Author Topic: Atkinson Differential Engine  (Read 7364 times)

Offline Dave Otto

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Atkinson Differential Engine
« on: November 06, 2017, 01:01:42 AM »
Here is my buddy Max's latest project, he still needs to build the display base but he does have it running nicely!
And he said this thing will never run!  :lolb:

<a href="https://www.youtube.com/watch?v=ZZbaF23NmsM" target="_blank">http://www.youtube.com/watch?v=ZZbaF23NmsM</a>

Dave
« Last Edit: November 06, 2017, 01:05:13 AM by Dave Otto »

Online crueby

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Re: Atkinson Differential Engine
« Reply #1 on: November 06, 2017, 01:17:37 AM »
Fascinating motion, and a wonderful sound!

Offline b.lindsey

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Re: Atkinson Differential Engine
« Reply #2 on: November 06, 2017, 12:27:28 PM »
Dave, does Max have any detail pictures of the links to the crankshaft. Would love to see those if possible. Lovely engine though and is running beautifully!!!

Bill

Online Kim

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Re: Atkinson Differential Engine
« Reply #3 on: November 06, 2017, 04:21:44 PM »
That is quite mesmerizing to watch.  The motion is fascinating!
Kim

Offline Roger B

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Re: Atkinson Differential Engine
« Reply #4 on: November 06, 2017, 05:59:12 PM »
Splendid  :praise2:  :praise2:

There have been a number of ways to meet Atkinsons criteria that the expansion (firing) stroke must be longer than the compression stroke. There was one in one of the German magazines using a single cylinder and a sort of modified Watt's parallel motion. Mazda cheat and just keep the inlet valve open after TDC  ::)
Best regards

Roger

Offline Dave Otto

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Re: Atkinson Differential Engine
« Reply #5 on: November 07, 2017, 01:16:31 AM »
Thanks Guys

Bill here are a couple pictures that I had, I will ask Max if he has a better picture of the crankshaft end. In one of the pictures you can see the link from the crank throw to the linkage arm.
This is a strange beast, it has poppet valves on both the intake and exhaust and neither one are operated mechanically.  The intake like on a lot of early engines is operated by vacuum; the exhaust is operated by pressure after the piston uncovers the port in the cylinder.

Dave

Offline b.lindsey

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Re: Atkinson Differential Engine
« Reply #6 on: November 07, 2017, 01:53:33 AM »
Thanks Dave. Great pictures and some very fine machine work too obviously!!

Bill

Offline Noitoen

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Re: Atkinson Differential Engine
« Reply #7 on: November 07, 2017, 03:08:09 PM »
Splendid  :praise2:  :praise2:

There have been a number of ways to meet Atkinsons criteria that the expansion (firing) stroke must be longer than the compression stroke. There was one in one of the German magazines using a single cylinder and a sort of modified Watt's parallel motion. Mazda cheat and just keep the inlet valve open after TDC  ::)

Toyota Prius engine is also a Atkinson cycle engine. The engine's crank center line is a little offset from the cylinders and due to this, the stroke lengths are different.

Offline tvoght

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Re: Atkinson Differential Engine
« Reply #8 on: November 07, 2017, 03:57:52 PM »

... The engine's crank center line is a little offset from the cylinders...

Known as "desaxe". This wikipedia article says that Ford's flathead V8s had such an offset configuration, though I assume not Atkinson cycle.

https://en.wikipedia.org/wiki/Desaxe

--Tim

Offline Dave Otto

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Re: Atkinson Differential Engine
« Reply #9 on: November 07, 2017, 04:32:14 PM »
My understanding of the Atkinson cycle is that all 4 cycles need to take place in one revolution of the crankshaft. I think these auto manufactures are just using the name to make people think think they have come up with a new and better product. I'm probably wrong but just my thoughts.

Dave

Online Jasonb

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Re: Atkinson Differential Engine
« Reply #10 on: November 07, 2017, 07:07:25 PM »
Another nice engine from Max, did he use the castings from David Perreault?

Offline Dave Otto

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Re: Atkinson Differential Engine
« Reply #11 on: November 08, 2017, 01:21:18 AM »
Thanks Jason

Yes, I believe that is who he purchased the castings from.

Bill here is a picture that shows the interesting links a little better.


Dave

Offline Art K

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Re: Atkinson Differential Engine
« Reply #12 on: November 08, 2017, 03:42:24 AM »
Dave,
I think that is one of the casting sets I will have to acquire at some point in the future when I'm more affluent. As my understanding is, You are right that the Atkinson stroke has all four strokes in one revolution. You must remember that engineers were twisting their brains into pretzels to beat Otto's copyrights on the four stroke engine. Atkinson's engines were quite efficient as I understand. But the the modern engines are really only trying to get the same effect as the Atkinson stroke within the constraints of their present engines, by the same tactic, engineering.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Dave Otto

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Re: Atkinson Differential Engine
« Reply #13 on: November 19, 2017, 05:21:35 PM »
Here is a short video of the completed engine.
Also attached is a picture of the S&S ignition and battery back located in the base.

Dave


<a href="https://www.youtube.com/watch?v=sIJUGEQJlhU" target="_blank">http://www.youtube.com/watch?v=sIJUGEQJlhU</a>
« Last Edit: November 19, 2017, 05:27:18 PM by Dave Otto »

Offline Don1966

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Re: Atkinson Differential Engine
« Reply #14 on: November 19, 2017, 07:58:45 PM »
That’s awesome Dave, Max does some superb work and nice runner.

Don

 

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