Author Topic: Gamma1-VPA Stirling  (Read 12625 times)

Offline tvoght

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Re: Gamma1-VPA Stirling
« Reply #45 on: September 06, 2014, 02:43:04 PM »
Hi Ian,
  I'm glad you asked, that's something I wanted to point out.

 Whereas most Gamma Stirlings would have crank pins 90 degrees apart, mine are just 41 degrees apart. The angle between the displacer and piston is added to the 41  to make the entire displacer lead angle. In other words, to get the tradiitional 90 degree displacer phase lead, the angle between piston and displacer would be just: (90 - 41) = 49 degrees. I did that so that the tube between would not have to be
so long which would have added to the dead volume in the engine.

Oh yes, as you suggested, there is a slightly longer stroke on the displacer pin to help make the difference in swept volume ratios.

Make sense?

--Tim

Offline Ian S C

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  • Stirling Engine Maker Darfield Canterbury N Z
Re: Gamma1-VPA Stirling
« Reply #46 on: September 07, 2014, 09:58:09 AM »
Tim, that explains the angle of the power cylinder in the video, thank you.  My thing is that I do minimum maths on the build of my motors, so I haven't tried any thing fancy yet, I'v built one GAMMA motor with parallel cylinders, a bell crank, and single crank pin.
                                                           Ian S C
« Last Edit: September 07, 2014, 10:42:32 AM by Ian S C »

Offline tvoght

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Re: Gamma1-VPA Stirling
« Reply #47 on: September 09, 2014, 11:00:43 PM »
It seems I've run out of build photographs and yet the flow of the narrative seems quite incomplete. I'll attempt to provide closure by offering this rather
grungy video showing the engine first partially disassembled, followed by a re-assembly. At the end, there's a short and slightly more graphical description of what I was trying to explain to Ian about how the Variable Phase Angle feature is accomplished.

Sorry in advance for the quality of the video.

<a href="http://www.youtube.com/watch?v=bm25oCfxbEA" target="_blank">http://www.youtube.com/watch?v=bm25oCfxbEA</a>

Thanks,

--Tim