Dieter Hartmann-Wirthwein patent engine

[GailinNM]

With Brian's Different Opposed piston engine in Junior form winding down it is time to do some serious thinking about the next build - or not.

A few years ago there was a flurry of interest about the Ducati Elenore V8/lnline 4 patent drawing that was released.  To my knowledge there were only two prototypes built. One a V8 of about 860 cc displacement and one an In-line 4 of 125 cc displacement.  Both were installed  in motorcycles and there are a few Youtube videos of them running.  I don't know of any models being built.

I have found very little information on the engines.  One page of the patent and the video model that I have attached to this post.  A few general specifications and a few photos of the engines external appearance.  Most everything else links back to these sources.  A couple of little discussions on HMEM a few years ago went nowhere. I would welcome any additional information on these engines as I am far from being a master at searching the internet.

What I am thinking of doing is building a 45 degree slant 4 in line demonstration engine with an open crankcase so the motion can be seen.  Design would be so everything could be mirrored and a second set of parts built that could convert it to a V8 if the inline 4 is successful. Only two parts should be troublesome.  The forked main connecting rod and the piston with two intersecting orthogonal wrist pins.  The wrist pins had me stumped for a while but I now think I have a way that will work.  Everything else is standard design stuff.

All comments are welcome. I have not detailed out any parts yet.  Just a few (bunch) of sketches.
Gail in NM

<a href="https://www.youtube.com/watch?v=7E6KglXPmTs" target="_blank">http://www.youtube.com/watch?v=7E6KglXPmTs</a>

[Brian Rupnow]

My Goodness Gail--You are a bear for punishment!!! That looks absolutely fascinating. I remember that engine being discussed a while ago, but never paid it much attention. I will definitely be following to see what comes of this.---Brian

[IanR]

An interesting idea. I'm not a master of internet searching either, but from what I can see from a quick look, this is the invention of an ingenious German to fit into a Ducati  frame and V twin crankcases, rather than a project from the factory. His website is here
http://www.wirthwein-motor.de/?page_id=59

won't you need several ball joints to cope with the varying angles between middle and outer pistons, and have to squeeze 2 conn-rods into each middle piston? A pig to make at full size, and entertainingly fiddly as a model, I'd have thought.

[smfr]

That looks fascinating! I suppose with that arrangement of 4 cylinders, there's no reason for the cylinders to be in a line; you could have a 2x2 arrangement if the connecting linkages work out.

The cylinders are timed in pairs, so I guess the 4 cylinder version would act more like a 2 cylinder engine?

Simon

[GailinNM]

Brian - not punishment ; fun!  If we don't push ourselves we never know what we can do.  Besides you and I both like the unusual.

Ian, Near as I can tell he was responsible for the prototypes that were built and the patent was assigned to or funded by Ducati.  No ball joints are needed with the intersecting orthogonal wrist pins.  It does take a bunch of small sub connecting rods to balance the load. Eight of them on the I4 engine.  So the center pistons each have 4 rods in them.  But my sketches show it can be done as the sub rods can be small as they divide the load and have small angularity problems.

Simon,  It is a 4 stroke engine so there is a power stroke every 180 degrees on the I4, just like a conventional  I4 engine. I did not try anything for a 2X2 design but I can not see any way for it to be done.

Gail in NM

[gerritv]

A link to the patent, it explains the mechanism: http://www.google.com/patents/DE102008047719A1?cl=en
This design is almost as fascinating as the BRM H 16

Gerrit

[b.lindsey]

Another fascinating build on the drawing board...I admire your creativity and tenacity both Gail. Looking forward to seeing more.

Bill

[GailinNM]

Thanks Gerrit,
I had not found that patent link.  By following the link to the final grant link I found another drawing of the piston.  It is the same as what I had deduced.  I think I have a way to make it work in model size.  These forums are wonderful to as more talented people are so willing to help in situations like these.

From reading the details in the patent it is obvious that Ducati had nothing or very little to do with the engine design as I was  lead to believe from my searching.  Therefore I have renamed the title of this thread to give credit where it is due.
Gail in NM

[zeeprogrammer]

A most interesting project. It will be fascinating to follow along.

[Tennessee Whiskey]

Bottom end looks real doable. Cam and valve train could get interesting.

Whiskey

[Johnmcc69]

No slowing you down Gail, is there.
what an interesting design, I love the Ducatis, their engineering efforts
are quite interesting. I can't wait to see this progress. No doubt in my
mind that you can pull this off...

 John

[Alan Haisley]

This will be fun to follow. It must be different in some way from a two cylinder engine with the same throw but with pistons with twice the area but It's not obvious just how alike or different it will turn out (other than the linkages that is.)

Alan

[GailinNM]

Except for the different linkage arrangement  operation is identical to a conventional 4 cylinder inline 4 stroke engine.
In the diagrams below on the conventional 4 cylinder the two center throws (Cylinder 2 and 3) are replaced with the forked main connecting rod on a single crank pin. Same action.  Cylinders 1 and 4 are driven by the bell cranks from Cyl 2 &3 instead of the outside throws of a crank shaft. Again it is the same action.  So is is a conventional inline 4 with just a different way of driving the pistons to accomplish the same thing.

[GailinNM]

Here is a general sketch of things.  I have started drawing things up a bit so I can build a dummy mock up of the action. l Everything is scaled for an engine with a 1/2 inch bore by 3/8 stroke.  This is quite a bit over square and new territory for me.  All the engines I have built in the past have had square ratios or been under square.  But it is a balancing act on this engine.  As the bore increases it gets harder to get the cylinders close together and have enough cooling fin area. I could make it liquid cooled but I really don't want to.   If I use a small bore and larger stroke the angularity problems with the linkages increase and I run out of room inside the piston for all the goodies. This seems like a good compromise.

First up on the mock up parts will be the forked connecting rod. I need it to check clearances and I think it will be the most difficult part to make.

I will make it out of 6061 aluminum but the actual engine connecting rod will be made of 7075 T6 for the additional strength in the thin sections. The work is not lost in making the mock up parts as if it is successful I can use the fixtures to make it to make the working parts.

No shop time tomorrow so it will have to wait until the weekend.  I will post photos as I go.
Gail in NM

[AussieJimG]

Please let me come along for the journey again. I woke each morning eagerly looking forward to seeing what you had done the previous (our) night and was never disappointed.

This one promises to be even better.

Jim