Brian builds Atkinson Engine

[Brian Rupnow]

Today I received a complete set of drawings to build an Atkinson 4 cycle engine from Jan Ridders, in the Netherlands. Jan sells these plans for a very reasonable "donation" of 5 to 10 Euros (About $6 to $12 Canadian.) I have looked through the plans, and they seem very complete and well documented. Also included with the engine plans is a set of plans for an atmospheric carburetor. The plans are in metric, so I will model them all in Solidworks as metric parts and then use some of the computer magic inherent in Solidworks to print out drawings with the dimensions in British Imperial (Which I am far more comfortable with when working in my machine shop). I will be changing fastener sizes and shaft sizes to Imperial as I do up the models. I will post the 3D models along with step by step pics of the actual build procedures as I go along, however I will not be posting detail drawings, as that would be very unfair to Jan. This is a rather amazing engine, as it accomplishes all four cycles--Intake, compression, power, and exhaust with one revolution of the crankshaft!!! This will be my third I.C. engine. as I have previously built the Kerzel hit and miss engine and everyones favourite, the Webster. Follow along---This probably won't be a quick build, but it should be a fun build.----Brian

 

[Brian Rupnow]

Well, here's a beginning. The first thing I notice is that Jan used a 24mm bore, and I only have a 7/8" (22.22mm) reamer. Since I have more faith in my ability to get a good consistent reamed finish than a good consistent bored finish, I THINK I will design this with a 7/8" bore. Jan calls up grey pearlitic cast iron for the cylinder, and since I haven't worked with that before, I may try and use it, depending on cost.

 

[Don1966]

Well, Brian you have me interested. I had been reading about the Atkinson for a while on Gentry's web sight. So I will be following you on your journey. Most of the engines I have seen are scale rather large, has any one scaled to a 6" version yet? If not I would be interested in doing it.

Don

 

[Brian Rupnow]

As I get a bit deeper into this, I see that his engine is designed with valve cages, rather than having the valve seats directly into the cylinder head. For my opinion, thats a GOOD thing. I also note with some interest that he doesn't show any piston rings. I may add a Viton o-ring, I'm not sure yet. As far as scaling things up to a much larger size as is suggested by Don, I can't imagine why anyone would want to do that. This forum is "home MODEL engine machinist". If I wanted a full scale engine to do some kind of work, I would buy one. None of my machinery is large enough to even consider a "full size" engine build.

 

[vcutajar]

Brian

I will be here following your build. It looks like it is going to be an interesting build.

Vince

 

[AlanHaisley]

Brian,

This should be fun. The Atkinson is a really curious engine. Looking up the explanation of why it was invented was quite interesting. ;D

Alan

 

[Don1966]

Brian I wasn't indicating to build a full size engine sorry if you misunderstood . I am looking to scale a 6" tall engine. I should of been more specific. My apology.

Don

 

[Brian Rupnow]

Sorry Don, I misunderstood you. I have two i.c. engines that are both about 4" tall, my Webster and my Kerzel. This engine is a tall one, measuring about 8 3/4" tall from the underside of the metal base to the top of the flywheel. The flywheel is 6" diameter, so it is 5 3/4" high to the center of the crankshaft.--

 

[Brian Rupnow]

Brian,

This should be fun. The Atkinson is a really curious engine. Looking up the explanation of why it was invented was quite interesting. ;D

Alan

Alan---Wasn't it to get around the Otto 4 cycle patent?

 

[b.lindsey]

Should be a fun one to watch Brian...drawings look great so far.

Bill

 

[AlanHaisley]

Alan---Wasn't it to get around the Otto 4 cycle patent?

Yep, apparently Otto patented everything he could think of about his design. Kinda sounds like early steam engine goings-on.

 

[ShedBoy]

Looking forward to this build Brian. Always liked the look of these engines and fascinating to watch.

Brock

 

[Captain Jerry]

Yep, apparently Otto patented everything he could think of about his design. Kinda sounds like early steam engine goings-on.

Sounds like it. Watt and Boulton had to come up with an alternative to the crank for which the patent was owned by someone else. Their solution led to the development of planetary gearing which is a development of huge importance and which also had no detrimental effect on their steam engine.

I'm not sure what particular feature of Otto's patents that Atkinson was trying to circumvent. My guess is that it had something to do with timing gears but I don't know (citation needed here). In any case, while it is very entertaining to watch, and was effective in beating the patent, it does not seem to have any engineering benefit. It is difficult or impossible to balance and because of that, limited to slow speed operation. The principle of its operation seems to be what is known as a "four bar link" mechanism, which has many uses and is found in many forms, but I doubt that this is the first use of a "four bar link".

It just occurred to me that Atkinson's original engine did not have a separate cam shaft but had cams on the crankshaft with very long push rods. It may be that Otto's patent covered the separate camshaft.

Jerry

Believe me, I am a great fan of "WTF" engineering, and I will be following this build to the end. I am sure it will be entertaining and it's completion will be well worth the trip.

 

[Brian Rupnow]

Well There!!! Thats enough modelling for one day (As if I didn't get enough of this through the week!!!!) This is a very interesting engine.

 

[rebush]

Brian: I've always been fascinated by Atkinson's Cycle and Differential engines. Should be a very interesting build. You have my full attention. Roger

 

[doc1955]

Well There!!! Thats enough modelling for one day (As if I didn't get enough of this through the week!!!!) This is a very interesting engine.

Yes I like that each stroke is a different length your model looks good. I know what you mean when you say don't I get enough of this during the week :big: :big: I have found myself doing the same I like to model things up and check fits and make mods before building as I suspect you do the same. Gives you a good feel for what you are building before you actually make chips.
Looks good so far Brian good job!

 

[Tin Falcon]

Brian cast iron is easy to machine but tends to be dirty . recomendened coolant dry air. so keep the shop vac handy.
Tin

 

[swilliams]

This is a cool project Brian, I'm following along

Steve

 

[cfellows]

Speaking of scaling engines up, here's a video of an Atkinson engine supersized by Tom T a while back. Kind of scary to watch it run...

http://media.photobucket.com/video/atkinson%20engine/csguinn/100_1547.mp4?o=3

Chuck

 

[Brian Rupnow]

Here we have it guys. About 8 to 10 hours modelling yeilds this. My software tells me that there are a total of 65 parts, not counting fasteners, of course. The sparkplug is not modelled and the pushrod which either presses on a piezzo electric crystal or opens a set of ignition points is not yet modelled either.