additional friction as it drives a pair of inactive pistons (piston rings etc). The active pistons burn once per two crank rotations (four-stroke friction vs. two-stroke friction).

If instead of the straight-four, a two-cylinder was used (FIAT solution), the fuel economy would improve.

The inertia torque of the two-cylinder FIAT TwinAir engine (FIAT 500, Alfa Romeo Mito etc) comprises a heavy 1st order component (offset from the crankshaft center of the single counter-rotating balancing shaft of the FIAT), which makes the PatPortLess a substantially better balanced engine.



Hello JAW.

You are right: "most buyers don't know or care what mill is doing the work".

So, if the next VW Passat was powered by a single cylinder two-stroke PatPortLess, "would you consider buying it"?


Thanks
Manolis Pattakos

[JAW]

No, but I drive M-B..

 

Mind you  - my mean Toyota company hack buying employer - might..

[JAW]

I should add, I do prefer 2-strokes, & own only 2-stroke motorcycles,

& would buy a high performance 2-stroke car..