Author Topic: Junkers CLM  (Read 941 times)

Online Roger B

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Re: Junkers CLM
« Reply #15 on: December 24, 2018, 09:14:46 AM »
I have given this a bit more thought. The basic dimensions will be taken fron my horizontal diesel, the short connecting rod will be identical but the long pull rods are in tension so all the firing load is on the big end bolts. I did some stress calculations for the horizontal engine which gave a good safety margin with M3 bolts but I think these will have to be increased to M4. As the stroke is shorter the additional width of the bearing won't require a bigger crankcase. As the rods are in tension buckling won't be a problem so I think they can be reduced to 8mm diameter. The big ends will be reduced to 10mm wide to keep the crankshaft as short as possible.
I had a dig through my material stocks and have a cylinder block, cylinder liner, crankshaft and pistons.
Best regards

Roger

Offline Rustkolector

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Re: Junkers CLM
« Reply #16 on: December 26, 2018, 05:59:38 PM »
Roger,
Here is another OP diesel engine design from Achates Power currently in a joint research project with Cummins Engine Co. for development of combat vehicle engines for the US Army. It is a compact engine following more contemporary engine package design features. It does use a blower for scavenging which might complicate a smaller model engine design. Watch their video.
Jeff

http://achatespower.com/our-formula/opposed-piston/

Online Roger B

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Re: Junkers CLM
« Reply #17 on: January 13, 2019, 05:35:43 PM »
Thank you Jeff  :ThumbsUp:  There seem to have been many attempts at opposed piston engines but they have only been successful in larger sizes  :(

I am slowly working through the design. I now understand the square scavenge piston  :) It is so the ends of the pull rods for the top piston can go into the scavenge cylinder and reduce the height of the engine (and the piston).

The next step is to work out a governor design. It is mounted on a vertical shaft in the front part of the crankcase driven by a pair of helical gears. The principle is similar to the one I was experimenting with for the horizontal diesel:

http://www.modelenginemaker.com/index.php/topic,5545.195.html

In this case the bottom plate is mounted on a bearing and the balls are driven by a spider keyed to the shaft. A PDF of the principle is attached. I think I will have to make a trial version. The shaft is 6mm diameter and the overall diameter is 32mm with 6 6mm diameter balls.
Best regards

Roger