2 stroke thread (with occasional F1 relevance!)

[PlatinumZealot]

Hello PlatinumZealot.

You write:
"I understand your system...


Explaining the patVVD:

The cyan part is the cam shaft whereon a cam lobe is pivotally mounted; the cyam cam shaft rotates at constant angular velocity.

The patVVD mechanism (not shown here***) causes a fluctuation of the angular velocity of the cam lobe along a camshaft rotation.

https://www.pattakon.com/VVD/PatVVD_explained.gif

(slow motion at https://www.pattakon.com/VVD/PatVVD_explained_slow.gif )

The animation has a slide per 6 degrees of camshaft rotation (or per 12 degrees of crankshaft rotation).

At a first position of the control pin (not shown) the camlobe (shown red in this case) rotates slowly when its nose passes over the "for more: www.pattakon.com" label (at bottom), and quickly when its nose passes over the "patVVD : pattakon CVVD" label (at top).

At a second position of the control pin, the camlobe (shown blue in this case) rotates quickly when its nose passes over the "for more: www.pattakon.com" label (at bottom), and slowly when its nose passes over the "patVVD : pattakon CVVD" label (at top).

If the valve actuator were where the bottom label is, the valve duration with the control pin at its first position (cam lobe red) would be more than 70 camshaft degrees longer than with the control pin at its second position (cam lobe blue).”

***the mechanism is explained by a windows “exe” animation at thebottompf the https://www.pattakon.com/pattakonVVD.htm web page.



You also write:
"But man your assembly drawings are hard to read!"

They are not "assembly drawings".
They are "patent drawings".
Isn't the "single cylinder" simple and simple to get?


By the way:

the PatRoVa rotary valve :

https://www.pattakon.com/PatRoVa/PatRoVa_Taper_3B.gif

is by far simpler,can be variable, and has a few times higher rev limit than the patVVD,

while the DVVA (desmodromic VVA):

https://www.pattakon.com/DVA_files/DVVA_height.jpg

is way more variable and has substantially higher rev limit than the patVVD.

But as compared to

"Hyundai’s Breakthrough Engine that Answers a 133-year Challenge"!! (more at theirofficial web page at : https://tech.hyundaimotorgroup.com/arti ... challenge/),

the patVVD has significantl differences and advantages.

Thanks
Manolis Pattakos

Very impressive. What did you think when Hyundai announced their production ready design?

[PlatinumZealot]

A lot of sliding friction in those slots although the Rover system has been around for 24 years and seems reliable.

Rover had continuosly variable valve duration adjustment? Really? That's news.

[gruntguru]

Yes eg 1.8 VVC 1995. https://www.youtube.com/watch?v=mKlB8zDI3PA

Hyundai has pretty much copied it and somehow managed to get a patent issued.

[manolis]

Hello PlatinumZealot

You write:
“What did you think when Hyundai announced their production ready design?”


At first glance it appeared as “great news”: a big car maker, Hyundai, making a true step ahead.

But understanding their design and, worse even, reading their arrogant claims like “Hyundai’s Breakthrough Engine that Answers a 133-year Challenge” etc, several questions arise.

Hyundai Motor Company is the assignee of the following set of US-patents US8,813,704, US9,512,748, US9,822,674, US9,850,789, US9,856,758, US10,174,643, US10,533,464 that cover “their” CVVD.
The same “patent examiner” granted all, except the last one.
This “patent examiner” generously grants patents to car makers, and refuses – based on arguments against the common sense and human reasoning - patents to independent inventors (experience talking)

Seeing the prior-art (Peter Parker’s / Rover patent, granted some 25years ago) it is hard to find an “inventive step” in Hyundai’s US patents over Parker’s patent.

Here is the Rover VVC:



Here is a drawing from the last US patent granted to Hyundai (as the assignee) :



Spot on the 62 and 82 parts.

And here they are shown their differences:



The red part is the 62, the yellow part is the 82.

The pin of Rover VVC has been moved outside, the slot of the Rover VVC has been moved inside.
What a breakthrough!... What a disruptive technology, indeed…


But even Rover’s patent was not new: a guy named Mitchell had invented / proposed / patented the mechanism some 50 years ago:

Quote from http://www.sandsmuseum.com/cars/elise/t ... e/vvc2.pdf

Rover VVC:

The basic concept was developed by a mr. Mitchell and it was published and patented back in 1973. However no one used it and it was forgotten until Rover re-discovered it. In 1989 Rover began experimenting with the system and in 1993 had developed a 1.4 litre version with VVC.
. . .
At this moment (Jan 2001) Rover is the only one who has a mass production engine with a variable duration of the camshaft. A bigger duration has more effect on power than opening and closing the valve later as with cam phasing systems. The Rover system is without a doubt far superior to all the cam phasing systems. It would be possible to incorporate a cam lobe switching mechanism to switch to a higher lift cam lobe as with Honda's VTEC. This would give the Rover engine the best of all worlds.

End of Quote


To put in production an expired patent is legitimate (is according the law).

But to claim (and advertise all over the world, and be proud) that you have invented the invention an independent inventor (a poor human being) had patented some 50 years ago. . .

Thanks
Manolis Pattakos

[manolis]

Hello Gruntguru

You write:
Hyundai has pretty much copied it and somehow managed to get a patent issued.

Not "a patent".
Seven patents granted already, only in the USA.
Calculate how many worldwide.
I can't help thinking of the maintenance fees.


"managed": that's THE word.

Thanks
Manolis Pattakos

[Tommy Cookers]

for a good read try this ....
http://enginehistory.org/Piston/WW2Drone/WW2Drone1.html

McCulloch made many of these engines (then Righter designed drone aircraft 4 cylinder engines for McCulloch)
as I said before - could there have been a WW2-era Personal Flyer ?

[manolis]

for a good read try this ....
http://enginehistory.org/Piston/WW2Drone/WW2Drone1.html

McCulloch made many of these engines (then Righter designed drone aircraft 4 cylinder engines for McCulloch)
as I said before - could there have been a WW2-era Personal Flyer ?

Hello Tommy Cookers

The link returns an error.

The correct link is http://enginehistory.org/Piston/WW2Dron ... one1.shtml


*****************


A useful technical article, full of data. Thanks Tommy Cookers.



Thanks
Manolis Pattakos

[manolis]

Hello all.

The following animation, added to the patVVD web page at https://www.pattakon.com/pattakonVVD.htm , may be useful in understanding the patVVD mechanism



The control lever (cyan) is displaced at six different angles about the camshaft rotation axis.
Each angle of the control lever defines a different "valve lift profile" the valves have to follow during the rotation of the sprocket:

At https://www.pattakon.com/VVD/PatVVD_Con ... r_slow.gif is the above animation at slow motion.


Here the sprocket rotates with the control lever (cyan) immovable:



At https://www.pattakon.com/VVD/PatVVD_Run_slow.gif is the above animation at slow motion.

Thanks
Manolis Pattakos

[PlatinumZealot]

Yes eg 1.8 VVC 1995. https://www.youtube.com/watch?v=mKlB8zDI3PA

Hyundai has pretty much copied it and somehow managed to get a patent issued.

Ok. Having seen the Hyndai video some time ago and now this one. There are some mechanical differences in the layouts between them though the maths is the same. The Hyundai a bit more refined, though needs a talker valve cover. And it lends it self more easily to VVT since the mechanism is not where the cam gear is.

[gruntguru]

The Hyundai system. . . . . lends it self more easily to VVT since the mechanism is not where the cam gear is.

The mechanism doesn't need to be there, if you look at this image from the previous page . .

[manolis]

Hello PlatinumZealot

You write:
"Ok. Having seen the Hyndai video some time ago and now this one. There are some mechanical differences in the layouts between them though the maths is the same. The Hyundai a bit more refined, though needs a talker valve cover. And it lends it self more easily to VVT since the mechanism is not where the cam gear is."


Let me show some differences and characteristics of each solution.

Here:





they are shown the parts required for the CVVD of Hyundai, also their relative dimensions.

The part 102 is a “crankshaft” (a shaft having eccentric pins) rotatably mounted on its “own” series of bearings on the cylinder head. Each eccentric pin of this “crankshaft” forms a “scotch yoke” with its respective “frame” 90.

Inside the frame 90 it is a needle roller bearing of big diameter (some 3.5 times larger than the diameter of the shaft whereon the cams are pivotally mounted).


Why Hyundai and Rover need the big diameter needle roller bearing?


Here is a photo of the Rover VVC mechanism:



The black arrow at right is the force applied by the right pin/rectangle (i.e. the drive shaft) to the intermediate “disk”.
The green arrow at left is the reaction force from the respective cam (i.e. the driven shaft) to the intermediate “disk”.
The red arrow is the total force loading the bearing through which the intermediate “disk” is rotatably mounted on the eccentric control ring (that with the teeths at a portion of its periphery).
The total force (red) is about twice as strong as the driving force (black) and acts on a big diameter bearing; these make a “needle roller bearing” obligatory.


Here is a drawing of the PatVVD:



The red arrow represents the total force; the total force is substantially smaller than the “driving” force (black).

The diameter of the bearing (external diameter of the yellow “control” pin) whereon the total force acts is substantially smaller (say, two times the cam shaft diameter).

After 180 degrees of rotation of the “cam shaft” (Fig 14), the wider angle between the cyan and the gray links / rods reduces substantially the total force on the bearing.

According the previous the use of a needle roller bearing is not necessary / mandatory / useful.

The mechanism of the PatVVD is more compact, more robust, more efficient (reduced friction loss and wear) and simpler / cheaper than Hyundai’s CVVD and Rover’s VVC .


One more thing: the “eccentricity” of the control pin of the PatVVD can be substantially larger than the “eccentricity” in the Rover VVC and in the Hyundai CVVD (the h1 and h2 in the Fig. 5 ofHyundai).

This allows a smaller rotation of the control pin (or control lever).

For instance, each of the following sets of valve lift profiles corresponds to 60 degrees of control lever rotation:



For applications without a VVT (like, say, high revving motorcycle engines, like cheap engines etc), the right choice of the region of the rotation angle of the control pin (or control lever) compensates the lack of a VVT (variableValve Timing).

Thanks
Manolis Pattakos

[PlatinumZealot]

Likely the Hynadia design is easier to assemble on a factory line? Something automakers really have to consider.

I am also looking at the green linkage in your design.. The driving linkage... Can this and its pins take the force of the valve springs at high rpms?

[manolis]

Hello PlatinumZealot

You write:
"Likely the Hynadia design is easier to assemble on a factory line? Something automakers really have to consider."


The simplest case is to apply the system on a single cylinder (or boxer twin, or Vee twin).

In the case of the PatVVD:



the eccentric control pin (which is integral with the control lever, both cyan) is directly supported on the camshaft (beige), with the three links (or connecting rods; red, green and blue) of the mechanism being directly supported on the camshaft (beige), sprocket (gray) and control pin (cyan).

**** EDIT : image added



**** EDIT

Count how many more parts (and “accurate” support points) are required for replacing the above patVVD by a Hyundai CVVD.


Things are similar for in-line multicylinder engines.

For the support of the mechanism on a cylinder head the PatVVD does not require bearings other than a set of coaxial bearings as those supporting a conventional camshaft on a cylinder head; it also does not require additional structure(s) to bear and displace the control parts.

Here they are shown the parts (and their assembly) of the PatVVD for a straight four-cylinder engine:







After the assembly of the camshaft, the complete set is mounted on the cylinder head as a conventional camshaft.

Compare to the assembly of Hyundai’s CVVD: the substantially simpler patVVD is also substantially easier to assemble.



You also write:
"I am also looking at the green linkage in your design.. The driving linkage... Can this and its pins take the force of the valve springs at high rpms?"

The mechanism of the patVVD (links and pins) “deals” with a few dozens of kilograms of loads.

The “same” mechanism is used in the patVRA apparatus:



for the reduction of vibrations transmitted from the engine to the gearbox / vehicle (more at https://www.pattakon.com/pattakonVRA.htm ).

In the PatVRA case, all the power of the engine passes through the mechanism (links and pins) to the gearbox, loading the mechanism not with a few dozens of kilograms, but with a few thousands of kilograms.

While the pins and links (connecting rods) of the patVVD can substantially increase in size, this doesn’t seem necessary.
The mechanism as shown is stronger than what high rpm operation requires.

Thanks
Manolis Pattakos

[PlatinumZealot]

OK Manolis.. I see.. I also have a question about the little arm beside the cam lobes. That peice may have to be separately manufactured, and pressed on. Not a big deal.Nevertheless, my regards for doing your own take on this concept.

This article explains how Hyundai has gotten away with their claim to be the first...Sly marketing by use of word tricks is how.

https://www.autoweek.com/car-life/but-w ... -duration/

They correctly claimed to build the world’s first mass-production engine with both continuously variable valve duration and timing

Whenever you guys are ready to get back to the portable flyer, I will be too. It is still unresolved.

[J.A.W.]

Hyundai's '1st with mass-produced variable timing/lift' claim - amounts to marketing hype,
(unless more 'qualifiers' keep on being added), as Yamaha has a prior claim - via its YPVS, too.

Topically, its a 2T engine, yet YPVS did use a electro-mechanical system to effect a
'variable timing/lift' valve set-up, & Yamaha did put it into mass production, decades ago: